Induction by short-chain fatty acids of alkaline phosphatase activity in cultured mammalian cells.

Short-chain fatty acids, such as propionic, n-butyric, n-butyric, n-valeric, isovaleric, n-caproic, and n-caprylic acids, induce alkaline phosphatase activity in cultured mammalian cells. Long-chain fatty acids have no similar effects. With B-6 cells (mouse X Chinese hamster cell hybrids), n-butyrate at 2 to 5 mM exhibits the greatest activity. Induction begins exponentially about 24 hours after addition of the fatty acid and continues over 48 hours. Studies on the inducing activity-structure relationship revealed the necessity of a carboxyl and an ethyl or longer alkyl group. n-Butyrate shows a marked synergistic action of induction when added along with other types of inducers: adenosine 3':5'-cyclic monophosphate (cAMP) or 5-bromodeoxyuridine (BrdU). Treatment of other cell lines with either n-buryrate, cAMP, or BrdU revealed a cell-type specific response pattern of alkaline phosphatase. The biological significance of this effect of short-chain fatty acids is discussed.