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Investigating The P53 Tumor-Suppressive Network And The Dynamics/Mechanism Of P53 Loss Of Heterozygosity, Jun Wang

All ETDs from UAB

Tumor suppressor gene TP53 is the most frequently mutated gene across human cancers (~50%). Patients with Li-Fraumeni syndrome (LFS) who carry germline p53 mutations exhibit a diverse spectrum of childhood- and adult-onset malignancies. Despite over 40 years of dedicated studies to understand the role of p53 in tumor prevention, there are still many unanswered questions regarding the underlying mechanisms of p53. Previous studies have supported the notion that p53 exerts its tumor-suppressive function through its transcriptional activities. Therefore, strategies to enhance p53’s functions in tumor suppression via manipulating of downstream target gene activities in cancers show promising. To better investigate …

Discovery Of Sex Differences In Response To P53 Loss And Gain-Of-Function In Glioblastoma, Nathan Cuyle Rockwell

Arts & Sciences Electronic Theses and Dissertations

The tumor suppressor TP53 (p53) is the most frequently mutated gene in cancer and among the most mutated genes in brain cancer. Functionally, p53 is a transcription factor that, when activated by an array of stress stimuli, regulates a complex transcriptional program that contributes to a variety of antiproliferative pathways. The loss of p53 function (LOF), either through mutation, deletion, or inhibition by alterations in the proteins that regulate p53, removes an essential barrier to the unfettered proliferation and genomic instability that drive transformation. Unlike most tumor suppressors, many p53 mutations are missense mutations that lead to stable expression of …

Mechanisms Of Apoptosis Induced By Actinomycin D In Aerodigestive Tract Cancers, Adeoluwa Ayodeji Adeluola

Theses, Dissertations and Capstones

Upper aerodigestive tract cancers including cancers of the oral cavity, pharynx, larynx, esophagus, and lungs are the most prevalent cancers and leading causes of cancer-related deaths. Collectively, over 300,000 new cases and 146,500 deaths are projected within the US in the year 2021. Drug-associated toxicities, as well as resistance to therapy (intrinsic and acquired), are big challenges for successfully treating these cancers. Recent studies have shown that combining low-dose actinomycin D with existing therapies is a promising strategy to reduce toxicity (cyclotherapy) and to overcome resistance. The development of these treatment strategies however requires an understanding of the molecular mechanisms …

P53 Drives A Transcriptional Program That Elicits A Non-Cell-Autonomous Response And Alters Cell State In Vivo, Sydney Moyer

Dissertations & Theses (Open Access)

Cell stress and DNA damage activate the tumor suppressor p53, triggering transcriptional activation of a myriad of target genes. The molecular, morphological, and physiological consequences of this activation remain poorly understood in vivo. We activated a p53 transcriptional program in mice by deletion of Mdm2, a gene which encodes the major p53 inhibitor. By overlaying tissue-specific RNA-sequencing data from pancreas, small intestine, ovary, kidney, and heart with existing p53 ChIP-sequencing, we identified a large repertoire of tissue-specific p53 genes and a common p53 transcriptional signature of seven genes which included Mdm2 but not p21. Global p53 activation …

P53r245w Mutation Elicits Metastatic Phenotype In Pten Deficient Prostate Cancer, Ky Pham

Dissertations & Theses (Open Access)

Trp53 mutations are the most frequent genetic alterations in prostate cancer and are associated with more aggressive disease and worse overall survival. The majority of Trp53 mutations in prostate cancer are missense mutations, resulting in amino acid substitutions with profound effect. In addition to the loss of wild type function, missense mutations in Trp53 result in a gain-of-function (GOF) phenotype. This GOF phenotype confers biologic advantages to the tumor cells, enabling them to metastasize and invade distant organs. In this study, we generated mice carrying a conditional prostate-specific p53R245W mutant and Pten deletion to access the role of this common …

Novel Insights Into The Use Of Ercc1 As A Biomarker For Response To Platinum-Based Chemotherapy In Lung Cancer, Joshua Ryan Heyza

Wayne State University Dissertations

ERCC1/XPF is a DNA endonuclease with variable expression in primary tumor specimens, and has been investigated as a predictive biomarker for efficacy of platinum-based chemotherapy in non-small cell lung cancers where up to 30-60% of tumors harbor low to undetectable ERCC1 expression. The failure of an international, randomized Phase III clinical trial utilizing ERCC1 expression to predict response to platinum-based chemotherapy suggests additional mechanisms underlying the basic biology of ERCC1 in the response to platinum-DNA damage remain unknown. In this work, we aimed to characterize a panel of ERCC1 knockout cell lines generated via CRISPR-Cas9 where we identified a synthetic …

Study Of Alpha Mangostin As A Chemoprotective Agent For Breast Cancer Via Activation Of The P53 Pathway, Vanessa Van Oost

Pence-Boyce STEM Student Scholarship

Breast carcinoma is the most frequently diagnosed cancer among women and causes over 400,000 deaths yearly worldwide. Current treatments such as chemotherapy are not selective for cancerous tissues but are destructive to normal tissues as well. This causes a range of side effects including pain, nausea, hair loss, weakness, and more. Inactivation of p53 is an almost universal mutation within human cancer cells. The ability to activate the p53 pathway which protects cells from tumor formation is lost in 50% of cancers. Due to the prevalence of this mutation, p53 is a uniquely valuable target for applied research. Alpha mangostin …

Trim24 As An Oncogene In The Mammary Gland, Aundrietta Duncan

Dissertations & Theses (Open Access)

Despite the many advances made in breast cancer research and treatments, breast cancer remains one of the deadliest diseases plaguing women worldwide. While many findings on genetic mutations and their role in predisposing people to breast cancer have been uncovered, we are just beginning to understand the extent to which epigenetic regulators promote tumorigenic phenotypes, metastasis, and chemotherapeutic resistance. Moreover, new experimental tools offer the ability to address questions we were previously unable to assess. My project takes advantage of a new mouse model to understand the role of a proto-oncogenic, transcriptional co-regulator, TRIM24, in mammary gland development and disease. …

Effects Of The Mortalin Inhibitor Mkt-077 On The Tumor Suppressor P53 In Neuroblastoma Imr-32 Cells, Yusuf Ebrahim

Honors Theses and Capstones

The tumor suppressor protein, p53, is an important cell cycle regulator in humans. Over half of all human cancers involve disruption of p53 function. One way this is achieved is by tethering p53 to the mitochondrial 70 kilodalton heat shock protein (Hsp70), mortalin, in the cytoplasm, and preventing p53 from entering the nucleus. The mortalin inhibitor, MKT-077, binds competitively to the p53 binding site in mortalin, and disrupts the p53-mortalin complex in cancer cell lines, allowing p53 to enter the nucleus and promote apoptotic cell death. Previous research reported that cytoplasmic tethering of p53 occurs in certain human neuroblastomas. Thus, …

Contrasting Effects Of An Mdm2 Functional Polymorphism On Tumor Phenotypes, Guadalupe J. Ortiz Iv

Dissertations & Theses (Open Access)

Cancer predisposition by the cooperation of genetic variants, such as single nucleotide polymorphisms (SNPs), may be of much greater significance to public health than previously appreciated. Functional polymorphisms are genetic variants that alter gene function. Meta-analyses associate many functional polymorphisms with cancer risk. The MDM2 SNP309G allele is a cancer-associated functional polymorphism positioned in the MDM2 P2 promoter that enhances transcription factor SP1 binding, resulting in elevated levels of MDM2 concomitant with decreased p53 tumor-suppressor activity. Mdm2^SNP309G/G mice are more prone to spontaneous tumor formation than Mdm2^SNP309T/T mice, providing direct evidence for the impact of this SNP on …

Targeting Apoptotic Pathways To Overcome Drug Resistance In Acute Myeloid Leukemia, Rongqing Pan

Dissertations & Theses (Open Access)

Evasion of apoptosis is integral to tumorigenesis and drug resistance. BCL-2 and p53 proteins represent two focal nodes in convergent apoptosis signaling. Upregulation of anti-apoptotic BCL-2 family members and inactivation of p53 functions are two canonical approaches exploited by cancer cells to escape apoptosis. In the current study, we find that BCL-2 protein is highly expressed in acute myeloid leukemia (AML) cells. BCL-2–specific inhibitor ABT-199 potently induces mitochondrial apoptosis in AML cells and effectively kills AML stem/progenitor cells. Our biomarker studies demonstrate that both BH3 profiling and the expression profiling of BCL-2 proteins may serve as predictive biomarkers for the …

Using Mouse Models To Define How The P53 R72p Polymorphism Impacts The Adverse Effects Of Doxorubicin And Ionizing Radiation, Emily Dominguez

Dissertations & Theses (Open Access)

The single nucleotide polymorphism (SNP) at codon 72 of the tumor suppressor gene p53 codes for either an arginine (R) or proline (P) (p53 R72P). This SNP may impact how cells respond to genotoxic insult. Studies in cell culture and in tissues from mouse models of the SNP indicate that, in response to gentoxic treatment, the two variants may differentially induce apoptosis and expression of p53 target genes. In epidemiological studies, the P variant is associated with decreased cancer survival and increased risk of side-effects from genotoxic cancer treatment. Genotoxic therapy is still the mainstay of cancer treatment, and doxorubicin …

Investigating The Roles Of Δnp63 As A Suppressor Of Migration, Invasion, And Metastasis, Ramon E. Flores Gonzalez

Dissertations & Theses (Open Access)

Cancer is one of the leading causes of death and disease in the world. Considerable resources are spent to study and understand cancer, with the hope of developing new treatments and eventually cures that will help millions of people. Efforts to understand cancer are hindered by its inherent complexity and instability. Nonetheless, understanding the basics of tumor development and progression are the key to focused on studying the role of ΔNp63 in cancer, a p53 family member known to be involved in epithelial development, microRNA biogenesis, and stem cell maintenance. Using the strength of in vivo mouse models, we found …

Circumventing Cisplatin Resistance In Ovarian Cancers Through Reactivation Of P53 By Non-Cross-Resistant Platinum Analogs, Michelle Martinez-Rivera

Dissertations & Theses (Open Access)

Abstract

CIRCUMVENTING CISPLATIN RESISTANCE IN OVARIAN CANCERS THROUGH REACTIVATION OF P53 BY NON-CROSS-RESISTANT PLATINUM ANALOGS

Michelle Martinez-Rivera, B.S.

Advisory Professor: Zahid H. Siddik, Ph.D.

Cisplatin (cis-Pt), an anticancer platinum (Pt) drug, is used widely in the treatment of several malignancies, such as ovarian cancer. This Pt compound induces DNA damage, which results in p53 activation through post-translational modifications, mainly phosphorylation, culminating in execution of programmed cell-death. However, despite initial therapeutic response to cis-Pt, clinical resistance to this drug emerges leading to disease progression. Pt-resistance phenotypes have been associated with dysfunction in the p53 signaling pathway. Therefore, an effort to understand …

Investigating The Regulation And Function Of The Nr4a Nuclear Receptors In Cancer, Jordan A. Beard

Theses and Dissertations (ETD)

The nuclear receptor (NR) superfamily represents a structurally-conserved group of ligand-regulated transcription factors. These proteins have critical roles in various physiological and pathological processes, including cancer, and have been targets of drug therapy. The orphan NR subfamily 4A (NR4A), which includes the NR4A1 (Nur77), NR4A2 (Nurr1), and NR4A3 (Nor-1) genes, has been implicated in adult solid tumors and has been characterized as pro-tumorigenic mediator of cell proliferation, transformation, migration, and drug resistance. Alternatively, in leukemia, NR4A1 and NR4A3 have been described as tumor suppressors in hematologic malignancies. Members of the NR4A family are commonly overexpressed in cancer and this has …

Novel Cellular Targets Of Aspirin In Chemoprevention Studies On P53, G6pd And C-Myc, Guoqiang Ai

Electronic Theses and Dissertations

Background

Aspirin has generated a significant interest in recent years as a potential chemopreventive agent supported by strong evidence from epidemiological data; however, the mechanisms are not well understood. The objective of this dissertation is to identify novel cyclooxygenase (COX)-independent pathways by which aspirin exerts its anticancer effects in epithelial cancer cell lines. We investigated the effect of aspirin on p53, glucose 6-phosphate dehydrogenase (G6PD), and c-Myc, all of which are known to play a major role in cancer development. p53 is a tumor suppressor protein, often mutated in cancers causing its inactivation. Expression of G6PD is elevated in many …

Synthetic Lethality Of Cdk Inhibition And Doxorubicin In Triple-Negative Breast Cancer Requires P53 Inactivation, Natalie A. Jabbour-Leung

Dissertations & Theses (Open Access)

Triple-negative breast cancer (TNBC) is an aggressive malignancy in which the tumors lack expression of estrogen receptor, progesterone receptor and HER2. As such, TNBC patients cannot benefit from clinically available targeted therapies and must rely on chemotherapy and surgery for treatment. While initially responding well to chemotherapy, TNBC patients are at increased risk of developing distant metastasis and have decreased overall survival compared to non-TNBC patients. A majority of TNBC tumors carry p53 mutations, enabling them to bypass the G1 checkpoint and complete the cell cycle even in the presence of DNA damage. Therefore, we hypothesized that TNBC cells are …

Heat Stress: A Risk Factor For Skin Carcinogenesis, Leslie Calapre

Theses: Doctorates and Masters

BACKGROUND: The incidence of skin cancer in Australia has increased rapidly in the last few decades. Ultraviolet radiation (UV) is a major risk factor for skin carcinogenesis. UV, particularly the UVB spectrum, causes formation of cyclobutane pyrimidine dimers (CPD) in cellular DNA. Persistent and incorrectly repaired CPDs lead to DNA mutations and consequently, formation of cutaneous lesions. Interestingly, recent epidemiological studies have shown a significant increase in skin cancer incidence in geographical locations with high environmental temperatures. Thus, heat stress may potentiate the effects of UV exposure and act as an additional risk factor for skin cancer. Previous studies …

The Role Of Noxa/Mcl-1 In Head And Neck Squamous Cell Carcinoma (Hnscc) Treatment, June Young Lee

Theses and Dissertations

Head and neck cancer is the sixth leading type of cancer with 90 percent of head and neck cancer arising from squamous cell lining on the epithelium of the oral and nasal cavity, pharynx, and salivary gland. Even with tremendous achievements on chemotherapeutic drugs and therapies, the long-term prognosis of patients with advanced head and neck squamous cell carcinoma (HNSCC) has shown little improvement over the last three decades. Cisplatin is one of widely used chemotherapeutic drugs for multiple

cancers, including head and neck cancer, but the prolonged use of this drug is limited by its toxicity and by the …

Investigating Checkpoint Kinases 1/2 As Novel Therapeutic Targets In Head And Neck Squamous Cell Carcinoma, Mayur Arvind Gadhikar

Dissertations & Theses (Open Access)

Cisplatin, despite being the cornerstone chemotherapy for the treatment of head and neck squamous cell carcinoma (HNSCC), provides clinical benefits in just a subset of patients. This together with the lack of biomarkers predicting therapeutic responses, have led to unacceptably high rate of treatment failures in HNSCC. TP53 is the most frequently mutated gene in HNSCC, and the effect of p53 loss or mutation on cisplatin responses in HNSCC is poorly understood. In the current study, we hypothesized that HNSCC cells respond to cisplatin in a p53 dependent manner and unambiguously show that presence of wild-type TP53 (wtp53) confers sensitivity …

Targeting The Mdm2-P53 Axis For The Treatment Of Dedifferentiated Liposarcoma, Katelynn Bill

Dissertations & Theses (Open Access)

Dedifferentiated liposarcoma (DDLPS) is an aggressive malignancy characterized by a high rate of recurrence and dismal patient outcome. Minimal improvement in patient survival has been made in the last several decades, highlighting the crucial need for improved therapeutic strategies. A better understanding of the molecular deregulations underlying DDLPS would facilitate the discovery of improved therapeutic approaches. MDM2 is a well characterized oncoprotein and the most known negative regulator of p53. MDM2 amplification is considered the “hallmark” of DDLPS. Additionally, these tumors are known to harbor wild-type p53. We sought to take advantage of this knowledge and evaluate the role of …

Isolation And Characterization Of Multipotent Lung Stem Cells From P53 Mutant Mice Models, Venkat Sundar Gadepalli

Theses and Dissertations

Recent advances in understanding lung biology have shown evidence for the existence of resident lung stem cells. Independent studies in identifying and characterizing these somatic lung stem cells have shown the potential role of these cells in lung repair and regeneration. Understanding the functional characteristics of these tissue resident stem/progenitor cells has gained much importance with increasing evidence of cancer stem cells, cells in a tumor tissue with stem cell characteristics. Lung cancer is most commonly characterized by loss of p53 function which results in uncontrolled cell divisions. Incidence of p53 point mutations is highest in lung cancer, with a …

Therapeutic Efficacy Of P53 Restoration In Mdm2-Overexpressing Tumors, Qin Li

Dissertations & Theses (Open Access)

The TP53 tumor suppressor is the most mutated gene in human cancers. Recent studies using genetically modified mouse models have shown that restoring the expression of wild-type p53 has led to tumor growth suppression in various types of tumors lacking p53. Other mechanisms, e.g. upregulation of Mdm2 levels, exist in tumors to inactivate the p53 pathway. Mdm2, an E3 ubiquitin-ligase that targets p53 for proteasomal degradation, is present at high levels in many tumors with wild-type p53. In this study, we probed the effects of restoring p53 activity in Mdm2-overexpressing tumors genetically using animal models. Here we demonstrated high levels …

The Partial Characterization Of The 142r Protein Of Tanapox Virus, Krystal N. Seibert

Dissertations

Due to the complex nature of cancer, a variety of strategies are being employed to treat patients. Among these are oncolytic viruses that conditionally replicate in tumor cells with specific cellular landscapes. Several viruses including Herpesviruses, Adenoviruses, and Poxviruses, predominantly vaccinia virus (VV), have been explored for their oncolytic potential. Most of these viruses can productively infect a variety of cell types and it is one goal to create conditionally lethal viruses that can only replicate in tumor cells. Due to the prevalence of p53 inactivating mutations in cancers viruses that are restricted to p53 null cells are desirable and …

Cytotoxic Properties Of Novel Platinum Compounds, Bbr3610-Dach And Trans-4-Nbd In Tumor Cells: Cellular Effects Of 1, 2-Dach And Nbd Ligands, Vijay Menon

Theses and Dissertations

Platinum-based chemotherapeutics are used for the treatment of a wide range of cancers and a number of attempts have been made toward developing compounds with better cellular stability and similar or enhanced cytotoxicity as compared to their predecessors. The first part of the work reported here focuses on the cellular effects of the metabolically stable dinuclear platinum compound, BBR3610-DACH. Comet assay showed this compound to form interstrand crosslinks, a highly toxic DNA lesion in HCT116 cells, at equimolar concentrations to its parental compound, BBR3610. Cell cycle studies showed that BBR3610-DACH causes G1/S and G2/M cell cycle arrest with S phase …

Genome-Wide Profiling Unveils Criticial Functions Of P53 In Human Embryonic Stem Cells, Kadir C. Akdemir

Dissertations & Theses (Open Access)

Embryonic stem cells (ESCs) possess two unique characteristics: infinite self-renewal and the potential to differentiate into almost every cell type (pluripotency). Recently, global expression analyses of metastatic breast and lung cancers revealed an ESC-like expression program or signature, specifically for cancers that are mutant for p53 function. Surprisingly, although p53 is widely recognized as the guardian of the genome, due to its roles in cell cycle checkpoints, programmed cell death or senescence, relatively little is known about p53 functions in normal cells, especially in ESCs. My hypothesis is that p53 has specific transcription regulatory functions in human ESCs (hESCs) that …

A Study On The Function Of 14-3-3sigma In Regulating Cancer Energy Metabolism, Liem M. Phan, Liem M. Phan

Dissertations & Theses (Open Access)

Metabolic reprogramming has been shown to be a major cancer hallmark providing tumor cells with significant advantages for survival, proliferation, growth, metastasis and resistance against anti-cancer therapies. Glycolysis, glutaminolysis and mitochondrial biogenesis are among the most essential cancer metabolic alterations because these pathways provide cancer cells with not only energy but also crucial metabolites to support large-scale biosynthesis, rapid proliferation and tumorigenesis. In this study, we find that 14-3-3σ suppresses all these three metabolic processes by promoting the degradation of their main driver, c-Myc. In fact, 14-3-3s significantly enhances c-Myc poly-ubiquitination and subsequent degradation, reduces c-Myc transcriptional activity, and down-regulates …

Characterization Of Beryllium As A Novel Agent To Study Cell Cycle Arrest And Cellular Senescence, Priyatham Gorjala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cancer cells evade senescence, apoptosis, and other constraints on proliferation, often via mutation of the p53 tumor suppressor gene (TP53). Normal human lung fibroblasts have been shown to enter premature senescence upon exposure to beryllium. In these cells, BeSO₄ stabilizes p53 protein, increases p21 gene expression, induces senescence-associated β-galactosidase activity and causes cell proliferation arrest. In the present study, we have investigated whether BeSO₄ is able to induce similar effects in cancer cells that have wildtype p53. We have demonstrated that beryllium salt at low concentration can induce molecular changes in the p53 signaling pathway leading to cell …

Understanding The Roles Of Non-Homologous End Joining And P53 After Dna Damage, Omid Tavana

Dissertations & Theses (Open Access)

The inability to maintain genomic stability and control proliferation are hallmarks of many cancers, which become exacerbated in the presence of unrepaired DNA damage. Such genotoxic stresses trigger the p53 tumor suppressor network to activate transient cell cycle arrest allowing for DNA repair; if the damage is excessive or irreparable, apoptosis or cellular senescence is triggered. One of the major DNA repair pathway that mends DNA double strand breaks is non-homologous end joining (NHEJ). Abrogating the NHEJ pathway leads to an accumulation of DNA damage in the lymphoid system that triggers p53-mediated apoptosis; complete deletion of p53 in this system …

Dna Damage And Oxidative Stress Induced-P53 Activity In Astrocytes Causes Growth Arrest, Sarah A. Humphrey

Electronic Thesis and Dissertation Repository

An increasing body of evidence suggests that astrocytes play a key role in modulating neuronal fate during acute and chronic neurodegenerative conditions. Following CNS injury, an upregulation of p53 has been noted in both neurons and reactive astrocytes. p53 is an extremely important protein in determining cell fate decisions and its activation can result in the transcriptional induction of target genes that regulate apoptosis, autophagy, senescence and cell-cycle arrest. We found that p53 is upregulated in primary cortical astrocytes following oxidative stress and DNA damage and that this upregulation results in the p53-dependent transcriptional induction of several target genes involved …