Effect of HIPK2 gene on viability,apoptosis and JAK2/STAT3 signaling pathway in NRK-52E renal tubular epithelial cells induced by hypoxia and reoxygenation

AIM: To investigate the effect of homeodomain-interacting protein kinase 2 (HIPK2) on the viabi-lity, apoptosis and JAK2/STAT3 signaling pathway in NRK-52E renal tubular epithelial cells induced by hypoxia and reoxygenation (H/R). METHODS: HIPK2 small interfering RNA (siRNA) was transfected into NRK-52E cells by Lipofectamine^TM 2000, and normal control group (control group) and negative control group (HIPK2-NC group) were set up. After H/R, the cell viability was measured by CCK-8 assay, the apoptotic rate and Ca²⁺ fluorescence intensity were analyzed by flow cytometry, and the protein levels of Ki67, cleaved caspase-3, caspase-12, Bcl-2, Bax, p-JAK2 and p-STAT3 were determined by Western blot. RESULTS: Compared with control group, the protein expression of HIPK2 in the NRK-52E cells was significantly decreased after transfection with HIPK2 siRNA (P<0.05). Compared with control group, the cell viability and the protein expression of Ki67 and Bcl-2 in H/R group were also significantly decreased, and the apoptotic rate, the Ca²⁺ fluorescence intensity and the protein levels of cleaved caspase-3, caspase-12, Bax, p-JAK2 and p-STAT3 were significantly increased (P<0.05). Compared with H/R group, the cell viability and the protein expression of Ki67 and Bcl-2 in HIPK2-siRNA+H/R group were significantly increased, while the apoptotic rate, the Ca²⁺ fluorescence intensity and the protein levels of cleaved caspase-3, caspase-12, Bax, p-JAK2 and p-STAT3 were significantly decreased (P<0.05). CONCLUSION: Inhibition of HIPK2 gene expression promotes H/R-induced growth of NRK-52E renal tubular epithelial cells, and reduces the apoptosis. The mechanism is related to down-regulating the JAK2/STAT3 signaling pathway.     

Effects of Homer1a over-expression on apoptosis and AMPK protein expression in mechanically injured neurons

AIM:To investigate the effects of Homer1a over-expression on the apoptosis and AMP-activated protein kinase (AMPK) protein expression in mechanically injured neurons. METHODS:The rat cortical neurons were isolated and cultured in vitro, and then ramdomly divided into control group, model group, empty vector group, and Exp-Homer1a group. Neuron models with mechanical injury were constructed and infected with the Homer1a over-expression vector. The mRNA expression of Homer1a was detected by qPCR. The cell viability in each group was detected by MTT assay. The activity of lactate dehydrogenase (LDH) in the supernatant of each group was measured by LDH test kit. The apoptosis level was analyzed by flow cytometry. The protein levels of Hormer1a, cleaved caspase-3, Bax, Bcl-2, p-AMPKα and AMPKα were determined by Western blot. RESULTS:Compared with control group, the viability of mechanically injured neurons was significantly decreased, the LDH activity in the supernatant and neuronal apoptotic rate were significantly increased (P<0.05), and Homer1a expression at mRNA and protein levels was significantly increased (P<0.05). Compared with model group, the LDH activity in the supernatant and neuronal apoptotic rate in Exp-Homer1a group were significantly decreased, the protein levels of cleaved caspase-3 and Bax were significantly decreased (P<0.05), and the protein levels of Bcl-2 and p-AMPKα were significantly increased (P<0.05). CONCLUSION:Over-expression of Homer1a may increase the viability of mechanically injured neurons and inhibit their apoptosis by promoting the activation of AMPKα phosphorylation.     

Protective effect of BNDF on vascular endothelial cells with H2O2-induced oxidative injury

AIM: To study the protective effect of brain-derived neurotrophic factor (BDNF) on vascular endothelial cells with H₂O₂-induced oxidative injury. METHODS: Human umbilical vein endothelial cells (HUVECs) were cultured in vitro, and the oxidation injury model of HUVECs was established by treatment with H₂O₂. The oxidatively injured HUVECs were cultured with different concentrations (1, 10 and 100 μg/L) of BDNF. At the same time, the control group (no injury), PBS treatment after H₂O₂ injury group and TrkB inhibitor group (with 100 μg/L BDNF and 1: 1 000 TrkB inhibitor) were also set up. The viability of the HUVECs was detected by MTT assay. The levels of LDH, MDA, SOD and GSH were measured. The releases of NO, ET-1 and ICAM-1 were analyzed by ELISA. The changes of ROS production and cell apoptosis were evaluated by flow cytometry. The protein levels of TrkB, p-TrkB, cleaved caspase-3, Bcl-2 and Bax were determined by Western blot. RESULTS: Compared with uninjured control group, in H₂O₂ oxidative injury plus PBS treatment group, the viability of the cells was decreased significantly, the LDH and MDA levels were increased significantly and the activities of SOD and GSH were decreased significantly. The NO secretion was decreased, and the ET-1 and ICAM-1 concentrations were increased significantly. The ROS content and apoptotic rate were increased significantly. The protein levels of cleaved caspase-3 and Bax were increased but Bcl-2 protein expression was decreased significantly. Compared with PBS treatment group, in H₂O₂-injured HUVECs treated with different concentrations of BDNF, the cell viability was gradually increased, the LDH and MDA levels were decreased and the activities of SOD and GSH were increased gradually. The secretion of NO was increased but ET-1 and ICAM-1 were decreased gradually. The ROS content and apoptotic rate were decreased significantly. The TrkB and p-TrkB levels were significantly increased significantly, the protein expression of cleaved-caspase 3 and Bax was decreased gradually and the Bcl-2 protein expression increased gradually. The role of BDNF was inhibited by TrkB inhibitor. CONCLUSION: BDNF protects HUVECs from oxidative injury by binding with TrkB to activate the BDNF-TrkB signaling pathways.     

Effect of Herba Taxilli extracts combined with miR-375 on viability and apoptosis of osteoarthritic chondrocytes

AIM To study the effects of extracts of Herba Taxilli (Sangjisheng, SJS) on the viability and apoptosis of osteoarthritic chondrocytes and the underlying mechanism. METHODS Human primary osteoarticular chondrocytes (RPOC) were divided into control group, interleukin-1β (IL-1β) group, IL-1β+low-dose extracts of SJS (SJS-L) group, IL-1β+medium-dose extracts of SJS (SJS-M) group, IL-1β+high-dose extracts of SJS (SJS-H) group, IL-1β+anti-miR-NC group, IL-1β+anti-miR-375 group, IL-1β+SJS-H+miR-NC group, IL-1β+SJS-H+miR-375 group. The cell viability was measured by MTT assay, apoptosis was analyzed by flow cytometry, miR-375 expression was detected by qPCR, and the protein levels of cyclin D1, P21, Bcl-2, Bax and caspase-3 were determined by Western blot. RESULTS Compared with control group, the viability of RPOC at 24 h, 48 h and 72 h and the protein expression levels of cyclin D1 and Bcl-2 were significantly decreased (P<0.05), the protein levels of P21, Bax and caspase-3, the apoptotic rate and the expression level of miR-375 were remarkably increased in IL-1β group(P<0.05). Compared with IL-1β group, the cell viability at 24 h, 48 h and 72 h and the protein expression of cyclin D1 in the RPOC were greatly increased (P<0.05), while the expression of P21 was significantly decreased in IL-1β+SJS-M group and IL-1β+SJS-H group(P<0.05).The apoptotic rate, Bax, caspase-3 protein and miR-375 expression were obviously decreased (P<0.05), and Bcl-2 protein level was significantly increased in IL-1β+SJS-H group compared with IL-1β group(P<0.05). Compared with IL-1β+anti-miR-NC group, the expression of miR-375, the protein levels of P21, Bax, caspase-3 and the apoptotic rate in the RPOC of IL-1β+anti-miR-375 group were markedly decreased (P<0.05), while the cell viability at 24 h, 48 h and 72 h and the protein levels of cyclin D1 and Bcl-2 were significantly increased (P<0.05). Over-expression of miR-375 reversed the effects of extracts of SJS on the viability and apoptosis of RPOC with IL-1β stimulation. CONCLUSION The extracts of Herba Taxilli promotes the viability and inhibits apoptosis of RPOC treated with IL-1β, which is related to the regulation of miR-375 expression.     

siRNA targeting TRIM29 gene induces apoptosis of nasopharyngeal carcinoma cells by inhibiting PI3K/AKT signaling pathway

AIM:To investigate the effect of TRIM29 gene expression silencing on the apoptosis and PI3K/AKT signaling pathway in human nasopharyngeal carcinoma 5-8F cells. METHODS:The 5-8F cells were divided into blank group, negative control (NC) group (transfected negative control siRNA) and si-TRIM29 group (transfected TRIM29 specific siRNA). The viability of the 5-8F cells transfected with si-TRIM29 for 0~96 h was measured by CCK-8 assay. The apoptotic rate and the protein levels of TRIM29, cleaved caspase-3, cleaved caspase-9, Bcl-2, Bax, t-AKT and p-AKT in the 5-8F cells transfected with si-TRIM29 for 48 h were determined by flow cytometry and Western blot, respectively. PI3K/AKT signal specific inhibitor LY294002 at 10 μmol/L and si-TRIM29 alone or in combination were treated with the 5-8F cells, and the cells were divided into blank group, LY294002 group and LY294002+si-TRIM29 group. The apoptotic rates in the 3 groups were detected by flow cytometry. RESULTS:The protein expression of TRIM29 in the 5-8F cells transfected with TRIM29 siRNA was significantly lower than that in blank group (P<0.05). Compared with blank group, the cell viability was significantly decreased, the apoptotic rate was significantly increased, the protein levels of cleaved caspase-3, cleaved caspase-9 and Bax were significantly increased, and the protein levels of Bcl-2 and p-AKT were significantly decreased in si-TRIM29 group (P<0.05). The apoptotic rate in LY294002 group was higher than that in blank group, while that in LY294002+si-TRIM29 group was even higher than that in LY294002 group (P<0.05). CONCLUSION:Silencing of TRIM29 gene expression induces apoptosis of nasopharyngeal carcinoma 5-8F cells by inhibiting PI3K/AKT signaling pathway.     

Effect of 27nt-miRNA on apoptosis of human umbilical vein endothelial cells induced by oxidized low-density lipoprotein

AIM To investigate the effect of 27nt-miRNA （27nt-miR） on apoptosis of human umbilical vein endothelial cells （HUVECs） induced by oxidized low-density lipoprotein （Ox-LDL） and its underlying mechanism. METHODS HUVECs were cultured in vitro and grouped as below： normal control group， Ox-LDL group， 27nt-miR+Ox-LDL group， anti-27nt-miR+Ox-LDL group and negative control+Ox-LDL group. The cells in Ox-LDL group were treated with Ox-LDL at 40 mg/L for 48 h， while those in normal control group were untreated but cultured normally. The cells in 27nt-miR+Ox-LDL group， anti-27nt-miR+Ox-LDL group and negative control+Ox-LDL group were transfected with their corresponding lentiviral vectors under the same procedure， followed by treatment with Ox-LDL at 40 mg/L for 48 h to induce apoptosis. The cell viability was measured by CCK-8 assay. The migration capacity was detected by scratch assay. The caspase-3 activity was measured by caspase-3 activity assay kit. The apoptotic rate was analyzed by Hoechst 33258 and flow cytometry. The mRNA and protein expression levels of Bcl-2， Bax and caspase-3 were determined by RT-qPCR and Western blot. RESUITS： Compared with negative control+Ox-LDL group， the cell viability and migration ability were significantly decreased by over-expression of 27nt-miR in the HUVECs （P<0.05）， while the activity of caspase-3 and apoptosis induced by Ox-LDL were significantly increased （P<0.05）. Furthermore， the mRNA and protein expression levels of Bax and caspase-3 were significantly up-regulated （P<0.05）， and the mRNA and protein expression level of Bcl-2 was down-regulated in 27nt-miR+Ox-LDL group （P<0.05）. Meanwhile， all the above indexes showed an opposite tendency in anti-27nt-miR+Ox-LDL group. CONCLUSION 27nt-miR promotes Ox-LDL-induced apoptosis and inhibits the viability and migration of HUVECs in vitro， possibly through regulating the expression of apoptotic/anti-apoptotic proteins such as Bax，caspase-3 and Bcl-2.     

Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells via PI3K/Akt signaling pathway

AIM:To investigate the effect of apelin-13 on nicotine-induced apoptosis of cardiomyocytes and its potential molecular mechanism. METHODS:Rat H9c2 cells were treated with nicotine (10 μmol/L) to induced apoptosis. Flow cytometry was used to detect apoptotic rate. Western blot was used to determined the expression of related proteins. RESULTS:Compared with control group, nicotine treatment significantly increased the apoptotic rate of the H9c2 cells (P<0.01), and the protein levels of apoptosis-related proteins Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with nicotine group, apelin-13+nicotine significantly decreased the apoptotic rate of the H9c2 cells (P<0.01) and the the protein levels of Bax and cleaved caspase-3, but markedly increased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with apelin-13+nicotine group, apelin-13+nicotine+PI3K/Akt inhibitor LY294002 significantly increased the apoptotic rate of the H9c2 cells (P<0.01) and the protein levels of Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt and p-PI3K (P<0.05). CONCLUSION:Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells through PI3K/Akt signaling 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.     

Brucine induces apoptosis in colon cancer SW480 cells via inhibiting IL-6/STAT3 signaling pathway

AIM: To observe the effects of brucine on the viability and apoptosis of colon cancer SW480 cells.METHODS: The SW480 cells were divided into control group, 1 μmol/L brucine treatment group, 100 μg/L IL-6 treatment group and IL-6＋brucine treatment group. The cell viability was detected by CCK-8 assay. The apoptotic rate was measured by flow cytometry using fluorescein-labeled Annexin V/PI. The changes of apoptosis-related proteins were determined by Western blot. The protein level of p-STAT3 was also detected by immunofluorescence staining. RESULTS: Brucine inhibited SW480 cell growth, and the viability inhibition rate of the SW480 cells treated with brucine alone was more efficient than using brucine combined with IL-6 (P < 0.05). The apoptotic SW480 cells increased significantly after 1 μmol/L brucine treatment as compared with brucine treatment alone (P < 0.05). The apoptotic SW480 cells were significantly reduced in brucine and IL-6 combination treatment group (P < 0.05). Brucine inhibited the protein level of p-STAT3 significantly. The protein level of p-STAT3 was significantly increased in 100 μg/L IL-6 treatment group. Compared with 1 μmol/L brucine treatment alone, the expression of Bcl-2 was increased and the protein levels of p-STAT3, Bax and cleaved PARP were reduced in brucine and IL-6 combination treatment group (P < 0.05).CONCLUSION: Brucine may inhibit the activation of STAT3 phosphorylation in IL-6/STAT3 pathway to exert an antitumor effect on SW480 cells in vitro.     

Tongxinluo improves anti-hypoxia ability of vascular endothelial cells via PI-3K/Akt/HIF pathway

AIM: To investigate the effects of PI-3K/Akt/HIF pathway on anti-hypoxia ability of vascular endothelial cells influenced by Tongxinluo under hypoxic condition. METHODS: Human umbilical vein endothelial cells (HUVECs) were divided into the following groups: control group, Tongxinluo (100 mg/L) group, hypoxia group and hypoxia+Tongxinluo (100 mg/L) group. The CCK-8 assay were used to detect the viability and proliferation rate of the cells in each group. The protein levels of HIF-1α, Bcl-2, Mcl-1, Bax and phosphorylated Akt were studied by immunoblotting analysis. The HUVECs were transiently transfected with the dominant negative mutant of HIF-1α (DN-HIF). The apoptotic rates were analyzed by flow cytometry (FCM). The HUVECs were transiently transfected with the dominant negative mutant of PI-3K (Δp85) or Akt (DN-Akt) to investigate the role of PI-3K/Akt signal pathway in the anti-hypoxia ability of Tongxinluo on endothelial cells. RESULTS: Under hypoxic condition, although the proliferation rate increased significantly in Tongxinluo group compared with hypoxia group, the degree was notably weak compared with control group. The protein levels of HIF-1α, Bcl-2, Mcl-1 and phosphorylated Akt were up-regulated by Tongxinluo. Meanwhile, the expression of Bax was down-regulated. Inhibition of HIF-1α activation by DN-HIF and inhibition of the PI-3K/Akt pathway by Δp85 or DN-Akt attenuated the increase in HIF-1α expression and HUVEC viability induced by Tongxinluo. The percentage of apoptotic HUVECs was down-regulated to a certain extent by Tongxinluo. CONCLUSION: Tongxinluo improves the anti-hypoxia ability of vascular endothelial cells by up-regulating the protein level of HIF-1α, promoting the expression of anti-apoptotic factors, improving the cell viability and eventually reducing the apoptotic rate.These effects of Tongxinluo depend on PI-3K/Akt signal pathway.     

Injury pathways of hypoxia/reoxygenation in AC16 cardiomyocyte

AIM:To investigate the effects of hypoxia/reoxygenation (H/R) for different reoxygenation times on cardiomyocyte injury. METHODS:Human cardiomyocyte AC16 was cultured in glucose-free and serum-free DMEM with 1% O₂ for 24 h, 10% fetal bovine serum and low glucose DMEM combined with 21% O₂ were used to establish reoxygenation for 2 h, 6 h and 12 h, respectively. The cell viability was measured by CCK-8 assay. The protein levels of different cell injury pathway related molecules, such as LC3-Ⅱ/-I (autophagy), caspase-1 and gasdermin D (pyroptosis) and caspase-3 and Bax/Bcl2 (apoptosis), were determined by Western blot. RESULTS:Compared with blank control group, the cell viability in each H/R group was continuously decreased with the extension of reoxygenation time (P<0.05). The expression of LC3-Ⅱ/-I was up-regulated in hypoxia group and H/R group compared with blank control group (P<0.05). In addition, the protein levels of cleaved caspase-1 and cleaved gasdermin D were increased in H/R groups for 6 h and 12 h, respectively (P<0.05). Cleaved caspase-3 and Bax/Bcl2 were increased after reoxygenation for 12 h (P<0.05). CONCLUSION:Autophagy in hypoxia-induced AC16 cells is up-regulated, and then decreased by reoxygenation. The cell pyroptosis is activated earlier than the apoptosis during reoxygenation.     

Artesunate induces apoptosis of human hepatocellular carcinoma HepG2 cells by increasing generation of reactive oxygen species

AIM: To investigate the effect of reactive oxygen species (ROS) on the apoptosis of HepG2 cells induced by artesunate. METHODS: The effect of artesunate on the viability of HepG2 cells was measured by MTT assay. The morphological changes of the apoptotic cells were observed by the method of Hoechst 33258 fluorescence staining.The apoptosis of HepG2 cells was analyzed by flow cytometry. DCFH-DA was used to detect the changes of ROS generation during the process of apoptosis. The protein levels of Bax, Bcl-2, cleaved caspase-3 and cytochrome C (Cyt C) were determined by Western blot. HepG2 cells were pretreated with apocynin and then Western blot was used to detect the expression of p47^phox and p22^phox, and ROS changes were analyzed by flow cytometry. RESULTS: Compare with control group, the cell viability was obviously inhibited after treatment with artesunate for 24 h (P<0.05). The nuclei were densely stained, and the proportion of apoptotic cells was increased (P<0.05). ROS was increased significantly (P<0.05). The results of Western blot demonstrated that the expression level of Bax was increased, Bcl-2 was decreased, the ratio of Bax/Bcl-2 was increased, and the protein levels of cleaved caspase-3 and Cyt C were increased. Pretreatment with apocynin reduced the expression of p47^phox and p22^phox and the generation of ROS in the artesunate treatment group. CONCLUSION: Artesunate induces the apoptosis of HepG2 cells. The possible mechanism may be related to the increase in the generation of ROS.     

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.     

Effect of sulodexide on apoptosis of human dermal microvascular endothelial cells exposed to hypoxia

AIM: To investigate the effect of sulodexide (SDX) on the apoptosis of human dermal microvascular endothelial cells (HDMECs) exposed to hypoxia and its underlying mechanism. METHODS: The HDMECs were cultured and divided into normoxia control group cultured under normoxic condition; hypoxia control group cultured in a humid incubator maintained at 37℃ with 5% CO₂ and 1% O₂ for 24 h; treatment groups treated with SDX at 0.25, 0.5 and 1 LSU/mL for 24 h under hypoxic condition. The cell viability was measured by CCK-8 assay. The apoptotic rate of the HDMECs was analyzed by flow cytometry. The activity of caspase-3 in HDMECs was examined by caspase-3 activity assay kit. The expression of pro-apoptotic factor P53, caspase-3, Bax and anti-apoptotic factor Bcl-2 at mRNA and protein levels was determined by real-time PCR and Western blot. RESULTS: SDX increased the viability of HDMECs exposed to hypoxia, but also decreased the apoptosis. Furthermore, SDX down-regulated the expression of pro-apoptotic factor P53, Bax and caspase-3 at mRNA and protein levels as well as the activity of caspase-3, while the expression of anti-apoptotic factor Bcl-2 was up-regulated. CONCLUSION: SDX significantly increases the viability and decreases the apoptosis of HDMECs exposed to hypoxia. Inhibition of the mitochondrial apoptosis pathway may be involved in the underlying mechanism.     

Senescence of endothelial cells and gene expression associated with apoptosis induced by angiotensinⅡ

AIM: To study the senescence of human umbilical vein endothelial cells (HUVECs) and Bcl-2, Bax gene expression associated with apoptosis induced by angiotensinⅡ (AngⅡ).METHODS: HUVECs were cultured in vitro and the cell viability was observed by methyl thiazolyl tetrazolium (MTT). HUVECs were intervened by AngⅡ and valsartan (AngⅡ type 1 receptor blocking) and divided into 3 groups: the control group, AngⅡ group (stimulated with AngⅡ10^-6mol/L for 48 h), valsartan group (valsartan was added to cells 1 h before 10^-6mol/L AngⅡ treatment). β-gal staining and cell cycle analysis were used to identify the cell aging status. Morphologic changes and percentage of apoptosis were assayed with Hoechst33258 under fluorescent microscope. The expressions of Bcl-2 and Bax, and the apoptosis-associated genes were detected by immunocytochemical staining, RT-PCR and Western blotting. RESULTS: The cell viability by AngⅡ-induced cells was (81.9%±4.1)%, the positive cell number of β-gal staining was significantly higher in AngⅡ-induced cells (80.10%±6.81)% than that in the control cells. The cell cycle was at G₀-G₁(91.36%±6.45)%, the apoptotic cells significantly increased (31.84±2.86)% under fluorescent microscope. In valsartan group, Bcl-2 mRNA and protein expression increased markedly (P<0.05), but Bax mRNA and protein expression decreased evidently (P<0.05) compared to those in the AngⅡ group.CONCLUSION: Cell apoptosis is possibly an important factor for endothelial cell senescence and vascular aging induced by AngⅡ. One of its molecular mechanisms might be associated with decreasing the expression level of Bcl-2 and increasing that of Bax, which regulate the imbalance between mRNA and protein expression of Bcl-2 and Bax. Valsartan improves endothelial cell aging.     

Effects of platelet-rich plasma on chondrocyte apoptosis and NLRP3/IL-1β signaling pathway in rabbits with osteoarthritis

AIM To explore the effect of platelet-rich plasma (PRP) on rabbit osteoarthritis and its possible mechanism. METHODS The rabbits with knee osteoarthritis were prepared and then divided into model group, sodium hyaluronate (SH) group and PRP group, and another sham operation group was set up, with 6 rabbits in each group. The gross morphological changes of rabbit cartilage were observed. HE staining was used to evaluate the pathomorphological changes of the cartilage. TUNEL staining was used to detect the apoptosis of chondrocytes. The expression of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)/interleukin-1β （IL-1β） signaling pathway-related molecules was observed by immunohistochemical staining, and the protein levels of caspase-3, Bcl-2 and Bax were determined by Western blot. Chondrocytes were isolated and processed according to grouping, and the NLRP3 and IL-1β levels of the cells were measured by ELISA. RESULTS Compared with sham operation group, Pelletier score, Mankin score, chondrocyte apoptotic rate, the positive protein expression rates of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1 and IL-1β, and the protein levels of caspase-3 and Bax in model group were increased significantly (P<0.05), while the protein expression of Bcl-2 was decreased significantly (P<0.05). Compared with model group, Pelletier score, Mankin score, the apoptotic rate of chondrocytes, the positive protein expression rates of NLRP3, ASC, caspase-1 and IL-1β, and the protein levels of caspase-3 and Bax in SH group and PRP group were decreased significantly (P<0.05), while the protein expression of Bcl-2 was increased significantly (P<0.05). In PRP group, Pelletier score, Mankin score, the apoptotic rate of chondrocytes, the positive protein expression rates of NLRP3, ASC, caspase-1 and IL-1β, and the protein levels of caspase-3 and Bax were lower than those in SH group, while the protein expression of Bcl-2 was higher than that in SH group (P<0.05). Compared with control group, the expression of NL?RP3 and IL-1β in MCC950 (NLRP3 ihibitor) group were significantly reduced (P<0.05), the expression of NLRP3 in eucalyptol (IL-1β inhibitor) group was not significantly changed (P>0.05), and the expression of IL-1β was significantly reduced (P<0.05). CONCLUSION Platelet-rich plasma promotes the repair of cartilage in osteoarthritis rabbits, which has better effect than SH. The mechanism may be related to the inhibition of NLRP3/IL-1β pathway and the reduction of chondrocyte apoptosis.     

TPX2 induces apoptosis of rectal cancer HR-8348 cells through p38 MAPK signaling pathway

AIM: To study the effect of targeting protein for Xenopus kinesin-like protein 2 (TPX2) expression knockdown on the apoptosis of rectal cancer HR-8348 cells.METHODS: The HR-8348 cells transfected with TPX2 small interfering RNA (siRNA) served as TPX2 siRNA group. The non-transfected cells were used as control group. The cells transfected with siRNA negative control (siRNA-NC) were used as siRNA-NC group. The TPX2 siRNA-transfected cells exposed to p38 MAPK inhibitor SB203580 served as TPX2 siRNA+SB203580 group. The expression of TPX2 at mRNA and protein levels was determined by RT-qPCR and Western blot. The cell viability was measured by MTT assay, the apoptosis was analyzed by flow cytometry. The protein levels of p38 MAPK, p-p38 MAPK, cleaved caspase-3 and Bcl-2 in the HR-8348 cells were determined by Western blot.RESULTS: After transfection, the expression of TPX2 at mRNA and protein levels was decreased in TPX2 siRNA-transfected cells (P<0.05). Transfection with siRNA-NC had no effect on TPX2 mRNA and protein levels in the cells. After knockdown of TPX2 expression, the viability of rectal cancer HR-8348 cells and the expression of Bcl-2 were decreased, while the apoptotic rate and the protein levels of cleaved caspase-3 and p-p38 MAPK/p38 MAPK were increased significantly reduced (P<0.05). Compared with TPX2 siRNA group, the apopto-tic rate and the protein levels of cleaved caspase-3 and p-p38 MAPK/p38 MAPK in TPX2 siRNA+SB203580 group were significantly decreased, while the viability was significantly increased (P<0.05).CONCLUSION: Knockdown of TPX2 expression promotes apoptosis of rectal cancer HR-8348 cells by activating p38 MAPK signaling pathway.     

Effect of bim silencing by siRNA on hypoxia-induced apoptosis of rat cardiomyocytes

AIM：To investigate the effect of BH3-only protein Bim (Bcl-2 interacting mediator of cell death) on apoptosis of rat cardiomyocytes induced by hypoxia. METHODS：Rat cardiomyocytes were isolated from infant rats aged 1~3 days and then primarily cultured. The antibody targeting α-actin of striated muscle was used to identify the cardiomyocytes. The siRNAs of bim were transfected into the cardiomyocytes with liposome, and the expression of Bim was determined by Western blotting. The cardiomyocytes were divided into blank control group, hypoxia group, hypoxia+liposome group, hypoxia+negative control siRNA group and hypoxia+bim-siRNA group.The frequency and rhythm of cardiomyocyte beating were observed and recorded under inverted microscope. The activity of lactate dehydrogenase (LDH) in the culture medium was assessed by automatic biochemical analyzer. The viability of the cells was analyzed by MTT assay. The cell apoptotic rate was measured by flow cytometry. The protein expression of Bim, Bax, Bcl-2, p-p38 MAPK and p38 MAPK was detected by Western blotting. RESULTS：Immunohistochemical identification confirmed that the rat cardiomyocytes were successfully cultured. The expression of Bim was obviously inhibited after transfected with bim-siRNAs and the silencing efficiency of bim-siRNA-2 was the highest (86.73%). The frequency of cardiomyocyte beating was slowed down after hypoxia and the rhythm was disordered, while the frequency of beating was obviously increased after silencting the expression of bim. Compared with control group, the LDH in the culture medium was increased (P<0.01), and the viability of the cardiomyocytes was reduced in hypoxia group (P<0.05). The apoptotic rate was increased (P<0.01). After transfection with bim-siRNA, the release of LDH was decreased, and the viability of the cardiomyocytes was increased. The apoptotic rate was decreased. The results of Western blotting showed that hypoxia increased the expression of Bax and p-p38 MAPK (P<0.05), and decreased the expression of Bcl-2 (P<0.01), while transfection with bim-siRNA reduced the effects caused by hypoxia (P<005). These were greatly related to the decrease of apoptosis. However, the expression of p38 MAPK was not changed. CONCLUSION：The apoptosis of cardiomyocytes induced by hypoxia can be inhibited by silencing the expression of bim gene by down-regulation of p-p38 MAPK and Bax expression and up-regulation of Bcl-2 expression.     

Effect of KLF6 gene on apoptosis of THP-1 cell-derived macrophages

AIM: To investigate the effects of Kruppel-like factor 6 (KLF6) over-expression on the viability, apoptosis, reactive oxygen species (ROS) level and AKT signaling pathway of THP-1 cell-derived macrophages. METHODS: Human monocyte cell line THP-1 was induced to differentiate into macrophages by phorbol myristate acetate (PMA), and the macrophages were randomly divided into pcDNA3.1 group, oxidized low-density lipoprotein (ox-LDL) group, ox-LDL+pcDNA3.1 group and ox-LDL+pcDNA3.1-KLF6 group. pcDNA3.1 was transfected according to Lipofectamine^TM 2000 Kit. The cell viability, apoptotic rate and ROS level were detected by MTT assay, flow cytometry with Annexin V-FITC/PI double staining and H₂DCF-DA probing, respectively. The protein levels of Bcl-2, Bax and p-AKT were determined by Western blot. RESULTS: After pcDNA3.1-KLF6 was transfected into the macrophages, the expression of KLF6 was increased significantly (P<0.05). ox-LDL significantly inhibited the viability of the macrophages, induced apoptosis and ROS production, up-regulated the protein expression of Bax, and down-regulated the protein levels of Bcl-2 and p-AKT (P<0.05). Over-expression of KLF6 significantly reduced the effects of ox-LDL on cell viability, apoptosis, ROS level and the protein levels of Bcl-2, Bax and p-AKT (P<0.05). CONCLUSION: KLF6 significantly reduces the apoptosis of THP-1 cell-derived macrophages induced by ox-LDL, which may be related to the reduction of ROS level and activation of AKT signaling pathway.     

Effect of component II of broccoli polypeptide on glioma cell apoptosis

AIM：To explore the effect of component II of broccoli polypeptide on the apoptosis in glioma cells. METHODS：Human glioma SHG-44 cells were cultured and divided into control group and 3, 10, 30 and 100 mg/L component II of broccoli polypeptide groups. Cell viability was detected by MTT assay. The apoptotic rates were examined by Annexin V/PI staining. The morphological changes of the cells were observed under inverted microscope. The protein expression of Bax and Bcl-2 was detected by immunocytochemistry and Western blotting. The protein level of caspase-3 was also examined by Western blotting. RESULTS：Treatment with component II of broccoli polypeptide for 24 h, 48 h or 72 h induced significant inhibition of viability of SHG-44 cells in a time- and dose-dependent manner. The results of Annexin V/PI staining showed that the apoptotic rates were increased in treatment groups in a dose-dependent manner. The density of glioma cells was decreased after treated with increasing concentrations of the drug, and the apoptotic bodies were observed under inverted microscope at 72 h. The results of immunocytochemistry and Western blotting showed that the expression of Bax protein was increased but Bcl-2 protein expression was decreased, and the ratio of Bax/Bcl-2 was increased significantly compared with control group (P<0.05 or P<0.01). The level of caspase-3 protein was increased in 30 and 100 mg/L component II of broccoli polypeptide groups compared with control group (P<0.01). CONCLUSION：The component II of broccoli polypeptide increases the ratio of Bax/Bcl-2 and activates caspase-3 protein, thus inducing the apoptosis of glioma cells.