title: Anti-CXCR4 monoclonal antibody conjugated to ultrasmall superparamagnetic iron oxide nanoparticles in an application of MR molecular imaging of pancreatic cancer cell lines.
abstract: BACKGROUND
  Chemokine receptor 4(CXCR4) plays an important role in the potential growth of pancreatic tumor and its ability to develop metastasis. Ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles offer strong contrast-enhancing effect for MR imaging of pancreatic tissue.
  
  
  OBJECTIVE
  To establish a biomarker-targeted nanoparticulate contrast agent CXCR4-USPIO for pancreatic cancer cell MR imaging and to investigate the relationship between in vitro MR T2 enhancement ratio, ΔR2 values, and the cellular CXCR4 expression levels.
  
  
  METHODS
  The CXCR4 monoclonal antibody and bovine serum albumin (BSA) were bioconjugated with USPIO using carbodiimide. The T2 and T2* values of CXCR4-USPIO, BSA-USPIO, and USPIO were evaluated at the same iron concentration levels. After incubating four pancreatic cancer cell lines (AsPC-1, BxPC-3, CFPAC-1, PANC-1) with CXCR4-USPIO and BSA-USPIO, respectively, changes of T2 values were measured with a clinical 1.5-T MRI scanner. Western blot and immunofluorescence tests were applied to semi-quantitatively analyze the expression levels of CXCR4 in the four cell lines.
  
  
  RESULTS
  MR imaging revealed a linear correlation between ΔR2 and ΔR2* values of CXCR4-USPIO nanoparticles and the iron concentrations. The T2 enhancement ratio and ΔR2 values of AsPC-1, BxPC-3, CFPAC-1, PANC-1 cell lines in the CXCR4-USPIO group exhibited strong correlation with the CXCR4 peptide relative grey values measured by western blot (r = 0.976, P = 0.024; r = 0.959, P = 0.041, respectively) and the mean fluorescence signal intensity detected by laser scanning confocal microscopy (r = 0.996, P = 0.004; r = 0.962, P = 0.038, respectively).
  
  
  CONCLUSIONS
  The targeted probe CXCR4-USPIO was created for MR molecular imaging of pancreatic cancer cell lines. The T2 enhancement ratio and ΔR2 values of CXCR4-USPIO nanoparticles could semi-quantitatively assess the cellular CXCR4 expression levels.
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, PR China.
authors.forename: Yonglan
authors.initials: Y
authors.lastname: He
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.forename: Jing
authors.initials: J
authors.lastname: Lei
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Cao
authors.forename: Shuai
authors.initials: S
authors.lastname: Huang
authors.forename: Jie
authors.initials: J
authors.lastname: Meng
authors.forename: Haiyan
authors.initials: H
authors.lastname: Xu
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Jin
authors.forename: Huadan
authors.initials: H
authors.lastname: Xue
mesh_terms: D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D003911:Dextrans / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D016014:Linear Models; D058185:Magnetite Nanoparticles / Q000737:chemistry / Q000633:toxicity; D018613:Microscopy, Confocal; D053758:Nanoparticles; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D010190:Pancreatic Neoplasms / Q000473:pathology*; D019718:Receptors, CXCR4 / Q000737:chemistry
chemical_list: D000911:Antibodies, Monoclonal; C527276:CXCR4 protein, human; D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D019718:Receptors, CXCR4; C097921:ferumoxtran-10