Differential p63 and p53 expression in human keloid fibroblasts and hypertrophic scar fibroblasts

The p63 gene belongs to the p53 gene family and encodes for sequence-specific transcription factors. p63 has been characterized primarily in the context of epidermis where is implicated in the establishment of keratinocyte cell fate and in maintenance of epithelial self-renewal. ΔNp63 isoform has been showed to be involved in several kinds of human tumors of epidermal origin, even nonmalignant, for the neoplastic and proliferative potential. Here, we report the differential expression and the cellular localization of the ΔNp63 isoform in fibroblasts isolated from human keloids and hypertrophic scars compared to normal skin. Differently from hypertrophic scar, our results show that ΔNp63 has a nuclear localization and is overexpressed only in keloid fibroblasts, suggesting an essential role of ΔNp63 in vivo in human keloids. Consistent with our results, we hypothesize that ΔNp63 overexpression may be oncogenic because of its ability to block the activity of p53 since p53 is underexpressed in fibroblasts from keloids. © Mary Ann Liebert, Inc.