ヨゴサワ　シンゴ   YOGOSAWA Shingo   与五沢　真吾    所属   埼玉医科大学  保健医療学部 臨床検査学科    職種   准教授
論文種別	学術雑誌(原著)
言語種別	英語
査読の有無	査読あり
表題	p53 Inactivation Upregulates p73 Expression through E2F-1 Mediated Transcription
掲載誌名	正式名：PLOS ONE ISSNコード：1932-6203
出版社	PUBLIC LIBRARY SCIENCE
巻・号・頁	7(8),e43564頁
著者・共著者	Chaitali Tophkhane,Shi-He Yang,Yunbo Jiang,Zhikun Ma,Dharmalingam Subramaniam,Shrikant Anant,Shingo Yogosawa,Toshiyuki Sakai,Wan-Guo Liu,Susan Edgerton,Ann Thor,Xiaohe Yang
発行年月	2012/08
概要	While p73 overexpression has been associated with increased apoptosis in cancer tissues, p73 overexpressing tumors appear to be of high grade malignancy. Why this putative tumor suppressor is overexpressed in cancer cells and what the function of overexpressed p73 is in breast cancers are critical questions to be addressed. By investigating the effect of p53 inactivation on p73 expression, we found that both protein and mRNA levels of TAp73 were increased in MCF-7/p53siRNA cells, MCF-7/p53mt135 cells and HCT-116/p532/2 cells, as compared to wild type control, suggesting that p53 inactivation by various forms upregulates p73. We showed that p53 knockdown induced p73 was mainly regulated at the transcriptional level. However, although p53 has a putative binding site in the TAp73 promoter, deletion of this binding site did not affect p53 knockdown mediated activation of TAp73 promoter. Chromatin immuno-precipitation (ChIP) data demonstrated that loss of p53 results in enhanced occupancy of E2F-1 in the TAp73 promoter. The responsive sequence of p53 inactivation mediated p73 upregulation was mapped to the proximal promoter region of the TAp73 gene. To test the role of E2F-1 in p53 inactivation mediated regulation of p73 transcription, we found that p53 knockdown enhanced E2F-1 dependent p73 transcription, and mutations in E2F-1 binding sites in the TAp73 promoter abrogated p53 knockdown mediated activation of TAp73 promoter. Moreover, we demonstrated that p21 is a mediator of p53-E2F crosstalk in the regulation of p73 transcription. We concluded that p53 knockdown/inactivation may upregulate TAp73 expression through E2F-1 mediated transcriptional regulation. p53 inactivation mediated upregulation of p73 suggests an intrinsic rescuing mechanism in response to p53 mutation/inactivation. These findings support further analysis of the correlation between p53 status and p73 expression and its prognostic/predictive significance in human cancers.
DOI	10.1371/journal.pone.0043564
PMID	22952705