Leptin-induced transphosphorylation of vascular endothelial growth factor receptor increases Notch and stimulates endothelial cell angiogenic transformation

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• 作者：Viola Lanier^a ; Corey Gillespie^b ; Merle Leffers^c ; Danielle Daley-Brown^a ; Joy Milner^a ; Crystal Lipsey^a ; Nia Webb^a ; Leonard M. Anderson^a ; ^d ; Gale Newman^a ; Johannes Waltenberger^c ; Ruben Rene Gonzalez-Perez^a ; ^{rgonzalez@msm.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Leptin ; VEGFR ; Notch ; Endothelial cells ; Angiogenesis ; Tumor angiogenesis
• 刊名：International Journal of Biochemistry and Cell Biology
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：79
• 期：Complete
• 页码：139-150
• 全文大小：3749 K

文摘

Leptin increases vascular endothelial growth factor (VEGF), VEGF receptor-2 (VEGFR-2), and Notch expression in cancer cells, and transphosphorylates VEGFR-2 in endothelial cells. However, the mechanisms involved in leptin’s actions in endothelial cells are not completely known. Here we investigated whether a leptin-VEGFR-Notch axis is involved in these leptin’s actions. To this end, human umbilical vein and porcine aortic endothelial cells (wild type and genetically modified to overexpress VEGFR-1 or -2) were cultured in the absence of VEGF and treated with leptin and inhibitors of Notch (gamma-secretase inhibitors: DAPT and S2188, and silencing RNA), VEGFR (kinase inhibitor: SU5416, and silencing RNA) and leptin receptor, OB-R (pegylated leptin peptide receptor antagonist 2: PEG-LPrA2). Interestingly, in the absence of VEGF, leptin induced the expression of several components of Notch signaling pathway in endothelial cells. Inhibition of VEGFR and Notch signaling significantly decreased leptin-induced S-phase progression, proliferation, and tube formation in endothelial cells. Moreover, leptin/OB-R induced transphosphorylation of VEGFR-1 and VEGFR-2 was essential for leptin’s effects. These results unveil for the first time a novel mechanism by which leptin could induce angiogenic features via upregulation/trans-activation of VEGFR and downstream expression/activation of Notch in endothelial cells. Thus, high levels of leptin found in overweight and obese patients might lead to increased angiogenesis by activating VEGFR-Notch signaling crosstalk in endothelial cells. These observations might be highly relevant for obese patients with cancer, where leptin/VEGFR/Notch crosstalk could play an important role in cancer growth, and could be a new target for the control of tumor angiogenesis.