The Protective Effects Of Heat Shock Protein 70 On Ionizing Radiation-induced Cell Injury Of V79

Objective: To study the expression of heat shock protein 70 in V79 cells after heat shock pretreatment and their protective effects on radiation-induced cell injury, and their influence on cell cycle progression.Methods: (1) Western blot was used to detect the expression of heat shock protein 70 in V79 cells after heat shock pretreatment.(2) V79 cells were irradiated using 60Coγ-ray after heat shock pretreatment, survival rate was observed using colony formation assay.(3) Flow cytometry was used to perform cell cycle analysis to decide the influence of heat shock pretreatment on radiation-induced cycle arrest.Results: 1) Overexpression of heat shock protein 70 was observed in V79 cells as early as recovering for 1 hour after heat shock pretreatment, with peak expression in cells recovering for 4-10 hours, and could last for 24 hours. HSP70 was unable to be observed in control cells without heat shock pretreatment.2) Compared to cells without heat shock pretreatment, no obvious difference was observed in survival rate of cells recovering for 4 hours and 10 hours after heat shock pretreatment when irradiation dose was 0Gy, 6Gy and 8Gy; when irradiation dose was 2Gy and 4Gy, there was obvious increase in survival rate of cells recovering for 10 hours after heat shock pretreatment, and no obvious difference in survival rate of cells recovering for 4 hours after heat shock pretreatment.3) Percentage of G2/M phase of cells increased after irradiation ofγ-ray. Compared to cells without heat shock pretreatment before irradiation, there was no obvious difference in the percentage of G2/M phase of cells with heat shock pretreatment before irradiation.Conclusion: 1) Overexpression of heat shock protein 70 was observed in cells as early as recovering for 1 hour after heat shock pretreatment, with peak expression in cells recovering for 4-10 hours, and could last for 24 hours.2) Heat shock pretreatment was able to elevate survival rate of V79 cells after irradiation ofγ-ray when irradiation dose was less than 6Gy (enough recovering time after heat shock pretreatment was required) which indicated that overexpression of HSP70 induced by heat shock pretreatment has protective effects on radiation-induced cell injury of V79.3) Cell cycle analysis showed that heat shock pretreatment, in association with irradiation, failed to induce any significant change in comparison to radiation-only cells.