SIRT1 and breast cancer: While, SIRT1, 4, 5, and 7 have been reported to be upregulated in certain cancers (70–72), the same SIRT1as well as SIRT2 and SIRT6 is shown to be downregulated in breast cancer, hepatic cell carcinoma (73), gliomas, gastric carcinomas (74, 75) and colon adenocarcinoma (76).