Molecular mechanisms of cancer cell progression during liver metastasis formation

本研究旨在阐明结肠癌肝转移形成的分子机制。我们主要感兴趣的是宿主在转移过程中的反应。本研究主要围绕以下两个方面展开：(1)转移早期癌细胞与肝脏的黏附与识别机制：FH6单抗决定簇在结肠癌组织中的表达与肿瘤的恶性程度相关。结肠癌细胞株KM12表达FH6决定簇，这是一种位于下列位点的独特的糖链结构，含有唾液酸化和岩藻糖基化，不被部分唾液酸化Lewis X抗体识别，对内切β糖苷酶敏感。为了阐明这些碳水化合物的分子性质，我们通过将FUT6基因导入缺乏FH6决定簇表达的KM12-LX细胞中，人工重组了FH6决定簇。我们发现肝细胞识别肝脏中的FH6决定簇。我们现在正在确定…的结构以49kD以上的蛋白质作为候选识别分子。(2)建立肝转移瘤形成伴随微转移灶周围宿主组织重建的小鼠实验性转移模型，再现微转移灶周围宿主组织的重建和已建立转移灶的形成。根据组织化学观察，我们将已建立转移的形成分为三个步骤：微转移、一过性微转移和已建立转移。在微转移中，特殊的宿主细胞侵入转移区。在一过性微转移中，多种类型的宿主细胞被渗透。成纤维细胞组织出现突起，伴有细胞外基质和新生血管，并与邻近微转移灶相连。我们认为，作为纤维化形成的初始事件，这一过程很重要。已建立的转移灶中富含成纤维细胞间质组织。结肠38细胞与宿主细胞分开分布于间质组织中。我们假设在已建立的转移形成过程中有一定的机制来分离癌症和间质。较少

The aim of this proposal was to elucidate molecular mechanisms of liver metastasis formation of colon cancer. Our main interest was how host respond during the metastasis process. We have concentrated on the following two research subjects.(1) Adhesion and recognition mechanisms between cancer cells and the liver in the early phase of metastasis : Expression of FH6 monoclonal Ab determinant on colon carcinoma correlates malignancy of the tumor. A colon carcinoma cell line KM 12 expresses FH6 determinant, a unique carbohydrate structure on the following points, containing sialylation anfd fucosylation, not recognized by a part of anti-sialyl lewis X Abs, sensitive to endo-β-glycosidase digestion. To elucidate molecular properties of the carbohydrates we artificially reconsituted FH6 determinants by FUT6 gene transfection into KM 12-LX that lacks expression of FH6 determinant. We showed that hepatocytes recognized the FH6 determinant in the liver. We are now determining the structure of … More 49 kD protein as a candidate of the recognition molecule.(2) Established liver metastasis formation accompanied with reconstitution of host tissues around micrometastasis : We have established a mouse experimental metastasis model that reproduces reconstitution of host tissue around micrometastasis and formation of established metastasis. Based on histochemical observations, we have classified the formation of established metastasis into three steps ; micrometastasis, transient micrometastasis, and established metastasis. In micrometastasis, paticular host cells infilrated into the matastasis region. In transient micrometastasis, many types of host cells infiltrated. Fibroblastic tissue protrusion appeared that accompanied with extracellular matrices and neovascularization and linked neighboring micrometastases. We believe that the process is important as an initial event of fibrosis formation. Established metastasis was rich in fibroblastic stromal tissue. Colon 38 cells separately distributed from host cells in the stromal tissue. We postulate a certain mechanism to separate cancer and stroma in the process of established metasiasis formation. Less