High SLC20A1 Expression Indicates Poor Prognosis in Prostate Cancer.

BACKGROUND/AIM: High expression of solute carrier family 20 member 1 (SLC20A1) indicates poor clinical outcomes for patients with breast cancer subtypes treated with endocrine therapy and radiotherapy. However, the association between SLC20A1 expression and clinical outcomes in prostate cancer remains to be determined. MATERIALS AND METHODS: Open-source datasets (The Cancer Genome Atlas prostate, Stand Up to Cancer-Prostate Cancer Foundation Dream Team, and The Cancer Genome Atlas PanCancer Atlas) were downloaded and analyzed. SLC20A1 expression was analyzed in prostate cancer and normal prostate tissue. Survival analysis using Kaplan-Meier curves and Cox regression analysis were performed to examine patient prognosis, as well as the effects of endocrine therapy and radiotherapy on high SLC20A1 expression in patients with prostate cancer. RESULTS: SLC20A1 was higher in prostate cancer than in normal prostate tissues. High SLC20A1 expression predicted poor disease-free and progression-free survival. Following endocrine therapy, no significant difference in prognosis was observed between patients with high SLC20A1 and those with low SLC20A1 expression. However, following radiotherapy, high SLC20A1 expression tended to be associated with a poor clinical outcome. CONCLUSION: SLC20A1 may serve as a prognostic biomarker for prostate cancer, and the recommended treatment for patients with high SLC20A1 expression is endocrine therapy.

High Expression of CD58 and ALDH1A3 Predicts a Poor Prognosis in Basal-like Breast Cancer.

BACKGROUND/AIM: CD58 is an immune adhesion molecule on the cellular surface. It was previously found that a high expression of CD58 predicted a poor prognosis of patients with lower-grade gliomas. Therefore, the aim of this paper was to investigate the association between CD58 and breast cancer. MATERIALS AND METHODS: CD58 gene expression data downloaded from cBioPortal was compared between the different subtypes of breast cancer. Clinical prognosis was examined using Kaplan-Meier analysis and multivariable Cox regression analysis. The association between CD58 expression and immune cell infiltration was estimated using the TIMER 2.0 web platform. Finally, the tumour sphere formation of aldehyde dehydrogenase 1 (ALDH1)high basal-like breast cancer stem cells in which CD58 was knocked down using siRNA was measured. RESULTS: CD58 mRNA was mainly enriched in claudin-low and basal-like subtypes. The high expression of CD58 predicted a good prognosis in patients with luminal A and luminal B breast cancer. This prediction may be due to the association of immune cell infiltration with CD58. Notably, patients with luminal A breast cancer with a high expression of CD58 in association with ALDH1A3 exhibited a good prognosis; however, this did not apply to patients with basal-like breast cancer. The in vitro experiments revealed that knockdown of CD58 inhibited the tumour sphere formation ability of ALDH1high basal-like cancer cells. CONCLUSION: CD58 may function as a potential prognostic biomarker and therapeutic target in ALDH-positive basal-like cancer stem cells.

High SLC20A1 Expression Is Associated With Poor Prognosis for Radiotherapy of Estrogen Receptor-positive Breast Cancer.

BACKGROUND/AIM: Radiotherapy is one of the main treatments for estrogen receptor-positive (ER+) breast cancer. However, in some ER+ breast cancer cases, radiotherapy is insufficient to inhibit progression and there is a lack of markers to predict radiotherapy insensitivity. Solute carrier family 20 member 1 (SLC20A1) is a sodium/inorganic phosphate symporter, which has been proposed to be a viable prognostic marker for luminal A and B types of ER+ breast cancer. The present study examined the possibility of SLC20A1 as a novel biomarker for the prediction of radiotherapy efficiency. PATIENTS AND METHODS: The Molecular Taxonomy of Breast Cancer International Consortium dataset was downloaded from cBioportal and the prognosis of patients with high SLC20A1 expression (SLC20A1 high ) was compared with that of patients with low SLC20A1 expression, without or with radiotherapy and tumor stages I, II, and III, using the Kaplan-Meier method and multivariate Cox regression analyses of disease-specific and relapse-free survival. RESULTS: Patients in the SLC20A1 high group with radiotherapy showed poor clinical outcomes in both luminal A and luminal B breast cancers. Furthermore, in luminal A breast cancer at tumor stage I, patients in the SLC20A1 high  group with radiotherapy also showed poor clinical outcomes. Therefore, these results suggest that radiotherapy is insufficient for patients in the SLC20A1 high group for both luminal A and B types, and especially for the luminal A type at tumor stage I. CONCLUSION: SLC20A1 can be used as a prognostic marker for the prediction of the efficacy of radiotherapy for luminal A and luminal B breast cancers.

High Expression of p62 and ALDH1A3 Is Associated With Poor Prognosis in Luminal B Breast Cancer.

BACKGROUND/AIM: p62 (also known as sequestosome 1) is involved in cancer progression, and high expression of p62 indicates poor clinical outcome in several cancer types. However, the association between p62 gene expression and cancer stem cells (CSCs) in breast cancer subtypes remains unclear. MATERIALS AND METHODS: In the present study, genomic datasets of primary breast cancer (The Cancer Genome Atlas, n=593; and Molecular Taxonomy of Breast Cancer International Consortium, n=2,509) were downloaded. p62 Expression was then examined in normal and breast cancer tissues derived from the same patients. Kaplan-Meier and multivariate Cox regression analyses were employed to evaluate disease-specific survival. Next, the effect on cell viability and in vitro tumor-sphere formation of p62 knockdown using targeted small interfering RNA was assessed by using cells with high activity of aldehyde dehydrogenase 1 (ALDH1high). RESULTS: Patients with normal-like, luminal A or luminal B breast cancer with p62high had poor prognosis. Furthermore, patients with p62high ALDH1A3high luminal B type also exhibited poor prognoses. Knockdown of p62 suppressed viability and tumor-sphere formation by ALDH1high cells of the luminal B-type cell lines BT-474 and MDA-MB-361. These results suggest that p62 is essential for cancerous progression of ALDH1-positive luminal B breast CSCs, and contributes to poor prognosis of luminal B breast cancer. CONCLUSION: p62 is potentially a prognostic marker and therapeutic target for ALDH1-positive luminal B breast CSCs.

High expression of SLC20A1 is less effective for endocrine therapy and predicts late recurrence in ER-positive breast cancer.

Estrogen receptor-positive (ER+) breast cancer intrinsically confers satisfactory clinical outcomes in response to endocrine therapy. However, a significant proportion of patients with ER+ breast cancer do not respond well to this treatment. Therefore, to evaluate the effects of endocrine therapy, there is a need for identification of novel markers that can be used at the time of diagnosis for predicting clinical outcomes, especially for early-stage and late recurrence. Solute carrier family 20 member 1 (SLC20A1) is a sodium/inorganic phosphate symporter that has been proposed to be a viable prognostic marker for the luminal A and luminal B types of ER+ breast cancer. In the present study, we examined the possible association of SLC20A1 expression with tumor staging, endocrine therapy and chemotherapy in the luminal A and luminal B subtypes of breast cancer. In addition, we analyzed the relationship between SLC20A1 expression and late recurrence in patients with luminal A and luminal B breast cancer following endocrine therapy. We showed that patients with higher levels of SLC20A1 expression (SLC20A1high) exhibited poorer clinical outcomes in those with tumor stage I luminal A breast cancer. In addition, this SLC20A1high subgroup of patients exhibited less responses to endocrine therapy, specifically in those with the luminal A and luminal B subtypes of breast cancer. However, patients with SLC20A1high showed good clinical outcomes following chemotherapy. Patients tested to be in the SLC20A1high group at the time of diagnosis also showed a higher incidence of recurrence compared with those with lower expression levels of SLC20A1, at >15 years for luminal A breast cancer and at 10-15 years for luminal B breast cancer. Therefore, we conclude that SLC20A1high can be used as a prognostic biomarker for predicting the efficacy of endocrine therapy and late recurrence for ER+ breast cancer.

GLO 1 and PKCλ Regulate ALDH1-positive Breast Cancer Stem Cell Survival.

BACKGROUND/AIM: We examined the inhibitory effects of both glyoxalase 1 (GLO 1) and protein kinase C (PKC)λ in aldehyde dehydrogenase 1 (ALDH1)-positive breast cancer stem cells (CSCs). MATERIALS AND METHODS: Breast cancer genomics datasets (TCGA, n=593; METABRIC, n=1904) were downloaded and statistically analyzed. The effects of GLO 1 and PKCλ on trypan blue staining and tumor-sphere formation by ALDH1high cells derived from triple negative breast cancer (TNBC) and basal-like breast cancer were examined. RESULTS: GLO 1high, PKCλhigh, and ALDH1A3high tumors were enriched in stage I/II/III/IV samples, associated with the HER2 and TNBC subtypes according to receptor status, and associated with the HER2-enriched and basal-like subtypes according to PAM50. Inhibition of either GLO 1 (TLSC702) or PKCλ (ANF) suppressed tumor-sphere formation and enhanced death in ALDH1high cells. TLSC702 also effectively inhibited tumor-sphere formation and induced death in PKCλ knockout ALDH1high cells. CONCLUSION: GLO 1 and PKCλ are important for the survival of ALDH1-positive breast CSCs, and may represent potential therapeutic targets for the treatment of ALDH1-positive breast CSCs.

Roles of Ubiquitination and Deubiquitination in Regulating Dendritic Cell Maturation and Function.

Dendritic cells (DCs) are specialized antigen-presenting cells that play a key role in immune homeostasis and the adaptive immune response. DC-induced immune tolerance or activation is strictly dependent on the distinct maturation stages and migration ability of DCs. Ubiquitination is a reversible protein post-translational modification process that has emerged as a crucial mechanism that regulates DC maturation and function. Recent studies have shown that ubiquitin enzymes, including E3 ubiquitin ligases and deubiquitinases (DUBs), are pivotal regulators of DC-mediated immune function and serve as potential targets for DC-based immunotherapy of immune-related disorders (e.g., autoimmune disease, infections, and tumors). In this review, we summarize the recent progress regarding the molecular mechanisms and function of ubiquitination in DC-mediated immune homeostasis and immune response.

Chemerin enhances the adhesion and migration of human endothelial progenitor cells and increases lipid accumulation in mice with atherosclerosis.

BACKGROUND: The role of adipokines in the development of atherosclerosis (AS) has received increasing attention in recent years. This study aimed to explore the effects of chemerin on the functions of human endothelial progenitor cells (EPCs) and to investigate its role in lipid accumulation in ApoE-knockout (ApoE-/-) mice. METHODS: EPCs were cultured and treated with chemerin together with the specific p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580 in a time- and dose-dependent manner. Changes in migration, adhesion, proliferation and the apoptosis rate of EPCs were detected. ApoE-/- mice with high-fat diet-induced AS were treated with chemerin with or without SB 203580. Weights were recorded, lipid indicators were detected, and tissues sections were stained. RESULTS: The data showed that chemerin enhanced the adhesion and migration abilities of EPCs, and reduced the apoptosis ratio and that this effect might be mediated through the p38 MAPK pathway. Additionally, chemerin increased the instability of plaques. Compared with the control group and the inhibitor group, ApoE-/- mice treated with chemerin protein had more serious arterial stenosis, higher lipid contents in plaques and decreased collagen. Lipid accumulation in the liver and kidney and inflammation in the hepatic portal area were enhanced by treatment with chemerin, and the size of adipocytes also increased after chemerin treatment. In conclusion, chemerin can enhance the adhesion and migration abilities of human EPCs and reduce the apoptosis ratio. In animals, chemerin can increase lipid accumulation in atherosclerotic plaques and exacerbate plaques instability. At the same time, chemerin can cause abnormal lipid accumulation in the livers and kidneys of model animals. After specifically blocking the p38 MAPK pathway, the effect of chemerin was reduced. CONCLUSIONS: In conclusion, this study showed that chemerin enhances the adhesion and migration abilities of EPCs and increases the instability of plaques and abnormal lipid accumulation in ApoE-/- mice. Furthermore, these effects might be mediated through the p38 MAPK pathway.

[Expression profile of Notch signaling pathway-related microRNAs in immune cells of collagen-induced arthritis mice].

Objective To study the expression of Notch signaling pathway-related microRNAs in T cells of collagen-induced arthritis (CIA) mice. Methods First, the mice model was established with bovine collagen type II and immune adjuvant DBA/1 J mice. Next, peripheral blood mononuclear cells (PBMCs) were isolated and CD4+ T and CD8+ T cells were sorted from the peripheral blood, spleen, lymph node in CIA mice by using flow cytometry. Finally, real-time quantitative PCR was used to detect the expression levels of Notch signaling pathway-related microRNAs in PBMCs and T cells. Results The levels of miR-200b-3p, miR-30c-5p, miR-30b-5p and miR-23b-3p in the PBMCs of CIA mice were significantly decreased; miR-200b-3p, miR-30c-5p and miR-30b-5p in peripheral blood, spleen, lymph node CD4+ T cells and CD8+ T cells of CIA mice was not significantly different from that of normal controls; but the expression level of miR-23b-3p in peripheral blood and spleen CD4+ T cells of CIA mice was significantly lower than that of normal control mice. Conclusion miR-23b-3p may be involved in the immunoregulation of Notch signaling to T cells of CIA mice.

Asiatic Acid Prevents Oxidative Stress and Apoptosis by Inhibiting the Translocation of α-Synuclein Into Mitochondria.

The association of α-synuclein (α-syn) with mitochondria occurs through interaction with mitochondrial complex I. Defects in this protein have been linked to the pathogenesis of Parkinson disease (PD). Overexpression of α-synuclein in cells has been suggested to cause elevations in mitochondrial oxidant radicals and structural and functional abnormalities in mitochondria. Asiatic acid (AA), a triterpenoid, is an antioxidant that is used for depression, and we have shown that pretreatment with AA can prevent PD-like damage, but its therapeutic effects in PD and mechanism remain unknown. In this study, we found that 0.5-2 mg AA/100 g diet significantly improves climbing ability in drosophila and extends their life-span-effects that we attributed to its antioxidant properties. AA also protected mitochondria against oxidative stress and apoptosis in a rotenone-induced cellular model. In an isolated mitochondria model, AA attenuated the decline in mitochondrial membrane potential that was induced by α-syn. Consequently, AA maintained membrane integrity and ATP production. Finally, we demonstrated that AA protects by blocking the translocation of α-syn into mitochondria. Our results suggest that mitochondria are crucial in PD and that AA is an excellent candidate for the prevention and therapy of this disease.

Andrographolide sulfonate improves Alzheimer-associated phenotypes and mitochondrial dysfunction in APP/PS1 transgenic mice.

Alzheimer's disease is a neurodegenerative disorder with Amyloid-ß plaques onset, synaptic damage, and cognitive decline. Aß deposits cause pathological events including oxidative stress, mitochondrial dysfunction, and neuron death. In this study, APPswe/PSENΔ9 double transgenic mice model was used to imitate Alzheimer's disease and the effect and possible mechanism of Andrographolide sulfonate were examined. Andrographolide sulfonate was given to the mice for 7 months before the onset of Aß plaque. Spatial memory test showed that Andrographolide sulfonate treatment prevented cognitive decline. Aß deposits were not affected while hippocampus and synapse damage was significantly alleviated. Mechanism studies showed that oxidative stress and mitochondrial swelling was reduced after Andrographolide sulfonate administration. These findings suggest that Andrographolide sulfonate, which has been applied in clinical medicine, might be a promising therapeutic agent for AD therapy via mitochondria protection.

Endotoxin-induced autocrine ATP signaling inhibits neutrophil chemotaxis through enhancing myosin light chain phosphorylation.

Although the neutrophil recruitment cascade during inflammation has been well described, the molecular players that halt neutrophil chemotaxis remain unclear. In this study, we found that lipopolysaccharide (LPS) was a potent stop signal for chemotactic neutrophil migration. Treatment with an antagonist of the ATP receptor (P2X1) in primary human neutrophils or knockout of the P2X1 receptor in neutrophil-like differentiated HL-60 (dHL-60) cells recovered neutrophil chemotaxis. Further observations showed that LPS-induced ATP release through connexin 43 (Cx43) hemichannels was responsible for the activation of the P2X1 receptor and the subsequent calcium influx. Increased intracellular calcium stopped neutrophil chemotaxis by activating myosin light chain (MLC) through the myosin light chain kinase (MLCK)-dependent pathway. Taken together, these data identify a previously unknown function of LPS-induced autocrine ATP signaling in inhibiting neutrophil chemotaxis by enhancing MLC phosphorylation, which provides important evidence that stoppage of neutrophil chemotaxis at infectious foci plays a key role in the defense against invading pathogens.

Adenosine effectively restores endotoxin-induced inhibition of human neutrophil chemotaxis via A1 receptor-p38 pathway.

Neutrophil chemotaxis plays an essential role in recruiting neutrophils to sites of inflammation. Neutrophil chemotaxis is suppressed both after exposure to lipopolysaccharide (LPS) in vitro and during clinical and experimental endotoxemia, leading to serious consequences. Adenosine (ADO) is a potent anti-inflammatory agent that acts on a variety of neutrophil functions. However, its effects on human neutrophil chemotaxis during infection have been less well characterized. In the present study, we investigated the effect of ADO and its receptor-specific antagonist and agonist on neutrophil chemotaxis in an in vitro LPS-stimulated model. The results showed that increasing the concentration of ADO effectively restored the LPS-inhibited neutrophil chemotaxis to IL-8. A similar phenomenon occurred after intervention with a selective A1 receptor agonist but not with a selective antagonist. Pre-treatment with cAMP antagonist failed to restore LPS-inhibited chemotaxis. Furthermore, protein array and western blot analysis showed that the activation of A1 receptor significantly decreased LPS-induced p38 MAPK phosphorylation. However, the surface expression of the A1 receptor in LPS-stimulated neutrophils was not significantly changed. Taken together, these data indicated that ADO restored the LPS-inhibited chemotaxis via the A1 receptor, which downregulated the phosphorylation level of p38 MAPK, making this a promising new therapeutic strategy for infectious diseases.

[Effects of lipopolysaccharide and phytohaemagglutinin on the level of microRNAs in mouse peripheral blood mononuclear cells].

OBJECTIVE: To investigate the effects of lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) on the level of microRNAs in mouse peripheral blood mononuclear cells (PBMCs). METHODS: The mouse PBMCs were cultured in vitro and stimulated with 100 ng/mL LPS for 1 hour or 2 hours and 2.5 µg/mL phytohaemagglutinin (PHA) for 2 hours or 4 hours, respectively. The levels of miR-9, miR-122-3p, miR-181d and miR-342-3p in both PBMCs and culture supernatants were determined by real-time quantitative PCR (qRT-PCR). RESULTS: The levels of miR-9, miR-122-3p, miR-181d and miR-342-3p in PBMCs and culture supernatants had no significant difference between blank control and LPS stimulation group, nor did between LPS stimulation 2 hours group and 1 hour group. The levels of miR-9, miR-122-3p and miR-342-3p in PBMCs and culture supernatant had no significant difference between blank control and PHA stimulation group, nor did between PHA stimulation 4 hours group and 2 hours group. However, compared with blank control, the expression of miR-181d significantly increased after PHA stimulation, while the time of stimulation did not affect the miR-181d level significantly. CONCLUSION: The stimulation of PHA could promote the expression and secretion of miR-181d in mouse PBMCs.

Functional characterization of myeloid-derived suppressor cell subpopulations during the development of experimental arthritis.

Recent evidence indicates the existence of subpopulations of myeloid-derived suppressor cells (MDSCs) with distinct phenotypes and functions. Here, we characterized the role of MDSC subpopulations in the pathogenesis of autoimmune arthritis in a collagen-induced arthritis (CIA) mouse model. The splenic CD11b(+) Gr-1(+) MDSC population expanded in CIA mice, and these cells could be subdivided into polymorphonuclear (PMN) and mononuclear (MO) MDSC subpopulations based on Ly6C and Ly6G expression. During CIA, the proportion of splenic MO-MDSCs was increased in association with the severity of joint inflammation, while PMN-MDSCs were decreased. MO-MDSCs expressed higher levels of surface CD40 and CD86 protein, but lower levels of Il10, Tgfb1, Ccr5, and Cxcr2 mRNA. PMN-MDSCs exhibited a more potent capacity to suppress polyclonal T-cell proliferation in vitro, compared with MO-MDSCs. Moreover, the adoptive transfer of PMN-MDSCs, but not MO-MDSCs, decreased joint inflammation, accompanied by reduced levels of serum cytokine secretion and the frequencies of Th1 and Th17 cells in draining lymph nodes. These results suggest that there could be a shift from potently suppressive PMN-MDSCs to poorly suppressive MO-MDSCs during the development of experimental arthritis, which might reflect the failure of expanded MDSCs to suppress autoimmune arthritis.

The mitochondrial protective mechanism of olfactory ensheathing cells conditioned medium protects against H2O2-induced injury in astrocytes.

Our previous studies showed that olfactory ensheathing cells conditioned medium (OECCM), has a positive effect against apoptosis in ASTs and prevents the morphology changes in the, mitochondria, but the accurate mechanism is still unknown. In this study, we examined the mitochondrial mechanism of OECCM which may protect against H2O2-induced injury in ASTs. It was, found that OECCM could protect ASTs from the injury of 500µmol/L H2O2, decrease the intracellular, ROS and Ca(2+) level, as well inhibit apoptosis and the expression of cleaved caspase-3. Further, investigations showed that OECCM could increase both the mitochondrial membrane potential and the, ATP level, as well enhance the cell respiratory function. In summary, OECCM could protect ASTs from, damages induced by H2O2. Its mechanism may be related to the decrease of ROS generation and the, overloading of Ca(2+), then stabilization of the mitochondrial function.

Asiatic acid, a pentacyclic triterpene in Centella asiatica, attenuates glutamate-induced cognitive deficits in mice and apoptosis in SH-SY5Y cells.

AIM: To investigate whether asiatic acid (AA), a pentacyclic triterpene in Centella asiatica, exerted neuroprotective effects in vitro and in vivo, and to determine the underlying mechanisms. METHODS: Human neuroblastoma SH-SY5Y cells were used for in vitro study. Cell viability was determined with the MTT assay. Hoechst 33342 staining and flow cytometry were used to examine the apoptosis. The mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured using fluorescent dye. PGC-1α and Sirt1 levels were examined using Western blotting. Neonatal mice were given monosodium glutamate (2.5 mg/g) subcutaneously at the neck from postnatal day (PD) 7 to 13, and orally administered with AA on PD 14 daily for 30 d. The learning and memory of the mice were evaluated with the Morris water maze test. HE staining was used to analyze the pyramidal layer structure in the CA1 and CA3 regions. RESULTS: Pretreatment of SH-SY5Y cells with AA (0.1-100 nmol/L) attenuated toxicity induced by 10 mmol/L glutamate in a concentration-dependent manner. AA 10 nmol/L significantly decreased apoptotic cell death and reduced reactive oxygen species (ROS), stabilized the mitochondrial membrane potential (MMP), and promoted the expression of PGC-1α and Sirt1. In the mice models, oral administration of AA (100 mg/kg) significantly attenuated cognitive deficits in the Morris water maze test, and restored lipid peroxidation and glutathione and the activity of SOD in the hippocampus and cortex to the control levels. AA (50 and 100 mg/kg) also attenuated neuronal damage of the pyramidal layer in the CA1 and CA3 regions. CONCLUSION: AA attenuates glutamate-induced cognitive deficits of mice and protects SH-SY5Y cells against glutamate-induced apoptosis in vitro.

Protective effects of asiatic acid on rotenone- or H2O2-induced injury in SH-SY5Y cells.

Parkinson's disease (PD) is a progressive neurodegenerative disorder with a prevalence of 1-2% in people over the age of 50. Mitochondrial dysfunction occurred in PD patients showing a 15-30% loss of activity in complex I. Asiatic acid (AA), a triterpenoid, is an antioxidant and used for depression treatment, but the effect of AA against PD-like damage has never been reported. In the present study, we investigated the protective effects of AA against H(2)O(2) or rotenone-induced cellular injury and mitochondrial dysfunction in SH-SY5Y cells. Mitochondrial membrane potential (MMP) and the expression of voltage-dependent anion channel (VDAC) were detected with or without AA pretreatment following cellular injury to address the possible mechanisms of AA neuroprotection. The results showed that pre-treatment of AA (0.01-100 nM) protected cells against the toxicity induced by rotenone or H(2)O(2). In addition, MMP dissipation occurred following the exposure of rotenone, which could be prevented by AA treatment. More interestingly, pre-administration of AA inhibited the elevation of VDAC mRNA and protein levels induced by rotenone(100 nM) or H(2)O(2) (300 microM).These data indicate that AA could protect neuronal cells against mitochondrial dysfunctional injury and suggest that AA might be developed as an agent for PD prevention or therapy.

Mitochondrial dysfunction enhances susceptibility to oxidative stress by down-regulation of thioredoxin in human neuroblastoma cells.

Increasing evidence suggests that Alzheimer's disease is associated with mitochondrial dysfunction and oxidative damage. To develop a cellular model of Alzheimer's disease, we investigated the effects of thioredoxin (Trx) expression in the response to mitochondrial dysfunction-enhanced oxidative stress in the SH-SY5Y human neuroblastoma cells. Treatment of SH-SY5Y cells with 15 mM of NaN3, an inhibitor of cytochrome c oxidase (complex IV), led to alteration of mitochondrial membrane potential but no significant changes in cell viability. Therefore, cells were first treated with 15 mM NaN3 to induce mitochondrial dysfunction, then, exposed to different concentrations of H2O2. Cell susceptibility was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay and morphological observation. Expressions of Trx mRNA and protein were determined by RT-PCR; and Western-blot analysis, respectively. It was found that the SH-SY5Y cells with mitochondrial impairment had lower levels of Trx mRNA and protein, and were significantly more vulnerable than the normal cells after exposure to H2O2 while no significant changes of Trx mRNA and protein in SH-SY5Y cells exposed to H2O2 but without mitochondrial complex IV inhibition. These results, together with our previous study in primary cultured neurons, demonstrated that the increased susceptibility to oxidative stress is induced at least in part by the down-regulation of Trx in SH-SY5Y human neuroblastoma cells with mitochondrial impairment and also suggest the mitochondrial dysfunction-enhanced oxidative stress could be used as a cellular model to study the mechanisms of Alzheimer's disease and agents for prevention and treatment.