Direct impact of cisplatin on mitochondria induces ROS production that dictates cell fate of ovarian cancer cells

Markus Kleih,Frank Essmann,Monilola A Olayioye,Simon Heine,Meng Dong,Kathrin Böpple,Walter E Aulitzky,Andrea Gaißler

doi:10.1038/s41419-019-2081-4

Abstract

Patients with high-grade serous ovarian cancer (HGSC) frequently receive platinum-based chemotherapeutics, such as cisplatin. Cisplatin binds to DNA and induces DNA-damage culminating in mitochondria-mediated apoptosis. Interestingly, mitochondrial DNA is critically affected by cisplatin but its relevance in cell death induction is scarcely investigated. We find that cisplatin sensitive HGSC cell lines contain higher mitochondrial content and higher levels of mitochondrial ROS (mtROS) than cells resistant to cisplatin induced cell death. In clonal sub-lines from OVCAR-3 mitochondrial content and basal oxygen consumption rate correlate with sensitivity to cisplatin induced apoptosis. Mitochondria are in two ways pivotal for cisplatin sensitivity because not only knock-down of BAX and BAK but also the ROS scavenger glutathione diminish cisplatin induced apoptosis. Mitochondrial ROS correlates with mitochondrial content and reduction of mitochondrial biogenesis by knock-down of transcription factors PGC1α or TFAM attenuates both mtROS induction and cisplatin induced apoptosis. Increasing mitochondrial ROS by inhibition or knock-down of the ROS-protective uncoupling protein UCP2 enhances cisplatin induced apoptosis. Similarly, enhancing ROS by high-dose ascorbic acid or H2O2 augments cisplatin induced apoptosis. In summary, mitochondrial content and the resulting mitochondrial capacity to produce ROS critically determine HGSC cell sensitivity to cisplatin induced apoptosis. In line with this observation, data from the human protein atlas (www.proteinatlas.org) indicates that high expression of mitochondrial marker proteins (TFAM and TIMM23) is a favorable prognostic factor in ovarian cancer patients. Thus, we propose mitochondrial content as a biomarker for the response to platinum-based therapies. Functionally, this might be exploited by increasing mitochondrial content or mitochondrial ROS production to enhance sensitivity to cisplatin based anti-cancer therapies.

Highlights

Platinum compounds, i.e. cisplatin ([Pt(NH3)2Cl2]) or carboplatin ([Pt(C6H6O4)(NH3)2]) are among the most important agents for chemotherapeutic treatment of solid cancers
Sensitivity to cisplatin induced cell death correlates with mitochondrial content Platinum based chemotherapeutic compounds critically target nuclear DNA integrity
Cells from six cell lines (OVCAR-3, OVCAR-4, OVCAR-5, OVCAR-8, IGROV-1, and A2780) were incubated in the presence of 10 μM cisplatin for 48 h and induction of apoptosis was analyzed by Annexin V-FITC/PI staining and flow cytometric analysis (Fig. 1a)

Summary

Introduction

I.e. cisplatin ([Pt(NH3)2Cl2]) or carboplatin ([Pt(C6H6O4)(NH3)2]) are among the most important agents for chemotherapeutic treatment of solid cancers. Altered energy metabolism of cancer cells compared to normal tissue was first shown by Otto Warburg[4]. Kleih et al Cell Death and Disease (2019)10:851 biochemical phenomenon by which cancer cells generate energy from conversion of glucose to lactate even when properly oxygenated. Later it has become clear that not all tumor cells depend on “aerobic glycolysis” to generate energy as the oxygen supply is a function of the localization of the tumor cell within the tissue[5]. Energy in form of ATP is produced by mitochondria. These pivotal organelles influence more distant cellular features ranging from stemness to differentiation and cell death (apoptosis)[6]. “metabolic checkpoints” regulate induction of apoptosis and major cell death regulators like BAX and MCL-1 influence mitochondrial metabolism[7]

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