Cao Zhonglian, Wright Meredith, Cheng Jiekai, Huang Xiaoxing, Liu Li, Wu Lixing, Yang Ping
School of Pharmacy, Fudan University, Shanghai 201203, P.R. China.
Horizon Biopharm, San Jose, CA 95131, USA.
Oncol Rep. 2014 Sep;32(3):1211-7. doi: 10.3892/or.2014.3326. Epub 2014 Jul 11.
Multidrug resistance (MDR) to chemotherapeutic drugs is the main cause of chemotherapy failure in cancer treatment, and it generally results from expression of ATP-dependent efflux pump P-glycoprotein (P-gp). MDR reversal agents typically act by inhibiting the drug efflux activity of P-gp, thereby increasing intracellular drug levels. PY35 is a novel 5-substituted tetrandrine (Tet) derivative (CN Application No. 201210238709.6). The present study was performed to investigate the ability of PY35 to reverse P-gp-mediated MDR and its mechanism in resistant K562/Adriamycin (ADM), MCF-7/ADM cells and their sensitive cell lines K562 and MCF-7. The ability of PY35 to reverse drug resistance was evaluated by MTT assay. The results showed that PY35 can reverse MDR more effectively than the drug prototype‑Tet. The P-gp function was assessed by the Rhodamine 123 (Rho-123; a P-gp substrate) uptake assay with flow cytometry (FCM) and laser scanning confocal microscopes (LSCM); it showed that the MDR cells pumped Rho-123 out the cells, while their sensitive cells scarcely showed efflux. The presence of PY35 efficiently decreased the efflux of the Rho-123, showing that PY35 can reverse P-gp-mediated MDR by increasing the intracellular concentration of Rho-123. The intracellular accumulation of ADM was analyzed by FCM and showed that the coadministration of PY35 and ADM had clearer accumulation than the treatment of Tet and ADM, and was also more evident than treatment with only ADM. The effect of PY35 on the expression of P-gp was assessed by western blotting. The results indicated that PY35 does not inhibit the expression level of the P-gp. This study indicated that PY35 can effectively reverse P-gp-mediated MDR, not by inhibiting the expression of P-gp, but by the coadministration of PY35 and ADM that could increase the intracellular accumulation of drugs. Thus, PY35 may be a potential inhibitor to overcome drug resistance.
对化疗药物的多药耐药性（MDR）是癌症治疗中化疗失败的主要原因，其通常由ATP依赖性外排泵P-糖蛋白（P-gp）的表达引起。多药耐药逆转剂通常通过抑制P-gp的药物外排活性起作用，从而提高细胞内药物水平。PY35是一种新型的5-取代粉防己碱（Tet）衍生物（中国专利申请号201210238709.6）。本研究旨在探讨PY35逆转P-gp介导的多药耐药性的能力及其在耐药K562/阿霉素（ADM）、MCF-7/ADM细胞及其敏感细胞系K562和MCF-7中的作用机制。通过MTT法评估PY35逆转耐药性的能力。结果表明，PY35比药物原型Tet更有效地逆转多药耐药性。通过流式细胞术（FCM）和激光扫描共聚焦显微镜（LSCM）的罗丹明123（Rho-123；一种P-gp底物）摄取试验评估P-gp功能；结果显示，多药耐药细胞将Rho-123泵出细胞，而其敏感细胞几乎没有外排现象。PY35的存在有效地降低了Rho-123的外排，表明PY35可通过增加细胞内Rho-123浓度来逆转P-gp介导的多药耐药性。通过FCM分析阿霉素的细胞内蓄积情况，结果显示，PY35与阿霉素联合给药比Tet与阿霉素联合给药有更明显的蓄积，且比仅用阿霉素治疗更显著。通过蛋白质印迹法评估PY35对P-gp表达的影响。结果表明，PY35不抑制P-gp的表达水平。本研究表明，PY35可有效逆转P-gp介导的多药耐药性，其机制不是抑制P-gp的表达，而是PY35与阿霉素联合给药可增加细胞内药物蓄积。因此，PY35可能是一种潜在的克服耐药性的抑制剂。
