C. Lugassy et al., ANGIO-TUMORAL LAMININ IN MURINE TUMORS DERIVED FROM HUMAN-MELANOMA CELL-LINES - IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL OBSERVATIONS, Journal of submicroscopic cytology and pathology, 30(2), 1998, pp. 231-237
Cells in tissues interact with each other and with the extracellular m
atrix as part of a structural and informational unit. During cancer pr
ogression, tumor cells participate in the formation of a neotissue inv
olving other cells and matrix. We recently observed in melanoma an ass
ociation between tumor and endothelial cells via an amorphous matrix c
ontaining free laminin. The pericytic location of melanoma cells in th
is angio-tumoral complex raised the question of an intramesenchymal mi
gration of metastatic melanoma cells promoted by free laminin along th
e endothelium. However the respective roles of melanoma cells and endo
thelial cells in laminin secretion were not clear. In an attempt to cl
arify the latter issue, we injected into mice three human melanoma cel
l lines, one secreting laminin and two that did not, in order to ident
ify the source of laminin secretion in the subsequent interactions bet
ween tumor cells and vascular endothelium. Using immunohistochemistry
and electron microscopy we observed in all three cases an amorphous ma
trix containing laminin between tumor and endothelial cells. The fact
that two cell lines did not secrete laminin suggests that the periendo
thelial/peritumoral laminin could be of endothelial origin. Given the
presence of laminin alone during intramesenchymal angiogenesis and emb
ryogenesis, we propose an analogous role for endothelial laminin in fa
cilitating the migration of melanoma cells along the abluminal surface
of the endothelium.