Cooperative inhibitory effect of sinomenine combined with 5-fluorouracil on esophageal carcinoma

AIM: To investigate the inhibitory effects of sinomenine (SIN) combined with 5-fluorouracil (5-FU) on esophageal carcinoma in vitro and in vivo. METHODS: Esophageal carcinoma (Eca-109) cells were cultured in DMEM. The single or combined growth inhibition effects of SIN and 5-FU on the Eca-109 cells were examined by measuring the absorbance of CCK-8 dye in living cells. Hoechst 33258 staining and an Annexin V/PI apoptosis kit were used to detect the percentage of cells undergoing apoptosis. Western blotting was used to investigate the essential mechanism underlying SIN and 5-FU-induced apoptosis. SIN at 25 mg/kg and 5-FU at 12 mg/kg every 3 d, either combined or alone, was injected into nude mice and tumor growth inhibition and side effects of the drug treatment were observed. RESULTS: SIN and 5-FU, both in combination and individually, significantly inhibited the proliferation of Eca-109 cells and induced obvious apoptosis. Furthermore, the combined effects were greater than those of the individual agents (P < 0.05). Annexin V/PI staining and Hoechst 33258 staining both indicated that the percentage of apoptotic cells induced by SIN and 5-FU combined or alone were significantly different from the control (P < 0.05). The up-regulation of Bax and down-regulation of Bcl-2 showed that the essential mechanism of apoptosis induced by SIN and 5-FU occurs via the mitochondrial pathway. SIN and 5-FU alone significantly inhibited the growth of tumor xenografts in vivo, and the combined inhibition rate was even higher (P < 0.05). During the course of chemotherapy, no obvious side effects were observed in the liver or kidneys. CONCLUSION: The combined effects of SIN and 5-FU on esophageal carcinoma were superior to those of the individual compounds, and the drug combination did not increase the side effects of chemotherapy. (C) 2013 Baishideng Publishing Group Co., Limited. All rights reserved.