Upregulation of bax gene expression promotes paclitaxel-induced apoptosis in esophageal carcinoma cells

An inducible mammalian expression vector of bax gene was constructed and the control ability of metallothionein II promoter in esophageal carcinoma cell line was systematically identified with luciferase report gene. After the transfection of it into human esophageal carcinoma cell line Eca109, Bax protein expression was analyzed by immunolcytochemical method. Paclitaxel-induced apoptosis was determined by TUNEL assay, DNA ladder assay and flow cytometry. Results showed that 140 mu mol/L ZnSO4 for 12 h is optimal for induction of bax gene expression. Under these conditions, a clonal transfectant X1097(#), expressing bax gene effectively, was obtained. It was found that X1097(#) had higher apoptotic rate and was more sensible than Eca109 upon paclitaxel treatment. These results implied that bax protein may play an important role in paclitaxel-induced apoptosis. Therefore, bax protein may be promising as an helping drug to improve therapeutic effects of paclitaxel.