Identification of two nuclear N-acetylglucosamine-binding proteins

Using neoglycoproteins, lectine that reconize different sugars, including N-acetylglucosamine residues, were previously detected in animal cell nuclei. We report herein the isolation of two N-acetylglucosamine-binding protein from HL60 cell nuclei:(i) a 22 kDa polypeptide (CBP22) with an isoelectric point of 4.5 was isolated for the first time and (ii) a 70 kDa polypeptide point of 7.8. This latter protein corresponds to the glucose-binding protein (CBP70) previously isolated, based on the following similsrties:(i) they have the same molecular mass, (ii)they have the same isoelectric point, (iii)they are recognized by antibodies raised against CBP70, and (iv) both are lectins from the C group of Drickamer's classsification. CBP70 appeared to recognized glucose and n-acetylglucosamine; howeve, its affinity for N-acetylglucosamine was found to be twice that for glucose. The presence in the nucleus of two nuclear N-acetylglucosamine-binding protein and their potential ligands, such as O-N-acetylglucosamine glycoproteins, strongly argues for possible intranuclear glycoprotein-lectine interactions.     

Chromosomal Assignments of Novel Genes Expressed in HL60 Granulocytes

By collecting 3'-directed cDNA sequences called gene signatures(GSs) on a large scale, it is possible to make an expressionprofile of genes in a particular tissue, as well as discoveringa number of novel genes. A total of 305 novel GSs collectedfrom granulocytoid cells derived from HL60, a human promyelocyticleukemia cell line, by exposure to dimethyl sulfoxide were radiolabeledand used for Southern blot analyses to determine the copy numberof the corresponding genes. Of these, 198 GSs identified asrepresenting single-copy genes were then used as probes forhybridization analyses using a monochromosomal hybrid cell DNApanel. Sixty-nine of them were assigned to individual chromosomes.These results demonstrate that the chromosomal distributionof the GSs seems not to be proportional to the cytogenetic lengthof each chromosome.     

Purification and properties of two different α1-protease inhibitors from mouse plasma

Two similar but distinct forms of α1-protease inhibitor (α1-PI) have been isolated and purified 120-fold to homogeneity from the plasma of female, white Swiss (Ha/ICR) mice. The two inhibitors can be separated by chromatography on DEAE-cellulose using a shallow NaCl gradient at pH 8.9 for elution. Because of their differing specificities for elastase and trypsin we have labeled the two inhibitors α1-PI(E) and α1-PI(T), respectively. The apparent M_r for both proteins, as estimated by gel exclusion chromatography, is approximately 53,000 daltons. However by polyacrylamide gel electrophoresis in the presence of SDS, α1-PI(T) has an apparent m_r of 65,000 while the apparent m_r of α1-PI(E) is 55,000. These results suggest differences in charge and carbohydrate composition. The two mouse inhibitors also have different AT-terminal amino acids. Like human α1-PI the mouse inhibitors form stable complexes with proteases. However they differed from human α1-PI in that they were not found to neutralize either human thrombin or plasmin. While α1-PI(E) inhibits bovine pancreatic trypsin, chymotrypsin, and porcine pancreatic elastase, α1-PI(T) is an effective inhibitor only of trypsin. Plasma levels of α1-PI(E) increase significantly 24 h after stimulation of the acute phase reaction while those of α1-PI(T) do not. Our data suggest that α1-PI(E) and α1-PI(T) are products of different genes.     

Protein kinase C activity following exposure to magnetic field and phorbol ester

We examined the separate and combined effects of 60 Hz sinusoidal magnetic fields (MFs) and a phorbol ester on protein kinase C (PKC) activity in HL60 cells. No enhancement in PKC activity was observed when a cell culture was exposed to a 1.1 mT (rms) MF alone or to a combination of MF and 2 μM phorbol 12-myristate 13-acetate (PMA) for 1 h. In a second set of experiments, cells were preexposed to a less than optimal concentration of PMA (50 nM) for 45 min, followed by a 15 min exposure to both PMA and MF. The data showed a greater decrease in cytosolic PKC activity and a larger increase in membrane activity than was induced by either 1 h PMA treatment alone or PMA and sham MF exposure. One logical conclusion from these data is that MFs may be acting in a synergistic manner on a pathway that has already been activated. Therefore, we suggest that MFs, rather than producing biological effects by a new pathway or mechanism of interaction, exert their effect(s) by interacting with already functioning reactions or pathways. If correct, the question of an MF's mechanism of interaction refocuses on how weak fields might enhance or depress a molecular reaction in progress, rather than on finding a new transduction pathway. Bioelectromagnetics 19:469–476, 1998. © 1998 Wiley-Liss, Inc.     

高压氧在放射性核素治疗大鼠种植癌后乏氧研究

目的：研究大鼠种植癌在高压氧（HBO）干预及放射治疗前后99mTc-HL91乏氧显像的变化,并探讨其与病理学改变之间的关系,为HBO联合放射性药物对恶性肿瘤治疗效果提供实验支持。方法：建立肿瘤株walker-256细胞大鼠皮下种植癌的动物模型,60只荷瘤大鼠随机分为四组：对照组,高压氧（HBO）组、胶体磷[^32P]酸铬和HBO＋胶体磷[^32P]酸铬组。尾静脉注射99mTc-HL9137MBq（0．1mL）,4h后利用SPECT显像,计算肿瘤组织与对侧相应部位放射性计数比值（T小T）,显像当日游标卡尺测量肿瘤最大长径（a）和最大垂直横径（b）,计算肿瘤体积以及治疗后不同时间的肿瘤生长率（f）。最后一次显像结束后处死全部模型大鼠,取肿瘤组织制成病理切片,观察各组大鼠肿瘤细胞的凋亡情况。比较实验各组T／NT与肿瘤生长率（f）以及凋亡的关系。结果：肿瘤99mTc-HL91显像良好,肿瘤部位与对侧相应部位具有较高的放射性计数比。治疗后大鼠肿瘤的乏氧区域及肿瘤体积均减少,以HBO＋胶体磷[^32P]酸铬组为著,T／NT与f呈正相关;大鼠肿瘤的细胞凋亡数明显高于对照组,以HBO＋胶体磷[^32P]酸铬组增加明显,治疗后T／NT与大鼠肿瘤细胞的凋亡数呈负相关。结论：HBO在放射性核素治疗大鼠种植癌中起到协同作用,通过99mTc—HL91乏氧显像观察HBO干预后胶体磷[^32P]酸铬治疗肿瘤效果,从而为二者联合在肿瘤治疗的应用提供依据。     

Phosphoprotein levels,MAPK activities and NFκB expression are affected by fisetin

Flavonoids, polyphenolic phytochemicals, are ubiquitous in plants and are commonly present in the human diet. They may exert diverse beneficial effects, including antioxidant and anticarcinogenic activities. The present study was designed to evaluate three biomolecules that play important roles in the apoptotic process: mitogen-activated protein kinases, protein phosphatases and NFκB, using HL60 cells treated with fisetin as an experimental model. Our results demonstrated that cells treated with fisetin presented high expression of NFκB, activation of MAPK p38 and an increase of phosphoprotein levels; inhibition of enzymes involved in redox status maintenance were also observed. Our findings reinforce the hypothesis that fisetin is likely to exert beneficial and/or toxic actions on cells not through its potential as antioxidant but rather through its modulation of protein kinase and phosphatase signaling cascades. Additionally, our results also indicate that the cellular effects of fisetin will ultimately depend on the cell type and on the extent to which they associate with the cells, either by interactions at the membrane or by uptake into the cytosol.     

Pro-apoptotic versus anti-apoptotic properties of dietary resveratrol on tumoral and normal cardiac cells

Resveratrol is a natural dietary polyphenol found in grape skin, red wine, and various other food products. Resveratrol has proved to be an effective chemopreventive agent for different malignant tumors. It has also been shown to prevent vascular alterations such as atherosclerosis and inflammatory-associated events. In view of these observations, we investigated the anti-proliferative and pro-apoptotic activities of resveratrol on a tumoral cardiac cell line (HL-1 NB) derived from mouse tumoral atrial cardiac myocytes. These effects were compared with those found on normal neonatal mouse cardiomyocytes. HL-1 NB cells and neonatal cardiomyocytes were treated with resveratrol (5, 30, and/or 100 μM) for different times of culture (24, 48, and/or 72 h). Resveratrol effects were determined by various microscopical and flow cytometric methods. After resveratrol treatment, a strong inhibition of tumoral cardiac HL1-NB cell growth associated with a loss of cell adhesion was observed. This cell proliferation arrest was associated with an apoptotic process revealed by an increased percentage of cells with fragmented and/or condensed nuclei (characteristic of apoptotic cells) identified after staining with Hoechst 33342 and by the presence of cells in subG1. At the opposite, on normal cardiomyocytes, no cytotoxic effects of resveratrol were observed, and a protective effect of resveratrol against norepinephrine-induced apoptosis was found on normal cardiomyocytes. Altogether, the present data demonstrate that resveratrol (1) induces apoptosis of tumoral cardiac HL1-NB cells, (2) does not induce cell death on normal cardiomyocytes, and (3) prevents norepinephrine-induced apoptosis on normal cardiomyocytes.     

Antioxidant protective effect of flavonoids on linoleic acid peroxidation induced by copper(II)/ascorbic acid system

Antioxidants are compounds that can delay or inhibit lipid oxidation. The peroxidation of linoleic acid (LA) in the absence and presence of Cu(II) ion–ascorbate combinations was investigated in aerated and incubated emulsions at 37 °C and pH 7. LA peroxidation induced by copper(II)–ascorbic acid system followed first order kinetics with respect to hydroperoxides concentration. The extent of copper-initiated peroxide production in a LA system assayed by ferric thiocyanate method was used to determine possible antioxidant and prooxidant activities of the added flavonoids. The effects of three different flavonoids of similar structure, i.e. quercetin (QR), morin (MR) and catechin (CT), as potential antioxidant protectors were studied in the selected peroxidation system. The inhibitive order of flavonoids in the protection of LA peroxidation was: morin > catechin ≥ quercetin, i.e. agreeing with that of formal reduction potentials versus NHE at pH 7, i.e. 0.60, 0.57 and 0.33 V for MR, CT, and QR, respectively. Morin showed antioxidant effect at all concentrations whereas catechin and quercetin showed both antioxidant and prooxidant effects depending on their concentrations. The structural requirements for antioxidant activity in flavonoids interestingly coincide with those for Cu(II)-induced prooxidant activity, because as the reducing power of a flavonoid increases, Cu(II)–Cu(I) reduction is facilitated that may end up with the production of reactive species. The findings of this study were evaluated in the light of structure–activity relationships of flavonoids, and the results are believed to be useful to better understand the actual conditions where flavonoids may act as prooxidants in the preservation of heterogeneous food samples containing traces of transition metal ions.     

Proanthocyanidins from Barley Bran Potentiate Retinoic Acid-induced Granulocytic and Sodium Butyrate-induced Monocytic Differentiation of HL60 Cells

Polyphenol extract from barley bran (BPE) induced nitro blue tetrazolium (NBT) reducing activity and alpha-naphthyl butyrate esterase activity in HL60 human myeloid leukemia cells. Because BPE induced the biochemical markers of HL60 cell differentiation, we investigated the effects of proanthocyanidins isolated from BPE on the HL60 cell differentiation of HL60 cells. Prodelphinidin B-3, T1, T2, and T3 induced 26-40% NBT-positive cells and 22-32% alpha-naphthyl butyrate esterase-positive cells. Proanthocyanidins potentiated retinoic acid (all-trans-retinoic acid)-induced granulocytic and sodium butyrate-induced monocytic differentiation in HL60 cells.