Basic FGF downregulates TSP50 expression via the ERK/Sp1 pathway.
Previous studies demonstrated that the expression of testes-specific protease 50 (TSP50) was increased in breast cancer cells and that overexpression of TSP50 can promote tumorigenesis. Thus, it is important to identify the regulatory mechanisms of TSP50 for tumor therapy. In this study, we elucidated the mechanism underlying TSP50 downregulation by basic fibroblast growth factor (bFGF). We used MDA-MB-231 and HEK293T cell lines to address this issue. RT-PCR and promoter activity assays indicated that bFGF downregulates TSP50 expression via transcriptional activation. We next investigated the signaling pathway that mediated the effect of bFGF on TSP50 transcription, and identified that bFGF induced the phosphorylation of ERK and Sp1. An ERK inhibitor suppressed Sp1 phosphorylation and bFGF-reduced TSP50 expression at the mRNA level. In addition, the dominant negative (DN) mutants of ERK and Sp1 both suppressed the reduction of TSP50 by bFGF. Deletion and mutation analyses indicated that the Sp1 site, located within the +237/+239 region of the human TSP50 promoter, is the major responsive element for bFGF. Taken together, our results strongly suggest that bFGF mediates TSP50 downregulation by ERK activation, leading to the phosphorylation of Sp1 in this process.
Wang
Miao
M
National Engineering Laboratory for Druggable Gene and Protein Screening, Northeast Normal University, Changchun 130024, China.
Bao
Yong-Li
YL
Wu
Yin
Y
Yu
Chun-Lei
CL
Meng
Xiang-Ying
XY
Huang
Yan-Xin
YX
Sun
Ying
Y
Zheng
Li-Hua
LH
Li
Yu-Xin
YX
D002460:Cell Line / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D006801:Humans; D011401:Promoter Regions, Genetic; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D004791:Enzyme Inhibitors; D016329:Sp1 Transcription Factor; D016222:Fibroblast Growth Factor 2; D048049:Extracellular Signal-Regulated MAP Kinases; D012697:Serine Endopeptidases; C446379:testis-specific protease 50