title: PET of c-Met in Cancer with ⁶⁴Cu-Labeled Hepatocyte Growth Factor.
abstract: The hepatocyte growth factor (HGF) and its receptor, c-Met, are actively involved in tumor progression and metastasis and are closely associated with a poor prognostic outcome for cancer patients. Thus, the development of PET agents that can assess c-Met expression would be extremely useful for diagnosing cancer and subsequently monitoring response to c-Met-targeted therapies. Here, we report the characterization of recombinant human HGF (rh-HGF) as a PET tracer for detection of c-Met expression in vivo.
  
  
  METHODS
  rh-HGF was expressed in human embryonic kidney 293 cells and purified by nickel-nitrilotriacetic acid affinity chromatography. The concentrated rh-HGF was conjugated to 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid and labeled with (64)Cu. c-Met binding evaluation by flow cytometry was performed on both U87MG and MDA-MB-231 cell lines, which have a high level and a low level, respectively, of c-Met. PET imaging and biodistribution studies were performed on nude mice bearing U87MG and MDA-MB-231 xenografted tumors.
  
  
  RESULTS
  The rh-HGF expression yield was 150-200 μg of protein per 5 × 10(6) cells after a 48-h transfection, with purity of approximately 85%-90%. Flow cytometry examination confirmed that rh-HGF had a strong and specific capacity to bind to c-Met. After (64)Cu labeling, PET imaging revealed specific and prominent uptake of (64)Cu-NOTA-rh-HGF in c-Met-positive U87MG tumors (percentage injected dose per gram, 6.8 ± 1.8 at 9 h after injection) and significantly lower uptake in c-Met-negative MDA-MB-231 tumors (percentage injected dose per gram, 1.8 ± 0.6 at 9 h after injection). The fact that sonication-denatured rh-HGF had significantly lower uptake in U87MG tumors, along with histology analysis, confirmed the c-Met specificity of (64)Cu-NOTA-rh-HGF.
  
  
  CONCLUSIONS
  This study provided initial evidence that (64)Cu-NOTA-rh-HGF visualizes c-Met expression in vivo, an application that may prove useful for c-Met-targeted cancer therapy.
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Haiming
authors.initials: H
authors.lastname: Luo
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Hao
authors.initials: H
authors.lastname: Hong
authors.affiliation: Promega Corp., Madison, Wisconsin.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Slater
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Graves
authors.affiliation: Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin; and.
authors.forename: Sixiang
authors.initials: S
authors.lastname: Shi
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin.
authors.forename: Yunan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin; and.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Nickles
authors.affiliation: Promega Corp., Madison, Wisconsin.
authors.forename: Frank
authors.initials: F
authors.lastname: Fan
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin Materials Science Program, University of Wisconsin-Madison, Madison, Wisconsin; and University of Wisconsin Carbone Cancer Center, Madison, Wisconsin wcai@uwhealth.org.
authors.forename: Weibo
authors.initials: W
authors.lastname: Cai
mesh_terms: D000818:Animals; D001692:Biological Transport; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D045744:Cell Line, Tumor; D003301:Copper Radioisotopes; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000000981:diagnostic imaging / Q000473:pathology*; D057809:HEK293 Cells; D017228:Hepatocyte Growth Factor / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D006571:Heterocyclic Compounds / Q000737:chemistry; D006573:Heterocyclic Compounds, 1-Ring; D006801:Humans; D051379:Mice; D049268:Positron-Emission Tomography / Q000379:methods*; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D003301:Copper Radioisotopes; D006571:Heterocyclic Compounds; D006573:Heterocyclic Compounds, 1-Ring; C048993:1,4,7-triazacyclononane-N,N',N''-triacetic acid; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met
keywords: 64Cu; c-Met; cancer; hepatocyte growth factor (HGF); positron emission tomography (PET)
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