Effects Of Tetrandrine In Combination With Paclitaxel On The Proliferation And Apoptosis Of Human Gastric Cancer Cell Lines And The Probable Mechanism

Objective To investigate the effects of tetrandrine (TET) in combination with paclitaxel (PTX) on the proliferation and apoptosis in human gastric cancer cell line MKN-45and the probable mechanism.Methods MKN-45cells were routinely cultured in RPMI-1640medium supplemented with10%heat-inactivated fetal calf serum. Subconfluent cell cultures were treated with either TET or PTX, or TET in combination with PTX for24h,36h or48h. Cell growth and proliferation of MKN-45were analyzed with MTT assay. DAPI staining and flow cytometric analysis were used to detect the apoptosis of MKN-45. Label intracellular ROS with Fluorescence probe2’,7’-Dichloroflourescin diacetate(DCFH-DA). The intensive of fluorescence was determined by a fluorescence spectrophotometer under an emission wavelength at535nm, while an excitation wavelength at485nm.Results Both TET and PTX alone or the combined treatment inhibited MKN-45cell proliferation in a time and dose-dependent manner. The50%inhibitory concentration (IC50) for TET and PTX were significantly decreased when MKN-45cells were treated simultaneously with TET plus PTX compared with the two drugs applied alone (P<0.05). DAPI staining and flow cytometric analysis showed that the apoptosis rates in the cells treated with TET and PTX were much greater than TET or PTX applied singly (P<0.05). ROS in the cells that treated with TET combined with PTX was increased remarkably (P<0.05). ROS scavengers NAC can remarkably decreased the production of intercellular ROS and blocked the effects of TET and (or) PTX-induced apoptosis.Conclution This study demonstrates that TET and PTX exerted a synergistic effect on the inhibition of proliferation and the induction of apoptosis in gastric cancer cells. The synergistic induction of intracellular ROS is one of the possible mechanism of synergy.