Wu Chung-Pu, Murakami Megumi, Wu Yu-Shan, Chi Ya-Chen, Hsiao Sung-Han, Huang Yang-Hui, Hung Tai-Ho, Ambudkar Suresh V
Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City, Taiwan.
Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Taoyuan City, Taiwan.
Front Cell Dev Biol. 2021 Jul 19;9:699571. doi: 10.3389/fcell.2021.699571. eCollection 2021.
The overexpression of P-glycoprotein (P-gp/ABCB1), an ATP-binding cassette (ABC) drug transporter, often contributes to the development of multidrug resistance (MDR) in cancer cells. P-gp mediates the ATP hydrolysis-dependent efflux of a wide range of chemotherapeutic agents out of cancer cells, thereby reducing the intracellular drug accumulation and decreasing the chemosensitivity of these multidrug-resistant cancer cells. Studies with tyrosine kinase inhibitors (TKIs) in P-gp-overexpressing cells have shown that certain TKIs could reverse MDR mediated by P-gp, while some TKIs are transported by P-gp. In the present work, we explored the prospect of repositioning branebrutinib (BMS-986195), a highly selective inhibitor of Bruton's tyrosine kinase (BTK), to resensitize P-gp-overexpressing multidrug-resistant cancer cells to chemotherapeutic agents. Our results demonstrated that branebrutinib is capable of reversing P-gp-mediated MDR at sub-toxic concentrations, most likely by directly inhibiting the drug transport function of P-gp. Our findings were supported by the result of branebrutinib stimulating the ATPase activity of P-gp in a concentration-dependent manner and the study of branebrutinib binding to the substrate-binding pocket of P-gp. In addition, we found that branebrutinib is equally cytotoxic to drug-sensitive parental cell lines and the respective P-gp-overexpressing multidrug-resistant variants, suggesting that it is unlikely that the overexpression of P-gp in cancer cells plays a significant role in reduced susceptibility or resistance to branebrutinib. In summary, we discovered an additional pharmacological action of branebrutinib against the activity of P-gp, which should be investigated further in future drug combination studies.
P-糖蛋白（P-gp/ABCB1）是一种ATP结合盒（ABC）药物转运蛋白，其过表达通常会导致癌细胞发生多药耐药（MDR）。P-糖蛋白介导多种化疗药物通过ATP水解依赖性方式从癌细胞中流出，从而减少细胞内药物蓄积，并降低这些多药耐药癌细胞的化疗敏感性。在过表达P-糖蛋白的细胞中使用酪氨酸激酶抑制剂（TKIs）进行的研究表明，某些TKIs可以逆转由P-糖蛋白介导的MDR，而一些TKIs会被P-糖蛋白转运。在本研究中，我们探索了重新定位布鲁顿酪氨酸激酶（BTK）的高度选择性抑制剂布罗替尼（BMS-986195），以使过表达P-糖蛋白的多药耐药癌细胞对化疗药物重新敏感的前景。我们的结果表明，布罗替尼能够在亚毒性浓度下逆转P-糖蛋白介导的MDR，最有可能是通过直接抑制P-糖蛋白的药物转运功能。布罗替尼以浓度依赖性方式刺激P-糖蛋白的ATP酶活性以及布罗替尼与P-糖蛋白底物结合口袋结合的研究结果支持了我们的发现。此外，我们发现布罗替尼对药物敏感的亲本细胞系和各自过表达P-糖蛋白的多药耐药变体具有同等的细胞毒性，这表明癌细胞中P-糖蛋白的过表达不太可能在对布罗替尼的敏感性降低或耐药中起重要作用。总之，我们发现了布罗替尼对P-糖蛋白活性的另一种药理作用，这在未来的药物联合研究中应进一步研究。
