Human Prostate Cancer Metastasis and Laminin Binding Integrins

描述(申请人提供)：我们的目标是了解人类前列腺肿瘤细胞的黏附、迁移，并利用这些信息阻止后续侵袭性扩散到晚期次级骨骼部位。具体地说，我们将通过体外组织培养和体内移植SCID小鼠模型在分子和细胞水平上确定层粘连蛋白结合整合素A6B1、A6pB1和A3B1的作用。我们将把这些发现转化为利用整合素相互作用和侵袭性扩散的阻滞剂。存档的人类前列腺癌骨转移将验证关键结果。几个关键的观察结果刺激了这项工作。首先，层粘连蛋白511结合整合素推动前列腺癌的侵袭和转移。它们在人的前列腺转移性病变中持续表达，包括骨。最近，层粘连蛋白511受体A6整合素是全基因组研究中发现的7个新的前列腺癌易感基因位点之一。最后，A6B1的高表达与癌症患者存活率的降低有关。我们和其他人已经证明，在体内和体外，阻断A6B1的表达或功能可以抑制肿瘤细胞的侵袭和转移。它们如何促进黏附和迁移，以及随后的转移和/或复发尚未完全阐明。核心假设是，层粘连蛋白511在骨中的黏附和定植依赖于层粘连蛋白结合整合素，并受涉及uPA/uPAR轴的新型细胞外蛋白分解调节。早期(通常是临床上看不出来的)骨转移可以为肿瘤细胞提供避难所。肿瘤细胞通过A6pB1从骨骼中转移，可能解释了在初次治疗5到10年后，广泛的骨骼复发作为侵袭性转移性疾病的临床现实。如果被证明是正确的，这一假设可能会有重要的翻译意义。治疗策略将包括采用放射治疗和/或前列腺切除术切除原发灶，并辅以预防性的抗整合素抗体或多肽组合，以消除骨性避难所，从而消除晚期骨复发的潜在来源。这是一种针对粘连依赖型和骨滞留型癌症的癌症控制新概念。我们将利用包括分子细胞生物学、病理学和放射学专家之间的合作在内的一系列专业知识，通过三个具体目标来测试我们的中心假设。所有目标都包含依赖层粘连蛋白511的功能终点，使用体外组织培养方法和体内测试，使用异种骨内注射模型，数字X线片和定量显微CT成像。了解肿瘤细胞在骨骼中黏附依赖的避难所及其后续部署的基本分子基础，将为控制癌细胞向次级骨骼部位迁移和转移的机制提供新的见解。转移到继发部位是骨骼发病率、疾病进展、癌症疼痛或死亡的原因。通过在常规治疗的基础上增加重要的“先发制人”策略，复发疾病有可能被消除。

DESCRIPTION (provided by applicant): Our goal is to understand human prostate tumor cell adhesion, migration and to use this information to block subsequent aggressive spread to late stage secondary skeletal sites. Specifically, we will identify the role of laminin binding integrins A6B1, A6pB1 and A3B1 at the molecular and cellular level using both in vitro tissue culture and in vivo xenograft SCID mouse models. We will translate these findings to utilize blockers of integrin interactions and aggressive spread. Archived human prostate cancer bone metastases will validate key results. Several key observations have stimulated this work. First, laminin 511 binding integrins drive invasion and metastasis of human prostate cancer. They are persistently expressed in human prostate metastatic lesions, including bone. Recently, a laminin 511 receptor, A6 integrin, was 1 of 7 new prostate cancer susceptibility loci discovered in a genome-wide association study. Lastly, elevated expression of A6B1 is correlated with reduced patient survival in cancer. We and others have shown that blocking expression or function of A6B1 curtails invasion and metastasis of tumor cells both in vivo and in vitro. How they facilitate adhesion and migration, with subsequent metastasis and/or recurrent disease has yet to be fully elucidated. The central hypothesis is that laminin 511 adhesion and colonization of cancer cells in bone is dependent upon laminin binding integrins and regulated by novel pericellular proteolysis involving the uPA/uPAR axis. Early (and often clinically inapparent) bone metastasis can provide a sanctuary site for tumor cells. Deployment of tumor cells from bone via A6pB1 may explain the clinical reality of widespread skeletal recurrence as aggressive metastatic disease 5 to 10 years after primary therapy. If proven correct, this hypothesis could have important translational implications. The therapeutic strategy would consist of ablation of the primary lesion using radiotherapy and/or prostatectomy coupled with prophylactic anti-integrin antibodies or peptide combinations to eliminate osseous sanctuary sites, and thereby the potential source of late bone recurrence. This is a new concept of cancer control directed at adhesion dependent and bone resident cancer. We will test our central hypothesis by three specific aims using a combination of expertise including collaborations between experts in Molecular Cellular Biology, Pathology and Radiology. All aims contain functional endpoints of laminin 511 dependent adhesion and migration using in vitro tissue culture methods and in vivo assays, using an intra- osseous injection xenograft model, digital radiographs and quantitative micro CT imaging. Understanding the fundamental molecular basis of adhesion dependent sanctuary of tumor cells in bone and their subsequent deployment will lend novel insight into mechanisms controlling cancer cell migration and metastasis to secondary skeletal sites. Metastasis to secondary sites is a cause of skeletal morbidity, disease progression, cancer pain or death. Recurrent disease could be potentially eliminated by adding important "pre-emptive" strategies to conventional therapy.