Thesis advisor: Thomas N. Seyfried / It has long been posited that all cancer cells are dependent on glucose for energy, termed the "Warburg Effect". As a result of an irreversible injury to the mitochondria, cancer cells are less efficient in aerobic respiration. Therefore, calorie restriction was thought to be a natural way to attenuate tumor growth. Calorie restriction lowers blood glucose, while increasing the circulation of ketone bodies. Ketone bodies are metabolized via oxidative phosphorylation in the mitochondria. Only cells that are metabolically capable of aerobic respiration will thus be able to acquire energy from ketone bodies. To date, calorie restriction has been shown to greatly reduce tumor growth and angiogenesis in the murine CT2A, EPEN, and human U87 brain tumor models. Using the novel VM-M3 model for invasive brain cancer and systemic metastatic cancer, I found that though calorie restriction had some efficacy in reducing brain tumor invasion and primary tumor size, metastatic spread was unaffected. Using a bioluminescent-based ATP assay, I determined the viability of metastatic mouse VM-M3 tumor cells grown in vitro in serum free medium in the presence of glucose alone (25 mM), glutamine alone (4 mM), or in glucose + glutamine. The VM-M3 cells could not survive on glucose alone, but could survive in glutamine alone indicating an absolute requirement for glutamine in these metastatic tumor cells. Glutamine could also maintain viability in the absence of glucose and in the presence of the F1 ATPase inhibitor oligomycin. Glutamine could not maintain viability in the presence of the Krebs (TCA) cycle enzyme inhibitor, 3-nitropropionic acid. The data indicate that glutamine can provide ATP for viability in the metastatic VM-M3 cells through Krebs cycle substrate level phosphorylation in the absence of energy from either glycolysis or oxidative phosphorylation. I therefore developed a metabolic therapy that targeted both glucose and glutamine metabolism using calorie restriction and 6-diazo-5-oxo-L-norleucine (DON), a glutamine analog. Primary tumor growth was about 20-fold less in DON treated mice than in untreated control mice. I also found that DON treatment administered alone or in combination with CR inhibited metastasis to liver, lung, and kidney as detected by bioluminescence imaging and histology. Although DON treatment alone did not reduce the incidence of tumor metastasis to spleen compared to the controls, DON administered together with CR significantly reduced the incidence of metastasis to the spleen, indicating a diet/drug synergy. In addition, the phagocytic capabilities of the VM-M3 tumor cells were enhanced during times of energy stress. This allowed for the digestion of engulfed material to be used in energy production. My data provide proof of concept that metabolic therapies targeting both glucose and glutamine metabolism can manage systemic metastatic cancer. Additionally, due to the phagocytic properties of the VM-M3 cell line also seen in a number of human metastatic cancers, I suggest that a unique therapy targeting metabolism and phagocytosis will be required for effective management of metastatic cancer. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.
| Identifer | oai:union.ndltd.org:BOSTON/oai:dlib.bc.edu:bc-ir_102047 |
| Date | January 2010 |
| Creators | Shelton, Laura Marie |
| Publisher | Boston College |
| Source Sets | Boston College |
| Language | English |
| Detected Language | English |
| Type | Text, thesis |
| Format | electronic, application/pdf |
| Rights | Copyright is held by the author, with all rights reserved, unless otherwise noted. |
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