Interleukin-8 Expression in Gastric Cancer

Abstract

We have previously demonstrated that interleukin-8 (IL-8) is expressed by epithelial cells in normal and gastritic antral mucosa. The aims of this study were to investigate IL-8 expression in gastric carcinoma and in gastric cancer epithelial cell lines. Tumour tissue from 16 patients undergoing surgery for gastric carcinoma was rapidly frozen. Cryosections were immunolabelled with a mouse monoclonal antibody to IL-8 followed by FITClabelled goat anti-mouse IgG antibody. Double immunofluorescence with rabbit anticytokeratin antibody was used to identify infiltrating carcinoma cells. A rabbit antifibronectin antibody was used as a negative control. Specificity of IL-8 immunolabelling was confirmed by competitive inhibition with exogenous recombinant IL-8. Strong IL-8 expression was observed in the neoplastic cells of all 16 patients, expression in diffuse (n = 6) and intestinal (n = 8) type gastric cancer (Lauren classification) being equally positive. IL-8 expression was also observed in one subject with a mixed tumour type and one unclassified gastric carcinoma. IL-8 positive cells infiltrating the stroma were cytokeratin positive, fibronectin negative. Constitutive expression of IL-8 mRNA was observed in 3 gastric cancer cell lines, Kato 3, MKN 45 and ST 42 using PCR. Expression of antigenic IL-8 in the cell lines was confirmed by immunofluorescence. These results demonstrate that IL-8 is expressed constitutively in gastric cancer cell lines and that gastric cancer cells in vivo show positive IL-8 expression. The relevance of IL-8 expression to the peritumoural inflammatory reaction and the possible contribution to diagnosis require further study.