Fig. 4.

PHD2 expression can rescue an epithelial phenotype in dedifferentiated cells. (A) Expression of PHD2 in ERβ-ablated cells induces a mesenchymal to epithelial transition. Two clones of ERβ-ablated LNCaP cells (shERβ#1 and shERβ#2) were infected with a PHD2 expression vector or empty vector (control). Expression of PHD2 promotes a more epithelial morphology with and a decrease in mesenchymal markers (vimentin, N-cadherin, and HIF-1α). (B) Expression of PHD2 in dedifferentiated cells induces epithelial differentiation that is dependent on PHD2 activity. PC3-M cells were infected with a PHD2 expression vector or empty vector (control). Note that expression of PHD2 promotes an epithelial phenotype with an increase in E-cadherin and a reduction of HIF-1α and vimentin. Subsequent treatment of the cells with DMOG (100 µM) for 3 d induces dedifferentiation and an increase in HIF-1α and vimentin. The changes in HIF-1α expression in response to PHD2 and DMOG inhibition are consistent with the activity of an HRE reporter (bar graph). (C) Expression of a HIF-1α mutant that is resistant to hydroxylation by PHD2 promotes dedifferentiation in cells with an epithelial phenotype. LNCaP cells were infected with expression vectors containing either wild-type HIF-1α, a mutant HIF-1α, or an empty vector (control). Expression of the mutant HIF-1α promotes dedifferentiation in contrast to wild-type HIF-1α. These morphologic changes are consistent with the changes in HIF-1α and E-cadherin expression (immunoblot) and the activity of an HRE reporter (bar graph: *P < 0.05). (Scale bars, 100 μm.)