The Regulation of UPA and UPAR in Human Carcinoma Cells

描述(申请人提供)：尿激酶型纤溶酶原激活物(UPA)及其受体(UPAR)在多种恶性肿瘤中过表达。体外和体内研究表明，uPA/uPAR在肿瘤的进展和转移中起重要作用。然而，侵袭性癌细胞中uPA/uPAR过度表达的机制尚不清楚。在我们早期的研究中，我们发现1)结构性p38 MAPK活性是稳定uPA/uPAR mRNA所必需的；2)av整合素的表达是提高p38活性和uPA表达的必要条件；3)av整合连接激活了p38并上调了uPA在侵袭性癌细胞中的表达。在我们的初步研究中，我们进一步证明：1)涉及rac1/CDc42-PAK1-MKK3的信号通路对于av整合素介导的p38激活是重要的；2)MAPKAPK2是调节uPA mRNA稳定性的主要p38下游效应器；3)uPA 3‘-UTR中富含AU的元件(ARE)对于p38调控的uPA mRNA稳定性是必不可少的；4)TTP是一种ARE结合蛋白，它破坏了uPA mRNA的稳定性，是p38和MAPKAPK2的直接底物。这项建议试图进一步描述侵袭性癌细胞中维持uPA/uPAR过度表达的机制。本研究有四个具体目的：1.av整合素亚基胞质尾部在αv整合素介导的p38活化和uPAIuPAR上调中的作用。2.Rho GTP酶和PAK1在av介导的p38激活和uPA/uPAR上调中的作用3.p38调节uPA/uPAR基因稳定性的机制。4.腺病毒介导的p38α、uPA和uPAR特异性核酶抑制癌细胞转移的效果这些研究将加深我们对αv整合素介导的信号转导、p38介导的mRNA稳定以及侵袭性癌细胞中uPA/uPAR高表达的机制的理解。更好地了解uPA/uPAR表达的机制可能有助于设计更好的治疗方法来抑制癌细胞的侵袭和转移。

DESCRIPTION (provided by applicant): The overexpression of urokinase plasminogen activator (uPA) and its receptor (uPAR) is detected in various malignancies. Both in vitro and in vivo studies demonstrate that uPA/uPAR play important role in tumor progression and metastasis. However, the mechanisms responsible for uPA/uPAR overexpression in invasive cancer cells remain unclear. In our early studies, we found that 1) the constitutive p38 MAPK activity is required for the stabilization of uPA/uPAR mRNA; 2) av integrin expression is essential for elevated p38 activity and uPA expression; 3) av integnn ligation activates p38 and upregulates uPA expression in invasive cancer cells. In our preliminary studies, we further demonstrated that 1) a signaling pathway involving Rac1/Cdc42-PAK1-MKK3 is important for av integrin-mediatedp38 activation; 2) MAPKAPK2 is a main p38 downstream effector for regulating uPA mRNA stability; 3) The AU-rich element (ARE) in uPA 3'-UTR is essential for p38-regulated uPA mRNA stability; 4) TTP, an ARE binding protein, destabilizes uPA mRNA stability and a direct substrate of p38 and MAPKAPK2. This proposal seeks to further characterize the mechanisms by which the overexpression of uPA/uPAR is maintained in invasive cancer cells. The proposed studies are composed of four specific aims: 1. Role of the cytoplasmic tail of av integrin subunit in alphav integrin-mediated p38 activation and uPAIuPAR upregulation. 2. Role of Rho GTPases and PAK1 in av-mediated p38 activation and uPA/uPAR upregulation. 3. The mechanisms involved in p38-regulated uPA/uPAR mRNA stability. 4. Efficacy of adenovirus-delivered p38alpha, uPA and uPAR-specific ribozymes to suppress cancer cell metastasis. These studies will increase our understanding on alphav integrin-mediated signaling, p38-mediated mRNA stabilization and mechanisms involved in high uPA/uPAR expression in invasive cancer cells. Better defining the mechanism on uPA/uPAR expression may help design better therapeutic approaches to suppress cancer cell invasion and metastasis.