title: Irradiation-dependent effects on tumor perfusion and endogenous and exogenous hypoxia markers in an A549 xenograft model.
abstract: OBJECTIVE
  Hypoxia is a major determinant of tumor radiosensitivity, and microenvironmental changes in response to ionizing radiation (IR) are often heterogenous. We analyzed IR-dependent changes in hypoxia and perfusion in A549 human lung adenocarcinoma xenografts.
  
  
  METHODS
  Immunohistological analysis of two exogenously added chemical hypoxic markers, pimonidazole and CCI-103F, and of the endogenous marker Glut-1 was performed time dependently after IR. Tumor vessels and apoptosis were analyzed using CD31 and caspase-3 antibodies. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and fluorescent beads (Hoechst 33342) were used to monitor vascular perfusion.
  
  
  RESULTS
  CCI-103F signals measuring the fraction of hypoxic areas after IR were significantly decreased by approximately 50% when compared with pimonidazole signals, representing the fraction of hypoxic areas from the same tumors before IR. Interestingly, Glut-1 signals were significantly decreased at early time point (6.5 h) after IR returning to the initial levels at 30.5 h. Vascular density showed no difference between irradiated and control groups, whereas apoptosis was significantly induced at 10.5 h post-IR. DCE-MRI indicated increased perfusion 1 h post-IR.
  
  
  CONCLUSIONS
  The discrepancy between the hypoxic fractions of CCI-103F and Glut-1 forces us to consider the possibility that both markers reflect different metabolic alterations of tumor microenvironment. The reliability of endogenous markers such as Glut-1 to measure reoxygenation in irradiated tumors needs further consideration. Monitoring tumor microvascular response to IR by DCE-MRI and measuring tumor volume alterations should be encouraged.
authors.affiliation: Department of Radiotherapy and Radiation Oncology, University Hospital Marburg, Medical Faculty of Philipps University, Marburg, Germany. emmanouil.fokas@yahoo.de
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Fokas
authors.forename: Jörg
authors.initials: J
authors.lastname: Hänze
authors.forename: Florentine
authors.initials: F
authors.lastname: Kamlah
authors.forename: Bastian G
authors.initials: BG
authors.lastname: Eul
authors.forename: Nico
authors.initials: N
authors.lastname: Lang
authors.forename: Boris
authors.initials: B
authors.lastname: Keil
authors.forename: Johannes T
authors.initials: JT
authors.lastname: Heverhagen
authors.forename: Rita
authors.initials: R
authors.lastname: Engenhart-Cabillic
authors.forename: Hanxiang
authors.initials: H
authors.lastname: An
authors.forename: Frank
authors.initials: F
authors.lastname: Rose
mesh_terms: D000230:Adenocarcinoma / Q000098:blood supply / Q000378:metabolism / Q000532:radiotherapy; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D001562:Benzimidazoles / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D053148:Caspase 3 / Q000032:analysis / Q000276:immunology; D015687:Cell Hypoxia / Q000528:radiation effects; D003287:Contrast Media / Q000378:metabolism; D005682:Gadolinium / Q000378:metabolism; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000098:blood supply / Q000378:metabolism / Q000532:radiotherapy; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009593:Nitroimidazoles / Q000378:metabolism*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis / Q000276:immunology; D013997:Time Factors; D014183:Transplantation, Heterologous; D005466:Fluorocarbons
chemical_list: D001562:Benzimidazoles; D015415:Biomarkers; D053148:Caspase 3; D003287:Contrast Media; D005682:Gadolinium; D051272:Glucose Transporter Type 1; D009593:Nitroimidazoles; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C049948:CCI 103F; D005466:Fluorocarbons; C033815:pimonidazole; C017807:bisbenzimide ethoxide trihydrochloride