Promoter methylation of ITF2, but not APC, is associated with microsatellite instability in two populations of colorectal cancer patients. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Savio, Andrea; Daftary, Darshana; Dicks, Elizabeth; Buchanan, Daniel; Parfrey, Patrick; Young, Joanne; Weisenberger, Daniel; Green, Roger; Gallinger, Steven; McLaughlin, John; Knight, Julia; Bapat, Bharati
• Is Part Of: BMC cancer. Volume 16:Issue 1(2016)
• Page Start: 1
• Page End: 11
• Publication Date: 2016-12
• Subjects: Colorectal cancer -- DNA methylation -- Microsatellite instability -- Wnt signaling -- MethyLight; Cancer -- Periodicals; 616.994005
• DOI: 10.1186/s12885-016-2149-9
• Languages: English
• ISSNs: 1471-2407

Abstract

Abstract Background Aberrant Wnt signaling activation occurs commonly in colorectal carcinogenesis, leading to upregulation of many target genes. APC (adenomatous polyposis coli) is an important component of the β-catenin destruction complex, which regulates Wnt signaling, and is often mutated in colorectal cancer (CRC). In addition to mutational events, epigenetic changes arise frequently in CRC, specifically, promoter hypermethylation which silences tumor suppressor genes.APC and the Wnt signaling target geneITF2 (immunoglobulin transcription factor 2) incur hypermethylation in various cancers, however, methylation-dependent regulation of these genes in CRC has not been studied in large, well-characterized patient cohorts. The microsatellite instability (MSI) subtype of CRC, featuring DNA mismatch repair deficiency and often promoter hypermethylation ofMutL homolog 1 (MLH1 ), has a favorable outcome and is characterized by different chemotherapeutic responses than microsatellite stable (MSS) tumors. Other epigenetic events distinguishing these subtypes have not yet been fully elucidated. Methods Here, we quantify promoter methylation ofITF2 andAPC by MethyLight in two case-case studies nested in population-based CRC cohorts from the Ontario Familial Colorectal Cancer Registry (n = 330) and the Newfoundland Familial Colorectal Cancer Registry (n = 102) comparing MSI status groups. Results ITF2 andAPC methylation are significantly associated with tumor versus normal state (bothP < 1.0×10-6 ).ITF2 is methylated in 45.8 % of MSI cases and 26.9 % of MSS cases and is significantly associated with MSI in Ontario (P = 0.002) and Newfoundland (P = 0.005) as well as the MSI-associated feature ofMLH1 promoter hypermethylation (P = 6.72×10-4 ).APC methylation, although tumor-specific, does not show a significant association with tumor subtype, age, gender, or stage, indicating it is a general tumor-specific CRC biomarker. Conclusions This study demonstrates, for the first time, MSI-associatedITF2 methylation, and further reveals the subtype-specific epigenetic events modulating Wnt signaling in CRC.