GLUT1 inhibitor BAY-876 induces apoptosis and enhances anti-cancer effects of bitter receptor agonists in head and neck squamous carcinoma cells

Abstract

Head and neck squamous cell carcinomas (HNSCCs) are cancers that arise in the mucosa of the upper aerodigestive tract. The five-year patient survival rate is ~50%. Treatment includes surgery, radiation, and/or chemotherapy and is associated with lasting effects even when successful in irradicating the disease. New molecular targets and therapies must be identified to improve outcomes for HNSCC patients. We recently identified bitter taste receptors (taste family 2 receptors, or T2Rs) as a novel candidate family of receptors that activate apoptosis in HNSCC cells through mitochondrial Ca²⁺ overload and depolarization. We hypothesized that targeting another component of tumor cell metabolism, namely glycolysis, may increase the efficacy of T2R-directed therapies. GLUT1 (SLC2A1) is a facilitated-diffusion glucose transporter expressed by many cancer cells to fuel their increased rates of glycolysis. GLUT1 is already being investigated as a possible cancer target, but studies in HNSCCs are limited. Examination of immortalized HNSCC cells, patient samples, and The Cancer Genome Atlas revealed high expression of GLUT1 and upregulation in some patient tumor samples. HNSCC cells and tumor tissue express GLUT1 on the plasma membrane and within the cytoplasm (perinuclear, likely co-localized with the Golgi apparatus). We investigated the effects of a recently developed small molecule inhibitor of GLUT1, BAY-876. This compound decreased HNSCC glucose uptake, viability, and metabolism and induced apoptosis. Moreover, BAY-876 had enhanced effects on apoptosis when combined at low concentrations with T2R bitter taste receptor agonists. Notably, BAY-876 also decreased TNFα-induced IL-8 production, indicating an additional mechanism of possible tumor-suppressive effects. Our study demonstrates that targeting GLUT1 via BAY-876 to kill HNSCC cells, particularly in combination with T2R agonists, is a potential novel treatment strategy worth exploring further in future translational studies.