Defects in MMR genes are known to be crucial for familial form of colorectal cancer but our findings suggest that specific genetic variations in MLH1 are important also in the individual predisposition to sporadic colon cancer.
Microsatellite instability is prone to occur in sporadic right colon carcinoma during tumor growth and is not associated significantly with mutations in the hMLH1 and hMSH2 mismatch repair genes or in the p53 gene.
The expression of hMLH1, hMSH2, hMSH6, and hPMS2 in the resected tumor tissues was examined by SP immunohistochemistry, in order to analyze the relationship between defective DNA MMR (dMMR) and the clinico-pathological features and prognosis of colon cancer.
A total of 864 tumors from individuals with colon cancer from Utah and Northern California were evaluated by methylation-specific polymerase chain reaction of CpG islands in hMLH1, methylated in tumors (MINT) 1, MINT 2, MINT 31, and CDKN2A (p16).
In patients with colon cancer, miR-449a expression was inversely correlated with disease-free survival and histological scores and was positively correlated with the expression of MLH1 for which loss-of function mutations have been shown to be involved in colon cancer.
We have studied the possible interactions between the mismatch repair system and p53 in a human colon cancer cell line, HCT-116 (known to have a homozygous mutation in mismatch repair gene hMLH1 on chromosome 3) and in a clone obtained after insertion of a single copy of chromosome 3 (HCT-116+ ch3).
This retrospective cohort study comprised 79 carriers of germline mutation in a MMR gene (18 MLH1, 55 MSH2, 4 MSH6, and 2 PMS2) from the Colon Cancer Family Registry who had had a proctectomy for index rectal cancer.
While a colon cancer from the same individual showed MSI, the BC specimen was MSI-negative, indicating that development of the latter tumor was unrelated to MMR impairment, despite presence of a constitutional MLH1 mutation.Hum Mutat 17:521, 2001.
We have studied MSI, somatic mutations in repeat-containing genes, DNA-ploidy, and cytogenetic aberrations in a colon carcinoma from a patient with a germline MLH1 mutation.
We have tested several cell lines from both MMR-deficient and MMR-proficient groups using this method, including a colon carcinoma cell line HCT116 with defective hMLH1 gene and a derivative complemented by transient transfection with hMLH1 cDNA.
Our results show that germline mutations of hMSH2 and hMLH1 genes contribute to a significant fraction of familial predisposition to colon cancer cases that do not fulfil all diagnostic criteria of HNPCC.
Recently, the aberrant hypermethylation of the hMLH1 promoter and its consequent transcriptional silencing has been shown to be a common event in the formation of sporadic microsatellite unstable colon cancer.
Here we report the first proven de novo germ line mutation in MLH1 (c.666dupA) identified in a 31-year-old colorectal cancer patient with the alteration being present in a heterozygous state in all three germ layers and homozygously in his colon cancer.
Colon cancer tissue was assayed using immunohistochemistry for expression of hMLH1 and hMSH2, and a panel of five pairs of microsatellite primers (NR21, NR22, NR24, BAT25, and BAT26) for MSI-H analysis and additional dinucleotide markers (D17S250, D5S346, and D2S123) used for MSI-L.
We obtained data from the Colon Cancer Family Registry for a cohort of 127 women who had a diagnosis of endometrial cancer and who carried a mutation in one of four MMR genes (30 carried a mutation in MLH1, 72 in MSH2, 22 in MSH6, and 3 in PMS2).
A family history of breast/ovarian, HNPCC or colon cancer in a first degree relative was found in 40% of fallopian, 20% of biliary, 35% of pancreatic, 27% of urothelial and 20% of small bowel cancer patients.
The most common hereditary colon cancer susceptibility condition, Lynch syndrome (LS), previously known as hereditary nonpolyposis colorectal cancer, is an autosomal dominant condition caused by a germline mutation in 1 of 4 DNA mismatch repair (MMR) genes: MLH1, MSH2, MSH6, or PMS2.
Risk of metachronous CRC was estimated for 382 MMR gene mutation carriers (172 MLH1, 167 MSH2, 23 MSH6 and 20 PMS2) from the Colon Cancer Family Registry, who had surgery for their first colon cancer, using retrospective cohort analysis.