Study On Aberrant Promoter Methylation Of CHFR And RUNX3 Gene In Gastric Cancer

Objective In this study, the methylation level of CHFR and RUNX3 genes promoter in gastric carcinoma tissues, 5cm adjacent nonmalignant gastric mucosa tissues and normal gastric mucosa, pre-operative and post-operative serum, were detected by combination of methylation-specific polymerase chain reaction (MSP) and combined bisulfite restriction analysis (COBRA), and to explore the relationship between the aberrant methylation of these two genes and the clinical parameters of the gastric cancer. Then, we compare the difference of MSP and COBRA on the methylation detecting of tumor suppressor gene in gastic cancer.Methods Patients diagnosed as primary gastric cancer without receiving any radiotherapy or chemotherapy before operation were collected. A total of 123 carcinoma specimens, the matched neighboring tissues during their surgical resection, and thirty normal gastric mucosa were collected as control group.78 pre-operative and corresponding post-operative sera were taken from the patients. The techniques of MSP and COBRA was adopted to investigate the promoter methylation of CHFR gene in 64 carcinoma specimens .Results1. The aberrant methylation of CpG islands of CHFR gene promoterThe positive rate of methylation of CHFR gene was found to be 41.5% (51/123) in gastric cancer tissues,11.4% (14/123) in the matched neighboring tissues and 0% (0/30) in normal gastric mucosa.The positive rate of methylation of CHFR gene in the former group was significantly higher than that in the latter two groups (P<0.05).The positive rate of methylation of CHFR gene from degree of histological differentiation G3/G4 carcinoma tissues was significantly higher than that from the tissues samller than G1/G2 (P<0.05). And the positive rate of methylation of CHFR gene from diameter lager than 5cm was significantly higher than that from the tissues samller than 5cm (P<0.05). While no significant difference was found in other clinical parameters including the age, gender, invasion depth, stage of pathology and the involvement of lymph node from the carcinoma specimens group (P>0.05).The positive rate of methylation of CHFR gene was found to be 20.5% (16/78) in pre-operative serum of gastric cancer, 2.6% (2/78) in the matched post-operative serum. The positive rate of methylation of CHFR gene in the former group was significantly higher than that in the latter two groups (P<0.05). And the positive rate of methylation of CHFR gene in serum had significant consistency with carcinoma specimens(P<0.05, Kappa value is 0.521).2. The aberrant methylation of CpG islands of RUNX3 gene promoterThe positive rate of methylation of RUNX3 gene was found to be 55.3% (68/123) in gastric cancer tissues, 9.8% (12/123) in the matched neighboring tissues and 0% (0/30) in normal gastric mucosa. The positive rate of methylation of RUNX3 gene in the former group was significantly higher than that in the latter two groups (P<0.05).The positive rate of methylation of RUNX3 gene from invasion depth T3/T4 carcinoma tissues was significantly higher than that from the tissues samller than T1/T2 (P<0.05). And the positive rate of methylation of RUNX3 gene from diameter lager than 5cm was significantly higher than that from the tissues samller than 5cm (P<0.05). While no significant difference was found in other clinical parameters including the age, gender, degree of histological differentiation, stage of pathology and the involvement of lymph node from the carcinoma specimens group (P>0.05). The positive rate of methylation of RUNX3 gene was found to be 28.2% (22/78) in pre-operative serum of gastric cancer, 2.6% (2/78) in the matched post-operative serum. The positive rate of methylation of RUNX3 gene in the former group was significantly higher than that in the latter two groups (P<0.05). And the positive rate of methylation of RUNX3 gene in serum had significant consistency with carcinoma specimens(P<0.05, Kappa value is 0.377).3.Comparison of the results of promoter methylation of CHFR gene between MSP and COBRA.There was no significant difference was found on the result of promoter methylation of CHFR gene between MSP and COBRA in 64 gastric cancer tissue specimens(P>0.05).Conclusions1. The aberrant CpG islands methylation of CHFR and RUNX3 gene promoter were existed both in carcinoma specimens and matched serum.. It indicated that the aberrant CpG islands methylation of CHFR and RUNX3 involved during the occurrence and development of gastric cancer. Combined detection of multi-TSG would contribute the diagnosis of gastric cancer on the clinic.2. Methylation of the promoter CpG islands of CHFR genes is significant associated with the degree of histological differentiation, indicating that aberrant methylation of this gene can used as a sensitive referred parameter on the evaluation of degree of histological differentiation in gastric cancer.3. Aberrant promoter CpG islands methylation of RUNX3 gene is significant associated with the invasion depth of gastric cancer. It can be a good parameter to evaluate the invasion depth of gastric cancer. 4. Aberrant promoter CpG islands methylation of RUNX3 and CHFR gene of gastric cancer specimens was significantly correlated with the tumor size. It can be used to evaluate the growth of gastric cancer in gastric cancer.5. There was no significant difference was found on the result of promoter methylation of TSG between MSP and COBRA.It is feasible to compare the results of promoter methylation of TSG of different experiment using different methods.