Role of TGF-β1-activated p38 MAPK in up-regulation of PAI-1 expression by TGF-β1 in human ovarian cancer cells

AIM: To investigate the relationship between up-regulation of plasminogen activator inhibitor-1(PAI-1) expression and activation of p38 mitogen-activated protein kinase(p38 MAPK) and extracellular signal-regulated kinase(ERK) pathways by TGF-β1 in human ovarian cancer cells. METHODS: PAI-1 expression in human ovarian cancer cells treated with TGF-β1(10 μg/L)was assayed by real-time PCR and Western blotting. The activation of p38 MAPK and ERK was determined by Western blotting using phosphorylated p38 MAPK and phosphorylated ERK antibodies. Specific p38 MAPK inhibitor(SB203580) or ERK inhibitor(PD98059) was used to inhibit their activation. RESULTS: TGF-β1 up-regulated the expression of PAI-1, and activated p38 MAPK and ERK pathways in the ovarian cancer cells. Inhibition of p38 MAPK activation by SB203580 resulted in significant inhibition of the mRNA expression of PAI-1 induced by TGF-β1. However, inhibition of ERK activation did not significantly alter TGF-β1-induced increase in PAI-1 mRNA level. CONCLUSION: TGF-β1-activated p38 MAPK pathway contributes to the up-regulation of PAI-1 expression by TGF-β1 in ovarian cancer cells.     

Effect of cladribine on growth inhibition and autocrining cytokines in human umbilical vein endothelial cell line EA.hy926

AIM: To study the effects of cladribine on growth and secretion activity of human umbilical vein endothelial cell line EA.hy926, and to investigate the mechanism of its anti-tumor effect by inhibiting endothelial cells. METHODS: The effects of cladribine at different concentrations on the cell viability were detected by CCK-8 assay. Apoptosis and cell cycle distribution were examined by flow cytometry. The protein expression levels were determined by Western blot. The levels of tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor (VEGF) secreted by EA.hy926 cells with cladribine treatment for 48 h were analyzed by ELISA. The nitric oxide (NO) production was measured by Gries method. RESULTS: Cladribine at 0.4~1 μmol/L inhibited the viability of EA.hy926 cells in time-and dose-dependent manners. The IC₅₀ was about 3.644 μmol/L. The results showed 43.74% cells in S phase when the concentration of cladribine was 0.4 μmol/L, and 77.23% cells in S phase when the concentration of cladribine was 1 μmol/L. The apoptosis was not induced by cladribine at 0.4~10 μmol/L. The protein expression of Bax and caspase-3 did not change. The expression of p21 increased and the p53 decreased (P<0.05). The levels of TNF-α and TGF-β1 secreted by EA.hy926 cells increased after cladribine treatment for 48 h. The levels of VEGF and NO decreased. CONCLUSION: Cladribine obviously inhibits the viability of EA.hy926 cells. The mechanism is related to the cell cycle arrest. Cladribine promotes the secretion of TNF-α and TGF-β1 by EA.hy926 cells and inhibits the secretion of VEGF and NO.     

p38 MAPK/ATF-2 pathway is involved in C-relative protein-induced endothelial cell activation

AIM: To investigate the role of p38 MAPK/ATF-2 pathway in C-relative protein (CRP)-induced endothelial cell activation. METHODS: Human coronary artery endothelial cells (HCAEC) were cultured and were used between passages 3 and 7. CRP served as a stimulus for endothelial cell activation. Western blotting was performed to determine the expression and phosphorylation of eNOS, p38 and ATF2. ELISA was carried out to detect the levels of ICAM-1, VCAM-1 and MCP-1 released from HCAEC. Pharmacological p38 inhibitors SB203580 and SB202190 were used to determine the effect of p38/ATF-2 pathway. RESULTS: CRP reduced the p-eNOS level in a concentration-dependent manner and induced the release of ICAM-1, VCAM-1 and MCP-1. The p38/ATF-2 pathway was activated by CRP treatment. SB203580 and SB202190 partially rescued p-eNOS level and suppressed the secretion of ICAM-1, VCAM-1 and MCP-1. CONCLUSION: p38MAPK/ATF-2 pathway participates in CRP-induced endothelial activation.     

Salvianolate attenuates oxidative stress injury of human endothelial EA.hy926 cells induced by hydrogen peroxide

AIM: To investigate the effect of salvianolate on oxidative damage induced by hydrogen peroxide in human endothelial EA.hy926 cells.METHODS: EA.hy926 cells were cultured in vitro and divided into the following groups:control group, damage group, and anti-damage groups (salvianolate+damage groups). The cell viability was measured by CCK-8 assay. The migration ability of the EA.hy926 cells was detected by Transwell assay. The content of nitric oxide (NO) in the culture supernatant of the EA.hy926 cells was examined. The levels of vascular endothelial growth factor (VEGF) were detected by ELISA. The apoptosis,mitochondrial membrane potential and intracellular superoxide anion content of the EA.hy926 cells were analyzed by flow cytometry. The protein levels of caspase-3, cleaved caspase-3, Bcl-2, Bax, NF-κB and p53 were determined by Western blot. RESULTS: Compared with damage group, the viability of EA.hy926 cells pretreated with salvianolate at different concentrations was significantly increased (P<0.05). The apoptotic rate was significantly decreased (P<0.05). Savianolate enhanced the migration ability of the cells. The levels of VEGF, NO and mitochondrial transmembrane potential were increased (P<0.05), and the intracellular ROS level was significantly decreased (P<0.05). The protein levels of NF-κB, p53, Bax and cleaved caspase-3 were significantly decreased, and the protein level of Bcl-2 was markedly increased(P<0.05). CONCLUSION: Savianolate reduces the damage of EA.hy926 cells by hydrogen peroxide exposure, and its mechanism may be related to the blocking of NF-κB signaling pathway.     

Effect of N,N-dimethylsphingosine on the expression of adhesion molecules in human umbilical vein endothelial cell line EA.hy926

AIM: To investigate whether and how N, N-dimethylsphingosine (DMS) plays a role in modulating the adhesion of monocytes to vascular endothelial cells, and identify whether human umbilical vein endothelial cell line EA.hy926 take place of the vascular endothelial cells.METHODS: Adhesion ratio was measured by flow cytometry, and immunohistochemistry was used to detect the expression of ICAM-1 and P-selectin in HUVEC: EA.hy926 cells after the effect of DMS. RESULTS: DMS inhibited the adhesion of monocytes to HUVEC: EA.hy926 cells in a time-dependent and concentration-dependent manner by reducing the expression of ICAM-1 and P-selectin. CONCLUSIONS: DMS reduced adhesion molecule expression in vascular endothelial cells. DMS may be an important contributor to reduce adhesion ratio, suggesting that DMS plays a negative role in proinflammatory and immune functions of the modified vascular endothelial cells during atherosclerosis and restenosis.     

Role of p38 MAPK signaling pathway in inflammatory effects on cerulein-induced pancreatic cells

AIM: To investigate the effect of p38 MAPK signal pathway on cerulein-treated pancreatic acinar AR42J cells.METHODS: AR42J cells were divided into control group, cerulein group (treated with 10^-8 mol/L of cerulein), and SB203580 group (treated with 10 μmol/L of SB203580 and 10^-8mol/L of cerulein).The cells were harvested 3 h after treatment.Secretion rate of amylase was measured.The translocation of p-p38 MAPK to nuclei was imaged by immunofluorescence.The protein expression levels of p-p38 MAPK and TNF-α were detected by Western blotting.The activation of NF-κB was measured by electrophoretic mobility assay.RESULTS: Compared with control group, cerulein resulted in increases in the secretion rate of amylase and protein level of TNF-α (P<0.01), as well as the expression levels of p-p38 MAPK and NF-κB (P<0.01).Cerulein induced nuclear translocation of p-p38 MAPK.Compared with cerulein group, the secretion rate of amylase and protein level of TNF-α in SB203580 group decreased significantly (P<0.01).The expression of p-p38 MAPK and NF-κB also decreased greatly (P<0.05).Nuclear translocation of p-p38 MAPK was inhibited by SB203580.CONCLUSION: The p38 MAPK pathway involves in cerulein-induced pancreatic inflammatory response via regulating NF-κB.     

Involvement of caspase-3 and p38MAPK in allogeneic CD8+T cell-induced apoptosis of vascular endothelial cells

AIM: To investigate the function of caspase-3 and mitogen-activated protein kinases (MAPKs) in allogeneic CD8+T cell-induced apoptosis of vascular endothelial cells. METHODS: Allogeneic CD8+T cells were isolated from PBMC by positive selection using magnetic beads coated with anti-CD8 antibody. After cocultured with allogeneic CD8+T cells, apoptosis of human umbilical vein endothelial cells (HUVECs) and human dermal microvascular endothelial cells (HDMECs) were detected by AnnexinV-FITC labeling. Western blotting was used to examine the change of MAPK and caspase-3 expression in the vascular endothelial cells. The influence of SB203580 (inhibitor of p38MAPK), SP600125 (inhibitor of JNK), PD98059 (inhibitor of ERK), Z-DEVD-FMK (a caspase-3-specific peptide inhibitor) on apoptosis was also examined. RESULTS: At 24 h and 48 h time-point, the apoptosis rates of HUVECs were 41.7%±10.1% and 29.4%±8.3%, respectively (P<0.01, vs untreated HUVECs); the apoptosis rates of HDMECs were 28.9%±7.2% and 15.2%±4.8%, respectively (P<0.01, vs untreated HDMECs). These effects were largely prevented by Z-DEVD-FMK and SB203580 (P<0.05). Allogeneic CD8+T cells enhanced cleavage of caspase-3 and led to p38MAPK phospholation. CONCLUSION: Caspase-3 and p38MAPK mediate allogeneic CD8+T cells-induced apoptosis of vascular endothelial cells.     

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

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

Role of p38 MAPK in cyclic mechanical stretch induced HMGB1 expression in alveolar macrophages

AIM: To investigate the role of p38 mitogen-activated protein kinase (MAPK) in cyclic mechanical stretch induced the expression of high mobility group box 1 protein (HMGB1) in alveolar macrophages (AMs). METHODS: AMs were cultured and seeded at 1×108 cells/L in 6-well Bioflex cell culture plates. Subsequently, the cells were exposed to cyclic mechanical stretch at 20% (group B) elongation using Flexercell 4000T cell stretching unit. In group C, cells were pre-treated with SB203580 (40 μmol/L) for 2 h before mechanical stretch. Group A served as control. The expression of HMGB1 mRNA in alveolar macrophages was detected by RT-PCR. p38 MAPK activity and the expression of HMGB1 protein were measured by Western blotting analysis. RESULTS: The expression of HMGB1 mRNA and protein, and the activity of p38 MAPK in AMs were significantly increased in group B than those in group A (P<0.05). SB203580, an inhibitor of p38 MAPK, significantly inhibited the inducing effect of mechanical stretch (P<0.05). CONCLUSION: Mechanical stretch regulates the expression of HMGB1 mRNA and protein in alveolar macrophages by activating p38 MAPK signal pathway.     

p38 MAPK specific inhibitor SB203580 down-regulates acute pulmonary thromboembolism-induced pulmonary artery hypertension and monocyte chemoattractant protein-1 in rats

AIM：To explore the hypothesis that initiation of pulmonary hypertension involves the up-regulation of monocyte chemoattractant protein-1 (MCP-1) in acute pulmonary thromboembolism (PTE), and to evaluate the role of p38 mitogen-activated protein kinase (MAPK) in this process. METHODS：One hundred and fifty male SD rats were randomly divided into five groups (n=30): normal control group, solvent control group, acute PTE group, acute PTE plus SB203580 (a p38 MAPK specific inhibitor) pretreatment group and acute PTE plus C1142 (a rodent chimeric monoclonal antibody neutralizing rat MCP-1) pretreatment group. Thirty rats in each group were further divided into 1, 4 and 8 h subgroups (n=10). A rat model of acute PTE was established by infusion of an autologous blood clot into the pulmonary artery through a polyethylene catheter. SB203580 or C1142, dissolved in 1% dimethyl sulfoxide (DMSO), was administered to the animals through caudal vein 1 h prior to the beginning of acute PTE modeling. Rats in normal control group and solvent control group were injected with normal saline and 1% DMSO, respectively. The mean pulmonary artery pressure (MPAP) and the mRNA and protein expression of MCP-1 were measured at each time point. RESULTS：Acute PTE elicited significant increase in MPAP, and up-regulated the expression of MCP-1. Pretreatment with SB203580 or C1142 significantly reduced MPAP, and down-regulated the expression of MCP-1. CONCLUSION：These findings suggest that MCP-1 is involved in the formation of acute PTE-induced pulmonary hypertension, and SB203580 down-regulates the expression of MCP-1 via p38 MAPK signaling pathway, thus attenuating pulmonary hypertension.     

Role of p38MAPK activation in high glucose-induced collagen Ⅲ synthesis in normal rat kidney tubular epithelial cells NRK52E

AIM: To study the role of p38 mitogen-activated protein kinase (p38MAPK) activation in high glucose-induced collagen Ⅲ synthesis in NRK52E cells. METHODS: Normal rat tubular epithelial cell line NRK52E was cultured in D-glucose of different concentrations, pretreated with SB203580 and collected at different time points. The levels of phospho-p38MAPK and extracellular matrix collagen Ⅲ were examined by Western blotting. RESULTS: The activation of p38MAPK was shown to be dependent upon D-glucose concentration and the time-course. Pretreatment with SB203580 blocked p38MAPK activation induced by high concentration of D-glucose in NRK52E cells. CONCLUSIONS: The activation of p38MAPK induced by high concentration of glucose may play a role in diabetic interstital renal fibrosis. SB203580 has a potential value of clinical applications in the prevention and treatment of diabetic nephropathy.     

Signaling mechanism of dendritic cell maturation stimulated by uric acid

AIM: To investigate the effect of uric acid on the signal molecule expression involved in MAPKs and NF-κB pathways during the maturation of dendritic cells (DCs). METHODS: DCs were obtained from murine bone-marrow and cultured in vitro. After the immature DCs were stimulated with uric acid (200 mg/L) and NF-κB inhibitor PDTC, or MAPKs inhibitors SB203580, PD98059 or SP600125 for 15 min, 30 min or 45 min, the cytoplasmic and nuclear extracts of the cells were collected and were subject to immunoblot analysis with the antibodies specific for NF-κB p65 or phosphorylated forms of p38, ERK1/2 and JNK. The cell lysates from DCs treated with LPS or DMSO served as controls. After treated with uric acid and PDTC, SB203580, PD98059 or SP600125 for 48 h, DCs were collected. The cell surface markers were analyzed by flow cytometry. The production of IL-12 p70 in the culture supernatants was detected by ELISA. RESULTS: Within 15 min of uric acid conditioning in the immature DCs, increased expression of NF-κB p65 and the phosphorylation of p38, ERK1/2 and JNK in the nuclear or cytoplasmic extracts of DCs were observed. The expression of these proteins reached their peak at 30 min after stimulation. Pretreatment of DCs with PDTC, SB203580, SP600125 or PD98059 blocked the expression of NF-κB p65 and phosphorylation of p38, ERK1/2 and JNK in response to uric acid stimulation. Treatment of DCs with SB203580, SP600125 or PDTC reduced the uric acid-induced up-regulation of CD83, CD86 and IA/IE, and inhibited the effect of uric acid on the secretion of IL-12 p70 (P<0.05 or P<0.01). SB203580 and PDTC possessed a significant inhibitory effect on uric acid. Nevertheless, PD98059 increased the up-regulation of CD83, CD86, IA/IE and IL-12 p70 induced by uric acid (P<0.05). CONCLUSION: Uric acid controls the balance of signal molecule phosphorylation of p38 MAPK, ERK1/2 and JNK, and NF-κB pathways. A possible mechanism of the DCs maturation stimulated by uric acid may be the modulation of the threshold and duration of MAPKs and NF-κB signaling.     

Inhibitory effect of catalpol on inflammation and expression of RAGE in EA.hy926 cells induced by advanced glycation end products

AIM: To investigate the inhibitory effect of catalpol on inflammation in EA.hy926 cells induced by advanced glycation end products(AGEs) and to explore its antioxidant mechanisms.METHODS: Human endothelial cell line EA.hy926 was cultured and randomly divided into control group, catalpol(0.5 mmol/L) group, AGEs group, high-dose(0.5 mmol/L) catalpol+AGEs group, middle-dose(0.25 mmol/L) catalpol+AGEs group and low-dose(0.05 mmol/L) catalpol+AGEs group. Intracellular reative oxygen species(ROS) production was detected by laser scanning confocal microscopy. The levels of monocyte chemotactic protein-1(MCP-1), tumor necrosis factor-α(TNF-α) and vascular cell adhesion molecule-1(VCAM-1) in culture supernatant were detected by commercial ELISA kits. The expression of MCP-1, TNF-α, VCAM-1 and receptor for advanced glycation end products(RAGE) in the EA.hy926 cells were detected by Western blot.RESULTS: In high-dose catalpol+AGEs and middle-dose catalpol+AGEs groups, the generation of ROS was decreased significantly. The levels of MCP-1, TNF-α and VCAM-1, and protein expression of MCP-1, TNF-α and VCAM-1 were significantly lower. The expression of RAGE protein in EA.hy926 cells were significantly inhibited(P<0.05).CONCLUSION: Catalpol effectively inhibits the AGEs-induced oxidative stress and inflammation in EA.hy926 cells, which may be associated with a decrease in the expression of RAGE.     

Lycium barbarum polysaccharides attenuate oxidative stress injury of human endothelium-like EA.hy926 cells induced by hydrogen peroxide

AIM: To study the effect of Lycium barbarum polysaccharides (LBP) on oxidative stress injury of human endothelium-like EA.hy926 cells induced by hydrogen peroxide (H₂O₂). METHODS: The EA.hy926 cell model of oxidative stress injury was established by H₂O₂ treatment. The EA.hy926 cells were divided into 5 groups:control group, damage (H₂O₂ at 50 mmol/L) group, LBP (100 mg/L) group, anti-damage groups (LBP at 50 mg/L, 100 mg/L or 200 mg/L+50 mol/L H₂O₂), and LY294002 (20 μmol/L) group. The effect of LBP at different concentrations on the cell viability of EA.hy926 cells was measured by CCK-8 assay, and the optimum concentration of LBP was screened out. The apoptotic of EA.hy926 cells was analyzed by flow cytometry. Acridine orange/ethidium bromide (AO/EB) staining was used to observe the morphological characteristics of the apoptotic cells. The cell migration ability was detected by scratch method. The levels of nitric oxide (NO) and vascular endothelial growth factor (VEGF) in the cell culture medium were examined. The protein levels of cleaved caspase-3, Bax, Bcl-2, endothelial NO synthase (eNOS), p-eNOS and p-Akt were determined by Western blot. RESULTS: LBP at concentration of 100 mg/L significantly attenuated the injury of EA.hy926 cells induced by H₂O₂, as indicated by improved cell viability (P<0.05) and decreased apoptosis (P<0.05). Pretreatment with LBP elevated the levels of NO and VEGF (P<0.05), and promoted the migration ability of EA.hy926 cells. LBP also increased the Bcl-2/Bax ratio, down-regulated the protein level of cleaved caspase-3, and up-regulated the protein levels of eNOS and p-eNOS. The protective effect of LBP were abolished by pretreatment of the EA.hy926 cells with the inhibitor of PI3K (P<0.05). As a result, the protein level of p-Akt was down-regulated, and the level of NO was also significantly reduced. CONCLUSION: LBP has protective effect on H₂O₂ -induced EA.hy926 cells by attenuating apoptosis of the cells. The mechanism is closely related to the activation of PI3K/Akt/eNOS signaling pathway.     

Exposure to fine particulate matter induces vascular smooth muscle cell proliferation and migration via p38 MAPK signaling pathway

AIMTo study the effects of fine particulate matter (PM2.5) on the proliferation and migration ability of human vascular smooth muscle cells (HVSMCs). METHODSHVSMCs were divided into control group and different concentrations (6.25, 12.5 and 25 mg/L) of PM2.5 groups. HVSMCs were treated with PBS or PM2.5 accord?ing to the group setting. The proliferation was measured by CCK-8 assay and EdU staining method, while the migration ability was detected by scratch assay and Transwell assay. The phosphorylation level of p38 MAPK signaling molecules was determined by Western blot. RESULTSCompared with control group, PM2.5 exposure significantly promoted the proliferation and migration ability of HVSMCs, especially at the dose of 12.5 mg/L(P<0.01). The results of Western blot showed that exposure to PM2.5 at 12.5 mg/L up-regulated the phosphorylation level of p38 MAPK rapidly in the HVSMCs, which peaked at 20 min incubation and kept at a relative high level until 60 min incubation. Pretreatment with SB203580, a p38 MAPK specific inhibitor, blocked the proliferation and migration ability induced by PM2.5(P<0.01). CONCLUSION Exposure to PM2.5 activates HVSMCs by promoting the proliferation and migration ability, and the p38 MAPK signaling pathway may be involved in this process.     

Expression of Smoothened and its role in endothelial cells in synovial tissues of rheumatoid arthritis

AIM: To investigate the expression of Sonic Hedgehog signaling pathway-associated factor Smoothened (Smo) and its role in endothelial cells in synovial tissue of active rheumatoid arthritis (RA). METHODS: Smo expression in synovial tissue from 4 RA patients and 4 patients with trauma or meniscal injury (without arthritis, used for control) was detected by the method of immunohistochemistry. Human umbilical vein endothelial cell line EA.hy926 was used as the model of synovial vascular endothelial cells. The expression of Smo was detected by Western blotting after TNF-α treatment. The small interfering RNA (siRNA) specifically targeting Smo gene was synthesized and transfected into EA.hy926 cells. The interference efficiency of the siRNA on the production of Smo protein was determined by Western blotting. The cells were treated with TNF-α and actinomycin D (ActD) 24 h after siRNA transfection. The cell survival rate was determined by CCK-8 assay and the apoptotic rate was examined by flow cytometry. RESULTS: Smo was highly expressed in synovial tissue from active RA patients, especially in endothelial cells as compared with control group. TNF-α significantly increased the protein expression of Smo in EA.hy926 cells. EA.hy926 cells transfected with Smo-siRNA showed a significant decrease in the cell viability with the cell survival rate of (24.30±0.45)% and the apoptotic rate of (48.00±1.96)%, as compared with those in negative control group ［(36.86±0.62）% and （31.70±0.82）%, respectively］. CONCLUSION: Smo may play a role in the regulation of apoptosis in endothelial cells in RA synovium.     

Effect of p38 MAPK on cisplatin-induced renal tubular cell apoptosis

AIM:To investigate the role of p38 MAPK in cisplatin-induced rat renal proximal tubular cell (RPTC) apoptosis. METHODS:To determine the optimal concentration of cisplatin to induce RPTC apoptosis, the cells were treated with 0, 5, 10 and 20 μmol/L cisplatin for 24 h, and then the cell lysates were collected for Western blot analysis of cleaved PARP, p38 and phosphor ylated p38 (p-p38). To determine the role of p38 MAPK in cisplatin-induced RPTC apoptosis, the cells were divided into control group, cisplatin group (the cells were treated with cisplatin for 24 h) and cisplatin+p38 MAPK inhibitor group (the cells were treated with p38 MAPK inhibitor SB203580 for 1 h, and then treated with cisplatin for another 24 h). The morphological changes of apoptotic cells were observed under phase-contrast fluorescence microscope. The apoptotic rate of the cells were analyzed by flow cytometry. The caspase activity of RPTC lysates was examined using Ac-DEVD-AFC kit. The protein levels of p-p38, p38, cleaved PARP and cleaved caspase-3 were determined by Western blot. The pH value of extracellular environment of the cells was measured by pH meter. RESULTS:Cisplatin at 20 μmol/L obviously induced apoptosis of RPTC. The p38 MAPK was phosphorylated and its phosphorylation peaked at 15 min after cisplatin treatment. The apoptotic rate of RPTC was 12.08% after cisplatin induction. Cisplatin treatment also enhanced caspase activity, and increased cleavage of PARP and caspase-3 proteins (P<0.05). The p38 MAPK inhibitor SB203580 effectively inhibited the phosphorylation of p38 MAPK, down-regulated the RPTC apoptosis rate and caspase activity, and reduced the cleavage of PARP and caspase-3 proteins. The pH value change in RPTC culture medium was also inverted by SB203580. CONCLUSION:The phosphorylation of p38 MAPK is involved in cisplatin-induced apoptosis of RPTC. The apoptosis induced by cisplatin results in the change of acidic extracellular environment, which is inhibited by p38 MAPK inhibitor SB203580.     

Calreticulin is involved in the protection of hypoxic preconditioning against cardiomyoblast H9c2 cell oxidative injury

AIM: To investigate whether hypoxic preconditioning (HPC) protects cardiomyoblast H9c2 cells against oxidative injury, and to discuss whether calreticulin (CRT) contribute to this protection through p38 MAPK signaling pathway. METHODS: Cardiomyoblast H9c2 cells were randomly divided into eight groups as follows: hydrogen peroxide stress (H₂O₂); brief hypoxic exposure of 20 min to simulate hypoxic preconditioning (HPC); 20 min of hypoxic exposure followed by 24 h of normoxic reoxygenation before hydrogen peroxide stress (HPC+H₂O₂), SB203580 (the specific inhibitors of p38 MAPK)+HPC+H₂O₂, antisense oligonucleotides transfection of calreticulin (AS), AS+H₂O₂, AS+HPC+H₂O₂ and control. Morphological studies, estimation of lactate dehydrogenase (LDH) leakage and flow cytometry were employed to assess the cell apoptosis and necrosis. RT-PCR and Western blotting analysis was used to detect calreticulin expression and phosphorylation of p38 MAPK. RESULTS: The results obtained are as follows: (1) HPC relieved cell injury caused by H₂O₂. Compared with those in H₂O₂ group, apoptosis rate and LDH leakage in culture medium in HPC + H₂O₂ group decreased 13.4% and 44.0%, respectively (P<0.05), and cell survive rate increased 12.7% (P<0.05). SB203580, a selective p38 MAPK inhibitor presented before HPC, eliminated the cytoprotection of HPC. Compared with HPC+H₂O₂ group, apoptosis rate and LDH leakage increased 5.4% and 45.0%, respectively (P<0.05), and cell survive rate decreased 5.0%(P<0.05). (2) Brief hypoxia intimating HPC resulted in mild CRT up-regulation (1.4-fold increased vs control group, P<0.05), but this up-regulation was lower than that of 3.6-fold increase induced by oxidative stress. HPC relieved the over-expression of CRT induced by H₂O₂ (26% decreased vs H₂O₂ group, P<0.05). (3) Transfection of antisense oligonucleotides of CRT before HPC reduced cytoprotection against oxidative stress. Correlative analysis indicated that mild up-regulation of CRT induced by HPC was positively correlated with survive rate (r=0.8573, P<0.05). (4) SB203580 suppressed CRT up-regulation (the expression of CRT decreased 38% or 23%, vs HPC+H₂O₂ group or HPC group, respectively). CONCLUSION: These results suggest that hypoxic preconditioning up-regulates calreticulin expression through p38 MAPK signaling pathway and protects cardiomyoblast H9c2 cells against oxidative injury.     

Role of p38 MAPK-HSP27 signaling pathway in rat acute lung injury induced by lipopolysaccharide

AIM: To observe the role of p38 mitogen-activated protein kinase (p38 MAPK)-heat-shock protein 27 (HSP27) signaling pathway in lipopolysaccharide-induced acute lung injury (ALI) in rats. METHODS: Wistar rats were randomly divided into control group, ALI group and ALI+SB203580 group. After the experimental model was established, the rats were sacrificed. The pathological changes of the lung and the changes of F-actin and G-actin in the endothelial cells were observed. The ratio of wet weight to dry weight (W/D) of the lung tissues was measured. The protein levels in bronchoalveolar lavage fluid (BALF) were detected. The levels of IL-6 and TNF-α in serum and BALF were tested. The concentrations of p-p38 and p-HSP27 in the lung were determined. RESULTS: In ALI group, the protein levels in BALF and W/D ratio of the lung increased significantly at 2 h. The levels of TNF-α and IL-6 in serum and BALF began to increase at 2 h, which had significant difference as compared with control group. Aleolar epithelial swelling, alveolar walls widening, alveolar interstitial and cavity edema, and the exudation of alveolar inflammation cells, red blood cells and protein were observed in ALI group. The protein levels in BALF and W/D ratio of the lung in ALI+SB203580 group were much less than those in ALI group. The exudation of alveolar inflammation cells, red blood cells and protein, and the interstitial and alveolar edema in ALI+SB203580 group alleviated as compared with ALI group. The expression of p-p38 MAPK and p-HSP27 in the lung at 2 h in ALI group was higher than that in control group. F-actin expression in ALI group obviously increased than that in control group at time points of 0 h and 8 h. Compared with ALI group, the expression of p-HSP27 and F-actin in ALI+SB203580 group was reduced. CONCLUSION: Lipopolysaccharide activates p38 MAPK-HSP27 signaling pathway and induces lung injury. Blockage of p38 MAPK-HSP27 signaling pathway may reduce lung injury.