miR-494 Sensitizes Gastric Cancer Cells to TRAIL Treatment Through Downregulation of Survivin.

BACKGROUND/AIMS: TNF-related apoptosis-inducing ligand (TRAIL) is a novel and low-toxic anti-tumor drug used for various cancers. However, cancer cells usually develop mechanisms to acquire the resistance against TRAIL. Among these changes, dysregulation of microRNAs (miRNAs) usually occurs in cancer cells and is responsible for induction of drug resistance.

METHODS: Expression of miR-494 in gastric cancer tissues and cell lines was detected by quantitative reverse transcriptase real time PCR (qRT-PCR) analysis. Effect of miR-494 on regulating the TRAIL sensitivity to gastric cancer cell lines was evaluated by MTT assays. Bioinformatics and luciferase reporter assays were used to confirm the regulation of miR-494 on survivin. Mitochondrial apoptosis pathway in gastric cancer cells was tested by western blot and flow cytometry analysis.

RESULTS: Obvious downregulation of miR-494 was observed in gastric cancer cells. Furthermore, we found that expression profile of miR-494 was associated with TRAIL-sensitivity in gastric cancer. Enforced expression of miR-494 was found to sensitize the gastric cancer cells to TRAIL-induced cytotoxicity. Mechanically, Luciferase reporter assays proved that survivin was the target of miR-494 in gastric cancer cells. Enforced expression of miR-494 decreased the expression of survivin, and thus promoted the TRAIL-induced mitochondria collapse and apoptosis pathway.

CONCLUSION: MiR-494/survivin axis represents a potential mechanism which is responsible for TRAIL resistance in gastric cancer cells. Increasing the miR-494 expression may serve as a novel therapeutic strategy to sensitize gastric cancer cells to TRAIL treatment.