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

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