title: Changes in 2-fluoro-2-deoxy-D-glucose incorporation, hexokinase activity and lactate production by breast cancer cells responding to treatment with the anti-HER-2 antibody trastuzumab.
abstract: BACKGROUND
  Changes in 2-[(18)F]-fluoro-2-deoxy-D-glucose (FDG) incorporation by tumors, detected using positron emission tomography, during response to chemotherapy are utilized clinically in patient management. Here, the effect of treatment with growth-inhibitory doses of the anti-human epidermal growth factor receptor-2 antibody trastuzumab (Herceptin) on the incorporation of FDG by breast tumor cells was measured along with hexokinase (HK) and glucose transport to determine the potential of FDG-positron emission tomography in predicting response to these biological anti-cancer therapies and their modulatory effects on the steps involved in FDG incorporation.
  
  
  METHODS
  The sensitivity to trastuzumab of three breast tumor cell lines, SKBr3, MDA-MB-453 and MDA-MB-468, expressing human epidermal growth factor receptor-2 at high, medium and low levels, respectively, was determined using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay over a 6-day period, and a clonogenic assay was carried out after 7- and 10-day exposures. FDG incorporation by cells treated with growth-inhibitory doses of trastuzumab was carried out after 4 h and 2, 4 and 6 days of treatment. Glucose transport (rate of uptake of the non-metabolizable analogue [(3)H]O-methyl-D-glucose), HK activity and lactate production were measured on cells treated with inhibitory doses of trastuzumab for 6 days.
  
  
  RESULTS
  The IC(50) doses for SKBr3 and MDA-MB-453 and the IC(20) dose for MDA-MB-468 after 6 days of treatment with trastuzumab were 0.25, 1 and 170 μg/ml, respectively. FDG incorporation by SKBr3 and MDA-MB-453 cells was found to be decreased using IC(50) doses of trastuzumab for 6 days. At the IC(50) doses, FDG incorporation was also decreased at 4 days and, in the case of MDA-MB-453, even after 4 h of treatment. Decreased FDG incorporation corresponded with decreased HK activity in these cells. Lactate production, previously suggested to be a potential measure of response, was found to be significantly decreased by SKBr3 and MDA-MB-453 cells responding to trastuzumab.
  
  
  CONCLUSIONS
  FDG incorporation at the tumor cell level is modulated by treatment with growth-inhibitory doses of trastuzumab due to modulation of HK activity. Changes in lactate production may also be a useful determinant of response to trastuzumab.
authors.affiliation: School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Cheyne
authors.forename: Laurent
authors.initials: L
authors.lastname: Trembleau
authors.forename: Abbie
authors.initials: A
authors.lastname: McLaughlin
authors.forename: Tim A D
authors.initials: TA
authors.lastname: Smith
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D001692:Biological Transport / Q000187:drug effects; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000096:biosynthesis*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D013778:Tetrazolium Salts / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism; D000068878:Trastuzumab; D014410:Tumor Stem Cell Assay
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D019788:Fluorodeoxyglucose F18; D005947:Glucose; D006593:Hexokinase; D019344:Lactic Acid; D018719:Erb-b2 Receptor Tyrosine Kinases; D013778:Tetrazolium Salts; D013844:Thiazoles; D000068878:Trastuzumab; C508053:ERBB2 protein, human; C022616:thiazolyl blue