Department of Surgery, Tumor Hospital of Harbin Medical University, Harbin, China.
Anat Rec (Hoboken). 2010 Jan;293(1):42-7. doi: 10.1002/ar.21012.
TGF-beta plays an important role in regulating cell differentiation and proliferation in human cancers such as colorectal cancer. Id-1 has been identified as a marker in colorectal cancer progression. The aim of this study was to investigate the role of TGF-beta in regulating Id-1 in LoVo cells. siRNA was used to silence smad2, smad3, and p38 MAPK gene expression in Lovo cells. Interference efficiency and the role of TGF-beta on Id-1 expression were analyzed using a luciferase reporter assay, RT-PCR, and Western blotting. Cell viability was determined using the MTT assay. In this study, we demonstrated that TGF-beta1 downregulated Id-1 protein expression in LoVo cells. Smad2 and smad3 siRNA inhibited TGF-beta1-induced 4xSBE luciferase reporter activity. p38 MAPK siRNA inhibited TGF-beta1-induced 3xAP-1 luciferase reporter activity. However, the suppression of Id-1 by TGF-beta1 was recovered by smad3 siRNA but not smad2 or p38 MAPK siRNA. Moreover, TGF-beta1 stimulated cellular proliferation and p21(Waf1) protein expression, which might be mediated by suppressing Id-1 expression. In conclusion, this study demonstrated that TGF-beta1 suppressed Id-1 expression in a smad3-dependent manner in LoVo cells using RNAi technology. These results provide new insight into the mechanisms of TGF-beta function in colorectal cancer cells.
TGF-β 在调节人类癌症（如结直肠癌）中的细胞分化和增殖方面发挥着重要作用。Id-1 已被确定为结直肠癌进展的标志物。本研究旨在探讨 TGF-β 在调节 LoVo 细胞中 Id-1 表达中的作用。使用 siRNA 沉默 Lovo 细胞中的 smad2、smad3 和 p38 MAPK 基因表达。使用荧光素酶报告基因检测、RT-PCR 和 Western blot 分析干扰效率和 TGF-β 对 Id-1 表达的作用。通过 MTT 测定法确定细胞活力。在本研究中，我们证明 TGF-β1 下调 LoVo 细胞中的 Id-1 蛋白表达。Smad2 和 smad3 siRNA 抑制 TGF-β1 诱导的 4xSBE 荧光素酶报告基因活性。p38 MAPK siRNA 抑制 TGF-β1 诱导的 3xAP-1 荧光素酶报告基因活性。然而，smad3 siRNA 而非 smad2 或 p38 MAPK siRNA 恢复了 TGF-β1 对 Id-1 的抑制作用。此外，TGF-β1 刺激细胞增殖和 p21(Waf1)蛋白表达，这可能是通过抑制 Id-1 表达介导的。总之，本研究使用 RNAi 技术证明 TGF-β1 通过 smad3 依赖性方式抑制 LoVo 细胞中的 Id-1 表达。这些结果为 TGF-β 在结直肠癌细胞中的功能机制提供了新的见解。
