IGF-1 Receptor mRNA Expression Research Articles

Estrogen Receptor Is Required for Metformin-Induced Apoptosis in Breast Cancer Cells Under Hyperglycemic Conditions.

About 25% to 30% of estrogen receptor (ER)-positive breast cancer patients develop resistance to endocrine therapy. Human epidermal growth factor receptor 2 (HER2) has been shown to cooperate with several growth factors that regulate cellular energy metabolism, including the insulin-like growth factor 1 receptor (IGF-1R). As the first-line therapy for type 2 diabetes mellitus (T2DM) patients, metformin is widely known to inhibit the metabolic reprogramming of cancer cells. This study aims to investigate metformin's efficacy in inhibiting endocrine resistance related to genes regulating energy metabolism in both ER-positive and ER-negative breast cancer cell lines under hyperglycemic conditions. MDA-MB-361 (ER-positive, HER2-positive) and SKBR3 (ER-negative, HER2-positive) cancer cell lines were used to represent ER status. Cell viability and cell survival rate were measured using the colorimetric assay of Cell Counting Kit-8. All mRNA levels were quantified using real-time quantitative polymerase chain reaction preceded by reverse transcription. A P value of <.05 was considered statistically significant. Unlike MDA-MB-361, SKBR3 were found to acquire resistance upon metformin treatment in hyperglycemic conditions. Moreover, the mRNA expression of IGF-1R and its downstream signaling, such as the mammalian target of rapamycin (mTOR), was not affected by metformin. Meanwhile, the mRNA expression level of ribosomal S6 kinase 1 (S6K1) was upregulated, whereas forkhead box O1 (FOXO1) was downregulated after metformin treatment in hyperglycemic conditions. This preliminary study suggests that an alternative pathway of metformin resistance may exist in the absence of ERα. Therefore, relying solely on metformin may be inadequate to inhibit the aggressiveness of breast cancer cells.

Initiation of muscle protein synthesis was unrelated to simultaneously upregulated local production of IGF-1 by amino acids in non-proliferating L6 muscle cells.

BackgroundIGF-1 is considered an important regulator of muscle protein synthesis. However, its role in stimulation of muscle protein synthesis by amino acids (AA) is not clear, despite pronounced alterations in IGF-1 mRNA expression and signaling in muscle tissues by feeding. This study evaluates the role of locally produced IGF-1 and IGF-1 signaling when skeletal muscle protein synthesis is activated by increased amino acid availability in confluent, non-proliferating cells.MethodsL6 skeletal muscle cells were subjected to amino acid starvation (24 h, 0.14 mM) followed by 18 h amino acid refeeding in Low AA (0.28 mM) or High AA concentrations (9 mM). Protein synthesis rates were estimated by L-[U-14C]-phenylalanine incorporation into cellular proteins. IGF-1 and IGF-1 receptor mRNA expression were quantified by real time PCR. SiRNA knockdown, antibodies and chemical inhibitors were used to attenuate muscle IGF-1 production and signaling.ResultsHigh AA concentrations (9mM) increased IGF-1 mRNA expression (+ 30%, p<0.05) and increased L-[U-14C]-phenylalanine incorporation compared to Low AA in confluent, non-proliferating muscle cells. Blocking IGF-1 signaling by chemical inhibitors reduced IGF-1 mRNA upregulation (~50%, p< 0.01), without decrease of protein synthesis. SiRNA knockdown of IGF-1 reduced protein synthesis, mainly explained by reduced cell proliferation. High AA or IGF-1 inhibitors did not change IGF-1 receptor mRNA expressions.ConclusionAmino acids increased IGF-1 mRNA expression and stimulated muscle protein synthesis. However, simultaneous upregulation of IGF-1 mRNA did not relate to increased protein synthesis by amino acids. The results indicate that increased IGF-1 mRNA expression is rather a covariate to amino acid initiation of protein synthesis in non-proliferating muscle cells; effects that may be related to unrecognized metabolic activities, such as transport of amino acids.

+3179G/A Insulin-Like Growth Factor-1 Receptor Polymorphism: A Novel Susceptibility Contributor in Anti-Ro/SSA Positive Patients with Sjögren's Syndrome: Potential Clinical and Pathogenetic Implications.

Background: Alterations of the insulin-like growth factor (IGF) pathway along with genetic variations of the IGF1 receptor (IGF1R) gene have been linked to the development of systemic autoimmunity, possibly through apoptosis induction. This study aims to investigate whether genetic variations of the IGF1R contribute to Sjögren’s syndrome (SS) pathogenesis and explores potential functional implications. Methods: DNA extracted from whole peripheral blood derived from 277 primary SS patients, complicated or not by lymphoma, and 337 Healthy controls (HC) was genotyped for the rs2229765 IGF1R polymorphism using the RFLP-PCR assay. Gene expression of IGF1R and IGF1 isoforms, caspases 1, 4, and 5, and inflammasome components NLRP3, ASC, IL1β, IL18, IL33, IGFBP3, and IGFBP6 were quantitated by RT-PCR in total RNA extracted from minor salivary gland biopsies (MSGs) of 50 SS patients and 13 sicca controls (SCs). In addition, IGF1R immunohistochemical (IHC) expression was assessed in formalin-fixed, paraffin-embedded MSG tissue sections derived from 10 SS patients and 5 SCs. Results: The prevalence of the A/A genotype of the rs2229765 IGF1R polymorphism was significantly higher in the anti-Ro/SSA positive SS population compared to healthy controls (24.8% vs. 10.7%, p = 0.001). Moreover, IGF1Rs at both mRNA and protein levels were reduced in SS-derived MSGs compared to SCs and were negatively associated with caspase 1 transcripts. The latter were positively correlated with NLRP3, ASC, and IL1β at the salivary gland tissue level. IGF1R expression in peripheral blood was negatively correlated with ESR and IgG serum levels and positively correlated with urine-specific gravity values. Conclusions: The rs2229765 IGF1R variant confers increased susceptibility for seropositive primary SS. Dampened IGF1R mRNA and protein expression in salivary gland tissues could be related to increased apoptosis and subsequently to the activation of inflammasome pathways.

The growth hormone and insulin-like growth factor 1 axis in cattle during the peri-ovulatory period activates the synthesis and release of oviductal contraction related substances.

Growth hormone (GH) and insulin-like growth factor 1 (IGF1) are crucial for female reproductive functions. The cyclic regulation of the local GH/IGF1 axis in the oviduct and its involvement in oviductal contraction in cattle has not been investigated. Thus, the messenger RNA (mRNA) expression for GH receptor (GHR), IGF1, IGF1 receptor (IGF1R) in the whole oviducts, as well as in cultured bovine oviductal epithelial cells (BOECs) were evaluated. The GHR, IGF1, and IGF1R mRNA expression was significantly higher during postovulatory phase. The luteinizing hormone (LH), estradiol-17β (E2), and LH + E2 treatments significantly increased GHR and IGF1 mRNA expression in cultured BOECs. Further, GH and combination of GH with LH and E2 upregulated IGF1 mRNA expression in the BOECs. Moreover, IGF1 + LH and combined IGF1 + LH + E2 treatments significantly increased prostaglandin synthesis cascade enzyme mRNA expression in the BOECs. An ex vivo microdialysis assay revealed that GH and IGF1 induced the release of oviductal contraction related prostaglandins, endothelin-1, and angiotensin II in follicular and postovulatory phases. Together, the findings strongly suggest that the presence of the active GH/IGF1 axis during the peri-ovulatory period, regulating the local system for the release of oviductal contraction related substances, which may provide the optimal oviductal environment for gametes and early embryo.

Reduced Insulin-Like Growth Factor Family Member Expression Predicts Neurogenesis Marker Expression in the Subependymal Zone in Schizophrenia and Bipolar Disorder.

The generation of inhibitory interneurons from neural stem cells in the subependymal zone is regulated by trophic factors. Reduced levels of trophic factors are associated with inhibitory interneuron dysfunction in the prefrontal cortex and hippocampus in psychiatric disorders, yet the extent to which altered trophic support may underpin deficits in inhibitory interneuron generation in the neurogenic niche remains unexplored in schizophrenia and bipolar disorder. We determined whether the expression of ligands, bioavailability-regulating binding proteins, and cognate receptors of 4 major trophic factor families (insulin-like growth factor [IGF], epidermal growth factor [EGF], fibroblast growth factor [FGF], and brain-derived neurotrophic factor [BDNF]) are changed in schizophrenia and bipolar disorder compared to controls. We used robust linear regression analyses to determine whether altered expression of trophic factor family members predicts neurogenesis marker expression across diagnostic groups. We found that IGF1 mRNA was decreased in schizophrenia and bipolar disorder compared with controls (P ≤ .006), whereas both IGF1 receptor (IGF1R) and IGF binding protein 2 (IGFBP2) mRNAs were reduced in schizophrenia compared with controls (P ≤ .02). EGF, FGF, and BDNF family member expression were all unchanged in both psychiatric disorders compared with controls. IGF1 expression positively predicted neuronal progenitor and immature neuron marker mRNAs (P ≤ .01). IGFBP2 expression positively predicted neural stem cell and neuronal progenitor marker mRNAs (P ≤ .001). These findings provide the first molecular evidence of decreased IGF1, IGF1R, and IGFBP2 mRNA expression in the subependymal zone in psychiatric disorders, which may potentially impact neurogenesis in schizophrenia and bipolar disorder.

High IGF1R protein expression correlates with disease-free survival of patients with stage III colon cancer

The aim of this study was to investigate the association between expression of insulin-like growth factor-1 receptor (IGF1R) and its ligand, IGF-II, and disease-free survival (DFS) in patients with stage III colon cancer (CC). In this retrospective study we included consecutive patients who underwent curative surgery for stage III CC. IGF1R and IGF-II/IGF2 status were evaluated in tumour samples by immunohistochemistry and quantitative real-time PCR (qRT-PCR). Associations of markers with DFS were analysed using Cox proportional hazards models. Hundred and fifty-one CC patients were included (median age, 66.6years; female, 54.3%). Low levels of IGF1R and IGF-II protein expression were observed in 16.1% and 10.7% of the cases, respectively. No significant differences in clinicopathological characteristics between patients with tumours expressing low IGF1R or IGF-II protein levels and those with high levels were observed. A low IGF1R protein expression was found to be significantly associated with a shorter DFS (HR 3.32; 95% CI, 1.7-6.31; p= 0.0003), while no association was observed between IGF-II protein expression and DFS (HR 0.91; 95% CI, 0.28-2.96; p= 0.87). In a multivariate analysis, IGF1R protein status remained an independent prognostic factor for DFS (HR 2.73; 95% CI, 1.40-5.31; p= 0.003). Furthermore, we found that neither IGF1R nor IGF2 mRNA expression levels as measured by qRT-PCR correlated with the respective protein expression levels as assessed by immunohistochemistry. Neither of the mRNA expression levels was significantly associated with DFS. From our data we conclude that low IGF1R protein expression represents a poor prognostic biomarker in stage III colon cancer.

IGF-1R/β-catenin signaling axis is involved in type 2 diabetic osteoporosis.

Insulin-like growth factor-1 receptor (IGF-1R) is involved in both glucose and bone metabolism. IGF-1R signaling regulates the canonical Wnt/β-catenin signaling pathway. In this study, we investigated whether the IGF-1R/ β-catenin signaling axis plays a role in the pathogenesis of diabetic osteoporosis (DOP). Serum from patients with or without DOP was collected to measure the IGF-1R level using enzyme-linked immunosorbent assay (ELISA). Rats were given streptozotocin following a four-week high-fat diet induction (DOP group), or received vehicle after the same period of a normal diet (control group). Dual energy X-ray absorption, a biomechanics test, and hematoxylin-eosin (HE) staining were performed to evaluate bone mass, bone strength, and histomorphology, respectively, in vertebrae. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to measure the total and phosphorylation levels of IGF-1R, glycogen synthase kinase-3β (GSK-3β), and β-catenin. The serum IGF-1R level was much higher in patients with DOP than in controls. DOP rats exhibited strikingly reduced bone mass and attenuated compression strength of the vertebrae compared with the control group. HE staining showed that the histomorphology of DOP vertebrae was seriously impaired, which manifested as decreased and thinned trabeculae and increased lipid droplets within trabeculae. PCR analysis demonstrated that IGF-1R mRNA expression was significantly up-regulated, and western blotting detection showed that phosphorylation levels of IGF-1R, GSK-3β, and β-catenin were enhanced in DOP rat vertebrae. Our results suggest that the IGF-1R/β-catenin signaling axis plays a role in the pathogenesis of DOP. This may contribute to development of the underlying therapeutic target for DOP.

Pathogenetic implications of early growth response 1 in Ewing sarcoma

Ewing sarcoma (ES) is the second most common primary malignant bone tumour, mainly occurs in children and adolescents, and has an overwhelming mortality. Despite extensive studies, few effective oncogenic signals have been described. Therefore, it is crucial to exploit novel pathognomonic factors and targetable biomarkers for ES patients. Based on previous studies, we speculate that insulin-like growth factor 1 receptor (IGF1R), which is upregulated by early growth response 1 (EGR1), may play a pivotal role in strengthening the downward transmission of IGF1 cascades. Therefore, in this study, we concentrated on determining the pathogenetic contribution of EGR1 in diverse ES cells. This report is the first to study the pathogenic role of EGR1 in ES. ES cells were cultured and transfected with Stealth RNAi human EGR1 small interfering RNA (siRNA) or negative control. Cell proliferation and invasion potential were measured. mRNA and protein expression of EGR1, IGF1R, and EWS-FLI1 also were assessed. In all EGR1 siRNA-transfected cells (SK-ES-1, RD-ES, and HS863.T), cell proliferation and invasive potential decreased significantly in EGR1 siRNA-transfected ES cells. mRNA and protein expression for EGR1, IGF1R, and EWS-FLI1 were also significantly reduced. In conclusion, EGR1 upregulated IGF1R expression and enhanced the expression of the oncogenic fusion protein EWS-FLI1. The EWS-FLI1/EGR1/IGF1R cascade combined with the previously confirmed pathways can form a speculative circuit, implicating positive feedback for tumourigenesis in ES. Therefore, EGR1 inhibitors are expected to be useful for the treatment of ES by preventing oncogenic IGF1/IGF1R expression.

Variable IGF1R mRNA Expression in Individual GV and In Vitro Matured M2 Human Oocytes

Objective Characterization of human insulin-like growth factor 1 receptor (IGF1R) mRNA expression in individual human oocytes to better understand the role of biologically significant mRNAs in establishing oocyte quality following ovarian hyperstimulation for in vitro fertilization (IVF) treatment. Design Germinal vesicle oocytes (GV) were identified after removal of all cumulus cells prior to ICSI and collected from consenting patients with IRB-approval. Materials and Methods Single GVs were placed directly into lysis buffer (5μl). Oocytes in vitro matured (IVM) to the M2 stage were placed into individual tubes containing lysis buffer after 24 to 48 hours (h) in culture. Total RNA isolated from cumulus granulosa cells (GC) using the TRIzol reagent (Invitrogen) as stated in the manufacturer’s protocol served as a positive control. Reverse Transcription (RT) was performed using anchored oligo-dT primers (IDT, Coralville, IA) and Moloney Murine Leukemia Virus reverse transcriptase (Invitrogen) on the entire 5μl oocyte lysate at 37°C for 1.5h or 1mg total GC RNA 42°C for 1h. Quantitative polymerase chain reaction (qPCR) was performed combining standards or 1μl cDNA with PCR buffer containing SYBR Green I (Sigma Chemical Co, St. Louis, Missouri), Taq polymerase (Genscript, Piscataway, NJ), and primers for IGF1R. Melting curves were routinely determined to ascertain generation of only the expected product. Results qPCR performed on GC cDNA demonstrated detection of the expected product under the reaction conditions in use. Gel electrophoresis of the PCR product confirmed the size of the DNA fragment generated. qPCR analysis detected a signal for IGF1R mRNA in 9 of the 15 GVs analyzed from 9 patients. Moreover, for 3 patients with multiple GVs, differences in IGF1R rnRNA expression were seen between individual GV oocytes, as well as between oocytes from different patients. Similarly, 8 of 12 IVM M2 oocytes from 11 patients gave a signal for the presence of IGF1R mRNA. Conclusions These results report the use of a direct-lysis method for the extraction and analysis of mRNA from single human oocytes. These data suggest that GV oocytes failing to respond to the hCG trigger during ovarian stimulation for IVF vary in their biological integrity. Furthermore, we observed that GV oocytes advanced to the M2 stage in vitro in the absence of any demonstrable IGF1R mRNA expression. Molecular assessment of single human oocytes can be used to better understand the low per-oocyte success rate in human IVF. Disclosures Nothing to disclose. Funding None.

Identifying Involvement of H19-miR-675-3p-IGF1R and H19-miR-200a-PDCD4 in Treating Pulmonary Hypertension with Melatonin

Non-coding RNAs play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). The aim of this study was to characterize the therapeutic role of melatonin as well as the underlying molecular mechanism (its effects on the expression of H19 and its downstream signaling pathways) in the treatment of PAH. Real-time PCR and western blot analysis were performed to evaluate the expression of H19, miR-200a, miR-675, insulin-like growth factor-1 receptor (IGF1R), and programmed cell death 4 (PDCD4). The value of systolic pulmonary artery pressure (SPAP) and the ratio of medial thickening in the monocrotaline (MCT) group were increased, whereas the melatonin treatment could decrease these values to some extent. The weights of RV (right ventricle), LV (left ventricle) + IVS (interventricular septal), and RV/(LV + IVS) in the MCT group were much higher than those in the MCT + melatonin and control groups. In addition, the expression of H19, miR-675, IGF1R mRNA, and IGF1R protein in the MCT group was the highest, whereas their expression in the control group was the lowest. The expression of miR-200, PDCD4 mRNA, and PDCD4 protein in the MCT group was the lowest, whereas their expression in the control group was the highest. Furthermore, H19 directly suppressed the expression of miR-200a, whereas miR-675-3p and miR-200a directly inhibited the expression of IGF1R and PDCD4, respectively. Finally, melatonin treatment inhibited cell proliferation; upregulated the expression of H19, miR-675-3p, and PDCD4; and downregulated the expression of miR-200a and IGF1R. This study demonstrated the role of H19-miR-675-3p-IGF1R- and H19-miR-200a-PDCD4-signaling pathways in the melatonin treatment of PAH.

High nutrient intake during the early postnatal period accelerates skeletal muscle fiber growth and maturity in intrauterine growth-restricted pigs

BackgroundIntrauterine growth-restricted (IUGR) neonates impair postnatal skeletal muscle growth. The aim of this study was to investigate whether high nutrient intake (HNI) during the suckling period could improve muscle growth and metabolic status of IUGR pigs.MethodsTwelve pairs of IUGR and normal birth weight (NBW) pigs (7 days old) were randomly assigned to adequate nutrient intake and HNI formula milk groups. Psoas major (PM) muscle sample was obtained after 21 days of rearing.ResultsIUGR decreased cross-sectional areas (CSA) and myofiber numbers, activity of lactate dehydrogenase (LDH), and mRNA expression of insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), mammalian target of rapamycin (mTOR), ribosomal protein s6 (RPS6), eukaryotic translation initiation factor 4E (eIF4E), protein expression of phosphorylated mTOR (P-mTOR), and phosphorylated protein kinase B (P-Akt) in the PM muscle of pigs. Irrespective of birth weight, HNI increased muscle weight and CSA, the concentration of RNA, and ratio of RNA to DNA, as well as ratio of LDH to β-hydroxy-acyl-CoA-dehydrogenase in the PM muscle of pigs. Furthermore, HNI increased percentages of MyHC IIb, mRNA expression of IGF-1, IGF-1R, Akt, mTOR, RPS6, and eIF4E, as well as protein expression of P-mTOR, P-Akt, P-RPS6, and P-eIF4E in the PM muscle of pigs.ConclusionThe present findings suggest that high nutrient intake during the suckling period could improve skeletal muscle growth and maturity, which is associated with increasing the expression of protein deposition-related genes and accelerating the development of glycolytic-type myofiber in pigs.

Up-regulation of microRNA-503 by high glucose reduces the migration and proliferation but promotes the apoptosis of human umbilical vein endothelial cells by inhibiting the expression of insulin-like growth factor-1 receptor.

The present study is aimed to investigate the regulatory effect of microRNA (miRNA or miR)-503 on endothelial functions, as well as the mechanism by which high glucose leads to injury of endothelial cells. When reaching 80% confluency, human umbilical vein endothelial cells (HUVECs) were subjected to non-serum synchronization for 12 h, and medium of cells in high-glucose (HG) group was replaced by normal medium supplemented with 25 mmol/L D-glucose. HUVECs cultured in normal glucose (NG) medium were used as control. To overexpress miR-503, HUVECs were transfected with miR-503 mimics. To silence insulin-like growth factor-1 receptor (IGF-1R) mRNA, HUVECs were transfected with small interfering RNA (siRNA). To predict whether miR-503 targets IGF-1R, bioinformatics was performed. Quantitative Real-time polymerase chain reaction was used to determine miR-503 and IGF-1R mRNA expression, and Western blotting was employed to measure IGF-1R protein expression. Cell-Counting Kit 8 assay was used to determine HUVECs proliferation, while wound-healing assay was used to evaluate HUVECs migration. HUVECs apoptosis was investigated by measuring caspase 3 activity. Expression of IGF-1R in HUVECs in high glucose was decreased compared to that in normal glucose. miR-503 was predicted to target IGF-1R mRNA, and miR-503 expression in HUVECs in high glucose was higher than that in normal glucose. Overexpression of miR-503 inhibited the transcription and the translation of IGF-1R gene reducing migration, suppressed proliferation and promoted apoptosis. Transfection with IGF-1R siRNA decreased IGF-1R protein expression in HUVECs. Down-regulated IGF-1R expression reduced migration and proliferation, but promoted apoptosis of HUVECs. The present study demonstrates that miR-503 expression in HUVECs is elevated in high glucose condition. Also, miR-503 reduces migration and proliferation, but promotes apoptosis of HUVECs by inhibiting IGF-1R expression.

Effects of electroacupuncture at "Zhongliao" (BL 33) and "Tianshu" (ST 25) on ovarian function in rats with premature ovarian insufficiency

To explore the effects of electroacupuncture (EA) at "Zhongliao" (BL 33) and "Tianshu" (ST 25) on ovarian function in rats with premature ovarian insufficiency (POI). A total of 48 SD female rats with regular estrus were divided into a blank group (n=8), a model group (n=10), an EA group (n=10), a binding group (n=10) and a tamoxifen (TAM) group (n=10). The rats in the model group, EA group, binding group and TAM group were all treated with intraperitoneal injection of 4-vinylcyclohexene diepoxide (VCD, 160 mg/kg) for 15 consecutive days to establish the model of POI; the rats in the blank group were treated with normal diet. After the model was established successfully, the rats in the EA group were treated with EA at "Zhongliao" (BL 33) and "Tianshu" (ST 25) with continuous wave (1 to 3 Hz, 0.1 to 1 mA) for 20 minutes, once a day (five times a week) for the first two weeks and once every other day (three times a week) for the following two weeks. The rats in the TAM group were treated with subcutaneous injection of tamoxifen (1mg/kg), once a day (five times a week) for the first two weeks and once every other day (three times a week) for the following two weeks. The rats in the binding group were bound by a small sack as the EA group. The rats in the blank group and the model group were treated with normal diet. After four weeks, the sexual gland weight and index were tested in each group; the ELISA method was applied to test the level of anti-mllerian hormone (AMH) and inhibin B; the morphology of ovary was observed; the number of primordial follicles, primary follicle, antral follicle and atretic follicle was counted; the expression of insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-1 receptor (IGF-1R) were measured. (1) Compared with the blank group, the ovary weight, ovary index, uterus weight and uterus index were significantly decreased after treatment in the model group, EA group, binding group and TAM group (all P<0.01); but the differences between the model group and the EA group, binding group, TAM group were not significant (all P>0.05). (2) Compared with the blank group, the levels of serum AMH, inhibin B and E2 were significantly reduced; the levels of FSH and LH were significantly increased in the model group; EA group, binding group and TAM group (all P<0.01). Compared with the model group, the levels of serum AMH, inhibin B and E2 were significantly increased, the level of FSH and LH were significantly reduced in the EA group and TAM group (all P<0.01). (3) Compared with the blank group, in the model group, EA group, binding group and TAM group the ovary was dark red and pale, surrounded by particle or not; the morphology was small and atrophic; the primordial follicles was reduced even vanished; the structure of primary follicle was damaged and loosely arranged; the mature follicle was few; the atretic follicle and interstitial gland were increased. (4) Compared with the blank group, the expressions of IGF-1 mRNA and IGF-1R mRNA were increased in the model group (all P<0.01); compared with the blank group, the expression of IGF-1 mRNA was increased in the binding group (P<0.05), but that of IGF-1R mRNA was not significantly different (P>0.05); compared with the model group, the expression of IGF-1 mRNA was not significantly different in the EA group, binding group and TAM group (all P>0.05), but that of IGF-1R mRNA was reduced (P<0.05, P<0.01). EA at "Zhongliao" (BL 33) and "Tianshu" (ST 25) has improvement effect on ovarian function in rats with VCD-induced POI, which is likely to be related to regulating the IGF-1R mRNA expression to improve the IGF-1/ IGF-1R axis.

Association of body weight gain with muscle, fat, and liver expression levels of growth hormone receptor, insulin-like growth factor I, and beta-adrenergic receptor mRNAs in steers

The physiological basis of feed efficiency is unclear. Administration of GH or beta-adrenergic agonists improves feed efficiency in various animals. The objective of this study was to test the hypothesis that more efficient cattle have greater expression of GH receptor (GHR) or beta-adrenergic receptor (ADRB) mRNA in skeletal muscle, fat, and liver, the major target tissues of GH and beta-adrenergic agonists. Fifty Angus steers were fed a finishing diet for 75 d to determine residual feed intake (RFI). Carcass measures, skeletal muscle, subcutaneous fat, and liver samples were collected from the top 10 high-RFI steers and top 10 low-RFI steers at slaughter. Abundances of GHR, insulin-like growth factor I (IGF1), IGF1 receptor (IGF1R), beta-1 adrenergic receptor (ADRB1), ADRB2, and ADRB3 mRNAs were quantified by real-time reverse transcription-PCR. Low-RFI steers consumed 11% less dry matter intake than high-RFI steers (P = 0.004). Low- and high-RFI steers, however, did not differ in ADG or other growth or carcass measures. Low-RFI steers had a tendency to have smaller birth weights than high-RFI steers (P = 0.089). The expression levels of GHR, IGF1, IGF1R, ADRB1, ADRB2, and ADRB3 mRNAs in muscle, fat, and liver were neither different (P > 0.1) between high- and low-RFI steers nor correlated (P > 0.1) with RFI. These results do not support our original hypothesis. However, the expression levels of GHR, IGF1, and IGF1R mRNAs in muscle and fat were positively correlated with ADG (r = 0.52 to 0.65, P = 0.002 to 0.02), whereas the expression levels of GHR mRNA (r = −0.50, P = 0.03) and IGF1 mRNA (r = −0.47, P = 0.04) in the liver were negatively correlated with ADG. These results suggest that the GHR, IGF1, and IGF1R mRNA expression levels in the muscle and fat have a positive effect, whereas the GHR and IGF1 mRNA expression levels in the liver have a negative effect on postweaning body weight gain in cattle.

Chromosome 15 structural abnormalities: effect on IGF1R gene expression and function.

Insulin-like growth factor 1 receptor (IGF1R), mapping on the 15q26.3 chromosome, is required for normal embryonic and postnatal growth. The aim of the present study was to evaluate the IGF1R gene expression and function in three unrelated patients with chromosome 15 structural abnormalities. We report two male patients with the smallest 15q26.3 chromosome duplication described so far, and a female patient with ring chromosome 15 syndrome. Patient one, with a 568 kb pure duplication, had overgrowth, developmental delay, mental and psychomotor retardation, obesity, cryptorchidism, borderline low testis volume, severe oligoasthenoteratozoospermia and gynecomastia. We found a 1.8-fold increase in the IGF1R mRNA and a 1.3-fold increase in the IGF1R protein expression (P < 0.05). Patient two, with a 650 kb impure duplication, showed overgrowth, developmental delay, mild mental retardation, precocious puberty, low testicular volume and severe oligoasthenoteratozoospermia. The IGF1R mRNA and protein expression was similar to that of the control. Patient three, with a 46,XX r(15) (p10q26.2) karyotype, displayed intrauterine growth retardation, developmental delay, mental and psychomotor retardation. We found a <0.5-fold decrease in the IGF1R mRNA expression and an undetectable IGF1R activity. After reviewing the previously 96 published cases of chromosome 15q duplication, we found that neurological disorders, congenital cardiac defects, typical facial traits and gonadal abnormalities are the prominent features in patients with chromosome 15q duplication. Interestingly, patients with 15q deletion syndrome display similar features. We speculate that both the increased and decreased IGF1R gene expression may play a role in the etiology of neurological and gonadal disorders.

MicroRNA-30a-5p inhibits the proliferation and invasion of gastric cancer cells by targeting insulin-like growth factor 1 receptor.

MicroRNAs (miRs) are a class of small non-coding RNAs of 18–25 nucleotides in length that serve as key regulators in the development and progression of human cancers. Recently, miR-30b-5p, as a member of the miR-30 family, has been reported to act as a tumor suppressor in gastric cancer. However, the expression and function of miR-30a-5p in gastric cancer, as well as the corresponding underlying mechanism, remain unknown. In the present study, it was demonstrated that the expression of miR-30a-5p was significantly reduced in gastric cancer tissues (n=43) compared with normal gastric tissues (n=10; P<0.01). Similarly, miR-30a-5p was significantly downregulated in the gastric cancer cell lines AGS, HGC27, BGC823 and SGC7901, when compared with the normal gastric mucosa epithelial cell line GES-1 (P<0.01). In addition, overexpression of miR-30a-5p significantly inhibited the proliferation and invasion of AGS cells (P<0.01). Insulin-like growth factor 1 receptor (IGF-1R) was identified as a novel target of miR-30a-5p, and the protein expression of IGF-1R was negatively regulated by miR-30a-5p in AGS cells (P<0.01). Furthermore, overexpression of IGF-1R significantly reversed the inhibitory effect of miR-30a-5p on the proliferation and invasion of AGS cells (P<0.01), indicating that IGF-1R was involved in miR-30a-5p-mediated proliferation and invasion of AGS cells. It was also observed that the expression of IGF-1R mRNA was upregulated in gastric cancer tissues compared with normal gastric tissues (P<0.01), and its levels of expression were reversely correlated with that of miR-30a-5p in gastric cancer tissues (R2=0.3892; P<0.01). Collectively, these data suggest that miR-30a-5p inhibits the growth and metastasis of gastric cancer by directly targeting IGF-1R. Therefore, the miR-30a-5p/IGF-1R axis may be a potential therapeutic target in the treatment of gastric cancer.

Clinicopathological significance and impact on outcomes of the gene expression levels of IGF-1, IGF-2 and IGF-1R, IGFBP-3 in patients with colorectal cancer: Overexpression of the IGFBP-3 gene is an effective predictor of outcomes in patients with colorectal cancer.

The insulin-like growth factors (IGF) system is involved in tumor proliferation, invasion and metastasis in cancer. The current study investigated the association of IGF-1, IGF-2 and IGF-1 receptor (IGF-1R), IGF binding proteins type 3 (IGFBP-3) mRNA expression levels with clinicopathological characteristics and outcomes of 202 patients with untreated colorectal cancer (CRC). IGF-1, IGF-2, IGF-1R and IGFBP-3 mRNA expression levels were analyzed in surgical specimens of cancer tissues and adjacent normal mucosa cells using reverse transcription-quantitative polymerase chain reaction. The IGF-1R gene expression level was significantly higher in cancer tissue compared with adjacent normal mucosa. By contrast, IGF-1 gene expression levels were reduced in cancer tissue compared with normal mucosa. IGF-2 and IGFBP-3 gene expression levels did not differ significantly between cancer tissue and adjacent normal mucosa. As for the association of gene expression and clinicopathological characteristics, IGFBP-3 gene expression was significantly associated with lymph node metastasis. High IGFBP-3 gene expression was associated with poor 5-year overall survival compared with patients with low IGFBP-3 expression. Furthermore, IGFBP-3 gene expression was identified as an independent prognostic factor using multivariate analysis. Overexpression of the IGFBP-3 gene is considered an effective independent predictor of outcomes in patients with CRC.

MicroRNA-503 inhibits the proliferation and invasion of breast cancer cells via targeting insulin-like growth factor 1 receptor.

MicroRNAs (miRs), a class of non-coding RNAs that are 18–25 nucleotides in length, serve as key regulators in the development and progression of human cancers. Previously, miR-503 has been implicated in breast cancer. However, the underlying mechanism of miR-503 in regulating the proliferation and invasion of breast cancer cells remains largely unknown. In the present study, reverse transcription-quantitative polymerase chain reaction analysis indicated that the expression of miR-503 was significantly reduced in breast cancer tissues compared with their matched adjacent normal tissues. Furthermore, miR-503 expression levels were markedly reduced in T2-T4 stage breast cancer, compared with T1 stage. Insulin-like growth factor 1 receptor (IGF-1R) was further identified as a novel target of miR-503. Overexpression of miR-503 significantly suppressed the protein expression levels of IGF-1R. Furthermore, it inhibited the proliferation and invasion of human breast cancer MCF-7 cells, as assessed by MTT and Transwell assays, respectively. However, restoration of IGF-1R expression markedly ameliorated the suppressive effects of miR-503 overexpression on MCF-7 cell proliferation and invasion, indicating that miR-503 inhibits breast cancer cell proliferation and invasion at least partially via directly targeting IGF-1R. Furthermore, the mRNA and protein expression levels of IGF-1R were demonstrated to be significantly increased in breast cancer tissues compared with their matched adjacent normal tissues. In addition, IGF-1R mRNA expression levels were reversely correlated with miR-503 expression levels in breast tumors, suggesting that the upregulation of IGF-1R may be due to downregulation of miR-503 in breast cancer. In conclusion, the present study expanded the understanding of the regulatory mechanism of miR-503 in breast cancer, and implicates the miR-503/IGF-1R axis as a potential therapeutic target for breast cancer.

Equine insulin receptor and insulin‐like growth factor‐1 receptor expression in digital lamellar tissue and insulin target tissues

Hyperinsulinaemia is implicated in the pathogenesis of endocrinopathic laminitis. Insulin can bind to different receptors: two insulin receptor isoforms (InsR-A and InsR-B), insulin-like growth factor-1 receptor (IGF-1R) and InsR/IGF-1R hybrid receptor (Hybrid). Currently, mRNA expression of these receptors in equine tissues and the influence of body type and dietary carbohydrate intake on expression of these receptors is not known. The study objectives were to characterise InsR-A, InsR-B, IGF-1R and Hybrid expression in lamellar tissue (LT) and insulin responsive tissues from horses and examine the effect of dietary nonstructural carbohydrate (NSC) on mRNA expression of these receptors in LT, skeletal muscle, liver and two adipose tissue (AT) depots of lean and obese ponies. In vivo experiment. Lamellar tissue samples were evaluated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) for receptor mRNA expression (n=8) and immunoblotting for protein expression (n=3). Archived LT, skeletal muscle, liver and AT from lean and obese mixed-breed ponies fed either a low (~7% NSC as dry matter; 5 lean, 5 obese) or high NSC diet (~42% NSC as dry matter; 6 lean, 6 obese) for 7days were evaluated by RT-qPCR to determine the effect of body condition and diet on expression of the receptors in different tissues. Significance was set at P≤0.05. Lamellar tissue expresses both InsR isoforms, IGF-1R and Hybrid. LT IGF-1R gene expression was greater than either InsR isoform and InsR-A expression was greater than InsR-B (P≤0.05). Obesity significantly lowered IGF-1R, InsR-A and InsR-B mRNA expression in LT and InsR-A in tailhead AT. High NSC diet lowered expression of all three receptor types in liver; IGF-1R and InsR-A in LT and InsR-A in tailhead AT. Lamellar tissue expresses IGF-1R, InsR isoforms and Hybrids. The functional characteristics of these receptors and their role in endocrinopathic laminitis warrants further investigation.

Metformin inhibits the proliferation of human prostate cancer PC-3 cells via the downregulation of insulin-like growth factor 1 receptor

Metformin is a biguanide drug that is widely used for the treatment of type 2 diabetes. Recent studies have shown that metformin inhibits cancer cell proliferation and tumor growth both in vitro and in vivo. The anti-tumor mechanisms of metformin include activation of the AMP-activated protein kinase/mTOR pathway and direct inhibition of insulin/insulin-like growth factor (IGF)-mediated cellular proliferation. However, the anti-tumor mechanism in prostate cancer remains unclear. Because activation of the IGF-1 receptor (IGF-1R) is required for prostate cell proliferation, IGF-1R inhibitors may be of therapeutic value. Accordingly, we examined the effects of metformin on IGF-1R signaling in prostate cancer cells. Metformin significantly inhibited PC-3 cell proliferation, migration, and invasion. IGF-1R mRNA expression decreased significantly after 48 h of treatment, and IGF-1R protein expression decreased in a similar manner. IGF-1R knockdown by siRNA transfection led to inhibited proliferation, migration and invasion of PC-3 cells. IGF-1 activated both ERK1/2 and Akt, but these effects were attenuated by metformin treatment. In addition, intraperitoneal treatment with metformin significantly reduced tumor growth and IGF-1R mRNA expression in PC-3 xenografts. Our results suggest that metformin is a potent inhibitor of the IGF-1/IGF-1R system and may be beneficial in prostate cancer treatment.