PINK1/Parkin-mediated mitophagy is involved in NaAsO2-induced apoptosis of human hepatic cells through activation of ERK signaling

Mitochondrial dysfunction has been demonstrated as one key event in arsenic-induced hepatic cell damage though the exact molecular target remains unknown. Here we examined NaAsO₂-induced mitochondrial damage in the L-02 cell led to mitochondrial depolarization and cytochrome c release, mitophagy, apoptosis in a dose response manner. Mitophagy was measured by analysis of PINK1, Parkin, LC3-II and p62 protein. Apoptosis was assessed by measuring Annexin V. Using the mitophagy inhibitor cyclosporine A (CsA) or ERK inhibitor (PD98059), the balance between mitophagy and apoptosis were further explored. When CsA was used prior to cell exposure to NaAsO₂, it was found that the levels of mitophagy were decreased as expected and apoptosis was increased in response. CsA alone had no effect on the apoptosis rate. When the ERK signaling inhibitor PD98059 was used, there was a similar result that mitophagy was reduced though in contrast with CsA the apoptosis rate was also decreased compared with NaAsO₂ alone. This result, along with the increased levels of ERK measured here in response to NaAsO₂, indicates that ERK activation is a second key molecular response to NaAsO₂ through the activation of both apoptosis and mitophagy. Thus the results with CsA indicate that the likely key biological event in NaAsO₂ toxicity is at the level of the mitochondria leading to cytochrome c release and apoptosis. Mitophagy is increased in response to a secondary effect of NaAsO₂ on ERK signaling that activates both mitophagy and apoptosis. The activation of mitophagy allows the cell to avoid some apoptosis. When ERK signaling is inhibited by PD98059 both the levels of apoptosis and mitophagy are decreased compared with the response produced by NaAsO₂ alone in comparison to the inhibition of mitophagy by CsA that reduced mitophagy but dramatically increased apoptosis in response.     

Silica nanoparticles induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway

The present study was to investigate effects of Silica nanoparticles (SiNPs) on nervous system and explore potential mechanisms in human neuroblastoma cells (SH-SY5Y). Cytotoxicity was detected by cell viability and Lactate dehydrogenase (LDH) release. Flow cytometry analysis was applied to assess mitochondrial membrane potential (MMP) loss, intracellular Ca²⁺ and apoptosis. To clarify the mechanism of SiNPs-induced apoptosis, intrinsic apoptosis-related proteins were detected. Our results showed that SiNPs caused cytotoxicity, cell membrane damage and Ca²⁺ increase in a dose-dependent manner in SH-SY5Y cells. Both the mitochondrial membrane potential (MMP) loss and potential mitochondria damage resulted in Cyt C release to the cytoplasm. The elevated Cyt C and Apaf1 further triggered intrinsic apoptosis via executive molecular caspase-9 and caspase-3. The present study confirmed that SiNPs induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway and provided a better understanding of the potential toxicity induced by SiNPs on human neurocyte.     

Somatic and germline mutations in the tumor suppressor gene PARK2 impair PINK1/Parkin-mediated mitophagy in lung cancer cells

PARK2,which encodes Parkin,is a disease-causing gene for both neurodegenerative disorders and cancer.Parkin can function as a neuroprotector that plays a crucial role in the regulation of mitophagy,and germline mutations in PARK2 are associated with Parkinson’s disease(PD).Intriguingly,recent studies suggest that Parkin can also function as a tumor suppressor and that somatic and germline mutations in PARK2 are associated with various human cancers,including lung cancer.However,it is presently unknown how the tumor suppressor activity of Parkin is affected by these mutations and whether it is associated with mitophagy.Herein,we show that wild-type(WT)Parkin can rapidly translocate onto mitochondria following mitochondrial damage and that Parkin promotes mitophagic clearance of mitochondria in lung cancer cells.However,lung cancer-linked mutations inhibit the mitochondrial translocation and ubiquitin-associated activity of Parkin.Among all lung cancer-linked mutants that we tested,A46T Parkin failed to translocate onto mitochondria and could not recruit downstream mitophagic regulators,including optineurin(OPTN)and TFEB,whereas N254S and R275W Parkin displayed slower mitochondrial translocation than WT Parkin.Moreover,we found that deferiprone(DFP),an iron chelator that can induce mitophagy,greatly increased the death of A46T Parkin-expressing lung cancer cells.Taken together,our results reveal a novel mitophagic mechanism in lung cancer,suggesting that lung cancer-linked mutations in PARK2 are associated with impaired mitophagy and identifying DFP as a novel therapeutic agent for PARK2-linked lung cancer and possibly other types of cancers driven by mitophagic dysregulation.     

Blocking Parkin/PINK1-mediated mitophagy sensitizes hepatocellular carcinoma cells to sanguinarine-induced mitochondrial apoptosis

Hepatocellular carcinoma (HCC) remains a major clinical challenge. Although mitophagy is implicated in hepatocarcinogenesis, novel therapeutic options targeting mitophagy for HCC treatment still await further studies. Here, we demonstrate that sanguinarine induces cell death in HCC cell line MHCC-97H through the mitochondrial apoptosis pathway. Sanguinarine triggers mitochondrial dysfunction and PTEN-induced putative kinase 1 (PINK1)/Parkin upregulation and recruitment to mitochondria. Elevated levels of p62 and LC3-II/I ratios suggest that sanguinarine is both an inducer of autophagy and a blocker of autolysosome formation, which is further confirmed by LC3-II conversion levels in presence of autophagy and mitophagy inhibitors, as well as an autophagy activator. In addition, blocking autophagy promotes sanguinarine-induced cell death, indicating mitophagy plays a cytoprotective role in sanguinarine-treated cells. Our findings suggest that blocking mitophagy may contribute to sanguinarine-induced mitochondrial apoptosis through the prevention of damaged mitochondrial clearance.     

Apoptosis induced by acrylamide in SH-SY5Y cells

Acrylamide (1–5 mM) dose-dependently decreased cell viability in human neuroblastoma cells (SH-SY5Y). The caspase-3 activity and cell population in sub-G₁ phase were elevated and peaked on exposure to 3 mM acrylamide, while both were less so at higher dose (4 and 5 mM). Z-VAD-fmk, a pan-caspase inhibitor, lowered the apparent cytotoxicity of acrylamide. U0126, a specific inhibitor of extracellular signal-regulated protein kinase (ERK) kinase, suppressed the elevation of caspase-3 activities as well as that of sub-G₁ population. Thus, although mechanisms other than caspase-dependent apoptosis may be involved, apoptotic process seems to take place in the genesis of toxicity of acrylamide in SH-SY5Y cells through ERK pathway and activation of caspase-3.     

Organophosphorus compound-induced apoptosis in SH-SY5Y human neuroblastoma cells

Organophosphorus (OP) compounds have been shown to be cytotoxic to SH-SY5Y human neuroblastoma cell cultures. The mechanisms involved in OP compound-induced cell death (apoptosis versus necrosis) were assessed morphologically by looking at nuclear fragmentation and budding using the fluorescent stain Hoechst 33342 (10 microgram/ml). Hoechst staining revealed significant paraoxon (1 mM), parathion (1 mM), phenyl saligenin phosphate (PSP, 10 and 100 microM), tri-ortho-tolyl phosphate (TOTP, 100 microM and 1 mM), and triphenyl phosphite (TPPi, 1 mM) induced time-dependent increases in traditional apoptosis (p < 0.05). In many cells, PSP and TOTP (1 mM) also induced nuclear condensation with little fragmentation or budding. Pretreatment with cyclosporin A (500 nM, 30 h) decreased apoptosis following 1 mM parathion and TOTP exposures. Apoptotic nuclear changes were verified by DNA gel electrophoresis. Activation of caspase-3, a cysteine aspartate protease, was also monitored. OP compounds induced significant time-dependent increases in caspase-3 activation following paraoxon (1 mM), parathion (100 microM, 1 mM), PSP (10 microM, 100 microM, 1 mM), TOTP (100 microM, 1 mM), and TPPi (1 mM) exposure (p < 0.05). Pretreatment with cyclosporin A (500 nM, 30 h) significantly decreased caspase-3 activation during extended incubations with paraoxon, parathion, and TPPi (p < 0.05). In addition, pretreatment with the caspase-3 inhibitor Ac-DEVD-CHO and the caspase-8 inhibitor Ac-IETD-CHO (25 microM, 8 h) significantly decreased caspase-3 activation following exposure to 1 mM PSP and parathion (p < 0.05). Pretreatment with the serine protease inhibitor phenylmethyl sulfonyl fluoride (PMSF; 1 mM, 8 h) also significantly decreased caspase activation following 1 mM PSP and TOTP exposures (p < 0.05). Alteration of OP compound-induced nuclear fragmentation or caspase-3 activation by pretreatment with cyclosporin A, Ac-IETD-CHO, or PMSF suggested that OP compound-induced cytotoxicity may be modulated through multiple sites, including mitochondrial permeability pores, receptor-mediated caspase pathways, or serine proteases.     

5-羟基-1-氢-吲唑对SH-SY5Y细胞的保护作用及其机制研究

目的研究5-羟基-1-氢-吲唑对1-甲基-4-苯基-吡啶离子(MPP~+)诱导凋亡的SH-SY5Y神经细胞的保护作用及其可能的作用机制。方法以MPP~+诱导SH-SY5Y细胞凋亡建立体外帕金森病细胞模型,以MTT法筛选药物有效保护浓度;以免疫化学染色以及Hoechst 33258核染研究药物的神经保护作用以及抗凋亡作用;以Western blot法检测与神经元凋亡密切相关的磷酸化tau蛋白及其上游激酶磷酸化糖原合成激酶(P-GSK-3β)和周期依赖性蛋白激酶5(cyclin dependent kinase,CDK5)的表达。结果 MPP+可引起GSK-3β的活化以及CDK5活性升高,诱导tau的异常磷酸化和神经细胞凋亡;而5-羟基-1-氢-吲唑可下调GSK-3β与CDK5的活性,降低磷酸化tau的水平和抑制MPP+导致的SH-SY5Y细胞的凋亡。结论 5-羟基-1-氢-吲唑可抑制MPP+引起的SH-SY5Y神经细胞凋亡,作用机制可能是通过同时抑制GSK-3β和CDK5两条信号传导通路,而降低tau蛋白的磷酸化水平,进一步发挥神经元保护作用。     

Acrylonitrile induced apoptosis via oxidative stress in neuroblastoma SH-SY5Y cell

Acrylonitrile (ACN) is a chemical that is widely used in the production of plastics, acrylic fibers, synthetic rubbers and resins. It has been reported that ACN can cause oxidative stress, a condition which is well recognized as an apoptotic initiator; however, information regarding ACN-induced apoptosis is limited. This present study investigated whether ACN induces apoptosis in human neuroblastoma SH-SY5Y cells, and whether its apoptotic induction involves oxidative stress. The results showed that ACN caused activation of caspase-3, a key enzyme involved in apoptosis, in a dose- and time-dependent manner. Detection of sub-G1 apoptotic cell death and apoptotic nuclear condensation revealed that ACN caused an increase in the number of apoptotic cells indicating ACN induces apoptosis in SH-SY5Y cells. ACN dose- and time-dependently increased the level of proapoptotic protein, Bax. Pretreatment with N-acetylcysteine (NAC), an antioxidant, attenuated caspase-3 activation by ACN, as evidenced by a reduction in proteolysis of PARP, a known caspase-3 substrate, as well as in the number of sub-G1 apoptotic cells. Moreover, induction of Bax by ACN was abolished by NAC. Taken together, the results indicate that ACN induces apoptosis in SH-SY5Y cells via a mechanism involving generation of oxidative stress-mediated Bax induction.     

Curcumin inhibits appoptosin-induced apoptosis via upregulating heme oxygenase-1 expression in SH-SY5Y cells

Aim:

Appoptosin (SLC25A38) is a pro-apoptotic protein, which is upregulated in Alzheimer''s disease (AD) brains and plays an important role in promoting the pathological progress of AD. The aim of this study was to investigate the effects of curcumin from the rhizome of Curcuma longa on appoptosin-induced apoptosis in SH-SY5Y cells.

Methods:

SH-SY5Y cells were pretreated with curcumin, then transfected with appoptosin or vector. The apoptotic cells were detected with Annexin V staining analysis by flow cytometry. The expression of cleaved caspase-3, appoptosin, heme oxygenase-1 (HO-1) was examined using Western blotting. Intracellular level of ROS was measured with DCFH-DA staining by flow cytometry analysis. Mitochondrial membrane potential (ΔΨm) was detected with JC-1 staining under a fluorescence microscope and quantified by fluorescence ratio detection.Overexpression of appoptosin in SH-SY5Y cells markedly increased cell apoptosis accompanied by reduced HO-1 expression, increased intracellular heme level, ROS overproduction and ΔΨm impairment. Treatment of SH-SY5Y cells with curcumin (2.5–20 μmol/L) for 24 h did not significantly affect their viability. However, pretreatment with curcumin (2.5–20 μmol/L) dose-dependently attenuated all above-mentioned pathological changes in appoptosin-transfected SH-SY5Y cells.

Results:

Overexpression of appoptosin in SH-SY5Y cells markedly increased cell apoptosis accompanied by reduced HO-1 expression, increased intracellular heme level, ROS overproduction and ΔΨm impairment. Treatment of SH-SY5Y cells with curcumin (2.5–20 μmol/L) for 24 h did not significantly affect their viability. However, pretreatment with curcumin (2.5–20 μmol/L) dose-dependently attenuated all above-mentioned pathological changes in appoptosin-transfected SH-SY5Y cells.

Conclusion:

Curcumin inhibits appoptosin-induced apoptosis in SH-SY5Y cells by upregulating the expression of HO-1, reducing the production of intracellular heme and ROS, and preventing the ΔΨm loss.     

类叶升麻苷对鱼藤酮致SH-SY5Y细胞凋亡的保护作用

目的探讨类叶升麻苷对鱼藤酮致多巴胺能神经元SH-SY5Y细胞凋亡的保护作用及其机制。方法采用MTT法检测细胞存活率,以荧光染料Hoechst33342染色分析细胞核的形态学变化,用流式细胞仪定量分析细胞凋亡峰,以2,′7′-二氢二氯荧光黄双乙酸钠(DCFH-DA)为标记探针检测细胞内活性氧的产生。结果①0.5μmol.L-1的鱼藤酮处理SH-SY5Y细胞48 h能引起细胞存活率的显著下降;诱导细胞发生凋亡,凋亡率达47.39%;大部分细胞胞体皱缩,突起缩短消失或断裂;染色质皱缩、浓缩、断裂及形成凋亡小体;细胞内活性氧水平上升。②预先用盐生肉苁蓉提取物类叶升麻苷(10,20或40 mg.L-1)处理细胞6 h,可提高细胞存活率;明显改善鱼藤酮引起的细胞形态学变化;流式细胞仪检测凋亡率分别降低到25.87%,23.97%,10.45%;以DCFH-DA为标记探针检测到20 mg.L-1类叶升麻苷可明显抑制鱼藤酮引起的细胞内活性氧产生。结论类叶升麻苷能抑制鱼藤酮诱导的多巴胺能神经元SH-SY5Y细胞凋亡,其神经细胞保护作用可能与降低细胞内活性氧水平有关。     

beta-Adrenoceptor blockers protect against staurosporine-induced apoptosis in SH-SY5Y neuroblastoma cells

The beta-adrenoceptor blockers exhibit a well-characterized anti-apoptotic property in the heart and kidney while less is known about the effect of this class of drugs on neuronal apoptosis. We studied the effects of three beta-adrenoceptor blockers propranolol (1-(isoproplyamino)-3-(naphthalene-1-yloxy)propan-2-ol), atenolol (2-[4-[2-hydroxy-3-(1-methylethylamino)propoxyl]phenyl]ehanamide), and ICI 118551 (1-[2,3-(dihydro-7-methyl-1H-iden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol), against staurosporine-induced apoptosis in SH-SY5Y human neuroblastoma cells. Staurosporine increased caspase 3-like activity, DNA fragmentation, PARP cleavage, and the number of TUNEL positive cells consistent with the induction of apoptosis. Propranolol and ICI 118551, but not atenolol, demonstrated a concentration-dependent inhibition of caspase 3-like activity. Propranolol and ICI 118551 directly inhibited the enzymatic activity of recombinant caspase 9 while atenolol did not; however, none of the beta-adrenoceptor blockers that were examined directly blocked caspases 2 or 3 activity. In isolated mitochondria, propranolol and ICI 118551 inhibited staurosporine-induced cytochrome c release while atenolol did not. We conclude that propranolol and ICI 118551 protect SH-SY5Y cells against staurosporine-induced apoptosis through a dual action on the mitochondria and on caspase 9 in a cell type and an apoptotic paradigm where the conventional inhibitors of mitochondrial permeability transition such as cyclosporin A and bongkrekic acid demonstrate no protection.     

Potential autophagy enhancers protect against fipronil-induced apoptosis in SH-SY5Y cells

Oxidative stress created by environmental toxicants activates several signaling pathways. Autophagy is one of the first lines of defense against oxidative stress damage. The autophagy pathway can be induced and up-regulated in response to intracellular reactive oxygen species (ROS). Recently, we reported that fipronil (FPN)-induced mitochondria-dependent apoptosis is mediated through ROS in human neuroblastoma SH-SY5Y cells. In this study, we explored the role of autophagy to prevent FPN neurotoxicity. We investigated the modulation of FPN-induced apoptosis according to autophagy regulation. FPN activated caspase-9 and caspase-3, and induced nuclear fragmentation and condensation, all of which indicate that FPN-induced cell death was due to apoptosis. In addition, we observed FPN-induced autophagic cell death by monitoring the expression of LC3-II and Beclin-1. Exposure to FPN in SH-SY5Y cells led to the production of ROS. Treatment with N-acetyl-cysteine (NAC) effectively blocked both apoptosis and autophagy. Interestingly, pretreatment with rapamycin, an autophagy inducer, significantly enhanced the viability of FPN-exposed cells; the enhancement of cell viability was partially due to alleviation of FPN-induced apoptosis via a decrease in levels of cleaved caspase-3. However, pretreatment with 3-methyladenine (3MA) a specific inhibitor for autophagy, remarkably strengthened FPN toxicity and further induced activation of caspase-3 in these cells. Our studies suggest that FPN-induced cytotoxicity is modified by autophagy regulation and that rapamycin is neuroprotective against FPN-induced apoptosis through enhancing autophagy.     

表没食子儿茶素没食子酸酯对H_2O_2诱导的SH-SY5Y神经细胞损伤的保护作用

目的观察表没食子儿茶素没食子酸酯(EGCG)对过氧化氢(H2O2)诱导的SH-SY5Y神经细胞凋亡的保护作用。方法采用体外细胞培养的方法,建立SH-SY5Y神经细胞H2O2损伤模型。通过观察细胞形态,测定细胞存活率(MTT法)、乳酸脱氢酶(LDH)活性,实时荧光定量(real-time)PCR检测细胞bax、bcl-2 mRNA表达的变化。结果同H2O2组比较,终浓度为50、100、150、200μmol.L-1的EGCG能减轻H2O2引起的SH-SY5Y神经细胞的损伤,且呈现剂量依赖趋势,能明显提高细胞的存活率,减少LDH的释放量,bax mR-NA表达下降,bcl-2 mRNA表达升高。结论 EGCG对H2O2诱导的SH-SYSY神经细胞损伤具有明显的保护作用。     

Enhanced oxidative stress and aberrant mitochondrial biogenesis in human neuroblastoma SH-SY5Y cells during methamphetamine induced apoptosis

Methamphetamine (METH) is an abused drug that may cause psychiatric and neurotoxic damage, including degeneration of monoaminergic terminals and apoptosis of non-monoaminergic cells in the brain. The cellular and molecular mechanisms underlying these METH-induced neurotoxic effects remain to be clarified. In this study, we performed a time course assessment to investigate the effects of METH on intracellular oxidative stress and mitochondrial alterations in a human dopaminergic neuroblastoma SH-SY5Y cell line. We characterized that METH induces a temporal sequence of several cellular events including, firstly, a decrease in mitochondrial membrane potential within 1 h of the METH treatment, secondly, an extensive decline in mitochondrial membrane potential and increase in the level of reactive oxygen species (ROS) after 8 h of the treatment, thirdly, an increase in mitochondrial mass after the drug treatment for 24 h, and finally, a decrease in mtDNA copy number and mitochondrial proteins per mitochondrion as well as the occurrence of apoptosis after 48 h of the treatment. Importantly, vitamin E attenuated the METH-induced increases in intracellular ROS level and mitochondrial mass, and prevented METH-induced cell death. Our observations suggest that enhanced oxidative stress and aberrant mitochondrial biogenesis may play critical roles in METH-induced neurotoxic effects.     

L-肌肽对鱼藤素诱导SH-SY5Y细胞神经毒性的保护作用

目的研究L-肌肽是否能通过抗氧化活性降低鱼藤素导致的神经毒性。方法 SH-SY5Y细胞在L-肌肽(1、10、20、40、60、80、100 mmol·L~(-1))中培养24 h,CCK-8法测定细胞存活率。30 mmol·L~(-1) L-肌肽、20μmol·L~(-1)鱼藤素、20μmol·L~(-1)鱼藤素与30 mmol·L~(-1) L-肌肽作用于SH-SY5Y细胞24 h,AO/EB法检测细胞形态和凋亡情况。8μmol·L~(-1)鱼藤素、8μmol·L~(-1)鱼藤素与3 mmol·L~(-1) L-肌肽、8μmol·L~(-1)鱼藤素与30 mmol·L~(-1) L-肌肽、20μmol·L~(-1)鱼藤素、20μmol·L~(-1)鱼藤素与3 mmol·L~(-1) L-肌肽、20μmol·L~(-1)鱼藤素与30 mmol·L~(-1) L-肌肽、50μmol·L~(-1)鱼藤素、50μmol·L~(-1)鱼藤素与3 mmol·L~(-1) L-肌肽、50μmol·L~(-1)鱼藤素与30 mmol·L~(-1) L-肌肽作用于SH-SY5Y细胞24 h,CCK-8法检测细胞的增殖情况;双染流式细胞术检测细胞凋亡率;DCFH-DA流式细胞术检测细胞活性氧(ROS)水平。结果 20μmol·L~(-1)鱼藤素与30 mmol·L~(-1) L-肌肽共作用于细胞后,细胞抑制率降低9.07%,早期凋亡的细胞数减少,早期凋亡率降低9.35%,总凋亡率降低10.7%,ROS水平低于20μmol·L~(-1)鱼藤素组,结果差异具有统计学意义(P<0.05)。结论 L-肌肽能有效降低鱼藤素诱导SH-SY5Y细胞的神经毒性,保护细胞,其机制可能与降低氧化应激水平相关。     

三苯基吡唑甲酮类化合物的合成及对6-OHDA 损伤的SH-SY5Y 细胞的保护作用

目的设计合成系列三苯基吡唑甲酮类化合物,测定其对6-羟基多巴胺(6-OHDA)损伤的SH-SY5Y细胞的保护作用,并初步探讨其构效关系。方法以2,5-二甲氧基苯乙酮为起始原料,经过Claisen-Schmidt反应和亲核加成合成目标化合物。采用CCK-8法考察了目标化合物对6-OHDA损伤的SH-SY5Y细胞的保护作用。结果与结论合成了8个未见文献报道的新化合物,其结构均经MS、~1H-NMR、~(13)C-NMR谱确证。体外活性筛选结果表明,化合物4c、4d、5c、5d具有较好的细胞保护作用,其EC_(50)值为1.1～9.6μmol·L~(-1),与阳性对照雷沙吉兰相当(EC_(50)=1.6μmol·L~(-1))。     

Reactive oxygen species mediate p53 activation and apoptosis induced by sodium nitroprusside in SH-SY5Y cells

Sodium nitroprusside (SNP) is a water-soluble iron nitrosyl complex clinically used as a powerful vasodilator for treatment of hypertension; and, in basic research, it has been used to mainly investigate the cytotoxic effects of nitrosative stress. Although NO is considered a pharmacologically active molecule, not all of the biological effects of SNP are dependent on its NO moiety. To elucidate the molecular executioner(s) responsible for SNP cytotoxicity, this study determines the involvement of oxidative stress in p53 activation and apoptotic induction elicited by SNP in SH-SY5Y neuroblastoma cells. We demonstrate that proapoptotic activity of SNP is independent of NO production, because SNP and its 2-day light-exhausted compound SNP(ex) trigger apoptosis to the same extent. We provide evidence for the occurrence of oxidative stress and oxidative damage during both SNP and SNP(ex) exposure and demonstrate that iron-derived reactive oxygen species (ROS) are the genuine mediators of their cytotoxicity. We show that p53 is equally activated upon both SNP and SNP(ex) treatments. Moreover, as demonstrated by small interfering RNA experiments, we indicate its primary role in the induction of apoptosis, suggesting the ineffectiveness of NO in its engagement. The attenuation of p53 levels, obtained by oxy-radical scavengers, is consistent with the recovery of cell viability and ROS decrease, demonstrate that SNP-mediated p53 activation is an event triggered by ROS and/or ROS-mediated damages. Together, our results suggest that investigations of the physiopathological effects of SNP should consider the role of ROS, other than NO, particularly in some conditions such as apoptotic induction and p53 activation.     

Tranexamic acid protects against rotenone-induced apoptosis in human neuroblastoma SH-SY5Y cells

Rotenone is a pesticide that has been shown to induce the pathological symptoms of Parkinson's disease (PD) in animal models. In this study, we investigated the protective effects of tranexamic acid (TA) on rotenone-induced apoptosis in human dopaminergic SH-SY5Y cells. TA blocked the rotenone-induced phosphorylation of JNK and P38, the downregulation of BCL2 and the upregulation of BAX. Furthermore, TA not only decreased the rotenone-induced cleavage of caspase 9, PARP, and caspase 3, but also increased caspase 3 enzymatic activity. Our findings indicate that TA is able to protect neuronal cells against apoptosis and suggest that TA might potentially serve as an agent for prevention or therapy of PD.