The broad goal of the project is to understand the mechanisms by which RNA binding protein RBM3 regulates gene expression at the posttranscriptional level of mRNA stability and translation in cancer cells. We have identified that overexpression of the protein causes a normal cell to undergo a transformed phenotype resulting in the cells forming tumors in immunocompromized mice. On the other hand, knockdown of RBM3 expression results in cell death due to mitotic catastrophe. RBM3 interacts with HuR and hnRNP A1, and with AU-RNA sequences to enhance mRNA stability and translation of AU-rich transcripts such as COX-2, VEGF and IL-8. In addition, RBM3 overexpression increases the activation of the mammalian target of rapamycin protein in a Notch dependent mechanism. We have also identified microRNAs regulated upon RBM3 overexpression, including downregulating one that inhibits its own expression. Our studies also suggest that RBM3 is regulated at the posttranslational levels of phosphorylation, ubiquitination and SUMOylation. Based on these observations, we propose three specific aims.
In Aim 1, we will determine the mechanism by which RNA binding protein RBM3 regulates gene expression. Here, we will identify the RNA sequences that interact with RBM3. In addition, we will determine the sequenced in COX-2 3'UTR that are required for RBM3-mediated COX-2 mRNA stability and translation. We will also identify the role of HuR and hnRNP-A1 in the process.
In Aim 2, we will determine the residues in RBM3 that undergo phosphorylation, ubiquitination and SUMOylation by mutagenesis. We will also determine the effect of the mutants on mRNA stability and translation.
In Aim 3, we propose to determine the mechanisms by which RBM3 induces tumorigenesis. We will use an xenograft cancer model to determine the role of mTOR and Notch pathway in RBM3 mediated tumorigenesis. Also, the role of microRNAs in the tumorigenesis will be determined. Completion of these experiments should give us a better understanding of how the RNA binding protein RBM3 functions in normal epithelial cells, and whether changes in the RBM3 expression that is observed in tumor cells is responsible for tumor behavior.

Public Health Relevance

Cancer is the leading cause of death in the United States. Understanding how the normal cell progresses to a cancer will aid in our developing novel therapies for this dreaded disease. We have identified a protein, RBM3 whose expression is increased in cancer cells. Overexpressing RBM3 protein causes a normal cell to become transformed into a cancer cell. Our current proposal deals with identifying mechanisms by which RBM3 expression is regulated, and also how RBM3 induces tumorigenesis. We expect that the work will lead to a better understanding of the tumorigenesis process which should subsequently lead to novel methods to stop or slow down tumorigenesis.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA135559-05
Application #
8444646
Study Section
Cancer Etiology Study Section (CE)
Program Officer
Strasburger, Jennifer
Project Start
2009-04-01
Project End
2014-01-31
Budget Start
2013-02-01
Budget End
2014-01-31
Support Year
5
Fiscal Year
2013
Total Cost
$283,799
Indirect Cost
$94,600
Name
University of Kansas
Department
Physiology
Type
Schools of Medicine
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
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He, Zhiyun; Subramaniam, Dharmalingam; Zhang, Zhongtao et al. (2013) Honokiol as a Radiosensitizing Agent for Colorectal cancers. Curr Colorectal Cancer Rep 9:
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He, Zhiyun; Subramaniam, Dharmalingam; Ramalingam, Satish et al. (2011) Honokiol radiosensitizes colorectal cancer cells: enhanced activity in cells with mismatch repair defects. Am J Physiol Gastrointest Liver Physiol 301:G929-37
Ali, Naushad; Allam, Heba; May, Randal et al. (2011) Hepatitis C virus-induced cancer stem cell-like signatures in cell culture and murine tumor xenografts. J Virol 85:12292-303
Anant, Shrikant; Houchen, Courtney W; Pawar, Vaibhav et al. (2010) Role of RNA-Binding Proteins in Colorectal Carcinogenesis. Curr Colorectal Cancer Rep 6:68-73

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