Transforming Growth Factor-β Suppressed Id-1 Expression in a smad3-Dependent Manner in LoVo Cells

Authors

  • Hongjiang Song,

    1. Department of Surgery, Tumor Hospital of Harbin Medical University, Harbin, China
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    • Hongjiang Song and Baoliang Guo contributed equally to this work.

  • Baoliang Guo,

    1. Department of Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, China
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    • Hongjiang Song and Baoliang Guo contributed equally to this work.

  • Jianguo Zhang,

    1. Department of Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, China
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  • Chunfang Song

    Corresponding author
    1. Department of Surgery, the First Affiliated Hospital of Harbin Medical University, Harbin, China
    • Department of General Surgery, the First Clinical College of Harbin Medical University, You Zheng Street 23, Harbin, 150000, China
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    • Fax: +86-451-84668252


Abstract

TGF-β 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-β 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-β 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-β1 downregulated Id-1 protein expression in LoVo cells. Smad2 and smad3 siRNA inhibited TGF-β1-induced 4×SBE luciferase reporter activity. p38 MAPK siRNA inhibited TGF-β1-induced 3×AP-1 luciferase reporter activity. However, the suppression of Id-1 by TGF-β1 was recovered by smad3 siRNA but not smad2 or p38 MAPK siRNA. Moreover, TGF-β1 stimulated cellular proliferation and p21Waf1 protein expression, which might be mediated by suppressing Id-1 expression. In conclusion, this study demonstrated that TGF-β1 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-β function in colorectal cancer cells. Anat Rec, 2010. © 2009 Wiley-Liss, Inc.

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