Deletion of chromosome 6q is frequent in
breast cancer, and the deletion often involves a region in 6q14-q16. At present, however, the underlying tumor suppressor gene has not been established. Based on a recent study identifying
snoRNA U50 as a candidate for the 6q14-16 tumor suppressor gene in
prostate cancer, we investigated whether U50 is also involved in
breast cancer. PCR-based approaches showed that U50 underwent frequent genomic deletion and transcriptional downregulation in cell lines derived from
breast cancer. Mutation screening identified the same 2-bp deletion of U50 as in
prostate cancer in both cell lines and primary
tumors from
breast cancer, and the deletion was both somatic and in germline. Genotyping of a cohort of
breast cancer cases and controls for the mutation demonstrated that, while homozygous genotype of the mutation was rare, its heterozygous genotype occurred more frequently in women with
breast cancer. Functionally, re-expression of U50 resulted in the inhibition of colony formation in
breast cancer cell lines. These results suggest that noncoding
snoRNA U50 plays a role in the development and/or progression of
breast cancer.