S‐I‐05 Increased Levels of Cell Division Cycle 25A Protein in Keloid Lesions

Abstract

Aim: Keloid lesions develope as a result of abnormal growth of dermal fibroblasts after the injury. On the other hand, cell division cycle (Cdc) 25 is a family of phosphatases that activate the cell cycle regulating cyclin‐dependent kinases. The three members of this family, Cdc25A, Cdc25B, and Cdc25C act in different phases of the cell cycle. In this study, we examined the dgree of expression of these phosphatases in keloid fibroblasts. Methods: Primary cultures of keloid and adjacent normal dermal fibroblasts (n = 4) as well as frozen and paraffin‐embedded keloid and normal dermal tissues (n = 12 and n = 17 respectively) were examined by Western blot and immunohistochemical analyses for the expressions of Cdc25A, Cdc25B, Cdc25C and phosphorylated Cdk2. Results: Cdc25A protein levels were frequently increased in keloid fibroblasts as compared to the adjacent normal‐appearing fibroblasts or different normal dermal fibroblasts. In contrast, Cdc25B and Cdc25C were none or rarely expressed. The incrased levels of Cdc25A were associated with lower levels of its substrate, Cdk2, in a phosphorylated or inactive form. Conclusions: Taken together, our data show that Cdc25A protein levels increase in keloid fibroblasts and this increase may be sufficient to activate its substrate, Cdk2, and accelerate the cell cycling. These results may have implication for the development of strategies to silence Cdc25A activity after the wound healing as a therapeutic modality for the keloid lesions.