PGM3 inhibition shows cooperative effects with erastin inducing pancreatic cancer cell death via activation of the unfolded protein response

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with a poor patient prognosis. Remarkably, PDAC is one of the most aggressive and deadly tumor types and is notorious for its resistance to all types of treatment. PDAC resistance is frequently associated with a wide metabolic rewiring, particularly the glycolytic branch named hexosamine biosynthetic pathway (HBP) whose final product is the uridine-5′ diphospho-N-acetyl-Dglucosamine (UDP-GlcNAc), the main substrate for O- and N- protein glycosylation. These post-translational modifications play critical roles in several protein features such as folding, activity, and function. Therefore, we have recently developed and tested a novel compound, FR054, capable of diminishing the HBP flux by targeting the HBP enzyme PGM3. Here, we performed transcriptional and bioinformatic analysis to obtain further information about HBP inhibition. Moreover, we used cell count, western blot, HPLC, and metabolomics analysis to determine the impact of the combined treatment between FR054 and erastin (ERA), a recognized ferroptosis inducer, on PDAC cell growth and survival. Of note, the combined treatment applied to PDAC cell lines induces a significant decrease in cell proliferation and a concurrent enhancement of cell death. Furthermore, this combined treatment induces unfolded protein response (UPR), NFE2-like BZIP transcription factor 2 (NRF2) activation, a change in cellular redox state, a greater sensitivity to oxidative stress, a major dependence on glutamine metabolism, and finally ferroptosis cell death. Our study discloses that HBP inhibition enhances, through UPR activation, the ERA effect and therefore might be a novel anticancer mechanism to be exploited as PDAC therapy.