Participation of inhibitory GPCR in normal pituitary cell proliferation induced by FGF2

DE PAUL AL; SOSA L DEL V.; PETITI J P; PICECH, F; TORRES, A I

Mar del Plata

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2019

The growth factors effects may beregulated by the inhibitory G protein-coupled receptors (GPCRGai)activation, thus modifying the metabolic activity of pituitarygland. Considering that intracellular communications areessential; the aim was to evaluate whether GPCR-Gai regulatesthe basic fibroblast growth factor (FGF2) proliferative activity innormal pituitary cell populations. Anterior pituitary cell culturesfrom female rats were treated with FGF2 (10 ng/mL) orsomatostatin analogue (OCT, 100 mM) alone or co-incubatedwith or without an inhibitor of GPCR-Gai, pertussis toxin (PTX,500 nM) or MEK inhibitor (U0126, 100 μM). Cell proliferation wasanalyzed by double-immunocytochemistry of BrdU and lactotroph(PRL) or somatotroph (GH); cell cycle by flow cytometry and celldeath by TUNEL at 24 h. The somatostatin receptors, SSR2 and 5were determined by WB and IF; and the ERK1/2, JNK, P38, AKT,S6, c-Jun and cell cycle regulators: cyclin D1, E1, CDK4, p21 andp27 by WB. Statistics: ANOVA-Bonferroni. The SSR2 and 5 wereexpressed in PRL and GH cells. The lactotroph and somatotrophcell proliferation was increased by FGF2 whereas OCT decreasedthe cell mitosis respect to control group. The FGF2/OCT coincubationsignificantly decreased the proliferation in both celltypes associated with a decrease of p-ERK, p-AKT, p-S6, c-Junand an increase of JNK, effect that was reverted by PTX or U0126pre-incubation. The TUNEL positive cells and p-P38 expressiondid not exhibited changes. In addition, the FGF2/OCT coincubationsignificantly increased the G1-phase arrest, effectrelated to an increase in the cell cycle inhibitors p27 and p21expression and a decrease of cyclin D1 while cyclin E1 and CDK4did not show any significant variation. These results show thatFGF2/OCT treatment induced a decreased of PRL and GH cellspopulation associated with G1-phase arrest, modulating theproteins expression involved in the regulation of cell proliferationand cell cycle progression.