||Control of Alkaline Phosphatase Activity in C3H10T1/2 Cells: Role of Retinoic Acid and Cell Density.
Reese, D. H. ;
Larsen, R. A. ;
Hornicek, F. J. ;
||Environmental Protection Agency, Washington, DC. Office of Health and Environmental Assessment. ;AScI Corp., McLean, VA.
Alkaline phosphatase ;
Serum-free media ;
Enzyme induction ;
Dose-response relationships ;
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The authors have begun to use the chemically-transformable mouse embryo fibroblast cell, C3H10T1/2, to investigate that altered AP expression in some cancers may be caused by a defect in the ability of the cells to respond normally to retinoid. In the initial study they characterized AP regulation in normal C3H10T1/2 cells and show that: (1) RA increases AP activity within 3-4 h in serum-free medium; (2) serum inhibits short-term induction (0-8 h) in a concentration-dependent manner (10% serum causes complete inhibition); (3) during long-term RA exposure (24 h and 48 h), induction can be detected in serum-containing medium; (d) AP induction is dose related in serum-free medium; (5) ten to the minus fifth power M RA is ineffective at inducing AP in serum-free medium during 8 h but is the most effective concentration in serum-containing medium during 24 h and 48 h exposures; (6) AP inducibility by RA requires near-confluent cell densities; and, (7) when cultures become confluent, cells become constitutive for AP and no longer require RA for enzyme expression.