Effects Of Paclitaxel Chemotherapy Combined With Hyperthermia On Paclitaxel-sensitive And Paclitaxel-resistant Gastric Cancer Cell Line

Objective: To observe the effect of paclitaxel (TAX) chemotherapy combined withhyperthermia on TAX-sensitive and TAX-resistant gastric cancer cell lines MKN-45andMKN-45/TAX. To further investigate possible mechanism of its role as reversing the drugresistance of multidrug resistance human gastric adenocarcinoma cell line MKN-45/TAX,and how to improve the reversal effect of the siRNA. It will provide theory evidence inclinic hyperthermia.Methods:1.Establish a TAX-resistant variant of human gastric cancer cells lineMKN-45by cultivating with TAX, named MKN-45/TAX.2. CCK-8test was used to detectthe inhibition rate of both cell lines proliferation under different temperatures and differentdrugs.3. Experimental methods including RT-PCR, Western-blot methods,immuno-cyto-histochemical staining, were employed to detect the effect of differenttemperatures and different drugs on the in vitro drug sensitivity of MKN-45/TAX cell lineand controlled MKN-45cell line, the expression of multidrug resistance related MDR1atthe level of mRNA and protein.4. RT-PCR and Western-blotting methods were used todetect the expression of MDR1mRNA and P-glycoprotein (P-gp) which was transfectedby siRNA.5. Construction of mesoporous silica nanoparticles loaded siRNA targetingMDR1gene. RT-PCR and Western-blotting methods were used to detect the effect ofMDR-siRNA.Results:1. Establishment of MKN-45/TAX cell line was successful.2. Expression ofMDR1was higher in MKN-45/TAX cell line but lower in MKN-45cell line.3. Inhibitionrate of both cell lines proliferation was significantly enhanced with the increase ofconcentration of TAX. Exposing to42℃hyperthermia reduced the inhibition rate of MKN-45/TAX cell line proliferation to TAX chemotherapy drugs, while enhance theinhibition rate of MKN-45cell line proliferation.4. The expression of MDR1mRNA andP-gp were reduced after transfection MDR1-siRNA.5. Mesoporous silica nanoparticlesloaded siRNA targeting MDR1gene was better than siRNA only.Conclusion：1.Hyperthermia itself might kill tumor cells．Hyperthermia combinedwith chemotherapy might enhance its paclitaxel resistance to MKN-45/TAX, but enhanceits sensitivity to MKN-45. The mechanism may be related to the expression of the MDR1.2. The siRNA targeting MDRl cells can be reversed MKN-45/TAX MDRl mediated MDR.3. Mesoporous silica nanoparticles loaded siRNA targeting MDR1gene interference canincrease siRNA transfection efficiency.