阿帕替尼对食管鳞癌ECA-109细胞及其干性细胞辐射敏感性的影响及机制探讨

目的 探索阿帕替尼对食管鳞癌ECA-109细胞及其干性细胞辐射敏感性的影响及其分子机制。方法 采用无血清悬浮培养法富集细胞中富含肿瘤干性细胞群的球囊。将ECA-109及其干性细胞分为细胞对照组、单纯药物组、单纯照射组以及药物+照射组。CCK-8法测定细胞增殖的变化,酶联免疫吸附法（ELISA）测定血管内皮生长因子（VEGF）蛋白的浓度,流式细胞术分析细胞周期及凋亡的变化;Western blot法测定细胞中CHK2、P-STAT3蛋白的表达。结果 阿帕替尼作用于ECA-109亲本细胞及干性细胞24、48和72 h后,ECA-109干性细胞的药物半数抑制浓度（IC₅₀）均较其亲本细胞的药物半数抑制浓度（IC₅₀）明显升高（t=8.17、9.29、18.85,P<0.05）,且其细胞抑制表达呈时间-剂量效应关系（亲本细胞：r²=0.94~0.97,P<0.05;干性细胞：r²=0.94~0.98,P<0.05）;不同浓度阿帕替尼（亲本细胞：10和20 μmol/L;干性细胞：30和40 μmol/L）联合不同剂量X射线（6和8 Gy）照射后,ECA-109亲本细胞及干性细胞的增殖抑制率均较单纯照射组明显增强（t=5.20~39.68,P<0.05）。ECA-109亲本细胞及干性细胞的VEGF蛋白水平差异具有统计学意义（t=7.45,P<0.05）,且单纯药物组（20 μmol/L）及药物+照射组（20 μmol/L,6 Gy）处理后,两种细胞VEGF蛋白水平均有所下降,其中亲本细胞差异具有统计学意义（t=14.51、26.40,P<0.05）。药物+照射组ECA-109亲本细胞的G₂/M期及凋亡细胞比例均较细胞对照组增高（t=8.83,11.59,P<0.05）;与细胞对照组（0 μmol/L）比较,单纯药物组的ECA-109亲本细胞CHK2、P-STAT3蛋白的表达水平显著下降（t=3.36、4.10,P<0.05）;与单纯照射组比较,药物+照射组ECA-109亲本细胞CHK2,P-STAT3蛋白的表达水平也显著下降（t=9.05、2.36,P<0.05）。结论 阿帕替尼能增强食管癌ECA-109亲本细胞及其干性细胞的放射敏感性,ECA-109干性细胞放射抵抗的原因可能与干性细胞更高表达VEGF蛋白有关。     

核定位序列修饰的二氧化钛纳米颗粒对胶质瘤U251细胞的放射增敏作用

目的 研究核定位序列（nuclear localization sequence,NLS）修饰的二氧化钛（titanium dioxide,TiO₂）纳米颗粒对胶质瘤U251细胞放射敏感性的作用。方法 合成并表征具有细胞核靶向性的TiO₂-NLS纳米颗粒,分别用纳米颗粒和电离辐射单独或联合处理U251细胞,流式细胞仪检测活性氧（ROS）含量和细胞凋亡率,γ-H2AX焦点（foci）染色检测DNA损伤修复的情况,细胞克隆形成实验检测细胞放射敏感性的改变。结果 NLS修饰可促进TiO₂纳米颗粒进入U251细胞核,与未修饰的TiO₂纳米颗粒相比,TiO₂-NLS纳米颗粒可促进电离辐射诱导的细胞凋亡（t=8.96,P<0.05）,细胞克隆实验显示,TiO₂-BSA纳米颗粒组的放射增敏比为1.18,TiO₂-NLS纳米颗粒处理组的放射增敏比为1.29,两组比较,差异有统计学意义（t=14.72,P<0.05）。结论 具有细胞核靶向性的TiO₂纳米颗粒能够增强胶质瘤U251细胞的放射敏感性。     

阿帕替尼对脑胶质瘤细胞放射敏感性的影响

目的 研究小分子酪氨酸激酶抑制剂甲磺酸阿帕替尼对脑胶质瘤细胞U87MG放射敏感性的影响,并初步探讨其作用机制。方法 将胶质瘤细胞U87MG分为空白对照组、阿帕替尼组、单纯照射组、阿帕替尼联合照射组。CCK-8法检测不同浓度阿帕替尼（5、10、20、40、80 μmol/L）对细胞增殖的影响;创伤愈合实验和侵袭实验检测阿帕替尼对胶质瘤细胞的迁移及侵袭能力的影响;平板克隆实验检测阿帕替尼对脑胶质瘤细胞的放射敏感性的影响;流式细胞术检测细胞凋亡情况;采用Western blot检测Bax、Bcl-2蛋白表达。结果 阿帕替尼对胶质瘤细胞U87MG的增殖具有明显抑制作用,且存在时间-剂量的依赖性。与单纯照射组比较,阿帕替尼联合照射组能明显抑制细胞的增殖、迁移和侵袭,差异有统计学意义（t=9.857、18.704、4.167,P<0.05）。与单纯照射组比较,阿帕替尼联合照射组的D₀、D_q和SF₂均下降,放射增敏比（SER_D0）为1.3。与单纯照射组比较,阿帕替尼联合照射组的细胞凋亡率增加,Bcl-2蛋白表达降低,Bax蛋白表达升高,差异有统计学意义（t=16.187、8.890、5.222,P<0.05）。结论 阿帕替尼能够抑制胶质瘤细胞增殖、迁移和侵袭,并促进细胞凋亡,增加胶质瘤细胞的放射敏感性。     

沉默Rev1基因对人结肠癌细胞放射敏感性的影响

目的 探讨沉默Rev1基因对人高分化结肠癌细胞THC8307 X射线照射后增殖、凋亡的影响。方法 利用RNA干扰技术将Rev1基因的特异性片段转染THC8307细胞,用实时荧光定量PCR和Western blot检测转染后细胞中目的基因的表达;实验分空白对照组、阴性对照组、Rev1 siRNA组。分别给予0、6 Gy X射线照射,运用四甲基偶氮唑盐（MTT）法检测不同时段（0、24、48、72、96 h）细胞增殖情况,并绘制增殖曲线;流式细胞仪（FCM）检测不同剂量X射线处理后的细胞凋亡;Western blot检测各组PCNA、γ-H2AX、P53、Bax、Bcl-2蛋白的表达。结果 与空白对照组相比,6 Gy X射线照射后,沉默Rev1基因组细胞增殖速率明显降低（t=7.53,P<0.05）,凋亡明显增加（t=6.23,P<0.05）,增殖细胞抗原（PCNA）表达下降（t=4.39,P<0.05）,γ-H2AX表达升高（t=5.48,P<0.05）,P53表达升高（t=5.09,P<0.05）、Bax表达升高（t=3.32,P<0.05）、Bcl-2表达降低（t=6.13,P<0.05）。结论 沉默Rev1基因,抑制了X射线作用下的结肠癌细胞THC8307的增殖,促进了凋亡,增加了其对X射线的放射敏感性。     

渥曼青霉素对胶质瘤细胞U251的辐射增敏作用

目的 利用渥曼青霉素（wortmannin,WM）抑制人恶性胶质瘤细胞U251磷脂酰肌醇-3-激酶（PI3K）通路的活性,探讨对U251细胞辐射敏感性的影响及可能的作用机制。方法 采用10 μmol/L WM预处理U251 2 h,并接受10 Gy X射线照射,检测PI3K/Akt信号通路的活性、集落形成率和凋亡的变化;通过Western blot方法检测凋亡相关蛋白活化型Caspase-3、Bax、Bcl-2及XIAP表达的变化。结果 10 μmol/L WM预处理2 h,明显抑制了U251细胞phospho-Akt的表达（t=0.000 1,P<0.01）。WM预处理联合X射线照射后,U251细胞的凋亡率由对照组和单纯照射组的（2.14±1.32）%和（11.5±2.9）%增加到（22.6±3.8）%,差异具有统计学意义（t=0.009 3、0.002 7,P<0.01）;集落形成率由对照组和单纯照射组的（88.54±4.76）%和（56.31±4.05）%降低到（12.25±9.59）%（t=0.000 03、0.000 2,P<0.01）;同时伴随着凋亡相关蛋白活化型Caspase-3表达显著增加,Bax/Bcl-2的比值明显增高以及XIAP的显著降低。结论 WM通过抑制PI3K/Akt信号通路活性,增加凋亡蛋白Caspase-3的活化和Bax/Bcl-2比值,下调凋亡抑制蛋白XIAP来增强恶性胶质瘤细胞的辐射敏感性。     

DNA依赖蛋白激酶催化亚基抑制剂NU7026对结肠癌HCT116癌干细胞的放射增敏作用

目的 以结肠癌细胞HCT116为研究对象,评价DNA依赖蛋白激酶催化亚基(DNA-PKcs)抑制剂NU7026对癌干细胞的放射增敏作用及其机制。方法 以CD133+/CD44+为标志物,流式细胞术检测癌干细胞亚群。将HCT116细胞分为对照组、单纯药物(20 μmol/L NU7026)组、单纯照射(2 Gy γ射线)组和药物+照射(20 μmol/L NU7026联合2 Gy γ射线)组,照射前2 h加入NU7026。细胞集落形成实验检测HCT116细胞增殖,流式细胞术检测细胞周期和凋亡, γ-H2AX foci的免疫荧光激光共聚焦分析DNA双链断裂损伤修复。结果 体外培养HCT116细胞中CD133+/CD44+癌干细胞亚群比例高达(88.14±0.47)%,HCT116细胞低密度接种无血清培养基中集落形成率为(84.75±1.35)%。与单纯照射组比较,药物+照射组细胞存活率显著降低(t=7.22,P<0.01)。受照后48 h,药物+照射组的癌干细胞亚群比例较单纯照射组显著降低(t=9.55,P<0.01)。受照后24 h,NU7026明显增加G₂/M期阻滞(t=7.67,P<0.01),48 h细胞早期凋亡发生率也明显增加(t=8.24,P<0.05)。药物+照射组在照后2、4、8和24 h DNA双链断裂(γ-H2AX foci)残留比单纯照射组明显增多(t=19.58、11.95、7.01和9.45,P<0.01)。结论 NU7026对癌干细胞为优势亚群的结肠癌HCT116细胞具有明显的放射增敏作用,显著增加对癌干细胞的杀伤效应,增敏机制包括抑制DNA修复,诱发不可逆G₂/M期阻滞和增加细胞凋亡。     

食管癌干细胞辐射抗性与相关蛋白表达的研究

目的 探讨NS398联合X射线照射对食管癌干细胞和贴壁肿瘤细胞辐射增敏效应的差异,并分析食管癌干细胞的辐射抗性及其与相关蛋白表达的关系。方法 采用无血清培养基分离细胞系ECA109的食管癌干细胞;流式细胞仪检测细胞表面标记物CD44+和CD271+的表达;四甲基偶氮唑盐比色法(MTT)检测NS398联合不同照射剂量(0、4和8 Gy)对细胞增殖能力作用的联合效应;克隆形成实验检测NS398对亲本细胞和细胞球辐射增敏效应的差异;Western blot检测细胞内4种相关蛋白的表达水平。结果 在无血清培养基中可分离培养稳定传代的肿瘤干性细胞球。细胞球CD271+的表达高于亲本细胞(t=3.81,P<0.05)。照射后细胞球增殖能力大于亲本细胞。NS398联合照射时,亲本细胞的存活分数(SF₂)小于细胞球(t=2.91,P<0.05),NS398对亲本细胞的SER大于细胞球。细胞球内Bmi-1、c-Myc、β-catenin和CyclinD1的表达水平较亲本细胞均升高(t=8.09、7.90、7.50、7.15,P<0.05);4 Gy照射后细胞内CyclinD1的表达水平均升高(t=9.74、6.67,P<0.05);NS398联合4 Gy照射组与4 Gy照射组相比,亲本细胞β-catenin和CyclinD1表达水平降低(t=10.15、12.12,P<0.05),细胞球β-catenin和Cyclin D1表达水平亦降低(t=3.23、7.45,P<0.05)。结论 无血清培养基分离培养的食管癌干细胞高表达干细胞表面标记物CD271和干细胞相关蛋白,并具有辐射抗性,其机制可能与β-catenin分子及其下游靶蛋白的表达水平有关。     

电离辐射对皮肤细胞铁死亡的影响及其抑制剂Ferrostatin-1的防护作用研究

目的 探讨电离辐射对皮肤细胞铁死亡的影响以及铁死亡抑制剂Ferrostatin-1（Fer-1）对受照射皮肤细胞的保护作用及机制。方法 为检测Fer-1对人永生化角质形成细胞（HaCaT）辐照后的影响,按照射与给药方式分为对照组、Fer-1组、单纯照射组、照射+Fer-1组。采用CCK-8法和乳酸脱氢酶（LDH）释放检测X射线照射以及Fer-1处理对HaCaT细胞存活和细胞死亡的影响。采用流式细胞术检测X射线照射以及Fer-1处理后对HaCaT细胞脂质过氧化水平的影响。利用结晶紫染色法检测X射线照射以及Fer-1处理对HaCaT细胞克隆形成能力的影响。Western blot检测X射线照射以及Fer-1处理对铁死亡相关蛋白ACSL4和GPX4表达的影响。结果 单纯照射组经不同剂量的X射线照射后细胞存活率明显降低（t=5.63、8.74,P<0.05）,LDH的释放明显增加（t=3.98、5.08、9.27,P<0.05）,Fer-1能够提高受照射皮肤细胞存活率（t=5.79,P<0.05）,降低LDH的释放量（t=12.36、11.96、18.13、9.96,P<0.05）。单纯照射组经10 Gy的X射线照射后细胞的脂质过氧化水平明显升高（t=9.59,P<0.05）,克隆存活能力明显减弱（t=4.26,P<0.05）,而Fer-1能够降低X射线照射引起的脂质过氧化水平的升高（t=6.48、17.04,P<0.05）,增加受照射皮肤细胞的克隆存活能力（t=3.96,P<0.05）。10 Gy的X射线照射会导致ACSL4表达水平的升高和GPX4的表达水平的降低,而Fer-1的治疗能促进ACSL4和GPX4的表达水平恢复正常（t=5.23、7.16、4.78、8.29、6.43,P<0.05）。结论 铁死亡抑制剂Fer-1在细胞水平上能够通过抑制电离辐射后铁死亡的发生而保护皮肤细胞,为放射性皮肤损伤的防护提供了一种新的策略。     

过表达脑源性神经营养因子的神经干细胞移植对受照海马内神经营养因子的影响

目的 探讨过表达脑源性神经营养因子（BDNF）的神经干细胞（NSCs）移植入放射性脑损伤大鼠模型后,对海马内神经营养因子水平及小胶质细胞活化的影响。方法 从胎鼠脑中分离海马神经干细胞并进行培养。选用绿色荧光蛋白（GFP）-慢病毒、GFP-BDNF-慢病毒感染神经干细胞。将SD大鼠按随机数表法分为4组：健康对照组、单纯照射组（R组）、照射后GFP修饰的神经干细胞移植组（R+NSCs组）、照射后GFP-BDNF修饰的神经干细胞移植组（R+BDNF-NSCs组）。全脑单次20 Gy照射后1个月将神经干细胞移植入大鼠双侧海马内。移植后2和8周检测海马组织中BDNF、胶质源性神经营养因子（GDNF）、神经生长因子（NGF）的表达情况;免疫荧光染色观察小胶质细胞活化情况。结果 移植后2和8周时,与R组相比,R+BDNF-NSCs组海马组织中BDNF、NGF蛋白表达均水平明显增高（P<0.05）;移植后8周R+NSCs组和R+BDNF-NSCs组活化的小胶质细胞与R组相比并未显著减少（P>0.05）。结论 过表达BDNF的神经干细胞移植后促进BDNF、NGF的产生,增加了辐射暴露后的海马内神经营养因子水平。     

FOXO4-DRI多肽增加非小细胞肺癌细胞放射敏感性研究

目的 探讨FOXO4-DRI多肽对非小细胞肺癌（NSCLC）细胞放射敏感性的影响。方法 为检测FOXO4-DRI对NSCLC细胞的影响,将H460和A549细胞按照射与给药方式分为对照组、FOXO4-DRI组、单纯照射组、照射+FOXO4-DRI组。采用剂量率为0.99 Gy/min γ射线单次照射,在照射前10 min对H460细胞给予FOXO4-DRI 6 μmol/L,A549细胞给予FOXO4-DRI 30 μmol/L。采用CCK-8法检测照射后24、48和72 h细胞存活率;用结晶紫染色法检测细胞克隆形成数目;用伤口愈合实验检测细胞迁移程度;用流式细胞术检测细胞凋亡和细胞周期的改变。结果 与对照组相比,FOXO4-DRI组H460细胞和A549细胞存活率降低（t=1.06~50.75,P<0.05）、迁移率降低（t=33.37~139.10,P<0.05）,克隆形成数目减少（t=5.20~93.48,P<0.05）。FOXO4-DRI诱导了细胞凋亡（t=2.95~42.00,P<0.05）,导致G₀/G₁细胞周期阻滞以及G₂/M期细胞比例下降（t=3.50~31.59,P<0.05）。与照射组相比,FOXO4-DRI可进一步降低辐照后的细胞存活率（t=2.94~23.40,P<0.05）,减少辐照后克隆形成数目（t=8.43~34.00,P<0.05）和细胞迁移率（t=5.25、7.56,P<0.05）,增加细胞凋亡（t=9.20~11.52,P<0.05）。照射+FOXO4-DRI组细胞,G₂/M期细胞比例进一步下降,S期细胞增加（t=3.85~17.62,P<0.05）。结论 FOXO4-DRI多肽通过促进细胞凋亡,降低细胞增殖能力和迁移率,可以提高NSCLC细胞放射敏感性。     

Genomic instability induced in distant progeny of bystander cells depends on the connexins expressed in the irradiated cells

Abstract

Purpose: To examine the time window during which intercellular signaling though gap junctions mediates non-targeted (bystander) effects induced by moderate doses of ionizing radiation; and to investigate the impact of gap junction communication on genomic instability in distant progeny of bystander cells.

Materials and methods: A layered cell culture system was developed to investigate the propagation of harmful effects from irradiated normal or tumor cells that express specific connexins to contiguous bystander normal human fibroblasts. Irradiated cells were exposed to moderate mean absorbed doses from 3.7?MeV α particle, 1000?MeV/u iron ions, 600?MeV/u silicon ions, or ¹³⁷Cs γ rays. Following 5?h of co-culture, pure populations of bystander cells, unexposed to secondary radiation, were isolated and DNA damage and oxidative stress was assessed in them and in their distant progeny (20–25 population doublings).

Results: Increased frequency of micronucleus formation and enhanced oxidative changes were observed in bystander cells co-cultured with confluent cells exposed to either sparsely ionizing (¹³⁷Cs γ rays) or densely ionizing (α particles, energetic iron or silicon ions) radiations. The irradiated cells propagated signals leading to biological changes in bystander cells within 1?h of irradiation, and the effect required cellular coupling by gap junctions. Notably, the distant progeny of isolated bystander cells also exhibited increased levels of spontaneous micronuclei. This effect was dependent on the type of junctional channels that coupled the irradiated donor cells with the bystander cells. Previous work showed that gap junctions composed of connexin26 (Cx26) or connexin43 (Cx43) mediate toxic bystander effects within 5?h of co-culture, whereas gap junctions composed of connexin32 (Cx32) mediate protective effects. In contrast, the long-term progeny of bystander cells expressing Cx26 or Cx43 did not display elevated DNA damage, whereas those coupled by Cx32 had enhanced DNA damage.

Conclusions: In response to moderate doses from either sparsely or densely ionizing radiations, toxic and protective effects are rapidly communicated to bystander cells through gap junctions. We infer that bystander cells damaged by the initial co-culture (expressing Cx26 or Cx43) die or undergo proliferative arrest, but that the bystander cells that were initially protected (expressing Cx32) express DNA damage upon sequential passaging. Together, the results inform the roles that intercellular communication play under stress conditions, and aid assessment of the health risks of exposure to ionizing radiation. Identification of the communicated molecules may enhance the efficacy of radiotherapy and help attenuate its debilitating side-effects.     

Irradiated human endothelial progenitor cells induce bystander killing in human non-small cell lung and pancreatic cancer cells

Purpose To investigate whether irradiated human endothelial progenitor cells (hEPC) could induce bystander killing in the A549 non-small cell lung cancer (NSCLC) cells and help explain the improved radiation-induced tumor cures observed in A549 tumor xenografts co-injected with hEPC.

Materials and methods We investigated whether co-injection of CBM3 hEPC with A549 NSCLC cells would alter tumor xenograft growth rate or tumor cure after a single dose of 0 or 5?Gy of X-rays. We then utilized dual chamber Transwell dishes, to test whether medium from irradiated CBM3 and CBM4 hEPC would induce bystander cell killing in A549 cells, and as an additional control, in human pancreatic cancer MIA PaCa-2 cells. The CBM3 and CBM4 hEPC were plated into the upper Transwell chamber and the A549 or MIA PaCa-2 cells were plated in the lower Transwell chamber. The top inserts with the CBM3 or CBM4 hEPC cells were subsequently removed, irradiated, and then placed back into the Transwell dish for 3?h to allow for diffusion of any potential bystander factors from the irradiated hEPC in the upper chamber through the permeable membrane to the unirradiated cancer cells in the lower chamber. After the 3?h incubation, the cancer cells were re-plated for clonogenic survival.

Results We found that co-injection of CBM3 hEPC with A549 NSCLC cells significantly increased the tumor growth rate compared to A549 cells alone, but paradoxically also increased A549 tumor cure after a single dose of 5?Gy of X-rays (p?p?p?p?Conclusions These data provide evidence that irradiated hEPC can induce strong bystander killing in A549 and MIA PaCa-2 human cancer cells and that this bystander killing is mediated by the cytokines TNF-α and TGF-β.     

乏氧辐射诱导人肝癌细胞HepG2的旁效应

目的 研究乏氧条件下辐射诱导人肝癌细胞 HepG2的旁效应及其发生机制。方法 采用条件培养基和细胞共培养两种方式,研究细胞在乏氧条件下经X线照射后对未照射旁细胞的影响。结果 乏氧可以显著降低细胞的直接辐射损伤效应,即微核的产生。 HepG2细胞微核率的氧增比约为1.6。无论是有氧还是乏氧条件下,受辐射细胞均可引起未受照射旁细胞微核率的显著增高,且旁效应程度基本相当,与辐射剂量也存在一定的相关性。另外,活性氧自由基(ROS)清除剂二甲基亚砜(DMSO)和iNOS抑制剂氨基胍(AG)均可显著降低乏氧条件下辐射旁效应引起的细胞微核率,DMSO的降低率为42.2%~46.7%,AG的降低率为42%。结论 ROS和NO及其下游信号因子在HepG2细胞乏氧辐射旁效应中具有重要作用。     

131I标记抗表皮生长因子受体抗体靶向性纳米载体治疗胶质母细胞瘤的可行性实验研究

目的 构建¹³¹I标记抗表皮生长因子受体抗体(antiEGFR)靶向性的纳米载体,探讨其在细胞水平和动物体内用于胶质瘤治疗的可行性。方法 制备放射性碘(¹³¹I)标记的antiEGFR靶向性的纳米载体牛血清白蛋白聚己内酯复合物¹³¹I-antiEGFR-BSA-PCL。用共聚焦显微镜观察纳米载体能够与肿瘤细胞结合情况,用MTT法检测纳米载体的细胞毒性作用,摄碘率实验检测肿瘤细胞对放射性纳米载体的摄取。制备裸鼠种植瘤模型,通过瘤体内注射给药,观察裸鼠种植瘤的体积变化,通过SPECT显像观察药物在裸鼠体内的停留情况,并分析纳米载体在裸鼠体内的分布情况。结果 成功地制备了BSA-PCL及antiEGFR-BSA-PCL纳米载体。与BSA-PCL相比,antiEGFR-BSA-PCL更容易与肿瘤细胞结合。当放射性纳米载体的放射性活度达到0.925 MBq时,U251和U87细胞的生长抑制率¹³¹I-antiEGFR-BSA-PCL组均高于¹³¹I-BSA-PCL组(t=2.517、2.821,P<0.05),且均高于同组其他剂量(U251:t=2.148、2.693,P<0.05;U87:t=2.436、2.615,P<0.05)。裸鼠体内实验发现两种纳米载体瘤体内注射后均经过肝脏代谢。¹³¹I-antiEGFR-BSA-PCL组荷瘤裸鼠的种植瘤体积较¹³¹I-BSA-PCL组缩小更多(t=4.115,P<0.05)。结论 ¹³¹I-antiEGFR-BSA-PCL在体内外实验中均能够抑制胶质瘤生长,为胶质瘤的治疗和预后评估提供了一种新方法。     

嗅鞘细胞对脊髓源性神经干细胞分化的影响

目的 探讨嗅鞘细胞对脊髓源性神经干细胞分化的作用。方法 应用Millicell插入式细胞培养皿，大鼠脊髓源性神经干细胞与嗅鞘细胞在无血清培养液中共培养，通过免疫化学染色方法，检测脊髓源性神经干细胞分化为神经元、星形胶质细胞和少突胶质细胞的比例。结果 共培养7d后，脊髓源性神经干细胞分化为神经元的比例高达43．5％，明显高于对照组的21．4％。结论 嗅鞘细胞提供的微环境可促进脊髓源性神经干细胞分化为神经元。     

CD44+/CD24+宫颈癌细胞和耐辐射宫颈癌细胞特性研究

目的 探讨放疗抵抗的宫颈癌细胞特性,揭示宫颈癌复发和转移的机制。方法 用多次分割照射获得耐辐射的宫颈鳞状细胞癌Siha细胞,利用流式细胞仪从宫颈鳞癌的亲代细胞中分选获得CD44+/CD24+宫颈鳞癌细胞。将耐辐射的宫颈鳞癌细胞和CD44+/CD24+宫颈鳞癌细胞设为实验组,亲代宫颈鳞癌细胞设为对照组,分别进行克隆形成实验和肿瘤移植瘤实验,评估实验组细胞是否具备肿瘤干细胞特性。通过Transwell侵袭实验研究实验组及对照组细胞侵袭和转移能力的差异。利用RT-PCR和Western blot检测实验组及对照组细胞OCT-4、Survivin、ABCG2和bcl-2 mRNA的表达,以及与肿瘤转移相关的E-cadherin和vimentin蛋白表达。结果 辐射抵抗的宫颈鳞癌细胞和CD44+/CD24+宫颈鳞癌细胞较亲代宫颈癌细胞高表达抗凋亡蛋白Bcl-2（t=205.26、198.17,P<0.05）和凋亡抑制蛋白survivin（t=896.62、765.34,P<0.05）,并表达肿瘤干细胞相关标志物OCT-4和ABCG2（t=92.13、81.26、220.45、216.32,P<0.05）。两组细胞均具有较强的致瘤能力以及侵袭和转移能力,且表现出E-cadherin下调和vimentin蛋白上调的EMT相关的分子表型变化。结论 放射抵抗的宫颈鳞癌细胞与CD44+/CD24+宫颈鳞癌细胞表现出相同的肿瘤干细胞特性,经历了上皮间质转化过程,放射可以富集宫颈癌干细胞。     

The effect of growth architecture on the induction and decay of bleomycin and X-ray-induced bystander response and genomic instability in lung adenocarcinoma cells and blood lymphocytes

Abstract

Purpose: Cancer patients treated with radiomimetic drug bleomycin (BLM) have shown incidence of 7% second malignancy. Studies regarding BLM-induced genomic instability in bystander cells are scarce, and experiments with cells grown on three-dimensional (3D) cultures to mimic the in-vivo condition have never been attempted.

Materials and methods: A549 and NCI-H23 (human lung adenocarcinoma) cells were grown as 3D cultures using Cytomatrix^?, exposed to BLM or X-radiation and co-cultured with their respective unexposed cells. The DNA damage in direct and bystander cells were assessed by the induction of micronuclei (MN) or phosphorylated serine-15 residue in protein 53 (p53^ser-15), a reflection of DNA damage, and by up-regulation of protein 21 (p21Waf1). The persistence of DNA damage was measured using MN assay and fluorescence in situ hybridization (FISH) in cancer cells and human peripheral blood lymphocytes (PBL) respectively.

Results: BLM or X-irradiation induced DNA damage in both A549 and NCI-H23 cells and their respective bystander cells grown in 2D or 3D cultures. Further persistence of these damages in bystander PBL at delayed times indicated genomic instability in these cells.

Conclusion: BLM-induced genomic instability in the progeny of bystander cells and their significance in therapy-induced second malignancy may not be eliminated completely.     

Increased susceptibility to delayed genetic effects of low dose X-irradiation in DNA repair deficient cells

Abstract

Purpose: To examine whether the levels of micronuclei induction, as a marker for genomic instability in the progeny of X-irradiated cells, correlates with DNA repair function.

Materials and methods: Two repair deficient cell lines (X-ray repair cross-complementing 1 [XRCC1] deficient cell line [EM9] and X-ray repair cross complementing 5 [XRCC5; Ku80] deficient X-ray sensitive Chinese hamster ovary [CHO] cell line [xrs5]) were used in addition to wild-type CHO cells. These cells were irradiated with low doses of X-rays (up to 1 Gy). Seven days after irradiation, micronuclei formed in binucleated cells were counted. To assess the contribution of the bystander effect micronuclei induction was measured in progeny of non-irradiated cells co-cultured with cells that had been irradiated with 1Gy.

Results: The delayed induction of micronuclei in 1 Gy-irradiated cells was observed in normal CHO and EM9 but not in xrs5. In the clone analysis, progenies of xrs5 under bystander conditions showed significantly higher levels of micronuclei, while CHO and EM9 did not.

Conclusion: Genomic instability induced by X-irradiation is associated with DSB (double-strand break) repair, even at low doses. It is also suggested that bystander signals, which lead to genomic instability, may be enhanced when DSB repair is compromised.     

Bystander effect in tumor cells produced by Iodine-125 labeled human lymphocytes

Abstract

Purpose: To investigate the ability of human lymphocytes labeled with DNA-incorporated ¹²⁵I to exert an inhibitory (antiproliferative) bystander effect on co-cultured human colon adenocarcinoma LS174T cells in vitro.

Materials and methods: Human peripheral blood lymphocytes were stimulated to synthesize DNA in the presence of phytohemagglutinin (PHA) and labeled with 5-[¹²⁵I]iodo-2′-deoxyuridine. Human colon adenocarcinoma LS174T cells were co-cultured with the ¹²⁵I-labeled lymphocytes in various ratios for 5 days and the proliferation of the LS174T cells was assessed. Further, the supernatant media from these co-cultures were: (i) Transferred to LS174T cells and their proliferation measured after 5 days, (ii) used to assess the clonogenic survival of LS174T cells, and (iii) screened for factors that suppress growth.

Results: A significant reduction in the proliferation of LS174T cells was observed when co-cultured either with ¹²⁵I-labeled lymphocytes (56?±?3.5%) or the supernatant media (52.5?±?1.3%) obtained from these co-cultures. Clonogenic survival of LS174T cells grown in the supernatant media corroborated the decrease in tumor cell growth.

Conclusion: The observed reduction in the proliferation of LS174T cells in presence of ¹²⁵I-labeled lymphocytes or media obtained from such co-cultures can be attributed to an inhibitory (antiproliferative) bystander effect, probably mediated by factor(s) released from the dying ¹²⁵I-labeled lymphocytes.