Tumor necrosis factor-alpha regulates inflammatory and mesenchymal responses via mitogen-activated protein kinase kinase, p38, and nuclear factor kappaB in human endometriotic epithelial cells.
Tumor necrosis factor (TNF)-alpha is central to the endometriotic disease process. TNF-alpha receptor signaling regulates epithelial cell secretion of inflammation and invasion mediators. Because epithelial cells are a disease-inducing component of the endometriotic lesion, we explored the response of 12Z immortalized human epithelial endometriotic cells to TNF-alpha. This report reveals the impact of disruption of established TNF-alpha-induced signaling cascades on the expression of biomarkers of inflammation and epithelial-mesenchymal transition (EMT) from endometriotic epithelial cells. Note that we show the molecular potential of soluble TNF-R1 [TNF binding protein (TBP)] and a panel of small molecule kinase inhibitors to block endometriotic gene expression directly. The TNF-alpha receptor is demonstrated to signal through IkappaB kinase complex (IKK) 2 > IkappaB > nuclear factor kappaB, extracellular signal-regulated kinase > mitogen-activated protein kinase kinase (MEK), p38, and phosphatidylinositol 3-kinase (PI3K) > Akt1/2. TNF-alpha induces the expression of transcripts for inflammatory mediators interleukin (IL)-6, IL-8, regulated on activation normal T cell expressed and secreted, TNF-alpha, granulocyte macrophage-colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein (MCP)-1 and also invasion mediators matrix metalloproteinase (MMP)-7, MMP-9, and intracellular adhesion molecule-1. Indeed, TBP inhibits the TNF-alpha-induced expression of all the above endometriotic genes in 12Z endometriotic epithelial cells. The secretion of IL-6, IL-8, GMCSF, and MCP-1 by TNF-alpha is blocked by TBP. Interestingly, MEK, p38, and IKK inhibitors block TNF-alpha-induced IL-8, IL-6, and GM-CSF secretion and 12z invasion, whereas the PI3K inhibitors do not. The only inhibitor to block MCP-1 expression is the p38 inhibitor. Last, TBP, MEK inhibitor, or p38 inhibitor also block cell surface expression of N-cadherin, a marker of mesenchymal cells. Taken together, these results demonstrate that interruption of TNF-alpha-induced signaling pathways in human endometriotic epithelial cells results in decreased expression and secretion of biomarkers for inflammation, EMT, and disease progression.