The Effect Of The Oligonucleotide Aptamer AS1411on Radiosensitization Of Hela Cancer Cells

Objective：To investigate the effects of AS1411on the Uterine Cervical Cancer HeLa cells inradiosensitivity and relative mechanism, we detected the cell survival rate and observedthe repair of DNA damage、cell cycle arrest and cell apoptosis of HeLa cells pretreatedby different concentrations of theAS1411combined with radiation.Methods:CCK-8assay was used to measure the cell proliferation-toxic effects of theAS1411on HeLa cells. Colon forming assay was adopted to study the effects of thethe cells survival rate of the HeLa cells under AS1411exposure to X-ray; γ-H2AXimmunofluorescence technique was applied to observe the double-stranded DNAbreaks of HeLa cells, which was for studying the effect of AS1411on double-strandedDNA breaks of HeLa cells caused by X-ray; The change in cell cycle and cell apoptosiswere examined using flow cytometry.Results：(1) The CCK-8experimental results showed that the cell toxicity of AS1411wassmall; all the survival rates of HeLa cells were more than94%when the AS1411withdifferent concentrations were used to treat the cells for24h,48h, and72h, respectively.Colon forming assay showed that there was a significant difference between HeLa cellspretreated by different concentrations AS1411and that treated by different irradiationdoses(P<0.05). The low-dose zone curve became smaller and the linear slope increasedsignificantly. The survival rate of all dose points was lower than the control group,indicatingAS1411had a significant radiosensitivity effect on the HeLa cells.(2) DNA damage experimental results demonstrated that γ-H2AX foci of HeLacells increased significantly after treated by AS1411; There were more γ-H2AX foci numbers up to24h in AS1411-treated cells than the control-treated cells; γ-H2AX fociin cells of the drug&irradiation group were clearly more than the irradiation alonegroup when HeLa cells were radiated with4Gy and8Gy; When the concentration ofAS1411was1μmol/L and the irradiation dose was4Gy and8Gy, the γ-H2AX focinumbers of HeLa cells were21.024±2.25and61.052±2.68in turn, and the γ-H2AX focinumbers of of HeLa cells the corresponding irradiation alone group were9.681±2.13and20.789±2.73.(3) The cell cycle experimental results showed it was an increase in the fraction ofcells in the S phase of the cell cycle (G0/G1phase、S phase and G2/M phase) for cellstreated with AS1411compared with the control group; Following exposure to dose of8Gy X-ray, HeLa cells were induced cell cycle arrest in G2/M phase, but AS1411pretreatment could not affect the G2/M arrest caused by irradiation. Therefore, weinferred that the mechanism of AS1411enhancing the radiosensitization of HeLa cellswas uncorrelated with cell cycle.(4) Results of cell apoptosis showed that AS1411in combination with radiationcould enhance the apoptosis of the HeLa cells; The early apoptosis rates ofAS1411-treated cells(500nmol/L group and1μmol/L group) were7.71±1.51%and91±1.04%, respectively, while the early apoptosis rates of control group was5.86±0.81%; The apoptosis rates of the drug&irradiation group were higher than theirradiation alone group when HeLa cells were radiated with4Gy and8Gy; The earlyapoptosis rates of AS1411-treated cells(500nmol/L group and1μmol/L group) were19.67±1.90%and21.31±1.74%when HeLa cells were radiated with4Gy, while theearly apoptosis rates of the irradiation alone group was15.44±2.41%; The earlyapoptosis rates of AS1411-treated cells(500nmol/L group and1μmol/L group) were39.02±1.91%and41.99±0.65%when HeLa cells were radiated with8Gy, while theearly apoptosis rates of the irradiation alone group was35.90±2.92%.Conclusions:(1) AS1411did not show the cell toxicity on the HeLa cells. Colon forming assayshowed thatAS1411had a significant radiosensitivity effect on the HeLa cells.(2) AS1411could prevent the repair of the DNA damage of HeLa cells induced byradiation, suggesting that the enhancement of radiosensitization of AS1411on the HeLacells was correlated with its prevention on the repair of DNA damage. (3) The mechanism of AS1411enhancing the radiosensitization of HeLa cells wasuncorrelated with cell cycle.(4)AS1411could increase the rate of apoptosis of HeLa cells and could promoteapoptosis of HeLa cells induced by irradiation, and the mechanism of AS1411enhancing the radiosensitization of HeLa cells was correlated with cell apoptosis.