SIRT1 and breast cancer: In this sense, it is overexpressed in primary samples of cancer patients [1,2] and has been linked to disease progression [3,4] and resistance to treatment [5] and is known to be overexpressed in drug-resistant cells of SKN-SH neuroblastoma, SaOS2 osteosarcoma, MCF7 breast cancer, A2780 ovarian, and IGROV1 cells [6]; however, different studies have shown an ambiguous role for SIRT1, also placing it as a tumor suppressor.