Calcium lonophore A-23187 and 12-O-Tetradecanoyl-phorboM 3-acetate Stimulation of Prostaglandin Synthesis in Herpes Simplex Virus Type 2-transformed Rat Cells1

The purpose of this investigation was to determine whether cells transformed by herpes simplex virus type 2 (HSV-2) can be stimulated to synthesize prostaglandins (PG). Stimulation was determined by measuring the release of PG into overlay fluids from cell monolayers prelabeled with [3H]arachidonic acid. Re sults showed that Ca2+ ionophore A-23187 markedly stimulated arachidonic acid release starting 30 min after treatment of HSV2-transformed and nontransformed rat embryo fibroblast cells. However, only HSV-2-transformed cells were stimulated in pro duction of PG. HSV-2-transformed, nontumorigenic, rat embryo fibroblast, line G, clone 2.0 cells synthesize nearly equal amounts of prostaglandin E2 (PGE2) and prostaglandin F2o, while tumor (rat fibrosarcoma) cells synthesize primarily PGE2. Stimulation of PGE2 synthesis by Ca2+ ionophore A-23187 or 12-O-tetradecanoyl-phorbol-13-acetate decreased as rat fibrosarcoma cells were serially passaged in tissue culture. At low passage of parental rat fibrosarcoma cells, four distinct morphological clonal cell lines were isolated, which varied markedly in their capacity to be stimulated in PG synthesis by 12-O-tetradecanoyl-phorbol13-acetate. There was correlation between the capacity of clone 1 cells to be stimulated in PGE2 synthesis by serum alone and capacity of the tumors produced by the clone 1 cells to metastasize to the lungs of syngeneic tumor-bearing rats. In summary, cell transformation by HSV-2 appears to be essential for stimu lation of PG synthesis in cells. The capacity to be stimulated in arachidonic acid metabolism and PG synthesis may be important in the process of carcinogenesis by a putative human cancer virus.