The expression of transforming growth factor-β2 (TGF-β2) appears to play a strong role in the establishment and progression
of glial tumors. In particular, elevated expression of TGF-β2 appears to be responsible for the impaired cellmediated immunity
often observed in patients with a glioblastoma. This study examined the regulation of the TGF-β2 at the transcriptional level
in the U87MG glioblastoma cell line. We demonstrate that a cAMP response element/activating transcription factor (CRE/ATF)
site and an E-box motif located just upstream of the transcription start site are essential for the transcription of the TGF-β2
gene in U87MG cells Gel mobility analysis determined that activating transcription factor-1, and possibly cAMP-responsive
element binding protein binds to the CRE/ATF site, and upsteam stimulatory factor (USF) 1 and USF2 bind to the E-box motif.
Interestingly, expression of a dominant negative USF protein down-regulates TGF-β2 activity by 80–95% in glioblastoma cells.
We conclude that the binding of transcription factors, in particular the USF proteins, to the TGF-β2 promoter is essential
for its expression and possibly its up-regulation in glioblastomas.
Key words U87MG - CRE/ATF - E-box - ATF-1 - CREB - USF