Nakajima M, Welch D R, Belloni P N, Nicolson G L
Cancer Res. 1987 Sep 15;47(18):4869-76.
A series of rat 13762NF mammary adenocarcinoma cell clones and subclones of various lung metastatic potentials were examined for their abilities to degrade rat lung subendothelial matrix and purified basement membrane type IV collagen. Metastatic potentials were simultaneously determined based on the ability to form "spontaneous" lung metastases after s.c. injection or "experimental" lung metastases after i.v. injection of cells. Microvessel endothelial cells isolated from rat lung were grown in vitro, and the subendothelial matrix containing type IV collagen was metabolically labeled with [3H]proline. When mammary adenocarcinoma cells were placed on the isolated subendothelial matrix, fragmentation and solubilization of [3H]proline-labeled components were observed; highly metastatic 13762NF cells solubilized the matrix at higher rates than did poorly metastatic cells. The 13762NF cells were assayed for type IV collagenolytic activity using [3H]proline-labeled type IV collagen purified from Engelbreth-Holm-Swarm tumor as a substrate. We found excellent correlation between the type IV collagenolytic activities of living cells and their "spontaneous" lung metastatic potentials (r = 0.993). The levels of type IV collagenolytic activity in the conditioned medium depended on the cell culture conditions. In the presence or absence of acid-treated fetal bovine serum, highly metastatic cells secreted higher amounts of type IV collagenolytic enzymes in active and latent forms than did poorly metastatic cells. Incubation of procollagen type IV with medium conditioned by highly metastatic 13762NF cells and treated with trypsin resulted in the production of several large fragments characteristic of type IV collagen. The results suggest that enzymatic degradation of basement membrane type IV collagen is important in lung metastasis of 13762NF mammary adenocarcinoma cells.
对一系列具有不同肺转移潜能的大鼠13762NF乳腺腺癌细胞克隆和亚克隆进行检测，观察它们降解大鼠肺内皮下基质和纯化的基底膜IV型胶原的能力。根据皮下注射后形成“自发”肺转移的能力或静脉注射细胞后形成“实验性”肺转移的能力，同时测定转移潜能。从大鼠肺中分离出微血管内皮细胞并在体外培养，用[3H]脯氨酸对含有IV型胶原的内皮下基质进行代谢标记。当将乳腺腺癌细胞置于分离的内皮下基质上时，观察到[3H]脯氨酸标记成分的片段化和溶解；高转移的13762NF细胞比低转移细胞以更高的速率溶解基质。以从Engelbreth-Holm-Swarm肿瘤中纯化的[3H]脯氨酸标记的IV型胶原为底物，检测13762NF细胞的IV型胶原酶活性。我们发现活细胞的IV型胶原酶活性与其“自发”肺转移潜能之间具有极好的相关性（r = 0.993）。条件培养基中IV型胶原酶活性的水平取决于细胞培养条件。在有或没有酸处理的胎牛血清存在的情况下，高转移细胞分泌的活性和潜伏形式的IV型胶原酶的量均高于低转移细胞。用高转移的13762NF细胞条件培养基处理并经胰蛋白酶处理的IV型前胶原孵育后，产生了几种IV型胶原特有的大片段。结果表明，基底膜IV型胶原的酶促降解在13762NF乳腺腺癌细胞的肺转移中起重要作用。
