IL-6对照射小鼠脾淋巴细胞亚群活性的影响

目的研究白细胞介素6（IL-6）对照射小鼠脾淋巴细胞亚群自然杀伤活性的影响。方法BALB／C小鼠分为照射组、对照组和照射＋IL-6组，采用Panning法从小鼠脾淋巴细胞中分离L3T4、Lyt2和B细胞，用^3H-TdR释放实验检测脾淋巴细胞亚群自然杀伤活性。结果照射＋IL-6组与对照组比较，^3H-TdR释放量有显著性差异（P〈0．01）。结论IL-6具有促进照射小鼠脾淋巴细胞亚群活性作用。     

曲古菌素A对K562细胞中HDAC1表达的影响

目的研究表明组蛋白去乙酰化酶(histone deacetylase,HDAC1)在多种肿瘤中高表达,曲古菌素A(trichostatin A,TSA)可以抑制肿瘤细胞的生长.该实验研究HDAC1在K562细胞的表达及TSA对其增殖的影响.方法50～400 nmol/L的TSA分别处理K562细胞8～48 h后用四甲基偶氮唑蓝(MTT法)比色检测K562细胞的生长活性;应用流式细胞仪法观察细胞凋亡.RT-PCR和蛋白印迹法(western blot)方法检测K562细胞在24 h不同浓度(50～400 nmol/L)的条件下HDAC1的mRNA和蛋白的表达以及TSA对其作用.结果TSA可显著抑制K562细胞的生长,诱导细胞发生凋亡,并呈时间及剂量依赖性.HDAC1的mRNA A值的半定量表达以及蛋白表达明显增强(P＜0.05),但随着浓度的增加而表达下调.结论TSA对K562细胞具有明显的增生抑制及诱导凋亡作用,抑制HDAC1的表达,可能是其重要作用机制之一.     

桂皮酸诱导K562细胞凋亡及其机制的初步研究

目的探讨桂皮酸对K562细胞凋亡的诱导作用及其机制。方法应用MTT测出 IC50,应用免疫荧光显微镜,DNA Ladder,流式细胞仪,检测凋亡的发生,应用RT-PCR琼脂糖凝胶电泳检测bcl-2基因表达的差异。结果经MTT检测发现IC50为1 mmol／L,24 h后药物基本达到了较佳的效果,且免疫荧光显微镜、DNA Ladder、流式细胞仪检测均有凋亡的发生,RT-PCR结果显示,经桂皮酸处理24h后,bcl-2基因表达明显降低。结论1 mmol／L的桂皮酸作用24 h后可以引起K562 细胞发生凋亡,并且bcl-2基因表达下调是引起凋亡的原因之一。     

人参多糖对K562细胞人粒-巨噬细胞集落刺激因子和促红细胞生成素及其受体表达的影响

目的研究人参多糖(GPS)对人红白血病细胞株(K562)表达人粒-巨噬细胞集落刺激因子(GM-CSF)、促红细胞生成素(EPO)及其受体的影响。方法采用细胞体外培养技术,RT-PCR检测GPS诱导后K562细胞中GM-CSF、EPOmRNA的表达、免疫细胞化学方法检测K562细胞经GPS作用后GM-CSF、EPO及其受体蛋白表达的变化、Westernblotting检测GPS诱导后K562细胞GM-CSF、EPO受体蛋白的表达。结果经GPS诱导后,RT-PCR检测显示K562细胞GM-CSFmRNA的表达有所增强,但与对照组相比无统计学意义,EPOmRNA的表达有明显的降低;免疫细胞化学方法检测EPO与GM-CSF蛋白的表达明显减弱,EPO与GM-CSF受体蛋白的表达明显增强;Westernblotting检测GM-CSF、EPO受体蛋白的表达增强。结论GPS既能抑制K562细胞分泌GM-CSF、EPO,又能明显促进GM-CSF、EPO受体的合成和分泌。     

土槿乙酸体外诱导K562细胞凋亡的研究

目的研究土槿乙酸体外对人白血病细胞(K562)凋亡的诱导作用,探讨其抗癌作用机制.方法以不同浓度土槿乙酸分别处理K562细胞,用琼脂糖凝胶电泳、荧光显微镜和倒置光显微镜、MTT法观察K562细胞DNA带型、形态和抑制率的变化.结果1×10-5mol/L土槿乙酸作用30 h能有效诱导K562细胞凋亡,凋亡细胞有典型的形态学改变及DNA梯形带形成.MTT法测定不同浓度土槿乙酸明显抑制K562细胞系的生长,其IC50值为2×10-6mol/L.结论土槿乙酸能成功诱导K562细胞凋亡,此种诱导作用呈药物作用浓度及时间依赖性.     

甘草次酸对白血病细胞株K562增殖及其分化的影响

目的探讨甘草次酸（GA）对白血病细胞株K562增殖和分化的作用。方法采用液体培养实验、MTT法、集落培养实验观察GA对K562细胞增殖的影响；采用联苯胺染色法观察细胞内血红蛋白含量变化，采用流式细胞术检测CD71分化抗原评价GA对K562细胞的诱导分化作用。结果GA可明显抑制K562细胞生长、MTT值、集落生长，并呈浓度依赖性；GA可升高细胞内血红蛋白含量，同时上调K562细胞膜CD71分化抗原的表达量。结论GA具有抑制K562细胞增殖和诱导其分化的作用。     

PMA-treated K-562 leukemia cells mediate a TH2-specific expansion of CD4+ T cells in vitro

Highly enriched preparations of human CD3+CD4+ T-lymphocytes were stimulated with mitogen or OKT3 to determine the capacity of K-562 cells to function as accessory cells. Phorbol 12-myristate 13-acetate (PMA)-treated K-562 cells were induced to differentiate along the megakaryocytic lineage and could supplant monocyte-accessory cell function. Intracytoplasmic analysis of interleukin-4 (IL-4) and interferon-γ (IFN-γ) established that IL-4, and not IFN-γ, was preferentially produced by the activated lymphocytes. This polarized stimulation is compatible with a type 2 or humoral immune response of purified T cells co-cultured with differentiated K-562 cells in vitro, and may have implications in immunoregulation due to disease progression.     

Modulation of P-glycoprotein-mediated multidrug resistance in K562 leukemic cells by indole-3-carbinol

Resistance to chemotherapeutic drugs is one of the major problems in the treatment of cancer. P-glycoprotein (P-gp) encoded by the mdr gene is a highly conserved protein, acts as a multidrug transporter, and has a major role in multiple drug resistance (MDR). Targeting of P-gp by naturally occurring compounds is an effective strategy to overcome MDR. Indole-3-carbinol (I3C), a glucosinolates present in cruciferous vegetables, is a promising chemopreventive agent as it is reported to possess antimutagenic, antitumorigenic, and antiestrogenic properties in experimental studies. In the present investigation, the potential of I3C to modulate P-gp expression was evaluated in vinblastine (VBL)-resistant K562 human leukemic cells. The resistant K562 cells (K562/R10) were found to be cross-resistant to vincristine (VCR), doxorubicin (DXR), and other antineoplastic agents. I3C at a nontoxic dose (10 x 10(-3) M) enhanced the cytotoxic effects of VBL time dependently in VBL-resistant human leukemia (K562/R10) cells but had no effect on parent-sensitive cells (K562/S). The Western blot analysis of K 562/R 10 cells showed that I3C downregulates the induced levels of P-gp in resistant cells near to normal levels. The quantitation of immunocytochemically stained K562/R10 cells showed 24%, 48%, and 80% decrease in the levels of P-gp by I3C for 24, 48, and 72 h of incubation. The above features thus indicate that I3C could be used as a novel modulator of P-gp-mediated multidrug resistance in vitro and may be effective as a dietary adjuvant in the treatment of MDR cancers.     

NF-H基因参与K562/A02细胞多药耐药机制形成的研究

目的 分析K562／A02细胞多药耐药性(MDR)分子机制,寻找可能参与K562／A02细胞耐药机制的新基因。方法 通过长期逐步增加K562细胞培养液中阿霉素(ADM)的浓度,诱导出多药耐药细胞株K562／A02,利用cDNA microarray比较K562和K562／A02基因表达的筹别,从中选择NF-H基因进行RT-PCR和免疫细胞化学验证,并利用反义核酸技术和细胞内ADM浓度的测定,进一步验证该基因与K562／A02细胞多药耐药的关系。结果 通过比较发现,有12个基因可能参与了K562／A02细胞的耐药机制,其中7个基因在K562／A02中被下调,5个基因被上调。本研究结果显示,NF-H基因在K562／A02细胞中高表达,并且,将NF-H和mdrl反义核酸同时转入K562／A02细胞后,可明显提高细胞内ADM浓度,而单独转入NF-H反义核酸效果不明显。结论 K562／A02细胞耐药表型的形成是多因素的．除了P-糖蛋白(P-gp)等常见因素外,可能还有NF-H基因的参与。