The β-catenin/B-cell lymphoma 9 (BCL9) protein-protein interaction (PPI) is a potential target for the suppression of hyperactive Wnt/β-catenin signaling that is vigorously involved in cancer initiation and development. Herein, we first described quercetin and its derivatives had potential inhibitory effects on β-catenin/BCL9 PPI. The most potent compound, quercetin-3′-O-(4-methylpiperazine-1-yl) propyl (C1), directly binded with β-catenin and disrupted the β-catenin/BCL9 interaction in both the protein level and the cellular context. C1 also effectively inhibited colorectal cancer in vitro and showed better selectivity in inhibiting hyperactive Wnt/β-catenin signaling cells like CT26 and HCT116. And we further confirmed that C1 could inhibit CT26 tumor growth in vivo and regulate the tumor immune microenvironment. This study provides a good chemical probe to explore β-catenin-related biology and a drug-like quercetin derivative as novel β-catenin/BCL9 PPI inhibitors for further drug development.

β-连环蛋白/B 细胞淋巴瘤 9 (BCL9) 蛋白-蛋白相互作用 (PPI) 是抑制过度活跃的 Wnt/ β-连环蛋白信号传导的潜在靶点，该信号通路积极参与癌症的发生和发展。在此，我们首先描述了槲皮素及其衍生物对β -catenin/BCL9 PPI 具有潜在的抑制作用。最有效的化合物槲皮素-3'- O- (4-甲基哌嗪-1-基)丙基 ( C1 )，直接与β-连环蛋白结合并在蛋白质水平和细胞环境中破坏β-连环蛋白/BCL9 相互作用. C1在体外也有效抑制结直肠癌并在抑制过度活跃的 Wnt/ β -catenin 信号细胞如 CT26 和 HCT116方面表现出更好的选择性。并进一步证实C1在体内可抑制CT26肿瘤生长，调节肿瘤免疫微环境。该研究为探索β-连环蛋白相关生物学和药物样槲皮素衍生物作为新型β-连环蛋白/BCL9 PPI抑制剂的进一步药物开发提供了良好的化学探针。