Lama Rati, Fose Joseph M, Martín Diana, Muñoz Inés G, Wang Eunice S, Sung Pamela J, Chemler Sherry R, Wang Xinjiang
Department of Pharmacology and Therapeutics, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA.
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260, USA.
Molecules. 2025 Jan 5;30(1):186. doi: 10.3390/molecules30010186.
MDM2 and MDM4 are major negative regulators of tumor suppressor p53. Beyond regulating p53, MDM2 possesses p53-independent activity in promoting cell cycle progression and tumorigenesis via its RING domain ubiquitin E3 ligase activity. MDM2 and MDM4 form heterodimer polyubiquitin E3 ligases via their RING domain interaction. Inhibitors disrupting p53 interaction with MDM2/MDM4 are in clinical trials in patients bearing wild-type p53 cancers. However, these inhibitors are not designed to work for p53-null/mutant cancer cells. Owing to the importance of the E3 ligase of MDM2 in its p53-independent oncogenic activity, inhibitors targeting the E3 ligase activity of MDM2-MDM4 are desirable for p53-mutant cancer cells. Here, we report the development of such inhibitors with pro-apoptotic activity in p53-null leukemic cells. Among analogues of MDM2-MDM4 E3 ligase inhibitors, we initially identified MMRi36 as a potent pro-apoptotic compound in p53-null leukemic cells with acquired drug resistance. MMRi36 acts as an activator of MDM2-MDM4 E3 ligase by stabilizing MDM2-MDM4 heterodimers and promotes MDM2/MDM4 degradation in cells. Interestingly, replacement of the sulfur in 1,3,4-thiadiazole MMRi36 with a carbon led to identification of pyrazole MMRi36C that dissociates the MDM2-MDM4 RING heterodimers, inhibits the E3 ligase activity of the complex, and induces p53 protein accumulation, but retains the p53-independent pro-apoptotic activity. A brief SAR study identified a fluorine derivative of MMRi36C with improved pro-apoptotic activity. This study discovered a novel class of compound that targets MDM2-MDM4 ubiquitin E3 ligase activity for apoptosis induction in p53-mutant cancer cells.
MDM2和MDM4是肿瘤抑制因子p53的主要负调控因子。除了调控p53外，MDM2通过其RING结构域泛素E3连接酶活性，在促进细胞周期进程和肿瘤发生方面具有不依赖p53的活性。MDM2和MDM4通过其RING结构域相互作用形成异二聚体多聚泛素E3连接酶。破坏p53与MDM2/MDM4相互作用的抑制剂正在携带野生型p53癌症的患者中进行临床试验。然而，这些抑制剂并非设计用于p53缺失/突变的癌细胞。由于MDM2的E3连接酶在其不依赖p53的致癌活性中具有重要作用，因此针对MDM2-MDM4的E3连接酶活性的抑制剂对于p53突变的癌细胞是理想的。在此，我们报告了此类在p53缺失的白血病细胞中具有促凋亡活性的抑制剂的研发情况。在MDM2-MDM4 E3连接酶抑制剂的类似物中，我们最初鉴定出MMRi36是一种在具有获得性耐药性的p53缺失的白血病细胞中具有强效促凋亡作用的化合物。MMRi36通过稳定MDM2-MDM4异二聚体而作为MDM2-MDM4 E3连接酶的激活剂，并促进细胞中MDM2/MDM4的降解。有趣的是，将1,3,4-噻二唑MMRi36中的硫替换为碳，导致鉴定出吡唑MMRi36C，其可使MDM2-MDM4 RING异二聚体解离，抑制该复合物的E3连接酶活性，并诱导p53蛋白积累，但保留不依赖p53的促凋亡活性。一项简短的构效关系研究鉴定出一种具有增强促凋亡活性的MMRi36C氟衍生物。本研究发现了一类新型化合物，其靶向MDM2-MDM4泛素E3连接酶活性以诱导p53突变的癌细胞凋亡。
