Mutation in the p53 tumor suppressor gene is a common event in human cancer. In the majority of human carcinomas with p53 mutations the mutant protein is over-expressed suggesting the existence of a selective advantage to maintain expression. The long-term goal of our research is to understand how p53 mutations lead to oncogenesis. The short-term objective is to test the following hypothesis: Expression of p53 mutants in human cells deregulates pathways controlled by the NF-kB2, a property critically important for chemosensitivity and tumor progression. The above-mentioned hypothesis is based on the following observations: Compared to vector transfected cells, H1299 p53-null human lung carcinoma cells expressing mutant p53 showed chemo-resistance when treated with common chemotherapeutic agents;however, cells expressing transactivation deficient mutants lose this function significantly, suggesting that transactivation by mutant p53 is crucial for chemo-resistance. A number of lung and breast cancer cell line with mutant p53 show chemo-resistance that is dependent on the level of p53 as the chemo-resistance decreases when the p53 level is lowered. p53 mutants induced expression of a number of genes involved in cell growth, survival, invasion, metastasis and angiogenesis. NF-kB2 was among this group. Introduction of short interfering RNA specific for NF-:B2 made these cells lose chemo-resistance. A preliminary screen of human lung cancer specimens shows co-existing p53 mutation and over-expression of NF-kB2 suggesting that, in the clinic, there is a subset of patients with p53 mutation and NF-kB2 over-expression. Our data also indicate that mutant p53 expression enhances cell adhesion, motility, tumorigenicity and metastatic phenotype. The following are the specific aims: 1. (a) To determine whether mutant p53 over-expression leads to higher levels of NF-kB2 in lung cancer. (b) To determine whether NF-kB2 is involved in reducing chemosensitivity in cancer cells expressing mutant p53. 2. To determine whether NF-:B2 enhances motility of cells expressing mutant p53. 3. To determine the mechanism of NF-kB2 up-regulation by mutant p53. 4. To identify factors interacting specifically with GOF p53 mutants utilizing mass spectrometric analysis. The proposed research will investigate the relationship between p53 mutants commonly found in cancer and the NF-:B2 pathway. In future, tumors with p53 mutations can be targeted at NF-:B2, mutant p53 and many of their potential target genes. Chemoresistance and Motility: Role of Mutant p53 and NF-:B2 in Cancer.

Public Health Relevance

This application is based on a novel observation that tumor-derived p53 mutants up-regulate NF-kB2 expression in cell culture. Preliminary examination of human tumors also indicates that lung tumors with p53 mutation have a higher NF-:B2 level. We also find that mutant p53 expression induces higher motility and chemo-resistance in cells expressing them. We propose to determine the molecular mechanism of this up- regulation and find out how that is related to chemo-resistance and higher motility of cells expressing mutant p53. Results obtained from this study should lead to identification of a subset of lung tumors co- expressing NFkB2 and mutant p53 that could be targeted by inhibitors of NF-kB pathway to prevent tumor progression.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA121144-04
Application #
8130849
Study Section
Basic Mechanisms of Cancer Therapeutics Study Section (BMCT)
Program Officer
Watson, Joanna M
Project Start
2008-09-01
Project End
2013-07-31
Budget Start
2011-08-01
Budget End
2013-07-31
Support Year
4
Fiscal Year
2011
Total Cost
$240,725
Indirect Cost
Name
Virginia Commonwealth University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
105300446
City
Richmond
State
VA
Country
United States
Zip Code
23298
Vaughan, Catherine A; Singh, Shilpa; Grossman, Steven R et al. (2017) Gain-of-function p53 activates multiple signaling pathways to induce oncogenicity in lung cancer cells. Mol Oncol 11:696-711
Frum, Rebecca A; Love, Ian M; Damle, Priyadarshan K et al. (2016) Constitutive Activation of DNA Damage Checkpoint Signaling Contributes to Mutant p53 Accumulation via Modulation of p53 Ubiquitination. Mol Cancer Res 14:423-36
Vaughan, Catherine A; Pearsall, Isabella; Singh, Shilpa et al. (2016) Addiction of lung cancer cells to GOF p53 is promoted by up-regulation of epidermal growth factor receptor through multiple contacts with p53 transactivation domain and promoter. Oncotarget 7:12426-46
Zhang, Honghong; Tassone, Cecilie; Lin, Nora et al. (2015) Detection of Bax Microsatellite Mutations and Bax?2 Isoform in Human Buccal Cells. J Cell Sci Ther 6:
Frum, Rebecca A; Singh, Shilpa; Vaughan, Catherine et al. (2014) The human oncoprotein MDM2 induces replication stress eliciting early intra-S-phase checkpoint response and inhibition of DNA replication origin firing. Nucleic Acids Res 42:926-40
Vaughan, Catherine A; Deb, Swati P; Deb, Sumitra et al. (2014) Preferred binding of gain-of-function mutant p53 to bidirectional promoters with coordinated binding of ETS1 and GABPA to multiple binding sites. Oncotarget 5:417-27
Ramamoorthy, Mahesh; Vaughan, Catherine; Deb, Sumitra et al. (2013) Measurement of chemosensitivity and growth rate in p53 expressing cells. Methods Mol Biol 962:127-33
Frum, Rebecca A; Deb, Sumitra; Deb, Swati Palit (2013) Use of the DNA fiber spreading technique to detect the effects of mutant p53 on DNA replication. Methods Mol Biol 962:147-55
Gadepalli, Venkat S; Vaughan, Catherine; Rao, Raj R (2013) Isolation and characterization of murine multipotent lung stem cells. Methods Mol Biol 962:183-91
Singh, S; Ramamoorthy, M; Vaughan, C et al. (2013) Human oncoprotein MDM2 activates the Akt signaling pathway through an interaction with the repressor element-1 silencing transcription factor conferring a survival advantage to cancer cells. Cell Death Differ 20:558-66

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