Expression Of C-Myc And ABCG2 In Artesunate Treated Cisplatin-resistant Tumor Cells Nude Mice Parotid Gland Xenografts

Objective:To establish a study model of nude mice xenograft with cisplatin-resistant cancer cells and investigate the inhibitory ability of artesunate(ART)on cancer cell proliferation and chemoresistance,by quantifying c-Myc and ABCG2 expressions in ART and/or DDP treated nude mice xenografts.Methods:A subculture of cisplatin induced chemo-resistant tumor cells,HELA-DDP,which derived from parental HELA cells,was adapted to build a tumor xenograft study model by inoculating such chemo-resistant tumor cells into one side of the parotid glands of BALB/C-nu nude mice.Randomized grouping was conducted in 7 days after the inoculation,marked by different accounts of drug and dosage,including normal saline,DDP 1.0 mg/kg,DDP 2.0 mg/kg,ART 50.0mg/kg,ART 100.0 mg/kg,ART 200.0 mg/kg and a combination of ART 100mg/kg+DDP 1.0 mg/kg.Intraperitoneal injection was applied accordingly to body weight of mice every other day.Animials were executed in 30 days after the first drug injection and the xenografted tumor tissues were harvested.Immunohistochemistry was performed to detect the expressions of c-Myc and ABCG2 protein in xenograft tissues from each group.Western blot and real-timefluorescence quantification PCR was applied to verify the gene and protein expressions of c-Myc and ABCG2.Results:1.The result of Real-time PCR showed that the gene expression of c-Myc and ABCG2 in chemo-resistant tumor cell xenografts could be effectively inhibited by ART in dosages of 50~200 mg/kg,compared to natural saline group(P<0.01)and DDP groups(P<0.05).2.The results of immunohistochemistry showed that the average optical density of c-Myc and ABCG2 in chemo-resistant tumor cell xenografts were decreased by ART in dosages of 50~200 mg/kg.compared to natural saline group(P<0.05)and DDP groups(P<0.05).3.The result of Western Blot showed that the expression of c-Myc and ABCG2 protein in chemo-resistant tumor cell xenografts could be effectively inhibited by ART in dosages of 50~200 mg/kg,compared to natural saline group(P<0.05)and DDP groups(P<0.05).Conclusion:1.The ability for ART to inhibit the proliferation of xenografted chemo-resistant tumor cells and to reverse tumor chemoresistance may due to its down-regulation of the m RNA and protein expression of c-Myc and ABCG2.2.During the combined treatment of ART and DDP,ART not only exerts an inhibitory effect towards tumor cell proliferation,but also the reversal ability towards chemoresistance.