Ovarian cancer is usually treated with transurethral resection or systemic chemotherapy in clinic. However, the development of drug resistance in ovarian cancer is frequently observed in ovarian cancer patients, leading to failure of tumor inhibition and recurrence. In this study, we aimed to efficiently reverse the drug resistance and enhance the anticancer effects by co-delivery of chemotherapeutic agents and multi-drugs resistant proteins inhibitor in ovarian cancer treatment.

The cell viability was measured by using MTT or flow cytometry (Annexin V/PI staining) under different culture conditions. Western blot was used to detect the expression of P-gp. We employed confocol to visualize the drug distribution under different culture systems. Using flow cytometry, we examined the drug absorption. MPEG-PLA was used to load chemotherapeutic drugs. We also applied mice model to evaluate the killing ability and side effects of free or methoxy poly (ethylene glycol)-poly (l-lactic acid) (MPEG-PLA) loaded drugs.

We found that pre-treatment of verapamil, a multi-drugs resistant proteins inhibitor, could efficiently reverse the drug resistant in ovarian cancer. To further improve the pharmacokinetics profiles and avoid the systemic toxicity caused by agents, we encapsulated verapamil and doxorubicin (DOX) by polymeric nanoparticles MPEG-PLA. Co-delivery of verapamil and DOX by nano-carrier revealed reduced drug resistance and enhanced anticancer effects compared with the free drug delivery. More importantly, accumulated drugs, prolonged drug circulation and reduced systemic were observed in nanoparticles encapsulation group.

Co-delivery of verapamil and chemotherapeutic drugs by MPEG-PLA efficiently reversed the drug resistance, resulting in enhanced anticancer effects along with reduced systemic toxicity, which provides potential clinical applications for drug resistant ovarian cancer treatment.