Abstract
Itraconazole is a safe and widely used antifungal drug that was recently found to possess potent antiangiogenic activity. Currently, there are four active clinical trials evaluating itraconazole as a cancer therapeutic. Tumor growth is dependent on angiogenesis, which is driven by the secretion of growth factors from the tumor itself. We report here that itraconazole significantly inhibited the binding of vascular endothelial growth factor (VEGF) to VEGF receptor 2 (VEGFR2) and that both VEGFR2 and an immediate downstream substrate, phospholipase C γ1, failed to become activated after VEGF stimulation. These effects were due to a defect in VEGFR2 trafficking, leading to a decrease in cell surface expression, and were associated with the accumulation of immature N-glycans on VEGFR2. Small molecule inducers of lysosomal cholesterol accumulation and mammalian target of rapamycin (mTOR) inhibition, two previously reported itraconazole activities, failed to recapitulate itraconazole's effects on VEGFR2 glycosylation and signaling. Likewise, glycosylation inhibitors did not alter cholesterol trafficking or inhibit mTOR. Repletion of cellular cholesterol levels, which was known to rescue the effects of itraconazole on mTOR and cholesterol trafficking, was also able to restore VEGFR2 glycosylation and signaling. This suggests that the new effects of itraconazole occur in parallel to those previously reported but are downstream of a common target. We also demonstrated that itraconazole globally reduced poly-N-acetyllactosamine and tetra-antennary complex N-glycans in endothelial cells and induced hypoglycosylation of the epidermal growth factor receptor in a renal cell carcinoma line, suggesting that itraconazole's effects extend beyond VEGFR2.
Highlights
Itraconazole is a widely used antifungal drug that was recently found to possess potent antiangiogenic activity
We report here that itraconazole significantly inhibited the binding of vascular endothelial growth factor (VEGF) to VEGF receptor 2 (VEGFR2) and that both VEGFR2 and an immediate downstream substrate, phospholipase C ␥1, failed to become activated after VEGF stimulation
We observed that in human umbilical vein endothelial cells (HUVEC) treated with itraconazole, the migration pattern of VEGFR2 was altered such that only the lower molecular weight species was present (Fig. 1A)
Summary
Itraconazole is a widely used antifungal drug that was recently found to possess potent antiangiogenic activity. Itraconazole’s long history of safe use in humans as an antifungal agent and its relatively high plasma concentrations have spurred its advance as a viable candidate for repurposing as an antiangiogenic drug It is currently undergoing four clinical trials as an anticancer therapeutic (NCT00769600, NCT00887458, NCT00798135, and NCT01108094) and has recently been shown to have efficacy in preclinical models for non-small cell lung cancer [2]. Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody and the first to be approved, only marginally extends survival and carries significant risk of adverse events [4,5,6,7] For this reason, itraconazole and other drug candidates are being actively pursued as new and potentially more safe and more effective antiangiogenic leads. Itraconazole, like other members of the azole antifungal class, inhibits the fungal enzyme lanosterol 14-␣-demethylase (14DM), which generates a key intermediate in ergosterol syn-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
