Antioxidants induce apoptosis of rat ovarian theca-interstitial cells.

Regulation of growth of ovarian theca-interstitial tissues is essential for normal ovarian development and function. Reactive oxygen species are involved in modulation of signal transduction pathways, including regulation of tissue growth and apoptosis. Previously, we have demonstrated that antioxidants inhibit proliferation of theca-interstitial cells. This report evaluates the effects of antioxidants on apoptosis of rat theca-interstitial cells. The cells were cultured in chemically defined media without or with vitamin E succinate and ebselen. Apoptosis was evaluated by cytochemical assessment of nuclear morphology, activity of executioner caspases 3 and 7, and determination of staining with annexin V in combination with propidium iodide. Both tested antioxidants induced significant morphological changes consistent with apoptosis, including chromatin condensation, nuclear shrinkage, and pyknosis. Antioxidants also induced other hallmarks of apoptosis including increased activity of caspases 3/7 as well as increased staining with annexin V. The present findings demonstrate that antioxidants with distinctly different mechanisms of action induce a series of events consistent with the process of apoptosis in ovarian mesenchyme. These observations may be of translational-clinical relevance, providing mechanistic support for the use of antioxidants in the treatment of PCOS, a condition associated with excessive growth and activity of theca-interstitial cells.

Statins inhibit growth of human theca-interstitial cells in PCOS and non-PCOS tissues independently of cholesterol availability.

CONTEXT: Polycystic ovary syndrome (PCOS) is associated with ovarian enlargement, prominent theca-interstitial hyperplasia, and excessive androgen production. Recent clinical trials have demonstrated that statins, 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors, decrease androgen levels in women with PCOS. OBJECTIVE: The present study evaluated the effect of statins on proliferation of human ovarian theca-interstitial cells. DESIGN AND SETTINGS: In vitro experiments were performed in the university research laboratory. PATIENTS: Human theca-interstitial cells were isolated from ovaries of PCOS (n=4) and non-PCOS (n=4) patients. MAIN OUTCOME MEASURES: The cells were incubated for 48 h without additives (control) or with simvastatin (3-30 µm), mevastatin (3-30 µm), and/or the cell- and mitochondrion-permeable form of cholesterol (22-hydroxycholesterol; 10 µm). To determine whether the effects of statins could be affected by leukocytes, the experiment was carried out on cells not purified of leukocytes and cells purified using anti-CD-45 immunomagnetic beads. The effect of statins on proliferation was evaluated by determination of DNA synthesis using radiolabeled thymidine-incorporation assay and by quantification of viable cells using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenil)-2H-tetrazolium assay. RESULTS: Statins induced an inhibition of DNA synthesis in both the absence and the presence of 22-hydroxycholesterol; furthermore, 22-hydroxycholesterol alone also inhibited DNA synthesis. These effects of statins and 22-hydroxycholesterol were confirmed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenil)-2H-tetrazolium assay. Comparable inhibition of proliferation was observed in cells obtained from women with and without PCOS and in cell preparations treated and not treated with anti-CD-45 immunomagnetic beads. CONCLUSIONS: Statins inhibit proliferation of human theca-interstitial cells irrespective of the availability of cholesterol and independently of leukocytes both in normal and PCOS ovaries.

Role of isoprenylation in simvastatin-induced inhibition of ovarian theca-interstitial growth in the rat.

Statins are competitive inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, a rate-limiting step of the mevalonate pathway. The pleiotropic effects of statins may be due to inhibition of cholesterol synthesis, as well as decreased availability of several biologically important intermediate components of the mevalonate pathway, including two substrates for isoprenylation (farnesyl pyrophosphate [FPP] and geranylgeranyl pyrophosphate [GGPP]). Recently, we demonstrated statin-induced inhibition of ovarian theca-interstitial cell proliferation in vitro, as well as reduction of testosterone levels in women with polycystic ovary syndrome (PCOS). This study evaluates the relative contribution of inhibition of isoprenylation and/or cholesterol availability to the modulation of theca-interstitial proliferation. Rat theca-interstitial cells were cultured in chemically defined media with or without simvastatin, FPP, GGPP, squalene, and/or two membrane-permeable forms of cholesterol (25-hydroxycholesterol and 22-hydroxycholesterol). Simvastatin inhibited DNA synthesis and the count of viable cells. The effects of simvastatin were partly abrogated by FPP and GGPP but not by squalene or cholesterol. Inhibition of farnesyl transferase and geranylgeranyl transferase reduced cell proliferation. The present findings indicate that simvastatin inhibits proliferation of theca-interstitial cells, at least in part, by reduction of isoprenylation. These observations provide likely mechanisms explaining clinically observed improvement of ovarian hyperandrogenism in women with PCOS.

Statins inhibit growth of human endometrial stromal cells independently of cholesterol availability.

Endometriosis is characterized by ectopic growth of endometrial tissues. Statins, inhibitors of 3-hydroxy-3methylglutaryl-coenzyme A reductase (HMGCR), have been shown to decrease proliferation of several mesenchymal tissues. Actions of statins may be related to decreased availability of cholesterol as well as intermediate metabolites of the mevalonate pathway downstream of HMGCR. This study was designed to evaluate effects of statins on growth of endometrial stromal cells and to investigate mechanisms of these effects. Human endometrial stromal cells were cultured in the absence and in the presence of serum and with or without mevastatin and simvastatin. DNA synthesis and viable cell numbers were determined. Effects of statins were also evaluated in the presence of mevalonate and squalene. Furthermore, effects on phosphorylation of mitogen-activated protein kinase 3/1 (MAPK3/1) (also known as extracellular signal-regulated kinase [ERK1/2]) were determined. Mevastatin and simvastatin induced a concentration-dependent inhibition of DNA synthesis and viable cell count in chemically defined media and in the presence of serum. Mevalonate, but not squalene, abrogated inhibitory effects of statins on cell proliferation. Statins inhibited MAPK3/1 phosphorylation. This is the first study demonstrating that statins inhibit growth of endometrial stromal cells. This effect is also demonstrable in the presence of a supply of cholesterol and may be related to decreased activation of MAPK3/1. The present observations may be relevant to potential therapeutic use of statins in conditions such as endometriosis.