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Macroscopic morphologic subtypes of laterally spreading colorectal tumors showing distinct molecular alterations
Author(s) -
Sugimoto Takafumi,
Ohta Miki,
Ikenoue Tsuneo,
Yamada Atsuo,
Tada Motohisa,
Fujishiro Mitsuhiro,
Ogura Keiji,
Yamaji Yutaka,
Okamoto Makoto,
Kanai Fumihiko,
Kawabe Takao,
Omata Masao
Publication year - 2010
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.25180
Subject(s) - kras , loss of heterozygosity , familial adenomatous polyposis , immunohistochemistry , colorectal cancer , adenomatous polyposis coli , pathology , univariate analysis , cancer research , biology , gene mutation , gene , microbiology and biotechnology , mutation , medicine , cancer , genetics , allele , multivariate analysis
Abstract Recent advances in colonoscopic techniques have resulted in more frequent detection of superficial‐type colorectal tumors, that is, laterally spreading tumors (LSTs), although little is known about the characteristic clinical features and genetic alterations of LSTs. To elucidate the molecular characteristics of LSTs, genetic alterations in the KRAS , BRAF and PIK3CA genes and abnormal expression of the p53, β‐catenin and MYC proteins were analyzed using direct DNA sequencing and immunohistochemistry for 50 protruded‐type tumors (Protruded), 35 granular‐type LSTs (LST‐G) and 19 nongranular‐type LSTs (LST‐NG). In addition, loss of heterozygosity (LOH) close to the adenomatous polyposis coli ( APC ) gene (5q21) was examined in these tumors. In univariate analyses, significant differences were noted in the percentages with KRAS mutations (Protruded, LST‐G, LST‐NG = 30.0%, 54.3%, 21.1%, respectively, p = 0.0156), nuclear accumulation of β‐catenin (Protruded, LST‐G, LST‐NG = 50.0%, 37.1%, 68.4%, respectively, p = 0.0267), expression of MYC (Protruded, LST‐G, LST‐NG = 26.0%, 17.1%, 42.1%, respectively, p = 0.0456) and LOH at the APC gene locus (Protruded, LST‐G, LST‐NG = 22.0%, 20.0%, 47.4%, respectively, p = 0.0302). Multivariate analysis demonstrated that the macroscopic subtype of LST was significantly associated with KRAS mutation (for LST‐NG: odds ratio [OR] 0.23, 95% CI 0.06–0.90) and nuclear accumulation of β‐catenin (for LST‐NG: OR 4.05, 95% CI 1.11–14.8). Our data revealed that the 2 subtypes of LST have different molecular characteristics, suggesting that 2 or more different molecular mechanisms result in colorectal tumors with a similar growth pattern.