title: Methylation in p14(ARF) is frequently observed in colorectal cancer with low-level microsatellite instability.
abstract: Colorectal cancer (CRC) can be classified as high-level microsatellite instability (MSI-H), low-level MSI (MSI-L) and microsatellite stable (MSS) depending on levels of MSI. MSI-H CRC relies on a distinct molecular pathway due to the mismatch repair (MMR) deficiency and shows methylation in multiple gene promoters. The genetic pathway leading to MSI-L is unknown, although higher levels of promoter methylation are observed in this group compared with MSS CRCs. This study explored how promoter methylation affects MSI phenotype, by analysing the methylation status of eight CRC-related promoters, MSI phenotype and KRAS/BRAF mutations in a series of 234 CRCs. Promoter methylation of p14(ARF) was significantly related to MSI-L CRC with KRAS mutation. The MSI-H phenotype was related to methylation of MLH1 as expected, while the MSS phenotype was related to methylation of p16(INK4a) and O(6)-methylguanine-DNA methyltransferase, although this was not statistically significant. Thus, promoter methylation of p14(ARF) could be a significant alteration leading to CRC with MSI-L.
authors.affiliation: Department of Gastroenterological Surgery and Surgical Oncology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kominami
authors.forename: T
authors.initials: T
authors.lastname: Nagasaka
authors.forename: H M
authors.initials: HM
authors.lastname: Cullings
authors.forename: N
authors.initials: N
authors.lastname: Hoshizima
authors.forename: H
authors.initials: H
authors.lastname: Sasamoto
authors.forename: J
authors.initials: J
authors.lastname: Young
authors.forename: B A
authors.initials: BA
authors.lastname: Leggett
authors.forename: N
authors.initials: N
authors.lastname: Tanaka
authors.forename: N
authors.initials: N
authors.lastname: Matsubara
mesh_terms: D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D020868:Gene Silencing; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D053842:Microsatellite Instability; D012150:Polymorphism, Restriction Fragment Length; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics* / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics
chemical_list: D004273:DNA, Neoplasm; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D025803:Tumor Suppressor Protein p14ARF; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins