Alteration of hSNF5/INI1/BAF47 detected in rhabdoid cell lines and primaryrhabdomyosarcomas but not Wilms' tumors

The organization of genomic DNA into chromatin aids in the regulation of ge ne expression by limiting the access of transcriptional binding domains. Th e SWI/SNF family of chromatin-remodeling complexes, which are conserved fro m yeast to humans, open the chromatin to facilitate the transcriptional mac hinery to access their targets. The gene encoding the BAF47/hSNF5 subunit o f the complex has been found mutated in both rhabdoid cell lines and in pri mary rhabdoid tumors. Since the pediatric tumors rhabdomyosarcoma (RMS) and Wilms' tumor (WT) share a similar genetic link with rhabdoid tumors, it wa s hypothesized that they may also show alterations of the BAF47 gene. Using primary tumors, the BAF47 protein was detected in all WT but less than 75% of the RMS tested, In cell lines, the BAF47 protein was missing in all rha bdoid cell lines and one RMS cell Line. Analysis of sample DNA displayed ei ther a mutation or deletion of the BAF47 gene in all samples negative for t he protein. Several other subunits of the human SWI/SNF complex, including BRG1 which is the subunit directly interacting with the Rb tumor suppressor gene, were detected in all tumor samples. Alteration of BAF47 may be a gen etic marker associated with the poor prognosis seen in all rhabdoid tumors but only some RMS.