The mechanism of transforming growth factor beta1 in myofibroblast differentiation / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the mechanism underlying myofibroblast differentiation induced by transforming growth factor (TGF) beta1 in obliterative bronchiolitis following lung transplantation.</p><p><b>METHODS</b>Heterotopic tracheal transplantation was performed in Smad3 wild-type and knock-out mice to simulate the lung transplantation in human. Murine tracheal fibroblasts cultivated in primary culture were used for in vitro study. Immunohistochemistry, immunocytochemistry, Western Blotting, RT-PCR and DNA electrophoresis mobility gel shift assay were conducted to detect the expression of alpha-smooth muscle actin (alphaSMA), the marker of fibroblast-myofibroblast differentiation, and the activation of Smad3, p38 and ERK1/2.</p><p><b>RESULTS</b>In affected airways of experimental obliterative bronchiolitis, abundant expression of alphaSMA were found. In vitro study for tracheal fibroblasts, the activation of Smad3 by TGF-beta1 presents as three major forms, phosphorylation, nuclear translocation and DNA binding. In Smad3 wild-type fibroblasts, TGF-beta1 induces the increase of the myofibroblasts transformation, characterized by the elevation of alphaSMA, both at transcription and protein level. While in Smad3 knock-out fibroblasts, the transformation of myofibroblasts induced by TGF-beta1 is significantly decreased (t = 2.080, P = 0.027; t = 1.982, P = 0.032), but not completely abolished. Further study in Smad3-deficient fibroblasts demonstrates that p38 and ERK1/2 could be activated by TGF-beta1 and result in fibroblast differentiation.</p><p><b>CONCLUSIONS</b>TGF-beta1 could promote the transformation of fibroblasts into myofibroblasts in Smad3 dependent and independent signal pathways, especially the Smad3 dependent path, and result in the development of obliterative bronchiolitis.</p>

The role of Smad4 and MAPK proteins in signal transduction pathway in non-small cell lung cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the expression of Smad4 in non-small cell lung cancer (NSCLC), its correlation with MAPK (mitogen activated protein kinase) and their clinical significance in NSCLC.</p><p><b>METHODS</b>Western blotting and RT-PCR were employed to test 42 resected lung cancers and normal lung tissues for the expression of Smad4. Imunohistochemistry was used to detect Smad4 and subtribes of MAPK in 71 paraffin samples.</p><p><b>RESULTS</b>The level of protein and mRNA expression of Smad4 in lung cancer tissues were 0.2092 +/- 0.1308 and 0.3986 +/- 0. 1982, respectively, lower than those in normal tissues (0.7852 +/- 0.4386 and 1.1206 +/- 0.6772, P < 0.05). The expression of p38, ERK1 and Smad4 was associated with TNM staging (P = 0.000, 0.000 and 0.005, respectively) and JNK1 with tumor location (P = 0.028) and staging (P = 0.000). There was a correlation between p38 and Smad4 (P = 0.000). The expression of Smad4 (P = 0.0001), p38 (P = 0.0000) and JNK1 (P = 0.0208), tumor differentiation (P = 0.0059) and staging (P = 0.0000) were significantly correlated with prognosis of NSCLC by univariate analysis. Smad4 (P = 0.019), p38 (P = 0.044), tumor differentiation (P = 0.003), and staging (P = 0.020) were correlated with prognosis tested by multivariable analysis. Taking p38 and Smad4 together, we found that the negative expression of p38 and positive expression of Smad4 were associated with a better prognosis of NSCLC (P = 0.000).</p><p><b>CONCLUSION</b>Smad4 could be of importance for the initiation and development of NSCLC. There is a significant correlation between main proteins of TGF-beta/smad4 and those of ras-MAPK signal transduction pathways. The expression of Smad4 is inhibited by p38. Smad4, as well as p38, tumor differentiation and staging can be used as prognostic factors of NSCLC.</p>