Mitotane alters mitochondrial respiratory chain activity by inducing cytochrome c oxidase defect in human adrenocortical cells: Mitotane-induced cytochrome c oxidase defectReport as inadecuate




Mitotane alters mitochondrial respiratory chain activity by inducing cytochrome c oxidase defect in human adrenocortical cells: Mitotane-induced cytochrome c oxidase defect - Download this document for free, or read online. Document in PDF available to download.

* Corresponding author 1 Récepteurs stéroïdiens : physiopathologie endocrinienne et métabolique 2 Service de Biochimie Bicêtre 3 Institut Cochin 4 IGR - Institut Gustave Roussy 5 HRA - Laboratoire HRA-Pharma 6 Service de génétique moléculaire, pharmacogénétique et hormonologie 7 Service d-endocrinologie 8 Médecine nucléaire Département d-imagerie médicale

Abstract : Mitotane, 1,1-dichloro-2-o-chlorophenyl-2-p-chlorophenylethane o,p-DDD is the most effective medical therapy for adrenocortical carcinoma but its molecular mechanism of action remains poorly understood. Although mitotane is known to have mitochondrial mt effects, a direct link to mitochondrial dysfunction has never been established. We examined the functional consequences on proliferation, steroidogenesis, and mitochondrial respiratory chain, biogenesis and morphology, of mitotane exposure in two human adrenocortical cell lines, the steroid-secreting H295R line and the non-secreting SW13 line. Mitotane inhibited cell proliferation in a dose- and a time-dependent manner. At the concentration 50μM 14 mg-L, which corresponds to the threshold for therapeutic efficacy, mitotane drastically reduced cortisol and 17-hydroxyprogesterone secretions by 70%. This was accompanied by significant decreases in the expression of genes encoding mitochondrial proteins involved in steroidogenesis STAR, CYP11B1, CYP11B2. In both H295R and SW13 cells, 50μM mitotane significantly inhibited 50% the maximum velocity of the activity of the respiratory chain complex IV cytochrome c oxidase, COX. This effect was associated with a drastic reduction in steady-state levels of the whole COX complex as revealed by Blue Native PAGE and reduced mRNA expression of both mtDNA-encoded COX2 and nuclear DNA-encoded COX4 subunits. In contrast, the activity and expression of respiratory chain complexes II and III were unaffected by mitotane treatment. Lastly, mitotane exposure enhanced mitochondrial biogenesis increase in mtDNA content and PGC1α expression and triggered fragmentation of the mitochondrial network. Altogether, our results provide first evidence that mitotane induced a mitochondrial respiratory chain defect in human adrenocortical cells.

keyword : Adrenocortical carcinoma mitotane p-DDD mitochondria cytochrome c oxidase





Author: Ségolène Hescot - Abdelhamid Slama - Anne Lombes - Angelo Paci - Hervé Remy - Sophie Leboulleux - Rita Chadarevian - Séverine

Source: https://hal.archives-ouvertes.fr/



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