Factor VIII, a coagulation cofactor, is a relevant survival factor in bladder cancer cell lines

Background Factor (F)VIII, an essential coagulation cofactor and independent cancer-associated thrombotic risk factor, has recently been shown to be synthesized directly by a broad profile of cancers. With evident extracoagulative functions, it remains to be understood if FVIII can play a functional role in cancer. Objectives Establish if FVIII plays a direct role in bladder cancer cell models. Methods Bladder cancer cell lines 5637 and ECV-304 were treated with recombinant human FVIII (rFVIII) B-domain-deleted or full-length rFVIII (rFVIII-FL) in low serum conditions, where cell cycle, migration, and cell survival were assessed. Cell cycle was measured by 7-aminoactinomycin D incorporation and migration by Transwell or wound healing assays. Cell survival was assessed by crystal violet (optical density 592) and 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (optical density 570) assays. Cell adhesion was determined with integrin β₁ and α_V protein levels, annexin-V-FITC/7-aminoactinomycin D staining, and Bcl2 with procaspase3 levels for apoptosis. Cancer cell-derived effects were assessed by silencing FVIII using short hairpin RNA. Results In both bladder cancer cell lines, cell cycle progression was pushed, and migration was advanced by rFVIII. More dramatic were the survival effects for rFVIII-FL, confirmed in a cell line of diverse origin, the osteosarcoma U2OS, through the maintenance of cell adhesion and inhibition of apoptosis. Further, silencing cell-derived FVIII retarded both cell cycle progression and migration. More importantly, cell survival was dramatically reduced and could be blocked by the administration of rFVIII-FL. Conclusion Overall, this investigation highlights FVIII as a relevant survival factor in bladder cancer cells and provides evidence of its role in cancer.