[Effects of SB203580 and WP631 on Smad signal transduction pathway in lung fibroblasts after irradiation].
OBJECTIVE
Radiation pulmonary fibrosis (RPF) is characterized by fibroblast proliferation and excessive accumulation of extracellular matrix (ECM). Transforming growth factor beta (TGFbeta) is a switch factor in the initiation and development of RPF and serves as a therapeutic target. Blocking TGFbeta1 signal transduction pathway might alleviate RPF. This study was to investigate the effects of two Smad pathway inhibitors, SB203580 and WP631, on Smad signal transduction pathway in human lung fibroblasts (HLFs) after irradiation.


METHODS
HLFs were pretreated with 25 micromol/L SB203580 or 5 nmol/L WP631, then irradiated with 3 Gy 60Co gamma rays and stimulated by 10 microg/L TGFbeta1. The transcriptional activity of SP1 and AP1 were measured using electrophoretic mobility shift assay (EMSA). Expressions of Smad3, Smad4, Smad7, p-Smad3 and P21(WAF1/CIP1) were detected by Western blot. The expression of type Iplasminogen activator inhibitor (PAI-I) was detected by immunohistochemical staining The cell cycle was measured by FACS.


RESULTS
After irradiation. with 3 Gy gamma rays and stimulation by TGFbeta1, HLFs pre-incubated with SB203580 or WP631 were increased in G2-M phase and decreased in S phase as compared with cells without pretreatment. p21(WAF1/CIP1) and p-Smad3 were decreased in HLFs pretreated with SB203580, while PAI-1 was decreased in HLFs pretreated with WP631. Furthermore, the transcriptional activity of SP1 and AP1 was inhibited by WP631.


CONCLUSIONS
SB203580 and WP631 can abrogate excessive proliferation, expressions of p21(WAF1/CIP1) and PAI-1 induced by gamma rays and TGFbeta1 in HLFs through blocking Smad signal transduction pathway.
Li
Yang
Y
Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing, 100850, P R China. leeyoung33@vip.sina.com
Song
Liang-Wen
LW
Peng
Rui-Yun
RY
Wang
De-Wen
DW
Jin
Mei-Hong
MH
Gao
Ya-Bing
YB
Ma
Jun-Jie
JJ
D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis; D004247:DNA / Q000378:metabolism; D003630:Daunorubicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects*; D005720:Gamma Rays; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D008168:Lung / Q000166:cytology / Q000528:radiation effects; D017395:Plasminogen Activator Inhibitor 1 / Q000032:analysis; D011725:Pyridines / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects*; D051785:Smad Proteins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D016329:Sp1 Transcription Factor / Q000037:antagonists & inhibitors; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007093:Imidazoles; D017395:Plasminogen Activator Inhibitor 1; D011725:Pyridines; D051785:Smad Proteins; D016329:Sp1 Transcription Factor; D018808:Transcription Factor AP-1; D053773:Transforming Growth Factor beta1; C104426:WP 631; D004247:DNA; C093642:SB 203580; D003630:Daunorubicin