Overexpression of neuroglobin attenuates Aβ-induced apoptosis in brains of double transgenic AD mice

AIM: To observe the effects of neuroglobin(NGB) overexpression on the apoptosis induced by Aβ in the brains of double transgenic AD(APPswe/PS1dE9) mice and to explore its potential mechanisms.METHODS: Twenty-four 13-month-old double transgenic AD mice were randomly divided into 3 groups:intracerebroventricular injection with normal saline(NS) group, intracerebroventricular injection with pcDNA3.1 and NS group, and intracerebroventricular injection with pcDNA3.1 and pNGB group. Immunohistochemistry was used to detect the expression of Aβ_1-42 in the brains. TUNEL staining was used for analyzing the apoptosis, and the protein levels of cleaved caspase-3, caspase-9, PI3K, Akt and p-Akt were determined by Western blot.RESULTS: After intracerebroventricular injection with pNGB, the areas of Aβ_1-42 in the hippocampus and cortex were decreased compared with NS group and pcDNA3.1+NS group(P<0.01). The TUNEL-positive staining cells in the pNGB group were less than those in NS group and pcDNA3.1 group(P<0.01). NGB overexpression attenuated the protein levels of cleaved caspase-3 and caspase-9(P<0.01), but induced the production of PI3K and p-Akt(P<0.01).CONCLUSION: Overexpression of pNGB significantly inhibits the generation of Aβ and attenuates the apoptosis induced by Aβ, indicating that NGB overexpression activates PI3K/Akt pathway and inhibits the production of cleaved caspase-3 and caspase-9, which were tightly related with apoptosis.     

Effect of autophagy in SH-SY5Y cells injured by Aβ25-35

AIM: To explore whether the damage of neurons induced by amyloid β-protein (Aβ) is related to the regulation of autophagy and its mechanism based on Akt/mTOR pathway. METHODS: SH-SY5Y cells were incubated with Aβ_25-35 (5 μmol/L, 10 μmol/L, 15 μmol/L, 20 μmol/L and 25 μmol/L) for 24 h, and the cell viability was measured by MTT assay. The protein levels of LC3-I, LC3-II, Akt, p-Akt, mTOR and p-mTOR in the SH-SY5Y cells were determined by Western blot. After the SH-5Y5Y cells were incubated with autophagy inducer rapamycin (Rapa) or autophagy inhibitor 3-methyladenine (3-MA) combined with Aβ_25-35 for 24 h, the cell viability and related protein expression were detected by the same methods above mentioned. RESULTS: Each concentration of Aβ_25-35 damaged SH-SY5Y cells and decreased the viability of SH-SY5Y cells. Aβ_25-35 increased the expression of autophagy marker protein LC3-II, increased the level of LC3-II/LC3-I, and down-regulated the phosphorylation level of Akt and mTOR proteins (P<0.05). When combined with autophagy inducer Rapa, the cell viability was not significantly affected, the expression of LC3-II protein was increased, LC3-II/LC3-I was increased significantly, and p-mTOR/mTOR level was decreased (P<0.05). When combined with autophagy inhibitor 3-MA, the protein expression of LC3-II and the level of LC3-II/LC3-I showed a downward trend, while the level of p-Akt/Akt was decreased (P<0.05). CONCLUSION: Aβ_25-35 may induce SH-SY5Y cell autophagy and injury by down-regulating phosphorylation levels of Akt and mTOR proteins.     

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.     

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.     

Shikonin induces apoptosis and autophagy of human cervical cancer HeLa cells by PI3K/Akt/mTOR signaling pathway

AIM:To observe the effects of shikonin on the apoptosis and autophagy of human cervical cancer HeLa cells, and to explore the possible role of PI3K/Akt/mTOR signaling pathway in these processes. METHODS:The HeLa cells were treated with shikonin, and the cell viability was detected by CCK-8 assay. The apoptosis was detected by Annexin V/PI double staining. The autophagosome was observed by transfection with GFP-LC3 into the HeLa cells. After the treatment with shikonin combined with autophagy inhibitor 3-methyladenine (3-MA) or apoptosis inhibitor Z-DEVD-FMK, the protein levels of autophagy-and apoptosis-related molecules microtuble-associated protein 1 light chain 3 (LC3) and cleaved caspase-3 in the HeLa cells were determined by Western blot. The protein levels of phosphorylated PI3K (p-PI3K), phosphorylated Akt (p-Akt) and phosphorylated mTOR (p-mTOR) were also determined by Western blot. RESULTS:Shikonin significantly inhibited the viability of HeLa cells (P<0.05). Compared with control group, shikonin significantly induced apoptosis of HeLa cells (P<0.05). The results of GFP-LC3 plasmid transfection analysis showed that green dot-like congregate autophagosomes appeared in the cytoplasm of the HeLa cells after shikonin treatment, while the autophagosomes were rarely observed in control group. Compared with shikonin group, LC3-Ⅱ/LC3-I was significantly decreased and cleaved caspase-3 was significantly increased in shikonin+3-MA group (P<0.05). Compared with shikonin group, LC3-Ⅱ/LC3-I was significantly increased and cleaved caspase-3 was significantly decreased in shikonin+Z-DEVD-FMK group (P<0.05). Compared with control group, shikonin significantly decreased the protein levels of p-PI3K, p-Akt and p-mTOR (P<0.05). CONCLUSION:The apoptosis and autophagy of the HeLa cells are induced by shikonin, these two processes are complementary. The mechanism may be related to inhibition of PI3K/Akt/mTOR signaling pathway.     

Over-expression of Hsp75 in neural stem cells reduced Aβ-mediated neurotoxicity

AIM: To investigate the effect of heat shock protein 75 (Hsp75) over-expression on Aβ-induced neurotoxicity in the neural stem cells and to explore its mechanism. METHODS: An adenovirus-mediated Hsp75 over-expression vector was used in vitro. The mouse neural stem cell C17.2 was cultured in vitro and divided into control group, Aβ group, negative adenovirus vector transfection group and Hsp75 over-expression adenovirus vector transfection group. The transfection and cellular immune identification were detected by fluorescence microscopy. The cell morphology was observed under inverted phase-contrast microscope. The cell viability and apoptosis were detected by MTT assay and flow cytometry, respectively. Hsp75 over-expression and cleaved caspase-3 protein level were measured by Western blot. RESULTS: Observation by fluorescence microscopy indicated that C17.2 cells were successfully transfected and Hsp75 gene was effectively expressed in the neural stem cells after transfection. In addition, the morphology and viability of the cells did not change and these cells did not differentiate after transfection. As compared with control group, the cell viability in Aβ group and negative adenovirus vector transfection group was significantly decreased (P < 0.05), and the cell apoptotic rate and cleaved caspase-3 level (P < 0.05) were increased. As compared with Aβ group and negative adenovirus vector transfection group, Hsp75 over-expression significantly increased the cell viability, and decreased the cell apoptosis and cleaved caspase-3 level (P < 0.05). CONCLUSION: Hsp75 over-expression protects the neural stem cells against Aβ-induced injury. The mechanism may be related to inhibiting caspase-3 pathway-dependent apoptosis.     

Protective effect of osthole on SH-SY5Y cells transfected with APP595/596 gene

AIM: To explore the protective effect of osthole on the SH-SY5Y cells transfected with APP595/596 gene, and to investigate the molecular mechanism. METHODS: The SH-SY5Y cells were transfected with APP595/596 gene in vitro for establishing a cell model to study the pathogenic role of amyloid β-protein (Aβ). The cell viability was detected by CCK-8 assay. The release of lactate dehydrogenase (LDH) was determined by the colour reaction of diaphorase-INT. The cell apoptotic rate was analyzed by flow cytometry. The expression of β-site APP cleaving enzyme 1(BACE1) at mRNA and protein levels was detected by RT-PCR and Western blot. The expression of Aβ was measured by the technique of immunofluorescence cytochemistry and Western blot. RESULTS: Treatment with osthole inhibited the LDH release, and increased the viability of the cells. The percentage of apoptotic cells was also significantly decreased. Osthole also inhibited the expression of BACE1 at mRNA and protein levels and the protein expression of Aβ. CONCLUSION: Osthole has protective effect on SH-SY5Y cells transfected with APP595/596 gene. The mechanism may be association with inhibiting the mRNA and protein expression of BACE1.     

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 MG132 on Aβ generation in SH-SY5Y cells

AIM: To observe the influences of different concentrations of MG132 on apoptosis and beta-amyloid protein(Aβ) generation in SH-SY5Y cells, and to explore the underlying mechanism.METHODS: SHSY-5Y cells were incubated with MG132 for 24 h. The final concentrations of MG132 were 2.5, 5 and 10 μmol/L. The cell viability was determined by MTT assay. The cell apoptosis was assessed by flow cytometry. The levels of Aβ were measured by ELISA. The relative protein levels were detected by Western blot.RESULTS: In the SH-SY5Y cells, MG132 reduced the cell viability, induced the cell apoptosis, increased the level of Aβ, and increased the expression of the related proteins for Aβ generation in a concentration-dependent manner.CONCLUSION: MG132 induces apoptosis and increases the levels of Aβ_1-42 and Aβ_1-40 by regulating the proteins related to Aβ generation in the SH-SY5Y cells.     

Resveratrol inhibits chondrosarcoma via mitochondrial and PI3K/Akt signaling pathways

AIM：To investigate the inhibitory effects of resveratrol on chondrosarcoma and the relation with mitochondrial and PI3K/Akt pathways. METHODS：Chondrosarcoma SW1353 cells were treated with resveratrol at concentrations of 25, 50 and 100 μmol/L for the time intervals of 24 h, 48 h and 72 h. The viability and apoptosis of the SW1353 cells in the presence or absence of resveratrol were analyzed by CCK8 assay and Hoechst 33258 staining, respectively. The protein levels of Bcl-2, Bax, activated caspase-3, Akt and p-Akt were detected by Western blotting. The cell migration ability was determined by wound scratch assay. RESULTS：Exposure of the cells to resveratrol resulted in a decrease in the cell viability in a dose- and time-dependent manner (P<0.05). visible nuclei with apoptotic characteristics in resveratrol group were observed. The protein levels of activated caspase-3 and Bax were increased, and Bcl-2 and p-Akt were decreased compared with control group. The total Akt were not significantly changed. Resveratrol also significantly reduced the migration of tumor cells. CONCLUSION：Resveratrol induces apoptosis of chondrosarcoma, which plays a role of part through mitochondrial and PI3K/Akt signaling pathways.     

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.     

Crosstalk between autophagy and apoptosis induced by Rip2 and its mechanisms in human pancreatic cancer cells

AIM To investigate the crosstalk between autophagy and apoptosis caused by receptor-interacting protein 2 (Rip2) and its underling mechanisms in human pancreatic cancer cells. METHODS Plasmids (pEGFP-C2 and pEGFP-Rip2) were transfected into human pancreatic cancer Panc-1 cells by jetPRIME method. The Panc-1 cells transfected with pEGFP-Rip2 were treated with 3-methyladenine (3-MA), an autophagy inhibitor. The apoptotic rate was analyzed by flow cytometry. The levels of apoptosis-associated proteins were measured by Western blot. The activity of caspase-8, -9 and -3 was examined by colorimetric method. Moreover, the Panc-1 cells transfected with pEGFP-Rip2 were treated with Z-VAD-FMK, a broad inhibitor of caspases. Subsequently, the levels of autophagy- and PI3K/Akt/mTOR signaling pathway-related proteins were assessed by Western blot. The autophagosomes were observed under transmission electron microscope. RESULTS (1) The apoptotic rate in pEGFP-Rip2 group markedly increased as compared with control group and pEGFP-C2 group, while the apoptotic rate in pEGFP-Rip2+3-MA group was further elevated compared with pEGFP-Rip2 group (P<0.05). Meanwhile, the protein levels of Fas, Bax and cytoplasmic cytochrome c (Cyt-c) were significantly increased, and the protein expression of Bcl-2 was markedly reduced in pEGFP-Rip2+3-MA group as compared with pEGFP-Rip2 group (P<0.05). The activity of caspase-8, -9 and -3 in pEGFP-Rip2+3-MA group was higher than that in pEGFP-Rip2 group. (2) The protein expression of beclin-1 and LC3-Ⅱ was significantly increased and more accumulated autophagosomes were observed under transmission electron microscope in pEGFP-Rip2+Z-VAD-FMK group as compared with pEGFP-Rip2 group. Furthermore, the protein levels of p-mTOR and p-Akt in pEGFP-Rip2+Z-VAD-FMK group were markedly reduced compared with pEGFP-Rip2 group, while no significant difference of mTOR and Akt protein expression was found between the 2 groups. CONCLUSION Inhibition of autophagy promotes apoptosis induced by Rip2 in the pancreatic cancer cells. Its mechanism may be associated with the further activation of the intrinsic and extrinsic apoptotic pathways. Suppression of apoptosis accelerates autophagy induced by Rip2 in the pancreatic cancer cells, and the mechanism may be related to the further down-regulation of PI3K/Akt/mTOR signaling pathways. There is a mutual antagonistic effect between autophagy and apoptosis caused by Rip2 in pancreatic cancer cells.     

Panax notoginseng saponins suppress oxygen-glucose deprivation/reoxygenation-induced pyroptosis of SH-SY5Y cells

AIM To investigate the effect of Panax notoginseng saponins (PNS) on pyroptosis of SH-SY5Y cells induced by oxygen-glucose deprivation/reoxygenation (OGD/R). METHODS The OGD/R was conducted to induce ischemia/reperfusion injury in SH-SY5Y cells. The effects of PNS on the viability (detected by CCK-8 assay) and membrane permeability [indicated by lactate dehydrogenase (LDH) leakage and propidium iodide (PI) staining positive cell proportion] of OGD/R-induced SH-SY5Y cells were observed. The protein levels of gasdermin D (GSDMD), GSDMD N-terminal fragment (GSDMD-N), caspase-1 and caspase-4, and the release of interleukin-1β (IL-1β) and IL-18 in the cells were also determined. RESULTS After exposure to OGD/R, the viability of SH-SY5Y cells dramatically decreased (P<0.01), while the LDH leakage, the PI staining positive cell proportion, the protein levels of GSDMD, GSDMD-N, caspase-1 and caspase-4, and the release of IL-1β and IL-18 were significantly increased (P<0.01). However, PNS treatment enhanced the viability of SH-SY5Y cells inhibited by OGD/R (P<0.01), but reduced the leakage of LDH and the percentage of PI staining positive cells (P<0.05 or P<0.01). Moreover, PNS reversed the increases in the protein levels of GSDMD, GSDMD-N, caspase-1 and caspase-4 and the release of IL-1β and IL-18 in OGD/R-induced SH-SY5Y cells (P<0.05 or P<0.01). CONCLUSION Treatment with PNS alleviates OGD/R-induced injury in SH-SY5Y cells. Its mechanism may be related to inhibition of SH-SY5Y cell pyroptosis induced by OGD/R.     

PI3K/mTOR dual inhibitor PF-04691502 induces apoptosis of human gastric cancer SGC-7901 cells

AIM:To determine the antitumor effect of PF-04691502, a dual inhibitor of phosphatidylinositol 3-kinase (PI3K)/Akt and mammalian target of rapamycin (mTOR), on the viability and apoptosis of human gastric cancer cell line SGC-7901.METHODS:Cell viability was analyzed by MTT assay. Cell cycle was detected by flow cytometry, and Annexin V-FITC/PI dual staining was used to detect cell apoptosis. Protein expression of p21, cyclin D1, caspase-3, caspase-8, caspase-9 and poly(ADP-ribose) polymerase (PARP) was determined by Western blotting. RESULTS:MTT assay and cell cycle analysis results indicated that PF-04691502 inhibited the viability of SGC-7901 cells in a dose-dependent manner, and arrested the cells in G1 phase. PF-04691502 down-regulated the expression of cyclin D1 and up-regulated the expression of p21. In addition, SGC-7901 cells treated with PF-04691502 showed typical characteristics of apoptosis, accompanied by activation of caspases and cleavage of PARP. CONCLUSION: The PI3K/mTOR dual inhibitor PF-04691502 induces the apoptosis and inhibited the growth of SGC-7901 cells, implicating its potential therapeutic value for the treatment of cancer.     

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.     

Effect of down-regulation of X-box binding protein 1 gene expression on viability and apoptosis of glioma cells

AIM: To investigate the effect of down-regulation of X-box binding protein 1 (XBP1) expression on the viability and apoptosis of glioma cells. METHODS: The mRNA expression of XBP1 in the glioma tissues was detected by qPCR. Small interfering RNA (siRNA) interfering with XBP1 expression (XBP1-siRNA) was transfected into human brain glioma U251 cells. At the same time, control group (the cells without special treatment) and negative control (NC-siRNA) group (transfected with siRNA without any interference) were set up. The mRNA expression of XBP1 in the 3 groups 48 h after transfection was detected by qPCR. The protein levels of XBP1, proliferating cell nuclear antigen (PCNA), B-cell lymphoma/leukemia-2 (Bcl-2), Bcl-2-associated X protein (Bax), cyclin D1 (cyclin D1), phosphatidylinositol 3-kinase (PI3K) and phosphorylated Akt (p-Akt) were determined by Western blot. The cell viability was measured by CCK-8 assay. The cell cycle distribution and apoptosis were analyzed by flow cytometry. RESULTS: The expression level of XBP1 in the glioma tissues was significantly higher than that in the tumor adjacent tissues (P<0.05). The XBP1 expression at mRNA and protein levels was significantly decreased in the cells transfected with XBP1-siRNA (P<0.05). No statistically significant difference of the cell viability, cell cycle, apoptotic rate and the protein levels of PCNA, Bcl-2, Bax, cyclin D1, PI3K and p-Akt between NC-siRNA group and control group was observed. Compared with control group, the cell viability, S-phase cells and the protein levels of PCNA, Bcl-2, cyclin D1, PI3K, and p-Akt in XBP1-siRNA group were decreased significantly, and the apoptotic rate, G₀/G₁-phase cells and Bax protein expression were significantly increased (P<0.05). CONCLUSION: Down-regulation of XBP1 gene expression in brain glioma cells reduces the viability of cancer cells, blocks the cells in G₁ phase and promote apoptosis. The mechanism is related to the inhibition of PI3K/Akt signaling pathway.     

Protective effects and mechanisms of losartan on apoptosis of H9c2 cells induced by β-adrenergic stimulation in vitro

AIM: To investigate the protective effect of losartan (Los) on apoptosis of H9c2 cells induced by isoprenaline (ISO), and to discover its related mechanism. METHODS: H9c2 cells cultured on plastic plates were divided into control, ISO, ISO+Los, ISO+Los+LY294002 and DMSO groups. Cell apoptosis was evaluated by flow cytometery and agarose gel electrophoresis. The mRNA levels of bax, bcl-2 and caspase-9 were detected by RT-PCR and the expressions of phosphorylated and total Akt (p-Akt and t-Akt) were assessed by Western blotting. The cAMP was measured by radioimmunoassay. RESULTS: ISO at concentration of 10 μmol/L induced apoptosis of H9c2 with an increase in bax/bcl-2, caspase-9 and cAMP. Addition of 10 μmol/L losartan inhibited apoptosis obviously with a decrease in bax/bcl-2, caspase-9 and cAMP. A significant increase in p-Akt was observed, and its protein level was elevated. LY294002 at concentration of 1 μmol/L abolished the protective effects of losartan on ISO-induced apoptosis in H9c2 cells. CONCLUSION: ISO might induce H9c2 cell apoptosis through stimulation of β-adrenergic receptor (β-AR). Los inhibits downstream signaling of β-AR, and promotes the activation of Akt. Subsequently it might attenuate the apoptosis induced by β-adrenergic stimulation of ISO.     

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.     

Protective effect of paeoniflorin on nerve cells in APP/PS1 mice and its mechanism

AIM: To investigate the therapeutic and preventive effects of paeoniflorin (PF) on APP/PS1 mice, and to explore the possible mechanism. METHODS: Fifteen male 5-month-old APP/PS1 non-dominant mice were chosen as normal control group, 15 male 5-month-old APP/PS1 double transgenic mice were used as model group, and 15 male 5-month-old APP/PS1 double transgenic mice treated with 5 mg/kg PF by intraperitoneal injection were allocated in administation group. The learning and memory ability of the mice in each group was detected by Morris water maze. The apoptosis was assessed by TUNEL fluorescence staining. The protein expression of PI3K, Akt, p-PI3K, p-Akt, caspase-3, caspase-9, Bcl-2 and Bax in cerebral cortex and hippocampus was detected by Western Blot. The protein expression levels and distribution of caspase-3 and caspase-9 were detected by immunohistochemistry. RESULTS: (1) Compared with normal control group, the learning and memory ability declined in APP/PS1 model group. Compared with APP/PS1 model group, PF obviously improve the ability of learning and memory in mice. (2) Compared with normal control group, the apoptosis of nerve cells in APP/PS1 model group significantly increased and distributed in wider areas, while that in PF group was reduced (P<0.05). (3) Compared with APP/PS1 model group, PF could significantly lower pro-apoptotic factors, caspase-3, caspase-9 and Bax (P<0.05), and increase the expression of anti-apoptotic factors, p-PI3K, p-Akt and Bcl-2 (P<0.05). CONCLUSION: PF can up-regulate the expression of Bcl-2 and down-regulate the expression levels of caspase-9, caspase-3 and Bax via the activation of PI3K/Akt pathway, thereby inhibiting the nerve cell apoptosis and protecting the nerve cells, so as to treat neurodegenerative diseases.