This Article Full Text Full Text (PDF) Supplementary Data Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kan, C. E. Articles by Jackson, M. W. Search for Related Content PubMed PubMed Citation Articles by Kan, C. E. Articles by Jackson, M. W.

p53-Mediated Growth Suppression in Response to Nutlin-3 in Cyclin D1–Transformed Cells Occurs Independently of p21

¹ Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic and ² Department of Genetics, Case Western Reserve University, Case Comprehensive Cancer Center, Cleveland, Ohio

Requests for reprints: Mark W. Jackson, Department of Molecular Genetics, Lerner Research Institute/NE20, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195. Phone: 216-368-5674; Fax: 216-368-8919; E-mail: mwj7{at}cwru.edu.

Interaction of cyclin D1 with cyclin-dependent kinases (CDK) results in the hyperphosphorylation of the RB family of proteins, thereby inactivating the tumor-suppressive function of RB. Our previous findings suggest that constitutive cyclin D1/CDK activity inhibits p53-mediated gene repression by preventing the appropriate regulation of CDK activity by the CDK inhibitor p21, a transcriptional target of p53. To study the role of cyclin D1 in driving human mammary cell transformation, we expressed a constitutively active cyclin D1–CDK fusion protein (D1/CDK) in immortalized human mammary epithelial cells. D1/CDK-expressing human mammary epithelial cells grew anchorage-independently in the presence of wild-type p53, consistent with the idea that D1/CDK disrupts downstream p53 signaling. Using this transformation model, we examined the sensitivity of the D1/CDK-expressing cells to Nutlin-3, an HDM2 antagonist that activates p53. Surprisingly, treatment of D1/CDK-transformed cells with Nutlin-3 prevented their anchorage-independent growth. The Nutlin-3–induced growth arrest was enforced in D1/CDK-expressing cells despite the presence of hyperphosphorylated RB implicating a p53-dependent, RB-independent mechanism for growth suppression. Further analysis identified that CDC2 and cyclin B1, key cell cycle regulators, were stably down-regulated following p53 stabilization by Nutlin-3, consistent with direct interaction between p53 and the CDC2 and cyclin B1 promoters, leading to the repression of transcription by methylation. In contrast to D1/CDK expression, direct inactivation of p53 resulted in no repression of CDC2 and no cell cycle arrest. We conclude that induction of p53 by Nutlin-3 is a viable therapeutic strategy in cancers with constitutive CDK signaling due to the direct repression of specific p53 target genes. [Cancer Res 2007;67(20):9862–8]

This article has been cited by other articles:

				S. De, R. Cipriano, M. W. Jackson, and G. R. Stark Overexpression of Kinesins Mediates Docetaxel Resistance in Breast Cancer Cells Cancer Res., October 15, 2009; 69(20): 8035 - 8042. [Abstract] [Full Text] [PDF]

				W. Du, J. Wu, E. M. Walsh, Y. Zhang, C. Y. Chen, and Z.-X. J. Xiao Nutlin-3 Affects Expression and Function of Retinoblastoma Protein: ROLE OF RETINOBLASTOMA PROTEIN IN CELLULAR RESPONSE TO NUTLIN-3 J. Biol. Chem., September 25, 2009; 284(39): 26315 - 26321. [Abstract] [Full Text] [PDF]

				M. Miyachi, N. Kakazu, S. Yagyu, Y. Katsumi, S. Tsubai-Shimizu, K. Kikuchi, K. Tsuchiya, T. Iehara, and H. Hosoi Restoration of p53 Pathway by Nutlin-3 Induces Cell Cycle Arrest and Apoptosis in Human Rhabdomyosarcoma Cells Clin. Cancer Res., June 15, 2009; 15(12): 4077 - 4084. [Abstract] [Full Text] [PDF]

				Y. Tabe, D. Sebasigari, L. Jin, M. Rudelius, T. Davies-Hill, K. Miyake, T. Miida, S. Pittaluga, and M. Raffeld MDM2 Antagonist Nutlin-3 Displays Antiproliferative and Proapoptotic Activity in Mantle Cell Lymphoma Clin. Cancer Res., February 1, 2009; 15(3): 933 - 942. [Abstract] [Full Text] [PDF]