Aptamer targeting of osteopontin in hepatocellular cancer

描述（由申请人提供）：肝细胞癌（HCC）是世界上最常见的实体器官肿瘤。在美国，HCC的发病率在过去二十年中几乎翻了一番。HCC与极差的预后相关，因为系统治疗在很大程度上是非特异性和无效的。骨桥蛋白（OPN）是HCC生长和转移的关键介质，近年来受到广泛关注。OPN在肿瘤中过表达，是晚期转移性癌症中恶性细胞分泌的主要磷蛋白，是肿瘤细胞迁移和转移的关键介质，并且是HCC进展和转移的主要标志物。体内和体外功能获得和丧失实验都证明了OPN在HCC的局部生长和转移中的关键功能作用。RNA适体是一类独特的治疗剂，其具有优于当前疗法的几个优点，因此代表了分子靶向治疗的令人兴奋的机会。适体是短的ss RNA寡核苷酸，其呈现稳定的三维形状以紧密且特异性地结合所选择的蛋白质靶标以引发生物反应。适体具有低纳摩尔至皮摩尔范围内的结合亲和力，是热稳定的，缺乏免疫原性，并且具有最小的批间变异性以有效靶向细胞外靶标。作为一种分泌型磷蛋白，OPN是RNA适配体介导的肝癌生长和转移阻断的理想治疗靶点。我们已经分离了针对人OPN的RNA适体（Kd ~18 nM）。在此资助申请中，我们建议：1）表征我们的RNA适体对OPN-细胞表面结合、信号转导和粘附/迁移/侵袭的体外作用，2）确定OPN-R3在人HCC的鼠异种移植模型中抑制局部生长、转移和消退的体内功效，和3）确定OPN适体的药效学和毒理学特征以优化体内给药。我们的最终目标是将这种OPN适体转化为HCC治疗的临床领域。该基金利用RNA适体这一新的治疗技术来抑制世界上最常见的实体器官肿瘤原发性肝癌的生长和扩散。

DESCRIPTION (provided by applicant): Hepatocellular cancer (HCC) is the most common solid organ tumor in the world. In the US, the incidence of HCC has nearly doubled over the past two decades. HCC is associated with an extremely poor prognosis because systemic therapies are largely nonspecific and ineffective. Attention has recently focused upon osteopontin (OPN) as a key mediator of HCC growth and metastasis. OPN is overexpressed in tumors, is the major phosphoprotein secreted by malignant cells in advanced metastatic cancer, is a key mediator of tumor cell migration and metastasis, and is a lead marker of HCC progression and metastasis. Both in vivo and in vitro gain- and loss-of-function experiments demonstrate a crucial functional role for OPN in local growth and metastasis of HCC. RNA aptamers are a unique class of therapeutic agents that carries several advantages over current therapies and as such, represent an exciting opportunity for molecularly targeted therapy. Aptamers are short ss RNA oligonucleotides that assume a stable three-dimensional shape to tightly and specifically bind selected protein targets to elicit a biological response. Aptamers possess binding affinities in the low nanomolar to picomolar range, are heat stable, lack immunogenicity, and possess minimal interbatch variability to effectively target extracellular targets. As a secreted phosphoprotein, OPN is an ideal therapeutic target for RNA aptamer mediated blockade of HCC growth and metastasis. We have isolated an RNA aptamer directed against human OPN (Kd ~18 nM). In this grant application, we propose to: 1) characterize the in vitro effect of our RNA aptamer on OPN-cell surface binding, signal transduction and adhesion/migration/invasion, 2) determine the in vivo efficacy of OPN-R3 for inhibition of local growth, metastasis and regression in a murine xenograft model of human HCC, and 3) determine the pharmacodynamic and toxicologic profile of the OPN aptamer to optimize in vivo dosing. It is our ultimate goal to translate this OPN aptamer into the clinical realm for HCC therapy. This grant utilizes RNA aptamers, a new therapeutic technology, to inhibit growth and spread of primary liver cancer, the most common solid organ tumor in the world.