Phosphoinositide-3-Kinase/Akt-Endothelial Nitric Oxide Synthase Signaling Pathway Mediates the Neuroprotective Effect of Sevoflurane Postconditioning in a Rat Model of Hemorrhagic Shock and Resuscitation.

BACKGROUND: Although extensive reports have demonstrated the neuroprotection of sevoflurane postconditioning in cases of focal and global cerebral ischemia/reperfusion, the underlying mechanisms are not completely elucidated. This study investigated whether this effect is related to endothelial nitric oxide synthase (eNOS) and mediated by the phosphoinositide-3-kinase pathway in a rat model of hemorrhagic shock and resuscitation. METHODS: Adult male Sprague Dawley rats were subjected to hemorrhagic shock for 60 minutes and then resuscitation for 30 minutes in experimental groups. Sevoflurane postconditioning was performed at the beginning of resuscitation to completion. At 24 hours after resuscitation, the brain infarct volume was evaluated by 2,3,5-triphenyltetrazolium chloride staining. The neuronal morphological changes and apoptosis were determined by hematoxylin and eosin staining and immunohistochemistry analysis, respectively. The activity of phosphorylated Akt and eNOS was evaluated by Western blot analysis. RESULTS: Brain injuries such as the cerebral infarct volume and pathological neuronal changes as well as cell apoptosis were observed in the hippocampus after hemorrhagic shock and resuscitation. Postconditioning with 2.4% sevoflurane significantly attenuated brain injuries. Wortmannin prevented the improvements of neuronal characteristics elicited by sevoflurane postconditioning as well as the hyperactivity of eNOS and phosphorylated Akt. CONCLUSIONS: Sevoflurane postconditioning could attenuate brain injury induced by hemorrhagic shock and resuscitation, and this neuroprotective effect may be partly by upregulation of eNOS through the phosphoinositide-3-kinase/Akt signaling pathway.

Aerobic exercise and resistance exercise alleviate skeletal muscle atrophy through IGF-1/IGF-1R-PI3K/Akt pathway in mice with myocardial infarction.

Myocardial infarction (MI)-induced heart failure (HF) is commonly accompanied with profound effects on skeletal muscle. With the process of MI-induced HF, perturbations in skeletal muscle contribute to muscle atrophy. Exercise is viewed as a feasible strategy to prevent muscle atrophy. The aims of this study were to investigate whether exercise could alleviate MI-induced skeletal muscle atrophy via insulin-like growth factor 1 (IGF-1) pathway in mice. Male C57/BL6 mice were used to establish the MI model and were divided into three groups: sedentary MI group (MI), MI with aerobic exercise group, and MI with resistance exercise group; sham-operated group was used as control. Exercise-trained animals were subjected to 4 wk of aerobic exercise (AE) or resistance exercise (RE). Cardiac function, muscle weight, myofiber size, levels of IGF-1 signaling and proteins related to myogenesis, protein synthesis, and degradation and apoptosis in gastrocnemius muscle were detected. H2O2-treated C2C12 cells were intervened with recombinant human IGF-1, IGF-1 receptor (IGF-1R) inhibitor NVP-AEW541, and PI3K inhibitor LY294002 to explore the mechanism. Exercises upregulated the IGF-1/IGF-1R-phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling; increased the expressions of Pax7, myogenic regulatory factors (MRFs), and protein synthesis; and reduced protein degradation and cell apoptosis in MI mice. In vitro, IGF-1 upregulated the levels of Pax7, MRFs, mTOR, and P70S6K; reduced MuRF1 and MAFbx; and inhibited cell apoptosis via IGF-1R-PI3K/Akt pathway. AE and RE, safely and effectively, alleviate skeletal muscle atrophy by regulating the levels of myogenesis, protein degradation, and cell apoptosis in mice with MI via activating IGF-1/IGF-1R-PI3K/Akt signaling pathway.

Circular RNA HIPK3 regulates human lens epithelial cell dysfunction by targeting the miR-221-3p/PI3K/AKT pathway in age-related cataract.

Circular RNA Homeodomain Interacting Protein Kinase 3 (circHIPK3) was found to involve in the pathogenesis of age-related cataract (ARC). Here, we further disclosed the related target genes and molecular mechanism of circHIPK3 in the ARC progression. The expression of circHIPK3, microRNA (miR)-221-3p was detected using the quantitative real-time polymerase chain reaction. Human lens epithelial cell (HLEC) proliferation and apoptosis were measured by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-di-phenytetrazoliumromide (MTT) assay and flow cytometry, respectively. Western blot was used to detect the levels of apoptosis-related proteins, and phosphoinositide 3-kinase (PI3K)/p-protein kinase B (AKT) pathway-related proteins. Levels of malondialdehyde (MDA) and glutathione peroxidase (GSH-PX) were measured by kits. The interaction between miR-221-3p and circHIPK3 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assay. CircHIPK3 was down-regulated while miR-221-3p was up-regulated in human lens epithelium samples of ARC patients. CircHIPK3 up-regulation or miR-221-3p down-regulation mediated the promotion of proliferation, inhibition of apoptosis, decrease of MDA level as well as increase of GSH-PX level in HLECs. MiR-221-3p was a target of circHIPK3, and miR-221-3p overexpression reversed the protective action of circHIPK in HLEC functions. In addition, circHIPK3 activated PI3K/AKT pathway via regulating miR-221-3p, and silencing miR-221-3p protected HLECs from dysfunction by activating PI3K/AKT pathway. We demonstrated that circHIPK3 protected HLECs from dysfunction by regulating miR-221-3p/PI3K/AKT pathway, indicating a new insight into the pathogenesis of ARC and providing a potential therapeutic target for ARC.

MiR-221 affects the proliferation and apoptosis of laryngeal cancer cells through the PI3K/AKT signaling pathway.

OBJECTIVE: To investigate the effect of MiR-221 on proliferation and apoptosis of laryngeal carcinoma cells through the PI3K/AKT signaling pathway. MATERIALS AND METHODS: LipofectamineTM 2000 liposomes were used to transfer MiR-221 analogue, MiR-221 NC into Hep-2 cells of laryngeal carcinoma. Real-time fluorescence quantitative polymerase chain reaction (PCR) method was used to detect the expression of MiR-221, MTT method was used to detect the proliferation of cells, flow cytometry was used to detect cell cycle, Western blotting was used to detect the expression of apoptosis proteinase-1 (Apaf-1) and cyclin-dependent kinase (CDK1, CDK2) protein and the activation of phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT). RESULTS: Compared with MiR-221 NC group, the expression of MiR-221 in MiR-221 analogue group was up-regulated (p<0.01), the cell proliferation rate was decreased (p<0.01), the cell cycle was stagnated in the G1 phase (p<0.01), the expression levels of Cyclin A, CDK1, CDK2, PI3K, and p-AKT were significantly down-regulated (p<0.01), and the expression levels of Bax and Apaf-1 were significantly up-regulated (p<0.01). CONCLUSIONS: MiR-221 analogues can significantly inhibit the proliferation and induce apoptosis of Hep-2 cells in laryngeal cancer, and this is achieved by blocking the PI3K/AKT signaling pathway, which also indicates that MiR-221 affects the proliferation and apoptosis of laryngeal cancer cells through the PI3K/AKT signaling pathway.

Effects of resveratrol on the expression of molecules related to the mTOR signaling pathway in pathological scar fibroblasts.

BACKGROUND: We observed the effects of resveratrol on the expression of molecules involved in the mTOR signaling pathway in pathological scar fibroblasts, including PI3K, Akt and mTOR. METHODS: We detected the expression of PI3K, Akt and mTOR in pathological scar and normal skin fibroblasts through immunofluorescence. After being treated with different concentrations of resveratrol, the expression of PI3K, Akt and mTOR mRNA and protein were detected by RT-PCR and Western Blot respectively. RESULTS: Results showed that the expression of PI3K, Akt and mTOR were significantly enhanced in pathological scar fibroblasts and mainly expressed in the nucleus, with no expression in normal skin fibroblasts. Results from RT-PCR and Western Blot tests demonstrated that after Res intervention with different concentrations for pathological scar fibroblasts, the relative expression quantity of PI3K mRNA and protein decreased and showed a dose dependent relationship. Compared to the control group, the differences were statistically significant (P<0.05). However, decrease in the expression of PI3K mRNA and protein was not obvious and there were no significant differences in comparison to the control group (P>0.05). CONCLUSIONS: The mechanism of resveratrol in the inhibition of the proliferation of pathological scar fibroblasts may be related to its down-regulation in the expression of Akt and mTOR, which are the key molecules of mTOR signaling pathway.

Mechanism of metformin enhancing the sensitivity of human pancreatic cancer cells to gem-citabine by regulating the PI3K/Akt/mTOR signaling pathway.

OBJECTIVE: To investigate the effect of metformin (MET) on enhancing the sensitivity of human pancreatic cancer cells to gemcitabine (GEM) by regulating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. MATERIALS AND METHODS: The GEM-resistant human pancreatic cancer PANC-1/GEM cell line was established, and the proliferation ability of PANC-1 and PANC-1/GEM cell lines was detected using the Cell Counting Kit-8 (CCK-8), which was then detected by flow cytometry after they were labeled by Ki67. Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) and Western blotting were adopted to detect the difference in the mTOR expression between PANC-1 and PANC-1/GEM cell lines. The proliferation ability of PANC-1/GEM/MET and PANC-1/GEM cell lines was determined using CCK-8 after drug-resistant cell lines were treated with 20 mmol/L MET combined with 0.4 µmol/L GEM or 0.4 µmol/L GEM alone for 48 h. Colony formation assay was applied to detect the proliferation ability of cells. The difference in the expression of mTOR/PI3K/Akt between PANC-1/GEM/MET and PANC-1/GEM cell lines was tested via qRT-PCR and Western blotting, respectively. RESULTS: Compared with PANC-1 cells, PANC-1/GEM cells had significantly enhanced proliferation ability (p<0.01). Flow cytometry results showed that the proliferation ability of PANC-1/GEM cells was notably enhanced (p<0.01). The expression level and phosphorylation level of mTOR in drug-resistant cell lines were increased (p<0.01). After the drug-resistant cell lines were treated with 20 mmol/L MET for 48 h, the proliferation ability of PANC-1/GEM/MET cells was evidently decreased compared with that of PANC-1/GEM cells (p<0.01). The messenger ribonucleic acid (mRNA) and protein expression levels of mTOR/PI3K/Akt were markedly down-regulated (p<0.01). CONCLUSIONS: MET can regulate the PI3K/Akt/mTOR signaling pathway to enhance the sensitivity of human pancreatic cancer cells to GEM.

Dose optimisation of PTEN inhibitor, bpV (HOpic), and SCF for the in-vitro activation of sheep primordial follicles.

The in-vitro development of primordial follicles is critical for improving mammalian fertility and wildlife conservation. This study aimed to optimise the effective doses of bpV (HOpic) and stem cell factor (SCF) for the in-vitro activation of sheep primordial follicles. To do this, sheep ovarian cortex was treated with bpV (1.5, 15, and 150 µM) and SCF (50 and 100 ng/ml). Follicular count indicated that 15 µM bpV and 100 ng/ml SCF significantly increased normal primary follicles compared to other groups (p < 0.05). Also, a significant downregulation of P53 and PTEN, as well as the increased expression of PI3K was observed. The in-vitro maturation was more pronounced when the fragmented tissues were co-treated with selected doses of bpV and SCF. In conclusion, the combination of 15 µM bpV and 100 ng/ml SCF was the most effective treatment strategy for the activation and survival of primordial follicles in sheep ovarian fragments.

Microglial BDNF, PI3K, and p-ERK in the Spinal Cord Are Suppressed by Pulsed Radiofrequency on Dorsal Root Ganglion to Ease SNI-Induced Neuropathic Pain in Rats.

Background: Pulsed radiofrequency (PRF) on the dorsal root ganglion (DRG) has been applied to alleviate neuropathic pain effectively, yet the mechanisms underlying pain reduction owing to this treatment are not clarified completely. The activated microglia, brain-derived neurotrophic factor (BDNF), phosphatidylinositol 3-kinase (PI3K), and phosphorylated extracellular signal-regulated kinase (p-ERK) in the spinal cord were demonstrated to be involved in developing neuropathic pain. Also, it has been just known that PRF on DRG inhibits the microglial activation in nerve injury rats. Here, we aim to investigate whether PRF treatment could regulate the levels of BDNF, PI3K, and p-ERK in the spinal cord of rats with spared nerve injury (SNI) via suppressing the spinal microglia activation to ease neuropathic pain. Methods: The rats with SNI were intrathecally treated with minocycline (specific microglia inhibitor) or same volume of dimethyl sulfoxide once daily, beginning from 1 h before nerve transection to 7 days. PRF was applied adjacent to the L4-L5 DRG of rats with SNI at 45 V for 6 min on the seventh postoperative day, whereas the free-PRF rats were treated without PRF. The withdrawal thresholds were studied, and the spinal levels of ionized calcium-binding adapter molecule 1 (Iba1), BDNF, PI3K, and p-ERK were calculated by western blot analysis, reverse transcription-polymerase chain reaction, and immunofluorescence. Results: The paw withdrawal mechanical threshold and paw withdrawal thermal latency decreased in the ipsilateral hind paws after SNI, and the spinal levels of Iba1, BDNF, PI3K, and p-ERK increased on day 21 after SNI compared with baseline (P < 0.01). An intrathecal injection of minocycline led to the reversal of SNI-induced allodynia and increase in levels of Iba1, BDNF, PI3K, and p-ERK. Withdrawal thresholds recovered partially after a single PRF treatment for 14 days, and SNI-induced microglia hyperactivity, BDNF upregulation, and PI3K and ERK phosphorylation in the spinal cord reduced on D14 due to the PRF procedure. Conclusion: Microglial BDNF, PI3K, and p-ERK in the spinal cord are suppressed by the therapy of PRF on DRG to ease SNI-induced neuropathic pain in rats.

PI3K-PKB-mTOR hyperactivation in relation to nasopharyngeal carcinoma progression and prognosis.

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology, which is not completely understood. The aim of this study is to investigate the expression patterns of phosphatidylinositol 3-kinase (PI3K), protein kinase B (PKB), and mammalian target of rapamycin (mTOR) proteins in patients with NPC and their relationship with NPC progression and prognosis. Between January 2008 and March 2010, PI3K, PKB, and mTOR protein expressions were detected using immunohistochemistry among 119 patients with NPC and 30 healthy people. A 5-year follow-up was conducted for all patients. Correlations of PI3K, PKB, and mTOR proteins with the clinicopathological features and prognosis of NPC were evaluated using Spearman's rank correlation coefficient and Kaplan-Meier curve. Cox's regression analysis was performed to analyze the risk factors for the prognosis of NPC. First, PI3K, PKB, and mTOR were highly expressed in patients with NPC. The expressions of PI3K, PKB, and mTOR proteins were associated with T stage, N stage, clinical stage, relapse, and distant metastasis. Meanwhile, PI3K is positively correlated with PKB and PKB is positively correlated with mTOR in NPC. Higher PI3K, PKB, and mTOR protein expressions were related to a shorter survival time and a lower survival rate in NPC. Cox regression analysis revealed that age, T stage, N stage, PI3K, PKB, and mTOR were independent risk factors for NPC patient survival. Altogether, our data suggest that overexpression of PI3K, PKB, and mTOR proteins is an important indicator of poor survival in NPC. In addition, inhibition of PI3K-PKB-mTOR signaling may also contribute to the development of new therapeutic strategies for NPC.

Phosphoinositide 3-kinase (p110α) gene delivery limits diabetes-induced cardiac NADPH oxidase and cardiomyopathy in a mouse model with established diastolic dysfunction.

Phosphoinositide 3-kinase [PI3K (p110α)] is able to negatively regulate the diabetes-induced increase in NADPH oxidase in the heart. Patients affected by diabetes exhibit significant cardiovascular morbidity and mortality, at least in part due to a cardiomyopathy characterized by oxidative stress and left ventricular (LV) dysfunction. Thus, PI3K (p110α) may represent a novel approach to protect the heart from diabetes-induced cardiac oxidative stress and dysfunction. In the present study, we investigated the therapeutic potential of a delayed intervention with cardiac-targeted PI3K gene therapy, administered to mice with established diabetes-induced LV diastolic dysfunction. Diabetes was induced in 6-week-old male mice by streptozotocin (STZ). After 8 weeks of untreated diabetes, LV diastolic dysfunction was confirmed by a reduction in echocardiography-derived transmitral E/A ratio. Diabetic and non-diabetic mice were randomly allocated to receive either recombinant adeno-associated viral vector-6 carrying a constitutively-active PI3K construct (recombinant adeno-associated-virus 6-constitutively active PI3K (p110α) (caPI3K) (rAAV6-caPI3K), single i.v. injection, 2 × 1011 vector genomes) or null vector, and were followed for a further 6 or 8 weeks. At study endpoint, diabetes-induced LV dysfunction was significantly attenuated by a single administration of rAAV6-caPI3K, administered 8 weeks after the induction of diabetes. Diabetes-induced impairments in each of LV NADPH oxidase, endoplasmic reticulum (ER) stress, apoptosis, cardiac fibrosis and cardiomyocyte hypertrophy, in addition to LV systolic dysfunction, were attenuated by delayed intervention with rAAV6-caPI3K. Hence, our demonstration that cardiac-targeted PI3K (p110α) gene therapy limits diabetes-induced up-regulation of NADPH oxidase and cardiac remodelling suggests new insights into promising approaches for the treatment of diabetic cardiomyopathy, at a clinically relevant time point (after diastolic dysfunction is manifested).

The effect of cortisol in rat steatotic and non-steatotic liver transplantation from brain-dead donors.

In the present study, we examined the effects of cortisol on steatotic and non-steatotic liver grafts from brain-dead donors and characterized the underlying mechanisms involved. Non-steatotic liver grafts showed reduced cortisol and increased cortisone levels in association with up-regulation of enzymes that inactivate cortisol. Conversely, steatotic liver grafts exhibited increased cortisol and reduced cortisone levels. The enzymes involved in cortisol generation were overexpressed, and those involved in cortisol inactivation or clearance were down-regulated in steatotic liver grafts. Exogenous administration of cortisol negatively affected hepatic damage and survival rate in non-steatotic liver transplantation (LT); however, cortisol treatment up-regulated the phosphoinositide 3-kinase (PI3K)-protein kinase C (PKC) pathway, resulting in protection against the deleterious effects of brain-dead donors on damage and inflammatory response in steatotic LT as well as in increased survival of recipients. The present study highlights the differences in the role of cortisol and hepatic mechanisms that regulate cortisol levels based on the type of liver. Our findings suggest that cortisol treatment is a feasible and highly protective strategy to reduce the adverse effects of brain-dead donor livers in order to ultimately improve liver graft quality in the presence of steatosis, whereas cortisol treatment would not be recommended for non-steatotic liver grafts.

Cysteine­rich 61 RNA interference inhibits pathological angiogenesis via the phosphatidylinositol 3­kinase/Akt­vascular endothelial growth factor signaling pathway in endothelial cells.

Hypoxia is a key factor in the pathogenesis of angiogenesis, and cysteine­rich 61 (CCN1), an angiogenic factor, is involved in the development of pathological angiogenesis. The aim of the present study was to investigate the mechanism of CCN1 RNA interference (RNAi)­induced inhibition of hypoxia­induced pathological angiogenesis in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions in vitro. The effects of inhibiting phosphoinositide 3­kinase (PI3K)/Akt signaling using LY294002 were investigated in hypoxic HUVECs. The proliferation and apoptosis of HUVECs under hypoxia were assessed using CCN1 RNAi. The CCN1­PI3K/Akt­vascular endothelial growth factor (VEGF) pathway was analyzed under hypoxic conditions using reverse transcription­quantitative polymerase chain reaction and western blotting. CCN1 RNAi inhibited the proliferation and induced the apoptosis of the HUVECs under hypoxia, with hypoxia significantly increasing the mRNA and protein expression levels of CCN1, Akt and VEGF. By contrast, CCN1 RNAi reduced the mRNA and protein expression levels of CCN1, Akt and VEGF in the HUVECs (P<0.05). Furthermore, LY294002 reduced the mRNA and protein expression levels of CCN1 in the hypoxic cells (P<0.05). These data indicated that CCN1 inhibits apoptosis and promotes proliferation in HUVECs. Therefore, CCN1 RNAi may offer a novel therapeutic strategy, which may aid in the treatment of pathological angiogenesis via inhibition of the PI3K/Akt­VEGF pathway.

Protective Effect of Tempol on Acute Kidney Injury Through PI3K/Akt/Nrf2 Signaling Pathway.

BACKGROUND/AIMS: Tempol is a protective antioxidant against ischemic injury in many animal models. The molecular mechanisms are not well understood. Nuclear factor erythroid 2-related factor (Nrf2) is a master transcription factor during oxidative stress, which is enhanced by activation of protein kinase C (PKC) pathway. Another factor, tubular epithelial apoptosis, is mediated by activation of phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB, Akt) signaling pathway during renal ischemic injury. We tested the hypothesis that tempol activates PKC or PI3K/Akt/Nrf2 pathways to transcribe many genes that coordinate endogenous antioxidant defense. METHODS: The right renal pedicle was clamped for 45 minutes and the left kidney was removed to study renal ischemia/reperfusion (I/R) injury in C57BL/6 mice. The response was assessed from serum parameters, renal morphology and renal expression of PKC, phosphorylated-PKC (p-PKC), Nrf2, heme oxygenase-1 (HO-1), Akt, phosphorylated-Akt (p-Akt), pro-caspase-3 and cleaved caspase-3 in groups of sham and I/R mice given vehicle, or tempol (50 or 100 mg/kg, intraperitoneal injection). RESULTS: The serum malondialdehyde (MDA, marker of reactive oxygen species) doubled and the BUN and creatinine increased 5- to 10-fold after I/R injury. Tempol (50 or 100 mg/kg) prevented the increases in MDA but only tempol (50 mg/kg) lessened the increases in BUN and creatinine and moderated the acute tubular necrosis. I/R did not change expression of PKC or p-PKC but reduced renal expression of Nrf2, p-Akt, HO-1 and pro-caspase-3 and increased cleaved caspase-3. Tempol (50 mg/kg) prevented these changes produced by I/R whereas tempol (100 mg/kg) had lesser or inconsistent effects. CONCLUSION: Tempol (50 mg/kg) prevents lipid peroxidation and attenuates renal damage after I/R injury. The beneficial pathway apparently is not dependent on upregulation or phosphorylation of PKC, at lower tempol doses, does implicate upregulation of Akt with expression of Nrf2 that could account for the increase in the antioxidant gene HO-1 and a reduction in the cleavage of the cellular damage marker pro-caspase-3.

Apelin attenuates postburn sepsis via a phosphatidylinositol 3-kinase/protein kinase B dependent mechanism: A randomized animal study.

INTRODUCTION: This study aims to investigate whether apelin would regulate inflammatory response and promote survival in an experimental burn sepsis model through a phosphatidylinositol 3-kinase/protein kinase B dependent pathway. METHODS: Male BALB/c mice were divided into the following groups: sham, burn, burn sepsis, burn sepsis treated with apelin, burn sepsis treated with apelin plus LY294002, and burn sepsis treated with LY294002 alone. Apelin level and inflammatory cytokines in serum were detected by enzyme-linked immuno sorbent assay. Apelin/APJ (apelin receptor, gene symbol APLNR) mRNA expression in spleen and adhesion molecules levels in lung was detected by real-time polymerase chain reaction. Neutrophil infiltration in lung was determined by myeloperoxidase assay. Phosphorylation of protein kinase B in lung was determined by western blot. Mortality rate was monitored. RESULTS: Burn sepsis induced decreased apelin/APJ mRNA expression in spleen and reduced apelin level in plasma, which were both restored by exogenous apelin treatment. Burn sepsis treated with apelin resulted in decreased interleukin-6, tumor-necrosis factor-alpha, interleukin -1ß and monocyte chemotactic protein-1 levels in plasma. Mice with apelin treatment also showed decreased neutrophil infiltration and adhesion molecules expression, accompanied by a remarkable increased protein kinase B phosphorylation in lung tissue. The mortality rate in apelin treated animals was also significantly reduced. Importantly, the above effects of apelin were abolished by LY294002 treatment. CONCLUSION: Apelin regulates inflammatory response, diminishes inflammatory remote organ damage and improves survival in an experimental model of burn sepsis, which is at least partly mediated by a phosphatidylinositol 3-kinase/protein kinase B dependent pathway.

Effects of Icariin on insulin resistance via the activation of AMPK pathway in C2C12 mouse muscle cells.

Insulin resistance in skeletal muscle is a major risk factor for the development of type 2 diabetes (T2D). In this study, we investigated the effect of icariin on insulin resistance in C2C12 mouse skeletal muscle cells. C2C12 myoblasts were differentiated into myotubes for five days, then treated with icariin (50 and 100µM) or metformin (1mM) in the presence of 100nM insulin for 24h. Adiponectin production was measured in culture media by ELISA, and AMP-activated protein kinase (AMPK)/insulin signaling pathway activation was assessed by the western blot analysis. Icariin significantly increased adiponectin production in C2C12 myotubes. Moreover, icariin markedly promoted the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC). Icariin up-regulated the expression of phosphatidylinositol 3-kinase (PI3K) and the phosphorylation of insulin receptor substrate-1 (IRS-1) in C2C12 myotubes. These results suggest that icariin has therapeutic potential for the treatment of T2D via the regulation of insulin resistance in skeletal muscle.

Paclitaxel resistance in MCF-7/PTX cells is reversed by paeonol through suppression of the SET/phosphatidylinositol 3-kinase/Akt pathway.

Breast cancer is one of the most prevalent types of malignant tumor. Paclitaxel is widely used in the treatment of breast cancer; however, the major problem contributing to the failure of chemotherapy in breast cancer is the development of drug resistance. Therefore, it is necessary to identify novel therapeutic targets and reversal agents for breast cancer. In the present study, the protein expression levels of SET, protein phosphatase 2A (PP2A) and phosphatidylinositol 3-kinase (PI3K)/Akt pathway were determined in MCF-7/PTX human breast carcinoma paclitaxel-resistant cells using western blot analysis. Small interference RNAs (siRNAs) were used to knock down the gene expression of SET in MCF-7/PTX cells and the cell viability was assessed following treatment with paclitaxel, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assays and flow cytometry. In addition, western blot analysis was used to determined PI3K/Akt pathway activity following SET knockdown. Furthermore, the reversal effects of paeonol on paclitaxel, and its underlying mechanisms of action, were investigated using western blot analysis and reverse transcription-quantitative polymerase chain reaction. The results demonstrated that increased levels of SET and PI3K/Akt pathway proteins were present in the MCF-7/PTX cells, compared with normal MCF-7 cells. Knockdown of SET significantly sensitized MCF-7/PTX cells to paclitaxel and induced cell apoptosis. In addition, the expression levels of the adenosine triphosphate binding cassette (ABC) transporter proteins were significantly reduced in the MCF-7/PTX cells compared with the normal MCF-7 cells. SET-induced paclitaxel resistance was found to be associated with the activation of the PI3K/Akt pathway. Paeonol significantly reduced the mRNA and protein expression levels of SET in the MCF-7/PTX cells. Furthermore, paeonol significantly sensitized the MCF-7/PTX to paclitaxel via regulation of ABC transporters, B cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein. In addition, paeonol inhibited SET-mediated paclitaxel resistance by attenuating PI3K/Akt pathway activity in the MCF-7/PTX cells. In conclusion, the results of the present study demonstrated that SET was associated with paclitaxel resistance in MCF-7/PTX cells, and that paeonol reversed paclitaxel resistance in MCF-7/PTX cells by downregulating the activity of the SET/PP2A/Akt pathway.

Shikonin inhibits oxidized LDL-induced monocyte adhesion by suppressing NFκB activation via up-regulation of PI3K/Akt/Nrf2-dependent antioxidation in EA.hy926 endothelial cells.

Oxidized low-density lipoprotein (oxLDL) is a key contributor to atherogenesis through multiple mechanisms, including the reactive oxygen species (ROS)-mediated nuclear factor-kappaB (NFκB) signaling pathway. Although shikonin, one of the main active components isolated from the Chinese herb Lithospermum erythrorhizon, has been shown to possess cardioprotective, antioxidative, and anti-inflammatory effects, the mechanisms underlying these actions are not well understood. In this study, we used EA.hy926 endothelial-like cells to examine the anti-atherogenic activity of shikonin. Shikonin (0-1 µM) concentration-dependently induced heme oxygenase-1, glutamate cysteine ligase modifier subunit, catalase, superoxide dismutase 1, glutathione peroxidase 1, and glutathione reductase protein and mRNA expression and glutathione content via activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/Nrf2 signaling pathway. In the presence of oxLDL (40 µg/ml), shikonin pretreatment reversed oxLDL-induced ROS production, antioxidant response element reporter activity, NFκB nuclear translocation, and intercellular adhesion molecule (ICAM)-1 and E-selectin expression and suppressed the increase of monocyte adhesion to endothelial cells. Nrf2 knockdown by using RNA interference attenuated the ability of shikonin to inhibit oxLDL-induced NFκB DNA binding activity, adhesion molecule expression, and monocyte adhesion. Taken together, these results suggest that shikonin protects against oxLDL-induced endothelial damage by suppressing ROS/NFκB-mediated ICAM-1 and E-selectin expression via up-regulation of PI3K/Akt/Nrf2-dependent antioxidant enzyme expression.

Studies on mitogen-activated protein kinase signaling pathway in the alveolar macrophages of chronic bronchitis rats.

Lipopolysaccharide (LPS), a potent stimulator of inflammatory responses in alveolar macrophages (AMs), activates several intracellular signaling pathways, including mitogen-activated protein kinases (MAPK). In the present study, we investigated the MAPK pathway in AMs of chronic bronchitis (CB) rats. CB was induced by endotracheal instillation of LPS followed by Bacillus Calmette Guerin injection through the caudal vein 1 week later. Specific inhibitors were used and protein phosphorylations were detected by Western blot. We found that Genistein (PTK inhibitor) could inhibit protein kinase C (PKC), phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt or PKB) MAPK signaling pathway with different degrees, LY294002 (PI3K inhibitor) could not only inhibit phospho-PI3K/Akt expression, but also inhibit p38 and c-Jun NH2-terminal kinases (JNK) phosphorylation. Calphostin C (PKC inhibitor) could inhibit phospho-PKC expression and exerted significant effects on extracellular signal-regulated kinases (ERK) phosphorylation, however, it had no impact on p38 and JNK phosphorylation. These results demonstrated that the LPS mediated signaling pathway of MAPK in AMs of CB rats could be described as follows: PTK-PI3K-Akt-JNK/p38 or PTK-PI3K-PKC-ERK, and PI3K may have a negative regulation on the activation of downstream proteins.

CD38 is highly expressed and affects the PI3K/Akt signaling pathway in cervical cancer.

Cervical cancer is the second most common cancer and the fifth most deadly malignancy in females worldwide, affecting 500,000 individuals each year. It is the leading cause of cancer mortality among women in developing countries. Dysregulated activation of genes, such as CD44, SOX9 and SKP2, plays a role in cervical cancer. CD38 is known to be involved in activities typical of cell surface receptors, such as signaling for activation and proliferation events and heterotypic cell adhesion. CD38 contributes to disease progression and relapse in certain tumors, such as acute myeloid and chronic lymphocytic leukemia. To the best of our knowledge, there is currently no report on the relationship between CD38 and cervical cancer. Using qPCR, immunohistochemistry, and western blot analysis, the expression levels of CD38 were investigated and found to be upregulated in cervical cancer. CD38 was correlated with dysregulation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in cervical cancer tissues in vitro. At the same time, CD38 overexpression affected the expression of PI3K, Akt, MDM2 and p53 in vivo. The results of the present study suggested that CD38 is highly expressed in cervical carcinoma tissues and play an important role in dysregulation of the PI3K/Akt signaling pathway.

RhoA/phosphatidylinositol 3-kinase/protein kinase B/mitogen-activated protein kinase signaling after growth arrest-specific protein 6/mer receptor tyrosine kinase engagement promotes epithelial cell growth and wound repair via upregulation of hepatocyte growth factor in macrophages.

Growth arrest-specific protein 6 (Gas6)/Mer receptor tyrosine kinase (Mer) signaling modulates cytokine secretion and helps to regulate the immune response and apoptotic cell clearance. Signaling pathways that activate an epithelial growth program in macrophages are still poorly defined. We report that Gas6/Mer/RhoA signaling can induce the production of epithelial growth factor hepatic growth factor (HGF) in macrophages, which ultimately promotes epithelial cell proliferation and wound repair. The RhoA/protein kinase B (Akt)/mitogen-activated protein (MAP) kinases, including p38 MAP kinase, extracellular signal-regulated protein kinase, and Jun NH2-terminal kinase axis in RAW 264.7 cells, was identified as Gas6/Mer downstream signaling pathway for the upregulation of HGF mRNA and protein. Conditioned medium from RAW 264.7 cells that had been exposed to Gas6 or apoptotic cells enhanced epithelial cell proliferation of the epithelial cell line LA-4 and wound closure. Cotreatment with an HGF receptor-blocking antibody or c-Met antagonist downregulated this enhancement. Inhibition of Mer with small interfering RNA (siRNA) or the RhoA/Rho kinase pathway by RhoA siRNA or Rho kinase pharmacologic inhibitor suppressed Gas6-induced HGF mRNA and protein expression in macrophages and blocked epithelial cell proliferation and wound closure induced by the conditioned medium. Our data provide evidence that macrophages can be reprogrammed by Gas6 to promote epithelial proliferation and wound repair via HGF, which is induced by the Mer/RhoA/Akt/MAP kinase pathway. Thus, defects in Gas6/Mer/RhoA signaling in macrophages may delay tissue repair after injury to the alveolar epithelium.