SRS359 - A novel association between disialoganglioside (GD2), GD2 synthesising enzymes and the Angiomotin family in breast cancer

Disialoganglioside GD2 is a plasma membrane glycosphingolipid synthesised through sequential glycosylation and sialylation facilitated by multiple enzymes. Increasing evidence suggests involvement of GD2 in mammary carcinogenesis and progression where it has been linked with tumour progression, stemness, and epithelial-mesenchymal transition; processes driving metastasis, therapy resistance, and relapse. The current study sought to explore novel GD2 responsive genes, angiomotin family, in breast cancer and their clinical values. The response of breast cancer cell lines (MCF7, MDA-MB-231, SKBR3) to exogenous GD2 was systemically analysed by quantitative mass spectrometry-based proteomics. The potential responsive proteins were validated in a cohort of human breast cancer tissues together with expression of disialoganglioside GD2 synthases using q-PCR and analysed against patient’s clinical outcome. Proteomic analysis identified Angiomotin as a top responsive protein in the TNBC cell line MDA-MB-231, with little change observed for angiomotin-like 1 (Amotl1) and angiomotin-like 2 (Amotl2). In the tissue cohort we found significant correlations between Amot family members and GD2 synthesis enzymes. Notably, significant correlation between Amot and B4GalNT1 (R = 0.386 P = 1.55x10−4), ST8Sia1 (R = 0.465, P = 3.4x10−6), B4GalT5 (R = 0.335 P = 0.001) and B3GalT4 (R = 0.219 P = 0.004). Additionally, Amotl2 showed strong correlations with ST8Sia1 (R = 0.708, P = 4.17x10−15) and B4GalNT1 (R = 0.704, P = 6.65x10−15). Combined abnormality of angiomotin and GD2 enzymes rendered unfavourable overall survival of the patient. This study identifies a novel association between the Amot protein family and GD2 synthesising enzymes in breast cancer suggesting contribution of Amot proteins to GD2 driven tumour behaviour. Future investigation is required to validate these findings and explore translational potential.