Objective  To investigate the diagnostic value of the promoter methylation of plasma RNF180 gene and its protein expression for the detection of gastric cancer.

  Methods  Methylation-specific polymerase-chain reaction (MSP) and enzyme-linked immuno-sorbent assay (ELISA) were performed to detect DNA methylation and protein expression of the RNF180 gene, respectively. The correlations of DNA methylation and protein expression of the RNF180 gene with the clinico-pathological parameters of gastric carcinoma were then separately analyzed.

  Results  MSP showed that the methylation rates of the RNF180 gene were 62.75% and 21.88% in the plasma of patients with gastric carcinoma and healthy volunteers, respectively; this result indicated that the two groups significantly differed (P < 0.01). The methylation of the RNF180 gene was associated with tumor size, clinical stage, tumor differentiation, lymph node metastasis, and distant metastasis (P < 0.05). ELISA results showed that the protein expression of the RNF180 gene (23.22 ± 1.36) μg/mL was significantly lower (P < 0.01) in the plasma of patients with gastric carcinoma than in the plasma of healthy volunteers (34.25 ± 2.44) μg/mL. However, the protein expression of the RNF180 gene was not associated with clinicopathological parameters (P>0.05).

  Conclusion  The RNF180 gene is expressed at a hypermethylation rate, and the corresponding protein expression level is decreased in the plasma of individuals with gastric carcinoma. Therefore, RNF180 gene methylation in plasma could be applied to detect microinvasion for the clinical diagnosis of gastric cancer.