Soluble ULBP suppresses natural killer cell activity via down-regulating NKG2D expression

Our previous studies show that growth hormone overexpression (GHo) upregulates the expression of the IGF-1R and IGF-2R resulting in the protection of the EL4 lymphoma cell line from apoptosis. In this study, we report that GHo also increases TGF-beta1 protein expression measured by luciferase promoter assay, Western analysis, and ELISA. Further, the data show that antibody to TGF-betaR2 decreases TGF-beta1 promoter activity to the level of vector alone control cells. GHo cells treated with (125)I-rh-latent TGF-beta1 showed increased activation of latent TGF-beta1 as measured by an increase in the active 24kDa, TGF-beta1 compared to vector alone control cells. The ability of endogenous GH to increase TGF-beta1 expression is blocked in EL4 cells by antisense but not sense oligodeoxynucleotides or in cells cultured with antibody to growth hormone (GH). The data suggest that endogenous GH may protect from apoptosis through the IGF-1R receptor while limiting cellular growth through increased expression and activation of TGF-beta1.     

Fibrin patch-based insulin-like growth factor-1 gene-modified stem cell transplantation repairs ischemic myocardium

Bone marrow mesenchymal stem cells (BMSCs), tissue-engineered cardiac patch, and therapeutic gene have all been proposed as promising therapy strategies for cardiac repair after myocardial infarction. In our study, BMSCs were modified with insulin-like growth factor-1 (IGF-1) gene, loaded into a fibrin patch, and then transplanted into a porcine model of ischemia/reperfusion (I/R) myocardium injury. The results demonstrated that IGF-1 gene overexpression could promote proliferation of endothelial cells and cardiomyocyte-like differentiation of BMSCs in vitro. Four weeks after transplantation of fibrin patch loaded with gene-modified BMSCs, IGF-1 overexpression could successfully promote angiogenesis, inhibit remodeling, increase grafted cell survival and reduce apoptosis. In conclusion, the integrated strategy, which combined fibrin patch with IGF-1 gene modified BMSCs, could promote the histological cardiac repair for a clinically relevant porcine model of I/R myocardium injury.     

Discovery of 2,4-bis-arylamino-1,3-pyrimidines as insulin-like growth factor-1 receptor (IGF-1R) inhibitors

The insulin-like growth factor-1 receptor (IGF-1R) plays an important role in the regulation of cell growth and differentiation, and in protection from apoptosis. IGF-1R has been shown to be an appealing target for the treatment of human cancer. Herein, we report the synthesis, structure-activity relationships (SAR), X-ray cocrystal structure and in vivo tumor study results for a series of 2,4-bis-arylamino-1,3-pyrimidines.     

A redox-sensitive pathway mediates oxidized LDL-induced downregulation of insulin-like growth factor-1 receptor

Oxidized low density lipoprotein (OxLDL) has multiple proatherogenic effects, including induction of apoptosis. We have recently shown that OxLDL markedly downregulates insulin-like growth factor-1 receptor (IGF-1R) in human aortic smooth muscle cells, and that IGF-1R overexpression blocks OxLDL-induced apoptosis. We hypothesized that specific OxLDL-triggered signaling events led to IGF-1R downregulation and apoptosis. We examined OxLDL signaling pathways and found that neither IGF-1R downregulation nor the proapoptotic effect was blocked by inhibition of OxLDL-triggered extracellular signal-regulated kinase, p38 mitogen-activated protein kinase (MAPK), or peroxisome proliferator-activated receptor gamma (PPARgamma) signaling pathways, as assessed using specific inhibitors. However, antioxidants, polyethylene glycol catalase, superoxide dismutase, and Trolox completely blocked OxLDL downregulation of IGF-1R and OxLDL-induced apoptosis. Nordihydroguaiaretic acid, AA-861, and baicalein, which are lipoxygenase inhibitors and also have antioxidant activity, blocked IGF-1R downregulation and apoptosis as well as reactive oxygen species (ROS) production. These results suggest that OxLDL enhances ROS production possibly through lipoxygenase activity, leading to IGF-1R downregulation and apoptosis. Furthermore, anti-CD36 scavenger receptor antibody markedly inhibited OxLDL-induced IGF-1R downregulation and apoptosis as well as ROS production. In conclusion, our data demonstrate that OxLDL downregulates IGF-1R via redox-sensitive pathways that are distinct from OxLDL signaling through MAPK- and PPARgamma-involved pathways but may involve a CD36-dependent mechanism.     

胰岛素样生长因子-1 对脂肪间充质干细胞增殖的影响

目的：探讨胰岛素样生长因子-1(insulin-like growth factor-1,IGF-1)对脂肪间充质干细胞(adipose-derived stem cells,ADSCs) 增殖的影响。方法：采用密度梯度离心法结合贴壁法分离脂肪间充质干细胞,接种于含体积分数为10%的胎牛血清的DMEM 培 养基中行贴壁培养。流式细胞仪检测ADSCs表面标志物(CD90、CD29、CD31、CD34、CD45)的表达情况,利用成骨、成脂诱导液诱 导ADSCs 向成骨细胞、成脂细胞分化,用碱性磷酸酶、油红O 染色观察。采用终浓度为0、5、10、15、20、30 ng/mL IGF的培养基培 养ADSCs,利用Edu 染色标记ADSCs,分析不同浓度的IGF-1 对ADSCs增殖的影响。结果：流式细胞术显示ADSCs的表型分子 CD90、CD29 呈阳性,CD31、CD45 呈阴性,成骨诱导后碱性磷酸酶染色阳性,成脂诱导后油红O染色可见大量脂滴,表明培养的 ADSCs具有成骨、成脂分化的能力。IGF-1 促进ADSCs 增殖的作用随IGF-1 的作用浓度的增加而增加,并逐渐趋于饱和,在趋于 15 滋g/mL的浓度时达到最大促增殖作用,且随着IGF-1 作用时间的延长其促ADSCs 增殖的作用逐渐增强。结论：本实验成功分 离培养ADSCs,IGF-1 对体外培养的ADSCs 有促进增殖的作用。     

The inhibition of angiogenesis and tumor growth by denbinobin is associated with the blocking of insulin-like growth factor-1 receptor signaling

Denbinobin, which is a phenanthraquinone derivative present in the stems of Ephemerantha lonchophylla, has been demonstrated to display antitumor activity. Recent reports suggest that the enhanced activity of insulin-like growth factor-1 receptor (IGF-1R) is closely associated with tumor angiogenesis and growth. This study aims at investigating the roles of denbinobin in suppressing these effects and at further elucidating the underlying molecular mechanisms. In the present study, we used an in vivo xenograft model antitumor and the Matrigel implant assays to show that denbinobin suppresses lung adenocarcinoma A549 growth and microvessel formation. Additionally, crystal violet and capillary-like tube formation assays indicated that denbinobin selectively inhibits insulin-like growth factor-1 (IGF-1)-induced proliferation (GI50=1.3×10⁻⁸ M) and tube formation of human umbilical vascular endothelial cells (HUVECs) without influencing the effect of epidermal growth factor; vascular endothelial growth factor and basic fibroblast growth factor. Furthermore, denbinobin inhibited the IGF-1-induced migration of HUVECs in a concentration-dependent fashion. Western blotting and immunoprecipitation demonstrated that denbinobin causes more efficient inhibition of IGF-1-induced activation of IGF-1R and its downstream signaling targets, including , extracellular signal-regulated kinase, Akt, mTOR, p70S6K, 4EBP and cyclin D1. All of our results provide evidences that denbinobin suppresses the activation of IGF-1R and its downstream signaling pathway, which leads to the inhibition of angiogenesis. Our findings suggest that denbinobin may be a novel IGF-1R kinase inhibitor and has potential therapeutic abilities for angiogenesis-related diseases such as cancer.     

Role of insulin-like growth factor-1 (IGF-1) in regulating cell cycle progression

Aims

Insulin-like growth factor-1 (IGF-1) is a polypeptide protein hormone, similar in molecular structure to insulin, which plays an important role in cell migration, cell cycle progression, cell survival and proliferation. In this study, we investigated the possible mechanisms of IGF-1 mediated cell cycle redistribution and apoptosis of vascular endothelial cells.

Method

Human umbilical vein endothelial cells (HUVECs) were pretreated with 0.1, 0.5, or 2.5 μg/mL of IGF-1 for 30 min before the addition of Ang II. Cell cycle redistribution and apoptosis were examined by flow cytometry. Expression of Ang II type 1 (AT₁) mRNA and cyclin E protein were determined by RT-PCR and Western blot, respectively.

Results

Ang II (1 μmol/L) induced HUVECs arrested at G₀/G₁, enhanced the expression level of AT₁ mRNA in a time-dependent manner, reduced the enzymatic activity of nitric oxide synthase (NOS) and nitric oxide (NO) content as well as the expression level of cyclin E protein. However, IGF-1 enhanced NOS activity, NO content, and the expression level of cyclin E protein, and reduced the expression level of AT₁ mRNA. L-NAME significantly counteracted these effects of IGF-1.

Conclusions

Our data suggests that IGF-1 can reverse vascular endothelial cells arrested at G₀/G₁ and apoptosis induced by Ang II, which might be mediated via a NOS-NO signaling pathway and is likely associated with the expression levels of AT1 mRNA and cyclin E proteins.     

Conversion of growth hormone-secreting cells into prolactin-secreting cells and its promotion by insulin and insulin-like growth factor-1 in vitro

The newly established rat pituitary cell line, MtT/S, has pituitary somatotroph (growth hormone-producing cell)-like characteristics, i.e., the cells produce growth hormone (GH), possess GH-immunopositive secretory granules, and respond to GH-releasing hormone. When MtT/S cells were cultured in regular medium no prolactin (PRL) cells were observed and PRL was not detected, by radioimmunoassay or Western blot analysis, in the medium or the cells. However, GH production and the GH cell population decreased markedly when the cells were incubated with insulin or insulin-like growth factor-1 (IGF-1). After stimulation with insulin or IGF-1 there was a 2-day lag period, then some PRL was detected in the medium; after 5 days a number of PRL cells appeared. Double immunocytochemistry indicated clearly that no cell contained both PRL and GH. These results show that insulin and IGF-1 stimulate conversion of MtT/S cell line GH cells to PRL cells. This suggests that the MtT/S cell line is an excellent model system which shows the GH-cell/PRL-cell lineage.     

Insulin-like growth factor-1 signaling in cardiac aging

Cardiovascular disease (CVD) is the leading cause of death in most developed countries. Aging is associated with enhanced risk of CVD. Insulin-like growth factor-1 (IGF-1) binds to its cognate receptor, IGF-1 receptor (IGF-1R), and exerts pleiotropic effects on cell growth, differentiation, development, and tissue repair. Importantly, IGF-1/IGF-1R signaling is implicated in cardiac aging and longevity. Cardiac aging is an intrinsic process that results in cardiac dysfunction, accompanied by molecular and cellular changes. In this review, we summarize the current state of knowledge regarding the link between the IGF-1/IGF-1R system and cardiac aging. The biological effects of IGF-1R and insulin receptor will be discussed and compared. Furthermore, we describe data regarding how deletion of IGF-1R in cardiomyocytes of aged knockout mice may delay the development of senescence-associated myocardial pathologies. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.     

胰岛素样生长因子-1对脂肪间充质干细胞增殖的影响

目的：探讨胰岛素样生长因子-1（insulin-like growth factor-1,IGF-1）对脂肪间充质干细胞（adipose-derived stem cells,ADSCs）增殖的影响。方法：采用密度梯度离心法结合贴壁法分离脂肪间充质干细胞,接种于含体积分数为10%的胎牛血清的DMEM培养基中行贴壁培养。流式细胞仪检测ADSCs表面标志物（CD90、CD29、CD31、CD34、CD45）的表达情况,利用成骨、成脂诱导液诱导ADSCs向成骨细胞、成脂细胞分化,用碱性磷酸酶、油红O染色观察。采用终浓度为0、5、10、15、20、30 ng/mL IGF的培养基培养ADSCs,利用Edu染色标记ADSCs,分析不同浓度的IGF-1对ADSCs增殖的影响。结果：流式细胞术显示ADSCs的表型分子CD90、CD29呈阳性,CD31、CD45呈阴性,成骨诱导后碱性磷酸酶染色阳性,成脂诱导后油红O染色可见大量脂滴,表明培养的ADSCs具有成骨、成脂分化的能力。IGF-1促进ADSCs增殖的作用随IGF-1的作用浓度的增加而增加,并逐渐趋于饱和,在趋于15μg/mL的浓度时达到最大促增殖作用,且随着IGF-1作用时间的延长其促ADSCs增殖的作用逐渐增强。结论：本实验成功分离培养ADSCs,IGF-1对体外培养的ADSCs有促进增殖的作用。     

Proprotein convertases regulate insulin-like growth factor 1-induced membrane-type 1 matrix metalloproteinase in VSMCs via endoproteolytic activation of the insulin-like growth factor-1 receptor

The IGF-1 receptor (IGF-1R) and MT1-MMP are synthesized as larger precursor proproteins, which require endoproteolytic activation by the proprotein convertases (PCs) furin/PC5 to gain full biological activity. The aim of this study was to investigate the contribution of PCs to IGF-1R and/or MT1-MMP activation in vascular smooth muscle cells (VSMCs) as well as VSMC proliferation/migration, which are key elements in vascular remodeling. Furin and PC5 mRNAs and proteins were found in VSMCs. Inhibition of furin-like PCs with the specific pharmacological inhibitor dec-CMK inhibited IGF-1R endoproteolytic activation. Inhibition of IGF-1R maturation abrogated IGF-induced IGF-1R autophosphorylation, PI3-kinase and MAPK induction, as well as VSMC proliferation (p<0.05 vs. controls), whereas it had no effect of PDGF-stimulated signaling pathways or cell growth. Both, IGF-1 and PDGF-BB, induced MT1-MMP expression, but only IGF-1-mediated MT1-MMP induction was inhibited by dec-CMK. Induction of MMP-2 by IGF-1 was inhibited by the PI3-kinase inhibitor wortmannin, but not by the MEK-inhibitor PD98059. Dec-CMK inhibited VSMC chemotaxis comparable to the effects of the MMP-inhibitor GM6001 (both p<0.05 vs. controls), supporting that MMPs are involved. In conclusion, this study demonstrates that targeting furin-like PCs and thus inhibiting IGF-1R activation is a novel target to inhibit IGF-1-mediated signaling and cell functions, such as IGF-1-induced MT1-MMP/MMP-2 in VSMCs.     

Tyrosine kinase-independent activation of extracellular-regulated kinase (ERK) 1/2 by the insulin-like growth factor-1 receptor

The extracellular-regulated kinase (ERK1/2) is a key conduit for transduction of signals from growth factor receptors to the nucleus. Previous work has shown that ERK1/2 activation in response to IGF-1 may require the participation of G proteins, but the role of the receptor tyrosine kinase in this process has not been clearly resolved. This investigation of IGF-1 receptor function was therefore designed to examine the contribution of the receptor tyrosine kinase to ERK1/2 activation. Phosphorylation of ERK1/2 in smooth muscle cells following treatment with IGF-1 was not blocked by pretreatment with AG1024 or picropodophylin, inhibitors of the IGF-1 receptor tyrosine kinase. Likewise, IGF-1 activated ERK1/2 in cells expressing a kinase-dead mutant of the IGF-1 receptor. ERK1/2 activation was unaffected by the phosphatidylinositol 3-kinase inhibitor LY-294002, but was sensitive to inhibitors of Src kinase, phospholipase C and Gβγ subunit signalling. Treatment with αIR-3, a neutralizing monoclonal antibody, also stimulated ERK1/2 phosphorylation without concomitant activation of the receptor tyrosine kinase. Phosphoprotein mapping of IGF-1 and αIR-3 treated cells confirmed that antibody-induced ERK1/2 phosphorylation occurred in the absence of tyrosine kinase phosphorylation, and enabled extension of these findings to p38 MAPK. These results suggest that stimulation of ERK1/2 phosphorylation by IGF-1 does not require activation of the receptor tyrosine kinase.     

Effects of insulin-like growth factor-1 on okadaic acid-induced apoptosis in SH-SY5Y cells

The effects of insulin-like growth factor-1 (IGF-1) on the cytotoxicity and apoptosis induced by okadaic acid (OA) in SH-SY5Y cells were investigated. Cell viability was measured using the MTT (3-(4,5-dimethylthiazolyl-2)-2,-5-diphenyltetrazolium bromide) assay. Early and late apoptosis/necrosis were analyzed by flow cytometry using Annexin V and propidium iodide (PI) double-staining. Caspase-3 activation was detected by Western blot analysis. Preincubation with IGF-1 for 24 h prevented cytotoxicity induced by 40 nM OA given for 24 h, and the MTT value significantly increased. Incubation with 20 nM OA for 24 h caused a marked increase in the percentage of early apoptotic and late apoptotic/necrotic cells, which was not dependent on the activation of caspase-3. OA-induced apoptosis was significantly decreased by pretreatment with 10 ng/ml of IGF-1 for 24 h. The results supported the hypothesis that IGF-1 may be useful in the treatment of Alzheimer's disease.     

IGF-1对细胞凋亡的抑制调控

胰岛素样生长因子-1（insulin—like growth factor,IGF—1）是胰岛素样生长因子家族中的一种,通过与IGF-1受体相结合产生生物学效应,是通过内分泌、自分泌和旁分泌的三种途径分泌的低分子多肽。近些年来,研究发现IGF-1不仅具有胰岛素类似的功能以及介导生长激素的作用,还是多种类型细胞凋亡的一个重要抑制因子。本文就IGF-1抑制细胞凋亡的信号转导途径和IGF-1对Bcl-2家族、caspases家族以及关键转录因子的调控机制作一综述。     

生长激素/胰岛素样生长因子1与阿尔茨海默病

生长激素／胰岛素样生长因子-1（GH／IGF-1）轴的合成、分泌、调节及生物学活性与阿尔茨海默病（AD）有密切关系。生长激素（GH）的合成和分泌受生长激素释放激素（GHRH）正向调节。GH／IGF-1轴活性下降导致一系列生理功能变化。GH／IGF-1缺乏可引起衰老及神经退行性变（AD）而导致认知功能的下降,相应激素的补给可以抑制或逆转这种认知障碍。越来越多的证据表明：GH／IGF-1参与AD型痴呆病理过程,对AD有很好的治疗应用前景。本文就生长激素／胰岛素样生长因子1在AD发病中的机理和药理学研究做一综述。     

Relationship of growth hormone and insulin-like growth factor-1 genotypes with growth and carcass traits in swine

The contribution of chromosomal regions linked to growth hormone (GH) and insulin-like growth factor-1 (IGF-1) loci to variation in preweaning average daily gain, postweaning average daily gain (ADG), 10th rib backfat, loin-eye area and muscle pH were evaluated. Offspring of four purebred sires (A–D; n = 150, 195, 148 and 136, respectively) and two crossbred sires (E and F; n = 157 and 145, respectively) were genotyped initially with GH and IGF-1 markers. When results of single marker analysis suggested possible linkage with a quantitative trait locus (QTL), additional flanking markers were typed for the family and interval mapping was performed. Growth hormone genotype was not associated with the traits evaluated in the study. Evidence suggestive of linkage was found for IGF-1 genotype and ADG in one sire family (lod = 2·3) where differences were 0.032 ± 0·01 kg/day for alternative sire alleles. Evidence for a putative ADG QTL was greatest in the interval between IGF-1 and Sw1071. A similar genomic region has been associated with growth variation in mice; however, QTL mapping precision in the current study is insufficient to establish similarity.     

Lentivirus-mediated shRNA targeting insulin-like growth factor-1 receptor (IGF-1R) enhances chemosensitivity of osteosarcoma cells in vitro and in vivo

The overexpression of the type 1 insulin-like growth factor receptor (IGF-1R) has been reported to be associated with malignant transformation, tumor development and chemo- or radioresistance of tumor cells. Previously, we have reported that inhibition of IGF-1R could reverse the radioresistance of human osteosarcoma cells. However, whether inhibition of IGF-1R could enhance chemosensitivity of ostesosarcoma cells is unclear. In this study, lentivirus-mediated shRNA was employed to downregulate endogenous IGF-1R expression to study the function of IGF-1R in chemoresistance of osteosarcoma cells. Results showed that lentivirus-mediated shRNA targeting IGF-1R combined with chemotherapy (CDDP or DTX) could lead to growth suppression of osteosarcoma cells not only in vitro but also in vivo. Moreover, inhibition of IGF-1R gene combined with chemotherapy also synergistically enhanced Caspase-3-mediated apoptosis of osteosarcoma cells. The synergistical enhancement of apoptosis might be associated with downregulation of Bcl-2 and upregulation of Bax in osteosarcoma cells induced by IGF-1R inhibition. Therefore, the overexpression of IGF-1R gene might play important roles in chemoresistance of osteosarcoma cells, and lentivirus-mediated RNAi targeting IGF-1R would be an attractive anti-cancer strategy to chemosensitization of osteosarcoma cell.     

Growth hormone-stimulated insulin-like growth factor-1 expression in rainbow trout (Oncorhynchus mykiss) hepatocytes is mediated by ERK, PI3K-AKT, and JAK-STAT

Growth hormone (GH) initiates many of its growth-promoting actions by binding to GH receptors (GHR) and stimulating the synthesis and secretion of insulin-like growth factor-1 (IGF-1) from the liver and other sites. In this study, we used hepatocytes isolated from rainbow trout as a model system in which to determine the molecular signaling events of GH in fish. GH directly stimulated the phosphorylation of ERK, protein kinase B (Akt), a downstream target of phosphatidylinositol 3-kinase (PI3K), JAK2, and STAT5 in hepatocytes incubated in vitro. Activation of ERK, Akt, JAK2, and STAT5 was rapid, occurring within 5-10 min, and was concentration dependent. GH-induced ERK activation was completely blocked by the ERK pathway inhibitor, U0126, and the JAK2 inhibitor, 1,2,3,4,5,6-hexabromocyclohexane (Hex), and was partially blocked by the PI3K inhibitor LY294002. GH-stimulated Akt activation was completely blocked by LY294002 and Hex, but was not affected by U0126; whereas, STAT5 activation by GH was blocked only by Hex, and was not affected by either U0126 or LY294002. GH stimulated hepatic expression of IGF-1 mRNA as well as the secretion of IGF-1, effects that were partially or completely blocked by U0126, LY294002, and Hex. These results indicate that GHR linkage to the ERK, PI3K/Akt, or STAT pathways in trout liver cells requires activation of JAK2, and that GH-stimulated IGF-1 synthesis and secretion is mediated through the ERK, PI3K/Akt, and JAK-STAT pathways.