Identifying individuals at-risk of developing oesophageal adenocarcinoma through symptom, risk factor and salivary biomarker analysis

Background: Oesophageal adenocarcinoma (OAC) carries a grave prognosis. Existing early detection strategies are flawed predominately because of reliance upon symptoms known to occur late when the disease is often incurable. Detection of individuals with Barrett’s Oesophagus (BO), a known pre-malignant condition, is problematic and the vast majority will not develop OAC. Aim: To explore novel methods of identifying patients with or at risk of OAC through machine learning (ML) techniques and biomarker identification. Materials and Methods: Initial work utilised novel ML on two existing patient symptom and risk factor questionnaire datasets. Additionally, targeted expression analysis was performed to establish whether transcriptomic biomarkers were present in blood and saliva of affected patients. Optimal RNA extraction techniques and saliva collection strategies for sufficient quality and quantity RNA were determined. Whole mRNA sequencing was performed on patient salivary RNA to identify biomarkers for future assessment. Epigenetic analysis was performed on salivary DNA to identify biomarkers. ML techniques analysed these data to derive a risk prediction tool. Results: ML techniques on questionnaire data produced satisfactory sensitivity (90%), but accuracy not appropriate for population screening (AUC 0.77). Blood and saliva extraction and collection methods were established and samples found to contain biomarkers. Targeted transcriptomic expression analysis demonstrated 12 / 22 tested genes were significantly aberrantly expressed in patients. 5 genes, combined with 6 questionnaire data-points, identified those with or at risk of OAC 93% sensitivity, AUC 0.88. Whole mRNA sequencing identified a further 134 genes implicated in OAC pathogenesis requiring future testing. Epigenetic analysis found 25 differentially methylated regions, when combined, identified those with or at risk of OAC to 99.9% accuracy. 5 Conclusion: Utilisation of salivary biomarkers is a potentially effective means to identify individuals with or at risk of OAC. Further work exploring transcriptomic and epigenetic data established in this thesis should be performed

Incorporating Deep Learning Techniques into Outcome Modeling in Non-Small Cell Lung Cancer Patients after Radiation Therapy

Radiation therapy (radiotherapy) together with surgery, chemotherapy, and immunotherapy are common modalities in cancer treatment. In radiotherapy, patients are given high doses of ionizing radiation which is aimed at killing cancer cells and shrinking tumors. Conventional radiotherapy usually gives a standard prescription to all the patients, however, as patients are likely to have heterogeneous responses to the treatment due to multiple prognostic factors, personalization of radiotherapy treatment is desirable. Outcome models can serve as clinical decision-making support tools in the personalized treatment, helping evaluate patients’ treatment options before the treatment or during fractionated treatment. It can further provide insights into designing of new clinical protocols. In the outcome modeling, two indices including tumor control probability (TCP) and normal tissue complication probability (NTCP) are usually investigated. Current outcome models, e.g., analytical models and data-driven models, either fail to take into account complex interactions between physical and biological variables or require complicated feature selection procedures. Therefore, in our studies, deep learning (DL) techniques are incorporated into outcome modeling for prediction of local control (LC), which is TCP in our case, and radiation pneumonitis (RP), which is NTCP in our case, in non-small-cell lung cancer (NSCLC) patients after radiotherapy. These techniques can improve the prediction performance of outcomes and simplify model development procedures. Additionally, longitudinal data association, actuarial prediction, and multi-endpoints prediction are considered in our models. These were carried out in 3 consecutive studies. In the first study, a composite architecture consisting of variational auto-encoder (VAE) and multi-layer perceptron (MLP) was investigated and applied to RP prediction. The architecture enabled the simultaneous dimensionality reduction and prediction. The novel VAE-MLP joint architecture with area under receiver operative characteristics (ROC) curve (AUC) [95% CIs] 0.781 [0.737-0.808] outperformed a strategy which involves separate VAEs and classifiers (AUC 0.624 [ 0.577-0.658]). In the second study, composite architectures consisted of 1D convolutional layer/ locally-connected layer and MLP that took into account longitudinal associations were applied to predict LC. Composite architectures convolutional neural network (CNN)-MLP that can model both longitudinal and non-longitudinal data yielded an AUC 0.832 [ 0.807-0.841]. While plain MLP only yielded an AUC 0.785 [CI: 0.752-0.792] in LC control prediction. In the third study, rather than binary classification, time-to-event information was also incorporated for actuarial prediction. DL architectures ADNN-DVH which consider dosimetric information, ADNN-com which further combined biological and imaging data, and ADNN-com-joint which realized multi-endpoints prediction were investigated. Analytical models were also conducted for comparison purposes. Among all the models, ADNN-com-joint performed the best, yielding c-indexes of 0.705 [0.676-0.734] for RP2, 0.740 [0.714-0.765] for LC and an AU-FROC 0.720 [0.671-0.801] for joint prediction. The performance of proposed models was also tested on a cohort of newly-treated patients and multi-institutional RTOG0617 datasets. These studies taken together indicate that DL techniques can be utilized to improve the performance of outcome models and potentially provide guidance to physicians during decision making. Specifically, a VAE-MLP joint architectures can realize simultaneous dimensionality reduction and prediction, boosting the performance of conventional outcome models. A 1D CNN-MLP joint architecture can utilize temporal-associated variables generated during the span of radiotherapy. A DL model ADNN-com-joint can realize multi-endpoint prediction, which allows considering competing risk factors. All of those contribute to a step toward enabling outcome models as real clinical decision support tools.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162923/1/sunan_1.pd

Tumor Suppressor Genes

Functional evidence obtained from somatic cell fusion studies indicated that a group of genes from normal cells might replace or correct a defective function of cancer cells. Tumorigenesis that could be initiated by two mutations was established by the analysis of hereditary retinoblastoma, which led to the eventual cloning of RB1 gene. The two-hit hypothesis helped isolate many tumor suppressor genes (TSG) since then. More recently, the roles of haploinsufficiency, epigenetic control, and gene dosage effects in some TSGs, such as P53, P16 and PTEN, have been studied extensively. It is now widely recognized that deregulation of growth control is one of the major hallmarks of cancer biological capabilities, and TSGs play critical roles in many cellular activities through signaling transduction networks. This book is an excellent review of current understanding of TSGs, and indicates that the accumulated TSG knowledge has opened a new frontier for cancer therapies

Algorithms and Applications for non-coding RNAs in Aging

Gene expression is a complex molecular process governing fate and function of most eukaryotic cells. The fundamental mechanism, namely that genetic material of a cell is compactly stored on chromosomal DNA and at times being transcribed into messenger-RNA to facilitate on-demand protein biosynthesis, is widely known. However, the interplay of biochemical regulatory pathways underlying an individual’s disease phenotype development remains incompletely understood. Intriguingly, the ∼ 20.000 protein-coding genes only account for 2% of the human genome, triggering profound questions on the purpose of remaining segments. In recent years it became apparent that non-coding RNAs essentially tune the observed gene expression circuits. In particular the small non-coding RNAs such as microRNAs, turned out to be regulatory players by switching on and off protein translation of target messenger-RNAs. Several thousand mammalian microRNAs have been discovered so far but little is known about their impact on the transcriptome, which likely depends on contextual variables like cell type identity, cellular and tissue environment or phase of activation. Previous efforts demonstrated that gene expression programs in human and mouse undergo gradual changes along the life trajectory with amplification at higher ages. In parallel, age-related diseases are currently accumulating in our globally aging population, posing a serious challenge to our society and healthcare systems. Neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease show steadily rising incidence rates with several million people already affected. Both are caused by pathological protein accumulation in selectively vulnerable neurons and brain regions. Notably, these neurological disorders do not appear all of a sudden in an individual but are believed to originate after long asymptomatic phases of subtle aberrant changes on the cellular level, turning early diagnosis into an intricate affair. Yet, no single comprehensive model to explain aging associated changes in gene expression exists and certainly any such model must take into account the role of microRNAs and other important non-coding RNAs. With the advent of ultra-high-throughput sequencing techniques and unprecedented computational power, the screening of microRNAs and their targets from human biofluids and tissues became not only affordable but scalable. To deal with the increasing complexity of molecular studies, novel bioinformatics-driven approaches are needed to generate reproducible and comprehensive conclusions from large-scale data sets. Here, the role of small non-coding RNAs in governing gene expression changes observed in complex age-related diseases is explored with the aid of new methods and databases as well as several thousand RNA profiling samples. This cumulative doctoral thesis comprises eight peer-reviewed publications. Basic research covers a comprehensive review on most target prediction tools and a novel experimental and computational workflow for microRNA-target pathway identification. In addition, with miRPathDB 2.0 the so-far largest database on enriched microRNA pathways for human and mouse is presented. Moreover, the new versatile web tool miEAA 2.0 allows rapid annotation of statistically enriched molecular properties and functions for large lists of microRNAs from ten species. The lessons learned from web-based tool development were condensed in an invited summary and survey article on scientific web server availability along with best practices for developers. The here presented toolkit was used in three applied research studies to investigate the association between microRNAs and their target pathways in the context of aging as well as the to date largest Parkinson’s disease biomarker discovery framework. Circulating microRNAs obtained low-invasively from whole-blood samples bear diagnostic and prognostic value in Alzheimer’s and Parkinson’s disease patients, which was discovered using machine learning models. Furthermore, selected microRNA families were found to systematically target entire signaling pathways as to effectively silence gene expression. Indeed, these pathways are affected in prevalent neurodegenerative disorders. Taken together, the published candidate signatures and validated targets are pivotal for subsequent experimental perturbation in microRNA or gene knockout studies. In future efforts, large-scale single-cell studies will be required to further dissect disease and cell-type specificity of aging disease biomarker candidates and their long-term effect on gene expression, possibly indicating early neuropathological hallmarks.Genexpression ist ein komplexer molekularer Prozess, der das Überleben und die Funktion der meisten eukaryotischen Zellen entscheidend beeinflusst. Der zugrunde liegende Mechanismus, nämlich, dass das genetische Material einer Zelle kompakt in chromosomaler DNA vorliegt und je nach Bedarf in messenger-RNA zur Proteinbiosynthese genutzt wird, ist weitgehend bekannt. Allerdings ist das Zusammenspiel der regulatorischen Pfade im Hintergrund der phenotypischen Veränderungen von erkrankten Individuen nur wenig verstanden. Interessanterweise machen die fast 20.000 protein-kodierenden Gene nur in etwa 2% des menschlichen Erbgutes aus. In den letzten Jahren hat man festgestellt, dass nicht-kodierende RNAs eine essentielle Rolle bei der Einstellung der beobachteten Genexpressionsschaltkreise spielen. Insbesondere kleine nicht-kodierende RNAs wie microRNAs, stellten sich als zuvor unterschätzte regulatorische Einheiten heraus, die die Translation von Ziel-messenger-RNA in Proteine an und ausschalten. Mehrere tausend microRNAs wurden bisher bei Säugetieren entdeckt, trotzdem ist immer noch wenig über ihren Einfluss auf das Transkriptom bekannt, ein Zusammenhang der wahrscheinlich vom Kontext wie Zelltypidentität, dem zelluären Umfeld sowie dem umgebenden Gewebe, und den Aktivierungsphasen abhängt. Frühere Forschungsarbeiten haben bereits gezeigt, dass das Genexpressionsprogramm im Menschen und in der Maus sukzessiven Änderungen im Laufe des Lebens unterworfen ist, welche sich im höheren Alter verstärken. Zur gleichen Zeit akkumulieren Fälle von altersbedingten Krankheiten in unserer immer älter werdenden, globalen Population, was ernstzunehmende Herausforderungen für unsere Gesellschaft sowie unser Gesundheitssystem mit sich bringt. Neurodegenerative Krankheiten wie Morbus Alzheimer und Morbus Parkinson zeigen eine kontinuierlich ansteigende Inzidenz, wobei bereits mehrere millionen Menschen weltweit betroffen sind. Besonders für diese Krankheiten ist, dass sie bei einem Menschen nicht spontan oder plötzlich entstehen, sondern vermutlich nach langer Zeit der asymptomatischen Phase aufgrund schleichender, abnormaler Veränderungen auf zellulärer Ebene entstehen, was eine frühe Diagnose überaus schwierig gestaltet. Bisher existiert noch kein verständliches Modell das die altersassoziierten Veränderungen der Genexpression erklären kann, wobei jedes darauf ausgerichtete Modell mit Bestimmtheit die Rolle der microRNAs und anderen wichtigen nicht-kodierenden RNAs zwangsläufig in Betracht ziehen muss. Mit dem Aufkommen der Sequenzierung im Ultrahochdurchsatzverfahren und der unübertroffenen Leistung moderner Computersysteme, wurde die Untersuchung von microRNAs und ihren Zielgenen anhand von Proben menschlicher Flüssigkeiten und Geweben nicht nur möglich gemacht, sondern kann entsprechend hochskaliert werden. Um mit der zunehmenden Komplexität molekularer Studien Schritt zu halten, braucht es neue Ansätze der Bioinformatik um reproduzierbare und nachvollziehbare Schlüsse aus großen Datensätzen gewinnen zu können. Im Rahmen dieser Arbeit wurden kleine nicht-kodierende RNAs hinsichtlich ihrer Rolle der Genregulation in komplexen altersbedingten Krankheiten anhand neuer Methoden und Datenbanken sowie mehreren tausend Proben der RNA-Sequenzierung untersucht. Diese kumulative Dissertationsarbeit umfasst acht von unabhängigen Experten begutachtete (peer-reviewed), wissenschaftliche Publikationen. Die Grundlagenforschung enthält einen umfassenden Übersichtsartikel zu fast allen Methoden der Vorhersage von microRNA Zielgenen sowie ein neuartiges Protokoll bestehend aus Labormethoden und computergestützen Berechnungen zur Identifikation von durch microRNAs regulierte Genpfade. Zusätzlich wird mit miRPathDB 2.0 die bisher größte Datenbank zu signifikant angereicherten microRNA Zielpfaden präsentiert. Des Weiteren, bietet die neue und vielseitige, web-basierte Software miEAA 2.0 die Möglichkeit der rasanten Annotation statistisch angereicherter, molekularer Eigenschaften sowie bekannter Funktionen einer gegebenen Liste an microRNAs von zehn Spezies. Die durch web-basierte Softwareentwicklung zuvor angelernten Fähigkeiten sowie daraus resultierende Empfehlungen für nachfolgende Entwickler wurden kurz und bündig in einem eingeladenen Übersichtsartikel zum Thema Verfügbarkeit wissenschaftlicher Software im Internet veröffentlicht. Die hier präsentierten Werkzeuge wurden gezielt in drei Studien zur angewandten Forschung genutzt um die Assoziation zwischen microRNAs und ihren Zielpfaden im Kontext der allgemeinen Altersforschung sowie im Rahmen der bisher größten Studie zur Entdeckung von Biomarkern der Parkinson Krankheit zu untersuchen. Im Blutkreislauf zirkulierende microRNAs, die anhand von Vollblutproben extrahiert wurden, zeigen diagnostisches und prognostisches Potential bei Alzheimer und Parkinson Patienten, was mit Methoden des maschinellen Lernens entdeckt werden konnte. Überdies konnte herausgefunden werden, dass bestimmte microRNA Familien systematisch Signalwege blockieren können, um die Genexpression herunterzufahren. Tatsächlich sind diese Pfade auch in neurodegenerativen Krankheiten betroffen. Insgesamt sind die hier publizierten Signaturen von Kandidaten-microRNAs und einiger validierter Zielgene herausragend dazu geeignet in weiteren Studien anhand von gezielter Ausschaltung im Labor genauer untersucht zu werden. In zukünftigen Forschungsprojekten sollten groß angelegte Untersuchungen vieler einzelner Zellen im Vordergrund stehen, um zu verstehen wie spezifisch für Krankheit oder Zelltyp die hier genannten Biomarker-Kandidaten für altersbedingte Krankheiten sind. Auch wird es wichtig sein die Langzeiteffekte von dysregulierten microRNAs auf die Genexpression zu verstehen, die möglicherweise frühzeitig neuropathologische Kennzeichen widerspiegeln

Computational analysis of multi-omic data for the elucidation of molecular mechanisms of neuroblastoma

Doctor ScientiaeNeuroblastoma is the most common extracranial solid tumor in childhood. The survival rates of patients with neuroblastoma, especially those in the high-risk category, are still low despite varied therapies. The detailed understanding of the molecular mechanisms underlying the pathogenesis of neuroblastoma is essential to develop better therapeutics and improve the poor survival rates. This study provides a multi-omic analysis of neuroblastoma datasets from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) neuroblastoma project and the Gene Expression Omnibus (GEO) data portals to better understand the molecular mechanisms of neuroblastoma

Expression levels of blood microRNAs as biomarker of cognitive decline due to Alzheimer's disease

Studies investigating differential miRNAs expression levels in patients with Alzheimer’s disease (AD) abounded in the last decades and catalysed the interest towards miRNAs as novel non-invasive biomarkers of AD. Chapter 1 provides an overview of AD’s pathogenesis, discusses the evolution of the disease’s definition, and introduces miRNAs. In Chapter 2, a systematic review and a P-value based meta-analysis of 107 studies investigate miRNA expression levels in AD patients. This leads to a prioritisation of 25, 32 and 5 dysregulated miRNAs at study-wide significance in the brain, the blood and the cerebrospinal fluid (CSF) of AD patients, respectively. A pathway enrichment analysis for the top dysregulated miRNAs in the brain confirms their role in regulating biological functions implicated in AD. In Chapter 3, expression levels of the 32 dysregulated miRNAs in the blood and 6 top dysregulated miRNAs in the brain of AD patients, are assessed using real-time quantitative polymerase chain reaction in the blood of cognitively healthy individuals from the CHARIOT-PRO cohort. Low performers on the total Repeatable Battery for the Assessment of Neuropsychological Status scale show downregulation of six miRNAs (hsa-miR-128-3p, hsa-miR-144-5p, hsa-miR-146a-5p, hsa-miR-26a-5p, hsa-miR-29c-3p and hsa-miR-363-3p). Pathway enrichment analysis highlights involvement in pathways initiating early pathogenetic changes in AD. Finally, in chapter 4, whole-genome sequencing data from the Alzheimer’s Disease Neuroimaging Initiative is used to perform an association analysis between polymorphisms within the six miRNAs’ genes and CSF biomarkers of neurodegeneration. A functional annotation of significant variants highlights expression quantitative trait loci, location in enhancer regions and alterations in the binding sites of transcription factors regulating neuronal function. The association of variants located within the same miRNA gene with different markers of neurodegeneration reveals a positive correlation between members of the amyloid cascade and microglial activation in the CSF. The final chapter highlights the clinical relevance of these findings and discusses future perspectives.Open Acces

Integration of Genome Scale Data for Identifying New Biomarkers in Colon Cancer: Integrated Analysis of Transcriptomics and Epigenomics Data from High Throughput Technologies in Order to Identifying New Biomarkers Genes for Personalised Targeted Therapies for Patients Suffering from Colon Cancer

Colorectal cancer is the third most common cancer and the leading cause of cancer deaths in Western industrialised countries. Despite recent advances in the screening, diagnosis, and treatment of colorectal cancer, an estimated 608,000 people die every year due to colon cancer. Our current knowledge of colorectal carcinogenesis indicates a multifactorial and multi-step process that involves various genetic alterations and several biological pathways. The identification of molecular markers with early diagnostic and precise clinical outcome in colon cancer is a challenging task because of tumour heterogeneity. This Ph.D.-thesis presents the molecular and cellular mechanisms leading to colorectal cancer. A systematical review of the literature is conducted on Microarray Gene expression profiling, gene ontology enrichment analysis, microRNA and system Biology and various bioinformatics tools. We aimed this study to stratify a colon tumour into molecular distinct subtypes, identification of novel diagnostic targets and prediction of reliable prognostic signatures for clinical practice using microarray expression datasets. We performed an integrated analysis of gene expression data based on genetic, epigenetic and extensive clinical information using unsupervised learning, correlation and functional network analysis. As results, we identified 267-gene and 124-gene signatures that can distinguish normal, primary and metastatic tissues, and also involved in important regulatory functions such as immune-response, lipid metabolism and peroxisome proliferator-activated receptors (PPARs) signalling pathways. For the first time, we also identify miRNAs that can differentiate between primary colon from metastatic and a prognostic signature of grade and stage levels, which can be a major contributor to complex transcriptional phenotypes in a colon tumour