射线照射对胰腺癌细胞凋亡及bcl-2、bax基因表达的影响

目的研究不同剂量的γ射线对人胰腺癌细胞凋亡及bcl2,bax基因表达的影响。方法利用不同剂量的γ射线对体外培养的胰腺癌Panc1细胞进行照射,采用PI和AnnexinⅤPI法定量检测细胞凋亡,流式细胞仪检测照射后胰腺癌细胞Panc1的Bcl2、Bax基因表达水平。结果胰腺癌panc1细胞凋亡百分率在一定剂量范围内(≤15Gy)随着照射剂量的提高而增大,在一定时间范围内(≤24h),随着时间的延长而增大。照射组细胞凋亡相关基因Bcl2表达较对照组明显降低,两组相比差异有统计学意义(P<005);照射组bax基因的表达较对照组明显升高,两组相比差异有统计学意义(P<005)。结论γ射线诱导胰腺癌panc1细胞凋亡具有剂量依赖性和时间相关性,bcl2和bax在胰腺癌细胞凋亡调节过程中起着重要作用,不同剂量γ射线照射胰腺癌细胞时Bcl2和Bax表达水平也不相同,通过降低bcl2的表达及提高bax表达来诱导胰腺癌细胞发生凋亡有可能是γ射线杀伤肿瘤细胞的机制之一。     

异鼠李素对人肺癌细胞抑制作用的观察

目的研究异鼠李素对人肺癌YTLMC-90细胞的抑制作用并探讨其作用机制。方法采用细胞生长、克隆形成和^3H—TdR掺入实验,流式细胞术等方法研究异鼠李素对、YTLMC-90细胞增殖和凋亡的作用及其分子机制。结果异鼠李素抑制YTLMC-90细胞的生长和增殖,诱导凋亡,使bcl-2,c—myc、H—ras癌基因表达下降,增强bax、c—fos基因表达。结论异鼠李素可能通过下调bcl-2、c-myc、H-ras基因的表达,增强bax、c—fos基因表达来达到抑制YTLMC-90细胞增殖和生长,诱导凋亡和分化。     

125I粒子对前列腺癌PC-3移植瘤bcl-2、bax基因表达和细胞凋亡的影响

目的 探讨125I粒子持续低剂量率照射对前列腺癌PC-3移植瘤bel-2、bax基因表达和细胞凋亡的影响.方法 利用2枚37 MBq 125I粒子模型对前列腺癌PC-3移植瘤裸鼠进行48,96和192 h照射,用免疫组织化学方法分析bcl-2和bax基因表达情况.用原位末端标记(TUNEL)法检测凋亡率.凋亡率和bax/bcl-2比值之间的相关性采用线性相关分析.统计学处理采用SPSS 11.0软件.结果 125I粒子持续低剂量率照射48 h后bcl-2表达下降到4.00±2.00,与对照组比较差异无统计学意义(t=2.500,P=0.067);96和192 h后bcl-2表达分别下降到2.67±1.16和3.00±1.00,与对照组比较差异有统计学意义(t=4.950,3.464;P=0.008,0.026).bax表达分别上升到11.33±2.89,8.67±1.16和8.67±1.16,与对照组比较差异有统计学意义(t=3.334,4.025,5.292;P值分别为0.029,0.016和0.006).125I粒子持续低剂量率照射48 h组PC-3细胞凋亡率为22.3%,与对照组比较差异无统计学意义(P=0.404);照射96和192 h组凋亡率增加到21.7%和30.7%,与对照组比较差异有统计学意义(P=0.016,0.036).各照射组之间凋亡率差异无统计学意义(P＞0.05).125I粒子持续低剂量率照射Pc-3细胞凋亡率和bax/bcl-2比值呈正相关(r=0.784,P=0.012).结论 125I粒子持续低剂量率照射可使PC-3细胞bcl-2表达下降,bax表达上升,诱导凋亡增加,而凋亡率与bax/bcl-2比值呈正相关.125I粒子对肿瘤细胞的抑制可能通过bcl-2、bax途径诱导细胞凋亡而发挥作用.     

β辐射致大鼠血管平滑肌细胞凋亡的研究

目的 观察放射性核素^188Re辐射对平滑肌细胞凋亡的影响及其机制，探讨辐射所致平滑肌细胞凋亡在预防再狭窄中的作用。方法 ^188Re进行培养平滑肌细胞的内辐射。通过台盼蓝染色计数、流式细胞术、JAM法DNA碎裂量测定、透射电镜及免疫细胞化学检测等方法，研究辐射后平滑肌细胞的存活率、细胞凋亡率、DNA断裂量、细胞超微结构改变及相关基因表达。结果 放射性浓度＜2.96GBq/L辐射，平滑肌细胞存活率、细胞凋亡率、DNA断裂量及细胞超微结构等未发生明显改变；高剂量辐射下（放射性浓度＞2.96GBq/L），平滑肌细胞存活率显著下降，细胞凋亡率明显上升，细胞DNA断裂量增加，细胞超微结构明显破坏。辐射诱导细胞凋亡过程中，p53、bax表达上调，bcl-2/bax比值下调。结论 能够明显抑制平滑肌细胞增殖的低剂量辐射对细胞存活及细胞凋亡无明显影响，未见细胞超微结构改变及DNA的严重破坏；吸收剂量大于20Gy可导致平滑肌细胞大量凋亡；相关基因p53、bcl-2及bax参与调控辐射诱导细胞凋亡过程。低剂量及低剂量率辐射既能有效抑制细胞增殖，又不明显损伤细胞存活，是临床血管内放射治疗预防再狭窄的理想方法。     

高效反义STAT3对A549细胞辐射敏感性的影响

目的 探讨高效反义STAT3转染肺腺癌A549细胞后,肿瘤细胞辐射敏感性的变化,为提高恶性肿瘤的辐射敏感性提供新的探索思路和途径。方法 用自行设计成功的高效反义STAT3(AS10)转染A549细胞后,以不同剂量γ射线照射,通过CCK-8试剂盒检测细胞增殖变化,Hoechst 33258染色对细胞凋亡作形态学上的观察;用Annexin V/PI复染,流式细胞仪检测细胞早期凋亡率的变化;Western blot检测STAT3蛋白表达及磷酸化变化情况,以及其下游基因表达变化情况。结果高效反义STAT3(AS10)转染后,加以γ射线照射,A549细胞的增殖相比于单独作用组受到明显抑制,细胞早期凋亡水平也增加,STAT3蛋白及其下游Bcl-Xl、Cyclin D1蛋白表达变化明显下降,STAT3蛋白磷酸化水平也降低。结论 反义STAT3(AS10)联合γ射线对A549细胞的增殖抑制和诱导凋亡作用明显增强,提高了A549细胞的辐射敏感性;表明阻断STAT3蛋白表达可能成为一种新的提高肿瘤辐射敏感性的有效手段。     

Egr-1启动子基因调控FLT3配基基因表达的实验研究

目的　探索辐射诱导基因调控元件启动的造血生长因子表达及其对造血的保护作用。方法　本实验将携带Egr 1调控序列的FLT3配基 (FL)和EGFP基因双顺反子载体 (Egr EF)转染骨髓基质细胞系HFCL ,采用流式细胞仪、RT PCR、ELISA及细胞增殖法等观察细胞受照后Egr 1调控元件诱导的FL表达及促进造血细胞的增殖作用。 结果　在转染细胞HFCL/EF细胞中证实有外源性基因的整合和表达 ,在 2 5Gy辐射后 16h的细胞培养上清液中表明FL含量较照射前明显增高 ((P <0 0 1) ,) ;辐射后 10dHFCL/EF培养上清液对CD34 造血祖细胞的作用较辐射前具有明显的扩增作用 ((P <0 0 1) ,)。结论　在辐射后Egr 1启动子调控的FL基因表达明显增高并具有保护造血作用。     

Egr-1启动子调控的造血因子基因疗法对SCID小鼠辐射防护的初步探讨

目的 探讨辐射诱导启动子调控的造血因子基因表达对照射后造血保护的作用。方法 将构建的携带有Egr-1启动子的Flt3配基（FL）cDNA和增强型绿色荧光蛋白（EGFP）cDNA双顺反子表达载体导入基质细胞后，联合人CD34^ 细胞输入经亚致死剂量照射的重症联合免疫缺陷（SCID）小鼠体内，观察外周血象动态改变和人造血细胞及其基质细胞植入的变化。结果 实验组与对照组相比外周血白细胞下降幅度明显减轻，恢复加快，骨髓可见绿色荧光阳性的基质细胞，而各组间骨髓中CD45^ 细胞、CD34^ 细胞、CFU－GM及骨髓有核细胞计数差异无显著性。结论 Egr-1启动子调控的造血因子基因疗法具有一定的辐射造血保护作用。     

反义STAT3寡核苷酸对B16细胞辐射敏感性的研究

目的 探讨反义STAT3转染鼠恶性黑色素瘤B16细胞后,肿瘤细胞辐射敏感性的变化。方法 利用反义寡核苷酸转染B16细胞后,以不同剂量γ射线照射。通过CCK-8试剂盒检测细胞增殖变化,Hoechst33258染色对细胞凋亡作形态学上的观察。用Annexin V/PI复染,流式细胞仪检测细胞早期凋亡率的变化。结果 反义STAT3转染后加以γ射线照射,B16细胞的增殖相比于两者单独作用组受到明显抑制,细胞凋亡水平也增加。结论 反义STAT3寡核苷酸联合γ射线对B16细胞的增殖抑制和诱导凋亡作用明显增强,提高了鼠黑色素瘤B16细胞的辐射敏感性;表明阻断STAT3蛋白表达可能成为一种新的提高肿瘤辐射敏感性的有效手段。     

异鼠李素对肺癌的作用及其抗肿瘤机制的初步探讨

目的探讨异鼠李素体内外对肺癌增殖的影响及初步研究其抗肿瘤机制。方法将不同浓度异鼠李素加入体外培养的人A549细胞,用MTT法,^3H-TdR掺入法等测定体外抗瘤活性,用流式细胞仪、彗星电泳、免疫组化等观察其对肿瘤细胞凋亡的诱导作用;采用Lewis细胞C57BL／6鼠移植瘤,观察药物对移植瘤的影响。结果异鼠李素处理A549细胞后,细胞形态出现典型凋亡特征,下调bcl-2基因,PCNA蛋白表达;上调抑癌基因P53、bax及caspase-3基因。实验观察到,异鼠李素在体内也具有明显的抗肿瘤作用,可显著降低癌细胞增殖指数,诱导Lewis肺癌凋亡,其机理可能与下调PCNA和bcl-2的表达,上调caspase-3、bax表达有关。结论异鼠李素抑制肿瘤细胞的生长增殖,诱导细胞凋亡是其抗肿瘤作用主要机制之一,是一种有较好前景的抗肿瘤的新型中药单体。     

大鼠脑创伤细胞凋亡和bcl-2基因家族表达的变化

目的：研究创伤性脑损伤（TBI）脑细胞凋亡发生及bcl-2基因家族表达变化,揭示TBI后继发性脑损伤的发生机制。方法：建立大鼠TBI模型,运用组织原位标记凋亡细胞检测、免疫组织化学等技术,观察TBI后1～14d大脑伤侧皮层和海马等脑区细胞凋亡及bcl-2、bax基因表达的变化。结果：TBI后伤侧大脑广泛存在凋亡现象,以皮层及海马为甚;伤后1d即出现凋亡细胞,3d达高峰,7～14d逐渐恢复正常;TBI后bcl-2、bax基因在伤脑表达增高,其增高的时相与凋亡规律相似,表达与细胞凋亡发生呈正相关。结论：细胞凋亡参与TBI后脑细胞的死亡机制,bcl-2基因在TBI后的脑组织中表达增加,对细胞凋亡发生有抑制作用;bax可促进细胞凋亡,TBI后表达明显增加,参与TBI后细胞凋亡的正向调节,可能是脑创伤后细胞死亡的重要机制。     

Flt3配体联合其他细胞因子对受照射小鼠免疫系统的作用研究

目的：研究Flt3配体（FL）在受照射小鼠免疫系统恢复中的作用。方法：采用F－800血细胞自动计数仪行外周血细胞计数及血细胞分类计数，流式细胞仪分析外周血淋巴细胞表型。结果：照射前应用FL或照射后联合应用FL，IL－11，EPO和G－CSF等细胞因子，能有效地促进受照小鼠外周血白细胞和淋巴细胞的恢复，对CD8^ 细胞的恢复作用尤为明显，同时使CD4^ /CD8^ 细胞比值较早恢复正常，提高受照射小鼠的生存率，结论：FL不但能促进辐射损伤机体造血功能的恢复，对免疫系统的亦具有重要的作用，FL单独或与其他细胞因子联合应用，对辐射损伤动物具有明显的防护和治疗效应。     

低剂量辐射对小鼠胸腺细胞成熟、分化、凋亡和激活的影响

目的研究低剂量辐射对胸腺细胞成熟、分化、激活和细胞凋亡及有关基因蛋白表达的影响，以揭示低剂量辐射免疫增强效应的发生机理。方法采用双参数直接免疫荧光和间接免疫荧光流式细胞术，检测了低剂量辐射小鼠全身照射后胸腺细胞ＣＤ４、ＣＤ８、ＴＣＲ、ＣＤ３、ＩＬ－２Ｒ、［Ｃａ２＋］ｉ、Ｂｃ１－２、Ｂａｘ的表达和细胞凋亡。结果实验结果表明：低剂量辐射全身照射未引起ＴＳ减少和ＴＨ／ＴＳ比值上调；低剂量辐射未增加胸腺细胞凋亡，这与Ｂｃｌ－２／Ｂａｘ比值上调有关；低剂量辐射促进了胸腺细胞的成熟分化和信息传递过程。结论以上结果提示：低剂量辐射促进胸腺细胞的成熟、分化和激活，使胸腺向外周输送成熟的具有功能活性的效应性Ｔ细胞的储备增强，可能是低剂量辐射免疫增强效应的重要机理。     

AIF、Bax和Bcl-2在中子及γ射线照射致肠道损伤中的表达

目的 探讨AIF、Bax和Bcl-2在中子及7射线照射致肠道损伤中的表达变化及意义.方法 290只BALWc雄性小鼠,随机分为对照组(24只)、2.5Gy中子照射组(80只)、4.0Gy中子照射组(60只)、5.5Gy γ射线照射组(72只)及12.0Gy γ射线照射组(54只),分别采用5.5和12.0Gy γ射线以及2.5和4.0Gy的中子照射,并于照射后6h,1、2、3、5、10d活杀,取空肠组织,用免疫组织化学和图像分析技术定量分析MF、Bax及Bcl-2蛋白的表达变化.结果 对照组小鼠空肠绒毛及隐窝上皮细胞质AIF呈强阳性,Bax和Bd-2呈弱阳性.中子和γ射线照射后6h～1d,隐窝细胞核中AIF呈强阳性,表达明显增加(P<0.01);4.0Gy中子照射后Bax强阳性持续至照射后3d,表达明显增加(P<0.01).5.5、12.0Gy γ射线及2.5Gy中子照射后6h～5d,Bcl-2于上述部位呈强阳性,表达明显增加(P<0.01).4.0Gy中子照射后6h～3d,Bcl-2于上述部位呈弱阳性,表达无改变(P>0.05).结论 中子及γ射线照射后空肠隐窝上皮细胞核中AIF表达增加,参与了肠上皮细胞凋亡的过程.中子照射时的Bax表达强于γ射线照射时,γ射线照射时的Bcl-2表达强于中子照射时,二者变化规律不同,提示中子和γ射线致肠道损伤具有不同的分子机制.     

Studies on radiation-induced apoptosis in G0 human lymphocytes

PURPOSE: To determine the relationships between the frequencies of radiation-induced chromosomal alterations and the extent of apoptosis in G0 human lymphocytes. MATERIAL AND METHODS: G0 human peripheral blood lymphocytes (HPBL) were X or gamma-irradiated, in the presence or absence of the repair inhibitor cytosine arabinoside (Ara-C). Directly after irradiation, a part of the lymphocytes were stimulated to grow while the rest were stimulated 48 h after irradiation. These lymphocyte cultures were analysed for induction of chromosomal aberrations. A subset of lymphocytes was kept in G0 and analysed for cell viability, apoptosis and p53 expression. RESULTS: The fraction of cells bearing dicentrics was reduced in lymphocytes stimulated to grow 48 h post irradiation as compared to lymphocytes stimulated immediately after irradiation. The decrease in the frequency of dicentrics correlated with the increase in the number of apoptotic cells. The operative apoptotic pathway in irradiated Go lymphocytes was dependent on the expression of p53. CONCLUSIONS: The radiation-induced apoptotic response of G0 lymphocytes is p53 dependent and increases with the time they are held in G0. When mitogen was added 48 h after irradiation, cells with dicentrics were either preferentially eliminated or did not enter mitosis. Thus the radiation-induced damage can be underevaluated depending on the time between radiation exposure and the induction of proliferation. These results may have relevance for biodosimetry studies or for evaluations of the efficacy of radiotherapy which are based on the frequencies of chromosomal aberrations.     

Bone marrow stromal cells spontaneously produce Flt3-ligand: influence of ionizing radiations and cytokine stimulation

PURPOSE: To define the ability of human bone marrow (BM) stromal cells to produce fms-like tyrosine kinase 3 (Flt3)-ligand (FL), and the effect of irradiation, tumour necrosis factor-alpha (TNFalpha) or tumour growth factor beta (TGFbeta) on FL production. MATERIAL AND METHODS: Primary BM stromal cell cultures were irradiated at 2-10 Gy or were stimulated with TNFalpha or TGFbeta1. The presence of FL was tested in culture supernatants and in cell lysate. The presence of a membrane-bound form of FL and the level of gene expression were also tested. RESULTS: Primary BM stromal cells spontaneously released FL. This production was increased by TNFalpha but not by TGFbeta1 or by irradiation. Chemical induction of osteoblastic differentiation from BM stromal cells also induced an increase in FL release. CONCLUSIONS: Our results suggest that the observed increase in FL concentration after in vivo irradiation is an indirect effect. The possible implication of BM stromal cells in these mechanisms is discussed.     

放创复合伤皮肤伤口成纤维细胞凋亡变化及其机理研究

目的 研究合并全身放射损伤的创伤（放创复合伤）局部成纤维细胞凋亡变化及其机理。方法 采用组织学、免疫组化、透射电镜、原位凋亡检测等方法观察大鼠皮肤伤口局部成纤维细胞数量、凋亡变化及调亡调控分子Bcl-2和Bax含量变化。结果 放创复合伤皮肤伤口成纤维细胞凋亡较单纯创伤组显著增加，伤口局部Bax含量也显著增加，Bcl-2含量和Bcl-2/Bax比值较单纯创伤组显著降低。结论 全身放射损伤可使创伤局部成纤维细胞凋亡增加，从而使伤口局部成纤维细胞数量减少；伤口局部Bcl-2、Bax含量及其比值异常可能是成纤维细胞凋亡增加的重要原因。     

重离子辐射对人外周血T淋巴细胞生物学性能的影响

目的研究重离子对人外周血T淋巴细胞增殖、凋亡等生物学性能的影响并探讨其机制,为肿瘤放射治疗的辐射防护提供实验依据和基础。方法 Ficoll分离法分离人外周血T淋巴细胞,采用12C重离子束坪区照射,照射样品能量为70 MeV、LET=29 keV/μm,照射剂量为1.0和2.0 Gy,剂量率为0.5 Gy/min。分别于照射后12、24h,RT-PCR检测凋亡相关基因Bcl-2,Bax,Caspase3,Caspase8和Caspase9的表达;于照射后24、48 h,CCK8法检测细胞增殖能力;于照射后24、48 h,采用AnnexinV-PE/7-AAD、AnnexinV-FITC/PI法检测凋亡发生,并采用RT-PCR检测凋亡相关蛋白Bcl-2、Bax和Caspase3的表达。结果重离子照射可明显抑制人外周血T淋巴细胞的增殖,随着剂量增大,抑制作用更加明显。同时,重离子照射可促进T淋巴细胞的凋亡,特别是对于晚期凋亡的诱导作用（P〈0.01）。RT-PCR检测结果显示,重离子辐射可抑制抗凋亡蛋白Bcl-2的表达,促进促凋亡蛋白Bax和Caspase3的表达（P〈0.01）。结论重离子辐射可显著影响抑制T淋巴细胞的增殖并促进其凋亡。     

黄芪总黄酮对人体正常细胞和肿瘤细胞辐射防护作用的差异性研究

目的 研究黄芪总黄酮(total flayonoids of astragalus,TFA)对60°Co γ射线辐射损伤的人体正常骨髓间充质干细胞(human mesenchymal stem cells,hMSCs)和肝癌细胞HepG-2辐射防护作用的差异性.方法 MTT法检测TFA处理组与单纯照射组hMSCs和HepG-2的细胞活性;HepG-2细胞克隆形成实验检测细胞的辐射敏感性;流式细胞技术分析细胞凋亡率;Western blot技术分析凋亡相关蛋白Fas,Bcl-2,Bax的表达.结果 MTT检测结果显示,当给予6 Gy γ射线一次性照射后,TFA预处理组hMSCs细胞活性分别比单纯照射组提高了1.15～1.95倍;经相同浓度TFA预处理的肝癌细胞HepG-2的细胞活性仅为单纯照射组的53%～23%;TFA的给药浓度与细胞存活率(survival rate)之间显现出良好的量效关系.细胞克隆形成实验结果显示:TFA+照射组能够明显抑制HepG-2细胞增殖,作用强于单纯TFA给药组和单纯照射组.流式细胞分析表明,经6 Gy γ射线一次性照射6、24和48 h后,TFA预处理组hMSCs的细胞凋亡率分别为23.3%,11.2%和2.9%.单纯照射组hMSCs的细胞凋亡率相应为29.3%,24.9%和13.6%;TFA预处理组肝癌细胞HepG-2的细胞凋亡率分别为11.6%,17.3%和20.1%,单纯照射组HepG-2的细胞凋亡率分别为6.9%、9.3%和15.8%.Western blot分析显示,在肝癌细胞HepG-2中,TFA预处理照射组促凋亡蛋白Fas和Bax 的表达量显著高于单纯照射组和对照组(t=11.17～-2.8,-12.35～3.4,P＜0.05);凋亡抑制蛋白Bel-2的表达量,TFA预处理照射组明显低于单纯照射组和对照组(f<6.36～17.61.P<0.05).结论 TFA对人正常骨髓间充质细胞具有明显的放射防护作用,对肝癌细胞不仅没有放射防护作用反而具有凋亡促进作用;TFA对肝癌细胞的促凋亡作用,主要通过上调促凋亡蛋白Fas和Bax的表达与下调凋亡抑制蛋白Bcl-2的表达,从而大大增强了60 Co γ射线对肝癌细胞的凋亡诱导作用.

Abstract：

Objective To investigate the different radioprotective effects of total flavonoids of Astragalus (TFA) on human normal mesenchymal stem cells(hMSCs) and hepatoma cells injured by 60 Coγ-ray radiation.Methods hMSCs and HepG-2 cells were cultured and randomly divided into TFA-treated and untreated groups.The cells of different groups were irradiated with 60 Co γ-rays at the dose of 6 Gy.MTT method was utilized to detect the survival rates of the hMSCs and HepG-2 cells pretreated or untreated with TFA before irradiation.Cell clone formation test was used to measure the cellular radiosensitivity.The apoptosis rates of different groups were determined by flow cytometer assay.The expression rates of the apoptosis-promoting proteins Fas and Bax and the apoptosis-inhibiting protein Bcl-2 were analyzed by Western blotting.Results MTT showed that the survival rates of hMSCs pretreated by TFA were 1.15-1.95 times higher than that of the pure irradiation group.On the contrary,the survival rates of the TFA pretreated HepG-2 cells were only 0.53-0.23 times that of the pure irradiation group.There was a good dose-effect relationship between the cell survival rate and the TFA concentration.Cell clone formation rate indicated that combined treatment of TFA and radiation inhibited the cell proliferation more effectively than single TFA or pure radiation.Flow cytometry showed that 6,24 and,48 h post-irradiation to 6 Gy,the apoptosis rates of the hMSCs were 23.3% ,11.2% ,and 2.9% ,respectively in the TFA pretreated group and were 29.3% ,24.9% ,and 13.6% in the pure radiation group.However,the apoptosis rates of the HepG-2 cells at 6,24,and 48 h post-irradiation to 6 Gy were 11.6% ,17.3% ,and 20.1% ,respectively in the TFA pretreated group and were 6.9% ,9.3% ,and 15.8% ,respectively in the direct radiation group.Western blotting showed that the expression levels of Fas and Bax proteins in the HepG-2 cells were significantly higher in the TFA pretreated group than in the pure radiation group.On the contrary,the expression level of the apoptosis inhibiting protein Bcl-2 was significantly lower in the TFA pretreated group than in the pure radiation group.Conclusions TFA has obvious effects of radiological protection on human hMSCs and has no effects of radiological protection but effects of apoptosis enhancement on hepatoma cells.The promotion of apoptosis of TFA on hepatoma cells is primarily through increasing the expression of apoptotic proteins such as Fas and Bax and reducing the expression of anti-apoptotic protein Bcl-2.     

12C重离子束对人淋巴细胞增殖、周期和凋亡的影响

目的 探讨¹²C重离子束对人淋巴细胞增殖以及周期、凋亡的影响.方法 ¹²C重离子束照射人淋巴细胞Peng-EBV,吸收剂量分别为0(对照组)、0.5、2.0 Gy.照射后用MTS法检测细胞增殖活力,流式细胞仪检测细胞周期和细胞凋亡.结果 与对照组相比,0.5 Gy照射可以增加细胞增殖活力(t=2.66~14.45, P<0.05),而2.0 Gy照射降低了细胞活力(t=7.65~64.45, P<0.05).受照射细胞的活力存在一个恢复和下降过程,受照后48 h内,细胞数量呈增加趋势,但72 h时细胞数量下降.照射后48 h,两组细胞G₂/M期呈明显上升趋势,高于对照组(t=2.01~99.80,P<0.05),且2.0 Gy组的周期阻滞较0.5 Gy组严重;照射后30 d,细胞周期阻滞恢复到正常水平.照射后12、24、48 h,两照射组与对照组相比,细胞凋亡率差异有统计学意义(t=-3.05~-1.05,P<0.05),在照后24 h最高,48 h明显下降,30 d恢复到对照水平.结论 ¹²C离子束辐射影响人淋巴细胞增殖,诱导人淋巴细胞发生明显的G₂/M期阻滞,并且明显地促进细胞凋亡.     

Studies on radiation-induced apoptosis in G0 human lymphocytes

Purpose: To determine the relationships between the frequencies of radiation-induced chromosomal alterations and the extent of apoptosis in G₀ human lymphocytes.

Material and methods: G₀ human peripheral blood lymphocytes (HPBL) were X or γ-irradiated, in the presence or absence of the repair inhibitor cytosine arabinoside (Ara-C). Directly after irradiation, a part of the lymphocytes were stimulated to grow while the rest were stimulated 48 h after irradiation. These lymphocyte cultures were analysed for induction of chromosomal aberrations. A subset of lymphocytes was kept in G₀ and analysed for cell viability, apoptosis and p53 expression.

Results: The fraction of cells bearing dicentrics was reduced in lymphocytes stimulated to grow 48 h post irradiation as compared to lymphocytes stimulated immediately after irradiation. The decrease in the frequency of dicentrics correlated with the increase in the number of apoptotic cells. The operative apoptotic pathway in irradiated Go lymphocytes was dependent on the expression of p53.

Conclusions: The radiation-induced apoptotic response of G₀ lymphocytes is p53 dependent and increases with the time they are held in G₀. When mitogen was added 48 h after irradiation, cells with dicentrics were either preferentially eliminated or did not enter mitosis. Thus the radiation-induced damage can be underevaluated depending on the time between radiation exposure and the induction of proliferation. These results may have relevance for biodosimetry studies or for evaluations of the efficacy of radiotherapy which are based on the frequencies of chromosomal aberrations.