Caspase activation is required for T cell proliferation

Triggering of Fas (CD95) by its ligand (FasL) rapidly induces cell death via recruitment of the adaptor protein Fas-associated death domain (FADD), resulting in activation of a caspase cascade. It was thus surprising that T lymphocytes deficient in FADD were reported recently to be not only resistant to FasL-mediated apoptosis, but also defective in their proliferative capacity. This finding suggested potentially dual roles of cell growth and death for Fas and possibly other death receptors. We report here that CD3-induced proliferation and interleukin 2 production by human T cells are blocked by inhibitors of caspase activity. This is paralleled by rapid cleavage of caspase-8 after CD3 stimulation, but no detectable processing of caspase-3 during the same interval. The caspase contribution to T cell activation may occur via TCR-mediated upregulation of FasL, as Fas-Fc blocked T cell proliferation, whereas soluble FasL augmented CD3-induced proliferation. These findings extend the role of death receptors to the promotion of T cell growth in a caspase-dependent manner.     

西达本胺对人B淋巴瘤细胞株的作用及其机制研究

本研究旨在探讨组蛋白去乙酰化酶抑制剂(HDACI)西达本胺对3种B淋巴瘤细胞株Raji(Burkitt淋巴瘤)、Maver及Z-138(套细胞淋巴瘤)的抑制增殖和诱导凋亡的作用及其机制。以不同浓度的西达本胺及不同时间作用于体外培养的3种B淋巴瘤细胞,采用CCK-8法检测细胞的增殖;流式细胞术检测细胞的凋亡及线粒体膜电位;Western blot方法检测细胞内组蛋白H3、H4乙酰化水平及caspase-3蛋白的表达。结果表明,西达本胺可抑制这3种B淋巴瘤细胞的增殖,其抑制作用具有一定的时间和浓度依赖性,尤其能较早较快地抑制Z-138细胞的增殖;另外,西达本胺还可诱导3种B淋巴瘤细胞发生凋亡并引起细胞线粒体膜电位下降,Maver及Z-138细胞对西达本胺较Raji细胞更为敏感;西达本胺可以提高细胞内组蛋白H3、H4乙酰化水平及Maver和Z-138细胞的caspase-3活性。结论:西达本胺能够抑制B淋巴瘤细胞株的增殖,诱导细胞凋亡,其机制可能与西达本胺上调组蛋白H3、H4乙酰化水平,触发线粒体凋亡途径及活化caspase-3有关。     

Induction of apoptosis in renal tubular cells by histone deacetylase inhibitors, a family of anticancer agents

Inhibitors of histone deacetylases, including suberoylanilide hydroxamic acid (SAHA) and Trichostatin A, are a new class of anticancer agents. With potent chemotherapy effects in cancers, these agents are not obviously toxic in normal nonmalignant cells or tissues. However, their toxicity in kidney cells has not been carefully evaluated. Here, we demonstrate a potent apoptosis-inducing activity of SAHA in cultured renal proximal tubular cells. SAHA induces apoptosis at low micromolar concentrations. At 5 muM, SAHA induces 30 to approximately 40% apoptosis in 18 h. The apoptosis is accompanied by notable caspase activation; however, the general caspase inhibitor VAD can only partially suppress SAHA-induced apoptosis, suggesting the involvement of both caspase-dependent and -independent mechanisms. SAHA treatment leads to cytochrome c release from mitochondria, which is suppressed by Bcl-2 but not by VAD. Bcl-2 consistently blocks SAHA-induced apoptosis. During SAHA treatment, Bcl-2 and Bcl-XL decrease, and Bid is proteolytically cleaved, whereas Bax and Bak expression remains constant. Bid cleavage, but not Bcl-2/Bcl-XL decrease, is completely suppressed by VAD. SAHA does not activate p53, and pifithrin-alpha (a pharmacological p53 inhibitor) does not attenuate SAHA-induced apoptosis, negating a role of p53 in SAHA-induced apoptosis. SAHA induces histone acetylation, which is not affected by VAD, Bcl-2, or pifithrin-alpha. Trichostatin A can also induce apoptosis and histone acetylation in renal tubular cells. Together, the results have shown evidence for renal toxicity of histone deacetylase inhibitors. The toxicity may be related to protein acetylation and decrease of antiapoptotic proteins including Bcl-2 and Bcl-XL.     

补骨脂素联合长波紫外线A诱导HL-60细胞凋亡作用的研究

本研究探讨中药补骨脂素（psoralen，PSO）加长波紫外线A（ultraviolet A，UVA）（PUVA）诱导人白血病细胞HL-60凋亡的作用及其可能的作用机制。采用MTT法观察PUVA对HL-60细胞增殖的影响；采用电子显微镜技术观察细胞超微结构改变；流式细胞术（FCM）检测细胞凋亡率、线粒体跨膜电位水平以及细胞Fas、FasL蛋白的表达；荧光定量PCR技术检测细胞Fas、FasL mRNA的表达；免疫细胞化学法（immunocytochemistry，ICC）检测caspase 8、caspase3蛋白的表达。结果表明，PUVA可抑制HL-60细胞的增殖，使凋亡率增加，作用呈时间、浓度依赖性；UVA照射时间15分钟和PSO浓度为80μg／ml时，HL-60细胞增殖的抑制率、凋亡率达峰值；PUVA作用后HL-60细胞超微结构出现明显的凋亡形态学改变，细胞线粒体跨膜电位水平下降；PUVA作用4小时Fas mRNA的表达升高，FasL mRNA的表达下降；PUVA作用24小时Fas、FasL在蛋白水平的表达亦呈现相同规律；PUVA可使HL-60细胞caspase 8、caspase 3蛋白的表达增强，在作用后8小时强度达峰值。结论：PUVA能够抑制HL-60细胞的增殖，并诱导其凋亡，可能的机制是PUVA作用于Fas／FasL系统，使Fas基因表达升高、FasL基因表达下降，激活下游caspase 8、caspase 3的表达，线粒体膜电位水平降低亦可能参与了这个过程。     

Involvement of Fas (CD95/APO-1) and Fas ligand in apoptosis induced by ganciclovir treatment of tumor cells transduced with herpes simplex virus thymidine kinase.

Transduction of cancer cells with herpes simplex virus thymidine kinase gene (HSVtk) followed by prodrug ganciclovir (GCV) treatment has been shown to induce apoptosis. In this study, four murine tumors including B16F10 melanoma, NG4TL4 sarcoma, H6 hepatoma and 1MEA 7R.1 hepatoma were found to vary in sensitivity to this gene therapy strategy in vitro but, at effective doses of GCV, the HSVtk-transduced cells of all four tumors showed similar kinetics of early rise in p53 protein levels, then cell cycle S-/G2-phase arrest and finally signs of apoptosis. Immunoblot analyses revealed that Fas (CD95/APO-1), Fas ligand (FasL) and two downstream mediators, RIP and caspase-3, (CPP32, YAMA, Apopain) were increased in GCV-treated HSVtk-transduced tumor cells the cell cycle arrest and before apoptosis. Increased expression of FasL could also be observed in vivo in HSVtk-transduced tumors induced to regress by GCV treatment. Enzyme measurements using specific substrate showed that the caspase-3 activation followed kinetically the FasL expression. More than half of the HSVtk/GCV-induced cell death could be abrogated by addition to the cell culture medium of a specific antisense oligonucleotide to block FasL synthesis, a recombinant Fas/Fc chimeric protein to compete with Fas receptor for FasL binding, or cell-permeable specific tetrapeptide inhibitors of caspase-3 or caspase-8.     

Asiatic acid, a triterpene, induces apoptosis and cell cycle arrest through activation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase pathways in human breast cancer cells

This study first investigates the anticancer effect of asiatic acid in two human breast cancer cell lines, MCF-7 and MDA-MB-231. Asiatic acid exhibited effective cell growth inhibition by inducing cancer cells to undergo S-G2/M phase arrest and apoptosis. Blockade of cell cycle was associated with increased p21/WAF1 levels and reduced amounts of cyclinB1, cyclinA, Cdc2, and Cdc25C in a p53-independent manner. Asiatic acid also reduced Cdc2 function by increasing the association of p21/WAF1/Cdc2 complex and the level of inactivated phospho-Cdc2 and phospho-Cdc25C. Asiatic acid treatment triggered the mitochondrial apoptotic pathway indicated by changing Bax/Bcl-2 ratios, cytochrome c release, and caspase-9 activation, but it did not act on Fas/Fas ligand pathways and the activation of caspase-8. We also found that mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase (ERK1/2), and p38, but not c-Jun NH2-terminal kinase (JNK), are critical mediators in asiatic acid-induced cell growth inhibition. U0126 [1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene] or SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole], specific inhibitors of mitogen-activated protein kinase kinase and p38 kinase activities, significantly decreased or delayed apoptosis. Asiatic acid was likely to confine the breast cancer cells in the S-G2/M phase mainly through the p38 pathway, because both SB203580 and p38 small interfering RNA (siRNA) inhibition significantly attenuated the accumulation of inactive phospho-Cdc2 and phospho-Cdc25C proteins and the cell numbers of S-G2/M phase. Moreover, U0126 and ERK siRNA inhibition completely suppressed asiatic acid-induced Bcl-2 phosphorylation and Bax up-regulation, and caspase-9 activation. Together, these results imply a critical role for ERK1/2 and p38 but not JNK, p53, and Fas/Fas ligand in asiatic acid-induced S-G2/M arrest and apoptosis of human breast cancer cells.     

Sulforaphane induces cell type-specific apoptosis in human breast cancer cell lines

Sulforaphane, an isothiocyanate found in cruciferous vegetables, has been shown to induce phase 2 detoxication enzymes and inhibit the growth of chemically induced mammary tumors in rats, although the exact mechanisms of action of sulforaphane are not understood. In this study, we evaluated the effects of sulforaphane on cell growth and death in several human breast cancer cell lines and examined the hypothesis that sulforaphane acts as a histone deacetylase (HDAC) inhibitor in these cell lines. Sulforaphane treatment inhibited cell growth, induced a G(2)-M cell cycle block, increased expression of cyclin B1, and induced oligonucleosomal DNA fragmentation in the four human breast cancer cell lines examined, MDA-MB-231, MDA-MB-468, MCF-7, and T47D cells. Activation of apoptosis by sulforaphane in MDA-MB-231 cells seemed to be initiated through induction of Fas ligand, which resulted in activation of caspase-8, caspase-3, and poly(ADP-ribose) polymerase, whereas apoptosis in the other breast cancer cell lines was initiated by decreased Bcl-2 expression, release of cytochrome c into the cytosol, activation of caspase-9 and caspase-3, but not caspase-8, and poly(ADP-ribose) polymerase cleavage. Sulforaphane inhibited HDAC activity and decreased the expression of estrogen receptor-alpha, epidermal growth factor receptor, and human epidermal growth factor receptor-2 in each cell line, although no change in the acetylation of H3 or H4 was seen. These data suggest that sulforaphane inhibits cell growth, activates apoptosis, inhibits HDAC activity, and decreases the expression of key proteins involved in breast cancer proliferation in human breast cancer cells. These results support testing sulforaphane in vivo and warrant future studies examining the clinical potential of sulforaphane in human breast cancer.     

Simultaneous activation of the intrinsic and extrinsic pathways by histone deacetylase (HDAC) inhibitors and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) synergistically induces mitochondrial damage and apoptosis in human leukemia cells

Interactions between histone deacetylase (HDAC) inhibitors and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), also known as Apo2 ligand, were examined in human leukemia cells (e.g., U937, Jurkat, and HL-60). Simultaneous exposure of cells to 100-ng/ml TRAIL with either 1-mM sodium butyrate or 2- micro M suberoylanilide hydroxamic acid resulted in a striking increase in leukemic cell mitochondrial damage, caspase activation, and apoptosis. Lethal effects were significantly diminished in U937 cells ectopically expressing dominant-negative caspase-8, dominant-negative Fas-associated death domain, CrmA (receptor pathway), or Bcl-2 or Bcl-X(L) (mitochondrial pathway). Analysis of mitochondrial events in U937 cells exposed to TRAIL/HDAC inhibitors revealed enhanced Bid activation and Bax translocation, loss of mitochondrial membrane potential, and cytoplasmic release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor. No changes were observed in expression of FLICE-like inhibitory protein, TRAIL receptors, or reactive oxygen species generation. TRAIL/HDAC inhibitor-induced apoptosis triggered caspase-dependent cleavage of p21(WAF1/CIP1); moreover, enforced expression of a nuclear localization signal deletant form of p21(WAF1/CIP1) significantly diminished lethality. Lastly, p27(KIP1), pRb, X-linked inhibitor of apoptosis, and Bcl-2 displayed extensive proteolysis. These findings indicate that coadministration of TRAIL with HDAC inhibitors synergistically induces apoptosis in human myeloid leukemia cells and provide further evidence that simultaneous activation of the extrinsic and intrinsic pathways in such cells leads to a dramatic increase in mitochondrial injury and activation of the caspase cascade.     

Synergistic activity of the histone deacetylase inhibitor suberoylanilide hydroxamic acid and the bisphosphonate zoledronic acid against prostate cancer cells in vitro

Bisphosphonates are widely used agents for the treatment of malignant bone disease. They inhibit osteoclast-mediated bone resorption and can have direct effects on cancer cells. In this study, we investigated whether the anticancer activity of the third-generation bisphosphonate zoledronic acid (ZOL) could be enhanced by combination with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA). We found that ZOL and SAHA cooperated to induce cell death in the prostate cancer cell lines LNCaP and PC-3. The effect was synergistic, as evidenced by combination index isobologram analysis. ZOL and SAHA synergized to induce dissipation of the mitochondrial transmembrane potential, to activate caspase-3, and to trigger DNA fragmentation, showing that the combination of ZOL and SAHA resulted in the initiation of apoptosis. Because ZOL acts by inhibiting the mevalonate pathway, thereby preventing protein prenylation, we explored whether the mevalonate pathway was also the target of the cooperative action of ZOL and SAHA. We found that geranylgeraniol, but not farnesol, significantly reduced ZOL/SAHA-induced cell death, indicating that the synergistic action of the agents was due to the inhibition of geranylgeranylation. Consistently, a direct inhibitor of geranylgeranylation, GGTI-298, synergized with SAHA to induce cell death, whereas an inhibitor of farnesylation, FTI-277, had no effect. In addition, SAHA synergized with mevastatin, an inhibitor of the proximal enzyme in the mevalonate pathway. These in vitro findings provide a rationale for an in vivo exploration into the potential of combining SAHA and ZOL, or other inhibitors of the mevalonate pathway, as an effective strategy for anticancer therapy.     

MiRNA-326抑制人椎间盘退变髓核细胞活力和凋亡的机制

目的:探讨过表达miRNA-326对椎间盘退变(intervertebral disc degeneration,IDD)髓核(nucleus pulposus,NP)细胞凋亡的影响及其作用机制。方法:构建miRNA-326慢病毒表达载体,在293T细胞中获得重组慢病毒,经感染NP细胞得到稳定过表达细胞系GV369-miRNA-326-NP,同时设置空载体GV369-NP组与空白组。荧光显微镜观察慢病毒载体的标签蛋白[绿色荧光蛋白(green fluorescent protein,GFP)]的表达,实时荧光定量PCR(real-time quantitative polymerase chain reaction,RT-qPCR)方法检测miRNA-326的表达,流式细胞术检测细胞凋亡,荧光素酶报告基因分析验证miRNA-326与FasL的靶向关系,蛋白质印迹法检测细胞中凋亡相关蛋白FADD,caspase-3,Bcl-2及Bax的表达,使用试剂盒检测细胞线粒体膜电势的变化情况。结果:荧光显微镜下示,经慢病毒感染的过表达细胞系和空载体细胞系均出现绿色荧光,而空白组未见绿色荧光。与空白组相比,GV369-miRNA-326-NP组中miRNA-326的表达水平、Bcl-2表达水平和线粒体膜电位明显升高,而细胞凋亡率,FADD,caspase-3和Bax的表达水平明显下降,差异均有统计学意义(P<0.05);GV369-NP组与空白组相比,差异无统计学意义(P>0.05)。荧光素酶报告基因分析证实miRNA-326与FasL存在靶向关系。结论:MiRNA-326可抑制IDD NP细胞发生凋亡,既可通过靶向性调控外源性FasL/Fas通路参与caspase-3和FADD介导的细胞凋亡,也可通过线粒体途径对细胞凋亡发挥作用。     

Glioma apoptosis induced by macrophages involves both death receptor-dependent and independent pathways

Apoptosis of glioma may represent a promising intervention for tumor treatment. Macrophages are able to induce apoptosis in a number of tumor cells, including glioma. It is known that apoptosis of cells is executed on either a death receptor-dependent or independent pathway. Whether and how apoptosis of glioma cells induced by activated macrophages is involved in these two pathways simultaneously are not known. Using in vitro and in vivo experimental models, we investigated Bcl-2 system and Fas/FasL channel, representing the death receptor-dependent and independent pathways, respectively, in glioma cells treated with the supernatant from the activated macrophages, which was rich in tumor necrosis factor-alpha and interferon-gamma. We found that levels of Fas and FasL were up-regulated both in vitro and in vivo, accompanying an increase in the expression of caspase-8. The number of apoptotic cells was also increased significantly, although the percentage of death cells exceeded the number of tumor cells positive for Fas or FasL. It was also evident that the expression of Bax was increased, whereas the level of Bcl-2 was decreased, in glioma cells treated with the supernatant from the activated macrophages. The alteration of molecules related to both death pathways led to apoptosis of glioma and the inhibition of xenograft glioma growth in mice. Apoptosis of glioma induced by the activated macrophage is executed by way of both death receptor-dependent and independent pathways, and such an apoptosis-induced approach can effectively inhibit the growth of glioma in vivo.     

白血病细胞对Fas/FasL途径介导凋亡的抵抗及其应对策略

从细胞凋亡的角度看，造血细胞凋亡过少是造血细胞堆积的原因，Fas／FasL系统作为诱导细胞凋亡的一条重要途径，参与了白血病的发生发展。白血病细胞普遍存在对Fas／FasL途径介导的凋亡不敏感或抵抗，而这也是造成白血病细胞免疫逃逸和对化疗不敏感的重要原因之一。近年来，国内外对白血病Fas／FasL途径介导的凋亡抵抗的机制．诸如Fas／FasL突变及表达异常Fas信号传导途径异常，凋亡调控基因对Fas／FasL系统的调控（NF—KB、XiAP膜受体CD28和基质金属蛋白酶7等）和应对策略的相关研究取得了一些进展，现对上述有关问题作一综述。     

Involvement of cathepsin D in chemotherapy-induced cytochrome c release, caspase activation, and cell death

Treatment of cells with chemotherapy drugs activates the intrinsic mitochondrial pathway of apoptosis and the caspase protease cascade. Recently, the lysosomal protease cathepsin D has been implicated in apoptosis caused by oxidative stress, inhibition of protein kinase C, and stimulation of the TNFR1 and Fas death receptors. However, the role of cathepsin D in chemotherapy-induced cell death has remained largely unexplored. In this report, we show that treatment of U937 leukemia cells with the chemotherapy drug etoposide (VP-16) results in cathepsin D release into the cytosol within 4 hours after initiation of drug treatment. VP-16-induced cathepsin D release was not inhibited by z-VAD-FMK or pepstatin A, suggesting that it occurred independently of the activities of caspase proteases or cathepsin D. Down-regulation of cathepsin D expression in suspension U937 cells or adherent HeLa cells using cathepsin D small interfering RNA partially inhibited cell death resulting from treatment of cells with tumor necrosis factor-alpha, tumor necrosis factor-related apoptosis inducing ligand, or the chemotherapy drugs VP-16, cisplatin, and 5-fluorouracil. Moreover, cathepsin D down-regulation significantly delayed cytochrome c release and caspase-3 activation in response to chemotherapy treatment. Incubation of isolated mitochondria with cathepsin D-treated cytosolic extracts resulted in potent release of cytochrome c, indicating that a cytoplasmic substrate mediates the effects of cathepsin D on mitochondria. Together, these findings show that cathepsin D plays an important role in chemotherapy-induced cell death, and that cathepsin D lies upstream of cytochrome c release and caspase-3 activation in the chemotherapy-induced execution pathway.     

Functional expression of Fas and Fas ligand on human colonic intraepithelial T lymphocytes

The expression of Fas, a cell surface receptor directly responsible for triggering cell death by apoptosis, and its ligand (FasL) was investigated on both human colonic intraepithelial T lymphocytes (IELs) and peripheral blood mononuclear lymphocytes (PBMLs). FACS analysis indicated that IELs have increased expression of Fas compared with PBMLs, together with the progress activation marker, CD45RO. A discrete fraction of freshly isolated IELs also constitutively expressed FasL, perhaps as a result of recent in vivo activation. Using monoclonal antibody APO2.7, which detects mitochondrial 7A6 antigen specifically expressed by cells undergoing apoptosis, we further investigated the apoptosis-inducing effect of anti-Fas monoclonal antibody (CH11) on both IELs and PBMLs. FACS analysis revealed that CH11 increased the percentage of apoptotic cells, in IELs but not in PBMLs. Culture with anti-FasL monoclonal antibody (4H9) significantly recovered cell viability in IELs, but not in PBMLs. These results indicate that IELs constitutively express both Fas and FasL and that Fas crosslinking generates signals resulting in apoptosis, outlining a potential mechanism involved in intestinal tolerance.     

Methylseleninic acid synergizes with tamoxifen to induce caspase-mediated apoptosis in breast cancer cells

Tamoxifen has efficacy as a breast cancer therapy and chemoprevention agent. However, toxicity and resistance to tamoxifen limit its clinical application. There is an urgent need to develop compounds that may be combined with tamoxifen to improve efficacy and overcome toxicity and resistance. We showed previously that the organoselenium compound methylseleninic acid (MSA) increased the growth-inhibitory effect of tamoxifen and reversed tamoxifen resistance in breast cancer cells. In this study, we examined the mechanism for induction of apoptosis by MSA combined with tamoxifen in tamoxifen-sensitive and tamoxifen-resistant breast cancer cells. 4-hydroxytamoxifen (TAM; 10(-7) mol/L) alone resulted in cell cycle arrest but no apoptosis, whereas MSA alone (10 mumol/L) induced apoptosis in tamoxifen-sensitive cells. Combination of MSA with TAM resulted in a synergistic apoptosis in both tamoxifen-sensitive and tamoxifen-resistant breast cancer cells compared with either agent alone. MSA and MSA combined with TAM induced apoptosis through the intrinsic, mitochondrial apoptotic pathway. MSA induced a sequential activation of caspase-9 and then caspase-8. These results indicate that the growth inhibition synergy and reversal of tamoxifen resistance by combination of selenium with tamoxifen occurs via a tamoxifen-induced cell cycle arrest, allowing more cells to enter the intrinsic apoptotic pathway elicited by selenium. [Mol Cancer Ther 2008;7(9):3056-63].     

特发性血小板减少性紫癜患者外周血T细胞Fas-FasL和caspase-3凋亡相关蛋白的表达及其意义

目的 探讨Fas、FasL及caspase-3凋亡相关蛋白在特发性血小板减少性紫癜(ITP)患者T淋巴细胞的表达及其意义.方法 应用流式细胞术测定T细胞亚群表面Fas、FasL的表达率及细胞质中活化caspase-3的表达率,用Western blot法检测T细胞亚群caspase-3蛋白的表达.结果 与健康对照组[(29.4±8.2)%]相比,ITP患者组CD4+ T细胞表面Fas的表达率显著增加[(42.1±9.5)%](P＜0.05),CD8+ T细胞表面Fas的表达率略有增加但差异无统计学意义[(9.3±6.0)%与(13.4±5.8)%](P＞0.05).ITP患者组T细胞亚群表面FasL的表达率均较健康对照组显著增加(P＜0.05).ITP患者组T细胞亚群胞质中活化caspase-3的表达率,明显高于健康对照组(P＜0.05).Western blot检测结果显示,与治疗前相比,ITP患者治疗后CD4+ T细胞表达pro-caspase-3和cleaved-caspase-3均明显减少(P＜0.05).结论ITP患者外周血T细胞Fas、FasL及caspase-3表达明显增加,激素治疗可干预Fas-FasL、caspase-3的表达水平,提示Fas、FasL及caspase-3信号通路在ITP发生机制中起一定作用.     

KD5170, a novel mercaptoketone-based histone deacetylase inhibitor, exerts antimyeloma effects by DNA damage and mitochondrial signaling

Histone deacetylase inhibitors have emerged as promising anticancer drugs. Using an unbiased ultrahigh throughput screening system, a novel mercaptoketone-based histone deacetylase inhibitor series was identified that was optimized to the lead compound, KD5170. KD5170 inhibited the proliferation of myeloma cell lines and the viability of CD138(+) primary myeloma cells by induction of apoptosis, accompanied by an increase of acetylation of histones and activation of caspase-3, caspase-8, and caspase-9. Treatment with KD5170 caused a loss of mitochondrial membrane potential resulting in release of apoptogenic factors such as cytochrome c, Smac, and apoptosis-inducing factor. Furthermore, KD5170 induced oxidative stress and oxidative DNA damage in myeloma cells as evidenced by the up-regulation of heme oxygenase-1 and H2A.X phosphorylation. Combination of KD5170 with proteasome inhibitor bortezomib or tumor necrosis factor-related apoptosis-inducing ligand synergistically enhanced the antimyeloma activity. We further found that resistance of myeloma cells to KD5170 was associated with activation of the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway under treatment with KD5170. Pretreatment with the mitogen-activated protein kinase inhibitor U0126 restored sensitivity to KD5170, suggesting that the combination of KD5170 with U0126 could overcome drug resistance. Growth of myeloma tumor xenografts in KD5170-treated nude mice was significantly inhibited and survival was prolonged. Histone acetylation was increased in spleen and tumor tissues of animals treated with KD5170. Our data indicate that KD5170 has potent antimyeloma activity in vitro and in vivo, which is mediated by DNA damage and mitochondrial signaling and subsequent induction of apoptosis.     

Fas和FasL在Na+/H+交换器-1抑制诱导缺氧大鼠肺动脉平滑肌细胞凋亡中的作用

目的探讨Fas、FasL在Na^＋／H^＋交换器-1（NHE-1）抑制所诱导的缺氧大鼠肺动脉平滑叽细胞（PASMCs）凋亡中的作用。方法将转染NHE-1特异性核酶基因的大鼠PASMCs置于缺氧条件下（O2的体积分数低下1％）培养。缺氧培养2、6、12、24和48h后用原位末端标记法（TUNEL）检测细胞凋亡情况；半定量逆转录-聚合酶链反应（sqRT—PCR）疗法检测细胞内fas和fasL mRNA表达变化；免疫细胞化学法检测细胞内Fas和FasL蛋白表达变化。结果转染NHE-1特异性核酶基因的大鼠PASMCs在缺氧培养时，其细胞凋亡率随缺氧时间的延长而逐渐升高，但细胞内fas、fasL mRNA及Fas、FasL蛋白表达与对照组细胞比较差异均无显著性。结论Fas／FasL死亡通路可能不参与NHE-1抑制而诱导缺氧大鼠PASMCs凋亡的调控。     

依曲替酸上调Fas、FasL诱导皮肤鳞癌细胞凋亡的实验研究

目的：探讨依曲替酸通过上调Fas、FasL基因表达诱导皮肤鳞状细胞癌（鳞癌）细胞系SCC13细胞凋亡的作用。方法：以体外培养的人皮肤鳞癌细胞系SCC13细胞为研究对象,采用酶联免疫分析法（ELISA）、AnnxinV-FITC/PI法检测凋亡的诱导情况。用实时荧光定量RT-PCR方法检测Fas、FasL mRNA的表达。用Fas中和抗体ZB4检测Fas、FasL在依曲替酸诱导SCC13细胞凋亡中的作用。结果：依曲替酸能诱导SCC13细胞凋亡,并具有浓度及时间依赖性。依曲替酸能上调肿瘤细胞内Fas、FasL mRNA表达水平。单独应用依曲替酸的早期凋亡率为（16.76±1.04）%,与ZB4共同处理SCC13后,早期凋亡率下降为（7.12±0.85）%,ZB4显著阻断依曲替酸诱导的凋亡（P〈0.05）。结论：依曲替酸能诱导皮肤鳞状细胞癌细胞凋亡,其机制可能与Fas死亡受体信号转导途径有关。