title: Inhibitory effects of sodium salicylate and acetylsalicylic acid on UVB-induced mouse skin carcinogenesis.
abstract: We conducted an in vivo carcinogenesis experiment to determine the efficacy of topical aspirin and sodium salicylate (NAS) in preventing UVB-induced nonmelanoma skin cancer. Hairless SKH-1 mice were randomly divided into eight treatment groups. They were treated topically with either 40 or 10 micromol aspirin or NAS three times weekly before 9 kJ/m(2) UVB irradiation. The experiment was carried out over 25 weeks. Both dose levels of NAS significantly inhibited (P < 0.05) the rate of tumor formation when compared with vehicle control. The 40 micromol dose of aspirin significantly inhibited the rate of tumor formation (P < 0.05), whereas the 10 micromol dose had no inhibitory effect when compared with the vehicle control. To investigate the mechanism of this inhibition, we studied UVB-induced thymine dimer formation in the epidermis of the mouse skin. We found that NAS inhibited UVB-induced thymine dimer formation (P = 0.0001), whereas aspirin did not. Therefore, we conclude that NAS prevents UVB-induced tumor growth and formation through a sunscreen effect; whereas, the moderate inhibition of aspirin may be because of a molecular event, such as the inhibition of various UVB signaling pathways.
authors.affiliation: Department of Radiation Oncology, The University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
authors.forename: Warner B
authors.initials: WB
authors.lastname: Bair
authors.forename: Nancy
authors.initials: N
authors.lastname: Hart
authors.forename: Janine
authors.initials: J
authors.lastname: Einspahr
authors.forename: Guangming
authors.initials: G
authors.lastname: Liu
authors.forename: Zigang
authors.initials: Z
authors.lastname: Dong
authors.forename: David
authors.initials: D
authors.lastname: Alberts
authors.forename: G Tim
authors.initials: GT
authors.lastname: Bowden
mesh_terms: D000287:Administration, Topical; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D001707:Biopsy, Needle; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002478:Cells, Cultured / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005260:Female; D007150:Immunohistochemistry; D051379:Mice; D008812:Mice, Hairless; D009374:Neoplasms, Experimental; D011740:Pyrimidine Dimers / Q000032:analysis*; D011897:Random Allocation; D012016:Reference Values; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D012980:Sodium Salicylate / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D016588:Anticarcinogenic Agents; D011740:Pyrimidine Dimers; D001241:Aspirin; D012980:Sodium Salicylate