ABSTRACT
Growth factors stimulating DNA synthesis in mouse 3T3, human DU145, and LNCaP were partially purified from human benign hyperplastic and cancerous prostates. These factors have a high affinity for heparin sepharose and are eluted from the heparin-sepharose column, at 1.2 to 1.9 M NaCl. In normal prostates, the high affinity human prostatic growth factor occurred only in extremely small amounts. The high affinity growth factors stimulate DNA synthesis in 3T3, DU145, and LNCaP. Stimulation was significantly enhanced by 5 alpha-dihydrotestosterone and 17 beta-estradiol in the androgen sensitive LNCaP cell line. SDS-PAGE and isoelectrofocusing confirmed that the partially purified factors had a molecular weight of 18 kDa and acidic isoelectric points of pH 3.6 and 4.7.
Subject(s)
DNA/biosynthesis , Growth Substances/isolation & purification , Prostate/metabolism , Steroids/pharmacology , Thymidine/metabolism , Adult , Aged , DNA, Neoplasm/biosynthesis , Dihydrotestosterone/pharmacology , Electrophoresis, Polyacrylamide Gel , Estradiol/pharmacology , Growth Substances/metabolism , Humans , Isoelectric Focusing , Male , Middle Aged , Molecular Weight , Prostatic Hyperplasia/metabolism , Prostatic Neoplasms/metabolismABSTRACT
The effects of epidermal growth factor (EGF) and somatostatin-14 (SS) on growth of Mia PaCa-2 cells in cell culture were examined. EGF had no effect on cell growth in sera containing media but significantly increased growth in sera-free media. The effect of EGF was complete within 18 h. SS added with EGF entirely eliminated the growth stimulation of EGF. SS added to cells in culture with sera inhibited their growth as well.
Subject(s)
Epidermal Growth Factor/pharmacology , Neoplasms, Hormone-Dependent/pathology , Pancreatic Neoplasms/pathology , Somatostatin/pharmacology , Cell Division/drug effects , Cell Line , Epidermal Growth Factor/physiology , ErbB Receptors/drug effects , ErbB Receptors/physiology , Humans , Neoplasms, Hormone-Dependent/drug therapy , Neoplasms, Hormone-Dependent/physiopathology , Pancreatic Neoplasms/drug therapy , Pancreatic Neoplasms/physiopathologyABSTRACT
A membrane receptor and a cytosolic receptor for somatostatin were found in a human undifferentiated pancreatic cancer cell line (MIA PaCa-2). Binding of somatostatin to this membrane receptor activates dephosphorylation of a phosphotyrosyl-membrane protein whose phosphorylation was promoted by epidermal growth factor (EGF). Vanadate, a purported inhibitor of dephosphorylation, interferes with the action of somatostatin. These findings suggest a possible biochemical mechanism by which somatostatin may inhibit the growth of human pancreatic cancers.
Subject(s)
Membrane Proteins/metabolism , Pancreatic Neoplasms/metabolism , Phosphoproteins/metabolism , Somatostatin/pharmacology , Cell Line , Epidermal Growth Factor/pharmacology , Humans , Phosphoprotein Phosphatases/metabolism , Phosphorylation , Receptors, Cell Surface/drug effects , Receptors, Cell Surface/physiology , Receptors, Somatostatin , Somatostatin/analogs & derivatives , Somatostatin/metabolism , Vanadates , Vanadium/pharmacologyABSTRACT
The antifibrinolytic activity of cytosol from Dunning R3327H rat prostate tumors was studied. The prostate tumors from rats treated with D-Trp6-LH-RH had 2.5 times lower plasminogen activator activity than tumors from untreated rats. This was due to the presence of an inhibitor of plasminogen activator as well as a reduction in residual activity of plasminogen activator(s). Only the cytosolic extracts from prostate tumors of rats treated with D-Trp6-LH-RH contained this inhibitor. The purified inhibitor (m.w. 21,000), formed a complex with urokinase and partially purified plasminogen activator(s) from prostate tumors of untreated as well as D-Trp6-LH-RH treated rats. The increase in antifibrinolytic activity after treatment with LH-RH analogs may be an important factor in reducing the invasiveness of the prostate tumor.
Subject(s)
Gonadotropin-Releasing Hormone/analogs & derivatives , Plasminogen Activators/antagonists & inhibitors , Plasminogen Inactivators , Prostatic Neoplasms/metabolism , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Animals , Cytosol/analysis , Gonadotropin-Releasing Hormone/pharmacology , Gonadotropin-Releasing Hormone/therapeutic use , Male , Prostatic Neoplasms/drug therapy , Rats , Rats, Inbred Strains , Triptorelin PamoateABSTRACT
We investigated phosphorylation in Dunning R-3327H prostate tumor tissue of untreated rats, and rats treated with the agonist D-Trp6-LH-RH and antagonist N-Ac-D-p-Cl-Phe1,2,D-Trp3,D-Arg6,D-Ala10-LH-RH. The total phosphorylation was significantly higher in Dunning tumors than in normal ventral and dorsal prostate. Incorporation of 32P into tumor tissue of rats treated with D-Trp6-LH-RH was significantly lower than in tumors from untreated animals. The tumor regression produced by LH-RH agonist appeared to be linked with changes in the pattern of tumor protein phosphorylation. Although inhibition of tumor growth also occurred after administration of the LH-RH antagonist, no significant changes in phosphorylation were observed. The dissimilarity of effects of the agonists and the antagonists on protein phosphorylation in rat prostate tumors may be related to the differences in the mechanisms of action of these two types of LH-RH analogues.
Subject(s)
Gonadotropin-Releasing Hormone/analogs & derivatives , Neoplasm Proteins/metabolism , Phosphoproteins/metabolism , Prostatic Neoplasms/metabolism , Animals , Gonadotropin-Releasing Hormone/therapeutic use , Male , Phosphorylation , Prostatic Neoplasms/drug therapy , Rats , Triptorelin PamoateABSTRACT
Plasminogen activator and nonspecific proteolytic activity in transplantable squamous cell rat prostate tumor 11095 were measured by a fluorometric method. Prostate tumors which regressed after treatment with D-Trp-6-LH-RH had 10-fold lower concentrations of plasminogen activator(s) per mg of protein, and considerably higher levels of nuclear androgen receptor. On the other hand, there were no significant changes in nonspecific proteolytic activity in tumor tissue between untreated and D-Trp-6-LH-RH treated rats. The prostate tumor had at least three different plasminogen activator-like bands, as determined by polyacrylamide gel electrophoresis with plasminogen as substrate. The decreased activity of plasminogen activator(s) and considerably higher levels of nuclear androgen receptors correlate with the regression of prostate tumors induced by the treatment of rats with D-Trp-6-LH-RH.
Subject(s)
Gonadotropin-Releasing Hormone/analogs & derivatives , Luteolytic Agents/pharmacology , Prostatic Neoplasms/metabolism , Receptors, Androgen/metabolism , Receptors, Steroid/metabolism , Animals , Cell Nucleus/metabolism , Electrophoresis, Polyacrylamide Gel , Gonadotropin-Releasing Hormone/pharmacology , Male , Peptide Hydrolases/metabolism , Prostatic Neoplasms/drug therapy , Rats , Rats, Inbred F344 , Receptors, Androgen/drug effects , Spectrometry, Fluorescence , Triptorelin PamoateABSTRACT
Quantitative analyses of LH-RH-like membrane receptors were performed in five tumors from the transplantable Dunning R3372H rat prostatic adenocarcinoma. The binding of D-Trp6-LH-RH, an agonist of LH-RH, was observed in all 5 tumors. The antagonist [Ac-Dp-Cl-Phe1,2,D-Trp3,D-Lys6, D-Ala10]-LH-RH was bound to 4 tumors. The apparent equilibrium dissociation constant (Kd) for D-Trp6-LH-RH receptor was from 2.6-3.9 x 10(-10) M. The apparent equilibrium Bmax values (maximum number of binding sites) were from 17.2-86.0 fmol/mg membrane protein for D-Trp6-LH-RH receptor. The Kd for the antagonist was from 2.4-2.7 x 10(-10) M and the Bmax values were from 35.5-66.0 fmol/mg membrane protein. Similar binding studies performed in 6 normal rat prostates showed no binding capacities.
Subject(s)
Prostatic Neoplasms/metabolism , Receptors, Cell Surface/isolation & purification , Animals , Male , Membrane Proteins/metabolism , Neoplasm Proteins/metabolism , Neoplasms, Experimental/metabolism , Protein Binding , Rats , Receptors, LHRHABSTRACT
The effect of administration of D-Trp6-Luteinizing Hormone-Releasing Hormone (LH-RH) on synthesis and degradation of cyclic nucleotides was studied in the rat. There were no significant changes in the rate of synthesis and degradation of cyclic AMP in the ovary, testis and pituitary gland of D-Trp6-LH-RH-treated rats as compared to controls. On the other hand, the levels of cyclic GMP and activity of guanylate cyclase were significantly higher in the ovary and testis as well as in the pituitary gland of animals which received the analog. The rate of hydrolysis of cyclic GMP was unchanged by the administration of D-Trp6-LH-RH. Interestingly, the cyclic CMP phosphodiesterase seemed to be activated in animals treated with D-Trp6-LH-RH.
