Background/Objectives: Mitochondrial oxidative phosphorylation (OXPHOS) has been exploited as a therapeutic target in cancer treatments because of its crucial role in tumorigenesis. CR6-interacting factor 1 (CRIF1), a mitochondrial ribosomal subunit protein, is essential for the regulation of mitochondrial OXPHOS capacity. However, the mechanism of CRIF1 in triple-negative breast cancer (TNBC) cells remains unclear. Methods/Results: We showed that the downregulation of CRIF1 reduced cell proliferation in the TNBC cell lines MDA-MB-468, MDA-MB-231, and, especially, BT549. In addition, wound scratch and Transwell assays showed that CRIF1 deficiency inhibited the migration and invasion of BT549 cells. CRIF1 downregulation resulted in the suppression of mitochondrial bioenergetics in BT549 cells, specifically affecting the inhibition of OXPHOS complexes I and II. This was evidenced by a decrease in the mitochondrial oxygen consumption rate and the depolarization of the mitochondrial membrane potential. Damage to mitochondria resulted in a lower adenosine triphosphate level and an elevated production of mitochondrial reactive oxygen species. In addition, CRIF1 deficiency decreased hypoxia-inducible factor 1α accumulation, NADPH synthesis, and TP53-induced glycolysis and apoptosis regulator (TIGAR) expression in BT549 cells. These events contributed to G0/G1-phase cell cycle inhibition and the upregulation of the cell cycle protein markers p53, p21, and p16. Transfection with a TIGAR overexpression plasmid reversed these effects and prevented CRIF1 downregulation-induced proliferation and migration reduction. Conclusions: These results indicate that blocking mitochondrial OXPHOS synthesis via CRIF1 may have a therapeutic antitumor effect in BT549 TNBC cells.
背景/目的：线粒体氧化磷酸化（OXPHOS）在肿瘤发生中起关键作用，因此已成为癌症治疗的重要靶点。CR6相互作用因子1（CRIF1）作为线粒体核糖体亚基蛋白，对调节线粒体OXPHOS功能至关重要。然而，CRIF1在三阴性乳腺癌（TNBC）细胞中的作用机制尚不明确。方法/结果：研究发现，下调CRIF1可抑制TNBC细胞系MDA-MB-468、MDA-MB-231（特别是BT549）的细胞增殖。划痕实验和Transwell实验表明，CRIF1缺失能抑制BT549细胞的迁移和侵袭能力。CRIF1下调导致BT549细胞线粒体生物能量学功能受损，特异性抑制OXPHOS复合物I和II的活性，具体表现为线粒体耗氧率降低和线粒体膜电位去极化。线粒体功能损伤导致三磷酸腺苷水平下降，线粒体活性氧生成增加。此外，CRIF1缺失降低了BT549细胞中缺氧诱导因子1α的积累、NADPH合成以及TP53诱导的糖酵解和凋亡调节因子（TIGAR）的表达。这些变化共同导致细胞周期G0/G1期阻滞，并上调细胞周期蛋白标志物p53、p21和p16。通过转染TIGAR过表达质粒可逆转上述效应，并阻止CRIF1下调引起的增殖和迁移抑制。结论：本研究结果表明，通过CRIF1阻断线粒体OXPHOS合成可能对BT549三阴性乳腺癌细胞产生抗肿瘤治疗作用。
肿瘤(癌症)患者之家