Varieties of interactions of anti-CD133 aptamers with cell cultures from patient glioblastoma

Development of aptatheranostics for glioblastoma (GB) requires investigating aptamer interactions with cells. The paper has described flow cytometry (FC) assessment of direct interactions of fluorescent anti-CD133 aptamers with cells, focusing on cell cultures derived from patient GB (CCPGB). Conventional cell lines with different levels of CD133 mRNA, Caco-2 and HCT116, were used to compare interactions with known 2′FY-RNA aptamer A15 and DNA aptamers of Ap and Cs series, labeled with FAM and Cy5. In addition, interactions of certain non-aptameric oligonucleotides were studied. In the case of antibody interactions with cells, FC signals, mean fluorescence intensities (MFIs), correlated with sizable amounts of CD133 mRNA in Caco-2 cells, and CCPGBs 107 and G01. Unexpectedly, MFI per se could not be the solid indicator of specific interactions of aptamer - CD133/cell. Instead, two types of interactions, target CD133-driven and off-target membrane-associated ones, contribute to MFI. The latter was notably observed for CCPGB Sus/fP2 with tiny CD133 mRNA amount. To prove specificity of aptamer - CD133/cell interactions, titration experiments have been performed, revealing half-saturation concentrations of 120±27 for 2′FY-RNA A15 and 180±12 for DNA Cs5 with Caco-2 cells. This knowledge is an essential step to develop aptatheranostics for GB.