title: Relationships between LDH-A, lactate, and metastases in 4T1 breast tumors.
abstract: OBJECTIVE
  To investigate the relationship between lactate dehydrogenase A (LDH-A) expression, lactate concentration, cell metabolism, and metastases in murine 4T1 breast tumors.
  
  
  METHODS
  Inhibition of LDH-A expression and protein levels were achieved in a metastatic breast cancer cell line (4T1) using short hairpin RNA (shRNA) technology. The relationship between tumor LDH-A protein levels and lactate concentration (measured by magnetic resonance spectroscopic imaging, MRSI) and metastases was assessed.
  
  
  RESULTS
  LDH-A knockdown cells (KD9) showed a significant reduction in LDH-A protein and LDH activity, less acid production, decreased transwell migration and invasion, lower proliferation, reduced glucose consumption and glycolysis, and increase in oxygen consumption, reactive oxygen species (ROS), and cellular ATP levels, compared with control (NC) cells cultured in 25 mmol/L glucose. In vivo studies showed lower lactate levels in KD9, KD5, and KD317 tumors than in NC or 4T1 wild-type tumors (P < 0.01), and a linear relationship between tumor LDH-A protein expression and lactate concentration. Metastases were delayed and primary tumor growth rate decreased.
  
  
  CONCLUSIONS
  We show for the first time that LDH-A knockdown inhibited the formation of metastases, and was accompanied by in vivo changes in tumor cell metabolism. Lactate MRSI can be used as a surrogate to monitor targeted inhibition of LDH-A in a preclinical setting and provides a noninvasive imaging strategy to monitor LDH-A-targeted therapy. This imaging strategy can be translated to the clinic to identify and monitor patients who are at high risk of developing metastatic disease.
authors.affiliation: Authors' Affiliations: Departments of Medical Physics, Neurology, Radiology, and Medicine, Bioinformatics Core, Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center; and Department of Physiology and Biophysics, Weill Cornell Graduate School of Medical Sciences, New York, New York.
authors.forename: Asif
authors.initials: A
authors.lastname: Rizwan
authors.forename: Inna
authors.initials: I
authors.lastname: Serganova
authors.forename: Raya
authors.initials: R
authors.lastname: Khanin
authors.forename: Hazem
authors.initials: H
authors.lastname: Karabeber
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Ni
authors.forename: Sunitha
authors.initials: S
authors.lastname: Thakur
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Zakian
authors.forename: Ronald
authors.initials: R
authors.lastname: Blasberg
authors.forename: Jason A
authors.initials: JA
authors.lastname: Koutcher
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D005260:Female; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000080864:Lactate Dehydrogenase 5; D019344:Lactic Acid / Q000378:metabolism*; D008175:Lung Neoplasms / Q000378:metabolism / Q000556:secondary*; D051379:Mice; D010101:Oxygen Consumption; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species; D014407:Tumor Cells, Cultured
chemical_list: D007527:Isoenzymes; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; D005947:Glucose