Graduation Date

Summer 8-12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Biochemistry & Molecular Biology

First Advisor

Justin Mott M.d., Ph.D.

Abstract

Cholangiocarcinoma is a primary liver cancer of the bile duct epithelium that exhibits microRNA-mediated control of tumor cell signaling. Strides toward new treatment rest on a better defining of cholangiocarcinoma tumor biology including the RNA-based layer of regulation. Additionally, there is a gap in knowledge on microRNA expression in human tissue. While there is RNA-seq data of microRNA expression in tissue, it does not differentiate between cell types, thus leaving unanswered questions about cell specific microRNA biology and expression.

Here, we identify miR-10a as an oncogenic microRNA acting through MAPK signaling. Using cholangiocarcinoma cell lines, we determined miR-10a is an oncogenic microRNA who’s overexpression results in the development of three cancer features: increased apoptotic resistance, increased cell migration and increased cell proliferation. miR-10a was found to regulate multiple kinase pathways and altered the expression of multiple kinases in cholangiocarcinoma. Of importance, we determined miR-10a regulates apoptotic resistance and cell migration through the novel binding of the MAP3 kinase proteins MLK-1 and TAK1.

To better understand the role of miR-10a in cholangiocarcinoma we also investigated its expression in patient samples as well as healthy colon and liver samples. We found while miR-10a expression is low overall in the cholangiocarcinoma tumor it has non-regional uniform expression throughout. This suggests miR-10a plays a key role in a specific phenotype of cholangiocarcinoma cells which are likely to be metastatic. Additionally, we discovered regional cell specific miR-10a expression in both normal colon and liver tissue, while also confirming RNA-seq results of general miR-10a expression in the liver and colon.

In summary, the expression of miR-10a is high in select populations of cholangiocarcinoma cells causing loss of MLK-1 and TAK1 expression. This results in the development of a metastatic phenotype of cholangiocarcinoma cells that have increased apoptotic resistance, cell migration and cell proliferation. Overall, this dissertation sought a deeper understanding of both tumor and microRNA biology by adding to our understanding of cholangiocarcinoma features as well as microRNA expression and regulation.

Comments

2022 Copyright, the authors

Available for download on Friday, August 04, 2023

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