The broader goal of this application is to understand the mechanisms that regulate translation of the Cdk inhibitor p27Kip2 (p27) in normal cells and in breast cancer cells. p27 is an essential component of normal cell cycle control and is expressed at elevated levels in quiescent cells and down-regulated of normal cell cycle control and is expressed at elevated levels in quiescent cells and down-regulated upon reentry into the cell cycle. There is a very strong correlation between low p27 expression and poor clinical prognosis for numerous types of cancer, including breast cancer. p27 levels are regulated by translation initiation efficiency and by protein stability. This proposal focuses specifically on translational control of p27. Evidence is provided demonstrating that the p27 mRNA can be translated by a cap-independent mechanism through an internal ribosome entry site. Based on these findings,, a model has been developed for p27 translational control. In order to test this model three specific aims are proposed. The third specific aim is to determine if changes in p27 translation that occur during cell proliferation and differentiation are mediated through the internal ribosome entry site and to determine if activity of eIF-4E, the cap-binding protein, influences this process.
The second aim i s to determine if the decrease in 27 expression that is observed in breast cancer cells involves changes that affect p27 translation through the internal ribosome entry site. Since eIF-4E is over- expressed in virtually all breast cancer cells, its potential role in low p27 expression will be examined.
The final aim i s to characterize the molecular components required for internal ribosome assembly on the p27 mRNA. This will include identification of the RNA motifs involved, characterization of RNA-protein interactions, purification of the factors involved, and cloning of their cDNAs.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA084325-03
Application #
6489352
Study Section
Metabolic Pathology Study Section (MEP)
Program Officer
Perry, Mary Ellen
Project Start
2000-01-07
Project End
2003-12-31
Budget Start
2002-01-01
Budget End
2002-12-31
Support Year
3
Fiscal Year
2002
Total Cost
$178,141
Indirect Cost
Name
University of South Dakota
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
929930808
City
Vermillion
State
SD
Country
United States
Zip Code
57069
Halaby, Marie-Jo; Li, Yan; Harris, Benjamin R et al. (2015) Translational Control Protein 80 Stimulates IRES-Mediated Translation of p53 mRNA in Response to DNA Damage. Biomed Res Int 2015:708158
Halaby, Marie-Jo; Harris, Benjamin R E; Miskimins, W Keith et al. (2015) Deregulation of Internal Ribosome Entry Site-Mediated p53 Translation in Cancer Cells with Defective p53 Response to DNA Damage. Mol Cell Biol 35:4006-17
Zheng, Yuhuan; Miskimins, W Keith (2011) CUG-binding protein represses translation of p27Kip1 mRNA through its internal ribosomal entry site. RNA Biol 8:365-71
Zheng, Yuhuan; Miskimins, W Keith (2011) Far upstream element binding protein 1 activates translation of p27Kip1 mRNA through its internal ribosomal entry site. Int J Biochem Cell Biol 43:1641-8
Zhuang, Yongxian; Miskimins, W Keith (2011) Metformin induces both caspase-dependent and poly(ADP-ribose) polymerase-dependent cell death in breast cancer cells. Mol Cancer Res 9:603-15
Smith, N L; Miskimins, W K (2011) Phosphorylation at serine 482 affects stability of NF90 and its functional role in mitosis. Cell Prolif 44:147-55
Coleman, Jennifer; Miskimins, W Keith (2009) Structure and activity of the internal ribosome entry site within the human p27 Kip1 5'-untranslated region. RNA Biol 6:84-9
Jiang, Hong; Coleman, Jennifer; Miskimins, Robin et al. (2007) Cap-independent translation through the p27 5'-UTR. Nucleic Acids Res 35:4767-78
Wang, Gang; Miskimins, Robin; Miskimins, W Keith (2004) Regulation of p27(Kip1) by intracellular iron levels. Biometals 17:15-24
Wei, Qiou; Miskimins, W Keith; Miskimins, Robin (2003) The Sp1 family of transcription factors is involved in p27(Kip1)-mediated activation of myelin basic protein gene expression. Mol Cell Biol 23:4035-45

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