Mitotane Inhibits Proliferation and Affects Mitochondrial Metabolism in Human Breast, Lung and Colon Cancer Cell Lines

Mitotane acts specifically on adrenocortical tissue and is used as a standard treatment in adrenocortical cancer. The exact mechanism of its action remains unknown, despite its clinical use for more than 60 years. Recently it has been suggested that in human adrenocortical cancer cells, mitotane alters mitochondrial respiratory chain activity by inducing cytochrome c oxidase defect. The aim of the study was to assess the effect of Mitotane on proliferation, apoptosis and mitochondrial metabolism in human breast (MCF7), lung (H1975) and colon (HKe-3) cancer cell lines and compare it with our previous results in human adrenocortical cancer (H295R). The proliferation rate of cells was assessed by the resazurin assay. The apoptosis induction was determined by the caspase-3-like activity assay. Changes in expression of the 84 genes involved in mitochondrial metabolism (Complex I: NADH-Coenzyme Q Reductase; Complex II: Succinate-Coenzyme Q Reductase; Complex III: Coenzyme Q-Cytochrome c Reductase; Complex IV: Cytochrome c Oxidase; Complex V: ATP Synthase) were assessed using Mitochondrial Energy Metabolism Plus PCR Arrays, Qiagen. Optimum cytotoxic effects of Mitotane were observed after 24 and 48 hours incubation for H295R cells and HKe-3, MCF7, H1975; respectively. In the H295R cell line a 10uM concentration of Mitotane resulted in 27.0±0.9% cytotoxicity, whereas in HKe-3, MCF7 and H1975 cell lines concentration of 40uM caused cytotoxicity of 48.5±5.2%; 40.2±2.5% and 28.6±2.1%, respectively. 100% cytotoxicity was achieved at a concentration of 20uM for H295R and 100uM for HKe-3, MCF7 and H1975. Cytotoxic effects were negatively influenced by the number of cells/well in H295R, HKe-3, and H1975 but not in MCF7. Although Mitotane had a strong cytotoxic effect on all tested cell lines, caspase-3 activity was induced only in H295R cell line. Expression levels of several genes involved in mitochondrial metabolism was changed by Mitotane; however different genes were affected in different cell lines. Of 84 genes investigated, mRNA levels were decreased/increased by >2 folds in 18/4; 10/29; 6/7 and 28/2 in H295R, HKe-3, MCF7 and H1975, respectively. Mitotane exhibits anti-proliferative activity in breast, colon and lung cancer cell lines. It affects mitochondrial metabolism regardless of the type of cancer and hence his cytotoxic effect is not specific to the adrenal cortex only.
Mitotane Inhibits Proliferation and Affects Mitochondrial Metabolism in Human Breast, Lung and Colon Cancer Cell Lines. Available from: https://www.researchgate.net/publication/274961069_Mitotane_Inhibits_Proliferation_and_Affects_Mitochondrial_Metabolism_in_Human_Breast_Lung_and_Colon_Cancer_Cell_Lines [accessed Apr 14, 2015].