UV radiation resistance-associated gene (UVRAG) promotes cell proliferation, migration, invasion by regulating cyclin-dependent kinases (CDK) and integrin-ß/Src signaling in breast cancer cells.

Breast cancer is a highly heterogeneous group of human cancer with distinct genetic, biological and clinicopathological features. Triple-negative breast cancer (TNBC) is the most aggressive and metastatic type of breast cancer and associated with poor patient survival. However, the role of UV Radiation Resistance-Associated Gene (UVRAG) in TNBC remains unknown. Here, we report that UVRAG is highly upregulated in all TNBC cells and its knockdown leads to the inhibition of cell proliferation, colony formation and progression of cell cycle, which is associated with and reduced expression of cell cycle related protein expression, including Cyclin A2, B1, D1, cdc2 and cdk6 in TNBC cells. Inhibition of UVRAG also suppressed cell motility, migration and invasion of TNBC cells by inhibition of Integrin ß1 and ß3 and Src activity. Our findings suggest for the first time that UVRAG expression contributes to proliferation, cell cycle progression, motility/migration and invasion of TNBC cells. Thus, targeting UVRAG could be a potential strategy in breast cancer especially against TNBC.

Toxic-dose warfarin-induced apoptosis and its enhancement by gamma ionizing radiation in leukemia K562 and HL-60 cells is not mediated by induction of oxidative stress.

The purpose of this study was to test the hypothesis that warfarin may enhance free radical production and oxidative damage on cancer cells. We examined the possible concentration-dependent effect of warfarin on cytotoxicity with respect to oxidative stress on leukemia cell lines (K562 and HL-60) and normal human peripheral blood mononuclear cells (PBMC). Gamma radiation was used as a positive control agent for oxidative stress. At all concentrations of warfarin (5-200 muM), 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)- and bis-N-methylacridinium nitrate (lucigenin)-amplified chemiluminescence responses and lipid peroxidation and protein oxidation were stable after 72 h incubation at 37 degrees C. However, The 2',7'-dichlorofluorescein diacetate (DCFH-DA) oxidation was increased when cells were incubated with high concentrations (50-200 muM) of warfarin. In these concentration ranges, warfarin reduced cell growth in a dose-dependent manner, producing apoptosis. Our results also revealed that at concentrations above 5 muM, warfarin had a potentiating effect on radiation-mediated growth inhibition and apoptosis. Furthermore, marked effects were observed on leukemic cells compared with PBMC. We report here that the increase of DCFH oxidation might be due to the increase in the release of cytochrome C caused by warfarin, as cytosolic cytochrome C content was significantly elevated in the warfarin-treated cells compared with control cells, and because cotreatment with antioxidants N- acetylcysteine or 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron) was unable to prevent cytochrome C release and DCFH oxidation induced by the drug. Taken together, these results suggest that high warfarin concentrations may be toxic to leukemic cells in vitro through apoptosis, although at the pharmacological concentrations (<50 muM), warfarin has no prooxidant or cytotoxic effect on PBMC, K562, and HL-60 cells. In addition, when the treatment of leukemic cells with warfarin at concentrations above 5 muM is combined with radiation, we observed an increase in radiation-induced cytotoxicity. The mechanism by which warfarin potentiates this cytotoxicity is unclear, but it may not be directly due to toxic damage induced by warfarin-generated free radicals.