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Biomedical subjects

K W Kinzler

Publications and source records attributed to K W Kinzler.

At least 19 recordsLinked to original sources
PubMed2001

Combination bacteriolytic therapy for the treatment of experimental tumors.

Current chemotherapeutic approaches for cancer are in part limited by the inability of drugs to destroy neoplastic cells within poorly vascularized compartments of tumors. We have here systematically assessed anaerobic bacteria for their capacity to grow expansively within avascular compartments of transplanted tumors. Among 26 different strains tested, one (Clostridium novyi) appeared particularly promising. We created a strain of C. novyi devoid of its lethal toxin (C. novyi-NT) and showed that intravenously injected C. novyi-NT spores germinated within the avascular regions of tumors in mice and destroyed surrounding viable tumor cells. When C. novyi-NT spores were administered together with conventional chemotherapeutic drugs, extensive hemorrhagic necrosis of tumors often developed within 24 h, resulting in significant and prolonged antitumor effects. This strategy, called combination bacteriolytic therapy (COBALT), has the potential to add a new dimension to the treatment of cancer.

Animals↗
PubMed2001

The role of hPMS1 and hPMS2 in predisposing to colorectal cancer.

Hereditary nonpolyposis colorectal cancer (HNPCC) is attributable to a deficiency of mismatch repair. Inactivation of DNA mismatch repair underlies the genesis of microsatellite instability in colorectal cancer. Germline mutations in three DNA mismatch repair genes, hMSH2, hMLH1, and hMSH6, have been found to segregate in HNPCC and HNPCC-like families. The two DNA mismatch repair genes hPMS1 and hPMS2 have also been suggested to predispose to HNPCC. In this study, 84 HNPCC and HNPCC-like kindreds without known mutations in the other three known DNA mismatch repair genes were screened for germline mutations in the hPMS1 or hPMS2 gene. No clear-cut pathogenic mutations were identified. Conversion technology was used to detect a large hMSH2 deletion in two affected members of the kindred in which the hPMS1 mutation was originally reported, whereas the hPMS1 mutation was only present in one of these two individuals. Since the hPMS1 and hPMS2 genes were first reported, germline mutations in hPMS2 have been demonstrated primarily in patients with Turcot's syndrome. However, no mutation in any of the two genes has been found to segregate in HNPCC families. Until there is better evidence for an increased colorectal cancer risk associated with germline mutations in these genes, a conservative interpretation of the role of mutations in these genes is advised.

Adenosine Triphosphatases↗
PubMed2001

A phosphatase associated with metastasis of colorectal cancer.

To gain insights into the molecular basis for metastasis, we compared the global gene expression profile of metastatic colorectal cancer with that of primary cancers, benign colorectal tumors, and normal colorectal epithelium. Among the genes identified, the PRL-3 protein tyrosine phosphatase gene was of particular interest. It was expressed at high levels in each of 18 cancer metastases studied but at lower levels in nonmetastatic tumors and normal colorectal epithelium. In 3 of 12 metastases examined, multiple copies of the PRL-3 gene were found within a small amplicon located at chromosome 8q24.3. These data suggest that the PRL-3 gene is important for colorectal cancer metastasis and provide a new therapeutic target for these intractable lesions.

Adenoma↗
PubMed2001

Secreted and cell surface genes expressed in benign and malignant colorectal tumors.

Serial analysis of gene expression was used to identify transcripts encoding secreted or cell surface proteins that were expressed in benign and malignant tumors of the colorectum. A total of 290,394 tags were analyzed from normal, adenomatous, and cancerous colonic epithelium. Of the 21,343 different transcripts observed, 957 were found to be differentially expressed between normal tissue and adenoma or between normal tissue and cancer. Forty-nine transcripts were elevated > or =20-fold in adenomas, 40 transcripts were elevated > or =20-fold in cancers, and 9 transcripts were elevated > or =20-fold in both. Products of six of these nine transcripts (TGFBI, LYS, RDP, MIC-1, REGA, and DEHL) were predicted to be secreted or to reside on the cell surface, and these were analyzed in more detail. The abnormal expression levels predicted by serial analysis of gene expression were confirmed by quantitative PCR analyses of each of these six genes. Moreover, the cell types responsible for the elevated expression were identified by in situ hybridization and by PCR analyses of epithelial cells immunoaffinity purified from primary tumors. This study extends knowledge of the differences in gene expression that underlie various stages of neoplasia and suggests specific diagnostic approaches that may be useful for the early detection of colorectal neoplasia.

Adenomatous Polyposis Coli↗
PubMed2001

Cell surface tumor endothelial markers are conserved in mice and humans.

We recently identified genes encoding tumor endothelial markers (TEMs) that displayed elevated expression during tumor angiogenesis. From both biological and clinical points of view, TEMs associated with the cell surface membrane are of particular interest. Accordingly, we have further characterized four such genes, TEM1, TEM5, TEM7, and TEM8, all of which contain putative transmembrane domains. TEM5 appears to be a seven-pass transmembrane receptor, whereas TEM1, TEM7, and TEM8 span the membrane once. We identified mouse counterparts of each of these genes, designated mTEM1, mTEM5, mTEM7, and mTEM8. Examination of these mTEMs in mouse tumors, embryos, and adult tissues demonstrated that three of them (mTEM1, mTEM5, and mTEM8) were abundantly expressed in tumor vessels as well as in the vasculature of the developing embryo. Importantly, expression of these mTEMs in normal adult mouse tissues was either undetectable or detected only in a small fraction of the vessels. These results demonstrate conservation of human and mouse tumor angiogenesis at the molecular level and support the idea that tumor angiogenesis largely reflects normal physiological neovasculaturization. The coordinate expression of TEM1, TEM5, and TEM8 on tumor endothelium in humans and mice makes these genes attractive targets for the development of antiangiogenic therapies.

Animals↗
PubMed2001

Detecting colorectal cancer in stool with the use of multiple genetic targets.

BACKGROUND: Colorectal cancer cells are shed into the stool, providing a potential means for the early detection of the disease using noninvasive approaches. Our goal was to develop reliable, specific molecular genetic tests for the detection of colorectal cancer in stool samples. METHODS: Stool DNA was isolated from paired stools and primary tumor samples from 51 colorectal cancer patients. Three genetic targets-TP53, BAT26, and K-RAS-were used to detect tumor-associated mutations in the stool prior to or without regard to the molecular analyses of the paired tumors. TP53 gene mutations were detected with a mismatch-ligation assay that detects nine common p53 gene mutations. Deletions within the BAT26 locus were detected by a modified solid-phase minisequencing method. Mutations in codons 12 and 13 of K-RAS were detected with a digital polymerase chain reaction-based method. RESULTS: TP53 gene mutations were detected in the tumor DNA of 30 patients, all of whom had the identical TP53 mutation in their stools. Tumors from three patients contained a noninherited deletion at the BAT26 locus, and the same alterations were identified in these patients' stool specimens. Nineteen of 50 tumors tested had a K-RAS mutation; identical mutations were detected in the paired stool DNA samples from eight patients. In no case was a mutation found in stool that was not also present in the primary tumor. Thus, the three genetic markers together detected 36 (71%) of 51 patients (95% confidence interval [CI] = 56% to 83%) with colorectal cancer and 36 (92%) of 39 patients (95% CI = 79% to 98%) whose tumors had an alteration. CONCLUSION: We were able to detect the majority of colorectal cancers by analyzing stool DNA for just three genetic markers. Additional work is needed to determine the specificity of these genetic tests for detecting colorectal neoplasia in asymptomatic patients and to more precisely estimate the prevalence of the mutations and sensitivity of the assay.

Aged↗
PubMed2001

Securin is required for chromosomal stability in human cells.

Abnormalities of chromosome number are the most common genetic aberrations in cancer. The mechanisms regulating the fidelity of mitotic chromosome transmission in mammalian cells are therefore of great interest. Here we show that human cells without an hSecurin gene lose chromosomes at a high frequency. This loss was linked to abnormal anaphases during which cells underwent repetitive unsuccessful attempts to segregate their chromosomes. The abnormal mitoses were associated with biochemical defects in the activation of separin, the sister-separating protease, rendering it unable to cleave the cohesin subunit Scc1 efficiently. These results illuminate the function of mammalian securin and show that it is essential for the maintenance of euploidy.

Amino Acid Sequence↗
PubMed2001

Short mononucleotide repeat sequence variability in mismatch repair-deficient cancers.

Mismatch repair-deficient cancers are characterized by widespread insertions and deletions in microsatellite sequences, including those comprised of mononucleotide repeats. Such alterations have been observed in relatively short mononucleotide tracts in several genes and often are interpreted to indicate that the affected genes normally act as tumor suppressors. To aid in the interpretation of such changes, we have systematically assessed their frequency within transcribed regions of the genome that are unlikely to play a tumorigenic role. The advent of the complete human genomic sequences of chromosome 22 allowed us to select 29 genes for this analysis, spaced at approximately 1-Mb intervals. Each of the selected genes had an (A)(8) or a (G)(8) tract deep within intronic sequences that was not included in the processed transcript. Surprisingly, we found that there was substantial variation in the prevalence of mutations among these tracts. Some tracts were altered in < 5% of the mismatch repair-deficient cancers studied, whereas other tracts were altered in nearly half of the cancers. In particular, (G)(8) tracts were considerably more prone to mutation than (A)(8) tracts, and the sequences or chromatin structures surrounding the mononucleotide tracts seemed to affect their mutability significantly.

Animals↗
PubMed2001

Carcinogen-specific induction of genetic instability.

It has been proposed recently that the type of genetic instability in cancer cells reflects the selection pressures exerted by specific carcinogens. We have tested this hypothesis by treating immortal, genetically stable human cells with representative carcinogens. We found that cells resistant to the bulky-adduct-forming agent 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) exhibited a chromosomal instability (CIN), whereas cells resistant to the methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) exhibited a microsatellite instability (MIN) associated with mismatch repair defects. Conversely, we found that cells purposely made into CIN cells are resistant to PhIP, whereas MIN cells are resistant to MNNG. These data demonstrate that exposure to specific carcinogens can indeed select for tumor cells with distinct forms of genetic instability and vice versa.

Blotting, Western↗
PubMed2001

Genetic disruption of PPARdelta decreases the tumorigenicity of human colon cancer cells.

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that have been implicated in a variety of biologic processes. The PPARdelta isotype was recently proposed as a downstream target of the adenomatous polyposis coli (APC)/beta-catenin pathway in colorectal carcinogenesis. To evaluate its role in tumorigenesis, a PPARdelta null cell line was created by targeted homologous recombination. When inoculated as xenografts in nude mice, PPARdelta -/- cells exhibited a decreased ability to form tumors compared with PPARdelta +/- and wild-type controls. These data suggest that suppression of PPARdelta expression contributes to the growth-inhibitory effects of the APC tumor suppressor.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Top-down morphogenesis of colorectal tumors.

One of the fundamental tenets of oncology is that tumors arise from stem cells. In the colon, stem cells are thought to reside at the base of crypts. In the early stages of tumorigenesis, however, dysplastic cells are routinely found at the luminal surface of the crypts whereas the cells at the bases of these same crypts appear morphologically normal. To understand this discrepancy, we evaluated the molecular characteristics of cells isolated from the bases and orifices of the same crypts in small colorectal adenomas. We found that the dysplastic cells at the tops of the crypts often exhibited genetic alterations of adenomatous polyposis coli (APC) and neoplasia-associated patterns of gene expression. In contrast, cells located at the base of these same crypts did not contain such alterations and were not clonally related to the contiguous transformed cells above them. These results imply that development of adenomatous polyps proceeds through a top-down mechanism. Genetically altered cells in the superficial portions of the mucosae spread laterally and downward to form new crypts that first connect to preexisting normal crypts and eventually replace them.

Base Sequence↗
PubMed2001

Mechanisms underlying losses of heterozygosity in human colorectal cancers.

Losses of heterozygosity are the most common molecular genetic alteration observed in human cancers. However, there have been few systematic studies to understand the mechanism(s) responsible for losses of heterozygosity in such tumors. Here we report a detailed investigation of the five chromosomes lost most frequently in human colorectal cancers. A total of 10,216 determinations were made with 88 microsatellite markers, revealing 245 chromosomal loss events. The mechanisms of loss were remarkably chromosome-specific. Some chromosomes displayed complete loss such as that predicted to result from mitotic nondisjunction. However, more than half of the losses were associated with losses of only part of a chromosome rather than a whole chromosome. Surprisingly, these losses were due largely to structural alterations rather than to mitotic recombination, break-induced replication, or gene conversion, suggesting novel mechanisms for the generation of much of the aneuploidy in this common tumor type.

Alleles↗
PubMed2001

Evidence that genetic instability occurs at an early stage of colorectal tumorigenesis.

Chromosomal instability is believed to be a common feature of most human tumors, but the stage at which such instability originates has not been defined. At the molecular level, chromosomal instability is characterized by allelic imbalance (AI), representing losses or gains of defined chromosomal regions. We have assessed AI in early colorectal tumors using newly developed methods for assessing AI in complex cell populations. A total of 32 adenomas of average size (2 mm; range, 1-3 mm) were studied. AI of chromosome 5q markers occurred in 55% of tumors analyzed, consistent with a gatekeeping role of the adenomatous polyposis coli tumor suppressor gene located at chromosomal position 5q21. AI was also detected in each of the other four chromosomes tested. The fractions of adenomas with AI of chromosomes 1p, 8p, 15q, and 18q were 10,19, 28, and 28%, respectively. Over 90% of the tumors exhibited AI of at least one chromosome, and 67% had allelic imbalance of a chromosome other than 5q. These findings demonstrate that AI is a common event, even in very small tumors, and suggest that chromosomal instability occurs very early during colorectal neoplasia.

Adenoma↗
PubMed2001

Transforming growth factor-beta-induced growth inhibition in a Smad4 mutant colon adenoma cell line.

Transforming growth factor-beta (TGF-beta) inhibits growth and induces apoptosis of colon epithelial cells. Binding of TGF-beta to its receptor induces phosphorylation of the Smad proteins Smad2 and Smad3, which then form heteromeric complexes with Smad4, translocate to the nucleus, and activate gene transcription. Smad4 function has been considered an obligate requirement for TGF-beta signaling, and Smad4 mutations present in some cancers have been considered sufficient to inactivate TGF-beta signaling. In this work, we describe studies with a nontransformed human colon epithelial cell line that is mutant for Smad4 but remains growth-inhibited by TGF-beta. The colon cell line VACO-235 has lost one of its Smad4 alleles via a chromosome 18q deletion. The remaining allele bears two missense point mutations located in regions important for Smad4 trimer formation, which is thought necessary for Smad4 function. As expected, pSBE4-BV/Luc, a Smad4-activated transcriptional reporter, was inactive in VACO-235. Nonetheless, VACO-235 demonstrated 80% growth inhibition in response to TGF-beta, as well as retention of some TGF-beta-mediated activation of the p3TP-Lux transcriptional reporter. Transient transfection of the VACO-235 Smad4 mutant allele into a Smad4-null cell line confirmed that this allele is functionally inactive as assayed by both the pSBE4-BV and p3TP-Lux reporters. The simplest explanation of these results is that there is a non-Smad4-dependent pathway for TGF-beta-mediated signaling and growth inhibition in VACO-235 cells.

Adenoma↗
PubMed2001

Mutation screening of the TNFRSF11A gene encoding receptor activator of NF kappa B (RANK) in familial and sporadic Paget's disease of bone and osteosarcoma.

Paget's disease of bone (PDB) is a common disorder characterized by focal areas of increased and disorganized osteoclastic bone resorption, leading to bone pain, deformity, pathological fracture, and an increased risk of osteosarcoma. Genetic factors play an important role in the pathogenesis of Paget's disease. In some families, the disease has been found to be linked to a susceptibility locus on chromosome 18q21-22, which also contains the gene responsible for familial expansile osteolysis (FEO)--a rare bone dysplasia with many similarities to Paget's disease. Insertion mutations of the TNFRSF11A gene encoding Receptor Activator of NF kappa B (RANK) have recently been found to be responsible for FEO and rare cases of early onset familial Paget's disease. Loss of heterozygosity (LOH) affecting the PDB/FEO critical region has also been described in osteosarcomas suggesting that TNFRSF11A might also be involved in the development of osteosarcoma. In order to investigate the possible role of TNFRSF11A in the pathogenesis of Paget's disease and osteosarcoma, we conducted mutation screening of the TNFRSF11A gene in patients with familial and sporadic Paget's disease as well as DNA extracted from Pagetic bone lesions, an osteosarcoma arising in Pagetic bone and six osteosarcoma cell lines. No specific abnormalities of the TNFRSF11A gene were identified in a Pagetic osteosarcoma, the osteosarcoma cell lines, DNA extracted from Pagetic bone lesions, or DNA extracted from peripheral blood in patients with familial or sporadic Paget's disease including several individuals with early onset Paget's disease. These data indicate that TNFRSF11A mutations contribute neither to the vast majority of cases of sporadic or familial PDB, nor to the development of osteosarcoma.

Adult↗
PubMed2001

PUMA induces the rapid apoptosis of colorectal cancer cells.

Through global profiling of genes that were expressed soon after p53 expression, we identified a novel gene termed PUMA (p53 upregulated modulator of apoptosis). The protein encoded by PUMA was found to be exclusively mitochondrial and to bind to Bcl-2 and Bcl-X(L) through a BH3 domain. Exogenous expression of PUMA resulted in an extremely rapid and profound apoptosis that occurred much earlier than that resulting from exogenous expression of p53. Based on its unique expression patterns, p53 dependence, and biochemical properties, PUMA may be a direct mediator of p53-associated apoptosis.

Amino Acid Sequence↗
PubMed2001

Counting alleles reveals a connection between chromosome 18q loss and vascular invasion.

The analysis of loss of heterozygosity (LOH) is perhaps the most widely used technique in cancer genetics. In primary tumors, however, the analysis of LOH is fraught with technical problems that have limited its reproducibility and interpretation. In particular, tumors are mixtures of neoplastic and nonneoplastic cells, and the DNA from the nonneoplastic cells can mask LOH. We here describe a new experimental approach, involving two components, to overcome these problems. First, a form of digital PCR was employed to directly count, one by one, the number of each of the two alleles in tumor samples. Second, Bayesian-type likelihood methods were used to measure the strength of the evidence for the allele distribution being different from normal. This approach imparts a rigorous statistical basis to LOH analyses, and should be able to provide more reliable information than heretofore possible in LOH studies of diverse tumor types.

Alleles↗