title: Alteration of p53-binding protein 1 expression during skin carcinogenesis: association with genomic instability.
abstract: Epidermal cells are the first cells to be exposed to environmental genotoxic agents such as ultraviolet and ionizing radiations, which induce DNA double strand breaks (DSB) and activate DNA damage response (DDR) to maintain genomic integrity. Defective DDR can result in genomic instability (GIN) which is considered to be a central aspect of any carcinogenic process. P53-binding protein 1 (53BP1) belongs to a family of evolutionarily conserved DDR proteins. Because 53BP1 molecules localize at the sites of DSB and rapidly form nuclear foci, the presence of 53BP1 nuclear foci can be considered as a cytological marker for endogenous DSB reflecting GIN. The levels of GIN were analyzed by immunofluorescence studies of 53BP1 in 56 skin tumors that included 20 seborrheic keratosis, eight actinic keratosis, nine Bowen's disease, nine squamous cell carcinoma, and 10 basal cell carcinoma. This study demonstrated a number of nuclear 53BP1 foci in human skin tumorigenesis, suggesting a constitutive activation of DDR in skin cancer cells. Because actinic keratosis showed a high DDR type of 53BP1 immunoreactivity, GIN seems to be induced at the precancerous stage. Furthermore, invasive cancers exhibited a high level of intense, abnormal 53BP1 nuclear staining with nuclear accumulation of p53, suggesting a disruption of DDR leading to a high level of GIN in cancer cells. The results of this study suggest that GIN has a crucial role in the progression of skin carcinogenesis. The detection of 53BP1 expression by immunofluorescence can be a useful histological marker to estimate the malignant potential of human skin tumors.
authors.affiliation: Department of Tumor and Diagnostic Pathology, Atomic Bomb Disease Institute, Nagasaki Unviersity Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Naruke
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakashima
authors.forename: Keiji
authors.initials: K
authors.lastname: Suzuki
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Matsuu-Matsuyama
authors.forename: Kazuko
authors.initials: K
authors.lastname: Shichijo
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Kondo
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sekine
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002467:Cell Nucleus / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D042822:Genomic Instability; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism*; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1