Fan Minghua, Xu Yongping, Hong Fanzhen, Gao Xiaolin, Xin Gang, Hong Haijie, Dong Lihua, Zhao Xingbo
Cell Physiol Biochem. 2016;38(4):1319-32. doi: 10.1159/000443076. Epub 2016 Mar 24.
BACKGROUND/AIMS: Preeclampsia is an idiopathic and serious complication during gestation in which placental trophoblast cells differentiate into several functional subtypes, including highly invasive extravillous trophoblasts (EVTs). Although the cause and pathogenesis of preeclampsia have remained unclear, numerous studies have suggested that the inadequacy of EVT invasion leads to imperfect uterine spiral artery remodelling, which plays a crucial role in the development of preeclampsia. Rac1, or Ras-related C3 botulinum toxin substrate 1, was found to be a key regulator of the migration, invasion uand apoptosis of various tumour cells. Because EVTs share similar invasive and migratory biological behaviours with malignant cells, this study aimed to determine whether the Rac1 signalling pathway affects trophoblast invasion and is thus involved in the pathogenesis of preeclampsia.
We measured the activity of Rac1 and its downstream targets, β-catenin, Snail and MMP9 in placental tissues from patients experiencing a normal pregnancy and those with preeclampsia. Furthermore, we treated HTR-8/SVneo cells with a shRNA Rac1 vector and the β-catenin inhibitor IWP-2 and explored Rac1 signalling pathway activation as well as the effects of Snail and β-catenin on trophoblast invasion.
In placental samples from patients experiencing a normal pregnancy and those with preeclampsia, active Rac1 levels and MMP9 protein and mRNA levels were significantly decreased in term pregnancy samples compared to early pregnancy samples. Lower levels were found in preeclampsia samples than in normal term pregnancy samples, and these levels significantly declined in severe preeclampsia samples compared with mild preeclampsia samples. Further analyses demonstrated that both Rac1 shRNA and the β-catenin inhibitor significantly suppressed MMP9 and Snail activation in trophoblasts, thus impairing trophoblast invasion. Notably, silencing Rac1 down-regulated the expression of β-catenin in HTR-8/SVneo cells, demonstrating that β-catenin is a downstream effector of Rac1 in trophoblast invasion.
Our data suggest that Rac1-mediated activation of β-catenin might regulate Snail and MMP9 expression subsequently promoting trophoblast invasion in pregnancy.
背景/目的：子痫前期是妊娠期一种特发性严重并发症，胎盘滋养层细胞可分化为多种功能亚型，包括高侵袭性的绒毛外滋养层细胞（EVT）。尽管子痫前期的病因和发病机制尚不清楚，但大量研究表明，EVT侵袭不足会导致子宫螺旋动脉重塑不完善，这在子痫前期的发展中起关键作用。Rac1，即Ras相关的C3肉毒杆菌毒素底物1，被发现是各种肿瘤细胞迁移、侵袭和凋亡的关键调节因子。由于EVT与恶性细胞具有相似的侵袭和迁移生物学行为，本研究旨在确定Rac1信号通路是否影响滋养层细胞侵袭，从而参与子痫前期的发病机制。
我们检测了正常妊娠患者和子痫前期患者胎盘组织中Rac1及其下游靶点β-连环蛋白、Snail和基质金属蛋白酶9（MMP9）的活性。此外，我们用shRNA Rac1载体和β-连环蛋白抑制剂IWP-2处理HTR-8/SVneo细胞，探讨Rac1信号通路激活以及Snail和β-连环蛋白对滋养层细胞侵袭的影响。
在正常妊娠患者和子痫前期患者的胎盘样本中，与早孕样本相比，足月妊娠样本中活性Rac1水平、MMP9蛋白和mRNA水平显著降低。子痫前期样本中的水平低于正常足月妊娠样本，与轻度子痫前期样本相比，重度子痫前期样本中的这些水平显著下降。进一步分析表明，Rac1 shRNA和β-连环蛋白抑制剂均显著抑制滋养层细胞中MMP9和Snail的激活，从而损害滋养层细胞侵袭。值得注意的是，沉默Rac1可下调HTR-8/SVneo细胞中β-连环蛋白的表达，表明β-连环蛋白是Rac1在滋养层细胞侵袭中的下游效应分子。
我们的数据表明，Rac1介导的β-连环蛋白激活可能随后调节Snail和MMP9表达，促进妊娠期滋养层细胞侵袭。
