JB6 murine epidermal cell lines sensitive and resistant to 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transformation exhibit differential arachidonic acid metabolism in response to TPA and the calcium ionophore A23187.

In a study of arachidonic acid metabolism in murine epidermal JB6 cells, promoter-sensitive (P+) and promoter-resistant (P-) variants, labeled with [3H]arachidonic acid, were treated successively with 12-O-tetradecanoylphorbol-13-acetate (TPA) and the calcium ionophore A23187. Released radiolabel was separated by HPLC and identified by coelution of standards. Prostacyclin release was then quantified by radioimmunoassay for 6-keto prostaglandin (PG)F1 alpha. A23187 alone resulted in a small but significant enhanced release of radiolabel from both cell variants (0.7 +/- 0.2% for P- and 0.6 +/- 0.3% for P+ cells; mean +/- SD). Treatment with TPA and subsequent treatment with A23187 resulted in a synergistically enhanced release of radiolabel from both cell variants (4.1 +/- 0.8% for P- and 3.4 +/- 0.9% for P+ cells) relative to that with either agent alone. Although the predominant product for each treatment regimen was prostaglandin E2 (PGE2), the TPA-resistant cells (P-) released significantly more 6-keto PGF1 alpha, a stable breakdown product of PGI2, than did the TPA-sensitive (P+) cells. These results indicate differential arachidonic acid metabolism between JB6 cell variants resistant and sensitive to TPA-induced transformation.