Clinical and Molecular Pharmacology Program, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Santiago 8380453, Chile.
Institute of Biotechnology, Czech Academy of Sciences, 25250 Prague, Czech Republic.
Cells. 2020 Feb 11;9(2):407. doi: 10.3390/cells9020407.
The mitochondrion has emerged as a promising therapeutic target for novel cancer treatments because of its essential role in tumorigenesis and resistance to chemotherapy. Previously, we described a natural compound, 10-((2,5-dihydroxybenzoyl)oxy)decyl) triphenylphosphonium bromide (GA-TPPC), with a hydroquinone scaffold that selectively targets the mitochondria of breast cancer (BC) cells by binding to the triphenylphosphonium group as a chemical chaperone; however, the mechanism of action remains unclear. In this work, we showed that GA-TPPC causes time-dependent complex inhibition of the mitochondrial bioenergetics of BC cells, characterized by (1) an initial phase of mitochondrial uptake with an uncoupling effect of oxidative phosphorylation, as previously reported, (2) inhibition of Complex I-dependent respiration, and (3) a late phase of mitochondrial accumulation with inhibition of α-ketoglutarate dehydrogenase complex (αKGDHC) activity. These events led to cell cycle arrest in the G1 phase and cell death at 24 and 48 h of exposure, and the cells were rescued by the addition of the cell-penetrating metabolic intermediates l-aspartic acid β-methyl ester (mAsp) and dimethyl α-ketoglutarate (dm-KG). In addition, this unexpected blocking of mitochondrial function triggered metabolic remodeling toward glycolysis, AMPK activation, increased expression of proliferator-activated receptor gamma coactivator 1-alpha () and electron transport chain (ETC) component-related genes encoded by mitochondrial DNA and downregulation of the uncoupling proteins and , suggesting an AMPK-dependent prosurvival adaptive response in cancer cells. Consistent with this finding, we showed that inhibition of mitochondrial translation with doxycycline, a broad-spectrum antibiotic that inhibits the 28 S subunit of the mitochondrial ribosome, in the presence of GA-TPPC significantly reduces the mt-CO1 and VDAC protein levels and the FCCP-stimulated maximal electron flux and promotes selective and synergistic cytotoxic effects on BC cells at 24 h of treatment. Based on our results, we propose that this combined strategy based on blockage of the adaptive response induced by mitochondrial bioenergetic inhibition may have therapeutic relevance in BC.
线粒体已成为新型癌症治疗方法的有前途的治疗靶标，因为它在肿瘤发生和对化疗的抵抗力中起着至关重要的作用。以前，我们描述了一种天然化合物 10-((2,5-二羟基苯甲酰)氧基)癸基)三苯基膦溴化物（GA-TPPC），其具有对苯二酚支架，通过与三苯基膦基团结合作为化学伴侣，选择性地靶向乳腺癌（BC）细胞的线粒体;然而，作用机制尚不清楚。在这项工作中，我们表明 GA-TPPC 导致 BC 细胞线粒体生物能量的时间依赖性复合物抑制，其特征在于（1）先前报道的线粒体摄取的初始阶段，具有氧化磷酸化的解偶联作用，（2）抑制复合物 I 依赖性呼吸，以及（3）线粒体积累的后期阶段，抑制α-酮戊二酸脱氢酶复合物（αKGDHC）活性。这些事件导致细胞在暴露 24 和 48 小时时在 G1 期停滞并死亡，并且通过添加穿透细胞的代谢中间物 l-天冬氨酸β-甲酯（mAsp）和二甲基α-酮戊二酸（dm-KG）来挽救细胞。此外，这种对线粒体功能的意外阻断触发了向糖酵解的代谢重塑，AMPK 激活，增殖激活受体γ共激活因子 1-α（PGC-1α）和电子传递链（ETC）组件相关基因的表达增加，由线粒体 DNA 编码和解偶联蛋白的下调和，提示癌细胞中 AMPK 依赖性的存活适应性反应。与这一发现一致，我们表明，在用 GA-TPPC 存在的情况下，用广谱抗生素多西环素抑制线粒体核糖体 28S 亚基抑制线粒体翻译，可显著降低 mt-CO1 和 VDAC 蛋白水平以及 FCCP 刺激的最大电子通量，并促进 BC 细胞在治疗 24 小时时的选择性和协同细胞毒性作用。基于我们的结果，我们提出，这种基于抑制线粒体生物能量抑制诱导的适应性反应的联合策略可能在 BC 中具有治疗相关性。
