Abstract A020: Elevated extracellular glucose level in tumor microenvironment by hyperglycemia increases glycolysis rate, stiffness, contractility, and motility of breast cancer cells through the cAMP-RhoA-Rock and AMPK-YAP-RhoA axes to promote metastasis
Authors: Kim Tae-Hyung , Bhat Aadil Q , Choe Jun-Yong , Yoon Donghoon 
Published: November 2024

Abstract
Glucose is a preferred nutrient for most cells, including cancer cells. The tumor microenvironment is both hypoxic and hypoglycemic. Glucose levels in tumors are ten times lower than in normal tissues due to poor vascularization and high glucose consumption by cancer cells, which adapt to hypoglycemia. Obesity, often accompanied by hyperglycemia, hyperinsulinemia, and hypertriglyceridemia, is linked to increased breast cancer metastasis. High extracellular glucose levels have been shown to promote cancer cell motility, though the mechanisms remain unclear. Given cancer cells' reliance on aerobic glycolysis (the Warburg effect), we hypothesized that hyperglycemia in obesity promotes cancer metastasis by modulating glucose metabolism and related cell mechanics pathways. Using Triple-Negative Breast Cancer (TNBC) cells, we found that elevated extracellular glucose levels increase glycolysis, activating the RhoA GTPase signaling pathway. This results in greater cell stiffness and contractility, correlating with increased motility. Our unpublished data, which I will present, validate these findings in obese-TNBC mouse models and further elucidate the glycolysis-mediated activation of the RhoA-ROCK axis. We also identified a novel long-term effect of hyperglycemia in promoting metastasis via transcriptional regulation of the AMPK-YAP-RhoA axis. To confirm hyperglycemia's pro-metastatic effects, we developed two obese-TNBC mouse models using diet-induced obesity (DIO) in NSG and C57BL/6J mice with orthotopic implantation of human and mouse TNBC cells, respectively. RhoA GTPase activity was measured with a GTP-RhoA FRET sensor or pull-down assay. Cell stiffness was assessed using our innovative parallel microfiltration (PMF) assay or Atomic Force Microscopy (AFM). We disrupted glucose uptake by knocking out glucose transporter 3 (GLUT3) via CRISPR/Cas9 or using a GLUT3-selective inhibitor, G3iA. Cell motility was measured by scratch wound-healing and invasion assays. Bulk RNA-seq identified differentially expressed genes under high glucose conditions in human breast cancer cells. Our results show increased lung metastasis of breast cancer cells under hyperglycemic conditions in vivo. Besides the previously reported cAMP-RhoA-ROCK axis, we discovered the glycolysis-AMPK-YAP axis also regulates RhoA-ROCK activity transcriptionally. GLUT3 inhibition activated AMPK, reduced F-actin levels via the AMPK-VASP axis, and decreased non-muscle myosin activity through the AMPK-YAP-RhoA axis. These changes in cell mechanics correlated with reduced motility. Our study suggests that targeting glucose metabolism and cell mechanics could be a novel approach to inhibit cancer metastasis, particularly in obese patients.
Citation Format: Tae-Hyung Kim, Aadil Q Bhat, Jun-Yong Choe, Donghoon Yoon. Elevated extracellular glucose level in tumor microenvironment by hyperglycemia increases glycolysis rate, stiffness, contractility, and motility of breast cancer cells through the cAMP-RhoA-Rock and AMPK-YAP-RhoA axes to promote metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A020.