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 (125)I 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. (125)I-mAb RM2 was added into the cell culture media and cellular uptake of (125)I-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 (125)I-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 (125)I-mAb RM2 in the PC-3 and LNCaP cells increased according to the incubation time, while the uptake of (125)I-mAb RM2 in MCF-7 cells did not show any increase up to 6 hours. The increase of (125)I-RM2 uptake was not observed when the PC-3 and LNCaP cells were pre-treated with unlabeled RM2. In the biodistribution studies, (125)I-mAb RM2 showed marked uptake into the implanted PC-3 cells. In PC-3 tumor-bearing mice, the tumor muscle ratio of (125)I-RM2 was increased for up to 72 hours in a time-dependent manner.
CONCLUSIONS: (125)I-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.
Written by:
Hasegawa Y, Oyama N, Nagase K, Fujibayashi Y, Furukawa T, Murayama Y, Arai Y, Saito S, Welch MJ, Yokoyama O. Are you the author?
Department of Urology, Faculty of Medical Sciences, University of Fukui 910-1193, Fukui, Japan.
Reference: Nucl Med Biol. 2012 Jul 3. Epub ahead of print.
doi: 10.1016/j.nucmedbio.2012.05.008
PubMed Abstract
PMID: 22766258
UroToday.com Investigative Urology Section