title: Genetic and epigenetic profiling in early colorectal tumors and prediction of invasive potential in pT1 (early invasive) colorectal cancers.
abstract: Morphologically, early colorectal tumors are divided into two groups, protruded-type tumors and flat-type tumors. Although some studies have shown genetic alterations in protruded-type tumors, little is known about genetic and epigenetic alterations in flat-type tumors, as well as pT1 (early invasive) colorectal cancers (CRCs). In the current study, we compared the frequencies of genetic and epigenetic alterations of the RAS-RAF and Wnt signaling pathways in flat-type and protruded-type tumors. In addition, we investigated the relationship between those alterations and invasive potential of pT1 CRCs. Methylations of RASSF2, O-6-methylguanine-DNA methyltransferase (MGMT), Wnt inhibitory factor-1 (WIF-1), EPHB2, CDKN2A and MLH1 were detected in 44.3, 30.3, 81.4, 7.5, 43.6 and 13.4% of the 307 early colorectal tumors, respectively. Mutations of KRAS, BRAF, catalytic subunit alpha of phosphatidylinositol 3'-kinase (PIK3CA) and beta-catenin were detected in 25.4, 4.6, 1.6 and 9.4% of those tumors, respectively. Methylations of MGMT, WIF-1 and CDKN2A were detected in significantly higher percentages of protruded-type tumors than in flat-type tumors. Mutation of at least one gene was detected in a significantly higher percentage of flat-type tumors than in protruded-type tumors. RASSF2 methylation was correlated significantly with KRAS, BRAF or PIK3CA mutation. Multiple logistic analysis showed that lymphatic invasion and RASSF2 methylation with KRAS, BRAF or PIK3CA mutation were independent risk factors for venous invasion in pT1 CRCs. In conclusion, since genetic alterations of these pathways have frequently occurred in flat-type tumors, flat-type tumors seem to have a distinct genetic profile different from that of protruded-type tumors. RASSF2 methylation with oncogenic activation is a promising biomarker for predicting invasive potential of pT1 CRCs.
authors.affiliation: First Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan. nosho@sapmed.ac.jp
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Nosho
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Taiga
authors.initials: T
authors.lastname: Takahashi
authors.forename: Masashi
authors.initials: M
authors.lastname: Mikami
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Nobuki
authors.initials: N
authors.lastname: Miyamoto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Adachi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Arimura
authors.forename: Fumio
authors.initials: F
authors.lastname: Itoh
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Shinomura
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011237:Predictive Value of Tests; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics; D051153:Wnt Proteins / Q000235:genetics / Q000502:physiology; D018631:ras Proteins / Q000235:genetics / Q000502:physiology
chemical_list: D051153:Wnt Proteins; D019908:Proto-Oncogene Proteins c-raf; D018631:ras Proteins