64Cu-Labeled Ubiquitin for PET Imaging of CXCR4 Expression in Mouse Breast Tumor

Huiqiang Li, Xiaohui Zhang, Hsuan Yi Wu, Lingyi Sun, Yongyong Ma, Junling Xu, Qing Lin, Dexing Zeng

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Ubiquitin has been recently identified as a chemokine receptor 4 (CXCR4) natural ligand, offering great potential for positron emission computed tomography (PET) imaging of CXCR4 expression. This study reports the preparation and evaluation of (64Cu)-radiolabeled ubiquitin for CXCR4 imaging. The ubiquitin was first fused with a C-terminal GGCGG sequence, and the resulting recombinant ubiquitin derivative UbCG4 was then functionalized with the trans-cyclooctene (TCO) moiety via thiol-maleimide click reaction, followed by 64Cu-radiolabeling through the TCO/Tz (tetrazine)-based Diels-Alder click reaction. In the prepared in vitro studies, the prepared (64Cu)-UbCG4 showed significantly higher specific uptakes in the 4T1 breast cancer cells compared with the uptakes in the CXCR4-knockdown 4T1 cells. In the in vivo evaluation in the 4T1-xenograft mouse model, (64Cu)-UbCG4 demonstrated a similar tumor uptake but much lower backgrounds compared with 64Cu-labeled AMD3465. These results suggested that (64Cu)-UbCG4 could serve as a potent PET tracer for the noninvasive imaging of CXCR4 expression in tumors.

Original languageEnglish (US)
Pages (from-to)12432-12437
Number of pages6
JournalACS Omega
Issue number7
StatePublished - Jul 31 2019

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering


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