USE OF RECONSTITUTED BASEMENT MEMBRANE EXTRACTS TO STUDY OF THE MECHANISMS OF THE INVASION OF MALIGNANT TUMORS THROUGH BASEMENT MEMBRANES

基底膜是包围大多数上皮组织、神经和肌肉以及大多数血管和淋巴管的衬里的薄的细胞外结构。肿瘤侵袭基底膜是导致转移形成的多阶段过程中的关键步骤。肿瘤细胞在扩散过程中最初侵入淋巴或血管床时穿过基底膜，并渗透到靶组织中。肿瘤细胞通过基底膜的侵袭可能涉及不同的事件，包括：a）肿瘤细胞通过细胞表面受体附着于基底膜中的层粘连蛋白; B）肿瘤细胞分泌引起基底膜屏障降解的酶，以及c）肿瘤细胞迁移到靶组织中。我们已经使用形成屏障的重建基底膜分子来研究恶性骨和软组织肿瘤细胞的体外侵袭性。从我们的研究中获得的结果如下：1）HT 1080人纤维肉瘤细胞通过层粘连蛋白的四个附着位点附着于基底膜（YIGSR，PDSGR，RGD，IKVAV）和IV型胶原。2）发现肿瘤细胞与基底膜中的层粘连蛋白的结合诱导IV型胶原酶的分泌和运动，这两者都是侵袭的关键因素。环AMP类似物和来自层粘连蛋白B1链的合成肽Tyr-Ile-Gly-Ser-Arg（YIGSR）能够抑制HT 1080人纤维肉瘤细胞的侵袭性。这些药物也被发现可以减少体内的肺定植。4）不仅细胞系，而且恶性骨和软组织肿瘤的原代培养物在体外显示出侵袭性，而非转移性细胞则不能。5）共注射基底膜提取物有助于手术获得的人恶性骨和软组织肿瘤移植到裸鼠体内。

Basement membrane are thin extracellular structures surrounding most epithelial tissues, nerves and muscles as well as the lining of most blood and lymph vessels. Tumor invasion of basement membrane is a crucial step in the multistage process which leads to the formation of metastasis. Tumor cells cross basement membranes as they initially invade the lymphatic or vascular beds during dissemination, and they penetrate into their target tissue. It is likely that the invasion of tumor cells through basement membranes involves distinct events, including: a) attachment of tumor cells to laminin in the basement membranes through cell surface receptors; b) secretion of enzymes by tumor cells that cause the degradation of basement membrane barrier, and c) migration of tumor cells into the target tissue. we have used the reconstituted basement membrane molecules formed into barriers in order to investigate the invasiveness of malignant bone and soft tissue tumor cells in vitro. Results obtained from our study were as follows: 1) HT1080 human fibrosarcoma cells attach to the basement membrane via four attachment sites of laminin (YIGSR,PDSGR,RGD,IKVAV) and type IV collagen.2) The binding of tumor cells to laminin in the basement membranes were found to induce the secretion of collagenase IV and motility both of which are crucial factors for the invasion.3) Cyclic AMP analogues and a synthetic peptide, Tyr-Ile-Gly-Ser-Arg (YIGSR), from the B1 chain of laminin were able to suppress the invasiveness of HT1080 human fibrosarcoma cells. These agents were also found to reduce the lung colonization in vivo.4) Not only the cell lines but also the primary cultures of malignant bone and soft tissue tumors showed invasiveness in vitro while non-metastatic cells failed to do so.5) Co-injection of basement membrane extracts facilitated the transplantability of human malignant bone and soft tissue tumors obtained at surgery into nude mice.