016 Signal Transduction Pathways and Cytokines Involved in Restoration of Hair Growth with Topical Anthralin in Alopecia Areata Rats

Liren Tang, Liping Cao, Steven Pelech, Harevey Lui, David I. McLean and Jerry Shapiro; Department of Medicine, University of British Columbia and Vancouver General Hospital, Vancouver, Canada

We have shown that anthralin is very effective on hair restoration in the Dundee experimental bald rats (DEBR). All 15 rats showed near complete hair regrowth on the treated sides, while the control sides remained balding. The aim of the present study was to investigate the underlying molecular mechanisms of the therapeutic effects of anthralin on AA-affected rats. Skin biopsies were collected from both treated and control sides. RNA and proteins were extracted. Proteins were used for KinetworkTM analytical screens for cell signaling proteins (Kinexus, Canada) to determine the expression of various protein kinases, phosphatases, and their down stream trascriptional regulators which might be responsible for the signal transduction pathways mediated by anthralin in rat skins. RNA protection assay was performed to determine the gene expression of various cytokines mediated by anthralin. Among the cytokines we have tested by RNA protection assay (RPA), interleukin 1b (IL-1â), IL-1á, IL-10 and IL-1 receptor antagonist (IL-1Ra) showed remarkable induction after anthralin treatment, while tumor necrosis factor á (TNF-á) and interferon ã (INF-ã) were decreased upon successful treatment with anthralin. Protein kinase screening revealed that growth factor mediated signal transduction involving Erk1 & 2, their upstream regulators (Raf, Mek 1 & 2) and downstream kinases (p70S6K and p90S6K), are all activated. The stress-activated pathways involving SAPK 1 & 2 and their upstream regulatory kinases (Mek 4 & 7) were also induced by anthralin, presumably owing to the free radicals generated by anthralin on the skin. In addition, another pathway mediated by PKB and GSK-3 kinases were also activated. Cytokine-mediated signals transduction pathways through Jak kinases were only weakly detected. But the downstream STAT-3 showed dramatic increase in its phosphorylation. We conclude that the molecular mechanism underlying the efficacy of anthralin on hair regrowth in AA rats might be mediated by the interplay of cytokines produced locally in the skin. The signal transduction pathways involving various protein kinases and their regulators may represent the initial molecular events in rat skin upon successful anthralin treatment. This line of information will help our understanding of the molecular mechanisms of anthralin’s efficacy on AA rats.