Transforming Growth Factor-β Drives Epithelial Mesenchymal Transition and Reduces Synthesis of Unelaborated O-GalNAc Glycans in Breast Cancer Cells.

SummaryAltered O-glycosylation of cancer cells is frequently associated with metastasis and poor prognosis. During metastasis, cells must also lose their epithelial characteristics and become mesenchymal and motile, termed epithelial-mesenchymal transition (EMT). While it is established that transforming growth factor beta-1 (TGF-β1) can induce EMT, the effect of cytokine-induced EMT on O-glycosylation of breast cancer cells has not previously been explored. MCF-7 and T47-D breast cancer cells were treated with TGF-β1 over a time course of up to 7 days. Morphological changes were assessed using confocal microscopy and quantified; levels of EMT marker expression were assessed using immunofluorescence with confocal microscopy and western blot. The effect of TGF-β1 on synthesis of unelaborated Tn antigen was explored using agglutinin (HPA) labelling. TGF-β1 treatment induced morphological changes, resulting in an elongated, mesenchymal-like phenotype, and a reduction of epithelial marker E-cadherin but did not detectably induce mesenchymal markers N-cadherin or vimentin. It also resulted in a significant reduction in unelaborated Tn antigen, detected by HPA labelling. These observations are consistent with TGF-β1 inducing an 'early' or partial EMT state over this timeframe, and a concomitant change in O-glycosylation, consistent with the synthesis of more elaborated O-glycan structures; such glycoplasticity may function in metastasis. .