The role of microRNAs in epithelial mesenchymal transition

Abstract

MicroRNAs (miRNAs) are master regulators of various biological processes, primarily by binding mRNA to control gene expression. Unsurprisingly, aberrant miRNA expression can therefore contribute to the development and progression of many diseases. A central process modulated by miRNAs is the epithelial-mesenchymal transition (EMT). Prostate cancer and glaucoma are two diseases advanced by aberrant EMT. Hence, this thesis investigated the role of miRNAs in EMT associated with these conditions. By integrating data from various sources through an in-silico selection process, miR-143-3p andmiR-145-5p emerged as leading candidates for further investigation.

In prostate cancer, results showed that decreased expression of miR-143-3pand miR-145-5p correlated with advanced disease markers. Functional enrichment analysis revealed their association with EMT and extra cellularmatrix remodelling. The EMT-linked genes AKT1 and MYO6 were identified and experimentally validated as novel targets of miR-143-3p and miR-145-5p, respectively. In vitro manipulation of these miRNAs significantly altered cell proliferation, clonogenicity, migration, and EMT marker expression in prostate cancer cells, highlighting their biological role in controlling cell growth and behaviour. Their potential as diagnostic biomarkers and therapeutic agents was also evidenced.

In glaucomatous trabecular meshwork (TM) cells, miR-143-3p and miR-145-5pwere upregulated and associated with fibrotic processes. TGF-β1 and TGF-β2treatment increased their expression in both normal and glaucomatous TM cells. KLF4, a gene implicated in fibrotic diseases, was identified and experimentally validated as a novel target of these miRNAs in TM cells. Modulation of miR-143-3p and miR-145-5p levels altered the expression of fibrotic markers and genes involved in actin cytoskeleton dynamics, leading to increased stress fibre formation and TM cell contractility. This demonstrates their important role in control of biological mechanisms related to EMT and fibrosis in glaucoma.

This thesis presents new evidence demonstrating the roles played by miR-143-3p and miR-145-5p in EMT processes which contribute to the pathogenesis of prostate cancer and glaucoma. These novel results add new knowledge to the understanding of the complex interactions, biological functions, and regulatory networks of miR-143-3p and miR-145-5p. The data helps propose these miRNAs as potential diagnostic biomarkers and therapeutic targets for these diseases. Together, this evidence of their importance warrants further investigation into the clinical utility of these miRNAs. Continued research will help translate these promising findings into improved patient care strategies and health outcomes for individuals affected by prostate cancer and glaucoma.

Date of Award	Jan 2025
Original language	English
Sponsors	Department for the Economy
Supervisor	Colin Willoughby (Supervisor) & Declan McKenna (Supervisor)