Antiapoptotic and proapoptotic BCL-2 protein family members regulate mitochondrial apoptotic pathway. Small molecule inhibitors of antiapoptotic BCL-2 proteins including BCL-2-specific inhibitor ABT-199 (Venetoclax) are in clinical development. However, the efficiency of ABT-199 as a single agent in solid tumors is limited. We performed a high-throughput RNAi kinome screen targeting 691 kinases to identify potentially targetable kinases to enhance ABT-199 response in breast cancer cells. Our studies identified Wee1 as the primary target kinase to overcome resistance to ABT-199. Depletion of Wee1 by siRNA-mediated knockdown or inhibition of Wee1 by the small molecule Wee1 inhibitor AZD1775 sensitized SKBR3, MDA-MB-468, T47D and CAMA-1 breast cancer cells to ABT-199 along with decreased MCL1. BH3-only proteins PUMA and BIM functionally contribute to apoptosis signaling following co-targeting BCL-2 and Wee1. Suppression of Wee1 function increased mitochondrial cell death priming. Furthermore, we found that Wee1 inhibition altered MCL1 phosphorylation and protein stability, which led to HUWE1-mediated MCL1 degradation. Our findings suggest that Wee1 inhibition can overcome resistance to ABT-199 and provide a rationale for further translational investigation of BCL-2 inhibitor/Wee1 inhibitor combination in breast cancer.

抗凋亡和促凋亡 BCL-2 蛋白家族成员调节线粒体凋亡途径。包括 BCL-2 特异性抑制剂 ABT-199 (Venetoclax) 在内的抗凋亡 BCL-2 蛋白的小分子抑制剂正在临床开发中。然而，ABT-199 作为单一药物在实体瘤中的效率是有限的。我们进行了针对 691 种激酶的高通量 RNAi 激酶组筛选，以确定潜在的可靶向激酶，以增强乳腺癌细胞中的 ABT-199 反应。我们的研究确定 Wee1 是克服 ABT-199 抗性的主要靶激酶。通过 siRNA 介导的敲低或小分子 Wee1 抑制剂 AZD1775 抑制 Wee1 消耗 Wee1，使 SKBR3、MDA-MB-468、T47D 和 CAMA-1 乳腺癌细胞对 ABT-199 敏感，同时降低 MCL1。BH3-only 蛋白 PUMA 和 BIM 在共靶向 BCL-2 和 Wee1 后在功能上有助于细胞凋亡信号传导。Wee1 功能的抑制增加了线粒体细胞死亡启动。此外，我们发现 Wee1 抑制改变了 MCL1 磷酸化和蛋白质稳定性，从而导致 HUWE1 介导的 MCL1 降解。我们的研究结果表明，Wee1 抑制可以克服对 ABT-199 的抗性，并为 BCL-2 抑制剂/Wee1 抑制剂组合在乳腺癌中的进一步转化研究提供理论依据。