Institute of Cancer Stem Cells and the Second Affiliated Hospital of Dalian Medical University, Dalian Medical University, Dalian, 116044, China.
Department of Pathology, the First Affiliated Hospital of Dalian Medical University, Dalian, 116011, China.
Signal Transduct Target Ther. 2023 Apr 21;8(1):159. doi: 10.1038/s41392-023-01367-x.
Cellular senescence provides a protective barrier against tumorigenesis in precancerous or normal tissues upon distinct stressors. However, the detailed mechanisms by which tumor cells evade premature senescence to malignant progression remain largely elusive. Here we reported that RBM4 adversely impacted cellular senescence to favor glutamine-dependent survival of esophageal squamous cell carcinoma (ESCC) cells by dictating the activity of LKB1, a critical governor of cancer metabolism. The level of RBM4 was specifically elevated in ESCC compared to normal tissues, and RBM4 overexpression promoted the malignant phenotype. RBM4 contributed to overcome H-RAS- or doxorubicin-induced senescence, while its depletion caused P27-dependent senescence and proliferation arrest by activating LKB1-AMPK-mTOR cascade. Mechanistically, RBM4 competitively bound LKB1 to disrupt the LKB1/STRAD/MO25 heterotrimeric complex, subsequently recruiting the E3 ligase TRIM26 to LKB1, promoting LKB1 ubiquitination and degradation in nucleus. Therefore, such molecular process leads to bypassing senescence and sustaining cell proliferation through the activation of glutamine metabolism. Clinically, the ESCC patients with high RBM4 and low LKB1 have significantly worse overall survival than those with low RBM4 and high LKB1. The RBM4 high/LKB1 low expression confers increased sensitivity of ESCC cells to glutaminase inhibitor CB-839, providing a novel insight into mechanisms underlying the glutamine-dependency to improve the efficacy of glutamine inhibitors in ESCC therapeutics.
细胞衰老为癌变前或正常组织中的肿瘤发生提供了一道保护屏障,以应对不同的应激源。然而,肿瘤细胞逃避过早衰老从而恶性进展的详细机制在很大程度上仍难以捉摸。在这里,我们报道 RBM4 通过调节 LKB1(癌症代谢的关键调控因子)的活性,对食管鳞状细胞癌(ESCC)细胞的谷氨酰胺依赖性存活产生不利影响,从而影响细胞衰老。与正常组织相比,RBM4 在 ESCC 中的水平特异性升高,并且 RBM4 的过表达促进了恶性表型。RBM4 有助于克服 H-RAS 或阿霉素诱导的衰老,而其缺失通过激活 LKB1-AMPK-mTOR 级联反应导致 P27 依赖性衰老和增殖停滞。从机制上讲,RBM4 与 LKB1 竞争结合,破坏 LKB1/STRAD/MO25 异三聚体复合物,随后募集 E3 连接酶 TRIM26 到 LKB1 上,促进 LKB1 在核内的泛素化和降解。因此,这种分子过程通过激活谷氨酰胺代谢来绕过衰老并维持细胞增殖。临床上,RBM4 高表达和 LKB1 低表达的 ESCC 患者的总生存期明显比 RBM4 低表达和 LKB1 高表达的患者差。RBM4 高/LKB1 低表达使 ESCC 细胞对谷氨酰胺酶抑制剂 CB-839 的敏感性增加,为了解谷氨酰胺依赖性提供了新的见解,从而提高谷氨酰胺抑制剂在 ESCC 治疗中的疗效。