Nox2 B-loop peptide, Nox2ds, specifically inhibits the NADPH oxidase Nox2

In recent years, reactive oxygen species (ROS) derived from the vascular isoforms of NADPH oxidase, Nox1, Nox2, and Nox4, have been implicated in many cardiovascular pathologies. As a result, the selective inhibition of these isoforms is an area of intense current investigation. In this study, we postulated that Nox2ds, a peptidic inhibitor that mimics a sequence in the cytosolic B-loop of Nox2, would inhibit ROS production by the Nox2-, but not the Nox1- and Nox4-oxidase systems. To test our hypothesis, the inhibitory activity of Nox2ds was assessed in cell-free assays using reconstituted systems expressing the Nox2-, canonical or hybrid Nox1-, or Nox4-oxidase. Our findings demonstrate that Nox2ds, but not its scrambled control, potently inhibited superoxide (O₂^•−) production in the Nox2 cell-free system, as assessed by the cytochrome c assay. Electron paramagnetic resonance confirmed that Nox2ds inhibits O₂^•− production by Nox2 oxidase. In contrast, Nox2ds did not inhibit ROS production by either Nox1- or Nox4-oxidase. These findings demonstrate that Nox2ds is a selective inhibitor of Nox2-oxidase and support its utility to elucidate the role of Nox2 in organ pathophysiology and its potential as a therapeutic agent.     

p16和Ki67在非小细胞肺癌组织中的表达及其与预后的关系

目的探讨p16和Ki67在非小细胞肺癌（non-small cell lung cancer,NSCLC）中的表达,研究它们对NSCLC患者预后的影响及其与临床及病理因素之间的关系。方法收集NSCLC术后标本160例及正常肺组织20例（对照组）,应用免疫组化法检测NSCLC组织和正常肺组织中p16和Ki67的表达。结果在NSCLC组织和正常肺组织中,p16和Ki67的阳性表达率分别为23.8%、82.5%和90%、5%,差异有统计学意义（P〈0.05）。多因素分析：PTNM分期、淋巴结转移、p16及Ki67的表达是影响NSCLC根治术后患者预后的独立因素（P〈0.05）;p16阳性组与阴性组5年生存率分别为55.3%和18.0%,差异有统计学意义（P〈0.05）;Ki67阳性组与阴性组5年生存率分别为23.5%和42.9%,差异有统计学意义（P〈0.05）,p16和Ki67表达呈负相关（P〈0.05）。结论 p16和Ki67参与了NSCLC的发生发展,p16和Ki67的表达水平与NSCLC的发展及预后有一定的关系。     

鼻咽癌组织ki67 表达与外周血NK 细胞的关系及意义

目的:研究鼻咽癌组织Ki67的表达及外周血NK细胞水平的意义。方法:检测66例鼻咽癌组织Ki67水平及与外周血NK细胞的百分含量。结果:Ki67表达阳性率为96.97%,与临床分期有关(r=0.290,P=0.030<0.05),与淋巴结转移状态相关性在统计学上无意义(r=0.068,P=0.412>0.05);放疗前中后鼻咽癌外周NK细胞水平差别均有统计学意义(前中、中后、前后F=0.513,0.627,0.623,P分别为0.005,0.004,0.000,均<0.05);ki67的表达与放疗后NK细胞NK值负相关(r=-0.433,P=0.017<0.05)。结论:Ki67的表达可能与临床分期有关,可能与放疗后NK值有关;Ki67表达与外周血NK细胞水平可以提示鼻咽癌组织增殖活跃程度和机体防御系统的状态。     

Apoptosis and production of TNF-α by tumor-associated inflammatory cells in histological grade III breast cancer

Tumor necrosis factor alpha (TNF-) is a cytokine that acts as an important mediator of the apoptotic process that also demonstrates selective citotoxicity against malignant breast tumor cells. In the present study, the presence of apoptotic tumor cells and the synthesis of TNF- by inflammatory cells were investigated in tissue samples from grade III invasive breast cancer with long-term follow-up. In situ detection of tumor apoptotic cells was investigated by direct immuno-peroxidase of digoxigenin-labeled genomic DNA. The production of TNF- and tumor cell proliferation were investigated by immunohistochemical procedures. Our data demonstrated that patients with a clinical history of cancer recurrence and metastasis presented a lower number of cancerous apoptotic cells, higher tumor proliferation rates, and lower TNF- expression rates by inflammatory cells than what is observed among patients diagnosed with the same histopathological breast cancer type but in the absence of tumor recurrence and metastasis.     

Evidence of a dominant negative mutant of yeast methionine aminopeptidase type 2 in Saccharomyces cerevisiae

Eukaryotic methionine aminopeptidase type 2 (MetAP2, MetAP2 gene (MAP2)), together with eukaryotic MetAP1, cotranslationally hydrolyzes initiator methionine from nascent polypeptides when the side chain of the second residue is small and uncharged. In this report, we took advantage of the yeast (Saccharomyces cerevisiae) map1 null strain's reliance on MetAP2 activity for the growth and viability to provide evidence of the first dominant negative mutant of eukaryotic MetAP2. Replacement of the conserved His(174) with alanine within the C-terminal catalytic domain of yeast MetAP2 eliminated detectable catalytic activity against a peptide substrate in vitro. Overexpression of MetAP2 (H174A) under the strong GPD promoter in a yeast map1 null strain was lethal, whereas overexpression under the weaker GAL1 promoter slightly inhibited map1 null growth. Deletion mutants further revealed that the N-terminal region of MetAP2 (residues 2-57) is essential but not sufficient for MetAP2 (H174A) to fully interfere with map1 null growth. Together, these results indicate that catalytically inactive MetAP2 is a dominant negative mutant that requires its N-terminal region to interfere with wild-type MetAP2 function.     

In vivo dynamics and kinetics of pKi-67: transition from a mobile to an immobile form at the onset of anaphase

A cell proliferation marker protein, pKi-67, distributes to the chromosome periphery during mitosis and nucleolar heterochromatin in the interphase. We report here on the structural domains of pKi-67 that are required for its correct distribution. While both the LR domain and the conserved domain were involved in localization to the nucleolar heterochromatin, both the LR domain and the Ki-67 repeat domain were required for its distribution to the mitotic chromosome periphery. Using in vivo time-lapse microscopy, GFP-pKi-67 was dynamically tracked from the mitotic chromosome periphery to reforming nucleoli via prenucleolar bodies (PNBs). The signals in PNBs then moved towards and fused into the reforming nucleoli with a thin string-like fluorescence during early G1 phase. An analysis of the in vivo kinetics of pKi-67 using photobleaching indicated that the association of pKi-67 with chromatin was progressively altered from "loose" to "tight" after the onset of anaphase. These findings indicate that pKi-67 dynamically alters the nature of the interaction with chromatin structure during the cell cycle, which is closely related to the reformation process of the interphase nucleolar chromatin.     

Eukaryotic initiation factor 2-associated glycoprotein, p67, shows differential effects on the activity of certain kinases during serum-starved conditions

Phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 is the major regulatory step in the initiation of protein synthesis in mammals. P67, a cellular glycoprotein, protects phosphorylation of eIF2alpha from kinases. P67 has five conserved amino acid residues at the D251, D262, H331, E364, and E459 positions. To determine the roles of these conserved amino acid residues in eIF2alpha phosphorylation during serum-starved conditions, we constitutively expressed D251A, D262A, H331A, E364A, and E459A mutants in rat tumor hepatoma cells. We find that the point mutants D251A, H331A, and E364A lower the levels of eIF2alpha phosphorylation. These low levels of phosphorylation decrease when serum-starved cells are grown in medium containing serum. To understand the mechanism of action of the p67 mutants in eIF2alpha phosphorylation during serum-starvation, we performed detailed biochemical analyses with the D251A mutant. We find that neither the O-GlcNAc modification on the D251A mutant nor the binding of D251A mutant with eIF2gamma has significant effects on eIF2alpha phosphorylation during serum-starved conditions. However, the D251A mutant inhibits p67's activity to suppress the activity of ERK1/2. Our data suggest that both p67 and the D251A mutant bind to ERK1, thus strengthening the idea that p67 regulates the activity of ERK1. During serum-starvation conditions, both PKR and PERK are phosphorylated and the D251A mutant shows increased stability of PERK as well as a slight decrease in its activity. Altogether, our data provide evidence to suggest that p67 modulates the expression and activity of certain eIF2alpha-specific kinases.     

Treatment with vector-expressed small hairpin RNAs against Ki67 RNA-induced cell growth inhibition and apoptosis in human renal carcinoma cells

Short hairpin RNAs (shRNAs) transcribed by.RNA polymerase Ⅲ promoters can triggersequence-selective gene silencing in mammalian cells.By virtue of their excellent function in knocking downexpression of cancer-associated genes,shRNAs could be used as new therapeutic agents for cancer.Asoverexpression of Ki67 in renal cancer has been correlated to a more aggressive tumor phenotype,inhibitionof Ki67 protein expression by means of shRNAs seems to be a promising approach for the therapy of renalcancer.In this study,we constructed an expression plasmid encoding shRNAs against the Ki67 gene,namedpSilencerKi67,and transfected it into human renal carcinoma cells.The pSilencerKi67 was shown to signifi-cantly knock down the expression of the Ki67 gene in human renal carcinoma cells,resulting in inhibitingproliferation and inducing apoptotic cell death that can be maintained for at least 6d.These findings offer thepromise of using vector-based shRNAs against Ki67 in renal cancer gene therapy.     

金葡菌L型感染致小鼠肿瘤中Survivin、Ki-67的表达及意义

目的探讨金黄色葡萄球菌(金葡菌)L型感染C57小鼠致瘤后,凋亡蛋白抑制因子(Survivin)和增殖细胞核相关抗原(Ki-67)在小鼠肿瘤及癌前病变中的表达及相关性研究。方法动物实验观察金葡菌L型感染90只C57小鼠后11.1%(10/90)小鼠发生肿瘤,14.4%(13/90)小鼠引起癌前病变。革兰染色、免疫组化及原位杂交检测小鼠肿瘤和癌前病变中金葡菌L型检出率和Survivin、Ki-67蛋白及cDNA的表达。结果10只小鼠肿瘤及13只小鼠癌前病变中金葡菌L型检出率及其cDNA阳性表达与正常对照组差异有非常显著性(P0.005~0.01);Survivin、Ki-67蛋白和cDNA的阳性表达与正常对照组差异有显著性(P0.01~0.05),呈正相关。结论金葡菌L型感染可能与Survivin、Ki-67基因协同在小鼠肿瘤发生和发展中起重要作用。     

COX-2、Ki-67和结核菌L型感染在前列腺癌中的表达

目的探讨环氧合酶-2（COX-2）和Ki-67在前列腺癌中的表达以及结核菌L型感染率及临床意义。方法应用免疫组化、原位杂交和抗酸染色等方法检测了65例前列腺癌（carcinoma of prostate,PCa）和30例良性前列腺增生（benign prostatic hyperplasia,BPH）中的COX-2、Ki-67蛋白及mRNA的表达,以及结核菌L型的检出率;并对前列腺肿瘤主要临床资料和病理分级参数进行比较,用χ^2检验进行统计学处理。结果COX-2、Ki-67蛋白及mRNA阳性表达和结核菌L型检出率,前列腺癌明显高于前列腺增生（P〈0.001～0.05）。COX-2、Ki-67蛋白及mRNA阳性表达和结核菌L型检出率与前列腺癌的临床分期、病理分级有明显差异（P〈0.01～0.05）。淋巴结转移组中COX-2、Ki-67蛋白及mRNA的阳性表达率明显高于非转移组（P〈0.01）。结核菌L型检出率淋巴结转移组明显高于非转移组（P〈0.05）。结论COX-2、Ki-67蛋白及mRNA在前列腺肿瘤中不同程度异常表达以及结核菌L型检出率与肿瘤的临床分期、病理分级和转移呈正相关,提示2种基因均可作为判断前列腺癌生物学行为及患者预后参考指标。结核菌L型感染极有可能导致基因的变异或过表达,成为诱发肿瘤因素之一,它们可能有协同致瘤作用。