Transforming growth factor-beta suppressed Id-1 Expression in a smad3-dependent manner in LoVo cells.
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.
Song
Hongjiang
H
Department of Surgery, Tumor Hospital of Harbin Medical University, Harbin, China.
Guo
Baoliang
B
Zhang
Jianguo
J
Song
Chunfang
C
D015153:Blotting, Western; D049109:Cell Proliferation; D002470:Cell Survival; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D020868:Gene Silencing; D006801:Humans; D015151:Immunoblotting; D051798:Inhibitor of Differentiation Protein 1 / Q000378:metabolism*; D008156:Luciferases; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051899:Smad2 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051901:Smad4 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology*; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta; D008156:Luciferases; D048051:p38 Mitogen-Activated Protein Kinases