Cell adhesion molecules involved in invasion of renal carcinoma cells into the extracellular matrix

Purpose: A derisive step towards the formation of haematogenous metastases of renal tumours is the invasion of tumour cells into the subendothelial extracellular matric (EXM). The cell adhesion molecules mainly involved in this process are the beta (1) integrins which specifically bind the amino acid sequence arginine-glycine-asparagine (RGD). We examined the invasion of a renal cell carcinoma line (CCF-RC1) into various components of ECM, as well as the influence of tumour necrosis factor alpha (TNF1) and interferon gamma (IFN gamma) in this process. In addition, we also tested the inhibitory action of an antibody blocking the beta (1) subunit of the integrins (CD 29) and of a CD44-blocking monoclonal antigen as well as of a pentapeptide comprising the amino acid sequence RGD. Material and method: We used a microchemotaxis chamber with a polycarbonate membrane (pore diameter 8 mum) to quantify the invasion by the renal cell carcinoma cells. The chemotactic factors used by us were fibronectin (6 mg/ml), laminin (250 mug/ml) or collagen IV (100 mug/ml). CCF-RC1 cells were preincubated before the test for 24 hours with TNF alpha, IFN gamma or with serum-free culture medium. Blocking tests were conducted under pre-incubation with antigens against CD29 or CD44 or the RGD-containing peptide. Results:Using the ECM components fibronectin, collagen IV and laminin we found a cell migration that was five to ten times higher. This enhanced invasion depended markedly on the beta (1) integrins; in fact, migration was almost completely inhibited when using another anti-CD29 antigen or a peptide comprising RGD. It appears that CD44 participates only slightly in the collagen IV-dependent migration; migration dependent on fibronectin and laninin remains largely unaffected by an anti-CD44 antigen. TNF alpha and IFN gamma were neither acapable of causing an increased expression of CD29 and CD44, nor did they markedly change the migration behaviour of the tumour cells. Conclusion: These results show that the invasion by renal carcinoma cells is stimulated by different substances of the ECM to a different degree, fibronectin playing the most prominent part. The interactions on a molecular level are derisively influenced by the beta (1) integrins and the corresponding amino acid sequence RGD.