The transcription factor p53 is an important master regulator of the cellular response to stress. Mdm2 is an E3 ubiquitin ligase that is the primary negative regulator of p53. Mdm2 downregulates p53 activity through three mechanisms: proteasome-mediated degradation, exportation from the nucleus, and direct inhibition through binding. Though the roles of the Mdm2-p53 axis in cancer have been well characterized, the relationship between p53 and other diseases remain elusive. Recently, three novel Mdm2 mutations were identified in patients with premature aging. One mutation leads to the abolishment of the Mdm2 stop codon, thereby extending the Mdm2 C-terminus by five additional amino acids. The other mutation leads to alternative splicing of Mdm2, resulting in two isoforms: a full length Mdm2 protein with a point mutation in the p53 binding domain and a truncated Mdm2 protein that has a 25 amino acid deletion in the p53 binding domain. Our results indicate that the causative Mdm2 variants are hyper-stable and lead to increased p53 protein stabilization. The anti-terminating mutant Mdm2 is defective as an E3 ligase, but retains its ability to bind and dampen p53 activity. However, p53 can be hyper-activated upon induction. Analysis of patient fibroblasts, patient lymphoblastoid cell lines, and genome-edited cells that express mutant Mdm2 confirmed the aberrant regulation of p53. MdmX may also potentially play a compensatory role in this axis. Altogether, our results demonstrate that defective Mdm2 can lead to constitutive dysfunctional regulation of p53 and contribute to accelerated aging phenotypes.

Thesis (Ph.D.)--Ohio University, August, 2009. / Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 89-107)

Thesis (Ph.D.)--Ohio University, August, 2009. / Title from PDF t.p. Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 89-107)

Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / On title page, the 'a' in ERa is symbolized by the Greek symbol for alpha. Includes bibliographical references (p. 108-124). Print copy also available.

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references (leaves 71-78). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38823

Cancer is a group of diseases that are the second leading cause of human mortality in the United States. Discovering new therapies is vital to conquer cancer. Thymoquinone (TQ) is found in the plant Nigella sativa. TQ was found to be cytotoxic to the human ovarian cancer cell lines PA-1, CAOV-3 and SKOV-3, which have varying p53 status. PA-1 cells were the most sensitive, indicating that TQ was effective against cells having wild-type (WT) p53. Western blots indicated an increase in p53 in cell lines having WT p53. TQ when given concurrently with cisplatin resulted in antagonism for PA-1, A172 and H460 cell lines. Sequential exposure to TQ followed by cisplatin resulted in synergy or additive effects in these cell lines. Sequential exposure to cisplatin followed by TQ resulted in additive or moderate antagonism in these cell lines. Concurrent exposure to TQ and paclitaxel showed synergy in PA-1 and H460 cells. Sequential exposure to TQ followed by paclitaxel resulted in synergism or antagonism in A172, PA-1, and H460 cells. Paclitaxel followed by TQ resulted in antagonism or synergism in these cells. These results demonstrate that TQ has a potential as an antineoplastic agent and may affect p53 levels.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 144-152). Also available in electronic version.

The TP53 gene can express protein p53 and 11 another isoform proteins N- and/or C-terminally truncated by using two promoters and alternative splicing. The p53 isoforms are found in both healthy and tumorous tissues, and are intensively studied in relation to cancer diagnosis, prognosis and treatment. In this work, the p53 isoforms were subcloned into expression vectors by LR reaction adapted from Gateway cloning system. The expression vectors were designed for protein production by bacteria E. coli strain BL-21. The constructs containing p53 isoforms were encoded together with two fusion proteins, glutathione-S-transferase and polyhistidine tag under the control of the same promotor for the affinity chromatography protein isolation. All the clones underwent Sanger sequencing for verification after homologous recombination. Sequencing confirmed the accuracy of the subcloned isoforms p53, 133p53, 160p53, p53 and 160p53 into an expression vector pDEST15-N6xHis-GST-GW-DEST. Protein 160p53 was expressed in BL-21 and isolated using both HIS and GST tag interacion. Isolation using HIS tag yielded in a higher protein concentration then the isolation mediated by the interaction of the glutathione-S-transferase.

The tumor suppressor protein p53 is one of the major regulators of the cell cycle after DNA damage. In addition to stopping the cycle and repairing DNA, it can, in extreme cases, induce programmed cell death - apoptosis. Mutations in the gene encoding p53 are present in more than 50% of cancer cases. This thesis examines alternative natural polyphenolic substances that could increase the level and expression of p53 protein in tumor cells. These substances could be an alternative to non-specific cytostatics, which bring many undesirable additional effects during treatment. In the theoretical part of the thesis the structure and properties of the p53 protein and describes alternative therapeutic approaches with a focus on polyphenolic substances is explained. The aim of the experimental part was to determine the effect of curcumin and resveratrol in comparison with often used cytostatic drug, doxorubicin, on cell viability of tumor cells and on p53 protein levels. The effect of these substances on the binding of p53 to DNA in yeast systems was also examined. It was found that doxorubin efficiency is many times higher than the examined polyphenolic agents, but resveratrol was showing some potential as a suitable alternative in the treatment of tumors, thanks to the ability to activate apotosis. It was clearly demonstrated that there is an association between induced programmed death and increased p53 protein expression after resveratrol treatment.