Human Drug Efflux Transporter ABCC5 Confers Acquired Resistance to Pemetrexed in Breast Cancer

Abstract

AimPemetrexed, a new generation antifolate drug, is approved for the treatment for locally advanced or metastatic breast cancer, but factors affecting the efficacy and resistance of it have yet to be fully explicit. ATP-binding cassette (ABC) transporters have been reported as prognostic and adverse effects predictors of many xenobiotics. This study was designed to explore whether ABC transporters affect pemetrexed resistance and may contribute to treatment regimen optimization for breast cancer.MethodsFirstly, the expression of ABC transporters family members was measured in cell lines, thereafter examined the potential role of ABC transporter in conferring resistance to pemetrexed in primary cancer cell lines isolated from 34 breast cancer patients, and then the role of ABCC5 in mediating transport of pemetrexed and apoptosis pathway in MCF-7 cell line was assessed. Finally, the functions of ABCC5 on therapeutic effect of pemetrexed was evaluated in breast cancer bearing mice.ResultsThe expressions of ABCC2, ABCC4, ABCC5 and ABCG2 were significantly increased in pan-resistance cell line, and the ABCC5, the most obvious one, was 5.21 times higher than that of the control group. The expression of ABCC5 was inversely correlated with sensitivity (IC50) of pemetrexed (r = 0.741; p<0.001) in breast cancer cells from 34 patients. Furthermore, we found that the expression of ABCC5 influenced the efflux and cytotoxicity of pemetrexed in MCF-7 cell line, and the IC50 were 0.06 μg/ml and 0.20 μg/ml in ABCC5 knock-down and over-expression cells, respectively. In in vivo study, we found ABCC5 affected the sensitivity of pemetrexed in breast cancer bearing mice, and the tumor volume was much larger in ABCC5 over-expression group than that in control group (2.7 folds vs 1.3 folds).ConclusionsOur results indicated ABCC5 expression was associated with pemetrexed resistance in vitro and in vivo, and may be a biomarker for regimen optimization of pemetrexed in breast cancer treatment.

Identification of Prognostic Biomarkers for Breast Cancer Metastasis Using Penalized Additive Hazards Regression Model

“…On the other hand, ABCC5 has a role in chemoresistance of several cancers, such as hepatocellular carcinoma, breast cancer, and colorectal cancer. 29-31 CD44 as a transmembrane glycoprotein has a role in cellular communication considered as a cancer stem cell marker. Cancer stemness was associated with metastasis, epithelial to mesenchymal transition, and therapeutic resistance of different cancers, such as breast cancer.…”