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Objective To investigate the possibility of chloroquine radiosensitization of esophageal cancer cell line TE-1 and its further mechanism.Methods Effect of chloroquine on cell viability of TE-1 cells was determined by MTT method.Expression of LC3,Beclin-1 and formation of acidic vesicular organelles (AVOs) were determined by Western blot,and fluorescence staining with Lyso-Tracker Red DND-99,respectively.Clonogenic survival of TE-1 cells was examined by clonogenic forming assay.Results Chloroquine showed dose-dependent inhibition of TE-1 cell growth,and its values of IC50 and IC10 were (72.33 ± 5.28) and (15.42 ± 3.33) μmol/L,respectively.The expression of Beclin-1 and LC3-Ⅱ/Ⅰ markedly increased in irradiated TE-1 cells.The addition of chloroquine with IC10concentration significantly reduced the fluorescence and intensity of AVOs accumulation in the cytoplasm of TE-1 cells.Clonogenic survival fraction decreased obviously,in TE-1 cells with addition of chloroquine after radiation and the value of SERD0 was 1.439.Conclusions Chloroquine could radiosensitize esophageal cancer cells by blocking autophagy-lysosomal pathway and be used as a potential radiosensitizing strategy.
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Objective To study the influence of survivin mutant-T34A ( survivinT34A) and survivin deletant-N-terminal 8 amino acids residues ( survivinN-8AA ) on the cell cycle distribution and chemosensitivity in human ovarian cancer HO-8910 cells for explorating the roles of modified survivin-mediated apoptosis induced by chemotherapeutic agents and possible signaling pathways involved. Methods pcDNA3.1 plasmid contained wild-type, survivinT34A and survivinN-8AA genes were transfected into HO-8910 cells,respectively, the control groups were HO-8910 cells transfected with pcDNA3. 1 plasmids. The expression of mRNA was examined by reverse transcription(RT) PCR and identified by DNA sequencing; the cell cycles were determined by flow cytometer analysis ( FCM ); the growth inhibitions rate of cisplatin ( DDP),paclitaxel (PTX) and LY294002 on the transfected cells were determined using methyl thiazolyl tetrazolium (MTT) assay. Results (1) The RT-PCR procedures and genome sequences showed that the survivin mRNA were expressed stable in the transfected HO-8910 cells. (2) There was lower percent of G0/G1 phase cells in SN-HO-8910 cells than that in PC-HO-8910 cells (44. 72% vs. 49.64%, P ＜0. 05) ;while higher percentage of G2/M phase and S phase cells( 1.06% and 54. 22% vs. 0. 56% and 49. 80%, P ＜ 0. 05 ).There was lower the G2/M phase and S phase cells in M-HO-8910 cells 0. 16% and 36. 33%, than that in PC-HO-8910 cells( P ＜ 0. 05 ); while higher percentage of G0/G1 phase cells(63. 51% ,P ＜ 0. 05 ). G0/G1 ,G2/M and S phase cells in Sur-HO-8910 cells were 54. 46%, 0. 62% and 44. 92%, and there were not significantly difference ( P ＞ 0. 05 ), compared to those in PC-HO-8910 cells. ( 3 ) The inhibitory concentration ( IC50 ) of DDP and PTX were higher in Sur-HO-8910 cells than those in control cells [(20. 4 ±6. 1)vs. (14.4 ±3.9)μmol/L,(36.7 ±4.0) vs. (28.6 ±3.6) μmol/L;all P＜0.05]. The IC50 of DDP and LY294002 in SN-HO-8910 cells were lower than those in control cells[(7. 6 ± 1.0) vs. ( 14. 4 ± 3.9)μmol/L, ( 13.2 ± 4. 0) vs. (41.0 ± 7. 9 ) μmol/L; all P ＜ 0. 01]. The IC50 of PTX [( 37. 9 ± 4. 8 ) μmol/L]in SN-HO-8910 cells were higher than that in control cells(P ＜0. 05). The IC50 of DDP in M-HO-8910 cells [(9.9 ± 1.2) μmol/L] were lower than that in control cells(P ＜0. 05) ,and the IC50 of LY294002 in M-HO-8910 cells [(66. 9 ± 4. 8) μ mol/L] higher than that in control cells ( P ＜ 0. 01 ). Conclusions The changes of cells cycle distribution caused by survivinT34A or survivinN-8AA enhanced the G2/M cell cycle-dependent chemosensitivity of PTX. Compared to survivinT34A, survivinN-8AA preferentially to mediate the cytotoxicity of DDP and LY294002, suggesting that it may be related to the cell cycle-dependence of survivin function and to blockage of the formation of its active dimer.
ABSTRACT
<p><b>BACKGROUND AND OBJECTIVE</b>Combined hypoxic cytotoxic drugs and chemoradiotherapy is an important mean of oncotherapy, and Tirapazamine (TPZ) is one of the most remarkable drugs. It has been shown that TPZ has a synergistic effect with radiotherapy on tumor cells, but whether TPZ would down-regulate the expression of the hypoxia-induced genes has not been reported. This study was to investigate the hypoxia-induced mRNA expressions of hypoxia inducible factor-1alpha (HIF-1alpha) and osteopontin (OPN) in human nasopharyngeal carcinoma HNE-1 and CNE-1 cells and the radiosensitization of TPZ, a hypoxia-specific drug, on HNE-1 and CNE-1 cells in vitro.</p><p><b>METHODS</b>The IC50 values of TPZ for HNE-1 and CNE-1 cells were measured using MTT assay, and the mRNA expressions of HIF-1alpha and OPN in HNE-1 and CNE-1 cells was determined using RT-PCR under aerobic and hypoxic conditions, respectively. The survival rates of HNE-1 and CNE-1 cells treated with or without TPZ at IC10 in the presence or absence of oxygen for 6 h were determined using colony formation assay following exposure to 1-6 Gy of 60Co radiation. The dose-survival curves were plotted and the values of D0, Dq and SER were calculated as a single-hit multitarget model.</p><p><b>RESULTS</b>The IC50 values of TPZ were 34.81 μmol/L and 35.02 μmol/L in HNE-1 and CNE-1 cells under aerobic condition, and 30.20 μmol/L and 28.48 μmol/L under hypoxic condition, respectively. The expressions of HIF-1alpha and OPN mRNA were reduced by TPZ in HNE-1 cells, but not in CNE-1 cells under hypoxic condition. For the HNE-1 cells, the respective values of D0 and Dq were 0.89 Gy and 0.28 Gy following normoxic irradiation versus 1.47 Gy and 0.44 Gy following hypoxic irradiation. For the CNE-1 cells, the respective values of D0 and Dq were 0.72 Gy and 0.68 Gy following normoxic irradiation versus 0.95 Gy and 0.56 Gy following hypoxic irradiation. The values of D0 and Dq for HNE-1 and CNE-1 cells treated with TPZ under hypoxic condition following irradiation were 0.66 Gy, 0.21 Gy and 0.85 Gy, 0.79 Gy, respectively.</p><p><b>CONCLUSION</b>TPZ can down-regulate hypoxia-induced expression of HIF-1alpha and OPN mRNA of HNE-1 cells and radiosensitize the HNE-1 cells but not CNE-1 cells, and act as a hypoxia modifier.</p>