The PI3K/AKT/mTOR pathway was involved in regulating FASN expression in ER+/HER2+ breast cancer cells.

<p>A, PI3K inhibitor LY294002 (25 µmol/L, 12 h) could down-regulate the expression of pAKT, pmTOR and FASN but had no effect on the expression of total AKT or mTOR. B, The transcriptional activity of FASN promoter was obviously decreased in all the three breast cancer cell lines in response to LY294002(25 µmol/L, 12 h). The decrease in the transcriptional activity of the FASN promoter was most pronounced in MCF-7/HER2 cells (MCF-7/HER2 86.09%; SKBR3, 80.27%; and MCF-7, 69.05%). C, mTOR inhibitor rapamycin (20 nmol/L, 12 h) up-regulated the expression of pAKT but had no effect on total AKT levels. Rapamycin (20 nmol/L, 12 h) could up-regulate the expression of pAKT and down-regulate the expression of downstream targets of mTOR such as 4EBP-1 and pp70S6K and FASN, whereas the expression of 4EBP-1 and p70S6K did not change.