Induction of apoptosis by arsenic trioxide and hydroxycamptothecin in gastric cancer cells in vitro

AIM To study the effects of arsenic trioxide andHCPT on different degrees of differentiated gastriccancer cells（SGC-7901,MKN-45,MKN-28）withrespect to both cytotoxicity and induction ofapoptosis in vitro.METHODS The cytotoxicity of As2O3 and HCPTon gastric cancer cells was determined by MTTassay.Morphologic changes of apoptosis ofgastric cancer cells were observed by lightmicroscopy and transmission electron microscopy.Apoptosis and cell cycle changes of gastric cancercells induced by HCPT and As2O3 were investigatedby TUNEL method and flow cytometry.RESULTS As2O3 and HCPT had remarkablecytotoxic effects on different degrees ofdifferentiated gastric cancer cells.The IC50ofAs2O3 on well differentiated gastric cancer cellMKN-28,moderately differentiated gastric cancercell SGC-7901,and poorly differentiated gastriccancer cell MKN-28 were 8.91 μmol/L,10.57μmol/L,and 11.65 μmol/L,respectively.The IC50of HCPT on MKN-28,SGC-7901,and MKN-45 were9.35 mg/L,10.21 mg/L,and 12.63 mg/Lrespectively after 48 h treatment.After 12 h ofexposure to both drugs,gastric cancer cellsexhibited morphologic features of apoptosis,including cell shrinkage,nuclear condensation, and formation of apoptotic bodies.A typicalsubdiploid peak before G0/G1 phase was observedby flow cytometry.The apoptotic rates of SGC-7901,MKN-45,and MKN-28 were 13.84%,22.52%,and 9.68%,respectively after 48 hexposure to 10 μmol/L As2O3.The apoptotic ratesof SGC-7901,MKN-45,and MKN-28 were 21.88%,12.35%,and 30.26%,respectively after 48 hexposure to 10 mg/L HCPT.The apoptotic indicewere 7%-15% as assessed by TUNEL method.The effect of As2O3 on SGC-7901 showedremarkable cell cycle specificity,which inducedcell death in G1 phase,and blocked G2/M phase.HCPT also showed a remarkable cell cyclespecificity,by inducing cell death and apoptosis inG1 phase and arrest of proliferation at S phase.CONCLUSION As2O3 and HCPT exhibitsignificant cytotoxicity on gastric cancer cells byinduction of apoptosis.As2O3 and HCPT mighthave a promising prospect in the treatment ofgastric cancer,which needs to be further studied.

AIM:To study the effects of arsenic trioxide and HCPT on dif ferent degrees of differentiated gastric cancer cells (SGC-7901, MKN-45, MKN-28) with respect to both cytotoxicity and induction of apoptosis in vitro.METHODS:The cytotoxicity of As(2)O(3) and HCPT on gastric cancer cells was det ermined by MTT assay.Morphologic changes of apoptosis of gastric cancer cells were observed by light microscopy and transmission electron microscopy.Apoptosis and cell cycle changes of gastric cancer cells induced by HCPT and As(2)O(3) we re investigated by TUNEL method and flow cytometry.RESULTS:As(2)O(3) and HCPT had remarkable cytotoxic effects on different degrees of differentiated gastric cancer cells. The IC(50) of As(2)O(3) on well differentiated gastric cancer cell MKN-28, moderately differentiated gastric cancer cell SGC-7901, and poorly differentiated gastric cancer cell MKN-28 were 8.91 &mgr;mol/L, 10.57 &mgr;mol/L, and 11.65&mgr;mol/L, respectively. The IC(50) of HCP T on MKN-28, SGC-7901, and MKN-45 were 9.35 mg/L, 10.21 mg/L,and 12.63 mg/L respectively after 48 h treatment. After 12 h of exposure to both drugs, gastric cancer cells exhibited morphologic features of apoptosis, includ ing cell shrinkage,nuclear condensation, and formation of apoptotic bodies. A ty pical subdiploid peak before G(0)/G(1) phase was observed by flow cytometry. The apoptotic rates of SGC-7901, MKN-45, and MKN-28 were 13.84%, 22.52%, and 9.68%, respectively after48 h exposure to 10&mgr;mol/L As(2)O(3). The apoptotic ra tes of SGC-7901, MKN-45, and MKN-28 were 21.88%, 12.35%, and 30.26%, resp ectively after 48 h exposure to 10 mg/L HCPT. The apoptotic indice were 7%-15% a s assessed by TUNEL method. The effect of As(2)O(3) on SGC-7901 showed remarkab le cell cycle specificity, which induced cell death in G(1) phase, and blocked G(2)/M phase.HCPT also showed a remarkable cell cycle specificity, by inducing cell death and apoptosis in G(1) phase and arrest of proliferation at Sphase.CONCLUSION:As(2)O(3) and HCPT exhibit significant cytotoxicity on gastric canc er cells by induction of apoptosis. As(2)O(3) and HCPT might have a promising pr ospect in the treatment of gastric cancer, which needs to be further studied.