Anti-cancer activity of Tonglian decoction against esophageal cancer cell proliferation through regulation of the cell cycle and PI3K/Akt signaling pathway

Objective: The purpose of this study was to observe the anti-cancer activity of Tonglian decoction (TD) on esophageal cancer (EC) cells in vitro, and to elucidate the related molecular mechanisms in the cell cycle and PI3K/Akt signaling pathway. Methods: EC9706 cells were cultured in RPMI 1640 medium supplemented with 10% calf serum at 37°C in a 5% CO2 incubator. The cells were treated with rat serum containing TD or the serum of rats administered Xiaoaiping as a positive control drug. Cell proliferation was assessed by methylthiazolyldiphenyl-tetrazolium bromide assays. Cell morphology was observed under a microscope. The cell cycle was examined by flow cytometry. Protein expression in the PI3K/Akt signaling pathway was measured by western blotting. Results: TD mainly inhibited cell proliferation. Concentrations of 50% cell inhibition by rat serum containing TD or Xiaoaiping were 73.6 and 153.8 μL/mL, respectively. TD also influenced cell morphology characterized by small shrunken cells. Cell colonies became small and the cell proliferation rate was slower. In cell cycle analysis, the percentage of cells in S phase was decreased significantly by TD and Xiaoaiping compared with the blank control group (P < .05). Western blotting showed that serum containing TD strongly down-regulated EGFR, PI3K, Akt, p-Akt, and mTOR expression compared with the blank control group (P < .05). Conclusion: TD could inhibit EC9706 carcinoma cell proliferation by blocking the cell cycle progression in S phase. The possible mechanism was inhibition of multiple targets in the PI3K/Akt signaling pathway by TD