Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.736094
Title: The role of ASPP2 in intestinal homeostasis and tumourigenesis
Author: Qin, Xiao
ISNI:       0000 0004 6501 0867
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2017
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Abstract:
The intestinal epithelium represents one of the most actively renewing tissues in the body, and is widely used as a model system to study epithelial cell biology. ASPP2, a member of the ASPP (apoptosis stimulating protein of p53) protein family, has been shown to act as a regulator of epithelial cell polarity and tumour suppressor. This study investigated whether the dual function of ASPP2 is involved in the regulation of intestinal homeostasis and tumourigenesis, with a particular interest in the distinction between epithelial cell autonomous and non-autonomous mechanisms. Germline and intestinal epithelial cell-specific ASPP2 conditional knockout mice were employed in this study. Deficiency of ASPP2 in the intestinal epithelium resulted in delayed recovery from dextran sulfate sodium (DSS)-induced acute colitis, concurrent with a reduction in the expression of proinflammatory cytokines such as interleukin (IL)-1β and IL-6. Moreover, ASPP2-deficient mice showed increased susceptibility to Azoxymethane/DSS-induced colorectal tumourigenesis. While wild-type and ASPP2-deficient crypts showed similar incidence of tumour formation, the local immune microenvironment of ASPP2-deficient mice favoured tumour progression. The intestinal organoid culture was established to supplement in vivo experiments. The feasibility of the system was demonstrated with small intestinal organoids, in the context of proliferation, differentiation, and cell death. Using the established workflow, a colonic organoid-based tissue regeneration model was developed. The intrinsic susceptibility of organoids to DSS-induced cell death was not affected by the loss of ASPP2. However, ASPP2-deficient colonic organoids were less responsive to the pro-proliferative effects of IL-6, but were more sensitive to tumour necrosis factor-α-induced cell death in the presence of IL-22. In conclusion, this project undertook parallel examinations of animal models and organoids, demonstrating that a deficiency of ASPP2 in the intestinal epithelium results in dysregulated epithelial-immune cell interactions. This may partially explain the pathological conditions observed in ASPP2-deficient mice. Importantly, this study highlights the possibility of using organoids to investigate epithelial cell non-autonomous factors implicated in intestinal pathogenesis.
Supervisor: Lu, Xin Sponsor: Ludwig Institute for Cancer Research ; China Scholarship Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.736094  DOI: Not available
Keywords: Cancer--Research ; Cell Biology ; Intestinal Stem Cell ; Colorectal Cancer ; ASPP2 ; Organoid ; Inflammation
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