Research on the regulatory mechanism of Smac peptide on drug resistance in esophageal squamous cell carcino-ma

YANG Yong-wei; AILIJIANG Duolikun; JIN Cheng-yu

doi:10.13820/j.cnki.gdyx.20232210

Abstract：Objective To investigate the effects and the underlying mechanisms of Smac peptide(Smac-N7)on the resistance of esophageal squamous cell carcinoma cell line Eca-109 and paclitaxel(PTX)-resistant strain(Eca-109/PTX).Methods The Eca-109/PTX cell line was established using a low-dose intermittent induction method.The half-maximal inhibitory concentration(IC50)of PTX on Eca-109 and Eca-109/PTX was detected using the CCK-8 assay.Eca-109 and Eca-109/PTX cells were treated with PTX and Smac-N7 alone or in combination and were divided into groups:Eca-109 group,Eca-109+PTX group,Eca-109+Smac-N7 group,and Eca-109+PTX+Smac-N7 group;Eca-109/PTX group,Eca-109/PTX+PTX group,Eca-109/PTX+Smac-N7 group,and Eca-109/PTX+PTX+Smac-N7 group.Flow cytometry,assay kits,and Western blot were used to detect apoptosis rates and the expression levels of caspase-3,Bcl-2,and Bax proteins in Eca-109 and Eca-109/PTX cells.Results The CCK-8 assay results showed that with increasing concentrations,the growth inhibition rates of PTX on Eca-109 and Eca-109/PTX increased significantly(P＜0.05),and the IC50 of PTX on Eca-109[(0.08±0.01)μg/mL]was significantly lower than that on Eca-109/PTX[(2.47±0.11)μg/mL](P＜0.01).Compared with the Eca-109 group or Eca-109/PTX group,the expression levels of Bcl-2 protein in Eca-109+PTX group,Eca-109+PTX+Smac-N7 group,Eca-109/PTX+Smac-N7 group,and Eca-109/PTX+PTX+Smac-N7 group cells decreased sig-nificantly(P＜0.05),while the apoptosis rate,caspase-3 activity,and Bax protein expression levels increased signifi-cantly(P＜0.05).Compared with the Eca-109+PTX group or Eca-109/PTX+PTX group,the expression levels of Bcl-2 protein in Eca-109+PTX+Smac-N7 group and Eca-109/PTX+PTX+Smac-N7 group cells decreased sig-nificantly(P＜0.05),while the apoptosis rate,caspase-3 activity,and Bax protein expression levels increased signifi-cantly(P＜0.05).Conclusion Smac-N7 can improve the sensitivity of Eca-109 cells and its PTX-resistant strain to PTX in vitro by promoting cell apoptosis.