Involvement of PI3K/Akt pathway in TGF-beta2-mediated epithelial mesenchymal transition in human lens epithelial cells.
BACKGROUND
Epithelial mesenchymal transition (EMT) of postoperative remnants of lens epithelial cells (LECs) can lead to posterior capsule opacification. This study was designed to determine the effect of signaling pathways that contribute to TGF-beta2-mediated EMT in human lens epithelial B-3 cells (HLEB-3 cells).


METHODS
The HLEB-3 cells were cultured and stimulated with TGF-beta2 at different concentrations for an indicated time. The effect of TGF-beta2 on cell cycle distribution was measured by flow cytometry. Western blot and immunofluorescence were used to analyze changes in connexin 43, fibronectin, desmin and integrin beta(1) protein expression associated with EMT in HLEB-3 cells. Activation of phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways was also detected by Western blot.


RESULTS
The cell cycle progression of HLEB-3 cells was limited, and the cells underwent morphological alteration after treatment with TGF-beta2. Stimulation of HLEB-3 cells with TGF-beta(2) suppressed connexin 43 protein expression, increased fibronectin, desmin and integrin beta1 protein expression. TGF-beta2 activated PI3K/Akt in a time-dependent manner, but not extracellular signal-regulated kinase and p38 MAPK. The activation of PI3K/Akt was necessary for the TGF-beta(2)-stimulated downregulation of connexin 43, which in turn was necessary for TGF-beta2-induced EMT in HLEB-3 cells.


CONCLUSIONS
TGF-beta(2) is a potent growth factor for LEC EMT. TGF-beta(2)-induced EMT in LECs is mediated by the downregulation of connexin 43, which is regulated through the PI3K/Akt pathway.
Yao
Ke
K
Eye Center, Affiliated Second Hospital, College of Medicine, Zhejiang University, Hangzhou, China. xlren@zju.edu.cn
Ye
Pan Pan
PP
Tan
Jian
J
Tang
Xia Jing
XJ
Shen Tu
Xing Chao
XC
D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D018031:Connexin 43 / Q000037:antagonists & inhibitors; D003893:Desmin / Q000378:metabolism; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D008648:Mesoderm / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology*
D002867:Chromones; D018031:Connexin 43; D003893:Desmin; D004791:Enzyme Inhibitors; D005353:Fibronectins; D019012:Integrin beta1; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D053781:Transforming Growth Factor beta2; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one