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Objective@#To investigate the effect of fractionated radiotherapy on the immune system of mice with subcutaneously transplanted hepatocellular carcinoma.@*Methods@#Logarithmic growth of mouse hepatocellular carcinoma cells Hepa 1-6 were inoculated subcutaneously on the right side of C57BL/6 J mice (1×107 cells /mice). The tumor-bearing mice were randomly divided into control group (Ctrl) and irradiation group (IR), 20 mice in each group. Additionally, 10 healthy mice were set as normal control group. Local fractionated X-ray irradiation of 8 Gy×3 fraction was given to the subcutaneous tumors, and the dose rate was 0.883 Gy/min. At 7 and 14 d after irradiation, the tumor organ index, spleen organ index, spleen pathological changes, and splenic T lymphocyte subsets, B lymphocyte subsets, and NK cells were detected.@*Results@#Compared with Ctrl, at 7 and 14 d after irradiation, the tumor organ index decreased (t=4.649, 26.34, P<0.05), and the percentage of NK cells increased significantly (t=3.952, 3.633, P<0.05). The percentages of CD3+ , CD4+ , CD3+ CD4+ lymphocytes and the ratio of CD4+ /CD8+ lymphocyte decreased at 7 d after irradiation (t=3.193, 3.656, 3.219, 2.641, P<0.05), and the percentage of CD3+ lymphocyte decreased at 14 d after irradiation (t=3.031, P<0.05). But after irradiation, there were no significant changes in spleen organ index, B lymphocyte, CD3+ CD4+ lymphocyte and CD8+ lymphocyte.@*Conclusions@#Local hepatoma radiotherapy causes imbalance of lymphocytes in distal spleen of mice and hence reduces immunity, which provides a novel mechanism of radiological immunity damage.
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Histone modification plays an important role in the process of cellular DNA damage repair. In recent years, a great number of studies have shown that histone modification affectsradiation responses including recruitment of DNA damage repair factors, creation of chromatin open structures and establishment of repressive histone marks.Regulation of histone modification may influence the process of DNA damage repair and thus affect radiation sensitivity. In this paper, the effects of histone modification on DNA damage repair, cellular radiosensitivity and the underlying mechanisms are reviewed.
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Objective:To investigate the protective effect of cimetidine on mice with fractionated X-ray irradiation through right thorax.Methods:Thirty male C57BL/6 mice were randomly divided into control group, irradiation group and irradiation + cimetidine group (100 mg/kg), 10 mice in each group. Mice right thorax was locally irradiated with X-rays at a dose rate of 0.883 Gy/min to a cumulative dose of 24 Gy, 8 Gy per day in 3 d. After irradiation, the irradiation + cimetidine group was given cimetidine (100 mg·kg -1·d -1) for 7 d consecutively, and Ctrl and IR groups were given saline. Seven days after irradiation, the mice weight, spleen index and its T lymphocytes, B lymphocytes and NK cells were measured. Spleen tissue was stained with HE for pathological observation. Results:The fractionated irradiation lightly suppressed mice growth but obviously induced abscopal damage on spleen so that the spleen index were decreased. The irradiation group (0.369±0.011) had statistically significant difference compared with the control group(0.396±0.022)( t=2.978, P<0.05), the spleen pathological structure became disorder, and the percentages of CD3+ , CD4+ , CD3+ CD4+ , CD3+ CD8+ lymphocytes in spleen were decreased significantly( t=5.754, 3.570, 4.442, 5.281, 4.570, P<0.05). Cimetidine could partially restore the weight of irradiated mice, relieved spleen structure damage and effectively restored lymphocyte subsets, and partly recovered the levels of CD3+ , CD3+ CD4+ , CD3+ CD8+ lymphocytes in the spleen ( t=3.523, 2.706, 2.520, P<0.05). Conclusions:Cimetidine, as a potential radiation protection drug, could effectively reduce the mouse spleen injury induced by X-ray fractionated irradiation by improving mouse immune function.
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Objective To investigate the effect of fractionated radiotherapy on the immune system of mice with subcutaneously transplanted hepatocellular carcinoma.Methods Logarithmic growth of mouse hepatocellular carcinoma cells Hepa 1-6 were inoculated subcutaneously on the right side of C57BL/6 J mice (1×107 cells/mice).The tumor-bearing mice were randomly divided into control group (Ctrl) and irradiation group (IR),20 mice in each group.Additionally,10 healthy mice were set as normal control group.Local fractionated X-ray irradiation of 8 Gy×3 fraction was given to the subcutaneous tumors,and the dose rate was 0.883 Gy/min.At 7 and 14 d after irradiation,the tumor organ index,spleen organ index,spleen pathological changes,and splenic T lymphocyte subsets,B lymphocyte subsets,and NK cells were detected.Results Compared with Ctrl,at 7 and 14 d after irradiation,the tumor organ index decreased (t =4.649,26.34,P＜0.05),and the percentage of NK cells increased significantly (t =3.952,3.633,P＜0.05).The percentages of CD3+,CD4+,CD3+CD4+ lymphocytes and the ratio of CD4+/CD8+ lymphocyte decreased at 7 d after irradiation (t=3.193,3.656,3.219,2.641,P＜0.05),and the percentage of CD3+lymphocyte decreased at 14 d after irradiation (t =3.031,P＜0.05).But after irradiation,there were no significant changes in spleen organ index,B lymphocyte,CD3 + CD4+ lymphocyte and CD8 + lymphocyte.Conclusions Local hepatoma radiotherapy causes imbalance of lymphocytes in distal spleen of mice and hence reduces immunity,which provides a novel mechanism of radiological immunity damage.
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Objective To establish an intestinal organoid-based assay to investigate the radiation mitigation effect of epiregulin in vitro. Methods Intestinal crypts were released from tissue incubated with EDTA. Intestinal crypts seeded in 3D matrigel were irradiated at 24 h after plating. The radiation mitigation effect of epiregulin was evaluated by measuring the survival rate, size and budding numbers of the organoid after irradiation, and the basic FGF was used as a positive control of epiregulin. Results Radiation-induced lethality and dose-dependent survival curve of the intestinal organoid were consistent with in vivo data. Treatment with epiregulin (400 ng/ml) at 24 h post-radiation significantly increased survival rate of 8 Gy X-ray irradiated intestinal organoid in comparison with non-treated group [(12.56 ± 1.02)％vs. (4.73 ± 0.38)％, t=12.43,P<0.05]. Conclusions Epiregulin has radiation mitigation effect on intestinal organoid and could serve as a potential medical countermeasure to mitigate gastrointestinal toxicity.
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Objective To investigate the changes of invasion and migration potential of residual hepatocarcinoma cells after fractionated X-ray irradiation and its underlying mechanism.Methods HepG2 cells were exposed to X-rays (2 Gy × 10) and recovered for 30 days after irradiation to generate residual cells.The changes of cellular invasion and migration potential were detected in the residual and its control cells using a Transwell assay.The expressions of epithelial-mesenchymal transition(EMT)-related proteins of N-cadherin and Snail were detected by Western blot.HepG2 subcutaneous tumor models were established using nude mice that were divided into control and radiation group.In radiation group,the tumors were locally irradiated with a dose of 2 Gy per fraction daily,5 days per week for 2 weeks until the cumulative dose reached to 20 Gy.The growth of the tumor was observed,and on the day 39 after cell implantation (i.e.day 14 after radiation),the liver metastasis and the expression of N-cadherin in tumor with or without radiation were detected.Results The invasions and migrations of the residual cells and xenograft tumor were significantly enhanced in comparison with the control group (t =5.126,7.714,P ＜0.05).The expressions of N-cadherin and Snail in the radiation group were significantly higher than that in the control group (t =7.509,7.184,P＜0.05).In the HepG2 subcutaneous tumor model,the weight and volume of tumor in nude mice of the radiation group was significantly smaller than that in the control group (t =2.396,3.170,P ＜0.05),and the number of liver metastases in nude mice and the expression of N-cadherin in tumor were significantly higher than those in the control group (t =2.994,5.695,P ＜0.05).Conclusions Fractionated irradiation enhances the abilities of invasion and migration by inducing EMT in hepatocarcinoma cells,which provides new insights of the recurrence and metastasis of hepatocarcinoma after radiotherapy.
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If loosely defined,an abscopal effect occurs when localized irradiation affects the whole organism.In recent years,distant tumor regression and normal tissue damage after localized irradiation have been concerned by immuno-oncologists.However,the mechanisms of this effect are still far from clear.Mounting evidences suggest that the generation of abscopal effects is closely related to immune regulation.Radiotherapy might become a systemic tumor-treatment modality by enhancing immune function and played an important role in every stage of tumor development and prognosis.For the moment,targeting the immune checkpoint has become an attractive approach for malignant tumor therapy.Preclinical data have revealed that a strong abscopal effect could be effectively induced by the co-treatement of immune checkpoint inhibitors and irradiation,which could recruit antitumor T cells and achieve a powerful antitumor effect.This review discusses current progress and perspectives of abscopal effects in the combination of radiotherapy and immunotherapy.
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Cumulative evidence demonstrated that the chromatin modification plays important roles in the processes of DNA replication,transcription,repair and recombination.Both of the generation of DNA lesions and the activation of DNA damage response (DDR) to ionizing radiation could be affected by the chromatin modifications.This paper reviewed the recent research progresses in the chromatin structure modifications and its role in DDR,especially the influence of characteristic chromatin structure and histone modification on the radiation sensitivity of tumor cells.
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Objective To measure the difference of radiosensitivity between small and large intestines toward high dose of radiation and investigate the role of stem cells in this difference.Methods C57BL/6 male mice,6-8 weeks old,were randomly divided as control group and radiation group received 19 Gy whole body γ-ray irridiation.Large and small intestines of the mice were collected 6,12,24,48,72 and 96 h after radiation.The proliferation and apoptosis of the large and small intestines and their stem cells were then detected by immunochemistry,and the change of stem cell number in the large and small intestines were detected by in-situ hybridization.Results HE staining showed that 19 Gy γ-ray irradiation caused more severe injury in the small intestine,and all the crypt in the small intestine were extinct at 48 h post-radiation.However,the proliferation index of crypt in the large intestine was as high as 0.23 (t =4.67,P ＜0.05).Compared with the small intestine,the apoptotic index of epithelial cells in the crypt of large intestine was much lower at 12 and 24 h after irradiation (t =-1.92,-2.42,P＜0.05).The apoptotic population of stem cells in the small intestine at 12 and 24 h post irradiation were significantly lower than that in the large intestine (t =-1.98,-2.33,P ＜ 0.05),and the number of stem cell in the large intestine was significantly higher than that in the small intestine 24,48 h after radiation (t =1.98,3.31,P ＜0.05).Conclusions The radiosensitivity of small intestine toward high dose of irradiation is significantly higher than that of the large intestine,where the difference in radiosensitivity of stem cells between large intestine and small intestine may be involved.
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Objective To investigate the effects of long-term low-dose radiation (LDR) of γ-rays on the proliferation and radiosensitivity of human lymphoblast cells HMy2.CIR (HMy) and to elucidate the underlying mechanism.Methods HMy cells were divided into control group and long-term LDR group.For the long-term LDR treatment,HMy cells were fractionally exposed to a low dose of γ-rays,which could enhance cell proliferation,3 times per week for 4 weeks.After the long-term LDR exposure,part of the control and long-term LDR exposed cells were further irradiated with a challenging dose (2 Gy) of γ-rays.Then cell proliferation and radiosensitivity were assayed by CCK-8 kit,cell apoptosis,and γ-H2AX formation was measured by flow cytometry.Gene expressions of cyclinD1,PCNA,bcl-2 and bax were detected by RT-PCR.Results The long-term LDR significantly increased cell proliferation (t =9.607,P ＜ 0.01) accompanied with up-regulation of cell cycle regulation gene cyclinD1 (t =6.869,P ＜ 0.01),proliferation regulation gene PCNA (proliferating cell nuclear antigen) (t =9.229,P ＜ 0.01) and bcl-2 gene (t =2.662,P ＜ 0.05),but decreased the expression of pro-apoptotic gene bax (t =19.908,P ＜0.01) in HMy cells.Compared to untreated cells,the long-term LDR decreased cell radiosensitivity (t =8.896,P ＜ 0.01),including apoptosis induction (t =4.762,P ＜ 0.01) and γ-H2AX formation (t =10.264,P＜0.01).Conclusions The long-term LDR promoted cell proliferation by up-regulating cell cycle related genes,while it reduced the radiosensitivity of HMy cells with acquisition of apoptotic resistance.
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Objective To evaluate the effect of gamma irradiation on the proliferation,differentiation,and mineralization of murine osteoblastic cells,and to investigate the related molecular mechanism.Methods Osteoblastic cells were irradiated by different doses (0,0.5,1.0,2.0,5.0 Gy)of 137Cs γ-rays.Cell morphology was observed with a microscopy,cell viability was analyzed by MTT assay,and ALP activity was analyzed by the methods of enzyme histochemistry and PNPP.Meanwhile,gene expressions of ALP,osteocalcin (OC),collagen Ⅰ,osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) were measured by semi-quantified RT-PCR.Results Cell viability decreased with the radiation doses over 1.0 Gy ( t =6.197 - 18.677,P ＜ 0.05 ).After radiation with a dose over 2.0 Gy,the cell number and the junctions of cell protrusions decreased,the cells had low refractivity and the activity and mineralization ability of ALP were also inhibited ( t =2.790 -2l.374,P ＜0.05).In addition,the expressions of ALP and OC mRNA were down-regulated significantly (t =3.563 -16.508,P ＜ 0.05) when the radiation dose was higher than 0.5 Gy,and the expressions of OPG,OPG/RANKL mRNA were down-regulated ( t =12.942,4.954,P ＜ 0.05 ) at 5 Gy.But the expressions of collagen Ⅰ and RANKL mRNA were not affected by irradiation.Conclusions The osteoblastic cells were significantly influenced by γ-irradiation,including morphological changes,inhibition of cell proliferation,differentiation and mineralization ability. Meanwhile,mRNA expressions of ALP and OC were downregulated.OPG/RANKL may be a main pathway of osteoblastic cell damage under high dose radiation.
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Objective To investigate the dose-response of micronuclei (MN) frequency in the lymphocytes irradiated with or without combination of α-particles and γ-rays. Methods Human lymphoblast cells HMy2.CIR were irradiated with 0 - 1 Gy of α-particles,0 - 5 Gy of γ-rays,and 0.025 -0.5 Gy of α-particles followed by different doses of γ-rays,respectively.The micronuclei (MN) in the irradiated cells were measured with the cytokinesis block technique,and the dose-responses of MN were established under different irradiation conditions.Results For γ-ray irradiation,the dose-response of MN was well-fit by the linear-quadratic model with an equation Y =c + αD + βD2.For α-particle irradiation,the MN induction increased linearly with the dose less than 0.250 Gy. But when the dose of α-particles increased continually,the dose-response curve bended and could be well fit with the BaD model Y =c + αD + σ[ 1 - exp( - δD) ] exp( - βD) where radiation-induced bystander effect (RIBE) was indicated.For the combined exposure,the dose-response of MN was similar to that of γ-irradiation when the dose of α-particles was lower than 0.1 Gy,but it was similar to that of α-irradiation when the dose of α-particles was higher.When the dose of α-particles was 0.2 and 0.5 Gy,MN induced by the mixed radiation were significantly higher than the sum of corresponding irradiation alone ( t =5.22 - 11.86,P ＜ 0.05 ).Conclusions The radiation damage of α-particles differs from that of γ-rays,where RIBE may be involved.The combination irradiation of α-particles and γ-rays has a synergistic effect on radiation damage of lymphoblast cells.
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Objective To investigate radiation induced bystander effect and its mechanism on hepatoma HepG2 cells under hypoxia condition. Methods Non-irradiated bystander hepatoma cells were co-cultured with irradiated cells or treated with the conditioned medium (CM) from irradiated cells, then micronuclei (MN) were measured for both irradiated cells and bystander cells. Results The MN yield of irradiated HepG2 cells under hypoxic condition was significantly lower than that under normoxia, the oxygen enhancement ratio of HepG2 cells of MN was 1.6. For both hypoxic and normoxic condition, the MN yield of bystander cells were obviously enhanced to a similar high level after co-culturing with irradiated cells or with CM treatment, and it also correlated with the irradiation dose. When the hypoxic HepG2 cells were treated with either DMSO, a scavenger of reactive oxygen species (ROS), or aminognanidine, an iNOS inhibitor, the yield of bystander MN was partly diminished, and the reducing rate of DMSO was 42.2%-46.7 %, the reducing rate of aminognanidine was 42 %. Conclusion ROS, NO and their downstream signal facets are involved in the radiation induced bystander effect of hypoxic HepG2 cells.
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Objective To investigate cadmium induced adaptive responses (AR) to either toxicant challenge or irradiation and also the role of PI3K family in the AR. Methods Cells were pre-treated with 0.1 or 1 μmol/L cadmium and then challenged by 50, 100 μmol/L cadmium or 1, 2 Gy γ-rays irradiation. Micronucleus induction was measured to evaluate the magnitude of AR. In some experiments, cells were treated with wortmannin during and after pretreatment. Results Cadmium of sub-lethal concentration could induce AR in all the cells toward 50 μmol/L cadmium or 1 Gy irradiation. When challenged by 50 μmol/L CdCl1, EM-C11 cells had an AR less apparent than the other two cell lines. Moreover, treatment of cells with wortmannin eliminated the AR in all three cell lines. Conclusions The magnitudes of AR in adapted cells may be related to multiple factors, such as DNA repair capacity, the priming and challenging dose of cadmium or irradiation. SSB rather than DSB repair is mainly involved in the cadmium induced AR and this cellular response may be mediated through ATM pathway.