Down-regulation of uPAR and uPA activates caspase-mediated apoptosis and inhibits the PI3K/AKT pathway.
Down-regulation of uPAR and uPA activates caspase-mediated apoptosis and inhibits the PI3K/AKT pathway.
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DOI：
10.3892/ijo.31.1.19
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发表时间：
2007-07
影响因子：
5.2
通讯作者：
C. Gondi;N. Kandhukuri;D. Dinh;M. Gujrati;J. S. Rao
中科院分区：
文献类型：
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作者：
C. Gondi;N. Kandhukuri;D. Dinh;M. Gujrati;J. S. Rao
尿激酶纤溶酶原激活物（uPA）及其受体（uPAR）在侵袭和增殖过程中起重要作用。越来越多的证据表明，uPA系统通过几种不同的机制促进肿瘤转移，而不仅仅是通过分解ECM。在本研究中，我们利用rnai介导的uPAR和uPA同时下调来确定信号通路分子和caspase介导的细胞凋亡。在我们的体外实验中，我们观察到基于质粒的rnai介导的SNB19人胶质瘤细胞中uPAR和uPA的下调导致uPAR蛋白水平和uPA酶活性降低。此外，我们观察到ras激活的通路分子如FAK、p38MAPK、JNK和ERK1/2，以及mek激活的磷脂酰肌醇3-激酶（PI3k）通路的磷酸化减少，p-AKTser473和p-mTORser2448的去磷酸化也延迟，提示uPAR-uPA系统的反馈信号机制。caspase 8的激活伴随着细胞色素c的释放和PARP的裂解也被观察到，这表明fas介导的凋亡。使用FMK-VAD-FAK肽与FITC偶联表明多胱天蛋白酶的激活，这伴随着细胞核碎片化的存在。我们的研究为uPAR-uPA系统的反馈反应的存在提供了证据，表明uPAR的多方面作用，以及同时靶向uPAR和uPA治疗癌症患者的潜力。
Urokinase plasminogen activator (uPA) and its receptor (uPAR) play a major role in invasion and proliferation. A growing body of evidence has suggested that the uPA system promotes tumor metastasis by several different mechanisms, and not just solely by breaking down the ECM. In this study we have used RNAi-mediated simultaneous down-regulation of uPAR and uPA to determine the signaling pathway molecules and caspase-mediated apoptosis. From our in vitro experiments, we have observed that plasmid-based RNAi-mediated down-regulation of uPAR and uPA in SNB19 human glioma cells caused a decrease in the levels of uPAR protein and uPA enzyme activities. In addition, we observed a decrease in the phosphorylation of the Ras-activated pathway molecules such as FAK, p38MAPK, JNK and ERK1/2, as well as the MEK-activated phosphatidylinositol 3-kinase (PI3k) pathway, and also retarded the dephosphorylation of p-AKTser473 and p-mTORser2448, indicative of a feedback signaling mechanism of the uPAR-uPA system. Activation of caspase 8 accompanied by the release of cytochrome c and cleavage of PARP was also observed and indicative of Fas-mediated apoptosis. The use of FMK-VAD-FAK peptides coupled with FITC indicated activation of polycaspases, which was accompanied by the presence of fragmented nuclei. Our studies provide evidence for the presence of a feedback response of the uPAR-uPA system indicative of the multifaceted role of uPAR, and also the therapeutic potential of simultaneously targeting uPAR and uPA in cancer patients.