ROLE OF METASTASIS GENES AT SPECIFIC STEPS OF METASTASIS

为了让实体瘤中的癌细胞完成 建立转移性病变的过程中，它必须完成一些 这些步骤的成功可能取决于完全不同的表型 特征（侵入、内渗、转运、外渗和 增长）。 尽管各种各样的基因都与这两种疾病有关， 增强或延迟转移性病变的形成， 实验性肿瘤植入或肿瘤静脉注射 细胞，还没有实验解剖的阶段内， 受个体“转移”表达影响的转移级联反应 基因. 我们已经获得了一系列小鼠乳腺肿瘤细胞系， 不同的转移潜力，来自一个自发的， 小鼠乳腺肿瘤的体内筛选。 我们已经开发了技术 用于确定转移级联中的哪一步不能再 由每个细胞系有效地完成。 我们在这项研究中的目标 是为了确定这个模型系统是否用于研究转移性 行为可用于定义受影响的特定进程 增强或抑制转移的基因。 我们选择了两个原型基因，激活的c-Ha-ras和 NM-23 已发现这些基因的表达与高血压相关 [ras]和低[NM-23]转移潜力。 也有很好的文献表明， 这些基因进入肿瘤细胞的转染影响转移性 受体细胞的行为。 因此，我们在这项建议中的具体目标 分别为：1）克隆NM 23或激活的Ha-ras基因的全长cDNA 在合适的表达载体中导入高或低转移性的细胞中， 2）为了确定每个基因的表达水平， 3）评估高或低水平表达的影响 这些基因对转染细胞完成 转移级联中的连续步骤，以及4）重新分离细胞 以确认任何观察到的转移性肿瘤 改变与这些基因的表达水平有关。 完成这些研究将验证测试系统 用于确定已知影响转移性肿瘤的各种基因 行为行为，并为开发一个系统提供了可能性， 以前不知道影响转移级联反应步骤的基因可以 被识别。

In order for a cancer cell in a solid tumor to complete the process of establishing a metastatic lesion it must complete a number of steps whose success is likely to depend on quite different phenotypic characteristics (invasion, intravasation, transport, extravasation and growth). Although a variety of genes have been implicated in either enhancement or retardation of the formation of metastatic lesions after implantation of experimental tumors or intravenous injection of tumor cells, there has been no experimental dissection of the stages within the metastatic cascade affected by expression of individual "metastasis" genes. We have available a series of mouse mammary tumor cell lines of varying metastatic potential which were derived from a single spontaneous mouse mammary tumor by in vivo selection. We have developed techniques for determining which step in the metastatic cascade can no longer be efficiently completed by each of the cells lines. Our goal in this study is to determine whether this model system for studies of metastatic behavior can be utilized to define the specific process(es) affected by genes that enhance or inhibit metastasis. We have chosen two prototype genes, activated c-Ha-ras and NM-23. Expression of these genes has been found to correlate with high [ras] and low [NM-23] metastatic potential in a variety of tumor models. There is also good documentation indicating that introduction of either of these genes into tumor cells by transfection affects the metastatic behavior of recipient cells. Thus, our specific aims in this proposal are: 1) To transfect full-length cDNA clones of NM23 or activated Ha-ras in appropriate expression vectors into cells of high or low metastatic potential, 2) To determine the level of expression of each gene in progeny clones, 3) To assess the effect of high or low level expression of these genes on the ability of the transfected cells to complete successive steps in the metastatic cascade, and 4) To reisolate cells from different metastatic sites to confirm that any observed metastatic alterations are associated with levels of expression of these genes. Completion of these studies will both validate a test system for determining where a variety genes already known to affect metastatic behavior act and open the possibility for development of a system wherein genes not previously known to affect steps in the metastatic cascade can be identified.