WILMS-TUMOR SUPPRESSOR GENE-EXPRESSION IN RAT AND HUMAN MESOTHELIOMA

Induction of mesothelioma in the rat is an important animal model for assessing the carcinogenic potential of fibers and for understanding t he molecular basis underlying the development of these tumors. Mesothe liomas and nephroblastoma (Wilms' tumor) have many developmental, bioc hemical, and histological similarities; however, the expression of the Wilms' tumor suppressor gene, WT-1, has not been well characterized i n the rat, and its expression pattern in rat or human mesothelioma has not been described. We report that WT-1 transcripts (3.2 kilobases) c ould be detected by Northern analysis in adult rat testis, spleen, kid ney, Lung, heart, and glomerular mesangial cells. Normal adult mesothe lial cells also expressed this gene. Rat mesothelioma cell lines expre ssed WT-1 transcripts of 3.2 kilobases and an additional 2.8-kilobase transcript, previously only reported to be expressed in the testis. No rmal and transformed rat mesothelial cells expressed all four of the W T-1 splice variants, except testis, which only expressed WT-1 splice v ariants containing exon 5. Seven of seven human mesothelioma cell line s examined also expressed WT-1 transcripts, suggesting that expression of this gene may be useful in the diagnosis of these tumors.