Abstract
Oligonucleotides with an antiproliferative activity for human cancer cells have attracted attention over the past decades; many of them have a G-quadruplex structure (GQ), and a cryptic target. In particular, DNA oligonucleotide HD1, a minimal GQ, could inhibit proliferation of some cancer cell lines. The HD1 is a 15-nucleotide DNA oligonucleotide that folds into a minimal chair-like monomolecular antiparallel GQ structure. In this study, for eight human cancer cell lines, we have analyzed the antiproliferative activities of minimal bimodular DNA oligonucleotide, biHD1, which has two HD1 modules covalently linked via single T-nucleotide residue. Oligonucleotide biHD1 exhibits a dose-dependent antiproliferative activity for lung cancer cell line RL-67 and cell line of central nervous system cancer U87 by MTT-test and Ki-67 immunoassay. The study of derivatives of biHD1 for the RL-67 and U87 cell lines revealed a structure-activity correlation of GQ folding and antiproliferative activity. Therefore, a covalent joining of two putative GQ modules within biHD1 molecule provides the antiproliferative activity of initial HD1, opening a possibility to design further GQ multimodular nanoconstructs with antiproliferative activity-either as themselves or as carriers.