上调基因4与癌症

上调基因4（up-regulated gene-4,URG4）是受乙肝病毒X蛋白（hepatitis B virus X protein,HBx）激活的下游基因之一,最初在转染HBx的HepG2细胞中被克隆,因其上调细胞增殖效应而得名。与未转染的细胞相比,URG4在HBx转染后的HepG2细胞中表达明显增加,证实了URG4与乙肝病毒相关的肝细胞癌发生相关。近年来,人们发现URG4不仅在肝癌细胞中高表达,还与胃癌、骨肉瘤、非小细胞肺癌、神经母细胞瘤等多种癌症相关。本文结合近年来对URG4的研究成果,包括URG4基因及其蛋白质的结构与功能,URG4在癌症发生发展中的作用,以及在癌症早期诊断和预后中的意义进行综述,可望为后续深入地开展URG4与癌症的研究提供参考。     

Leukotrienes C4, D4, and E4 in fetal lamb tracheal fluid

Previously, we demonstrated that either putative leukotriene receptor antagonists or a synthesis inhibitor markedly decreased pulmonary vascular resistance in the near-term fetal lamb and concluded that leukotrienes may play a role in maintaining the high pulmonary vascular resistance in the fetus. To further investigate the role of leukotrienes, we measured concentrations of leukotriene (LT) C4, LTD4, and LTE4 in 17 tracheal fluid samples from 8 of 9 near-term (129-139 days, term = 145 days), chronically-catheterized, fetal lambs during normoxia to evaluate their possible role in regulating resting tone and in seven of the nine before and during hypoxia to evaluate their possible role in hypoxic vasoconstriction. The tracheal fluid samples collected by gravity over 1-3 min, on ice, were immediately treated with cold ethanol, centrifuged, and the supernatant covered with N2 and stored in a -70 degrees C freezer for a maximum of 3 weeks. Purification and separation of leukotrienes was done by reverse-phase high performance liquid chromatography using a gradient elution method, and fractions corresponding to LTC4, LTD4, and LTE4 standards were quantified immediately by radioimmunoassay. During normoxia (descending aortic PaO2 2.9 +/- 0.3 kPa [21.5 +/- 2.5 mmHg]; mean +/- SD), all 3 leukotrienes were detected in 16 of the 17 samples: LTC4 29 +/- 28 pg/ml (range 0-119 pg/ml); LTD4 66 +/- 51 pg/ml (range 9-177 pg/ml); and LTE4 43 +/- 50 pg/ml (range 0-204 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Pulmonary microcirculatory responses to leukotrienes B4, C4 and D4 in sheep

The pulmonary microvascular responses to leukotrienes B4, C4, and D4 (total dosage of 4 micrograms/kg i.v.) were examined in acutely-prepared halothane anesthetized and awake sheep prepared with lung lymph fistulas. In anesthetized as well as unanesthetized sheep, LTB4 caused a marked and transient decrease in the circulating leukocyte count. Pulmonary transvascular protein clearance (pulmonary lymph flow X lymph-to-plasma protein concentration ratio) increased transiently in awake sheep, suggesting a small increase in pulmonary vascular permeability. The mean pulmonary artery pressure (Ppa) also increased. In the acutely-prepared sheep, the LTB4-induced pulmonary hemodynamic and lymph flow responses were damped. Leukotriene C4 increased Ppa to a greater extent in awake sheep than in anesthetized sheep, but did not significantly affect the pulmonary lymph flow rate (Qlym) and lymph-to-plasma protein concentration (L/P) ratio in either group. LTD4 increased Ppa and Qlym in both acute and awake sheep; Qlym increased without a significant change in the L/P ratio. The LTD4-induced rise in Ppa occurred in association with an increase in plasma thromboxane B2 (TxB2) concentration. The relatively small increase in Qlym with LTD4 suggests that the increase in the transvascular fluid filtration rate is the result of a rise in the pulmonary capillary hydrostatic pressure. In conclusion, LTB4 induces a marked neutropenia, pulmonary hypertension, and may transiently increase lung vascular permeability. Both LTC4 and LTD4 cause a similar degree of pulmonary hypertension in awake sheep, but had different lymph flow responses which may be due to pulmonary vasoconstriction at different sites, i.e. greater precapillary constriction with LTC4 because Qlym did not change and greater postcapillary constriction with LTD4 because Qlym increased with the same rise in Ppa.     

Genetics of complement C4. Two homoduplication haplotypes C4S C4S and C4F C4F in a family

Summary A family in which two homoduplicated C4 haplotypes (or supergenes) segregate is described. One haplotype C4F ^* 3 C4F ^*2.2 is composed of two C4F alleles and the other C4S ^* 5.1 C4S ^*1 of two C4S alleles. The C4F duplication haplotype is a partial inhibitor of the Rodgers antigen, and judged from our family and population material, it seems to be rather frequent and associated with HLAB ^*35, Bf ^* F, and HLAD/DR ^*1. The C4S duplication haplotype is Rg(a-) and is not identified in individuals without another S, Ch(a+) variant.This work was supported by grant No 12-1727 from the Danish Medical Research Council     

Leukotrienes C4 and D4 in psoriatic skin lesions

Chemoattractant arachidonate lipoxygenase products have been recovered from the skin lesions of psoriasis, and may play a role in eliciting the intra-epidermal neutrophil infiltrate that characterises this disease. In view of evidence for lipoxygenase activity in psoriasis, the characteristic vasodilation in psoriatic lesions, and the vasodilator properties of leukotriene (LT) C4 and D4 in human skin, the presence of these LTs in psoriatic lesions has been investigated. Skin chamber fluid from abraded psoriatic lesions contained significantly greater amounts of immunoreactive material than that from clinically normal skin, as determined by a double antibody radioimmunoassay (RIA) that uses antiserum cross-reacting with both LTC4 and LTD4. Purification of lesional chamber fluid and scale extracts by high performance liquid chromatography (HPLC) and RIA of fractions showed immunoreactivity which co-eluted with standard LTC4 and LTD4. These findings suggest that LTC4 and LTD4 may play a role in mediating the vasodilation and increased blood flow that characterise psoriatic skin lesions.     

Catabolism of 4-Hydroxyacids and 4-Hydroxynonenal via 4-Hydroxy-4-phosphoacyl-CoAs

4-Hydroxyacids are products of ubiquitously occurring lipid peroxidation (C₉, C₆) or drugs of abuse (C₄, C₅). We investigated the catabolism of these compounds using a combination of metabolomics and mass isotopomer analysis. Livers were perfused with various concentrations of unlabeled and labeled saturated 4-hydroxyacids (C₄ to C₁₁) or 4-hydroxynonenal. All the compounds tested form a new class of acyl-CoA esters, 4-hydroxy-4-phosphoacyl-CoAs, characterized by liquid chromatography-tandem mass spectrometry, accurate mass spectrometry, and ³¹P-NMR. All 4-hydroxyacids with five or more carbons are metabolized by two new pathways. The first and major pathway, which involves 4-hydroxy-4-phosphoacyl-CoAs, leads in six steps to the isomerization of 4-hydroxyacyl-CoA to 3-hydroxyacyl-CoAs. The latter are intermediates of physiological β-oxidation. The second and minor pathway involves a sequence of β-oxidation, α-oxidation, and β-oxidation steps. In mice deficient in succinic semialdehyde dehydrogenase, high plasma concentrations of 4-hydroxybutyrate result in high concentrations of 4-hydroxy-4-phospho-butyryl-CoA in brain and liver. The high concentration of 4-hydroxy-4-phospho-butyryl-CoA may be related to the cerebral dysfunction of subjects ingesting 4-hydroxybutyrate and to the mental retardation of patients with 4-hydroxybutyric aciduria. Our data illustrate the potential of the combination of metabolomics and mass isotopomer analysis for pathway discovery.     

Anti-MS4a4B treatment abrogates MS4a4B-mediated protection in T cells and ameliorates experimental autoimmune encephalomyelitis

Recent data show that anti-CD20 therapy is effective for some autoimmune diseases, including multiple sclerosis (MS). However, the efficacy of anti-CD20 therapy for MS is largely limited because anti-CD20 antibodies target only B cells. In previous studies, we have investigated the function of MS4a4B, a novel CD20 homologue, in T cell proliferation. Here, we found that MS4a4B regulates not only T cell proliferation but also T cell apoptosis. Knockdown of MS4a4B by MS4a4B-siRNA or MS4a4B-shRNA-expressing vector promoted apoptosis in primary T cells and T32 cell line. In contrast, vector-driven over-expression of MS4a4B reduced apoptosis in EL-4 cells. Machinery analysis showed that MS4a4B-mediated T cell survival was associated with decreased activity of caspases 3, 8 and 9. Interestingly, binding of anti-MS4a4B antibodies to T cells induced activated T cells to undergo apoptosis. To test whether anti-MS4a4B antibody interferes with MS4a4B-mediated protection of T cells, we injected anti-MS4a4B antibodies into mice with experimental autoimmune encephalomyelitis (EAE). The results show that anti-MS4a4B treatment ameliorated the severity of EAE, accompanied by decreased Th1 and Th17 cell responses and reduced levels of pro-inflammatory cytokines in the central nervous system, suggesting that MS4a4B may serve as a target of antibody-based therapy for T cell-mediated diseases.     

Redox labile site in a Zn4 cluster of Cu4,Zn4-metallothionein-3

Human metallothionein-3 (MT-3) is a neuronal inhibitory factor mainly expressed in brain and downregulated in Alzheimer's disease. The neuroinhibitory activity has been established for native Cu(4),Zn(3)-MT-3 and recombinant Zn(7)-MT-3. However, there is only limited knowledge about the structure and properties of the former metalloform. We have now generated native-like MT-3 through direct Cu(I) and Zn(II) incorporation into the recombinant apoprotein. Its characterization revealed monomeric Cu(4),Zn(4)-MT-3 containing metal-thiolate clusters located in two mutually interacting protein domains, a Cu(4) cluster in the beta-domain and a Zn(4) cluster in the alpha-domain. Using the PC12 cell line, the nontoxic nature of the protein was demonstrated. The results of electronic absorption and Cu(I) luminescence at 77 K showed that the Cu(4) cluster possesses an unprecedented stability in air. In contrast, the Zn(4) cluster is air sensitive. Its oxidation results in the release of one Zn(II) and the formation of a Zn(3) cluster, i.e., Cu(4),Zn(3)-MT-3. This process can be prevented or reversed under reducing conditions. The determined apparent stability constant for the Zn(4) cluster of 2.4 x 10(11) M(-1) is similar to that obtained for other zinc-containing MTs. This suggests that a substantially increased nucleophilic reactivity of specific thiolate ligands is responsible for this effect. Thus, the Zn(4) cluster in MT-3 may play a redox-dependent regulatory role.     

Metabolism of LTC4 to LTD4 and LTE4 in isolated guinea pig lung lobes

Leukotrienes are known to be easily metabolized to other substances. But the metabolic fates of LTC4 and LTD4 have not been established in the intact lung. In this investigation we perfused isolated guinea pig lung lobes and injected synthesized LTC4 and LTD4. The effluent was assayed by HPLC. LTD4 and LTE4 were detected following perfusion of LTC4, and LTE4 was detected following perfusion of LTD4. These results suggest that perfused guinea pig lung lobes may metabolize LTC4 to LTD4 and LTE4, and LTD4 to LTE4.     

Bal31 sensitivity of micronuclear sequences homologous to C4A4/G4T4 repeats in Oxytricha nova

The sequence similarity and functional equivalence of telomeres from macronuclear linear DNA molecules in Oxytricha and telomeric sequences of true mitotic/meiotic chromosomes suggest that the (C4A4)n/(G4T4)n sequences found at macronuclear telomeres may also function as micronuclear telomeres in Oxytricha. In this study, radioactively labeled (C4A4)n have been hybridized to micronuclear DNA samples that have been treated with the enzyme Bal31, which has double-stranded exonuclease activity. A time course of digestion shows that approximately 50% of the micronuclear sequences that hybridize to a C4A4 probe disappear with mild digestion by Bal31, suggesting that these sequences are telomeric. The remainder of the hybridizing sequences are not degraded any more rapidly than the total genomic DNA. All of the C4A4/G4T4 sequences that can be detected by hybridization of C4A4 probes to Southern-blotted restriction enzyme digests of micronuclear DNA occur in regions of the genome that are highly resistant to restriction enzyme digestion and show a clustering of sites reminiscent of telomeres in other organisms. We propose that the micronuclear C4A4 hybridizable sequences that are Bal31 resistant may be located near the telomere and within telomere-associated repetitive sequences that are immediately internal to telomeric (Bal31 sensitive) C4A4 hybridizeable sequences.     

Methylation profile of INK4B-ARF-INK4A locus in atherosclerosis

Single-nucleotide polymorphisms (SNPs) in the 9p21.3 locus have recently been demonstrated to be strongly associated with atherosclerosis. However, the pathophysiology of this locus is insufficiently studied. Here, the methylation profile of the nearest mapped genes for cyclin-dependent kinase inhibitors CDKN2A (p16^INK4a, p14^ARF) and CDKN2B (p15^INK4b) in the tissues of the carotid artery in patients with atherosclerosis was evaluated for the first time. Aberrant DNA methylation of the analyzed loci was not established in either the atherosclerotic plaques or in the tissues from the macroscopically intact vascular wall in the same patients.     

Conversion of leukotrienes A4 to C4 in cell-free systems

A procedure for assaying leukotriene C4 synthase activity in cell-free extracts has been presented. Leukotriene A4 methyl ester was as active a substrate as leukotriene A4 (Na salt) for the synthesis. The methyl ester is the substrate of choice, because (1) it is more stable than the sodium salt, (2) it is not a substrate of epoxide hydrolase for leukotriene B4 synthesis, and (3) it gives a lower blank than an equimolar concentration of leukotriene A4. The enzyme activity in rat liver, guinea pig and human lungs, and human nasal polyp was chiefly membrane-bound, although the cytosol contained some activity.     

MicroRNA 421 suppresses DPC4/Smad4 in pancreatic cancer

Dihydroavenanthramide D (DHAvD) is a synthetic analog to naturally occurring avenanthramide, which is the active component of oat. Previous study demonstrates that DHAvD strongly inhibits activation of nuclear factor-kappa B (NF-κB), which is a major component in cancer cell invasion. The present study investigated whether DHAvD can modulate MMP-9 expression and cell invasion in MCF-7 human breast cancer cells. MMP-9 expression and cell invasion in response to 12-O-tetradecanoylphorbol-13-acetate (TPA) was increased, whereas these inductions were muted by DHAvD. DHAvD also suppressed activation of mitogen-activated protein kinase (MAPK), and MAPK-mediated nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1) activations in TPA-treated MCF-7 cells. The results indicate that DHAvD-mediated inhibition of TPA-induced MMP-9 expression and cell invasion involves the suppression of the MAPK/NF-κB and MAPK/AP-1 pathways in MCF-7 cells. DHAvD may have potential value in breast cancer metastasis.     

MAP4K4: an emerging therapeutic target in cancer

The serine/threonine kinase MAP4K4 is a member of the Ste20p (sterile 20 protein) family. MAP4K4 was initially discovered in 1995 as a key kinase in the mating pathway in Saccharomyces cerevisiae and was later found to be involved in many aspects of cell functions and many biological and pathological processes. The role of MAP4K4 in immunity, inflammation, metabolic and cardiovascular disease has been recognized. Information regarding MAP4K4 in cancers is extremely limited, but increasing evidence suggests that MAP4K4 also plays an important role in cancer and MAP4K4 may represent a novel actionable cancer therapeutic target. This review summarizes our current understanding of MAP4K4 regulation and MAP4K4 in cancer. MAP4K4-specific inhibitors have been recently developed. We hope that this review article would advocate more basic and preclinical research on MAP4K4 in cancer, which could ultimately provide biological and mechanistic justifications for preclinical and clinical test of MAP4K4 inhibitor in cancer patients.     

Immunosuppressive properties of leukotriene D4 and E4 in vitro

Leukotrienes D₄ and E₄ whose physiological function has been associated with smooth muscle contraction, are demonstrated to be potent suppressors of immunocompetent cell function. In concentrations as low as 10^?12 M both leukotriene D₄ and E₄ can inhibit mitogen-induced lymphocyte transformation. Higher concentrations of leukotrienes E₄ and D₄ will inhibit appearance of antibody-forming cells in tissue culture. These data suggest another role for the leukotrienes in addition to their function as slow-reacting substances.