Ethanol signals for apoptosis in cultured skin cells

Ethanol is commonly used in cosmetic and pharmaceutical preparations. To test whether ethanol may cause apoptosis in skin cells, we treated A431 epidermoid skin cells and neonatal human primary skin cells with different concentrations of ethanol, for different time periods. Ethanol was toxic to cells in both a dose- and time-dependent manner and increased the percentage of cells undergoing apoptosis. Treatment of cells with 40 and 100 mM ethanol increased release of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) into culture medium and increased its expression in cells. The TNF-alpha was toxic to A431 epidermoid skin cells at concentrations similar to those released by cells on exposure to ethanol. Ethanol-treated cells examined by electron microscopy showed organelle damage, condensed chromatin, and apoptotic bodies. Therefore, even at low concentrations, ethanol may induce apoptosis in skin cells by enhancing the effects of TNF-alpha.