Differential Display Analysis of Fiber-Induced Carcinogenesis in Rat: Clue for Involvement of Integrin-Mediated...

In this study, mRNA expression patterns during mesothelioma carcinogenesis in the peritoneal cavity were investigated. To this purpose, the mRNA expression patterns of fiber-induced mesothelioma and of fiber-treated tissues were compared to untreated tissues, respectively. Suppression subtractive hybridization (SSH) and an array hybridization assay were used to perform differential display analyses. Genes found to be expressed differentially mainly represent proteins of signal transduction pathways and regulatory proteins of the cell cycle. The genes for components of the AP-1 transcription factor, c-jun, c-fos, and fra-1 (fos-related antigen-1) are upregulated in nontumorous tissue treated with asbestos. These data confirm in vivo the involvement of AP-I expression as response to fiber treatment. In addition, osteopontin, zyxin, and integrin-linked kinase were upregulated in tumors and in treated tissues. These genes code for proteins involved in the signal transduction from the extracellular matrix to the nucleus. Using integrin-specific inhibitors, the apoptotic effects of crocidolite fibers could be suppressed significantly. From these results we hypothesize that direct effects of the fibers on the target tissue are mediated by interaction of the fibers with the extracellular matrix molecules.