KLF6 Mediates de novo Ornithine Synthesis and Polyamine Production in Pancreatic Ductal Adenocarcinoma

• Main Author: Santos Cade, Jamil
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-2023
• Subjects: Biochemistry; Cellular biology; Medicine; Molecular biology; Oncology
• ISBN: 9798379968571

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy that has one of the lowest 5-year survival rates amongst all cancers due to its aggressiveness and low progress in elucidating new therapies for this disease. A recent discovery from our lab is the reliance of PDAC on glutamine for the production of polyamines within the tumor microenvironment, a process that will support cancer cell proliferation and tumor growth. The transcriptional factor KLF6, which is highly expressed in PDAC, was identified to be essential for de novo ornithine synthesis (DNS), an unconventional pathway that PDAC cells employ to use glutamine, instead of arginine, for polyamine synthesis and to promote cell survival. However, the full mechanism that leads to KLF6 activation and its complete function in DNS and polyamine synthesis remain to be elucidated. In this study, we aim to investigate the role of KLF6 in polyamine synthesis and PDAC tumorigenesis. Initially, we observed that KLF6 is strongly expressed in murine tumor pancreatic tissue in comparison to normal pancreatic tissue. We then explored the mutational frequency of KLF6 in human and murine PDAC cell lines that could lead to its active state, but no mutation was found. We optimized antibody recognition of both murine and human KLF6 protein and immunoprecipitation conditions, however, no phosphorylation of KLF6 was observed upon modulation of EGF signaling via immunoblot analysis. Upon pharmacological inhibition of MEK, we detected no significant change in KLF6 protein expression in human PDAC cell lines, suggesting that KRAS downstream signaling is influencing KLF6 activity via post-translational modifications. Additionally, we optimized in vitro and immunoprecipitation conditions for Coomassie staining identification of KLF6 and mass spectrometry analysis. This work sheds a new light for potential therapeutic targets of PDAC and prepares the field for future work investigating KLF6 and tumorigenesis.