Influence of Tanshinone IIA on apoptosis of human esophageal carcinoma Eca‐109 cells and its molecular mechanism

BACKGROUND Previous studies have shown that Tanshinone (Tan) IIA exerts obvious antitumor efficacy; however, its molecular mechanism remains unclear. This study was conducted to identify the influence of Tan IIA on Eca-109 cell apoptosis, explore its molecular mechanism, and provide a theoretical basis for clinical application. METHODS Eca-109 cells were cultured in vitro and treated with different concentrations of Tan IIA. Morphologic changes were viewed under inverted fluorescence microscope with dual acridine orange/ethidium bromide staining assay. Methyl-thiazolyl-tetrazolium and Annexin V propidium iodide assays were respectively used to measure cell viability and apoptosis rate. The protein and messenger (m)RNA expression of binding immunoglobulin protein (BIP), mitochondrial cytochrome c (CytC), and caspase-9 were detected by Western blot and quantitative real-time PCR, respectively. RESULTS Cell viability decreased and the apoptosis rate significantly increased with increasing concentrations of Tan IIA (0, 20, 40, 60 μg/mL), which indicated that Tan IIA inhibited the proliferation and induced the apoptosis of Eca-109 cells in a dose-dependent manner. Eca-109 cells treated with 60 μg/mLTan IIA showed typical morphological changes of apoptosis under the inverted microscope. Moreover, compared with the negative control group, protein and mRNA expression of BIP decreased significantly (P < 0.05), whereas protein and mRNA expression of CytC and caspase-9 increased significantly (P < 0.05). CONCLUSION Tan IIA can induce apoptosis in human esophageal carcinoma Eca-109 cells by regulating BIP, CytC, and caspase-9 expression. Endoplasmic reticulum stress and mitochondrial-dependent may be involved in Tan IIA-induced Eca-109 cell apoptosis.