Correlation Of Aberrant Methylation Of P16, APC Gene To MTHFR, TS Genetic Polymorphisms In Hepatic Carcinoma

Object:To investigate the association between aberrant hypermethylation of p16,APC gene and folate, vitamin B12, methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase(TS) genetic polymorphisms in Hepatic Carcinoma.Method:Paired samples of peripheral blood, tumorous and coresponding non-tumorous tissues were obtained from Affiliated Hospital of Qingdao University Medical College from June 2008 to June 2009. The methylation of p16,APC gene and MTHFR gene polymorphisms were analyzed by Real-time quantitative polymerase chain reaction (Real-time PCR). TS gene polymorphisms was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).The levels of folate and vitamin B12 in plasma were measured by Electro-Chemiluminescence Immunoassay (ECLI).Results:1. The aberrant hypermethylation rate of p16 gene in tumorous tissues and coresponding plasma was significantly higher than that in non-cancer tissues (χ2=67.48,37.50,p<0.05), and it is significantly higher in tumorous tissues than that in plasma(x2=6.72,p<0.05). The concordance of p16 genes in tumorous tissues and plasma was 65.4%2. The aberrant hypermethylation rate of APC gene in tumorous tissues showed significantly higher than that in non-cancer tissues(x2=18.03,p<0.05), whereas plasma showed no significant. The aberrant hypermethylation rate of APC gene in tumorous tissues showed significantly greater than that in plasma (x2=29.16,p<0.05), the concordance of them was 43.3%.3. Aberrant methylation of p16 was associated with HBsAg. Patients with positive HBsAg had greater significantly methylation frequencies(x2=5.60,5.67,p<0.05).4. Compared with the group of unmethylated p16 gene.the levels of folate showed significantly lower in tumorous tissues with methylated group(p<0.05), whereas the vitamin B12 showed not significantly(p>0.05). And in plasma, the levels of folate and vitamin B12 showed significantly lower in methylated p16 gene group (p<0.05). The levels of folate and vitamin B12 showed no significance in APC gene both in tumorous tissues and plasma(p>0.05).5. Compared with the MTHFR 677CC genotype, the odds ratio (OR) and 95% confidence interval (95% CI) of p16 and APC gene with MTHFR 677T allele were 3.47(1.06-11.37)and 3.64(1.13-11.79)(p<0.05).6. Compared with the MTHFR 1298AA genotype, the OR and 95% CI of APC gene with MTHFR 1298C allele were 0.32(0.11-0.92) (p<0.05), whereas, there was no significant difference between aberrant methylation of p16 gene and MTHFR A1298C gene polymorphism(p>0.05).7. There were no significant difference between aberrant methylation of p16,APC gene and TS 5'-UTR gene polymorphism(p>0.05).Conclution:1. Methylation of p16 gene in plasma, as a non-invasive detection method, maybe showed some significance in Hepatic Carcinoma diagnosis.2. HBsAg may be related to p16 gene promoter methylation. It maybe increase the risk of p16 gene methylation.3. p16 gene methylation may be related to folate and vitamin B12, whereas APC may be not.4. MTHFR 677T allele maybe increase the risk of methylation of p16 and APC gene, whereas MTHFR 1298C allele maybe decrease the risk of methylation of APC gene. There were no significant difference between aberrant methylation of p16,APC gene and TS 5'-UTR gene polymorphism.