Artificial neural network-based one-equation model for simulation of laminar-turbulent transitional flow

A mapping function between the Reynolds-averaged Navier-Stokes mean flow variables and transition intermittency factor is constructed by fully connected artificial neural network(ANN),which replaces the governing equation of the intermittency factor in transition-predictive Spalart-Allmaras(SA)-γmodel.By taking SA-γmodel as the benchmark,the present ANN model is trained at two airfoils with various angles of attack,Mach numbers and Reynolds numbers,and tested with unseen airfoils in different flow states.The a posteriori tests manifest that the mean pressure coefficient,skin friction coefficient,size of laminar separation bubble,mean streamwise velocity,Reynolds shear stress and lift/drag/moment coefficient from the present two-way coupling ANN model almost coincide with those from the benchmark SA-γmodel.Furthermore,the ANN model proves to exhibit a higher calculation efficiency and better convergence quality than traditional SA-γmodel.

Epithelial-mesenchymal transition- activating transcription factors- multifunctional regulators in cancer

The process of epithelial to mesenchymal transition(EMT), first noted during embryogenesis, has also been reported in tumor formation and leads to the development of metastatic growth. It is a naturally occurring process that drives the transformation of adhesive,non-mobile epithelial like cells into mobile cells with a mesenchymal phenotype that have ability to migrate to distant anatomical sites. Activating complex network of embryonic signaling pathways, including Wnt, Notch,hedgehog and transforming growth factor-β pathways,lead to the upregulation of EMT activating transcription factors, crucial for normal tissue development and maintenance. However, deregulation of tightly regulated pathways affecting the process of EMT has been recently investigated in various human cancers. Given the critical role of EMT in metastatic tumor formation,better understanding of the mechanistic regulation provides new opportunities for the development of potential therapeutic targets of clinical importance.

Epithelial-mesenchymal transition transcription factors and mi RNAs: “Plastic surgeons” of breast cancer

Growing evidence suggests that breast cancer cell plasticity arises due to a partial reactivation of epithelialmesenchymal transition(EMT) programs in order to give cells pluripotency, leading to a stemness-like phenotype. A complete EMT would be a dead end program that would render cells unable to fully metastasize to distant organs. Evoking the EMT-mesenchymal-toepithelial transition(MET) cascade promotes successful colonization of distal target tissues. It is unlikely that direct reprogramming or trans-differentiation without passing through a pluripotent stage would be thepreferred mechanism during tumor progression. This review focuses on key EMT transcriptional regulators, EMT-transcription factors involved in EMT(TFs) and the mi RNA pathway, which are deregulated in breast cancer, and discusses their implications in cancer cell plasticity. Cross-regulation between EMT-TFs and mi RNAs, where mi RNAs act as co-repressors or co-activators, appears to be a pivotal mechanism for breast cancer cells to acquire a stem cell-like state, which is implicated both in breast metastases and tumor recurrence. As a master regulator of mi RNA biogenesis, the ribonuclease type Ⅲ endonuclease Dicer plays a central role in EMTTFs/mi RNAs regulating networks. All these EMT-MET key regulators represent valuable new prognostic and predictive markers for breast cancer as well as promising new targets for drug-resistant breast cancers.

Effects of epidermal growth factor on transforming growth factor-beta1-induced epithelial-mesenchymal transition and potential mechanism in human corneal epithelial cells

AIM: To evaluate the effects of epidermal growth factor(EGF) on transforming growth factor-beta1(TGF-β1)-induced epithelial-mesenchymal transition(EMT) in human corneal epithelial cells(HCECs). METHODS: HCECs were cultured and treated with TGF-β1 for establishing the model of EMT in vitro. Biological effect of EGF on TGF-β1-induced EMT was evaluated. Proteins and m RNAs expression changes of E-cadherin, N-cadherin and Fibronectin(EMT-relative markers) after TGF-β1 or TGF-β1 combined EGF treatment were detected by Western blot and RT-PCR, respectively. Viability and migration of HCECs were measured by CCK-8, transwell cell migration assay and cell scratch wound healing assay. Activation of Smad2, ERK, p38, JNK and Akt signaling pathways were evaluated by Western blot. Inhibitors of relevant signaling pathways were added to the HCECs to explore the key signal mechanism.RESULTS: With treatment of TGF-β1 only, three EMTrelative proteins and m RNA expression showed that EMT up-regulated in a concentration-dependent and time-dependent manner, with significantly decreasing cell viability(TGF-β1≥5 ng/m L, P<0.05) and increasing cell migration(TGF-β1≥5 ng/m L, P<0.01). The phosphorylation of Smad2 and p38 was a key process of TGF-β1-induced EMT. Meanwhile, EMT-relative proteins and m RNA expression showed that EGF inhibited TGF-β1-indued EMT, with significantly increasing cell viability(EGF≥10 ng/m L, P<0.01). It was noteworthy that EGF significantly enhanced cell migration although EMT was inhibited(EGF≥10 ng/m L, P<0.01), and the blockage of p38(by SB202190, a p38 inhibitor) was a potential mechanism of this phenomenon. CONCLUSION: EGF inhibits TGF-β1-induced EMT via suppressive p38, and promotes cells proliferation and migration in a non-EMT process by inhibiting p38 pathway.

The Effect of Lanthanide and Transition Metal Ions on the Fluorescence Spectra for the Anticoagulation Factor of Snake Venom

The effect of lanthanide and transition metal ions on the fluorescence spectra of the anticoagulation factor(ACF)of snake venom has been studied.It is postulated that the quenching of tryptophan residue fluorescence by lanthanide and transition metal ions is caused by the metal ion-induced conformation change of ACF.

Expression of transcription factors Slug in the lens epithelial cells undergoing epithelial-mesenchymal transition induced by connective tissue growth factor

AIMTo investigate the expression of transcription factors Slug in human lens epithelial cells (HLECs) undergoing epithelial-mesenchymal transition (EMT) induced by connective tissue growth factor (CTGF).METHODSHLECs were treated with CTGF of different concentrations (20, 50 and 100 ng/mL) or without CTGF (control) for 24h. The morphological changes of HLECs were analysed by microscopy. The expression and cellular localization of Slug was evaluated by immumo-fluorescence. Expressions of Slug, E-cadherin and alpha smooth muscle actin (&#x003b1;-SMA) were further determined by Western blot analysis.RESULTSHLECs showed spidle fibrolasts-like characteristics and loosely connected each other after CTGF treatment. The immuno-fluorescence staining indicated that Slug was localized in the nuclei and its expression was induced by CTGF. The relative expressions of Slug protein were 1.64&#x000b1;0.11, 1.96 &#x000b1;0.03, 3.12 &#x000b1;0.10, and 4.08&#x000b1;0.14, respectively, in response to control group and treatment with CTGF of 20, 50 and 100 ng/mL (F=443.86, P&#x0003c;0.01). The increased Slug protein levels were correlated well with up-expression of &#x003b1;-SMA (0.78&#x000b1;0.05, 0.85&#x000b1;0.06, 2.17&#x000b1;0.15, 2.86&#x000b1;0.10; F=449.85, P&#x0003c;0.01) and down-expression of E-cadherin (2.50&#x000b1;0.11, 1.79&#x000b1;0.26, 1.05&#x000b1;0.14, 0.63&#x000b1;0.08; F=101.55, P&#x0003c;0.01).CONCLUSIONTranscription factor Slug may be involved in EMT of HLECs induced by CTGF in vitro.

Role of reactive oxygen species in epithelial-mesenchymal transition and apoptosis of human lens epithelial cells

AIM:To investigate the role of reactive oxygen species(ROS)in epithelial–mesenchymal transition(EMT)and apoptosis of human lens epithelial cells(HLECs).METHODS:Flow cytometry was used to assess ROS production after transforming growth factorβ2(TGF-β2)induction.Apoptosis of HLECs after H_(2)O_(2) and TGF-β2 interference with or without ROS scavenger N-acetylcysteine(NAC)were assessed by flow cytometry.The corresponding protein expression levels of the EMT markerα-smooth muscle actin(α-SMA),the extracellular matrix(ECM),marker fibronectin(Fn),and apoptosis-associated proteins were detected by using Western blotting in the presence of an ROS scavenger(NAC).Wound-healing and Transwell assays were used to assess the migration capability of HLECs.RESULTS:TGF-β2 stimulates ROS production within 8h in HLECs.Additionally,TGF-β2 induced HLECs cell apoptosis,EMT/ECM synthesis protein markers expression,and pro-apoptotic proteins production;nonetheless,NAC treatment prevented these responses.Similarly,TGF-β2 promoted HLECs cell migration,whereas NAC inhibited cell migration.We further determined that although ROS initiated apoptosis,it only induced the accumulation of the EMT markerα-SMA protein,but not COL-1 or Fn.CONCLUSION:ROS contribute to TGF-β2-induced EMT/ECM synthesis and cell apoptosis of HLECs;however,ROS alone are not sufficient for EMT/ECM synthesis.

Transcriptional Factor Snail Mediates Epithelial-Mesenchymal Transition in Human Bronchial Epithelial Cells Induced by Silica

Epithelial-mesenchymal transition （EMT） plays an important role in fibrotic diseases. We have previously showed that silica induces EMT in human bronchial epithelial cells （BECs）; however, the underlying mechanism of silica-induced EMT is poorly understood. In the present study, we investigated the role of Snail in silica-induced EMT in human BECs in vitro. Human BECs were treated with silica at various concentrations and incubation times. Then MTr assay, western blot, electrophoretic mobility shift assay （EMSA）, and small interfering RNA （siRNA） transfection were performed. We found that silica increased the expression and DNA binding activity of Snail in human BECs. SNAI silica-induced expression siRNA upregulated the siRNA inhibited the of Snail. Moreover, SNAI expression of epithelial marker E-cadherin, but attenuated the expression of mesenchymal marker a-smooth muscle actin and vimentin in silica-stimulated cells. These results suggest that Snail mediates the silica-induced EMT in human BECs.

Mesenchymal-epithelial Transition Factor Regulates Monocyte Function during Mycobacterial Infection via Indoleamine 2,3-dioxygenase

Objective Mycobacterium tuberculosis(Mtb),the causative agent of tuberculosis(TB),causes an estimated 1.6 million human deaths annually,but the pathogenesis of TB remains unclear.Immunity plays a critical role in the onset and outcome of TB.This study aimed to uncover the roles of innate and adaptive immunity in TB.Methods The gene expression profiles generated by RNA sequencing from human peripheral blood mononuclear cells(PBMCs)stimulated with or without Mtb strain H37Rv antigens were analyzed.A total of 973 differentially expressed mRNAs were identified.Results The differentially expressed genes were enriched in innate immunity signaling functions.The mesenchymal-epithelial transition factor(MET)gene was significantly upregulated in CD14^(+)monocytes.A MET inhibitor improved the uptake of the BCG strain by monocytes and macrophages as well as inhibited the expression of indoleamine 2,3-dioxygenase(IDO).The expression of IDO was increased in PBMCs stimulated with Mtb antigens,and the IDO inhibitor promoted the expression of CD40,CD83,and CD86.Conclusion Our results might provide clues regarding the immunomodulatory mechanisms used by Mtb to evade the host defense system.

EDIL3 depletion suppress epithelial-mesenchymal transition of lens epithelial cells via transforming growth factor β pathway

AIM： To study the effect of discoidin I-like domaincontaining protein 3（EDIL3） depletion on the proliferation and epithelial-mesenchymal transition（EMT） in human lens epithelial cells（LECs）. METHODS： RNA interference was used to inhibit the expression of EDIL3 in human LECs in vitro. The morphology of cells was observed using an inverted microscope. Cell proliferation was assessed using Ed U kit. Cell migration was investigated using Transwell chamber and EMT of LECs was assessed using confocal microscope and Western blotting. The transforming growth factor β（TGFβ） pathway was investigated using Western blotting. RESULTS： The data showed that silencing EDIL3 expression changed LECs morphology and suppressed LECs proliferation（P〈0.05） and migration（P〈0.01）. Furthermore, the result of Western blotting showed that EDIL3 depletion reduced the expression of α-smooth muscle actin（α-SMA）（P〈0.001） and vimentin（P〈0.01）, while increased the expression of E-cadherin（P〈0.001）. EDIL3 depletion could suppress the phosphorylation of Smad2（P〈0.01） and Smad3（P〈0.01） and the activation of exracellular signal regulated kinase（ERK）（P〈0.05）. CONCLUSION： The findings indicate that EDIL3 might participate in the proliferation and EMT in LECs via TGFβ pathway and may be a potential therapeutic target for the treatment of posterior capsule opacification.

Integrin-linked kinase overexpression promotes epithelial-mesenchymal transition via nuclear factor-κB signaling in colorectal cancer cells

AIM: To investigate the effect of integrin-linked kinase (ILK) on proliferation, metastasis, and invasion of the colorectal cancer cell line SW480.METHODS: In this study, the colorectal cancer cell line SW480 was stably transfected with ILK plasmids, and small interfering RNA (siRNA) was used to knockdown expression of nuclear factor (NF)-&#x003ba;B/p65. Methylthiazole tetrazolium (MTT) assay was performed to measure proliferation, and the wound healing migration assay and matrigel invasion assay were used to test the metastasis and invasion ability of SW480 cells. To explore the epithelial-mesenchymal transition (EMT) process, embryonic development, and the invasion and metastasis of tumors, the protein level of E-cadherin, vimentin, snail, and slug was detected by western blot. Immunofluorescence was also used to detect E-cadherin expression. Western blot was used to determine the level of phosphorylated-inhibitor of kappa B (I&#x003ba;B)a, inhibitor of gamma B (I&#x003b3;B)a, and nuclear factor kappa B (NF-&#x003ba;B) expressions and to explore the ILK signaling pathway.RESULTS: Western blot results revealed that ILK expression significantly increased when ILK was overexpressed in SW480 cells (P &#x0003c; 0.05). Proliferation, metastasis, and invasion ability were improved in the vector-ILK group compared to the vector group (P &#x0003c; 0.05). Immunofluorescence results revealed that E-cadherin fluorescence intensity decreased after ILK was overexpressed (P &#x0003c; 0.05). Western blot results revealed that the protein expression of E-cadherin was reduced, while vimentin, snail, and slug were upregulated when ILK was overexpressed in SW480 cells (P &#x0003c; 0.05). In order to determine the role of the NF-&#x003ba;B signaling pathway in ILK overexpression promoted EMT occurrence, we overexpressed ILK in SW480 cells and found that levels of NF-&#x003ba;B/p65 and cytoplasmic phosphorylated-I&#x003ba;Ba were increased and that cytoplasmic I&#x0043a;Ba levels were decreased compared to the control group (P &#x0003c; 0.05). Furthermore, NF-&#x003ba;B/p65 knockout revealed that E-cadherin was increased in the overexpressed ILK group.CONCLUSION: ILK overexpression improved the proliferation, metastasis, and invasion ability of SW480 cells, and this effect may be mediated by the NF-&#x003ba;B signaling pathway.

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.

Short-term inbound rail transit passenger flow prediction based on BILSTM model and influence factor analysis

Accurate and real-time passenger flow prediction of rail transit is an important part of intelligent transportation systems(ITS).According to previous studies,it is found that the prediction effect of a single model is not good for datasets with large changes in passenger flow characteristics and the deep learning model with added influencing factors has better prediction accuracy.In order to provide persuasive passenger flow forecast data for ITS,a deep learning model considering the influencing factors is proposed in this paper.In view of the lack of objective analysis on the selection of influencing factors by predecessors,this paper uses analytic hierarchy processes(AHP)and one-way ANOVA analysis to scientifically select the factor of time characteristics,which classifies and gives weight to the hourly passenger flow through Duncan test.Then,combining the time weight,BILSTM based model considering the hourly travel characteristics factors is proposed.The model performance is verified through the inbound passenger flow of Ningbo rail transit.The proposed model is compared with many current mainstream deep learning algorithms,the effectiveness of the BILSTM model considering influencing factors is validated.Through comparison and analysis with various evaluation indicators and other deep learning models,the results show that the R2 score of the BILSTM model considering influencing factors reaches 0.968,and the MAE value of the BILSTM model without adding influencing factors decreases by 45.61%.

Total flavone of Abelmoschus manihot suppresses epithelial-mesenchymal transition via interfering transforming growth factor-β1 signaling in Crohn's disease intestinal fibrosis

AIM To explore the role and mechanism of total flavone of Abelmoschus manihot(TFA) on epithelial-mesenchymal transition(EMT) progress of Crohn's disease(CD) intestinal fibrosis.METHODS First,CCK-8 assay was performed to assess TFA on the viability of intestinal epithelial(IEC-6) cells and select the optimal concentrations of TFA for our further studies.Then cell morphology,wound healing and transwell assays were performed to examine the effect of TFA on morphology,migration and invasion of IEC-6 cells treated with TGF-β1.In addition,immunofluorescence,real-time PCR analysis(q RT-PCR) and western blotting assays were carried out to detect the impact of TFA on EMT progress.Moreover,western blotting assay was performed to evaluate the function of TFA on the Smad and MAPK signaling pathways.Further,the role of co-treatment of TFA and si-Smad or MAPK inhibitors has been examined by q RTPCR,western blotting,morphology,wound healing andtranswell assays.RESULTS In this study,TFA promoted transforming growth factor-β1(TGF-β1)-induced(IEC-6) morphological change,migration and invasion,and increased the expression of epithelial markers and reduced the levels of mesenchymal markers,along with the inactivation of Smad and MAPK signaling pathways.Moreover,we revealed that si-Smad and MAPK inhibitors effectively attenuated TGF-β1-induced EMT in IEC-6 cells.Importantly,co-treatment of TFA and si-Smad or MAPK inhibitors had better inhibitory effects on TGF-β1-induced EMT in IEC-6 cells than either one of them.CONCLUSION These findings could provide new insight into the molecular mechanisms of TFA on TGF-β1-induced EMT in IEC-6 cells and TFA is expected to advance as a new therapy to treat CD intestinal fibrosis.

Empirical Research on the Factors of Chinese City Growth in the Transitional Period

Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land area to the area of the city X1(%), green coverage ratio of the built up area X2(%), the ratio of personnel involved in the secondary industry X3(%), the GDP per capita X4(×104)and other 43 indicators, by relying on the relevant data from China Urban Statistical Yearbook(2008), applying SPSS statistical software and by applying the Factor Analysis and Regression Analysis. The results show that the factors which affect the city growth have four major groups, namely economic and institutional factors, location factors, environmental factors and social cultural services and functions. Among the factors which affect Chinese city growth, the general budgetary expenditures and the general budgetary revenues of local public finance are the most important factors. The general budgetary expenditures of local finance, the general budgetary revenues, the lands of urban construction and other 12 factors obtained by gradually excluding method can be used to present the coefficient of city growth.

The sustainability and transition of economic growth in China:from a perspective of factor structure

After more than 20 years＇ high speed growth, the sustainable growth of Chinese economy faces serious limitation of resources and factors now and in the future. In order to maintain the economic growth. China has to trans-form the way of economic growth, Based on the analysis on the related theories of economic growth and the structural transformation in factors of production, this paper proposes that the transformation of the economic growth way has to impel the optimization and the promotion of the utilization structure of factors of production. Finall.v, based on the analysis of the necessity to change the pattern of economic growth, this paper proposes＇ the strategic measures to promote the continuous economic growth and the transformation of patterns of economic growth.

A New Zero-Voltage Transition Power Factor Corrected Single-Phase Single-Stage AC-to-DC Converter

This paper presents a new ZVT （zero-voltage transition） single-stage ac-to-dc converter using PWM （pulse width modulation） and HF （high frequency） transformer isolation with capacitive output filter. In this converter a front-end power factor corrected boost stage integrates with a cascaded dc-to-dc bridge HF converter. The front-end boost converter operates in discontinuous current mode and ensures natural power factor correction with very simple control. The auxiliary circuit of this topology deals with very small power and is placed out of the main power path. As a result, the auxiliary circuit components have smaller power rating as opposed to main converter components. Also, output rectifier voltage is clamped to output voltage due to capacitive output filter. Identification and analyses of different operating modes of this converter are presented. Based on these analyses design example of a 50 kHz, 48 V, 1 kW ac-to-dc converter is presented. PSPICE simulation results of the designed converter are presented and explained to verify the performance of this converter.

Saponin Ⅰ from Shuitianqi(Rhizoma Schizocapasae Plantagineae) inhibits metastasis by negatively regulating the transforming growth factor-β1/Smad7 network and epithelial-mesenchymal transition in the intrahepatic metastasis Bagg's Albino/c mouse model

OBJECTIVE:To examine the influence of SaponinⅠfrom Shuitianqi(Rhizoma Schizocapasae Plantagineae)(SSPHⅠ)on hepatocellular carcinoma(HCC)metastasis,and to elucidate the underlying mechanism.METHODS:The intrahepatic metastasis Bagg's Albino/c(BALB/c)mouse model was established with human hepatocellular carcinomas(HepG2)cells,then treated with normal saline(once per day),cisplatin(2 mg/kg,once every 2 d),and SSPHⅠ(25,50,and 75 mg/kg,once per day).Then,we assessed alterations in the hepatic pathology and target protein expressions in the intrahepatic metastasis BALB/c mouse model using a series of molecular biology techniques.RESULTS:Based on our analysis,SSPHⅠsignificantly alleviated hepatocyte necrosis and tumor cells infiltration.Moreover,SSPHⅠsuppressed extracellular matrix(ECM)degradation and angiogenesis via a decrease in matrix etalloproteinase-2(MMP-2),MMP-9,CD31,CD34,and vascular endothelial growth factor(VEGF)levels.Furthermore,SSPHⅠrepressed invasion and metastasis by suppressing the transforming growth factor-β1(TGF-β1)/Smad7 axis and epithelial-mesenchymal transition(EMT),as evidenced by the scarce TGF-β1,Ncadherin,and Vimentin expressions,and elevated Smad7 and E-cadherin expressions.CONCLUSION:The SSPHⅠ-mediated negative regulation of the TGF-β1/Smad7 axis and EMT are critical for the inhibition of HCC invasion and metastasis.

Transportation Development Transition in China

Scientific development is an invaluable asset to a country.Policies and development modes should be carried out based on scientific findings not only in industry,but also in transportation infrastructure construction.Building an integrated transportation system,which is in line with the national requirements of China and supports sustainable socio-economic development,is a key strategic issue related to building a moderately prosperous society and achieving realistic goals of a medium-level developed country.Based on a systematic review of the advances in China's transportation infrastructure over the last 60 years,this paper explores the main drivers of transportation development,including national policy,transportation structure,investment efficiency,and technological innovation.Analysis shows that China's comprehensive transportation infrastructure construction since 1949 can be divided into five stages initiated by these drivers,which correspond to four transition modes:policy transition,structural transition,efficiency transition,and technology transition.The transition path of China's transportation development shows that the dominant factors have changed,and the interval for each transition has shortened.With the implementation of the '12th Five-Year Plan',China's transportation infrastructure construction is showing some new characteristics and facing a new development transition.Finally,this paper analyzes the trends in transportation development in China and concludes that technological innovation will be the main driving force to increase the transportation supply and service area in the future.

MTHFR C677T polymorphisms are associated with aberrant methylation of the IGF-2 gene in transitional cell carcinoma of the bladder

The purpose of this study was to determine the relationship between methylation status of the insulin-like growth factor 2 （IGF-2） gene and methylenetetrahydrofolate reductase （MTHFR） C677T gene polymorphisms in bladder transitional cell carcinoma tissues in a Chinese population. The polymorphisms of the folate metabolism enzyme gene MTHFR were studied by restrictive fragment length polymorphism （RFLP）, PCR-based methods of DNA methylation analysis were used to detect the CpG island methylation status of the IGF-2 gene. The association between the methylation status of the IGF-2 gene and clinical characteristics, as well as MTHFR C677T polymorphisms, was analyzed. Aberrant hypomethylation of the IGF-2 gene was found in 68.3% bladder cancer tissues and 12.4% normal bladder tissues, respectively, while hypomethylation was not detected in almost all normal bladder tissues. The hypomethylation rate of the IGF-2 gene in cancer tissues was significantly higher in patients with lymph node metastasis than in those without lymph node metastasis （46.3% vs 17.2%, P = 0.018）. No association was found between aberrant DNA methylation and selected factors including sex, age, tobacco smoking, alcohol consumption and green tea consumption. After adjusting for potential confounding variables the variant allele of MTHFR C677T was found to be associated with hypomethylation of the IGF-2 gene. Compared with wildtype CC, the odds ratio was 4.33 （95% CI=1.06-10.59） for CT and 4,95 （95% CI=1.18-12.74） for TT. MTHFR 677 CC and CT genotypes might be one of the reasons that cause abnormal hypomethylation of the IGF-2 gene, and the aberrant CpG island hypomethylation of the IGF-2 gene may contribute to the genesis and progression of bladder transitional cell carcinoma.