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.