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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Humans show heterogeneous susceptibility to cancer development, suggesting the involvement of various genetic backgrounds in control of the production of endogenous carcinogens, the metabolism of carcinogens, the repair of DNA damage, cell proliferation and defence mechanisms including immune reactions. Gastric cancer is the major cancer in Japan. However, little is known about the genes linked with its development. In 1967, we found that N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induced gastric cancers in Wistar rats. Subsequently the Buffalo strain of rats was reported to be resistant to MNNG stomach carcinogenesis, while ACI rats were very sensitive. In a carcinogenesis study using F1 and F2 rats, we suggested that this trait of MNNG stomach carcinogenesis-resistance was regulated by a single autosomal dominant allele. The O6-methylguanine adduct levels in gastric mucosa induced by MNNG were the same in Buffalo and ACI rats, but cell proliferation induced by MNNG was much higher in ACI than Buffalo animals. Chromosome mapping of the gene responsible for susceptibility to MNNG-induced carcinogenesis is now in progress and its identification will hopefully give us clues to the involvement of genetic traits in susceptibility to gastric cancer in humans. In addition, the genetic background of susceptibility to breast cancer is also being studied. In Japan, about 5% of all cases of breast cancer are familial. We have studied BRCA1, the breast cancer susceptibility gene, as a determinant of susceptibility to breast cancer by linkage analyses in 11 families, but our results indicate that BRCA1 may not be important for development of familial breast cancer in Japanese.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Genetic polymorphisms and susceptibility to cancer development. 758 88

Recent investigations revealed that the 9p arm and 17q arm of human chromosomes harbour tumour suppressor genes (TSGs) with an important role in multistage carcinogenesis. At the 9p arm is located the p16 (MTS1) TSG and probably others with an effect on various human tumours such as acute lymphoblastic leukaemia, bladder cancer, gliomas, malignant mesotheliomas, melanomas and non-small cell lung carcinomas. In addition, the 17q arm harbours BRCA1 TSG which is responsible for approximately 80% of the familial breast/ovarian cancer cases. In order to investigate the implication of these performed a loss of heterozygosity (LOH) analysis with 10 polymorphic microsatellite markers (three at the 17q arm surrounding the BRCA1 region and seven at the 9p arm). Fourteen of the 17 (82%) tumours exhibited deletions at 9p. The highest incidence of LOH (6/13, 46%) was found for the marker D9S157 at 9p22. One sample exhibited deletion of all the informative markers tested indicating deletion of the complete 9p arm. No homozygous deletions were found. LOH at the 17q arm near the BRCA1 locus was found in 6 (35%) among 17 specimens. The results of this study indicate that allelic deletions at 9p are frequent in the development of laryngeal tumours. The highest incidence of LOH was found for the marker D9S157 which is near, but distinct from the location of p16 (MTS1) tumour suppressor gene, indicating the presence of multiple tumour suppressor genes within this chromosomal region. In addition, BRCA1 TSG is implicated in the development of laryngeal tumours.
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PMID:Loss of heterozygosity at 9p and 17q in human laryngeal tumors. 758 72

Various gene systems are involved in events occurring during transformation of a normal cell into a cancer cell. By order of intervention, genes responsible for an increased individual susceptibility to cancer can be distinguished from actual cancer genes, followed by genes involved at other levels of carcinogenesis. 15 to 20% of patients with breast cancer have a first-degree relative affected by the same cancer, although an inherited predisposition to cancer is only established in 4 to 10% of cases. The genetic heterogeneity of familial forms of breast cancer make it difficult to identify susceptibility genes. At the present time, 3 regions of the genome have been implicated in the predisposition to breast cancer in women: the BRCA1 gene, the BRCA2 gene and the TP53 gene. All predisposition genes are able to transmit susceptibility due to a mutation or inherited microdeletion.
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PMID:[Genetics and cancer: application to the breast]. 779 27

The BRCA1 gene on chromosome 17q21 is responsible for an autosomal dominant syndrome of increased susceptibility to breast and ovarian cancer but no somatic mutations in tumours have yet been described. To study the potential role of BRCA1 in sporadic carcinogenesis, we analysed the genomic DNA of tumour and normal fractions of 47 ovarian cancers for mutations in BRCA1 using the single-strand conformation polymorphism technique. We now describe somatic mutations in the DNA of four tumours which also had loss of heterozygosity (LOH) at a BRCA1 intragenic marker. Our data support a tumour suppressor mechanism for BRCA1; somatic mutations and LOH may result in inactivation of BRCA1 in at least a small number of ovarian cancers.
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PMID:Somatic mutations in the BRCA1 gene in sporadic ovarian tumours. 779 52

Linkage analysis in familial breast and ovarian cancer and studies of allelic deletion in sporadic ovarian tumors have identified a region on chromosome 17q containing a candidate tumor-suppressor gene (referred to as BRCA1) of likely importance in ovarian carcinogenesis. We have examined normal and tumor DNA samples from 32 patients with sporadic and 8 patients with familial forms of the disease, for loss of heterozygosity (LOH) at 21 loci on chromosome 17 (7 on 17p and 14 on 17q). LOH on 17p was 55% (22/40) for informative 17p13.1 and 17p13.3 markers. When six polymorphic markers flanking the familial breast/ovarian cancer susceptibility locus on 17q12-q21 were used, LOH was 58% (23/40), with one tumor showing telomeric retention. Evaluation of a set of markers positioned telomeric to BRCA1 resulted in the highest degree of LOH, 73% (29/40), indicating that a candidate locus involved in ovarian cancer may reside distal to BRCA1. Five of the tumors demonstrating allelic loss for 17q markers were from individuals with a strong family history of breast and ovarian cancer. More important, two of these tumors (unique patient number [UPN] 57 and UPN 79) retained heterozygosity for all informative markers spanning the BRCA1 locus but showed LOH at loci distal to but not including the anonymous markers CMM86 (D17S74) and 42D6 (D17S588), respectively. Deletion mapping of seven cases (two familial and five sporadic) showing limited LOH on 17q revealed a common region of deletion, distal to GH and proximal to D17S4, that spans approximately 25 cM. These results suggest that a potential tumor-suppressor gene involved in both sporadic and familial ovarian cancer may reside on the distal portion of chromosome 17q and is distinct from the BRCA1 gene.
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PMID:A common region of deletion on chromosome 17q in both sporadic and familial epithelial ovarian tumors distal to BRCA1. 794 44

Multiple chromosome 17 loci may be involved in ovarian carcinogenesis. Fifty-seven sporadic ovarian epithelial tumors were examined for loss of heterozygosity at 15 loci on chromosomes 17p. Eighty % (39 of 49) of informative tumors had allelic loss in 17p13.3 at D17S30, D17S28, or both loci within this region, including 3 of 7 tumors of low malignant potential and 4 of 5 nonmetastatic carcinomas. The smallest region of overlapping deletions extends from D17S28 to D17S30, a distance of 15 kb. Furthermore, several tumors have breakpoints within the region detected by the D17S30 probe. Chromosome 17p13.3 genes with potential tumor suppressor function include HIC-1, DPH2L (N. J. Phillips et al. Isolation of a human diphthamide biosynthesis gene on chromosome 17p13.3, submitted for publication)/OVCA1, PEDF, and CRK. The HIC-1 coding sequence lies i kb centromeric to the D17S28-S17S30 region of deletion (M. Makos Wales et al., Nat. Med., 1:570-577, 1995) but remains a candidate because 5'-regulatory elements may lie within the critical region. Portions of the DPH2L/OVCA1 coding sequence lie within the D17S28-D17S30 interval. Somatic cell hybrid analysis places PEDF in an interval including D17S28, D17S30, and D17S54, whereas CRK is excluded from this interval. Chromosome 17p13.3 loss precedes TP53 and BRCA1 region deletions because the latter changes are see only in high-stage carcinomas. Microsatellite instability plays only a minor role in sporadic ovarian carcinogenesis because only 1 of 57 tumors showed this finding.
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PMID:Allelic deletion on chromosome 17p13.3 in early ovarian cancer. 856 79

To investigate the putative role of BRCA1, a gene involved in hereditary breast and ovarian cancer, in sporadic ovarian tumors among Japanese women, we examined 76 unselected primary ovarian cancers for mutations in the coding region of BRCA1 using the single-strand conformation polymorphism technique. Although no somatic mutations were detected in any of the tumors, constitutional mutations were identified in four cases: two frameshifts, one nonsense mutation and one intronic base substitution 32 bp downstream of exon 22; RT-PCR experiments revealed that the single-base substitution in the intron seemed to increase the transcript lacking exon 22. All four cases were judged to involve truncation of the gene product. The evidence reported here supports a rather limited role of BRCA1 in ovarian carcinogenesis in the Japanese population.
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PMID:Mutation analysis of the BRCA1 gene in 76 Japanese ovarian cancer patients: four germline mutations, but no evidence of somatic mutation. 859 20

Predisposing germline mutations in the BRCA1 gene were identified recently in families with 17 q-linked breast and ovarian cancers. Using single-strand conformation polymorphism (SSCP) analysis, we examined primary breast cancers for mutations in coding exons of BRCA1 in a panel of 103 patients, of whom all either represented early-onset cases (< 35 of age), were members of multiply-affected families, and/or had developed bilateral breast cancers. Mutations were detected in tumors from four patients, all of whom had developed breast cancers bilaterally: a frame-shift due to a 2-bp deletion at codon 797; a nonsense mutation at codon 1214; and two missense mutations, one at codon 271 leading to Val-->Met substitution, and the other at codon 1150 leading to Pro-->Ser substitution. In each case the same mutation was present in constitutional DNA. The mean age of onset was 49 years among the Japanese carriers of BRCA1 mutations identified in this study, in contrast to the mean age of 35 observed among carriers of BRCA1 mutations in a similar U.S. study (Futreal et al., 1994). The evidence reported here supports a rather limited role of BRCA1 in breast carcinogenesis.
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PMID:Mutations in the BRCA1 gene in Japanese breast cancer patients. 872 83

The breast cancer gene BRCA1 has previously been cloned from both human and mouse. We cloned a fragment of the rat Brca1 homologue in order to map it and explore its biological function. Partial cDNA fragments of the rat Brca1 homologue were isolated by RT-PCR. Sequence analysis revealed that the RING-finger domain is well conserved among rat, mouse and human. Rat Brca1 mRNA was expressed in most tissues studied with the highest level in testis, consistent with studies in human and mouse. Next, intron 6-containing DNA fragments were amplified by PCR from WKY and WF rat strains. The splicing sites between exon 6 and exon 7 are conserved between rat and human. Partial sequencing of the rat Brca1 intron 6 revealed a polymorphism of a pentanucleotide TTTTG repeat between the WKY and WF strains. With this intragenic microsatellite marker, we were able to map precisely the rat Brca1 gene to chromosome 10 using a genetic linkage study of (WKY x WF)F1 x WF backcross rats. Brca1 cosegregates with marker BAND3A, and is flanked by R5123 and R5842. Using this polymorphic marker, we also investigated the loss of heterozygosity (LOH) of the Brca1 microsatellite marker in carcinogen- or radiation-induced mammary carcinomas in (WF x F344)F1 female rats. No LOH or somatic microsatellite instability was detected in 18 DMBA-induced tumors studied. Only one LOH of the F344 allele was observed in 26 radiation-induced tumors tested. Ribonuclease protection assays demonstrated that Brca1 mRNA levels are similar in normal rat mammary glands and mammary carcinomas of various etiologies, including those induced by DMBA, NMU, activated-neu and activated-ras oncogenes.
Carcinogenesis 1996 Aug
PMID:Cloning, genetic mapping and expression studies of the rat Brca1 gene. 876 10

The etiology of breast cancer involves a complex interplay of exogenous and endogenous factors, including genetic factors. The identification of oncogenes, tumor suppressor genes and human mismatch repair genes has helped to refine the characterization of breast carcinogenesis. The major types of genetic alterations in breast cancer are amplification of protooncogenes (ERBB2 and MYC) and DNA from chromosome band 11q13; mutation of p53; and loss of heterozygosity on 1p, 3p, 8p, 11p, 13q, 16q, 17p, 17q, 18q. The latter may imply inactivations of tumor suppressor genes. Recently, two distinct familial breast cancer susceptibility genes, BRCA1 and BRCA2, have been isolated. These findings enable to use these genes for genetic diagnosis in clinical oncology.
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PMID:[Cytogenetic abnormalities, genetic alterations, and applications for genetic diagnosis in breast cancer]. 897 25


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