Effects of adenovirus-mediated shRNA targeting PTEN on proliferation and apoptosis of activated hepatic stellate cells in vitro

AIM:To investigate the down-regulation of phosphatase and tensin homolog deleted on chromosome 10(PTEN) gene by adenovirus-mediated short hairpin RNA(shRNA) on proliferation and apoptosis of activated hepatic stellate cells(HSCs) in vitro and the related signaling transduction pathways. METHODS:The activated HSCs were cultured in vitro and transfected with recombinant adenovirus expressing shRNA targeting PTEN. The proliferation of HSCs was measured by MTT assay and the apoptosis was assessed by TUNEL and flow cytometry. Western blotting was used to detect the protein levels of PTEN, Bax, Bcl-2, Akt, p-Akt, ERK1/2 and p-ERK1/2 in HSCs, and real-time fluorescent quantitative PCR was applied to detect the mRNA expression of Akt and ERK1. RESULTS:The recombinant adenovirus expressing shRNA targeting PTEN was successfully transfected into activated HSCs in vitro, and significantly promoted the proliferation of HSCs in a time-dependent manner within a certain extent. The apoptotic rate of HSCs was significantly decreased 72 h after transfection(P<0.05). Meanwhile, reduced expression of Bax and elevated expression of Bcl-2 were induced 72 h after transfection(P<0.05). Furthermore, the expression of p-Akt and p-ERK1/2 were increased significantly(P<0.05), while no significant difference in the expression of Akt and ERK1 at mRNA and protein levels was observed(P>0.05). CONCLUSION:Down-regulation of PTEN by adenovirus-mediated shRNA dramatically promotes the proliferation of activated HSCs, and inhibits the apoptosis through Bcl-2/Bax pathway. In addition, the phosphorylation of Akt and ERK1/2 is increased, indicating that PI3K/Akt and ERK1/2 signal transduction pathways may play an important role in the regulation of proliferation and apoptosis of HSCs.     

Expression of Akt and ERK1/2 in human osteoarthritic chondrocytes

AIM: To investigate the expression of protein kinase B (Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) in normal and osteoarthritic chondrocytes. METHODS: The samples of knee cartilage were obtained from the normal donors (n=5) and the patients (n=18) undergoing total knee arthroplasty with the diagnosis of osteoarthritis (OA). The expression of p-Akt and p- ERK1/2 in the normal and osteoarthritic cartilage tissues was detected by the method of immunohistochemistry. The chondrocytes were isolated and identified by toluidine blue staining and immunohistochemical method. The expression levels of Akt, p-Akt, ERK1/2,p-ERK1/2,phosphorylated 70-kD ribosomal protein S6 kinase(p-p70S6K) and proliferating cell nuclear antigen(PCNA) were tested in normal and osteoarthritic chondrocytes by Western blotting. Real-time fluorescence quantitative PCR was used to measured the expression levels of aggrecan and type II collagen gene in normal and osteoarthritic chondrocytes. RESULTS: The expression of p-Akt in normal cartilage was higher than that in OA cartilage. The expression of p- ERK1/2 in OA cartilage was higher than that in normal cartilage. Compared with the normal chondrocytes, the expression of p-Akt and p-p70S6K, and the mRNA levels of aggrecan and type II collagen were increased (P<0.05), and the expression of p-ERK1/2 and PCNA was decreased in OA chondrocytes (P<0.05). CONCLUSION: Akt might regulate aggrecan and type II collagen synthesis via p-p70S6K, and ERK1/2 might regulate OA chondrocyte proliferation through PCNA. Both Akt and ERK1/2 play important roles in the pathogenesis of OA.     

Effects of bradykinin on proliferation of porcine pulmonary artery smooth muscle cells induced by TGF-β1

AIM: To investigate the effects of bradykinin (BK) on the proliferation of pulmonary artery smooth muscle cells (PASMCs) induced by transforming growth factor beta 1 (TGF-β1) and its possible mechanisms. METHODS: Primary porcine PASMCs were isolated, cultured and identified, and the cells at passages 2~6 were used in this study. The viability of PASMCs was determined by Cell Counting Kit-8 assay. The protein expression of phosphatidylinositol 3-kinase (PI3K), phosphorylated Akt (p-Akt) and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) was detected by Western blotting. RESULTS: TGF-β1 promoted the proliferation of PASMCs in a dose-dependent manner (P<005). BK significantly inhibited the proliferation of PASMCs induced by TGF-β1 (P<005), and attenuated the elevated expression of PI3K, p-Akt and p-ERK1/2 proteins (P<005). HOE-140, a BK type 2 receptor (B2R) inhibitor, reversed the effects of BK (P<005). CONCLUSION: BK inhibits TGF-β1-induced proliferation of PASMCs, which may be associated with inactivation of PI3K/Akt and ERK1/2 signaling pathways.     

Role of Mfn2 in mediating trichostatin A-induced growth arrest in HeLa cells

AIM: To investigate the roles of mitofusin 2 (Mfn2) in mediating trichostatin A (TSA)-induced growth arrest and the underlying mechanism. METHODS: After treating with different doses of TSA or over-expression of Mfn2, the proliferation, apoptosis and cell cycle of HeLa cells were analyzed. The protein levels of Ras, p-Raf, Raf, p-ERK, ERK, p-Akt, Akt and Mfn2 were determined by Western blot. The mRNA expression of Mfn2 was detected by real-time PCR. The interaction between Mfn2 and Ras was probed by co-immunoprecipitation. RESULTS: TSA inhibited cell proliferation by inducing apoptosis and a cell-cycle arrest at G₂/M phase in a dose and time dependent manner in the HeLa cells. TSA induced up-regulation of Mfn2 at mRNA and protein levels, improved interaction between Mfn2 and Ras and decreased the phosphorylation levels of Raf and ERK. However, Mfn2 over-expression hardly caused cell apoptosis, yet it resulted in severe growth arrest by inhibiting Ras-Raf-ERK pathway in the HeLa cells. CONCLUSION: TSA might trigger HeLa cell arrest by increasing Mfn2 expression and thus inhibiting the activity of Ras-Raf-ERK pathway.     

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.     

Cordycepin inhibits proliferation and migration of gallbladder cancer cell SNU-308 by ERK1/2, Ezrin and Akt signaling pathways

AIM: To investigate the effects of cordycepin on the proliferation and migration abilities of gallbladder cancer cell line SNU-308 and its molecular mechanism. METHODS: The viability of SNU-308 cells treated with cordycepin at different concentrations was measured by MTT assay and the colony formation ability was also detected. The effect of cordycepin on apoptosis was analyzed by flow cytometry with Annexin V/PI double staining. The protein levels of apoptosis and autophagy markers, and the phosphorylation level of Akt, ERK1/2 and Ezrin were evaluated by Western blot. Immunofluorescence staining was also used to analyze the expression level of LC3 after cordycepin treatment. Wound healing assay and Transwell assay were performed to evaluate the migration ability of the SNU-308 cells after cordycepin treatment. Wound healing assay was also used to evaluate the effects of Akt inhibitor, ERK1/2 inhibitor and Ezrin knockdown on the changes of migration ability. RESULTS: Cordycepin significantly inhibited the viability and the ability of colony formation of gallbladder cancer cells (P<0.05). Induction of apoptosis by cordycepin were revealed by flow cytometry (P<0.05). The protein expression of Bcl-2 was down-regulated, while the protein levels of Bax, cytochrome C (Cyto C), Fas, FasL and cleaved caspase-3 were increased and the autophagy marker beclin 1 and the ratio of LC3-Ⅱ/I were upregulated by Western blot analysis (P<0.05). LC3 accumulation in the cytoplasm after cordycepin treatment was demonstrated by immunofluorescence staining. Cordycepin treatment resulted in the inhibition of cell migration were detected by Transwell assay and wound healing assay (P<0.05). The protein levels of p-Akt, p-ERK1/2 and p-Ezrin were down-regulated after cordycepin treatment (P<0.05). Besides, Ezrin knockdown, Akti-1/2 and GDC-0994 all resulted in the inhibition of migration ability (P<0.05). CONCLUSION: Cordycepin induces apoptosis and autophagy to inhibit gallbladder can-cer cell proliferation and migration by regulating ERK1/2, Ezrin and Akt signaling pathways.     

Metoprolol inhibits norepinephrine-induced rat cardiomyocyte apoptosis and connexin 43 phosphorylation

AIM: To study the effects of metoprolol (Meto) on the apoptosis of neonatal rat cardiomyocytes and the phosphorylation of connexin 43 (Cx43) induced by norepinephrine (NE). METHODS: Neonatal SD rat cardiomyocytes were divided into the following five groups (n=6 in each group): (1) control (Con) group: no treatment; (2) NE group: treatment with NE at 0.1 μmol/L for 24 h; (3) NE+Meto group: simultaneous treatment with NE and Meto both at 01 μmol/L for 24 h; (4) NE+Meto+PD98059 group: pretreatment with extracellular signal-regulated kinase (ERK) phosphorylation inhibitor PD98059 at 10 μmol/L for 30 min and then treatment with NE and Meto both at 01 μmol/L for 24 h; (5) NE+PD98059 group: pretreatment with PD98059 at 10 μmol/L for 30 min and then treatment with NE at 01 μmol/L for 24 h. The beating rates of cardiomyocytes in various groups were calculated, and the viability of cardiomyocytes was assayed by MTT method. The Cx43 mRNA expression was detected by RT-PCR, and the protein expression of phosphorylated Cx43 (p-Cx43), phosphorylated ERK1/2 (p-ERK1/2) and cleaved caspase-3 was detected by Western blotting. RESULTS: (1) Separate NE treatment could significantly increased the beating rate of cardiomyocytes and reduced cell viability, while Meto showed the opposite effects. PD98059 treatment had no significant effect on cardiomyocyte beating rate, but suppressed Meto to improve cell viability to some extent. (2) Compared with Con group, separate NE treatment significantly increased the Cx43 mRNA expression (P<001). Compared with NE group, Meto or PD98059 intervention could significantly inhibited Cx43 mRNA expression (both P<001), and simultaneous treatment with Meto and PD98059 could further suppress Cx43 mRNA expression up-regulated by NE (P<001). (3) Compared with NE group, Meto significantly inhibited the increased p-Cx43, p-ERK1/2 and cleaved caspase-3 expression induced by NE (P<001), and simultaneous treatment with Meto and PD98059 could further enhance the inhibition of p-Cx43, p-ERK1/2 and cleaved caspase-3 expression by Meto (P<001). PD98059 treatment had no significant effect on the increased p-Cx43 and cleaved caspase-3 expression induced by NE (P>005). CONCLUSION: The inhibitory effect of Meto on NE-induced cardiomyocyte apoptosis is related to the inhibition of Cx43 phosphorylation, which may be partly mediated via ERK1/2 pathway.     

Role of ghrelin in cell protection by up-regulating HSP70 through ERK1/2 signaling pathway in PC12 cells

AIM:To study the role of ghrelin in cell protection by up-regulating heat shock protein 70 (HSP70) and inhibiting apoptosis induced by oxidative stress through extracellular regulated protein kinases 1/2 (ERK1/2) signaling pathway in the PC12 cells. METHODS:Sodium nitoprusside (SNP) was used to induce oxidative stress injury in the PC12 cells. The cultured PC12 cells were divided into SNP-injured group (incubated with SNP at 0.5 mmol/L for 6, 12, 18 and 24 h), ghrelin pretreatment group (ghrelin at 100 nmol/L was given 30 min before adding SNP); HSP70 inhibitor group (quercetin at 10 μmol/L was added 60 min before ghrelin treatment), ERK inhibitor group (ERK 1/2 inhibitor PD98059 was added 60 min before ghrelin treatment) and control group (added same amount of culture medium only). The apoptotic rate was detected by flow cytometry. The protein expression was determined by Western blot and immunocytochemistry. RESULTS:Compared with control group, the apoptotic rate of PC12 cells in SNP-injured group was significantly increased (P<0.05). Compared with SNP-injured group, ghrelin (100 nmol/L) pretreatment significantly inhibited SNP-induced apoptosis of PC12 cells (P<0.05), and significantly up-regulated the protein expression of HSP70 (P<0.05). Time-effect analysis showed that ghrelin had the most significant effect at 18 h after SNP injury. Quercetin, an inhibitor of HSP 70, significantly reduced the anti-apoptotic effect of ghrelin (P<0.05). Ghrelin pretreatment promoted the phosphorylation of ERK1/2. ERK1/2 inhibitor PD98059 significantly inhibited the effects of ghrelin on up-regulation of HSP70 expression (P<0.05). CONCLUSION:Ghrelin upregulates the expression of HSP70 and inhibits the apoptosis in the PC12 cells induced by oxidative stress by promoting the phosphorylation of ERK1/2.     

Effect of growth arrest-specific protein 6 on H9c2 cell apoptosis induced by anoxia-reoxygenation via PI3K/Akt survival pathway

AIM: To investigate the effect of growth arrest-specific protein 6(Gas 6) on H9c2 cell apoptosis induced by anoxia-reoxygenation (A/R) and its possible relationship with PI3K/Akt pathway. METHODS: Cultured H9c2 cell line of cardiomyocytes was randomly divided into 4 groups: normal control group, anoxia-reoxygenation group (A/R), anoxia-reoxygenation+Gas6 group (A/R+Gas6) and anoxia/reoxygenation+Gas6+LY294002 group (A/R+Gas6+LY294002). The procedure of A/R was performed in cultured H9c2 cells by 3 h of anoxia and then 3 h of reoxygenation. The viability of the cells and the activity of caspase-3 were detected by automatic biochemistry analytic instrument. Cell apoptotic rates were evaluated by flow cytometry. The protein level of phosphorylated Akt(p-Akt) was determined by Western blotting. RESULTS: Compared with control group, the cell viability was significantly decreased, and caspase-3 activity, cell apoptotic rate and the protein level of p-Akt were increased in A/R group. Compared with A/R group, the caspase-3 activity and cell apoptotic rate reduced markedly, while the cell viability and the protein level of p-Akt were significantly increased in A/R+Gas6 group .The effect of Gas6 was inhibited by LY294002. CONCLUSION: Gas6 may protect the H9c2 cells from anoxia-reoxygenation-induced apoptosis. Its mechanism is possibly involved in the activation of PI3K/Akt survival pathway via increasing the phosphorylation of Akt protein.     

Role of Gab2 in mouse myeloid abnormal proliferation induced by SHP-2D61G/+ mutation

AIM: To investigate whether Gab2, the key adapter protein in the SHP-2 signaling pathway, is involved in mouse myeloid abnormal proliferation induced by SHP-2D61G/+ mutation.METHODS: Four kinds of mouse model genotyped as SHP-2+/+, Gab2-/-, SHP-2D61G/+ and SHP-2D61G/+/Gab2-/- were generated from crossbreeding of Gab2-/- mice and SHP-2D61G/+ mice. The mouse spleen size was analyzed. The number of peripheral blood leukocytes was counted by cell counting and the percentage of Mac-1 or Gr-1 positive myeloid cells in the bone marrow was detected by flow cytometry. The proliferation ability of bone marrow hematopoietic stem/progenitor cells in response to cytokines was assayed by colony formation. The expression of p-ERK and p-Akt and the binding capacity of SHP-2 with Gab2 in the bone marrow-derived mast cells stimulated with IL-3 were detected by Western blotting and immunoprecipitation.RESULTS: The phenotype of myeloproliferative disorder, such as enlarged spleen size, increased leukocyte number and high percentage of myeloid cells, in SHP-2D61G/+ mutant mice was found, and was dramatically improved in SHP-2D61G/+/Gab2-/- double mutation mice. Furthermore, compared with SHP-2D61G/+ mutation mice, significantly decreased colony formation ability of the bone marrow cells with IL-3 stimulation was observed in SHP-2D61G/+/Gab2-/- double mutation mice. A reduced phosphorylation level of ERK/Akt, and SHP-2 without binding of Gab2 were found in SHP-2D61G/+/Gab2-/- bone marrow-derived mast cells with IL-3 stimulation.CONCLUSION: Gab2 knockout significantly reduces mouse myeloid abnormal proliferation induced by SHP-2D61G/+ mutation. The molecular mechanism may be associated with reduced binding of SHP-2D61G/+ under Gab2 knockout, and further weakened the activation of downstream signaling pathways of ERK and Akt.     

Effect of gonadotropin-releasing hormone analogue on human breast cancer cell line in vitro

AIM: To investigate the effects of gonadotropin-releasing hormone (GnRH) analogue on the growth of breast cancer cell lines MCF-7 and MDA-MB-231 in vitro and to explore the related mechanisms with PI3K/Akt or ERK/MAPK pathways. METHODS: The proliferation of human breast cancer cell lines MCF-7 and MDA-MB-231 treatment with triptorelin was detected by MTT assay and the distribution of the cell cycle was determined by flow cytometry. The phosphorylation of the ERK1/2 and Akt was evaluated by Western blotting. RESULTS: Triptorelin inhibited the proliferation of MCF-7 cells at concentration of 10^-5 mol/L after treated for 192 h or at concentration of 10^-4 mol/L after treated for 168 h and 192 h. Triptorelin inhibited the proliferation of MDA-MB-231 cells at concentration of 10^-4 mol/L after treated for 192 h (P<0.05).Treatment with triptorelin for 192 h at concentration of 10^-4 mol/L had no statistical significance effect on phosphorylation of ERK1/2 and Akt(P>0.05).CONCLUSION: Inhibitory effect of GnRH analogue triptorelin on human breast cancer cells is not just the connection with the down-regulation of pituitary hormone, but also a direct inhibitory effect. The role may not be involved in the activation of ERK/MAPK and PI3K/Akt signaling pathways.     

NAC-1 -specific siRNA enhances paelitaxel-induced apoptosis of ovarian cancer cell line HO8910

AIM: To observe the effect of NAC-1 -specific siRNA alone, or in combination with paelitaxel on proliferation and apoptosis of human ovarian cancer cell line HO8910. METHODS: Ovarian cancer cells were treated with NAC-1 siRNA alone or in combination with paelitaxel. The level of NAC-1 mRNA was assessed by real-time quantitative PCR. Western blotting analysis was used to detect NAC-1 protein and the activation of epidermal growth factor receptor(EGFR) downstream signals,Akt and ERK. The cell proliferation rate was measured by MTT assay, and the cell cycle and apoptosis were determined by flow cytometry. RESULTS: After treated with NAC-1 -specific siRNA for 48 h, the expression of NAC-1 at mRNA and protein levels in HO8910 cells decreased by 71.1% and 80.5%, respectively. The cells in G₁ phase increased. The protein levels of p-Akt and p-ERK were decreased by 43.7% and 49.8%, respectively. After treated with NAC-1 -specific siRNA for 72 h, the proliferation inhibitory rate of the cells was increased to 45.6% as compared with the cells treated with negative siRNA. Apoptotic rate of the cells treated with NAC-1 siRNA (0.5 μmol/L combined with 2 μmol/L of paelitaxel) for 72 h was (30.93±4.57)%,higher than that of the cells treated with paelitaxel alone[(23.85±3.65)%]. CONCLUSION: NAC-1 siRNA suppresses NAC-1 gene expression and EGFR downstream signaling activation, inhibits cell proliferation and enhances the responsiveness of ovarian cancer cells to paelitaxel. The combination treatment produces synergistic inhibition.     

PGRN gene silencing on proliferation and migration abilities of human non-small-cell lung cancer A549 cells

AIM: To investigate the effect of small interfering RNA (siRNA)-mediated progranulin (PGRN) gene silencing on the proliferation and migration abilities of human non-small-cell lung cancer A549 cells and its mechanism. METHODS: The mRNA and protein expression levels of PGRN in the A549 cells and human bronchial epithelial (HBE) cells were detected by qPCR and Western blot. A549 cells were transfected with PGRN-siRNA by liposome method. The expression of PGRN at mRNA and protein levels in the A549 cells transfected with PGRN-siRNA was detected by qPCR and Western blot, respectively. The cell viability was measured by MTT assay. The cell proliferation ability was measured by living cells counting and crystal violet staining assays. The cell migration ability was measured by wound-healing and Transwell assays. The protein levels of proliferating cell nuclear antigen (PCNA), cyclin D1, Bcl-2 and Bax were determined by Western blot. The protein levels of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) and phosphorylated protein kinase B (p-Akt) were also determined by Western blot. RESULTS: The expression of PGRN at mRNA and protein levels was higher in the A549 cells than that in the HBE cells (P<0.05). The expression of PGRN at mRNA and protein levels in the A549 cells transfected with PGRN-siRNA was significantly decreased, and the cell proliferation and migration abilities were significantly decreased. The protein expression levels of PCNA, cyclin D1 and Bcl-2 were significantly reduced and the protein expression level of Bax was significantly increased (P<0.05). Meanwhile, the protein levels of p-ERK1/2 and p-Akt were down-regulated (P<0.05). CONCLUSION: PGRN gene silencing obviously inhibits the proliferation and migration abilities of human non-small-cell lung cancer A549 cells. The PI3K/Akt and MAPK/ERK signaling pathways may play an important role in these processes.     

PI3K/Akt signaling pathway regulates autophagy induced by acute kidney injury in septic rats

AIM：To investigate the autophagy induced by sepsis and acute kidney injury, and the regulation of phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway in this process. METHODS：The rats were subjected to cecal ligation and puncture (CLP) or sham operation. Histopathologic changes of the renal tissues were examined by HE staining. Blood urea nitrogen (BUN) and serum creatinine (SCr) were measured by chemical colorimetry. The protein expression of microtubule-associated protein light chain 3 I/II (LC3 I/II), beclin-1 and p-Akt at different time points after CLP was detected by Western blotting. In vitro, human proximal tubular epithelial cell line HK-2 were treated with LPS to induce autophagy. The protein expression of LC3 I/II and p-Akt in the HK-2 cells after LPS treatment at different time points and different concentrations was detected by Western blotting. These molecules in HK-2 cells and apoptosis of HK-2 cells treated with LPS plus PI3K inhibitor or Akt inhibitor were also detected. RESULTS：Compared with sham group, the severe changes of renal histopathological injuries in CLP groups were observed, the levels of BUN and SCr in CLP groups were significantly increased. LC3 I/II, beclin-1 and phosphorylation of Akt gradually increased after CLP. After treatment with LPS, the expression of p-Akt (308) in the HK-2 cells gradually increased in a dose- and time-dependent fashion. The expression of beclin-1 and p-Akt (472) reached a peak at 8 h or 10 mg/L LPS treatment. Treatment with PI3K or Akt inhibitor down-regulated the expression of LC3 and promoted the apoptosis of HK-2 cells. CONCLUSION：Autophagy in the kidney is induced by sepsis and acute kidney injury. PI3/Akt signaling pathway may be involved in this process.     

Minocycline suppresses sodium nitroprusside-induced apoptosis in PC12 cells by regulating PI3K/Akt signaling

AIM：To explore the role of PI3K/Akt signaling in the anti-apoptotic effect of minocyline (MC) on the apoptosis of PC12 cells induced by sodium nitroprusside (SNP). METHODS：PC12 cells were divided into 4 groups: blank control group, SNP (500 μmol/L) group, MC (10 μmol/L)+SNP group and LY294002+MC+SNP group. The cell viability was observed by MTT assay. The expression of Akt and p-Akt was determined by Western blotting. RESULTS： The viability of the PC12 cells decreased after exposed to 500 μmol/L SNP for 24 h. Meanwhile, MC at concentration of 10 μmol/L significantly blocked the effect of SNP, such as decreasing the cell viability. Pretreatment with LY294002 for 60 min prior to exposure of the PC12 cells to MC and SNP down-regulated the expression of p-Akt induced by SNP. CONCLUSION：Minocycline regulates PI3K/Akt signaling pathway to restrain the apoptosis of PC12 cells induced by SNP.     

SHP-2 regulates PC12 cell survival and apoptosis in response to NGF via activation of ERK and JNK

AIM: To investigate the central role of the protein tyrosine phosphatase SHP-2 in the survival of PC12 cells upon NGF treatment and apoptosis after NGF withdrawal. METHODS: PC12 cells were treated with SHP-2 inhibitor (NSC87877). Cell survival rate was detected by MTT method and apoptosis was determined by flow cytometry. Moreover, pIRES-GFP (vector alone), pIRES-GFP-SHP-2 (wild type) and pIRES-GFP-SHP-2C459S (dominant negative mutant form) were transfected into PC12 cells. ERK, p-ERK, JNK and p-JNK were immunoblotted at 1 h in the presence of NGF and 5 h after NGF withdrawal. RESULTS: SHP-2 potentially enhanced survival and attenuated apoptosis of PC12 cells. The activation of ERK was significantly enhanced with NGF treatment either in the group without SHP-2 inhibitor or the SHP-2 wild type group. On the other hand, phosphorylation level of JNK was significantly increased after NGF withdrawal when PC12 cells were treated with SHP-2 inhibitor or transfected with SHP-2 mutant. CONCLUSION: SHP-2 may play a central role in mediating the survival and apoptosis of PC12 cells upon NGF exposure and withdrawal. The underlying mechanisms may be through the activation of ERK and JNK.     

ROCK promotes high glucose-induced cardiomyocyte apoptosis by inhi-biting PI3K/Akt signaling pathway

AIMTo investigate whether Rho-associated coiled-coil kinase (ROCK) is involved in high glucose-induced apoptosis of primary cardiomyocytes by regulating PI3K/Akt signaling pathway. METHODSPrimary Wistar rat cardiomyocytes were cultured and identified by α-sarcomeric actin (α-SCA) immunohistochemistry. Cardiomyocytes were treated with 5.5, 33 and 40 mmol/L glucose for 48 h. The cell viability was measured by MTT assay, and the mRNA expression of ROCK1 and ROCK2 in the cardiomyocytes was detected by RT-qPCR. Flow cytometry was used to analyze the apoptosis of the cardiomyocytes. The protein levels of ROCK1, ROCK2, cleaved caspase-3, Bcl-2, PI3K, Akt and p-Akt were determined by Western blot. In order to confirm the regulatory effect of ROCKs on PI3K/Akt signaling pathway, the cells were divided into control group (5.5 mmol/L glucose), high glucose group (33 mmol/L glucose) and high glucose+Y27632 (ROCK inhibitor) group. Western blot was used to detect the protein levels of ROCK1, ROCK2, PI3K, Akt and p-Akt. RESULTSAfter 48 h of high glucose exposure, the values of relative cell viability in 33 and 40 mmol/L glucose groups were (79.71±2.43)% and (68.41±7.49)%, respectively, both of which were significantly decreased compared with normal control group (P<0.05). After 48 h of high glucose exposure, the relative mRNA levels of ROCK1 and ROCK2 in 33 and 40 mmol/L glucose groups were significantly increased compared with normal control group (P<0.05). Compared with normal control group, the apoptotic rate in 33 and 40 mmol/L glucose groups was increased significantly (P<0.05). Compared with normal control group, the protein expression of ROCK1, ROCK2 and cleaved caspase-3 in 33 and 40 mmol/L glucose groups was increased (P<0.05), while the protein expression of Bcl-2 was decreased (P<0.05). No significant difference in the protein levels of PI3K and Akt among the 3 groups was observed, while the protein level of p-Akt in 33 and 40 mmol/L glucose groups was decreased compared with normal control group (P<0.05). Compared with high glucose group, the expression of ROCK1 and ROCK2 was decreased in high glucose+Y27632 group. No significant difference in the protein levels of PI3K and Akt among the 3 groups was observed. Compared with normal control group, the protein level of p-Akt in high glucose group was decreased, and the protein level of p-Akt in high glucose+Y27632 group was increased significantly compared with high glucose group. CONCLUSION Under high glucose environment, ROCK may reduce the level of p-Akt by inhibiting the PI3K/Akt signaling pathway， thus promoting the apoptosis of cardiomyocytes.     

Expression of genes in MAPKs pathway in development of neural tube defects induced by hyperthermia

AIM: To study the expression and the role of ERK1/2 and JNK1/2 of MAPKs pathways in the development of neural tube defects induced by hyperthermia. METHODS: The animal models of golden hamster were produced by hyperthermia. The expression of ERK1/2 and JNK1/2, and levels of their phosphorylation were measured by Western blotting in control group and hyperthermia group. RESULTS: p-ERK1/2 steadily expressed in each control group, and the expression of p-ERK1/2 significantly decreased, which was different from that in the corresponding control group (P<0.05). The activity of p-JNK1/2 increased in hyperthermia group and the amount of p-JNK1/2 increased as compared to control group. The peak appeared at 16 h after exposed to hyperthermia (P<0.05). CONCLUSION: Hyperthermia, which induces a decrease in p-ERK1/2 expression and increases the expression of p-JNK1/2 of MAPKs pathway, results in the unbalance of cell proliferation and apoptosis, and induces neural tube defects.