Tumor-produced, active interleukin-1beta regulates gene expression in carcinoma-associated fibroblasts.

Abstract

Recently we described a co-culture model of periodontal ligament (PDL) fibroblasts and SCC-25 lingual squamous carcinoma cells, which resulted in conversion of normal fibroblasts into carcinoma-associated fibroblasts (CAFs), and in epithelial-mesenchymal transition (EMT) of SCC-25 cells. We have found a constitutive high interleukin-1beta (IL1-beta) expression in SCC-25 cells in normal and in co-cultured conditions. In our hypothesis a constitutive IL1-beta expression in SCC-25 regulates gene expression in fibroblasts during co-culture. Co-cultures were performed between PDL fibroblasts and SCC-25 cells with and without dexamethasone (DEX) treatment; IL1-beta processing was investigated in SCC-25 cells, tumor cells and PDL fibroblasts were treated with IL1-beta. IL1-beta signaling was investigated by western blot and immunocytochemistry. IL1-beta-regulated genes were analyzed by real-time qPCR. SCC-25 cells produced 16kD active IL1-beta, its receptor was upregulated in PDL fibroblasts during co-culture, which induced phosphorylation of interleukin-1 receptor-associated kinase-1 (IRAK-1), and nuclear translocalization of NFkappaBalpha. Several genes, including interferon regulatory factor 1 (IRF1) interleukin-6 (IL-6) and prostaglandin-endoperoxide synthase 2 (COX-2) were induced in CAFs during co-culture. The most enhanced induction was found for IL-6 and COX-2. Treatment of PDL fibroblasts with IL1-beta reproduced a time- and dose-dependent upregulation of IL1-receptor, IL-6 and COX-2. A further proof was achieved by DEX inhibition for IL1-beta-stimulated IL-6 and COX-2 gene expression. Constitutive expression of IL1-beta in the tumor cells leads to IL1-beta-stimulated gene expression changes in tumor-associated fibroblasts, which are involved in tumor progression.