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Coexpression of p21 Waf1/Cip1 and p53 in sun‐exposed normal epidermis, but not in neoplastic epidermis
Author(s) -
INOHARA S.,
KITAGAWA K.,
KITANO Y.
Publication year - 1996
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1046/j.1365-2133.1996.d01-1068.x
Subject(s) - epidermis (zoology) , cyclin dependent kinase , biology , dna damage , cell cycle , cancer research , cell cycle checkpoint , cyclin d1 , microbiology and biotechnology , cell , dna , biochemistry , anatomy
Summary Wild‐type p53 accumulation induced by DNA damaging agents such as ultraviolet (UV) radiation. γ‐irradiation and drugs, may arrest the cell cycle until DNA damage is repaired. p21 Waf1/Cip1 is a cyclin‐dependent kinase (CDK) inhibitor induced by wild‐type p53. CDK is activated by cyclin and progresses the cell cycle. On the other hand. CDK inhibitors inhibit CDK activity to arrest the cell cycle. Thus, p21 Waf1/Cip1 is thought to mediate the signal of p53 induced by DNA damaging agents to arrest the cell cycle. p21 Waf1/Cip1 is induced by wild‐type, but not mutant p53. To investigate p21 Waf1/Cip1 regulation by p53 in epidermis in vivo , immunohistochemical staining of p21 Waf1/Cip1 and p53 were conducted in chronically sun‐exposed normal epidermis and in neoplastic epidermis. p21 Waf1/Cip1 expression was found to be coincident with the p53‐positive regions or not coincident with the p53‐positive regions in chronically sun‐exposed normal epidermis, whereas there was only low or undetectable p21 Waf1/Cip1 expression in any regions including the p53‐positive regions of solar keratosis and squamous cell carcinoma of the skin. This suggests that wild‐type p53 and p21 Waf1/Cip1 may play a part in chronically sun‐exposed normal epidermis response to UV exposure, whereas p21 Waf1/Cip1 cannot be induced by mutated p53 in solar keratosis and squamous cell carcinoma of the skin.