The maintenance of appropriate glycemic control is important for the prevention of diabetic complications in people with type 2 diabetes(T2D). Numerous oral antidiabetic drugs are now clinically available, but in part...The maintenance of appropriate glycemic control is important for the prevention of diabetic complications in people with type 2 diabetes(T2D). Numerous oral antidiabetic drugs are now clinically available, but in particular, the introduction of injection regimens using insulin and/or glucagon-like peptide-1 receptor agonist(GLP-1RA)s represents promising step-up options for oral antidiabetic drug treatment. The recently licensed fixed-ratio combination(FRC) products,which comprise basal insulin and a GLP-1RA, have potent anti-hyperglycemic effects and reduce the undesirable side-effects of each component, such as body weight gain, hypoglycemia, and gastrointestinal symptoms. Two FRCs-insulin degludec/Liraglutide and insulin glargine/Lixisenatide-are now clinically available and, to date, several phase Ⅱ/Ⅲ trials have been conducted in particular groups of subjects with T2D. However, their utility in real-world clinical settings is of interest for most clinicians. Recently reported real-world clinical trials of these two FRCs in various situations have demonstrated their efficacy regarding glycemic control and the quality of life of people with T2D. Their long-term safety and efficacy require confirmation, but a treatment strategy that includes an FRC may be compatible with the concept of “well-balanced” therapy in certain groups of patients with T2D who have inadequate glycemic control.展开更多
Objective To study the effect of β3 adrenergic receptor （β3AR） Trp64Arg and peroxisome proliferator activated receptor gamma 2 （PPAR72） Prol2Ala polymorphisms on insulin resistance. Methods One hundred and eight...Objective To study the effect of β3 adrenergic receptor （β3AR） Trp64Arg and peroxisome proliferator activated receptor gamma 2 （PPAR72） Prol2Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment （HOMA）. PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state （IBS） was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%, and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio （WHR）, blood glucose （GLU）, and insulin （INS）, homeostasis model assessment insulin resistance index （HOMA-IR） of the twin pairs sharing 2 alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA4R had statistic significance. For PPAR3t2 Prol2Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index （BMI）, WHR, percent of body fat （PBF） and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Condusions β3AR Trp64Arg and PPAR）,2 Pro 12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci, and further studies are necessary to confirm this finding.展开更多
The aim of this investigation was to determine whether a PPAR72 Prol2Ala polymorphism was associated with insulin resistance, β-cellfunction and hypertension in Chinese populations. 289 unrelated Chinese subjects fir...The aim of this investigation was to determine whether a PPAR72 Prol2Ala polymorphism was associated with insulin resistance, β-cellfunction and hypertension in Chinese populations. 289 unrelated Chinese subjects first diagnosed Type 2 diabetes （HbAC1〈6.0） were investigated, including 132 hypertensive diabetic （HTD） subjects, 157 normotensive diabetic （NTD） subjects. Blood pressure and anthropometric measurements were collected from all participants, as well as several venous blood samples during oral glucose tolerance test （OGTT）. Biochemical measurements （high-density lipoprotein （HDL） and low-density lipoprotein-cholesterol （LDL）, triglycerides） and PPARγ2 Pro12Ala genotype were also determined. And insulin resistance and β-cells function was assessed by HOMA-IR and HOMA-β respectively. The frequency of subjects bearing the Pro12Ala was lower in the hypertension group （3. 03 %） than in the non-hypertension group （5.7 %） （P〈0.05） after adjusted for age, BMI and gender. Hypertensive diabetic Pro12Ala subjects had lower fasting plasma glucose level （P=0. 0127）, and better glucose tolerance 60 min after oral glucose （P=0. 0361）. Moreover, plasma insulin concentrations at 60 min was lower than those without A variant （P = 0. 0275）, and both hypertensive Ala/Pro in HOMA-β （P ： 0. 0455） and AUC for insulin （P=0. 0473） were higher, and HOMA-IR was lower （P=0. 0375） as compared with hypertensive Pro/Pro subjects. No association was observed between Prol2Ala genotype and BMI, total cholesterol, HDL- cholesterol or triglycerides in either group. Our findings suggested that the Ala 12 allele of the PPARγ2 gene may improve insulin resistance and ameliorate β-cell function reserves in T2DM with hypertension, and protect patients from hypertension in T2DM. As an important thrifty gene, environment factors may exerts an effect of PPARγ2 on glucose homeostasis and insulin resistance.展开更多
Objective： Bererine has been used to treat type 2 diabetes mellitus in Chinese traditional medicine because of its hypoglycemic effect. In this report, we compared the intrinsic tyrosine kinase activities of erythroc...Objective： Bererine has been used to treat type 2 diabetes mellitus in Chinese traditional medicine because of its hypoglycemic effect. In this report, we compared the intrinsic tyrosine kinase activities of erythrocyte insulin receptors from type 2 diabetes mellitus with or without stimulation by berberine in vitro. Methods- Preparations containing insulin receptors were obtained from soluble human erythrocytes, and the insulin receptors were partially purified by affinity chromatography. The tyrosine kinase activity was measured by the exogenous substrate phosphorylation. Results： Both the membrane tyrosine kinase activity and the purified receptor tyrosine kinase activity from diabetics decreased significantly compared with those of normal individuals （reduced by 67.4% and 47.2%, respectively）. After incubation with berbefine, there is a statistical difference in the activity of membrane tyrosine kinase for diabetic patients （ a 150% increase）. Berefine had no effect on the tyrosine kinase activity of purified insulin receptors. Conclusion： We concluded from these results that berbefine was able to improve the insulin sensitivity by increasing the protein tyrosine kinase activity of membrane-bound insulin receptors from type 2 diabetes mellitus.展开更多
AIM: To investigate the effects of blockade of insulin receptor substrate-1(IRS-1) on the bio-function of tube formation of human choroidal endothelial cells(HCECs).METHODS: Quantitative reverse transcriptionpolymeras...AIM: To investigate the effects of blockade of insulin receptor substrate-1(IRS-1) on the bio-function of tube formation of human choroidal endothelial cells(HCECs).METHODS: Quantitative reverse transcriptionpolymerase chain reaction(RT-PCR) and Western blot were performed to determine the expression level of IRS-1 and phospho-IRS-1 in HCECs. Tube formation of HCECs was analyzed using three dimensional in vitro Matrigel assay with or without IRS-1 blockage via IRS-1 inhibitor(GS-101) and vascular endothelial growth factor receptor 2(VEGFR2) inhibitor. In addition, cell counting kit(CCK)-8 and Transwell migration assay were exerted to analyze the effects of blockade of IRS-1 on the bio-function of proliferation and migration of HCECs, respectively. The apoptosis of HCECs was examined using flow cytometry(FCM).RESULTS: RT-PCR and Western blot revealed that IRS-1 phospho-IRS-1 were expressed in HCECs and the expression level was enhanced by stimulation of VEGF-A. The number of tube formation was decreased significantly in GS-101 treated groups compared to phosphate buffered saline(PBS) treated control groups. Furthermore, both cell proliferation and migration of HCECs were decreased in the presence of GS-101. FCM analysis showed that the apoptosis of HCECs was enhanced when the cells were treated with GS-101. Western blot also showed that the expression level of cleaved-caspase 3 in GS-101 treated group was higher than that in control group.CONCLUSION: Blockade of IRS-1 can inhibit tube formation of HCECs through reducing cell proliferation and migration and promoting cell apoptosis.展开更多
BACKGROUND： Human gliomas are more likely to express basic fibroblast growth factor-2 （FGF-2） insulin-like growth factor-1（IGF-1）, and IGF-1 receptor （IGF-1R） than normal brain tissue. These factors activate si...BACKGROUND： Human gliomas are more likely to express basic fibroblast growth factor-2 （FGF-2） insulin-like growth factor-1（IGF-1）, and IGF-1 receptor （IGF-1R） than normal brain tissue. These factors activate signal transduction systems of Ras/MAPK and PI3K/Akl, which promote glioma growth. OBJECTIVE： To utilize RNA interference （RNAi） technique to down-regulate FGF-2, IGF-1, and IGF-1R gene expression, and to investigate the effects of these genes on rat C6 glioma cells, as well as the feasibility of RNAi for treating glioma. DESIGN, TIME AND SETTING： This neurooncological, randomized, controlled, in vivo and in vitro experiment, which used RNAi methodology, was performed at the Laboratory of Molecular Biology, Institute of Biochemistry, Chinese Academy of Sciences between August 2005 and February 2008. MATERIALS： Rat C6 cell lines were purchased from Shanghai Institute of Cellular Biology Affiliated to Chinese Academy of Sciences. Small interfering RNA （siRNA） was synthesized by Shanghai GenePharma. Anti-IGF-1, anti-IGF-1R, anti-FGF-2, anti-mouse and anti-rabbit IgG G1-HRP antibodies were provided by Santa Cruz Biotechnology, USA. Four to six week-old BALB/c nude mice were purchased from the Laboratory Animal Center, Chinese Academy of Sciences. METHODS： C6 glioma cells were transfected with siRNA, which was chemically synthesized in vitro to correspond to endogenous FGF-2, IGF-1, and IGF-1R genes. The inhibition ratio of targeting mRNA expression was detected by semiquantitative RT-PCR, and protein expression was determined by Western blot analysis. C6 glioma cell proliferation was observed using a growth curve C6 glioma cell apoptosis rate and cell cycle were detected by flow cytometry. C6 glioma cell growth regression was observed by transwell migration assay. In addition, nude mouse subcutaneous tumor models were used in this study. For studying the anti-tumor effects of IGF-1 and IGF-1R siRNA, two blank control groups, with six mice each, were set up： A （2.5 μg siRNA was injected one week after C6 cells were inoculated, Le., when tumor volume reached 8 mm × 8 mm） and B （siRNA was injected at the same time with C6 cells were inoculated. To study the effects of FGF-2 siRNA, the groups consisted of a blank control group, negative control group, 2.6 μg siRNA group, 4 μg siRNA group, and 5.3 μg siRNA group, with six mice each. MAIN OUTCOME MEASURES： mRNA and protein inhibition ratio of FGF-2, IGF-1, and IGF-1 R; C6 glioma cell proliferation, apoptosis, and cycle growth arrest; C6 glioma cell growth regression and subcutaneous tumorigenicity rates. RESULTS： All siRNA constructs proved to be effective. After 48 hours, transfection of 200 nmol/L siRNA resulted in a FGF-2 or IGF-1R gene inhibition ratio 〉 80% and an IGF-1 gene inhibition ratio of approximately 70%. Protein expression levels for FGF-2, IGF-1, and IGF-1R decreased in a dose-dependent manner following siRNA transfection, with an inhibition rate 〉 85%, 60%, and 50%, respectively. C6 glioma cell proliferation and apoptosis rates increased in proportion to siRNA. The apoptosis rate of C6 glioma cells induced by FGF-2, IGF-1, and IGF-1R siRNA was 39.96%, 15.07% and 22.47%, respectively （P 〈 0.01）. Transfection of 200 nmol/L IGF or IGF-1R siRNA for 48 hours suppressed C6 glioma cell migration. At 30 days after intratumoral injection of 2.6, 4, and 5.3 tJg FGF-2 siRNA, tumor growth regression rate of FGF-2 siRNA was 56%, 67%, and 86%, respectively. The tumor growth regression rate was 71.88% and 45.71%, respectively, when IGF-1 or IGF-1R siRNA was intratumorally injected 1 week after C6 glioma cell transplantation. When IGF-1 or IGF-1 R siRNA was intratumorally injected during C6 glioma cell transplantation, the tumor growth regression rate was 78.13% and 74.29%, respectively. CONCLUSION： siRNA transfection downregulated gene expression of FGF-2, IGF-1, and IGF-1R In addition, siRNA treatment markedly suppressed glioma cell proliferation, growth, and migration, and concomitantly reduced subcutaneous tumorigenicity.展开更多
Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracell...Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.展开更多
Type 2 diabetes一associated with impaired insulin/insulin-like growth factor-1 (IGF1) signaling (IIS)一is a risk factor for cognitive impairment and dementia including Alzheimer's disease (AD). The insulin recepto...Type 2 diabetes一associated with impaired insulin/insulin-like growth factor-1 (IGF1) signaling (IIS)一is a risk factor for cognitive impairment and dementia including Alzheimer's disease (AD). The insulin receptor substrate (IRS) proteins are major components of IIS, which transmit upstream signals via the insulin receptor and/or IGF1 receptor to multiple intracellular signaling pathways, including AKT/protein kinase B and extracellular-signal-regulated kinase cascades. Of the four IRS proteins in mammals, IRS1 and IRS2 play key roles in regulating growth and survival, metabolism, and aging. Meanwhile, the roles of IRS1 and IRS2 in the central nervous system with respect to cognitive abilities remain to be clarified. In contrast to IRS2 in peripheral tissues, inactivation of neural IRS2 exerts beneficial effects, resulting in the reduction of amyloid p accumulation and premature mortality in AD mouse models. On the other hand, the increased phosphorylation of IRS 1 at several serine sites is observed in the brains from patients with AD and animal models of AD or cognitive impairment induced by type 2 diabetes. However, these serine sites are also activated in a mouse model of type 2 diabetes, in which the diabetes drug metformin improves memory impairment. Because IRS1 and IRS2 signaling pathways are regulated through complex mechanisms including positive and negative feedback loops, whether the elevated phosphorylation of IRS1 at specific serine sites found in AD brains is a primary response to cognitive dysfunction remains unknown. Here, we examine the associations between IRS 1 /1 RS2-mediated signaling in the central nervous system and cognitive decline.展开更多
There are many advantages of combining incretin therapy[glucagon-like peptide-1(GLP-1)receptor agonists and dipeptidyl peptidase-4(DPP-4)inhibitors]with insulin therapy as a glucose-lowering strategy in type2 diabetes...There are many advantages of combining incretin therapy[glucagon-like peptide-1(GLP-1)receptor agonists and dipeptidyl peptidase-4(DPP-4)inhibitors]with insulin therapy as a glucose-lowering strategy in type2 diabetes.One important advantage is the complementary mode of the mechanistic action of incretin and insulin therapy.Another advantage is the reduction in risk of hypoglycemia and weight gain when adding incretin therapy to insulin.Several clinical trials have studied the addition of GLP-1 receptor agonists[exenatide BID(twice daily),lixisenatide,albiglutide]or DPP-4inhibitors(vildagliptin,sitagliptin,saxagliptin,alogliptin,linagliptin)to ongoing insulin therapy or adding insulin to ongoing therapy with a GLP-1 receptor agonist(liraglutide).These studies show improved glycemia in the presence of limited risk for hypoglycemia and weight gain with the combination of incretin therapy with insulin.This article reviews the background and clinical studies on this combination.展开更多
文摘The maintenance of appropriate glycemic control is important for the prevention of diabetic complications in people with type 2 diabetes(T2D). Numerous oral antidiabetic drugs are now clinically available, but in particular, the introduction of injection regimens using insulin and/or glucagon-like peptide-1 receptor agonist(GLP-1RA)s represents promising step-up options for oral antidiabetic drug treatment. The recently licensed fixed-ratio combination(FRC) products,which comprise basal insulin and a GLP-1RA, have potent anti-hyperglycemic effects and reduce the undesirable side-effects of each component, such as body weight gain, hypoglycemia, and gastrointestinal symptoms. Two FRCs-insulin degludec/Liraglutide and insulin glargine/Lixisenatide-are now clinically available and, to date, several phase Ⅱ/Ⅲ trials have been conducted in particular groups of subjects with T2D. However, their utility in real-world clinical settings is of interest for most clinicians. Recently reported real-world clinical trials of these two FRCs in various situations have demonstrated their efficacy regarding glycemic control and the quality of life of people with T2D. Their long-term safety and efficacy require confirmation, but a treatment strategy that includes an FRC may be compatible with the concept of “well-balanced” therapy in certain groups of patients with T2D who have inadequate glycemic control.
基金This study was supported by the National Natural Science Foundation of China (30371223)the Major State Basic Research Development Program of China (2001CB510310).
文摘Objective To study the effect of β3 adrenergic receptor （β3AR） Trp64Arg and peroxisome proliferator activated receptor gamma 2 （PPAR72） Prol2Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment （HOMA）. PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state （IBS） was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%, and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio （WHR）, blood glucose （GLU）, and insulin （INS）, homeostasis model assessment insulin resistance index （HOMA-IR） of the twin pairs sharing 2 alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA4R had statistic significance. For PPAR3t2 Prol2Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index （BMI）, WHR, percent of body fat （PBF） and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Condusions β3AR Trp64Arg and PPAR）,2 Pro 12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci, and further studies are necessary to confirm this finding.
文摘The aim of this investigation was to determine whether a PPAR72 Prol2Ala polymorphism was associated with insulin resistance, β-cellfunction and hypertension in Chinese populations. 289 unrelated Chinese subjects first diagnosed Type 2 diabetes （HbAC1〈6.0） were investigated, including 132 hypertensive diabetic （HTD） subjects, 157 normotensive diabetic （NTD） subjects. Blood pressure and anthropometric measurements were collected from all participants, as well as several venous blood samples during oral glucose tolerance test （OGTT）. Biochemical measurements （high-density lipoprotein （HDL） and low-density lipoprotein-cholesterol （LDL）, triglycerides） and PPARγ2 Pro12Ala genotype were also determined. And insulin resistance and β-cells function was assessed by HOMA-IR and HOMA-β respectively. The frequency of subjects bearing the Pro12Ala was lower in the hypertension group （3. 03 %） than in the non-hypertension group （5.7 %） （P〈0.05） after adjusted for age, BMI and gender. Hypertensive diabetic Pro12Ala subjects had lower fasting plasma glucose level （P=0. 0127）, and better glucose tolerance 60 min after oral glucose （P=0. 0361）. Moreover, plasma insulin concentrations at 60 min was lower than those without A variant （P = 0. 0275）, and both hypertensive Ala/Pro in HOMA-β （P ： 0. 0455） and AUC for insulin （P=0. 0473） were higher, and HOMA-IR was lower （P=0. 0375） as compared with hypertensive Pro/Pro subjects. No association was observed between Prol2Ala genotype and BMI, total cholesterol, HDL- cholesterol or triglycerides in either group. Our findings suggested that the Ala 12 allele of the PPARγ2 gene may improve insulin resistance and ameliorate β-cell function reserves in T2DM with hypertension, and protect patients from hypertension in T2DM. As an important thrifty gene, environment factors may exerts an effect of PPARγ2 on glucose homeostasis and insulin resistance.
文摘Objective： Bererine has been used to treat type 2 diabetes mellitus in Chinese traditional medicine because of its hypoglycemic effect. In this report, we compared the intrinsic tyrosine kinase activities of erythrocyte insulin receptors from type 2 diabetes mellitus with or without stimulation by berberine in vitro. Methods- Preparations containing insulin receptors were obtained from soluble human erythrocytes, and the insulin receptors were partially purified by affinity chromatography. The tyrosine kinase activity was measured by the exogenous substrate phosphorylation. Results： Both the membrane tyrosine kinase activity and the purified receptor tyrosine kinase activity from diabetics decreased significantly compared with those of normal individuals （reduced by 67.4% and 47.2%, respectively）. After incubation with berbefine, there is a statistical difference in the activity of membrane tyrosine kinase for diabetic patients （ a 150% increase）. Berefine had no effect on the tyrosine kinase activity of purified insulin receptors. Conclusion： We concluded from these results that berbefine was able to improve the insulin sensitivity by increasing the protein tyrosine kinase activity of membrane-bound insulin receptors from type 2 diabetes mellitus.
基金Supported by the National Natural Science Foundation in China(No.81671641 No.81970830+6 种基金 No.31600736)Suzhou Municipal Natural Science Foundation(No.SYS201745)Soochow University Doctoral Academic Talents Program(No.5832001313)Jiangsu Provincial Medical Youth Talent(No.QNRC2016718)Jiangsu Provincial Medical Innovation Team(No.CXTDA2017039)Jiangsu Provincial Natural Science Foundation(No.BK20151208)the Soochow Scholar Project of Soochow University(No.R5122001)
文摘AIM: To investigate the effects of blockade of insulin receptor substrate-1(IRS-1) on the bio-function of tube formation of human choroidal endothelial cells(HCECs).METHODS: Quantitative reverse transcriptionpolymerase chain reaction(RT-PCR) and Western blot were performed to determine the expression level of IRS-1 and phospho-IRS-1 in HCECs. Tube formation of HCECs was analyzed using three dimensional in vitro Matrigel assay with or without IRS-1 blockage via IRS-1 inhibitor(GS-101) and vascular endothelial growth factor receptor 2(VEGFR2) inhibitor. In addition, cell counting kit(CCK)-8 and Transwell migration assay were exerted to analyze the effects of blockade of IRS-1 on the bio-function of proliferation and migration of HCECs, respectively. The apoptosis of HCECs was examined using flow cytometry(FCM).RESULTS: RT-PCR and Western blot revealed that IRS-1 phospho-IRS-1 were expressed in HCECs and the expression level was enhanced by stimulation of VEGF-A. The number of tube formation was decreased significantly in GS-101 treated groups compared to phosphate buffered saline(PBS) treated control groups. Furthermore, both cell proliferation and migration of HCECs were decreased in the presence of GS-101. FCM analysis showed that the apoptosis of HCECs was enhanced when the cells were treated with GS-101. Western blot also showed that the expression level of cleaved-caspase 3 in GS-101 treated group was higher than that in control group.CONCLUSION: Blockade of IRS-1 can inhibit tube formation of HCECs through reducing cell proliferation and migration and promoting cell apoptosis.
基金the National Natural Science Foundation of China,No.30371459Science and Technology Development Fund of Shanghai,No.034047
文摘BACKGROUND： Human gliomas are more likely to express basic fibroblast growth factor-2 （FGF-2） insulin-like growth factor-1（IGF-1）, and IGF-1 receptor （IGF-1R） than normal brain tissue. These factors activate signal transduction systems of Ras/MAPK and PI3K/Akl, which promote glioma growth. OBJECTIVE： To utilize RNA interference （RNAi） technique to down-regulate FGF-2, IGF-1, and IGF-1R gene expression, and to investigate the effects of these genes on rat C6 glioma cells, as well as the feasibility of RNAi for treating glioma. DESIGN, TIME AND SETTING： This neurooncological, randomized, controlled, in vivo and in vitro experiment, which used RNAi methodology, was performed at the Laboratory of Molecular Biology, Institute of Biochemistry, Chinese Academy of Sciences between August 2005 and February 2008. MATERIALS： Rat C6 cell lines were purchased from Shanghai Institute of Cellular Biology Affiliated to Chinese Academy of Sciences. Small interfering RNA （siRNA） was synthesized by Shanghai GenePharma. Anti-IGF-1, anti-IGF-1R, anti-FGF-2, anti-mouse and anti-rabbit IgG G1-HRP antibodies were provided by Santa Cruz Biotechnology, USA. Four to six week-old BALB/c nude mice were purchased from the Laboratory Animal Center, Chinese Academy of Sciences. METHODS： C6 glioma cells were transfected with siRNA, which was chemically synthesized in vitro to correspond to endogenous FGF-2, IGF-1, and IGF-1R genes. The inhibition ratio of targeting mRNA expression was detected by semiquantitative RT-PCR, and protein expression was determined by Western blot analysis. C6 glioma cell proliferation was observed using a growth curve C6 glioma cell apoptosis rate and cell cycle were detected by flow cytometry. C6 glioma cell growth regression was observed by transwell migration assay. In addition, nude mouse subcutaneous tumor models were used in this study. For studying the anti-tumor effects of IGF-1 and IGF-1R siRNA, two blank control groups, with six mice each, were set up： A （2.5 μg siRNA was injected one week after C6 cells were inoculated, Le., when tumor volume reached 8 mm × 8 mm） and B （siRNA was injected at the same time with C6 cells were inoculated. To study the effects of FGF-2 siRNA, the groups consisted of a blank control group, negative control group, 2.6 μg siRNA group, 4 μg siRNA group, and 5.3 μg siRNA group, with six mice each. MAIN OUTCOME MEASURES： mRNA and protein inhibition ratio of FGF-2, IGF-1, and IGF-1 R; C6 glioma cell proliferation, apoptosis, and cycle growth arrest; C6 glioma cell growth regression and subcutaneous tumorigenicity rates. RESULTS： All siRNA constructs proved to be effective. After 48 hours, transfection of 200 nmol/L siRNA resulted in a FGF-2 or IGF-1R gene inhibition ratio 〉 80% and an IGF-1 gene inhibition ratio of approximately 70%. Protein expression levels for FGF-2, IGF-1, and IGF-1R decreased in a dose-dependent manner following siRNA transfection, with an inhibition rate 〉 85%, 60%, and 50%, respectively. C6 glioma cell proliferation and apoptosis rates increased in proportion to siRNA. The apoptosis rate of C6 glioma cells induced by FGF-2, IGF-1, and IGF-1R siRNA was 39.96%, 15.07% and 22.47%, respectively （P 〈 0.01）. Transfection of 200 nmol/L IGF or IGF-1R siRNA for 48 hours suppressed C6 glioma cell migration. At 30 days after intratumoral injection of 2.6, 4, and 5.3 tJg FGF-2 siRNA, tumor growth regression rate of FGF-2 siRNA was 56%, 67%, and 86%, respectively. The tumor growth regression rate was 71.88% and 45.71%, respectively, when IGF-1 or IGF-1R siRNA was intratumorally injected 1 week after C6 glioma cell transplantation. When IGF-1 or IGF-1 R siRNA was intratumorally injected during C6 glioma cell transplantation, the tumor growth regression rate was 78.13% and 74.29%, respectively. CONCLUSION： siRNA transfection downregulated gene expression of FGF-2, IGF-1, and IGF-1R In addition, siRNA treatment markedly suppressed glioma cell proliferation, growth, and migration, and concomitantly reduced subcutaneous tumorigenicity.
文摘Free fatty acids are known to play a key role in promoting loss of insulin sensitivity in type 2 diabetes mellitus but the underlying mechanism is still unclear.It has been postulated that an increase in the intracellular concentration of fatty acid metabolites activates a serine kinase cascade,which leads to defects in insu-lin signaling downstream to the insulin receptor.In addition,the complex network of adipokines released from adipose tissue modulates the response of tissues to insulin.Among the many molecules involved in the intracellular processing of the signal provided by insulin,the insulin receptor substrate-2,the protein kinase B and the forkhead transcription factor Foxo 1a are of particular interest,as recent data has provided strong evidence that dysfunction of these proteins results in insulin resistance in vivo.Recently,studies have revealed that phosphoinositidedependent kinase 1-independent phosphorylation of protein kinase Cε causes a reduction in insulin receptor gene expression.Additionally,it has been suggested that mitochondrial dysfunction triggers activation of several serine kinases,and weakens insulin signal transduction.Thus,in this review,the current developments in understanding the pathophysiological processes of insulin resistance in type 2 diabetes have been summarized.In addition,this study provides potential new targets for the treatment and prevention of type 2 diabetes.
基金supported by a MEXTGrant-in-Aid for Scientific Research on Innovative Areas(brain environment)(JP24111536 to AT)+3 种基金JSPS KAKENHI(JP24650201,JP26282026,JP17K19951,JP17H02188 to AT)grants from the Mitsubishi Foundation(to AT)NOVARTIS Foundation Japan for the Promotion of Science(to AT)
文摘Type 2 diabetes一associated with impaired insulin/insulin-like growth factor-1 (IGF1) signaling (IIS)一is a risk factor for cognitive impairment and dementia including Alzheimer's disease (AD). The insulin receptor substrate (IRS) proteins are major components of IIS, which transmit upstream signals via the insulin receptor and/or IGF1 receptor to multiple intracellular signaling pathways, including AKT/protein kinase B and extracellular-signal-regulated kinase cascades. Of the four IRS proteins in mammals, IRS1 and IRS2 play key roles in regulating growth and survival, metabolism, and aging. Meanwhile, the roles of IRS1 and IRS2 in the central nervous system with respect to cognitive abilities remain to be clarified. In contrast to IRS2 in peripheral tissues, inactivation of neural IRS2 exerts beneficial effects, resulting in the reduction of amyloid p accumulation and premature mortality in AD mouse models. On the other hand, the increased phosphorylation of IRS 1 at several serine sites is observed in the brains from patients with AD and animal models of AD or cognitive impairment induced by type 2 diabetes. However, these serine sites are also activated in a mouse model of type 2 diabetes, in which the diabetes drug metformin improves memory impairment. Because IRS1 and IRS2 signaling pathways are regulated through complex mechanisms including positive and negative feedback loops, whether the elevated phosphorylation of IRS1 at specific serine sites found in AD brains is a primary response to cognitive dysfunction remains unknown. Here, we examine the associations between IRS 1 /1 RS2-mediated signaling in the central nervous system and cognitive decline.
文摘There are many advantages of combining incretin therapy[glucagon-like peptide-1(GLP-1)receptor agonists and dipeptidyl peptidase-4(DPP-4)inhibitors]with insulin therapy as a glucose-lowering strategy in type2 diabetes.One important advantage is the complementary mode of the mechanistic action of incretin and insulin therapy.Another advantage is the reduction in risk of hypoglycemia and weight gain when adding incretin therapy to insulin.Several clinical trials have studied the addition of GLP-1 receptor agonists[exenatide BID(twice daily),lixisenatide,albiglutide]or DPP-4inhibitors(vildagliptin,sitagliptin,saxagliptin,alogliptin,linagliptin)to ongoing insulin therapy or adding insulin to ongoing therapy with a GLP-1 receptor agonist(liraglutide).These studies show improved glycemia in the presence of limited risk for hypoglycemia and weight gain with the combination of incretin therapy with insulin.This article reviews the background and clinical studies on this combination.
