Discovery, Optimization, and Anticancer Activity of Lipid-Competitive Pleckstrin Homology Domain-Containing Family A Inhibitors

Phosphoinositide signaling is a major cellular mechanism controlling cancer cell viability, proliferation, and survival. Yet, inhibition of lipid kinases that produce oncogenic phosphoinositides has afforded only a limited number of efficacious drugs attributed in large part to on-target toxicity resulting from the pleiotropic effects of these signaling lipids. Targeting the specific phosphoinositide effector pathways via competitive inhibitors of phosphoinositide-recognizing pleckstrin homology (PH) domains represents a relatively unexplored means to achieve greater specificity. Herein, we present the discovery from in silico screening, structure–activity relationship (SAR) optimization, and cellular characterization of novel phosphoinositide-competitive inhibitors of the pleckstrin homology domain-containing A (PLEKHA) family. These compounds induce cytotoxic effects in BRAF and NRAS mutant melanoma cells, consistent with on-target inhibition, and the most potent compound is activated by endogenous esterase activity, suggesting that prodrug esters represent a viable strategy for targeting the phosphoinositide-binding pockets of the PLEKHA family of PH domains.磷酸肌醇信号通路（Phosphoinositide signaling）是调控癌细胞存活性、增殖能力与生存状态的核心细胞机制。然而，针对生成致癌性磷酸肌醇的脂质激酶开发的抑制剂，仅能产出有限的有效药物，这在很大程度上源于这类信号脂质多效性所引发的靶点毒性。通过靶向识别磷酸肌醇的普列克底物蛋白同源（pleckstrin homology, PH）结构域的竞争性抑制剂，来干预特定的磷酸肌醇效应通路，是一种尚未被充分探索的、可实现更高特异性的治疗策略。本文通过虚拟筛选、构效关系（structure–activity relationship, SAR）优化与细胞水平表征，发现了一类靶向含普列克底物蛋白同源结构域家族A（PLEKHA）的新型磷酸肌醇竞争性抑制剂。这类化合物可在BRAF与NRAS突变型黑色素瘤细胞中诱导细胞毒性效应，该效应与靶点抑制作用一致；其中活性最强的化合物可被内源性酯酶活性激活，这提示前药酯基策略可作为靶向PLEKHA家族PH结构域磷酸肌醇结合口袋的可行方案。