Secretion Of Insulin-like Growth Factor Research Articles

Arginine induces IGF-1 secretion from the endoplasmic reticulum

Arginine is a semi-essential amino acid with multiple functions, including stimulating the secretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). IGF-1, which is produced by hepatocytes, plays important roles in cellular metabolism, proliferation, and growth. Previous studies showed that arginine-induced IGF-1 secretion occurs via two pathways: a GH-dependent pathway and an arginine-dependent pathway with an unknown mechanism. In this study, we identified the mechanisms regulating IGF-1 secretion. First, GH stimulates the translation of IGF-1 and increases IGF-1 protein levels, leading to IGF-1 secretion. As observed in fasted mice and hepatocytes cultivated in arginine-depleted medium, decreases in arginine concentrations resulted in IGF-1 retention in the endoplasmic reticulum. Arginine administration reverses this retention, leading to IGF-1 secretion. These data describe a novel IGF-1 secretion control system in the endoplasmic reticulum.

5-ARI induces autophagy of prostate epithelial cells through suppressing IGF-1 expression in prostate fibroblasts.

Objectives5α‐reductase inhibitor (5‐ARI) is a commonly used medicine in the treatment of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH). Our study mainly focuses on the mechanism of BPH development after 5ARI treatment.Materials and MethodsProstate specimens from patients were collected. Insulin‐like growth factor 1 (IGF‐1), Beclin‐1, LC3 levels, was analysed by immunohistochemistry. The role IGF‐1 on autophagic flux in prostate epithelial cells was studied. Additionally, effect of autophagy on recombinant grafts consisting of prostate stromal and epithelial cells in nude mice was investigated.ResultsWe demonstrated that IGF‐1 expression is down‐regulated in prostate fibroblasts after long‐term 5‐ARI application. A decrease in IGF‐1 levels was found to activate autophagic flux through the mTOR pathway in prostate epithelial cells, while the inhibition of IGF‐1 receptor function induced autophagy in prostate epithelial cells. In addition, we revealed that blocking autophagic flux initiation can reduce the volume of recombinant grafts in vivo. Finally, our findings suggest that long‐term 5‐ARI application reduces IGF‐1 secretion by prostatic stromal cells, thereby inducing autophagy of prostatic epithelial cells, which is one of the mechanisms underlying BPH pathogenesis and progression.ConclusionsFocusing on the autophagy induced by low levels of IGF‐1 in prostatic epithelial cells, after elucidating AR signalling impairment of prostate stromal cells, might provide a novel strategy for the treatment and prevention of BPH development.

Effects of Xiaotan Tongfu decoction on hepatic metastasis in obesity-associated colorectal cancer.

ObjectiveThis study was performed to assess the influence of obesity on colorectal cancer (CRC) and investigate the efficacy of Xiaotan Tongfu (XTTF) decoction to CRC treatment.MethodsBALB/C mice were used to establish an obesity-associated CRC model by a high-fat diet and tumor implantation. The tumors were harvested from mice inoculated with CT26 cell suspension. Body weight, liver weight, hepatic metastasis, and histological changes were observed. Immunohistochemical analysis and real-time polymerase chain reaction were performed to measure the levels of insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), and IGF binding protein 3 (IGFBP-3).ResultsObesity influenced the secretion of IGFs and aggravated CRC, while XTTF decoction inhibited the process of hepatic metastasis in CRC by upregulating the secretion of IGF-1/IGF-1R and downregulating the secretion of IGFBP-3.ConclusionsThis study provides evidence that XTTF decoction can serve as a candidate curative treatment for CRC.

Subacute Transplantation of Native and Genetically Engineered Neural Progenitors Seeded on Microsphere Scaffolds Promote Repair and Functional Recovery After Traumatic Brain Injury.

There is intense interest and effort toward regenerating the brain after severe injury. Stem cell transplantation after insult to the central nervous system has been regarded as the most promising approach for repair; however, engrafting cells alone might not be sufficient for effective regeneration. In this study, we have compared neural progenitors (NPs) from the fetal ventricular zone (VZ), the postnatal subventricular zone, and an immortalized radial glia (RG) cell line engineered to conditionally secrete the trophic factor insulin-like growth factor 1 (IGF-1). Upon differentiation in vitro, the VZ cells were able to generate a greater number of neurons than subventricular zone cells. Furthermore, differentiated VZ cells generated pyramidal neurons. In vitro, doxycycline-driven secretion of IGF-1 strongly promoted neuronal differentiation of cells with hippocampal, interneuron and cortical specificity. Accordingly, VZ and engineered RG-IGF-1-hemagglutinin (HA) cells were selected for subsequent in vivo experiments. To increase cell survival, we delivered the NPs attached to a multifunctional chitosan-based scaffold. The microspheres containing adherent NPs were injected subacutely into the lesion cavity of adult rat brains that had sustained controlled cortical impact injury. At 2 weeks posttransplantation, the exogenously introduced cells showed a reduction in stem cell or progenitor markers and acquired mature neuronal and glial markers. In beam walking tests assessing sensorimotor recovery, transplanted RG cells secreting IGF-1 contributed significantly to functional improvement while native VZ or RG cells did not promote significant recovery. Altogether, these results support the therapeutic potential of chitosan-based multifunctional microsphere scaffolds seeded with genetically modified NPs expressing IGF-1 to promote repair and functional recovery after traumatic brain injuries.

The intrinsically disordered E-domains regulate the IGF-1 prohormones stability, subcellular localisation and secretion

Insulin-like growth factor-1 (IGF-1) is synthesised as a prohormone (proIGF-1) requiring enzymatic activity to yield the mature IGF-1. Three proIGF-1s are encoded by alternatively spliced IGF-1 mRNAs: proIGF-1Ea, proIGF-1Eb and proIGF-1Ec. These proIGF-1s have a common IGF-1 mature sequence but different E-domains. The structure of the E-domains has not been resolved, and their molecular functions are still unclear. Here, we show that E-domains are Intrinsically Disordered Regions that have distinct regulatory functions on proIGF-1s production. In particular, we identified a highly conserved N-glycosylation site in the Ea-domain, which regulated intracellular proIGF-1Ea level preventing its proteasome-mediated degradation. The inhibition of N-glycosylation by tunicamycin or glucose starvation markedly reduced proIGF-1Ea and mature IGF-1 production. Interestingly, 2-deoxyglucose, a glucose and mannose analogue, increased proIGF-1Ea and mature IGF-1 levels, probably leading to an accumulation of an under-glycosylated proIGF-1Ea that was still stable and efficiently secreted. The proIGF-1Eb and proIGF-1Ec were devoid of N-glycosylation sites, and hence their production was unaffected by N-glycosylation inhibitors. Moreover, we demonstrated that alternative Eb- and Ec-domains controlled the subcellular localisation of proIGF-1s, leading to the nuclear accumulation of both proIGF-1Eb and proIGF-1Ec. Our results demonstrated that E-domains are regulatory elements that control IGF-1 production and secretion.

Adipose-derived stem cells improve erectile function partially through the secretion of IGF-1, bFGF, and VEGF in aged rats.

Adipose-derived stem cells (ADSCs) have recently been considered as a promising therapy for erectile dysfunction (ED). However, the mechanism of ADSC-based therapy is unclear. Insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) secreted by ADSCs were assessed invitro. Sixteen 24-month-old male Sprague-Dawley rats were used for comparative analysis of 2-week treatment with labeled ADSCs or PBS. Eight additional 5-month-old rats were used as a young rat group. At 2weeks post-transplantation, all rats were analyzed for erectile function, cavernous IGF-1, bFGF and VEGF levels, and penile histology. Conditioned medium and co-culture systems were used in cell experiments to detect how growth factors act on corpus cavernosum smooth muscle cells (CCSMCs) under oxidative stress conditions via crystal violet staining and immunofluorescence staining. We found that ADSCs secreted significantly higher IGF-1, bFGF, and VEGF levels in culture medium compared with basal medium. Compared with young rats, untreated aged rats had significantly lower Max ICP/MAP and ADSC treatment significantly increased the ratio. Immunofluorescence staining demonstrated a small number of labeled ADSCs in the corpus cavernosum. The untreated aged rats showed significantly decreased cavernous IGF-1, bFGF, and VEGF levels and significantly decreased contents of cavernous smooth muscle and endothelium compared with young rats. ADSC treatment partially normalized these alterations. In cell experiments, the groups receiving growth factor neutralizing antibody separately or combined had significantly decreased numbers of CCSMCs compared with control groups. These results indicated that ADSC treatment may improve aging-related ED partially through the secretion of IGF-1, bFGF, and VEGF.

Knockdown of Chloride Channel-3 Inhibits Breast Cancer Growth In Vitro and In Vivo.

PurposeChloride channel-3 (ClC-3) is a member of the chloride channel family and plays a critical role in a variety of cellular activities. The aim of the present study is to explore the molecular mechanisms underlying the antitumor effect of silencing ClC-3 in breast cancer.MethodsHuman breast cancer cell lines MDA-MB-231 and MCF-7 were used in the experiments. Messenger RNA and protein expression were examined by quantitative real-time polymerase chain reaction and western blot analysis. Cell proliferation was measured by the bromodeoxyuridine method, and the cell cycle was evaluated using fluorescence-activated cell sorting. Protein interaction in cells was analyzed by co-immunoprecipitation. Tumor tissues were stained with hematoxylin-eosin and tumor burden was measured using the Metamorph software.ResultsBreast cancer tissues collected from patients showed an increase in ClC-3 expression. Knockdown of ClC-3 inhibited the secretion of insulin-like growth factor (IGF)-1, cell proliferation, and G1/S transition in breast cancer cells. In the mouse xenograft model of human breast carcinoma, tumor growth was significantly slower in animals injected with ClC-3-deficient cells compared with the growth of normal human breast cancer cells. In addition, silencing of ClC-3 attenuated the expression of proliferating cell nuclear antigen, Ki-67, cyclin D1, and cyclin E, as well as the activation of extracellular signalregulated protein kinases (ERK) 1/2, both in vitro and in vivo.ConclusionTogether, our data suggest that upregulation of ClC-3 by IGF-1 contributes to cell proliferation and tumor growth in breast cancer, and ClC-3 deficiency suppresses cell proliferation and tumor growth via the IGF/IGF receptor/ERK pathway.

Leukocyte-Poor Platelet-Rich Plasma-Derived Growth Factors Enhance Human Fibroblast Proliferation In Vitro.

BackgroundLeukocyte-poor platelet-rich plasma (LP-PRP) from peripheral blood is currently used as a concentrated source of growth factors to stimulate repair at sites of soft tissue injury. Fibroblasts are primary mediators of wound healing. Thus, we aimed to assess the positive effect of LP-PRP on human fibroblast proliferation in vitro.MethodsLP-PRP was prepared from 49 donors. The fibroblasts were seeded, and at 24 hours after seeding, 1 × 107/10 µL LP-PRP was added once to each well. The cells were harvested 10 times during study period at our planned points, and we examined cell proliferation using the water-soluble tetrazolium salt-1 assay. We collected the supernatants and measured the amount of growth factors such as platelet-derived growth factor (PDGF)-AB/BB, insulin-like growth factor-1 (IGF-1), transforming growth factor-β1 (TGF-β1), and vascular endothelial growth factor (VEGF), which are known to be involved in wound healing processes, by multiplex assay.ResultsHuman fibroblasts treated with LP-PRP showed a significant increase in proliferation when compared to untreated controls (p < 0.001 at days 4, 6, and 8). Multiplex cytokine assays revealed various secretion patterns. PDGF-AB/BB appeared at early time points and peaked before fibroblast proliferation. IGF-1 and TGF-β1 secretion gradually increased and peaked on days 4 and 6 post-treatment. The early VEGF concentration was lower than the concentration of other growth factors but increased along with cell proliferation.ConclusionsPlatelets in LP-PRP release growth factors such as PDGF, IGF-1, TGF-β1 and VEGF, and these growth factors have a promoting effect for human fibroblast proliferation, one of the important mediators of wound healing. These results suggest that growth factors derived from LP-PRP enhance the proliferation of human fibroblast.

Effects of l-arginine on growth hormone and insulin-like growth factor 1.

l-Arginine has been reported to promote cellular and organismal growth. In this study, the effects of l-arginine on the expression of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), the two key growth factors, are investigated in cultured GH3 pituitary epithelium and HepG2 cells, respectively. l-Arginine significantly induced the gene expression of GH and IGF-1 in GH3 pituitary epithelium and HepG2 hepatocytes respectively, and reduced IGF binding protein-1 gene expression in HepG2 cells assessed via quantitative polymerase chain reaction analysis. l-Arginine also significantly induced GH and IGF-1 hormone secretion from GH3 and HepG2 cells, respectively. In addition, the multi-target ELISA analysis conducted revealed that phosphorylation of p-38 MAPK, MEK, and JNK were significantly increased in HepG2 cells, suggesting l-arginine-induced activation of the MAPK signaling pathway. These results suggest that l-arginine promotes the synthesis and secretion of GH and IGF-1 in vitro and induces the MAPK signaling cascade in cultured hepatocytes.

Non-Islet Cell Tumor Hypoglycemia

SESSION TITLE: Non-Small Cell Lung Cancer SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Non-islet cell tumor hypoglycemia (NICTH) is a serious but rare complication seen with certain malignancies. Tumor over production of insulin-like growth factors (IGF) causes the increased utilization of glucose resulting in symptomatic hypoglycemia. CASE PRESENTATION: A 74 year old non-diabetic male with a medical history significant for sarcomatoid carcinoma of the right lung presented with altered mental status and global weakness. He had been diagnosed with sarcomatoid lung cancer 8 years ago and had undergone a lobectomy with radiation therapy, but had been lost of follow up. He denied any illicit drug use, including herbal or over the counter medications. On presentation, the patient was disoriented and unable to follow simple commands. Pulmonary auscultation revealed distant breath sounds, and a 1.5 by 1.5 cm lesion with central necrosis was present on his left buccal area. Laboratory investigations were significant for blood glucose of 28 mg/dL, confirming hypoglycemia, potassium of 2.8mEq/L, and a negative urine toxicology screen. A CT head was negative for acute events. CT chest, abdomen and pelvis showed progression of his sarcomatoid lung cancer. Administration of dextrose immediately resolved his symptoms. An extensive work-up during subsequent hypoglycemic events measured an IGF-1 of 51 ng/mL, IGF-II of 290 ng/mL, growth hormone of 0.6 ng/mL, C-Peptide of 0.16 ng/mL (low) and insulin levels at <1 uIU/mL. Big IGF-2 was not available at our facility. Based on these results a diagnosis of NICTH was made. DISCUSSION: A history and physical examination in a patient with an active tumor remains key in making the diagnosis. The mechanism of hypoglycemia in NICTH remains unclear but is thought to be related to tumor secretion of IGF, specifically big IGF-2, which suppresses glucagon and growth hormone, resulting in hypoglycemia. Some suggest the secretion of insulin by the tumor results in hypoglycemia. In addition to hypoglycemia, hypokalemia may be present due to the insulin like activity of IGF. In patients with NITCH, low serum insulin and C-peptide levels are seen during hypoglycemic episodes. Measurement of IGF-1, IGF-2, and big IGF-2 may be supportive as well, but should not deter diagnosis. Glucagon and dextrose intravenously can be used to help resolve the hypoglycemic events. Steroids have also been shown to help by increasing clearance of IGF-2. Treatment of the underlying malignancy provides a definite solution. CONCLUSIONS: Our patient deferred treatment for his advanced cancer. He was started on prednisone 60 mg once a day, with resolution of his symptoms upon discharge, and he remained asymptomatic at follow-up appointments, 2 and 4 weeks later. He was offered palliative care services, but declined as well. Reference #1: de Groot JW, Rikhof B, van Doorn J, et al. Non-islet cell tumour-induced hypoglycaemia: a review of the literature including two new cases. Endocr Relat Cancer. 2007;14(4):979-993. DISCLOSURE: The following authors have nothing to disclose: Oteni Hamilton, Timothy Legare, Sarah Dhannoon, Sayed Ali No Product/Research Disclosure Information

Adipose stem cells from chronic pancreatitis patients improve mouse and human islet survival and function

BackgroundChronic pancreatitis has surgical options including total pancreatectomy to control pain. To avoid surgical diabetes, the explanted pancreas can have islets harvested and transplanted. Immediately following total pancreatectomy with islet autotransplantation (TP-IAT), many islet cells die due to isolation and transplantation stresses. The percentage of patients remaining insulin free after TP-IAT is therefore low. We determined whether cotransplantation of adipose-derived mesenchymal stem cells (ASCs) from chronic pancreatitis patients (CP-ASCs) would protect islets after transplantation.MethodsIn a marginal mass islet transplantation model, islets from C57BL/6 mice were cotransplanted with CP-ASCs into syngeneic streptozotocin-treated diabetic mice. Treatment response was defined by the percentage of recipients reaching normoglycemia, and by the area under the curve for glucose and c-peptide in a glucose tolerance test. Macrophage infiltration, β-cell apoptosis, and islet graft vasculature were measured in transplanted islet grafts by immunohistochemistry. mRNA expression profiling of 84 apoptosis-related genes in islet grafts transplanted alone or with CP-ASCs was measured by the RT2 Profiler™ Apoptosis PCR Array. The impact of insulin-like growth factor-1 (IGF-1) on islet apoptosis was determined in islets stimulated with cytokines (IL-1β and IFN-γ) in the presence and absence of CP-ASC conditioned medium.ResultsCP-ASC-treated mice were more often normoglycemic compared to mice receiving islets alone. ASC cotransplantation reduced macrophage infiltration, β-cell death, suppressed expression of TNF-α and Bcl-2 modifying factor (BMF), and upregulated expressions of IGF-1 and TNF Receptor Superfamily Member 11b (TNFRSF11B) in islet grafts. Islets cultured in conditioned medium from CP-ASCs showed reduced cell death. This protective effect was diminished when IGF-1 was blocked in the conditioned medium by the anti-IGF-1 antibody.ConclusionCotransplantation of islets with ASCs from the adipose of chronic pancreatitis patients improved islet survival and islet function after transplantation. The effects are in part mediated by paracrine secretion of IGF-1, suppression of inflammation, and promotion of angiogenesis. ASCs from chronic pancreatitis patients have the potential to be used as a synergistic therapy to enhance the efficacy of islet transplantation following pancreatectomy.

Bone marrow mesenchymal stem cells repair the hippocampal neurons and increase the expression of IGF-1 after cardiac arrest in rats.

The present study aimed to investigate the beneficial effects and underlying mechanisms of bone marrow mesenchymal stem cells (BMSCs) on global ischemic hypoxic brain injury. Cells collected from the femurs and tibias of male Sprague Dawley rats were used to generate BMSCs following three culture passages. A rate model of cardiac arrest (CA) was induced by asphyxia. One hour following return of spontaneous circulation (ROSC), BMSCs were transplanted through injection into the tail vein. Neurological status was assessed using modified neurological severity score (mNSS) tests 1, 3 and 7 days following ROSC. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemical staining were used to detect insulin-like growth factor 1 (IGF-1) expression in the hippocampus. Furthermore, double-fluorescent labeling of green fluorescent protein (GFP) and IGF-1 was used to detect the IGF-1 expression in transplanted BMSCs. Serum levels of protein S100-B were examined using ELISA. GFP-labeled BMSCs were observed in the hippocampus at 1, 3 and 7 days post transplantation through fluorescent microscopy. BMSC transplantation resulted in reduced protein S100-B levels. The mNSS of the BMSC-treatment group was significantly reduced compared with that of the CA group. The RT-qPCR analysis and immunohistochemistry results demonstrated that BMSC treatment significantly increased IGF-1 expression in the hippocampus. In addition, the double-fluorescent labeling results demonstrated that transplanted BMSCs expressed IGF-1 in the hippocampus. The results of the present study suggest that BMSC treatment promotes the recovery of cerebral function following CA in rats possibly through the secretion of IGF-1.

The energy sensing LKB1-AMPKα1 pathway regulates IGF1 secretion and consequent activation of the IGF1R-PKB pathway in primary hepatocytes.

The insulin-like growth factor 1 (IGF1) pathway has been linked with various diseases including diabetes, cancer and aging. In contrast to the well-established regulatory mechanisms controlling IGF1 expression, molecular mechanisms regulating its secretion are not fully understood. The AMP-activated protein kinase (AMPK) is a key energy sensor, and cumulative evidence shows that it is an attractive therapeutic target for treatment of diabetes, cancer and aging. Here we found that deficiency of AMPK promoted IGF1 secretion in mouse primary hepatocytes. Furthermore, we found that AMPKα1 but not AMPKα2 was involved in regulation of IGF1 secretion in mouse primary hepatocytes. Knockout of AMPK caused activation of the IGF1 receptor (IGF1R)-protein kinase B (PKB; also known as Akt) pathway in hepatocytes, which was mediated by hypersecretion of IGF1. Upstream of AMPK, liver kinase B1 (LKB1) was responsible for AMPK-dependent suppression of IGF1 secretion in hepatocytes. Collectively, these findings demonstrate that the energy-sensing LKB1-AMPK pathway regulates IGF1 secretion in mouse primary hepatocytes, which in turn regulates activation of the IGF1R-PKB pathway.

Dietary protein-induced hepatic IGF-1 secretion mediated by PPARγ activation.

Dietary protein or amino acid (AA) is a crucial nutritional factor to regulate hepatic insulin-like growth factor-1 (IGF-1) expression and secretion. However, the underlying intracellular mechanism by which dietary protein or AA induces IGF-1 expression remains unknown. We compared the IGF-1 gene expression and plasma IGF-1 level of pigs fed with normal crude protein (CP, 20%) and low-protein levels (LP, 14%). RNA sequencing (RNA-seq) was performed to detect transcript expression in the liver in response to dietary protein. The results showed that serum concentrations and mRNA levels of IGF-1 in the liver were higher in the CP group than in the LP group. RNA-seq analysis identified a total of 1319 differentially expressed transcripts (667 upregulated and 652 downregulated), among which the terms “oxidative phosphorylation”, “ribosome”, “gap junction”, “PPAR signaling pathway”, and “focal adhesion” were enriched. In addition, the porcine primary hepatocyte and HepG2 cell models also demonstrated that the mRNA and protein levels of IGF-1 and PPARγ increased with the increasing AA concentration in the culture. The PPARγ activator troglitazone increased IGF-1 gene expression and secretion in a dose dependent manner. Furthermore, inhibition of PPARγ effectively reversed the effects of the high AA concentration on the mRNA expression of IGF-1 and IGFBP-1 in HepG2 cells. Moreover, the protein levels of IGF-1 and PPARγ, as well as the phosphorylation of mTOR, significantly increased in HepG2 cells under high AA concentrations. mTOR phosphorylation can be decreased by the mTOR antagonist, rapamycin. The immunoprecipitation results also showed that high AA concentrations significantly increased the interaction of mTOR and PPARγ. In summary, PPARγ plays an important role in the regulation of IGF-1 secretion and gene expression in response to dietary protein.

Metformin inhibits the proliferation of benign prostatic epithelial cells.

ObjectiveBenign prostatic hyperplasia (BPH) is the most common proliferative abnormality of the prostate affecting elderly men throughout the world. Epidemiologic studies have shown that diabetes significantly increases the risk of developing BPH, although whether anti-diabetic medications preventing the development of BPH remains to be defined. We have previously found that stromally expressed insulin-like growth factor 1 (IGF-1) promotes benign prostatic epithelial cell proliferation through paracrine mechanisms. Here, we seek to understand if metformin, a first line medication for the treatment of type 2 diabetes, inhibits the proliferation of benign prostatic epithelial cells through reducing the expression of IGF-1 receptor (IGF-1R) and regulating cell cycle.MethodsBPE cell lines BPH-1 and P69, murine fibroblasts3T3 and primary human prostatic fibroblasts were cultured and tested in this study. Cell proliferation and the cell cycle were analyzed by MTS assay and flow cytometry, respectively. The expression of IGF-1R was determined by western-blot and immunocytochemistry. The level of IGF-1 secretion in culture medium was measured by ELISA.ResultsMetformin (0.5-10mM, 6-48h) significantly inhibited the proliferation of BPH-1 and P69 cells in a dose-dependent and time-dependent manner. Treatment with metformin for 24 hours lowered the G2/M cell population by 43.24% in P69 cells and 24.22% in BPH-1 cells. On the other hand, IGF-1 (100ng/mL, 24h) stimulated the cell proliferation (increased by 28.81% in P69 cells and 20.95% in BPH-1 cells) and significantly enhanced the expression of IGF-1R in benign prostatic epithelial cells. Metformin (5mM) abrogated the proliferation of benign prostatic epithelial cells induced by IGF-1. In 3T3 cells, the secretion of IGF-1 was significantly inhibited by metformin from 574.31pg/ml to 197.61pg/ml. The conditioned media of 3T3 cells and human prostatic fibroblasts promoted the proliferation of epithelial cells and the expression of IGF-1R in epithelial cells. Metformin abrogated the proliferation of benign prostatic epithelial cells promoted by 3T3 conditioned medium.ConclusionsOur study demonstrates that metformin inhibits the proliferation of benign prostatic epithelial cells by suppressing the expression of IGF-1R and IGF-1 secretion in stromal cells. Metformin lowers the G2/M cell population and simultaneously increases the G0/G1 population. Findings here might have significant clinical implications in management of BPH patients treated with metformin.

Endothelin signaling regulates mineralization and posttranscriptionally regulates SOST in TMOb cells via miR 126-3p.

Previously, our laboratory identified ECE‐1, encoding endothelin‐converting enzyme‐1 (ECE‐1), as a positional candidate for a pleiotropic quantitative trait locus affecting femoral size, shape, and biomechanical performance. We hypothesized that endothelin‐1 (ET‐1) signaling promotes osteogenesis. Exposure of immortalized mouse osteoblast (TMOb) cells to big ET‐1 increased mineralization. Following big ET‐1 treatment, we measured the secretion of insulin‐like‐growth factor‐1 (IGF1), dickkopf‐homolog‐1 protein 1 (DKK1), and sclerostin (SOST). In each case, big ET‐1 signaling changed secretion in a manner that favored increased osteogenic activity. Treatment with ECE‐1, endothelin receptor A (EDNRA), or WNT receptor antagonists inhibited the big ET‐1‐mediated increase in mineralization. In the presence of big ET‐1, message levels of Runx2, Igf1, Dkk1, and Sost are uncoupled from protein production, suggesting posttranscriptional regulation. To evaluate the role of big ET‐1 in normal bone physiology, we inhibited EDNRA signaling during mineralization in the absence of exogenous ET‐1. EDNRA blockade reduced mineralization, decreased IGF1, and increased DKK1 and SOST secretion, responses opposite to those induced by exogenous big ET‐1. Pharmacological and siRNA knockdown to inhibit ECE‐1 reduced mineralization and IGF1 secretion with decreasing DKK1 and decreasing or stable SOST secretion, suggesting a further, unknown role of ECE‐1 in osteoblast maturation. Previously we identified miR 126‐3p as a potential ET‐1‐responsive regulator of SOST in murine cells. Overexpression of miR126‐3p increased mineralization in TMOb cells and decreased SOST secretion. Osteoblasts express the ET‐1 signaling pathway and ET‐1 signaling is necessary for normal osteoblast differentiation and mineralization, acting through regulation of miRs that target osteogenic molecules.

Impacts on thepregnancy outcome in the mice of controlled ovarian hyperstimulation treated with acupuncture at different time points

To explore the optimal time of acupuncture intervention in the assisted reproduction. One hundred and twenty female mice and 60 male mice were collected. 20 female mice were selected in the natural period group and the rest 100 female mice were prepared as the model of controlled ovarian hyperstimulation (COH). The model mice were randomized into a COH group, a down-regulation group, a gonadotropins (Gn) start group, an injection of human chorionic gonadotropin (HCG) group and an embryo culture group, 20 mice in each one. The donor mice and receptor mice were subdivided in each group, 10 mice in each subgroup. One week before the experiment, vas deferens ligature was done in 30 male mice and the other 30 male mice did not receive ligature. In the down-regulation group, the Gn start group, the HCG injection group and the embryo culture group, electroacupuncture (EA) was applied to "Guanyuan" (CV 4), "Zhongji" (CV 3) and "Sanyinjiao" (SP 6) at the time points accordingly. EA stimulation was in the condition of continuous wave, 2 Hz and 1 mA. No inter-vention was given in the natural period group and the COH group. On the day of HCG injection, the donor mice and the non-ligatured male mice were put in the same cage of each group. The fertilized ovum was collected with the date of fertilization marked and was fostered in the incubator. At the ratio of 1:1, the receptor mice and ligatured mice were put in the same cage in each group. The vaginal plug was examined in the next morning. The pseudopregnancy was marked with the date of plug observed. In the 68th hour of embryo culture, the embryo of the donor was shifted to the receptor on the same day when the plug was observed. The clinical pregnancy rate and embryo imbed site number were observed. RT-PCR assay was adopted to determine the expression of insulin-like growth factor-1 (IGF-1) mRNA in endometrium. In the COH group, the pregnancy rate, average imbed site number and endometrial IGF-1 mRNA expression were all significantly lower than those in the natural period group (all P<0.01). After EA treatment, in the Gn group, the HCG injection group and the embryo culture group, the pregnancy rates were higher significantly than those in the COH group (P<0.05, P<0.01). In the HCG injection group, the average imbed site number and IGF-1 mRNA expression were increased apparently as compared with those in the COH group (both P<0.01), better than those in the Gn group and the embryo culture group (all P<0.01). In the treatment with acupuncture combined with IVF-ET for infertility, the intervention of acupuncture on the day of HCG injection is the optimal time point. It increases the secretion of endometrial IGF-1 so as to improve the clinical pregnancy rate, the mean imbed site number and the embryo implantation.

Refractory hypoglycemia in a patient with functional adrenal cortical carcinoma.

SummaryAdrenacarcinomas are rare, and hypoglycemic syndrome resulting from the secretion of insulin-like growth factor II (IGF-II) by these tumors have been described infrequently. This study describes the case of a young woman with severe persistent hypoglycemia and a large adrenal tumor and discusses the physiopathological mechanisms involved in hypoglycemia. The case is described as a 21-year-old woman who presented with 8 months of general symptoms and, in the preceding 3 months, with episodes of mental confusion and visual blurring secondary to hypoglycemia. A functional assessment of the adrenal cortex revealed ACTH-independent hypercortisolism and hyperandrogenism. Hypoglycemia, hypoinsulinemia, low C-peptide and no ketones were also detected. An evaluation of the GH–IGF axis revealed GH blockade (0.03; reference: up to 4.4 ng/mL), greatly reduced IGF-I levels (9.0 ng/mL; reference: 180–780 ng/mL), slightly reduced IGF-II levels (197 ng/mL; reference: 267–616 ng/mL) and an elevated IGF-II/IGF-I ratio (21.9; reference: ~3). CT scan revealed a large expansive mass in the right adrenal gland and pulmonary and liver metastases. During hospitalization, the patient experienced frequent difficult-to-control hypoglycemia and hypokalemia episodes. Octreotide was ineffective in controlling hypoglycemia. Due to unresectability, chemotherapy was tried, but after 3 months, the patient’s condition worsened and progressed to death. In conclusion, our patient presented with a functional adrenal cortical carcinoma, with hyperandrogenism associated with hypoinsulinemic hypoglycemia and blockage of the GH–IGF-I axis. Patient’s data suggested a diagnosis of hypoglycemia induced by an IGF-II or a large IGF-II-producing tumor (low levels of GH, greatly decreased IGF-I, slightly decreased IGF-II and an elevated IGF-II/IGF-I ratio).Learning points:Hypoglycemyndrome resulting from the secretion of insulin-like growth factor II (IGF-II) by adrenal tumors is a rare condition.Hypoinsulinemic hypoglycemia associated with hyperandrogenism and blockage of the GH–IGF-I axis suggests hypoglycemia induced by an IGF-II or a large IGF-II-producing tumor.Hypoglycemia in cases of NICTH should be treated with glucocorticoids, glucagon, somatostatin analogs and hGH.

Disruption of the AMPK-TBC1D1 nexus increases lipogenic gene expression and causes obesity in mice via promoting IGF1 secretion.

Tre-2/USP6, BUB2, cdc16 domain family member 1 (the TBC domain is the GTPase activating protein domain) (TBC1D1) is a Rab GTPase activating protein that is phosphorylated on Ser(231) by the AMP-activated protein kinase (AMPK) in response to intracellular energy stress. However, the in vivo role and importance of this phosphorylation event remains unknown. To address this question, we generated a mouse model harboring a TBC1D1(Ser231Ala) knockin (KI) mutation and found that the KI mice developed obesity on a normal chow diet. Mechanistically, TBC1D1 is located on insulin-like growth factor 1 (IGF1) storage vesicles, and the KI mutation increases endocrinal and paracrinal/autocrinal IGF1 secretion in an Rab8a-dependent manner. Hypersecretion of IGF1 causes increased expression of lipogenic genes via activating the protein kinase B (PKB; also known as Akt)-mammalian target of rapamycin (mTOR) pathway in adipose tissues, which contributes to the development of obesity, diabetes, and hepatic steatosis as the KI mice age. Collectively, these findings demonstrate that the AMPK-TBC1D1 signaling nexus interacts with the PKB-mTOR pathway via IGF1 secretion, which consequently controls expression of lipogenic genes in the adipose tissue. These findings also have implications for drug discovery to combat obesity.

Melatonin Mediates Monochromatic Light-induced Insulin-like Growth Factor 1 Secretion of Chick Liver: Involvement of Membrane Receptors.

Monochromatic lights influenced the proliferation and differentiation of skeletal satellite cells in broilers by the enhancement of insulin-like growth factor 1 (IGF-1) secretion. However, whether melatonin (MEL)-mediated monochromatic lights influenced the IGF-1 secretion remains unclear. Newly hatched broilers, including intact, sham operation and pinealectomy groups, were exposed to blue (BL), green (GL), red (RL) and white light (WL) from a light-emitting diode system for 14 days. The results showed that GL effectively promoted the secretion of MEL and IGF-1, the expression of proliferating cell nuclear antigen and MEL receptor subtypes Mel1a, Mel1b and Mel1c in the liver compared to BL and RL in vivo. Moreover, those was a positive correlation between MEL and IGF-1 (r = 0.834). After pinealectomy, however, these parameters declined, and there were no differences between GL and other monochromatic light treatments. In vitro, exogenous MEL increased hepatocyte proliferation and IGF-1 secretion. Meanwhile, the MEL enhancements were suppressed by prazosin (selective Mel1c antagonist), followed by luzindole (nonselective Mel1a/Mel1b antagonist), but not suppressed by 4-phenyl-2-propionamideotetralin (selective Mel1b antagonist). These findings demonstrated that MEL mediated the monochromatic light-induced secretion of IGF-1 in chicks' livers by Mel1c and that Mel1a may be involved in this process.