RESUMO
BACKGROUND: Previous studies on the efficacy of platinum-based drugs and selective inhibitors of proteasome have revealed promising outcomes. This study is aimed to evaluate the effects of the combination of cisplatin and carfilzomib on the cell death induction and drug efflux transporters expression in cisplatin-sensitive (A2780s) and cisplatin-resistant (A2780cp) ovarian cancer cells lines. METHODS: MTT cytotoxic assay was conducted to determine the cytotoxicity. Drug interactions were analyzed based on Chou-Talalay's principles and real-time PCR analysis was performed to determine possible alterations in mRNA levels of MRP1 and BCRP. RESULTS: A2780s cells were more susceptible to both cisplatin and carfilzomib while analyses of drug interactions between the two agents showed synergistic effects in all affected fractions of drug-treated A2780s and A2780cp cells (CI<0.9) with the combination indices being significantly lower in A2780cp cells (p < 0.01). We also found that although mRNA levels of BCRP and MRP1 were significantly altered in both cells exposed to each drug alone, only the combination regimen was able to significantly reduce the mRNA levels of these genes in A2780cp cells (p<0.001). CONCLUSION: This combination might be a potential strategy for suppressing cell growth via downregulating the drug efflux transporters expression, especially in cisplatin-resistant ovarian cancer cells (Fig. 3, Ref. 45).