Jenq W, Wu S J, Kefalides N A
Connective Tissue Research Institute, University of Pennsylvania, Philadelphia 19104-2614.
Connect Tissue Res. 1993;30(1):59-73. doi: 10.3109/03008209309032930.
The cell adhesion promoting activity of laminin isolated from normal human placenta was compared with that isolated from mouse EHS tumor and from the cultures of a mouse epithelial cell line B82 and its tumorigenic derivative, B82HT. The adhesion promoting properties of commercial merosin isolated from placenta was also compared with the above preparations using the human fibrosarcoma HT1080 cells. Percent attachment was defined as (radioactivity extracted from attached cells)/(radioactivity in cells added to assay) x 100. HT1080 cells adhered more efficiently on laminin (0.5 micrograms/well), isolated from the B82 rather than B82HT cell conditioned medium, (82% vs 64%). Percent attachment of HT1080 cells on isolated native placental laminin or commercial merosin was significantly higher compared to laminin from the EHS tumor (at 0.75 micrograms/well, 69%, 73% and 20% respectively). In parallel experiments the steady-state levels of mRNAs for subunits A, M, B1 and B2 in cultures of B82 and B82HT cells were determined. The ratio of mRNA for the laminin subunits in B82 and B82HT cells was 1:0.9 for the A chain, 1:0.6 for the M chain, 1:0.4 for the B1 chain, and 1:0.3 for the B2 chain. Protein studies indicated that the M subunit is absent in laminin preparations from the EHS tumor whereas it is abundant in the laminin from placenta and in commercial merosin. Laminin isolated from B82 cells contains a higher proportion of the M subunit compared to that from B82HT cells. The data suggest that there are functional differences between the laminin found in normal tissue and that present in a solid tumor. Functional differences were noted between the laminins synthesized by the B82 cell line and its tumorigenic counterpart, B82HT. These differences may result from the lack of gene expression for the laminin subunit M by the EHS tumor and by the lower degree of gene expression for this subunit by B82HT cells. The possibility that the laminin synthesized by the tumorigenic cell line may be structurally different from that synthesized by the B82 cells should also be considered.
将从正常人胎盘中分离出的层粘连蛋白的细胞黏附促进活性，与从小鼠EHS肿瘤以及小鼠上皮细胞系B82及其致瘤衍生物B82HT的培养物中分离出的层粘连蛋白的细胞黏附促进活性进行了比较。还使用人纤维肉瘤HT1080细胞，将从胎盘中分离出的商业merosin的黏附促进特性与上述制剂进行了比较。附着百分比定义为（从附着细胞中提取的放射性）/（添加到测定中的细胞中的放射性）×100。HT1080细胞在从B82而非B82HT细胞条件培养基中分离出的层粘连蛋白（0.5微克/孔）上的附着效率更高（分别为82%和64%）。与来自EHS肿瘤的层粘连蛋白（在0.75微克/孔时，分别为69%、73%和20%）相比，HT1080细胞在分离出的天然胎盘层粘连蛋白或商业merosin上的附着百分比显著更高。在平行实验中，测定了B82和B82HT细胞培养物中层粘连蛋白亚基A、M、B1和B2的mRNA稳态水平。B82和B82HT细胞中层粘连蛋白亚基的mRNA比例，A链为1:0.9，M链为1:0.6，B1链为1:0.4，B2链为1:0.3。蛋白质研究表明，EHS肿瘤的层粘连蛋白制剂中不存在M亚基，而胎盘层粘连蛋白和商业merosin中的M亚基含量丰富。与B82HT细胞相比，从B82细胞中分离出的层粘连蛋白含有更高比例的M亚基。数据表明，正常组织中的层粘连蛋白与实体瘤中的层粘连蛋白之间存在功能差异。在B82细胞系及其致瘤对应物B82HT合成的层粘连蛋白之间也注意到了功能差异。这些差异可能是由于EHS肿瘤缺乏层粘连蛋白亚基M的基因表达以及B82HT细胞中该亚基的基因表达程度较低所致。还应考虑致瘤细胞系合成的层粘连蛋白在结构上可能与B82细胞合成的层粘连蛋白不同的可能性。
