Human chromosome 11 suppresses the tumorigenicity of adenovirus transformed baby rat kidney cells: Involvement of the wilms' tumor 1 gene

Human chromosome 11 was introduced into adenovirus‐transformed baby rat kidney (BRK) cells by microcell‐mediated chromosome transfer. The resulting microcell hybrids (MCHs) showed a reduced ability to form tumors upon s.c. injection into athymic mice. Further analysis, with the use of defined deletion chromosomes of lip, indicated that the presence of region 11 p 13‐p 12 is necessary for the suppression of tumorigenicity. In contrast, the presence of region lip 15–14.1 appeared to increase the rate of tumor growth. Expression studies on the human Wilms' tumor I (WTI) and the insulin‐like growth factor II (IGF‐II) genes, which lie in regions 11 p 13 and 11 p 15, respectively, suggested the involvement of both genes in determining the degree of suppression of tumorigenicity. Finally, stable expression of a murine WTI protein in the adenovirus‐transformed cells resulted in almost complete suppression of tumorigenicity, establishing the WTI protein as a tumor suppressor in this cell system.