In 80–100% of cases, the transformation of human somatic cells into tumor cells is associated with of the catalytic subunit of telomerase, reverse transcriptase (hTERT), increased expression. hTERT gene transcription inhibition in tumor cells may become one of the approaches to antitumor therapy. The hTERT promoter contains a G-rich region with a length of 68 nucleotides, which is capable of forming G-quadruplexes (G4) under certain conditions in vitro. It is known that G4s interfere with the human RNA polymerases activity. Thus, G4 structure stabilization in the promoter can be considered as a possible way to reduce hTERT expression. To prove the G4 formation in the G-rich sequence of the hTERT promoter in a double-stranded supercoiling DNA, plasmid constructs based on the pRFPCR plasmid were obtained. The plasmids contained genes of fluorescent proteins (RFP and Cerulean) and the central hTERT promoter region G4. The hTERT promoter region central G4 formation in the obtained constructs was demonstrated with the DNA polymerase stop assay method. The influence of G228A and G250A substitutions on G4 stability in physiological conditions was investigated. It was established that the low molecular weight ligands BRACO19 and TMPyP4, well-studied stabilizers of the G4 structure, can effectively interact with the hTERT promotor central G4 in the range of concentrations 5–25 μM.
Iakushkina et al. (Wed,) studied this question.