유방암내성단백질(BCRP)를 과발현하는 항암제내성암세포의 선별 및 프라 보노이드 BCRP억제제의 탐색

Abstract

Background and Objective: The overexpression of breast cancer resistant protein (BCRP) confers multidrug resistance (MDR) on cancer cells. MDR cells could be sensitized to anticancer drugs when treated concomitantly with a chemosensitizer. In this study, flavonoids have been screened for the development of chemosensitizers reversing BCRP-mediated MDR using a BCRP-overexpressing cancer cell line. Materials and methods: The mitoxantrone-resistant breast cancer cell subline was selected from the parental MCF-7cells by treating mitoxantrone chronically. Expression of BCRP were determined using Western blot and RT-PCR analyses. Chemosensitizing effects of flavonoids were determined by the MTT assay. Results: The human breast cancer cell subline MCF-7/MX5 cells selected in the presence of 5 μg/ml mitoxantrone (MX) were more resistant to MX (15.7 (5.1 times) and 5-fluorouracil (4.4 times) than were the MCF-7cells. Western blot and RT-PCR analyses revealed that the MCF-7/MX5 cells overexpressed BCRP mRNA and protein, whose activity was inhibited by nicardipine, a known BCRP inhibitor. Of eleven flavonoids tested 5,7,4′-trimethoxyflavone, 5,6,7,3′,4′,5′-hexamethoxyflavone and 5,6,7,3′,4′-pentamethoxyflavone showed higher chemosensitizing effects than nicardipine. Conclusion: The mitoxantrone-resistant brest cancer cell subline MCF-7/MX5 could provide a useful model for the screening of chemosensitizers of BCRP-mediated MDR. It is anticipated 5,7,4′-trimethoxyflavone, 5,6,7,3′,4′,5′-hexamethoxyflavone and 5,6,7,3′,4′-pentamethoxyflavone could be candidates for BCRP inhibitors.