Astragaloside IV Induced MIR-134 Expression Reduces EMT and Increases Chemotherapeutic Sensitivity by Suppressing CREB1 Signaling in Colorectal Cancer Cell Line SW-480

Abstract

Background: Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Although chemotherapy is the primary means in colorectal cancer treatment, it is burdenerd by adverse drug effects. Drug-resistance is one of the most important challenges for chemotherapy and epithelial-mesenchymal transition (EMT) plays critical role in the development of drug resistance. Aims: The aim of this study was to investigate the mechanisms underlying the effect of astragaloside IV (AS-IV) on MIR-134 expression, EMT and chemotherapeutic sensitivity in CRC. Methods: Cell proliferation, transfection assay, western blot, real-time PCR, cell migration and invasion assay and luciferase reporter assay were used to detect the effects of AS-IV on CRC. Results: AS-IV significantly inhibited CRC cell migration and invasion by inducing MIR-134 expression. Moreover, AS-IV and MIR-134 increased the sensitivity of CRC tumors to oxaliplatin (OXA) chemotherapy. cAMP responsive element-binding protein 1 (CREB1), which was required for CRC cells migration, invasion and drug sensitivity, was significantly down-regulated by AS-IV. Conclusions: Our results indicated that AS-IV inhibited CRC EMT by inducing MIR-134 expression which significantly down-regulated the CREB1 signaling pathway, and therefore increased the sensitivity to chemotherapy. Our findings provided new insight into the mechanisms of chemotherapy-resistant CRC, and may open new therapeutic options in the treatment of this devastating disease.