Abstract Breast cancer is the second most common cause of brain metastasis, often in advanced-stage disease. The mechanisms underlying breast cancer brain metastasis (BCBM), particularly how tumor cells cross the blood-brain barrier and adapt to the brain environment, remain unclear. Cell surface glycosylation plays diverse roles, and its dysregulation in cancer can disrupt signaling and promote metastasis. We investigated how changes in cell surface N-glycans contribute to BCBM by analyzing N-glycans released from human breast cancer cell lines (MDA-MB-231, MDA-MB-361, HTB-131, HTB-22), a brain-seeking variant (MDA-MB-231BR), and glioblastoma cells (CRL-1620) using nano liquid chromatography-tandem mass spectrometry (LC-MS/MS). Surface N-glycans were enzymatically released from live cells with PNGase F without compromising membrane integrity. Results showed the 231BR cell line expressed higher levels of sialylated N-glycans than other cells, with N-glycan 4502 as the most abundant. Four sialylated structures (4501, 4502, 3501, 5602) were significantly elevated in 231BR, suggesting a role in brain metastasis. This study expands understanding of altered N-glycan profiles in BCBM and highlights potential molecular features linked to brain colonization. Further research on these N-glycans could clarify their function in mediating metastasis and identifying therapeutic targets. Citation Format: Judith Nwaiwu, Wenjing Peng, Akhila Reddy, Xue Dong, Parisa Ahmadi, Jingfu Zhao, Yifan Huang, Peilin Jiang, Waziha Purba, Oluwatosin Daramola, Yehia Mechref, . Altered cell surface N-glycosylation implicates hypersialylation in breast cancer brain metastasis abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7660.
Nwaiwu et al. (Fri,) studied this question.