Explored Its Mechanism That β-elemene Reversed The Durg Resistance Of Human Lung Adernocancer A549/DDP Cells

Objective:β-elemene (β-ELE) injection is a new anticancer drug extracted from Curcumazedoaria Roscoe that has been widely used to treat malignant tumors.Recent studiesshow that β-ELE reverses the durg resistance of tumor cells.To explore possible itsmechanisms of β-ELE,we investigated its effects on cisplatin-resistant human lungadenocarcinoma A549/DDP cells.Methods:The effects of β-ELE on the growth of A549/DDP cells in vitro were determinedby MTT assay. Apoptosis was assessed by fluorescence microscopy with Hoechst33342staining, flow cytometry with Annexin V-FITC/PI double staining, IntracellularRhodamine-123fluorescence intensity was detected by flow cytometry, and theexpression of P-glycoprotein was detected by Western blotting, Mitochondrialmembrane potential using JC-1fluorescence probe and laser confocal scanningmicroscopy, and intracellular reactive oxygen species levels were measured by2’,7’-dichlorfluorescein-diacetate staining and flow cytometry,and contents ofcytosolic glutathione were determined by the GSH kits. The expression ofCytochrome C, Caspase-3, Pro-caspase-3and the Bcl-2family proteins was measuredby Western blotting.Results:β-ELE inhibited the proliferation of A549/DDP cells in a time-and dose-dependent manner. Furthermore, β-ELE enhanced the sensitivity of A549/DDP cellsto cisplatin and reversed the drug resistance of A549/DDP cells.Consistent with a rolein activating apoptosis, β-ELE decreased mitochondrial membrane potential,increased intracellular reactive oxygen species concentration and intracellularaccumulation of Rhodamine-123, decreased the cytoplasmic glutathione levels and the expression of P-glycoprotein in a time-and dose-dependent manner. Thecombination of β-ELE and cisplatin enhanced the protein expression of CytochromeC, Caspase-3and Bad, and reduced the protein levels of Bcl-2and Pro-caspase-3inthe A549/DDP cancer cells.Conclusions:These results define a pathway of β-ELE function that involves (1) decreased theexpression of P-glycoprotein, inhibitted of P-gp and MRP-dependent drug efflux, andthus increasing the concentration of anticancer drugs in the cell.(2) decreasedmitochondrial membrane potential, increased intracellular reactive oxygen speciesconcentration, decreased the cytoplasmic glutathione levels and activated intracellularredox (3) damaged to the mitochondrial membrane and decreasing the membranepermeability, leading to apoptosis triggered by the release cytochrome C intoCytoplasm, actived Caspase-3, up-regulated pro-apoptotic protein Bad anddown-regulated anti-apoptotic protein Bcl-2, finally caused apoptosis. The reversal ofthe durg resistance of the A549/DDP cell line by β-ELE may be derived from itseffect in inhibitting of P-gp pand MRP-dependent drug efflux, thus increasing thechemosensitivity to anticancer drug and inducing mitochondria dependent apoptoticpathway.