Synergistic effect of hyperthermia and neferine on reverse multidrug resistance in adriamycin-resistant SGC7901/ADM gastric cancer cells

Multidrug resistance(MDR) plays a major obstacle to successful gastric cancer chemotherapy.The purpose of this study was to investigate the MDR reversal effect and mechanisms of hyperthermia in combination with neferine(Nef) in adriamycin(ADM) resistant human SGC7901/ADM gastric cancer cells.The MDR cells were heated at 42℃ and 45℃ for 30 min alone or combined with 10 μg/mL Nef.The cytotoxic effect of ADM was evaluated by MTT assay.Cellular plasma membrane lipid fluidity was detected by fluorescence polarization technique.Intracellular accumulation of ADM was monitored with high performance liquid chromatography.Mdr-1 mRNA,P-glycoprotein(P-gp),γH2AX expression and γH2AX foci formation were determined by real-time PCR,Western blot and immunocytochemical staining respectively.It was found that different heating methods induced different cytotoxic effects.Water submerged hyperthermia had the strongest cytotoxicity of ADM and Nef combined with hyperthermia had a synergistic cytotoxicity of ADM in the MDR cells.The water submerged hyperthermia increased the cell membrane fluidity.Both water submerged hyperthermia and Nef increased the intracellular accumulation of ADM.The water submerged hyperthermia and Nef down-regulated the expression of mdr-1 mRNA and P-gp.The water submerged hyperthermia could damage DNA and increase the γH2AX expression of SGC7901/ADM cells.The higher temperature was,the worse effect was.Our results show that combined treatment of hyperthermia with Nef can synergistically reverse MDR in human SGC7901/ADM gastric cancer cells.     

Effect of prolonging interval time between coronary angiography and percutaneous coronary intervention on X-ray-induced DNA double-strand breaks in blood lymphocytes

Background It is desirable to minimize the risk of adverse radiation effects associated with percutaneous coronary intervention.The aim of this study was to determine the impact of prolonging the interval between coronary angiography and percutaneous coronary intervention on X-ray-induced DNA double-strand breaks in blood lymphocytes using γ-H2AX immunofluorescence microscopy.Methods Blood samples of eight patients were taken before the first exposure to ionizing radiation,10 minutes,20 minutes,30 minutes,1 hour,and 24 hours after the last exposure to determine the γ-H2AX foci repair kinetics.Fifty-eight patients undergoing percutaneous coronary intervention were randomized to an intermittent radiation exposure group and a continuous radiation exposure group.Blood samples were taken before coronary angiography and 15 minutes after the last exposure.By enumerating γ-H2AX foci,the impact of prolonging the interval on DNA double-strand breaks was investigated.Student t-test was used to compare the difference in DNA double-strand breaks between the two groups.Results An increase in foci was found in all patients received percutaneous coronary intervention.The maximum number of γ-H2AX foci was found 10-20 minutes after the end of the last exposure.There was no statistically significant difference between the two groups in γ-H2AX foci at baseline.On average there were （0.79±0.15） γ-H2AX foci induced by interventional X-rays per lymphocyte in the continuous radiation exposure group and （0.66±0.21） in the intermittent radiation exposure group after exposure （P〈0.05）.Conclusions A significant number of γ-H2AX foci develop following the percutaneous coronary intervention procedures.The number of X-ray-induced DNA double-strand breaks may be decreased by prolonging the interval time between coronary angiography and percutaneous coronary intervention to 30 minutes.     

Mechanism of thalidomide to enhance cytotoxicity of temozolomide in U251-MG glioma cells in vitro

Background Glioma is the most common primary brain tumor with poor prognosis. Temozolomide has been used with thalidomide to treat gliomas. We investigated the synergistic mechanism of these two drugs in vitro. Methods Human malignant glioma cells U251-MG were cultured and assigned to four groups with different treatments for 3 days： temozolomide group （100 μmol/L）, thalidomide group （100 μg/L）, temozolomide （100 μmol/L） plus thalidomide group （100 μg/L） and control group. MTT assay was applied to evaluate the cell viability. Cell cycle was analyzed by flow cytometry. The ultra-structural features of autophagosomes were observed with electron microscope. Acridine orange and monodansylcadaverine were adopted to label autophagosomes and flow cytometry was applied for quantification of autophagosomes. The expression of autophagy-associated protein was detected by Western blotting. Results Proliferation of tumor cell was obviously suppressed by temozolomide with thalidomide treatment than by either drug used alone （P=0.000 for each day）. The combination treatment induced cell cycle arrest at G0/G1 phase. Typical autophagic ultra-structural character was found after the combined treatment. Thalidomide promoted the autophagy induced by temozolomide. The autophagy-associated proteins - microtubule associated protein 1 light chain 3 （MAP1LC3） and Beclinl were more significantly up-regulated by the combined treatment than temozolomide used alone （MAP1LC3, P=0.000; Beclinl, P=0.004）. The expression level of phosphatase and tensin homolog deleted on chromosome ten （PTEN）, which promoted autophagy by suppressing PI3K/Akt/mTOR signaling pathway, was elevated by thalidomide （thalidomide group： P=0.000; combined group： P=0.002）. Conclusions Thalidomide enhances the cytotoxicity of temozolomide by promoting the autophagy induced by temozolomide. Contributing to the up-regulation of PTEN by thalidomide, the expression of autophagy associated protein-MAP1LC3 and Beclinl was enhanced, which leads to a reinforced autophagy in the combined treatment of temozolomide and thalidomide in vitro.     

Irradiation Injury Temporarily Induces Enhancement of APN/CD13 Peptidase Activity on Aorta-gonads-mesonephros （AGM）-derived Stromal Cells

This study was designed to investigate the expression of aminopeptidase N (APN)/CD13 on intraembryonic AGM stromal cells, and the change of its enzymatic activity after irradiation injury. The expression of APN/CD13 on AGM stromal cells was assayed by RT-PCR and immunihistochem- istry. After the stromal cells in AGM region were irradiated with 8.0 Gy of 60Co γ-rays, APN/CD13 enzymatic activity was measured by spectrophotometer at different time points. The result showed that AGM stromal cells strongly expressed APN/CD13. The enzymatic activity of APN/CD13 de- creased temporarily after irradiation injury, then increased to higher level 4 h after irradiation, and it returned to the pre-irradiation level 24 to 48 h after the irradiation. The enzymatic activity of APN/CD13 was temporarily enhanced after irradiation injury, which might be one of the compensa- tory mechanisms that promote the hematopoietic recovery after irradiation.     

蛋白激酶CK2基因表达沉默对鼻咽癌细胞放射增敏作用

目的 研究蛋白激酶CK2表达沉默对鼻咽癌细胞放射增敏作用,并探讨其可能机制.方法 通过RNA干扰技术下调鼻咽癌5-8F细胞中CK2α蛋白表达,利用Western blotting方法验证干扰效果;利用克隆形成实验观察CK2表达沉默后对鼻咽癌细胞放射敏感性的影响;应用免疫荧光方法检测γ-H2AX灶点形成;Annexin-V和PI双染流式细胞仪检测细胞凋亡.结果 通过RNA干扰技术可以有效沉默CK2α表达.克隆形成实验结果显示CK2α表达沉默后,鼻咽癌细胞形成克隆能力明显下降,对X线的敏感性明显增加;1 Gy照射后15min,CK2α沉默的细胞γ-H2AX灶点数目明显增加;CK2α沉默的细胞凋亡率明显高于对照组(P<0.01).结论 蛋白激酶CK2与鼻咽癌放射敏感性密切相关,CK2可能是一个非常有潜力的鼻咽癌治疗靶点.

Abstract：

Objective To investigate the effect of protein kinase CK2 gene silencing on the radiosensitization in human nasopharyngeal carcinoma (NPC) cells and its possible mechanism. Methods RNA interference (RNAi) technique was used to down-regulate the protein kinase CK2α expression in 5-8F cells, and clonogenic assay was employed to observe the changes in the radiosensitivity of the cells. DNA double-strand break was assessed by immunofluorescence staining of γ-H2AX foci,and the cell apoptosis was examined using Annexin V-FITC/PI double-staining flow cytometry. Results CK2α protein was successfully silenced by siRNA. CK2α knockdown significantly decreased the clonogenic activity and increased the radiosensitivity of the NPC cells. After a 15-min exposure of the cells to 1 Gy radiation, significant difference occurred in the γ-H2AX foci between CK2α knockdown cells and the control cells (P<0.01). CK2α silencing significantly increased the cell apoptosis after the exposure (P<0.01). Conclusion Protein kinase CK2 plays an important role in the radiosensitivity of the NPC cells, and suppression of its expression might be a potential therapeutic approach of cancer.     

Effect of Anluohuaxian Tablet Combined with γ-IFN on Schistosomal Liver Fibrosis

The therapeutic effects of anluohuaxian tablet combined with γ-IFN on schistosomal liver fibrosis and its mechanism were studied in a murine model and clinical cases of schistosomal liver fibrosis, Fifty Kunming mice were randomly divided into 5 groups： normal control group, infection control group, anluohuaxian tablet-treated group, γ-IFN-treated group and combined treatment （anluohuaian tablet＋γ-IFN） group. Pathologic changes in liver, including hepatic pigmentation and the size of schistosomal egg granuloma, were observed by HE staining after treatment for 8 weeks. The expression of the type Ⅰ and Ⅲ collagen, and TIMP-1 was detected by immunohistochemistry. TGF-β1 mRNA expression was examined by real-time fluorescent quantitative PCR. Sixty patients with schistosomal liver fibrosis were divided into treatment group and control group. The patients in treatment group were treated with anluohuaxian tablet in combination with γ-IFN for 6 months. Before and after treatment, the changes of symptoms and signs, liver function, serum liver fibrosis indexes and imaging indexes were observed. The results showed that as compared with infection control group, all forms of treatments relieved the hepatic pathological injury with apparently diminished size of schistosomal egg nodules and decreased percentage of pigmentation （P〈0.05）. Furthermore, the expression of collagen Ⅰ and Ⅲ, TIMP-1, and TGF-β1 mRNA in combined treatment group was significantly decreased as compared with anluohuaxian tablet-treated and γ-IFN-treated groups （P〈0.05）. In the clinical observation, the serum liver fibrosis indexes, the portal vein width as well as the spleen thickness was significantly reduced in treatment group as compared with control group （P〈0.05）. It was concluded that the combined use of anluohuaxian tablet with γ-IFN in schistosomal liver fibrosis could protect liver function, alleviate liver fibrosis, and could be used as a choice in treating patients with schiatosomal liver fibrosis.     

The role of DNA damage repair and Chk2 protein in hyper-radiosensitivity of lung adenocarcinoma A549 cells

To explore the role of the Chk2 protein expression and DNA double strand breaks (DSBs) repair in low dose hyper-radiosensitivity (HRS)/increased radioresistance (IRR) of non-small cell lung cancer,A549 cells were subjected to irradiation at the dosage ranging from 0.05-2 Gy.Clonogenic survival was measured by using fluorescence-activated cell sorting (FACS) plating technique.Percentage of cells in M-phase after low doses of X-irradiation was evaluated by phospho-histone H3-FITC/PI and Western blotting was used to detect protein expression of Chk2 and phospo-Chk2.DNA DSBs repair efficiency was also measured by induction and persistence of γ-H2AX.The results showed that the killing ability of irradiation with A549 cells increased at low conditioning dose below 0.3 Gy.Within the dose of 0.3 to 0.5 Gy,A549 cells showed a certain extent of radiation resistance.And when the dose was more than 0.5 Gy,survival fraction exhibited a negative correlation with the dosage.There was no difference between the 0.1 or 0.2 Gy dosage groups and the un-irradiated group in terms of the percentage of cells in M phase.But in the high dosage group (0.3-1.0 Gy),the percentage of cells in M phase was decreased markedly.In addition,the percentage of cells in M phase began to decrease two hours after irradiation.One hour after irradiation,there was no conspicuous activation of Chk2 kinase in 0.1 or 0.2 Gy group,but when the irradiation dose reached 0.3 Gy or higher,Chk2 kinase started to be activated and the activation level showed no significant difference among high dosage groups (0.4,0.5,1.0 Gy).Within 1 to 6 h,the DNA DSBs repair efficiency was decreased at 0.2 Gy but increased at 0.5 Gy and 1.0 Gy,which was in line with Chk2 activation.We are led to conclude that the mechanism of HRS/IRR in A549 cell line was probably due to early G2/M checkpoint arrest and enhanced DNA DSBs repair.In this regard,Chk2 activation plays a key role in G2/M checkpoint activation.     

Effect of rhBMP-2 and Osteogenic Revulsants on Proliferation and Differentiation of Bone Marrow Stromal Cells in Rats

The effects of recombinant human bone morphogenetic protein-2 （rhBMP-2） and osteogenic revulsants alone or in combination at different time points and in different dosages on proliferation and osteogenesis of bone marrow stromal cells （BMSCs） in SD rats were investigated. Rat BMSCs were cultured in vitro and induced by rhBMP-2 in different dosages （10, 50, 100 and 200μg/L） alone or in combination with osteogenic revulsants. MTT colorimetric assay was used to evaluate The proliferation, activity of alkaline phosphoric （ALP） and osteocalcin were measured at 3rd, 6th, 9th, 12th day respectively. The results showed that rhBMP-2 and osteogenic revulsants could promote the differentiation of BMSCs towards osteoblast phenotype. The proliferation of BMSCs could be enhanced by rhBMP-2 in a dose-dependent manner. The expression of osteoblast phenotype was significantly higher by using both of them than by using them alone, which was verified by the activity of ALP and osteocalcin. It was suggested that the combined use of rhBMP-2 and osteogenic revulsants could promote the proliferation and simultaneously induce and maintain the expression of osteoblast phenotype of BMSCs in rats.     

Anti-tumor effect of pEgr-interferon-γ-endostatin gene-radiotherapy in mice bearing Lewis lung carcinoma and its mechanism

Background Gene-radiotherapy, the combination of gene therapy and radiation therapy, is a new paradigm for cancer treatment. To enhance anti-tumor effect of gene-radiotherapy, in this study we construct a radiationinducible dual-gene co-expression vector pEgr-interferon(IFN)-γ/- endostatin and studied the anti-tumor effect of pEgr-IFN-γ/-endostatin gene-radiotherapy in mice bearing Lewis lung carcinoma and its mechanism.Methods Gene recombinant technique was used to construct dual-gene co-expression plasmid pEgr-IFN-γ endostatin, and single-gene expression plasmid pEgr-IFN-γ and pEgr-endostatin. The plasmids packed by liposome were injected locally into the tumors of the mice, and the tumors were irradiated with 5 Gy X-ray 36 hours later. The tumor growth rate at different time and mean survival period of the mice were observed.Cytotoxic activity of splenic cytotoxic T-lymphocyte ( CTL), natural killer (NK) cell and tumor necrosis factor (TNF)-α secretion activity of peritoneal macrophages of the mice in various groups were evaluated 15 days after irradiation. The intratumor micro-vessel density was evaluated by immunohistochemical staining 10 days after irradiation.Results The tumorgrowthrate of the mice in dual-gene-radiotherapy group was significantly lower than those in control group, 5 Gy group and single-gene-radiotherapy group at different time after gene-radiotherapy, and the mean survival period of which was longer. Cytotoxic activity of splenic CTL, NK and TNF-α secretion activity of peritoneal macrophages of the mice in dual-gene-radiotherapy group were significantly higher than those in control group, 5 Gy X-ray irradiation group and pEgr-endostatin gene-radiotherapy group 15 days after irradiation. The intratumor micro-vessel density of the mice in dual-gene-radiotherapy group was significantly lower than those in control group, 5 Gy X-ray irradiation group and pEgr-IFN-γ/gene-radiotherapy group.Conclusion The anti-tumor effect of dual-gene-radiotherapy was significantly better than that of single-gene-radiotherapy by combining the enhancement of anti-tumor immunologic function induced by IFN-γ/with the antiangiogenesis function of endostatin.     

Isolation and characterization of radiation-resistant lung cancer D6-R cell line

Objective To isolate an isogenic radioresistant cancer cell line after fractioned X-ray radiation and characterize the resistant cells. Methods D6 cells were exposed to repeated X-ray irradiation, and after a total dose of 5200 cGy in 8 fractions, a radioresistant monoclone D6-R was obtained. The radiosensitivity and drug sensitivity of the novel radioresistant D6-R cells, together with their parent D6 cells, were measured using clonogenic assay and MTT assay respectively. Cell cycle distribution was analyzed by flow cytometry. Fluorescence microscopy and flow cytometry were applied for apoptosis detection Comet assay was used for the detection of DNA damage and repair. Results D6-R cells showed higher and broader initial shoulder （D0=2.08 Gy, Dq=1.64 Gy, N=2.20） than the parent D6 cells （D0=1.84 Gy, Dq=0.34 Gy, N=1.20）. They were 1.65-fold more radioresistant than D6 cells in terms of SF2 （63% vs 38%） and were more resistant to ADM （3.15-fold） and 5-FU （3.86-fold） as compared with the latter. It was found that D6-R cells had higher fractions of cells in S phase （53.4% vs 37.8%） and lower fractions of cells in G1 （44.1% vs 57.2%） and G2-M phase （2.5% vs 5%）. There was no difference in radiation-induced apoptosis between D6-R and D6 cells. D6-R cells showed less initial DNA damage and increased capacity in DNA repair after irradiation, as compared with the parent cells. Conclusions D6-R cells have been isolated by exposing the parental D6 cells to repeated irradiation. The difference in cell cycle pattern together with the induction and repair of DNA damage might, at least partially, explain the mechanism of the radioresistance.     

安罗替尼对肺腺癌细胞株A549放射敏感性的影响及机制

  目的  研究安罗替尼对肺腺癌细胞放疗增敏作用及机制。  方法  采用安罗替尼处理人肺腺癌细胞株A549，使用CCK8法测定安罗替尼对细胞增殖的影响；采用克隆形成实验测定安罗替尼联合放疗对细胞的生长抑制作用；使用流式细胞术测定细胞周期和细胞凋亡的变化；采用免疫荧光测定安罗替尼联合放疗对细胞内DNA损伤的影响；采用Western blot检测细胞内DNA损伤标志因子DNA-PKcs的表达变化。  结果  安罗替尼对人肺腺癌细胞A549增殖具有抑制作用，第2、3、4、5天，（P < 0.05）。体外培养克隆形成实验显示，安罗替尼联合放疗组的准予剂量（Dq）、平均致死剂量（D0）及4 Gy照射时的存活分数（SF）均明显低于单纯放疗组（P < 0.05）。安罗替尼能够使细胞阻滞于G1/G0期，与放疗联合作用后，进一步降低了G2和S期细胞比例。安罗替尼能够增加放疗诱导的细胞凋亡比例（31.94±2.25）%和（44.44±2.30）%，（P < 0.001），增加γH2AX阳性细胞数量（25.67±2.52）%和(54.67±3.79）%，（P < 0.001）。安罗替尼能够降低放疗诱导的DNA断裂损伤标志因子DNA-PKcs的表达强度（0.90±0.06）和（0.40±0.06），（P < 0.001）。  结论  安罗替尼具有放疗增敏作用，其机制可能与减少G2/S期细胞、增加细胞凋亡和维持DNA持续损伤有关。     

电离辐射对Jurkat细胞γ-H2AX蛋白表达的影响

目的：探讨电离辐射诱导Jurkat细胞γ-H2AX蛋白表达的影响。方法：采用流式细胞术（FCM）分别检测2.0 Gy X线照射后不同时间点（0、0.5、1.0、4.0、8.0、16.0及24.0 h）和0.5、1.0、2.0、4.0及6.0 Gy不同剂量X线照射后Jurkat细胞γ-H2AX表达变化,并于量效实验同时进行Jurkat细胞凋亡率检测。结果：与假照组比较,2.0 Gy X线照射后Jurkat细胞γ-H2AX表达水平于1.0 h内达最大值,1.0 h后开始呈时间依赖性下降,16.0 h仍高于假照水平（P<0.01）,24.0 h降至与对照无明显差异;不同剂量X线照射后1.0 h,Jurkat细胞γ-H2AX的表达水平在0.5 Gy以内没有明显变化,0.5 Gy以后呈剂量依赖性升高,4.0 Gy时达最高水平（P<0.01）,6.0 Gy时表达略下降;不同剂量X线照射后8.0 h,γ-H2AX表达在0～4.0 Gy范围内随剂量增大而逐渐升高,4.0 Gy时达到最高水平（P<0.01）,6.0 Gy时表达有所下降。结论：X射线能诱导Jurkat细胞γ-H2AX表达增高,在一定范围内存在时间和剂量依赖关系。     

siRNA沉默COX-2基因对胶质瘤细胞放射敏感性的影响

目的 利用小分子RNA(small interfering RNA,siRNA)技术体外沉默人胶质瘤细胞COX-2基因表达,探讨其对放射敏感性的影响,以期为胶质瘤的治疗提供新的思路和方法。 方法 体外培养胶质瘤U251细胞,使用siRNA技术构建U251细胞COX-2基因沉默模型,Western blot检测转染后细胞COX-2蛋白表达情况,筛出最适序列。将实验分为对照组与转染组,分别予以2、4、6、8 Gy四个剂量组予以X线照射,实验重复3次,使用MTT法检测辐射后细胞增殖抑制情况,平板克隆形成实验检测细胞存活分数(SF)并通过单击多靶拟合曲线计算增敏比(SER),流式细胞术检测细胞凋亡情况。 结果 转染组COX-2蛋白表达情况较对照组均下降,其中以siRNA600序列降低最为明显,差异具有统计学意义(P<0.05),后续实验均以siRNA600序列进行转染。辐射后转染组的细胞增殖抑制率为(84.87±3.50)%、(63.62±0.35)%、(55.05±4.87)%、(36.85±3.00)%,较对照组增殖抑制作用明显增强,并随放射剂量增加而增加,差异具有统计学意义(P<0.05)。辐射后的转染组SF低于对照组,且转染组D0为4.110,Dq为1.387,均低于对照组,对照组D0为6.908,Dq为2.772,放射增敏比SER为1.680,差异有统计学意义(P<0.05)。辐射后的转染组细胞凋亡率为(3.63±0.45)%、(6.08±0.87)%、(47.97±2.13)%、(59.56±3.07)%均高于对照组,且在6 Gy、8 Gy照射后升高更为明显。 结论 siRNA技术沉默人胶质瘤U251细胞COX-2基因表达可以提高细胞的放射敏感性,增加了放射后细胞的凋亡率及增殖抑制作用,降低了克隆形成率。      

沉默lncRNA HCP5上调miR-508-3p表达增加胶质瘤细胞的辐射敏感性

目的探讨长链非编码(lnc)RNA HCP5对胶质瘤细胞的辐射敏感性的影响及其机制。方法分别用0、2、4、6、8 Gy射线照射胶质瘤细胞U251和U87,作为不同剂量辐射组;将si-con、si-HCP5、pcDNA、pcDNA-HCP5转染至细胞U251和U87中,分别记为si-con组、si-HCP5组、pcDNA组、pcDNA-HCP5组;将si-con、si-HCP5转染至细胞U251和U87后再用4 Gy射线照射,分别记为IR+si-con组、IR+si-HCP5组,仅用4 Gy射线照射的细胞记为IR组;将si-HCP5分别与anti-miR-con、anti-miR-508-3p共转染至细胞U251和U87后再用4 Gy射线照射,分别记为IR+si-HCP5+anti-miR-con组、IR+si-HCP5+anti-miR-508-3p组,转染均用脂质体法。采用RT-qPCR检测miR-508-3p和HCP5的表达;细胞克隆形成实验检测胶质瘤细胞的放射敏感性;流式细胞术检测细胞凋亡;Western blot检测磷酸化H2AX(γ-H2AX)、裂解半胱氨酸天冬氨酸蛋白酶-3(Cleaved caspase-3)、磷酸化磷脂酰肌醇3激酶(p-PI3K)、磷脂酰肌醇3激酶(PI3K)、磷酸化蛋白激酶B(p-AKT)、蛋白激酶B(AKT)蛋白表达;双荧光素酶报告基因检测实验检测荧光活性。结果放射处理的胶质瘤细胞HCP5高表达,miR-508-3p低表达;沉默HCP5后细胞U251和U87放射敏感性增强,细胞凋亡率升高[U251:(16.67±1.68)%,(3.58±0.62)%,t=21.929,P<0.05;U251:(12.32±1.08)%,(4.48±0.71)%,t=18.198,P<0.05],γ-H2AX[U251:(0.45±0.04),(0.23±0.05),t=10.307,P<0.05;U87:(0.38±0.04),(0.24±0.03),t=8.400,P<0.05]、Cleaved caspase-3[U251:(0.37±0.04),(0.16±0.03),t=12.600,P<0.05;U87:(0.38±0.04),(0.22±0.03),t=9.600,P<0.05]表达水平升高。相比单独沉默HCP5或辐射处理,沉默HCP5同时辐射处理U251细胞,细胞凋亡率[(25.34±1.54)%,(16.67±1.68)%,t=11.413,P<0.05;(25.34±1.54),(11.13±1.06),t=22.802,P<0.05]显著升高,γ-H2AX[(0.69±0.05),(0.45±0.04),t=11.245,P<0.05;(0.69±0.05),(0.31±0.04),t=17.804,P<0.05]、Cleaved caspase-3[(0.52±0.06),(0.37±0.04),t=6.240,P<0.05;(0.52±0.06),(0.34±0.04),t=7.488,P<0.05]表达水平升高。辐射处理后且沉默HCP5后U251和U87细胞中p-PI3K[(0.21±0.02),(0.52±0.04),t=20.795,P<0.05;(0.26±0.23),(0.67±0.07),t=5.116,P<0.05]、p-AKT[(0.22±0.03),(0.66±0.07),t=17.332,P<0.05;(0.23±0.04),(0.71±0.03),t=28.800,P<0.05]表达水平降低。HCP5可靶向调节miR-508-3p表达;干扰miR-508-3p逆转了沉默HCP5和辐射对U251和U87细胞放射的增敏和促进细胞凋亡的作用,降低了γ-H2AX、Cleaved caspase-3表达水平,提高了p-PI3K、p-AKT表达水平。结论沉默lncRNA HCP5可增强胶质瘤细胞的辐射敏感性,促进细胞凋亡,其机制可能与miR-508-3p及PI3K/Akt信号通路有关,可为胶质瘤治疗提供新靶点和新思路。     

ABT737通过延迟宫颈癌细胞放射后DNA损伤修复及诱导凋亡而增敏放疗

【目的】 探讨类似BH-3的小分子物质ABT737诱导增敏放疗的作用及其分子机制?【方法】噻唑蓝法(MTT)检测不同浓度ABT737对HeLa细胞的生长抑制作用;细胞克隆形成实验检测ABT737联合放疗对放疗的增敏作用;免疫荧光法检测γ-H2AX观察DNA损伤修复情况;流式细胞术检测细胞凋亡;免疫印迹法检测Caspase-3?PARP的表达观察凋亡?【结果】与对照组相比,ABT737能显著抑制宫颈癌HeLa细胞的增殖(P < 0.05),并呈浓度依赖性,其IC50为15.7 μmol/L?体外培养克隆形成实验结果显示放疗+ABT737不同用药时间组的DEF值均大于1,放疗+8 μmol/L ABT737持续用药组为1.88,放疗+12 μmol/L ABT737用药72 h组为1.13,细胞存活分数(SF值)持续用药组为0.84,用药72 h组SF值为0.82;免疫荧光结果显示ABT737联合放疗处理HeLa细胞1 h后,放射线导致的γ-H2AX聚焦点数量及有γ-H2AX聚焦点生成的细胞数量均明显增加,上述处理24 h后,单纯放疗组γ-H2AX焦点消失,而联用ABT737处理组仍可观察到γ-H2AX焦点聚集?流式细胞术结果显示,单纯放疗组早期凋亡率(Annexin V+,PI-)为23.3%,ABT737联合放疗可以明显提高放射线诱导的细胞凋亡,早期凋亡率最高达50.3%?免疫印迹结果显示10 ?滋mol/L ABT737与2 Gy放射联合作用于Hela细胞后,凋亡蛋白cleaved Caspase-3与cleaved PARP的表达较单纯放疗组增加?【结论】 ABT737对宫颈癌Hela细胞具有放疗增敏作用,其机制与ABT737可延迟宫颈癌细胞放疗后DNA损伤修复及诱导凋亡有关?     

电离辐射对沉默ATRX的HeLa细胞DNA损伤修复的影响

目的：靶向沉默宫颈癌HeLa细胞中α-地中海贫血/精神发育迟滞综合征X染色相关蛋白（ATRX）,检测电离辐射对ATRX、γH2AX和Rad51蛋白表达及γH2AX和Rad51焦点数的影响,探讨ATRX参与辐射后HeLa细胞DNA损伤修复的作用。方法： 3条ATRX-shRNA和阴性对照（Control-shRNA）的慢病毒载体转染293T细胞,收集慢病毒并感染HeLa细胞,利用puromycin筛选获得稳定沉默ATRX的细胞系,分别命名为shA₁-HeLa、shA₂-HeLa、shA₃-HeLa和shCon-HeLa,采用Western blotting法检测沉默ATRX效率以及电离辐射后ATRX、γH2AX和Rad51蛋白的表达,采用免疫荧光技术观察shCon-HeLa和shA₁-HeLa组中γH2AX和Rad51焦点并计数其数量。结果： shCon-HeLa细胞中可见ATRX蛋白表达,而shA₁-HeLa、shA₂-HeLa和shA₃-HeLa细胞中均无ATRX蛋白表达,表明沉默效率较高。在2和8 Gy剂量照射后1、6和24 h,shCon-HeLa组ATRX蛋白表达量逐渐升高,24 h时表达量最高,且8 Gy照射后1、6和24 h表达量均较高。4 Gy照射后0~6 h,与shCon-HeLa组比较,shA₁-HeLa组γH2AX焦点数在1 h明显升高（P<0.05）,而后逐渐降低,但在6 h焦点数仍明显高于shCon-HeLa组（P<0.01）;Rad51焦点数与γH2AX焦点数变化相一致,与shCon-HeLa组比较,shA₁-HeLa组Rad51焦点数在1 h明显升高（P<0.05）,在6 h时shA₁-HeLa焦点数仍明显高于shCon-HeLa组（P<0.01）。4 Gy照射后0~16 h,shA₁-HeLa组细胞中γH2AX和Rad51蛋白表达量均较shCon-HeLa组增加。结论：成功获得稳定沉默ATRX的HeLa细胞模型,电离辐射可诱导ATRX蛋白表达量增加,且沉默ATRX的HeLa细胞中γH2AX和Rad51焦点数及蛋白表达量均高于对照组,提示ATRX参与了辐射诱导的DNA损伤修复过程。     

塞来昔布对人肝癌细胞株HepG2的放射增敏作用研究

目的探讨COX-2抑制剂塞来昔布对体外培养的HepG2细胞放射增敏作用及其可能的机制,为提高肝癌的放疗效果提供实验依据。方法集落形成法绘制细胞存活曲线,计算增敏比;流式胞仪检测塞来昔布对细胞周期及凋亡的影响;免疫细胞化学染色法检测塞来昔布作用后HepG2细胞的Bcl-2、Casepase-3的表达情况。结果集落形成实验计算得单纯照射组D0=2.57Gy、Dq=2.62Gy,药物＋照射组D0=2.18Gy、Dq=1.89Gy,增敏比SER=1.18。塞来昔布作用48h后,流式细胞仪检测发现细胞周期时相分布发生明显变化,G0/G1期细胞比例增加,S期细胞减少,细胞凋亡率增加。免疫细胞化学染色法观察塞来昔布对凋亡蛋白Bcl-2、Caspase-3表达的影响,发现塞来昔布作用48h后Bcl-2的表达无明显变化,Caspase-3的表达增强。结论塞来昔布具有较强的放射增敏作用,作用机制可能与塞来昔布影响细胞周期的分布,促进细胞凋亡,抑制细胞亚致死性损伤修复有关。     

DNA damage response in resting and proliferating peripheral blood lymphocytes treated by camptothecin or X-ray

DNA damage response (DDR) in different cell cycle status of human peripheral blood lymphocytes (PBLs) and the role of H2AX in DDR were investigated. The PBLs were stimulated into cell cycle with phytohemagglutinin (PHA). The apoptotic ratio and the phosphorylation H2AX (S139) were flow cytometrically measured in resting and proliferating PBLs after treatment with camptothecin (CPT) or X-ray. The expressions of γH2AX, Bcl-2, caspase-3 and caspase-9 were detected by Western blotting. DDR in 293T cells was detected after H2AX was silenced by RNAi method. Our results showed that DNA double strand breaks (DSBs) were both induced in quiescent and proliferating PBLs after CPT or X-ray treatment. The phosphorylation of H2AX and apoptosis were more sensitive in proliferating PBLs compared with quiescent lymphocytes (P<0.05). The expression levels of anti-apoptotic proteins Bcl-2 were reduced and cleaved caspase-3 and caspase-9 were increased. No significant changes were observed in CPT-induced apoptosis in 293T cells between H2AX knocking down group and controls. It was concluded that proliferating PBLs were more vulnerable to DNA damage compared to non-stimulated lymphocytes and had higher apoptosis rates. γH2AX may only serve as a marker of DNA damage but exert no effect on apoptosis regulation.