Significance of serum laminin and type IV collagen levels for metastasis in murine RCT sarcoma

We investigated in vivo the correlation between pulmonary metastasis and serum concentrations of laminin and type IV collagen in high-metastatic RCT(+) and low-metastatic RCT(-) clones established from poorly differentiated RCT sarcoma in C3H/He mice. The in vitro invasiveness of these cell clones through the extracellular matrix was also studied. In the in vitro invasion assay, high-metastatic RCT(+) cells showed significantly more invasiveness than low-metastatic RCT(-) cells. The different invasiveness of these cloned cells was associated with their different ability to attach to and degrade the matrix. In mice inoculated with RCT(+) cells, serum levels of laminin and type IV collagen rose with the increase in the number of pulmonary metastatic nodules. Serum levels of these extracellular matrix components started to rise when pulmonary metastatic nodules were macroscopically observed in the RCT(+) group. In mice bearing RCT(-) cells with lower metastatic ability, there were no significant increases in serum extracellular matrix levels. These findings suggested that serum concentrations of laminin and type IV collagen might be useful markers for the early detection of metastasis.