Location and Movement of the Oxytocin Receptor Differ Between the Normal and Diseased Prostate.

Background: In normal prostate cells, receptors for oxytocin (OT), a peptide involved in regulating prostate growth are sequestered within membrane microdomains called caveolae. During cancer progression, polymerase-transcript-release factor (PTRF) is downregulated, caveolae structures are lost and receptors move onto the cell membrane. This study investigated whether proteins responsible for caveolae formation were affected by the OT peptide, also, how OT treatment affected oxytocin receptor (OTR) movement within living cells.

Methods: Normal human prostate epithelial cells (PrEC) expressing caveolin and PTRF and androgen-independent (PC3) cancer cells expressing caveolin but not PTRF were used. OTR, caveolin and PTRF expression was determined in human prostate tissue.

Results: PTRF expression decreased in tissue alongside an increase in malignancy. Caveolin-1 expression was downregulated by OT treatment. Caveolin-2 was decreased by OT in PrEC cells but increased in PC3 cells. PTRF was decreased by OT in PrEC. TIRF microscopy showed OTR translocated from caveolae to caveolae in normal cells, whereas OTR moved without restraint in malignant cells, possibly stimulating signaling pathways.

Conclusions: This study provides evidence for the ability of OT to regulate caveolin and PTRF expression. This study elucidates possible mechanisms by which cell receptors and caveolae proteins interact to enhance cell proliferation.