Monoclonal antibody RM2 as a potential ligand for a new immunotracer for prostate cancer imaging

Yoko Hasegawa, Nobuyuki Oyama, Keiko Nagase, Yasuhisa Fujibayashi, Takako Furukawa, Yasuko Murayama, Yoichi Arai, Seiichi Saito, Michael J. Welch, Osamu Yokoyama

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Objectives: To investigate the potential of monoclonal antibody (mAb) RM2 as a ligand for a radioimmunotracer for prostate cancer imaging. Methods: Labeling was conducted with mAb RM2 and 125I using the chloramine-T method. The cell study was conducted with PC-3 and LNCaP, which are prostate cancer cell lines, and MCF-7, which is a breast cancer cell line. The cells were treated or untreated with unlabeled mAb RM2 to block the haptoglobin-β chains expressed on the surface of the prostate cancer cells. 125I-mAb RM2 was added into the cell culture media and cellular uptake of 125I-mAb RM2 was evaluated at 1, 3 and 6 hours of incubation. For the in vivo biodistribution study, PC-3 cells were implanted in athymic male mice. The animals were injected intravenously with 125I-mAb RM2. At 24, 48 and 72 hours after tracer injection, the animals were sacrificed and the activity levels of blood and tissue samples were determined. Results: The uptake of 125I-mAb RM2 in the PC-3 and LNCaP cells increased according to the incubation time, while the uptake of 125I-mAb RM2 in MCF-7 cells did not show any increase up to 6 hours. The increase of 125I-RM2 uptake was not observed when the PC-3 and LNCaP cells were pre-treated with unlabeled RM2. In the biodistribution studies, 125I-mAb RM2 showed marked uptake into the implanted PC-3 cells. In PC-3 tumor-bearing mice, the tumor muscle ratio of 125I-RM2 was increased for up to 72 hours in a time-dependent manner. Conclusions: 125I-mAb RM2 showed excellent prostate cancer cell targeting in vitro and in vivo. Therefore, mAb RM2 seems to be a potential candidate for an immunoligand for prostate cancer imaging.

Original languageEnglish
Pages (from-to)944-947
Number of pages4
JournalNuclear Medicine and Biology
Issue number7
Publication statusPublished - 2012 Oct


  • IgM
  • Monoclonal antibody
  • Prostate cancer
  • RM2
  • Radioimmunoligand

ASJC Scopus subject areas

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


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