Modulation of JB6 mouse epidermal cell transformation response by the prostaglandin F_2α receptor

Prostaglandin F_2α (PGF_2α) modulates clonal selection processes in the mouse skin model of carcinogenesis. In this study we investigated whether JB6 mouse epidermal cells expressed a functional PGF_2α receptor (FP) coupled with a cell-transformation response. Treatment of JB6 cells with an FP agonist (fluprostenol) potently (pM-nM) increased anchorage-dependent and anchorage-independent growth. Inositol phospholipid accumulation and extracellular signal-regulated kinase (Erk) activity were increased in cells treated with FP agonists, consistent with established FP- related signal transduction. FP mRNA was detected by reverse transcription-polymerase chain reaction, and the average specific [³H]PGF_2α binding was 8.25 ± 0.95 fmol/mg protein. Erk activity and colony size were increased by cotreatment of JB6 cells with epidermal growth factor (EGF) and fluprostenol to a greater extent than with either treatment alone, whereas the cotreatment effect on colony number appeared to be simply additive. Collectively, our data indicated that JB6 cells expressed a functional FP coupled with transformation-related signal transduction and the regulation of clonal selection processes. Erk activity appears to be a convergence point in the EGF and FP pathways. The data raise the possibility that the FP contributes to clonal selection processes but probably plays a more important role as a response modifier.