Anti-VEGF Therapy Induces Proteinuria through Endothelial Disorganization Leading to Nephrin Decrease in Podocytes

Background: VEGF is involved in cancer development by stimulating neo-angiogenesis and tumor proliferation. Anti-angiogenic therapies, especially tyrosine kinase inhibitors such as sunitinib, have significantly improved cancer prognosis. Nevertheless, renal side effects, such as proteinuria and thrombotic microangiopathy, have been reported. The underlying physiopathological mechanisms remain unclear, but animal models and clinical similarities with preeclampsia suggest that such therapies affect the function of the endothelial and    pithelial layers of the glomerular basement membrane, with activation of the endothelin  ignaling system and loss of glomerular slit diaphragm integrity.The aim of this in vitro study  as to determine sunitinib effects on normal podocytes and glomerular endothelial cells.Methods: The glomerular microvascular endothelial (GMVEC) and human glomerular  isceral epithelial (hGVE) cell lines were incubated with various doses of sunitinib. The MTT Cell Proliferation Assay was used to assess cell proliferation. Expression of nephrin (a major slit diaphragm protein) and endothelin was evaluated by immunofluorescence or western blotting assays.Results: Sunitinib inhibited GMVEC and hGVE cell proliferation in a dose-dependent manner. In GMVEC cells, endothelin transcription and secretion were increased after incubation with sunitinib. Conversely, in hGVE cells, sunitinib did not affect nephrin expression. However, conditioned medium from GMVEC cells incubated with sunitinib modified nephrin expression when added to the culture medium of hVGE cells. This effect was inhibited by pre-incubating hGVE cells with an endothelin inhibitor.Conclusion: This study suggests an indirect toxicity of sunitinib on podocytes through endothelin. Therefore, sunitinib-induced renal side effects could be controlled with endothelin inhibitors.