Zinc finger E‐box binding homeobox‐1 (Zeb1) drives anterograde lysosome trafficking and tumor cell invasion via upregulation of Na+/H+ Exchanger‐1 (NHE1)

Abstract

Tumor cell invasion through the extracellular matrix is facilitated by the secretion of lysosomeassociated proteases. As a common mechanism for secretion, lysosomes must first traffic to the cell periphery (anterograde trafficking), consistent with invasive cells often containing lysosomes closer to the plasma membrane compared to non-invasive cells. Epithelial to mesenchymal transition (EMT) is a transcriptionally-driven program that promotes an invasive phenotype, and Zeb1 is one transcription factor that activates the mesenchymal gene expression program. The role of lysosome trafficking in EMT-driven invasion has not been previously investigated. We found that cells with increased levels of Zeb1 displayed lysosomes located closer to the cell periphery and demonstrated increased protease secretion and invasion in 3-dimensional (3D) cultures compared to their epithelial counterparts. Additionally, preventing anterograde lysosome trafficking via pharmacological inhibition of Na+/H+ exchanger 1 (NHE1) or shRNA depletion of ADP-Ribosylation like protein 8b (Arl8b) reversed the invasive phenotype of mesenchymal cells, thus supporting a role for lysosome positioning in EMT-mediated tumor cell invasion. Immunoblot revealed that expression of Na+/H+ exchanger 1 correlated with Zeb1 expression. Furthermore, we found that the transcription factor Zeb1 binds to the Na+/H+ exchanger 1 promoter, suggesting that Zeb1 directly controls Na+/H+ transcription. Collectively, these results provide insight into a novel mechanism regulating Na+/H+ exchanger 1 expression and support a role for anterograde lysosome trafficking in Zeb1-driven cancer progression.

AXL Mediates Esophageal Adenocarcinoma Cell Invasion through Regulation of Extracellular Acidification and Lysosome Trafficking

“…Indeed, cancer-associated peripheral distribution of lysosomes is emerging as important for cell migration and invasion [15] . Consistent with Dykes and colleagues, we found that mesenchymal EAC cell lines expressing high levels of AXL display enhanced anterograde lysosome trafficking and that inhibition of lysosome trafficking by knocking down AXL does not seem to reverse EMT (data not shown) but does inhibit EMT-mediated cell invasion [52] . Moreover, we showed that inhibition of AXL-dependent peripheral distribution of lysosomes by knocking down of ARL8B expression or using niclosamide strongly impairs cell invasion, demonstrating that AXL-mediated cell invasion requires an effective trafficking of lysosomes to the cell periphery.…”

“…Indeed, HGF and its receptor MET have been reported to induce anterograde trafficking of lysosomes through the PI3K pathway, microtubules, RhoA signaling, and activity of sodium-proton exchangers (NHEs) [49] . Moreover, EGF through its receptor EGFR has been shown to induce anterograde lysosomes trafficking through p38 MAPK activity and NHEs [52] . Our study identifies a new signaling cascade involving the AXL RTK, AKT/NF-κB signaling pathway and the lactate transporter MCT-1, promoting the peripheral redistribution of lysosomes and subsequent cell invasion.…”

“…Interestingly, although these RTKs have overlapping downstream signaling pathways, they seem to act through distinct signaling effectors to induce peripheral distribution of lysosomes and cell invasion. EGFR- and MET-induced lysosome anterograde trafficking depends on NHEs in prostate cancer cells ( [49] , [52] ). Although NHE-mediated proton reflux contributes to the acidification of the extracellular environment, expression of NHE1 does not appear to be regulated by AXL in our EAC cell models (data not shown).…”

Lysosome trafficking is necessary for EGF-driven invasion and is regulated by p38 MAPK and Na+/H+ exchangers

“…In support of this, Cardone et al recently found that EGFR forms a complex with NHE1 in pancreatic ductal carcinoma [ 47 ]. Indeed, EGF stimulation is known to activate NHE1 through Janus kinase and calmodulin signaling [ 36 , 37 ] and recently the transcription factor Zeb1 has been reported to control lysosome trafficking resulting in increased cell invasiveness [ 48 ]. Also, NHE1 contains a cytoplasmic tail containing an ezrin-rodoxin-moesin (ERM) domain that associates with proteins that regulate actin polymerization [ 49 , 50 ].…”

Annexins—Coordinators of Cholesterol Homeostasis in Endocytic Pathways

“…On the other hand, the redistribution of LE/Lys towards the cell periphery appears vital for growth, migratory, and invasive properties of cells, ensuring the rapid delivery of membrane and secretory components to the cell surface. Indeed, plus-end (anterograde) transport facilitates lysosomal exocytosis, leading to the secretion of acidic hydrolases and metalloproteinases that degrade the extracellular matrix to promote the migration and invasion of cancer cells [ 191 , 192 , 193 ].…”