Browsing by Subject "kidney development"

Wilms tumor is the most common kidney cancer in children. The origin of Wilms tumor is thought to arise from disturbed embryonic development. Wilms tumor is characterized by so called nephrogenic rests consisting of undifferentiated metanephric mesenchyme, that are precursor lesions for tumorigenesis. In addition, the tumors themselves contain tissue types normally found only in the developing kidney and they resemble embryonic kidneys transcriptionally. Since the tumors are heterogenous and contain blastemal, stromal, and epithelial components, all three progenitor populations of the developing kidney, nephron, collecting duct and stromal progenitors, are possible origins of tumors. MAPK/ERK pathway plays a significant role in kidney development for example by affecting nephron progenitor self-renewal and regulating collecting duct progenitor maintenance. Previous studies suggest that MAPK/ERK activity plays a role in Wilms tumor by mediating the intracellular effects of IGF2 overexpression. The aim of this master’s thesis is to compare transcriptional profiles of Wilms tumor to the transcriptional profiles in mouse MAPK/ERK deficient nephron progenitors and ureteric bud epithelium. This is done by utilizing internet-based tool ToppFun and R/Bioconductor tool gage (Generally Applicable Gene-set Enrichment for Pathway Analysis) for Gene Ontology (GO) and KEGG pathway analysis. My analysis revealed several shared GO and KEGG pathways that compose of differentially expressed genes with opposite expression patterns in Wilms tumor and MAPK/ERK deficient renal progenitors. The identified pathways include those previously validated by the host laboratory and some interesting new pathways that will be studied further in the future. The most interesting novel pathways affected in both Wilms tumor and MAPK/ERK deficient kidneys were related to the extracellular matrix (ECM) and chromatin. ECM related GO terms were specifically altered in nephron progenitors and Wilms tumor suggesting that Wilms tumor transformation involves dysregulation of ECM possibly downstream of MAPK/ERK pathway. MAPK/ERK pathway also mediates chromatin level regulation which is also demonstrated by my results. Chromatin related GO terms were upregulated in Wilms tumor and downregulated both in ureteric bud epithelium and nephron progenitors. The second aim of my thesis is to verify the observed gene expression changes by utilizing mouse embryonic kidney cultures and qPCR. The validation was only initial trial and requires further optimization. It did not show significant downregulation in selected validation genes that were chosen for validation. Future goal of my research is to carry out similar analysis in chemotherapy naïve dataset and at different Wilms tumor stages. This will allow avoiding possible chemotherapy induced changes in the outcome and better sorting of tumor progression and its correlation with specific renal progenitor types. In summary, my current results suggest both ECM and chromatin regulation as promising fields for future research.