Activated caspase expression and apoptosis increase in keloids: cytochrome c release and caspase-9 activation during the apoptosis of keloid fibroblast lines.
To characterize apoptosis in keloids and the mechanisms responsible for this process, the expression of activated caspase-9 and -3 in fibroblasts obtained from keloids was analyzed. Immunohistochemistry revealed that the number of fibroblasts positive for terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) or activated caspase-9 or -3 was low but was significantly higher in keloid tissues than in normal scar tissues. Significant relationships between the number of caspase-positive fibroblasts and TUNEL-positive fibroblasts suggested that the activation of caspase-9 and -3 induces apoptosis in a subpopulation of keloid fibroblasts. All keloid fibroblast cell lines established in this study showed activation of caspase-9 and -3 after serum deprivation for 3 or 4 hours, as shown using Western blotting. Furthermore, serum deprivation-induced apoptosis in a keloid fibroblast line was blocked by a caspase-9 inhibitor (acetyl-Leu-Glu-His-Asp-al), indicating that activation of caspase-9 was necessary for the process of apoptosis in keloid fibroblasts. Although serum deprivation did not significantly change the level of apoptosis protease activating factor-1 in any of the lines, cytochrome c release was detected in cytosolic fractions of the lines after serum deprivation for 3 or 4 hours. These results strongly suggest that keloid fibroblasts are predisposed to apoptosis and cytochrome c release and that caspase-9 activation may underlie regulation of apoptosis in keloid fibroblasts in vivo.
Akasaka
Yoshikiyo
Y
Department of Pathology, School of Medicine, Toho University, Tokyo, Japan. akasakay@med.toho-u.ac.jp
Ito
Kinji
K
Fujita
Kazuko
K
Komiyama
Kazuo
K
Ono
Ichiro
I
Ishikawa
Yukio
Y
Akishima
Yuri
Y
Sato
Hiroko
H
Ishii
Toshiharu
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000502:physiology*; D053477:Apoptotic Protease-Activating Factor 1; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000096:biosynthesis*; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D045304:Cytochromes c / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts; D006801:Humans; D007223:Infant; D007627:Keloid / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011506:Proteins / Q000032:analysis / Q000378:metabolism
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D011506:Proteins; D045304:Cytochromes c; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases