Pokrzywinski Kaytee L, Biel Thomas G, Kryndushkin Dmitry, Rao V Ashutosh
Laboratory of Applied Biochemistry, Division of Biotechnology Research and Review III, Office of Biotechnology Products, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, United States of America.
PLoS One. 2016 Dec 28;11(12):e0168283. doi: 10.1371/journal.pone.0168283. eCollection 2016.
Mitochondrial dysregulation is closely associated with excessive reactive oxygen species (ROS) production. Altered redox homeostasis has been implicated in the onset of several diseases including cancer. Mitochondrial DNA (mtDNA) and proteins are particularly sensitive to ROS as they are in close proximity to the respiratory chain (RC). Mitoquinone (MitoQ), a mitochondria-targeted redox agent, selectively damages breast cancer cells possibly through damage induced via enhanced ROS production. However, the effects of MitoQ and other triphenylphosphonium (TPP+) conjugated agents on cancer mitochondrial homeostasis remain unknown. The primary objective of this study was to determine the impact of mitochondria-targeted agent [(MTAs) conjugated to TPP+: mitoTEMPOL, mitoquinone and mitochromanol-acetate] on mitochondrial physiology and mtDNA integrity in breast (MDA-MB-231) and lung (H23) cancer cells. The integrity of the mtDNA was assessed by quantifying the degree of mtDNA fragmentation and copy number, as well as by measuring mitochondrial proteins essential to mtDNA stability and maintenance (TFAM, SSBP1, TWINKLE, POLG and POLRMT). Mitochondrial status was evaluated by measuring superoxide production, mitochondrial membrane depolarization, oxygen consumption, extracellular acidification and mRNA or protein levels of the RC complexes along with TCA cycle activity. In this study, we demonstrated that all investigated MTAs impair mitochondrial health and decrease mtDNA integrity in MDA-MB-231 and H23 cells. However, differences in the degree of mitochondrial damage and mtDNA degradation suggest unique properties among each MTA that may be cell line, dose and time dependent. Collectively, our study indicates the potential for TPP+ conjugated molecules to impair breast and lung cancer cells by targeting mitochondrial homeostasis.
线粒体功能失调与活性氧（ROS）的过量产生密切相关。氧化还原稳态的改变与包括癌症在内的多种疾病的发生有关。线粒体DNA（mtDNA）和蛋白质对ROS特别敏感，因为它们与呼吸链（RC）距离很近。线粒体靶向氧化还原剂米托醌（MitoQ）可能通过增强ROS产生所诱导的损伤来选择性地损伤乳腺癌细胞。然而，MitoQ和其他三苯基鏻（TPP+）共轭剂对癌症线粒体稳态的影响仍然未知。本研究的主要目的是确定线粒体靶向剂[与TPP+共轭的（MTAs）：线粒体Tempol、米托醌和米托色醇-乙酸酯]对乳腺癌（MDA-MB-231）和肺癌（H23）细胞线粒体生理学和mtDNA完整性的影响。通过量化mtDNA片段化程度和拷贝数，以及测量对mtDNA稳定性和维持至关重要的线粒体蛋白质（TFAM、SSBP1、TWINKLE、POLG和POLRMT）来评估mtDNA的完整性。通过测量超氧化物产生、线粒体膜去极化、氧消耗、细胞外酸化以及RC复合物的mRNA或蛋白质水平以及三羧酸循环活性来评估线粒体状态。在本研究中，我们证明所有研究的MTAs都会损害MDA-MB-231和H23细胞的线粒体健康并降低mtDNA完整性。然而，线粒体损伤程度和mtDNA降解的差异表明每种MTA具有独特的特性，这可能取决于细胞系、剂量和时间。总体而言，我们的研究表明TPP+共轭分子有可能通过靶向线粒体稳态来损害乳腺癌和肺癌细胞。
