Expression Of HINT1 And Epigenetic Mechanism In Gastric Cancer

Objective: To study the expression and clinical significance of HINT1 in gastric cancer cases, and explore potencial mechanism in gastric cancer.Methods: The Real-time fluorescent quantitative PCR analysis was used to detect the expression level of Hint1 in 34 gastric cancer ( GC ) and adjacent non-tumor cancers, and statistical analyze the Hint1 expression between tumor group and non-tumor group. The relationship between the expression patterns of Hint1 and corresponding clinical pathology information was analysed by the expression level observing in cases. The infection of Hp and EB was detected by RT-PCR in tumor and non-tumor tissues, and the relationship of Hint1 expression and the infection situation was analysed.The HINT1 protein was detected in 51 GCs and matched non-tumor tissues by Western blot, and the relationship between HINT1 expression and corresponding clinical pathology information was analyzed. Statistical analysis of HINT1 expression in Hp/EB infection or uninfection group was analyzed in tumor and adjacent non-tumor tissues. Immunohistochemistry was used to show immunostaining in gastric mucosal cells in five poorly differentiation cases and five moderately differentiation cases, and then analysed the correlation between HINT1 expression and differentiation.The level of HINT1 was detected by RT-PCR and Western blot in four GC cell lines and a normal gastric mucosal cell line. The Hint1 low expression GC cell line AGS was treated by epigenetic drug 5-Aza-dC and then detected the restored expression after treatment.The methylation of the promoter region of the Hint1 was detected by MSP in GCs and matched non-tumor tissues.Results: Decreased expression of HINT1 detected by qPCR and Western blot in tumor tissues was 58.82% and 39.2%, respectively. Significant reduced expression of HINT1 was found in poorly differentiated tumor tissues ( p = 0.027 ). Environmental interference ( either Hp or EB infection ) ( p = 0.005 ) affected the expression of HINT1.Representative examples of HINT1 expression in adjacent non-cancerous tissues showed expression of the HINT1 in both tumor cell nuclei and cytoplasm by Immunohistochemistry. GC tissue with moderately differentiation displayed expression of the HINT1 in both tumor cell nuclei and cytoplasm while GC tissue with poorly differentiation showed lack of expression in tumor cells. We treated AGS cells, a low expression HINT1 GC cell line, with 5μmol/L and 10μmol/L 5-Aza-dC for 72 h and found HINT1 could be induced by 5-Aza-dC and was dose-dependent. The data implied that decreased expression of HINT1 in human GC cell line AGS may also, at lease in part, due to methylation of the promoter region of the Hint1 gene.Representative examples of MSP showed methylation in GCs and unmethylation in matched non-tumor tissues.Conclusion: In conclusion, the present study revealed that low HINT1 expression may be correlated with biological aggressiveness and poor prognosis in gastric cancer, and involved in environmental factors such as Hp/EB infection. Inactive Hint1 due to DNA methylation of promoter may play a role in gastric tumorigenesis. The result of MSP showed low Hint1 expression in GC may be correlated with methylation status of the promoter region.