Abstract A033: Gangliosides as regulators of the hybrid epithelial-mesenchymal phenotype in pancreatic ductal adenocarcinoma

Abstract

Despite advances in cancer research, the five-year survival rate for pancreatic ductal adenocarcinoma (PDAC) remains only 13%, largely due to early metastasis, the lack of effective treatments against metastatic cancer, and the absence of reliable biomarkers. PDACs and other cancers gain metastatic capability and heightened treatment resistance through high plasticity between epithelial and mesenchymal states, driven mainly by cells that undergo a partial epithelial/mesenchymal transition (pEMT) to adopt a hybrid state. Treatments to target the cells in a hybrid state and their ability to undergo epithelial/hybrid/mesenchymal (E/H/M) state transitions have been hindered by the lack of identification and definition of persistent hybrid cancer cells in primary tumors. We investigated whether hybrid cancer cells have distinct metabolic, transcriptional, and cell-surface glycan and protein profiles that enable the definition of such cells in primary tumors and in-vitro systems. We used 13C tracing, metabolomics, and transcriptional profiling to identify newly produced glycans in epithelial-mesenchymal transitions and multiplexed glycan/protein immunofluorescence and spatial transcriptomics to determine cell-surface glycan and protein profiles in primary tumors and cell culture. We found that cells undergoing EMT increase glycolysis, increase glucose commitment to sialic acid and glycosphingolipid production, and increase transcriptional support of ganglioside and a2,6 sialic acid production. In primary tumors, specific E, H, and M cancer cell subpopulations had distinct cell-surface glycan and protein profiles, and spatially linked clusters of cancer cells with high heterogeneity in E/H/M states had increased ganglioside and a2,6 sialic acid display. In cell culture, such features identified cells in stable hybrid states. Specific gangliosides were associated with highly migratory cells, and knockdown of the B4GALNT1 gene that contributes to ganglioside production induced reversion from the hybrid to the epithelial state. Therefore, cell-surface glycan and ganglioside features identify specific hybrid subpopulations of PDAC cells and potential drivers of E/H/M state transitions. The further characterization of these subpopulations may reveal methods to prevent E/H/M plasticity and reduce the metastatic and treatment-resistant capabilities of PDAC.