蜂毒素对肝癌细胞磷脂酶A_2的影响

目的观察蜂毒素诱导细胞凋亡及对胞质型细胞磷脂酶A2(cPLA2)的影响。方法肝癌细胞BEL-7402体外培养,采用MTT法了解蜂毒素对肝癌细胞增殖的影响,用流式细胞术测定细胞凋亡,采用RT-PCR检测cPLA2的表达。结果蜂毒素在体外能够抑制肝癌细胞的增殖活性,并有诱导细胞凋亡的作用,RT-PCR检测显示,蜂毒素mRNA水平均具有激活cPLA2的作用。结论蜂毒素具有诱导肝癌凋亡及激活cPLA2的生物活性。     

异鼠李素对人肝癌HepG-2细胞增殖与凋亡影响的实验研究

目的：观察异鼠李素对人肝癌HepG-2细胞的增殖周期及凋亡的影响。方法噻唑蓝（Mar）法检测异鼠李素对肿瘤细胞生长的抑制作用,流式细胞仪检测异鼠李素对肿瘤细胞周期及凋亡的影响。结果MTr结果提示异鼠李素对人肝癌细胞的增殖有明显抑制作用,并随着作用浓度的增大,抑制作用逐渐增强,以100mg／L的异鼠李素培养基抑制作用最明显。流式细胞仪检测可见亚二倍体峰,提示异鼠李素有诱导入肝癌细胞凋亡作用。异鼠李素可通过诱导人肝癌细胞凋亡并将细胞阻滞在G0—G1期,使细胞不能进入s期进行DNA合成,最终使瘤细胞的体外增殖受到抑制。结论异鼠李素抑制人肝癌细胞的增殖。阻滞细胞周期,诱导细胞凋亡,可能具有一定抗肝癌作用。     

三氧化二砷对人结肠癌细胞增殖及凋亡影响的研究

目的：观察三氧化二砷（As2O3）对人结肠腺癌LS-174T细胞增殖的抑制及凋亡的诱导作用。方法：应用MTT法、细胞集落形成试验、流式细胞仪技术和TUNEL法观察不同浓度的As2O3(1.0μmol,2.0μmol，4.0μmol，8.0μmol，16.0μmol/L）对LS-174T细胞增殖和凋亡的影响。免疫组化技术观察As2O3对bcl-2基因表达的影响。结果：LS-174T细胞经As2o3作用后，细胞生长抑制率上升，细胞集落形成率下降，细胞周期中G1期细胞比例上升，S期和G2/M期细胞比例下降，TUNEL法显示凋亡细胞数增加，免疫组化结果显示bcl-2的表达明显减弱。结论：As2O3能抑LS-174T细胞增殖并诱导该细胞株凋亡，其机理可能与下调bcl-2表达有关。     

鹰嘴豆芽提取物对Caco-2细胞凋亡的作用

目的研究鹰嘴豆芽乙醇提取物（CSE）对人结肠腺癌Caco-2细胞增殖及细胞凋亡的影响。方法提取鹰嘴豆芽的活性成分并测定含量;MTT法观察提取物对Caco-2细胞增殖的影响;透射电镜观察细胞超微结构;琼脂糖凝胶电泳法进行细胞凋亡的DNA分析;流式细胞术检测凋亡情况。结果 CSE含23.53%皂苷、14.73%异黄酮;不同浓度的CSE对Caco-2细胞均有一定的增殖抑制作用,且呈量效和时效关系;细胞出现染色质边移和凋亡小体;DNA电泳呈现梯度条带,表明CSE可诱导Caco-2细胞凋亡;3、5、10μg/ml的CSE作用后,细胞凋亡率分别为32.6%、68.8%、73.9%,与对照组（0.9%）比较差异显著（P〈0.05）。结论 CSE可通过诱导细胞凋亡而抑制人结肠腺癌株Caco-2细胞的生长,为鹰嘴豆应用于结肠癌的临床治疗和预防提供了理论依据。     

FHIT基因转染增强人肝癌细胞HepG2辐射敏感性

目的探讨脆性组胺酸三联体基因转染对肿瘤细胞辐射敏感性的影响。方法首先构建了含有FHIT基因编码序列的真核表达质粒pcDNA／FHIT，并转染人肝癌细胞株Hep G2得到表达正常FHIT蛋白的细胞株Hep G2，FHIT。然后利用CCK-8和流式细胞仪等方法研究了Hep G2／FHIT细胞接受^60Coγ射线电离辐射后细胞周期、增殖和凋亡的改变。结果研究表明人肝癌细胞Hep G2重新表达FHIT后其对电离辐射的敏感性增加，表现为接受电离辐射后细胞存活率下降，凋亡细胞增加。细胞周期检测发现Hep G2重新表达FHIT后接受电离辐射后发生G2期阻滞的程度减轻。结论FHIT基因缺失的肿瘤细胞重新表达正常的FHIT蛋白可以提高其辐射敏感性，并且辐射敏感性提高可能是和FHIT基因抑制了ATR／CHK1通路活性有关。FHIT基因．电离辐射联合治疗肿瘤，具有一定的协同作用，可以作为一个较好的肿瘤基因治疗的靶点。     

抑制端粒酶活性对1,25-（OH）2D3诱导肝癌细胞增殖分化的影响

目的：观察抑制端粒酶活性对1,25-（OH）2D3诱导肝癌细胞增殖分化的影响作用。方法：经脂质体介导,将反义端粒酶RNA转染肝癌细胞系SMMC7721细胞。转染细胞扩大培养后,添加1,25-（OH）2D3分别作用于各实验组细胞后,采用MTT法、平板克隆形成实验检测细胞的存活和生长;光镜和电子显微镜检测细胞分化形态改变。结果：对照组与转染组的吸光度值分别为1.685和0.686,说明转染反义端粒酶RNA可显著抑制肝癌细胞的端粒酶活性;而在抑制肝癌细胞端粒酶活性的基础上,1,25-（OH）2D3抑制肝癌细胞增殖和诱导细胞分化的作用得以显著的增强。形态学检查也进一步证实存在诱导分化改变。结论：在降低细胞端粒酶活性的基础上,1,25-（OH）2D3抑制肝癌细胞增殖、诱导细胞分化的作用得到增强。     

6-溴异香兰素对HeLa细胞的增殖抑制及放射增敏作用

目的研究香兰素衍生物中的6-溴异香兰素（6-溴-5-羟基-4-甲氧基苯甲醛,BVAN08）对HeLa细胞增殖和放射敏感性的影响,为开发新的抗癌和放射增敏药物提供理论依据。方法利用MTT法检测细胞增殖,单细胞凝胶电泳检测细胞DNA损伤,流式细胞术检测细胞周期,克隆形成率法检测细胞放射敏感性,AnnexinⅤ/PI染色法检测细胞凋亡。结果研究表明BVAN08在10～20μmol/L以上浓度就显示出对HeLa细胞增殖的抑制作用,抑制程度具有剂量依赖性,抑制细胞存活的IC50值为19.07μmol/L。BVAN08能诱发细胞DNA双链断裂损伤,作用4h就开始诱发细胞周期G2/M阻滞,随时间延长阻滞更加明显。BVAN08明显降低DNA修复蛋白DNA-PKcs的表达水平,20μmol/LBVAN08与2Gyγ射线复合作用可以显著增加细胞对射线的敏感性,增加细胞凋亡率。结论 BVAN08抑制HeLa细胞增殖,提高细胞的放射敏感性,其放射增敏作用与降低DNA-PKcs蛋白表达水平和G2/M阻滞有关。     

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。     

外源一氧化氮对大鼠胰岛细胞损伤机制研究

目的：研究外源NO对胰岛细胞的损伤机制和功能的影响。方法：采用DNA电泳技术以及单细胞电泳检测NO对胰岛细胞的凋亡和DNA的损伤作用；通过测定胰岛素含量检测胰岛细胞在NO作用下的合成和分泌功能。结果：外源NO能导致胰岛细胞DNA的断裂形成彗星细胞，DNA电泳显示典型梯状条带，大剂量NO形成死亡条带；同时NO能抑制胰岛细胞合成和分泌胰岛素。结论：外源NO可导致胰岛细胞凋亡、DNA断裂损伤并抑制其合成分泌胰岛素的功能。     

188Re-β射线诱导肝癌细胞凋亡与细胞周期阻断

目的：探讨放射性素^188Re-β射线内照射对人肝癌细胞HCC的细胞周期阻断及诱导凋亡的作用,方法：通过MTT实验,形态学观察,琼脂糖凝胶电泳和流式细胞术对核素诱导的HCC细胞进行了检测和观察,结果：^188Re导致的HCC细胞死亡具有典型的细胞凋亡形态学和生化特征,流式细胞术定量显示各期细胞数发生改变,且凋亡率和剂量呈依赖性,结论：^188Re-β射线低剂量和高剂量对HCC细胞周期的影响不同,低剂量主要使C0／G1期阻滞,较高剂量则导致G1阻滞减轻,S期和G2／M期细胞数增多。     

Angiopoietin-2 overexpression in morris hepatoma results in increased tumor perfusion and induction of critical angiogenesis-promoting genes.

Monitoring of angiogenesis-relevant approaches with functional imaging and histomorphometric analyses is desirable to evaluate the biologic effects. In this study we wished to examine the complex effects of angiopoietin-2 (Ang-2) gene transfer in a rat hepatoma model. METHODS: Using a bicistronic retroviral vector for Ang-2, Morris hepatoma (MH3924A) cell lines with Ang-2 expression were generated (Ang-2-MH3924A). In human umbilical vein endothelial cells (HUVECs) cocultured with Ang-2-MH3924A, the proliferative action with or without growth factors were determined. Furthermore, animal experiments were performed to measure effects on tumor growth and perfusion. Finally, tumors were examined by immunohistochemistry and DNA chip analysis. RESULTS: Ang-2-expressing MH3924A enhanced basic fibroblast growth factor-mediated endothelial cell proliferation. Perfusion, as measured by H(2)(15)O PET, was increased in genetically modified tumors. Consistent with the increased perfusion, micro- and macrovascularization were increased. However, tumor growth was similar to wild-type MH3924A (WT-MH3924A). Proliferating cell nuclear antigen and TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) staining revealed an increased number of positive cells, indicating a compensation of increased proliferation by enhanced apoptosis. DNA chip analysis showed an induction of angiogenesis-promoting genes, including crucial vascular growth factor receptors, as well as genes related to extracellular matrix (ECM), apoptosis, signal transduction, and oxidative stress. CONCLUSION: Our results suggest that Ang-2 expression increases perfusion or vascularization, especially in interaction with the vascular growth factor system, without affecting tumor growth. Simultaneous, enhanced expression of genes for ECM, apoptosis, and signal transduction indicates Ang-2's versatile role in angiogenesis including its destabilizing function on ECM and endothelium.     

Preclinical evaluation of locoregional delivery of radiolabeled iododeoxyuridine and thymidylate synthase inhibitor in a hepatoma model.

We report improved incorporation of the radiolabeled-thymidine analog [125I/131I]5-iodo-2'-deoxyuridine ([125I/131I]IdUrd) into DNA by the addition of Thymitaq, a thymidylate synthase inhibitor, as a strategy of molecular radiotherapy for hepatoma treatment. METHODS: The synergistic effect of combination [125I]IdUrd and Thymitaq in clonogenic survival and DNA incorporation was shown on the human hepatoma cell line Hep3B. Radiobiodistribution of intrahepatic arterially injected [125I]IdUrd and Thymitaq was studied in a rat N1S1 hepatoma model. In vivo therapeutic effects of locoregional delivery of both drugs were evaluated in mouse subcutaneous hepatoma and ascitic hepatoma models. RESULTS: In a clonogenic assay, Thymitaq showed a synergistic effect with [125I]IdUrd but not cold IdUrd. Thymitaq had a dose-dependent modulation effect on DNA-[125I]IdUrd incorporation. The biodistribution study indicated a slower clearance rate of [125I]IdUdR in the hepatoma as well as an initially higher uptake of [125I]IdUrd into DNA when the [125I]IdUrd was combined with Thymitaq. In vivo studies showed a superior therapeutic effect of combination Thymitaq and [125I]IdUrd in both subcutaneous and ascites tumor models, but the combination of [131I]IdUrd and [125I]IdUrd may be more effective than Auger electron emitters alone for the treatment of subcutaneous tumor. CONCLUSION: The strategy of locoregional delivery of [125I/131I]IdUrd to a tumor site through an intrahepatic arterial, intratumoral, or intraperitoneal route in combination with Thymitaq is promising and may also have a favorable therapeutic index in vivo.     

125I-UdR壳聚糖纳米微粒对肝癌细胞的内照射生物学效应

目的 评估¹²⁵I-UdR壳聚糖载药纳米微粒(¹²⁵I-UdR-CS-DLN)对肝癌细胞的内照射生物学效应.方法 采用激光共聚焦显微镜观察¹²⁵I-UdR-CS-DLN在肝癌细胞HepG2和人正常肝组织细胞HL-7702内的聚积和分布;通过MTT实验、流式细胞仪和单细胞凝胶电泳技术,评价内照射细胞生物学效应;采用TUNEL染色法观察兔肝原位肿瘤细胞经¹²⁵I-UdR-CS-DLN靶向治疗后的细胞凋亡.结果 纳米微粒作用30 min后,其在HepG2细胞质内的聚积大于HL-7702;当¹²⁵I-UdR-CS-DLN浓度大于37 kBq/ml时,HepG2细胞在纳米微粒作用后24、48 h的存活率显著低于HL-7702细胞(t=-4.46~6.31,P<0.05),且细胞周期G₁期阻滞明显, G₂/M期细胞明显受损;¹²⁵I-UdR-CS-DLN造成细胞DNA双链断裂的程度明显高于¹²⁵I-UdR,HepG2细胞的DNA损伤后修复能力显著低于HL-7702(Olive尾矩:t=2.94,P<0.05;彗尾DNA%:t=10.64,P<0.01);兔肝原位癌模型经介入被动靶向治疗后的TUNEL染色结果表明,¹²⁵I-UdR-CS-DLN可使兔肝原位肿瘤细胞产生明显的凋亡,而相同剂量¹²⁵I-UdR作用后肿瘤并未出现明显的凋亡.结论 ¹²⁵I-UdR-CS-DLN进入肝癌细胞的能力明显强于¹²⁵I-UdR,引起的DNA辐射损伤效应更强,可明显加剧肝癌细胞的凋亡,阻止DNA损伤修复.     

Influence of clinically used antioxidants on radiation-induced expression of intercellular cell adhesion molecule-1 on HUVEC

Purpose: The effects of antioxidants (N-acetyl-l-cysteine [NAC] and pyrrolidine dithiocarbamate [PDTC]) on radiation-induced ICAM-1 expression on human umbilical vein endothelial cells (HUVEC) were investigated. Materials and methods : The expression of ICAM-1 on HUVEC was determined by flow cytometry up to 72h after X-irradiation. Functional competence of induced ICAM-1 was assessed by adhesion experiments with human polymorphonuclear neutrophils on irradiated HUVEC. Results: Preincubation of cells with both or either NAC and PDTC was unable to reduce radiation-induced ICAM-1 expression on HUVEC. In fact, by themselves, these antioxidants induced a significant increase of ICAM-1 expression, which in comparison with a radiation dose of 7Gy after 24h was nine times higher for PDTC, and more than double for NAC. Treatment with NAC clearly restrained TNF-alpha-induced ICAM expression on HUVEC, while preincubation of cells with PDTC showed synergistic effects. Conclusions: The role of reactive oxygen intermediates in signal transduction pathways leading to ICAM-1 expression should be investigated further. Furthermore, antioxidants may exert a proinflammatory role, as revealed by the induction of ICAM-1 expression on endothelial cells. The inhibition of TNF-alpha-induced ICAM-1 expression by NAC might have clinical implications because this substance is used as a radioprotector in radiotherapy.     

补骨脂素加长波紫外线光化学疗法诱导NB4细胞凋亡及对NF-κB/I-κB蛋白的影响

目的探讨补骨脂素(PSO)加长波紫外线(UVA)光化学疗法(PUVA)诱导人白血病NB4细胞凋亡及对NF-κB、I-κB蛋白的影响。方法以NB4细胞为研究对象,以电镜下细胞超微结构改变、细胞凋亡率以及NF-κB、I-κB蛋白的表达为检测指标,观察不同浓度PSO和(或)不同照射时间波长为360 nm的UVA对NB4细胞的作用。结果 PUVA处理后的NB4细胞超微结构出现明显的凋亡形态学改变;PSO、UVA及PUVA均可使细胞凋亡率增加,PUVA的作用显著强于前两者;凋亡率增加的同时上调了NF-κB、I-κB蛋白的表达。结论 PUVA可诱导NB4细胞凋亡,过程中上调了NF-κB、I-κB蛋白的表达。     

Apoptosis and the adaptive response in human lymphocytes.

PURPOSE: To determine whether the sensitivity of human lymphocytes for apoptosis induced by either a membrane oxidizing agent or a DNA damaging agent is modified by an adaptive response. MATERIALS AND METHODS: Peripheral blood lymphocytes from normal human donors were exposed to low doses of the DNA damaging agent gamma-radiation, or the membrane oxidizing agent t-butyl hydroperoxide (t-BuOOH), incubated for various times and then tested for their sensitivity to induction of apoptosis by a subsequent exposure to a high dose of either agent. Apoptosis was measured using a fluorescent assay of DNA unwinding or a terminal deoxynucleotide transferase assay. RESULTS: The results show that Go lymphocytes pre-exposed to an adapting dose of radiation or DNA strand breaking agent are not protected but can become sensitized to subsequent apoptosis induced by radiation (a kinetically slow process). Inter- and intraindividual variations were observed. However, neither pre-exposure to radiation nor to a membrane oxidizing agent sensitized lymphocytes from any donor to apoptosis induced by a membrane oxidizing agent (a kinetically fast process). CONCLUSIONS: Since an increase in the elimination of genetically damaged cells by apoptosis could reduce the risk of cancer from exposure to radiation or other DNA damaging agents, this cellular sensitization for apoptosis may represent a novel adaptive response mechanism.     

Apoptosis and the adaptive response in human lymphocytes

Purpose: To determine whether the sensitivity of human lymphocytes for apoptosis induced by either a membrane oxidizing agent or a DNA damaging agent is modified by an adaptive response. Materials and methods: Peripheral blood lymphocytes from normal human donors were exposed to low doses of the DNA damaging agent gamma-radiation, or the membrane oxidizing agent t-butyl hydroperoxide (t-BuOOH), incubated for various times and then tested for their sensitivity to induction of apoptosis by a subsequent exposure to a high dose of either agent. Apoptosis was measured using a fluorescent assay of DNA unwinding or a terminal deoxynucleotide transferase assay. Results: The results show that Go lymphocytes pre-exposed to an adapting dose of radiation or DNA strand breaking agent are not protected but can become sensitized to subsequent apoptosis induced by radiation (a kinetically slow process). Inter- and intra-individual variations were observed. However, neither pre-exposure to radiation nor to a membrane oxidizing agent sensitized lymphocytes from any donor to apoptosis induced by a membrane oxidizing agent (a kinetically fast process). Conclusions: Since an increase in the elimination of genetically damaged cells by apoptosis could reduce the risk of cancer from exposure to radiation or other DNA damaging agents, this cellular sensitization for apoptosis may represent a novel adaptive response mechanism.     

Influence of clinically used antioxidants on radiation-induced expression of intercellular cell adhesion molecule-1 on HUVEC.

PURPOSE: The effects of antioxidants (N-acetyl-L-cysteine [NAC] and pyrrolidine dithiocarbamate [PDTC]) on radiation-induced ICAM-1 expression on human umbilical vein endothelial cells (HUVEC) were investigated. MATERIALS AND METHODS: The expression of ICAM-1 on HUVEC was determined by flow cytometry up to 72 h after X-irradiation. Functional competence of induced ICAM-1 was assessed by adhesion experiments with human polymorphonuclear neutrophils on irradiated HUVEC. RESULTS: Preincubation of cells with both or either NAC and PDTC was unable to reduce radiation-induced ICAM-1 expression on HUVEC. In fact, by themselves, these antioxidants induced a significant increase of ICAM-1 expression, which in comparison with a radiation dose of 7 Gy after 24h was nine times higher for PDTC, and more than double for NAC. Treatment with NAC clearly restrained TNF-alpha-induced ICAM expression on HUVEC, while preincubation of cells with PDTC showed synergistic effects. CONCLUSIONS: The role of reactive oxygen intermediates in signal transduction pathways leading to ICAM-1 expression should be investigated further. Furthermore, antioxidants may exert a pro-inflammatory role, as revealed by the induction of ICAM-1 expression on endothelial cells. The inhibition of TNF-alpha-induced ICAM-1 expression by NAC might have clinical implications because this substance is used as a radioprotector in radiotherapy.     

Radiation responses of Sf9, a highly radioresistant lepidopteran insect cell line

PURPOSE: Lepidopteran insect cells are known to exhibit very high radioresistance. Although very effective DNA excision-repair has been proposed as a contributing factor, a detailed understanding of insect cell radiation responses has not yet been obtained. Therefore, the study was carried out to understand the in vitro radiation responses of Sf9 lepidopteran cells. MATERIALS AND METHODS: Exponentially growing asynchronous Sf9 cells (derived from ovaries of Spodoptera frugiperda) were exposed to gamma-radiation doses of 2-200 Gy. Cell survival, growth inhibition, cell cycle progression delay, alterations in cell morphology as well as induction of DNA damage, micronuclei and apoptosis were studied at various post-irradiation time intervals. RESULTS: Biphasic survival response curves were obtained with D0 rising from 20 Gy (at doses < or = 60 Gy) to 85 Gy (between 60 and 200 Gy), corroborating earlier reports on lepidopteran cells. An additional downward deviation at 2 Gy indicated a hypersensitive response. Dose-dependent growth inhibition with a transient G2 delay starting 12 h and extending up to 48-96 h was observed at doses of 10-200 Gy, while a brief G1/S transition delay was observed only at higher doses (> or = 100 Gy). Significant DNA damage was detected only at 20 Gy and higher doses, in contrast with human cells that showed similar damage at 2 Gy. Interestingly, micronuclei were not induced at any of the doses tested, although spontaneous micronucleation was evident in <1% of cells. Lack of micronucleus induction even at doses that induced significant DNA damage and a transient G2 block (20-50 Gy) strongly indicated a role of holocentric lepidopteran chromosomes. Apoptosis was detected only in a small proportion of cells (3%) exposed to 200 Gy, and cell/nucleus size and granularity increased by 72-96 h post-irradiation in a dose-dependent manner. Sf9 nucleoids extracted at 2 M NaCl showed higher compactness than the nucleoids prepared from human cells. CONCLUSIONS: It is clearly shown that lepidopteran cells are highly resistant to the induction of DNA damage and micronuclei, and display very low induction of apoptosis at doses up to 200 Gy. While the lack of micronucleus induction seems to be primarily due to the holocentric nature of their chromosomes, certain unique signalling pathways might be responsible for the low induction of apoptosis. Factors causing protection of Sf9 cellular DNA from radiation-induced damage are presently being investigated.