Hepatocyte growth factor enhances the ability of dental pulp stem cells to ameliorate atherosclerosis in apolipoprotein E-knockout mice

BACKGROUND Atherosclerosis(AS),a chronic inflammatory disease of blood vessels,is a major contributor to cardiovascular disease.Dental pulp stem cells(DPSCs)are capable of exerting immunomodulatory and anti-inflammatory effects by secreting cytokines and exosomes and are widely used to treat autoimmune and inflam-mation-related diseases.Hepatocyte growth factor(HGF)is a pleiotropic cytokine that plays a key role in many inflammatory and autoimmune diseases.AIM To modify DPSCs with HGF(DPSC-HGF)and evaluate the therapeutic effect of DPSC-HGF on AS using an apolipoprotein E-knockout(ApoE-/-)mouse model and an in vitro cellular model.METHODS ApoE-/-mice were fed with a high-fat diet(HFD)for 12 wk and injected with DPSC-HGF or Ad-Null modified DPSCs(DPSC-Null)through tail vein at weeks 4,7,and 11,respectively,and the therapeutic efficacy and mechanisms were analyzed by histopathology,flow cytometry,lipid and glucose measurements,real-time reverse transcription polymerase chain reaction(RT-PCR),and enzyme-linked immunosorbent assay at the different time points of the experiment.An in vitro inflammatory cell model was established by using RAW264.7 cells and human aortic endothelial cells(HAOECs),and indirect co-cultured with supernatant of DPSC-Null(DPSC-Null-CM)or DPSC-HGF-CM,and the effect and mechanisms were analyzed by flow cytometry,RT-PCR and western blot.Nuclear factor-κB(NF-κB)activators and inhibitors were also used to validate the related signaling pathways.RESULTS DPSC-Null and DPSC-HGF treatments decreased the area of atherosclerotic plaques and reduced the expression of inflammatory factors,and the percentage of macrophages in the aorta,and DPSC-HGF treatment had more pronounced effects.DPSCs treatment had no effect on serum lipoprotein levels.The FACS results showed that DPSCs treatment reduced the percentages of monocytes,neutrophils,and M1 macrophages in the peripheral blood and spleen.DPSC-Null-CM and DPSC-HGF-CM reduced adhesion molecule expression in tumor necrosis factor-αstimulated HAOECs and regulated M1 polarization and inflammatory factor expression in lipopolysaccharide-induced RAW264.7 cells by inhibiting the NF-κB signaling pathway.CONCLUSION This study suggested that DPSC-HGF could more effectively ameliorate AS in ApoE-/-mice on a HFD,and could be of greater value in stem cell-based treatments for AS.

Microvesicles derived from mesenchymal stem cells inhibit acute respiratory distress syndrome-related pulmonary fibrosis in mouse partly through hepatocyte growth factor

BACKGROUND Pulmonary fibrosis is one of the main reasons for the high mortality rate among acute respiratory distress syndrome(ARDS)patients.Mesenchymal stromal cell-derived microvesicles(MSC-MVs)have been shown to exert antifibrotic effects in lung diseases.AIM To investigate the effects and mechanisms of MSC-MVs on pulmonary fibrosis in ARDS mouse models.METHODS MSC-MVs with low hepatocyte growth factor(HGF)expression(siHGF-MSC-MVs)were obtained via lentivirus transfection and used to establish the ARDS pulmonary fibrosis mouse model.Following intubation,respiratory mechanics-related indicators were measured via an experimental small animal lung function tester.Homing of MSC-MVs in lung tissues was investigated by near-infrared live imaging.Immunohistochemical,western blotting,ELISA and other methods were used to detect expression of pulmonary fibrosis-related proteins and to compare effects on pulmonary fibrosis and fibrosis-related indicators.RESULTS The MSC-MVs gradually migrated and homed to damaged lung tissues in the ARDS model mice.Treatment with MSC-MVs significantly reduced lung injury and pulmonary fibrosis scores.However,low expression of HGF(siHGF-MSC-MVs)significantly inhibited the effects of MSC-MVs(P<0.05).Compared with the ARDS pulmonary fibrosis group,the MSC-MVs group exhibited suppressed expression of type I collagen antigen,type III collagen antigen,and the proteins transforming growth factor-βandα-smooth muscle actin,whereas the siHGF-MVs group exhibited significantly increased expression of these proteins.In addition,pulmonary compliance and the pressure of oxygen/oxygen inhalation ratio were significantly lower in the MSC-MVs group,and the effects of the MSC-MVs were significantly inhibited by low HGF expression(all P<0.05).CONCLUSION MSC-MVs improved lung ventilation functions and inhibited pulmonary fibrosis in ARDS mice partly via HGF mRNA transfer.

Hepatocyte growth factor promotes retinal pigment epithelium cell activity through MET/AKT signaling pathway

AIM:To explore the effects of hepatocyte growth factor(HGF)on retinal pigment epithelium(RPE)cell behaviors.METHODS:The human adult retinal pigment epithelial cell line-19(ARPE-19)were treated by HGF or mesenchymalepithelial transition factor(MET)inhibitor SU11274 in vitro.Cell viability was detected by a Cell Counting Kit-8 assay.Cell proliferation and motility was detected by a bromodeoxyuridine incorporation assay and a wound healing assay,respectively.The expression levels of MET,phosphorylated MET,protein kinase B(AKT),and phosphorylated AKT proteins were determined by Western blot assay.The MET and phosphorylated MET proteins were also determined by immunofluorescence assay.RESULTS:HGF increased ARPE-19 cells’viability,proliferation and migration,and induced an increase of phosphorylated MET and phosphorylated AKT proteins.SU11274 significantly reduced cell viability,proliferation,and migration and decreased the expression of MET and AKT proteins.SU11274 suppressed HGF-induced increase of viability,proliferation,and migration in ARPE-19 cells.Additionally,SU11274 also blocked HGF-induced phosphorylation of MET and AKT proteins.CONCLUSION:HGF enhances cellular viability,proliferation,and migration in RPE cells through the MET/AKT signaling pathway,whereas this enhancement is suppressed by the MET inhibitor SU11274.HGF-induced MET/AKT signaling might be a vital contributor of RPE cells survival.

Hepatocyte Growth Factor Gene-modified Bone Marrow-derived Mesenchymal Stem Cells Transplantation Promotes Angiogenesis in a Rat Model of Hindlimb Ischemia

Summary： Angiogenic gene therapy and cell-based therapy for peripheral arterial disease （PAD） have been studied intensively currently. This study aimed to investigate whether combining mesenchymal stem cells （MSCs）transplantation with ex vivo human hepatocyte growth factor （HGF） gene transfer was more therapeutically efficient than the MSCs therapy alone in a rat model of hindlimb ischemia. One week after establishing hindlimb ischemia models, Sprague-Dawley （SD） rats were randomized to receive HGF gene-modified MSCs transplantation （HGF-MSC group）, untreated MSCs transplantation （MSC group）, or PBS injection （PBS group）, respectively. Three weeks after injection, angiogenesis was significantly induced by both MSCs and HGF-MSCs transplantation, and capillary density was the highest in the HGF-MSC group. The number of transplanted cell-derived endothelial cells was greater in HGF-MSC group than in MSC group after one week treatment. The expression of angiogenic cytokines such as HGF and VEGF in local ischemic muscles was more abundant in HGF-MSC group than in the other two groups. In vitro, the conditioned media obtained from HGF-MSCs cultures exerted proproliferative and promigratory effects on endothelial cells. It is concluded that HGF gene-modified MSCs transplantation therapy may induce more potent angiogenesis than the MSCs therapy alone. Engraftment of MSCs combined with angiogenic gene delivery may be a promising therapeutic strategy for the treatment of severe PAD.

HEPATOCYTE GROWTH FACTOR PROTECTS AGAINST APOPTOSIS INDUCED BY ADVANCED GLYCATION END PRODUCTS IN ENDOTHELIAL CELLS

Objective To investigate the effects of hepatocyte growth factor(HGF)on vascular endothelial cells apoptosis induced by advanced glycation end products(AGEs)and its possible mechanism. Methods Human umbilical vein endothelial cells(HUVECs)were cultured in vitro and intervened by different concentrations of AGEs and HGF.The cell inhibitory rates of each group with different culture time(12, 24, 48, and 72 hours)were measured by methyl thiazolyl tetrazolium(MTT)assay. The early stage apoptosis was detected by flow cytometry with Annexin V-FITC/PI double staining, morphology of cell apoptosis was observed by hoechst 33258 fluorescence staining, and the expression of apoptosis-associated genes Bax and Bcl-2 were determined by Western blotting.The activity of caspase-3 was detected by enzyme-linked immunosorbent assay (ELISA).Results Morphological observation indicated that high concentration of AGEs induced characteristic apoptotic changes in HUVECs.Within a certain concentration range, HUVECs apoptosis inducing rates by AGEs were in both dose- and time-dependent manners.HGF significantly inhibited the apoptosis of HUVECs induced by AGEs (P< 0.05).AGEs significantly promoted expression of Bax protein, but not Bcl-2.Whereas HGF significantly promoted the expression of Bcl-2(P<0.01)and decreased the activity of caspase-3(P<0.05)without affecting Bax level.Conclusions AGEs can induce the apoptosis of endothelial cells in vitro.HGF may effectively attenuate AGEs-induced endothelial cells apoptosis through upregulating Bcl-2 gene expression and inhibiting caspase-3 activation.

Construction of hepatocyte growth factor gene recombinant adenovirus vector and its expression in rat bone marrow mesenchymal stem cells

Objective：To construct the adenoviral expression vector system containing human hepatocyte growth factor （hHGF） cDNA, and to further study the transduction efficiency and the expression of HGF in mesenchymal stem cells （MSCs）. Methods：The HGF cDNA was amplificated from the expression plasmid pCMV-HGF, and was subcloned into the adenovirus shuttle plasmid pDC316-IRESEGFP vector containing a green fluorescence protein （GFP） reporter gene. Virus Ad-HGF was produced by homologous recombination in HEK293 package cells. Bone marrow derived MSCs were harvested and cultured, and then were transduced with Ad-HGF. The efficiency of Ad-HGF transduction was assessed by FACS analysis using GFP gene expression. And HGF/MSCs were generated. The HGF concentrations in supernatants of HGF/MSCs were determined by ELISA using anti-human HGF monoclonal antibody. Results： The recombinant, named pDC316-HGF-IRES-eGFP, was digested with restriction enzyme, and the DNA sequencing of HGF was identical to the report in Genebank and did not reveal any mutation. GFP expression could be observed on the second day after packing of the linearized pAd-HGF in HEK293 cells and 7.15 × 10^10pfu/ml titer of Ad-HGF was obtained. Forty-eight hours after transduction, 96.89% of HGF/MSCs were GFP positive. Peak concentration levels of hHGF（103ng/mL） in the cultured supernatants were detected on day 2 post-transduction, and the adenovirus-mediated expression of HGF by MSCs was maintained for at least 2 weeks in vivo. Conclusion：Our data demonstrated that the adenovirus expression＇vector system pDC316-HGF-IRES-EGFP has been constructed successfully, and their effective expressions also have been obtained in MSCs. This will provide material basis for the next study on liver regeneration after small-for-size liver transplantation.

Effects of hypoxia-inducible factor-1α silencing on the proliferation of CBRH-7919 hepatoma cells

AIM:To study the effects of hypoxia-inducible factor1α(HIF-1α) silencing on the proliferation of hypoxic CBRH-7919 rat hepatoma cells.METHODS:The CBRH-7919 rat hepatoma cell line was used in this study and the hypoxic model was constructed using CoCl2.The HIF-1α-specific RNAi sequences were designed according to the gene coding sequence of rat HIF-1α obtained from GeneBank.The secondary structure of the HIF-1α gene sequence was analyzed using RNA draw software.The small interfering RNA(siRNA) transfection mixture was produced by mixing the siRNA and Lipofectamine2000TM,and transfected into the hypoxic hepatoma cells.Real time reverse transcription-polymerase chain reaction(RTPCR) and Western blotting assay were used to detect the expression levels of mRNA and protein.HIF-1α and vascular endothelial growth factor(VEGF) mRNA was determined using real time RT-PCR;the protein expression levels of AKT,p-AKT,p21 and cyclinD1 were determined using Western blotting.The proliferation of hepatoma cells was observed using the methyl thiazolyl tetrazolium(MTT) assay and the bromodeoxyuridine(BrdU) incorporation cell proliferation assay.RESULTS:Under induced hypoxia,the viability of the hepatoma cells reached a minimum at 800 μmol/L CoCl2;the viability of the cells was relatively high at CoCl2 concentrations between 100 μmol/L and 200 μmol/L.Under hypoxia,the mRNA and protein expression levels of HIF-1α and VEGF were significantly higher than that of hepatoma cells that were cultured in normaxia.HIF-1α-specific RNAi sequences were successfully transfected into hepatoma cells.The transfection of specific siRNAs significantly inhibited the mRNA and protein expression levels of HIF-1α and VEGF,along with the protein expression levels of p-AKT and cyclinD1;the protein expression of p21 was significantly increased,and there was no significant difference in the expression of AKT.The MTT assay showed that the amount of hepatoma cells in S phase in the siRNA transfection group was obviously smaller than that in the control group;in the siRNA transfection group,the amount of hepatoma cells in G1 phase was more than that in the control group.The BrdU incorporation assay showed that the number of BrdU positive hepatoma cells in the siRNA transfection group was less than that in the control group.The data of the MTT assay and BrdU incorporation assay suggested that HIF-1α silencing using siRNAs significantly inhibited the proliferation of hepatoma cells.CONCLUSION:Hypoxia increases the expression of HIF-1α,and HIF-1α silencing significantly inhibits the proliferation of hypoxic CBRH-7919 rat hepatoma cells.

Effects of basic fibroblast growth factor on angiogenin expression and cell proliferation in H7402 human hepatoma cells

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Basic fibroblast growth factor (bFGF), which is highly expressed in developing tissues and malignant cells, regulates cell growth, differentiation, and migration. Its expression is essential for the progression and metastasis of HCC. This study aims to investigate the effects of bFGF on the expression of angiogenin, another growth factor, which plays an important role in tumor angiogenesis, and on cell proliferation in H7402 human hepatoma cells. The bFGF sense cDNA or antisense cDNA was stably transfected into H7402 cells. Genomic DNA PCR analysis demonstrated that human bFGF sense cDNA or antisense cDNA was inserted into the genome. Furthermore, the expression of bFGF and angiogenin was examined by RT-PCR and Western blot assays. MTT and colony formation assays were employed to determine cell proliferation. Stable bFGF over-expressing and under-expressing transfectants were successfully established. Expression of angiogenin was decreased in the over-expressing bFGF cells (sense transfectants) and was increased in the under-expressing bFGF cells (antisense transfectants). Cell proliferation increased in the bFGF sense transfectants and decreased in the bFGF antisense transfectants. These results demonstrated that the endogenous bFGF may not only negatively regulate the angiogenin expression but also contribute to the overall cell proliferation in H7402 human hepatoma cells. This study may be helpful in finding a potential therapeutic approach to HCC.

Effects of hepatocyte growth factor-mediated activation of Dll4-Notch-Hey2 signaling pathway

Background Hepatocyte growth factor （HGF） treats ischemic disease by promoting arteriogenesis, however, its mechanism of action is not known. The notch signaling pathway plays an important role in neovascularization. The relationship between the proliferation and migration ability of artery endothelial cells and the Dll4-Notch-Hey2 signaling pathway in the process of arteriogenesis was investigated as a mechanism of action of HGE Methods Based on the prophase study cells and supernatant were harvested at the indicated time after human femoral artery endothelial cells （HFAECs） were infected with adenovirus-HGF （Ad-HGF） at 200 pfu/cell. Cells were analyzed for HGF expression and Notch1, DII4 and Hey2 expression by ELISA and reverse transcription-PCR （RT-PCR）. The changes in the proliferation and migration ability of HFAECs were observed by M-I-I- and Transwell migration experiments Ad-GFP-infected HFAECs were used as control. Results Compared with the control group the Ad-HGF group＇s HGF expression was not increased with time, and the induction by HGF of Notch1, DII4 and Hey2 gene transcription was not enhanced with an increase of HGF. The proliferation ability of Ad-HGF-transduced HFAECs was enhanced and their migration ability was also enhanced in the presence of HGF. Conclusions Through activating the DII4-Notch-Hey2 signaling pathway, HGF indirectly promotes the proliferation and migration ability of cells, so that offspring artery branches are formed.

Hepatogenic differentiation of mesenchymal stem cells induced by insulin like growth factor-Ⅰ

AIM:To improve hepatic differentiation of human mesenchymal stem cell(MSC)using insulin growth factor 1(IGF-Ⅰ),which has important role in liver development,hepatocyte differentiation and function.METHODS:Bone marrow of healthy donors was aspirated from the iliac crest.The adherent cells expanded rapidly and were maintained with periodic passages until a relatively homogeneous population was established.The identification of these cells was carried out by immunophenotype analysis and differentiation potential into osteocytes and adipocytes.To effectively induce hepatic differentiation,we designed a protocol based on a combination of IGF-Ⅰ and liver specificfactors(hepatocyte growth factor,oncostatin M and dexamethasone).Morphological features,hepatic functions and cytological staining were assessed to evaluate transdifferentiation of human marrow-derived MSCs.RESULTS:Flow cytometric analysis and the differentiation potential into osteoblasts and adipocytes showed that more than 90% of human MSCs which were isolated and expanded were positive by specif ic markers and functional tests.Morphological assessment and evaluation of glycogen storage,albumin and α-feto protein expression,as well as albumin and urea secretion revealed a statistically signif icant difference between the experimental groups and control.CONCLUSION:In vitro differentiated MSCs using IGF-Ⅰwere able to display advanced liver metabolic functions,supporting the possibility of developing them as potential alternatives to primary hepatocytes.

The involvement of p38 MAPK in transforming growth factor β1-induced apoptosis in murine hepatocytes

We reported in this manuscript that TGF-beta1 induces apoptosis in AML12 murine hepatocytes, which is associated with the activation of p38 MAPK signaling pathway. SB202190, a specific inhibitor of p38 MAPK, strongly inhibited the TGF-beta1-induced apoptosis and PAI-1 promoter activity. Treatment of cells with TGF-beta1 activates p38. Furthermore, over-expression of dominant negative mutant p38 also reduced the TGF-beta1-induced apoptosis. The data indicate that the activation of p38 is involved in TGF-beta1-mediated gene expression and apoptosis.

Effect of Calmodulin and Voltage-dependent Ca^(2+) Channel on the Proliferation of Heptoma Cells Induced by Epidermal Growth Factor

The effect of thyrosine kinase, calmodulin and voltage-dependent Ca 2+ channel on the proliferation of hepatoma cells induced by EGF was studied. Hepatoma cell line SMMC7721 was cultured in RPMI1640 serum-free medium. DNA synthesis rate of hepatoma cells was measured by 3H-TdR incorporation. 10 -9 mol/L EGF could significantly stimulate the proliferation of hepatoma cells (P<0.05), and this effect might be significantly inhibited by tyrosine kinase inhibitor (P<0.001). Calmodulin inhibitor W-7 had no effect on the basic phase of cultured hepatoma cells (P> 0.05), but it had very significantly inhibitory effect on the proliferation of hepatoma cells induced by EGF (P<0.001). Voltage-dependent Ca 2+ channel inhibitor Varapamil had no inhibition on the proliferation of hepatoma cells induced by EGF (P>0.05). It had no effect on the basic phase of cultured hepatoma cells (P>0.05). It is suggested that tyrosine kinase and Ca 2+-calmodulin-dependent pathway may play a critical role on the proliferation of heptoma cells induced by EGF, and voltage-dependent Ca 2+ channel is independent of the effect of EGF.

Changes in growth factor and cytokine expression in biliary obstructed rat liver and their relationship with delayed liver regeneration after partial hepatectomy

AIM： To study the effects of obstructive jaundice on liver regeneration after partial hepatectomy. METHODS： Hepatocyte growth factor （HGF）, its receptor, c-Met, vascular endothelial growth factor （VEGF） and transforming growth factor-β1 （TGF-β1） mRNA expression in both liver tissue and isolated liver cells were investigated after biliary obstruction （BO） by quantitative reverse-transcription polymerase chain reaction （RT-PCR） using a LightCycler. Immunohistochemical staining for desmin and e-smooth muscle actin （α-SNA） was also studied. Regenerating liver weight and proliferating cell nuclear antigen （PCNA） labeling index, and growth factor expression were then evaluated after 70% hepatectomy with concomitant internal bUiary drainage in BO rats or sham-operated rats. RESULTS： Hepatic TGF-β1 mRNA levels increased significantly 14 days after BO, and further increased with duration of cholestasis. Meanwhile, HGF and VEGF tended to increase, but was not significant. In cell isolates, TGF-β1 mRNA was found mainly in the hepatic stellate cell （HSC） fraction. Immunohistochemical studies revealed an increased number of HSCs （desmin-positive cells） and activated HSCs （α-SMA-positive cells） in portal areas after BO. In a hepatectomy model, liver regeneration was delayed in BO rats, as compared to sham-operated rats. TGF-β1 mRNA was significantly up-regulated up to 48 h after hepatectomy, and the earlier HGF mRNA peak was lost in BO rats. CONCLUSION： BO induces HSCs proliferation and activation, leading to up-regulation of TGF-β1 mRNA and suppression of HGF mRNA in livers. These altered expression patterns may be strongly involved in delayed liver regeneration after hepatectomy with obstructive jaundice.

Effect of IL-10 on the expression of HSC growth factors in hepatic fibrosis rat

AIM： To study the effect of IL-10 on the expression of growth factors - transforming growth factor-β1 （TGF-β1）, epidermal growth factor （EGF）, hepatocyte growth factor （HGF）and platelet-derived growth factor （PDGF） of hepatic stellate cells （HSCs） of hepatic fibrosis rat and the anti-fibrogenic role of exogenous IL-10. METHODS： Hepatic fibrosis was induced by CCI4 administration intra-peritoneally. Sixty clean male Sprague-Dawley （SD） rats were randomly divided into three groups： normal control group （GN, 8 rats）, hepatic fibrosis model group （GC, 28 rats） and IL-10 treated group （GI, 24 rats）. At the beginning of the 7^th and 11^th wk, rats in each group were routinely perfused with pronase E and type IV collagenase through a portal vein catheter and the suspension obtained from the liver was spun by centrifugation with 11% Nycodenz density gradient to isolate HSCs. Histological examination was used to determine the degree of hepatic fibrosis. RT-PCR was employed to analyze mRNA expression from freshly isolated cells. Immunocytochemistry was performed to detect protein expression in primary cultured HSCs. RESULTS： Rat hepatic fibrosis was developed with the increase of injection frequency of CCl4, and HSCs were successfully isolated. At the 7^th and 11^th wk, TGF-β1, EGF, and HGF mRNA in GC increased obviously compared with GN （P = 0.001/0.042, 0.001/0.001, 0.001/0.001） and GI （P= 0.001/0.007, 0.002/0.001, 0.001/0.001）. For TGF-β1, no difference was observed between GI and GN. For EGF, mRNA level in GI increased compared with GN during the 7^th wk （P= 0.005） and 11^th wk （P= 0.049）. For HGF, mRNA level in GI decreased compared with GN at the 7^th wk （P = 0.001） and 11^th wk （P= 0.021）. Between these two time points, TGF-β1 expression at the 7^th wk was higher than that of the 11^th wk （P = 0.049）, but for EGF, the former was lower than the latter （P = 0.022）. As for PDGF mRNA, there was no significant difference between thesegroups, but difference seemed to exist in protein levels. Results by immunocytochemistry of TGF-β1 and EGF were paralleled with the above findings. CONCLUSION： The expression of TGF-β1, EGF and HGF increased in HSC of hepatic fibrosis rat and decreased after treatment with IL-10. IL-10 plays an anti-fibrogenic role by suppressing growth factors expression.

Growth factor-and cytokine-driven pathways governing liver stemness and differentiation

Liver is unique in its capacity to regenerate in response to injury or tissue loss. Hepatocytes and other liver cells are able to proliferate and repopulate the liver. However, when this response is impaired, the contribution of hepatic progenitors becomes very relevant. Here, we present an update of recent studies on growth factors and cytokine-driven intracellular pathways that govern liver stem/pro-genitor cell expansion and differentiation, and the rel-evance of these signals in liver development, regeneration and carcinogenesis. Tyrosine kinase receptor signaling, in particular, c-Met, epidermal growth factor receptors or fibroblast growth factor receptors, contribute to prolifera-tion, survival and differentiation of liver stem/progenitor cells. Different evidence suggests a dual role for the trans-forming growth factor (TGF)-β signaling pathway in liver stemness and differentiation. On the one hand, TGF-βmediates progression of differentiation from a progenitor stage, but on the other hand, it contributes to the expan-sion of liver stem cells. Hedgehog family ligands are nec-essary to promote hepatoblast proliferation but need to be shut off to permit subsequent hepatoblast differentiation. In the same line, the Wnt family and β-catenin/T-cell fac-tor pathway is clearly involved in the maintenance of liver stemness phenotype, and its repression is necessary for liver differentiation during development. Collectively, data indicate that liver stem/progenitor cells follow their own rules and regulations. The same signals that are essential for their activation, expansion and differentiation are good candidates to contribute, under adequate conditions, to the paradigm of transformation from a pro-regenerative to a pro-tumorigenic role. From a clinical perspective, this is a fundamental issue for liver stem/progenitor cell-based therapies.

Connective tissue growth factor is overexpressed in human hepatocellular carcinoma and promotes cell invasion and growth

AIM:To determine the expression characteristics of connective tissue growth factor(CTGF/CCN2) in human hepatocellular carcinoma(HCC) in histology and to elucidate the roles of CCN2 on hepatoma cell cycle progression and metastasis in vitro.METHODS:Liver samples from 36 patients(who underwent hepatic resection for the first HCC between 2006 and 2011) and 6 normal individuals were examined for transforming growth factor β1(TGF-β1) or CCN2 mRNA by in situ hybridization.Computer image analysis was performed to measure integrated optimal density of CCN2 mRNA-positive cells in carcinoma foci and the surrounding stroma.Fibroblast-specific protein-1(FSP-1) and E-cadherin were examined to evaluate the process of epithelial to mesenchymal transition,α-smooth muscle actin and FSP-1 were detected to identify hepatic stellate cells,and CD34 was measured to evaluate the extent of vascularization in liver tissues by immunohistochemical staining.CCN2 was assessed for its stimulation of HepG2 cell migration and invasion using commercial kits while flow cytometry was used to determine CCN2 effects on HepG2 cell-cycle.RESULTS:In situ hybridization analysis showed that TGF-β1 mRNA was mainly detected in connective tissues and vasculature around carcinoma foci.In comparison to normal controls,CCN2 mRNA was enhanced 1.9-fold in carcinoma foci(12.36 ± 6.08 vs 6.42 ± 2.35) or 9.4-fold in the surrounding stroma(60.27 ± 28.71 vs 6.42 ± 2.35),with concomitant expression of CCN2 and TGF-β1 mRNA in those areas.Epithelial-mesenchymal transition phenotype related with CCN2 was detected in 12/36(33.3%) of HCC liver samples at the edges between carcinoma foci and vasculature.Incubation of HepG2 cells with CCN2(100 ng/mL) resulted in more of the cells transitioning into S phase(23.85 ± 2.35 vs 10.94 ± 0.23),and induced a significant migratory(4.0-fold) and invasive(5.7-fold) effect.TGF-β1-induced cell invasion was abrogated by a neutralizing CCN2 antibody showing that CCN2 is a downstream mediator of TGF-β1-induced hepatoma cell invasion.CONCLUSION:These data support a role for CCN2 in the growth and metastasis of HCC and highlight CCN2 as a potential novel therapeutic target.

Expression of vascular endothelial growth fac-tor gene in primary cultured rat hepatocytes

BACKGROUND: It is the key point for vascular endothelialgrowth factor (VEGF121) gene related therapy as to how totransfect and express the gene safely, effectively and repeat-edly. This study was designed to investigate the VEGF121transfection and expression in primary cultured rat hepato-cyte.METHODS: After construction of vector internal ribosomeentry site-enhanced yellow fluorescent protein (pIRES-EY-FP)/VEGF121, the transfection and expression of the exoge-nous VEGF121 gene in primary cultured rat hepatocyteswere observed through RT-PCR, Western blot and fluores-cent microscopy.RESULTS: pIRES-EYFP/VEGF121 plasmid was construct-ed and transfected successfully into primary cultured rathepatocytes, the transfection and expression of gene in pri-mary cultured rat hepatocytes were examined by RT-PCRand Western blot, and yellow-green fluorescence was ob-served through a fluorescent microscope.CONCLUSION: The successful transfection and expressionof plasmid pIRES-EYFP/VEGF121 in primary cultured rathepatocytes provides a foundation for hepatocyte transplan-tation and gene therapy after modification of hepatocytesby the gene.

Effects of transferred NK4 gene on proliferation, migration, invasion and apoptosis of human prostate cancer DU145 cells

We investigated the ability of NK4, an antagonist of human hepatocyte growth factor （HGF）, to inhibit the influence of HGF on proliferation, migration, invasion and apoptosis of human prostate cancer cells. Expression vector pBudCE4.1-EGFP-NK4 containing NK4 cDNA was used to transfect human prostate cancer DU145 cells, and the effects of the autocrine NK4 on tumor cell proliferation, migration, invasion and apoptosis were assessed in vitro. in vivo, we subcutaneously implanted DU145 cells, mock-transfected clone （DU145/empty vector） cells and NK4- transfected clone （DU145/NK4） cells into nude mice, and then evaluated tumor growth, cell proliferation and cell apoptosis in vivo. We found that DU145/NK4 cells expressed NK4 protein. In the in vitro study, autocrine NK4 at- tenuated the HGF-induced tumor cell proliferation, migration and invasion, and stimulated apoptosis. Furthermore, autocrine NK4 effectively inhibited the HGF-induced phosphorylation of c-Met, extracellular signal-regulated kinase-1 （ERK1）. and protein kinase B 1/2 （Aktl/2）. Histological examination revealed that autocrine NK4 inhibited prolifera- tion and accelerated apoptosis of prostate cancer cells. These results show that genetic modification of DU145 cells with NK4 cDNA yields a significant effect on their proliferation, migration, invasion and apoptosis. Molecular targeting of HGF/c-Met by NK4 could be applied as a novel therapeutic approach to prostate cancer.

c-Fos overexpression increases the proliferation of human hepatocytes by stabilizing nuclear Cyclin D1

AIM： To investigate the effect of stable c-Fos over- expression on immortalized human hepatocyte （IHH） proliferation. METHODS： IHHs stably transfected with c-Fos （IHH- Fos） or an empty vector （IHH-C） were grown in me- dium supplemented with 1% serum or stimulated with 10% serum. Cell proliferation was assessed by cell counts, 3H-thymidine uptake and flow cytometry analyses. The levels of cell cycle regulatory proteins （Cyclin DI, E, A） cyclin dependent kinases （cdk） cdk2, cdk4, cdk6, and their inhibitors p15, p16, p21, p27, total and phosphorylated GSK-3β and epidermal growth factor receptor （EGF-R） were assayed by Western blotting. Analysis of O/c/in D1 mRNA levels was performed by reverse transcription-polymerase chain reaction and real-time polymerase chain reaction （PCR） analysis. Stability of Cyclin DI was studied by cycloheximide blockade experiments. RESULTS： Stable c-Fos overexpression increased cell proliferation under low serum conditions and resulted in a two-fold increase in [3H]-thymidine incorpora- tion following serum addition. Cell cycle analysis by flow cytometry showed that c-Fos accelerated the cell cycle kinetics. Following serum stimulation, Cyclin D1 was more abundantly expressed in c-Fos overexpress- ing cells. Cyclin D1 accumulation did not result from increased transcriptional activation, but from nuclear stabilization. Overexpression of c-Fos correlated with higher nuclear levels of inactive phosphorylated GSK- 3β, a kinase involved in Cyclin D1 degradation and higher levels of EGF-R mRNA, and EGF-R protein com- pared to IHH-C both in serum starved, and in serum stimulated cells. Abrogation of EGF-R signalling in IHH- Fos by treatment with AG1478, a specific EGF-R tyro- sine kinase inhibitor, prevented the phosphorylation of GSK-3β induced by serum stimulation and decreased Cyclin D1 stability in the nucleus. CONCLUSION： Our results clearly indicate a positive role for c-Fos in cell cycle regulation in hepatocytes. Importantly, we delineate a new mechanism by which c-Fos could contribute to hepatocarcinogenesis through stabilization of Cyclin D1 within the nucleus, evoking a new feature to c-Fos implication in hepatocellular carcinoma.

IGFBPrP1 induces liver fibrosis by inducing hepatic stellate cell activation and hepatocyte apoptosis via Smad2/3 signaling

AIM: To investigate the role and mechanism of insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) in the development of liver fibrosis.