Computational Biology Commons^™

Unique Transcriptional Profiles Underlie Osteosarcomagenesis Driven By Different P53 Mutants, Dhruv Chachad

Dissertations & Theses (Open Access)

Missense mutations in the DNA binding domain of the Trp53 gene are characterized as structural (p53R172H) or contact (p53R245W) mutations based on their effect on the conformation of the protein. These mutations show gain-of-function activities such as increased metastatic incidence as compared to p53 loss, often mediated by their interaction with a repertoire of transcription factors. These interactions are largely context specific. In order to understand the mechanisms by which these mutations drive osteosarcoma progression, we created a mouse model, wherein either the p53 structural mutant p53R172H, or the contact mutant, p53R245W, are expressed specifically in …

Reconstructing Mutational Lineages In Breast Cancer By Multi-Patient-Targeted Single Cell Dna Sequencing, Jake Leighton

Dissertations & Theses (Open Access)

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with high rates of metastasis and recurrence, where TNBC patients have a poor 5-year survival and ~50% are non-responsive to chemotherapy. Aneuploidy is a cancer hallmark that is pervasive in over 90% of breast cancer patients and is indicative of complex genomic rearrangements that are acquired during tumor initiation. Although copy number aberrations have been extensively studied in relation to aneuploidy and TNBC initiation, little is currently known regarding the timing and impact of single nucleotide variants (SNVs) contributing to these early transformative genomic events. Paramount to novel …

Development Of Graphical Models And Statistical Physics Motivated Approaches To Genomic Investigations, Yashwanth Lagisetty

Dissertations & Theses (Open Access)

Identifying genes involved in disease pathology has been a goal of genomic research since the early days of the field. However, as technology improves and the body of research grows, we are faced with more questions than answers. Among these is the pressing matter of our incomplete understanding of the genetic underpinnings of complex diseases. Many hypotheses offer explanations as to why direct and independent analyses of variants, as done in genome-wide association studies (GWAS), may not fully elucidate disease genetics. These range from pointing out flaws in statistical testing to invoking the complex dynamics of epigenetic processes. In the …

Decoding Copy Number Substructure And Evolution From Single Cell Genomics, Darlan Conterno Minussi

Dissertations & Theses (Open Access)

Aneuploidy is a prominent feature in Triple-Negative Breast Cancers (TNBC), however, the evolution of genotypes during tumor expansion remains poorly understood. The prevalent model of TNBC evolution is the Punctuated Copy Number Evolution (PCNE), in which tumors undergo a period of elevated genomic instability, acquiring complex genomic rearrangements within a short timeframe followed by clonal stasis. However, these observations rely on limited cell numbers and inherent experimental bias from first-generation single cell technologies. Therefore, the evolutionary trajectory after the punctuated burst remains unknown. To address this question, we sequenced 9,765 cells from 8 primary TNBCs and 6,413 cells from 4 …

Haplotype-Informed Allelic Imbalance Detection From Rna In Cancer, Zuhal Ozcan

Dissertations & Theses (Open Access)

Comprehensive genomic and transcriptomic characterization of tumors has uncovered enrichment for distinct aneuploidy and expression patterns, demonstrating the utility of molecular based classification of cancers and their subtypes. Existing cohorts with transcriptomic profiling from next-generation sequencing contain an untapped potential to also relate genomics with rich clinical phenotypes. Yet, derivation of somatic copy number and expression profiles from analyses of RNA has remained elusive. Further, DNA analysis in these cohorts is not always feasible due to limited tissue availability or financial constraints. Here, we present a statistical approach that overcomes these challenges using haplotype information to aid detection of somatic …

An Investigation Of Epigenetic Mechanisms Driving The Biology Of Head And Neck Squamous Cell Carcinoma, Scot Carson Callahan

Dissertations & Theses (Open Access)

Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer worldwide and is associated with significant morbidity and mortality. To date, the majority of work in the field has focused on genomic alterations such as mutations and copy number alterations. However, the clinical success of targeted therapies that exploit known genomic alterations, such as EGFR mutations, has remained mixed. Over the past decade, the importance of epigenetic regulators has come to the forefront, with the realization that many of these genes are mutated in cancer. Despite this realization, the role of epigenetics in regulating tumorigenesis, progression and …

Investigating The Ecology And Evolution Of Normal Breast Tissues And Breast Cancer With Single Cell Genomics, Tapsi Kumar, Tapsi Kumar

Dissertations & Theses (Open Access)

There is vast cellular heterogeneity in human breast tissues, with different transcriptional programs in the stromal, epithelial, and immune components, however, it remains unclear how their reprogramming and interplay leads to the progression of invasive phenotypes such as Triple- Negative Breast cancer (TNBC). To do define the microenvironmental alterations that occur during cancer, we first established a human breast cell atlas, a reference of normal breast cell types from disease free women. We profiled 535,941 cells from 62 women and 124,024 nuclei from 20 women revealing 11 major cell types and 52 cell states that reflect different biological functions that …

Computational Approaches To Understand Chemoresistance & Tumor Evolution Using Longitudinal Clinical Data And Lineage Tracing, Sahil Seth

Dissertations & Theses (Open Access)

Tumors are highly heterogeneous and dynamic, continually adapting and evolving in response to their microenvironment as well as external perturbations. Multi-region (spatial) and single cell sequencing has enabled us to anatomize the heterogeneity further and provide evidence of its association with chemo and drug resistance. To investigate this further we took two different approaches to understand the chemo-resistance, and functional heterogeneity in Triple negative breast cancer (TNBC) and Pancreatic ductal carcinoma in situ (PDAC) from an evolutionary perspective.

The first approach was to leverage tumor profiling from an ongoing randomized clinical trial in triple-negative breast cancer (ARTEMIS) to assess mechanisms …

Unveiling Global Roles Of G-Quadruplexes And G4-22 In Human Genetics, Ruth Barros De Paula

Dissertations & Theses (Open Access)

G-quadruplexes are non-B DNA structures formed by four or more runs of repeated guanines that confer unique features to living organism’s genomes. These sequences are enriched in regulatory regions, such as promoters and 5’ UTRs, and have distinct regulatory roles in both health and disease states. Even though previous studies showed the impact of G4 in gene expression, none of them summarized the location-specific effect of G4. Also, there is no broad understanding about the most common G4 repeat in the human genome, named here as G4-22, and how it links to the evolution of mammals and their biology. In …

Impact Of Intratumor Heterogeneity And The Tumor Microenvironment In Shaping Tumor Evolution And Response To Therapy, Akash Mitra

Dissertations & Theses (Open Access)

Intratumor heterogeneity (ITH) is a crucial challenge in cancer treatment. The genotypic and phenotypic heterogeneity underlying diverse cancer types leads to subclonal variation, which may result in mixed or failed response to therapy. The heterogeneity at the tumor level, along with the tumor microenvironment (TME), often shapes tumor evolution and ultimately clinical outcome. Given that modern treatment paradigms increasingly expose patients with metastatic disease to multiple treatment modalities through the course of their disease, there exists a need to characterize robust and predictive biomarkers of response to therapy. In order to accurately characterize tumor evolution, we need to account for …

Rare Variant Association Studies In Crohn’S Disease And Colorectal Cancer: Methods And Applications, Jiun-Sheng Chen

Dissertations & Theses (Open Access)

Genetic factors account for a substantial portion of Crohn’s disease and colorectal cancer (CRC) risk. Patients with Crohn’s disease, a condition that causes chronic inflammation of the gastrointestinal tract, are at increased risk of colorectal cancer morbidity and mortality. Genome-wide association studies using single marker approaches have identified loci responsible for these diseases, but disease susceptibility from rare variants is incompletely understood. This dissertation includes three chapters, two association studies for Crohn’s disease and CRC, and a statistical method to improve the power of statistical tests.

For Crohn’s disease, we performed targeted sequencing of 101 genes in 205 children with …

Computational Approaches To Delineate Transcriptional And Functional Heterogeneity In Pancreatic Cancer, Sanjana Srinivasan

Dissertations & Theses (Open Access)

Pancreatic ductal adenocarcinoma (PDAC) is an incurable disease characterized by poor survival, dense desmoplastic stroma and activating mutations in KRAS (>90%). These tumors are highly complex ecosystems composed of molecularly distinct sub-populations that exhibit a spectrum of genetic features and associated phenotypes. Despite recent advances in the transcriptomic characterization of PDAC into at least two tumor subtypes, this alone has been insufficient to define more specific patterns of oncogenic dependency. To fully leverage advancements in next generation sequencing and functional genomics, we have sought to establish computational methodologies to aid in refined target discovery, and to develop a novel …

Biases And Blind-Spots In Genome-Wide Crispr-Cas9 Knockout Screens, Merve Dede

Dissertations & Theses (Open Access)

Adaptation of the bacterial CRISPR-Cas9 system to mammalian cells revolutionized the field of functional genomics, enabling genome-scale genetic perturbations to study essential genes, whose loss of function results in a severe fitness defect. There are two types of essential genes in a cell. Core essential genes are absolutely required for growth and proliferation in every cell type. On the other hand, context-dependent essential genes become essential in an environmental or genetic context. The concept of context-dependent gene essentiality is particularly important in cancer, since killing cancer cells selectively without harming surrounding healthy tissue remains a major challenge. The toxicity of …

Investigation Of Proliferation Suppressors In Genetic Fitness Screens, Walter Frank Lenoir Iv

Dissertations & Theses (Open Access)

Innovation of CRISPR gene-editing technology has provided scientists genome manipulation tools that allowed rapid advancement of scientific capabilities and thus improved our ability to systematically study mammalian genetic functional profiles. Genome-wide CRISPR knockout screens conducted in collections of human cell lines can knock out genes at multiple loci, and have provided new insights into functional roles for independent genes. This method has launched massive efforts in looking across genetic backgrounds for context specific genetic vulnerabilities within cancer. Much of the research effort thus far has been spent on optimizing phenotype distinctions between essential, genes required for cell fitness, and non-essential, …

Decoding The Evolutionary Response To Prostate Cancer Therapy Using Plasma Genome Sequencing, Naveen Ramesh

Dissertations & Theses (Open Access)

Investigating genome evolution in response to therapy is difficult in human tissue samples due to the difficulty in accessing metastatic tumor sites and logistical challenges of collecting longitudinal samples. To overcome these issues, we developed an unbiased whole-genome plasma DNA sequencing approach called PEGASUS that concurrently measures genomic copy number and exome mutations from archival cryostored plasma samples. This approach was applied to study longitudinal blood plasma samples from prostate cancer patients. A molecular characterization of archival plasma DNA from 233 patients and genomic profiling of 101 patients identified clinical correlations of aneuploid plasma DNA profiles with poor survival, increased …

Identification Of Trim24 Domain Essentiality In Primary Trim24coe Carcinosarcoma Cell Lines, Cem Dede

Dissertations & Theses (Open Access)

Regulation of transcriptional control is a critical feature for organismal development and survival. Because of its effects on chromatin-controlled expression, disruptions of this delicately tuned mechanism are an important factor in development of tumorigenesis. Therefore, there is a growing interest in targeting these control mechanisms for their potential therapeutic values.

Our lab previously discovered the epigenetic regulator function of Tripartite motif protein 24 (TRIM24) through its H3K4me0 and H3K23ac dual histone signature reader function, its negative regulatory effect on the p53 tumor suppressor, in addition to its shown oncogenic driving capacity on immortalized mammary epithelial cells when overexpressed. Although TRIM24 …

Statistical Methods For Resolving Intratumor Heterogeneity With Single-Cell Dna Sequencing, Alexander Davis

Dissertations & Theses (Open Access)

Tumor cells have heterogeneous genotypes, which drives progression and treatment resistance. Such genetic intratumor heterogeneity plays a role in the process of clonal evolution that underlies tumor progression and treatment resistance. Single-cell DNA sequencing is a promising experimental method for studying intratumor heterogeneity, but brings unique statistical challenges in interpreting the resulting data. Researchers lack methods to determine whether sufficiently many cells have been sampled from a tumor. In addition, there are no proven computational methods for determining the ploidy of a cell, a necessary step in the determination of copy number. In this work, software for calculating probabilities from …

Molecular Consequences Of High Taz Expression In Gliomas, Visweswaran Ravikumar

Dissertations & Theses (Open Access)

Diffuse high grade gliomas are complex and lethal neoplasms of the adult central nervous system that are driven by a range of genetic and epigenetic alterations. Molecular classification of these tumors has identified different transcriptional subtypes, the most notable being Proneural (PN) and Mesenchymal (MES) classes. The most aggressive forms of the disease have a Mesenchymal expression signature, with reported PN-to-MES transition occurring with tumor progression. Master regulatory analysis has identified the transcriptional co-activator TAZ (WWTR1) as a major driver of the MES transition. Overexpression of this single protein in glioma stem cells has been shown to drive a transition …

Computational Genomic Models For Spatio-Temporal Investigation Of Early Lung Cancer Pathology, Smruthy Sivakumar

Dissertations & Theses (Open Access)

Lung cancer, of which non-small cell lung cancer (NSCLC) is the most common form, is the second most prevalent cancer and the leading cause of cancer-related deaths. NSCLCs primarily comprise adenocarcinomas (LUAD) and squamous cell carcinomas (LUSC). Advances in early detection and prevention have been limited by the lack of early-stage biomarkers and targets. A comprehensive molecular characterization of premalignant lesions and tumor-adjacent normal tissue can aid in better understanding NSCLC pathogenesis. However, these investigations are further challenged by limited tissue availability and low cellular fractions of detectable somatic mutations.

Therefore, there is a dearth of knowledge about the pathogenesis …

Improving Dbnsfp, Mingyao Lu

Dissertations & Theses (Open Access)

IMPROVING dbNSFP

Mingyao Lu, B.S.

Advisory Professor: Xiaoming Liu, Ph.D.

The analysis and interpretation of DNA variation are very important for the Whole Exome studies (WES). Genome research has focused on single nucleotide variants (SNVs). Since indels are as important as SNVs, especially indels in coding regions are often candidates of disease-causing variants, thus, it is necessary to expand the focus to include indel mutations.

The goal of my project is to provide an automatic annotation pipeline to the WES based disease studies project by extending the dbNSFP with a tool for automated indel annotation and deleteriousness prediction. The current …

Integrative Cancer Immunogenomic Analysis Of Serial Melanoma Biopsies Reveals Correlates Of Response And Resistance To Sequential Ctla-4 And Pd-1 Blockade Treatment, Whijae Roh

Dissertations & Theses (Open Access)

Melanoma is the most malignant form of skin cancer. The five-year survival rate for metastatic melanoma is 19.9%. Although targeted therapy of BRAF and MEK inhibitors were developed for melanoma, resistance to therapy is inevitable. Immune checkpoint blockade, which reverses the suppression of the immune system, on the other hand, has shown a durable response in 20-30% of patients with metastatic melanoma. However, more predictive and robust biomarkers of response to this therapy are still needed, and resistance mechanisms remain incompletely understood. To address this, we examined a cohort of metastatic melanoma patients treated with sequential checkpoint blockade against cytotoxic …

Statistical Methods For Two Problems In Cancer Research: Analysis Of Rna-Seq Data From Archival Samples And Characterization Of Onset Of Multiple Primary Cancers, Jialu Li

Dissertations & Theses (Open Access)

My dissertation is focused on quantitative methodology development and application for two important topics in translational and clinical cancer research.

The first topic was motivated by the challenge of applying transcriptome sequencing (RNA-seq) to formalin-fixation and paraffin-embedding (FFPE) tumor samples for reliable diagnostic development. We designed a biospecimen study to directly compare gene expression results from different protocols to prepare libraries for RNA-seq from human breast cancer tissues, with randomization to fresh-frozen (FF) or FFPE conditions. To comprehensively evaluate the FFPE RNA-seq data quality for expression profiling, we developed multiple computational methods for assessment, such as the uniformity and continuity …

Development Of An In Silico Kir Genotyping Algorithm And Its Application To Population And Cancer Immunogenetic Analyses, Howard Rosoff

Dissertations & Theses (Open Access)

Gene content determination and variant calling in the complex KIR genomic region are useful for immune system function analysis, pathogenesis and disease risk factor elucidation, immunotherapy development, evolutionary investigations, and human migration modeling. Sequence-specific oligonucleotide and sequence-specific primer PCR methods are the de facto standards for KIR presence/absence identification, but the current platforms are unsuitable for SNP calling, impractical for KIR typing large cohorts of DNA samples, and inapplicable for typing repositories in which sequence data, but not cells or cell analytes, are available. Alternative typing methods, such as in silico sequence-based typing, can address the problems associated with amplicon-based …

Accurate Mutation Annotation And Functional Prediction Enhance The Applicability Of -Omics Data In Precision Medicine, Tenghui Chen

Dissertations & Theses (Open Access)

Clinical sequencing has been recognized as an effective approach for enhancing the accuracy and efficiency of cancer patient management and therefore achieve the goals of personalized therapy. However, the accuracy of large scale sequencing data in clinics has been constrained by many different aspects, such as clinical detection, annotation and interpretation of the variants that are observed in clinical sequencing data. In my Ph.D thesis work, I mainly investigated how to comprehensively and efficiently apply high dimensional -omics data to enhance the capability of precision cancer medicine. Following this motivation, my dissertation has been focused on two important topics in …

Investigating Metastatic Lineage In Colorectal Cancer By Single Cell Dna Sequencing, Marco Leung

Dissertations & Theses (Open Access)

Metastasis is the primary cause of human cancer deaths. Patients with metastatic colorectal cancer (mCRC) show only an 11% 5-year survival rate, compared to those without local or distant metastases (92% 5-year survival rate). Understanding the CRC tumor evolution may provide valuable insights on how to improve treatment in patients with mCRC. However, the genomic basis of metastasis has been difficult to study, in part due to the extensive intratumor heterogeneity at both the primary and metastatic tumor sites, and the low frequency of subclones with metastatic potential. Previous studies have applied conventional bulk next-generation sequencing (NGS) methods, which have …

Functional Analysis Of Synthetic Gene Circuits Controlling A Protein Pump In Yeast, Junchen Diao

Dissertations & Theses (Open Access)

Synthetic biology aims to build biological devices to understand living systems and explore new applications. Synthetic gene circuits such as genetic switches, oscillators and logic gates are at the core of many synthetic biology applications. These gene circuits often include a sensor/regulator protein capable to detect small molecules and then transduce them into a regulatory signal to generate measurable output. Similar signal transduction networks are also abundant in nature. However, in many natural and engineered scenarios, the output also affects the regulator/sensor protein. How such interactions between the regulator/sensor and the output affect synthetic gene circuit function has not been …

Investigation Of Genetic Alterations In Emt Suppressor, Dear1, Through Pan-Cancer Analysis And Ultra-Deep Targeted Sequencing In Ductal Carcinoma In Situ, Jacquelyn Reuther

Dissertations & Theses (Open Access)

Ductal carcinoma in situ (DCIS) is thought to be one of the earliest pre-invasive form of and non-obligate precursor to invasive ductal carcinoma (IDC). There is an urgent need to identify predictive and prognostic biomarkers for breast cancers with a heightened risk of progression from DCIS to IDC. Our laboratory has previously discovered a novel TRIM family member, DEAR1 (Ductal Epithelium Associated Ring Chromosome 1, annotated as TRIM62) within chromosome 1p35.1, that is mutated and homozygously deleted in breast cancer and whose expression is downregulated/lost in DCIS. Previous work has shown that DEAR1 is a novel tumor suppressor …

Genetics Of Obesity In Starr County, Texas Mexican Americans, Heather M. Highland

Dissertations & Theses (Open Access)

Currently, over two-thirds of Americans are classified as over-weight or obese. Obesity increases risk for many other diseases including type 2 diabetes, heart disease, stroke, and cancer, making obesity the largest public health problem in America and most other Westernized nations. Hispanics have a higher rate of both obesity and type 2 diabetes, making them a particularly interesting population in which to study obesity. For the last 33 years, the Starr County Health Studies has collected an array of phenotypes and biological samples from residents of Starr County, along Texas-Mexico border. This study includes 825 subjects who were not known …

Genomic Characterization Of Polyps In Familial Adenomatous Polyposis Patients And Identification Of Candidate Chemopreventive Drugs, Francis A. San Lucas

Dissertations & Theses (Open Access)

Familial adenomatous polyposis (FAP) is an autosomal dominant disease characterized by APC germline mutations and the development of hundreds to thousands of premalignant adenomas in the gastrointestinal tract at a young age. If left untreated, these patients inevitably develop colon cancer (CRC) and small bowel tumors. We performed exome sequencing of samples from 12 FAP patients to characterize adenomas and to identify candidate genes of adenoma development that may serve as potential targets for chemoprevention drug development. From each patient, a blood and at least one polyp were sequenced with a total of 25 polyps analyzed. In some cases, normal …

The Association Between The Il-1 Pathway, Isaac C. Wun

Dissertations & Theses (Open Access)

Cutaneous malignant melanoma (CMM) is a potentially lethal malignancy that warrants attention and further research, as it is known to that there is an increasing rate of incidence in theUnited States, and it is also known that exposure to UV light is its most crucial risk factor, and family history of melanoma is also an important risk factor. Melanoma is an aggressive and lethal cancer in humans. There are an estimated new 132,000 melanoma cases annually worldwide, and the trend has doubled in the past 20 years. However, attempts to treat melanoma have encountered considerable resistance and remained ineffective. The …