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

Abstract

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.

Keywords: 5-Fluorouracil; Chemotherapy; Esophageal carcinoma; Sinomenine.