Purpose: Interactions between endothelial and tumor cells via E-selectin and sialyl Lewis x (sLex) have been suggested to play a significant role in the development of metastasis and tumor growth. In this work, we tested whether inhibition of E-selectin expression on the surface of endothelial cells might impair endothelial/tumor cells interactions and tumor growth of hepatocarcinoma cells in vitro and in vivo.
Methods: We used HepG2 cells that highly express sLex antigens and HuH7 cells that do not express sLex. Inhibition of E-selectin expression on the surface of endothelial cells was obtained by using cimetidine and amiloride treatment.
Results: Cimetidine and amiloride inhibited, respectively, by 20 and 64 % E-selectin expression by activated endothelial cells and significantly subsequent adhesion of HepG2 cells to activated endothelial cells. Subcutaneous injection of cimetidine or amiloride resulted in a significant inhibition of HepG2 cells tumor growth in nu/nu mice but not of HuH7 cells. Thus, cimetidine and amiloride administration led to an inhibition of 57 and 75 % of HepG2 tumor growth in vivo, respectively. This effect was associated with an inhibition of vasculogenesis as demonstrated by anti-CD31 immunostaining.
Conclusion: Inhibition of E-selectin expression allows an anti-tumoral effect on sLex-expressing HCC tumors in vivo. This suggests that interactions between HCC cells and endothelial cells through sLex antigens and E-selectin might be a target for treatment of HCC. Further studies might evaluate the clinical impact of cimetidine and amiloride in the treatment of HCC patients alone or in combination with other anti-tumoral agents.
Keywords: Amiloride; Cimetidine; E-selectin; Hepatocarcinoma; Sialyl Lewis x; Tumor angiogenesis.