Date of Completion
2025
Document Type
Honors College Thesis
Department
Biomedical and Health Sciences
Thesis Type
Honors College
First Advisor
Paula Deming
Second Advisor
David Seward
Third Advisor
Alicia Ebert
Abstract
Lung adenocarcinomas with co-occurring mutations in KRAS and STK11 comprise a population of cases contributing to the approximately 125,000 lung cancer related deaths each year (Siegel et al., 2024). This subtype exhibits increased metastatic disease; however the mechanisms remain unknown. The tumor suppressor STK11 has been shown to regulate metabolism in cancers due to its position upstream of many metabolic pathways. With regard to metastatic potential, and of interest to the Deming Lab, it has been observed that cancer cell lines with the inactivation of STK11 in the presence of a KRAS oncogenic mutation have rewired metabolic flux through a pathway known as the Hexosamine Biosynthesis Pathway (HBP). One product of this pathway is a sugar moiety that can be used for general glycosylation or the post-translational modification, O-GlcNAcylation, which has been associated with epithelial-mesenchymal transition (EMT) and metastatic spread (Lucena et al., 2016). While multiple studies have shown that STK11 null lung adenocarcinoma (LUAD) cells have enhanced HBP flux under nutrient replete conditions, we recently observed a striking observation that HBP flux increases during early hours of glutamine deprivation, suggesting a protective metabolic shunt under conditions of glutamine stress. Glutamine fructose-6-phosphate amidotransferase (GFAT), controls the entrance of glutamine into the HBP, and there are two isoforms, GFAT1 and GFAT2. Upon glutamine deprivation in both the parental and STK11 null cells, GFAT1 levels increase while GFAT2 levels correspondingly decrease, suggesting the enhanced HBP flux observed previously upon glutamine deprivation could be due to elevated GFAT1 protein levels. To further establish the effect of GFAT2 on HBP flux, we created GFPT2 knockout cell lines from both parental and STK11 null LUAD cells. While the densitometry did not reveal any significant differences in HBP flux upon glutamine deprivation or upon loss of GFPT2, there was a trend of elevated HBP flux for both GFPT2 knock out cell lines. Further work is needed to conclude the role of GFPT2 in promoting HBP flux upon glutamine deprivation, however these results provide evidence to support that GFPT1 might be influencing the observed flux in STK11 null cells. Elucidation of metabolic rewiring, specifically of HBP in STK11 null LUAD may provide the basis for future therapeutic implications given the current interest in targeting of metabolic liabilities in cancers.
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Recommended Citation
Johnson, Rachel M., "Investigating the Glutamine-Dependent Metabolism of Knockout STK11 Lung Adenocarcinoma" (2025). UVM Patrick Leahy Honors College Senior Theses. 729.
https://scholarworks.uvm.edu/hcoltheses/729