[Effects of transforming growth factor-β2 on transdifferentiation, extracellular matrix synthesis and connective tissue growth factor expression of human lens epithelium cells].

OBJECTIVE: To explore the effects of transforming growth factor-β2 (TGF-β2) on the transdifferentiation, extracellular matrix synthesis and connective tissue growth factor (CTGF) expression in human lens epithelium cells (HLEC) in vitro. METHODS: HLEC were incubated with different concentrations of TGF-β2 (0.0, 0.1, 1.0 and 10.0 µg/L) for 24 h in vitro. The morphological changes of HLEC were observed under inverted phase-contrast microscope. The expression of CTGF and α-smooth muscle actin (α-SMA, as a landmark protein of epithelial mesenchymal transition) in HLEC was measured by immunofluorescence method. Real-time PCR and Western blot were used to evaluate the expression of CTGF, α-SMA, fibronectin (Fn) and COL-I (as the major components of extracellular matrix) after stimulating by TGF-β2. RESULTS: Normal HLEC presented polygonal shape and were anchorage-dependent. After incubated with different concentrations of TGF-β2 for 24 h, the morphology of polygonal HLEC was changed into fibroblast-like shape and changed from monolayer and to multilayer cells, and the intercellular space became bigger. CTGF and α-SMA were expressed in the cytoplasm after induction of TGF-β2. Expression of CTGF in HLEC was increased with increasing concentrations of TGF-β2 (CTGF protein expression: 0.53 ± 0.03, 0.73 ± 0.01, 0.65 ± 0.03 in cells cultured with 0.1, 1.0 and 10 µg/L TGF-β2, respectively; CTGF gene induction: 1.00 ± 0.00, 7.18 ± 0.41, 12.88 ± 0.45, 32.84 ± 1.61 in cells cultured with 0.0, 0.1, 1.0 and 10.0 µg/L TGF-β2, respectively) (F = 77.55, P < 0.05; F = 379.0, P < 0.05). TGF-β2 could induce HLEC transdifferentiation and accelerate. α-SMA expression was increased by TGF-β2 dose-dependently (protein expression: 0.48 ± 0.01,0.78 ± 0.04, 0.69 ± 0.04; gene induction: 1.00 ± 0.00, 2.30 ± 0.22, 3.1 ± 0.21, 3.86 ± 0.10) (F = 62.73, P < 0.05; F = 80.22, P < 0.05). TGF-β2 also promoted expression of Fn and COL-I in a dose-dependent manner (COL-I gene induction: 1.00 ± 0.00, 5.52 ± 0.96, 18.31 ± 1.2, 82.51 ± 1.45;COL-I protein expression: 0.78 ± 0.05, 1.15 ± 0.11, 2.16 ± 0.14; Fn gene induction: 1.00 ± 0.00, 2.36 ± 0.25, 3.27 ± 0.24, 4.25 ± 0.24; Fn protein expression: 0.64 ± 0.01,0.95 ± 0.02, 1.23 ± 0.14) (F = 1881.52, 105.30, P < 0.05; F = 64.44, 51.81, P < 0.05). CONCLUSION: TGF-β2 induces the expression of CTGF by HLEC, promotes transdifferentiation of and extracellular matrix synthesis by HLEC.