期刊
CANCER RESEARCH
卷 70, 期 10, 页码 4034-4044出版社
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/0008-5472.CAN-09-4063
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资金
- Ministry of Health Labor and Welfare of Japan
- Ministry of Education, Culture, Sports, Science, and Technology of Japan
The p53 family member p63 is a master regulator of epithelial development. One of its isoforms, Delta Np63 alpha, is predominantly expressed in the basal cells of stratified epithelia and plays a fundamental role in control of regenerative potential and epithelial integrity. In contrast to p53, p63 is rarely mutated in human cancers, but it is frequently overexpressed in squamous cell carcinomas (SCC). However, its functional relevance to tumorigenesis remains largely unclear. We previously identified the Notch1 gene as a novel transcriptional target of p53. Here, we show that Delta Np63 alpha functions as a transcriptional repressor of the Notch1 gene through the p53-responsive element. Knockdown of p63 caused upregulation of Notch1 expression and marked reduction in proliferation and clonogenicity of both normal human keratinocytes and cervical cancer cell lines overexpressing Delta Np63 alpha. Concomitant silencing of Notch1 significantly rescued this phenotype, indicating the growth defect induced by p63 deficiency to be, at least in part, attributable to Notch1 function. Conversely, overexpression of Delta Np63 alpha decreased basal levels of Notch1, increased proliferative potential of normal human keratinocytes, and inhibited both p53-dependent and p53-independent induction of Notch1 and differentiation markers upon genotoxic stress and serum exposure, respectively. These results suggest that Delta Np63 alpha maintains the self-renewing capacity of normal human keratinocytes and cervical cancer cells partly through transcriptional repression of the Notch1 gene and imply a novel pathogenetical significance of frequently observed overexpression of Delta Np63 alpha together with p53 inactivation in SCCs. Cancer Res; 70(10); 4034-44. (C) 2010 AACR.
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