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Characterization and Treatment of Chromatin Remodeling Protein Deficient DDEC
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- Author / Creator
- Coatham, Mackenzie L.
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Some of the most aggressive endometrial cancer cases display extensive heterogeneity within the same tumor in the form of mixed undifferentiated and well-differentiated phenotypes. The emergence of dedifferentiation in higher grade endometrial carcinomas presents an obstacle for both timely and accurate diagnosis and specific and effective treatment. Even though endometrial cancers of this nature are less common, we used a collection of patient tissue and developed cell line-based models of disease using gene editing technology to discover and interrogate many features of dedifferentiated endometrial cancer or DDEC. Firstly, utilizing targeted sequencing and gene expression profiling paired with immunohistochemistry, I discovered loss of chromatin remodellers and markers of epithelial differentiation to be a defining feature of the undifferentiated portions of DDEC neoplasms. By comparing the profiles of the undifferentiated regions to their well-differentiated predecessors within the same tumor, I also demonstrated the emergence of a population of undifferentiated cells within DDEC acquires cancer stem cell-like features. Secondly, three models of DDEC with absent SWI/SNF chromatin remodelling complex subunit SMARCA4 expression, were generated and extensively characterized. I thoroughly documented how in vitro, SMARCA4 loss results in endometrial cancer cells exhibiting senescence but in vivo, SMARCA4 deficiency leads to the formation of tumors that recapitulate clinical DDEC neoplasms. I propose dysregulation of transcription factors governing epithelial cell-related gene expression as a major driver of dedifferentiation in the context of DDEC. Finally, screening of one of the isogenic pairs of gene edited endometrial cancer cells, revealed several synthetic lethal vulnerabilities specific to cells with absent SMARCA4 expression. In vitro, I extensively validated many of the hits and found chemical inhibition of CDK4 and EGFR both alone and in combination to be potentially effective in targeting DDEC-like cells. Preclinical animal studies demonstrated the efficacy of targeting CDK4 and EGFR may be counteracted by in vivo transformation of the model and stromal contribution. In its totality, the work in this thesis provides one of the first comprehensive examinations of DDEC and my development of and findings with the cell line models of this malignancy constitute a noteworthy contribution to our overall understanding of SWI/SNF deficient cancers of the gynecological tract.
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- Graduation date
- Spring 2022
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.