Nuclear-cytoplasmic shuttling has emerged as an important determinant of p53 activity. Various cancers and normal cells have been described in which p53 is inactivated through abnormal sequestration in the cytoplasm, including neuroblastoma, breast cancer, and stressed endothelial cells, among others. Current models suggest this cytoplasmic localization results from excessive nuclear export that is mediated by MDM2, followed by association between p53 and one or more cytoplasmic """"""""anchor"""""""" proteins. Strategies to inhibit nuclear export or block anchor-protein binding may promote p53 nuclear accumulation and enhance sensitivity to current cytotoxic therapies. We have established an assay system in which MDM2 promotes p53 nuclear export in transiently transfected cells. DNA damaging agents block p53 nuclear export in this system. We will characterize the effect of DNA damaging stress on p53 nuclear export, the role of p53 phosphorylation in this effect, and whether the ATM or ATR kinases are required to inhibit p53 export following stress. In addition, we will examine p53 activity in two model cell types (human umbilical vein endothelial cells (HUVECs) and breast cancer cells) where wild-type p53 is inactivated due to excessive nuclear export and cytoplasmic sequestration. Certain compounds are predicted to block binding between p53 and its cytoplasmic anchor in stressed HUVECs, and may also block p53:anchor protein binding in breast cancer cells. We are testing the effect of these compounds on p53 localization and cellular sensitivity to radiation and other chemotherapeutic agents.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA080918-06
Application #
6823880
Study Section
Cancer Etiology Study Section (CE)
Program Officer
Knowlton, John R
Project Start
1999-06-15
Project End
2007-08-31
Budget Start
2004-09-10
Budget End
2005-08-31
Support Year
6
Fiscal Year
2004
Total Cost
$248,544
Indirect Cost
Name
University of Chicago
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
Moran, D M; Gawlak, G; Jayaprakash, M S et al. (2008) Geldanamycin promotes premature mitotic entry and micronucleation in irradiated p53/p21 deficient colon carcinoma cells. Oncogene 27:5567-77
Shen, Hong; Moran, Diarmuid M; Maki, Carl G (2008) Transient nutlin-3a treatment promotes endoreduplication and the generation of therapy-resistant tetraploid cells. Cancer Res 68:8260-8
Nie, Linghu; Sasaki, Mark; Maki, Carl G (2007) Regulation of p53 nuclear export through sequential changes in conformation and ubiquitination. J Biol Chem 282:14616-25
Sasaki, Mark; Nie, Linghu; Maki, Carl G (2007) MDM2 binding induces a conformational change in p53 that is opposed by heat-shock protein 90 and precedes p53 proteasomal degradation. J Biol Chem 282:14626-34
Inoue, Tomomi; Wu, Liqing; Stuart, Jeremy et al. (2005) Control of p53 nuclear accumulation in stressed cells. FEBS Lett 579:4978-84
Wu, Liqing; Zhu, Hongyan; Nie, Linghu et al. (2004) A link between p73 transcriptional activity and p73 degradation. Oncogene 23:4032-6
Wei, Xiaolong; Yu, Zhong Kang; Ramalingam, Arivudainambi et al. (2003) Physical and functional interactions between PML and MDM2. J Biol Chem 278:29288-97
Inoue, Tomomi; Stuart, Jeremy; Leno, Richard et al. (2002) Nuclear import and export signals in control of the p53-related protein p73. J Biol Chem 277:15053-60
Inoue, T; Geyer, R K; Yu, Z K et al. (2001) Downregulation of MDM2 stabilizes p53 by inhibiting p53 ubiquitination in response to specific alkylating agents. FEBS Lett 490:196-201
Inoue, T; Geyer, R K; Howard, D et al. (2001) MDM2 can promote the ubiquitination, nuclear export, and degradation of p53 in the absence of direct binding. J Biol Chem 276:45255-60

Showing the most recent 10 out of 12 publications