Expression Of Protocadherin-10(PCDH10) In Tissue And Plasma Of Gastric Cancer And Its Clinical Significance

Objective and Background: To detect the levels of PCDH10 gene promoter DNA methylation and expression of protein of PCDH10 in gastric cancer and adjacent normal tissue; and to investigate the relationship between the clinicopathological features and levels of PCDH10 gene promoter DNA methylation and protein expression of PCDH10 genes of gastric cancer, and analysis the relationship between protein expression of PCDH10 and prognosis in patients with gastric cancer, and to estimate PCDH10 gene in plasma between the gastric cancer and normal plasma.Methods: January 2008 to December 2009, Tianjin Medical University Cancer Hospital and surgical resection in patients with gastric cancer tissues and adjacent normal tissues were 109 cases were Collected. Methylation-specific polymerase chain reaction(MSP) and bisulfite genomic sequencing method, were used to detect the PCDH10 promoter hypermethylation of gastric cancer and adjacent normal tissues in qualitative and quantitative analysis, respectively. Western blotting(western-blot) was used to detect the expression of PCDH10 protein of gastric cancer and adjacent normal tissues quantitatively, and further methylation-specific polymerase chain reaction(MSP) were used to detect the expression levels of PCDH10 gene DNA in plasma of 68 gastric cancer patients and 20 normal human plasma. The relationship between expression of PCDH10 and various clinicopathological factors were evaluated.Results: 1. The rate of PCDH10 gene promoter methylation in gastric tumor tissues(40/50, 80%) were higher than in normal tissue tissues(6/48, 12.5%), and there were statistically significantly(P <0.01) between them.2. Methylated Cp G site count of 109 GC patients ranged between 0 and 27. PCDH10 promoter methylation was found in 99 patients(90.83%) presented with 1 or more hypermethylated Cp G sites, and 10 patients(9.17%) presented with hypomethylated Cp G site. According to the cut-off point of methylated Cp G site count, 29 patients(26.60%) presented 4 or less hypermethylated Cp G sites and 80(73.40%)patients presented 5 or more hypermethylated Cp G sites. univariate analysis showed PCDH10 status and number of PCDH10 gene promoter Cp G island methylation sites were prognostic factors of gastric cancer, multivariate analysis showed like the traditional number of tumor size, lymph node metastasis, number of PCDH10 gene promoter Cp G island methylation sites is also an independent prognostic factor in gastric cancer.3. Western Blotting showed that: The positive expression rate of PCDH10 protein in 109 gastric cancer tissues was lower than those in the adjacent normal tissues(37.6% VS 88.1%). the difference was statistically significant(P <0.05). PCDH10 protein expression in gastric cancer tissue was significantly associated with lymph node status, Tumor size, depth of invasion and TNM stage(P<0.05).4. The 5-year survival rate of positive expression of 41 cases PCDH10 protein was 63.4%, while 68 cases with negative expression of PCDH10 protein was 30.9%.there has a significant difference(P <0.05). Univariate analysis showed: prognosis of gastric cacner related to tumor size(P <0.001), depth of invasion(P = 0.002), lymph node metastasis(P <0.001), TNM stage(P <0.001) and the expression of PCDH10(P <0.001). Multivariate analysis showed: lymph node metastasis, tumor sizeand expression of PCDH10 were independent prognostic factor(P <0.05) of gastric cancer patients.5. MSP method shows that 42(65.5%) of 64 cases in plasma of gastric cancer appeared promoter methylation, but in normal human plasma, the rate of PCDH10 promoter hypermethylation is lower.Conclusion: 1. The levels of PCDH10 gene promoter methylation is higher than normal tissues compared with adjacent normal tissue decreased expression at the protein level, suggesting PCDH10 is likely to be a tumor suppressor gene.2. After radical surgery, the level of PCDH10 expression was independent prognostic factor in patients with gastric cancer. It can be measured in the plasma levels, is likely to be a predictor of gastric cancer patients.