Kobayashi K, Nakanishi H, Inada K, Fujimitsu Y, Yamachika T, Shirai T, Tatematsu M
Laboratory of Pathology, Aichi Cancer Center Research Institute, Kanokoden, Nagoya.
Jpn J Cancer Res. 1996 Dec;87(12):1227-34. doi: 10.1111/j.1349-7006.1996.tb03137.x.
A micrometastasis model was established using a rat differentiated prostatic adenocarcinoma, designated PLS30lZ, transfected with the lacZ gene encoding a bacterial beta-galactosidase. The morphology, tumorigenicity and metastatic ability of PLS30lZ were comparable to those of the parental cells. Micrometastatic foci could be specifically detected at the single cell level after X-Gal staining with a dissecting microscope. After intravenous injection, the number of X-Gal positive foci in the lung decreased progressively to a steady-state level (less than 1% of injected cells) by 4-7 days, while the size of persisting positive foci started to increase from 4 days after inoculation, as demonstrated by image analysis. X-Gal and BrdU double staining revealed that BrdU labeling indices of X-Gal-positive cells decreased transiently at the 2-day time point and increased again from 4 days after inoculation. Type IV collagen immunostaining showed the tumor cells to be surrounded by a basement membrane intravascularly at the time point when they started new growth. Electron microscopy confirmed that, 2 days post injection, most tumor cells were degenerative or dead, but on day 4, persisting tumor cells formed multicellular clumps in contact with the vascular basement membrane inside vessels. These results indicate that PLS30lZ cells begin to grow intravascularly depending upon the presence of a basement membrane before extravasation at the initial stage of micrometastasis formation.
使用转染了编码细菌β-半乳糖苷酶的lacZ基因的大鼠分化型前列腺腺癌（命名为PLS30lZ）建立了微转移模型。PLS30lZ的形态、致瘤性和转移能力与亲代细胞相当。在用解剖显微镜进行X-Gal染色后，可以在单细胞水平特异性检测到微转移灶。静脉注射后，肺中X-Gal阳性灶的数量在4-7天逐渐减少至稳态水平（注射细胞的不到1%），而持续存在的阳性灶的大小从接种后4天开始增加，图像分析表明了这一点。X-Gal和BrdU双重染色显示，X-Gal阳性细胞的BrdU标记指数在第2天时间点短暂下降，并从接种后4天再次增加。IV型胶原免疫染色显示，在肿瘤细胞开始新生长的时间点，血管内的肿瘤细胞被基底膜包围。电子显微镜证实，注射后2天，大多数肿瘤细胞发生退变或死亡，但在第4天，持续存在的肿瘤细胞在血管内与血管基底膜接触形成多细胞团块。这些结果表明，在微转移形成的初始阶段，PLS30lZ细胞在血管内开始生长依赖于基底膜的存在，然后才外渗。
