The relationship between sirtuin 1 (SIRT1) expression and tumor size, Proliferating Cell Nuclear Antigen (PCNA) expression and histological grading in rat breast carcinoma induced by dimethylbenz()anthracene (DMBA)
Controversy regarding the role of SIRT1 in pathology of cancers exists and is still under debate. SIRT1 could act as either a tumor supressor or tumor promotor. This study was conducted to evaluate the relationship between SIRT1 expression and tumor size, Proliferating Cell Nuclear Antigen (PCNA) expression and histological grading in rat breast carcinoma induced by dimethylbenz(a)anthracene (DMBA). Thirty female Sprague Dawley rats were randomly allocated into three groups with 10 rats in each group. Group 1 as negative control was just fed the standard food. Group 2 as vehicle control was fed the standard food and corn oil. Group 3 as induction group was fed the standard food and induced with DMBA at dose of 20 mg/kg body weight (BW) in corn oil twice a week for five weeks. All rats were palpated weekly to determine the appearance, size and location of tumors. Sixteen weeks after DMBA induction rats were sacrified and histological preparations of the breast carcinoma tissue were then processed for SIRT1 and PCNA expression examination as well as histological grading. The result showed that SIRT1 expression was significantly higher in breast carcinoma tissue compared to normal gland (26.12 vs 0.05; p = 0.004). SIRT1-positive was observed mostly in poor histological grade carcinomas (56.2%), and it was not observed in good histological grade carcinomas. However, there was no significantly difference between SIRT1 and histological grading (p = 0.097; r = 0.285). A significant correlation between SIRT1 expression and the tumor size (p =0.009; r =0.877), as well as PCNA expression (p =0.000; r =0.790) was observed. In conclusion, there is relationship between SIRT1 expression and tumor size as well as PCNA expression in rat breast carcinoma induced by DMBA.