SHIP基因真核表达载体的构建、鉴定及对白血病细胞系K562的抑制作用

目的 构建真核表达质粒pCAC-IRESSHIP-GFP,并观察其在K562细胞中的表达. 方法 将SHIP基因的RT-PCR产物克隆入载体pCAG-IRES-GFP,经酶切、鉴定及测序分析,构建pCAG-IRESSHIP-GFP重组真核表达质粒.实验设置3个组:K562组(未转染)、K562/IRES组(转染宅载体pCAG-IRGA-GFP),K562/SHIP)组(转染重组质粒pCAC-IRES-SHIP-GFP).荧光显微镜和流式术榆测重组质粒的转染效率;Western blotting检测各组SHIP蛋白的表达及Akt磷酸化水平变化;MIT法和流式术分析SHIP基凶转染对细胞增殖的影响. 结果 重组质粒pCAG-IRESSHIP-GFP已成功载人SHIP的全长编码基凶,序列测定的结果与预期设计完全一致.荧光显微镜在K562/SHIP组町见绿色荧光,转染效率为4&2%±6.6%.Westem blotting显示K562/SHIP组有明显的SHIP蛋白表达,且p-Akt-308和p-Akt-473的水平(分别为0.182和0.381)较K562/IRES组(0.361和0.716)和K562组(0.365和0.725)明显下降(P＜0.01).流式术分析显示K562/SHIP组细胞生长减慢,G0/G1期细胞增多、G2/M期细胞减少,增殖指数降低. 结论 成功构建了3 585bp的SHIP基因真核表达质粒pCAG-IRES-SHIP-GFP,并在K562细胞中表达.外源性SHIP基因转染能使K562细胞增殖受抑,原因可能与Akt的磷酸化下调有关.     

2-甲氧基雌二醇对K562细胞L-选择素及其基因表达的影响

目的 观察2-甲氧基雌二醇(2-ME)对慢性粒细胞白血病细胞系K562细胞L-选择素表达的影响,并通过分析L-选择素与bcr/abl融合基因表达的关系探讨2-ME的作用机制.方法 实验分3组.①对照组:培养基中不含2-ME;②实验组:分别用1、2、4、8、16μmol/L的2-ME处理K562细胞36h,观察各项指标的变化;③阴性对照组:培养基中以无RNase水代替K562细胞.用流式细胞术(FCM)检测K562细胞L-选择素蛋白表达;半定量RT-PCR检测L-选择素mRNA的表达;SYBR Green Ⅰ实时荧光定量RT-PCR检测bcr/abl融合基因的mRNA表达.结果 不同浓度的2-ME与K562细胞作用36h后,L-选择素蛋白及其mRNA的表达量均呈剂量依赖性增加,与对照组比较均有显著性差异(P＜0.05,P＜0.01);L-选择素mRNA与其蛋白表达之间呈正相关(r=0.758,P=0.004).L-选择素mRNA与bcr/abl融合基因mRNA之间呈负相关(r=-0.968,P=0.001).结论 2-ME可能通过抑制K562细胞bcr/abl融合基因的表达,增加L-选择素mRNA及其蛋白表达水平,改善或恢复K562细胞的黏附缺陷.     

JTV1对K562细胞增殖和凋亡的影响及其机制

目的观察上调JTV1基因的表达对人白血病K562细胞系增殖与凋亡的影响并探讨其机制。方法将携带有JTV1基因的pcDNA3.1-JTV1载体转染人K562细胞作为阳性转染组,转染pcDNA3.1空载体作为空载体转染组,未转染的K562细胞为未转染组。通过集落形成实验检测各组K562细胞的增殖能力,采用流式细胞术与Annexin-PI双染色结合分析细胞周期和细胞凋亡率,同时采用RT-PCR法检测JTV1基因及凋亡相关基因Bcl-2、Bax、C-myc mRNA水平的变化,采用Western blotting检测基因JTV1及凋亡相关基因Bcl-2、Bax、C-myc蛋白水平的变化。结果集落形成实验结果显示上调JTV1基因表达后K562细胞的增殖能力明显降低。流式细胞术与Annexin-PI双染色检测结果显示,与空载体转染组及未转染组相比,阳性转染组K562细胞的G期细胞比例明显升高(P<0.05);阳性转染组中Bax基因的mRNA水平和蛋白水平较空载体转染组及未转染组均明显上升,而Bcl-2基因和C-myc基因的mRNA水平和蛋白水平则明显下调(P<0.05)。结论 JTV1基因过表达可能通过抑制基因Bcl-2和C-myc的表达增强基因Bax的表达,从而抑制K562细胞系的增殖并促进其凋亡。     

新的白血病相关基因LRP15真核表达载体构建及在K562细胞中的表达

 目的构建LRP15基因开放阅读框架(ORF)序列的真核表达载体,并观察其在K562细胞中的表达情况.方法采用RT-PCR方法自1例白血病患者中克隆LRP15cDNA片段,将目的基因LRP15克隆入pGEM-T载体中并进行酶切鉴定和DNA序列测定.将鉴定过的DNA片段插入真核质粒pcDNA3.1(+),构建真核表达载体pcDNA-LRP15.脂质体介导法将其转染K562细胞,72 h以RT-PCR方法检测转染细胞中LRP15基因的表达情况.结果酶切鉴定和序列分析证实,重组质粒含有人LRP15基因ORF序列;转染实验表明LR15基因能在K562细胞中表达.结论成功构建LRP15基因真核表达载体,并在K562细胞中获得表达,为进一步研究LRP15基因的功能奠定了基础.     

人参总皂甙对K562细胞凋亡相关基因XIAP和Survivin表达的影响

目的探讨人参总皂甙（TSPG）对K562细胞凋亡相关基因XIAP和Survivin表达的影响。方法采用四唑盐比色试验（MTT法）检测TSPG对K562细胞增殖的影响;Hoechst33342/PI荧光染色法观察K562细胞的凋亡;逆转录-聚合酶链反应（RT-PCR）检测K562细胞XIAP和Survivin基因的mRNA的表达。结果TSPG在低浓度时有促进细胞增殖的作用（P〉0.05）,高浓度时逐渐出现抑制作用（P〈0.05）;荧光技术显示不同浓度TSPG培养K562细胞后24和48小时后凋亡细胞数目明显增多（P〈0.01）;TSPG下调K562细胞XIAP和Survivin基因的表达（P〈0.01）。结论TSPG通过下调K562细胞XIAP和Survivin基因的表达从而诱导K562细胞凋亡。     

髓细胞白血病β—catenin表达及与外源性Wnt5a的作用关系

目的调查β-catenin在髓细胞白血病标本及细胞株中的表达,明确外源性Wnt5a与K562细胞β-catenin表达的关系。方法首先以RT-PCR和免疫组化检测β-catenin在髓细胞白血病标本及细胞株中的表达,再以Wnt5a条件培养液处理K562细胞,然后用Westernblot检测β-catenin表达变化。结果β-catenin在髓细胞系白血病标本及细胞株中有普遍表达,但外源性Wnt5a不能明显下调K562细胞β-catenin表达。结论外源性Wnt5a对K562细胞Wnt／β-catenin信号传导途径无明显抑制作用。     

慢性粒细胞性白血病中SHIP1基因的表达变化及机制探讨

目的观察SHIP1基因在慢性粒细胞性白血病(CML)患者中的表达变化,并通过特异性小干扰RNA(siRNA)封闭K562细胞株BCR-ABL基因的表达,探讨BCR-ABL基因表达对SHIP1基因的影响。方法应用RQ-PCR方法检测CML患者骨髓、正常人外周血白细胞及白血病细胞株K562中SHIP1基因表达的差异。另取K562细胞分为3组:空白对照组(不加任何干扰成分);非特异性siRNA处理组(加非特异性siRNA);特异性siRNA处理组(加入特异性siRNA封闭BCR/ABL融合基因),应用RQ-PCR及Western blot方法分别检测3组中BCR/ABL、SHIP1基因的mRNA及其相应蛋白P210(BCR/ABL编码)、P145(SHIP1基因编码)的表达,并比较各组中表达水平的变化。结果CML患者骨髓白细胞和K562细胞中SHIP1基因的表达明显低于正常人的外周血白细胞。特异性siRNA处理组中BCR-ABL基因mRNA和P210蛋白的表达水平明显下降,SHIP1基因mRNA和P145蛋白表达水平随BCR-ABL表达下降而增加;非特异性siRNA处理组与空白组相比无明显差异。结论CML患者SHIP1基因的表达低于正常人;特异性siRNA能够抑制BCR-ABL基因的表达;BCR-ABL基因能抑制SHIP1基因及其蛋白表达。     

ASPP1基因mRNA在肿瘤细胞株中的表达初探

目的 建立p53凋亡刺激蛋白基因(ASPP1)mRNA表达水平的RT-PCR测定方法;并应用该方法测定ASPP1 mRNA在正常人单核细胞与白血病细胞株Jurkat,HL-60、K562中的表达水平.方法 应用单核细胞分离液分离正常人血液单核细胞,用RPMI 1640培养液培养细胞株Jurkat、HL-60.K562,所得细胞用Tripure分离试剂提取总RNA,用RT-PCR扩增.取ASPP1基因和β-actin基因的扩增产物各10μl,行溴钇锭染色,在琼脂糖凝胶上进行电泳,检测AsfIP1 mRNA的表达水平.对ASPP1基因表达量与β-actin表达量的比值进行比较,从而计算ASPP1在各细胞株的相对表达量.结果 在正常人单核细胞和各自血病细胞株中均有ASPP1基因的mRNA表达,ASPP1与β-actin的比值在正常人单核细胞中为0.545±0.019,而在白血病细胞株Jurkat、HL-60、K-562中分别为0.155±0.081、0.199±0.016、0.191±0.015,可见ASPP1 mRNA在正常细胞中的表达水平比在白血病细胞株Jurkat、HL-60、K-562中的表达水平高(P＜0.01).结论 在肿瘤的发生、发展中,ASPP1与p53共同作用,形成ASPP-p53复合物作用于原凋亡基因启动子,能特异性增强p53结合DNA的能力,促进p53诱导细胞凋亡的作用.ASPP1的这种功能在抑制正常细胞恶性转化的过程中有重要作用.     

黄芪的含药血清诱导K562细胞表达^Gγ-mRNA和合成HbF

目的研究黄芪对K562细胞的^Gγ-珠蛋白基因表达的作用。方法以K562细胞为体外模型，用联苯胺染色方法来确定黄芪的含药血清诱导K562细胞向红系分化的作用；用RT—PCR方法研究黄芪的含药血清诱导K562细胞^Gγ-珠蛋白mRNA的表达；用Western Blot方法研究黄芪的含药血清诱导K562细胞HbF的合成。结果黄芪的含药血清作用于K562细胞5d后联苯胺染色阳性率达19．8％；同时伴有^Gγ-珠蛋白mRNA的表达的增加（最高可达3．6倍）和HbF的合成的增加，与丁酸钠组比较，黄芪组诱导K562细胞^Gγ-珠蛋白基因mRNA的表达可以持续3～5d，而丁酸钠组只有1d。结论黄芪有望成为一种有效的γ蛋白基因诱导剂。     

维甲酸诱导白血病细胞分化对WT1基因表达的影响

为了解WT1基因的表达与白血病细胞分化的关系以及WT1基因在白血病细胞分化中的作用。本文采用全反式维甲酸（ATRA）诱导HL-60、K562细胞系分化,然后应用NBT还原试验和RT-PCR方法分别测定细胞分化程度笔WT1基因表达的变化。结果发现,ATRA作用5天后可以诱导HL-60细胞分化,WT1的表达随着HL-60细胞的分化而降低;ATRA对K562细胞无诱导分化作用。其WT1的表达也无显著变化。提示WT1基因的表达与造血细胞分化呈负相关,与白血病细胞的分化有密切联系。     

用99^Tc^m-MIBI细胞内动力学变化评价多药耐药及逆转剂作用

目的用99^Tc^m-甲氧基异丁基异腈（MIBI）细胞摄取变化探测肿瘤细胞P-糖蛋白（P-gp）表达及多药耐药（MDR）逆转剂存在时P-gP功能的变化。方法人类髓系白血病K562细胞及其耐药细胞株K562／D（高度表达P-gP）各2×10^6个,分别加入99^Tc^m-MIBI 8 MBq,观察不同时间99^Tc^m-MIBI摄取清除情况,后在不同质量浓度MDR逆转剂环孢素A（CsA,0．1,0．2和0．4μg／ml）存在时,观察K562细胞及K562／D细胞对99^Tc^m-MIBI摄取变化。2种细胞株间及采用逆转剂前后间比较采用t检验,组间比较采用q检验。结果K562细胞及K562／D细胞99^Tc^m-MIBI摄取值分别为1．559±0．529及0．107±0．036,K562细胞比K562／D细胞高15倍。不同质量浓度CsA作用下K562细胞对99^Tc^m-MIBI的摄取较不用逆转剂略有增加,但差异无统计学意义（t=0．25,0．55,0．24,P〉0．05）;K562／D细胞99^Tc^m-MIBI摄取均较不用逆转剂时明显增加,0．1,0．2和0．4μg／ml CsA作用后分别增加106％,148％及163％（t=4．35,4．83,5．88,P〈0．05）。结论以99^Tc^m-MIBI细胞内摄取变化可评价P-gP的功能及逆转剂CsA作用。     

Loss of mitochondrial membrane potential and caspase activation enhance apoptosis in irradiated K562 cells treated with herbimycin A

PURPOSE: We previously reported that herbimycin A (HMA) alters the mode of cell death of K562 cells induced by radiation and enhanced their radiosensitivity. In the present study, we explored the apoptosis-inducing activity of HMA and the fundamental mechanism via which it regulates radiation-induced cell death. MATERIALS AND METHODS: Chronic myelogenous leukemia (CML) cell line K562 was used. For X-irradiation and drug treatment, cells were plated at approximately 2x10(5) cells/ml. Exponentially growing cells were treated with 10 Gy of X-ray using a 6-MeV X-ray machine at a dose rate of 200-300 cGy/min. The cells were treated with 0.25 microM HMA immediately after irradiation and HMA remained for the entire culture period. The modes of cell death were discriminated by morphological changes, analysis of cell cycle, analysis of the mitochondrial events, and the expression of apoptosis-related proteins. RESULTS: Our data demonstrates that radiation induced a significant time-dependent increase of cell death and failed to sustain a prolonged G2 arrest in K562 cells. Radiation-induced cell death caused the accumulation of cyclinB1 and weak nuclear fragmentation, suggesting a mitotic catastrophe. This mitotic catastrophe was dependent upon the mitochondrial permeability transition pore (PTP) opening and was independent of caspase-3. In contrast, K562 cells treated with radiation and HMA had an accelerated cell death and induced a p53-independent apoptosis. This apoptotic pathway was dependent upon an initial hyperpolarization of the mitochondrial inner membrane, following the release of cytochrome c and subsequent caspase-3 activation. CONCLUSIONS: Two mechanisms of radiation-induced cell death in K562 cells, mitotic catastrophe and apoptosis, are regulated through distinct pathways, mitochondria and caspase-independent and -dependent, respectively. The findings of this study may provide new insights into improving the efficiency of radiotherapy in CML patients.     

The expression and intranuclear distribution of nucleolin in HL-60 and K-562 cells after repeated, short-term exposition to rotating magnetic fields

PURPOSE: The aim of the study was to analyze the influence of rotating magnetic fields (RMF) on the expression and intranuclear distribution of nucleolin, protein involved in ribosome biosynthesis, in HL-60 (acute promyelocytic leukemia) and K-562 (chronic myelogenous leukemia) established human cell lines. MATERIALS AND METHODS: Cells were exposed to RMF for two chosen states of the magnetic field induction: B=10 mT and B=20 mT in experimental set-up for 30 min with 24-h intervals for four days. Cytospin slides were prepared and expression of nucleolin was detected using monoclonal antibodies. Parameters of fluorescence related to nucleolin were measured in at least 2000 tumor cells in each slide by a laser scanning cytometer with an argon laser. Percentages of cells in different phases of cell cycle were also analyzed. RESULTS: The repeated exposition of cells to RMF caused significant increase in nucleolin expression in the whole nucleus and in the nucleolin aggregates (NUA). The redistribution of nucleolin measured by changes in number of NUA was also observed. The exposition of both cell lines studied to RMF did not alter the cell cycle. CONCLUSION: The nucleolin is responsive to RMF in HL-60 and K-562. The increase of its expression may indicate a reaction of cells to RMF and it may influence their other biological properties.     

c-CBL是连接BCR/ABL与磷脂酰肌醇-3激酶的桥梁

目的 :探讨原癌基因产物c CBL在P2 10BCR/ABL激发的异常信号转导中的作用。方法 :以慢性粒细胞白血病细胞株K56 2细胞为研究对象 ,用反义技术、免疫沉降和蛋白免疫印迹分析 ,研究c CBL、BCR/ABL和磷脂酰肌醇 3激酶 (phosphatidylinositol 3kinase ,PI3K)三者之间的相互关系。结果 :在K56 2细胞内 ,c CBL、BCR/ABL与PI3K可能形成一种三分子复合物 ,c cbl反义RNA转染细胞后BCR/ABL免疫沉降物中PI3K含量减少 59%左右 ,而BCR/ABL自身酪氨酸磷酸化水平无明显改变。结论 :原癌基因产物c CBL对BCR/ABL酪氨酸激酶活性无反向调节作用 ,它是连接BCR/ABL与PI3K之间的重要桥梁分子。     

激光激发5-氨基乙酰丙酸己酯对人红白血病耐药/非耐药细胞株的杀伤效应研究

目的探讨5-氨基乙酰丙酸己酯-光动力疗法(He-ALA-PDT)对人红白血病细胞株K562及其耐阿霉素细胞株K562/ADM的杀伤效应。方法实验设4组:PDT组(加光敏剂并接受光照)、激光组(不加光敏剂只接受光照)、暗毒性组(只加光敏剂而不接受光照)、正常对照组(不加光敏剂且不接受光照)。用不同浓度(0.025、0.1、0.4、1.6mmol/L)的He-ALA避光孵育细胞,给予不同功率密度(4.5、9、18、36J/cm2)的630nm波长激光照射后,继续培养12h,观察细胞形态学变化,以CCK8法测定细胞存活率,采用甲基纤维素培养体系分析白血病细胞克隆形成能力的变化。结果暗毒性组、激光组均未对细胞产生明显杀伤作用,而PDT组能明显杀伤白血病细胞,且细胞存活率随He-ALA浓度和激光功率密度的增加而降低,且在相同条件下,K562细胞的存活率显著低于K562/ADM细胞(P<0.05)。PDT组的集落形成率明显低于正常对照组(P<0.001),且与K562/ADM细胞相比,K562细胞的集落形成率降低程度更为显著(P<0.001)。结论He-ALA-PDT可杀伤K562、K562/ADM细胞,并显著降低白血病细胞的克隆形成能力;K562/ADM细胞对PDT的反应不如K562细胞敏感。     

γ-catenin在白血病细胞中的表达

目的检测白血病骨髓标本及白血病细胞株中γ-catenin的表达情况,探讨γ-catenin在白血病细胞中的作用。方法以RT-PCR检测76例白血病骨髓标本、8例正常骨髓标本和白血病细胞株K562、HL-60、U-937、Jurkat中γ-catenin的mRNA表达情况,以Western blot和免疫细胞化学法检测上述白血病细胞株中γ-catenin蛋白表达及其分布情况。结果正常骨髓标本中γ-catenin表达阳性率为0（0/8）,急性髓细胞白血病（AML）骨髓标本中γ-catenin表达阳性率为40.0%[12/30,其中M2型的阳性率为50.0%（7/14）],慢性髓细胞白血病（CML）骨髓标本中γ-catenin表达阳性率为13.6%（3/22）,急性淋巴细胞白血病（ALL）和慢性淋巴细胞白血病（CLL）骨髓标本中γ-catenin表达阳性率均为25.0%（3/12）。白血病组γ-catenin表达阳性率与正常组相比,AML组有显著性差异（P〈0.05,其中M2型最为显著）,其余各组均无显著性差异（P〉0.05）。RT-PCR及免疫组化检测可见HL-60和K562细胞γ-catenin呈强阳性,U-937和Jurkat细胞呈弱阳性表达,且γ-catenin主要表达于细胞质中。Western blot检测见K562和HL-60细胞γ-catenin呈阳性表达,而U-937和Jurkat细胞未见表达。结论作为细胞内信号传导分子,γ-catenin表达于AML组、HL-60及K562细胞中,可能与急性髓细胞白血病（特别是M2型）的发生有关。     

Loss of mitochondrial membrane potential and caspase activation enhance apoptosis in irradiated K562 cells treated with herbimycin A

Purpose: We previously reported that herbimycin A (HMA) alters the mode of cell death of K562 cells induced by radiation and enhanced their radiosensitivity. In the present study, we explored the apoptosis-inducing activity of HMA and the fundamental mechanism via which it regulates radiation-induced cell death.

Materials and methods: Chronic myelogenous leukemia (CML) cell line K562 was used. For X-irradiation and drug treatment, cells were plated at approximately 2 × 10⁵ cells/ml. Exponentially growing cells were treated with 10 Gy of X-ray using a 6-MeV X-ray machine at a dose rate of 200 – 300 cGy/min. The cells were treated with 0.25 μM HMA immediately after irradiation and HMA remained for the entire culture period. The modes of cell death were discriminated by morphological changes, analysis of cell cycle, analysis of the mitochondrial events, and the expression of apoptosis-related proteins.

Results: Our data demonstrates that radiation induced a significant time-dependent increase of cell death and failed to sustain a prolonged G2 arrest in K562 cells. Radiation-induced cell death caused the accumulation of cyclinB1 and weak nuclear fragmentation, suggesting a mitotic catastrophe. This mitotic catastrophe was dependent upon the mitochondrial permeability transition pore (PTP) opening and was independent of caspase-3. In contrast, K562 cells treated with radiation and HMA had an accelerated cell death and induced a p53-independent apoptosis. This apoptotic pathway was dependent upon an initial hyperpolarization of the mitochondrial inner membrane, following the release of cytochrome c and subsequent caspase-3 activation.

Conclusions: Two mechanisms of radiation-induced cell death in K562 cells, mitotic catastrophe and apoptosis, are regulated through distinct pathways, mitochondria and caspase-independent and -dependent, respectively. The findings of this study may provide new insights into improving the efficiency of radiotherapy in CML patients.     

The expression and intranuclear distribution of nucleolin in HL-60 and K-562 cells after repeated,short-term exposition to rotating magnetic fields

Purpose: The aim of the study was to analyze the influence of rotating magnetic fields (RMF) on the expression and intranuclear distribution of nucleolin, protein involved in ribosome biosynthesis, in HL-60 (acute promyelocytic leukemia) and K-562 (chronic myelogenous leukemia) established human cell lines.

Materials and methods: Cells were exposed to RMF for two chosen states of the magnetic field induction: B = 10 mT and B = 20 mT in experimental set-up for 30 min with 24-h intervals for four days. Cytospin slides were prepared and expression of nucleolin was detected using monoclonal antibodies. Parameters of fluorescence related to nucleolin were measured in at least 2000 tumor cells in each slide by a laser scanning cytometer with an argon laser. Percentages of cells in different phases of cell cycle were also analyzed.

Results: The repeated exposition of cells to RMF caused significant increase in nucleolin expression in the whole nucleus and in the nucleolin aggregates (NUA). The redistribution of nucleolin measured by changes in number of NUA was also observed. The exposition of both cell lines studied to RMF did not alter the cell cycle.

Conclusion: The nucleolin is responsive to RMF in HL-60 and K-562. The increase of its expression may indicate a reaction of cells to RMF and it may influence their other biological properties.