Acrylamide-induced astrogliotic and apoptotic responses in human astrocytoma cells

This study was to clarify whether acrylamide (ACR) will induce apoptosis and astrogliosis in an astrocytic cell line in vitro. Different time- and dose-dependent cytotoxic studies were conducted upon neuronal (SH-SY5Y) and glial cell lines (U-1240 MG) under exposure to ACR up to 72 h. We showed that SH-SY5Y cells were more sensitive in cytotoxic assays than U-1240 MG cells, and significantly decreased cell viability was observed at concentrations higher than 1 mM with increased lactate dehydrogenase leakage observed only at 5 and 10 mM in U-1240 MG cells. The ACR-induced apoptotic responses and phosphorylation of p53 protein at Ser15 for U-1240 MG cells were identified at 48 h. The increase of glial fibrillary acidic protein (GFAP) as a chemical-induced astrogliotic response was found to be associated with different ACR concentrations and exposure times, particularly at ≧48 h of ≧2 mM. In addition, immunocytochemical staining at 36 h of 5 and 10 mM treatments had significantly higher density of GFAP than the control. Thus, ACR-induced effects can be seen in neuronal and astrocytic cells. These results suggest that ACR exposure may lead to apoptotic and astrogliotic effects in human astrocytoma cells in vitro in a time- and dose-dependent manner.     

Acrylamide-induced apoptosis in rat primary astrocytes and human astrocytoma cell lines

This study aimed to evaluate the acrylamide (ACR)-induced apoptotic effects on rat primary astrocytes and three human astrocytoma-derived cell lines (U-1240 MG, U-87 MG, and U-251 MG). As determined through the MTT assay, treatment with 1 and 2 mM ACR for 24–72 h resulted in decreased cell viability in all cells. Decreases in cell viability could be blocked in all cells with the exception of U-251 MG cells by Z-DEVD FMK. ACR-induced dose-dependent apoptotic effects were also demonstrated by increases in the sub-G₁ phase cell population in all cells. The decreased expressions of pro-caspase 3, 8, and 9 and the interruption of the mitochondrial membrane potential were observed in all cells. Exposure to 2 mM ACR for 48 h resulted in increased Bax/Bcl-2 ratios in primary astrocytes and U-87 MG cells, whereas the overexpression of Bcl-2 was observed in U-1240 MG and U-251 MG cells. The ACR-induced increases in the levels of p53 and pp53 in primary astrocytes could be attenuated by caffeine. These results suggest the existence of a common apoptotic pathway among all cell types and that U-87 MG cells may be a suitable substitute in vitro model for primary astrocytes in future studies on ACR-induced neurotoxicity.     

Disruption of mitochondria during tocotrienol-induced apoptosis in MDA-MB-231 human breast cancer cells

Tocotrienols, which are Vitamin E isoforms, are known to inhibit the growth of human breast cancer cells due partly to apoptosis. However, the characterization of tocotrienol-induced apoptosis is incomplete, particularly what happens during the initiation phase that precedes execution of the cells. The objective of this study was to clarify the apoptotic effects of tocotrienols, with especial emphasis in determining if the mitochondria-mediated death pathway is activated when human breast cancer cells are incubated with a specific tocotrienol isomer. During incubation with gamma-tocotrienol, MDA-MB-231 human breast cancer cells showed membrane blebbing, and apoptotic bodies were present. Upon 4',6-diamidino-2-phenylindole staining of the cells, chromatin condensation and fragmentation were observed. Additionally, the annexin V-binding assay detected the translocation of membrane phospholipid during earlier analysis of the cells. Taken together, these results further establish that gamma-tocotrienol can induce apoptosis in human breast cancer cells. To help elucidate how gamma-tocotrienol induced the apoptosis, some important parameters related to the mitochondria-mediated death pathway were examined next. In gamma-tocotrienol-treated cells, the mitochondria were disrupted. Collapse of the mitochondrial membrane potential was detected, and cytochrome c was released later from mitochondria. However, expression of Bax and Bcl-2 (mRNA and protein) did not change. Furthermore, poly-(ADP-ribose)-polymerase cleavage was not detected, suggesting that caspases were not involved in the gamma-tocotrienol-induced apoptosis. These results imply that cytochrome c is not the critical protein released from mitochondria that triggers gamma-tocotrienol-induced apoptosis in MDA-MB-231 cells.     

Radon-induced reduced apoptosis in human bronchial epithelial cells with knockdown of mitochondria DNA

Radon and radon progeny inhalation exposure are recognized to induce lung cancer. To explore the role of mitochondria in radon-induced carcinogenesis in humans, an in vitro partially depleted mitochondrial DNA (mtDNA) cell line (ρ-) was generated by treatment of human bronchial epithelial (HBE) cells (ρ+) with ethidium bromide (EB). The characterization of ρ- cells indicated the presence of dysfunctional mitochondria and might thus serve a reliable model to investigate the role of mitochondria. In a gas inhalation chamber, ρ- and ρ+ cells were exposed to radon gas produced by a radium source. Results showed that apoptosis was significantly increased both in ρ- and ρ+ cells irradiated by radon. Moreover, apoptosis in ρ- cells showed a lower level than in ρ+ cells. Radon was further found to depress mitochondrial membrane potential (MMP) of HBE cells with knockdown mtDNA. Production of reactive oxygen species (ROS) was markedly elevated both in ρ- and ρ+ cells exposed to radon. The distribution of phases of cell cycle was different in ρ- compared to ρ+ cells. Radon irradiation induced a rise in G2/M and decrease in S phase in ρ+ cells. In ρ- cells, G1, G2/M, and S populations remained similar to cells exposed to radon. In conclusion, radon-induced changes in ROS generation, MMP and cell cycle are all attributed to reduction of apoptosis, which may trigger and promote cell transformation, leading to carcinogenesis. Our study indicates that the use of the ρ- knockdown mtDNA HBE cells may serve as a reliable model to study the role played by mitochondria in carcinogenic diseases.     

Berberine induces apoptosis through a mitochondria/caspases pathway in human hepatoma cells

Berberine, a main component of Coptidis Rhizoma, is a plant alkaloid with a long history of medicinal use in Chinese medicine. Berberine has indicated significant antimicrobial activity against a variety of organisms including bacteria, viruses, fungi. The mechanism by which berberine initiates apoptosis remains poorly understood. In the present study, we demonstrated that berberine exhibited significant cytotoxicity in hepatoma HepG2 cells but is ineffective in Chang liver cells. Herein we investigated cytotoxicity mechanism of berberine in HepG2 cells. The results showed that HepG2 cells underwent internucleosomal DNA fragmentation after 24-h treatment with berberine (50 μM). Moreover, berberine induced the activation of caspase-8 and −3, and caused the cleavage of poly ADP-ribose polymerase (PARP) and the cytochrome c release, whereas the expression of Bid and anti-apoptosis factor Bcl-XL were decreased markedly. The loss of mitochondrial membrane potential (Δ ψm) at 24 h and activation of Fas at 12 h were also seen in the berberine-treated HepG2 cells. These findings supported the fact that the inhibitors of caspases, DEVD-FMK, IETD-FMK and VAD-FMK, prevented apoptosis and restored the expression of Bcl-XL, Bcl-2 and Bid. These results indicated that the potential of anti-hepatoma activity of berberine may be mediated through a caspases-mitochondria-dependent pathway.     

The role of mitochondria in bee venom-induced apoptosis in human breast cancer MCF7 cells

Our previous studies have shown that bee venom (BV) can induce apoptosis in human cervical cancer Ca Ski cells, but it can also affect human breast cancer cells, though its molecular mechanisms are not precisely known. In this study, the molecular mechanisms of apoptosis induced by BV in human breast cancer MCF7 cells were investigated. BV induced morphological changes (examined by phase-contrast microscopy) and inhibited the proliferation (examined by MTT assay) of MCF7 cells; both effects occurred in a dose- and time-dependent manner. Flow cytometric analysis demonstrated that BV induced the production of reactive oxygen species (ROS) and dysfunction of the mitochondrial membrane potential (Azm), and led to cytochrome c release, an increase in the levels of caspase-9 and Poly (ADP-ribose) polymerase (PARP) and then apoptosis. It also showed that BV induced S-phase arrest in MCF7 cells which may occur through the promotion of p53, p21, p27 and the exhibition of Cdk2. Western blotting demonstrated that BV reduced Bcl-2 and increased Bax protein levels which may have caused the changes of delta psi m. BV treatment led to ROS production up to but after treatment led to a decrease in the levels of ROS, which may be associated with the observations of BVaffecting glutathion S-transferase (GST), Zn-superoxide dismutase (Zn-SOD), Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase. The Comet assay also showed that BV induced DNA damage while DAPI staining also confirmed that BV induced apoptosis in examined MCF7 cells. Our results also showed that BV increased the levels of AIF and EndoG in MCF7 cells. In conclusion, our data demonstrated that BV induced apoptosis via a mitochondria-dependent pathway based on the changes of delta psi m, AIF and EndoG release in MCF7 cells.     

Paraquat-induced apoptosis in human neuroblastoma SH-SY5Y cells: involvement of p53 and mitochondria

The herbicide paraquat is a suspected etiologic factor in the development of Parkinson's disease (PD). Paraquat was therefore used to reproduce Parkinsonian syndromes in lab animals, in which it produces dopaminergic pathogenesis. However, the factors or mechanisms by which paraquat kills dopaminergic neurons are not fully understood. Based on reported evidence that paraquat increases p53 protein levels and inhibits mitochondrial function, it was hypothesized that paraquat induces cell death in dopaminergic neurons through a mechanism in which p53 and mitochondrial apoptotic pathway are linked. To explore this possibility, dopaminergic SY5Y cells were treated with paraquat for 48 h and p53 responses were investigated, as well as biomarkers of the mitochondrial intrinsic pathway of apoptosis. Paraquat significantly increased protein levels of p53 and one of its target genes, Bax. By 24 h, paraquat decreased mitochondrial complex I activity and mitochondrial transmembrane potential and induced the release of cytochrome c from mitochondria. In addition, paraquat increased the activities of caspases 9 and 3. Finally, nuclear condensation and DNA fragmentation occurred 48 h after treatment. The decrease of mitochondrial functions, the release of cytochrome c, the increase of caspase 9 and 3 activities, and DNA damage that were produced by paraquat were inhibited by a specific p53 inhibitor, pifithrin-alpha. These findings support the conclusion that paraquat produced apoptosis in SY5Y cells through the mitochondrial intrinsic pathway associated with p53.     

DC-81-Indole conjugate agent induces mitochondria mediated apoptosis in human melanoma A375 cells

DC-81, an antitumor antibiotic produced by the Streptomyces species, belongs to pyrrolo[2,1-c] [1,4]benzodiazepine (PBD), which are potent inhibitors of nucleic acid synthesis. We previously reported an efficient synthesis of PBD hybrids linked with indole carboxylates. This is the first demonstration on the mechanism of the anticancer effect of PBD hybrid (IN6CPBD) agent on human melanoma A375 cells. IN6CPBD-treated cells exhibited higher cytotoxicity than DC-81 and displayed several features of apoptosis, including an increase in the sub-G1 population, a significantly increased annexin V binding, a degradation of caspase-3, and poly (ADP-ribose) polymerase (PARP) cleavage. Because degradative changes associated with apoptosis are often preceded by the disruption of mitochondrial function, the assessment of mitochondrial function in IN6CPBD-treated cells is worthy of investigation. Our data revealed that treatment of A375 cells with IN6CPBD resulted in the loss of mitochondrial membrane potential (DeltaPsimt), a decrease in intracellular pH (pHi), a reduction of ATP synthesis, increased reactive oxygen species (ROS) generation, and cytochrome c release. Collectively, our studies indicate that IN6CPBD induces apoptosis in A375 cells through a mitochondrial dysfunction pathway, leading to caspase-3 substrate PARP cleavage and subsequent apoptotic cell death.     

Thrombin-promoted release of UDP-glucose from human astrocytoma cells

As an increasing number of non-cardiac drugs have been reported to cause QT interval prolongation and torsades de pointes (TdP), we extensively studied the utility of atrioventricular (AV) block animals as a model to predict their torsadogenic action in human. The present review highlights such in vivo proarrhythmia models. In the case of the canine model, test substances were administered p.o. at conscious state >4 weeks after the induction of AV block, with subsequent Holter ECG monitoring to evaluate drug effects. Control AV block dogs (no pharmacological treatment) survive for several years without TdP attack. For pharmacologically treated dogs, drugs were identified as high, low or no risk. High-risk drugs induced TdP at 1-3 times the therapeutic dose. Low-risk drugs did not induce TdP at this dose range, but induced it at higher doses. No-risk drugs never induced TdP at any dose tested. Electrophysiological, anatomical histological and biochemical adaptations against persistent bradycardia-induced chronic heart failure were observed in AV block dogs. Recently, we have developed another highly sensitive proarrhythmia model using a chronic AV block cynomolgus monkey, which possesses essentially the same pathophysiological adaptations and drug responses as those demonstrated in the canine model. As a common remodelling process leading to a diminished repolarization reserve may present in patients who experience drug-induced TdP and in the AV block animals, the in vivo proarrhythmia models described in this review may be useful for predicting the risk of pharmacologically induced TdP in humans.     

H1-histamine receptors on human astrocytoma cells

The H1-histamine receptor antagonist [3H]mepyramine bound with high affinity (Kd = 3-5 nM) to membranes derived from 1321N1 human astrocytoma cells. The H1-receptor antagonists triprolidine and diphenhydramine inhibited [3H]mepyramine binding with Kj values of 1-5 nM, whereas the Kj of the H2-histamine receptor antagonist cimetidine was greater than 100 microM. Histamine also inhibited [3H]mepyramine binding to 1321N1 cell membranes, and the histamine inhibition curve was shifted to the right and steepened in the presence of 1 microM guanosine 5'-O-(3-thiotriphosphate). Treatment of 1321N1 cells with pertussis toxin had no effect on the capacity of histamine to inhibit [3H]mepyramine binding either in the absence or presence of guanosine 5'-O-(3-thiotriphosphate). Therefore, agonist-occupied histamine receptors in these cells apparently interact with a guanine nucleotide regulatory protein that is not the inhibitory guanine nucleotide regulatory protein of adenylate cyclase. Although adenylate cyclase activity was not affected by histamine in a cell-free preparation, incubation of 1321N1 cells with histamine resulted in an attenuation of cyclic AMP accumulation. Analysis of cyclic AMP degradation in the presence of histamine indicated that the effects of histamine on cyclic AMP accumulation are mediated through activation of phosphodiesterase. This idea was supported by the fact that the phosphodiesterase inhibitor 1-isobutyl 3-methylxanthine blocked attenuation of cyclic AMP accumulation by histamine in a noncompetitive manner. Histamine also markedly increased phosphoinositide breakdown and 45Ca2+ efflux in 1321N1 cells. These histamine-induced effects apparently are mediated through H1-receptors, since triprolidine, but not cimetidine, potently inhibited histamine action. As for histamine interaction with its receptor, pertussis toxin had no effect on histamine-induced phosphoinositide breakdown, 45Ca2+ efflux, or attenuation of cyclic AMP accumulation. Taken together, these data indicate that 1321N1 human astrocytoma cells are a useful model system for the study of H1-histamine receptors and the biochemical responses mediated through these receptors.     

细胞凋亡基因在人脑星形细胞瘤中的表达和意义

目的 探讨bcl-2、Bax在星形细胞瘤发生、发展中的作用。方法 本实验运用免疫组化技术SP法检测bcl-2、Bax在60例星形细胞瘤组织中的表达情况,并分析它们与星形细胞瘤的病理分级的关系。结果 bcl-2、Bax在星形细胞瘤中的表达率分别为58.3％(35/60)、66.7％(40/60),病理分级无统计学意义(P>0.05)。结论 bcl-2、Bax在星形细胞瘤的发生、发展起着次要作用。     

Acrylamide-induced visual impairment in primates

Subchronic exposure to acrylamide monomer caused deterioration in the visual capacities of macaque monkeys. Thresholds for visual acuity and flicker-fusion were increased and the latency of patternevoked potentials prolonged, well before the monkeys showed overt signs of toxicity. The termination of dosing resulted in rapid recovery of flicker-fusion thresholds, gradual recovery in evoked potential latency, and only partial recovery of visual acuity.     

Gentamicin-induced apoptosis in LLC-PK1 cells: involvement of lysosomes and mitochondria

Gentamicin accumulates in lysosomes and induces apoptosis in kidney proximal tubules and renal cell lines. Using LLC-PK1 cells, we have examined the concentration- and time-dependency of the effects exerted by gentamicin (1-3 mM; 0-3 days) on (i) lysosomal stability; (ii) activation of mitochondrial pathway; (iii) occurrence of apoptosis (concentrations larger than 3 mM caused extensive necrosis as assessed by the measurement of lactate dehydrogenase release). Within 2 h, gentamicin induced a partial relocalization [from lysosomes to cytosol] of the weak organic base acridine orange. We thereafter observed (a) a loss of mitochondrial membrane potential (as from 10 h, based on spectrophotometric and confocal microscopy using JC1 probe) and (b) the release of cytochrome c from granules to cytosol, and the activation of caspase-9 (as from 12 h; evidenced by Western blot analysis). Increase in caspase-3 activity (assayed with Ac-DEVD-AFC in the presence of z-VAD-fmk]) and appearance of fragmented nuclei (DAPI staining) was then detected as from 16 to 24 h together with nuclear fragmentation. Gentamicin produces a fast (within 4 h) release of calcein from negatively-charged liposomes at pH 5.4, which was slowed down by raising the pH to 7.4, or when phosphatidylinositol was replaced by cardiolipin (to mimic the inner mitochondrial membrane). The present data provide temporal evidence that gentamicin causes apoptosis in LLC-PK1 with successive alteration of the permeability of lysosomes, triggering of the mitochondrial pathway, and activation of caspase-3.     

Antiviral activity of ganciclovir and artesunate towards human cytomegalovirus in astrocytoma cells

Antimalarial drug artesunate inhibits cytomegalovirus (HCMV) replication in human fibroblasts. Astrocytes, the major cell type of the brain, support cytomegalovirus (HCMV) replication. The aim of the study was to assess the antiviral activity of artesunate in astrocytoma cell line U373MG in comparison with ganciclovir. The antiviral concentration inhibiting by 50% (IC(50)) the synthesis of viral DNA was measured by real-time PCR in parallel in U373MG and MRC-5 cells. Reference HCMV strains susceptible and resistant to ganciclovir, and clinical isolates were tested. Ganciclovir and artesunate had similar activity in U373MG cells and MRC-5 fibroblasts. The artesunate IC(50)s in U373MG cells (1.5-2.25 μM) were at least 36-fold lower than the 50% cytotoxicity concentrations. Then, the anti-HCMV activity of artesunate was demonstrated in a cancer cell line.     

DSF-Cu通过影响线粒体功能和细胞骨架诱导鼻咽癌CNE-2Z细胞凋亡

目的探测双硫仑(disulfiram,DSF)螯合氯化铜(DSF-Cu)通过影响线粒体功能和细胞骨架诱导人低分化鼻咽癌CNE-2Z细胞凋亡。方法采用流式细胞术检测细胞周期、凋亡率、活性氧(reactive oxygen species,ROS)的生成以及线粒体膜电位(mitochondrial membrane potential,MMP)的改变。AFM探测细胞表面形貌和超微结构、细胞高度、宽度及粗糙度的变化。激光扫描共聚焦显微镜(laser scanning confocal microscope,LSCM)观察细胞骨架F-actin的分布和重组。结果细胞周期检测显示DSF-Cu将CNE-2Z细胞周期阻滞于G2/M期。Annexin-V/PI检测细胞凋亡显示随药物浓度增加,与对照组相比,实验组早凋率和晚凋率、坏死率细胞均明显增加。进一步检测凋亡相关信号发现DSF-Cu可促进CNE-2Z细胞内活性氧水平的增加及诱导MMP下降。AFM成像表明,与对照组相比,随着药物浓度增大,细胞逐渐变小,胞质浓缩,高度增加,膜表面粗糙度降低,变得平整光滑;细胞伪足由对照组的丰富密集,逐渐变短、萎缩,甚至完全破坏。LSCM进一步观察发现DSF-Cu引起F-actin荧光强度减弱,结构重排,严重影响微丝的功能。结论 DSF-Cu可诱导CNE-2Z细胞依赖线粒体的凋亡途径,利用AFM在单细胞水平上分析DSF-Cu对细胞膜的毒性作用,为鼻咽癌的治疗提供新的思路。     

Cadmium-induced apoptosis in human normal liver L-02 cells by acting on mitochondria and regulating Ca(2+) signals

Cadmium is a well-known toxic compound for the liver. It has been demonstrated to induce hepatotoxicity partly via apoptosis, but no uniform mechanism of apoptosis has so far been proposed. This study was first to determine whether cadmium-induced apoptosis in L-02 cells, second to observe the mechanism of cadmium-induced apoptosis. Studies of morphology, DNA fragmentation and apoptotic rate demonstrated that 60μM cadmium induced apoptosis with strong effects on cell viability. A concomitant time-dependent decrease of Bcl-2 and mitochondrial transmembrane potential (ΔΨ(m)) was observed. Subsequently, increase of caspase-3 activity and release of mitochondrial AIF were detected. However, cell pretreatment with a broad-specificity caspase inhibitor (Z-Asp) did not abolish apoptosis. These data demonstrated that the apoptotic events involved a mitochondria-mediated apoptotic pathway but not necessarily caspase-dependent signaling. On the other hand, intracellular free Ca(2+) concentration ([Ca(2+)](i)) of cadmium-exposed cells had significant increases and the Bapta-AM, a well-known calcium chelator, pretreatment partially blocked cadmium-induced apoptosis, indicating that the elevation of [Ca(2+)](i) may play an important role in the apoptosis. Together, these results support the notion that cadmium-induced hepatotoxicity is comparable to effects in L-02 by inducing apoptotic pathways on the basis of acting on mitochondria and regulating Ca(2+) signals.     

Mastoparan-induced phosphatidylcholine hydrolysis by phospholipase D activation in human astrocytoma cells.

1. The effect of mastoparan on phosphatidylcholine hydrolysis was examined in 1321N1 human astrocytoma cells. Mastoparan (3-30 microM) caused an accumulation of diacylglycerol (DG) and phosphatidic acd (PA) accompanied by choline release in a concentration- and time-dependent manner. 2. In the presence of 2% n-butanol, mastoparan (3-100 microM) induced phosphatidylbutanol (PBut) accumulation in a concentration- and time-dependent manner, suggesting that mastoparan activates phospholipase D (PLD). Propranolol (30-300 microM), a phosphatidate phosphohydrolase inhibitor, inhibited DG accumulation induced by mastoparan, supporting this idea. 3. Depletion of extracellular free calcium ion did not alter the effect of mastoparan on PLD activity. 4. A protein kinase C (PKC) inhibitor, calphostin C (1 microM), did not inhibit mastoparan-induce PLD activation but the ability of mastoparan to stimulate phospholipase D activity was decreased in the PKC down regulated cells. 5. PLD activity stimulated by mastoparan was not prevented by pretreatment of the cells with pertussis toxin (PT) or C3 ADP-ribosyltransferase. Furthermore, guanine nucleotides did not affect PLD activity stimulation by mastoparan in membrane preparations. 6. Mastoparan stimulated PLD in several cell lines such as RBL-2H3, RBL-1, HL-60, P388, endothelial cells, as well as 1321N1 human astrocytoma cells. 7. These results suggest that mastoparan induces phosphatidylcholine (PC) hydrolysis by activation of PLD, not by activation of phosphatidylcholine-specific phospholipase C (PC-PLC); mastoparan-induced PLD activation is not mediated by G proteins.     

Caspase cascade regulated mitochondria mediated apoptosis in monocrotophos exposed PC12 cells

Monocrotophos (MCP) is a commonly used organophosphorus (OP) pesticide. We studied apoptotic changes in PC12 cells exposed to MCP. A significant induction in reactive oxygen species (ROS), lipid peroxide (LPO), and the ratio of glutathione disulfide (GSSG)/reduced glutathione (GSH) was observed in cells exposed to selected doses of MCP. Following the exposure of PC12 cells to MCP, the levels of protein and mRNA expressions of Caspase-3, Caspase-9, Bax, p53, P(21), Puma, and cytochrome-c were significantly upregulated, whereas the levels of Bcl(2), Bcl(w), and Mcl1 were downregulated. TUNEL assay, DNA laddering, and micronuclei induction show that long-term exposure of PC12 cells to MCP at higher concentration (10(-5) M) decreases the number of apoptotic events due to an increase in the number of necrotic cells. MCP-induced translocation of Bax and cytochrome-c proteins between the cytoplasm and mitochondria confirmed the role of p53 and Puma in mitochondrial membrane permeability. Mitochondria mediated apoptosis induction was confirmed by the increased activity of caspase cascade. We believe that this is the first report showing MCP-induced apoptosis in PC12 cells, which is mitochondria mediated and regulated through the caspase cascade. Our data demonstrates that MCP induced the apoptotic cell death in neuronal cells and identifies the possible cellular and molecular mechanisms of organophosphate pesticide-induced apoptosis in neuronal cells.     

脑星形细胞瘤中HPA的表达及其对肿瘤细胞侵袭力的影响

目的：观察乙酰肝素酶（ HPA）在人脑星形细胞瘤组织的表达及对肿瘤细胞侵袭力的影响。方法采用免疫组化ElivisionTMplus两步法和Real time-PCR法检测75例星形细胞瘤组织和40例正常脑组织中HPA蛋白和mRNA表达情况。通过siRNA干扰技术沉默星形细胞瘤U87细胞中HPA表达,采用Real time PCR、Western blot、Tr-answell小室实验检测肿瘤细胞HPA、血管内皮生长因子（ VEGF ）、基质金属蛋白酶-9（ MMP-9）表达及细胞侵袭力变化。结果正常脑组织未见HPA蛋白表达,星形细胞瘤组织中HPA阳性表达率为78侣．67％（59／75）,星形细胞瘤组织HPA阳性表达率显著高于正常脑组织,且其mRNA表达水平也显著高于正常脑组织,差异有统计学意义（ P ＜0．05）。星形细胞瘤Ⅱ～Ⅳ级组,HPA阳性表达率逐渐增加,差异有统计学意义（ P ＜0．05）;且有转移组HPA阳性表达率显著高于无转移组（ P ＜0．05）。 siRNA能够有效抑制星形细胞瘤U87细胞中HPA表达,并下调VEGF、MMP-9表达,同时穿膜细胞数显著减少,差异有统计学意义（ P ＜0．05）。结论 HPA在星形细胞瘤组织异常高表达,随着肿瘤恶性程度增高而逐渐升高。 siRNA沉默HPA后细胞侵袭力显著降低,HPA有可能成为治疗星形细胞瘤的潜在靶点。