Regulation of cell-to-cell communication in non-tumorigenic and malignant human prostate epithelial cells.

Abstract

Gap-junction-mediated intercellular communication (GJIC) is required for normal development and tissue homeostasis. However, the role of GJIC in human prostate carcinogenesis and progression remains ill-defined. The ability of hormones, anti-hormones, and the anti-hypertensive drug, forskolin, to restore GJIC in non-tumorigenic (RWPE-1 and PWR-1E) and malignant (RWPE-2, LNCaP, DU-145) human prostate epithelial cell lines, was examined by Scrape-Loading/Dye Transfer (SL/DT) and Fluorescence Recovery After Photobleaching (FRAP) methods using an Ultima laser cytometer. Results from both assays show that PWR-1E, RWPE-2, LNCaP, and DU-145 cells have weak or absent GJIC activity. However, the non-tumorigenic RWPE-1 cells showed restoration of some GJIC (nearly 10%) after 1 hr in the FRAP assay. Forskolin and estrone, which increase intracellular cAMP levels, induced a significant and consistent increase (2.8- and 4.4-fold, respectively) in cell-to-cell communication only in the non-tumorigenic RWPE-1 cells. Furthermore, estrone induced a two-fold increase in connexin 43 (Cx43) and a 30% decrease in Cx32 expression, while forskolin caused a 50% reduction in Cx32 with no effect on Cx43 expression in RWPE-1 cells. These data suggest that agents that increase Cx43:Cx32 ratio may be used to restore GJIC in junctionally-deficient, non-tumorigenic immortalized cells, thus providing insights into potential mechanisms responsible for the multistep carcinogenesis in the human prostate.