抗CD28＋B7．1单抗共刺激T细胞诱导肝癌细胞凋亡的第二信使系统研究

目的：探讨T淋巴细胞活化、增殖、诱导肝癌细胞凋亡过程中第二信使系统的调控机制。方法：用CD28＋B7．1（CD80）单克隆抗体共刺激T淋巴细胞诱导肝癌细胞（BLE－7402）凋亡,测定不同诱导时间T细胞内cAMP,cGMP和Ca^2 的浓度改变及肝癌细胞凋亡情况。结果：活化的T淋巴细胞中,cAMP浓度在初期短暂升高,继而快速下降,作用于肝癌细胞后逐步回升至1－2倍,而细胞内cGMP的浓度急剧升高6－7倍,Ca^2 浓度也显著增加2－3倍,且均在第4天达最高值,与癌细胞的凋亡呈正相关,结论：T淋巴细胞内第二信使系统cAMP、cGMP和Ca^2 的水平与细胞的活化增殖、杀伤效应密切相关。     

激发型CD28单抗诱导多发性骨髓瘤细胞凋亡的作用研究

为了探讨激发型CD2 8单抗诱导多发性骨髓瘤细胞凋亡的作用及其机制 ,在表达CD2 8分子的多发性骨髓瘤细胞U2 6 6和XG 1的培养体系中加入终浓度为 10 μg/ml的激发型CD2 8单抗 ,逐日观察和分析细胞的生长与增殖状况。结果显示 ,在加入激发型CD2 8单抗后 2 4h即可见细胞聚集且逐渐加剧 ,细胞的立体感和折光性逐渐减弱 ,细胞的生长与增殖抑制 ,台盼蓝着色阳性率增加 ;凝胶电泳的结果表明 ,多发性骨髓瘤细胞出现降解的DNA条带 ;透射电镜分析的结果显示 ,加入激发型CD2 8单抗培养 2 4～ 4 8h ,30 %以上的细胞出现核质边聚的凋亡早期的病理性改变 ,培养 72h后 ,5 0 %以上的细胞出现空泡及凋亡小体。提示激发型CD2 8单抗具有诱导表达CD2 8分子的多发性骨髓瘤细胞凋亡的作用。     

CD28与B7.1共刺激PBLs受肝癌细胞诱导后的TCR Vβ基因表达

目的 研究Ｔ细胞受体（ＴＣＲ）Ｖβ在外周血淋巴细胞（ＰＢＬｓ）中的表达。方法 用单克隆抗体ＣＤ２８＋Ｂ７．１（ＣＤ８０）共刺激正常人外周血淋巴细胞后作用于肝癌细胞（ＢＥＬ－７４０２）。结果 发现ＰＢＬＳＴＣＲＶβ７基因在体外选择性扩增,表达水平为１５￣２５％,对照组为４￣８％。结论Ｖβ７基因对识别肿瘤抗原具有特异性,为肿瘤基因治疗和研究提供新的线索和实验依据。     

McAb共刺激PBLs膜表面分子表达与肝癌细胞凋亡的相关性

目的研究McAb共刺激PBLs前后的表型变化及与肝癌细胞凋亡的相关性。方法采用流式细胞仪分析PBLs被刺激前后的表型,用电镜超微结构和DNA梯子电泳观察肝癌细胞凋亡。结果CD3、CD4分子表达高于刺激前约10%,肝癌细胞出现凋亡,细胞核固缩、边聚、裂解。同时也出现典型的DNA梯子。而肝癌患者用共刺激PBLs后,CD3和CD8增高(P<0.05)。结论共刺激使共刺激信号分子增加,抗原呈递能力增强,也使细胞因子分泌增加,这些因素促使肝癌细胞凋亡,而肿瘤患者T细胞增加时向CD8     

胃癌细胞诱导凋亡过程中蛋白激酶B的表达意义

蛋白激酶B(PKB／Akt)是一类丝氨酸／苏氨酸蛋白激酶家族，其与蛋白激酶A，蛋白激酶C有着广泛的同源性，多种细胞外因子均可以诱导PKB／Akt活性，调节细胞生长代谢活动。PKB／Akt的生物学功能之一是能够与细胞内的一些凋亡相关因子相互作用，抑制细胞凋亡，维持细胞生长。因此探讨蛋白激酶PKB／Akt在肿瘤诱导凋亡过程中的表达状况，     

抗CD4单抗增强抗CD3单抗／IL—2活化的肿瘤特异性T细胞的抗瘤活性

目的探讨抗CD4mAb增强抗CD3mAb刺激的肿瘤特异性T细胞增殖和杀瘤活性的作用。方法将肿瘤细胞免疫的小鼠脾细胞,采用4种不同的方案培养1单独加2×104U/LrIL2IL2组2单独加抗CD3mAb抗CD3组3加抗CD3mAb48h后,再加入抗CD3mAb和2×104U/LrIL2抗CD3 IL2组4同时加抗CD3mAb和抗CD4mAb48h后,再加入抗CD3mAb、抗CD4mAb和2×104U/LrIL2抗CD3 IL2 抗CD4组。然后分别检测4组效应细胞的增殖水平、杀瘤活性及表型。结果抗CD3 IL2组细胞的3HTdR掺入量在第6,12和20d分别为:22045、13986和1931;抗CD3 IL2 抗CD4组细胞的3HTdR掺入量在第6、12和20d,分别为46193、31047和7443,后者明显高于前者P0.05。在培养12d时,抗CD3 IL2组的细胞对FBL3细胞株的最大杀伤率为83.6%;抗CD3 IL2 抗CD4组细胞的最大杀伤率为91.7%。细胞表型:FACS分析表明,抗CD3 IL2 抗CD4组培养12d的细胞,99%以上为Thy1.2 细胞,且CD4 、CD25 细胞的百分率均高于抗CD3 IL2组。结论抗CD4mAb对抗CD3mAb刺激、IL2诱导的肿瘤特异性T细胞的增殖和杀瘤活性具有增强作用。     

抗人CD28激发性单抗对T细胞淋巴瘤的抑制作用研究

目的:研究鼠抗人CD28单克隆抗体(克隆号:2F5)对T淋巴细胞瘤的抗肿瘤效应,为抗体介导肿瘤靶向治疗提供新的方法和思路。方法:流式细胞术检测鼠抗人CD28单克隆抗体2F5对人T淋巴瘤细胞株Jurkat细胞表面膜型CD28分子的识别;MTT法检测2F5对Jurkat细胞体外增殖的影响;将Jurkat细胞株接种于裸鼠腋下,建立Jurkat细胞荷瘤裸鼠模型;经瘤内多点注射2F5(注射剂量1μg/mm3),逐日观察肿瘤的大小和裸鼠的生存状态。结果:2F5能够识别Jurkat细胞表面CD28分子,阳性结合率可达93.37%;2F5与Jurkat细胞共培养后,显微镜下观察可见胞质中出现黑色颗粒,胞膜破裂,细胞的折光性和立体感减弱;MTT法分析结果显示,抗CD28单抗对Jurkat细胞的体外增殖具有明显的抑制作用;将Jurkat细胞接种35只裸鼠(成瘤率达70%);经瘤内多点注射2F5,35天后荷瘤小鼠体内肿瘤的生长速率明显降低;而生理盐水对照组肿瘤生长无明显改变。结论:鼠抗人CD28单克隆抗体2F5通过与Jurkat细胞表面膜型CD28分子结合对其增殖具有明显的抑制作用,提示CD28分子可作为治疗T淋巴瘤的一个潜在靶点,抗体对治疗CD28分子阳性的肿瘤具有潜在临床应用价值。     

交联抗人DR5单抗诱导的Jurkat细胞凋亡的信号转导

目的探讨抗肿瘤坏死因子相关凋亡诱导配体（TRAIL）的死亡受体5（DR5）单抗——YM366EC对Jurkat细胞增殖的影响，阐明抗DR5抗体的抗肿瘤效应机制。方法MTF方法检测抗体对Jurkat细胞存活率，FrlE—AnnexinV／PI标记流式细胞仪检测交联YM366EC对Jurkat细胞凋亡率影响。交联YM366EC作用于Jurkat细胞2、4、6、8、10、12h收集细胞，提取蛋白Westernblot检测Bcl-2、Cyt—C、Caspase-8、Caspase-3、Bax、Caspase-9的变化。结果抗DR5抗体单独应用不能抑制高表达DR5分子的Jurkat细胞增殖，但应用抗小鼠IgG交联DR5抗体后可直接诱导TRAIL敏感的Jurkat细胞凋亡改变。并且Westernblot检测到随着抗体诱导时间的延长Jurkat细胞Bel-2蛋白表达减少；Cyt—C、Bax，有活性的Caspase-8、Caspase-3和Caspase-9蛋白的表达增加。结论交联抗DR5抗体YM366EC对Jur—kat细胞增殖有明显的抑制作用，诱导的Jurkat细胞凋亡的分子机制涉及到Cyt-C、Bax、Caspase．8、Caspase-3、Caspase-9。     

抗CD94单抗与NK细胞、γδ^＋T细胞及CTL功能的关联

目的：探讨抗CD94单抗与NK细胞、γδ^ T细胞及CTL的相关性。方法,采用荧光检测法,分别分析NK细胞、γδ^ 细胞和CTL上CD94分子的表达,采用^3H TdR掺入法和MTT释放法,分析抗94单抗对这3种细胞的杀伤活性和细胞增殖的影响。结果NK细胞和γδ^ T细胞上CD94分子的表达,明显高于PBL和CTL。抗CD94单抗能激活NK细胞、γδ^ T细胞和CTL的增殖,并能提高γδ^ T细胞和CTL的杀伤活性。结论CD94分子在NK细胞和γδ^ T细胞表面呈高表达。抗CD94单抗对NK细胞、γδ^ T细胞及CTL的增殖具有上调节作用,对它们的杀伤活性具有正向调节作用。     

T细胞活化的辅助刺激因子:CD28和B7

近年来研究发现,T细胞受体与抗原-主要组织相容性抗原复合物的结合并不能有效地激活T细胞,T细胞的活化尚需要一种辅助刺激因子。T细胞表面的CD28与抗原呈递细胞表面的B7间的作用是T细胞活化最主要的辅助刺激途径。     

Oxidants in receptor tyrosine kinase signal transduction pathways

The accumulation of oxygen in the atmosphere created an evolutionary stress for organisms to survive because oxygen, while the by-product of photosynthesis and an important substrate in oxidative metabolism, can also be partially reduced to form toxic products. These forms of oxygen, reduced by one electron or two electrons, yield superoxide anion (O(2).-) and hydrogen peroxide (H(2)O(2)), respectively. Recent studies suggest that reactive oxygen species (ROS) such as O(2).- and H(2)O(2) function as mitogenic mediators of activated growth-factor receptor signaling. Reported data imply that growth factor-stimulated ROS generation can mediate intracellular signaling pathways by activating protein tyrosine kinases, inhibiting protein tyrosine phosphatase, and regulating redox-sensitive gene expression. This review examines the mechanisms of growth factor-induced generation of ROS and their roles in specific receptor tyrosine kinase signaling pathways.     

Protein kinase C in IL- 2 signal transduction

Interleukin-2 (IL-2), secreted principally by activated helper T-cells, plays a pivotal role in the generation and regulation of the immune response. The various biologic functions of IL-2 have been the focus of intensive study over the years and have been well worked out. By contrast, an understanding of the intracellular signals coupled to the IL-2 receptor and responsible for mediating IL-2 effects in T-cells is far less developed, and the role that protein kinase C (PKC) may play in the various cellular responses to IL-2 receptor activation is unclear. In this article we will discuss IL-2, its receptors, and IL-2 signal transduction in relation to the physiological roles PKC activation may play in IL-2-mediated activation of T-cells and other hematopoietic cells.     

Protein kinase mediators of integrin signal transduction

 Protein kinases are important mediators of signal transduction initiated by soluble growth factors and cytokines. Cellular interactions with the extracellular matrix are mediated largely by members of the integrin class of cell adhesion molecules, which also subsume signal transduction functions required for cell growth, differentiation, and survival. Here we review the involvement of protein kinases in mediating integrin intracellular signal transduction and the possible role for these molecules in regulating integrin adhesion. Although in most cases mechanistic details are incomplete, the emerging theme of protein kinases mediating cross-talk between growth factor receptor and integrin signalling systems provides a timely backdrop against which to present new developments in this area. The contribution of the actin cytoskeleton to integrin signal transduction is discussed, with respect to the concept of ’solid-state’ signalling providing a mechanism for imposing order on the protein-protein interactions which underlie signal discrimination. Moreover, we review evidence that dysregulated integrin signalling contributes to pathological processes including arthritis, thrombasthenia, leucocyte adhesion deficiencies, and tumour angiogenesis and invasion. Received: 14 May 1996 / Accepted: 2 July 1996     

Antibody valence and induced signal transduction: the role of antibody valence in anti-CD3-induced signal transduction in isolated normal T cells

This report provides direct evidence that protein kinase C (PKC) is activated in isolated, rigorously accessory cell (AC)-depleted T cells when the T cell antigen recognition complex is stimulated by divalent anti-CD3 monoclonal antibody. Anti-CD3 monoclonal antibody-stimulated PKC activation alone does not, however, directly stimulate T cell proliferation in the absence of AC. A rise in cytosolic calcium is the second signal believed to be of paramount importance in T cell activation. While mitogenic concentrations of some divalent anti-CD3 antibodies do not cause a rise in cytosolic calcium, polyvalent anti-CD3 does evoke increased intracellular Ca2+ in rigorously AC-depleted resting human T cells.     

CD28 and CTLA-4 coreceptor expression and signal transduction

Summary:  T-cell activation is mediated by antigen-specific signals from the TCRζ/CD3 and CD4–CD8–p56lck complexes in combination with additional co-signals provided by coreceptors such as CD28, inducible costimulator (ICOS), cytotoxic T-lymphocyte antigen-4 (CTLA-4), programmed death (PD-1), and others. CD28 and ICOS provide positive signals that promote and sustain T-cell responses, while CTLA-4 and PD-1 limit responses. The balance between stimulatory and inhibitory co-signals determines the ultimate nature of T-cell responses where response to foreign pathogen is achieved without excess inflammation and autoimmunity. In this review, we outline the current knowledge of the CD28 and CTLA-4 signaling mechanisms [involving phosphatidylinositol 3 kinase (PI3K), growth factor receptor-bound protein 2 (Grb2), Filamin A, protein kinase C θ (PKCθ), and phosphatases] that control T-cell immunity. We also present recent findings on T-cell receptor-interacting molecule (TRIM) regulation of CTLA-4 surface expression, and a signaling pathway involving CTLA-4 activation of PI3K and protein kinase B (PKB)/AKT by which cell survival is ensured under conditions of anergy induction.     

ActRIPs在激活素受体信号传导中的作用

激活素属于TGF-β超家族成员的多功能因子,其受体属于TGF-β超家族的Ser/THr激酶型受体,由Ⅰ型和Ⅱ型组成,Ⅱ型受体与配体激活素特异结合,再激活Ⅰ型受体,进一步通过Smad蛋白家族的级联反应将信号传入胞核。最新的研究发现Ser/THr激酶型受体介导的信号传导实际上受控于Ⅱ型受体,细胞内激活素受体相互作用蛋白(ActRIPs)参与了Ⅱ型受体的活性调控,ActRIPs蛋白家族具有与激活素Ⅱ型A受体(ActRⅡA)C末端特异结合的活性,不同的ActRIPs具有不同的作用,Ac-tRIP1以脚手架形式与ActRⅡA及Smad3结合,抑制细胞内Smad途径信号传导;ActRIP2与ActRⅡA结合后,通过其C末端介导受体内吞作用,对信号传导也具有抑制作用;ActRIP3则与ActRIP1,2不同,其与ActRⅡA结合后,具有促进信号传导的作用。ActRIPs的发现,使人们更清晰地认识到Ser/THr激酶型受体介导的信号传导调控机制。     

Mammalian mitogen-activated protein kinase signal transduction pathways activated by stress and inflammation

The molecular details of mammalian stress-activated signal transduction pathways have only begun to be dissected. This, despite the fact that the impact of these pathways on the pathology of chronic inflammation, heart disease, stroke, the debilitating effects of diabetes mellitus, and the side effects of cancer therapy, not to mention embryonic development, innate and acquired immunity, is profound. Cardiovascular disease and diabetes alone represent the most significant health care problems in the developed world. Thus it is not surprising that understanding these pathways has attracted wide interest, and in the past 10 years, dramatic progress has been made. Accordingly, it is now becoming possible to envisage the transition of these findings to the development of novel treatment strategies. This review focuses on the biochemical components and regulation of mammalian stress-regulated mitogen-activated protein kinase (MAPK) pathways. The nuclear factor-kappa B pathway, a second stress signaling paradigm, has been the subject of several excellent recent reviews (258, 260).     

Redox-linked signal transduction pathways for protein tyrosine kinase activation

The signaling for activation of protein tyrosine kinases (PTKs) is usually started by binding of ligands to cell-surface receptors. However, recent evidence suggests the presence of ligand binding-independent signaling pathways that are mediated by oxidative stress. Oxidation and reduction of protein cysteine sulfhydryl (SH) groups may work as a molecular switch to start or to stop the signaling. It is known that oxidation of cysteine SH groups on protein tyrosine phosphatases switches off the action of protein tyrosine phosphatases. This event may not, however, signal for initial autophosphorylation of previously unphosphorylated PTKs, whereas it certainly prevents dephosphorylation of once-phosphorylated PTKs. We have suggested new mechanisms for oxidative stress-mediated PTK activation. First, cell-surface glycosylphosphatidylinositol-anchoring proteins and a phosphoglycolipid/cholesterol-enriched membrane microdomain termed a "raft" can be the direct targets of oxidative stress for inducing their clustering through an S-S-bonded or S-X-S-bonded crosslinking of cell-surface proteins and subsequent activation of raft-associating Src family PTKs. Second, intracellular specific cysteine SH groups on PTK proteins can be another target of oxidative stress for inducing a conformational change necessary for initial activation of PTKs. A possible relationship between cell-surface and intracellular events is that the former frequently induces superoxide production as the second messenger for the latter.