AVB-500, a selective inhibitor of GAS6-AXL, in combination with paclitaxel alters uterine serous cancer cell metabolism

Abstract

<h3>Objectives:</h3> Even in the presence of oxygen, cancer cells preferentially metabolize glucose to ATP by the less efficient glycolysis pathway over oxidative phosphorylation. This concept, known as the Warburg effect, has been implicated in the rapid proliferation of cancer cells, tumor progression, and resistance to chemotherapy. The receptor tyrosine kinase AXL is highly expressed in uterine serous cancer (USC) and promotes chemo-resistance and metastasis. Our lab has shown that treatment with novel GAS6-AXL inhibitor, AVB-500, in combination with paclitaxel (P) has improved therapeutic efficacy compared to P alone. The role of AXL in cancer cell metabolism has not been elucidated. Our objective was to evaluate if AVB-500+P decreases tumor cell ability to generate energy via glycolysis, thereby providing a mechanism by which this treatment decreases tumor burden in a USC mouse model. <h3>Methods:</h3> In vivo studies were performed using NOD-SCID mice injected intraperitoneal (IP) with 1 x 107 ARK1 uterine serous cells. Treatment groups included vehicle, AVB-500, P, and AVB-500+P. [U-13C] glucose tracer was injected IP one hour before sacrifice. Tumor was collected, snap frozen in liquid nitrogen, and prepared for liquid chromatography/mass spectrometry (LC/MS). Hydrophilic interaction liquid chromatography was performed with an Agilent 6530 QTOF. Metabolites were identified by in-house database with retention time and fragment data. To determine the relative metabolite abundance across samples, the area of the extracted ion current peak for the metabolite of interest was normalized for protein content. <h3>Results:</h3> Treatment with AVB-500+P was found to decrease multiple glycolytic metabolites: glucose-6-phosphate by 2.66 fold (p=0.031), fructose-1,6-bisphosphate by 4.20 fold (p=0.002), 3-phosphoglyceric acid by 7.76 fold (p=0.014), phosphoenolpyruvate by 8.85 fold (p=0.013), lactate by 2.78 fold (p=0.024) compared to P alone. Additionally, TCA cycle intermediates including fumarate and malate were decreased by 1.94 fold (p=0.036) and 2.03 fold (p=0.031) respectively in AVB-500+P treated tumor compared to P alone. Notably, glucose abundance was not significantly different between P and AVB-500+P treated tumor (p=0.440) suggesting that AVB-500 is acting downstream of glucose uptake which correlates with the decrease in the metabolites listed above. <h3>Conclusions:</h3> Innovative [U-13C] glucose tracing <i>in vivo</i> has revealed metabolic changes in tumor cells after treatment. We observed that the novel GAS6-AXL inhibitor AVB-500+P prevents tumors cells from generating adequate energy (ATP) through the preferred glycolysis pathway. These results indicate that GAS6-AXL signaling may play a role in metabolic reprogramming in USC tumors, suggesting a mechanism for the observed decreased tumor burden in AVB-500+P treated mice. Additional studies are ongoing to better define this relationship.