ABSTRACT
The development of colorectal cancer (CRC) spans about 5-10 years, making early detection and prevention beneficial to the survival of CRC patients. To address inconsistencies in evidence regarding O(6)-methylguanine-DNA-methyltransferase (MGMT) methylation as a potential prognostic factor in CRC, we conducted a meta-analysis to evaluate MGMT methylation in CRC patients. Fourteen studies were included in the meta-analysis after screening 120 articles. The following items were collected from each study: author, published year, country, patient gender, MGMT methylation status, and patients' disease progression. Pooled hazard ratios and odd ratios with 95% confidence intervals (CIs) were calculated using fixed or random effect models depending on the heterogeneity between studies. The overall survival of CRC patients was found not to be significantly associated with MGMT methylation. Further subgroup analysis showed that the frequency of MGMT methylation was significantly higher in CRC than in normal tissues (p < 0.00001). MGMT promoter in CRC patients was more frequently methylated than in adenoma patients. In addition, MGMT methylation was significantly increased in adenoma than in normal tissues (p < 0.0001). In conclusion, MGMT methylation is central to the development of cancer that involves a stepwise carcinogenesis of normal adenoma carcinoma cascade. However, MGMT methylation is not associated with the prognosis of CRC.
Subject(s)
Colorectal Neoplasms/diagnosis , Colorectal Neoplasms/genetics , DNA Methylation , DNA Modification Methylases/genetics , DNA Repair Enzymes/genetics , Tumor Suppressor Proteins/genetics , Adenoma/diagnosis , Adenoma/genetics , Biomarkers, Tumor/genetics , Carcinoma/diagnosis , Carcinoma/genetics , Humans , Prognosis , Promoter Regions, GeneticABSTRACT
OBJECTIVE: To investigate the methylation in promtor region of RASSF2 and sFRP1 in sporadic colorectal cancer patients in order to provide screening method for early colorectal cancer. METHODS: The methylation in promoter region of RASSF2 and sFRP1 in serum samples of 59 sporadic colorectal cancer patients and 59 healthy volunteers was detected by methylation specific PCR. The association between clinicopathological features of sporadic colorectal cancer patients and methylation in promoter region of RASSF2 and sFRP1 was analyzed. RESULTS: The methylation rates of RASSF2 and sFRP1 gene in serum of 59 sporadic colorectal cancer patients were 27.1% and 30.5%, significantly higher than those in healthy volunteers(0%, both P<0.01). The methylation of RASSF2 or sFRP1 occurred in 29(49.2%) patients, which was significantly higer than the methylation rate of single gene(P<0.05). No association was found between methylation ratio of RASSF2 and sFRP1 and clinicopathological features in sporadic colorectal cancer patients. CONCLUSIONS: Methylation in promoter region of RASSF2 and sFRP1 is often detected in serum of colorectal cancer patients. The combination detection of methylation for the two genes may provide information for early screening of colorectal cancer.
