Abstract
Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy that is often resistant to therapy. Nowadays, chemotherapy is still one of the main methods for the treatment of ESCC. However, the multidrug resistance (MDR)-mediated chemotherapy resistance is one of the leading causes of death. Exploring agents able to reverse MDR, which thereby increase the sensitivity with clinical first-line chemotherapy drugs, could significantly improve cancer treatment. Cepharanthine hydrochloride (CEH) has the ability to reverse the MDR in ESCC and the mechanism involved have not been reported. The aim of the study was to investigate the potential of CEH to sensitize chemotherapeutic drugs in ESCC and explore the underlying mechanisms by in vitro and in vivo studies. Our data demonstrated that CEH significantly inhibited ESCC cell proliferation in a dose-dependent manner, induced G2/M phase cell cycle arrest and apoptosis, and increased the sensitivity of cell lines resistant to cisplatin (cDDP). Mechanistically, CEH inhibited ESCC cell growth and induced apoptosis through activation of c-Jun, thereby inhibiting the expression of P-gp, and enhancing p21 expression via activation of the p53 signaling pathway. In this study, we observed that growth of xenograft tumors derived from ESCC cell lines in nude mice was also significantly inhibited by combination therapy. To our knowledge, we demonstrate for the first time that CEH is a potentially effective MDR reversal agent for ESCC, based on downregulation of the mRNA expression of MDR1 and P-gp. Together, these results reveal emphasize CEH putative role as a resistance reversal agent for ESCC.