MDM2-dependent downregulation of p21 and hnRNP K provides a switch between apoptosis and growth arrest induced by pharmacologically activated p53.

We have previously identified the p53-reactivating compound RITA in a cell-based screen. Here, using microarray analysis, we show that the global transcriptional response of tumor cells to RITA is p53 dependent. Pathway analysis revealed induction of the p53 apoptosis pathway, consistent with apoptosis being the major response to RITA in cancer cells. We uncovered that MDM2 released from p53 by RITA promotes degradation of p21 and the p53 cofactor hnRNP K, required for p21 transcription. Functional studies revealed MDM2-dependent inhibition of p21 as a key switch regulating cell fate decisions upon p53 reactivation. Our results emphasize the utility of targeting wild-type p53 protein itself as a promising approach for anticancer therapy.

[1]  中尾 光輝,et al.  KEGG(Kyoto Encyclopedia of Genes and Genomes)〔和文〕 (特集 ゲノム医学の現在と未来--基礎と臨床) -- (データベース) , 2000 .

[2]  K. Kinzler,et al.  Requirement for p53 and p21 to sustain G2 arrest after DNA damage. , 1998, Science.

[3]  Lilya V. Matyunina,et al.  Evidence that p53-Mediated Cell-Cycle-Arrest Inhibits Chemotherapeutic Treatment of Ovarian Carcinomas , 2007, PloS one.

[4]  R. Tibshirani,et al.  Significance analysis of microarrays applied to the ionizing radiation response , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[5]  L. Vassilev,et al.  In Vivo Activation of the p53 Pathway by Small-Molecule Antagonists of MDM2 , 2004, Science.

[6]  Eduardo Sontag,et al.  Transcriptional control of human p53-regulated genes , 2008, Nature Reviews Molecular Cell Biology.

[7]  O. Myklebost,et al.  Small-molecule MDM2 antagonists reveal aberrant p53 signaling in cancer: implications for therapy. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[8]  M. Protopopova,et al.  Small molecule RITA binds to p53, blocks p53–HDM-2 interaction and activates p53 function in tumors , 2004, Nature Medicine.

[9]  Xin Lu,et al.  Live or let die: the cell's response to p53 , 2002, Nature Reviews Cancer.

[10]  P. Farnham,et al.  c-Myc target gene specificity is determined by a post-DNAbinding mechanism. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[11]  Xin Lu,et al.  ASPP proteins specifically stimulate the apoptotic function of p53. , 2001, Molecular cell.

[12]  P. Park,et al.  Discovering statistically significant pathways in expression profiling studies. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Ronen Marmorstein,et al.  Acetylation of the p53 DNA-binding domain regulates apoptosis induction. , 2006, Molecular cell.

[14]  Xinbin Chen,et al.  MDM2 Is a Negative Regulator of p21WAF1/CIP1, Independent of p53* , 2004, Journal of Biological Chemistry.

[15]  Rafael A. Irizarry,et al.  A Model-Based Background Adjustment for Oligonucleotide Expression Arrays , 2004 .

[16]  Lee Baker,et al.  Discovery, In Vivo Activity, and Mechanism of Action of a Small-Molecule p53 Activator , 2007, Cancer cell.

[17]  Mengjia Tang,et al.  Hdmx Modulates the Outcome of P53 Activation in Human Tumor Cells* , 2006, Journal of Biological Chemistry.

[18]  Stephen P. Jackson,et al.  hnRNP K: An HDM2 Target and Transcriptional Coactivator of p53 in Response to DNA Damage , 2005, Cell.

[19]  A. Gartel,et al.  The Role of the Cyclin-dependent Kinase Inhibitor p 21 in Apoptosis 1 , 2002 .

[20]  René Bernards,et al.  An shRNA barcode screen provides insight into cancer cell vulnerability to MDM2 inhibitors , 2006, Nature chemical biology.

[21]  M. Miura,et al.  Resistance to Fas-mediated apoptosis: activation of Caspase 3 is regulated by cell cycle regulator p21WAF1 and IAP gene family ILP , 1998, Oncogene.

[22]  Yi Tang,et al.  Tip60-dependent acetylation of p53 modulates the decision between cell-cycle arrest and apoptosis. , 2006, Molecular cell.

[23]  A. Levine,et al.  Surfing the p53 network , 2000, Nature.

[24]  I. Simon,et al.  Chromatin immunoprecipitation-on-chip reveals stress-dependent p53 occupancy in primary normal cells but not in established cell lines. , 2008, Cancer research.

[25]  D. Johnson,et al.  p21WAF1 Prevents Down-modulation of the Apoptotic Inhibitor Protein c-IAP1 and Inhibits Leukemic Apoptosis , 2000, Molecular medicine.

[26]  M. Ashburner,et al.  Gene Ontology: tool for the unification of biology , 2000, Nature Genetics.

[27]  C. Harris,et al.  The IARC TP53 database: New online mutation analysis and recommendations to users , 2002, Human mutation.

[28]  Z. Weng,et al.  A Global Map of p53 Transcription-Factor Binding Sites in the Human Genome , 2006, Cell.

[29]  F. McCormick,et al.  E2F-1 transcriptional activity is a critical determinant of Mdm2 antagonist-induced apoptosis in human tumor cell lines , 2008, Oncogene.

[30]  A. Barsotti,et al.  Caspase 2 is both required for p53-mediated apoptosis and downregulated by p53 in a p21-dependent manner , 2008, Cell cycle.

[31]  Pankaj Oberoi,et al.  Small molecule inhibitors of HDM2 ubiquitin ligase activity stabilize and activate p53 in cells. , 2005, Cancer cell.

[32]  M. Dai,et al.  MDM2 promotes p21waf1/cip1 proteasomal turnover independently of ubiquitylation , 2003, The EMBO journal.

[33]  Gordon K Smyth,et al.  Statistical Applications in Genetics and Molecular Biology Linear Models and Empirical Bayes Methods for Assessing Differential Expression in Microarray Experiments , 2011 .

[34]  M. Rolfe,et al.  Differentiation of Hdm2-mediated p53 ubiquitination and Hdm2 autoubiquitination activity by small molecular weight inhibitors , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[35]  Owen J. Marshall.  PerlPrimer: cross-platform, graphical primer design for standard, bisulphite and real-time PCR , 2004, Bioinform..

[36]  John N Weinstein,et al.  The p53 tumor suppressor network is a key responder to microenvironmental components of chronic inflammatory stress. , 2005, Cancer research.

[37]  M. El-Gewely,et al.  P53-responsive genes and the potential for cancer diagnostics and therapeutics development. , 2001, Biotechnology annual review.

[38]  Giulia Piaggio,et al.  Homeodomain-interacting protein kinase-2 phosphorylates p53 at Ser 46 and mediates apoptosis , 2002, Nature Cell Biology.