Evaluation of Sirt1 And Foxo’s In Primary Tumor And Distant Organ Metastasis Invaded By Benign And Highly Metastatic Breast Carcinoma Cells Under In Vitro And In Vivo Conditions.
Abstract Breast cancer is the second most common cancer in women. In malignant breast cancers, tumor cells have the potential to metastasize to distant organs through the lymphatic system and blood circulation. The aim of this study is to evaluate the expression of SIRT1 and FoxO proteins in metastatic and nonmetastatic breast cancer cells and distant organs metastasis. In our study, SIRT1, p53, p21, and FoxO proteins have been evaluated in metastatic 4TLM and non-metastatic 67NR cell lines by immunocytochemistry in vitro and also in mice breast cancer model in vivo. Cells were orthotopically injected to mammary fat pads of 8-10 weeks old Balb/c female mice. Primary tumor, lung and liver tissues were removed and expressions of these proteins were evaluated by immunohistochemistry, western blot and RT-PCR. In addition, signal pathways that are related to SIRT and FoxO proteins were examined by using IPA core analysis. TCGA database was browsed for investigation of different genes.In primary tumors, SIRT1, p21, p53, E2F1 and FoxO expressions were higher in 67NR compared to 4TLM. In metastatic lung and liver tissues, the expression levels of SIRT1, FoxO1, FoxO3a and FoxO4 proteins were increased in 4TLM compared to 67NR. IPA and TCGA analysis have also revealed that SIRT1 and FoxO proteins are lower in primary tumors, but increased in metastatic stages. In conclusion, in primary tumors SIRT1 and FoxO expressions were decreased in 4TLM compared to 67NR. Moreover, SIRT1 and FoxO, especially expressed in metastatic cells. High level of FoxO expressions in metastatic stages in TNBC patients also supports its association with metastasis. Our findings suggest that SIRT1 and FoxO’s have crucial role in tumor progression metastatic process in breast cancer.