Prostaglandin Receptor Regulation of Kidney Cancer

描述(申请人提供)：肾细胞癌是癌症死亡的主要原因，其发病率在人群中以每年2.5%的速度稳步增长。大约三分之一的患者存在转移性疾病，这些患者的预后很差，中位生存期为10个月。虽然手术对治疗局限性肾细胞癌(RCC)非常有效，但对转移性疾病患者的治疗选择非常有限。因此，了解肾细胞癌中的分子事件将有助于更好地了解肿瘤的分子发病机制，从而为转移性疾病的高度特异性和有效的基于机制的治疗方案打开大门。我们克隆了一种新的透明细胞系RCC(RCC7)，它在小鼠体内具有致瘤和转移作用。基因和蛋白表达分析显示，与正常上皮细胞相比，RCC7细胞存在G蛋白偶联受体信号中间产物的变化，包括Gs和GQ的1个亚单位以及前列腺素E2(PGE2)受体的EP4亚型的表达增加，而小GTP酶失活因子Rap1GAP的表达减少。PGE2促进了Rap1介导的RCC7细胞的侵袭，而Rap1GAP的挽救表达则减弱了PGE2介导的细胞体外侵袭和动物体内转移。基于这些结果，并考虑到先前的知识，我们假设EP4的非调控表达/功能参与了肾癌的侵袭。本应用的具体目的是：[1]利用现有的EP受体特异性激动剂和拮抗剂，并通过RNA干扰抑制EP受体，建立介导肾癌细胞体外侵袭的EP亚型(S)；[2]确定PGE2介导的肾癌细胞侵袭的分子机制，尤其是小GTPase Rap1的激活；以及[3]利用动物模型系统确定EP4和Rap1信号在肾癌肿瘤体内生长和转移中的作用。这些研究的成功结论可能确定EP4和Rap是治疗晚期肾脏恶性肿瘤的有效新药靶点。公共卫生相关性：转移性肾细胞癌(RCC)患者的治疗选择有限，RCC的发生和发展机制尚不完全清楚。我们发现EP4和Rap是肾癌细胞侵袭和转移的介质。靶向干扰EP4信号和失活Rap可能为干预肾癌进展为目前无法治愈的晚期疾病提供了一扇机会之窗。

DESCRIPTION (provided by applicant): Renal cell carcinoma is a leading cause of cancer death, and its incidence is steadily increasing at an annual rate of 2.5% across population groups. Approximately one third of patients present with metastatic disease, and the prognosis of such patients is poor with a median survival of ten months. Although surgery is highly effective for the treatment of localized renal cell carcinoma (RCC), treatment options available for patients with metastatic disease are very limited. Hence, understanding the molecular events operating in RCC will help in gaining better insight into the molecular pathogenesis of the cancer and, therefore, open the door to highly specific and effective mechanism-based treatment options for metastatic disease. We have cloned a new line of clear cell RCC (RCC7) that is tumorigenic and metastatic in mice. Gene and protein expression analyses revealed that the RCC7 cells possess altered levels of G protein-coupled receptor signaling intermediates, including increased expression of the 1 subunits of Gs and Gq, and EP4 subtype of prostaglandin E2 (PGE2) receptor, and decreased expression of the small GTPase inactivator Rap1GAP, in comparison to normal epithelial kidney cells. Treatment with PGE2 promoted the Rap1-mediated RCC7 cell invasion, and the rescued expression of Rap1GAP attenuated the PGE2- mediated cell invasion in vitro and metastasis in animals. Based on these results, and taking into account previous knowledge, we hypothesize that unregulated expression/function of the EP4 is involved in RCC invasion. The specific aims of this application are: [1] To profile EP receptors expression and to establish the EP subtype(s) that mediate the RCC cell invasion in vitro using available EP receptor-specific agonists and antagonists, and EP receptor knockdown with RNAi, [2] To determine the molecular mechanisms responsible for the PGE2-mediated RCC cell invasion with special emphasis on small GTPase Rap1 activation, and [3] To determine the role of EP4 and Rap1 signaling in the in vivo growth and metastasis of RCC tumors using animal model systems. The successful conclusion of these studies may identify EP4 and Rap as novel drug targets effective for the treatment of advanced kidney malignancies. PUBLIC HEALTH RELEVANCE: Patients with metastatic renal cell carcinoma (RCC) have limited treatment options, and mechanisms involved in the initiation and progression of RCC are not fully known. We have identified EP4 and Rap as mediators of invasion and metastasis of RCC cells. Targeted disruption of EP4 signaling and inactivation of Rap may provide a window of opportunity to interfere with progression of kidney cancer to currently incurable advanced disease.