In vivo characterization of a reporter gene system for imaging hypoxia-induced gene expression

Sean Carlin, Andrei Pugachev, Xiaorong Sun, Sean Burke, Filip Claus, Joseph O'Donoghue, C. Clifton Ling, John L. Humm

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Purpose: To characterize a tumor model containing a hypoxia-inducible reporter gene and to demonstrate utility by comparison of reporter gene expression to the uptake and distribution of the hypoxia tracer 18F-fluoromisonidazole (18F-FMISO). Methods: Three tumors derived from the rat prostate cancer cell line R3327-AT were grown in each of two rats as follows: (1) parental R3327-AT, (2) positive control R3327-AT/PC in which the HSV1-tkeGFP fusion reporter gene was expressed constitutively, (3) R3327-AT/HRE in which the reporter gene was placed under the control of a hypoxia-inducible factor-responsive promoter sequence (HRE). Animals were coadministered a hypoxia-specific marker (pimonidazole) and the reporter gene probe 124I-2′-fluoro-2′-deoxy-1-β-d-arabinofuranosyl-5-iodouracil (124I-FIAU) 3 h prior to sacrifice. Statistical analysis of the spatial association between 124I-FIAU uptake and pimonidazole fluorescent staining intensity was then performed on a pixel-by-pixel basis. Utility of this system was demonstrated by assessment of reporter gene expression versus the exogenous hypoxia probe 18F-FMISO. Two rats, each bearing a single R3327-AT/HRE tumor, were injected with 124I-FIAU (3 h before sacrifice) and 18F-FMISO (2 h before sacrifice). Statistical analysis of the spatial association between 18F-FMISO and 124I-FIAU on a pixel-by-pixel basis was performed. Results: Correlation coefficients between 124I-FIAU uptake and pimonidazole staining intensity were: 0.11 in R3327-AT tumors, -0.66 in R3327-AT/PC and 0.76 in R3327-AT/HRE, confirming that only in the R3327-AT/HRE tumor was HSV1-tkeGFP gene expression associated with hypoxia. Correlation coefficients between 18F-FMISO and 124I-FIAU uptakes in R3327-AT/HRE tumors were r=0.56, demonstrating good spatial correspondence between the two tracers. Conclusions: We have confirmed hypoxia-specific expression of the HSV1-tkeGFP fusion gene in the R3327-AT/HRE tumor model and demonstrated the utility of this model for the evaluation of radiolabeled hypoxia tracers.

Original languageEnglish (US)
Pages (from-to)821-831
Number of pages11
JournalNuclear Medicine and Biology
Volume36
Issue number7
DOIs
StatePublished - Oct 1 2009

Keywords

  • Cancer
  • Hypoxia
  • Nuclear medicine
  • PET tracer validation
  • Reporter gene

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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