title: Increased expression of p53 and p21 (Waf1/Cip1) in the lesional skin of bleomycin-induced scleroderma.
abstract: Systemic sclerosis (SSc) is a connective tissue disorder characterized by excessive deposition of extracellular matrix in the affected skin as well as various internal organs, vascular injury and immune abnormality; however, the etiology of SSc remains still unknown. We previously established an experimental mouse model for scleroderma by repeated local injections of bleomycin, a DNA damaging agent. In this study, we examined the induction of apoptosis and the expression of p53, p21 (Waf1/Cip1), and proliferating cell nuclear antigen (PCNA) in the lesional skin following bleomycin exposure in this model. Dermal sclerosis was induced by alternate day's injections of bleomycin for 4 weeks. TUNEL assay showed that apoptotic cells began to appear at 1 week after bleomycin exposure, and were prominently detected at 3-4 weeks. Immunohistochemical examination showed increased expression of p53 and p21 mainly in the infiltrating mononuclear cells at 2 weeks after bleomycin treatment. Bleomycin treatment markedly enhanced PCNA expression at 1-2 weeks, mainly in mesenchyme, as compared with control phosphate buffered saline treatment. Reverse transcriptase-polymerase chain reaction analysis showed that the expression of p53 and p21 mRNA was concurrently upregulated at 1-2 weeks after bleomycin treatment. Taken together, coordinate increased levels of p53 and p21 preceded the maximal induction of apoptosis and dermal sclerosis. Our findings suggest that apoptotic processes are involved in the pathophysiology of bleomycin-induced scleroderma, which may be mediated, in part, by the upregulation of p53 and p21.
authors.affiliation: Department of Dermatology, Tokyo Medical and Dental University, School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. yamamoto.derm@med.tmd.ac.jp
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nishioka
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic; D001761:Bleomycin; D018797:Cell Cycle Proteins / Q000235:genetics*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012595:Scleroderma, Systemic / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D012879:Skin Physiological Phenomena; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D000903:Antibiotics, Antineoplastic; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016159:Tumor Suppressor Protein p53; D001761:Bleomycin