Undetectable expression of hMLH1 protein in sporadic colorectal cancer with replication error phenotype

Koike, Junki; Yamada, Kazuo; Takano, Shoichi; Kikuchi, Yoshinori; Hemmi, Hiromichi; Koi, Minoru; Tsujita, Kazunori; Yanagita, K.; Terada, Yoshio; Shimatake, Hiroyuki

doi:10.1007/bf02062016

Cited by 11 publications

(8 citation statements)

References 23 publications

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“…Specific monoclonal or polyclonal antibodies for p53 , gastric and intestinal mucin (gastric mucin, mouse monoclonal antibody NCL‐HGM‐45M1; intestinal mucin; mouse monoclonal antibody NCL‐MUC‐2; Novocastra, Newcastle, UK), hMLH1 (clone G168–728; Pharmingen, San Diego, CA, USA) and hMSH2 25 were used with the avidin–biotin–peroxidase technique 12,26 . We defined grades as follows: +, more than 50% of the cancer cells showing clear positive staining in comparison with the background and the negative control; −, more than 90% of the cancer cells showing no staining (that is, specimens could not be differentiated from the background and negative control); +/−, borderline specimens.…”

Section: Methodsmentioning

confidence: 99%

Microsatellite instability of papillary subtype of human gastric adenocarcinoma and hMLH1 promoter hypermethylation in the surrounding mucosa

Guo

Arai

Kitayama

et al. 2001

Pathology International

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Gastric cancer has striking heterogeneity in histological pattern, cellular phenotype, genotype, biomarkers, and biological behavior. We focused on the specific morphological papillary phenotype of gastric adenocarcinoma and attempted to identify its distinct molecular characteristics. In our comparative study, early stage papillary (papillary-dominant) gastric cancer showed a significantly higher and more widespread high-frequency microsatellite instability (MSI-H) than other morphological types. Analysis of mutations in a panel of five putative microsatellite instability (MSI)-associated genes in the MSI-H cases revealed that papillary or papillary-dominant cancer displays a unique profile of mutations compared to profiles previously reported in gastric cancer. Immunohistochemical staining and methylation analysis revealed that silencing of hMLH1 by methylation in its promoter region was responsible for the failure of mismatch repair in papillary-type gastric cancer, whereas aberrant promoter methylation of hMLH1 was not found in any cases without the unique mutator phenotype. Promoter hypermethylation of the hMLH1 genes was found to a lesser degree in the adjacent non-tumor mucosa in four of the 10 cases with tumor having the mutator phenotype. Microsatellite instability itself could not be detected in the adjacent non-tumor mucosa. Inactivation of hMLH1 expression by promoter hypermethylation may be an early event in carcinogenesis of this type of gastric cancer, preceding the development of the clear MSI phenotype of papillary carcinoma.

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Section: Methodsmentioning

confidence: 99%

Microsatellite instability of papillary subtype of human gastric adenocarcinoma and hMLH1 promoter hypermethylation in the surrounding mucosa

Guo

Arai

Kitayama

et al. 2001

Pathology International

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“…Mismatch repair defects are the basis for the microsatellite instability found in hereditary nonpolyposis colorectal cancer (HNPCC) and in a significant fraction of sporadic colorectal cancers and certain other sporadic tumors [Ionov et al, 1993;Fishel et al, 1993;Parsons et al, 1993;Peltomaki et al, 1993;Thibodeau et al, 1993;Aaltonen et al, 1994;Umar et al, 1994;Li and Modrich, 1995]. The majority of these defects are in the hMLH1 or hMSH2 genes [Bronner et al, 1994;Hemminki et al, 1994;Koike et al, 1997;Benanchenhou et al, 1998;Cunningham et al, 1998;Guerrette et al, 1998;Herman et al, 1998]. …”

Section: Introductionmentioning

confidence: 98%

Mutation frequency analysis of mononucleotide and dinucleotide repeats after oxidative stress

Yamada

Parker

Farber

2003

Environ and Mol Mutagen

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Many tumors exhibit genetic instability at the DNA sequence level in the form of frameshift mutations in simple repeats (microsatellite instability). A high level of microsatellite instability, such as that seen in hereditary nonpolyposis colorectal cancer (HNPCC), arises from defects in the mismatch repair pathway. A low level of microsatellite instability is found in some non-HNPCC-associated cancers, such as those of the breast and lung, and is not attributable to mismatch repair defects. We hypothesized that oxidative DNA damage may be at least partly responsible for the generation of microsatellite mutations in these tumors. We investigated whether oxidative DNA damage can induce microsatellite mutations in mismatch repair-proficient cultured cells. Telomerase-immortalized normal human fibroblasts were stably transfected with a plasmid containing a tk-neo fusion gene, such that the neo coding region was placed out of frame by the presence of an upstream microsatellite sequence. Cells were treated with H(2)O(2) and mutation frequencies were determined for G(17), A(17), and (CA)(17) repeats. Mutation frequencies of mononucleotide repeats in cells with the neo gene in the (+1) reading frame were reduced after treatment. No effect was observed in cells with the mononucleotide repeats in the (-1) reading frame. A small increase in mutation frequency was observed in cells with the (CA)(17) repeat. Our data suggest that diploid human cells may have protective mechanisms that prevent the induction of microsatellite mutations by a short exposure to high levels of oxidative stress.

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“…The dashed lines show the relative amount of probe À107C or À107G required to bind the same amount of nuclear protein À107G allele is insufficient to evaluate the difference of clinicopathological properties between À107C and À107G patients. For the MSI status, tumors of two patients had the microsatellite stable (MSS) phenotype and one had an MSI-H phenotype, which was due to hMSH2 deficiency (Koike et al 1997. Thus, although the À107G allele was found only in the cancer population, the correlation between hMLH1 repression exerted by the À107G substitution and the carcinogenesis of these patients remains to be elucidated.…”

Section: Clinicopathological Properties Of Tumors With à107g Allelementioning

confidence: 98%

“…We have previously investigated expression of hMSH2 and hMLH1 proteins in tumor tissues of colorectal cancer patients (Koike et al 1997Zhong et al 2001). We found that approximately 6-7% of cases had reduced or absent hMLH1 protein and mRNA expression.…”

Section: Introductionmentioning

confidence: 98%

A Single Nucleotide Substitution (−107C → G) in the hMLH1 Promoter Found in Colorectal Cancer Population Reduces Transcriptional Activity

et al. 2007

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Inactivation of the DNA mismatch repair gene hMLH1 predisposes one to colorectal cancer. We have identified a C to G nucleotide substitution at position -107 relative to the hMLH1 gene translation initiation site in three of 163 colorectal cancer patients with an allele frequency of 0.0092 (3/326). One of the three -107G alleles occurred in one patient out of five with reduced hMLH1 expression in the tumor tissue. The -107G was not found in 63 healthy individuals. This substitution reduced transcriptional activity by 51% compared with -107C (P<0.01) and impeded the promoter-binding capacity of nuclear proteins. Although the small number of identified -107G alleles is insufficient to evaluate the contribution to the carcinogenesis and clinicopathological properties of the tumors, the effects of -107G on hMLH1 gene transcription and nuclear protein binding to the promoter sequence implicate the site, including -107C, as a crucial element interacting with the activator that maintains hMLH1 gene expression.

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Undetectable expression of hMLH1 protein in sporadic colorectal cancer with replication error phenotype

Abstract: hMLH1 protein was undetectable in the two tumor tissues of the six replication error-positive samples of sporadic colorectal cancer. The detection procedure used here may have potential use for determining a dysfunctional mismatch repair gene product.

Cited by 11 publications

References 23 publications

Microsatellite instability of papillary subtype of human gastric adenocarcinoma and hMLH1 promoter hypermethylation in the surrounding mucosa

Microsatellite instability of papillary subtype of human gastric adenocarcinoma and hMLH1 promoter hypermethylation in the surrounding mucosa

Mutation frequency analysis of mononucleotide and dinucleotide repeats after oxidative stress

A Single Nucleotide Substitution (−107C → G) in the hMLH1 Promoter Found in Colorectal Cancer Population Reduces Transcriptional Activity

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