Effect Of Radiosensitibity Enhancement Of SAHA On Cervical Cancer Cell

ObjectiveTo investigate the effect of minimally cytotoxic concentrations of the HDAC inhibitor suberoylanilide ydroxamic acid (SAHA) on the radiosensitivity of cervical cancer Siha cells.Methods1. MTT assay was used to measure the proliferation inhibition of the histone deacetylase inhibitor (SAHA) in different concentrations (0.5 umoL/L,1 umoL/L,2 umoL/L,4 umoL/L,6 umoL/L,8 umoL/L) and durations (24h) and then calculate IC50.2. Siha cells were incubated with SAHA at the concentration of 20% IC50 for 24h and then were exposed to X-ray (0,2,4,6,8Gy), Colonies and surviving fraction (SF) were detected by clonogenic assay,the D0,Dq,sensitizing enhancement ratio(SER) and the cell survival curve were gained by single-hit multi-target model.3. Siha cells were incubated with SAHA at the concentration of 20% IC50 for 24h and then were exposed to X-ray (4Gy),RT-PCR and Western Blot were used to detect the expression of Bax and Ku70 of control group,SAHA group,X-ray group and SAHA+X-ray group to find the pathway of sensitization enhancement of SAHA on Siha cells.Results1. SAHA inhibited the proliferation of Siha cells significantly with dose dependent,the IC50 of SAHA for 24h was 4.80μmol/L.2. SAHA at the concentration of 20% IC50 had less toxic but sensitization on Siha cells,cell survival fraction of SAHA+X-ray group was lower than X-ray group.the D0 of X-ray group and SAHA+X-ray group were 2.329 and 1.213,the Dq were 1.721 and 0.823 respectively, and SFR was 1.92. The cell survival curve of SAHA+X-ray group was to the left compared with X-ray group and the privious one was relatively flat and the shoulder area was not obvious.3. Compare the expression of Bax mRNA:There was no statistical signi- ficance between SAHA group and control group (P>0.05);there was statistical significance between SAHA group and control group(P<0.05), the expression of X-ray group was higher than control group; there was statistical significance between SAHA+X-ray group and the other groups (P<0.05),the expression of SAHA+X-ray group was higher than the other groups.4. Compare the expression of Ku70 mRNA:There was statistical signi- ficance between SAHA group and control group(P<0.05), the expression of SAHA group was lower than control group; There was statistical signi- ficance between X-ray group and control group(P<0.05), the expression of X-ray group was higher than control group; there was statistical significance between SAHA+X-ray group and X-ray group (P<0.05),the expression of SAHA+X-ray group was lower than X-ray group.Conclusions1. The histone deacetylase inhibitor SAHA inhibited the growth of cervical cancer Siha cells at dose dependent.2. Minimally cytotoxic concentrations of SAHA enhanced the radiosensi- tivity of Siha cells.3. Both of up-regulating the expression of Bax response to radiotherapy and down-regulating the expression of Ku70 response to repairing of DNA damage might play an imporment role in the sensitization enhancement of SAHA on Siha cells.