DBC1/KIAA1967 (deleted in
breast cancer 1) is a putative tumor-suppressor gene cloned from
breast cancer specimens and is reported to regulate p53-dependent apoptosis through its specific inhibition of
SIRT1 deacetylase. Although
SIRT1 plays a pivotal role in
carcinogenesis by regulating cellular proliferation, survival and death, its role in
breast cancer remains controversial. Therefore, we aimed to investigate the expression status and clinicopathological significance of DBC1 and
SIRT1 in
breast cancer tissues. We evaluated the expression of DBC1 and
SIRT1 in breast core-needle biopsy specimens from 48 primary
breast cancer patients between 2005 and 2008. These patients were treated with primary systemic
chemotherapy and subsequent surgical resection of the lesions. Immunohistochemical expression scores of DBC1 and
SIRT1 were evaluated, and the relationship between their expression levels and clinicopathological features of
breast cancer was analyzed. The expression was observed exclusively in the nuclei of normal and neoplastic ductal cells. In breast biopsy specimens, positive expression of DBC1 and
SIRT1 was noted in 85 and 98% of patients, respectively. Expression of DBC1 was significantly associated with the
tumor nuclear grade (P=0.019). DBC1 and
SIRT1 expression was inversely correlated with HER2 expression (P=0.026 and 0.003, respectively). Lower expression of DBC1 and
SIRT1 indicated a tendency for a favorable pathological response to
chemotherapy, although this was not statistically significant. Our results reveal that the expression of DBC1 and
SIRT1 in breast tissues is associated with
tumor characteristics.