Structure-Based Discovery of MDM2/4 Dual Inhibitors that Exert Antitumor Activities against MDM4-Overexpressing Cancer Cells

Despite recent clinical progress in peptide-based dual inhibitors of MDM2/4, small-molecule ones with robust antitumor activities remain challenging. To tackle this issue, 31 (YL93) was structure-based designed and synthesized, which had MDM2/4 binding Ki values of 1.1 and 642 nM, respectively. In three MDM4-overexpressing cancer cell lines harboring wild-type p53, 31 shows improved cell growth inhibition activities compared to RG7388, an MDM2-selective inhibitor in late-stage clinical trials. Mechanistic studies show that 31 increased cellular protein levels of p53 and p21 and upregulated the expression of p53-targeted genes in RKO cells with MDM4 amplification. In addition, 31 induced cell-cycle arrest and apoptosis in western blot and flow cytometry assays. Taken together, dual inhibition of MDM2/4 by 31 elicited stronger antitumor activities in vitro compared to selective MDM2 inhibitors in wild-type p53 and MDM4-overexpressing cancer cells.

尽管基于肽的鼠双微体蛋白2/4（MDM2/4）双重抑制剂领域近期已取得临床进展，但开发具备强效抗肿瘤活性的此类小分子抑制剂仍极具挑战。为解决这一难题，研究人员通过基于结构的设计策略合成了化合物31（YL93），其对MDM2和MDM4的结合抑制常数（Ki）分别为1.1 nM和642 nM。在三株携带野生型p53（wild-type p53）的MDM4过表达癌细胞系中，化合物31的细胞生长抑制活性优于RG7388——后者是一款处于晚期临床试验阶段的MDM2选择性抑制剂。机制研究显示，在MDM4扩增的RKO细胞中，化合物31可提升细胞内p53与p21的蛋白水平，并上调p53靶基因的表达。此外，通过蛋白质免疫印迹（Western Blot）与流式细胞术（flow cytometry）检测，证实化合物31可诱导细胞周期阻滞与细胞凋亡。综上，相较于选择性MDM2抑制剂，化合物31通过双重抑制MDM2/4，在野生型p53且MDM4过表达的癌细胞中展现出更强的体外抗肿瘤活性。