Professor Natsuko CHIBA, MD, PhD
Assistant Professor Yuki YOSHINO, MD, PhD
Assistant Professor Zhenzhou FANG, MD, PhD

Approximately 5% -7% of all breast cancers are inherited, and the two most important breast cancer susceptibility genes, BRCA1 and BRCA2, were identified by linkage analysis of familial breast cancers. Mutations of BRCA1 and BRCA2 have been identified in 25% of familial breast cancers. These breast cancers are collectively referred to as Hereditary Breast and Ovarian Cancer Syndrome (HBOC). In addition to hereditary cancer, it has been reported that BRCA1 is involved in a subtype of sporadic breast cancer, triple-negative breast cancer, and in the chemosensitivity of various cancers. BRCA1 is also involved in many cellular processes, including DNA repair and centrosome regulation. Defects in the regulatory mechanisms of the centrosome and DNA repair result in defective mitoses, chromosome segregation errors, and the accumulation of DNA damage, which are significant sources of genome instability, and a hallmark of cancer. Our research specifically focuses on the functions of BRCA1 in DNA repair and centrosome regulation. To analyze the functions of BRCA1 and its related proteins, we performed cytological analyses, analyses using genetically modified mice, and analyses of clinical specimens. We believe that this research will contribute to the further understanding of carcinogenesis and aid in developing novel cancer therapies.