Rapid induction of alkaline phosphatase activity by retinoic acid

Retinoic acid (vitamin A acid) increased alkaline phosphatase activity in cultured cells derived from both normal rat prostate and the Dunning R-3327 transplantable prostatic adenocarcinoma. Retinoic acid was found to be 3–4-fold more effective as an inducer of enzyme activity than retinol or retinal. In one rapidly-growing cell line (UMS-1541Q) which has a barely-detectable level of enzyme activity in the uninduced state, increased activity could be detected as early as 3–4 hours after the addition of 10μM retinoic acid. This increase was totally blocked by actinomycin D and cycloheximide. The demonstrated rapid inducibility of alkaline phosphatase activity provides a specific marker for the action of retinoic acid at the molecular level.