CONTROL OF ALKALINE PHOSPHATASE ACTIVITY IN C3H10T1/2 CELLS: ROLE OF RETINOIC ACID AND CELL DENSITY

Abstract

The enzyme alkaline phosphatase (AP) has been shown to be lost or inappropriately expressed during carcinogenesis in some tissues. ecause retinoic acid (RA) appears to play a role in the normal regulation of the enzyme (RA up-regulates AP in a variety of cell types) we have suggested that altered AP expression in some cancers may be caused by a defect in the ability of the cells to respond normally to retinoid. e have begun to use the chemically-transformable mouse embryo fibroblast cell, C3H10T1/2, to investigate this possibility. n this initial study we characterized AP regulation in normal C3H10T1/2 cells and show that: (a) 10-7 M BA increases AP activity within 3-4 h in serum-free medium; (b) serum inhibits short-term induction (0-8 h) in a concentration-dependent manner (10% serum causes complete inhibition); (c) during long-term RA exposure (24 h and 48 h), induction can be detected in serum-containing medium; (d) AP induction is dose related at RA concentrations from 10-10 M to 10-6 M in serum-free medium; (e) 10-5 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; (f) AP inducibility by RA requires near-confluent cell densities; and, (g) when cultures become confluent, cells become constitutive for AP and no longer require RA for enzyme expression. he effects of serum and cell density on AP inducibility by RA and implications of the up-regulation of AP for teratogenesis are discussed.

Citation

Reese, D., R. Larsen, AND F. Hornicek. CONTROL OF ALKALINE PHOSPHATASE ACTIVITY IN C3H10T1/2 CELLS: ROLE OF RETINOIC ACID AND CELL DENSITY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/239 (NTIS PB92198639), 1991.

Additional Information

Journal of Cellular Physiology 151:239-248

• CONTROL OF ALKALINE PHOSPHATASE ACTIVITY IN C3H10T1/2 CELLS: ROLE OF RETINOIC ACID AND CELL DENSITY