CONICET | Buscador de Institutos y Recursos Humanos

Panc-1 cells overexpress H1 and H2 histamine receptors (H1R, H2R). Histamine (HA) in concentrations higher than 1 µM activates the adenylate cyclase signaling pathway via H2R and inhibits cell proliferation. It has been reported that nitric oxide (NO) exerts antiproliferative action in different tumoral cell lines. Moreover, HA induces the nitric oxide synthase (NOS) expression and increases NO production in endothelial cells. The aim of this work was to study HA-induced NOS modulation and its possible involvement in PANC-1 cell growth. Cell proliferation was evaluated by the clonogenic method. A dose-dependent inhibition on cell growth was observed when cell cultures were treated with NOS inhibitors (L-NAME, EC50: 1.5 ± 0.5 nM; Aminoguanidine, EC50: 250 ± 30 µM) and the NO donnor (SIN-1, EC50: 10 ± 3 µM). Endothelial and inducible NOS (eNOS and iNOS) isoforms expression was determined by RT-PCR. Data indicated that PANC-1 cells express constitutive eNOS and that it is positively modulated at 24 h by 10 µM HA, 10 µM Forskolin (Fk, adenylate cyclase direct activator) and 4 mM L-NAME. Conversely, a decrease in eNOS mRNA levels was observed when cells were treated with 20 µM SIN-1. iNOS mRNA expression was undetectable when tested at the previous mentioned experimental conditions. A significant augmentation of intracellular NO level was demonstrated by flow cytometric analyses employing the fluorescent dye DAF-2DA after cell cultures were exposed to HA (140 ± 13%), Fk (162 ± 18%) or L-NAME (153 ± 15 %). In conclusion, NO levels modulate eNOS expression and cell growth in PANC-1 cells. Results also indicate that the inhibitory effect exerted by HA on cell proliferation may be mediated by HA-produced NO levels. POSTER

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