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

SOSA L.; PICECH F.; DE PAUL A.L.; PETITI J. P.; TORRES A.

Mar del Plata

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

The growth factors effects may be regulated by the inhibitory G protein-coupled receptors (GPCRGai) activation, thus modifying the metabolic activity of pituitary gland. Considering that intracellular communications are essential; the aim was to evaluate whether GPCR-Gai regulates the basic fibroblast growth factor (FGF2) proliferative activity in normal pituitary cell populations. Anterior pituitary cell cultures from female rats were treated with FGF2 (10 ng/mL) or somatostatin analogue (OCT, 100 mM) alone or co-incubated with or without an inhibitor of GPCR-Gai, pertussis toxin (PTX, 500 nM) or MEK inhibitor (U0126, 100 µM). Cell proliferation was analyzed by double-immunocytochemistry of BrdU and lactotroph (PRL) or somatotroph (GH); cell cycle by flow cytometry and cell death by TUNEL at 24 h. The somatostatin receptors, SSR2 and 5 were determined by WB and IF; and the ERK1/2, JNK, P38, AKT, S6, c-Jun and cell cycle regulators: cyclin D1, E1, CDK4, p21 and p27 by WB. Statistics: ANOVA-Bonferroni. The SSR2 and 5 were expressed in PRL and GH cells. The lactotroph and somatotroph cell proliferation was increased by FGF2 whereas OCT decreased the cell mitosis respect to control group. The FGF2/OCT coincubation significantly decreased the proliferation in both cell types associated with a decrease of p-ERK, p-AKT, p-S6, c-Jun and an increase of JNK, effect that was reverted by PTX or U0126 pre-incubation. The TUNEL positive cells and p-P38 expression did not exhibited changes. In addition, the FGF2/OCT coincubation significantly increased the G1-phase arrest, effect related to an increase in the cell cycle inhibitors p27 and p21 expression and a decrease of cyclin D1 while cyclin E1 and CDK4 did not show any significant variation. These results show that FGF2/OCT treatment induced a decreased of PRL and GH cells population associated with G1-phase arrest, modulating the proteins expression involved in the regulation of cell proliferation and cell cycle progression.