Cooperative Treatment of Gastric Cancer Using B7-H7 siRNA and Docetaxel; How Could They Modify Their Effectiveness?

PURPOSE: Despite the high prevalence of gastric cancer (GC), drug resistance is a major problem for effective chemotherapy. B7-H7 is a novel member of the B7 superfamily and is expressed in most common cancers. However, the role of B7-H7 on the aggressiveness of GC and chemosensitivity has remained unknown. Therefore, this study was designed to assess the effect of B7-H7 suppression using small interference RNA (siRNA) in combination with docetaxel on GC cells. METHODS: MTT test was applied to determine the IC50 of docetaxel and the combined effect of B7-H7 siRNA and docetaxel on the viability of the MKN-45 cells. To determine B7-H7, BCL-2, BAX, and caspase-3-8-9 genes expression, qRT-PCR was performed. Furthermore, flow cytometry was applied to evaluate apoptosis and the cell cycle status. Finally, to evaluate the effect of this combination therapy on migratory capacity and colony-forming ability, wound healing assay and colony formation test were employed, respectively. RESULTS: B7-H7 suppression increased the chemo-sensitivity of MKN-45 cells to docetaxel. The expression of B7-H7 mRNA was reduced after using B7-H7 siRNA and docetaxel in MKN-45 GC cells. Also, B7-H7 suppression alongside docetaxel reduced cell migration and colony formation rate, arrested the cell cycle at the G2-M phase, and induced apoptosis by modulating the expression of apoptotic target genes. CONCLUSION: B7-H7 plays a significant role in the chemo-sensitivity and pathogenesis of GC. Therefore, B7-H7 suppression, in combination with docetaxel, may be a promising therapeutic approach in treating GC.