Liraglutide attenuates obese-associated breast cancer cell proliferation via inhibiting PI3K/Akt/mTOR signaling pathway

This study aims to explore the anti-proliferative, pro-apoptotic, and anti-migration activities of liraglutide (LGT) in MCF-7 breast cancer (BC) cells in subjects with obesity, particularly its effects on the PI3K/Akt/mTOR/AMPK pathway. The role of AMPK/SIRT-1, an essential regulator of adipokine production, in the effect of LGT on the production of adipose-derived adipokine was also assessed. MCF-7 cells were incubated in conditioned medium (CM) generated from adipose-derived stem cells (ADSCs) of obese subjects. MCF-7 cells were then treated with LGT for 72 h. Anti-proliferative, pro-apoptotic, and anti-migration activities were investigated using alamarBlue, annexin V stain, and scratch assay, respectively. Protein levels of phosphorylated PI3K, p-Akt, p-mTOR, and p-AMPK were investigated using immunoblotting. Levels of adipokines in ADSCs were determined using RT-PCR before and after transfection of ADSCs using the specific small interference RNA sequences for AMPK and SIRT-1. LGT evoked anti-proliferative, apoptotic, and potential anti-migratory properties on MCF-7 cells incubated in CM from obese ADSCs and significantly mitigated the activity of the PI3K/Akt/mTOR survival pathway-but not AMPK-in MCF-7 cells. Furthermore, the anti-proliferative effects afforded by LGT were similar to those mediated by LY294002 (PI3K inhibitor) and rapamycin (mTOR inhibitor). Our results reveal that transfection of AMPK/SIRT-1 genes did not affect the beneficial role of LGT in the expression of adipokines in ADSCs. In conclusion, LGT elicits anti-proliferative, apoptotic, and anti-migratory effects on BC cells in obese conditions by suppressing the activity of survival pathways; however, this effect is independent of the AMPK/SIRT1 pathway in ADSCs or AMPK in BC cells.