Study Of The Impact Of Biological Behaviors In Human Renal Cell Carcinoma Cells By HSP90 Inhibitor 17-AAG In Vitro

Objective To observe the inhibition and radiosensitizing effects of 17-AAG as a HSP90 inhibitor on Human renal cell carcinoma Caki-1 cell line,The possible mechanisms of those effects were investigated in this study.Methods (1) Human renal cell carcinoma Caki-1 cell line was cultured in vitro. (2) MTT colorimetric assay was used to determine the proliferation rate of Caki-1 cells in hypoxic condition, when Caki-1 cells were cultured in medium containing the Hsp90 inhibitor 17-AAG in different concentrations and time. (3) Human renal cell carcinoma cell line Caki-1 cells were cultured with or without 80nmol/L 17-AAG under normoxic and hypoxic conditions (Experimental group),respectively. Negative control group and blank control group were set up at the same time. MTT colorimetric assay was used to determine OD570 of Caki-1 cells; The changes of cell morphology were observed by inverted microscope;Apoptosis was detected by flow cytometry;Western blot were used to detect the expression of HIF-2αprotein. (4) After the treatment of 10nmol/L 17-AAG on Caki-1 cells in hypoxic condition, using different doses of 6MV-X-ray irradiation, cell survival curve were drawn by Experimental application of colony-forming.Results (1) The HSP90 inhibitor 17-AAG significantly inhibited the proliferation of Caki-1, and may produce a concentration-dependent and time-dependent inhibition of Caki-1 cell growth. (2) In the normoxic state, there was no significant difference among the OD570 of these three groups of Caki-1 cells (P>0.05). After 48 hours, OD570 of the experimental group significantly lower than the negative control group and blank control group at different time points in hypoxic conditions,, the difference was statistically significant (P <0.05). (3) In the normoxic state, the three groups were low apoptosis rate by flow cytometry, however, there were no significant differences among them (P> 0.05). In hypoxic conditions, the apoptosis rate in experimental group was higher than Negative control group and blank control group (P <0.05). (4) In normoxic and hypoxic conditions, Experimental group cells HIF-2αprotein expression was inhibited, which is lower than the negative control group and blank control group (P <0.05). Compared with normoxic state, the expression of HIF-2αprotein in the Negative and blank control group was significantly increased in hypoxic conditions (P <0.05). however, the expression of HIF-2αprotein in the Experimental group was no significant difference between in hypoxic conditions and normoxic state (P>0.05). (5) The results of colony formation and relevant parameters of survival curves showed that the radiosensitivity index D₀, SF₂, Dq all declined. D0 sensitizer ratio was 1.3169.Conclusion In hypoxic conditions, The HSP90 inhibitor 17-AAG exerts a significant growth inhibition on human renal cancer cell line Caki-1 and promote its apoptosis .It was likely due to the inhibition of HIF-2αexpression. 17-AAG could enhance radiosensitivity of human renal cancer cell line Caki-1 in hypoxic condition.