Effects of 17β-estradiol on proliferation, cell viability and intracellular redox status in native human lens epithelial cells

Purpose: The purpose of this study was to examine the effects of 17 beta-estradiol on proliferation, cell death and redox status in cultured human lens epithelial cells (HLECs). Methods: HLECs were exposed to 17 beta-estradiol after which cell viability was measured by 3-(4,5dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) and the number of mitotic and apoptotic cell nuclei was determined after staining with Hoechst 33342. Apoptosis was also determined by measuring caspase-3 activity and propidium iodide was used to determine the proportion of non-viable cells. Pro-and antioxidative effects of 17 beta-estradiol was investigated by measuring peroxides, superoxides and glutathione, using dichlorofluorescein diacetate (DCFH-DA), dihydroethidium (HET), and monochlorobimane (MCB), respectively. Effects on mitochondrial membrane potential were determined using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1). The ability of 17 beta-estradiol to prevent reactive oxygen species (ROS)-production in HLECs after exposure to 25 mu M H(2)O(2) for 24h was also measured. Results: This study demonstrates increased mitotic activity in HLECs exposed to physiologic concentrations of 17 beta-estradiol (1 nM). Pharmacological concentrations of 17 beta-estradiol caused increased number of apoptotic cell nuclei and caspase-3 activation. Physiologic concentrations of 17 beta-estradiol (0.1-10 nM) stabilized the mitochondrial membrane potential. Similar or slightly higher concentrations of 17 beta-estradiol (0.01-1 mu M) protected against H(2)O(2)-induced oxidative stress as evident by decreased levels of peroxides and superoxides. Conclusions: The present study demonstrates mitogenic and anti-oxidative effects of 17 beta-estradiol at physiologic concentrations, whereas pharmacological levels induced oxidative stress and acted pro-apoptotic in cultured lens cells.