Xu Guoxiong, Chakraborty Chandan, Lala Peeyush K
Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ont. Canada N6A 5C1.
Biochem Biophys Res Commun. 2003 Jan 10;300(2):383-90. doi: 10.1016/s0006-291x(02)02845-0.
Extravillous trophoblast (EVT) cells of the human placenta proliferate, migrate, and invade the pregnant uterus and its vasculature in order to nourish the fetus. However, the normal EVT cell proliferation, migration, and invasiveness are exquisitely controlled in situ by decidua-produced transforming growth factor-beta (TGF-beta), whereas EVT cancer (choriocarcinoma) cells are TGF-beta-resistant. We found that these cells lack in expression of Smad3, a key transcription factor involved in TGF-beta signaling pathway. To test whether Smad3 restitution restores TGF-beta response in choriocarcinoma cells, we produced a Smad3-expressing cell line (JAR-smad3/c). Since anti-invasive effect of TGF-beta in the normal EVT cells was partly mediated by an upregulation of tissue inhibitor of metalloprotease (TIMP)-1, we examined whether Smad3-restituted JAR cells have restored TGF-beta response of TIMP-1 upregulation. The expression of TIMP-1 mRNA was found to be low in JAR and JAR-smad3/c cells. Moreover, the basal level of secreted TIMP-1 protein was very low in these cells as compared to the normal EVT cells. TGF-beta1 upregulated TIMP-1 mRNA and secreted protein in Smad3-restituted JAR cells as well as in the normal EVT cells, whereas no effect was detected in Smad3-deficient (wild-type) JAR cells. We had earlier shown that Smad3-restituted JAR cells had also restored TGF-beta response of plasminogen activator inhibitor-1 upregulation. However, in vitro functional analysis revealed that, in contrast to the normal EVT cells, anti-invasive action of TGF-beta was not restored in Smad3-restituted JAR cells. Thus, additional factors (possibly low expression of Smad4 and/or other unknown factors) may contribute to refractoriness to anti-invasive action of TGF-beta in JAR cells.
人胎盘的绒毛外滋养层（EVT）细胞增殖、迁移并侵入妊娠子宫及其脉管系统以滋养胎儿。然而，正常的EVT细胞增殖、迁移和侵袭能力在原位受到蜕膜产生的转化生长因子-β（TGF-β）的精确调控，而EVT癌细胞（绒毛膜癌）对TGF-β具有抗性。我们发现这些细胞缺乏Smad3的表达，Smad3是参与TGF-β信号通路的关键转录因子。为了测试Smad3的恢复是否能恢复绒毛膜癌细胞对TGF-β的反应，我们构建了一个表达Smad3的细胞系（JAR-smad3/c）。由于TGF-β对正常EVT细胞的抗侵袭作用部分是由金属蛋白酶组织抑制剂（TIMP）-1的上调介导的，我们研究了恢复Smad3的JAR细胞是否恢复了TGF-β对TIMP-1上调的反应。结果发现，JAR和JAR-smad3/c细胞中TIMP-1 mRNA的表达较低。此外，与正常EVT细胞相比，这些细胞中分泌的TIMP-1蛋白的基础水平非常低。TGF-β1上调了恢复Smad3的JAR细胞以及正常EVT细胞中TIMP-1 mRNA和分泌蛋白的水平，而在缺乏Smad3的（野生型）JAR细胞中未检测到影响。我们之前已经表明，恢复Smad3的JAR细胞也恢复了TGF-β对纤溶酶原激活物抑制剂-1上调的反应。然而，体外功能分析表明，与正常EVT细胞相比，恢复Smad3的JAR细胞中TGF-β的抗侵袭作用并未恢复。因此，其他因素（可能是Smad4表达较低和/或其他未知因素）可能导致JAR细胞对TGF-β的抗侵袭作用产生抗性。
