dinoprost and 1-oleoyl-2-acetylglycerol

Prostaglandin F2 alpha (PGF2 alpha), a mitogen for resting Swiss 3T3 cells, rapidly stimulates phosphorylation of an 80 kDa protein (80 K). 1-Oleoyl-2-acetylglycerol (OAG) and 12-O-tetradecanoyl phorbol-13-acetate (TPA) both protein kinase C (PKC) activators, also elicit 80 K phosphorylation. In contrast PGE1, PGE2 or PGF2 beta, which are non-mitogenic in these cells, had little or no action on this event. However PGE1 and PGE2 potentiate the PGF2 alpha proliferative effect but do not enhance its action on 80 K phosphorylation. These results suggest that PGF2 alpha mitogenic induction involves PKC signalling pathway activation while its enhancement by PGE1 or PGE2 occurs through a different mechanism(s).

Topics: 3T3 Cells; Alprostadil; Animals; Cell Division; Diglycerides; Dinoprost; Dinoprostone; DNA; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Mice; Phosphorylation; Protein Kinase C; Tetradecanoylphorbol Acetate

The inhibition of prostaglandin (PG) synthesis found in early human decidua is antagonized by the anti-progestin, ZK 98734. This action of ZK 98734 is abolished by actinomycin, an inhibitor of protein synthesis and by the calcium channel blocker, verapamil. Calmidazolium, an antagonist of the intracellular calcium binding protein calmodulin was less effective in inhibiting the stimulation of PG synthesis induced by the anti-progestin. Chronic stimulation of protein kinase C activity by 1-oleoyl-2-acetyl-sn-glycerol (OAG) induced a slight reduction of PG release and was antagonized by polymixin. These findings suggest that inhibition of PG synthesis in early pregnancy is caused by progesterone and that increased release of PGs induced by anti-progestins is dependent on new protein formation and requires extracellular calcium.

Topics: Abortion, Spontaneous; Calmodulin; Cells, Cultured; Dactinomycin; Decidua; Diglycerides; Dinoprost; Estrenes; Female; Humans; Imidazoles; Kinetics; Pregnancy; Progesterone; Progestins; Radioimmunoassay; Verapamil

Prostaglandin F2 alpha (PGF2 alpha) release from the uterus causes luteolysis in ruminants, and oxytocin is thought to be a regulator of this release. In the present study, we have examined the mechanisms involved in oxytocin stimulation of PGF2 alpha secretion by bovine endometrium in vitro. Endometrial tissue explants, obtained from heifers at Day 19 or 20 (n = 3) and Day 0 (estrus, n = 5) of the estrous cycle, were incubated for 2 h and 6 h, and PGF2 alpha concentration in the medium was determined by radioimmunoassay (RIA). Basal PGF2 alpha release increased for up to 6 h and was significantly stimulated after 2 h of incubation with 100 microU and 1000 microU of oxytocin at Day 0 but not at Day 19 or 20. Secretion of PGF2 alpha was not affected by cholera toxin (10 ng/ml) or the cyclic nucleotide analogs dibutyryl cyclic adenosine 3',5'-monophosphate and dibutyryl cyclic guanosine 3',5'-monophosphate at a concentration of 1 mM. A protein kinase A inhibitor (500 microM) had no effect on the oxytocin-induced release of PGF2 alpha. Both the phorbol ester, 12-myristate-13-acetate (100 mM), and the non-phorbol stimulator of protein kinase C, 1-octanoyl-2-acetylglycerol (500 microM), significantly stimulated PGF2 alpha secretion to the same extent as oxytocin. Neither basal nor stimulated PGF2 alpha release was affected by the calcium ionophore A23187 (0.1-5.0 microM). However, PGF2 alpha secretion was sensitive to cycloheximide (1 microgram/ml) suggesting that protein synthesis may be involved. In conclusion, these data suggest that the stimulation of PGF2 alpha by oxytocin is via the protein kinase C effector pathway.

Topics: Animals; Arachidonic Acids; Bucladesine; Calcimycin; Carcinogens; Cattle; Cholera Toxin; Cycloheximide; Dibutyryl Cyclic GMP; Diglycerides; Dinoprost; Endometrium; Female; Nucleotides, Cyclic; Oxytocin; Phorbol Esters; Protein Kinase Inhibitors; Tetradecanoylphorbol Acetate; Uterus

Epidermal melanocytes (MC) synthesize melanin in response to ultraviolet radiation (UVR). The mechanisms mediating the UV-induced activation of melanogenesis are unknown but since UVR induces turnover of membrane phospholipids generating prostaglandins (PGs) and other products, it is possible that one of these might provide the activating signal. We have examined the effects of prostaglandins (PGs) E1, E2, D2, F2 alpha, and di-acyl glycerol upon the UV-induced responses of cultured human MC and the Cloudman S91 melanoma cell line. The PGs had little effect on unirradiated cells and did not alter the response to UVR in either human MC or S91 melanoma cells. However, a synthetic analogue of di-acyl glycerol, 1-oleyl 2-acetyl glycerol (OAG), caused a significant (P less than 0.0001), dose-related augmentation of melanin content both in human MC (seven-fold) and S91 cells (three-fold). UVR caused a significant augmentation of the OAG-induced melanogenesis of both human MC and S91 cells. Since OAG is known to activate protein kinase C, it was possible that the observed modulation of the UVR signal could be via that pathway. Di-octanoyl glycerol, another di-acyl glycerol, which activates kinase C, caused a small (70%) increase in melanogenesis in MC which was not altered by UVR. However, 12-0 tetradecanoyl phorbol 13-acetate (TPA), a potent activator of protein kinase C, had no significant effect on either basal or UV-induced melanin synthesis in either cell type. These data suggest that the UV-induced signal activating melanogenesis could be mediated by di-acyl glycerol. Furthermore, they imply that the signal is transduced via an alternative, pathway that might be independent of protein kinase C.

Topics: Alprostadil; Animals; Cell Division; Diglycerides; Dinoprost; Dinoprostone; Glycerides; Humans; Male; Melanins; Melanocytes; Melanoma, Experimental; Mice; Prostaglandin D2; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured; Ultraviolet Rays

The combination of palytoxin and 1-oleoyl-2-acetyl-glycerol (OAG) synergistically stimulates production of 6-keto-PGF1 alpha and PGF2 alpha by rat liver cells (the C-9 cell line). In contrast, the combination of 12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters (TPA, dihydroteleocidin B, aplysiatoxin, phorbol-12,13-didecanoate) and OAG does not. Production of 6-keto-PGF1 alpha by palytoxin added with recombinant murine interleukin-1 (IL-1) or with insulin is also greater than the sum of the two effects taken independently. Palytoxin and OAG individually stimulate the release of radiolabeled compounds from the rat liver cells pre-labeled with [3H]arachidonic acid and also act synergistically to release labeled metabolites. After separation by h.p.l.c., these materials co-chromatograph with authentic 6-keto-PGF1 alpha and arachidonic acid. The synergistic stimulation by palytoxin and OAG is biphasic; a rapid synergistic production of 6-keto-PGF1 alpha or release of radiolabel from [3H]arachidonic acid prelabeled cells is followed, after approximately 2-4 h, by a prolonged synergistic response.

Topics: 6-Ketoprostaglandin F1 alpha; Acrylamides; Animals; Arachidonic Acid; Arachidonic Acids; Carcinogens; Cell Line; Cnidarian Venoms; Diglycerides; Dinoprost; Drug Synergism; Glycerides; Insulin; Interleukin-1; Kinetics; Liver; Phorbols; Prostaglandins F; Rats; Structure-Activity Relationship; Tetradecanoylphorbol Acetate

Recombinant murine IL 1 stimulated arachidonic acid metabolism by rat liver cells (the C-9 cell line) and squirrel monkey smooth muscle cells, and in the presence of tumor promoters this stimulation was synergistic. In the rat liver cells that had been prelabeled with [3H]arachidonic acid, the release of 6-keto-PGF1 alpha and arachidonic acid also was stimulated by the IL 1, and this release was synergistic in the presence of TPA. 1-Oleoyl-2-acetyl-glycerol (OAG) stimulated prostaglandin production, and IL 1 synergized the prostaglandin production in the presence of OAG. OAG and TPA mimic the endogenous activator of protein kinase C, 1,2-diacylglycerol, and therefore IL 1 may amplify arachidonic acid metabolism during signal transmission processes.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Cell Line; Diglycerides; Dinoprost; Dinoprostone; Drug Synergism; Epoprostenol; Glycerides; Interleukin-1; Liver; Mice; Muscle, Smooth, Vascular; Phorbol Esters; Prostaglandins E; Prostaglandins F; Protein Kinase C; Rats; Recombinant Proteins; Saimiri