JNK mediates TNF-α or H2O2-induced insulin resistance in 3T3-L1 adipocytes

AIM: To study the role of c-Jun NH2-terminal kinase (JNK) in the development of insulin resistance induced by tumor necrosis factor-α (TNF-α) or H2O2 in 3T3-L1 adipocytes. METHODS: Differentiated 3T3-L1 adipocytes were pretreated with JNK1 small interfering RNA (siRNA) or JNK inhibitor SP600125, then exposed to 1 nmol/L of TNF-α or micromolar H2O2 generated by adding glucose oxidase (50 U/L) to the medium for 12 h. The cellular glucose uptake was determined by radioactive method. RESULTS: Compared to control adipocytes, 12 h incubation with TNF-α or H2O2 led to 50%-55% reduction (P<0.01) of the insulin-dependent glucose uptake. JNK1 siRNA transfection significantly inhibited JNK1 expression and blocked the TNF-α or H2O2-induced impairments of cellular glucose uptake. Pretreatment with SP600125 (20 μmol/L) resulted in significant increases in insulin-stimulated glucose uptakes in both TNF-α (66%) and H2O2 (62%) treated adipocytes (P<0.01). CONCLUSION: JNK plays a key role in TNF-α or H2O2 induced insulin resistance in 3T3-L1 adipocytes, and inhibition of JNK over-activation may be a new therapeutic target for insulin resistance.     

Effects of TNF-α-mediated insulin resistance on INSIG2 and SCAP expressions in vivo

AIM: To investigate the effects of TNF-α induced insulin resistance (IR) on INSIG1, INSIG2, SCAP and SREBP expressions in mice. METHODS: Male C57BL/6J mice were randomly divided into 4 groups. The mice were given an intraperitoneal injection of TNF-α (6 μg·kg-1·d-1; 3 μg·kg-1·d-1 and 1 μg·kg-1·d-1) and saline (NC group) twice daily for 7 d. The insulin sensitivity and glucose metabolism in awaken mice were evaluated by intravenous glucose tolerance test (IVGTT). The mRNA expression and protein levels of gene were measured by RT-PCR and Western blotting. RESULTS: After TNF-α treatment, fasting blood glucose (FBG), plasma insulin and free fatty acids (FFA) were significantly elevated in TNF-α (6 μg·kg-1·d-1) group compared to NC, TNF-α (1 μg·kg-1·d-1) and TNF-α (3 μg·kg-1·d-1) groups (P<0.01 and P<0.05, respectively). There was a lower glucose tolerance in TNF-α (6 μg·kg-1·d-1) group than that in other three groups during IVGTT. In TNF-α (6 μg·kg-1·d-1) group, the insulin release of glucose-stimulation was higher than that in NC and TNF-α (1 μg·kg-1·d-1) groups (P<0.01 and P<0.05). The INSIG2 mRNA expression of adipose tissues in TNF-α (6 μg·kg-1·d-1) group was significantly increased compared with NC group (P<0.01), and INSIG2 protein levels were also increased (P<0.05). In TNF-α treatment mice, SCAP mRNA level in adipose tissues was significantly up-regulated than that in the controls (P<0.05). The mRNA expressions of INSIG1 and SREBP1 in two groups were not significantly changed (P>0.05). CONCLUSION: In TNF-α induced insulin resistance, INSIG2 and SCAP may be involved in the pathways of lipid metabolism.     

Effects of immune-activated platelets and LDL on expression and activity of COX-2 and PPAR-α in HUVECs

AIM: To observe the effect of immune-activated platelets and low-density lipoprotein cholesterol (LDL) on the expression and activity of cyclooxygenase-2 (COX-2) and peroxisome proliferator activated receptor α (PPAR-α) in human umbilical vein endothelial cells (HUVECs) treated with activated platelets and LDL. METHODS: The platelets were activated by ADP. The co-culture system of HUVECs with immune activated platelets and/or LDL were established. The activity of COX-2 and expression of PPAR-α at mRNA and protein levels in HUVECs were detected by RT-PCR and Western blotting. The concentration of PGE2 was measured by ELISA for representing the COX-2 activity. The PPAR-α activity was determined by a nuclear factor assay kit. RESULTS: The COX-2 activity and mRNA expression of PPAR-α, the protein levels of COX-2 and PPAR-α and PGE2 concentration in activated platelets group were significant higher than those in un-activated platelets group (all P<0.01). No difference of PPAR-α binding activity was observed between two groups. LDL didnt affect the COX-2 activity and PPAR-α expression, but significantly promoted the stimulating effect of immune-activated platelets. CONCLUSION: Immune-activated platelets significantly promote COX-2 activity and PPAR-α expression in HUVECs, but dont change the PPAR-α binding activity. LDL at general concentration does not affect the expression and activity of COX-2 and PPAR-α, but promote the effect of activated platelets on HUVECs.     

Effects of curcumin on actinomycin D/TNF-α-induced injury in PC12 cells and rat hippocampal neurons

AIM: To study the possible mechanism of curcumin on actinomycin D (ActD)/tumor necrosis factor α (TNF-α)-induced injury in PC12 cells and rat hippocampal neurons. METHODS: PC12 cells were divided into control group, TNF-α group, ActD group, curcumin group, ActD/TNF-α group and curcumin+ActD/TNF-α group. The cells were cultured for 24 h. Inverted fluorescence microscopy was used to observe the morphological changes of the cells in each group. Annexin V/PI double staining was applied to analyze the apoptosis of PC12 cells. The level of intracellular Ca²⁺ was detected by Fluo-3 AM staining. Rat hippocampal slices were prepared and divided into the same groups as the PC12 cells. Extracellular microelectrode recording technique was used to observe and calculate the changes of long-term potentiation (LTP) in different groups. RESULTS: Apoptosis of PC12 cells was induced by ActD/TNF-α. Curcumin protected the PC12 cells from ActD/TNF-α-induced apoptosis (P<0.05). ActD/TNF-α increased the intracellular Ca²⁺ concentration. Curcumin significantly reduced ActD/TNF-α-induced apoptosis by decreasing the intracellular Ca²⁺ concentration (P<0.05), inversed the effect of ActD/TNF-α on LTP in hippocampal slices, and improved the synaptic plasticity (P<0.05). CONCLUSION: Curcumin protects ActD/TNF-α-induced neuronal damage by depressing the intracellular Ca²⁺ concentration and maintaining the homostasis of intracellular calcium.     

Effect of inhibiting nuclear factor-kappa B on TNF-α-induced expression of angiotensinogen and production of angiotensinⅡ in glomerular mesangial cells

AIM: To study the effect of inhibiting nuclear factor-kappa B (NF-κB) activity on the expression of angiotensinogen (AGT) and the production of angiotensinⅡ (AngⅡ) induced by tumor necrosis factor-α (TNF-α) in glomerular mesangial cells (MCs) of SD rats. METHODS: The MCs of SD rats were isolated and divided into three groups as follows: control; MCs treated with TNF-α, and the MCs treated with TNF-α + pyrrolidinedithiocarbamate (PDTC). The activity of nuclear factor-kappa B was measured by electrophoretic mobility shift assay. The expression of AGT was determined by RT-PCR for mRNA and Western blotting for protein. The concentration of angiotensinⅡ in supernatant was measured by RIA. RESULTS: The NF-κB activity in the MCs treated with TNF-α (20.67±9.14)×102 μg/cell was significantly higher than that in control cells ［(8.25±4.35)×102 μg/cell, P<0.01］ and the MCs treated with TNF-α+PDTC ［(7.20±4.57)×102 μg/cell, P<0.01］, and no significant difference was found between control and the MCs treated with TNF-α＋PDTC (P>0.05). The AGT mRNA level in the MCs treated with TNF-α (0.27±0.05) was higher than that in the control cells (0.20±0.05, P<0.05), and no significant difference was observed when compared with that in the MCs treated with TNF-α＋PDTC (0.22±0.06, P>0.05). The expression of AGT protein in the MCs treated with TNF-α (0.60±0.19) μg/cell was higher than that in the control ［(0.37±0.15)μg/cell, P＜0.05］ and the MCs treated with TNF-α＋PDTC ［(0.37±0.17)μg/cell, P<0.05］, and no significance was found between the MCs treated TNF-α＋PDTC and the control (P>0.05). The AngⅡ level in supernatant of cultured MCs treated with TNF-α ［(9.73±2.38)×10-5 ng·L-1/cell］ was significantly higher than that in the control ［(7.50±1.51)×10-5 ng·L-1/cell, P<0.05］ and in the MCs treated with TNF-α＋PDTC ［(6.94±1.46)×10-5 ng·L-1/cell, P<0.05］, however, the difference between the MCs treated with TNF-α＋PDTC and the control was of no significance (P>0.05). CONCLUSION: TNF-α activates the NF-κB in glomerular MCs, induces the AGT expression and the production of AngⅡ. Inhibition of NF-κB decreases the AGT expression and the production of AngⅡ. Therefore, the effects of TNF-α on AGT and AngⅡ may be mediated by NF-κB.     

Effects of miR-92a and miR-19b on insulin gene expression in mouse pancreatic β-cells

AIM To investigate the effect of microRNA-92a （miR-92a） and microRNA-19b （miR-19b） on the insulin expression in mouse pancreatic β-cells. METHODS The relative expression levels of endogenous miR-92a and miR-19b in mouse insulinoma MIN6 cells were detected by qPCR. The MIN6 cells were divided into control group, and experimental groups I and II, with 3 samples in each group, and transfected with negative control miRNA （NC）, miR-92a and miR-19b, respectively. The over-expression of the miRNAs was detected by qPCR. The morphological changes and viability of the cells were detected by optical microscopy and CCK8 assay, respectively. The expression of insulin was detected by qPCR, Western blot and immunofluorescence. The possible mechanisms of miR-92a and miR-19b regulating insulin expression were analyzed by bioinformatics prediction, dual-luciferase reporter assay, and Western blot. RESULTS Compared with the adult pancreatic progenitor cells, the expression of endogenous miR-92a and miR-19b in the MIN6 cells was decreased significantly （P<0.05）. Over-expression of miR-92a and miR-19b had no effect on the viability of MIN6 cells, but inhibited the expression of insulin at mRNA and protein levels. miR-19b significantly inhibited the luciferase activity of NeuroD1 3′UTR and the protein expression of NeuroD1 （P<0.05）. miR-92a had a fine-tuning effect on the luciferase activity of NeuroD1 3′UTR and the protein expression of NeuroD1. CONCLUSION miR-92a and miR-19b inhibit the insulin expression in mouse pancreatic β-cells.     

Effects of metformin on nuclear factor-κB expression and serum high sensitivity C-reactive protein level in atherosclerosis model of rabbit

AIM: To investigate the effects of metformin on nuclear factor-κB (NF-κB),its inhibitor IκB,and the level of serum high sensitivity C-reactive protein (hs-CRP) in rabbits.METHODS: 24 New Zealand male rabbits were randomly divided into control group,atherosclerosis (AS) group and metformin (Met) group.AS group and Met group were made as models by cholesterolenriched diets feeding and vascular intimal immunologic injury.The AS model was confirmed by high frequency ultrasound.Met group were given metformin 150 mg·kg-1·d-1 for 8 weeks.At the end of experiment,serum hs-CRP and serum lipids in all three groups were detected.Immunohistochemistry and Western blotting technique were applied to detect the expression of nucleus NF-κB p65 and cytoplasma IκBα in aorta in all three groups.RESULTS: Compared to normal control group,the level of serum hs-CRP was elevated (1.27±0.43 vs 3.96±0.63,P<0.01),the expression of nucleus NF-κB p65 increased significantly (P<0.01) while the expression of IκBα reduced significantly (P<0.01).Compared to AS group,metformin significantly reduced the level of serum hs-CRP (2.79±0.40 vs 3.96±0.63,P<0.05) and the expression of nucleus NF-κB p65 (P<0.01),and increased the expression of IκBα (P<0.05).CONCLUSION: Metformin inhibits the activation of NF-κB p65 and the degradation of IκBα,and decreases the levels of serum hs-CRP in AS rabbits.These results suggest that metformin exerts direct vascular anti-inflammatory effects.It may be one important mechanism of metformins antiatherogenic properties.     

Differential roles of Gβ/Gαq-PI3K-PKC signaling pathway in the regulation of 3T3-L1 pre-adipocyte differentiation

AIM:To investigate the role of individual protein isoforms in the regulation of 3T3-L1 adipocyte development through detecting temporal patterns of Gβ, Gα/q, phosphorylated phosphoinositide 3-kinase IA and IB isoforms and activated protein kinase C α and ζ subtypes involved in Gβ/Gαq-PI3K-PKC signaling pathway during 3T3-L1 preadipocyte differentiation. METHODS:The cells were induced by 1-methyl-3-isobutylxanthine, dexamethasone and insulin in vitro, and harvested at indicated time points (0 d, 6 h,12 h, 1 d, 3 d, 6 d, 9 d), then the total proteins of these cells were extracted. The expressions of Gβ, Gα/q, p101, phosphorylated p85, p55, p110γ, PKCα and ζ were assayed by Western blotting. RESULTS:(1) Gαq/11 and Gβ increased after induction of differentiation, reaching maxima respectively at 3 d and 1 d when cellular level of Gβ was 1.97±0.16-fold higher and expression of Gαq/11 was 2.34±0.22-fold higher than that in just-confluent (0 d) cells. Subsequently the expression declined. (2) Compared to 0 d, phosphorylated p110γ, p55 and p85 elevated slightly at 12 h, and decreased significantly by the end of the treatment period (9 d) which coincided with maximal differentiation. While the expression of p101 elevated slightly at 12 h, no statistical significance through differentiation was found. (3) Phosphorylated PKCα increased significantly, peaking at 3 d of differentiation. Expression of phosphorylated PKCζ decreased during differentiation and its level 45.52% lower in adipocytes than that in preadipocyte was observed. CONCLUSION:The protein levels elevating at the early stage of differentiation correlate with the time point at which clonal expansion of cells is observed. Phosphorylated p55 and PKCζ decrease in adipocytes than that in preadipocyte, indicating an inhibitory influence upon the late differentiation process.     

Effects of diosmin on changes of TNF-α, IL-1β, IL-6, IL-8 and IL-10 in serum and kidney tissues of rats with kidney ischemia and reperfusion

AIM: To observe the effects of diosmin on the production of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), IL-6, IL-8 and IL-10 in serum and kidney tissues of rats with kidney ischemia and reperfusion (I/R). METHODS: Sprague-Dawley rats (180 in total) were randomly divided into 3 groups including sham operation group (sham),I/R group and diosmin+I/R group (diosmin+I/R). At the end of the experiment, the blood and kidney tissues were obtained and TNF-α, IL-1β, IL-6, IL-8 and IL-10 were detected by ELISA. RESULTS: The levels of TNF-α, IL-1β, IL-6, IL-8 and IL-10 in serum and kidney tissues in I/R group and diosmin+I/R group were significantly higher than those in sham group (P<0.01 or P<0.05). Following the development of the pathologic process, the level of TNF-α, IL-1β, IL-6 and IL-8 was significantly increased in I/R group and diosmin+I/R groups, but the level of IL-10 was significantly decreased in I/R group and significantly increased in diosmin+I/R group. The levels of TNF-α, IL-1β, IL-6 and IL-8 in I/R group was significantly higher than those in diosmin+I/R group (except TNF-α at 1 h in diosmin+I/R group). The level of IL-10 in diosmin+I/R group was significantly higher than that in I/R group (P<0.01 or P<0.05). CONCLUSION: Diosmin not only decreases the production of TNF-α, IL-1β, IL-6 and IL-8, but also promotes the production of anti-inflammatory cytokine IL-10, suggesting that the protective effect of diosmin on kidney I/R injury was associated with anti-inflammatory mechanism.     

Effect of Buyanghuanwu decoction on the expression of ERK2 and CaMKⅡβ in hippocampus tissue and on ability of learning and memory in vascular dementia rats

AIM: To investigate the effect of Buyanghuanwu decoction, a Chinese medicine, on the ability of learning and memory in the rats with vascular dementia (VD) and on the protein expression of extracellular signal-regulated kinase 2(ERK2) and calcium/calmodulin-dependent protein kinase Ⅱβ(CaMKⅡβ) in hippocampus CA1 area.METHODS: The rats were divided into 4 groups: sham group, VD group, VD+Buyanghuanwu decoction group and VD+nimodipine group. The VD rat model was prepared by Pulsinelli's four-vessel occlusion. At 7th day, 14th day or 28th day after operation, the behaviors of the rats were tested by Morris water maze. The morphological changes of the neurons in hippocampus CA1 area were observed by HE staining 30 d after operation. Western blotting was used to observe the protein expression of ERK2 and CaMKⅡβ in the brain tissues of hippocampal CA1 area of the VD rats. RESULTS: Compared with sham group, the pathological changes such as irregular arrangement, coagulation necrosis and obvious deletion in the neurons of hippocampus CA1 area in VD group appeared significantly. The obstacle of learning and memory ability was observed and the protein expression of ERK2 and CaMKⅡβ in hippocampal CA1 area was significantly decreased (P<0.05). Compared with VD group, the neurons in hippocampal CA1 area of VD+Buyanghuanwu decoction group and VD+nimodipine group were in eumorphism, lined up in order, and the structure was close to that in sham group. The ability of learning and memory also significantly improved (P<0.05). The protein expression of ERK2 and CaMKⅡβ in hippocampal CA1 area significantly increased (P<0.05). CONCLUSION: Buyanghuanwu decoction promotes the protein expression of ERK2 and CaMKⅡβ in hippocampus CA1 area to protect the neurons from injury, builds up the synapses and promotes the ability of learning and memory in VD rats.     

Effects of ClC-3 knockdown-induced TNF-α/IL-10 imbalance in rat DRG on voltage-gated sodium channel expression and mechanical allodynia

AIM To investigate the effect of ClC-3 chloride channel/antiporter knockdown in rat dorsal root ganglion (DRG) on voltage-gated sodium channel expression in neurons and mechanical allodynia in rats. METHODS Adeno-associated virus carrying ClC-3 shRNA (AAV-ClC-3 shRNA) was injected intrathecally to knock down ClC-3 expression in DRG tissues of adult SD rats. The mRNA and protein expression levels of ClC-3, cytokines and voltage-gated sodium channels were detected by RT-qPCR, immunofluorescence and Western blot. The mechanical sensitivity was assessed using von Frey hairs and up-down method. RESULTS Intrathecal injection of AAV-ClC-3 shRNA decreased ClC-3 expression in the DRG tissues and induced mechanical allodynia in the rats. Knockdown of ClC-3 up-regulated the expression levels of Nav1.3, Nav1.7, Nav1.8 and Nav1.9 in the DRG tissues. Knockdown of ClC-3 increased tumor necrosis factor-α (TNF-α) and decreased interleukin-10 (IL-10) levels in the DRG tissues. CONCLUSION Knockdown of ClC-3 in rat DRG tissues induces TNF-α/IL-10 imbalance and increases expression of voltage-gated sodium channels, thus contributing to mechanical allodynia.     

Effect of IL-1β and IL-6 on expression of nerve growth factor in human nucleus pulposus cells

AIM: To determine the effect of interleukin-1β(IL-1β)and IL-6 on the expression of nerve growth factor (NGF) by human nucleus pulposus (NP) cells. METHODS: The NP cells from the normal disc of operative patients with scoliosis were isolated, cultured and identified. After 7 days preculture, the NP cells were treated with IL-1β (10 μg/L, 50 μg/L) or IL-6 (10 μg/L, 50 μg/L) for 48 h in the experimental groups and 0.3% PBS was used in the control groups. The expression of NGF was detected by the methods of immunohistochemistry, semi-quantitative RT-PCR and Western blotting.RESULTS: The NP cells were chondrocyte-like cellular morphology with positive staining of toluidine blue, safranine O and anti-collagen II antibody. The NP cells cultured in monolayer showed immunoreactivity to NGF either in control condition or in experimental group. IL-1β and IL-6 up-regulated the mRNA expression of NGF and the protein production of NGF. The effect of this up-regulation was higher by treating with IL-6 than by treating with IL-1β in the same concentration.CONCLUSION: Our results demonstrate that the proinflammatory cytokines IL-1β and IL-6 stimulate the production of NGF in NP cells. The effect of IL-6 is more significant than that of IL-1β.     

Effects of panax notoginseng saponins on content of triglyceride and the mRNA expression of LXRα in steatotic hepatocyte L02

AIM: To study the effects of panax notoginseng saponins (PNS) on the content of triglyceride (TG) and the mRNA expression of liver X receptor α (LXRα) in steatotic hepatocyte L02.METHODS: The cells of hepatocyte L02 were cultured with 50% bovine calf serum for 48 h and a model of steatosis of hepatocytes was established. The appropriate concentrations of PNS on steatotic hepatocytes were detected by MTT assay. The cells were divided into 5 groups: normal control group, model group, spontaneous recovery group, low concentration of PNS group (10 mg/L) and high concentration of PNS group (50 mg/L). Meanwhile, hepatocytes in model group were continuously cultured by RPMI-1640 medium containing 50% bovine calf serum while others were cultured by RPMI-1640 medium containing 10% bovine calf serum. After 24 h, the lipid droplets in the cells stained with oil red O were observed under microscope, the intracellular TG levels were determined by automatic biochemical analyzer and the mRNA expression of LXRα in hepatocytes was examined by RT-PCR. RESULTS: Compared to normal control group, Oil red O staining presented numerous orange-red or red lipid droplets in the cytoplasm of human L02 hepatocytes in model group. The content of TG in model group were significantly increased (P<0.01). After treated with PNS for 24 h, the content of TG in PNS treatment groups was significant decreased than that in spontaneous recovery group (P<0.05), especially in low concentration of PNS group (P<0.01). The accumulation of lipid droplets in low concentration of PNS group was decreased significantly. Compared to normal control group, the mRNA expression of LXRα in model group was significantly up-regulated (P<0.01). Compared to spontaneous recovery group, the mRNA expression of LXRα in PNS treatment groups declined in different levels, especially in low concentration group (P<0.05).CONCLUSION: The deposition of lipid in hepatocytes might be related to the high expression of LXRα mRNA. PNS decreases the content of TG in steatotic hepatocytes and promotes the recovery of hepatocyte steatosis by downregulating the mRNA level of LXRα.     

Effects of arsenic trioxide on activities of MMPs and expression of TIMP-1 and TGF-β1 in skin fibroblasts and polymorphonuclear neutrophils

AIM: To observe the effects of arsenic trioxide (As₂O₃) on activities of matrix metalloproteinases (MMPs), expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and transforming growth factor beta1 (TGF-β₁) in human fibroblast (hFb), and to discuss weather As₂O₃ promotes the healing of chronic skin ulcer through regulating collagen metabolism. METHODS: Zymography was used for testing activity of MMP-9 deriving from rat polymorphonuclear neutrophils (PMNs) and activities of MMP-1, MMP-2 secreted by hFb. Immunocytochemical method was used to determine the expressions of TIMP-1 and TGF-β₁. RESULTS: At the concentration of 50 mg/L, As₂O₃ elevated the activity of MMP-9 (P<0.01). At the concentration of 0.8 mg/L, As₂O₃ increased the activities of MMP-1 and MMP-2 (P<0.01, respectively). After hFb was cultured with As₂O₃ for 6 h, 12 h and 18 h, the expressions of TIMP-1 and TGF-β₁ decreased continuously (P<0.01). CONCLUSION: As₂O₃ elevates the activities of MMP-1, MMP -2 and MMP-9, also inhibits the expressions of TIMP-1 and TGF-β₁, suggesting that arsenic preparation may exert positive effect on healing chronic skin ulcer through regulating collagen metabolism.     

Effects of HIF-1α silencing on expression of p27 and Ki67 in rat hepatoma cell line CBRH-7919

AIM: To study the effect of hypoxia-inducible factor 1α(HIF-1α) silencing on the expression of p27 and Ki67 in rat hepatoma cell line CBRH-7919 under hypoxia. METHODS: Hypoxic condition was induced by CoCl₂ and the expression of HIF-1α was silenced by small interference RNA. HIF-1α-specific RNAi lentiviral vector was constructed. Real-time RT-PCR and Western blotting were used to detect the expression of HIF-1α at mRNA and protein levels in CBRH-7919 cells under hypoxia. The expression of p27 and Ki67 was observed by Western blotting after HIF-1α silencing was performed. The cell cycle of hepatoma cells was detected by flow cytometry. RESULTS: Under hypoxic condition, the expression of HIF-1α at mRNA and protein levels in CBRH-7919 cells increased significantly (P<0.05). HIF-1α silencing significantly reduced the expression of Ki67 but increased the expression of p27 (P<0.05) in CBRH-7919 cells. In transfected cells, the number of cells in G₀/G₁ phase was much higher and that in S phase was much lower than those in the control cells. CONCLUSION: Hypoxia induces the expression of HIF-1α. HIF-1α silencing can regulate the proliferation of hepatoma cells through reducing the expression of Ki67 and increasing the expression of p27.