eNOS, nNOS, cGMP and protein kinase G mediate the inhibitory effect of pancreastatin, a chromogranin A-derived peptide, on growth and proliferation of hepatoma cells.
Pancreastatin (PST), a chromogranin A-derived peptide, has an anti-insulin metabolic effect and inhibits growth and proliferation by producing nitric oxide (NO) in HTC rat hepatoma cells. When NO production is blocked, a proliferative effect prevails due to the activation a Galphaq/11-phospholipase C-beta (PLC-beta) pathway, which leads to an increase in [Ca2+]i, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activation. The aim of the present study was to investigate the NO synthase (NOS) isoform that mediates these effects of PST on HTC hepatoma cells and the possible roles of cyclic GMP (cGMP) and cGMP-dependent protein kinase. DNA and protein synthesis in response to PST were measured as [3H]-thymidine and [3H]-leucine incorporation in the presence of various pharmacological inhibitors: N-monomethyl-L-arginine (NMLA, nonspecific NOS inhibitor), L-NIO (endothelial nitric oxide synthase (eNOS) inhibitor), espermidine (neuronal nitric oxide synthase (nNOS) inhibitor), LY83583 (guanylyl cyclase inhibitor), and KT5823 (protein kinase G inhibitor, (PKG)). L-NIO, similarly to NMLA, reverted the inhibitory effect of PST on hepatoma cell into a stimulatory effect on growth and proliferation. Nevertheless, espermidine also prevented the inhibitory effect of PST, but there was no stimulation of growth and proliferation. When guanylyl cyclase activity was blocked, there was again a reversion of the inhibitory effect into a stimulatory action, suggesting that the effect of NO was mediated by the production of cGMP. PKG inhibition prevented the inhibitory effect of PST, but there was no stimulatory effect. Therefore, the inhibitory effect of PST on growth and proliferation of hepatoma cells may be mainly mediated by eNOS activation. In turn, the effect of NO may be mediated by cGMP, whereas other pathways in addition to PKG activation seem to mediate the inhibition of DNA and protein synthesis by PST in HTC hepatoma cells.
Díaz-Troya
Sandra
S
Department of Medical Biochemistry and Molecular Biology, School of Medicine, Investigation Unit, University Hospital Virgen Macarena, Av. Sanchez Pizjuan 4, Seville 41009, Spain.
Najib
Souad
S
Sánchez-Margalet
Víctor
V
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000737:chemistry; D002118:Calcium / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D049108:Cell Enlargement; D049109:Cell Proliferation; D053379:Chromogranin A; D002864:Chromogranins / Q000502:physiology*; D006152:Cyclic GMP / Q000502:physiology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000494:pharmacology / Q000502:physiology*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D007930:Leucine / Q000737:chemistry; D008099:Liver / Q000166:cytology*; D020935:MAP Kinase Signaling System; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D009952:Ornithine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010187:Pancreatic Hormones / Q000378:metabolism* / Q000502:physiology*; D010455:Peptides / Q000737:chemistry; D054799:Phospholipase C beta; D020033:Protein Isoforms; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism; D013095:Spermidine / Q000494:pharmacology; D013936:Thymidine / Q000737:chemistry; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism; D019323:omega-N-Methylarginine / Q000494:pharmacology
D000634:Aminoquinolines; D002227:Carbazoles; D053379:Chromogranin A; D002864:Chromogranins; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D010187:Pancreatic Hormones; D010455:Peptides; D020033:Protein Isoforms; C506153:chromogranin A, rat; C050836:pancreastatin; C073601:KT 5823; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; C065027:N(G)-iminoethylornithine; D004247:DNA; C041715:6-anilino-5,8-quinolinedione; D001120:Arginine; D009952:Ornithine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496316:Nos3 protein, rat; D017869:Cyclic GMP-Dependent Protein Kinases; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A; D007930:Leucine; D006152:Cyclic GMP; D002118:Calcium; D013095:Spermidine; D013936:Thymidine