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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gene changes in multiple oncogenes, multiple growth factors and multiple tumor-suppressor genes are observed in stomach cancer. Among them, those most commonly implicated in both well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma are inactivation (mutations and allele loss) of the p53 gene, and activation (abnormal expression and amplification) of the c-met gene. Moreover, they occur at an early stage of stomach carcinogenesis. In addition, loss of heterozygosity (LOH) on chromosome 5q (APC locus) is frequently associated with well-differentiated adenocarcinoma. LOH on chromosome 18q (DCC locus) and LOH of the bcl-2 gene also are common events of well-differentiated adenocarcinoma. LOH on chromosomes 1q and 7q may be involved in the progression of well-differentiated adenocarcinoma. Conversely, the development of poorly differentiated adenocarcinoma, in addition to changes in p53 and c-met genes, requires reduction or dysfunction of cadherin. Overexpression of bcl-2 protein is observed in poorly differentiated adenocarcinoma or signet-ring cell carcinoma. Moreover, the K-sam gene is amplified preferentially in poorly differentiated adenocarcinoma of scirrhous carcinoma. K-sam amplification in scirrhous carcinoma often occurs independently of c-met gene amplification. LOH on chromosome 1p also is relatively common in poorly differentiated adenocarcinoma. Exceptionally, signet-ring cell carcinoma shares APC mutations. There are some differences in expression of the growth-factor/receptor system between well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma. Moreover, interaction between cell-adhesion molecules in tumor cells expressing c-met and hepatocyte growth factor (HGF) from stromal cells is linked with morphogenesis of two histological types of stomach cancer. Intestinal metaplasia and adenoma of the stomach also contain p53 mutations and K-ras mutations or tpr-met rearrangement. Taken together, different genetic pathways of stomach carcinogenesis may exist for poorly differentiated and well-differentiated stomach cancers. Some of the latter may develop by a cumulative series of gene alterations similar to those of colorectal cancer.
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PMID:Molecular mechanism of stomach carcinogenesis. 844 Jul 43

Lung cancers exhibit multiple genetic lesions including mutations activating the dominant cellular proto-oncogenes as well as those inactivating the recessive or "tumor suppressor" genes. Candidate tumor suppressor genes include those on chromosomes 1p, 1q, 3p14, 3p21.3, 3p25 (VHL gene), 5q21 (APC/MCC gene cluster), 9p21-22 (interferon gene cluster), 11p, 13q (rb gene), 16p24, and 17p (p53 gene). Mutations in p53 inactivate its transcriptional activity, while replacement of a wild-type p53 in lung cancer cells inhibits growth and tumorigenicity suggesting that p53 acts as a master growth regulatory switch. Lung cancer cells exhibit several positive autocrine growth factor loops and express nicotine receptors which could function as tumor promoting systems. In addition, they express a negative autocrine loop involving opioids and their receptors which is reversed by nicotine acting through nicotinic acetylcholine receptors. The presence of nicotine receptors suggests nicotine or its metabolites may play a direct role in lung cancer pathogenesis.
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PMID:The molecular biology of lung cancer pathogenesis. 846 39

Two distinct gene classes have been implicated in colorectal carcinogenesis. Tumour promoter genes (oncogenes, dominant oncogenes) produce an excessive positive stimulus to cell proliferation. The ras family of oncogenes are an example. Acquired mutations of the c-k-ras gene are commonly found in colonic adenomas and carcinomas. Tumour suppressor genes (anti-oncogenes, recessive oncogenes) normally constrain or regulate cell proliferation. Loss of this function through gene deletion or mutation is oncogenic. Inherited tumour suppressor gene mutations have now been identified in several of the familial cancer syndromes. Acquired tumour suppressor gene mutations are found in both sporadic and hereditary cancers. Together with the tumour promoter genes they provide the genetic basis for the cellular changes occurring during carcinogenesis. The retinoblastoma gene was the first human tumour suppressor gene to be characterized and exemplifies the class. More recently, linkage studies in the hereditary cancer syndromes and the detection of specific deletions in sporadic tumours have helped to identify several new tumour suppressor genes. At least four of these (MCC, APC, p53 and DCC) apparently contribute to sporadic colorectal carcinogenesis. Germ line APC mutations produce the inherited colorectal cancer syndrome familial adenomatous polyposis (FAP). Detection of these mutations using linked markers has already found clinical application in the screening of families with this disease. In the future, genetic diagnosis of hereditary non-polyposis colorectal cancer (HNPCC) and the recognition of those genetically susceptible to sporadic colorectal cancer may become possible. At the same time, as our understanding of the genes involved improves, new avenues for treatment and prevention of colorectal cancer may emerge.
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PMID:Tumour suppressor genes and colorectal neoplasia. 847 56

Both 17p and 5q allelic losses appear to be involved in the pathogenesis or progression of many human solid tumors. In colon carcinogenesis, there is strong evidence that the targets of the 17p and 5q allelic losses are TP53, the gene encoding p53, and APC, respectively. It is widely accepted that 5q allelic losses precede 17p allelic losses in the progression to colonic carcinoma. The data, however, supporting this proposed order are largely based on the prevalence of 17p and 5q allelic losses in adenomas and unrelated adenocarcinomas from different patients. We investigated the order in which 17p and 5q allelic losses developed during neoplastic progression in Barrett esophagus by evaluating multiple aneuploid cell populations from the same patient. Using DNA content flow cytometric cell sorting and polymerase chain reaction, 38 aneuploid cell populations from 14 patients with Barrett esophagus who had high grade dysplasia, cancer or both were evaluated for 17p and 5q allelic losses. 17p allelic losses preceded 5q allelic losses in 7 patients, both 17p and 5q allelic losses were present in all aneuploid populations of 4 patients, and only 17p (without 5q) allelic losses were present in the aneuploid populations of 3 patients. In no patient did we find that a 5q allelic loss preceded a 17p allelic loss. Our data suggest that 17p allelic losses typically occur before 5q allelic losses during neoplastic progression in Barrett esophagus.
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PMID:Clonal ordering of 17p and 5q allelic losses in Barrett dysplasia and adenocarcinoma. 847 62

A predisposition to colorectal cancer is shown to be linked to markers on chromosome 2 in some families. Molecular features of "familial" cancers were compared with those of sporadic colon cancers. Neither the familial nor sporadic cancers showed loss of heterozygosity for chromosome 2 markers, and the incidence of mutations in KRAS, P53, and APC was similar in the two groups of tumors. Most of the familial cancers, however, had widespread alterations in short repeated DNA sequences, suggesting that numerous replication errors had occurred during tumor development. Thirteen percent of sporadic cancers had identical abnormalities and these cancers shared biologic properties with the familial cases. These data suggest a mechanism for familial tumorigenesis different from that mediated by classic tumor suppressor genes.
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PMID:Clues to the pathogenesis of familial colorectal cancer. 848 15

The biology of colorectal cancer is discussed in terms of multistage carcinogenesis. Colorectal cancer evolves through the stepwise acquisition of mutations at certain critical genetic loci, many of which have been identified recently. The earliest step in the neoplastic pathway is a shift of proliferation from the normally restricted zone at the base of the colonic crypt and the retention of cells capable of proliferation at the top of the colonic crypt. This appears to be mediated by a mutation in the APC gene. The adenoma, a collection of benign neoplastic cells, is the first pathologically recognizable neoplastic lesion. Adenomas may grow or involute. Additional genetic lesions, such as a mutation in the Ki-ras gene, contribute to the growth and progressive dysplasia of the adenoma. Critical lesions in the p53 gene appear to be responsible for malignant transformation and the appearance of genetic instability of the neoplastic cell, which greatly increases the likelihood that additional genetic events will occur that contribute to a progressively more aggressive neoplastic phenotype. Genetic and phenotypic diversity develop within the primary malignant tumor, and metastasis occurs as a consequence of a complex series of events. Opportunities for detection and therapeutic intervention in colorectal neoplasia are discussed in this framework.
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PMID:The biology of colorectal cancer. Implications for pretreatment and follow-up management. 850 77

More than 70 cell lines were established from esophageal cancer, including 15 TE-series cell lines established by the authors. This article reviews molecular and cellular features of esophageal cancer cells from studies using these cell lines as well as primary tumors. The subjects reviewed include primary cultures of normal epithelium of the esophagus and of esophageal tumors, their growth and differentiation properties, chromosomal aberrations, protein kinase C, growth factors and their receptors, oncogenes, and tumor-suppressor genes. Lesions of genetic loci in esophageal cancer include the absence of mutations in ras genes in primary tumors, amplification and overexpression of the c-erbB gene, co-amplification of hst-1 and int-2 genes, mutations, and allelic loss of tumor suppressor genes, p53, Rb, APC, and MCC. Future clinical improvement will be achieved on the basis of the understanding of molecular and cellular features of esophageal cancer cells.
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PMID:Molecular and cellular features of esophageal cancer cells. 850 34

We examined 24 human bladder cancer tissues for possible mutations in the entire coding region of the human DNA polymerase beta gene using polymerase chain reaction analysis, single-strand conformational polymorphism analysis of RNA, and sequence analysis. DNA polymerase beta gene mutations were observed in four of the 24 cases (16.7%) and included three missense point mutations and a single base insertion. The single base insertion was also observed in our previous study of human prostate cancer, suggesting that this region may be a hot spot for mutation of the DNA polymerase beta gene. No clinical or pathological association was found among the four cases that contained the mutation. Three of the four cases with DNA polymerase beta gene mutation had mutations of the p16 or RB genes or loss of heterozygosity of the p53 and APC gene loci. The results of the study presented here suggest that DNA polymerase beta gene mutations, in combination with mutations of tumor suppressor genes, may be involved in certain cases of human bladder cancer.
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PMID:DNA polymerase beta gene mutations in human bladder cancer. 856 64

The predisposition to colon cancer is multigenetically controlled in animals and probably also in humans. We have analyzed the multigenic control of susceptibility to 1,2-dimethylhydrazine-induced colon tumors in mice by using a set of 20 homozygous CcS/Dem recombinant congenic strains, each of which contains a different random subset of approximately 12.5% of genes from the susceptible strain STS/A and 87.5% of genes from the relatively resistant strain BALB/cHeA. Some CcS/Dem strains received the alleles from the susceptible strain STS/A at one or more of the multiple colon tumor susceptibility loci and are susceptible, whereas others are resistant. Linkage analysis shows that these susceptibility genes are different from the mouse homologs of the genes known to be somatically mutated in human colon cancer (KRAS2, TP53, DCC, MCC, APC, MSH2, and probably also MLH1). Different subsets of genes control tumor numbers and size. Two colon cancer susceptibility genes, Scc1 and Scc2, map to mouse chromosome 2. The Scc1 locus has been mapped to a narrow region of 2.4 centimorgans (90% confidence interval).
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PMID:Fine mapping of colon tumor susceptibility (Scc) genes in the mouse, different from the genes known to be somatically mutated in colon cancer. 857 18

Prostate cancer is the most common cancer in aged men. Although ras and p53 gene mutations have been detected in some prostate cancers, the major genetic alterations involved in its carcinogenesis are not well understood. Mutation of the APC gene is responsible for colorectal tumors in which ras and p53 mutations are also often involved. Using PCR-SSCP analysis and sequencing, we examined 31 human primary prostate cancers (three cases at stage A, 10 at stage B, five at stage C and 13 at stage D) and four cases of lymph node metastasis from the stage D cases, for mutations in the APC gene. A mutation was detected in only one of the 35 samples (3%). This mutation, present in a primary stage B cancer, had a T to C transition in exon 15 at the first position of codon 956, resulting in substitution of histidine for tyrosine. This study clarified that APC gene mutations are not largely involved in the development of clinical prostate cancer.
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PMID:APC gene mutations in human prostate cancer. 860 98


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