Development of liposomal pemetrexed for enhanced therapy against multidrug resistance mediated by ABCC5 in breast cancer

Abstract

Purpose

Breast cancer is the most common cancer among women. Pemetrexed, a new generation antifolate drug, is one of the primary treatments for breast cancer. However, multidrug resistance (MDR) in breast cancer greatly hampers the therapeutic efficacy of chemotherapies such as pemetrexed. Nanomedicine is emerging as a promising alternative technique to overcome cancer MDR. Thus, pemetrexed-loaded d-alpha tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) liposomes (liposomal pemetrexed) were developed as a strategy to overcome MDR to pemetrexed in breast cancer.

Materials and methods

Liposomal pemetrexed was developed using the calcium acetate gradient method. The cytotoxic effects, apoptosis-inducing activity, in vivo distribution, and antitumor activity of liposomal pemetrexed were investigated.

Results

Liposomal pemetrexed was small in size (160.77 nm), with a small polydispersity of <0.1. The encapsulation efficacy of liposomal pemetrexed was 63.5%, which is rather high for water-soluble drugs in liposomes. The IC₅₀ of liposomal pemetrexed following treatment with MDR breast cancer cells (MCF-7 cells overexpressing ABCC5) was 2.6-fold more effective than pemetrexed. The in vivo biodistribution study showed that the liposomes significantly accumulated in tumors 24 h after injection. The antitumor assay in mice bearing MDR breast cancer xenograft tumors confirmed the superior antitumor activity of liposomal pemetrexed over pemetrexed. It was also found that the improved therapeutic effect of liposomal pemetrexed may be attributed to apoptosis through both extrinsic and intrinsic pathways.

Conclusion

Liposomal pemetrexed represents a potential therapeutic approach for overcoming breast cancer MDR.

Keywords:

• cancer nanotechnology
• breast cancer
• multidrug resistance
• pemetrexed
• liposomes

Supplementary materials

Figure S1 Viruses transfection into the tumors of nude mice (×200). Thirty days after injection when the tumor growth was over 100 mm³, adenovirus contained ABCC5 was injected into the tumors of the mice (twice for each tumor, each time with 5×10^⁹ PFU). The frozen sections of the tumors demonstrated the overexpression of ABCC5 in the tumors by the diffused green GFP fluorescence.

Abbreviations: DAPI, 4′,6-diamidino-2-phenylindole dihydrochloride; PFU, plaque formation unit; GFP, green fluorescent protein; Blank, no drugs.

Figure S2 Expression of ABCC5 protein of MCF-7 cells transfected with adenoviruses containing ABCC5 and the MCF-7 cells without transfection. GAPDH is used an internal control. The expression of ABCC5 was measured by Western blot. The bands were visualized with the Image Studio system (LI-COR Biosciences; Lincoln, NE, USA).

Abbreviation: GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

Acknowledgments

The authors thank Dr Jie Gao and Dr Chuan Yin for editing the entire manuscript. This work was financially supported by the Shanghai Municipal Commission of Health and Family Planning Foundation (No 20154Y0077), the Science and Technology Commission of Shanghai Municipality (No 12JC1406800, No 14411950206 and No 17411950104), the Shanghai Key Specialty Project of Clinical Pharmacy (No 2016-40044-002), the National Natural Science Foundation of China (No 81771964) and the Chinese Naval Medical University military medical innovation (No 2017JS07).

Disclosure

The authors report no conflicts of interest in this work.