PRIMA-1met induces autophagy in colorectal cancer cells through upregulation of the mTOR/AMPK-ULK1-Vps34 signaling cascade

Abstract

p53-reactivation and induction of massive apop- tosis-1, APR-017 methylated (PRIMA-1met; APR246) targets mutant p53 to restore its wild-type structure and function. It was previously demonstrated that PRIMA-1met effectively inhibited the growth of colorectal cancer (CRC) cells in a p53-independent manner, and distinctly induced apoptosis by upregulating Noxa in p53-mutant cell lines. The present study including experiments of western blotting, acridine orange staining and transmission electron microscopy revealed that PRIMA-1met induced autophagy in CRC cells independently of p53 status. Importantly, PRIMA-1met not only promoted autophagic vesicle (AV) formation and AV-lysosome fusion, but also increased lysosomal degradation. Furthermore, Cell Counting Kit-8 assay, colony formation assay and small interfering RNA transfection were performed to investigate the underling mechanisms. The study indicated that activa- tion of the mTOR/AMPK-ULK1-Vps34 autophagic signaling cascade was key for PRIMA-1met-induced autophagy. Additionally, autophagy served a crucial role in the inhibi- tory effect of PRIMA-1met in cells harboring wild-type p53, which was closely associated with the increased expression of Noxa. Taken together, the results determined the effect of PRIMA-1met on autophagy, and further revealed mechanistic insights into different CRC cell lines. It was concluded that PRIMA-1met-based therapy may be an effective strategy for CRC treatment.