Histone hyperacetylation is involved in the quercetin-induced human leukemia cell death

Quercetin (QU) is recognized as a promising anticancer drug, but its mechanism remains elusive. Here we found that QU induced human leukemia cell death in a dose-dependent manner. However, it did not show a dose-dependent inhibition on ROS generation (indicated by the level of malondialdehyde, MDA) in the same cells. QU showed similar antioxidant activity at concentrations of 50, 75 and 100 microM. Consistent with that, the antioxidant, N-acetyl-cysteine (NAC) could only further decrease the ROS generation and enhance the cell death triggered by QU at the concentrations less than 50 microM. These results indicate that an additional mechanism is involved in the anticancer activity of high concentrations of QU. When the effect of QU on histone acetylation was studied, QU induced significant histone hyperacetylation at 75 and 100 microM, indicating the possible involvement of histone hyperacetylation in the anticancer activity of high concentrations of QU. This conclusion was supported by the findings that when histone acetylation in the cells treated by QU was increased by different concentrations of TSA, the cell death was significantly enhanced. Our results thus provide the first evidence that QU can induce histone hyperacetylation and this induction of histone hyperacetylation may represent an unrevealed mechanism in its anticancer activity.     

Calcineurin-NFAT signaling is involved in phenylephrine-induced vascular smooth muscle cell proliferation

Aim： Catecholamine-induced vascular smooth muscle cell （VSMC） proliferation is one of the major events in the pathogenesis of atherosclerosis and vascular remodeling. The calcineurin-NFAT pathway plays a role in regulating growth and differentiation in various cell types. We investigated whether the calcineurin-NFAT pathway was involved in the regulation of phenylephrine-induced VSMC proliferation. Methods： Proliferation of VSMC was measured using an MTT assay and cell counts. Localization of NFATcl was detected by immunofluorescence staining. NFATcl-DNA binding was determined by EMSA and luciferase activity analyses. NFATcl and calcineurin levels were assayed by immunoprecipitation. Results： Phenylephrine （PE, an α1-adrenoceptor agonist） increased VSMC proliferation and cell number. Prazosin （an α1-adrenoceptor antagonist）, cyclosporin A （CsA, an inhibitor of calcineurin） and chelerythrine （an inhibitor of PKC） decreased PE-induced proliferation and cell number. Additional treatment of VSMC with CsA or chelerythrine further inhibited proliferation and cell number in the chelerythrine-pretreatment group and the CsA-pretreatment group. CsA and chelerythrine alone had no effect on either absorbance or cell number. CsA decreased PE-induced calcineurin levels and activity. NFATcl was translocated from the cytoplasm to the nucleus upon treatment with PE. This translocation was reversed by CsA. CsA decreased the PE-induced NFATcl level in the nucleus. PE increased NFAT＇s DNA binding activity and NFAT-dependent reporter gene expression. CsA blocked these effects. Conclusion： CsA partially suppresses PE-induced VSMC proliferation by inhibiting calcineurin activity and NFATcl nuclear translocation. The calcineurin-NFATcl pathway is involved in the hyperplastic growth of VSMC induced by phenylephrine.     

Glutamate excitotoxicity is involved in cell death caused by tributyltin in cultured rat cortical neurons.

Tributyltin, an endocrine-disrupting chemical, has been used as a heat stabilizer, agricultural pesticide, and component of antifouling paints. In this study, the neurotoxicity of tributyltin was investigated in cultured rat cortical neurons. Tributyltin caused marked time- and dose-dependent increases in the number of trypan blue-stained cells. Measurement of extracellular glutamate concentration showed that glutamate release was induced by tributyltin. Application of the glutamate receptor antagonists MK-801 and CNQX decreased the neurotoxicity. These results suggest that released glutamate and glutamate receptors are involved in tributyltin toxicity. Next, we examined whether various factors, believed to be involved in glutamate excitotoxicity also influence tributyltin toxicity. Cell death induced by tributyltin was found to be reduced by alpha-tocopherol (a membrane-permeable antioxidant), SB202190 (a p38 mitogen-activated protein kinase inhibitor), and U-0126 (an extracellular signal-regulated protein kinase kinase inhibitor). MK-801 and CNQX decreased the phosphorylation of ERK, but not that of p38. A caspase-3 inhibitor had no effect on tributyltin toxicity, and tributyltin did not change the nuclear morphology. These results suggest that the glutamate excitotoxicity caused by tributyltin is unrelated to apoptosis. In conclusion, we demonstrated that tributyltin induced glutamate release and subsequent activation of glutamate receptors, leading to neuronal death. We propose two independent neuronal death pathways by tributyltin; one is glutamate receptor-dependent cell death via ERK phosphorylation, and the other may be glutamate receptor-independent cell death via p38 activation.     

Mitochondrial dysfunction, apoptotic cell death, and Alzheimer's disease

Being major sources of reactive oxygen species (ROS), mitochondrial structures are exposed to high concentrations of ROS and might therefore be particularly susceptible to oxidative injury. Mitochondrial damage may play a pivotal role in the cell death decision. Bolstered evidence indicates that mitochondrial abnormalities might be part of the spectrum of chronic oxidative stress occurring in Alzheimer’s disease (AD) finally contributing to synaptic failure and neuronal degeneration. Accumulation and oligomerization of amyloid beta (Aβ) is also thought to play a central role in the pathogenesis of this disease by probably directly leading to mitochondrial dysfunction. Moreover, numerous lines of findings indicate increased susceptibility to apoptotic cell death and increased oxidative damage as common features in neurons from sporadic AD patients but also from familial AD (FAD) cases. Here we provide a summary of recent work demonstrating some key abnormalities that may initiate and promote pathological events in AD. Finally, we emphasize a hypothetical sequence of the pathogenic steps linking sporadic AD, FAD, and Aβ production with mitochondrial dysfunction, caspase pathway, and neuronal loss.     

Effects of cadmium on cell death and cell proliferation in chick embryos

The aim of this study was to examine cell death and cell proliferation in chick embryos destined to have ventral body wall defects as a result of cadmium (Cd) treatment. Embryos in shell-less culture were treated with 50 μL Cd acetate (8.9 × 10⁻⁵ M Cd²⁺) at Hamilton–Hamburger (H.–H.) stage 16–17, or with equimolar sodium acetate. TdT-Mediated dUTP nick end labelling (TUNEL) showed the mode of cell death to be apoptosis commencing 4 h after treatment in somites and neural tube. Desquamation also occurred in the peridermal layer of the ectoderm. Cd caused no changes in the S-phase population of any tissue except ectoderm. The peridermal layer of the latter had a 40% reduction in labeling index (LI) 5.25 h after treatment but increased thereafter, being 30% greater than control values at 25.25 h. The occurrence of gross malformation was strongly correlated with the degree of apoptosis and in turn with the extent of peridermal desquamation. Pre-treatment with zinc acetate (10× the dose of Cd) prevented gross malformation, apoptosis and the effect of Cd on peridermal proliferation. We hypothesize that the ventral body wall defect resulting from Cd treatment in chick embryos is the result of changes in the somites perhaps following interruption of a signalling pathway originating in ectoderm.     

Ionic mechanisms underlying the regulation of cell proliferation,differentiation and death

Ion channels and transporters act as major components that regulate membrane excitability in neurons, muscles, and some secretory glands, but may also contribute to the regulation of proliferation, differentiation, and death in a greater variety of cells including non-excitable ones. The molecular basis of ionic mechanisms underlying the later regulation has been partly identified in the last several years and is a hot issue now. In this short review, some of the molecular mechanisms underlying these regulations and novel compounds acting on the mechanisms were introduced as exciting topics in this area. Several types of transient receptor potential (TRP), identified as Ca(2+)-permeable, non-selective cation channels, may play obligatory roles in functional complexes, which regulate multiple signal transduction pathways triggering proliferation, differentiation, or death of many cell types. In addition, the relation between Cl(-) pump activity and the induction of beta-amyloid protein toxicity for neuronal cell death in Alzheimer disease was described. Unique functions of H(+) channel and pump in osteoclasts in bone mineral homeostasis and remodeling were also discussed. Finally, topics about activation of specific types of Cl(-) channels and K(+) channels, which are responsible for the induction of apoptosis or proliferation in several types of cells, were introduced.     

Altered de novo sphingolipid biosynthesis is involved in the serum deprivation-induced cell death in LLC-PK1 cells

Fumonisin B1, a specific inhibitor of ceramide synthase, and ISPI (Myriocin), a serine palmitoyltransferase inhibitor, modulate the de novo sphingolipid biosynthesis pathway. This study was conducted to determine whether serum deprivation-induced cell death is regulated by de novo sphingolipid biosynthesis in pig kidney LLC-PK1 cells. Serum withdrawal from the culture medium produced cell death in LLC-PK1 cells. Fumonisin B1 at concentrations ranging from 5 M to 30 M delayed until 48 h this cell death resulting from the absence of fetal bovine serum (FBS) in cell culture. Pretreatment of cultured cells with fumonisin B1 in the presence of serum for 24 h increased by approximately 70% this cytoprotective activity of fumonisin B1 against serum deprivation-induced cell death. Serum deprivation increased sphingolipid biosynthesis threefold compared to 5% serum-enriched culture. Fumonisin B1 at 5-30 M lowered the content of total complex sphingolipids to levels of 50% and 77% of the content in serum-enriched culture, although the concentration of intracellular free sphinganine was elevated. ISP1 alone at greater than 1 nM concentration reduced total complex sphingolipid content to values in LLC-PK1 cells grown in the presence of 5% FBS. The results suggest that the de novo complex sphingolipid biosynthesis modulated by either fumonisin B1 or ISP1 may regulate serum deprivation-induced cell death in LLC-PK1 cells.     

Neuronal cell death in Alzheimer's disease and a neuroprotective factor, humanin

Brain atrophy caused by neuronal loss is a prominent pathological feature of Alzheimer's disease (AD). Amyloid beta (Abeta), the major component of senile plaques, is considered to play a central role in neuronal cell death. In addition to removal of the toxic Abeta, direct suppression of neuronal loss is an essential part of AD treatment; however, no such neuroprotective therapies have been developed. Excess amount of Abeta evokes multiple cytotoxic mechanisms, involving increase of the intracellular Ca(2+) level, oxidative stress, and receptor-mediated activation of cell-death cascades. Such diversity in cytotoxic mechanisms induced by Abeta clearly indicates a complex nature of the AD-related neuronal cell death. We have identified a 24-residue peptide, Humanin (HN), which suppresses in vitro neuronal cell death caused by all AD-related insults, including Abeta, so far tested. The anti-AD effect of HN has been further confirmed in vivo using mice with Abeta-induced amnesia. Altogether, such potent neuroprotective activity of HN against AD-relevant cytotoxicity both in vitro and in vivo suggests the potential clinical applications of HN in novel AD therapies aimed at controlling neuronal death.     

Calcium-dependent nitric oxide production is involved in the cytoprotective properties of n-acetylcysteine in glycochenodeoxycholic acid-induced cell death in hepatocytes

The intracellular oxidative stress has been involved in bile acid-induced cell death in hepatocytes. Nitric oxide (NO) exerts cytoprotective properties in glycochenodeoxycholic acid (GCDCA)-treated hepatocytes. The study evaluated the involvement of Ca²⁺ on the regulation of NO synthase (NOS)-3 expression during N-acetylcysteine (NAC) cytoprotection against GCDCA-induced cell death in hepatocytes. The regulation of Ca²⁺ pools (EGTA or BAPTA-AM) and NO (l-NAME or NO donor) production was assessed during NAC cytoprotection in GCDCA-treated HepG2 cells. The stimulation of Ca²⁺ entrance was induced by A23187 in HepG2. Cell death, Ca²⁺ mobilization, NOS-1, -2 and -3 expression, AP-1 activation, and NO production were evaluated. GCDCA reduced intracellular Ca²⁺ concentration and NOS-3 expression, and enhanced cell death in HepG2. NO donor prevented, and l-NAME enhanced, GCDCA-induced cell death. The reduction of Ca²⁺ entry by EGTA, but not its release from intracellular stores by BAPTA-AM, enhanced cell death in GCDCA-treated cells. The stimulation of Ca²⁺ entrance by A23187 reduced cell death and enhanced NOS-3 expression in GCDCA-treated HepG2 cells. The cytoprotective properties of NAC were related to the recovery of intracellular Ca²⁺ concentration, NOS-3 expression and NO production induced by GCDCA-treated HepG2 cells. The increase of NO production by Ca²⁺-dependent NOS-3 expression during NAC administration reduces cell death in GCDCA-treated hepatocytes.     

具有促C17.2神经干细胞增殖作用的多功能咔唑-利凡斯的明二聚体的发现(英文)

目的具有多靶点作用的化合物在治疗神经退行性疾病、心血管疾病、癌症等方面可能比传统"一药一靶"的治疗策略更有效。方法通过结合氨丙基咔唑和氨基甲酸酯两个药效团的方式设计合成了4个具有多功能化合物,并对化合物的促增殖、神经保护、抑制胆碱酯酶的活性进行检测。结果这些化合物可促进C17.2神经干细胞的增殖,对谷氨酸诱导的HT22细胞氧化毒性具有保护作用,具有较好的丁酰胆碱酯酶抑制活性和高血脑屏障透过性。结论这些化合物可能是一种新的多功能药物先导化合物,可以激活或保护内源性神经干细胞,从而重建受损的大脑。     

The role of the mitochondrion in smooth muscle cell fate choices of proliferation versus apoptosis during vascular and cardiovascular diseases

The role of the mitochondrion in cellular metabolism has, in recent years, become more pronounced beyond its traditional role of the energy supplier in the cell. Now the mitochondrion is known to have the duties of biosynthesis, and is involved in programmed cell death (apoptosis). There are pathophysiological incidences where the cell is stressed and must make a choice between survival (including proliferating) and apoptosis. It is unknown how the cell chooses between these two fates, but the mitochondrion may play a role in at least the series of steps leading to apoptosis or proliferation. In this paper it is proposed that the mitochondria may be a lynchpin through which this decision is made. It is suggested that the production of reactive oxygen species (ROS) originating from the mitochondrion may produce the signalling molecules which drive the cell down either a proliferative pathway or one of programmed cell death. These peroxidised molecules may alter the phosphatase/kinase activities in the cell, determine the cell fate and play a central role in the pathogenesis of several vascular pathologies. If so, the mitochondrion may be the key in producing the signalling molecules necessary for dictating cell fate choice.     

Plasminogen-stimulated airway smooth muscle cell proliferation is mediated by urokinase and annexin A2, involving plasmin-activated cell signalling

BACKGROUND AND PURPOSE

The conversion of plasminogen into plasmin by interstitial urokinase plasminogen activator (uPA) is potentially important in asthma pathophysiology. In this study, the effect of uPA-mediated plasminogen activation on airway smooth muscle (ASM) cell proliferation was investigated.

EXPERIMENTAL APPROACH

Human ASM cells were incubated with plasminogen (0.5–50 μg·mL⁻¹) or plasmin (0.5–50 mU·mL⁻¹) in the presence of pharmacological inhibitors, including UK122, an inhibitor of uPA. Proliferation was assessed by increases in cell number or MTT reduction after 48 h incubation with plasmin(ogen), and by earlier increases in [³H]-thymidine incorporation and cyclin D1 expression.

KEY RESULTS

Plasminogen (5 μg·mL⁻¹)-stimulated increases in cell proliferation were attenuated by UK122 (10 μM) or by transfection with uPA gene-specific siRNA. Exogenous plasmin (5 mU·mL⁻¹) also stimulated increases in cell proliferation. Inhibition of plasmin-stimulated ERK1/2 or PI3K/Akt signalling attenuated plasmin-stimulated increases in ASM proliferation. Furthermore, pharmacological inhibition of cell signalling mediated by the EGF receptor, a receptor trans-activated by plasmin, also reduced plasmin(ogen)-stimulated cell proliferation. Knock down of annexin A2, which has dual roles in both plasminogen activation and plasmin-signal transduction, also attenuated ASM cell proliferation following incubation with either plasminogen or plasmin.

CONCLUSIONS AND IMPLICATIONS

Plasminogen stimulates ASM cell proliferation in a manner mediated by uPA and involving multiple signalling pathways downstream of plasmin. Targeting mediators of plasminogen-evoked ASM responses, such as uPA or annexin A2, may be useful in the treatment of asthma.     

Group 1 metabotropic glutamate receptor 5 is involved in synaptically-induced Ca2+-spikes and cell death in cultured rat hippocampal neurons

Group 1 metabotropic glutamate receptors (mGluRs) can positively affect postsynaptic neuronal excitability and epileptogenesis. The objective of the present study was to determine whether group 1 mGluRs might be involved in synaptically-induced intracellular free Ca²⁺ concentration ([Ca²⁺]_i) spikes and neuronal cell death induced by 0.1 mM Mg²⁺ and 10 µM glycine in cultured rat hippocampal neurons from embryonic day 17 fetal Sprague–Dawley rats using imaging methods for Ca²⁺ and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays for cell survival. Reduction of extracellular Mg²⁺ concentration ([Mg²⁺]_o) to 0.1 mM induced repetitive [Ca²⁺]_i spikes within 30 sec at day 11.5. The mGluR5 antagonist 6-Methyl-2-(phenylethynyl) pyridine (MPEP) almost completely inhibited the [Ca²⁺]_i spikes, but the mGluR1 antagonist {"type":"entrez-nucleotide","attrs":{"text":"LY367385","term_id":"1257996803","term_text":"LY367385"}}LY367385 did not. The group 1 mGluRs agonist, 3,5-dihydroxyphenylglycine (DHPG), significantly increased the [Ca²⁺]_i spikes. The phospholipase C inhibitor U73122 significantly inhibited the [Ca²⁺]_i spikes in the absence or presence of DHPG. The IP₃ receptor antagonist 2-aminoethoxydiphenyl borate or the ryanodine receptor antagonist 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate also significantly inhibited the [Ca²⁺]_i spikes in the absence or presence of DHPG. The TRPC channel inhibitors {"type":"entrez-protein","attrs":{"text":"SKF96365","term_id":"1156357400","term_text":"SKF96365"}}SKF96365 and flufenamic acid significantly inhibited the [Ca²⁺]_i spikes in the absence or presence of DHPG. The mGluR5 antagonist MPEP significantly increased the neuronal cell survival, but mGluR1 antagonist {"type":"entrez-nucleotide","attrs":{"text":"LY367385","term_id":"1257996803","term_text":"LY367385"}}LY367385 did not. These results suggest a possibility that mGluR5 is involved in synaptically-induced [Ca²⁺]_i spikes and neuronal cell death in cultured rat hippocampal neurons by releasing Ca²⁺ from IP₃ and ryanodine-sensitive intracellular stores and activating TRPC channels.     

Mucosal T cell proliferation and apoptosis in inflammatory bowel disease

Both forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), represent prototypical conditions whose most salient features are the presence of chronic inflammation involving various parts of the intestinal tract and an increased risk of cancer, which is a complication directly related to the duration and activity of gut inflammation. Several factors have been implicated in the unrelenting mucosal inflammation of IBD, prominent among them being the presence of a persistently elevated number of activated T cells in the mucosa of CD and UC patients. These T cells display various defects of proliferation and apoptosis, and these abnormalities are credited with directly contributing to the pathogenesis of IBD and possibly the progression to colon cancer. This notion is supported by the observation that T cells are also prominently found infiltrating most tumors and are functionally impaired compared to T cells in the circulation. This establishes a parallel that may constitute a link between chronic intestinal inflammation and the development of malignancies in the inflamed intestine. This article will review some of the basic features of human intestinal mucosal T cells, examine the mechanisms underlying the processes of cell cycling and cell death, describe the defective proliferative and apoptotic function detected in CD and UC, and discuss the implications of modulating T cell apoptosis in IBD for therapeutic purposes and eventually decreasing the risk of cancer development.     

The calcium-sensing receptor (CaR) is involved in strontium ranelate-induced osteoblast proliferation

Strontium ranelate has several beneficial effects on bone and reduces the risk of vertebral and hip fractures in women with postmenopausal osteoporosis. We investigated whether Sr(2+) acts via a cell surface calcium-sensing receptor (CaR) in HEK293 cells stably transfected with the bovine CaR (HEK-CaR) and rat primary osteoblasts (POBs) expressing the CaR endogenously. Elevating Ca(o)(2+) or Sr(2+) concentration-dependently activated the CaR in HEK-CaR but not in non-transfected cells, but the potency of Sr(2+) varied depending on the biological response tested. Sr(2+) was less potent than Ca(o)(2+) in stimulating inositol phosphate accumulation and in increasing Ca(i)(2+), but was comparable to Ca(o)(2+) in stimulating ERK phosphorylation and a non-selective cation channel, suggesting that Ca(2+) and Sr(2+) have differential effects on specific cellular processes. With physiological concentrations of Ca(o)(2+), Sr(2+)-induced further CaR activation. Neither Sr(2+) nor Ca(o)(2+) affected the four parameters just described in non-transfected cells. In POB, Sr(2+) stimulated cellular proliferation. This effect was CaR-mediated, as transfecting the cells with a dominant negative bovine CaR significantly attenuated Ca(o)(2+)-stimulated POB proliferation. Finally, Sr(2+) significantly increased the mRNA levels of the immediate early genes, c-fos and egr-1, which are involved in POB proliferation, and this effect was attenuated by overexpressing the dominant negative CaR. In conclusion, Sr(2+) is a full CaR agonist in HEK-CaR and POB, and, therefore, the anabolic effect of Sr(2+) on bone in vivo could be mediated, in part, by the CaR.     

自噬参与缺血性心脏病的发生发展

细胞自噬广泛存在于真核生物生命过程中,是一种进化上高度保守的细胞内蛋白质再循环机制,它通过细胞内的溶酶体降解自身受损细胞器及异常大分子物质来维持细胞内稳态平衡。研究表明缺血性心脏病发病的不同阶段均可通过多种因素诱导自噬,但其具体作用的类型及机制仍旧存在很大争议。近年来,缺血性心脏病中自噬发生的具体分子学机制已成为国内外学者研究的热点,该文就自噬发生的分子学机制及其在缺血性心脏病的研究进展方面作一综述。     

Mitochondrial signaling pathway is also involved in bisphenol A induced germ cell apoptosis in testes

Bisphenol A (BPA) is a potential endocrine disruptor and testicular toxicant. An earlier study showed that BPA-induced germ cell apoptosis through the Fas/FasL apoptotic pathway. In the present study, we aimed to investigate whether the mitochondrial pathway is also involved in the process of BPA-mediated germ cell apoptosis in testes. Male mice were administered with BPA (160 or 480 mg/kg) by gavage daily from postnatal day 35 (PND35) to PND49. Germ cell apoptosis in testes was determined by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL). As expected, the number of TUNEL+ germ cells per tubule and the percentage of tubules with TUNEL+ germ cells were significantly increased in testes of mice treated with BPA during puberty. TUNEL+ germ cells were observed mainly in stages VII–VIII seminiferous tubules in testes. An increase in the level of Fas and FasL was observed in testes of mice exposed to BPA during puberty. In addition, pubertal BPA exposure evoked the activation of caspase-8 and caspase-3 in testes. Interestingly, pubertal BPA exposure also caused the translocation of cytochrome c from mitochondria into cytosol. In addition, pubertal BPA exposure upregulated the level of Bax and active caspase-9 in testes. Taken together, these results suggest that pubertal BPA exposure induces germ cell apoptosis in testes through not only the Fas/FasL signaling pathway but also the mitochondrial apoptotic pathway.     

Vorinostat in autophagic cell death: A critical insight into autophagy-mediated, -associated and -dependent cell death for cancer prevention

Histone deacetylases (HDACs) inhibit the acetylation of crucial autophagy genes, thereby deregulating autophagy and autophagic cell death (ACD) and facilitating cancer cell survival. Vorinostat, a broad-spectrum pan-HDAC inhibitor, inhibits the deacetylation of key autophagic markers and thus interferes with ACD. Vorinostat-regulated ACD can have an autophagy-mediated, -associated or -dependent mechanism depending on the involvement of apoptosis. Molecular insights revealed that hyperactivation of the PIK3C3/VPS34–BECN1 complex increases lysosomal disparity and enhances mitophagy. These changes are followed by reduced mitochondrial biogenesis and by secondary signals that enable superactivated, nonselective or bulk autophagy, leading to ACD. Although the evidence is limited, this review focuses on molecular insights into vorinostat-regulated ACD and describes critical concepts for clinical translation.