Induction of apoptosis by sphingosine-1-phosphate in human hepatoma cells is associated with enhanced expression of bax gene product.

Sphingolipid metabolites are important regulators of cell growth and differentiation. Recent studies have suggested that sphingosine-1-phosphate, a biologically active sphingolipid metabolite, acts as a crucial messenger in apoptosis. In the present work, we examined the expression levels of the members of the bcl-2-related gene family to determine their roles in sphingosine-1-phosphate-induced apoptosis is human hepatoma cells. Our results indicate that sphinogosine-1-phosphate-induced apoptosis is associated with enhanced expression of Bax protein. Moreover, the regulation of bax gene expression by sphingosine-1-phosphate is independent of the p53 tumor suppressor.