An immunohistochemical study of tumour vessels in metastatic liver cancers and the surrounding liver tissue.

To elucidate the phenotype of the blood vessels and the expression of the growth factors involved in angiogenesis in metastatic liver cancers, we carried out an immunohistochemical study of 57 surgically resected livers with metastatic cancer. Blood vessels in the metastatic liver cancers frequently expressed von Willebrand factor (vWF), Ulex europaeus agglutinin I (UEA I)-binding sites, alpha-smooth muscle actin (alpha-SMA), type IV collagen and laminin. Sinusoidal endothelial cells around the metastatic liver cancers were positive for vWF in 33.3% of the specimens examined and for UEA I in 28.1%. alpha-SMA-positive perisinusoidal cells accumulated in the vicinity of the metastatic liver cancers in 68.4% of the specimens. Type IV collagen was detected in the perisinusoidal space close to the metastatic cancers as well as distant from them (91.2%). Laminin was detected in the perisinusoidal space in only one specimen (1.8%). Tumour cells of the metastatic liver cancers were positive for vascular endothelial growth factor, basic fibroblast growth factor (bFGF), and acidic fibroblast growth factor (aFGF) in 78.9%, 38.4% and 7.0% of the specimens, respectively. Hepatocytes close to the metastatic liver cancers expressed bFGF more strongly than those distant from the metastatic liver cancers, and their expression of bFGF was more intense than that in the tumour cells. These results suggest that: (1) tumour vessels in metastatic liver cancers consist of endothelium, basement membrane and pericytes, (2) the sinusoids adjacent to tumours undergo capillarization, and (3) vascular endothelial growth factor may contribute to angiogenesis in metastatic liver cancer. Basic fibroblast growth factor may be responsible for the sinusoidal capillarization and the peritumoral fibrosis.