ABSTRACT
Breast cancer is the most frequent cancer diagnosed in women and the second most common cancer-causing death worldwide. The major problem around the management of breast cancer is its high heterogeneity and the development of therapeutic resistance. Therefore, understanding the fundamental breast cancer biology is crucial for better diagnosis and therapy. Protein sialylation is a key posttranslational modification of glycoproteins, which is also involved in tumor progression and metastasis. Increased expression of sialic acids (Sia) can interfere in receptor-ligand interactions and might protect tumor cells from the immune system. Furthermore, Sia content on the cell membrane plays a role in cancer resistance towards chemo- and radiation therapy. In this study, we glycoengineered MCF-7 breast cancer cells using a series of non-natural Sia precursors, which are prolonged in their acyl side chain. We observed a significant reduction in the natural Sia (N-Acetylneuraminic acid) expression after cultivation of MCF-7 cells with these Sia precursors. In addition, the expression of polySia, a unique glycosylation of the neural cell adhesion molecule NCAM, which interferes with cell adhesion, was decreased. We conclude that sialic acid engineering i) opens up novel opportunities to study the biological role of Sia in breast cancer and ii) provides a toolbox to examine the sialic acid-dependent complex cellular alterations in breast cancer cell biology.
Subject(s)
Breast Neoplasms/pathology , Cell Adhesion , Cell Membrane/metabolism , Cell Movement , Glycoproteins/metabolism , Metabolic Engineering , N-Acetylneuraminic Acid/metabolism , Apoptosis , Breast Neoplasms/metabolism , Cell Proliferation , Female , Humans , Neural Cell Adhesion Molecules/metabolism , Tumor Cells, CulturedABSTRACT
Neuroblastoma is the second most frequent extracranial tumor, affecting young children worldwide. One hallmark of tumors such as neuroblastomas, is the expression of polysialic acid, which interferes with adhesion and may promote invasion and metastasis. Since tumor cells use glycolysis for energy production, they thereby produce as side product methylglyoxal (MGO), which reacts with proteins to advanced glycation end products in a mechanism called glycation. Here we analyzed the expression of (poly) sialic acid and adhesion of Kelly neuroblastoma cells after glycation with MGO. We found that both sialylation and polysialylation is increased after glycation. Furthermore, glycated Kelly neuroblastoma cells had a much higher potential for migration and invasion compared with non-glycated cells.
Subject(s)
Glycolysis/genetics , Neuroblastoma/genetics , Sialic Acids/metabolism , Cell Adhesion , Cell Movement , Female , Glycosylation , Humans , Infant , Male , Neoplasm Metastasis , Neuroblastoma/pathologyABSTRACT
BACKGROUND: Sialic acids (Sia) represent negative-charged terminal sugars on most glycoproteins and glycolipids on the cell surface of vertebrates. Aberrant expression of tumor associated sialylated carbohydrate epitopes significantly increases during onset of cancer. Since Sia contribute towards cell migration (â=â metastasis) and to chemo- and radiation resistance. Modulation of cellular Sia concentration and composition poses a challenge especially for neuroblastoma therapy, due to the high heterogeneity and therapeutic resistance of these cells. Here we propose that Metabolic Sia Engineering (MSE) is an effective strategy to reduce neuroblastoma progression and metastasis. METHODS: Human neuroblastoma SH-SY5Y cells were treated with synthetic Sia precursors N-propanoyl mannosamine (ManNProp) or N-pentanoyl mannosamine (ManNPent). Total and Polysialic acids (PolySia) were investigated by high performance liquid chromatography. Cell surface polySia were examined by flow-cytometry. Sia precursors treated cells were examined for the migration, invasion and sensitivity towards anticancer drugs and radiation treatment. RESULTS: Treatment of SH-SY5Y cells with ManNProp or ManNPent (referred as MSE) reduced their cell surface sialylation significantly. We found complete absence of polysialylation after treatment of SH-SY5Y cells with ManNPent. Loss of polysialylation results in a reduction of migration and invasion ability of these cells. Furthermore, radiation of Sia-engineered cells completely abolished their migration. In addition, MSE increases the cytotoxicity of anti-cancer drugs, such as 5-fluorouracil or cisplatin. CONCLUSIONS: Metabolic Sia Engineering (MSE) of neuroblastoma cells using modified Sia precursors reduces their sialylation, metastatic potential and increases their sensitivity towards radiation or chemotherapeutics. Therefore, MSE may serve as an effective method to treat neuroblastoma.
