[Regulation of Smad7 gene by TGF-beta 1 in process of malignant transformation].
OBJECTIVE
Escape from transforming growth factor-beta(TGF-beta)-induced inhibition of growth and proliferation may contribute to tumorigenesis. Smad7 is inhibitory Smads of TGF-beta s signal transduction pathway and prevents TGF-beta signaling. The disorder of Smad7 may lead to the perturbation of TGF-beta signal pathway. In this study, The authors analyzed the expression of Smad7 mRNA and the regulation of Smad7 gene by TGF-beta 1 in the process of malignant transformation of BEP2D cells to investigate the mechanism of cells malignant transformation.


METHODS
Cells were cultured and stimulated with TGF-beta 1 followed by RNA extraction. Purified total RNA from TGF-beta 1 treated cells and untreated controls and performed an expression analysis with a human Smad7-specific probe applying Northern blot. As a loading control for the Northern experiment, the membrane was hybridized with a human glyceraldehyde-3-phosphate dehydrogenase(GAPDH) probe. Proteins were extracted from BEP2D and BERP35T-2 cells, then perform Western blot to examine the expression level of TGF-beta 1.


RESULTS
Before stimulation with TGF-beta 1, the expression level of Smad7 in the BERP35T-2 cells were higher than that in the BEP2D cells. When stimulated with TGF-beta 1, Smad7 expression levels was upregulated evidently in BEP2D cells, but not significant in BERP35T-2 cells. The expression level of endogenetic TGF-beta 1, BERP35T-2 cells was a little higher than BEP2D cells.


CONCLUSIONS
Over expression of Smad7 mRNA and down-regulation of the cells' responsiveness to TGF-beta 1 in human lung cancer cell line which induced by alpha-particles should be one of the mechanism of radiation induced lung cancer.
Huo
Yan-ying
YY
Department of Molecular Toxicology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China.
Zhang
Kai-tai
KT
Li
Bang-yin
BY
Duan
Rui-feng
RF
Fan
Bao-xing
BX
Xiang
Xiao-qiong
XQ
Hu
Ying-chun
YC
Xie
Ling
L
Wu
De-chang
DC
D015153:Blotting, Western; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D051906:Smad7 Protein; D015534:Trans-Activators / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; C497806:SMAD7 protein, human; D051906:Smad7 Protein; C508960:TGFB1 protein, human; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1