PO.MCB09.01 · 分子与细胞生物学
MEX3A 维持线粒体完整性和代谢韧性以驱动卵巢透明细胞癌进展和肝脏定植
MEX3A sustains mitochondrial integrity and metabolic resilience to drive ovarian clear cell carcinoma progression and liver colonization
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摘要 Abstract
中文摘要
背景与目的：卵巢透明细胞癌 OCCC 是一种代谢上独特且化疗耐药的卵巢癌亚型，其特征为预后差和复发率高。OCCC 表现出独特的代谢适应，使其能够在营养剥夺和氧化应激下存活。线粒体完整性是这种适应能力的核心，然而在 OCCC 中维持线粒体稳态的分子机制仍未被充分定义。近期证据已确定 RNA 结合蛋白 MEX3A 在包括 OCCC 在内的多种癌症中作为致癌调控因子，在 OCCC 中它促进肿瘤进展。然而，其在调控线粒体代谢和应激适应中的作用在很大程度上仍未被探索。本研究旨在阐明 MEX3A 是否以及如何维持线粒体稳态以驱动 OCCC 进展，重点关注其对肿瘤生长、线粒体结构以及对代谢和线粒体应激的转录应答的影响。
方法：通过蛋白质印迹在 OCCC 细胞组中评估内源性 MEX3A 蛋白水平。使用慢病毒 shRNA 系统生成稳定的 MEX3A 敲低和对照细胞。使用 OCCC 细胞系 TOV21G、JHOC5 以及体内原位囊内和脾内异种移植模型进行功能研究，以评估肿瘤生长和肝脏定植。通过 Seahorse 代谢通量检测、ATP 定量和 NAD+/NADH 测量分析线粒体功能。通过共聚焦和透射电子显微镜检查形态学和超微结构改变。通过 qPCR 和免疫印迹评估线粒体生物合成基因和线粒体自噬标志物。
结果：MEX3A 表达在 OCCC 组织中显著升高，并与较差的总生存期相关。在 OCCC 细胞中敲低 MEX3A 显著减少原发肿瘤生长，并在小鼠模型中显著减少肝转移结节数量，证明了其对转移性定植的功能重要性。在细胞水平，MEX3A 耗竭导致线粒体嵴完整性丧失、形态碎片化、耗氧量降低和 ATP 生成减少，表明氧化磷酸化功能障碍。在 FCCP 或肝提取物诱导的线粒体应激下，对照细胞激活线粒体生物合成的转录程序，上调 PGC1A、NRF2 和 TFAM。相反，MEX3A 缺陷细胞未能诱导这种适应性应答，导致 TOM20 降解和线粒体恢复缺陷。
结论：我们的研究揭示 MEX3A 是一种关键的 RNA 结合蛋白，可保持线粒体完整性并使 OCCC 实现代谢适应。通过维持应激后的线粒体生物合成和恢复，MEX3A 增强了 OCCC 的适应性、肿瘤生长和肝脏定植。
查看英文原文 English abstract
Background and Aim: Ovarian clear cell carcinomaOCCC is a metabolically distinct and chemo-resistant subtype of ovarian cancer characterized by poor prognosis and high recurrence rates. OCCC exhibits unique metabolic adaptations that enables survival under nutrient deprivation and oxidative stresses. Mitochondrial integrity is central to this adaptive capacity, yet the molecular mechanisms that preserve mitochondrial homeostasis in OCCC remain poorly defined. Recent evidence has identified the RNA-binding protein MEX3A as an oncogenic regulator in several cancers, including OCCC, where it promotes tumor progression. However, its role in regulating mitochondrial metabolism and stress adaptation is largely unexplored. This study aims to elucidate whether and how MEX3A sustains mitochondrial homeostasis to drive OCCC progression, focusing on its impact on tumor growth, mitochondrial structure and transcriptional responses to metabolic and mitochondrial stress.
Methods: Endogenous MEX3A protein levels were evaluated across an OCCC cell panel by western blotting. Stable MEX3A knockdown and control cells were generated using a lentivirus shRNA system. Functional studies were performed using OCCC cell lines TOV21G,JHOC5 and in vivo orthotopic intrabursa and intrasplenic xenograft models to assess tumor growth and liver colonization. Mitochondrial function was analyzed by Seahorse metabolic flux assays, ATP quantification and NAD + /NADH measurements. Morphological and ultrastructural alterations were examined by confocal and transmission electron microscopy. Mitochondrial biogenesis genes and mitophagy markers were assessed by qPCR and immunoblotting.
Results: MEX3A expression was significantly elevated in OCCC tissues and correlated with poor overall survival. Knockdown of MEX3A in OCCC cells markedly reduced primary tumor growth and significantly reduced the number of liver metastatic nodules in mouse models, demonstrating its functional importance for metastatic colonization. At the cellular level, MEX3A depletion led to loss of mitochondrial cristae integrity, fragmented morphology, reduced oxygen consumption and decreased ATP generation, indicating a dysfunctional in oxidative phosphorylation. Under mitochondrial stress induced by FCCP or liver-extract, control cells activated transcriptional programs for mitochondrial biogenesis, upregulating PGC1A, NRF2 and TFAM. In contrast, MEX3A-deficient cells failed to induce this adaptive response, leading to TOM20 degradation and defective mitochondrial recovery.
Conclusion: Our study reveals MEX3A as a crucial RNA-binding protein that preserves mitochondrial integrity and enables metabolic adaptation in OCCC. By sustaining mitochondrial biogenesis and recovery following stress, MEX3A enhances OCCC fitness, tumor growth and liver colorization
利益披露 Disclosure
P. Vinothkumar, None..
P. Lin, None..
L. Cheng, None..
C. Albert Yu, None..
P. Hsu, None..
Y. Chou, None..
W. W. Hwang-Verslues, None.