Abstract LB-107: Targeting the glycolytic pathway as an effective therapeutic approach for triple-negative breast cancer
Authors: Pelicano Helene , Zhang Wan , Hammoudi Naima , Pusztai Lajos , Dai Jiale , Huang Peng 
Published: February 2011

Abstract
Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with estrogen receptor-negative, progesterone receptor-negative, and HER-2-negative phenotype. TNBC often exhibits poor prognosis due in part to their resistance to therapeutic agents. Thus, development of novel therapeutic approaches and effective agents are urgently needed to improve the clinical outcomes of this disease. In our recent study of metabolic alterations in cancer cells, we observed a striking metabolic pattern in TNBC cells manifested by lower mitochondrial respiration and elevated glycolysis. Using the extracellular flux analyzer XF24, we compared 4 TNBC cell lines (BT-20, MDA-231, MDA-468, MDA-436) with other subtypes of breast cancer cells (BT-474, MCF7, T47D, ZR-751) for their oxygen consumption rate (OCR) as an indicator of mitochondrial respiration and extracellular acidification rate (ECAR) as an indication of lactic acid production from glycolysis. All TNBC cell lines consistently exhibited lower OCAR and higher ECAR. These metabolic alterations were further confirmed using several conventional biochemical analyses including Clark-type electrode detection of oxygen consumption, [3H]-glucose uptake, and direct lactate measurement. In triple-positive breast cancer cells (BT474), blockage of ER-signaling by 4-hydroxy-tamoxifen (4-HOT), progestin signaling by RU486, or the HER-2 pathway by herceptin caused a moderate decrease in mitochondrial respiration when each inhibitor was used alone. Simultaneous inhibition of the three receptors by a combination of 4-HOT, RU486 and herceptin significantly down-regulated mitochondrial respiration (40%), suggesting a possible cross-talk among the three pathways in regulating mitochondrial metabolism. Western blot and mitochondrial functional analyses revealed that TNBC cells had altered expression of certain respiratory chain components and corresponding defect in the respiratory complex activity. Based on these novel observations, we further tested the hypothesis that TNBC cells might be more dependent on glycolysis for ATP generation and thus more vulnerable to glycolytic inhibitors. Indeed, our results demonstrated that TNBC cells were significantly more sensitive to the glycolytic inhibitors 3-bromopyruvate and 2-deoxyglucose than other breast cancer subtypes. Inhibition of glycolysis caused a massive cell death in TNBC cells, as evidenced by positive annexin-V staining and loss of membrane potential. Our study suggest that TNBC cells have profound metabolic alterations characterized by decreased mitochondrial respiration and increased glycolysis, and that glycolytic inhibition may represent a novel therapeutic strategy to effective kill the drug-resistant TNBC cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-107.