Identification and Characterization of Novel Kinases that Regulate BRCA1 Expression and Function

Abstract

Transcriptional and functional regulation of the breast cancer susceptibility gene 1 (BRCA1) in the pathogenesis of sporadic breast cancers is poorly understood. We developed a functional assay, which assesses the ability of BRCA1 to localize to sites of DNA damage and form ionizing radiation-induced foci (IRIF), to screen a kinase siRNA library and thirty-two potential positive regulators of BRCA1 were identified. Subsequent validation resulted in fourteen kinases that consistently diminished BRCA1 IRIF. Secondary screening assays for three selected kinases determined whether siRNA-mediated knockdown of the kinases caused an expression or function defect of BRCA1. Repair capacity and cell survival after DNA damage were characterized following siRNA-mediated knockdown of these three kinases. Our long term goal is to describe signaling pathways that explain how the identified kinases are able to regulate BRCA1. This knowledge could potentially translate into a novel therapeutic approach for sporadic breast cancers expressing low levels of BRCA1.