Establishment and characterization of an oxaliplatin-resistant hepatic cancer cell line*

Abstract

Abstract Objective The aim of the current study was to establish an oxaliplatin-resistant hepatoma cell line (HepG2/OXA) and investigate the potential mechanisms of its drug resistance. Methods The hepatoma cell subline, HepG2/OXA, resistant to oxaliplatin (OXA), was established from a parent cell line HepG2, by stepwise exposure to gradually increasing concentrations of OXA over a half-year period. Chemosenstivity of the cytotoxic drugs, OXA, cisplatin (CDDP), adriamycin (ADM), and 5-fuorouracil (5-FU), was determined in HepG2 and HepG2/OXA cells, by the Cell counting kit-8 (CCK8) assay. Cell cycle distribution of HepG2 and HepG2/OXA cells was analyzed by Flow cytometry (FCM). The expression levels of several drug resistance-related proteins, such as P-glycoprotein (P-gp), multidrug resistant protein 1 (MRP1), and excision repair-cross complementing 1 (ERCC1) protein in the two cell lines were tested by the western blot assay. Results The IC50 of OXA in HepG2/OXA and HepG2 were 136.84 µmol/L and 23.86 µmol/L, respectively. The resistance index (RI) was 5.34. HepG2 was also demonstrated to be cross-resistant to other anti-tumor agents, such as 5-FU, ADM, and CDDP. The percentage of HepG2/OXA cells in the S phase was significantly decreased compared to HepG2 cells (25.58% ± 2.36% vs 14.37% ± 2.54%, P < 0.05), while the percentage of cells in the G0/G1 and G2/M phases showed no statistical difference (respectively 55.29% ± 4.98% vs 56.73% ± 4.56%, P > 0.05, and 24.63% ± 4.81% vs 28.26% ± 3.82%, P > 0.05). The ERCC1 was found to be over expressed in HepG2/OXA cells, while there was no difference in the expressions of P-gp and MRP1 between the multiple drug resistance (MDR) phenotype cell line and its parental cell line. Conclusion HepG2/OXA showed an MDR ability; the over expression of ERCC1 might be associated with the platinum resistance of the cells, but P-gp and MRP1 are not.