随机定位模拟微重力促进人前破骨细胞增殖和分化

目的观察随机定位模拟微重力对人前破骨细胞FLG29.1增殖和分化的影响。方法 FLG29.1细胞分为正常对照组与随机定位处理组,分别培养72 h后收集细胞。采用细胞计数法检测细胞总数和活细胞数;流式细胞术检测细胞周期;Griess法检测培养基中NO(nitric oxide,NO)浓度;抗酒石酸盐酸性磷酸酶(TRAP)染色计算TRAP阳性细胞比例;对硝基苯磷酸(pNPP)法检测胞内TRAP活性。结果随机定位处理后,FLG29.1细胞增殖能力与活细胞比例均较对照组明显增加;细胞周期分布发生变化,处于G1期的细胞比例增加;培养基中NO浓度有增加趋势;在回转处理的同时添加诱导剂12-氧-十四烷酰佛波醋酸酯-13乙酸酯(TPA),发现TRAP阳性细胞数量增多;胞内TRAP活性较对照组明显增加。结论随机定位模拟微重力提高了FLG29.1细胞活力并促进其向破骨细胞分化。     

The role of Beclin 1 in SDT-induced apoptosis and autophagy in human leukemia cells

Abstract

Purpose: To prove the occurrence of autophagy after treatment by protoporphyrin IX (PpIX)-mediated sonodynamic therapy (SDT) of human chronic myelogenous leukemia K562 cells as well as its relationship with apoptosis.

Materials and methods: The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylter-trazolium bromide tetrazolium (MTT) assay was adopted to examine cytotoxicity of different treatments. Nuclear morphology changes were observed under a fluorescence microscopy with 4?-6-Diamidino-2-Phenylindole (DAPI) staining. Western blotting was used to analyze the expression of caspase-3, Beclin 1 (BECN 1) and the conversion of LC3- phosphatidylethanolamine conjugate/a cytosolic form of LC3 (LC3 II/I). Fluorescence microscope was used to identify the formation of autophagic vacuoles (AVO) during autophagy.

Results: Under optimal conditions, SDT was shown to induce autophagy in K562 cells, which caused the up-regulation of Beclin-1 and the formation of AVO. In addition, pre-treatment of cancer cells with Beclin 1-targeted short hairpin RNA (Beclin 1 shRNA) was shown to reduce the level of LC3-II accumulation and staining with punctate spots of monodansylcadaverine (MDC) staining. Besides, the cytotoxic effect of SDT was significantly increased by Beclin 1 shRNA. Furthermore, studies showed a marked effect on the apoptosis of cells by Beclin 1 shRNA to sonodamage with increased DAPI staining and caspase-3 cleavage.

Conclusions: These results demonstrated that SDT significantly induced autophagy of K562 cells, probably to protect the K562 cells from sonodamage.     

Effect of photodynamic therapy with hypocrellin B on apoptosis,adhesion, and migration of cancer cells

Abstract

Purpose: In the present study, we investigated effects of photodynamic therapy with hypocrellin B on apoptosis, adhesion, and migration of cancer cells in vitro.

Materials and methods: Human ovarian cancer HO-8910 cell as a cancer model cell was incubated with hypocrellin B at a concentration of 2.5 μM for 5 h and irradiated by light from a light-emitting diodes (LED) source. Cell apoptosis was analyzed by flow cytometry with annexin V/propidium iodide (PI) staining and nuclear staining 6 h after hypocrellin B photoirradiation. Cell adhesion was assessed using the 3-(4, 5-dimthylthiazol-2-yl)-2, 5 diphenyl-tetrazolium bromide (MTT) assay 4 h after photodynamic treatment. Cell migration was measured 48 h after photodynamic treatment.

Results: Flow cytometry with annexin V/PI staining showed that early apoptotic and late apoptotic (necrotic) rates following photodynamic therapy with hypocrellin B markedly increased to 16.40% and 24.67%, respectively. Nuclear staining found nuclear condensation and typical apoptotic body in the treated cells. The number of cell migration was significantly decreased to 183 ± 28 after photodynamic therapy with hypocrellin B (p < 0.01). Light irradiation alone and hypocrellin B alone had no significant effect on cell migration. The cell adhesion inhibitory rate due to photodynamic action of hypocrellin B was 53.2 ± 1.8%, significantly higher than 2.7 ± 2.1% of light treatment alone and 1.0 ± 0.4% of hypocrellin B treatment alone (p < 0.01).

Conclusion: The findings demonstrated that photodynamic therapy with hypocrellin B remarkably induced apoptosis and inhibited adhesion and migration of cancer cells in vitro.     

Gamma irradiation of human leukaemic cells HL-60 and MOLT-4 induces decrease in Mcl-1 and Bid,release of cytochrome c,and activation of caspase-8 and caspase-9

Purpose:?Apoptosis is significantly controlled by proteins of Bcl-2 (B-cell lymphoma 2) family promoting cell death or maintaining cell survival. We selected two representatives of Bcl-2 family (anti-apoptotic Mcl-1 – myeloid cell line-1 and pro-apoptotic Bid – Bcl-2 homology domain 3 interacting death agonist), cytochrome c (cyt-c), and two initial caspases (-8 and -9) to evaluate their function in ionizing radiation (IR)-induced apoptosis in human leukaemic cell lines diverging in p53 (TP53 tumor suppressor gene) status.

Materials and methods:?A total of 30 μg of proteins of whole-cell lysates or 10 μg of mitochondrial protein fractions were electrophoretically separated and analyzed by Western-blotting.

Results:?Here we show that in both HL-60 (p53 null) and MOLT-4 (p53 wild type) leukaemic cells the amount of Mcl-1 initially increased after irradiation by sublethal but not by lethal dose and later (when apoptosis occurred) it decreased in a dose-dependent manner. Caspase-8 was cleaved and afterwards the amount of Bid decreased as it was truncated. We also found cyt-c release from the inner mitochondrial membrane space into cytoplasm to be dose-dependent and it was followed by induction of apoptosis. In the p53-null cells caspase-8 was activated prior caspase-9, whereas the cells harboring p53 exhibited a simultaneous activation of both initial caspases.

Conclusion:?IR induced a decrease in Mcl-1, activation of Bid, caspase-8, and -9, and release of cyt-c. Presented data indicate that both extrinsic and intrinsic apoptosis signalling pathways were activated in HL-60 and MOLT-4 cells upon exposure to IR regardless to the p53 status.     

双氢青蒿素联合吉非替尼抑制肺腺癌细胞周期和迁移能力的体外研究

 目的 探究双氢青蒿素(dihydroartemisinin, DHA)联合吉非替尼(gefitinib, GEF)对肺腺癌细胞系的细胞周期和迁移能力的影响。方法 10 μM DHA和(或)50 μM GEF处理肺腺癌细胞系A549和SPC-A-1,四唑盐(methyl thiazolyl tetrazolim, MTT)比色法检测细胞增殖,流式细胞术检测细胞周期,划痕实验检测细胞迁移,蛋白质印记法(western blot, WB)检测单独或联合应用DHA和GEF对细胞周期和迁移相关蛋白表达的影响。结果 MTT实验结果显示联合应用DHA和GEF(Com组)后,A549和SPC-A-1的增殖能力显著低于单药组和对照(NC)组,且具有时间依赖性(P＜0.05);碘化丙啶(propidium iodide, PI)单染流式细胞术检测细胞阻滞于G₀/G₁期;WB显示与NC组和单药组相比,Com组细胞周期蛋白依赖性蛋白激酶4(cyclin dependent kinase 4,CDK4)和细胞周期素D1(Cyclin D1)表达显著下降;划痕实验中Com组细胞融合率显著低于NC组和单药组,并伴随基质金属蛋白酶(matrix metalloproteinase, MMP)2和MMP9表达下降,差异均具有统计学意义(P＜0.05)。结论 DHA联合GEF可以显著抑制肺腺癌细胞的增殖和迁移,并阻滞细胞周期。     

Cell death pathways in directly irradiated cells and cells exposed to medium from irradiated cells

Abstract

Purpose: The aim of this study was to compare levels of apoptosis, necrosis, mitotic cell death and senescence after treatment with both direct radiation and irradiated cell conditioned medium.

Materials and methods: Human keratinocytes (HaCaT cell line) were irradiated (0.005, 0.05 and 0.5 Gy) using a cobalt 60 teletherapy unit. For bystander experiments, the medium was harvested from donor HaCaT cells 1 hour after irradiation and transferred to recipient HaCaT cells. Clonogenic assay, apoptosis, necrosis, mitotic cell death, senescence and cell cycle analysis were measured in both directly irradiated cells and bystander cells

Results: A reduction in cell survival was observed for both directly irradiated cells and irradiated cell conditioned medium (ICCM)-treated cells. Early apoptosis and necrosis was observed predominantly after direct irradiation. An increase in the number of cells in G2/M phase was observed at 6 and 12 h which led to mitotic cell death after 72 h following direct irradiation and ICCM treatment. No senescence was observed in the HaCaT cell line following either direct irradiation or treatment with ICCM.

Conclusion: This study has shown that directly irradiated cells undergo apoptosis, necrosis and mitotic cell death whereas ICCM-treated cells predominantly undergo mitotic cell death.     

Hypocrellin B in hepatocellular carcinoma cells: Subcellular localization and sonodynamic damage

Abstract

Purpose: To study subcellular localization of hypocrellin B in hepatocellular carcinoma cells, and hypocrellin B-mediated sonodynamic action-induced cell damage.

Materials and methods: After incubation with 2.5 μM of hypocrellin B, human hepatocellular carcinoma HepG2 cells were exposed to ultrasound waves for 8 sec at an intensity of 0.46 W/cm². Clonogenic survival of HepG2 cells was measured using a colony forming assay and light microscope. Ultrastructural morphology was observed using transmission electron microscope (TEM) and mitochondrial membrane potential (MMP) was assessed using confocal laser scanning microcope (CLSM) after rhodamine 123 staining. Additionally, subcellular localization of hypocrellin B in HepG2 cells with organelle probe staining was also observed using CLSM.

Results: The colony forming units of HepG2 cells decreased substantially after sonodynamic treatment. The results of TEM showed microvilli disappearance, apoptotic body formation, swollen mitochondria with loss of cristae and mitochondrial myelin-like features (or membrane whorls). Collapse of MMP was found in the treated cells. Hypocrellin B was distributed in mitochondria and lysosomes as well as in endoplasmic reticulum and Golgi apparatus.

Conclusions: The findings demonstrated that sonodynamic action of hypocrellin B induced mitochondrial damage, survival inhibition, and apoptosis of HepG2 cells. Additionally, other subcellular organelles such as endoplasmic reticulum, Golgi apparatus and lysosomes were also the targets of hypocrellin B-mediated sonodynamic action as well as mitochondria.     

A role for endothelial cells in radiation-induced inflammation

Purpose: To unravel the role of the vasculature in radiation-induced brain tissue damage.

Materials and methods: Postnatal day 14 mice received a single dose of 10?Gy cranial irradiation and were sacrificed 6?h, 24?h or 7 days post-irradiation. Endothelial cells were isolated from the hippocampus and cerebellum using fluorescence-activated cell sorting, followed by cell cycle analysis and gene expression profiling.

Results: Flow cytometric analysis revealed that irradiation increased the percentage of endothelial cells, relative to the whole cell population in both the hippocampus and the cerebellum. This change in cell distribution indicates that other cell types are more susceptible to irradiation-induced cell death, compared to endothelial cells. This was supported by data showing that genes involved in endothelial cell-specific apoptosis (e.g. Smpd1) were not induced at any time point investigated but that genes involved in cell-cycle arrest (e.g. Cdkn1a) were upregulated at all investigated time points, indicating endothelial cell repair. Inflammation-related genes, on the other hand, were strongly induced, such as Ccl2, Ccl11 and Il6.

Conclusions: We conclude that endothelial cells are relatively resistant to ionizing radiation but that they play an active, hitherto unknown, role in the inflammatory response after irradiation. In the current study, this was shown in both the hippocampus, where neurogenesis and extensive cell death after irradiation occurs, and in the cerebellum, where neurogenesis no longer occurs at this developmental age.     

Valproic acid modulates radiation-enhanced matrix metalloproteinase activity and invasion of breast cancer cells

Abstract

Purpose: To evaluate matrix metalloproteinase (MMP) activity and invasion after ionizing radiation (IR) exposure and to determine whether MMP could be epigenetically modulated by histone deacetylase (HDAC) inhibition.

Material and methods: Two human breast cancer cell lines (MDA-MB-231 and MCF-7) were cultured in monolayer (2D) and in laminin-rich extracellular matrix (3D). Invasion capability, collagenolytic and gelatinolytic activity, MMP and TIMP protein and mRNA expression and clonogenic survival were analyzed after IR exposure, with and without a HDAC inhibition treatment [1.5?mM valproic acid (VA) or 1?μM trichostatin-A (TSA)].

Results: IR exposure resulted in cell line-dependent stimulation of invasion capacity. In contrast to MCF-7 cells, irradiated MDA-MB-231 showed significantly enhanced mRNA expression of mmp-1, mmp-3 and mmp-13 and of their regulators timp-1 and timp-2 relative to unirradiated controls. This translated into increased collagenolytic and gelatinolytic activity and could be reduced after valproic acid (VA) treatment. Additionally, VA also mitigated IR-enhanced mmp and timp mRNA expression as well as IR-increased invasion capability. Finally, our data confirm the radiosensitizing effect of VA.

Conclusion: These results suggest that IR cell line-dependently induces upregulation of MMP mRNA expression, which appears to be mechanistically linked to a higher invasion capability that is modifiable by HDAC inhibition.     

Response of human hematopoietic stem and progenitor cells to energetic carbon ions

Purpose:?To characterise the radiation response of human hematopoietic stem and progenitor cells (HSPC) with respect to X and carbon ion irradiation.

Materials and methods:?HSPC from peripheral blood of healthy donors treated with granulocyte-colony stimulating factor (G-CSF) were enriched for the transmembrane glycoprotein CD34 (cluster of differentiation) and irradiated with X rays or carbon ions (29 keV/μm monoenergetic beam and 60-85 keV/μm spread-out Bragg peak), mimicking radiotherapy conditions. Apoptotic cell death, cell cycle progression and the frequency of chromosomal aberrations were determined.

Results:?After radiation exposure no inhibition in the progression of the cell cycle was detected. However, an enhanced frequency of apoptotic cells and an increase in aberrant cells were observed, both effects being more pronounced for carbon ions than X rays, resulting in a relative biological effectiveness (RBE) of 1.4–1.7. The fraction of complex-type aberrations was higher following carbon ion exposure.

Conclusions:?RBE values of carbon ions are low, as expected for radiosensitive cells. The observed frequencies of apoptotic cells and chromosome aberrations in HSPC are similar to those reported for human peripheral blood lymphocytes suggesting that at least with respect to apoptosis and chromosomal aberrations mature lymphocytes reflect the respective radiation responses of their proliferating progenitors.     

Gamma irradiation of aloe-emodin induced structural modification and apoptosis through a ROS- and caspase-dependent mitochondrial pathway in stomach tumor cells

Purpose: The changes in molecular structure and the physiological properties of a gamma-irradiated aloe-emodin were examined.

Materials and methods: Aloe-emodin was gamma-irradiated at doses ranging from 0 to 150 kGy, and the molecular structure was then analyzed using high-performance liquid chromatography (HPLC). AGS cells were cultured in RPMI medium and treated gamma irradiated aloe-emodin. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis efficiency was investigated by cell cycle arrest, cell morphology, and signaling pathway. The structure of new radiolytic peak was identified by the hydrogen-nuclear magnetic resonance (¹H NMR).

Results: HPLC results showed that gamma irradiation induced new radiolytic peaks that were distinguishable from the aloe-emodin standard, and the area of new peaks was increased as the radiation dose increased. Gamma-irradiated aloe-emodin treatment significantly increased the cytotoxicity in AGS tumor cells. We also found that 150?kGy aloe-emodin increased the expression of Bax, cytosolic cytochrome c, PARP cleavage, and the activation of caspases-8, -9, -3, Bid, and Bcl-2. Treatment of 150?kGy aloe-emodin induced ROS production, DNA fragmentation, alterations of cell morphology, and the migration in AGS cells. Gamma-irradiated aloe-emodin induced an increase of sub-G1 phase and depolarization of mitochondrial membrane potential in AGS cells. We also confirmed that fractionated AEF1 (new radiolytic peak) induce the cell death, migration, an increase of sub-G1 phase and cytochrome c in a ROS-dependent manner.

Conclusions: The radiolysis product (AEF1) of aloe-emodin transformed by gamma-irradiation strongly induced apoptotic cell death in AGS cells, indicating AEF1 is a potential candidate drug for use in anti-cancer drug.     

The influence of differently polarised microwave radiation on chromatin in human cells

Purpose: To determine the possible biological effects of differently polarised microwave radiation on the chromatin state in human cells.

Materials and methods: Isolated human buccal epithelium cells were irradiated by microwaves of frequency f = 35 GHz and surface power density E = 30 μW/cm². The state of chromatin in human cells was determined by methods of light and electron microscopy. The state of cell membranes was evaluated by the method of vital indigo carmine staining.

Results: The microwave-induced condensation of chromatin in human cells is revealed. Degree of microwave-induced condensation depends on the state of polarisation of electromagnetic wave: In some cases left circularly polarised waves induce less effect than linearly polarised radiation. The linearly polarised electromagnetic waves induce cell membrane damage revealed by increase of cell staining. The data obtained are discussed in connection with mechanisms of biological effects of electromagnetic fields.

Conclusion: The data obtained in this work demonstrate important biological effects of monochromatic microwave irradiation at 35 GHz. Low-level microwave irradiation induces chromatin condensation in human cells and damages of cell membranes.     

UVA radiation augments cytotoxic activity of psoralens in melanoma cells

Purpose: Melanoma is an aggressive form of skin cancer. The aim of the study was to evaluate the influence of UVA radiation and psoralens: 5-methoxypsoralen (5-MOP) or 8-methoxypsoralen (8-MOP) on melanoma cells viability.

Materials and methods: The amelanotic C32 and melanotic COLO829 human melanoma cell lines were exposed to increasing concentrations of psoralens (0.1–100 μM) in the presence or absence of UVA radiation. Cell viability was evaluated by the WST-1 assay.

Results: We demonstrated that 8-MOP, in contrast to 5-MOP, has no cytotoxic effect on both melanoma cell lines. Simultaneous exposure of cells to 8-MOP and UVA radiation caused significant cytotoxic response in C32 cells where the EC₅₀ value was estimated to be 131.0 μM (UVA dose: 1.3 J/cm²) and 105.3 μM (UVA dose: 2.6 J/cm²). The cytotoxicity of 5-MOP on both C32 and COLO829 cells was significantly augmented by UVA radiation – the EC₅₀ was estimated to be 22.7 or 7.9 μM (UVA dose: 1.3 J/cm²) and 24.2 or 7.0 μM (UVA dose: 2.6 J/cm²), respectively.

Conclusions: The demonstrated high cytotoxic response after simultaneous exposure of melanoma cells to psoralens and UVA radiation in vitro suggests the usefulness of PUVA therapy to treat melanoma in vivo.     

The evaluation of radio-sensitivity of mung bean proteins aqueous extract on MCF-7, hela and fibroblast cell line

Purpose: Breast cancer is one of the most common malignant tumors in women all over the world. Many of these women resist the common treatments. Therefore, it is important to find new products to increase the efficacy of the treatment process. Legume beans, with their various pharmacological properties, can be regarded as a sensitizer when they are combined with radiation. The present study strove to survey the radio-sensitivity effect of proteins isolated from mung bean aqueous extract on the human breast adenocarcinoma cell line (MCF-7), human cervical cancer cells (Hela) and the human dermal fibroblast cell line.

Materials and methods: The mung bean aqueous extract was partially purified by ammonium sulfate. At first, various concentrations of the extracts were used to evaluate the inhibitory activity by MTT cell proliferation assay.

Results: The results showed that MCF-7 cells and Hela cells were inhibited by an IC₅₀ value of less than 250 and 411?µg/ml, respectively, but it proved to have a proliferation effect on the fibroblast cells. Then, the cells were incubated with 250?µg/ml extract and exposed to 2, 4, and 6?Gy of X-ray radiation. The percentage of the cell survival was investigated through MTT and the clonogenic assay. Apoptosis was measured using acridine orange/ethidium bromide staining. The results demonstrated that the treated MCF-7 cells and Hela cells had significant radio-sensitivity compared with the results of the control group in radiation dose manner in all MTT, clonogenic, and apoptosis assays. In contrast, the treated fibroblast showed a protective effect against radiation.

Conclusion: The results suggest that mung bean proteins have the capacity to be regarded as a radio-sensitizer for breast cancer. Our results also indicated that it could be worth to investigate on mung bean proteins further and they should be tested in animal models for being treated in radiotherapy.     

Famitinib enhances nasopharyngeal cancer cell radiosensitivity by attenuating radiation-induced phosphorylation of platelet-derived growth factor receptor and c-kit and inhibiting microvessel formation

Purpose: Famitinib is a novel tyrosine kinase inhibitor. We investigated the effects of famitinib on the radiosensitivity of human nasopharyngeal carcinoma (NPC) cell radiosensitivity in vitro and in vivo, and explored its possible mechanisms.

Materials and methods: Human nasopharyngeal carcinoma cell line (CNE-2) were treated with famitinib and radiation, and analyzed by3-(4,5-dimethylthaizol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), clonogenic survival assay, and Western blot. A xenograft model using CNE-2 cells was established to analyze the effects of famitinib and radiation on tumor volume and microvessel density (MVD).

Results: Famitinib dose-dependently inhibited CNE-2 cells growth and significantly reduced clonogenic survival (p < 0.05), with a sensitivity enhancement ratio (SER) of 1.45. The tumor inhibition rate of the combined treatment group was 91%, which was significantly higher than the radiation group (35%, p < 0.05) and famitinib group (46%, p < 0.05). Famitinib attenuated radiation-induced phosphorylation of the platelet-derived growth factor receptor (PDGFR) and stem cell factor (c-kit) at 0, 30, 60 min after radiation treatment. Furthermore, radiation combined with famitinib decreased tumor MVD (p < 0.05).

Conclusions: Famitinib significantly increased CNE-2 cell radiosensitivity in vitro and in vivo by attenuating radiation-induced PDGFR and c-kit phosphorylation and by inhibiting microvessel formation.     

Involvement of MAPK activation and ROS generation in human leukemia U937 cells undergoing apoptosis in response to sonodynamic therapy

Abstract

Purpose: To elucidate the underlying events in Chlorin e6 (Ce6)-mediated sonodynamic therapy (SDT) (Ce6-SDT)-induced apoptosis of human leukemia cell line U937.

Materials and methods: The viability of cells was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltertrazolium bromide tetrazolium (MTT) test. Apoptosis was analyzed using a ?ow cytometer as well as ?uorescence microscopy with 4′-6-Diamidino-2-Phenylindole (DAPI) staining. Western blotting was used to analyze the expression of caspase-3, poly ADP- ribose polymerase (PARP) and mitogen-activated protein kinase (MAPK).

Results: Several distinct sonochemical effects were found after SDT treatment. The participation of MAPK signals in SDT which caused U937 cell damage was specifically examined and the inhibition of p38 MAPK and Jun-N-terminal kinase (JNK) both apparently exerted a negative effect on SDT-induced cell death, while extracellular signal-regulating kinase (ERK1/2) inhibition enhanced SDT-induced cell death. The intracellular reactive oxygen species (ROS) was significantly enhanced by SDT, and pre-treatment with ROS scavenger N-acetylcysteine (NAC) partially alleviated SDT-induced cell viability loss, DNA fragmentation, mitochondria membrane potential (MMP) dissipation, caspase-3 activation, but interestingly MAPK activation was not affected much by NAC.

Conclusions: In the present paper, cell apoptosis of U937 cells was markedly enhanced after Ce6-SDT. Meanwhile, p38 MAPK, JNK and ERK were all differently activated in this process. One possible explanation for the induced cell apoptosis could be the increased ROS generation in Ce6-SDT.     

Role of N-acetyl cysteine and acetyl-l-carnitine combination treatment on DNA-damage-related genes induced by radiation in HEI-OC1 cells

Abstract

Purpose: The aim of the present study was to evaluate the effect of acetyl-l-carnitine (ALC) and N-acetyl cysteine (NAC) on ionizing radiation (IR)-induced cytotoxicity and change in DNA damage-related genes in House Ear Institute-Organ of Corti 1 (HEI-OC1) cells.

Methods: HEI-OC1 cells were irradiated with 5?Gy radiation and treated by eight combinations of NAC and/or ALC: control, NAC, ALC, IR, NAC?+?IR, ALC?+?NAC, ALC?+?IR, and ALC?+?NAC?+?IR. Cell viability, apoptotic cell death, and DNA damage were measured at the 72nd hour. Eighty-four IR-induced DNA-damage-related genes were determined by RT-PCR gene array and >10-fold changes were considered significant.

Results: IR decreased cell viability by about 50% at 72?hours of incubation. In particular, the ALC and/or NAC combination before IR protected the HEI-OC1 cells (p?<?.05). Single and combination treatment prior to IR led to lower apoptotic cell death (p?<?.05). There was a significant lower DNA damage in ALC?+?NAC?+?IR group compared to IR group (p?<?.05). Expressions of Brca2, Xpc, Mlh3, Rad51, Xrcc2, Hus1, Rad9a, Cdkn1a, Gadd45a which are the DNA-repair genes were found to be significantly higher in NAC?+?ALC?+?IR group than those in individual treatment of ALC or NAC.

Conclusions: ALC and/or NAC treatment prior to IR led to higher cell viability and lower apoptotic cell damage compared to the IR group. The results of the study show that the ALC?+?NAC combination treatment inhibits DNA damage and induces DNA-repair genes to repair radiation damage, and this combination treatment is more effective against radiation-induced DNA damage than NAC or ALC therapy individually.