Effect of miR-24 on chemotherapy sensitivity in lung cancer A549 cells

AIM: To study the effect of microRNA (miR)-24 on chemotherapy sensitivity and its possible mechanisms in human lung adenocarcinoma A549 cells. METHODS: The expression of miR-24 in the A549 cells and A549/DDP cells was determined by real-time PCR. Transfection of miR-24 inhibitor was used to down-regulate the miR-24 level in the A549/DDP cells. The viability and apoptosis rate were measured by CCK-8 assay and flow cytometry, respectively. The protein levels of Bcl-2, Bax, cleaved caspase-3, cleaved caspase-9, cytochrome C (Cyt C), phosphorylated extracellular signal regulated kinase (p-ERK) and P53 were detected by Western blot. Luciferase reporter assay was used to predict and identify the target genes of miR-24. RESULTS: The expression of miR-24 was significantly higher in the A549/DDP cells than that in the A549 cells (P<0.05). miR-24 inhibitor induced cell apoptosis and increased the sensitivity of the A549/DDP cells to cisplatin. Furthermore, miR-24 inhibitor down-regulated the ratio of Bcl-2/Bax, while up-regulated the protein levels of P53, p-ERK, cleaved caspase-9, cleaved caspase-3 and Cyt C. Incubation with U0126, a specific ERK inhibitor, partly reversed the viability of miR-24 inhibitor transfected A549/DDP cells. Bioinformatics analysis demonstrated that p53 was a potential target gene of miR-24. Co-teansfection of miR-24 inhibitor and P53 siRNA in A549/DDP cells partially reversed the effect of miR-24 inhibitor on cell viabiltiy. CONCLUSION: Down-regulation of miR-24 increases the sensitivity of A549/DDP cells to cisplatin. The mechanism may be related to directly targeting p53 gene and over-activation of ERK/P53 signaling pathway, thus promoting apoptosis via mitochondrial apoptosis pathway.     

Nontypeable haemophilus influenzae induces IL-8 expression in alveolar epithelial cells in a p38 MAPK and NF-κB dependent manner

AIM:To investigate the key molecular mechanism of inflammatory response in alveolar epithelial cells induced by nontypeable haemophilus influenzae (NTHi). METHODS: A549 cells were co-cultured with NTHi (multiplicity of infection, MOI: 10) and harvested 15 min and 30 min after stimulation. The phosphorylation of p38 mitogen activated protein kinase (p38 MAPK) in A549 cells was detected by Western blotting. The intracellular expression of nuclear factor-κB (NF-κB) p65 was examined by flow cytometry 4 h after stimulation. A549 cells were preincubated with p38 inhibitor (SB203580) or NF-κB inhibitor (PDTC) for 1 h and then stimulated with NTHi for 24 h. The level of interleukin 8 (IL-8) in the supernatants was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The phosphorylation of p38 MAPK was rapidly induced by NTHi stimulation. The expression of NF-κB p65 in A549 cells after NTHi stimulation was significantly up-regulated compared with control group (P<0.05). The level of IL-8 in the supernatants was increased 24 h after bacterial stimulation compared with control group (P<0.05). Blockage of p38 MAPK or NF-κB remarkably decreased IL-8 secretion in A549 cells (P<0.05). CONCLUSION:NTHi induces inflammatory response in alveolar epithelial cells in a p38 MAPK and NF-κB dependent manner.     

Effect of RYR1 gene expression knock-down by siRNA on mitochondria in C2C12 cells

AIM: To investigate the effect of ryanodine receptor 1 (RYR1) down-regulation on mitochondria in mouse myoblast C2C12 cell line and to explore the possible mechanism. METHODS: The expression of RYR1 in the C2C12 cells was knocked down by the targeted small interfering RNA (siRNA). The mitochondrial number and morpholo-gical changes were evaluated by transmission electron microscopy and the stereoscopic analysis. Real-time PCR and Western blot were used to determine the mRNA and protein levels of mitofusin 2 (Mfn2), peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and extracellular signal-regulated kinase 1/2 (ERK1/2), respectively. RESULTS: The expression of RYR1 was significantly down-regulated by siRNA transfection (P<0.01), with fragmentized mitochondria in the C2C12 cells in knock-down (KD) group. Although no statistical difference of the mitochondrial number was observed, the mitochondria area and circumference were significantly lowered in KD group (P<0.05). In KD group, the mRNA and protein expression of Mfn2 was significantly reduced (P<0.01). The mRNA level of PGC-1α was also reduced (P<0.01), but no significant change at protein level was observed. No change of ERK1/2 expression and phosphorylated ERK1/2 level was detected. CONCLUSION: Knock-down of RYR1 expression leads to morphological changes of mitochondria, and down-regulation of Mfn2 expression may be involved in the underlying mechanism. While PGC-1α and ERK1/2-associated oxidative stress pathway may not play an important role in the process.     

Role of Drp1 in high glucose-induced rat cardiomyocyte hypertrophy

AIM: To investigate the effect of dynamin-related protein 1 (Drp1) on high glucose-induced cardiomyocyte hypertrophy. METHODS: The primarily cultured rat cardiomyocytes were divided into normal glucose group, mannitol group, DMSO group, high glucose group and high glucose+mitochondrial division inhibitor-1 (Mdivi-1) group. The area of single cardiomyocyte was calculated by wheat germ agglutinin staining. The mitochondrial membrane potential of the cardiomyocytes was detected by JC-1 staining, and the expression levels of atrial natriuretic peptide (ANP), the marker of cardiac hypertrophy, Drp1 and its phosphorylated proteins p-Drp1 (Ser616) and p-Drp1 (Ser637) were determined by Western blot. RESULTS: Compared with normal glucose group and mannitol group, the cell area was increased significantly and the mitochondrial membrane potential was decreased significantly in high glucose group. The protein levels of ANP and p-Drp1 (Ser616) were significantly increased, the protein level of p-Drp1 (Ser637) was decreased, and no significant difference of total Drp1 level among groups was observed. In high glucose+Mdivi-1 group, ANP expression and the protein level of p-Drp1 (Ser616) were significantly decreased, and the protein level of p-Drp1 (Ser637) was increased as compared with high glucose group. CONCLUSION: High glucose induces hypertrophy of cardiomyocytes, and the mechanism is associated with increased mitochondrial fission due to changes of Drp1 phosphorylation levels.     

Expression of miRNA-181a in human lung adenocarcinoma cells and its effect on cell function

AIM: To study the expression of microRNA (miRNA)-181a in different human lung adenocarcinoma cell lines, and to investigate the effect of miRNA-181a on cell function and its mechanism in human lung adenocarcinoma drug resistant cell A549/DDP. METHODS: Real-time PCR was used to detect the expression of miRNA-181a in BEAS-2B cells, A549 cells and A549/DDP cells. The A549/DDP cells were transfected with pGenesil-miRNA-181a eukaryotic expression plasmid. At the same time, the untransfection group and negative transfection group were also set up. The expression of miRNA-181a, cell viability, cell growth inhibition and apoptosis rate during cis-diamminedichloroplatinum (DDP) treatment, cell cycle, cell invasion, the protein expression of miRNA-181a target genes bcl-2 and p53 in the A549/DDP cells were determined by real-time fluorescence quantitative PCR, MTT assay, flow cytometry, Transwell method and Western blot, respectivly. RESULTS: The expression of miRNA-181a in A549 cells and A549/DDP cells was significantly lower than that in BEAS-2B cells, and the lowest expression level was observed in A549/DDP cells (P<0.05). The expression of miRNA-181a in A549/DDP cells was significantly increased after transfection with pGenesil-miRNA-181a (P<0.05). The cell viability, cell cycle and invasion ability of the A549/DDP cells were inhibited after miRNA-181a transfection (P<0.05). The cell growth inhibition rate and apoptotic rate of the A549/DDP cells were increased (P<0.05). The expression of Bcl-2 was reduced, but the expression of P53 was increased after transfection with miRNA-181a in A549/DDP cells (P<0.05). CONCLUSION: miRNA-181a may be correlated with the development of human lung adenocarcinoma. miRNA-181a can serve as a new target for treatment of lung cancer.     

Effects of p21-activated kinase 6 on invasion and migration of human non-small-cell lung cancer A549 cells

AIM：To investigate the effects of p21-activated kinase 6 (PAK6) on the invasive and migratory abilities of human non-small-cell lung cancer A549 cells. METHODS：The expression of PAK6 mRNA in A549 cells, human bronchial epithelial (HBE) cells, non-small-cell lung cancer tissues and paired adjacent non-tumor tissues was measured by real-time PCR. After A549 cells were transfected with siRNA-PAK6 (siPAK6) or negative control (NC) for 48 h, the expression of PAK6 at mRNA and protein levels was measured by real-time PCR and Western blotting, respectively. The invasion and migration of A549 cells were detected by Matrigel invasion assay and Transwell migration assay. The cytoskeletal changes were observed with FITC-phalloidin staining under confocal microscope. RESULTS：The level of PAK6 mRNA in A549 cells was higher than that in HBE cells (3.50±1.16 vs 1.12±0.42, P<0.05). The level of PAK6 mRNA in non-small-cell lung cancer tissues was higher than that in paired adjacent non-tumor tissues (5.13±1.33 vs 1.08±0.37, P<0.05). The expression of PAK6 protein decreased by 72% in A549 cells transfected with siPAK6 (P<0.05), and the level of PAK6 mRNA significantly decreased in A549 cells transfected with siPAK6 (3.72±0.75 vs 0.69±0.21, P<0.05). Matrigel invasion assay and Transwell migration assay demonstrated that knockdown of PAK6 markedly attenuated the invasion and migration of A549 cells (P<0.05). The cytoskeletal actin remodeling and reduction of stress fibers in A549 cells transfected with siPAK6 were observed under confocal microscope. CONCLUSION：PAK6 may affect the invasive and migratory abilities of non-small-cell lung cancer cells by cytoskeletal actin remodeling.     

Effects of survivin inhibitor YM155 on mitochondrial apoptotic pathway of retinoblastoma Y79 cells

AIM: To investigate the effects of survivin inhibitor YM155 {4,9-dihydro-1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(2-pyrazinylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium bromide} on the apoptosis, mitochondrial membrane potential (Δψ_m) and cytochrome C (Cyt C) of retinoblastoma Y79 cells, and to analyze the mitochondrial mechanisms of apoptosis.METHODS: Y79 cells were cultured in vitro and treated with YM155 at concentrations of 0, 0.5, 1, 2, 4 and 8 nmol/L. The cells in control group were treated without YM155. The proliferation of Y79 cells were measured by CCK-8 assay and bromodeoxyuridine (BrdU) labeling assay. Y79 cells were randomly divided into 4 groups:control group (with equal volume of RPMI-1640 nutrient medium), positive control group (10 nmol/L topotecan), low-dose (1 nmol/L) YM155 group and high-dose (2 nmol/L) YM155 group. The effects of YM155 on the apoptosis, the changes of Δψ_m, the mitochondrial distribution and the protein level of Cyt C in the Y79 cells were evaluated by flow cytometry with Annexin V-FITC/PI staining, JC-1 staining, immunofluorescence analysis and Western blot, respectively. RESULTS: Compared with control group, YM155 significantly inhibited the proliferation of Y79 cells and induced apoptosis (P<0.05). YM155 significantly reduced Δψ_m of the Y79 cells, promoted Cyt C which released from mitochondria to the cytosol and reduced the protein level of Cyt C in the mitochondria (P<0.05). CONCLUSION: YM155 inhibits Y79 cell proliferation and induces apoptosis, and the possible mechanisms may be involved in the mitochondrium-mediated apoptotic pathway.     

Effect of Ginsenoside Rh2 on apoptosis of human osteosarcoma cell line MG-63

AIM: To investigate the effect of Ginsenoside Rh2(Rh2) on the apoptosis of human osteosarcoma cell line MG-63.METHODS: The cell viability was determined by MTT assay. MG-63 cell apoptotic rate was examined by flow cytometry with Annexin V-PI double staining. The expression of Bcl-2, Bax, cytochrome C(Cyt C) and cleaved caspase-3 were measured by Western blot.RESULTS: Rh2 enhanced the apoptosis of MG-63 cells in a dose-dependent manner. Furthermore, after treatment with Rh2, the release of mitochondrial Cyt C and Bax expression were increased, while Bcl-2 and the ratio of Bcl-2/Bax were decreased as compared with control group(P<0.05). The protein level of cleaved caspase-3 was also increased(P<0.05).CONCLUSION: Ginsenoside Rh2 accelerates the apoptosis of MG-63 cells through mitochondria-dependent pathway, suggesting that Rh2 is a novel approach for the treatment of osteosarcoma.     

Genipin inhibits oxidative stress and apoptotic damage in high glucose-induced H9c2 cardiomyocytes

AIM:To explore the effects of genipin (GEN) on high glucose (HG)-induced oxidative stress injury and apoptosis in H9c2 cardiomyocytes.METHODS:H9c2 cells were cultured in vitro and HG-induced injury model was established. H9c2 cells were divided into 4 groups:normal control (NC) group (glucose at 5.6 mmol/L), HG group (glucose at 50 mmol/L), NG+GEN group and HG+GEN group. The concentration of genipin was used at 10 μmol/L. The viability of the H9c2 cells was measured by CCK-8 assay. The intracellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined by enzyme labeling and WST-1 methods, respectively. The activity of lactate dehydrogenase (LDH) in the cell culture supernatant was detected by microplate method. Fluorescent probe DCF was used to detect intracellular levels of reactive oxygen species (ROS). Nucleosome fragments was measured to evaluate cell apoptosis by ELISA. The intracellular mitochondrial membrane potential was detected by JC-1 method. The protein levels of Mn-SOD, cytochrome C (Cyt C), Bax and cleaved caspase-3 were determined by Western blot. RESULTS:Compared with HG group, the cell viability in HG+GEN group was increased significantly (P<0.05), the levels of MDA and LDH were decreased (P<0.05), SOD activity was increased (P<0.05), the levels of ROS and nucleosome fragments in HG+GEN group were decreased (P<0.05), and the mitochondrial membranes potential was notably increased (P<0.05). Compared with NG group, the activation of Mn-SOD was decreased, but the protein levels of Cyt C, Bax and cleaved caspase-3 were increased in HG group (P<0.05). Compared with HG group, the activation of Mn-SOD was increased, and the protein levels of Cyt C, Bax and cleaved caspase-3 were decreased in HG+GEN group (P<0.05).CONCLUSION:Genipin protects HG-induced H9c2 cardiomyocytes against oxidative stress injury and apoptosis.     

Effects of tangeretin on growth and invasion of human non-small-cell lung cancer cells

AIM: To study the influences of tangeretin (TGN) on the growth and invasion of non-small-cell lung cancer (NSCLC) cells, and to explore the molecular mechanisms. METHODS: The A549 cells were treated with different concentrations of TGN in vitro. The relative cell activity was determined by MTT assay. The apoptotic rate was analyzed by flow cytometry with Annexin V-FITC/PI staining. The number of the invasive cells was measured by Transwell assay. The mRNA expression of MMP-2 and MMP-9 was detected by RT-PCR, and the protein levels of Ki67, Cyt C, caspase-3, cleaved caspase-3, MMP-2, MMP-9, Akt, p-Akt and p-PI3K were determined by Western blotting analysis. RESULTS: TGN inhibited the proliferation of A549 cells in a dose-dependent manner (P<0.05) along with the low expression level of proliferation biomarker Ki67. TGN up-regulated the protein levels of Cyt C, caspase-3 and cleaved caspase-3 (P<0.01) and promoted the apoptosis of A549 cells in a dose-dependent manner. Moreover, TGN down-regulated the invasion-related molecules MMP-2 and MMP-9 at the mRNA and protein levels, and the number of invasive cells reduced with the increase in the concentration of TGN. The protein levels of p-Akt and p-PI3K in the A549 cells was reduced (P<0.05), and no difference of the cell viability in the cells treated with different concentrations of TGN was observed after blocking PI3K/Akt signaling pathway using LY294002. CONCLUSION: TGN inhibits the growth and invasion of A549 cells and promotes the cell apoptosis by potentially inhibiting PI3K/Akt signaling pathway activation. Therefore, this study will provide a new target for the prevention and control of NSCLC.     

Down-regulation of lncRNA PCAT1 suppresses oral squamous cell carcinoma cell proliferation,growth, invasion,migration and epithelial-mesenchymal transition

AIM: To investigate the effects of the long non-coding RNA (lncRNA) PCAT1 on the oral squamous cell carcinoma (OSCC) cell proliferation, growth, invasion and migration, and to explore the underlying mechanisms. METHODS: The PCAT1 siRNA was transfected by Lipofectmine 2000, and RT-qPCR and Western blot were performed to determine the mRNA and protein expression of relevant genes, respectively. CCK-8 assay and colony formation assay were used to measure OSCC cell proliferation and growth, respectively. The cell invasion and migration assays were used to measure the invasive and migratory abilities of the OSCC cells, respectively. RESULTS: PCAT1 was significantly up-regulated in OSCC tissues and cells compared with normal adjacent tissues and normal human oral keratinocyte cells, respectively (P<0.05). PCAT1 siRNA transfection suppressed the expression of PCAT1 in Tca8113 and TSCCa cells (P<0.05). Knockdown of PCAT1 in Tca8133 cells and TSCCa cells significantly suppressed the cell proliferation, invasion and migration abilities (P<0.05). In addition, knockdown of PCAT1 in Tca8133 cells and TSCCa cells also suppressed the mRNA and protein levels of ZEB-1, N-cadherin and vimentin, and increased the mRNA and protein expression of E-cadherin (P<0.05). CONCLUSION: Knockdown of PCAT1 suppresses cell proliferation and migration abilities, and the effect of PCAT1 on OSCC cells may be associated with epithelial-mesenchymal transition.     

Ursolic acid inhibits migration and invasion of human lung cancer A549 cells by targeting miRNA-133a

AIM: To investigate the effects of ursolic acid (UA) on the migration and invasion of human lung cancer cell line A549, and to explore its mechanism. METHODS: The cell viability was detected by MTT assay. The expression of miRNA-133a was detected in the A549 cells treated with UA by real-time PCR. The miRNA-133a mimics and inhibitor were transfected into the A549 cells, and the transfection efficiency was analyzed by real-time PCR. The cell migratory and invasive abilities were determined by wound healing and Transwell methods, respectively. RESULTS: The viability of the human lung cancer A549 cells was significantly inhibited by UA in a dose-dependent manner (P<0.05). IC₅₀ of UA (24 h) for lung cancer A549 cells was 31.04 μmol/L. UA treatment significantly inhibited the migratory and invasive abilities of A549 cells in a concentration-dependent manner, accompanied by significantly elevation of miRNA-133a expression. The mimics and inhibitor of miRNA-133a significantly upregulated and downregulated the expression of miRNA-133a in the transfected A549 cells, respectively. In addition, the viability of the A549 cells was decreased extremely after tansfected with the miRNA-133a mimics (P<0.01), so did the results of the cell migration and invasion test. The A549 cells tansfected with the miRNA-133a inhibitor showed an opposite changes of the cell viability, migration and invasion. CONCLUSION: UA inhibited the viability, migration and invasion of lung cancer A549 cells by elevating the expression of miRNA-133a.     

Cyanidin attenuates pressure overload-induced cardiac remodeling in mice via mitochondrial fusion enhancement

AIM To investigate the effect of cyanidin （Cyn） on pressure overload-induced cardiac remodeling and the underlying mechanism. METHODS Six-week-old male C57BL/6 mice （n=120） were divided into 4 groups： sham group （n=20）, sham+Cyn group （n=20）, transverse aortic constriction （TAC） group （n=40） and TAC+Cyn group （n=40）. The model of cardiac chronic pressure overload was induced by TAC, and the first day of TAC was defined as day 0. The animals in sham+Cyn group and TAC+Cyn group were treated with Cyn dissolved in DMSO and normal saline （5 mg·kg^-1·d^-1） for 5 d before TAC, while the animals in sham group and TAC group were treated with the same amount of DMSO and normal saline. Four weeks after TAC, the survival rate of the animals in each group was analyzed, the heart function of the mice was measured by ultrasound echocardiography, and the heart weight/body weight and lung weight/body weight were calculated. The cross-sectional area of the cardiomyocytes was measured by wheat germ agglutinin staining and hematoxylin-eosin staining. The degree of cardiac oxidative stress was evaluated by dihydroethidium staining and measurement of superoxide dismutase （SOD） and malondialdehyde （MDA） levels. The cardiomyocyte apoptosis was detected by TUNEL method. The mRNA expression levels of atrial natriuretic peptide （ANP）, brain natriuretic peptide （BNP） and β-myosin heavy chain （β-MHC） were detected by RT-qPCR, and the protein expression levels of Bax, Bcl-2, optic atrophy protein 1 （OPA1） and dynamin-related protein 1 （Drp1） were determined by Western blot. The mitochondrial morphological changes were observed by transmission electron microscopy. RESULTS Compared with TAC group, the survival rate of the mice in TAC+Cyn group was significantly increased （P<0.05）, the myocardial apoptosis, the cross-sectional area of myocardial cells, the heart weight/body weight, the lung weight/body weight, the level of reactive oxygen species and the MDA content were decreased （P<0.05）, and the SOD was activated （P<0.05）. M-mode ultrasound tests showed that Cyn treatment significantly increased left ventricular ejection fraction and left ventricular fractional shortening in the mice after TAC （P<0.05）, while left ventricular end-diastolic diameter and left ventricular posterior wall thickness in diastole were reduced （P<0.05）. Transmission electron microscopic observation showed that the number of myocardial mitochondria was increased and the mitochondrial area was decreased after TAC （P<0.05）, while treatment with Cyn increased the area of myocardial mitochondria and decreased the mitochondrial number （P<0.05）. Compared with sham group, the protein level of OPA1 in TAC group was significantly reduced （P<0.05）, while treatment with Cyn significantly increased the protein level of OPA1. CONCLUSION Cyanidin significantly increases the survival rate, improves the cardiac function and attenuates the cardiac remodeling of the mice after TAC. The mechanism may be related to the inhibition of myocardial mitochondrial OPA1 cleavage and the promotion of mitochondrial fusion.     

miR-486 targeted regulation of PTEN on LPS-induced apoptosis of alveolar epithelial cell A549

AIM: To investigate the effect of microRNA-486 (miR-486) on lipopolysaccharide (LPS)-induced apoptosis of alveolar epithelial cell A549. METHODS: A549 cells were treated with LPS, and the expression of miR-486 was detected by RT-qPCR. miR-486 mimics were transfected into LPS-induced A549 cells, and RT-qPCR was used to detect the up-regulation effect. The apoptotic rate was analyzed by flow cytometry and the protein levels of cleaved caspase-3 (C-caspase-3) and C-caspase-9 were determined by Western blot. The target gene prediction software was used to predict the target gene PTEN of miR-486. Luciferase reporter vector was used to identify the target relationship. pcDNA 3.1-PTEN and miR-486 mimics were co-transfected into A549 cells to detect the effect of PTEN up-regulation on apoptosis of miR-486 mimics transfected A549 cells stimulated with LPS. RESULTS: After LPS treatment, the expression of miR-486 in A549 cells was significantly decreased (P<0.05). Transfection of miR-486 mimics significantly up-regulated the expression of miR-486 in A549 cells stimulated with LPS (P<0.05). The apoptotic rate of A549 cells and the protein levels of C-caspase-3 and C-caspase-9 were significantly increased after LPS treatment (P<0.05). Up-regulation of miR-486 significantly down-regulated LPS-induced apoptosis of A549 cells (P<0.05). The expression of PTEN was negatively regulated by miR-486. Transfection of pcDNA 3.1-PTEN significantly increased the expression of PTEN, promoted the apoptosis and increased the protein levels of C-caspase-3 and C-caspase-9 in A549 cells stimulated with LPS after co-transfection with miR-486 mimics(P<0.05). CONCLUSION: miR-486 inhibits PTEN expression and reduces LPS-induced apoptosis of A549 cells.     

Influence of hydrogen sulfide on ileal epithelial cell apoptosis in rats with intestinal ischemia-reperfusion injury

AIM: To investigate the influence of hydrogen sulfide (H₂S) on intestinal epithelial cell mitochondrial morphology and function and the expression of caspase-3, cleaved caspase-3, cytochrome C (Cyt C), Bcl-2 and Bax in rats with intestinal ischemia-reperfusion (I/R) injury. METHODS: Wistar rats (n=24) were randomly divided into 3 groups (8 in each group): sham group, I/R group and I/R+sodium hydrosulfide (NaHS) group. The animal model of intestinal I/R injury was established. The rats in I/R+NaHS group received NaHS (100 μmol/kg bolus +1 mg·kg^-1·h^-1 infusion) 10 min prior to the onset of reperfusion, whereas the rats in I/R group and sham group received equal volume of normal sodium. Ileum epithelial mitochondrial morphology and function were measured. Plasma H₂S was detected by sensitive sulfide electrode. The expression of Bcl-2 and Bax mRNA was studied by RT-PCR. The protein levels of caspase-3, cleaved caspase-3, cytochrome C (Cyt C), Bcl-2 and Bax were tested by Western blot.RESULTS: The area, volume density, maximum diameter, minimum diameter and equivalent diameter of mitochondria, and the expression of cleaved caspase-3, Cyt C and Bax in I/R group were significantly higher than those in I/R+NaHS and sham groups (P<0.01). The mitochondrial count, circumference, specific surface area, area density and population density, plasma H₂S, respiratory control rate (RCR), the ratio of P/O, R₃ , R₄, and the expression of Bcl-2 in I/R group were sharply lower than those in I/R+NaHS and sham groups (P<0.01). H₂S was negatively correlated with caspase-3, cleaved caspase-3, Cyt C and Bax (P<0.01), and was positively correlated with Bcl-2 (P<0.01). CONCLUSION: H₂S has a protective effect on mitochondrial morphology and function in rats with intestinal I/R injury by down-regulating cleaved caspase-3, Cyt C and Bax and up-regulating Bcl-2.     

Salinomycin promotes the apoptosis-inducing effect of gefitinib on human lung adenocarcinoma cell line A549

AIM: To investigate the effect of salinomycin alone or in combination with gefitinib (an inhibitor of epidermal growth factor receptor tyrosine kinase) on the growth and apoptosis of human non-small-cell lung cancer cell line A549. METHODS: The inhibitory effect of salinomycin on the growth of A549 cells was tested by MTT assay. The cell apoptosis and the level of mitochondrial membrane potential were determined by flow cytometry. The activity of caspase-3, -8, and -9 was measured by the method of colorimetry. The protein levels of cytochrome C, Bcl- 2, p-EGFR, p-Akt and p-ERK were detected by Western blotting. RESULTS: Salinomycin or gefitinib alone inhibited the growth of A549 cells in a dose-dependent manner. Salinomycin or gefitinib also induced apoptosis of the cells. Salinomycin combined with gefitinib produced stronger inhibitory effect on the cell proliferation, and a significant increase in cell apoptosis was also observed. Compared with control group, salinomycin alone significantly reduced mitochondrial membrane potential, transitorily increased the levels of intracellular reactive oxygen species (ROS), cytoplasmic cytochrome C and Ca2+, and increased the activity of caspase-3, -8 and -9 in A549 cells. Gefitinib alone inhibited the protein expression of p-EGFR, p-Akt and p-ERK, but no obvious effect on the release of cytochrome C and the activity of caspase-3, -8 and -9 was found. The combination of salinomycin and gefitinib significantly reduced the protein levels of Bcl-2, p-EGFR, p-Akt and p-ERK, but the protein levels of EGFR, Akt and ERK were not obviously changed. CONCLUSION: The synergy of salinomycin and gefitinib is observed. Salinomycin inhibits the growth and induces apoptosis of human lung carcinoma A549 cells through Bcl-2 pathway and mitochondrial apoptosis pathway. Salinomycin also increases the sensitivity of A549 cells to gefitinib.     

H IF-1αm ediates effect of interm ittent hypoxia on biological behavior of A 549 cells in vitro

ATM: To investigate whether hypoxia-inducible factor 1α (HIF-1α) mediates the effect of intermittent hypoxia on A549 cell viability, apoptosis and invasive ability METHODS: A549 cells were transfected with HIF-1α-siRNA and cultured under intermittent hypoxia. The expression of HIF-1α and its downstream genes, such as Bcl-2, Bax, P53, P21 and VEGF at mRNA and protein levels was determined by real-time PCR and Western blot. The viability of the A549 cells was measured by MTT assay. The apoptosis and cell cycle distribution of the A549 cells were examined by flow cytometry. The invasive ability of the A549 cells was detected by transwell test. RESULTS: The expression levels of HIF-1α, Bcl-2 and VEGF in non-HIF-1α-siRNA transfected A549 cells cultured in intermittent hypoxia environment[blank controlgroup(IH C),empty vector control group (IH E) and negative control group (IH N)] were higher than those in the A549 cells in normoxia group (RA), but the expression levels of Bax and P21 were lower than those in RA group (P<0.05). The siRNA-mediated HIF-1α gene silencing[intermittent hypoxia silenced group (IHS)] resulted in obvious down-regulation of HIF-1α, Bcl-2 and VEGF, and significant increase in the protein expression of P21 and Bax(P<0.05). The expression level of P53 in intermittent hypoxia groups was significantly higher than that in RA group, and no significant difference of P53 expression in different intermittent hypoxia groups was observed. Compared with normoxia, intermittent hypoxia resulted in significantly enhanced cell viability, decreased apoptosis, and enhanced invasive ability of non-HIF-1α-siRNA transfected A549 cells (P<0.05). The siRNA-mediated HIF-1α gene silencing resulted in significant cell viability inhibition, elevated apoptotic rate and decreased invasive ability under hypoxic condition (P<0.05).CONCLUSION: Intermittent hypoxia promotes the viability and invasion of A549 cells by HIF-1α-mediated downstream gene expression. HIF-1α gene silencing inhibits A549 cell growth and invasion under intermittent hypoxia by inhibition of HIF-1α signal pathways in vitro.     

Effects of uric acid on mitochondrial damage and Pgam5/Drp1 expression in rat kidney cells

AIM To investigate the effects of uric acid on mitochondrial damage and the expression of phosphoglycerate mutase family member 5 (Pgam5) and dynamin-related protein 1 (Drp1) in rat kidney cells. METHODS Normal rat kidney NRK-52E cells were treated with uric acid at 0.6 mmol/L. The cell viability was measured by MTT assay. The cell morphological change was observed by Hoechst 33258 staining. The apoptosis of the cells was analyzed by flow cytometry. The morphological structure of mitochondria was observed under transmission electron microscope. The expression of Pgam5 and Drp1 was examined by immunofluorescence staining. The mRNA expression of Pgam5 in mitochondria was detected by RT-qPCR. The protein expression of Pgam5 and Drp1 in the cytoplasmic matrix was determined by Western blot. RESULTS Uric acid significantly decreased the viability of NRK-52E cells, and significantly increased the apoptotic rate of the cells (P<0.01). Mitochondrial swelling, vacuolation and cristal rupture were observed after the NRK-52E cells were treated with uric acid, and the mRNA expression of Pgam5 in mitochondria was decreased significantly, while the protein expression of Pgam5 and Drp1 in the cytoplasmic matrix was increased significantly (P<0.01). CONCLUSION Uric acid intervention destroys the mitochondrial structure of rat renal cells, up-regulates the expression of Pgam5 and Drp1 in the cytoplasmic matrix, and induces apoptosis of the cells.