INTEGRIN DISTRIBUTION AND FUNCTION IN TUMOR CELLS

整合素是一个复杂的细胞表面受体家族， 细胞-基质和细胞-细胞粘附。大多数已知的整合素识别 细胞外基质配体，包括纤连蛋白，层粘连蛋白，胶原蛋白， 玻连蛋白和腱生蛋白。一些整合素介导细胞间的相互作用 通过与其他膜蛋白结合，比如I-CAM有力的初步证据 提示沿着其他类型的细胞粘附受体， 整联蛋白家族的许多成员有助于肿瘤转移。 整合素是几年前才发现的，从那以后，大约有20种整合素被发现。 已经描述了该主要基因家族的成员。的表达 其中大多数是发育调节的，在某些情况下是受限制的 特定的细胞类型。很有可能，许多额外的数字， 这个家庭还没有被发现。更好地了解 肿瘤细胞整合素的结构和功能可能导致设计 用于对抗癌症的新的诊断和/或治疗技术。 拟议研究的长期目标是分析 整合素与肿瘤转移作为第一步， 将研究不同转移潜能的肿瘤细胞中的整联蛋白。 一种新的技术，同源PCR扩增，将用于 鉴定和克隆肿瘤细胞整合素。这项技术使得 克隆在给定细胞类型中表达的所有整联蛋白，包括 以前身份不明的家庭成员。不变量的短延伸 该家族所有已知成员共有的氨基酸序列用作 启动已知和新型整联蛋白mRNA PCR扩增的引物 序列的所得到的对应于不同的 将整联蛋白克隆到质粒载体中， 其特征在于DNA测序。克隆的cDNA片段将用作 探针来分析整合素在培养的肿瘤细胞中的表达， 不同的转移潜能，以及肿瘤组织的切片。整合素 cDNA片段也将在细菌中表达为融合蛋白， 将被注射到兔子体内， 预定的特异性。这些抗体将是重要的工具， 分析亚基缔合、加工和细胞表面表达， 研究整合素在正常和肿瘤组织中的分布 组织中肿瘤细胞整合素的功能特性将被分析 使用抗体或反义RNA技术在多种细胞粘附中， 和侵入测定。这些研究将为更多的 通过在异源细胞中表达cDNA进行详细的功能分析。

Integrins are a complex family of cell surface receptors involved in both cell-matrix and cell-cell adhesion. Most of the known integrins recognize extracellular matrix ligands, including fibronectin, laminin, collagens, vitronectin, and tenascin. Some integrins mediate cell-cell interactions by binding to other membrane proteins, like I-CAM. Strong initial evidence suggests that along with other with other types of cell adhesion receptors, many members of the integrin family contribute to tumor metastasis. Integrins were discovered only a few years ago,and since then, about 20 members of this major gene family have been described. The expression of most of these is developmentally regulated, and in some cases restricted to a specific cell type. It is very likely that many additional numbers of the family are yet to be discovered. Improved understanding of the structure and function of tumor cell integrins might lead to the design of novel diagnostic and/or therapeutic techniques in the fight against cancer. The long-term objective of the proposed research is to analyze the role of integrins in tumor metastasis. As a first step, the distribution of integrins in tumor cells of different metastatic potential will be studied. A novel technique, homology-based PCR amplification, will be used to identify and clone tumor cell integrins. This technique makes it possible to clone all the integrins expressed in a given cell type, including previously unidentified members of the family. Short stretches of invariant amino acid sequence shared by all known members of the family are used as primers to initiate PCR amplification of both known and novel integrin mRNA sequences. The resulting mixture of fragments corresponding to different integrins is cloned into a plasmid vector, and individual clones are characterized by DNA sequencing. Cloned cDNA fragments will be used as probes to analyze the expression of integrins in cultured tumor cells of varying metastatic potential, and in sections of tumor tissues. Integrin cDNA fragments will also be expressed in bacteria as fusion proteins, which will be injected into rabbits to raise anti-integrin antibodies of predetermined specificity. These antibodies will be important tools to analyze subunit association, processing and cell surface expression of the respective antigens, and to study integrin distribution in normal and tumor tissues. The functional properties of tumor cell integrins will be analyzed using antibodies or antisense RNA techniques in a variety of cell adhesion and invasion assays. These studies will provide the basis for a more detailed functional analysis by expression of cDNAs in heterologous cells.