Vitamin D protects endothelial cells from irradiation-induced senescence and apoptosis by modulating MAPK/SirT1 axis.
Radiotherapy toxicity is related to oxidative stress-mediated endothelial dysfunction. Here, we investigated on radioprotective properties of Vitamin D (Vit.D) on human endothelial cells (HUVEC).



HUVEC, pre-treated with Vit.D, were exposed to ionizing radiation (IR): ROS production, cellular viability, apoptosis, senescence and western blot for protein detection were performed. The role of MAPKs pathway was investigated by using U0126 (10 μM) MEKs/ERKs-, SB203580 (2.5 μM) p38-inhibitor or by over/expressing MKK6 p38-upstream activator.



Vit.D reduced IR-induced ROS production protecting proliferating and quiescent HUVEC from cellular apoptosis or senescence, respectively, by regulating MAPKs pathways. In proliferating HUVEC, Vit.D prevented IR-induced apoptosis by activating ERKs while in quiescent HUVEC counteracted IR-induced senescence by inhibiting the p38-IR-induced activation. MEKs&ERKs inhibition in proliferating or MKK6/mediated p38 activation in quiescent HUVEC, respectively, reverted anti-apoptotic or anti-senescent Vit.D properties. SirT1 protein expression levels were up-regulated by Vit.D. ERKs inhibition blocked Vit.D-induced SirT1 protein up-regulation in proliferating cells. In quiescent HUVEC cells, p38 inhibition counteracted the IR-induced SirT1 protein down-regulation, while MKK6 transfection abrogated the Vit.D positive effects on SirT1 protein levels after irradiation. SirT1 inhibition by sirtinol blocked the Vit.D radioprotective effects.



Vit.D protects HUVEC from IR induced/oxidative stress by positively regulating the MAPKs/SirT1 axis.
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
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Marampon
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy. giovanniluca.gravina@libero.it.
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Gravina
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
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Festuccia
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA.
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Popov
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
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Colapietro
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
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Sanità
Department of Radiotherapy, Policlinico Umberto I "Sapienza" University of Rome, Rome, Italy.
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Musio
Department of Radiotherapy, Policlinico Umberto I "Sapienza" University of Rome, Rome, Italy.
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De Felice
Department Experimental Medicine, "Sapienza" University of Rome, Rome, Italy.
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Lenzi
Department of System Medicine, University of Tor Vergata, 00133, Rome, Italy.
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Jannini
Division of Radiotherapy and Radiobiology, Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
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Di Cesare
Department of Radiotherapy, Policlinico Umberto I "Sapienza" University of Rome, Rome, Italy.
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Tombolini
D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects* / Q000528:radiation effects; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects* / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D056564:Sirtuin 1 / Q000378:metabolism*; D014807:Vitamin D / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
D017382:Reactive Oxygen Species; D014815:Vitamins; D014807:Vitamin D; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; C447939:SIRT1 protein, human; D056564:Sirtuin 1
Endothelium; Oxidative stress; Radiotherapy; SirT1; Vitamin D