Ultraviolet B Light Induces Rapid Changes in Gene Expression as Detected by Non-Invasive, Adhesive Skin Biopsies

The purpose of this study is to determine changes in skin gene expression following exposure to ultraviolet (UV) B radiation. Non-invasive, adhesive patch skin biopsies (DermTech, Inc., La Jolla, CA) were performed on the right and left post-auricular areas of 24 subjects before and 24-hours after UV-B exposure using an excimer laser dosed at 300mJ to mimic UV damage. RNA was isolated from the samples and assessed by reverse transcriptase followed by quantitative polymerase chain reaction to assess the expression of genes believed to play a role in skin cancer development. Of 18 assessed genes, 8 showed significantly changed gene expression (p\u3c0.05) after 24 hours of UV-exposure compared to baseline. These 8 genes are among those involved in the cellular retinoic acid (Vitamin A) binding, cellular inflammation (members of interleukin family) and cell death, as well as genes from several cellular protease families, such as mucinlike protein family, cystatin superfamily, serine proteases family and genes encoding the crosslinked envelope proteins of keratinocytes. Through this study, we also identified one gene that did not demonstrate significant change in gene expression after 24 hours of UV exposure, but showed significant change (p\u3c0.05) at 2 weeks following UV exposure, suggesting this gene may be a slow responder to UV irradiation. These results suggest that UV exposure does cause rapid gene expression changes in exposed skin and that these changes can be readily identified non-invasively and without the need for surgical biopsies. The identified target genes can be used as cellular markers for sun damage that may play a role in skin cancer development and may help assess the efficacy of topical agents, such as chemopreventive agents and topical DNA repair enzymes, in reversing UV damage