Overexpression of PTGS2, an inducible inflammatory gene, has a special role to begin the tumourogenesis and angiogenesis, and to increase of colorectal tumouric polyps. The other studies have shown the potential of G-quadruplex (G4) structure formation of oncogenes promoter. So, the G4 formation on promoter region could be used as a strategy to control the cancer. By QGRS online software the potential of G4 structure in PTGS2 promoter was checked and one sequence (WT-35) was found with G-score of 32 which shows it is a high potential region. Here we investigated whether the targeted sequence structured the G4 formation or not, compares to control negative and positive by using 0-2 μM of TMPyP4 as a G4 stabilizer. The PCR Stop assay and differential pulse voltammetry methods (DPV) were used to determine G4 structure. Based on the PCR Stop assay results, the intensity of PCR product bands decreased under TMPyP4 treatment while the control negative did not change. But there was not any decreasing of PCR product intensity in control negative sequence by increasing of TMPyP4. The normalized fold change of PCR products showed, targeted oligonucleotide product with 1.0 μM TMPyp4 decreased to 0.08 compared to the product of oligonucleotide without TMPyP4. The results of DPV for WT-35 with TMPyP4 showed the peak of G4 structure, same as the control positive oligonucleotide while the control negative did not show this peak. Based on our study, WT-35 sequence that exist in human PTGS2 promoter, is able to form the G4, a novel structure for human PTGS2, especially with TMPyP4 as a G4 stabilizer in this sequence after its treatment by G4 stabilizer.
