新型人转录因子hBKLF对K562细胞增殖、分化及血红蛋白合成作用的研究

孕22周的胎肝是胎儿的主要造血器官,其中含有大量与造血相关的调控因子。人碱性Krüppel样因子(humanbasicKrüppel-likefactor,hBKLF)是本研究室从这一时期胎肝cDNA文库中新克隆的转录因子。对其C端的结构分析发现,它含有3个特征性C2H2锌指结构,因此属于KLF转录因子家族。前期的表达谱研究工作显示,hBKLF在成人外周血白细胞、骨髓和胎肝中表达量高,在红系中有表达,这提示它可能与造血相关。本研究以K562细胞为模型,研究hBKLF与造血细胞增殖、分化及血红蛋白合成的关系。构建hBKLF正义及反义真核表达载体,转染K562细胞,经G418筛选4周,得到稳定细胞株;用RT-PCR、Westernblot方法测定转染后K562细胞hBKLF表达水平的变化;以转染空质粒的K562细胞为对照组,在显微镜下直接观察转染正义质粒和反义质粒的两组细胞形态的改变;用MTT法比较增殖速率的变化;用甲基纤维素半固体培养法比较集落形成率的差别;用苯息丁法观察氯高铁血红素(hemin)诱导K562细胞分化后血红蛋白合成水平的差异。结果表明正义质粒和反义质粒经NcoI酶切鉴定构建正确。转染正义质粒的K562细胞(正义组)中hBKLF的mRNA及蛋白质表达水平增加,转染反义质粒的K562细胞(反义组)中hBKLF的mRNA水平降低。增殖活性在反义组、正义组、对照组分别为1.335±0.022、1.067±0.010、1.118±0.014,反义组K562细胞的增殖速率加快,正义组细胞增殖速率减慢(P<0.001)。细胞形态在各组间无明显区别。集落形成率在反义组、正义组、对照组分别为148±13、136±10、141±10,各组间无显著差异(P>0.05)。3组细胞血红蛋白合成水平在hemin诱导后均升高,诱导后血红蛋白升高倍数在对照组、反义组、正义组分别为9.064±1.637、14.360±2.185、4.820±0.404,反义组K562细胞合成血红蛋白能力增加,正义组合成血红蛋白能力下降(P<0.05)。结论hBKLF可以抑制K562细胞的增殖,对血红蛋白合成有负调控作用,但未观察到hBKLF对细胞形态及克隆形成率的影响     

Effect of tetrahydrouridine on metabolism and transport of 1-beta-D-arabinofuranosylcytosine in human cells.

Deamination of cytosine arabinoside (ara-C) by cytidine deaminase is the main mode of inactivation of this drug which can be responsible for ara-C resistance. The present study was undertaken to determine the effect of tetrahydrouridine (THU; a potent inhibitor of cytidine deaminase) on ara-C transport and metabolism in human cells. A rapid transport of ara-C into freshly isolated hepatocytes and an increased intracellular accumulation of the unchanged drug were observed in the presence of 50 micrograms/ml THU. THU inhibited the intracellular deamination of ara-C by 80% and slowed elimination of the compound extracellularly. The intracellular ara-C concentrations achieved after incubation with 1 micrograms/ml ara-C plus 50 micrograms/ml THU are similar to those attained with ara-C (10 micrograms/ml) alone. Treatment of leukemic K562 cells with the combination of THU (50 micrograms/ml) and ara-C (1 micrograms/ml) led to an augmentation of intracellular ara-C triphosphate formation up to twofold.     

龟板、黄芪、丹参和党参诱导K562细胞合成γ珠蛋白的实验研究

本研究探讨龟板、黄芪、丹参和党参对K562细胞γ-珠蛋白合成的影响。以K562细胞为体外模型，用联苯胺染色方法确定龟板、黄芪、丹参及党参4种中药诱导K562细胞血红蛋白表达的剂量效应和时间效应，并用Western blot技术检测血红蛋白F（α2γ2）水平。结果表明：龟板、黄芪、丹参和党参作用于K562细胞6天，联苯胺染色阳性率最高分别可达23．5％、19．8％、15．8％和14．5％；Western blot检测显示血红蛋白F表达增加。结论：龟板、黄芪、丹参及党参在体外可诱导K562细胞1珠蛋白的合成水平增高，从而使血红蛋白F增加。4种中药具有与阳性对照丁酸钠相似的诱导1珠蛋白合成增加的作用。     

Expression of red cell antigens by K562 human leukemia cells before and after induction of hemoglobin synthesis by hemin

We studied the red cell antigens present on K562 human leukemia cells before and after induction of hemoglobin synthesis by hemin. The fetal antigens i, IF, and IT were detected on uninduced cells. While expression of both i and IT antigens increased after hemin induction, expression of IT was closely related to fetal hemoglobin synthesis as determined in experiments in which the induction was reversed. The EnaFR, NVg, and T antigens of glycophorin A were also present on uninduced cells. In contrast, the M and Pra antigens of glycophorin A, the Kell system antigens, and the P1 antigen became detectable only after hemin induction. Antigens of other major red cell systems were not detected.     

The histone deacetylase inhibitor sodium butyrate induces DNA topoisomerase II alpha expression and confers hypersensitivity to etoposide in human leukemic cell lines

The differentiating agent and histone deacetylase inhibitor, sodium butyrate (NaB), was shown previously to cause a transient, 3-17-fold induction of human DNA topoisomerase II alpha (topo II alpha) gene promoter activity and a 2-fold increase in topo II alpha protein early in monocytic differentiation of HL-60 cells. This observation has now been extended to other short chain fatty acids and aromatic butyrate analogues, and evidence is presented that human topo II alpha promoter induction correlates closely with histone H4 acetylation status. Because increased topo II alpha expression is associated with enhanced efficacy of topo II-poisoning antitumor drugs such as etoposide, the hypothesis tested in this report was whether NaB pretreatment could sensitize HL-60 myeloid leukemia and K562 erythroleukemia cells to etoposide-triggered DNA damage and cell death. A 24-72 h NaB treatment (0.4-0.5 mM) induced topo II alpha 2-2.5-fold in both HL-60 and K562 cells and caused a dose-dependent enhancement of etoposidestimulated, protein-linked DNA complexes in both cell lines. At concentrations with minimal effects on cell cycle kinetics (0.4 mM in HL-60; 0.5 mM in K562), NaB pretreatment also modestly enhanced etoposidetriggered apoptosis in HL-60 cells, as determined morphologically after acridine orange/ethidium bromide staining, and substantially increased K562 growth inhibition and poly(ADP-ribose)polymerase cleavage after etoposide exposure. Therefore, a temporal window may exist whereby a differentiating agent may sensitize experimental leukemias to a cytotoxic antitumor agent. These results indicate that histone deacetylase inhibitors should be investigated for etoposide sensitization of other butyrate-responsive hematopoietic and nonhematopoietic tumor lines in vitro and in vivo.     

Cinchona alkaloids as natural fetal hemoglobin inducing agents in human erythroleukemia cells

Pharmacologically mediated reactivation of γ-globin gene with an increase in fetal hemoglobin production, is a cost effective experimental therapeutic intervention for the management of β-hemoglobinopathies. Investigation of new pharmacological agents as HbF inducers from natural resources is desirable to develop safe and effective HbF inducers. We evaluated selected cinchona alkaloids (cinchonidine and quinidine) for their potential of erythroid differentiation and augmentation of fetal hemoglobin production. K562 cells were used as in vitro experimental model. Erythroid differentiation of K562 cells was studied using a benzidine assay, and total hemoglobin was estimated through a calorimetric method. Whereas, quantitative real-time PCR (qRT-PCR) was used to analyse γ-globin gene expression, and flow cytometry and immunofluorescence microscopy for evaluating HbF production. Cinchona alkaloids showed dose dependent erythroid differentiation, time driven cellular proliferation, with kinetics of hemoglobin accumulation in K562 cells. The findings of qRT-PCR showed an increase in expression of γ-globin mRNA content (3.17-fold in cinchonidine and 2.03-fold increase in quinidine treated K562 cells), accompanied by an increase in fetal hemoglobin production. Altogether, this study demonstrates that cinchona alkaloids can be used as therapeutic agents in treating β-thalassemia after further biological investigation.

Pharmacologically mediated reactivation of γ-globin gene and fetal hemoglobin (HbF) induction by cinchona alkaloids; a cost effective experimental therapeutic intervention for the efficient management of β-thalassemia.     

联合诱导法对K562细胞红系分化及其相关基因和膜蛋白表达的影响

目的优化K562细胞体外红系诱导分化条件,分析红系相关基因和膜蛋白的表达,探讨K562细胞的分化潜能。方法采用红系诱导联合培养法,优化丁酸钠、促红细胞生成素、氯化高铁血红素、枸橼酸铁等成分组合和剂量组合。鉴定指标选用红系血红素合成酶(eALAS)mRNA和粒系bcr/ablmRNA表达丰度分析、细胞形态学观察、联苯胺染色阳性率计数。红系分化进一步鉴定指标选用Real-timePCR检测10种红系分化相关基因的表达;流式细胞术测定红系细胞膜标志物。结果K562细胞诱导120h后,联苯胺染色阳性率达100%;α、β收缩蛋白(spectrinα、β)、带3蛋白(band3)、eALAS、整合素相关蛋白(CD47)、RhD血型抗原(RhD)、锚蛋白(ankyrin)、红细胞膜带4.2蛋白(EPB4.2)的mRNA水平为对照组的8.05、14.58、22.87、14.52、26.53、3.48、2.71、1.94倍,而bcr/ablmRNA水平为对照组的39%;红系膜蛋白CD47、band3、RhD水平明显增高(P<0.01),血型糖蛋白A(GPA)无明显差异。结论优化组合体外红系诱导分化法可使K562细胞稳定向红系分...     

Growth inhibition by STI571 in combination with radiation in human chronic myelogenous leukemia K562 cells

Altered radiation responses by STI571 (Imatinib, Glivec), a specific inhibitor of the tyrosine kinase activity of Bcr-Abl, was assessed in K562 chronic myelogenous leukemia cells using growth inhibition and colony formation assays. Flow cytometry, Western blotting, and microscope observation were used to determine cell cycle redistribution, erythroid differentiation, apoptosis, necrosis, senescence, and expression and phosphorylation of effectors downstream from Bcr-Abl as endpoints. STI571 (> or =24-h contact) retarded the growth of K562 cells and elicited reduction in the G(2)-phase content due to an efficient arrest in early S phase rather than to the disruption of the G(2) checkpoint as confirmed by analysis of Lyn and CDK1 phosphorylation. STI571 brought about the inhibitory dephosphorylation of Bcr-Abl and STAT5, but the expression of DNA-PKcs and Rad51 was unaffected and the interaction between radiation and STI571 was strictly additive with regard to induction of apoptosis. Overall STI571 interacted cooperatively with radiation to retard the growth of K562 cells but did not affect intrinsic radiosensitivity. However, STI571 and radiation acted antagonistically with each other with regard to induction of senescence and erythroid differentiation.     

人类ERMAP基因在诱导K562细胞向红系和巨噬系细胞分化过程中表达的研究

为了探讨人类ERMAP基因在红细胞分化发育过程中的作用,以Ara-C诱导K562细胞向红系方向分化,以十二氟波酯钠盐(TPA)诱导K562细胞向巨噬系方向分化,用荧光定量PCR检测上述过程中人类ERMAP基因表达量的变化。结果发现:终浓度为2.5×10-6mmol/L/L及1.0×10-6mmol/L/L的Ara-C可诱导K562细胞向红系方向分化,在此过程中人类ERMAP基因的表达量逐渐增加;终浓度为2.0×10-6mmol/L/L及1.0×10-6mmol/L/L的TPA可诱导K562细胞向巨噬系方向分化,在此过程中人类ERMAP基因的表达量无变化。结论:人类ER-MAP基因与红系分化增殖密切相关。     

抑制钠氢交换蛋白1促进低氧诱导的K562细胞分化

本研究主要探讨低氧微环境对慢性髓系白血病细胞系K562分化的影响及钠氢交换蛋白1(NHE1)在该过程中的作用。利用低氧模拟物CoCl2或于低氧(2%O2、5%CO2和93%N2)环境中培养K562细胞,应用激光共聚焦显微镜测定细胞内pH值(intracellular pH,pHi),瑞氏染色观察细胞形态,实时定量RT-PCR检测基因表达,Western blot技术检测MAPK磷酸化水平的改变。结果表明:与对照组相比,低氧培养的K562细胞表现出成熟相关的形态学改变,并伴随CCAAT/增强子结合蛋白(C/EBPα)的mRNA水平上调;特异性NHE1抑制剂Cariporide预处理能够促进低氧诱导的K562细胞分化,Cariporide处理后K562细胞的P38和ERK5蛋白激酶磷酸化水平显著增强。结论 :低氧及低氧模拟物能够诱导K562细胞系分化,抑制NHE1活性协同促进低氧诱导的K562细胞分化,其机制可能是通过增强细胞内MAPK蛋白激酶磷酸化水平促进分化。     

Hydroxyurea induces fetal hemoglobin by the nitric oxide-dependent activation of soluble guanylyl cyclase

Hydroxyurea treatment of patients with sickle-cell disease increases fetal hemoglobin (HbF), which reduces hemoglobin S polymerization and clinical complications. Despite its use in the treatment of myeloproliferative diseases for over 30 years, its mechanism of action remains uncertain. Recent studies have demonstrated that hydroxyurea generates the nitric oxide (NO) radical in vivo, and we therefore hypothesized that NO-donor properties might determine the hemoglobin phenotype. We treated both K562 erythroleukemic cells and human erythroid progenitor cells with S-nitrosocysteine (CysNO), an NO donor, and found similar dose- and time-dependent induction of gamma-globin mRNA and HbF protein as we observed with hydroxyurea. Both hydroxyurea and CysNO increased cGMP levels, and the guanylyl cyclase inhibitors ODQ, NS 2028, and LY 83,538 abolished both the hydroxyurea- and CysNO-induced gamma-globin expression. These data provide strong evidence for an NO-derived mechanism for HbF induction by hydroxyurea and suggest possibilities for therapies based on NO-releasing or -potentiating agents.     

联合培养法优化K562细胞红系诱导分化及红系相关基因和膜蛋白表达分析

目的 优化K562细胞体外红系诱导分化条件,分析红系相关基因和膜蛋白的表达,探讨K562细胞的分化潜能.方法 采用红系诱导联合培养法,优化诱导试剂丁酸钠、红细胞生成素、氯化高铁血红素等成分组合和剂量组合.诱导效率鉴定指标选用红系ALAS mRNA和粒系bcr/abl mRNA表达丰度分析、细胞形态学观察、联苯胺染色阳性率计数.红系分化进一步鉴定指标选用Realtime-PCR检测10种红系分化相关基因的表达;流式细胞术测定红系细胞膜标志物.结果 优化红系诱导组合联合培养K562细胞120 h后,联苯胺染色计数阳性细胞可达100%.Realtime-PCR检测Spectrina、Spectrinβ、band3、eALAS、CD47、RhD、EPB4.2的mRNA水平分别为对照组的8.05、14.58、22.87、14.52、26.53、3.48、1.94倍,而ber/abl mRNA水平为对照组的0.39倍.流式细胞术测定红系膜蛋白CD47,band3、RhD水平明显增高(P<0.01),GPA无明显差异.结论优化组合体外红系诱导分化法可使K562细胞稳定向红系分化,良好细胞状态利于转外源基因操作,进行红系统疾病研究.RhD比GPA更早在红系细胞表达,可作为早期红系特异标记.     

组蛋白去乙酰化酶抑制剂对HL-60细胞和K562细胞的抗肿瘤作用

为了观察组蛋白去乙酰化酶抑制剂丙戊酸（VPA）、曲古抑菌素（TSA）对K562细胞和HL-60细胞的抗肿瘤作用以及它们同全反式维甲酸（ATRA）之间的协同效应,采用绘制细胞生长曲线,计算半数抑制浓度（IC50）以及集落抑制试验等方法观察VPA,TSA以及全反式维甲酸（ATRA）在不同浓度或不同组合条件下对HL-60细胞和K562细胞的增殖抑制作用.采用细胞化学染色、分化抗原检测、细胞周期测定、联合NBT与MTT还原试验计算A（NBT）/A（MTT）值等方法分析细胞的分化或凋亡特点.结果显示,在体外培养体系中,VPA对HL-60细胞的IC50值低于对K562细胞的IC50值.ATRA能明显增强VPA、TSA对HL-60细胞以及VPA对K562细胞集落形成的抑制.HL-60经VPA处理后出现粒系表型,NBT还原率增加,CD11b表达增强,而K562细胞未显示分化迹象.结论：VPA和TSA抑制HL-60细胞增殖,VPA诱导HL-60细胞向粒系分化,这些作用均能被ATRA增强;VPA和TSA对K562细胞增殖抑制作用较弱,不能诱导K562细胞分化.     

硼替佐米体外诱导K562细胞凋亡的作用不受骨髓间充质干细胞的影响

本研究探讨蛋白酶体抑制剂硼替佐米在有或无骨髓间充质干细胞(mesenchymal stem cells)条件下对白血病细胞株K562促凋亡作用,以及对MSC和K562细胞的黏附分子VCAM-1表达的影响.建立MSC和K562细胞的共培养体系,以终浓度为50 mnol/L的绷替佐米处理K562细胞4-24小时,应用Annexin-V/PI双染法检测K562细胞凋亡,半定量RT-PCR检测VCAM-1 mRNA的表达.结果显示,硼替佐米可诱导K562细胞凋亡,并呈现时间依赖性;共培养组调亡细胞比例与单独培养组相比无显著差异;K562细胞与MSC共培养可诱导K562细胞表达VCAM-1,MSC在共培养前后表达VCAM-1无明显变化.硼替佐米作用24小时后,K562细胞表达VCAM-1消失,MSS表达VCAM-1明显下降.结论:硼替佐米在MSC存在的情况下依然可诱导白血病细胞凋亡,提示硼替佐米可拮抗MSC对白血病细胞的保护作用.     

Bcl-6在K562细胞的表达及其在髓系分化诱导机制中的作用

本研究探讨诱导K562细胞分别向髓系不同细胞系分化时bcl-6表达的变化,并分析其机制。用Western blot检测以十四烷酸佛波醇-13-乙酯（tetradecanoylphorbol 13-acetate,TPA）、羟基脲（hydooxyurea,Hu）及六甲基双乙酰胺（hexamethylenebisacetamide,HMBA）为诱导剂分别诱导K562细胞向巨核细胞系、红细胞系及巨噬细胞系分化时bcl-6表达变化,用PCR、克隆、直接DNA测序方法分析bcl-6基因5′调控区序列变异情况。结果表明,BCL-6蛋白仅在TPA诱导K562细胞向巨核细胞系分化时表达上调,其5′调控区序列未发现有突变发生。结论：bcl-6可能是调控K562细胞向髓系不同细胞系分化的关键基因之一,在TPA诱导的K562细胞向巨核细胞分化过程中发挥重要作用,其表达上调不伴有调控区基因突变,     

Effects of recombinant human cytokines on cytarabine activity in K562 human myeloid leukaemia cells.

The K562 cell line provides a unique population of primitive human myeloid leukaemia cells which can be induced to differentiate along the erythroid, granulocytic, macrophage and megakaryocytic lineages in response to several agents. Cytarabine is not only the most widely used drug in the treatment of myeloid leukaemia but also the most effective agent in K562 cells. The effects of five recombinant human cytokines - interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-alpha, interferon-beta and interferon-gamma on cytarabine-induced growth inhibition and differentiation of K562 cells was studied in liquid suspension cultures. GM-CSF and to a lesser extent IL-3 enhanced the antiproliferative effect of cytarabine in K562 cells, whereas the three interferons reduced it. The efficacy of cytarabine in inhibiting the growth of K562 cells was doubled by its combination with GM-CSF or IL-3 but was halved by its combination with interferons. The five cytokines did not significantly affect cytarabine-induced erythroid differentiation of K562 cells. The present results appear to favour the use of GM-CSF and IL-3 but not of interferons in future treatment strategies based on a combined cytokine and chemotherapy approach for myeloid leukaemia.     

Sonic hedgehog signaling regulates Bcr-Abl expression in human chronic myeloid leukemia cells

Purpose

Bcr-Abl fusion protein activates tyrosine kinase, resulting in the proliferation of leukemia cells, especially chronic myeloid leukemia (CML) cells. Imatinib (IM) effectively targets Bcr-Abl tyrosine kinase, but development of resistance to IM occurs with varying frequency.

Methods

Elucidation of the common regulatory pathway upstream of Bcr-Abl in IM-sensitive and IM-resistant CML cells is important for developing novel therapeutics against CML.

Results

This study demonstrated that IM preferentially inhibited the viability and Bcr-Abl expression in IM-sensitive K562 (K562) cells, but not in Bcr-Abl overexpressing IM-resistant K562 (K562R) cells. Both K562 and K562R cells expressed Shh preproprotein, cleaved Shh C-terminal and N-terminal peptides, as well as mRNA level of major Shh signaling molecules, including sonic hedgehog (Shh), patched (PTCH), smoothened (Smo) and Gli-1. Moreover, Gli-1 translocation into nucleus was evident in these two cell lines, suggesting that both K562 and K562R cells possess activated and major components of the Shh signaling pathway. Silencing of Gli-1 by interference RNA was accompanied by inhibition of Bcr-Abl protein expression. Pharmacological suppression of Bcr-Abl expression was restored by the Smo agonist purmorpharmine. Treatment of Shh peptide in both K562 and K562R cells not only increased Shh and Gli-1 expression, but also up-regulated Bcr-Abl expression. Resveratrol, a known Bcr-Abl inhibitor, reduced Gli-1 activation and inhibited the viability of CML cells.

Conclusions

Shh signaling may regulate Bcr-Abl expression in human chronic myeloid leukemia cells. Novel compounds inhibiting both Shh signaling and Bcr-Abl expression, such as resveratrol, may have potential to be effective agents against CML independent of IM resistance.     

三丁酸甘油酯诱导白血病细胞分化及凋亡机制的研究

为了探讨组蛋白去乙酰化酶抑制剂三丁酸甘油酯（tributyrin,TB）诱导NB4、K562白血病细胞分化和（或）凋亡的作用机制,利用Western blot方法及逆转录聚合酶链反应（RT-PCR）检测TB作用前后NB4、K562细胞组蛋白H3乙酰化水平以及p21^WAF1表达量的改变.结果表明：NB4（或K562）细胞经TB0.1 mmol/L（或TB 0.5 mmol/L）作用16小时后可见组蛋白H3乙酰化水平明显上升,并有剂量依赖效应.NB4、K562细胞经TB 0.1 mmol/L作用后可见p21^WAF1 mRNA表达上调,且具有剂量依赖效应.p21^WAF1 mRNA的这种上调开始于TB作用2小时后,16小时达高峰,可维持48小时.结论：TB诱导NB4、K562细胞发生分化和（或）凋亡的机制与TB引起细胞组蛋白高乙酰化和继而上调p21^WAF1表达有关.     

酪氨酸激酶抑制剂HerbimycinA联合化疗药物对K562细胞凋亡…

探讨慢性髓细胞白血病细胞抗凋亡机制和诱导细胞凋亡的有效方法。方法：采用Ｋ５６２细胞培养，观察酪氨酸激酶抑制剂ＨｅｒｂｉｍｙｃｉｎＡ联合化疗药物对细胞凋主恨的影响，探讨ＨＭＡ对ＣＭＬ细胞的作用。结论ＨＭＡ通过抑制ＣＭＬ细胞内酪氨酸激酶活性促进细胞凋亡而增加对化疗药物的敏感性，表明酪氨酸激酶抑制剂作为治疗ＣＭＬ药物具有潜在应用价值。