SIRT1 and breast cancer: SIRT1 is a mammalian NAD+-dependent deacetylase that is also referred to as class III histone deacetylases; this deacetylase is involved in several tumor progressions, such as melanoma, breast cancer, and CRC, via inhibition of cell proliferation.31, 32 SIRT1 exerts multiple effects on cellular metabolism, DNA repair, and senescence by deacetylating a variety of un-histone proteins, including p53.