The tumor suppressor BRCA1 is a translational regulator

BRCA1 inactivation is a hallmark of familial breast cancer, often encountered inaggressive triple negative breast cancers. BRCA1 is a tumor suppressor with knownfunctions in DNA repair, transcription regulation, cell cycle control, and apoptosis. Inthe present study, we demonstrate that BRCA1 is also a translational regulator. Basedon the combination of RNA-binding protein immunoprecipitation and microarrayanalysis, as well as polysome profiling, we identified a subset of mRNAs translationallyregulated by BRCA1 and coding for proteins whose functions play major role in cancer.We found that the level of these key proteins is similarly controlled in humanmammary tumors according to their BRCA1-status. Therefore, our results proposetranslational control as a novel molecular mechanism with clinical relevance throughwhich BRCA1 is a tumor suppressor.