title: Nicotinamide prevents ultraviolet radiation-induced cellular energy loss.
abstract: UV radiation is carcinogenic by causing mutations in the skin and also by suppressing cutaneous antitumor immunity. We previously found nicotinamide (vitamin B3) to be highly effective at reducing UV-induced immunosuppression in human volunteers, with microarray studies on in vivo irradiated human skin suggesting that nicotinamide normalizes subsets of apoptosis, immune function and energy metabolism-related genes that are downregulated by UV exposure. Using human adult low calcium temperature keratinocytes, we further investigated nicotinamide's effects on cellular energy metabolism. We found that nicotinamide prevented UV-induced cellular ATP loss and protected against UV-induced glycolytic blockade. To determine whether nicotinamide alters the effects of UV-induced oxidative stress posttranslationally, we also measured UV-induced reactive oxygen species (ROS). Nicotinamide had no effect on ROS formation, and at the low UV doses used in these studies, equivalent to ambient daily sun exposure, there was no evidence of apoptosis. Hence, nicotinamide appears to exert its UV protective effects on the skin via its role in cellular energy pathways.
authors.affiliation: Discipline of Dermatology, Bosch Institute, Sydney Cancer Centre at Royal Prince Alfred Hospital, University of Sydney, Camperdown, New South Wales, Australia.
authors.forename: Joohong
authors.initials: J
authors.lastname: Park
authors.forename: Gary M
authors.initials: GM
authors.lastname: Halliday
authors.forename: Devita
authors.initials: D
authors.lastname: Surjana
authors.forename: Diona L
authors.initials: DL
authors.lastname: Damian
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000528:radiation effects; D009536:Niacinamide / Q000494:pharmacology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D017382:Reactive Oxygen Species; D009536:Niacinamide; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases