Effects Of Dihydroartemisinin On Mmalignant Behaviors Of Cisplatin-Resistant Gastric Cancer Cells

Objective:To investigate the influence of dihydroartemisinin（DHA）on the malignant behaviors of human cisplatin（DDP）-resistant gastric cancer cell strain SGC7901/DDP and the possible molecular mechanism.Methods:SGC7901/DDP cells were cultured in vitro.The IC50 of DHA against SGC7901/DDP cells at 48 h was determined by cell counting（CCK-8）.DHA concentrations of 0μmol/L,0.5-fold IC₅₀,1-fold IC₅₀,or 2-fold IC₅₀ were then used as experimental treatments on SGC7901/DDP,and the proliferative activity of SGC7901/DDP from days 1 to 5 was detected by CCK-8.At 48 h after DHA treatment,we observed apoptosis,invasion,and migration.We evaluated autophagy with mRFP-GFP-LC3 adenovirus transfection and transmission electron microscopy,and detected the expression levels of proteins related to the regulation of autophagy,apoptosis,angiogenesis,and lymphangiogenesis via western blot.The influence of DHA on cisplatin resistance of SGC7901/DDP was detected through a sensitization test and the evaluation of p-gp expression levels.Results:The IC₅₀ concentration of DHA against SGC7901/DDP cells at 48 h was 70μmol/L.DHA significantly inhibited the proliferation of SGC7901/DDP,which was time-and concentration-dependent（all P<0.05）.After having been treated for 48 h by increasing concentrations of DHA（0,35,70,and 140μmol/L）,the apoptosis rates increased,and the penetrating cell numbers and scratch healing rates significantly decreased（all P<0.05）.The expression levels of Beclin1 and LC3-II/LC3-I,which were corrected with autophagy,and the formation of autophagosomes and autophagous vacuoles increased in a concentration-dependent manner（all P<0.05）.The total PI3-K,Akt,and mTOR expression levels did not significantly change,but their phosphorylated products（PI3P,p-Akt（Ser473）,and p-mTOR（Ser2448））showed concentration-dependent decreases（all P<0.05）.The protein expressions of caspases-8/9/3 significantly increased while the expressions of VEGF-A and VEGF-C protein decreased（all P<0.05）.DHA reversed the resistance of SGC7901/DDP cells to cisplatin after DHA treatment at a non-toxic dose（15.23μg/mL）with a reversal rate of2.95.After DHA treatment at different concentrations for 48 h,the expression of p-gp was significantly reduced in a concentration-dependent manner（P<0.05）.Conclusion:DHA significantly inhibited proliferation,promoted programmed death,and had anti-invasion and anti-metastatic effects on SGC7901/DDP cells.The likely mechanism was by upregulating autophagy-related Beclin1 and LC3-II expression and by inhibiting the anti-autophagy signaling pathway PI3-K/AKT/mTOR,thus promoting autophagic death.In addition,DHA induced caspase-dependent and mitochondrial pathway apoptosis in SGC7901/DDP cells,and reduced VEGF-A and VEGF-C activities to promote anti-angiogenesis and anti-lymphangiogenesis.Furthermore,DHA reversed the cisplatin resistance of gastric cancer cells effectively by inhibiting P-gp expression.