Anticancer Drug Resistance of HeLa Cells Transfected With Rat Glutathione S-transferase pi Gene

Key words: 
• Glutathione S-transferase P1 /
• Enhancer element /
• Trans-acting factor /
• Gene transfection /
• Drug resistance /
• Tumor cell /
• In situ hybridization

Abstract: Objective To establish a cytologic expressing system of rat glutathione S-transferase pi(GST-pi) cDNA for detecting the resistance of HeLa cells to anticancer drugs. Methods Theassessment was made with various anticancer drugs (adriamycin, mitomycin, cisplatinum andvincristine) that showed different cytotoxicities in transfectant HeLa cells with pSV-GT containing ratGST-pi cDNA (HeLa/pSV-GT) or control pSV-neo (HeLa/pSV-neo). Expression levels of GST-pimRNA in HeLa/pSV-GT and HeLa/pSV-neo were measured by in situ hybridization usingDigoxin-labelled cDNA probe. Results HeLa/pSV-GT expressed significantly high degree ofGST-pi mRNA, whereas both HeLa/pSV-neo and HeLa cells had very low expression. Cytotoxicitiesof HeLa/pSV-GT and HeLa/pSV-neo with 4 anticancer drugs were measured by MTT assay. Drugconcentrations for yielding 50% inhibition (IC50) in HeLa/pSV-GT by adriamycin, mitomycin andcisplatinum were 70.13 μg/mL, 10.95 μg/mL and 16.52 μg/mL, respectively. In contrast, IC50 inHeLa/pSV-neo was 10.34 μg/mL, 7.48 μg/mL and 13.70 μg/mL, respectively. The cytotoxicities ofvincristine on both HeLa/pSV-GT and HeLa/pSV-neo were not significantly different. ConclusionsOur findings suggest that HeLa/pSV-GT containing rat GST-pi cDNA is resistant to some anticancerdrugs due to overexpression of GST-pi. Also, HeLa/pSV-GT cell line could serve as a usefulcytogenetic model for further research.