title: Up-regulation of p21WAF1/CIP1 in psoriasis and after the application of irritants and tape stripping.
abstract: p21WAF1/CIP1 is a nucleoprotein that was initially characterized by its ability to be regulated transcriptionally by p53 and by its ability to mediate growth arrest by binding to cyclin-dependent kinases. Although p21WAF1/CIP1 is thought to mediate the effects of p53 in causing growth arrest, p21WAF1/CIP1 is also regulated in a p53-independent manner, e.g., during terminal differentiation of some cell lines. Growth factors including epidermal growth factor also induce p21WAF1/CIP1 through p53-independent pathways. Because the epidermal growth factor signaling pathway is abnormal in psoriatic epidermis, we studied p21WAF1/CIP1 expression, using in situ hybridization and immunohistochemistry, in psoriasis. Both p21WAF1/CIP1 mRNA and protein were significantly elevated in untreated psoriatic plaques compared with uninvolved psoriatic skin (p < 0.0001), with the up-regulation of p21WAF1/CIP1 being predominantly suprabasal. This increase was accompanied by a small increase in p53 protein expression of uncertain significance. Furthermore, p21WAF1/CIP1 expression was induced in skin after sellotape stripping and by the application of agents, such as dithranol, that are capable of inducing hyperproliferation. The pattern of p21WAF1/CIP1 expression observed is consistent with a role in induction and maintenance of differentiation. Our experiments, however, cannot determine whether the abnormalities of p21WAF1/CIP1 epidermal expression in psoriasis and after insult are independent of changes in p53 expression.
authors.affiliation: Department of Dermatology, University of Newcastle upon Tyne, United Kingdom.
authors.forename: E
authors.initials: E
authors.lastname: Healy
authors.forename: N J
authors.initials: NJ
authors.lastname: Reynolds
authors.forename: M D
authors.initials: MD
authors.lastname: Smith
authors.forename: D
authors.initials: D
authors.lastname: Harrison
authors.forename: E
authors.initials: E
authors.lastname: Doherty
authors.forename: C
authors.initials: C
authors.lastname: Campbell
authors.forename: J L
authors.initials: JL
authors.lastname: Rees
mesh_terms: D000875:Anthralin / Q000494:pharmacology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007509:Irritants / Q000494:pharmacology*; D010812:Physical Stimulation; D011565:Psoriasis / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007509:Irritants; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D012967:Sodium Dodecyl Sulfate; D000875:Anthralin