Site-specific glycoproteomic analysis identifies decreasing TMX3 associated with breast cancer tumorigenesis via Notch signaling pathway

Abstract Numerous studies have demonstrated that protein glycosylation participated in cancer progression. However, the site-specific glycoproteomic analysis and potential targets of breast cancer (BC) are largely unknown. In this study, the intact glycopeptides of BC cells were enriched and investigated by applying mass spectrometry-based glycoproteomic strategies, followed by the widespread mapping of site-speific glycan structures via StrucGP. Cell viability, colony formation, migration assays and in vivo tumorigenesis were performed to assess the biological functions of unique glycoprotein TMX3. Glycoproteomic analysis revealed that glycoproteins with core fucosylated and sialylated glycan structures may be extremely associated with focal adhesion, ECM-receptor interaction, cell proliferation, migration, and notch signaling. Meanwhile, we found that ITGA2, ITGA3, ITGAV, ITGB1, NT5E, PLAUR, BTD, P4HTM, TMX3, SUMF1, MBTPS1, MAN2B2, GNPTG, CD40, and PLAT may have considerable predictive advantages in BC. Among them, decreased TMX3 suggested poor medical ending in BC patients. Notably, TMX3 was significantly down-regulated in BC cell lines and function assays showed that TMX3 overexpression inhibited BC cell proliferation, migration, and epithelial-mesenchymal transition (EMT) markers both in vitro and in vivo by repressing Jagged 1/Notch1 pathway. In conclusion, our results demonstrate that TMX3 might function as an oncogene to promote BC progression by activating Jagged 1/Notch1 pathway.