Photosensitization of the sunscreen octyl p-dimethylaminobenzoate by UVA in human melanocytes but not in keratinocytes.
Sunscreens penetrate human epidermis and modify the biology of proliferating cells. This study addressed the question whether the UV response of cultured human cells is affected by direct treatment with nontoxic levels of sunscreens. Cell survival following exposure to UVC or unfiltered UBV was not altered by preincubation with 25 micrograms/mL of octyl p-dimethylaminobenzoate (o-PABA), 2-ethylhexyl p-methoxycinnamate (EHMC) or oxybenzone. However, UVA or UVB filtered to reproduce the solar UV spectrum penetrating to the basal layer of the epidermis, highly sensitized cells to killing by o-PABA but not by its hydrolysis product, 4-dimethylaminobenzoic acid. Sensitization was found in all cell types tested, except normal keratinocytes, and could be prevented by certain antioxidants particularly pyruvate and the hydroxyl radical scavenger mannitol. o-PABA and EHMC applied without UV reduced the adherence of cells. The results indicate that sunscreens may increase cell mobility and the combination of o-PABA with solar UV may selectively damage melanocytes in the skin.
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Queensland Cancer Fund Laboratories, Queensland Institute of Medical Research, Queensland, Australia.
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Parisi
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D010129:4-Aminobenzoic Acid / Q000494:pharmacology / Q000528:radiation effects*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002448:Cell Adhesion / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000528:radiation effects; D008544:Melanocytes / Q000187:drug effects / Q000528:radiation effects*; D018462:Photobiology; D017319:Photosensitizing Agents / Q000494:pharmacology; D013473:Sunscreening Agents / Q000494:pharmacology / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D062366:para-Aminobenzoates
D016166:Free Radical Scavengers; D017319:Photosensitizing Agents; D013473:Sunscreening Agents; D062366:para-Aminobenzoates; C015402:octyl dimethyl 4-aminobenzoic acid; D010129:4-Aminobenzoic Acid