Browsing by Subject "Disease Models, Animal"
Now showing 1 - 7 of 7
- Results Per Page
- Sort Options
Item FishATLAS: Assessment of Organotropism Determination Through Imaging Informatics of Xenografted Zebrafish(December 2021) Saucier, David Hamilton; Fiolka, Reto; Danuser, Gaudenz; Amatruda, James F.; Whitehurst, Angelique Wright; Brekken, Rolf A.; Mason, Ralph P.Ewing sarcoma patients with metastatic disease have a 5-year survival rate of approximately 28%. The hallmark of this disease is an aberrant transcription factor made by a fusion of Chromosomes 11 and 22 called EWSFLI1. EWSFLI1 expression levels have been correlated with differing responses in cell metastatic propensity, but much remains to be elucidated. Indeed, many current models fail to meet the statistical rigor that is needed for exceedingly spontaneous, rare events like metastasis. To address this need, FishATLAS utilizes zebrafish human cancer cell xenograft images after high fidelity registration using a novel diffeomorphic transformation to display metastatic hot spots of different cancer cell conditions to begin to grasp the deeper underpinnings of organotropism in vivo with individual cancers. Utilizing a suite of statistical tests, FishATLAS determines at a global whole-fish scale and the local microenvironment, if there are statistically different cell hotspots when comparing two or more different conditions. As it stands, data for EWSFLI1, its target SOX6, a non-transformed cell line NIH3T3, TC32 subclones, and melanoma cell lines have all shown unique distributions of metastatic hot spots. These findings serve as a tool for drug discovery and later environmental re-mapping in FishATLAS by allowing transgenic fish images (such as vasculature and lymphatics) to be overlayed onto any historical data set. These can then be used to determine a given microenvironment's contributions to secondary sites of metastasis. In the case of EWSFLI1 and its target SOX6, there was a marked difference upon shRNA-mediated knockdown that removed a population of hotspots in the upper somitic veins while some were persistent post genetic perturbation. SOX6 shRNA KD data indicates that the somite and inter-somitic arteries are more sensitive for metastatic colonization. Previous studies and our current accumulator data suggest these to be regions with higher oxidative stress, guiding insights for oxidative-mechanistic therapy. These and other conditional accumulations of sparse metastatic hotspots demonstrate the power of FishATLAS as a longitudinal assay of cellular and genetic conditions across all cancers.Item Investigating the Effects of Particle Radiation Exposure on Lung Carcinogenesis(2019-04-16) Luitel, Krishna; Shay, Jerry W.; Chen, Benjamin P.; Aroumougame, Asaithamby; Akbay, Esra A.Lung cancer accounts for more cancer-related deaths than any other cancer type among both men and women. The overall increase in radiation risk for human cancer types has been substantiated by the epidemiological data obtained from atomic bomb survivors and uranium mine workers. The lung has a large surface area which makes it a prominent target for radiation exposure making it susceptible to radiation-induced cancer. Recently particle radiation therapy such as the use of protons and carbon has increased in the treatment of cancer. The long-term biological effects of proton radiation remain less well characterized in terms of radiotherapy and well as for astronauts during deep space explorations. We compared the long-term side effects of proton radiation to equivalent doses of X-rays in the initiation and progression of premalignant lesions in a transgenic mouse lung cancer model (K-rasLA1). We show proton irradiation causes more complex DNA damage that is not completely repaired resulting in increased oxidative stress in the lungs both acutely and persistently. Proton irradiated mice had lower median survival and increased carcinoma incidence as compared to un-irradiated controls or X-ray exposed mice. Additionally, the space radiation environment consists of a wide variety of ion species with a various range of energies. To understand the effects of mixed ion beam radiation, we exposed K-rasLA-1 mice with three ion beams: Proton (H), Helium (He), and Silicon (Si) at a low dose rate of 0.5cGy/min. Using the three ion beams, we performed whole body irradiation in two different orders: 3B-1 (H-He-Si) and 3B-2 (Si-He-H) and used only H as a reference. We found that whole-body irradiation with 3B-1 increases the incidence of cancer initiation and systemic oxidative stress in mice 100 days post-irradiation compared to 3B-2 and H irradiation. Additionally, we saw an increase in adenomas with atypia and adenocarcinomas in 3B-1 irradiated mice but not in 3B-2 and H irradiated mice. We also found that a non-toxic anti-inflammatory, anti-oxidative radioprotector (CDDO-EA) reduced 3B-1 induced oxidative stress and cancer initiation almost back to baseline. Thus, exposure to 3B-1 elicits significant changes in lung cancer initiation that can be mitigated using CDDO-EA.Item Mechanisms Controlling Virulence Thresholds of Mixed Viral Populations and Identification of Novel Host Barriers to Poliovirus Neuropathogenesis(2012-07-20) Lancaster, Karen; Pfeiffer, Julie K.Neurotropic viruses comprise some of the worlds most widespread and deadly pathogens, including West Nile virus, rabies virus, and poliovirus. Poliovirus, as a model neurotropic virus, is also an RNA virus. RNA viruses have high mutation rates and a propensity to revert attenuating mutations, contributing to disease and complicating treatment and vaccine development. Despite worldwide epidemics in the early nineteenth century, paralysis from poliovirus is a rare event occurring in less than 1% of poliovirus infections. This suggests the presence of viral and host barriers limiting disease. Here we examined viral barriers by exploring the concept of virulence thresholds using mixtures of virulent and attenuated viruses in a transgenic mouse model of poliovirus infection. We determined that 1000-fold excess of an attenuated strain of poliovirus was protective against disease induced by the virulent strain. Protection was induced locally, was a poliovirus specific effect, and inactivated virus conferred protection. Treatment with a poliovirus receptor-blocking antibody phenocopied the protective effect of inactivated viruses in vitro and in vivo, suggesting virulence thresholds may be modulated by competition for viral receptor. Furthermore, we found the attenuated virus became virulent in immune-deficient mice due to enhanced replication and reversion of attenuating mutations. We also identified additional host barriers limiting pathogenesis using a novel hybridization-based viral diversity assay to quantify the efficiency of poliovirus transport from the periphery to the central nervous system. We found viral replication in peripheral axons is limited and the type I interferon response limits viral replication in peripheral tissues, protecting against disease. Significantly, we discovered that retrograde axonal transport of poliovirus in the sciatic nerve was inefficient and only 20% of viral pool members reaching the brain. The efficiency of viral transport increased upon muscle damage, leading to increased viral diversity and pathogenesis. In summary, we identified a viral induced mechanism controlling virulence of mixed viral populations, and characterized three host barriers that restrict poliovirus pathogenesis in the nervous system. The identification of these barriers restricting virulence may help explain the rare incidence of neurological complications following poliovirus infection and aid in our understanding of viral population dynamics and pathogenesis.Item Metabolomic Investigation of Melanoma Metastasis in a Patient-Derived Xenograft Mouse Model(2017-07-19) Shi, Xiaolei; Zhu, Hao; DeBerardinis, Ralph J.; Wang, Richard; Morrison, Sean J.; Davies, MichaelMetabolic reprogramming is considered a major factor in cellular transformation and tumor initiation, but whether or how metabolism supports tumor metastasis remains an open question. This study seeks to identify metabolic predictors of metastasis, with the rationale that understanding metabolic changes accompanying metastasis may lead to new therapies to prevent metastatic cancer. We used a set of patient-derived xenograft mouse models of melanoma, in which the metastatic potential of individual tumor lines correlated strongly with the history of metastasis in the patient donors. Six tumor lines with low metastatic potential (L-met) and nine with high metastatic potential (H-met) were implanted into several mice individually, then several fragments were isolated from each tumor, yielding a total of 182 individual tumor fragments for metabolomics. A tandem mass spectrometry (MS/MS)-based analytical platform was used to characterize 133 metabolites extracted from each tumor specimen. We then used a suite of statistical tools to identify metabolites differentiating H-met from L-met tumors. We identified durable metabolomic signatures correlating with molecular and biological features of the tumors. BRAF-mutant tumors had metabolomic and metabolic flux features of enhanced glycolysis compared to BRAF-wild type tumors. Tumors that metastasized efficiently from their primary sites had elevated levels of metabolites related to protein methylation, including trimethyllysine (TML). TML levels correlated with histone H3 trimethylation at lysines 9 and 27, and methylation at these sites was also enhanced in efficiently metastasizing tumors. Erasing either of these marks by genetically or pharmacologically silencing the histone methyltransferases SETDB1 or EZH2 had no effect on primary tumor growth but reduced cellular invasiveness, circulating tumor cell count and metastatic spread. Thus, metabolite profiling can uncover targetable epigenetic requirements for the metastasis of human melanoma cells.Item Mucosal HIV-1 Transmission in Humanized Mice(2008-05-13) Denton, Paul Wesley; Garcia-Martinez, J. VictorHIV-1 infects ~6,800 people each and every day, transmitting predominantly through unprotected sexual contact. On a global scale, vaginal transmission now accounts for more than half of newly acquired HIV-1 infections. In developed countries intrarectal infection represents a major form of HIV-1 transmission. The social and economic toll of this disease has created an urgency to develop and implement novel approaches capable of preventing HIV-1 transmission. Yet this process has been hindered by the lack of adequate small animal models for pre-clinical efficacy and safety testing. Given the importance of mucosal HIV-1 transmission, the susceptibility of humanized mice to intrarectal and intravaginal HIV-1 infection was investigated. Human lymphocytes, including CD4+ T cells, generated in situ from hematopoietic stem cells reconstitute the gastrointestinal tract and the female reproductive tract of Bone marrow Liver Thymus (BLT) mice. The presence of human CD4+ T cells in these mucosal tissues renders BLT mice susceptible to both intrarectal and intravaginal HIV-1 transmission. Mucosally transmitted HIV-1 disseminates systemically in BLT mice. Effects of disseminated HIV-1 infection include a systemic loss of CD4+ T cells, particularly in gut associated lymphoid tissue, which closely mimics what happens in HIV-1 patients. The utility of humanized mice to study mucosal HIV-1 transmission is particularly highlighted by the demonstration herein that pre-exposure prophylaxis with antiretroviral drugs can prevent intravaginal HIV-1 transmission. This experimental finding has important implications for the clinical implementation of antiretroviral-based pre-exposure prophylactic measures to prevent the spread of AIDS. The goal of this dissertation project was to determine the suitability of the BLT mouse to serve as an animal model of HIV-1 transmission and as a model for assessing interventions aimed at preventing HIV-1 transmission. My conclusions are that BLT mice are susceptible to both intrarectal and intravaginal HIV-1 transmission and that pre-exposure prophylaxis with FDA approved antiretroviral drugs does prevent vaginal transmission in BLT mice. Thus, the BLT mouse system is an excellent candidate for pre-clinical evaluation of both microbicides and pre-exposure prophylactic regimens to prevent mucosal HIV-1 transmission.Item A Mutation in Alk6b Causes Impaired Germ Cell Differentation and Testicular Germ Cell Tumors in Zebrafish(2010-11-02) Neumann, Joanie; Amatruda, James F.Germ cell tumors (GCTs) affect infants, children and young adults and are increasing in incidence worldwide. GCTs arise from pluripotent germ cells and can exhibit differentiated and undifferentiated histologies, which vary in their malignant potential and response to treatment. The pathways that determine tumor cell differentiation are not known, impeding the development of new therapies. Thus, the treatment of GCTs has remained static since the introduction 30 years ago of cisplatin which, while effective, causes severe side effects including hearing loss, infertility and kidney damage. We identified a zebrafish mutant line with a high incidence of GCT during a forward genetic screen to identify cancer susceptibility loci. Homozygous adult males develop tumors consisting of undifferentiated spermatogonia by 4 months of age while heterozygous males develop tumors around 7 to 9 months of age. We used interval haplotype analysis and high-resolution recombinational mapping to localize the mutation to a 0.82 cM interval on zebrafish chromosome 10. We identified a premature termination codon in Alk6b (Activin Receptor-like Kinase 6b) in the mutant animals. Alk6b is a member of the TGF-beta/BMP superfamily of receptors. BMP signaling has diverse roles including regulation of cell proliferation, differentiation, embryonic development, germ cell specification and gonadogenesis. Misregulation of the BMP signaling pathway has been implicated in various human cancers. In agreement with a critical role for Alk6b in controlling germ cell differentiation, we find evidence of impaired BMP signal transduction in the zebrafish GCTs, as well as evidence of alterations in the expression level of BMP target genes. We have also examined BMP signaling in a series of 40 clinically-annotated human GCTs of diverse histologic subtypes. In agreement with the predictions made from our zebrafish model, we find that undifferentiated GCTs such as dysgerminomas lack BMP signaling activity, whereas signaling is maintained in the differentiated subtype of Yolk Sac Tumors. These results confirm the relevance of the zebrafish model for understanding germ cell tumorigenesis, and will foster the development of improved, targeted therapy of human GCTs.Item Vulnerability and Resilience to Social Defeat: The Role of Neuroplasticity Within the Mesolimbic Dopamine Circuit(2010-05-14) Krishnan, Vaishnav; Nestler, Eric J.The pathophysiology of major depression and post-traumatic stress disorder are poorly understood. In particular, while stressful life events are an important cause of psychopathology, most individuals exposed to adversity maintain normal psychological functioning. The molecular mechanisms underlying this “resilience” are poorly understood. Here, we demonstrate that an inbred population of mice subjected to social defeat can be separated into susceptible and unsusceptible subpopulations which differ along several behavioral and physiological domains. Through a series of molecular and electrophysiological techniques, we identify signature adaptations within the mesolimbic dopamine circuit that are uniquely associated with vulnerability and, by a combination of viral-mediated gene transfer and genetic mouse models, we demonstrate how these adaptations are causally linked to a vulnerable phenotype. We also show that molecular recapitulations of adaptations associated with the unsusceptible phenotype are sufficient to promote resilient behavior. Our results validate a multidisciplinary approach to examine the neurobiological mechanisms of variations in stress resistance, and illustrate the importance of plasticity within the brain’s reward circuits in actively maintaining an emotional homeostasis.