Association of miR-34a with metastatic progression through the FoxO3a–SIRT1 regulatory axis in breast cancer

SIRT1 may act as either a tumor suppressor or a tumor promoter, depending on cellular context, signaling pathways, and its specific molecular targets across cancer types. The elevated expression of SIRT1 in 67NR primary tumors suggests a tumor-suppressive role in nonmetastatic settings. However, the increased SIRT1 expression observed in metastatic regions indicates its potential role as a tumor promoter and modulator of the tumor microenvironment, possibly through FoxO3a and miR-34a signaling, thereby enhancing cellular proliferation and invasion.