Knockout of filamin A in KGN granulosa tumor cells impairs proliferation, cell cycle progression, migration, and cytoskeletal organization under mechanical stress.

backgroundFilamin A (FLNA) is an actin-binding protein that regulates mechanosensitivity and functions as an intracellular signaling scaffold in various cell types. It has also been implicated in tumor growth. We recently reported FLNA expression in human ovarian granulosa cells and in KGN cells, a granulosa cell tumor (GCT) line.

resultsImmunohistochemistry analysis of 51 GCT samples revealed heterogeneous FLNA expression, with approximately 20% showing weak, 18% strong, and the majority moderate expression. We therefore conducted functional studies in KGN cells using CRISPR/Cas9 gene editing. A proteomic approach revealed marked changes in protein abundance upon FLNA depletion: proteins with increased abundance were predominantly related to adhesion, cytoskeletal organization, regulation of cell shape, and lipid metabolic process, whereas those with decreased abundance were associated with DNA replication, cell division, and cell cycle regulation. FLNA-knockout cells showed enlarged cell sizes, reduced proliferation, and slightly affected steroidogenesis. Disruption of FLNA further reduced migration velocity, altered actin cytoskeletal alignment under flow, and modified expression of genes involved in cytoskeletal architecture, adhesion, and mechanosensing under shear stress.

conclusionsOur results identify crucial roles of FLNA in shaping the cellular architecture, motility, and proliferation of KGN cells. Consequently, alterations in FLNA expression may influence intracellular signaling, and responsiveness to mechanical cues in both physiological and pathological contexts.