Abstract Background: Glycosylation profoundly influences the interactions between cancer cells and microenvironmental stromal cells during the peritoneal disseminated metastasis of ovarian carcinoma (OC), which is the major cause of cancer-related death. Although the characteristic cancer glycoconjugates are widely used as biomarkers for cancer diagnosis, our knowledge about cancer glycome remains quite fragmented due to the technique limitations in analyzing glycan chains with tremendous structural and functional heterogeneity. Method: Given the dysregulated cancer glycome is defined by the altered glycosylation machinery, here we performed a systematic loss-of-function screen on 498 genes involved in glycosylation for key regulators of OC dissemination. We identified neuraminidase 4 (NEU4), an enzyme capable of hydrolyzing terminal sialic acid from glycoconjugates, as a vital peritoneal dissemination-promoting modifier of OC glycome. What’s more, we also identified membrane proteins whose sialylation was able to be modified by NEU4 in OC cells by pull down and mass spectrum to investigate the functional significance of NEU4-mediated desialylation. Results: In human patients with high-grade serous OC (HGSOC), increased NEU4 was detected in the disseminated OC cells when compared with that in the primary tumor cells, which significantly correlated with the worse survival. Among three alternative splice-generated isoforms of human NEU4, we revealed that only the plasma membrane-localized NEU4 isoform 2 (NEU4-iso2) and intracellular isoform 3 promoted the peritoneal dissemination of OC by enhancing the cell motility and epithelial-mesenchymal transition. We also identified NEU4-iso2-regulated cell surface glycoproteome and found that NEU4-iso2 desialylated the epithelial growth factor receptor (EGFR), in particular at N196 residue, for the hyperactivation of EGFR and its downstream tumor-promoting signaling cascades. Conclusion: Our results provide new insights into how the OC glycome is dysregulated by NEU4 during OC progression and reveals a functionally important glycosite on EGFR for its abnormal activation in cancer. Citation Format: Jie Shi, Rui Zhou, Shuo Wang, Yuxin Liu, Baorui Tian, Yanhua Liu, YaNan Chen, Taoyu Hu, Yuhao Mu, Shufan Wang, Xintao Shao, Jie Yan, Pengpeng Qu, Wei Ding, Shuang Yang, Yi Shi, Jia Li, Longlong Wang. NEU4-mediated desialylation ignites the oncogenic receptors for the dissemination of ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1564.
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