SIRT1 and breast carcinoma: Other genes associated with breast cancer progression such as suppressor of cytokine signaling 1 and forkhead box O3a are negatively regulated by miR-155.78 MiR-34a is oftentimes downregulated in breast cancer, which promotes breast cancer growth and survival through upregulation of SIRT1 and BCL2 proteins.79, 80 miR-205 is frequently downregulated in metastatic breast cancer.