SIRT1 and breast carcinoma: Consistent with these findings, significant correlations between miR-155-5p, SIRT1, and EMT markers were observed in PIK3CAMUT HR + breast cancer cells following co-culture with MDSCs, suggesting activation of the miR-155-5p/SIRT1 axis in PIK3CAMUT HR + breast cancer (Fig. 5C–D).