Filamin A modulates cell growth and EGFR/ERK signalling in pituitary tumoral cells

JONATHAN TOLEDO; PABLO A. PÉREZ; ANA L. DE PAUL; SILVINA GUTIÉRREZ

Congreso; Reunión Anual de las Sociedades de Biociencia, Sociedad Argentina de Investigación Clínica (SAIC); 2022

SAIC

Filamin A (FLNA) interacts withsignaling molecules and membrane receptors to affect cell signal transductionand function. Epidermal Growth Factor Receptor (EGFR) is a major player modulatingcell proliferation and hormone secretion in pituitary tumors, however, whetherFLNA regulates EGFR expression affecting pituitary tumoral growth remains to beelucidated. The aim of this study was to evaluate the impact of FLNA onproliferation, viability and hormone secretion in tumoral pituitary cells andestablish if these alterations are mediated by EGFR signaling. LactosomatotrophicGH3 cells were transfected for FLNA overexpression (GH3F+) and stimulated for 5,10, 30 min and 24h with EGF (10 ng/ml). Protein expression was analyzed by westernblot and immunocitochemistry (ICC) and quantified by flow cytometry, protein subcellularlocalization was observed by indirect immunofluorescence (IFI), cell cycleprogression was determined by cellular DNA content with flow cytometry and cellviability was analyzed by number of colonies formed in a clonogenic assay. Thestatistical analysis used was ANOVA-Tukey. FLNA overexpression induced asignificant decreased of Ki67-labelled cells, reduced S/G2-M cell percentage,decreased cell viability, and inhibited the PRL secretion. In order to elucidatethe mechanism through FLNA overexpression impacts on these parameters, weevaluate membrane EGFR expression and EGF-induced signaling pathway activation.Plasmatic membrane EGFR was significantly reduced under FLNA overexpression in GH3cells, with further decrease with EGF stimulation. Also, a consequent declined inERK1/2 phosphorilation in response to EGF was observed in GH3F+ vs. GH3. Theresults showed that FLNA overexpression decreased lactosomatotroph cell growthand membrane EGFR localization and activity, suggesting that FLNA may inhibitEGF‑induced cell proliferation in pituitary tumor cells.