Gastrin-releasing peptide (GRP) belongs to the family of
bombesin-like
peptides. GRP was demonstrated to stimulate the proliferation and invasiveness of
androgen-independent prostate
carcinoma. GRP mediates its action through the membrane-bound receptor, GRP receptor (GRPR), which is characterized by a high-affinity binding for both GRP and
bombesin. In human
prostate cancer tissue, GRPR
mRNA was reported to be detectable in more than 90% but its immunolocalizaition has not been reported. Therefore, in this study we immunolocalized GRPR in 51 human
prostate cancer cases and correlated the findings with several clinicopathological parameters in order to better understand the function and regulation of GRPR in human
prostate cancer. GRPR was immnolocalized in
carcinoma cells and their values were significantly associated with Gleason score and immunoreactivity of
estrogen receptor βcx (ERβcx) that is one of splicing variants of
ligand dependent
transcription factor, ERβ, and considered to be prognostic factor of
prostate cancer patients. The amounts of GRPR and ERβcx
mRNA in three
prostate cancer cell lines PC-3, DU-145 and LNCaP evaluated by quantitative RT-PCR (qPCR) analysis were also significantly correlated. In addition, we established stable transformants of prostate
carcinoma cell line PC-3 introduced with ERβcx, and confirmed that GRPR
mRNA was induced in ERβcx over-expressing PC-3 cells by qPCR analysis. These results also suggest that ERβcx contributes to
prostate cancer development possibly through mediating GRPR expression in
carcinoma cells.