PLASMINOGEN ACTIVATOR INHIBITOR--1 GENE EXPRESSION IN TUMOR METASTASIS

恶性肿瘤原发部位肿瘤细胞转移的原因 对大多数癌症患者的死亡负责。这一过程 转移是复杂的，涉及几个步骤，包括侵袭和 细胞外基质的降解，血管内，通过 血管生成、外渗与肿瘤新病灶的建立 远离原发肿瘤。这些步骤可能涉及 几种受多种调控的蛋白水解酶的作用 在转移过程中的暂时性水平。UPA是关键之一 酶通过其激活能力参与代谢过程 纤溶酶原转化为纤溶酶。UPA在肿瘤细胞中的活性可能是 受uPA与抑制物PAI-1结合的调节。初步 由细胞系组成的人类骨肉瘤模型的数据显示 裸鼠体内不同成瘤和转移能力的研究 表明膜结合uPA的水平而不是 分泌的uPA与肿瘤的侵袭和转移行为相关 肿瘤细胞。 二倍体人类胚胎细胞HEL299的Southern杂交技术 作为基因拷贝数的对照，我们发现这些基因 编码PAI-1和uPAR在HOS、AD110和KRIB细胞中为单拷贝 经Northern印迹杂交，AD110细胞表达约2-3 比HOS或KRIB细胞有更多稳定状态的PAI-1mRNA。AD110 和KRIB表达同等水平的uPAR mRNA(约为5-10倍 大于居屋单位)。进一步的研究正在进行中，以评估 这些细胞中PA1-1编码基因的转录调控。 纤溶酶原激活物-1在调节uPA与uPAR结合中的作用 纤溶酶原激活物-1对AD110细胞侵袭和转移特性的影响 被评估。

Metastasis of tumor cells from the primary site of a malignancy accounts for the majority of fatalities in cancer patients. The process of metastasis is complex and involves several steps including invasion and degradation of the extracellular matrix, intravasation, transit through the vasculature, extravasation, and establishment of new tumor foci distant from the primary tumor. These steps probably involve the actions of several proteolytic enzymes which are regulated at several levels temporally during the metastatic process. UPA is among pivotal enzymes involved in the metastic process through its ability to activate plasminogen to plasmin. The activity of uPA in tumor cells is probably regulated by the binding of uPA with the inhibitor PAI-1. Preliminary data from a human osteosarcoma model comprised of cell lines showing varying abilities to form tumors and metastasize in athymic nude mice has shown that the level of membrane bound UPA rather than the level of secreted uPA correlates with the invasive and metastatic behavior of the tumor cells. By Southern blot technique using HEL299, a diploid human embryonic cell line, as a control for gene copy number, we have found that the genes encoding PAI-1, and uPAR are single copy in HOS, AD110, and KRIB cells By Northern blot hybridization, AD110 cells express approximately 2-3 fold more steady state PAI-1 mRNA than either HOS or KRIB cells. AD110 and KRIB express equivalent levels of uPAR mRNA (approximately 5-10 fold greater than HOS cells). Further studies are underway to evaluate the transcriptional regulation of the gene encoding PA1-1 in these cells. The role of PAI-1 in regulating the binding of uPA to uPAR and the effect of PAI-1 on the invasive and metastatic properities of AD110 will be evaluated.