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p53 and apoptosis alterations in keloids and keloid fibroblasts
Author(s) -
Ladin Daniel A.,
Hou Zizheng,
Patel Dipa,
McPhail Monica,
Olson Jennifer C.,
Saed Ghassan M.,
Fivenson David P.
Publication year - 1998
Publication title -
wound repair and regeneration
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.847
H-Index - 109
eISSN - 1524-475X
pISSN - 1067-1927
DOI - 10.1046/j.1524-475x.1998.60106.x
Subject(s) - keloid , fibroblast , wound healing , apoptosis , pathology , tunel assay , immunohistochemistry , flow cytometry , immunoperoxidase , fibroblast activation protein, alpha , staining , antigen , biology , antibody , microbiology and biotechnology , medicine , in vitro , monoclonal antibody , immunology , cancer , biochemistry , genetics
Keloids are the result of a dysregulated wound‐healing process and are characterized by formation of excess scar tissue that proliferates beyond the boundaries of the inciting wound. In this study, we investigated the expression of key proteins involved in regulating apoptosis in keloids. Twenty archival paraffin‐embedded keloid samples were randomly selected for an immunoperoxidase assay with antibodies against fas, p53, bcl‐2, and bcl‐x proteins using the target antigen‐retrieval technique. Apoptosis was assessed in keloids and normal skin and in keloid and normal fibroblasts by the TdT‐mediated dUTP nick‐end labeling (tunel) assay on tissue sections, fibroblast cultures, and by flow cytometry for cell suspensions. We found that 18 of 20 keloids expressed p53 protein; bcl‐2 was expressed by keloid fibroblasts in 19 of 20 keloids, and all specimens had prominent fas expression throughout the tissue. The distribution of these three antigens was regional within each lesion and followed a consistent pattern of p53 and bcl‐2 expression colocalized to the hypercellular, peripheral areas of each keloid in a perinuclear pattern ( p < .001). In contrast, an inverse distribution of fas expression was shown, with staining being more diffuse across the cell surfaces and limited to the central, more hypocellular regions in 16 of 17 keloids ( p < .001). There was no specific staining pattern in these keloids with antihuman bcl‐x. In vitro studies on cultured keloid fibroblasts (derived from six patients) revealed maintenance of the p53+, bcl‐2+ phenotype up to passage 10. Neither neonatal nor normal adult skin fibroblasts expressed either antigen but could be induced to express p53 by exposure to adriamycin. Keloid lesions and keloid fibroblasts were found to have lower rates of apoptosis than normal controls. Keloid fibroblasts displayed enhanced apoptosis rates in response to hydrocortisone, γ interferon and hypoxia treatment as compared with normal adult fibroblasts. Focal dysregulation of p53 combined with upregulation of bcl‐2 may help produce a combination of increased cell proliferation and decreased cell death in the younger hypercellular areas of the keloid. This phenotype is reversed in the older areas of the keloid and may prevent malignan degeneration, thus favoring normal apoptosis as evidenced by prominent fas expression.