The Effect Of Hyperbaric Oxygen On Radiosensitivity Of Glioma U251 Cells And Its Mechanism

1 The Effect of hyperbaric oxygen on radiosensitivity of human glioma U251 cells at cell levelObjectives:To observe the effect of hyperoxia combined with X-ray and hyperbaric oxygen(HBO)combined with X-ray on the morphology and proliferation activity of glioma U251 cells,and then investigate the value of HBO in regulating the radiosensitivity of glioma U251 cells.Methods:(1)Glioma U251 cells were randomly divided into control group(normal pressure and normoxia),X-ray(2Gy)group,hyperoxia combined with X-ray(2Gy)group and HBO combined with X-ray(2Gy)group.The cell adhesion,cell status and cell count in different experimental groups were observed at 24 h,48 h and 72 h after Glioma U251 cells were correspondingly treated.(2)MTT assay was used to detect the effects of hyperoxia and HBO combined with X-ray(0,2,4,6,8Gy)on the proliferation activity of glioma U251 cells.Results:(1)Total cell numbers of glioma U251 cells cultured for 24 h,48 h and 72 h in HBOcombinedwithX-raygroup[(1.09±0.1222)×10~5,(0.33±0.036)×10~5,(0.33±0.036)×10~5]were significantly lower than that in X-ray irradiation group[(1.81±0.0550)×10~5,(0.85±0.0907)×10~5,(0.44±0.0472)×10~5]and hyperoxia combined with X-ray group[(1.28±0.0754)×10~5,(0.64±0.0624)×10~5,(0.38±0.0351)×10~5](P<0.05).(2)With the increase of X-ray dose(from 2Gy to 8Gy),the proliferation inhibition rate of glioma U251 cells increased successively,that was[(0.1159±0.008)times,(0.1650±0.009)times,(0.2196±0.00909)times and(0.2625±0.009)times],respectively.The proliferation inhibition rate of Glioma U251 cells in hyperoxia combined with X-ray group and HBO combined with X-ray group were significantly higher than that in the corresponding dose X-ray irradiation group(P<0.05),and the proliferation inhibition rate in HBO combined with X-ray group was also significantly higher than that of hyperoxia combined with X-ray group(P<0.05).The proliferation inhibition rate in hyperoxia group and HBO group was(0.0184±0.0004)times and(0.0193±0.0009)times,respectively.There was no significant difference between two groups(P>0.05).Conclusion:Hyperbaric oxygen makes glioma U251 cells in an oxygen-rich state,which enhances the radiation damage effect of X-ray,and thus plays the role of radiosensitization.2 The effect of hyperbaric oxygen on human glioma U251 cells at gene levelObjective:To investigate the molecular mechanism of hyperbaric oxygen(HBO)in improving radiosensitivity of glioma U251 cells,through Observeing the effects of HBO combined with X-ray(2Gy)on the relative expression of HIF-1αmRNA,VEGF mRNA and Akt1 mRNA in glioma U251 cells.Methods:Glioma U251 cells were divided into group A(2Gy),group B (HBO+2Gy),group C(hyperoxia+2Gy),group D(HBO),group E(hyperoxia)and group F(normal pressure and normoxia).After each experimental group was treated separately,The relative expression of HIF-1αmRNA,VEGF mRNA and Akt1 mRNA was detected through RT-PCR.Results:The expression of HIF-1αmRNA,VEGF mRNA and Akt1 mRNA in each experimental group were found.Gene expression in each experimental group was lower than that in group F,but the most significant decrease in gene expression was observed in Group B,The expression of HIF-1αmRNA,VEGF mRNA and Akt1mRNA was(0.19±0.0117)times,(0.53±0.0319)times and(0.20±0.0117)times,respectively.(1)HIF-1αmRNA expression in Group B[(0.19±0.0117)times]was significantly lower than that in group C[(0.22±0.0378)times](P=0.031,P<0.05);HIF-1αmRNA expression in Group A[(0.30±0.0095)times]was significantly higher than that in Group B and Group C(P<0.01,P<0.01);HIF-1αmRNA expression in Group D[(0.48±0.0207)times]and Group E[(0.53±0.0105)times]were significantly lower than that in Group F(P<0.01,P<0.01).(2)VEGF mRNA expression in group B[(0.53±0.0319)times]and group C[0.55±0.0909)times]was significantly lower than that in group A[(0.71±0.0756)times](P<0.01,P<0.01);VEGF mRNA expression in group D and group E was[(0.91±0.3189)times]and[(0.92±0.0435)times],respectively.There was no significant difference between two groups(P=0.762,P>0.05).(3)Akt1 mRNA expression in group B[(0.20±0.0117)times]and group C[(0.47±0.0474)times]was significantly lower than that in group A[(0.64±0.0323)times](P<0.01,P<0.01);There was no significant difference in Akt1 mRNA expression between group D[(0.33±0.0651)times]and group E[(0.35±0.0283)times](P=0.269,P>0.05).Conclusion:Hyperbaric oxygen improve the radiosensitivity of glioma U251cells through HIF-1α/VEGF/Akt 1 signaling pathway.