Prostaglandin E₂ switches from a stimulator to an inhibitor of cell migration after epithelial-to-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is critical for embryonic development, and this process is recapitulated in adults during wound healing, tissue regeneration, fibrosis and cancer progression. Cell migration is believed to play a key role in both normal wound repair and in abnormal tissue remodeling. Prostaglandin E₂ (PGE₂) inhibits fibroblast chemotaxis, but stimulates chemotaxis in airway epithelial cells. The current study was designed to explore the role of PGE₂ and its four receptors on airway epithelial cell migration following EMT using both the Boyden blindwell chamber chemotaxis assay and the wound closure assay. EMT in human bronchial epithelial cells (HBECs) was induced by TGF-β₁ and a mixture of cytokines (IL-1β, TNF-α, and IFN-γ). PGE₂ and selective agonists for all four EP receptors stimulated chemotaxis and wound closure in HBECs. Following EMT, the EP1 and EP3 agonists were without effect, while the EP2 and EP4 agonists inhibited chemotaxis as did PGE₂. The effects of the EP2 and EP4 receptors on HBEC and EMT cell migration were further confirmed by blocking the expected signaling pathways. Taken together, these results demonstrate that PGE₂ switches from a stimulator to an inhibitor of cell migration following EMT of airway epithelial cells and that this inhibition is mediated by an altered effect of EP2 and EP4 signaling and an apparent loss of the stimulatory effects of EP1 and EP3. Change in the PGE₂ modulation of chemotaxis may play a role in repair following injury.