Graduation Date

Spring 5-10-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Biochemistry & Molecular Biology

First Advisor

Moorthy Ponnusamy, PhD

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer known for being one of the most fatal, with a 5-year survival rate of only 10%. This highlights the urgent need to better understand its underlying biology. In recent years, there has been increasing interest in and research into the metabolic characteristics of pancreatic cancer, driven by strong evidence indicating that metabolic reprogramming is crucial in the initiation, progression, and resistance to therapy of the tumor. As our knowledge of the metabolic complexities of pancreatic cancer grows, this area has become increasingly important, offering potential opportunities for early detection, targeted therapies, and personalized treatment approaches in the battle against this challenging disease.

This dissertation has investigated the role and mechanism of two proteins in increasing the aggressiveness of Pancreatic Ductal Adenocarcinoma (PDAC). While several publications have reported different axes affecting and rewiring metabolism in PDAC, my thesis primarily focuses on understanding the impact of abnormal protein expressions on metastatic and aggressive properties of PDAC. We identified a novel protein expressed specifically in aggressive PDAC.

My first set of results addresses the effects that aberrant PAF1 expression has on PDAC metabolism. A correlation analysis using Polymerase associated factor-1 (PAF1) as the selected gene for Pancreatic Cancer (PC) sample type and customized the corGSEA to the hallmark. The analysis revealed that PAF1 expression in Pancreatic Cancer (PC) is enriched and statistically significant in various metabolic pathways, xii including oxidative phosphorylation and glycolysis. Additionally, loss of PAF1 expression resulted in reduced Lactate Dehydrogenase A (LDHA) expression, Extracellular Acidification rate (ECAR), and increased Oxygen Consumption Rate (OCR) rates. Further analysis showed that PAF1 interacts with Hypoxia-Induced Factor 1 (HIF1α) and together regulates the transcription of LDHA.

My second set of results identified a novel protein, GDA, and its role in the metabolic reprogramming of PDAC. Using an aggressive PC cell line and a normal pancreas cell line, RNA sequencing revealed an increased fold change in expression for GDA, which is an enzyme involved in the purine salvage pathway. This was confirmed using multiple analyses (RT-PCR, ddPCR, western blot, and immunohistochemistry) to confirm expression variation in several PC cell lines. Validation of the role of the protein was confirmed through the depletion of the protein and by performing multiple in vivo and in vitro experiments. In addition, we identified a mechanism of action and an inhibitor capable of reducing the expression of these proteins and, ultimately, the proliferation of pancreatic cancer cells. Overall, my work contextualized the roles of two proteins (PAF1 and GDA) in aberrant metabolism to fuel PDAC aggressiveness. The unique mechanisms I discovered provide a potential mode of action to develop therapeutics for PDAC.

Comments

2025 Copyright, the authors

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