Tumor Necrosis Factor-α Regulates Steroidogenesis, Apoptosis, and Cell Viability in the Human Adrenocortical Cell Line NCI-H295R

Abstract

TNF-α regulates the hypothalamo-pituitary-adrenal axis at several levels. It has been shown to modify adrenal steroidogenesis in many species, and it is supposed to act as an auto/paracrine factor. However, its significance in human adrenocortical function remains unclear. Therefore, we investigated the effect of TNF-α on adrenal steroidogenesis, expression of the key steroidogenic genes, apoptosis, and cell viability in the human adrenocortical cell line NCI-H295R. TNF-α treatment (1 nm for 48 h) decreased the basal production of cortisol, androstenedione, dehydroepiandrosterone sulfate (DHEAS), and aldosterone (14, 18, 35, and 52%, respectively), and the 8-bromo-cAMP-induced production of cortisol, androstenedione, dehydroepiandrosterone (DHEA), and DHEAS (44, 66, 58, and 48%, respectively). However, when the steroid production data were normalized by the cell number, TNF-α increased the basal production of cortisol, androstenedione, DHEA, DHEAS, and aldosterone (137, 121, 165, 73, and 28%, respectively), and the 8-bromo-cAMP-induced production of cortisol, DHEAS, and aldosterone (122, 121, and 256%, respectively). This was accompanied by a parallel increase in the expression of the genes encoding for the steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase 2, and 17-hydroxylase/17,20-lyase (74, 200, and 50%, respectively; quantitative real-time RT-PCR analysis). TNF-α increased caspase 3/7 activity (an indicator of apoptosis) and decreased cell viability dose and time dependently. The effect of TNF-α on apoptosis was neutralized by a monoclonal TNF-α antibody. These findings indicate that TNF-α is a potent regulator of steroidogenesis and cell viability in adrenocortical cells. TNF-α may have physiological and/or pathophysiological significance as an endocrine and/or paracrine/autocrine regulator of adrenocortical function.