Abstract
BACKGROUND
G-quadruplex folding oligodeoxyribonucleotides (G4 ODNs) are considers to be potential anticancer agents, because G4 interferes with some functions of cell, like survival, proliferation, ets, by interacting with G4 binding regulatory proteins. There are some experimental data on anti-proliferative activities of G4: for telomerase complex, aptamers for STAT3, nucleolin, TOP1, SP1, VEGF, and SHP-2, but there is no molecular mechanism yet. Because ODNs are supposed to block regulatory proteins, like cryptic aptamers do, they could be potentially therapeutics, like monoclonal antibodies. The only current approach to find proper model for G4 plus reference cell line, is to screen sets of G4 for sets of cancer cell lines. To avoid selection from large number of G4 structures, we have initiated anti-proliferative study of minimal DNA nano-construct biHD1, built from two minimal active G4 15-mer, by testing 7 human cancer cell lines, including glioblastoma (GBM): U87 and primary cultures from GBM surgery samples.
MATERIAL AND METHODS
ODN were from Evrogen (Russia). ODN were folded: heated to 950C, slowly cooled to 250C. biHD1, GGTTGGTGTGGTTGG TGGTTGGTGTGGTTGG, and derivatives with G4 structure variations. CD in saline phosphate, pH 7.5; CHIRASCAN (UK) and MARK-5 (France); melting curves at 294 nm. 7 human cancer cell lines: colon, HCT116; prostate, PC3; lung, RL-67; breast adenocarcinoma, MCF7; melanoma, mS; HeLa; GBM, U87 and primary cultures from surgery samples; and human embryonic fibroblast, hEF, as control. MTT for cell viability by colorimetric measurements of metabolic activity (Tecan plate reader, Switzerland). ODN: 0.10 μM, 1.0 μM, 10 μM for 3 days.
RESULTS
biHD1 is dose-dependent toxic for several human cancer cell lines, most active for lung cancer RL-67 and GBM U87, survival at 10 μM ODN 35% and 45%, respectively. According to data for biHD1 derivatives with deviations from G4 conformation: length of linker joining modules, light distortions of loops, strong distortions of G4, freezing of G4 conformation, it is G4 fold which is responsible for toxicity for U87 cell line.
CONCLUSION
Cell survival after treatment with G4 minimal bimodular DNA oligonucleotide biHD1 and its derivatives have been tested for 7 human cancer cell lines, including CNS, U87. biHD1 is toxic for cancer cells, but not for embryonic fibroblast, as control; activity depends on G4 fold. Therefore, it is possible to manipulate with minimal G4 as module, and build G4 nano-construct being toxic for cancer cells, including GBM, U87.
Research is supported by RFBR grants 17-00-00157, 18-29-01047
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