Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
Department of Breast Surgery, Shanghai Medical College, Fudan University, Shanghai, China.
Clin Transl Med. 2023 Mar;13(3):e1210. doi: 10.1002/ctm2.1210.
Microtubule-targeing agents (MTAs), such as paclitaxel (PTX) and vincristine (VCR), kill cancer cells through activtion of the spindle assembly checkpoint (SAC) and induction of mitotic arrest, but the development of resistance poses significant clinical challenges.
Immunoblotting and RT-qPCR were used to investigate potential function and related mechanism of MORC2. Flow cytometry analyses were carried out to determine cell cycle distribution and apoptosis. The effect of MORC2 on cellular sensitivity to PTX and VCR was determined by immunoblotting, flow cytometry, and colony formation assays. Immunoprecipitation assays and immunofluorescent staining were utilized to investigate protein-protein interaction and protein co-localization.
Here, we identified microrchidia family CW-type zinc finger 2 (MORC2), a poorly characterized oncoprotein, as a novel regulator of SAC activation, mitotic progression, and resistance of cancer cells to PTX and VCR. Mechanically, PTX and VCR activate cyclin-dependent kinase 1, which in turn induces MORC2 phosphorylation at threonine 717 (T717) and T733. Phosphorylated MORC2 enhances its interation with HSPA8 and LAMP2A, two essential components of the chaperone-mediated autophagy (CMA) mechinery, resulting in its autophagic degradation. Degradation of MORC2 during mitosis leads to SAC activation through stabilizing anaphase promoting complex/cyclosome activator protein Cdc20 and facilitating mitotic checkpoint complex assembly, thus contributing to mitotic arrest induced by PTX and VCR. Notably, knockdown of MORC2 promotes mitotic arrest induced by PTX and VCR and enhances the sensitivity of cancer cells to PTX and VCR.
Collectively, these findings unveil a previously unrecognized function and regulatory mechanism of MORC2 in mitotic progression and resistance of cancer cells to MTAs. These results also provide a new clue for developing combined treatmentstrategy by targeting MORC2 in combination with MTAs against human cancer.
微管靶向药物（MTAs），如紫杉醇（PTX）和长春新碱（VCR），通过激活纺锤体组装检查点（SAC）和诱导有丝分裂停滞来杀死癌细胞，但耐药性的发展带来了重大的临床挑战。
使用免疫印迹和 RT-qPCR 来研究 MORC2 的潜在功能和相关机制。通过流式细胞术分析来确定细胞周期分布和细胞凋亡。通过免疫印迹、流式细胞术和集落形成实验来确定 MORC2 对细胞对 PTX 和 VCR 的敏感性的影响。免疫沉淀实验和免疫荧光染色用于研究蛋白质-蛋白质相互作用和蛋白质共定位。
在这里，我们确定了微线体家族 CW 型锌指 2（MORC2），一种未被充分研究的癌蛋白，作为 SAC 激活、有丝分裂进展和癌细胞对 PTX 和 VCR 耐药性的新型调节因子。从机制上讲，PTX 和 VCR 激活周期蛋白依赖性激酶 1，后者反过来诱导 MORC2 在苏氨酸 717（T717）和 T733 处磷酸化。磷酸化的 MORC2 增强其与热休克蛋白家族 A 成员 8（HSPA8）和溶酶体相关膜蛋白 2A（LAMP2A）的相互作用，这两种蛋白是伴侣介导的自噬（CMA）机制的两个重要组成部分，导致其自噬降解。有丝分裂期间 MORC2 的降解通过稳定后期促进复合物/环体激活蛋白 Cdc20 并促进有丝分裂检查点复合物的组装来激活 SAC，从而有助于 PTX 和 VCR 诱导的有丝分裂停滞。值得注意的是，MORC2 的敲低促进了 PTX 和 VCR 诱导的有丝分裂停滞，并增强了癌细胞对 PTX 和 VCR 的敏感性。
总之，这些发现揭示了 MORC2 在有丝分裂进展和癌细胞对 MTAs 耐药性中的以前未被认识到的功能和调节机制。这些结果还为通过靶向 MORC2 与 MTAs 联合治疗人类癌症提供了新的线索。
