Thrombin binding aptamer analogues containing inversion of polarity sites endowed with antiproliferative and anti-motility properties against Calu-6 cells

Background: Although the thrombin binding aptamer (TBA) is endowed with both anticoagulant and anti proliferative properties, it is possible to reduce the first and enhance the second one by suitable chemical modifications. Methods: Two oligonucleotides (TBA353 and TBA535) based on the TBA sequence (GGTTGGTGTGGTTGG) and containing inversion of polarity sites have been investigated by CD, UV and electrophoretic techniques for their ability to form G-quadruplex structures. Furthermore, their anticoagulant (PT assay), antiproliferative (MTT assay) and anti-motility (wound healing assay) properties against Calu-6 cells have been tested and compared with TBA. Results: CD, UV and electrophoresis data indicate that both ODNs are able to form G-quadruplex structures. Particularly, results suggest that TBA535 adopts a G-quadruplex structure characterized by a loop arrangement different from that of TBA. Both TBA analogues drop the anticoagulant activity. However, TBA535 is endowed with a significant antiproliferative activity against lung cancer Calu-6 cells. Importantly, both TBA and TBA535 possess a remarkable anti-motility property against the same cell line. Conclusions: Both TBA analogues TBA353 and TBA535 are able to form G-quadruplex structures with no anticoagulant activity. However only TBA535 is endowed with noteworthy antiproliferative and anti-motility properties against lung cancer Calu-6 cells. General significance: The switching from the anticoagulant to antiproliferative property can be obtained also in TBA derivatives not adopting the chair-like G-quadruplex structure typical of TBA. Furthermore, results have highlighted an unprecedented anti-cell-motility property of TBA and TBA535 reinforcing the potential of these ODNs as anticancer drugs.