Overexpression of the ATP-binding cassette (ABC) transport proteins, like ABCB1, commonly referred to as P-glycoprotein (P-gp), initiates active efflux of a broad spectrum of unrelated chemotherapeutic drugs in structure and function, leading to chemotherapy failure. A series of 2-((pyridin-4-ylmethyl)amino)nicotinamide derivatives as potent reversal agents against P-glycoprotein-mediated multidrug resistance (MDR) were designed and synthesized. The majority of target compounds displayed great reversal potency, especially 9n. In-depth studies demonstrated 9n has high potency (EC₅₀ = 119.6 ± 6.9 nM), low cytotoxicity, and long duration (>24 h) in reversing adriamycin (ADM) resistance in K562/A02 cells. 9n also improved the effects of other cytotoxic agents related to MDR, increased accumulation of ADM, interrupted P-gp-mediated Rh123 efflux function, and suppressed P-gp ATPase activity in K562/A02 MDR cells. The Western blot analysis indicated that the MDR reversal by 9n was not due to a decrease in protein expression. Besides, the effect of CYP3A4 was not influenced by 9n, avoiding the toxicity caused by drug interactions. The study yielded 9n with superior properties compared to the classical inhibitor verapamil (VRP) and leading compound apatinib.

中文翻译：

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2-（（吡啶-4-基甲基）氨基）烟酰胺衍生物作为对抗P-糖蛋白介导的多药耐药性的有效逆转剂的探索

ATP结合盒（ABC）转运蛋白的过表达，如ABCB1，通常称为P-糖蛋白（P-gp），在结构和功能上引发了广泛的无关化疗药物的主动流出，从而导致化疗失败。设计并合成了一系列2-（（吡啶-4-基甲基）氨基）烟酰胺衍生物，作为对抗P-糖蛋白介导的多药耐药性（MDR）的有效逆转剂。大多数目标化合物显示出很大的逆转能力，尤其是9n。深入研究表明，9n在逆转K562 / A02细胞中对阿霉素（ADM）的耐药性方面具有很高的效力（EC ₅₀ = 119.6±6.9 nM），低细胞毒性和较长的持续时间（> 24小时）。9n还改善了与MDR相关的其他细胞毒性剂的作用，增加了ADM的积累，中断了P-gp介导的Rh123外排功能，并抑制了K562 / A02 MDR细胞中的P-gp ATPase活性。Western印迹分析表明MDR逆转9n不是由于蛋白质表达的降低。此外，CYP3A4的作用不受9n的影响，避免了药物相互作用引起的毒性。与经典抑制剂维拉帕米（VRP）和领先化合物阿帕替尼相比，该研究产生的9n具有优越的性能。