Connexin expression in nonneoplastic human prostate epithelial cells

Expression of gap-junction proteins connexins (Cx), specifically Cx43, Cx32, and Cx26, in both nontumorigenic (RWPE-1) and tumorigenic (RWPE-2) human prostate epithelial cells as well as in two cell clones (WPEI-7 and WPEI-10) originating from the RWPE-1 cell line was investigated. The aim was to determine whether individual connexins are differentially expressed in cultured cells. Western blot analysis revealed striking differences in the expression of individual connexins in the cell lines studied. In particular, Cx43 is largely expressed in RWPE-1 and WPEI-10 cells, whereas Cx32 is expressed predominantly in RWPE-2 and WPEI-7 cells. In addition, both forskolin and estrone increase Cx43 expression levels in WPEI-10 cells, with no apparent effect on WPEI-7 cells. Conversely, forskolin and especially estrone induce a marked increase of Cx32 in WPEI-7 cells, whereas Cx32 expression is limitedly affected by both agents in WPEI-10 cells. Overall, expression levels of Cx43 and Cx32 appear to be inversely related, with RWPE-1 and WPEI-10 cells having a significantly higher Cx43 to Cx32 ratio than that observed in RWPE-2 and WPEI-7 cells. We recently reported that junctional communication could be rescued in RWPE-1 cells by either forskolin or estrone and that restoration of GJIC is associated with an increase of Cx43 or a decrease of Cx32, or both, eventually leading to a marked rise of the Cx43 to Cx32 ratio. Studies are currently ongoing in our laboratories to assess the potential effect of agents increasing the Cx43 to Cx32 ratio on GJIC activity in these systems.