Mechanism of drug resistance and reversal with ligustra-zine and cyclosporin a in cisplatin-induced human epithelial ovarian cancer resistant cell line 3AO/CDDP

Abstract

Objective: To investigate the mechanism of resistance and reversal effect of ligustrazine and cyclosporin A in cisplatin-induced multidrug resistance ovarian cancer cell line 3Ao/cDDP. Methods: Using the corresponding dose calculated from clinical chemotherapy at 30 mg cisplatin per cycle, we established 3Ao/cDDP with 3Ao exposed at regular intervals and repeatedly to high-level concentration of cisplatin at 10 µg/ml for 24 hours each time. Expressions of LRP, MRP, P-gp, GSTπ and TopoII were quantitatively detected with FCM. For drug resistance reversal, cyclosporin A and ligustrazine were administered singly or in combination at the maximal dose without cytotoxicity. Inhibition rates were determined by MTT assay. Results: 3Ao/cDDP was established after 4.5 months, with resistance factor 1.6 which was similar to clinical resistance degree. Low expression levels of MRP and P-gp were found in both 3Ao and 3Ao/cDDP (P>0.05), and LRP and GSTπ expression levels in 3Ao/cDDP were significantly higher than those in 3Ao (P<0.005 andP<0.05, respectively), and TopoII in 3Ao/cDDP was significantly lower vs 3Ao (P<0.05). The inhibition rate of cDDP was 20.807±0.015%, cDDP plus ligustrazine 27.421±0.07% (P>0.05 vs cDDP), cDDP plus cyclosporin A 49.635±0.021% (P<0.01 vs cDDP), and cDDP plus ligustrazine and cyclosporin A 58.861±0.014% (P<0.01 vs cDDP). Conclusions: 3Ao/cDDP, induced by cisplatin and established by imitating the characteristics of clinical chemotherapy for epithelial ovarian cancer, was an ideal model for investigation of cisplatin resistancein vitro. Cisplatin resistance in 3Ao/cDDP could be accounted for by higher LRP, GSTπ and lower TopoII expression and was not associated with MRP or P-gp. Ligustrazine had no significant reversal effect on cisplatin resistance, but cyclosporin A could reverse the resistance effectively.