Macroautophagy promotes cellular homeostasis by delivering cytoplasmic constituents to lysosomes for degradation [Mizushima, Nat. Cell Biol. 20, 521–527 (2018)]. However, while most studies have focused on the mechanisms of protein degradation during this process, we report here that macroautophagy also depends on glycan degradation via the glycosidase, α- l -fucosidase 1 (FUCA1), which removes fucose from glycans. We show that cells lacking FUCA1 accumulate lysosomal glycans, which is associated with impaired autophagic flux. Moreover, in a mouse model of fucosidosis—a disease characterized by inactivating mutations in FUCA1 [Stepien et al. , Genes (Basel) 11, E1383 (2020)]—glycan and autophagosome/autolysosome accumulation accompanies tissue destruction. Mechanistically, using lectin capture and mass spectrometry, we identified several lysosomal enzymes with altered fucosylation in FUCA1-null cells. Moreover, we show that the activity of some of these enzymes in the absence of FUCA1 can no longer be induced upon autophagy stimulation, causing retardation of autophagic flux, which involves impaired autophagosome–lysosome fusion. These findings therefore show that dysregulated glycan degradation leads to defective autophagy, which is likely a contributing factor in the etiology of fucosidosis.

PDAC is predicted to become the second commonest cause of cancer death in the western world by 2030. Aggressive invasion and early metastases are characteristic of the disease, and even the few patients eligible for potentially curative resection inevitably develop recurrent or metastatic disease. We now show that CXCR2 signalling is upregulated in human pancreatic cancer, predominantly in neutrophils at the tumour invasive edge. In mouse models, genetic ablation or inhibition of CXCR2 abrogated metastasis while inhibition also slowed tumorigenesis, particularly when combined with chemotherapy. Depletion of neutrophils also suppressed metastasis, suggesting a key role for CXCR2 in establishing and maintaining the metastatic niche. Indications from trials thus far suggest that immunotherapy will not work as a single agent strategy in pancreatic cancer patients. Importantly, we find that loss or inhibition of CXCR2 improved T-cell entry and combined inhibition of CXCR2 and PD1 in mice with established disease caused a significant extension of survival. Thus, our data highlight two novel therapeutic opportunities for PDAC: first the use of CXCR2 inhibitors in surgically-resected patients to prevent recurrence at distant sites, and second, the use of CXCR2 inhibition in combination with immunotherapy in surgically unresectable advanced disease. This abstract is also being presented as Poster B55 Citation Format: Colin Steele, Saadia Karim, Josh Leach, Peter Bailey, Andrew Biankin, Rob Nibbs, Simon Barry, Owen Sansom, Jen Morton.{Authors}. CXCR2 Inhibition Suppresses Metastasis and Improves the Response to Immunotherapy in Pancreatic Cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr PR10.