Synergistic antitumour effects of triptolide plus gemcitabine in bladder cancer

Abstract

Background and objective: Gemcitabine (GEM) effectively inhibits bladder cancer progression in the clinic, but novel combination treatments using multiple drugs are needed.

Materials and methods: The bladder cancer cell lines EJ and UMUC3 were treated with triptolide (TPL) and/or GEM. Tumour cell viability and proliferation were measured using MTT and clonogenic assays, respectively. Flow cytometry and western blotting were used to detect the cell cycle phase, apoptosis, reactive oxygen species (ROS) and the levels of specific relevant proteins. The AKT/GSK3β signalling pathway proteins were also measured by immunofluorescence and western blotting.

Results: The cytotoxicity of the GEM plus TPL combination treatment was stronger than that of GEM or TPL alone. In bladder cancer cell lines, GEM plus TPL induced cell cycle arrest at the G1 phase via suppression of CDK4, CDK6 and cyclins A1 and A2. Significantly increased apoptosis and increases in apoptosis-related proteins (caspase 8 and Bcl-xL) were observed in cells treated with GEM plus TPL. While ROS increased, certain ROS-related proteins (catalase and SOD2) clearly decreased in cells treated with a combination of GEM plus TPL. The AKT/GSK3β signalling pathway was also inhibited more significantly in cells treated with the GEM plus TPL combination than in cells treated with either agent alone.

Conclusion: The combination of GEM plus TPL showed significantly enhanced anticancer effects compared to those of GEM or TPL alone.

Keywords: Bladder cancer; Combination; Drug therapy; Gemcitabine; Triptolide.