Invasion of
tumor cells into the extracellular matrix is an essential step in the formation of
metastases in
renal cancer.
Cell adhesion molecules such as beta(1)-integrins, which bind to the RGD sequence (
arginine-
glycine-
asparagine) and CD44 are involved in this process. We examined the invasion of a
renal carcinoma cell line (CCF-RC1) into the extracellular matrix compounds
fibronectin,
collagen IV and
laminin and the effect of
TGFbeta and IFNgamma on this process. The inhibitory effect of an antibody against the beta(1)-subunit of
integrins (CD29), as well as a pentapeptide including the RGD sequence, was also evaluated. A micro-chemotaxis chamber, including a
polycarbonate membrane with a pore diameter of 8 microm, was used for quantification of cell migration. The addition of the extracellular matrix compounds
fibronectin,
laminin and
collagen IV resulted in a 5-10-fold increase in invasion. This increased invasion depends strongly on the presence of beta(1)-integrins, shown by the use of an antibody against CD29 or a RGD including
peptide which inhibit the cell migration by approximately 88%. CD44 is less involved in
collagen IV dependent migration and almost no influence of CD44 was observed on a
fibronectin and
laminin dependent migration.
TNFalpha and IFNgamma did not significantly influence the expression of CD29 or CD44, and no alteration in
tumor cell migration was observed. These results show that the invasion of
renal cancer cells is differentially regulated by compounds of the extracellular matrix, whereby
fibronectin seems to be the most critical factor. The molecular interactions in this process are strongly dependent on beta(1)-integrins and the corresponding amino acid sequence RGD.