Abstract P2-04-03: The roles of fucosylation in promoting tumorigenic signaling in breast cancer

Abstract

Abstract Fucosylation is an important form of protein glycosylation involved in the progression of cancer. Aberrant fucose and fucosylated serum protein/oligosaccharide levels have been previously described in breast cancer (BC). Fucosylation has been reported impact proliferation and key signaling pathways (e.g., ERK1/2, p38 MAPK, and E-selectin) in human breast invasive ductal carcinoma. However, precise roles and functions of fucosylated proteins function in BC remain largely unclear. In our preliminary analyses, we performed immunofluorescent lectin staining of BC tissue microarrays and cell lines grown in vitro and found that fucosylation is increased in BC vs. normal breast tissues. To study the functional contributions of fucosylation to BC biology, we either pharmacologically or genetically suppressed fucosylation in BC cell lines. The treated or modified cell lines were characterized for their ability to grow/proliferate in 2D or 3D, as well as on adhesion to extracellular matrix (ECM). We observed that inhibiting fucosylation blunted BC cell proliferation, particularly in 3D, and attenuated adhesive capacity. To determine the mechanism(s) underlying the biological functions of fucosylation in BC cells, we performed parallel fucosylated and phosphoproteomic mass spectrometric analyses on BC cells that were either pharmacologically or genetically inhibited for fucosylation to identify: (i) all fucosylated proteins in BC cells and (ii) signaling pathways that comprise directly fucosylated proteins and that are significantly altered in activity (phosphorylation). All filtered hits were subject to Ingenuity Pathway Analysis. Thirteen signaling pathways were identified in common amongst both pharmacologically or genetically modulated BC groups. These pathways clustered into the following 3 major functional groups: cell-cell/cell-matrix contact, RNA processing, and endosomal/phagosomal dynamics. The most fucosylated proteins included integrins. We validated the direct fucosylation of integrins and further dissected the molecular and functional contributions of fucosylation to integrin signaling in vitro and in vivo in mouse models of breast cancer. Our data identify new roles for fucosylation in regulating key signal transduction pathways in BC. How integrin signaling and BC cell biology is regulated by fucosylation, as well as potential clinical utility of fucosylated integrins for BC, will be discussed. Citation Format: Kara Snyder, Hui Ren, Daniel Lester, Bin Fang, John Koomen, Eric Lau. H. The roles of fucosylation in promoting tumorigenic signaling in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-04-03.