Comethylation of p16 and MGMT genes in colorectal carcinoma:Correlation with clinicopathological features and prognostic value

作     者：Koviljka Krtolica Milena Krajnovic Slavica Usaj-Knezevic Dragan Babic Dusan Jovanovic Bogomir Dimitrijevic 

作者机构：Laboratory for Radiobiology and Molecular Genetics Institute of Nuclear Sciences "Vinca" P. O. BOX 522 Belgrade Serbia Institute of OncologySremska KamenicaSerbia Institute for Medical Statistics of Medical UniversityBelgradeSerbia 

出 版 物：《World Journal of Gastroenterology》 (世界胃肠病学杂志（英文版）)

年 卷 期：2007年第13卷第8期

页      面：1187-1194页

核心收录：

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

基　　金：Supported by the grant 143010 from the Ministry of Science and Environment Protection of the Republic of Serbia 

主　　题：结直肠癌 p16基因 MGMT基因 共甲基化 临床病理特征 相关性 

摘      要：AIM: To investigate the significance of p16 and O6- methylguanine-DNA methyltransferase (MGMT) genes promoter hypermethylation and K-ras mutations on colorectal tumorigenesis and progression. METHODS: p16 and MGMT methylation status was examined on 47 tumor samples, and K-ras mutational status was examined on 85 tumor samples. For methylation analysis, a methylation specific PCR (MS-PCR) method was used. RESULTS: p16 and MGMT promoter methylation was found in 51% (24/47) and 43% (20/47) of CRCs, respectively, and the K-ras mutation was found in 44% (37/85) of CRCs. Comethylation of p16 and MGMT genes was significantly associated with lower aggressiveness of the disease within a two-year period of observation. Only 27% of patients with simultaneous p 16 and MGMT methylation showed the detectible occurrence of metastasis and/or death, compared to 67% of patients without double methylation or with no methylation (3/11 vs 22/33, P 0.05, χ2-test). In addition, p16 and MGMT comethylation showed a trend toward an association with longer survival in patients with CRCs (35.5 ± 6.0 mo vs 23.1 ± 3.2 mo, P = 0.072, Log-rank test). Progression of the disease within a two-year period was observed in 66% of patients carrying the K-ras mutation, compared to only 19% of patients with wild type K-ras (29/44 vs 7/37, P 0.001, χ2-test). The presence of the K-ras mutation significantly correlated to shortened overall survival (20.0 ± 1.9 mo vs 37.0 ± 1.8 mo, P 0.001, Log-rank test). The comethylation of p16 and MGMT genes was significantly associated with lower aggressiveness of the disease even when K-ras mutations were included in the analysis as an independent variable. CONCLUSION: Our data suggest that comethylation of promoters of p 16 and MGMT genes could have a prognostic value in patients with CRC. Specifically, concurrent methylation of both genes correlates with better prognosis.