Goukassian David A, Kishore Raj, Krasinski Kevin, Dolan Christine, Luedemann Corinne, Yoon Young-sup, Kearney Marianne, Hanley Allison, Ma Hong, Asahara Takayuki, Isner Jeffrey M, Losordo Douglas W
Department of Medicine, Division of Cardiovascular Research, St Elizabeth's Medical Center, Boston, Mass, USA.
Circ Res. 2003 Jul 25;93(2):162-9. doi: 10.1161/01.RES.0000082980.94211.3A. Epub 2003 Jun 26.
Tumor necrosis factor-alpha (TNF-alpha) is expressed locally in the vessel wall after angioplasty and induces growth arrest and apoptosis in endothelial cells (ECs), thereby delaying reendothelialization. Prior studies have shown that direct antagonism of TNF-alpha, using a systemically administered soluble receptor, can enhance endothelial recovery and reduce neointimal thickening. These studies have also shown that downregulation of the transcription factor E2F1 was a key mechanism of TNF's effect on ECs. We now show that Ad-E2F1 overexpression at sites of balloon injury accelerates functional endothelial recovery, consistent with the prior in vitro findings. Moreover these studies also reveal divergent effects of TNF-alpha and overexpression of E2F1 on ECs versus VSMCs. TNF-alpha exposure of VSMCs had no affect on proliferation or apoptosis, in contrast to the effect seen in ECs. In Ad-E2F1-transduced VSMCs, however, TNF-alpha-induced marked apoptosis in contrast to the survival effect seen in ECs. Finally, these studies suggest that differential activation of NF-kappaB may play a key role in mediating these opposing effects. Nuclear translocation and transcriptional activity of NF-kappaB was markedly attenuated in Ad-E2F1-transduced VSMCs, whereas it remained active in similarly treated ECs when the cells were exposed to TNF-alpha. These studies reveal that overexpression of Ad-E2F1 primes VSMCs to TNF-alpha-induced apoptosis. Furthermore, E2F1 potentiates VSMC death by blocking antiapoptotic signaling pathway through inhibition of NF-kappaB activation. The divergent responses of VSMCs and ECs to E2F1 overexpression provide unique therapeutic possibilities: simultaneously targeting the cell cycle of two different cell types, within same tissue microenvironment resulting in opposite and biologically complimentary effects.
肿瘤坏死因子-α（TNF-α）在血管成形术后于血管壁局部表达，并诱导内皮细胞（ECs）生长停滞和凋亡，从而延迟再内皮化。先前的研究表明，使用全身给药的可溶性受体直接拮抗TNF-α可促进内皮恢复并减少内膜增厚。这些研究还表明，转录因子E2F1的下调是TNF对ECs作用的关键机制。我们现在表明，在球囊损伤部位过表达Ad-E2F1可加速功能性内皮恢复，这与先前的体外研究结果一致。此外，这些研究还揭示了TNF-α和E2F1过表达对ECs与血管平滑肌细胞（VSMCs）的不同影响。与在ECs中看到的效应相反，VSMCs暴露于TNF-α对增殖或凋亡没有影响。然而，在Ad-E2F1转导的VSMCs中，TNF-α诱导明显的凋亡，这与在ECs中看到的存活效应相反。最后，这些研究表明，NF-κB的差异激活可能在介导这些相反效应中起关键作用。在Ad-E2F1转导的VSMCs中，NF-κB的核转位和转录活性明显减弱，而当细胞暴露于TNF-α时，在同样处理的ECs中它仍保持活性。这些研究表明，Ad-E2F1的过表达使VSMCs对TNF-α诱导的凋亡敏感。此外，E2F1通过抑制NF-κB激活来阻断抗凋亡信号通路，从而增强VSMC死亡。VSMCs和ECs对E2F1过表达的不同反应提供了独特的治疗可能性：在同一组织微环境中同时靶向两种不同细胞类型的细胞周期，产生相反且具有生物学互补性的效应。
