Title: Kidney injury-related molecules
United States Patent: 6,664,385
Issued: December 16, 2003
Inventors: Sanicola-Nadel; Michele (Winchester, MA); Bonventre; Joseph V. (Wayland, MA); Hession; Catherine (Hingham, MA); Ichimura; Takaharu (South Burlington, VT); Wei; Henry (Ossining, NY); Cate; Richard L. (Weston, MA)
Assignee: Biogen, Inc. (Cambridge, MA)
Appl. No.: 197970
Filed: November 23, 1998
Proteins which are upregulated in injured or regenerating tissues, as well as the DNA encoding these proteins, are disclosed, as well as therapeutic compositions and methods of treatment encompassing these compounds.
SUMMARY OF THE INVENTION
The invention generally provides Kidney Injury-related Molecules (each of which is henceforth called a "KIM") which are upregulated in renal tissue after injury to the kidney. The KIM proteins and peptides of the invention, as well as their agonists and antagonists, and their corresponding nucleic acids are useful in a variety of therapeutic interventions.
The invention provides a purified and isolated DNA molecule having a nucleotide sequence set forth in SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6. The invention also includes the complementary strands of these sequences, DNA molecules which hybridize under stringent conditions to the aforementioned DNA molecules, and DNA molecules which, but for the degeneracy of the genetic code, would hybridize to any of the DNA molecules defined above. These DNA molecules may be recombinant, and may be operably linked to an expression control sequence.
The invention further provides a vector comprising a purified and isolated DNA molecule having a nucleotide sequence set forth in SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6, or one of the other DNA molecules defined above. This vector may be a biologically functional plasmid or viral DNA vector. One embodiment of the invention provides a prokaryotic or eukaryotic host cell stably transformed or transfected by a vector comprising a DNA molecule of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6. In another embodiment of the invention, a process is provided for the production of a KIM polypeptide product encoded by a DNA molecule as described above; the process involves growing, under suitable culture conditions, prokaryotic or eukaryotic host cells transformed or transfected with the DNA molecule in a manner allowing expression of the DNA molecule, and recovering the polypeptide product of said expression.
A purified and isolated human KIM protein substantially free of other human proteins is specifically within the invention, as is a process for the production of a polypeptide product having part or all of the primary structural conformation and the biological activity of a KIM protein. KIM proteins of the invention may have an amino acid sequence which comprises SEQ ID NO:3, SEQ ID NO:5, or SEQ ID NO:7, or may be, a variant of SEQ ID NO:3, SEQ ID NO:5 or SEQ ID NO:7, or a purified and isolated protein encoded by the DNA of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6. These proteins can be provided substantially free of other human proteins. The invention further includes variants of these proteins, such as soluble variants or fusion proteins. KIM fusion proteins of the invention may comprise an immunoglobulin, a toxin, an imageable compound or a radionuclide.
The invention also provides a specific antibody, such as a monoclonal antibody (MAb), to the KIM proteins described above. The present antibody binds to any epitope that is unique to a KIM protein disclosed herein. In some embodiments, the epitope is displayed on the surface of a cell expressing KIM. Antigen-binding fragments of the antibody are also provided herein, preferably Fab, Fab2, Fab' and Fv fragments, whether produced by chemical or enzymatic cleavage, or by molecular engineering techniques. Engineered versions of the present antibody include chimeric, humanized and human antibodies, and antibody fusion proteins. Monoclonal antibodies (MAbs) of the present invention can be of mouse, rat, hamster or human origin. An exemplary MAb of the invention is the murine AKG7 MAb disclosed herein, which binds specifically to the human KIM polypeptide disclosed herein. Anti-KIM antibodies of the present invention may be conjugated or fused to a therapeutic agent, toxin, imageable compound or radionuclide. Exemplary therapeutic agents include cytokines, lymphokines, trophic factors, survival factors, chemokines and chemoattractants. Exemplary toxins include ricin and diphtheria toxin. Exemplary imageable compounds include luminescent proteins (e.g., luciferin), fluorescent proteins (e.g., green fluorescent protein), haptens (e.g., biotin), and radioactively labeled proteins. Exemplary radionuclides include any radionuclide used for medical imaging purposes. The invention further encompasses all hybridoma cell lines and engineered host cells which produce antibodies of the invention.
Pharmaceutical compositions are also within the scope of the invention. A pharmaceutical composition of the invention may comprise a therapeutically effective amount of a KIM protein or anti-KIM antibody of the invention, along with a pharmacologically acceptable carrier.
Diagnostic methods are within the invention, such as assessing the presence or course of resolution of renal injury by measuring the concentration of KIM in urine, serum, or urine sediment of patients who have or who are at risk of developing renal disease. Other diagnostic methods that are within the invention include assessing KIM expression level in kidney tissue (e.g., in kidney biopsy tissue) of patients who have, are suspected of having, or are at risk of developing renal cancer (e.g., renal carcinoma). The present methods involve contacting an appropriate tissue or fluid sample derived from the patient being diagnosed, with a KIM antibody or a KIM probe (as the case may be), under binding conditions. Complexes formed by the binding of antibody or probe to KIM protein or nucleic acid (e.g., RNA) in the sample are detected by standard techniques. The presence or abnormal elevation of KIM protein in urine or serum is expected to correlate with renal failure or renal disease. The presence or abnormal elevation of KIM gene expression in renal cells or tissue is expected to correlate with disease processes, particularly carcinogenesis. Such correlations are expected to be useful in the prognostication, staging and clinical management of diseases or other conditions deleterious to renal tissue and/or renal function.
Methods of treatment of the invention include treating patients with therapeutically; effective amounts of KIM, KIM variants, KIM analogs, KIM fusion proteins, KIM agonists, and antibodies to KIM or to KIM ligands. Other therapeutic compounds of the invention include KIM ligands, anti-KIM antibodies, and fusions proteins of KIM ligands. These compounds can be useful in therapeutic methods which either stimulate or inhibit cellular responses that are dependent on KIM function.
Further methods of the invention inhibit the growth of KIM-expressing tumor cells by contacting the cells with a fusion protein of a KIM ligand and either a toxin or radionuclide, or with an anti-KIM antibody conjugated to a toxin or to a radionuclide. Likewise, growth of tumor cells which express KIM ligand may be inhibited by contacting the cells with a fusion protein of a KIM and either a toxin or radionuclide, or with an anti-KIM ligand antibody conjugated to a toxin or to a radionuclide.
The invention also encompasses methods of gene therapy. These include a method of treating a subject with a renal disorder, a method of promoting growth of new tissue in a subject, and a method of promoting survival of damaged tissue in a subject, wherein each method comprises administering to the subject a vector which includes DNA comprising the nucleotide sequence of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6.
The compounds of the invention are also useful for imaging tissues, either in vitro or in vivo. One such method involves targeting an imageable compound to a cell expressing a protein of SEQ ID NO:3, SEQ ID NO:5 or SEQ ID NO:7, comprising contacting the cell with either a monoclonal antibody of the invention or a fusion protein comprising a protein as described above, fused to an imageable compound. For in vivo methods, the cell is within a subject, and the protein or the monoclonal antibody is administered to the subject.
The invention also includes diagnostic methods, such as a method of identifying damage or regeneration of renal cells in a subject, comprising comparing the level of expression of either SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6 in renal cells of the subject to a control level of expression of the sequence in control renal cells. Another method of the invention includes identifying upregulation of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6 in cells comprising contacting the cells with an antisense probe and measuring hybridization to RNA within the cell.
A further embodiment of the diagnostic methods of the invention includes assessing the presence or concentration of a molecule of the invention either in urine, serum, or other body fluids, or in urine sediment or tissue samples. The measured injury-related molecule can be correlated with the presence, extent or course of a pathologic process. This correlation can also be used to assess the efficacy of a therapeutic regime.
DETAILED DESCRIPTION OF THE INVENTION
KIM genes were identified by analyzing differences in mRNA expression between regenerating and normal kidneys using representational difference analysis (RDA). RDA is a PCR-based method for subtraction which yields target tissue or cell-specific cDNA fragments by repetitive subtraction and amplification. The cDNA representation from 48 hr postischemic adult rat kidney RNA is subtracted with the sample from normal (sham-operated) adult rat kidney. In this procedure, sequences which are common to both postischemic and to normal kidney samples are removed, leaving those sequences which are significantly expressed only in the injured kidney tissue. Such genes encode proteins that may be therapeutically beneficial for renal disorders or involved in the injury process. Several clones have been obtained, sequenced and characterized. The clones are then investigated for their expression patterns during kidney repair, development and tissue distribution by northern analysis and RNA in situ hybridization.
Sequence Identification Numbers
Nucleotide and amino acid sequences referred to in the specification have been given the following sequence identification numbers:
SEQ ID NO:1--nucleotide sequence of rat 3-2 cDNA insert
SEQ ID NO:2--nucleotide sequence of rat 1-7 cDNA insert
SEQ ID NO:3--amino acid sequence of rat KIM-1, encoded by rat 3-2 and 1-7 cDNAs
SEQ ID NO:4--nucleotide sequence of rat 4-7 cDNA insert
SEQ ID NO:5--amino acid sequence encoded by 4-7 cDNA insert
SEQ ID NO:6--nucleotide sequence of human cDNA clone H13-10-85
SEQ ID NO:7--amino acid sequence encoded by human cDNA clone H13-10-85
Compounds of the Invention
The invention includes the cDNA of SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6, as well as sequences which include the sequence of SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:6, and derivatives of these sequences. The invention also includes vectors, liposomes and other carrier vehicles which encompass these sequence or derivatives of them. The invention further includes proteins transcribed from SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:4, or SEQ ID NO:6, including but not limited to SEQ ID NO:3, SEQ ID NO:5 or SEQ ID NO:7, and their derivatives and variants.
One embodiment of the invention includes soluble variants of a KIM protein that is usually synthesized as a membrane associated protein, and which is upregulated after injury. Soluble variants lack at least a portion of the transmembrane or intra-membrane section of a native KIM protein. In some examples, the soluble variant lacks the entire transmembrane or intra-membrane section of a native KIM protein. The present soluble variants can be derived from intact or native KIM proteins by any suitable means, including chemical or enzymatic cleavage, or through molecular engineering techniques such by expression of a truncated KIM nucleic acid. Thus, the present soluble variants should be understood to be derivatives of an intact KIM. Soluble variants include fusion proteins which encompass derivatives of KIM proteins that lack at least a portion of the transmembrane or intra-membrane section of a native KIM protein. All types of KIM fusion proteins are included, particularly those which incorporate his-tag, Ig-tag, and myc-tag forms of the molecule. These KIM fusions may have characteristics which are therapeutically advantageous, such as the increased half-life conferred by the Ig-tag. Also included are fusion proteins which incorporate portions of selected domains of the KIM protein.
Variants can differ from naturally occurring KIM protein in amino acid sequence or in ways that do not involve sequence, or both. Variants in amino acid sequence are produced when one or more amino acids in naturally occurring KIM protein is substituted with a different natural amino acid, an amino acid derivative or non-native amino acid. Particularly preferred variants include naturally occurring KIM protein, or biologically active fragments of naturally occurring KIM protein, whose sequences differ from the wild type sequence by one or more conservative amino acid substitutions, which typically have minimal influence on the secondary structure and hydrophobic nature of the protein or peptide. Variants may also have sequences which differ by one or more non-conservative amino acid substitutions, deletions or insertions which do not abolish the KIM protein biological activity. Conservative substitutions typically include the substitution of one amino acid for another with similar characteristics such as substitutions within the following groups: valine, glycine; glycine, alanine; valine, isoleucine; aspartic acid, glutamic acid; asparagine, glutamine; serine, threonine; lysine, arginine; and phenylalanine, tyrosine. The non-polar (hydrophobic) amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan and methionine. The polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine and glutamine. The positively charged (basic) amino acids include arginine, lysine and histidine. The negatively charged (acidic) amino acids include aspartic acid and glutamic acid.
Other conservative substitutions can be taken from the table below, and yet others are those which meet the criteria for an accepted point mutation in Dayhoff et al. (1978), 5Atlas of Protein Sequence and Structure, Suppl. 3, ch. 22, Natl. Biomed. Res. Found., Washington, D.C. 20007, the teachings of which are incorporated by reference herein.
TABLE 1 CONSERVATIVE AMINO ACID REPLACEMENTS For Amino Acid Code Replace with any of Alanine A D-Ala, Gly, beta-Ala, L-Cys, D-Cys Arginine R D-Arg, Lys, homo-Arg, D-homo-Arg, Met, D-Met, Ile, D-Ile, Orn, D-Orn Asparagine N D-Asn, Asp, D-Asp, Glu, D-Glu, Gln, D-Gln Aspartic Acid D D-Asp, D-Asn, Asn, Glu, D-Glu, Gln, D-Gln Cysteine C D-Cys, S-Me-Cys, Met, D-Met, Thr, D-Thr Glutamine Q D-Gln, Asn, D-Asn, Glu, D-Glu, Asp, D-Asp Glutamic Acid E D-Glu, D-Asp, Asp, Asn, D-Asn, Gln, D-Gln Glycine G Ala, D-Ala, Pro, D-Pro, Beta-Ala, Acp Isoleucine I D-Ile, Val, D-Val, Leu, D-Leu, Met, D-Met Leucine L D-Leu, Val, D-Val, Met, D-Met Lysine K D-Lys, Arg, D-Arg, homo-Arg, D-homo-Arg, Met, D-Met, Ile, D-Ile, Orn, D-Orn Methionine M D-Met, S-Me-Cys, Ile, D-Ile, Leu, D-Leu, Val, D-Val, Norleu Phenylalanine F D-Phe, Tyr, D-Thr, L-Dopa, His, D-His, Trp, D-Trp, Trans 3,4 or 5-phenylproline, cis 3,4 or 5 phenylproline Proline P D-Pro, L-I-thioazolidine-4-carboxylic acid, D- or L-1- oxazolidine-4-carboxylic acid Serine S D-Ser, Thr, D-Thr, allo-Thr, Met, D-Met, Met(O), D-Met(O), Val, D-Val Threonine T D-Thr, Ser, D-Ser, allo-Thr, Met, D-Met, Met)O, D-Met(O), Val, D-Val Tyrosine Y D-Tyr, Phe, D-Phe, L-Dopa, His, D-His Valine V D-Val, Leu, D-Leu, Ile, D-Ile, Met, D-Met
Other variants within the invention are those with modifications which increase peptide stability. Such variants may contain, for example, one or more non-peptide bonds (which replace the peptide bonds) in the peptide sequence. Also included are: variants that include residues other than naturally occurring L-amino acids, such as D-amino acids or non-naturally occurring or synthetic amino acids such as beta or gamma amino acids and cyclic variants. Incorporation of D-instead of L-amino acids into the polypeptide may increase its resistance to proteases. See, e.g., U.S. Pat. No. 5,219,990.
Generally, substitutions that may be expected to induce changes in the functional properties of KIM polypeptides are those in which: (I) a hydrophilic residue, e.g., serine or threonine, is substituted by a hydrophobic residue, e.g., leucine, isoleucine, phenylalanine, or alanine; (ii) a cysteine residue is substituted for (or by) any other residue; (iii) a residue having an electropositive side chain, e.g., lysine, arginine or histidine, is substituted for (or by) a residue having an electronegative charge, e.g., glutamic acid or aspartic acid; or (iv) a residue having a bulky side chain, e.g., phenylalanine, is substituted for (or by) one not having such a side chain, e.g., glycine.
The peptides of this invention may also be modified by various changes such as insertions, deletions and substitutions, either conservative or nonconservative where such changes might provide for certain advantages in their use. Splice variants are specifically included in the invention.
In other embodiments, variants with amino acid substitutions which are less conservative may also result in desired derivatives, e.g., by causing changes in charge, conformation and other biological properties. Such substitutions would include for example, substitution of hydrophilic residue for a hydrophobic residue, substitution of a cysteine or proline for another residue, substitution of a residue having a small side chain for a residue having a bulky side chain or substitution of a residue having a net positive charge for a residue having a net negative charge. When the result of a given substitution cannot be predicted with certainty, the derivatives may be readily assayed according to the methods disclosed herein to determine the presence or absence of the desired characteristics.
In accordance with the foregoing, the scope of the invention includes proteins and peptides with variant amino acid sequences (sequence variants) having at least eighty percent similarity with a KIM protein. More preferably the sequence similarity is at least ninety percent, or at least ninety-five percent. For example, a sequence variant within the scope of the invention is any which shares at least eighty percent similarity with a KIM selected from rat KIM1 (SEQ ID NO:3) and human KIM1 (SEQ ID NO: 7). The percentage of similarity between a variant sequence and a reference sequence (such as SEQ ID NO:3 or SEQ ID NO: 7) is determined after the variant is aligned with the reference, preferably according to the method of Needelman et al. (1970), 48 J. Mol. Biol. 443-454, or according to an appropriate sequence alignment program (discussed more fully below). The percentage of sequence "identity" of the variant to the reference is the percentage of amino acid or nucleic acid residues of the variant sequence that are identical to the aligned (corresponding) residues of the reference. The percentage of sequence "similarity" is the sum of the percentage of identical corresponding residues and the percentage of variant residues that are conservative substitutions for the aligned (corresponding) reference residues.
A number of algorithms and computer software programs can be utilized to determine whether a sequence of interest is a KIM sequence variant within the scope of this invention. One such is the algorithm of Karlin and Altschul (1990) Proc. Natl. Acad. Sci. USA 87:2264-68, as modified in Karlin and Altschul (1993), Proc. Natl. Acad. Sci. USA 90:5873-77. This algorithm is incorporated into the NBLAST and XBLAST programs of Altschul et al. (1990) J. Mol. Biol. 215:403-10. BLAST nucleotide searches can be performed with NBLAST. BLAST protein searches can be performed with XBLAST. To obtain gapped alignments, gapped BLAST can be utilized as described in Altschul et al. (1997) Nucl. Acids Res. 25(17):3389-3402. All of the foregoing are available through http:.backslash..backslash.www.ncbi.nlm.nih.gov. Another suitable algorithm is that of Myers and Miller, CABIOS (1989), which is incorporated into the ALIGN program (version 2.0), which is a part of the Wisconsin Sequence Analysis package of the Genetics Computing Group (GCG). Thus, variants within the invention include any polypeptide or nucleic acid sequence which is identified through BLAST or CABIOS analysis as being related to a KIM nucleic acid or polypeptide sequence disclosed herein (e.g., rat KIM1, SEQ ID NO:3 or human KIM1, SEQ ID NO:7). "Related" sequences are those for which, in the judgement of an ordinarily skilled practitioner, the results of sequence analysis indicate a biologically significant relationship with the reference sequence (e.g., rat KIM1 or human KIM1).
Preferably, sequence variants of the KIM proteins disclosed herein are those having an amino acid sequence which is at least forty (40) percent identical overall (i.e., when aligned) to a disclosed KIM polypeptide sequence, and sharing at least 80% of the aligned KIM cysteine residues. Particularly preferred sequence variants are those which meet the foregoing analysis criteria when analyzed, relative to a KIM reference sequence disclosed herein (e.g., rat KIM1, SEQ ID NO:3 or human KIM1, SEQ ID NO:7), using the program GAP, which is a part of the Wisconsin analysis package of the GCG. To run a GAP analysis, the following program parameters should be used: the gap creation penalty (gap weight) should be set to 3.0, and the gap extension penalty (gap length) should be set to 0.1. GAP uses the algorithm of Needelman et al. (1970), 48 J. Mol. Biol. 443-453, to create an alignment with the largest number of matched (aligned identical) residues and the fewest number of sequence gaps.
Just as it is possible to replace substituents of the scaffold, it is also possible to substitute functional groups which are bound to the scaffold with groups characterized by similar features. These substitutions will initially be conservative, i.e., the replacement group will have approximately the same size, shape, hydrophobicity and charge as the original group. Non-sequence modifications may include, for example, in vivo or in vitro chemical derivatization of portions of naturally occurring KIM protein, as well as changes in acetylation, methylation, phosphorylation, carboxylation or glycosylation.
Also included within the invention are agents which specifically bind to the protein, or a fragment of the protein (SEQ ID NO:3, 5 or 7). These agents include ligands and antibodies (including monoclonal, single chain, double chain, Fab fragments, and others, whether native, human, humanized, primatized, or chimeric). Additional descriptions of these categories of agents are in PCT application 95/16709, the specification of which is herein incorporated by reference.
1. Generation of RNA from Ischemic and Normal Rat Adult Kidneys
Ischemic injured rat kidneys are generated as described by Witzgall et al. (J. Clin Invest. 93: 2175-2188, 1994). Briefly, the renal artery and vein from one kidney of an adult Sprague-Dawley rat are clamped for 40 minutes and then reperfused. Injured kidneys are harvested from the rats at 24 hours and at 48 hours after reperfusion. Kidneys from sham-operated, normal adult Sprague-Dawley rats are also harvested.
Total RNA is prepared from the organs based on the protocol by Glisin et al. (Biochemistry 13: 2633, 1974). Briefly, the harvested organs are placed immediately into GNC buffer (4M guanidine thiocyanate, 0.5% SDS, 25 mM sodium citrate, 0.1% Sigma anti foam) and disrupted on ice with a polytron. Cell debris is removed with a low speed spin in a clinical centrifuge and the supernatant fluid is placed on a 5.7 M CsCl, 25 mM sodium acetate, 1 mM EDTA cushion. RNA is pelleted through the cushion in a SW40Ti rotor at 22K for 15 hrs. RNA is resuspended in sterile DEPC-treated water, precipitated twice with 1/10 volume 3M sodium acetate and 2.5 volumes of EtOH. Poly A+RNA is isolated using an mRNA purification kit (Pharmacia, catalog No.27-9258-02).
2. Representational Difference Analysis (RDA) Method to Isolate 1-7. 3-2 and 4-7 RDA Fragments
Double stranded cDNA is synthesized from sham-operated and from 48 hr post-ischemic kidney poly A+RNA using Gibco BRL "Superscript Choices System cDNA Synthesis Kit", catalog No. 18090. First strand is synthesized by priming with oligo dT and using Superscript II.TM. reverse transcriptase. Second strand is generated using E. coli DNA polymerase I and RNase H followed by T4 DNA polymerase using BRL recommended conditions.
RDA analysis is performed essentially as described by Hubank and Schatz (Nucleic Acid Research 22: 5640-48, 1994). Briefly, 48 hr post-ischemic kidney cDNA is digested with the restriction enzyme Dpn II, and ligated to R-Bgl-12/24 oligonucleotides (see reference for exact sequence). PCR amplification (performed with Perkin-Elmer Taq polymerase and their corresponding PCR buffer) of the linker ligated cDNA is used to generate the initial representation. This PCR product is designated "tester amplicon." The same procedure is used to generate "driver amplicon" from sham-operated rat kidney cDNA.
Hybridization of tester and driver amplicons followed by selective amplification are performed three times to generate Differential Product One (DP1), Two (DP2) and Three (DP3). Generation of the DP1 product is performed as described by Hubank and Schatz (Nucleic Acid Research 22: 5640-48, 1994). The DP2 and DP3 products are also generated as described by Hubank and Schatz (id.), except that the driver:tester ratios are changed to 5,333:1 for DP2 and to 40,000:1 or 4,000:1 for DP3.
Three RDA products are cloned from DP3 into the cloning vector pUC 18: RDA product 1-7 (252 bp) when the DP3 was generated using a ratio of 40,000:1, and product RDA 3-2 (445 bp) and 4-7 (483 bp) when the DP3 was generated using a ratio of 4,000:1. The DNA fragments are subcloned using the Pharmacia Sureclone.TM. kit (catalog No. 27-9300-01) to repair the ends of the PCR fragments with Klenow enzyme and to facilitate blunt end ligation of the fragments into the pUC18 vector.
3. Northern Analysis
Poly A+RNA (2.5 .mu.g) from rat normal adult kidney (sham operated), from 48 hr post-ischemic injured adult kidney, and from day 18 embryonic kidney is electrophoresed and Northern blotted (Cate, Cell 45:685, 1986) to a GeneScreen.TM. membrane (Dupont). Hybridization in PSB buffer (50 mM Tris 7.5, 1M NaCl , 0.1% Na pyrophosphate, 0.2% PVP, 0.2% Ficoll, 0.2% BSA, 1% SDS), containing 10% dextran sulphate and 100 .mu.g/ml tRNA, is performed at 65C using three different probes: 1-7 RDA product, 3-2 RDA product and 4-7 RDA product. All are radiolabeled using Pharmacia's "Ready to Gorm" random priming labeling kit (catalog No.27-9251-01). RDA products 1-7, 3-2 and 4-7 hybridize to mRNAs present in all three samples, but most intensely to mRNAs in the 48 hr post-ischemic kidney RNA samples.
A Northern blot analysis of adult rat tissues indicates that the 1-7 gene is expressed at very low levels in normal adult kidney, testis, spleen and lung. The 3-2 gene is expressed in liver, kidney, spleen, and brain. The 4-7 gene is expressed in spleen, kidney, lung, testis, heart , brain, liver, and skeletal muscle. The presence of different sized mRNAs in some tissues in the 1-7 and 3-2 blot indicates that the primary transcription product of the 1-7 gene and of the 3-2 gene may undergo alternate splicing and/or polyadenylation.
4. Isolation of 3-2 and 4-7 cDNA Clones
A cDNA library is generated from 4 .mu.g of polyA+RNA from 48 hr post-ischemic injured kidney using reagents from BRL Superscript Choice.TM. System for cDNA synthesis, and Stratagene.TM. Lambda ZapII cloning kit (catalog No. 236201), according to protocols recommended by the manufacturers.
105 clones are screened with the 3-2 RDA product as a probe (random primed labeled as described above). Eight positive clones are selected and four are randomly chosen for secondary analysis to obtain pure phage plaques. After tertiary screening, four pure phage clones are isolated. Cloned inserts from the phage are isolated by in vivo excision procedure according to Stratagenem Lambda Zap II kit. The largest insert, of approximately 2.6 kb (referred to as cDNA clone 3-2), is subjected to DNA sequencing. The sequence of the insert (SEQ ID NO:1) is shown in FIG. 1. cDNA clone 3-2 (E. coli K-12, SOLR/p3-2#5-1) has been deposited as ATCC No. 98061. The sequence of cDNA clone 3-2 is identical to that of clone 1-7 cDNA (SEQ ID NO:2), except that nucleotides 136-605 of SEQ ID NO:1 represent an insertion. Thus, SEQ ID NO:2 represents a splice variant form of SEQ ID NO: 1. The clone for 1-7 (E. coli K-12, SOLR/p1-7#3-1) has been deposited as ATCC No. 98060.
105 clones are screened with the 1-7 RDA product as a probe (random primed radiolabeled as described above). Eight positive clones are selected and four are randomly chosen for secondary analysis to obtain pure phage plaques. After tertiary screening, four pure phage clones are isolated. Cloned inserts from the phage are isolated by in vivo excision procedure according to Stratagene.TM. Lambda Zap II kit. The largest insert of approximately 2.0 kb (referred to as cDNA clone 1-7) is subjected to DNA sequencing; the sequence of the insert (SEQ ID NO: 2) is shown in FIG. 2.
105 clones are screened with the 4-7 RDA product as a probe (random primed labeled as described above and hybridized in PSB at 65C). Eight positive clones are selected and four are randomly chosen for secondary analysis to obtain pure phage plaques. After secondary screening, two pure phage clones are isolated. Cloned inserts from the phage are isolated by in vivo excision procedure according to Stratagen.TM. Lambda Zap II kit. The largest insert, approximately 2.4 kb (referred to as cDNA clone 4-7), is subjected to DNA sequencing. The sequence of the insert, SEQ ID NO: 4, is shown in FIG. 3. The cDNA clone 4-7 (E. coli K-12, SOLR/p4-7#1-1) has been deposited as ATCC No. 98062.
5. Characterization of the 1-7. 3-2 and 4-7 cDNA Clones
A.) DNA and Protein Sequences:
The sequence of 3-2 cDNA (FIG. 1; SEQ ID NO:1) contains an open reading frame of 307 amino acids (FIG. 1; SEQ ID NO:3). A signal sequence of 21 amino acids is inferred from Von Heijne analysis (Von Heijne et al., Nucl. Acid Res. 14:14683 (1986)), and a transmembrane region spanning approximately aa 235-257 indicates that the 3-2 product is a cell surface protein. The sequence of 1-7 cDNA (FIG. 2; SEQ ID NO:2) contains an open reading frame of 307 amino acids, which is identical to the open reading frame contained in the 3-2 cDNA (SEQ ID NO: 3). This 307 amino acid polypeptide is herein designated rat KIM1. The sequence of 4-7 cDNA (FIG. 3; SEQ ID NO:4) contains an open reading frame of 572 amino acids (SEQ ID NO:5). A transmembrane region is located at approximately amino acids 501-521. This 572 amino acid polypeptide is related to the polypeptide known as nmb. Weterman et al. (1995) 60 Int. J. Cancer 73-81.
B.) In situ Analysis of 1-7, 3-2 and 4-7 mRNAs in Contralateral and in Post-ischernic Adult Rat Kidneys:
In situ hybridization is carried out according to the method described by Finch et al., Dev. Dynamics 203: 223-240, 1995. Briefly, both ischemic and contralateral kidneys are perfusion fixed with 4% paraformaldehyde in PBS. Kidneys are further fixed overnight at 4C and processed. Paraffin sections are deparaffinized and rehydrated, fixed with 4% paraformaldehyde in PBS, digested with proteinase K, refixed, then acetylated with acetic anhydride in triethanolamine buffer. Sections are then dehydrated and hybridized with 32 P-labeled riboprobes at 55oC. overnight, with 33P-labeled riboprobes generated from 3-2 RDA or 1-7 RDA products subcloned into BamH1 site of pGEM-11Z. After hybridization, sections were washed under high stringency conditions (2xSSC, 50% formamide at 65oC.). Sections are finally dehydrated, emulsion (NBT-2) coated for autoradiography, and exposed for at least a week. Silver grains are developed and sections are counterstained with toluidine blue and microphotographed.
Analysis of 1-7 and 3-2 mRNA expression by in situ hybridization indicates that these genes are greatly upregulated in damaged kidney cells compared to their expression in normal kidney sections. The expression seen is in regenerative cells of the cortex and outer medulla, most of which appear to be proximal tubule cells.
Analysis of the 4-7 in situ RNA expression pattern also reveals abundant expression of this gene in the injured ischemic kidney compared to the normal adult kidney. The site of expression appears to be infiltrating cells.
6.) Isolation of a Human cDNA Clone Which Cross Hybridizes to the Rat 3-2 cDNA
A 32 P-labeled DNA probe comprising nucleotides 546-969 of the insert of clone 3-2 shown in FIG. 1 is generated and used to screen a human embryonic liver lambda gt10 cDNA library (Clontech Catalog #HL5003a). 1x106 plaques are screened in duplicate using standard conditions as described above but temperature for screening was 55C. For the high stringency wash, the filters are washed in 2xSSC at 55C. Fifty positive phage are identified and plaque purified, and DNA is prepared. The phage DNAs are subjected to Southern analysis using the same probe as above. The Southern blot filter is subjected to a final wash with 0.5xSSC at 55C. Two clones are identified as positive. The insert of clone H13-10-85 is sequenced and a region is found that encodes a protein with a high level of identity to the 3-2 protein shown in FIG. 3.
The nucleotide sequence (SEQ ID NO:6) and predicted amino acid sequence (SEQ ID NO:7) of the human 3-2 related protein are shown in FIG. 4. As shown by the bestfit analysis depicted in FIG. 5, the human 3-2 related protein is 43.8% identical and 59.1% similar to the rat 3-2 protein. Both contain IgG, mucin, transmembrane, and cytoplasmic domains. The six cysteines within the IgG domains of both proteins are conserved. Accordingly, the polypeptide of SEQ ID NO:7 is designated human KIM1 (or KIM-1) herein. It is believed that the mammalian genome (e.g., the human genome) includes genes encoding a family of KIM-1 related proteins. Thus, the human KIM-1 disclosed herein is more precisely designated human KIM-1a.
7) Production of KIM-1 Ig Fusion Protein
A fusion protein of the extracellular domain of KIM and the Fc region of immunoglobulin (Ig) is a useful tool for the study of the molecular and cellular biology of the injured/regenerating kidney and as a therapeutic molecule. To produce Kim Ig fusion protein with the extracellular domain of human and rat KIM-1 protein, a fragment of the extracellular domain of KIM-1 cDNA was amplified by PCR and cloned in the Biogen expression vector, pCA125, for transient expression in COS cells. The expression vector pCA125 produces a fusion protein which has a structure from gene cloned at N-terminus and a human Ig Fc region at the C-terminus. COS cells were transfected with the plasmids SJR 103 or 104; these plasmids express a fusion protein which contains the human KIM sequences 263-1147 (SEQ ID NO:6; SJR 103) or rat KIM sequences 599-1319 (SEQ ID NO:1; SJR 104) of the extracellular domain fused to human Ig Fc region. The cells were grown in 10% FBS in DMEM in the cell factory (Nunc, Naperville, Ill.). Two to three days post-transfection, medium was harvested, concentrated using Amicon concentrator, and fusion protein was purified using Protein-A Sepharose column. After purification, purity of fusion protein was evaluated by SDS-PAGE.
8) Production of Antibodies, Including Monoclonal Antibody (MAb) AKG7, With Binding Specificity for Human KIM Protein
Antibody production involves administration of one or more immunogenic doses of a KIM polypeptide preparation (whether isolated, or as part of a cell suspension, fraction or extract) to an appropriate non-human animal, such as a mouse, rat, rabbit, gunea pig, turkey, goat, sheep, pig or horse. To enhance immunogenicity, the preparation is emulsified with a conventional adjuvant (e.g., Complete Freund's Adjuvant, CFA). Serum immunoglobulins (Ig), using peripheral blood samples withdrawn at intervals (e.g., weekly) after initial or a subsequent immunization, are monitored to detect the onset and/or maturation of a humoral immune response to KIM. Any conventional technique, e.g., ELISA, RIA, Western blotting, or the like, can be used to detect and/or quantitate (titer) the KIM-specific Ig. High titer immune sera are preferred for use as anti-KIM polyclonal antibodies herein. High titer sera (e.g., having a titer of at least 1:1000) can be harvested in bulk for purification of anti-KIM Ig, using conventional immunoaffinity chromatography (e.g., using a Protein A resin).
Animals (e.g., mice, rats, guinea pigs, hamsters) having a high serum titer of anti-KIM Ig also can be used for the conventional production of monoclonal antibodies (MAb) with binding specificity for KIM. Splenocytes are isolated from such animals and are fused with a myeloma cell line according to standard techniques to produce hybridomas. Such hybridomas are cloned by limiting dilution, fluorescence-activated cell sorting, or any other suitable cell isolation technique, to produce monoclonal hybridoma cell lines of the present invention. Hybridoma lines of the present invention are useful for the production of anti-KIM MAbs, and also as sources from which nucleic acids encoding the present anti-KIM MAbs can be routinely isolated. Such nucleic acids, encoding heavy and/or light chain polypeptides of the present MAbs, can be used to produce recombinant, engineered versions of the present MAbs, including truncated MAb polypeptides, chimeric or humanized MAbs, and MAb fusion proteins.
By way of illustration, mice have been immunized with a human KIM1-Ig fusion protein as disclosed herein, which was immobilized on Protein A Sepharose beads and emulsified in CFA. The fusion protein included the extracellular domain of human KIM1 (amino acids 1 to 291) fused to a truncated human IgG1 polypeptide comprising the hinge-C2-C3 domains of the IgG1 heavy chain polypeptide. The onset and maturation of a humoral immune response was monitored using a conventional ELISA, in which another Ig fusion protein was used as a blocking agent to subtract serum Ig's having undesired specificity for the IgG1 portion of the KIM1 fusion protein. Following conventional isolation of immune splenocytes, fusion, ELISA screening, and cloning by limiting dilution, ten MAbs were obtained with desirable binding specificity for human KIM 1. Among these, one, designated AKG7, is preferred herein. The AKG7 antibody is useful in ELISA, Western blot and immunohistochemistry analysis of human KIM1 polypeptides. The present technique can be repeated and/or adapted routinely to produce any number of MAbs to domains (e.g., the extracellular domain) of KIM proteins, that have the KIM-specific binding properties of MAb AKG7 and are useful in the analytical, diagnostic and therapeutic methods described herein.
MAbs of the present invention, such as AKG7, are obtained from cell culture media conditioned by the present hybridoma lines, or from ascites fluid, or from media conditioned by an engineered host cell expressing a heavy and/or light chain nucleic acid construct encoding an anti-KIM MAb of the present invention. Such MAbs are purified using conventional immunoaffinity chromatography, and used in the various diagnostic, analytical and therapeutic methods described herein.
Diagnostic Uses of the Compounds of the Invention
Anti-KIM antibodies of the invention, which specifically bind to the protein of SEQ ID NO:3, SEQ ID NO:5 or SEQ ID NO:7 or a fragment thereof, are useful in several diagnostic methods. These agents may be labeled with detectable markers, such as fluoroscopically or radiographically opaque substances, and administered to a subject to allow imaging of tissues which express KIM protein. The agents may also be bound to substances, such as horseradish peroxidase, which can be used as immunocytochemical stains to allow visualization of areas of KIM protein-positive cells on histological sections. A specific antibody could be used alone in this manner, and sites where it is bound can be visualized in a sandwich assay using an anti-immunoglobulin antibody which is itself bound to a detectable marker.
For example and not by way of limitation, the AKG7 MAb can be used to visualize cells producing KIM-1 protein in immunohistochemistry analysis of human renal tissue samples. Immunohistochemistry is carried out on paraformaldehyde-fixed paraffin sections by deparaffinizing the sections, then ablating endogenous peroxidase activity by incubation in 2% hydrogen peroxide in methanol for 20 min. Sections are then heated in a microwave oven in 0.1 M citrate buffer, pH 6.0, for 10 min., then blocked with diluted goat serum (1:67) overnight at 4oC. Thereafter, sections are incubated with affinity purified AKG7 or control IgG at a concentration of 5 .mu.g/mL. After 1 hr, the sections are washed in PBS and incubated with biotinylated goat anti-mouse IgG for 30 min. After further washes with PBS, the sections are incubated with avidin-biotinylated horseradish peroxidase complex (Vectastain Elite ABC kit, Vector Laboratories) for 1 hr. Sections are washed in PBS and developed by the addition of 50 mM sodium phosphate buffer, pH 7.6, containing 0.12% 3,3-diaminobenzidine tetrahydrochloride (Sigma), 0.0075% nickel chloride, 0.0075% cobalt chloride, and 0.0075% hydrogen peroxide for 2-5 min., producing a dark brown stain indicating immunoreactivity. Sections are then counterstained with 0.01% toluidine blue. This technique has been used to visualize KIM-1 immunoreactivity in paraffin sections from two different human patients with renal cell carcinoma. Sections comprising tumor tissue and adjacent normal renal tissue were assessed. In patients, strong KIM-1 immunoreactivity was noted in tumor tissue. By contract, immunoreactivity was virtually absent in adjacent normal tissue (as judged by pathology). Immunoreactivity was also virtually absent in normal control renal tissue sections. These data are consistent with the utility of antibodies to KIM-1 as reagents for the diagnosis, prognostication and/or staging of renal cancers.
Specific antibodies to KIM protein are also useful in immunoassays to measure KIM presence or concentration in samples of body tissues and fluids. Such concentrations may be correlated with different disease states. As an embodiment of particular interest, the invention includes a method of diagnosing renal injury, or of monitoring a process of renal repair, by measuring the concentration of KIM or of KIM fragments in the urine, plasma or serum of a patient. Similarly, KIM can be measured in urine sediment, in particular in cellular debris in the urine sediment. Casts of renal tubule cells, which may be present in urine sediment from patients with ongoing renal disease, may contain elevated levels of KIM protein and nRNA.
Specific antibodies to KIM protein may also be bound to solid supports, such as beads or dishes, and used to remove the ligand from a solution, either for measurement, or for purification and characterization of the protein or its attributes (such as posttranslational modifications). Such characterization of a patient's KIM protein might be useful in identifying deleterious mutants or processing defects which interfere with KIM function and are associated with abnormal patient phenotypes. Each of these techniques is routine to those of skill in the immunological arts.
Additional imaging methods utilize KIM or KIM fragments, fused to imageable moieties, for diagnostic imaging of tissues that express KIM ligands, particularly tumors.
Further diagnostic techniques are based on demonstration of upregulated KIM mRNA in tissues, as an indication of injury-related processes. This technique has been tested and found workable in a model of ischemic injury in rats, as follows.
To determine if the amount of KIM-1 protein is increased after injury, kidney homogenates of contralateral and postischemic kidneys were examined 24 and 48 hours following a 40 minute clamping of the renal artery and vein of a single kidney for each rat. The kidney homogenate was assessed for the presence of KIM-1 protein. Western blot analysis identifies three proteins detected by two different antibodies after ischemic injury, which are not detectable in homogenates from contralateral kidneys which were not exposed to ischemic injury. The apparent molecular weights of the bands are approximately 40 kDa, 50 kDa and 70-80 kDa. The three protein species detected by western blotting could represent glycosylated forms of the same protein given the presence of potential N and O linked glycosylation sites. The fact that each of these proteins react with two different sets of polyclonal antibodies supports the idea that they are related to KIM-1 and are not cross-reacting bands. Confirmation of this prediction came from the results of partial CNBr cleavage of the three proteins which revealed they shared common CNBr cleavage fragments. Since the cytoplasmic domain of the KIM-1 protein is not predicted to contain any major post-translational modifications, the two smallest products of the digest (4.7 kDa and 7.4 kDa) detected with antibodies directed against the cytoplasmic domain of KIM-1 should be the same size for the three different KIM-1 protein bands if they originate from the same protein. The KIM1 40 kDa and 70-80 kDa proteins indeed produced fragments migrating at the predicted size. Digest of the 50 kDa protein band gave also the same C-terminal signature band peptide.
The KIM-1 sequence presents two putative sites for N-glycosylation and a mucin domain where O-glycosylation could cover the polypeptide chain. The three KIM-1 bands detected in postischemic kidney could correspond to glycosylation variants of the same core protein. De-N-glycosylation with PNGase F resulted in a shift of all three bands to a lower molecular weight, corresponding to a loss of about 3 kDa, indicating that all three proteins are N-glycosylated. Differences in O-glycosylation might explain the differences in sizes of these three bands.
Further studies are expected to corroborate the correlation between KIM-1 expression and disease status of renal tissue. For example and not by way of limitation, Northern blot analysis can be carried out to establish levels of KIM-1 expression in normal and cancerous renal tissue samples. Poly(A)+RNA is obtained from tissue samples of interest (e.g., kidney biopsy or necropsy samples, or control samples), size fractionated by electrophoresis, and transferred to a GeneScreen membrane (NEN Life Science Products). Hybridization with a KIM-1 probe corresponding to part or all of the open reading frame of the KIM-1 gene of interest (e.g., human KIM-1, SEQ ID NO:6) is carried out in plaque screening buffer (PSB, 50 mM Tris, pH 7.5, 1 M NaCl, 0.1% sodium pyrophosphate, 0.2% polyvinylpyrrolidone, 0.2% Ficoll, 0.2% bovine serum albumin, 1% SDS) containing 10% dextran sulfate and 100 .mu.g/mL tRNA at 65oC. The KIM-1 probe is preferably detectably labeled, e.g., radiolabelled. The membrane is then washed to remove unbound probe, and KIM-1 mRNA is visualized using standard membrane development techniques. Thereafter, the KIM-1 probe is stripped from the blot, and the blot is rehybridized with a control probe, such as a .beta.-actin probe.
The results of an exemplary Northern blot analysis are set forth in FIG. 6: biopsy samples containing histologically normal renal tissue were compared to renal tumor tissues (renal cell carcinoma) obtained from four different patients afflicted with renal cancers. KIM-1 expression was virtually undetectable in three of the four normal samples and was weakly detectable in the fourth. In contract, two of the four renal cancer samples displayed strong KIM-1 expression. These results are consistent with the utility of KIM-1 probes as reagents for the diagnosis, prognostication or staging of renal cancers. Without being limited hereby, it is believed that aberrant KIM-1 gene expression may correlate with the degree of neoplastic transformation, agressiveness or metastatic propensity of a given renal cell carcinoma. Thus, assessment of KIM-1 gene expression is believed to provide information useful in conjunction with other, conventional diagnostic and/or clinical criteria for characterizing renal cancers.
Therapeutic Uses of the Compounds of the Invention
The therapeutic methods of the invention involve selectively promoting or inhibiting cellular responses that are dependent on KIM ligation. Where the KIM and the KIM ligand are both membrane bound, and expressed by different cells, the signal transduction may occur in the KIM-expressing cell, in the KIM ligand-expressing cell, or in both.
KIM ligation-triggered response in a KIM ligand-expressing cell may be generated by contacting the cell with exogenous KIM, KIM fusion proteins or activating antibodies against KIM ligand, either in vitro or in vivo. Further, responses of the KIM ligand-expressing cell that would otherwise be triggered by endogenous KIM could be blocked by contacting the KIM ligand-expressing cell with a KIM ligand antagonist (e.g., an antagonist antibody that binds to KIM ligand), or by contacting the endogenous KIM with an anti-KIM antibody or other KIM-binding molecule which prevents the effective ligation of KIM with a KIM ligand.
Similarly, the responses triggered by KIM ligation in the KIM-expressing cell may be promoted or inhibited with exogenous compounds. For example, KIM ligation-triggered response in a KIM-expressing cell may be generated by contacting the cell with a soluble KIM ligand, or certain anti-KIM activating antibodies. Further, responses of the KIM-expressing cell that would otherwise be triggered by interaction with endogenous KIM ligand could be blocked by contacting the KIM-expressing cell with an antagonist to KIM (e.g., a blocking antibody that binds to KIM in a manner that prevents effective, signal-generating KIM ligation), or by contacting the endogenous KIM ligand with an anti-KIM ligand antibody or other KIM ligand-binding molecule which prevents the effective ligation of KIM with the KIM ligand.
Which of the interventions described above are useful for particular therapeutic uses depend on the relevant etiologic mechanism of either the pathologic process to be inhibited, or of the medically desirable process to be promoted, as is apparent to those of skill in the medical arts. For example, where KIM ligation results in desirable cellular growth, maintenance of differentiated phenotype, resistance to apoptosis induced by various insults, or other medically advantageous responses, one of the above-described interventions that promote ligation-triggered response may be employed. In the alternative, one of the inhibitory interventions may be useful where KIM ligation invokes undesirable consequences, such as neoplastic growth, deleterious loss of cellular function, susceptibility to apoptosis, or promotion of inflammation events.
Following are examples of the previously described therapeutic methods of the invention. One therapeutic use of the KIM-related compounds of the invention is for treating a subject with renal disease, promoting growth of new tissue in a subject, or promoting survival of damaged tissue in a subject, and includes the step of administering to the subject a therapeutically effective amount of a KIM protein of the invention, or of a pharmaceutical composition which includes a protein of the invention. The protein used in these methods may be a fragment of a full-length KIM protein, a soluble KIM ligand protein or fusion fragment, or a KIM agonist. These methods may also be practiced by administering to the subject a therapeutically effective amount of an agonist antibody of the invention, or a pharmaceutical composition which includes an agonist antibody of the invention. A KIM protein may be administered concurrently with a therapeutically effective amount of a second compound which exerts a medically desirable adjunct effect. While tissues of interest for these methods may include any tissue, preferred tissues include renal tissue, liver, neural tissue, heart, stomach, small intestine, spinal cord, or lung. Particular renal conditions which may be beneficially treated with the compounds of the invention include acute renal failure, acute nephritis, chronic renal failure, nephrotic syndrome, renal tubule defects, kidney transplants, toxic injury, hypoxic injury, and trauma. Renal tubule defects include those of either hereditary or acquired nature, such as polycystic renal disease, medullary cystic disease, and medullary sponge kidney. This list is not limited, and may include many other renal disorders (see, e.g., Harrison's Principles of Internal Medicine, 13th ed., 1994, which is herein incorporated by reference.) The subject of the methods may be human.
A therapeutic intervention for inhibiting growth of undesirable, KIM ligand-expressing tissue in a subject includes the step of administering to the subject a therapeutically effective amount of a KIM antagonist (e.g., an antagonist antibody that binds to KIM ligand), or by administering a therapeutically effective amount of an anti-KIM antibody or other KIM-binding molecule which blocks KIM binding to the KIM ligand-expressing tissue. In an embodiment of interest, the KIM antagonist or anti-KIM antibody may be used therapeutically to inhibit or block growth of tumors which depend on KIM protein for growth.
Other methods of the invention include killing KIM ligand-expressing tumor cells, or inhibiting their growth, by contacting the cells with a fusion protein of a KIM and a toxin or radionuclide, or an anti-KIM ligand antibody conjugated to a toxin or radionuclide. The cell may be within a subject, and the protein or the conjugated antibody is administered to the subject.
Also encompassed within the invention is a method for targeting a toxin or radionuclide to a cell expressing a KIM, comprising contacting the cell with a fusion protein comprising a KIM ligand and a toxin or radionuclide, or an anti-KIM antibody conjugated to a toxin or radionuclide. Another embodiment includes the method of suppressing growth of a tumor cell which expresses KIM, comprising contacting the cell with a fusion protein of KIM ligand and a toxin or radionuclide or with an anti-KIM antibody conjugated to a toxin or radionuclide; the cell may be within a subject, and the protein administered to the subject.
The term "subject" used herein is taken to mean any mammal to which KIM may be administered. Subjects specifically intended for treatment with the method of the invention include humans, as well as nonhuman primates, sheep, horses, cattle, goats, pigs, dogs, cats, rabbits, guinea pigs, hamsters, gerbils, rats and mice, as well as the organs, tumors, and cells derived or originating from these hosts.
Use of Compounds of the Invention in Gene Therapy
The KIM genes of the invention are introduced into damaged tissue, or into tissue where stimulated growth is desirable. Such gene therapy stimulates production of KIM protein by the transfected cells, promoting cell growth and/or survival of cells that express the KIM protein.
In a specific embodiment of a gene therapy method, a gene coding for a KIM protein may be introduced into a renal target tissue. The KIM protein would be stably expressed and stimulate tissue growth, division, or differentiation, or could potentiate cell survival. Furthermore, a KIM gene may be introduced into a target cell using a variety of well-known methods that use either viral or non-viral based strategies.
Non-viral methods include electroporation, membrane fusion with liposomes, high velocity bombardment with DNA-coated microprojectiles, incubation with calcium-phosphate-DNA precipitate, DEAE-dextran mediated transfection, and direct micro-injection into single cells. For instance, a KIM gene may be introduced into a cell by calcium phosphate coprecipitation (Pillicer et al., Science, 209: 1414-1422 (1980); mechanical microinjection and/or particle acceleration (Anderson et al., Proc. Nat. Acad. Sci. USA, 77: 5399-5403 (1980); liposome based DNA transfer (e.g., LIPOFECTIN-mediated transfection-Fefgner et al., Proc. Nat. Acad. Sci., USA, 84: 471-477,1987; Gao and Huang, Biochim. Biophys. Res. Comm., 179: 280-285, 1991; DEAE Dextran-mediated transfection; electroporation (U.S. Pat. No. 4,956,288); or polylysine-based methods in which DNA is conjugated to deliver DNA preferentially to liver hepatocytes (Wolff et al., Science, 247: 465-468, 1990; Curiel et al., Human Gene Therapy 3: 147-154, 1992).
Target cells may be transfected with the genes of the invention by direct gene transfer. See, e.g., Wolff et al., "Direct Gene Transfer Into Moose Muscle In Vivo", Science 247:1465-68, 1990. In many cases, vector-mediated transfection will be desirable. Any of the methods known in the art for the insertion of polynucleotide sequences into a vector may be used. (See, for example, Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 1989; and Ausubel et al., Current Protocols in Molecular Biology, J. Wiley & Sons, NY, 1992, both of which are incorporated herein by reference.) Promoter activation may be tissue specific or inducible by a metabolic product or administered substance. Such promoters/enhancers include, but are not limited to, the native c-ret ligand protein promoter, the cytomegalovirus immediate-early promoter/enhancer (Karasuyama et al., J. Exp. Med., 169: 13,1989); the human beta-actin promoter (Gunning et al., Proc. Nat. Acad. Sci. USA, 84: 4831,1987; the glucocorticoid-inducible promoter present in the mouse mammary tumor virus long terminal repeat (MMTV LTR) (Klessig et al., Mol. Cell. Biol., 4: 1354, 1984); the long terminal repeat sequences of Moloney murine leukemia virus (MuLV LTR) (Weiss et al., RNA Tumor Viruses, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y., 1985); the SV40 early region promoter (Bernoist and Chambon, Nature, 290:304,1981); the promoter of the Rous sarcoma virus (RSV) (Yamamoto et al., Cell, 22:787, 1980); the herpes simplex virus (HSV) thymidine kinase promoter (Wagner et al., Proc. Nat. Acad. Sci. USA, 78: 1441, 1981); the adenovirus promoter (Yamada et al., Proc. Nat. Acad. Sci. USA, 82: 3567, 1985).
The KIM genes may also be introduced by specific viral vectors for use in gene transfer systems which are now well established. See for example: Madzak et al., J. Gen. Virol., 73: 1533-36, 1992 (papovavirus SV40); Berkner et al., Curr. Top. Microbiol. Immunol., 158: 39-61, 1992 (adenovirus); Hofmann et al., Proc. Natl. Acad. Sci. 92: 10099-10103, 1995 (baculovirus); Moss et al., Curr. Top. Microbiol. Immunol., 158: 25-38,1992 (vaccinia virus); Muzyczka, Curr. Top. Microbiol. Immunol., 158: 97-123, 1992 (adeno-associated virus); Margulskee, Curr. Top. Microbiol. Immunol., 158: 67-93, 1992 (herpes simplex virus (HSV) and Epstein-Barr virus (HBV)); Miller, Curr. Top. Microbiol. Immunol., 158: 1-24, 1992 (retrovirus); Brandyopadhyay et al.,Mol. Cell. Biol., 4: 749-754, 1984 (retrovirus); Miller et al., Nature, 357: 455-450, 1992 (retrovirus); Anderson, Science, 256: 808-813, 1992 (retrovirus), Current Protocols in Molecular Biology: Sections 9.10-9.14 (Ausubel et al., Eds.), Greene Publishing Associcates, 1989, all of which are incorporated herein by reference.
Preferred vectors are DNA viruses that include adenoviruses (preferably Ad-2 or Ad-5 based vectors), baculovirus, herpes viruses (preferably herpes simplex virus based vectors), and parvoviruses (preferably "defective" or non-autonomous parvovirus based vectors, more preferably adeno-associated virus based vectors, most preferably AAV-2 based vectors). See, e.g., Ali et al., Gene Therapy 1: 367-384, 1994; U.S. Pat. Nos. 4,797,368 and 5,399,346 and discussion below.
The choice of a particular vector system for transferring, for instance, a KIM sequence will depend on a variety of factors. One important factor is the nature of the target cell population. Although retroviral vectors have been extensively studied and used in a number of gene therapy applications, they are generally unsuited for infecting cells that are not dividing but may be useful in cancer therapy since they only integrate and express their genes in replicating cells. They are useful for ex vivo approaches and are attractive in this regard due to their stable integration into the target cell genome.
Adenoviruses are eukaryotic DNA viruses that can be modified to efficiently deliver a therapeutic or reporter transgene to a variety of cell types. The general adenoviruses types 2 and 5 (Ad2 and Ad5, respectively), which cause respiratory disease in humans, are currently being developed for gene therapy of Duchenne Muscular Dystrophy (DMD)and Cystic Fibrosis (CF). Both Ad2 and Ad5 belong to a subclass of adenovirus that are not associated with human malignancies. Adenovirus vectors are capable of providing extremely high levels of transgene delivery to virtually all cell types, regardless of the mitotic state. High titers (1013 plaque forming units/ml) of recombinant virus can be easily generated in 293 cells (an adenovirus-transformed, complementation human embryonic kidney cell line: ATCC CRL1573) and cryo-stored for extended periods without appreciable losses. The efficacy of this system in delivering a therapeutic transgene in vivo that complements a genetic imbalance has been demonstrated in animal models of various disorders. See Watanabe, Atherosclerosis, 36: 261-268, 1986; Tanzawa et al., FEBS Letters 118(1):81-84, 1980; Golasten et al., New Engl.J. Med. 309:288-296, 1983; Ishibashi et al., J. Clin. Invest. 92: 883-893, 1993; and Ishibashi et al., J. Clin. Invest. 93: 1889-1893, 1994, all of which are incorporated herein by reference. Indeed, recombinant replication defective adenovirus encoding a cDNA for the cystic fibrosis transmembrane regulator (CFTR) has been approved for use in at least two human CF clinical trials. See, e.g., Wilson, Nature 365:691-692, 1993. Further support of the safety of recombinant adenoviruses for gene therapy is the extensive experience of live adenovirus vaccines in human populations.
The first-generation recombinant, replication-deficient adenoviruses which have been developed for gene therapy of DMD and other inherited disorders contain deletions of the entire E1a and part of the E1b regions. This replication-defective virus is grown in 293 cells containing a functional adenovirus E1 a gene which provides a transacting E1a protein. E1-deleted viruses are capable of replicating and producing infectious virus in the 293 cells, which provide E1a and E1b region gene products in trans. The resulting virus is capable of infecting many cell types and can express the introduced gene (providing it carries its own promoter), but cannot replicate in a cell that does not carry the E1 region DNA unless the cell is infected at a very high multiplicity of infection. Adenoviruses have the advantage that they have a broad host range, can infect quiescent or terminally differentiated cells such as neurons, and appear essentially non-oncogenic. Adenoviruses do not appear to integrate into the host genome. Because they exist extrachromasomally, the risk of insertional mutagenesis is greatly reduced. Ali et al., supra, at 373. Recombinant adenoviruses (rAdV) produce very high titers, the viral particles are moderately stable, expression levels are high, and a wide range of cells can be infected. Their natural host cells are airway epithelium, so they are useful for therapy of lung cancers.
Baculovirus-mediated transfer has several advantages. Baculoviral gene transfer can occur in replicating and nonreplicating cells, and can occur in renal cells, as well as in hepatocytes, neural cells, spleen, skin, and muscle. Baculovirus is non-replicating and nonpathogenic in mammalian cells. Humans lack pre-existing antibodies to recombinant baculovirus which could block infection. In addition, baculovirus is capable of incorporating and transducing very large DNA inserts.
Adeno-associated viruses (AAV) have also been employed as vectors for somatic gene therapy. AAV is a small, single-stranded (ss) DNA virus with a simple genomic organization (4-7 kb) that makes it an ideal substrate for genetic engineering. Two open reading frames encode a series of rep and cap polypeptides. Rep polypeptides (rep78, rep68, rep 62 and rep 40) are involved in replication, rescue and integration of the AAV genome. The cap proteins (VP 1, VP2 and VP3) form the virion capsid. Flanking the rep and cap open reading frames at the 5' and 3' ends are 145 bp inverted terminal repeats (ITRs), the first 125 bp of which are capable of forming Y- or T-shaped duplex structures. Of importance for the development of AAV vectors, the entire rep and cap domains can be excised and replaced with a therapeutic or reporter transgene. See B. J. Carter, in Handbook of Parvoviruses, ed., P. Tijsser, CRC Press, pp. 155-168 (1990). It has been shown that the ITRs represent the minimal sequence required for replication, rescue, packaging, and integration of the AAV genome.
Adeno-associated viruses (AAV) have significant potential in gene therapy. The viral particles are very stable and recombinant AAVs (rAAV)have "drug-like" characteristics in that rAAV can be purified by pelleting or by CsCl gradient banding. They are heat stable and can be lyophilized to a powder and rehydrated to full activity. Their DNA stably integrates into host chromosomes so expression is long-term. Their host range is broad and AAV causes no known disease so that the recombinant vectors are non-toxic.
Once introduced into a target cell, sequences of interest can be identified by conventional methods such as nucleic acid hybridization using probes comprising sequences that are homologous/complementary to the inserted gene sequences of the vector. In another approach, the sequence(s) may be identified by the presence or absence of a "marker" gene function (e.g, thymidine kinase activity, antibiotic resistance, and the like) caused by introduction of the expression vector into the target cell.
Formulations and Administration
The compounds of the invention are formulated according to standard practice, such as prepared in a carrier vehicle. The term "pharmacologically acceptable carrier" means one or more organic or inorganic ingredients, natural or synthetic, with which the mutant proto-oncogene or mutant oncoprotein is combined to facilitate its application. A suitable carrier includes sterile saline although other aqueous and non-aqueous isotonic sterile solutions and sterile suspensions known to be pharmaceutically acceptable are known to those of ordinary skill in the art. In this regard, the term "carrier" encompasses liposomes and the HIV-1 tat protein (See Chen et al., Anal. Biochem. 227: 168-175, 1995) as well as any plasmid and viral expression vectors.
Any of the novel polypeptides of this invention may be used in the form of a pharmaceutically acceptable salt. Suitable acids and bases which are capable of forming salts with the polypeptides of the present invention are well known to those of skill in the art, and include inorganic and organic acids and bases.
A compound of the invention is administered to a subject in a therapeutically-effective amount, which means an amount of the compound which produces a medically desirable result or exerts an influence on the particular condition being treated. An effective amount of a compound of the invention is capable of ameliorating or delaying progression of the diseased, degenerative or damaged condition. The effective amount can be determined on an individual basis and will be based, in part, on consideration of the physical attributes of the subject, symptoms to be treated and results sought. An effective amount can be determined by one of ordinary skill in the art employing such factors and using no more than routine experimentation.
A liposome delivery system for a compound of the invention may be any of a variety of unilamellar vesicles, multilamellar vesicles, or stable plurilamellar vesicles, and may be prepared and administered according to methods well known to those of skill in the art, for example in accordance with the teachings of U.S. Pat. Nos. 5,169,637, 4,762,915, 5,000,958 or 5,185,154. In addition, it may be desirable to express the novel polypeptides of this invention, as well as other selected polypeptides, as lipoproteins, in order to enhance their binding to liposomes. As an example, treatment of human acute renal failure with liposome-encapsulated KIM protein may be performed in vivo by introducing a KIM protein into cells in need of such treatment using liposomes. The liposomes can be delivered via catheter to the renal artery. The recombinant KIM protein is purified, for example, from CHO cells by immunoaffinity chromatography or any other convenient method, then mixed with liposomes and incorporated into them at high efficiency. The encapsulated protein may be tested in vitro for any effect on stimulating cell growth.
The compounds of the invention may be administered in any manner which is medically acceptable. This may include injections, by parenteral routes such as intravenous, intravascular, intraarterial, subcutaneous, intramuscular, intratumor, intraperitoneal, intraventricular, intraepidural, or others as well as oral, nasal, ophthalmic, rectal, or topical. Sustained release administration is also specifically included in the invention, by such means as depot injections or erodible implants. Localized delivery is particularly contemplated, by such means as delivery via a catheter to one or more arteries, such as the renal artery or a vessel supplying a localized tumor.
Claim 1 of 19 Claims
What is claimed is:
1. An isolated nucleic acid comprising a nucleotide sequence encoding a polypeptide comprising amino acids 1-290 of SEQ ID NO:7.