Ethanol alters cell cycle gene expression in human embryonic stem cells

Ethanol consumption during pregnancy has been shown to promote abnormal development in offspring. These abnormalities include microcephaly, growth retardation, neurological deficits and behavioral and cognitive deficiencies. Cyclins and cyclin dependent kinases (CDKs) are crucial for cell cycle progression, proliferation and differentiation of various cell types. The purpose of our study was to better understand the effects of ethanol on proliferation during early human development by using three human embryonic stem cell (hESC) lines. We found that treatment of ethanol at low doses (20 mM; four days) increased cell proliferation. The expression of key cell cycle regulators, CDKN2B (p15) and CDKN2A (p16) increased in two hESC lines, while CDKN1A (p21) and CDKN1B (p27) gene expression decreased in all cell lines. Western analysis showed a decrease in CDKN2B (p15) and CDKN2A (p16), while CDKN1A (p21) increased and CDKN1B (p27) remained unchanged. The changes in proliferation, gene expression, and protein synthesis suggest that ethanol can have a significant effect on cellular development at an early stage of human development. The correlation of our findings to in vivo conditions remains speculative, but the differential expression of regulators of the cell cycle may be involved in the manifestation of the many phenotypes seen in Fetal Alcohol Spectrum Disorder (FASD).