γ射线增强喉癌细胞hTERTp启动子活性研究

目的 探讨γ射线对喉癌细胞中端粒酶逆转录酶基因启动子(hTERTp)活性的影响,以及通过射线增强hTERTp下游基因表达的可行性。方法 将含hTERTp的质粒转染细胞,采用报告基因评价启动子活性,通过RT-PCR和酶活性检测观察射线作用下hTERTp调控辣根过氧化物酶(HRP)的表达,克隆形成实验评价射线对phTERTp-HRP/IAA杀伤和放射增敏作用的影响。结果 在Hep-2细胞中,6 Gyγ射线照射后hTERTp活性是0 Gy照射后的2.96倍,在Hep-2R细胞中是1.60倍。质粒phTERTp-HRP转染Hep-2和Hep-2R细胞后,6 Gy照射组的HRP mRNA分别增高2.1和1.1倍,酶活性分别增高2.54和1.23倍。6 Gy联合吲哚乙酸(IAA)组Hep-2细胞的存活分数为1.3%,Hep-2R细胞的存活分数为3.5%,比对照组明显降低(F=234.280和F=357.148,P值均<0.01)。6Gy联合IAA组与IAA组相比,放射增敏比SER_<sub>SF2分别为1.52(Hep-2)和1.68(Hep-2R),存活曲线的参数α分别为0.416、0.099(Hep-2)和0.356、0.090(Hep-2R)。结论 γ射线可以增强不同放射敏感性喉癌细胞hTERTp活性,增强下游基因表达。射线联合phTERTp-HRP/IAA对喉癌细胞具有更加明显的杀伤和放射增敏作用。     

Radiosensitization efficacy of KU-2285, RP-170 and etanidazole at low radiation doses: assessment by in vitro cytokinesis-block micronucleus assay.

Since the cytokinesis-block micronucleus assay is very sensitive at low radiation doses, we used it to investigate the in vitro sensitizing effects of two new hypoxic cell sensitizers (KU-2285, a fluorinated 2-nitroimidazole and RP-170, a 2-nitroimidazole nucleoside analogue) at 1-3 Gy in comparison with etanidazole. Exponentially growing EMT6 cells were treated with the drugs under aerobic or hypoxic conditions for 40 min prior to and during irradiation, after which the drugs were removed and cytochalasin B (2 micrograms/ml) was added to the medium. The number of micronuclei in binucleate cells was counted after 42 h of culture. Under aerobic conditions the three compounds at 5 mM had no sensitizing effect. Under hypoxic conditions the sensitizer enhancement ratio (SER) at 5 mM was 3.8 for KU-2285, 3.2 for RP-170, and 2.3 for etanidazole, while the oxygen enhancement ratio was 2.9. When the cells were pretreated under hypoxic conditions with drugs at 5 mM but then irradiated under aerobic conditions, KU-2285 and RP-170 had a sensitizing effect whereas etanidazole did not. The sensitizers were also tested at 0.5 and 1 mM, and the SER values were compared with those obtained at high doses (15-30 Gy) using a colony assay. The SER at low doses was higher than that at high doses for 1 and 5 mM KU-2285 and 5 mM RP-170, while the SERs were similar for all concentrations of etanidazole and the lower concentrations of KU-2285 and RP-170. These results might suggest the potential usefulness of KU-2285 and RP-170 in clinical radiotherapy.     

Preferential radiosensitization in p53-mutated human tumour cell lines by pentoxifylline-mediated disruption of the G2/M checkpoint control

PURPOSE: There is evidence that the duration of the G2/M delay following irradiation is correlated with cell survival. We studied the radiosensitizing potential of pentoxifylline (PTX) and the PTX-mediated modulation of cell-cycle progression dependent on the p53 status of various human tumour cell lines. MATERIALS AND METHODS: The cellular radiosensitivity of human MCF-7 (wild-type p53) and HT-29 (p53-defective) tumour cells, which were exposed to PTX (2 mM) immediately after gamma-irradiation was determined by colony forming assay. The influence on cell cycle progression after irradiation (6 Gy) was assessed by flow cytometric analysis using p53 wild-type MCF-7 and HPR600 cells, and p53-defective HT-29 and WiDr cells. RESULTS: Clonogenic survival assays up to 8 Gy demonstrated that p53-defective HT-29 cells (sensitizer enhancement ratio [SER]=1.54) were sensitized by PTX (2 mM) to a significantly higher degree than p53 wild-type MCF-7 (SER=1.14) cells. Exposure of irradiated (6 Gy) cells to PTX (2 mM) resulted in abrogation of the radiation-induced G2/M arrest in the p53-defective HT-29 and WiDr cells, whereas the p53 wild-type-expressing MCF-7 and HPR600 cells showed less significant impairment of the G2/M checkpoint. In HT-29 cells, the rate of transition into mitosis was even higher than in the sham-treated control cells. G2/M abrogation was accompanied by an increase of apoptosis only in HPR600 cells. CONCLUSIONS: Since PTX was less effective in cells expressing intact p53, the application of PTX suggests a promising strategy of pharmacological disruption of the G2/M checkpoint control by which preferentially radiation-resistant tumours with defective p53 function might be rendered more sensitive to ionizing radiation.     

Preferential radiosensitization in p53-mutated human tumour cell lines by pentoxifylline-mediated disruption of the G2/M checkpoint control

Purpose : There is evidence that the duration of the G2/M delay following irradiation is correlated with cell survival. We studied the radiosensitizing potential of pentoxifylline (PTX) and the PTX-mediated modulation of cell-cycle progression dependent on the p53 status of various human tumour cell lines. Materials and methods : The cellular radiosensitivity of human MCF-7 (wild-type p53) and HT-29 (p53-defective) tumour cells, which were exposed to PTX (2 mM) immediately after γ-irradiation was determined by colony forming assay. The influence on cell cycle progression after irradiation (6 Gy) was assessed by flow cytometric analysis using p53 wild-type MCF-7 and HPR600 cells, and p53-defective HT-29 and WiDr cells. Results : Clonogenic survival assays up to 8 Gy demonstrated that p53-defective HT-29 cells (sensitizer enhancement ratio [SER]=1.54) were sensitized by PTX (2 mM) to a significantly higher degree than p53 wild-type MCF-7 (SER=1.14) cells. Exposure of irradiated (6 Gy) cells to PTX (2 mM) resulted in abrogation of the radiation-induced G2/M arrest in the p53-defective HT-29 and WiDr cells, whereas the p53 wild-type-expressing MCF-7 and HPR600 cells showed less significant impairment of the G2/M checkpoint. In HT-29 cells, the rate of transition into mitosis was even higher than in the sham-treated control cells. G2/M abrogation was accompanied by an increase of apoptosis only in HPR600 cells. Conclusions : Since PTX was less effective in cells expressing intact p53, the application of PTX suggests a promising strategy of pharmacological disruption of the G2/M checkpoint control by which preferentially radiation-resistant tumours with defective p53 function might be rendered more sensitive to ionizing radiation.     

Comparison of the combined action of oxaliplatin or cisplatin and radiation in cervical and lung cancer cells

BACKGROUND AND PURPOSE: To test the combined effects of oxaliplatin and radiation versus cisplatin and radiation using human cervical and lung cancer cell lines. MATERIAL AND METHODS: CaSki cervical cancer cells, and A549 lung cancer cells were cultured under standard conditions. Cells were treated with escalating doses of gamma-irradiation (0-6 Gy), and with oxali- and cisplatin for 2 h or 24 h, or a combination of both. Cell survival was measured by a colony-forming assay. Survival curves were fitted to the data using the linear quadratic model. Sensitizer enhancement ratios (SER) were calculated at the 37% survival level, and isobologram analysis was applied to test for the drug-radiation interactions. RESULTS: Oxaliplatin as well as cisplatin alone were cytotoxic in both cell lines. In CaSki cells, oxaliplatin and cisplatin significantly increased radiation toxicity. In A549 cells no increase of radiation toxicity was observed after treatment with cisplatin, however, isobologram analysis revealed supra-additive interaction between oxaliplatin and radiation in A549 cells. CONCLUSION: Oxaliplatin had the same effectiveness on tumor cells as cisplatin and induced enhanced radiation toxicity in lung cancer cells, where cisplatin was not able to achieve radiosensitization.     

DNA strand breakage by bivalent metal ions and ionizing radiation

PURPOSE: To investigate mechanisms of DNA breakage via the interaction of bivalent metal ion, thiol reducing agent and ionizing radiation, in *OH scavenging abilities comparable to those in cells. MATERIALS AND METHODS: We measured the effects of 10 min exposure to 200 microM Fe2+ vs. Fe3+ on the induction of single (SSB) and double (DSB) strand breaks in unirradiated and oxically irradiated SV40 DNA, in aqueous solution containing 75 or 750 mM glycerol and/or 5 mM glutathione (GSH). RESULTS: Fe2+ or GSH alone produced little DNA damage. However, their combination produced a dramatic increase in the production of both SSB and DSB. Experiments with ferric ion suggest that it produces DNA damage only after partial reduction to ferrous by GSH. Induction efficiencies for SSB in the presence of Fe2+/GSH showed additivity of the effects of radiation alone with those from Fe2+/GSH. However, the corresponding induction efficiencies for DSB demonstrated a 2.5-fold enhancement. CONCLUSIONS: Our results are consistent with a model in which reduced bivalent metal ions plus thiols, in the presence of O2, produce DSB in DNA primarily via local clusters of hydroxyl radicals arising from site specific Fenton reactions. The synergism observed between DSB production by Fe/GSH and by ionizing radiation, also believed to occur via local clusters of hydroxyl radicals, is consistent with this model. Our results suggest that both normally present intracellular iron and ionizing radiation may be important sources of oxidative stress in cells.     

Photoreactivation of Ionizing-radiation-induced Damage in E. Coli

Since the cytokinesis-block micronucleus assay is very sensitive at low radiation doses, we used it to investigate the in vitro sensitizing effects of two new hypoxic cell sensitizers (KU-2285, a fluorinated 2-nitroimidazole and RP-170, a 2-nitroimidazole nucleoside analogue) at 1–3 Gy in comparison with etanidazole. Exponentially growing EMT6 cells were treated with the drugs under aerobic or hypoxic conditions for 40 min prior to and during irradiation, after which the drugs were removed and cytochalasin B (2 µg/ml) was added to the medium. The number of micronuclei in binucleate cells was counted after 42 h of culture. Under aerobic conditions the three compounds at 5 mm had no sensitizing effect. Under hypoxic conditions the sensitizer enhancement ratio (SER) at 5 mm was 3·8 for KU-2285, 3·2 for RP-170, and 2·3 for etanidazole, while the oxygen enhancement ratio was 2·9. When the cells were pretreated under hypoxic conditions with drugs at 5 mm but then irradiated under aerobic conditions, KU-2285 and RP-170 had a sensitizing effect whereas etanidazole did not. The sensitizers were also tested at 0·5 and 1 mm, and the SER values were compared with those obtained at high doses (15–30 Gy) using a colony assay. The SER at low doses was higher than that at high doses for 1 and 5 mm KU-2285 and 5 mm RP-170, while the SERs were similar for all concentrations of etanidazole and the lower concentrations of KU-2285 and RP-170. These results might suggest the potential usefulness of KU-2285 and RP-170 in clinical radiotherapy.     

辐射增强启动子调控的p53基因联合照射对肿瘤细胞的作用

目的 研究辐射增强启动子调控的野生型-p53抑癌基因系统联合照射对人肿瘤细胞系HeLa和A549细胞的特异性杀伤作用。方法 构建辐射增强启动子pE6（TATA）-p53,Western blot检测不同射线剂量诱导下人肺腺癌A549细胞系和人宫颈癌HeLa细胞系中P53蛋白的表达水平,筛选出最适的照射剂量;AnnexinV-FITC试剂盒检测肿瘤细胞系早期凋亡率;利用克隆形成实验检测此系统对肿瘤细胞放射敏感性的影响。结果 在HeLa和A549细胞中,P53蛋白表达均受放射线诱导增高,且在6 Gy时辐射诱导活性最高;实验组质粒的细胞早期凋亡率与转染对照组质粒的细胞早期凋亡率相比有明显提高（F=11.018、10.736,P<0.05）。HeLa细胞和A549细胞的放射增敏比（SER）分别为2.56和2.36。结论 辐射增强启动子调控的p53基因系统具有显著的诱导肿瘤细胞凋亡的作用,可以提高肿瘤细胞的辐射敏感性,对肿瘤的治疗提供了新思路。     

Indomethacin lowers the threshold thermal exposure for hyperthermic radiosensitization and heat-shock inhibition of ionizing radiation-induced activation of NF-kappaB

PURPOSE: It is well established that salicylate and several other non-steroidal anti-inflammatory agents (NSAID), including indomethacin, can activate the heat-shock response, albeit at high concentrations. This is significant since heat shock significantly alters the cellular cytotoxic response to ionizing radiation (IR). It was previously shown that heat shock, as well as NSAIDs, inhibits IR-induced activation of NF-kappaB and that NF-kappaB protects against IR-induced cytotoxicity. Hence, it is hypothesized that pretreatment with indomethacin before heating will lower the temperature and heating times required to inhibit the activation of NF-kappaB and induce significant hyperthermic radiosensitization. MATERIALS AND METHODS: Experiments were performed in HeLa cell lines and the DNA-binding activity was determined by EMSA. Cellular radiosensitivity was determined by clonogenic assay. RESULTS: HeLa cells pretreated with indomethacin showed a decrease in the temperature-time combination necessary to inhibit IR-induction of NF-kappaB DNA binding. In addition, clonogenic cell survival assays using identical conditions showed an indomethacin dose-dependent enhancement of hyperthermic radiosensitization. Thus, similar concentrations of indomethacin both lowered the threshold thermal exposure to inhibit activation of NF-kappaB DNA-binding and increased the sensitivity of tumour cells to hyperthermic radiosensitization-induced cytotoxicity. In HeLa cells treated with N-alpha-tosylphenylalanyl-chloromethyl ketone (TPCK), a serine protease inhibitor that blocks activation of NF-kappaB, an increase in radiosensitivity was observed. Interestingly, no additional cell killing was observed when heat shock was added to cells treated with TPCK before IR, suggesting a possible common cytotoxic pathway. CONCLUSIONS: The results demonstrate that indomethacin lowers the temperature-time conbination necessary to induce several physiological processes associated with the heat-shock response. Furthermore, NSAID may be potential adjuvants in improving the clinical effectiveness of hyperthermia in radiation therapy.     

DNA strand breakage by bivalent metal ions and ionizing radiation

Purpose: To investigate mechanisms of DNA breakage via the interaction of bivalent metal ion, thiol reducing agent and ionizing radiation, in ?OH scavenging abilities comparable to those in cells.

Materials and methods: We measured the effects of 10 min exposure to 200 μM Fe²⁺ vs. Fe³⁺ on the induction of single (SSB) and double (DSB) strand breaks in unirradiated and oxically irradiated SV40 DNA, in aqueous solution containing 75 or 750 mM glycerol and/or 5 mM glutathione (GSH).

Results: Fe²⁺ or GSH alone produced little DNA damage. However, their combination produced a dramatic increase in the production of both SSB and DSB. Experiments with ferric ion suggest that it produces DNA damage only after partial reduction to ferrous by GSH. Induction efficiencies for SSB in the presence of Fe²⁺/GSH showed additivity of the effects of radiation alone with those from Fe²⁺/GSH. However, the corresponding induction efficiencies for DSB demonstrated a 2.5-fold enhancement.

Conclusions: Our results are consistent with a model in which reduced bivalent metal ions plus thiols, in the presence of O₂, produce DSB in DNA primarily via local clusters of hydroxyl radicals arising from site specific Fenton reactions. The synergism observed between DSB production by Fe/GSH and by ionizing radiation, also believed to occur via local clusters of hydroxyl radicals, is consistent with this model. Our results suggest that both normally present intracellular iron and ionizing radiation may be important sources of oxidative stress in cells.     

Sustained enhancement of liposome-mediated gene delivery and gene expression in human breast tumour cells by ionizing radiation

PURPOSE: To investigate whether irradiation improves the delivery and expression of liposome-DNA complexes in human breast tumour cells. MATERIALS AND METHODS. MDA-MB231 and MCF-7 human breast tumour cells were transfected with a liposomal SV40-luciferase complex and irradiated immediately after, at 24h after or 24h prior to transfection and in the presence or absence of serum. The amount of luciferase plasmid in the cell was evaluated after extraction by the Hirt procedure, while luciferase expression was measured using a luminescence assay. RESULTS: Ionizing radiation enhanced the liposome-mediated delivery and expression of the SV40-luciferase transgene in MDA-MB231 breast tumour cells both in the absence and presence of serum as well as in MCF-7 breast tumour cells. Improved transgene delivery and expression was observed at a clinically relevant dose of 2 Gy, and was dose-dependent over a dose range of 2-10 Gy. The effects of irradiation on transgene expression were observed with irradiation immediately prior to exposure of the cells to the liposome-transgene complex, with irradiation up to 24 h before or up to 24 h after initiation of exposure. CONCLUSIONS: Irradiation at 24 h prior to exposure of breast tumour cells to the liposome-transgene complex appears to be the optimal approach for enhancing transgene delivery and expression. These findings suggest that ionizing radiation could promote the utility of gene therapy in the treatment of breast cancer.     

The role of iron oxide nanoparticles in the radiosensitization of human prostate carcinoma cell line DU145 at megavoltage radiation energies

Abstract

Purpose: To examine the radiosensitizing effects of iron oxide nanoparticles in the presence of 6 MV (megavoltage) X-ray radiation.

Materials and methods: Iron oxide nanoparticles with two different modifications – dextran coating (plain) and amino-group dextran coating – were used. The rate of iron oxide penetration was monitored using Prussian blue staining, magnetic resonance imaging and atomic adsorption spectroscopy. The effect of iron oxide on the viability of cells was determined using trypan blue dye exclusion assay followed by evaluating the cytotoxicity effect of amino-group iron oxide nanoparticles and ionizing radiation. Radiation dose enhancement studies were carried out on DU145 human prostate carcinoma cell line with 1 mg/ml amino-group iron oxide nanoparticles and different doses of 6 MV X-ray radiation.

Results: The uptake of amino-group coated nanoparticles by DU145 cells was significantly more than the plain nanoparticles. In addition, cell viability was decreased with the increase of iron oxide concentration. The dose enhancement factor (DEF) is approximately 1.2 at different doses in the range of 2–8 Gy of 6 MV X-ray radiation.

Conclusions: It was demonstrated that iron oxide nanoparticles with the appropriate surface modifications can enter the DU145 cells and it can be used as a cell sensitizer to megavoltage ionizing radiations in radiation therapy.     

腺病毒介导的人视网膜母细胞瘤94基因对人食管癌细胞辐射增敏作用的研究

目的 探讨重组腺病毒人视网膜母细胞瘤94基因(Ad-Rb94)对γ射线杀伤人食管癌 EC109细胞的增敏作用。方法 将Ad-Rb94体外转染后的EC109细胞,按数字随机表法,分为空白对照组、Ad-LacZ对照组、Ad-Rb94组、照射组和Ad-Rb94联合照射组,观察EC109的细胞的抑制率、细胞周期和Rb蛋白的表达。结果 Ad-Rb94组、照射组和Ad-Rb94联合照射组对EC109细胞生长均具有抑制作用,Ad-Rb94联合照射组的抑制效应最强,明显高于Ad-Rb94组和照射组(F=23.31,P<0.05)。Ad-Rb94联合照射组EC109细胞出现明显的G₂期阻滞,G₂期细胞所占比例达50%。Ad-Rb94联合照射组表达Rb蛋白的细胞明显增加,阳性率达71%,较Ad-Rb94组和照射组差异有统计学意义(χ²=8.31和6.73,P<0.05)。结论 Rb94基因联合照射能明显提高对人食管癌细胞的辐射增敏性。     

Indomethacin lowers the threshold thermal exposure for hyperthermic radiosensitization and heat-shock inhibition of ionizing radiation-induced activation of NF-κB

Purpose : It is well established that salicylate and several other non-steroidal anti-inflammatory agents (NSAID), including indomethacin, can activate the heat-shock response, albeit at high concentrations. This is significant since heat shock significantly alters the cellular cytotoxic response to ionizing radiation (IR). It was previously shown that heat shock, as well as NSAIDs, inhibits IR-induced activation of NF- κB and that NF- κB protects against IR-induced cytotoxicity. Hence, it is hypothesized that pretreatment with indomethacin before heating will lower the temperature and heating times required to inhibit the activation of NF- κB and induce significant hyperthermic radiosensitization. Materials and methods : Experiments were performed in HeLa cell lines and the DNA-binding activity was determined by EMSA. Cellular radiosensitivity was determined by clonogenic assay. Results : HeLa cells pretreated with indomethacin showed a decrease in the temperature-time combination necessary to inhibit IR-induction of NF- κB DNA binding. In addition, clonogenic cell survival assays using identical conditions showed an indomethacin dose-dependent enhancement of hyperthermic radiosensitization. Thus, similar concentrations of indomethacin both lowered the threshold thermal exposure to inhibit activation of NF- κB DNA-binding and increased the sensitivity of tumour cells to hyperthermic radiosensitization-induced cytotoxicity. In HeLa cells treated with N - α -tosylphenylalanyl-chloromethyl ketone (TPCK), a serine protease inhibitor that blocks activation of NF- κB, an increase in radiosensitivity was observed. Interestingly, no additional cell killing was observed when heat shock was added to cells treated with TPCK before IR, suggesting a possible common cytotoxic pathway. Conclusions : The results demonstrate that indomethacin lowers the temperature-time conbination necessary to induce several physiological processes associated with the heat-shock response. Furthermore, NSAID may be potential adjuvants in improving the clinical effectiveness of hyperthermia in radiation therapy.     

Micronuclei, CREST-positive micronuclei and cell inactivation induced in Chinese hamster cells by radiation with different quality

PURPOSE: To study the relative biological effectiveness-linear energy transfer (RBE-LET) relationship for micronuclei (MN) and cell inactivation, in Chinese hamster cells irradiated with low-energy protons (0.88 and 5.04 MeV, at the cell entrance surface). Chromosome loss was also investigated by means of antikinetochore CREST staining. MATERIALS AND METHODS: Cl-1 cells were exposed to different doses of X-rays, gamma-rays, 7.7 keV/microm and 27.6 keV/microm protons. The induction of MN, the distribution of MN per cell and the frequency of CREST-positive MN were evaluated in cytokinesis-blocked binucleated cells (BN cells) in the dose range 0.125-3 Gy. In parallel, cell survival experiments were carried out in samples irradiated with 0.5 to 4 Gy. RESULTS: MN yield and the frequency of BN cells carrying multiple MN (> or =2) were significantly higher after exposure to 27.6 keV/microm protons, compared with the other radiation types. In contrast, MN induction and MN distribution per BN cell were similar among 7.7 keV/microm protons, X- and gamma-rays up to 1 Gy. Cell survival experiments gave RBE values very close to those obtained with the MN assay. Both X-rays and 27.6 keV/microm protons yielded a significant proportion of CREST-positive MN at the highest doses investigated (0.75-3 Gy). CONCLUSIONS: Good correlations between MN induction and cell inactivation were observed for both low- and high-LET radiation, indicating that the MN assay can be a useful tool to predict cell sensitivity to densely ionizing radiation with implications for tumour therapy with protons.     

Increased body weight in C57BL/6 female mice after exposure to ionizing radiation or 60Hz magnetic fields

PURPOSE: The purpose of this investigation was to determine whether early treatment with ionizing radiation and/or chronic magnetic field (MF) exposure affected body weight in female mice. MATERIALS AND METHODS: Weanling C57BL/6 female mice were irradiated with four equal weekly cobalt-60 exposures (total cumulative doses: 3.0, 4.0, 5.1Gy) and/or received chronic lifetime exposure to 1.4 mT 60 Hz circularly polarized MF or ambient MF. The body weights of 2280 mice were recorded at 35 age intervals, and analysis of variance was used to compare the mean differences from baseline weights between treatment groups and sham-exposed controls. RESULTS: A highly statistically significant effect of ionizing radiation on body weight was observed at 28 age intervals (p < or = 0.001), and for MF exposure at 10 age intervals (p < or = 0.001). During the young adult growth phase, mice exposed only to MF exhibited < or =0.5 g greater weight gain relative to sham-exposed controls (p = 0.0001). The effect of ionizing radiation alone was inversely related to dose, with the largest weight increases observed in all of the irradiated groups after 9-12 months (p = 0.0001). CONCLUSIONS: Treatment with split-dose ionizing radiation at an early age and chronic exposure to a residential power frequency MF were found to produce small but significant increases in body weight.     

青蒿琥酯对人宫颈癌HeLa细胞的放射增敏作用

目的 探讨青蒿琥酯对人宫颈癌HeLa细胞的放射增敏作用。方法 应用⁶⁰Co γ射线照射细胞,吸收剂量率为0.635 Gy/min,照射剂量为0、1、2、4和6 Gy。采用MTT法检测青蒿琥酯对HeLa细胞的抑制作用,确定青蒿琥酯的最适实验作用浓度。克隆形成法检测青蒿琥酯对HeLa细胞放射敏感性的影响;采用"多靶单击数学模型"拟合HeLa细胞的剂量-存活曲线,得出平均致死剂量、准阈剂量及放射增敏比,评价其增敏效果。用流式细胞术检测HeLa细胞凋亡率,进一步检测青蒿琥酯对HeLa细胞的放射增敏性。结果 青蒿琥酯对HeLa细胞的抑制作用随药物浓度的增加而增加,单纯照射1、2、4和6 Gy细胞的克隆形成率分别为91.67%、82.02%、58.60%和25.01%,加入青蒿琥酯后,相同照射剂量下克隆形成率分别降低为74.93%、60.53%、22.38%和5.05%;单纯照射组与药物+照射组的平均致死剂量(D₀)分别为2.95和2.07 Gy,准阈剂量(D_q)分别为2.01和1.24 Gy,放射增敏比(SER)为1.43。单纯2和6 Gy照射组细胞凋亡率分别是12.26%和40.08%,加入青蒿琥酯后,相同照射剂量下细胞凋亡率分别上升至22.71%和59.92%。结论 青蒿琥酯对人宫颈癌HeLa细胞的抑制作用成药物浓度依赖性;青蒿琥酯对HeLa细胞具有一定的放射增敏作用。