Stable interaction between the products of the BRCA1 and BRCA2 tumor suppressor genes in mitotic and meiotic cells

BRCA1 and BRCA2 account for most cases of familial, early onset breast and/or ovarian cancer and encode products that each interact with hRAD51. Results presented here show that BRCA1 and BRCA2 coexist in a biochemical complex and colocalize in subnuclear foci in somatic cells and on the axial elements of developing synaptonemal complexes. Like BRCA1 and RAD51, BRCA2 relocates to PCNA⁺ replication sites following exposure of S phase cells to hydroxyurea or UV irradiation. Thus, BRCA1 and BRCA2 participate, together, in a pathway(s) associated with the activation of double-strand break repair and/or homologous recombination. Dysfunction of this pathway may be a general phenomenon in the majority of cases of hereditary breast and/or ovarian cancer.