The methods used for detection of
prostate cancer and
prostate cancer lymph node metastases in medical diagnostics leave room for improvement. Currently, no means of identifying metastasized lymph nodes other than biopsies is available. Markers which are exclusively found on
prostate cancer cells present a focal point for potential imaging methods. To
complement the established markers like e.g. PCA3-a noncoding
mRNA sequence-and PSA-a
serine protease-we investigated the ectopically expressed
G-protein coupled
olfactory receptor OR1D2 as a possible target for prostate-specific detection with its agonist
bourgeonal which has been conjugated to two different
fluorescent dyes. We performed
mRNA expression analysis of the OR1D2 receptor
mRNA by
reverse transcriptase polymerase chain reaction on LNCaP prostate
carcinoma cells and three other non-prostate derived
carcinoma cell lines. Additionally, we used flow cytometry to investigate the uptake of
fluorescent-dye-bound OR1D2-ligand
bourgeonal into the examined
carcinoma cell lines. Finally, confocal
laser scanning microscopy of in vitro cell culture and in vivo
tumor xenografts on mice was performed. We could confirm OR1D2 receptor
mRNA overexpression as well as stronger uptake of both
bourgeonal conjugates in vitro and in vivo for LNCaP cells compared to the non-prostate derived cell lines. Cytoplasmic accumulation and no adverse effects after in vitro and in vivo application of the conjugates were observed. The conjugates represent a platform for the development of future prostate-specific imaging applications, e.g. detection of metastasized lymph nodes during surgery by intraoperative
laser examination.