Morin promotes autophagy in human PC3 prostate cancer cells by modulating AMPK/mTOR/ULK1 signaling pathway

AMP-activated protein kinase (AMPK) suppresses tumorigenesis by modulating autophagy and apoptosis. This study evaluated the impact of Morin on PC3 prostate cancerous cells by examining the AMPK/ mechanistic target of rapamycin (mTOR)/ ULK1 (UNC-51-like kinase 1) pathway and autophagy process. The PC3 cells were treated with Morin (50 µg/ml) and AICAR (an AMPK activator). Cell viability, apoptosis, autophagy, and level of phosphorylated and non-phosphorylated ULK1, AMPK, and mTOR, as well as LC3B/LC3A, have been investigated. Through DAPI staining, measurement of Bax/Bcl-2 ratio, Caspase activity, and Annexin V/PI method, it has been revealed that Morin induces apoptosis and reduces the growth of PC3 cells. Morin enhanced the protein level of phosphorylated AMPK (p-AMPK) and ULK1 (p-ULK1) and decreased the expression of phosphorylated mTOR (p-mTOR) in the PC3 cells. Morin could also increase the LC3B/LC3A ratio, Acridine Orange-positive cells, expression of Beclin-1 and ATG5 genes, and decrease the p62 protein level indicating autophagy-inducing. AICAR (an AMPK activator) enhanced the impact of Morin on apoptosis, cell growth, and expression of LC3B, p-AMPK, p-ULK1, and p-mTOR proteins in the PC3 cells. These findings suggest that Morin induces apoptotic and autophagic cell death by activating AMPK and ULK1 and suppressing mTOR pathways.