| Summary: | Breast cancer is the most common invasive cancer in women worldwide. Sirtuin 1 (SIRT1) has recently been shown to have implications in regulating cancer cell growth and apoptosis. SIRT1 regulates Forkhead box O3a (FOXO3a) by both inhibiting FOXO3-induced apoptosis and potentiating the ability of FOXO3a to resist oxidative stress. Matrix metalloproteinase 2 (MMP2) participates in tumor invasion and metastasis by degrading extracellular matrix. SIRT1 up regulates MMP2 expression by its deacetylation activity. This study aimed to investigate the expression of SIRT1, FOXO3a and MMP2 in breast tissues of women with breast cancer. In addition, the effect of SIRT1 inhibition on both FOXO3a and MMP2 expression in breast cancer (MCF-7) cells was assessed. The expression levels of SIRT1, FOXO3a and MMP2 in the breast tissues were determined by real-time PCR in 60 patients with malignant tumor and in 24 patients with benign tumors. After SIRT1 inhibition, protein levels of SIRT1 and FOXO3a were assessed by Western Blot and levels of MMP2 by ELISA in MCF-7 cells. The expression levels of SIRT1, FOXO3a and MMP2 were significantly higher in breast cancer tissues compared to in benign breast tumor and adjacent normal tissues. SIRT1, MMP2 and FOXO3a expression were associated directly with each other. SIRT1 inhibition suppresses MMP2 and FOXO3a expression compared to control MCF7. Sirtinol (SIRT1 inhibitor) effectively induced inhibition of MMP2 and FOXO3a expression in MCF-7 cells, indicating the promising therapeutic strategy of targeting SIRT1 for breast cancer.
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