1,25-Dihydroxycholecalciferol stimulates the expression of intercellular adhesion molecule-1 in renal carcinoma cells.

1,25-Dihydroxycholecalciferol (1,25-D3) is a potent immunomodulatory vitamin modulating major histocompatibility complex class-II expression in monocytes and epithelial cells. However, the impact of 1,25-D3 on the expression of adhesion molecules in epithelial cells has not been investigated. Human renal tubular epithelial and renal carcinoma cells express intercellular adhesion molecule-1 (ICAM-1), a ligand of the leukocyte-function-associated antigen-1 (LFA-1). Therefore, we addressed the question whether 1,25-D3 modulates ICAM-1 expression by renal carcinoma cells. Using an enzyme-linked immunoassay we detected an increase in ICAM-1 expression by a renal carcinoma cell line (ACHN) cultured in the presence of 1,25-D3. Also, in ACHN cells stimulated with gamma-IFN a significant stimulatory effect of 1,25-D3 was evident. ICAM-1 is crucial for the adhesion of LFA-1-expressing lymphocytes and is involved in antigen presentation. In addition, ICAM-1 may be of significance in lymphocyte lysis of tumor cells. Therefore, the impact of 1,25-D3 on ICAM-1 expression by renal and non-renal and non-renal carcinoma cells and renal tubular epithelial cells may be of clinical importance.