背景:除了在细胞周期中充当精确的监测机制外,据报道,后期促进复合物/环小体(APC/C)通过促进关键酶的泛素介导的降解而参与调节多种代谢过程.脂肪酸氧化是肿瘤细胞利用的代谢途径,对恶性进展至关重要;然而,其与APC/C的关联仍有待探索。
方法:细胞周期同步,免疫印迹,并进行碘化丙啶染色以研究肉碱棕榈酰转移酶1C(CPT1C)的表达方式。进行邻近连接测定和免疫共沉淀以检测CPT1C和APC/C之间的相互作用。流式细胞术,3-(4,5-二甲基噻唑-2-基)-5-(3-羧基甲氧基苯基)-2-(4-磺基苯基)-2H-四唑,内盐(MTS)测定,细胞划痕试验,进行了transwell测定和异种移植测定,以研究CPT1C在体外和体内肿瘤进展中的作用。在肿瘤组织芯片上进行免疫组织化学检查,以评估CPT1C的表达水平并探讨其潜在的临床价值。
结果:我们确定CPT1C为新型APC/C底物。CPT1C蛋白水平表现出细胞周期依赖性波动,在G1/S边界处达到峰值。CPT1C升高加速了G1/S过渡,促进肿瘤细胞的体外和体内增殖。此外,CPT1C提高脂肪酸利用率,上调ATP水平,降低了活性氧的水平,从而有利于细胞在恶劣的代谢环境中存活。临床上,CPT1C高表达与食管鳞状细胞癌患者生存率低相关.
结论:总体而言,我们的结果揭示了肿瘤细胞中脂肪酸利用和细胞周期机制之间的新的相互作用。此外,CPT1C通过增加细胞ATP水平和保持氧化还原稳态促进肿瘤细胞增殖和存活,特别是在代谢压力下。因此,CPT1C可作为食管鳞癌的独立预后指标。
BACKGROUND: In addition to functioning as a precise monitoring mechanism in cell cycle, the anaphase-promoting complex/cyclosome (APC/C) is reported to be involved in regulating multiple metabolic processes by facilitating the ubiquitin-mediated degradation of key enzymes. Fatty acid oxidation is a metabolic pathway utilized by tumor cells that is crucial for malignant progression; however, its association with APC/C remains to be explored.
METHODS: Cell cycle synchronization, immunoblotting, and propidium iodide staining were performed to investigate the carnitine palmitoyltransferase 1 C (CPT1C) expression manner. Proximity ligation assay and co-immunoprecipitation were performed to detect interactions between CPT1C and APC/C. Flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium, inner salt (MTS) assays, cell-scratch assays, and transwell assays and xenograft transplantation assays were performed to investigate the role of CPT1C in tumor progression in vitro and in vivo. Immunohistochemistry was performed on tumor tissue microarray to evaluate the expression levels of CPT1C and explore its potential clinical value.
RESULTS: We identified CPT1C as a novel APC/C substrate. CPT1C protein levels exhibited cell cycle-dependent fluctuations, peaking at the G1/S boundary. Elevated CPT1C accelerated the G1/S transition, facilitating tumor cell proliferation in vitro and in vivo. Furthermore, CPT1C enhanced fatty acid utilization, upregulated ATP levels, and decreased reactive oxygen species levels, thereby favoring cell survival in a harsh metabolic environment. Clinically, high CPT1C expression correlated with poor survival in patients with esophageal squamous cell carcinoma.
CONCLUSIONS: Overall, our results revealed a novel interplay between fatty acid utilization and cell cycle machinery in tumor cells. Additionally, CPT1C promoted tumor cell proliferation and survival by augmenting cellular ATP levels and preserving redox homeostasis, particularly under metabolic stress. Therefore, CPT1C could be an independent prognostic indicator in esophageal squamous cell carcinoma.