Folate Receptor-Mediated siRNA Delivery to Cancer Cells

描述（由申请人提供）：通过小干扰RNA（siRNA）进行的转录后基因沉默已发展成为一种高效和序列特异性下调任何靶基因的有力工具。原则上，siRNA可能成为开发下一代高效低毒抗病毒和抗癌药物的基础。然而，目前没有治疗上可接受的siRNA递送方法。虽然叶酸受体（FR）介导的通过内吞作用向癌细胞递送功能剂已显示出对FR阳性癌细胞是有效的和高度特异性的，但叶酸和siRNA之间的直接偶联的化学直到现在还不容易实现。利用Huang（PI）实验室最近开发的RNA生物缀合方法，这项拟议的研究将开发一种新的基于叶酸受体的siRNA递送策略，以对抗FR表达癌细胞中的特定靶基因。结合FR介导的药物递送和RNA干扰（RNAi）等不同领域的最新进展，以及PI在化学/RNA和Dr. Quo（co-Pi）在细胞生物学方面的专业知识，我们将合成叶酸偶联的siRNA并研究其细胞递送和功能，靶向癌细胞标记物尿激酶纤溶酶原激活物受体（uPAR）。我们将检验通过漂浮物缀合的siRNA下调癌细胞中uPAR表达将有效抑制与肿瘤生长相关的uPAR的细胞活性的假设。使用KB癌细胞（人鼻咽表皮样癌细胞系）分析叶酸-siRNA的递送效率和特异性。将通过在mRNA和蛋白质水平测定uPAR的表达以及通过uPAR的细胞功能分析来评估RNAi效应。我们期望在KB细胞中递送针对uPAR的叶酸-siRNA将比目前可用的其他方法更有效和特异。因此，预期通过uPAR沉默抑制肿瘤生长。拟议研究的结果可能会导致FR介导的siRNA递送针对FR表达癌细胞中特定靶基因的一般策略和方法的开发，因此可能直接导致癌症治疗应用。

DESCRIPTION (provided by applicant): Posttranscriptional gene silencing by small interfering RNA (siRNA) has evolved into a powerful tool for down regulation of any target gene(s) with both high efficiency and sequence specificity. In principle, siRNA may become the basis for developing the next generation of antiviral and anti-cancer agents with high potencies and low side toxicities. However, no therapeutically acceptable delivery methods of siRNA are currently available. Although folate receptor (FR)-mediated delivery of functional agents by endocytosis to cancer cells has been shown to be efficient and highly specific towards FR-positive cancer cells, the chemistry of direct coupling between folate and siRNA has not been readily achievable until now. Capitalizing on the recent RNA bio-conjugation methods developed in the Huang (PI) laboratory, this proposed research will develop a novel folate receptor-based siRNA delivery strategy against specific target genes in FR-expressing cancer cells. Integrating the recent advances in such diverse areas as FR-mediated drug delivery and RNA interference (RNAi) with the expertise of the PI in chemistry/RNA and Dr. Quo (co-Pi) in cell biology, we will synthesize folate-conjugated siRNA and investigate their cellular delivery and functions, targeting a cancer cell marker, urokinase plasminogen activator receptor (uPAR). We will test the hypothesis that down- regulation uPAR expression in cancer cells by floate-conjugated siRNA will effectively inhibit the cellular activity of uPAR associated with tumor growth. Both the delivery efficiency and specificity of Folate-siRNA will be analyzed using KB cancer cells (a human nasopharyngeal epidermoid carcinoma cell line). RNAi effects will be assessed by determining the expression of uPAR at mRNA and protein levels and by cellular functional analysis of uPAR. We expect that the delivery of Folate-siRNA against uPAR in KB cells will be more efficient and specific than other current available methods. As a consequence, tumor growth suppression through uPAR silencing is expected. Results from the proposed research will likely lead to the development of general strategies and methods for FR-mediated delivery of siRNA against specific target genes in FR-expressing cancer cells and, therefore, may lead directly to cancer therapeutic applications.