Connecting sialic acid expression to cancer cell characteristics : Novel tools for detection, imaging, and analysis

Abstract: Sialic acid (SA) plays a crucial role in many biological processes. Cell surface SA expression is usually analyzed with antibodies or lectins; however, they are costly and with poor stability. We have used a molecular imprinting technique to synthesize an alternative SA receptor – SA molecularly imprinted polymers(SA-MIPs) with an embedded fluorophore for fluorescent detection of theSA-MIPs. The binding behavior and specificity of SA-MIPs were verified by using lectins and SA conjugates on cancer cell lines, showing that SA-MIPs can be used as an effective tool for SA expression analysis of cancer cells. Digital holographic cytometry (DHC) is a non-phototoxic quantitative phase imaging technique that facilitates the monitoring of living cells over time. We have demonstrated the potential of DHC by mapping cellular parameters, such as cell number, area, thickness, and volume. In addition, cellular parameters possibly depending on sialylation, were evaluated using DHC. Furthermore, the uptake over time of SA-MIPs by macrophages was investigated for any inflammatory and/or cytotoxic responses when administered to phagocytosing cells. Our results indicate that SA-MIPs caused low induction and sparse secretion of inflammatory cytokines, and that reduced cell proliferation was not due to cytotoxicity, but to attenuated cell cycles. These results suggest that SA-MIPs will contribute to the further understanding of cancer cell behavior and can be an asset for in vivo studies.

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