Autophagy is a cellular catabolic process that degrades and recycles cellular materials. Autophagy is considered to be beneficial to the cell and organism by preventing the accumulation of toxic protein aggregates, removing damaged organelles, and providing bioenergetic substrates that are necessary for survival. However, autophagy can also cause cell death depending on cellular contexts. Yet, little is known about the signaling pathways that differentially regulate the opposite outcomes of autophagy. We have previously reported that insulin withdrawal (IW) or corticosterone (CORT) induces autophagic cell death (ACD) in adult hippocampal neural stem (HCN) cells. On the other hand, metabolic stresses caused by 2-deoxy-D-glucose (2DG) and glucose-low (GL) induce autophagy without death in HCN cells. Rather, we found that 2DG-induced autophagy was cytoprotective. By comparing IW and CORT conditions with 2DG treatment, we revealed that ERK and JNK are involved with 2DG-induced protective autophagy, whereas GSK-3β regulates death-inducing autophagy. These data suggest that cell death and survival-promoting autophagy undergo differential regulation with distinct signaling pathways in HCN cells.

Triple-negative breast cancer (TNBC) lacks effective targeted therapies, and the mechanisms by which developmental endothelial locus-1 (EDIL3/Del-1) promotes TNBC remain incompletely defined. We profiled Del-1 and AMPK subunits in TNBC cell lines by RT-PCR and immunoblotting, performed functional assays in CRISPR/Cas9 Del-1 knockout and AMPKβ-manipulated cells, and evaluated AMPKβ in early-stage TNBC tumors using tissue microarrays (TMA) (immunohistochemistry; n = 100) and AMPKβ2 mRNA quantification. Del-1 and AMPKβ were enriched in TNBC cells, most prominently in the mesenchymal stem-like subtype, whereas AMPKα levels were relatively stable. Increased Del-1 and activated AMPKβ enhanced proliferation and invasion, while Del-1 deletion reduced AMPKβ expression and suppressed tumor-promoting phenotypes. Mechanistically, Del-1 increased AMPKβ phosphorylation at serine 108, and a phospho-mimetic AMPKβ mutant further amplified oncogenic effects. In the pilot TMA study, high AMPKβ protein expression showed a trend toward poorer DFS in Kaplan–Meier analysis, while multivariate analysis identified high AMPKβ protein expression as an independent factor associated with poorer DFS in patients with early TNBC. These data support AMPKβ as a key mediator of Del-1-driven signaling and suggest AMPKβ could be a therapeutic target in aggressive TNBC subsets.