CHFR promoter hypermethylation in colon cancer correlates with the microsatellite instability phenotype

Abstract

A subset of sporadic colon cancers has been shown to have microsatellite instability caused by an epigenetic inactivation of the MLH1 gene by hypermethylation of the the CpG island in its promoter region. We report here that in colorectal cancer, inactivation of the MLH1 gene is frequently accompanied by hypermethylation of the CpG island in the promoter of the mitotic gene checkpoint with forkhead and ring finger domains (CHFR). This was first observed in the colon cancer cell lines HCT-116, DLD-1, RKO and HT29. Among the 61 primary colon cancer samples studied, hypermethylation of the MLH1 and the CHFR promoter was found in 31% of the tumors. In 68% of all primary cancers (13/19) with MLH1 promoter hypermethylation, hypermethylation of the CHFR promoter was observed as well (P-value < 0.0001, Fisher's two-sided exact). Hypermethylation of the HLTF, MGMT, RASSF1, APC, p14 and p16 promoter regions were also frequent events, being observed in 48% (28/58), 40% (26/64), 21% (14/64), 50% (31/62), 43% (26/60) and 56% (35/63), respectively. However, methylation of these genes was not associated with methylation of either MLH1 or CHFR. The observed methylation profile was unrelated to Duke's stage. The coordinated loss of both mismatch repair caused by methylation of MLH1 and loss of checkpoint control associated with methylation of CHFR suggests the potential to overcome cell cycle checkpoints, which may lead to an accumulation of mutations.

Association of interindividual differences in p14ARF promoter methylation with single nucleotide polymorphism in primary colorectal cancer

“…We detected p14 ARF promoter methylation in 32% of the colorectal cancers exam- ined, a range of frequency that has been reported previously. 3,10,11,17,18 Our data suggest that 2 SNPs at positions 24256 and 21477 of the p14 ARF gene were associated with the p14 ARF methylation phenotype, which indicates that the interindividual differences in susceptibility to p14 ARF promoter methylation may be ascribed to genetic variants around the p14 ARF promoter region. The 2 SNPs were in strong LD (|D 0 | 5 0.99; r 2 5 0.95), and haplotype analysis suggests that the variant C allele at the 24256 locus and the variant A allele at the 21477 locus may play a role in hypermethylation of the p14 ARF promoter.…”

Optimal primer design using the novel primer design program: MSPprimer provides accurate methylation analysis of the ATM promoter

“…The most frequently used methods are bisulfite sequencing (Frommer et al, 1992), COBRA assay (Xiong and Laird, 1997), methylation-specific PCR (MSP) (Herman et al, 1996) and nested MSP, which allows the amplification of even heavily fragmented DNA from paraffin-embedded tissue (Brandes et al, 2005). Optimal primer design is critical to achieve reliable results, and must take several factors into account that might jeopardize specific and robust amplification: (a) PCR primers must overlap non-CpG cytosines to amplify specifically only bisulfite converted sequences and not any non-converted DNA which is present after nearly every bisulfite reaction.…”

Sequential gene promoter methylation during HPV-induced cervical carcinogenesis

“…To the best of our knowledge, this is the first study showing methylation of CHFR to be associated with cervical carcinogenesis. CHFR promoter methylation has, however, been described in other types of cancer, such as breast (Tokunaga et al, 2006), gastric (Kang et al, 2004) and colorectal cancer (Brandes et al, 2005).…”