粘中着斑激酶在TNF—α和环己亚胺协同诱导人肝癌细胞SMMC—7721凋亡中的作用

探讨了粘着斑激酶（focal adhesion kinase,FAK）在TNF－α和环己亚胺协同诱导SMMC－7721细胞凋亡中的作用,利用转染FAK反义质粒来特异性降低SMMC－7721细胞的FAK含量,用Western杂交的方法来检测蛋白激酶B（PKB）的蛋白含量,以及用流式细胞仪的方法来检测细胞的凋亡。研究发现TNF－α本身并不能诱导SMMC－7721细胞发生凋亡,而只有当用环己亚胺和TNF－α协同处理时才发生凋亡。在TNF－α和环己亚胺协同诱导的凋亡过程中,PKB蛋白含量的降低,提示PKB的蛋白水平与凋亡的发生密切相关。当用FAK反义质粒降低SMMC－7721细胞的FAK含量（约降低了60％）后,细胞对TNF－α和环己亚胺协同诱导的凋亡的敏感性在用低剂量TNF－α处理的情况下增加,而在高剂量TNF－α和处理的情况下降低,相应地,在低剂量TNF-α和环己亚胺处理的情况下,FAK反义质粒转染株细胞的PKB含量比对照的PKB含量低;而在高剂量TNF－α和环己亚胺处理的情况下,FAK反义质粒转染株细胞的PKB含量比对照的要高。结果提示,FAK对TNF－α和环己亚胺协同诱导SMMC－7721凋亡的过程有一双相作用,并且该过程可能与PKB有关。     

核苷酸切除修复基因XPA反义RNA表达载体的构建及其抑瘤功能

采用RT PCR方法扩增出 4 2 6bp着色性干皮病A(xerodermapigmentosumgroupA ,XPA)cDNA片段 (2～ 4 2 7bp) ,反向插入pcDNA3 1质粒构建XPA反义RNA表达载体 .经测序证实 ,该片段序列与XPAmRNA对应片段完全互补 .通过脂质体Lipofectamine 2 0 0 0将重组质粒转染肺癌A5 4 9细胞 ,RT PCR检测表明转染XPA反义RNA重组质粒能够抑制肺癌细胞XPAmRNA表达 ;MTT实验表明转染XPA反义RNA的肺癌细胞对顺铂敏感性增强 .本研究为深入探讨NER途径基因功能及临床克服肿瘤耐药提出了一个新的思路     

P16降低二倍体成纤维细胞的凋亡敏感性

脂质体介导法分别介导正、反义p16逆转录病毒表达载体转染人胚肺二倍体成纤维细胞 ,经鉴定后 ,分别用Hoechst33342 PI双染、TUNEL、DNAladder分析检测各转染细胞对H2 O2 的敏感性 .结果显示 ,反义p16重组体转染细胞较易凋亡 ,而正义p16重组体转染细胞不易凋亡 .Western印迹检测显示 ,正义p16重组体转染细胞中P2 1表达增强 ,caspase 3的表达减弱 .H2 O2 作用后 ,正义p16重组体转染细胞Bcl 2蛋白水平显著高于反义p16重组体转染细胞 .     

转染反义6A8cDNA对人鼻咽癌细胞肺转移的抑制

人鼻咽癌高肺转移克隆株CNE 2L2转染编码人α 甘露糖苷酶的cDNA( 6A8cDNA ,GenBank接受号为U3 72 48)的重组反义表达载体 ( pRc/CMV 反义6A8cDNA)后 ,与转染空载质粒pRc/CMV及未作任何转染的细胞相比 ,其生长受一定程度抑制 .接种于无胸腺鼠皮下 2个月 ,野型CNE 2L2细胞组有肺转移的小鼠数为 9/10 ( 90 % ) ,其中Ⅲ级 8只 ,Ⅱ级 1只 ;转染空载质粒pRc/CMV ,有肺转移者为6/8( 75 % ) ,其中Ⅲ级 1只 ,Ⅱ级 2只 ,Ⅰ级 3只 ;转染pRc/CMV 反义 6A8cDNA ,有肺转移者为 3 /10 ( 3 0 % ) ,全部为Ⅰ级 .     

下调c—erbB—2对细胞DNA修复和凋亡的影响

将有义和反义c-erbB-2逆转录病毒体分别经脂质体包裹后转染入人胚肺二倍体成纤维细胞（2BS）。Southern印迹杂交表明,外源c-erbB-2 cDNA在转染细胞中已成功整合入基因组中。Northern印迹杂交显示,有义转染细胞的erbB-2表达上升57％,反义转染细胞erbB-2表达下降48％。与对照和空载体转染细胞相比,反义转染细胞的DNA损伤修理能力显著下降,凋亡可诱导性降低。这和我们观察到的反义转染细胞提早出现衰老表型相一致。     

人骨髓间充质干细胞过表达白细胞介素-34对THP-1细胞的调节作用

构建人IL-34真核表达载体并将其转染到人骨髓间充质干细胞,观察高表达IL-34的骨髓间充质干细胞对THP-1细胞的影响。PCR扩增IL-34 DNA,并将其克隆到真核表达载体pIRES2-EGFP;将构建成功的重组体转染到骨髓间充质干细胞,Western blotting和ELISA分析IL-34在细胞中的表达;用高表达IL-34的骨髓间充质干细胞培养上清液来培养THP-1细胞,Real-time PCR分析THP-1细胞中IL-10和TNFα的表达变化。经双酶切和测序鉴定,成功构建了pIRES2-EGFP-IL-34重组体;转染至骨髓间充质干细胞的IL-34可以促进THP-1细胞表达IL-10和TNFα。结果表明,骨髓间充质干细胞表达分泌的IL-34对THP-1有调节作用。     

bcl-2对IL-1和TNFα表达的调节作用初探

通过将反义bcl-2基因转染于U937细胞,建立了Bcl-2蛋白表达受抑的U937细胞模型,证实了模型细胞的增殖和存活表型无明显变化.放线菌素D-结晶紫试验和ELISA检测表明模型细胞上清中TNFα的活性和含量无明显变化,小鼠胸腺细胞增殖试验表明模型细胞上清中IL-1活性升高,提示bcl-2的表达对TNFα的表达无明显影响,但可能在一定程度上抑制了IL-1的表达或活性.探讨bcl-2对细胞因子表达的调节作用,为其作用机制的研究积累了有益资料.     

bFGF反义寡核苷酸增强鼠黑色素瘤B16细胞化疗药物敏感性研究

目的:研究bFGF反义硫代寡核苷酸增强肿瘤细胞对化疗药物敏感性作用。方法:设计、合成bFGF寡核苷酸,用聚乙烯亚胺(polyemyleneimine,PEI)介导bFGF反义硫代寡核苷酸转染入黑色素瘤B16细胞,MTT法检测bFGF反义硫代寡核苷酸及其与化疗药物联合处理后的细胞增殖率;半定量RT-PCR测定bFGF反义硫代寡核苷酸转染后细胞中bFGF mRNA水平;流式细胞仪分析bFGF反义硫代寡核苷酸诱导的细胞凋亡。结果:bFGF反义硫代寡核苷酸对B16细胞增殖的抑制率为64.8%,且呈剂量依赖效应。B16细胞中bFGF mRNA被bFGF反义硫代寡核苷酸显著降低,为对照细胞的57.9%,且bFGF反义硫代寡核苷酸诱导B16细胞凋亡,凋亡率为41.8%。bFGF反义硫代寡核苷酸转染能显著增强B16细胞对阿霉素、5-氟脲嘧啶及顺铂的敏感性,非特异性硫代寡核苷酸不影响阿霉素、5-氟脲嘧啶及顺铂抑制B16细胞增殖。结论:bFGF反义硫代寡核苷酸显著增强B16细胞的化疗敏感性,表明其可协同化疗药物用于治疗肿瘤。     

Ms—SOD对CHO细胞电离辐射敏感性的影响

近年来的研究发现,ＩＬ－１和ＴＮＦ最重要的辐射防护因子,因ＩＬ－０１和ＴＮＦ都能造反性诱导Ｍｎ－ＳＯＤ的高度表达,因此认为Ｍｎ－ＳＯＤ可能有辐射防护作用。通过转染有义和反义Ｍｎ－ＳＯＤｃＮＤＡ小于ＣＨＯ细胞,进一步说明了Ｍｎ－ＳＯＤ在抗电离辐射损伤中的作用。     

HIV-1Tat蛋白抑制DNA修复和增强细胞辐射敏感性

近年来临床研究发现,艾滋病合并肿瘤患者放疗后产生的正常组织和皮肤毒性反应明显高于普通肿瘤患者.本研究将探讨HIV-1Tat蛋白是否影响细胞对电离辐射敏感性及机理. 两个表达Tat蛋白的细胞系TT2和TE671-Tat均来源于人的横纹肌肉瘤细胞（TE671）并已转染了不同来源的tat基因.使用细胞辐射后克隆形成率检测辐射敏感性,RT-PCR和Western 印迹检测基因表达,彗星电泳和γ-H2AX位点检测DNA双链断裂和修复. TT2和TE671-Tat细胞的辐射敏感性与转染空载体及对照细胞相比明显增加.彗星电泳和γ-H2AX位点检测表明,在表达Tat蛋白的细胞中,辐射诱导DNA双链断裂的修复水平明显降低.通过RT-PCR和Western 印迹检测进一步证实,表达Tat蛋白的细胞中DNA修复蛋白DNA-PKcs的表达被抑制. HIV-1Tat蛋白抑制DNA-PKcs的表达,降低DNA双链断裂的修复,使细胞的电离辐射敏感性增高.本研究为了解AIDS合并肿瘤患者对放射治疗敏感性变化提供了重要信息.     

Increased chromosomal radiosensitivity of a Chinese hamster ovary cell line that inducibly expresses the Eco RI restriction endonuclease

We have transfected a Chinese hamster ovary cell line (CHO 6) with a plasmid that inducibly expresses the Eco RI restriction endonuclease gene in the presence of cadmium sulfate (CdSO4). Expression of Eco RI results in DNA double-strand breaks, which can lead to chromosome aberrations. The new line, designated CHO 10, also has a low level of constitutive expression of Eco RI in the absence of CdSO4 without any cytogenetic effect. This suggested that these cells may be efficient at repairing low levels of DNA double-strand breaks. To test this, both cell lines were exposed to ionizing radiation, and aberration yields were analyzed with or without induction of Eco RI. CHO 10 cells showed increased radiosensitivity after G1 irradiation, but after G2 exposure, only doses greater than or equal to 0.4 Gy caused more damage in CHO 10 cells. We conclude that CHO 10 cells can tolerate constitutive expression of Eco RI, but that when the cells are subjected to additional stress, in this case ionizing radiation, they become very sensitive to DNA double-strand breaks.     

Induction of Mn-superoxide dismutase by tumor necrosis factor, interleukin-1 and interleukin-6 in human hepatoma cells.

Effects of Tumor Necrosis Factor (TNF), Interleukin-1 (IL-1), Interleukin-6 (IL-6) and Interferon-gamma (IFN-gamma) on the expression of Mn-superoxide dismutase (Mn-SOD) protein were investigated in human hepatoma cells, Hu-H1, which revealed resistance to the cytotoxicity of TNF and IL-1. Both TNF and IL-1 enhanced the Mn-SOD production to the level of 30- to 40-fold. IL-6 also increased the enzyme protein to 2- to 3-fold of the basal level without any cell proliferative effect. A specific antibody against IL-6 almost completely inhibited the induction of Mn-SOD. IL-6, as well as TNF and IL-1, appears to play some role in the Mn-SOD protein expression in human hepatoma cells.     

Glucose-6-phosphate dehydrogenase and the oxidative pentose phosphate cycle protect cells against apoptosis induced by low doses of ionizing radiation

The initial and rate-limiting enzyme of the oxidative pentose phosphate shunt, glucose-6-phosphate dehydrogenase (G6PD), is inhibited by NADPH and stimulated by NADP(+). Hence, under normal growth conditions, where NADPH levels exceed NADP(+) levels by as much as 100-fold, the activity of the pentose phosphate cycle is extremely low. However, during oxidant stress, pentose phosphate cycle activity can increase by as much as 200-fold over basal levels, to maintain the cytosolic reducing environment. G6PD-deficient (G6PD(-)) cell lines are sensitive to toxicity induced by chemical oxidants and ionizing radiation. Compared to wild-type CHO cells, enhanced sensitivity to ionizing radiation was observed for G6PD(-) cells exposed to single-dose or fractionated radiation. Fitting the single-dose radiation response data to the linear-quadratic model of radiation-induced cytotoxicity, we found that the G6PD(-) cells exhibited a significant enhancement in the alpha component of radiation-induced cell killing, while the values obtained for the beta component were similar in both the G6PD(-) and wild-type CHO cell lines. Here we report that the enhanced alpha component of radiation-induced cell killing is associated with a significant increase in the incidence of ionizing radiation-induced apoptosis in the G6PD(-) cells. These data suggest that G6PD and the oxidative pentose phosphate shunt protect cells from ionizing radiation-induced cell killing by limiting the incidence of radiation-induced apoptosis. The sensitivity to radiation-induced apoptosis was lost when the cDNA for wild-type G6PD was transfected into the G6PD(-) cell lines. Depleting GSH with l-BSO enhanced apoptosis of K1 cells while having no effect in the G6PD(-) cell line     

Expression of amplified cDNA and genomic sequences encoding human interleukin 2 in Chinese hamster ovary cells

Expression of human interleukin 2 (IL-2) at high levels has been achieved in Chinese hamster ovary (CHO) cells by amplification of transfected sequences. Plasmids containing the human IL-2 cDNA or genomic DNA and mouse dihydrofolate reductase (DHFR) cDNA were transfected into DHFR-negative CHO cells. Transformants expressing DHFR were selected in media lacking nucleosides, and cells which amplified both DHFR and IL-2 genes were obtained by exposure to increasing methotrexate (MTX) concentrations. These cell lines constitutively expressed elevated levels of IL-2 at a concentration of 2 mg/liter. These cell lines continued to produce IL-2 stably through at least 1 month, even in the absence of MTX.     

The in vitro sensitivities to radiation and misonidazole of mouse bone marrow cells derived from different microenvironments

Previous studies had indicated that haematopoietic cells (CFU-GM) which reside within compact bone are resistant to ionizing radiation and sensitive to the cytotoxic action of misonidazole (MISO) relative to cells which reside within the core of mouse femurs. It was postulated that the microenvironment within compact bone might be relatively hypoxic. CFU-GM from femur cores (Fraction 1) and from compact bone (Fraction 3) have been exposed to ionizing radiation and to the hypoxic cell radiosensitizer, MISO, under controlled conditions of oxygenation in vitro. The inherent radiosensitivity of aerated Fraction 1 CFU-GM is similar to their in vivo radiosensitivity. An oxygen enhancement ratio of 2.2 is observed for these cells in vitro. On the other hand, the in vitro radiosensitivity of hypoxic Fraction 3 CFU-GM was similar to their in vivo radiosensitivity. The oxygen enhancement ratio for Fraction 3 cells was 1.5, significantly lower than that observed for Fraction 1 cells. When CFU-GM cells were exposed to MISO under hypoxic conditions in vitro it was found that Fraction 3 CFU-GM were more sensitive to its cytotoxic action than were cells from Fraction 1. These data are consistent with the interpretation that some CFU-GM reside in an environment of relative hypoxia within the compact bone of the mouse femur.     

Sequence and expression of rat ICAM-1.

We have isolated cDNA clones-coding for rat intercellular adhesion molecule-1 (RICAM-1) from a cDNA library constructed from rat Ax cells stimulated with IL-1 beta using the mouse ICAM-1 cDNA as a hybridization probe. The RICAM-1 sequence shows 79.1% homology with mouse ICAM-1 and 55.6% homology with human ICAM-1 at the nucleic acid level. In order to examine the expression of RICAM-1 on Chinese hamster ovary (CHO) cells, we constructed the vector, pSV-RICAM1-neo, containing the SV40 promoter. Flowcytometric analysis showed that CHO-K1 cells transfected with pSV-RICAM1-neo expressed high amounts of RICAM-1 on their surfaces.     

全长及缺失VLDL受体基因转染的CHO细胞与β-VLDL的结合效应

为探讨 VLDL受体结合域中 8个重复序列在结合 VLDL中所起的作用 ,利用构建的全长VLDL受体 c DNA和缺失 5个重复序列的该受体 c DNA重组表达载体分别导入 CHO细胞中 .RT- PCR可检测到外源性 VLDL受体基因的表达 .受体与配体结合研究表明 ,转染全长 VLDLR重组体的 CHO细胞结合β- VLDL的能力明显高于转染 VLDLR缺失重组体的 CHO细胞 ,表明人VLDL受体在 CHO细胞中能有效表达 ,而缺失 5个重复序列的 VLDL受体基本失去了结合β-VLDL的能力     

人IL35-IgG4(Fc)融合蛋白在CHO/DG44细胞中的稳定表达

本研究利用基因重组技术构建人IL35-IgG4(Fc)融合基因真核表达载体, 稳定转染CHO/DG44细胞并检测重组蛋白的表达。主要采用聚合酶链式反应(PCR)从脂多糖(Lipopolysaccharides, LPS)诱导的人髓性白血病细胞株KG-I cDNA文库中克隆EBI3和IL-12p35 cDNA, 重叠PCR法连接2个片段, 并克隆到IgG4(Fc)- pOptiVEC?-TOPO?载体上,对新构建的IL-35-IgG4 (Fc) pOptiVEC?-TOPO?真核表达载体并进行酶切、测序、PCR鉴定; 脂质体法转染CHO/DG44细胞; RT-PCR检测转染结果, 采用a-MEM-培养基筛选实验组细胞, 对筛选的阳性克隆细胞再进行氨甲喋呤(Methotrexate, MTX)的加压筛选, ProteinG-Agarose纯化阳性克隆培养上清, 免疫印迹检测目的蛋白表达。结果显示IL-35-IgG4 (Fc) pOptiVEC?-TOPO?表达载体稳定转染CHO/DG44细胞并获得阳性克隆; SDS-PAGE电泳得到一条与预期相对分子质量大小相符的蛋白条带; 该蛋白能与羊抗人IgG4抗体特异结合。本实验获得了能够稳定表达具有稳定结构的IL35-IgG4(Fc)融合蛋白的CHO/DG44细胞株。     

Manganese superoxide dismutase is induced by IFN-gamma in multiple cell types. Synergistic induction by IFN-gamma and tumor necrosis factor or IL-1

We have previously characterized more than 20 proteins induced by the immunoregulatory lymphokine IFN-gamma in human fibroblasts by their m.w. and isoelectric points determined in two-dimensional gels. Some of these proteins are induced uniquely by IFN-gamma, whereas others are also induced by IFN-alpha, TNF, or IL-1. Recent technologic advances have allowed us to begin to rapidly identify proteins induced by IFN-gamma and other cytokines by sequencing the induced proteins from blots of preparative two-dimensional gels of total cell lysates. In this study, we show that the approximately 21 kDa, isoelectric point greater than 7 protein induced by IFN-gamma is manganese superoxide dismutase (Mn-SOD), a mitochondrial protective enzyme encoded by a nuclear gene. Mn-SOD is induced by IFN-gamma and also by TNF in all four human cell lines examined: HS153 fibroblasts, ACHN renal carcinoma, A549 lung carcinoma, and A375 melanoma. Induction of Mn-SOD mRNA is a primary, rapid, and dose-dependent response to IFN-gamma. In ACHN renal carcinoma cells, Mn-SOD mRNA and protein are induced synergistically by IFN-gamma in combination with either TNF or IL-1, and the induced protein is enzymatically active. IFN-gamma and TNF together induce Mn-SOD mRNA by more than 100-fold relative to its level in untreated ACHN cells. The induction of Mn-SOD by IFN-gamma and its synergistic induction by IFN-gamma in combination with TNF and IL-1 should protect healthy cells from the toxicity of O2- during an immune response, and may provide a mechanism for selective killing of infected cells.     

Involvement of DNA polymerase beta in repair of ionizing radiation damage as measured by in vitro plasmid assays

Characteristic of damage introduced in DNA by ionizing radiation is the induction of a wide range of lesions. Single-strand breaks (SSBs) and base damages outnumber double-strand breaks (DSBs). If unrepaired, these lesions can lead to DSBs and increased mutagenesis. XRCC1 and DNA polymerase beta (polbeta) are thought to be critical elements in the repair of these SSBs and base damages. XRCC1-deficient cells display a radiosensitive phenotype, while proliferating polbeta-deficient cells are not more radiosensitive. We have recently shown that cells deficient in polbeta display increased radiosensitivity when confluent. In addition, cells expressing a dominant negative to polbeta have been found to be radiosensitized. Here we show that repair of radiation-induced lesions is inhibited in extracts with altered polbeta or XRCC1 status, as measured by an in vitro repair assay employing irradiated plasmid DNA. Extracts from XRCC1-deficient cells showed a dramatically reduced capacity to repair ionizing radiation-induced DNA damage. Extracts deficient in polbeta or containing a dominant negative to polbeta also showed reduced repair of radiation-induced SSBs. Irradiated repaired plasmid DNA showed increased incorporation of radioactive nucleotides, indicating use of an alternative long-patch repair pathway. These data show a deficiency in repair of ionizing radiation damage in extracts from cells deficient or altered in polbeta activity, implying that increased radiosensitivity resulted from radiation damage repair deficiencies.