The Effect Of Quercetin And17-DMAG On Radiosensitization Of Hypoxic Cancer Cells

Objective：To explore the effect of quercetin and17-DMAG which were usedsolely and together on Radiosensitization of human uterine cervix cancer cell line(HeLa)in chemical hypoxia induced by CoCl2, and reseach of the possible mechanism. Cellswith different conceration of quercetin and17-DMAG which were used solely andtogether,the expression of HIF-1αand HSP70protein was detected by Western-Blotting;The effects of quercetin and17-DMAG which were used solely and together combinedwith radiation on cell survival rate, cell apoptosis, and DNA damage was determined.Methods: HeLa cells were cultured in differect concentrations of quercetin and17-DMAG in vitro.The inhibitory ratio of the cells were measured by MTT assay.HeLa cells were seeded in the medium containing200μmol/L CoCl2. The expressionof HIF-1α and HSP70of HeLa cells under hypoxia after exposure to quercetin and17-DMAG combined with radiation was detected by Western-Blotting. Colon formingassay is carried out to study the cells survival rate of HeLa cells under hypoxia afterexposure to quercetin and17-DMAG combined with radiation; Apoptosis and DNAdamage of hypoxic HeLa cells after exposure to quercetin and17-DMAG combinedwith radiation was observed by confocal microscope.Results：(1) Quercetin and17-DMAG could inhibit the growth of the HeLa cells in vitrosignificantly.The suppression was both in the dose-dependent and time-dependent.Quercetin and17-DMAG definitly enhanced radiosensitivity of the HeLa cells.(2) The results of the survival rate of cells after radiation which was detected byColon forming assay showed that: The survival rate of hypoxia group more than normal controls. Exposure to60~120μmol/L concentration of quercetin significantly reducedthe survival rate of HeLa cells under normoxia and hypoxia, and there was aconcentration-dependent decrease in the survival rate of cells; The survival rate of all17-DMAG dose points in hypoxic environment was lower than the hypoxiagroup(P<0.05), and there was a concentration-dependent decrease in the survival rate ofcells; Exposure to quercetin and17-DMAG which were used solely and together innormoxic and hypoxic environment, the survival rate was lower than the group with thesame dosage of medication.(3) The effects of different concentrations quercetin and17-DMAG on expressionof HIF-1αand HSP70protein: Exposure to different concentrations of quercetinsignificantly reduced the expression of HSP70of HeLa cells under normoxia andhypoxia, and there was a concentration-dependent decrease in the levels ofHSP70;17-DMAG significantly reduced the expression of HIF-1α of HeLa cells undernormoxia and hypoxia, and there was a concentration-dependent decrease in the levelsof HIF-1α;The expression levels of HSP70was enhanced,and was dependent on theconcentration17-DMAG; Exposure to quercetin and17-DMAG significantly reducedthe expression of HSP70and HIF-1α of HeLa cells under hypoxia, The expressionlevel are lower than the group with the same dosage of medication.(4) The effect of different concentrations quercetin and17-DMAG on apoptosis:Early apoptosis rate of the normal control group, slightly higher than the group ofhypoxia, but the effect of quercetin and17-DMAG combined with irradiation underhypoxia show that irradiation group of early and late apoptosis rate was significantlyhigher than that of hypoxia group, hypoxia drug group used by itself compare withhypoxia group show that the enhanced of apoptosis rate was in the drug anddose-dependent. Exposure to quercetin and17-DMAG which were used together innormoxic and hypoxic environment, early and late apoptosis rate was significantlyhigher than than the group with the same dosage of medication.(5) The effect of different concentrations quercetin and17-DMAG on DNAdamage:When irradiation dose was0Gy, there was no significance in the difference in the control group and hypoxia drug group. When irradiation dose was0Gy or4Gy,fociin cells of the control group significantly more than the group of hypoxia, foci in cellsof the hypoxia drug combing group significantly more than the group with the samedosage of medication.Conclusions:(1) Quercetin and17-DMAG could inhibit the growth of the HeLa cells.(2) In concentration of60~120μmol/L range, quercetin could increase theradiation sensitivity of normoxic and hypoxic cells;17-DMAG could increase theradiation sensitivity of normoxic and hypoxic cells; Quercetin and17-DMAG whichwere used together could increase the radiation sensitivity of normoxic and hypoxiccells.(3) Quercetin inhibits expression of HSP70in normoxic and hypoxicenvironment;17-DMAG inhibits expression of HIF1-α in hypoxic environment; theinhibition of HSP90led to HSP70overexpression of HeLa cells in the hypoxicenvironment.; quercetin and17-DMAG which were used together inhibit expression ofHSP70and HIF1-α.(4) Quercetin and17-DMAG which were used solely and together could increaseapoptosis rate that induced by the radiation in normoxic and hypoxic cells, and theenhancement was in the drug concentration-dependent(5) Quercetin and17-DMAG which were used solely and together could preventrepair of DNA damage that induced by the radiation in normoxic and hypoxic cells.