Tummalapalli Padmaja, Gondi Christopher S, Dinh Dzung H, Gujrati Meena, Rao Jasti S
Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL 61605, USA.
Int J Oncol. 2007 Jul;31(1):5-17.
Meningiomas are the most commonly occurring tumors of the central nervous system including the brain and spinal cord. Malignant meningiomas are highly aggressive and frequently recur after surgical resection of the tumor. Our previous studies have reported that urokinase plasminogen activator receptor (uPAR) and matrix metalloproteinase-9 (MMP-9) play important roles in tumor progression. In the present study, we have attempted to evaluate the roles of these molecules in the malignant meningioma tumor microenvironment and to determine the effectiveness of using single or bicistronic small interfering RNA constructs for uPAR and MMP-9 on tumor cell proliferation, migration, invasion, angiogenesis and regression of pre-established orthotopic tumors. Transfection of single or bicistronic constructs downregulated uPAR and MMP-9 in meningioma cells compared to controls. A significant reduction in tumor invasion was determined with matrigel gel and spheroid invasion assays in meningioma cells after transfection of these plasmids. Furthermore, downregulation of uPAR and MMP-9 reduced migration of tumor spheroids on vitronectin-coated plates. uPAR and MMP-9 downregulation suppressed capillary network formation, in both in vitro and in vivo models. Also, it is well known that tumor cells manipulate intracellular signaling pathways to aid in various processes involved in tumor progression. Our study revealed that downregulation of uPAR and MMP-9 leads to a decrease in the activation of some of the important enzymes participating in the MAPK and PI3 kinase pathways, which in turn, might decrease cell survival and proliferation. In addition, we analyzed the efficiency of RNAi-mediated targeting of uPAR and MMP-9 in pre-established tumor growth in vivo. We observed a significant regression of pre-established orthotopic tumors upon RNAi-mediated targeting of uPAR and MMP-9. In addition, the present study indicated that targeting both the proteins simultaneously augmented the therapeutic treatment of human meningiomas.
脑膜瘤是中枢神经系统（包括脑和脊髓）中最常见的肿瘤。恶性脑膜瘤具有高度侵袭性，在肿瘤手术切除后经常复发。我们之前的研究报道，尿激酶型纤溶酶原激活物受体（uPAR）和基质金属蛋白酶-9（MMP-9）在肿瘤进展中起重要作用。在本研究中，我们试图评估这些分子在恶性脑膜瘤肿瘤微环境中的作用，并确定使用针对uPAR和MMP-9的单顺反子或双顺反子小干扰RNA构建体对肿瘤细胞增殖、迁移、侵袭、血管生成以及已建立的原位肿瘤消退的有效性。与对照组相比，转染单顺反子或双顺反子构建体可下调脑膜瘤细胞中的uPAR和MMP-9。在转染这些质粒后，通过基质胶凝胶和球体侵袭试验确定脑膜瘤细胞的肿瘤侵袭显著减少。此外，uPAR和MMP-9的下调减少了肿瘤球体在玻连蛋白包被平板上的迁移。在体外和体内模型中，uPAR和MMP-9的下调均抑制了毛细血管网络的形成。同样，众所周知，肿瘤细胞操纵细胞内信号通路以辅助肿瘤进展涉及的各种过程。我们的研究表明，uPAR和MMP-9的下调导致参与丝裂原活化蛋白激酶（MAPK）和磷脂酰肌醇-3激酶（PI3激酶）途径的一些重要酶的活化减少，这反过来可能会降低细胞存活和增殖。此外，我们分析了RNA干扰介导的针对uPAR和MMP-9在体内已建立肿瘤生长中的靶向效率。我们观察到，在RNA干扰介导的针对uPAR和MMP-9的靶向作用下，已建立的原位肿瘤显著消退。此外，本研究表明，同时靶向这两种蛋白质可增强对人类脑膜瘤的治疗效果。
