Investigation of filamin protein functions in cells

Objective: Filamins are large actin-binding proteins that stabilize three-dimensional actin filament networks and link them to cellular membranes where they integrate cell architectural and signaling functions important for cell locomotion. Filamin A (FLNA) is the most abundant and widely expressed isoform in human tissues. Endogenous 90 kDa Carboxyl-terminal (CT) (FLNACT) is produced by cleavage in hinge 1 (H1) and hinge 2 (H2) sites by calpain. Carboxyl-terminal (CT) fragment of the cytoskeletal protein FLNA transports to the cell nucleus and stimulates cell transcription. Calpeptin is a calpain 1 and 2 inhibitor, which is responsible for FLNA cleavage. Identification of FLNACT roles in cell migration and invasion may help to develop more effective cancer therapies. Method: Human melanoma (A7), prostate cancer (PC3), mouse fibrosarcoma (T241) and endothelial (MS1) cells were assayed for proliferation, migration, invasion and colony formation after treatment with calpeptin. Results: In all cell lines, for calpeptin treated group we found less migration, invasion, proliferation and colony forming ability compared to the controls. Conclusion: The result of this study showed that calpeptin reduces FLNACT production by calpain cleavage in multiple cancer cells that express FLNA. On the other hand, cells with reduced FLNACT production showed significantly (p<0.05) less migration, invasion, proliferation and colony forming ability. These data suggest that FLNACT is one of the important regulators in cell proliferation, migration, invasion and colony forming. This experimental study was carried out through 2014-2017 in Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg. Key Words: Filamin, Filamin A, Calpain, Calpeptin, Prolifaration, Migration, İnvasion, Colony Forming, Cancer.