CONICET | Buscador de Institutos y Recursos Humanos

Filamin A (FLNA) is an acting binding protein that is deregulated in pituitary tumours and plays a role in lamellipodia formation. Cyclin D1 (CD1) is increased in tumours, but is not always correlat-ed with cell cycle progression. FLNA and CD1 localized on cellular protrusions and physically interact to regulate cell motility. We hypothesized that FLNA promotes CD1 expression with non-canonical functions in pituitary cells. The objective was to analyse the effect of FLNA over CD1 expression and function on lactotroph cells.Transfected GH3 cells for FLNA overexpression (GH3F+) and pituitary glands from female rats treated with estradiol benzoate for 20, 40 and 60 days, as pituitary hyperplastic adenomatous model, were used. FLNA and CD1 expression was analysed by Western blot and subcellular localization by immunocytochemistry (ICC). Cell cycle progression was analysed by flow cytometry, Ki67 index by ICC, colony formation capacity by clonogenic assay, and cellular morphology was performed by optical microscopy. The statistical analysis used was ANOVA-Tukey.GH3 FLNA overexpression induced CD1 increase with low proliferation rate detected by Ki67 index and clonogenic assay, suggesting that is not exerting canonical functions. Also, the GH3F+ Morphological analysis showed a significant increase in cells with lamellipodia, doubling the pleomorphic cell number, which showed diffuse cytoplasmic CD1 distribution, suggesting an Involvement of cytoplasmiC CD1 in cell motility.FLNA increased gradually until the 40 days of pituitary hyperplastic glands and declined at 60 days, similar to cyclin D1 expression pattern. Cell cycle analysis revealed a proliferation phase S/G2-Mdeclined at 40 days, suggesting that CD1 expression does not correlate with cell cycle progression.Our results suggest that FLNA enhanced CD1 expression, without affecting cell cycle progression, leading to non-canonical functions, possibly related to cell protrusion formation.

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