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Negative auto-regulators trap p53 in their web Free
Xiang Zhou1,†,*, Bo Cao2,†, and Hua Lu2,*
1 Fudan University Shanghai Cancer Center and the Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
2 Department of Biochemistry & Molecular Biology and Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA 70112, USA
† These authors contributed equally to this work *Correspondence to:Xiang Zhou, E-mail: xzhou24@hotmail.com; Hua Lu, E-mail: hlu2@tulane.edu
J Mol Cell Biol, Volume 9, Issue 1, February 2017, Pages 62-68  https://doi.org/10.1093/jmcb/mjx001
Keyword: : p53, MDM2, NGFR, transcription, feedback loop, chemoresistance

The transcriptional factor p53 activates the expression of a myriad of target genes involving a complicated signalling network, resulting in various cellular outcomes, such as growth arrest, senescence, apoptosis, and metabolic changes, and leading to consequent suppression of tumour growth and progression. Because of the profoundly adverse effect of p53 on growth and proliferation of cancer cells, several feedback mechanisms have been employed by the cells to constrain p53 activity. Two major antagonists MDM2 and MDMX (the long forms) are transcriptionally induced by p53, but in return block p53 activity, forming a negative feedback circuit and rendering chemoresistance of several cancer cells. However, they are not alone, as cancer cells also employ other proteins encoded by p53 target genes to inhibit p53 activity at transcriptional, translational, and posttranslational levels. This essay is thus composed to review a recent progress in understanding the mechanisms for how cancer cells hijack the p53 autoregulation by these proteins for their growth advantage and to discuss the clinical implications of these autoregulatory loops.