IGF-I Receptor Research Articles

229-OR: Role of Insulin Signaling in the Regulation of Proteostasis in Astrocytes

Insulin is a principal metabolic hormone. It regulates a plethora of metabolic pathways in sensitive peripheral tissues. Recent studies show insulin signaling plays fundamental roles in the brain. Loss of insulin action in different neuronal and glial cells contributes to a variety of metabolic and behavioral abnormalities in mice. In particular, loss of astrocytic insulin signaling leads to impaired brain glucose sensing and increased depressive-like behavior in mice. How insulin signaling modulates astrocytic cellular functions and neural circuits is not completely known. Using next-generation RNA sequencing, we show that insulin triggers a robust transcriptional regulation on multiple metabolic pathways in primary astrocytes. As expected, insulin increased expression of genes involved in cholesterol biosynthesis, important for supporting synaptic integrity and remodeling. Further, autophagy is a quintessential pathway subjected to insulin regulation, indicating the role of insulin action on proteostasis in astrocytes. Thus, insulin suppresses the expression of most critical genes involved in autophagy, including p62, Ulk1/2, several Atg genes. The inhibitory effect is potent, as 1 nM is sufficient to suppress gene expression. To determine whether insulin receptors (IR) are required for such regulation, we examined the insulin response in astrocytes without endogenous IR. IR loss only partially reverses insulin-dependent suppression of autophagic genes, indicating that insulin may act through closely related IGF-1 receptors in astrocytes. In summary, insulin potently suppresses autophagy in astrocytes through transcriptional regulation, indicating a potential important role of astrocytic insulin signaling on regulating proteostasis in accordance with systemic nutritional status. Impairment of this regulation in insulin resistance and diabetes may affect the modulation of neural circuits by astrocytes and contribute to neurological complications linked to diabetes. Disclosure S.Geffken: None. C.Smith: None. H.Lee: None. W.Cai: None. Funding KDK120740

Cell proliferation effects of S-allyl-L-cysteine are associated with phosphorylation of janus kinase 2, insulin-like growth factor type-I receptor tyrosine kinase, and extracellular signal-regulated kinase 2 in primary cultures of adult rat hepatocytes

The cell proliferation effect of S-allyl-L-cysteine (SAC) and its mechanisms were examined in primary cultures of adult rat hepatocytes. In serum-free cultivation, SAC (10−6 M)-stimulated hepatocytes showed significant proliferation compared to control at 5-h culture; the effect was dependent on the culture time and the dose of SAC (EC50 value 8.58 × 10−8 M). In addition, SAC-stimulated hepatocytes significantly increased mRNA expression levels of c-Myc and c-Fos at 1 h and cyclin B1 at 3.5 and 4 h, respectively. In contrast, alliin and allicin, structural analogs of SAC, did not show these effects observed with SAC. The SAC-induced hepatocyte proliferation effects were completely suppressed by monoclonal antibodies against growth hormone receptor and insulin-like growth factor type-I (IGF-I) receptor, respectively. Furthermore, the Janus kinase 2 (JAK2) inhibitor TG101209, phospholipase C (PLC) inhibitor U-73122, IGF-I receptor tyrosine kinase (RTK) inhibitor AG538, PI3 kinase inhibitor LY294002, MEK inhibitor PD98059, and mTOR inhibitor rapamycin completely suppressed the SAC-induced hepatocyte proliferation. JAK2 (p125 kDa) phosphorylation in cultured hepatocytes peaked 5 min after SAC stimulation. SAC-induced IGF-I RTK (p95 kDa) and ERK2 (p42 kDa) phosphorylation had slower rises than JAK2, peaking at 20 and 30 min, respectively. These results indicate that SAC promoted cell proliferation by growth hormone receptor/JAK2/PLC pathway activation followed by activation of the IGF-I RTK/PI3K/ERK2/mTOR pathway in primary cultures of adult rat hepatocytes.

Insulin-like growth factor I sensitization rejuvenates sleep patterns in old mice.

Sleep disturbances are common during aging. Compared to young animals, old mice show altered sleep structure, with changes in both slow and fast electrocorticographic (ECoG) activity and fewer transitions between sleep and wake stages. Insulin-like growth factor I (IGF-I), which is involved in adaptive changes during aging, was previously shown to increase ECoG activity in young mice and monkeys. Furthermore, IGF-I shapes sleep architecture by modulating the activity of mouse orexin neurons in the lateral hypothalamus (LH). We now report that both ECoG activation and excitation of orexin neurons by systemic IGF-I are abrogated in old mice. Moreover, orthodromical responses of LH neurons are facilitated by either systemic or local IGF-I in young mice, but not in old ones. As orexin neurons of old mice show dysregulated IGF-I receptor (IGF-IR) expression, suggesting disturbed IGF-I sensitivity, we treated old mice with AIK3a305, a novel IGF-IR sensitizer, and observed restored responses to IGF-I and rejuvenation of sleep patterns. Thus, disturbed sleep structure in aging mice may be related to impaired IGF-I signaling onto orexin neurons, reflecting a broader loss of IGF-I activity in the aged mouse brain.

S-Allyl-L-cysteine Promotes Cell Proliferation by Stimulating Growth Hormone Receptor/Janus Kinase 2/Phospholipase C Pathways and Promoting Insulin-Like Growth Factor Type-I Secretion in Primary Cultures of Adult Rat Hepatocytes.

The mechanism of insulin-like growth factor type-I (IGF-I) secretion stimulated by S-allyl-L-cysteine (SAC) was investigated as part of a study of SAC-induced DNA synthesis and cell proliferation in primary cultures of adult rat hepatocytes. When 10-6 M SAC was added to the culture, the amount of IGF-I in the medium was significantly increased at 10 min. The peak IGF-I level (140 pg/mL) was observed 20 min after SAC stimulation. The SAC-induced IGF-I secretion was completely suppressed by a selective Janus kinase 2 (JAK2) inhibitor (TG101209), a selective phospholipase C (PLC) inhibitor (U-73122), an intracellular Ca2+ chelating agent (BAPTA-AM), and a granule secretion inhibitor (somatostatin). On the other hand, 10-6 M SAC-stimulated hepatocytes showed increased intracellular Ca2+ concentration in a time-dependent manner from 0 to 10 min. Phosphorylation of SAC-induced JAK2 and IGF-I receptor tyrosine kinase (RTK) was completely suppressed by TG101209. In addition, U-73122, BAPTA-AM, and somatostatin did not suppress SAC-induced JAK2 phosphorylation, but significantly suppressed SAC-induced IGF-I RTK phosphorylation. Furthermore, binding of the monoclonal antibody against growth hormone (GH) to GH receptor was dose-dependently suppressed by SAC on immunofluorescence. These results showed that SAC promotes cell proliferation by stimulating GH receptor/JAK2/phospholipase C pathways and promoting autocrine secretion of IGF-I in primary cultures of adult rat hepatocytes.

Encouraging specific biomarkers-based therapeutic strategies for hepatocellular carcinoma.

The prevention, early discovery and effective treatment of patients with hepatocellular carcinoma (HCC) remain a global medical challenge. At present, HCC is still mainly treated by surgery, supplemented by vascular embolization, radio frequency, radiotherapy, chemotherapy and biotherapy. The application of multikinase inhibitor sorafenib, chimeric antigen receptor T cells, or PD-1/PD-L1 inhibitors can prolong the median survival of HCC patients. However, the treatment efficacy is still unsatisfactory due to HCC metastasis and postoperative recurrence. During the process of hepatocyte malignant transformation, HCC tissues can express and secrete many types of specific biomarkers, or oncogenic antigen molecules into blood, for example, alpha-fetoprotein, glypican-3, Wnt3a (one of the key signaling molecules in the Wnt/β-catenin pathway), insulin-like growth factor (IGF)-II or IGF-I receptor, vascular endothelial growth factor, secretory clusterin and so on. In addition, combining immunotherapy with non-coding RNAs might improve anti-cancer efficacy. These biomarkers not only contribute to HCC diagnosis or prognosis, but may also become molecular targets for HCC therapy under developing or clinical trials. This article reviews the progress in emerging biomarkers in basic research or clinical trials for HCC immunotherapy.

Picropodophyllin inhibits the growth of pemetrexed-resistant malignant pleural mesothelioma via microtubule inhibition and IGF-1R-, caspase-independent pathways.

BackgroundAcquired pemetrexed resistance leads to treatment interruption in patients with malignant pleural mesothelioma (MPM). Insulin-like growth factor-I receptor (IGF-1R) inhibitor is a candidate for treating pemetrexed-naïve MPM. However, the efficacy of cytotoxic and targeted drugs in acquired-pemetrexed resistant MPM is unclear. We explored anticancer drugs, including the IGF-1R inhibitor picropodophyllin, against acquired pemetrexed-resistant MPMs.MethodsAcquired pemetrexed-resistant human MPM cell lines, named as H2452/PEM and 211H/PEM after their parental lines H2452 and 211H, respectively, were established by exposure to pemetrexed in vitro. Picropodophyllin and siRNA for IGF-1R knockdown were used to evaluate the efficacy of IGF-1R inhibition. Immunofluorescence was used to evaluate microtubule localization. The efficacy of picropodophyllin was evaluated in 3-dimensional MPM models.ResultsThe acquired pemetrexed-resistant MPM lines retained their resistance after the removal of culture treatment. IGF-1R levels in H2452/PEM cells were higher than those in H2452 cells but not in 211H/PEM cells compared to the respective parental line. Picropodophyllin induced sub-G1 arrest in H2452/PEM cells but induced G2/M phase arrest in 211H/PEM cells, leading to caspase-independent cell death in the two acquired pemetrexed-resistant MPM lines. Although picropodophyllin inhibited phosphorylation of IGF-1R, specific inhibition of IGF-1R by RNA interference did not reduce the viability of pemetrexed-resistant MPM lines. Additionally, picropodophyllin reduced the viability of both IGF-1R knockdown pemetrexed-resistant MPM cells. Picropodophyllin was cytotoxic in acquired-pemetrexed-resistant MPM lines because of inhibition of microtubule formation and induction of aberrant mitosis. Moreover, combination treatment with picropodophyllin and vinorelbine synergistically affected the pemetrexed-resistant MPM lines but not the parental lines. Furthermore, we observed a similar efficacy of picropodophyllin in 3-dimensional pemetrexed-resistant MPM models.ConclusionsPicropodophyllin may offer novel therapeutic properties for treating acquired pemetrexed-resistant MPM. Targeting tubulin may be an important strategy in the treatment of MPM after the discontinuation of pemetrexed.

Response Facilitation Induced by Insulin-like Growth Factor-I in the Primary Somatosensory Cortex of Mice Was Reduced in Aging.

Aging is accompanied by a decline in cognition that can be due to a lower IGF-I level. We studied response facilitation induced in primary somatosensory (S1) cortical neurons by repetitive stimulation of whiskers in young and old mice. Layer 2/3 and 5/6 neurons were extracellularly recorded in young (≤ 6 months of age) and old (≥ 20 month of age) anesthetized mice. IGF-I injection in S1 cortex (10 nM; 0.2 μL) increased whisker responses in young and old animals. A stimulation train at 8 Hz induced a long-lasting response facilitation in only layer 2/3 neurons of young animals. However, all cortical neurons from young and old animals showed long-lasting response facilitation when IGF-I was applied in the S1 cortex. The reduction in response facilitation in old animals can be due to a reduction in the IGF-I receptors as was indicated by the immunohistochemistry study. Furthermore, a reduction in the performance of a whisker discrimination task was observed in old animals. In conclusion, our findings indicate that there is a reduction in the synaptic plasticity of S1 neurons during aging that can be recovered by IGF-I. Therefore, it opens the possibility of use IGF-I as a therapeutic tool to ameliorate the effects of heathy aging.

It Takes Two to Tango: IGF-I and TSH Receptors in Thyroid Eye Disease.

ContextThyroid eye disease (TED) is a complex autoimmune disease process. Orbital fibroblasts represent the central orbital immune target. Involvement of the TSH receptor (TSHR) in TED is not fully understood. IGF-I receptor (IGF-IR) is overexpressed in several cell types in TED, including fibrocytes and orbital fibroblasts. IGF-IR may form a physical and functional complex with TSHR. ObjectiveReview literature relevant to autoantibody generation in TED and whether these induce orbital fibroblast responses directly through TSHR, IGF-IR, or both. EvidenceIGF-IR has traditionally been considered a typical tyrosine kinase receptor in which tyrosine residues become phosphorylated following IGF-I binding. Evidence has emerged that IGF-IR possesses kinase-independent activities and can be considered a functional receptor tyrosine kinase/G-protein-coupled receptor hybrid, using the G-protein receptor kinase/β-arrestin system. Teprotumumab, a monoclonal IGF-IR antibody, effectively reduces TED disease activity, proptosis, and diplopia. In addition, the drug attenuates in vitro actions of both IGF-I and TSH in fibrocytes and orbital fibroblasts, including induction of proinflammatory cytokines by TSH and TED IgGs.ConclusionsAlthough teprotumumab has been proven effective and relatively safe in the treatment of TED, many questions remain pertaining to IGF-IR, its relationship with TSHR, and how the drug might be disrupting these receptor protein/protein interactions. Here, we propose 4 possible IGF-IR activation models that could underlie clinical responses to teprotumumab observed in patients with TED. Teprotumumab is associated with several adverse events, including hyperglycemia and hearing abnormalities. Underpinning mechanisms of these are being investigated. Patients undergoing treatment with drug must be monitored for these and managed with best medical practices.

Differentiation of Subclinical Ketosis and Liver Function Test Indices in Adipose Tissues Associated With Hyperketonemia in Postpartum Dairy Cattle.

Past studies suggested that during early lactation and the transition period, higher plasma growth hormone (GH) levels in subclinical ketosis (SCK) might involve the initiation of body adipose tissues mobilization, resulting in metabolic disorders in ruminants particularly hyperketonemia. The upregulated GH mRNA expression in adipose tissue may take part in the adipolysis process in SCK-affected cows that paves a way for study further. This study aimed to characterize the plasma levels of GH, β-hydroxybutyrate acid (BHBA) and non-esterified fatty acid (NEFA) and glucose (GLu) in ketotic cows and healthy control (CON) cows; to measure the liver function test (LFT) indices in ketotic and healthy CON cows, and finally the quantitative real-time PCR (qRT-PCR) assay of candidate genes expressed in adipose tissues of ketotic and healthy CON cows during 0 to 7 week postpartum. Three experiments were conducted. Experiment-1 involved 21 Holstein cows weighing 500–600 kg with 2–5 parities. Results showed that GH, BHBA, and NEFA levels in ketotic cows were significantly higher and the GLu level significantly lower. Pearson's correlation analysis revealed a significant positive correlation of GH with BHBA, NEFA, and GLu in ketotic and healthy CON cows. In experiment-2, dynamic monitoring of LFT indices namely, alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (GGT), total bilirubin (TBIL), direct bilirubin (DBIL), total protein (TP), albumin (ALB), globulin (GLOB) and albumin/globulin (A/G) were examined. The TBIL, DBIL, and GGT indices were significantly higher in ketotic cows and TP was significantly lower. In experiment-3, mRNA expression levels of GHR and peroxisome-proliferator-activated receptor alpha (PPARα) genes in adipose tissue were significantly upregulated in ketotic cows. However, the mRNA expression of insulin-like growth factor-I (IGF-1), insulin-like growth factor-I receptor (IGF-1R), and sterol regulatory element-binding protein-1c (SREBP-1c) genes in adipose tissue were downregulated in ketotic cows. Our study concluded that during postpartum, higher plasma GH levels in SCK cows might involve the initiation of body adipose tissue mobilization, resulting in hyperketonemia.

Altered IGF-I activity and accelerated bone elongation in growth plates precede excess weight gain in a mouse model of juvenile obesity.

Nearly one-third of children in the United States are overweight or obese by their preteens. Tall stature and accelerated bone elongation are characteristic features of childhood obesity, which cooccur with conditions such as limb bowing, slipped epiphyses, and fractures. Children with obesity paradoxically have normal circulating IGF-I, the major growth-stimulating hormone. Here, we describe and validate a mouse model of excess dietary fat to examine mechanisms of growth acceleration in obesity. We used in vivo multiphoton imaging and immunostaining to test the hypothesis that high-fat diet increases IGF-I activity and alters growth plate structure before the onset of obesity. We tracked bone and body growth in male and female C57BL/6 mice (n = 114) on high-fat (60% kcal fat) or control (10% kcal fat) diets from weaning (3 wk) to skeletal maturity (12 wk). Tibial and tail elongation rates increased after brief (1-2 wk) high-fat diet exposure without altering serum IGF-I. Femoral bone density and growth plate size were increased, but growth plates were disorganized in not-yet-obese high-fat diet mice. Multiphoton imaging revealed more IGF-I in the vasculature surrounding growth plates of high-fat diet mice and increased uptake when vascular levels peaked. High-fat diet growth plates had more activated IGF-I receptors and fewer inhibitory binding proteins, suggesting increased IGF-I bioavailability in growth plates. These results, which parallel pediatric growth patterns, highlight the fundamental role of diet in the earliest stages of developing obesity-related skeletal complications and validate the utility of the model for future studies aimed at determining mechanisms of diet-enhanced bone lengthening.NEW & NOTEWORTHY This paper validates a mouse model of linear growth acceleration in juvenile obesity. We demonstrate that high-fat diet induces rapid increases in bone elongation rate that precede excess weight gain and parallel pediatric growth. By imaging IGF-I delivery to growth plates in vivo, we reveal novel diet-induced changes in IGF-I uptake and activity. These results are important for understanding the sequelae of musculoskeletal complications that accompany advanced bone age and obesity in children.

Assessment of androgen receptor, IGF-IR and insulin receptor expression in male patients with severe peripheral artery disease

BackgroundPeripheral artery disease (PAD) of the lower limbs is a common condition that can affect quality of life. Androgen receptor (AR) can exert sex-specific effects on metabolic system, endothelial function and vascular tone. IGF-I receptor (IGF-IR) and insulin receptor (IR) may also be involved in the aforementioned functions. The aim of this study was to evaluate AR, IGF-IR and IR expression in the arterial vessel walls of PAD patients. ResultsThis is a cross-sectional study examining 30 males with PAD undergoing open surgery procedures. Mean age was 75.9 ± 8.8y. All patients belonged to Rutherford stage 4–6. Median expression levels of IR, IGF-IR and AR significantly decreased from stage 4–6 (p < 0.05). SignificanceThe study evidenced a progressive decrease of IR, IGF-IR and AR expression as the severity of disease increased. Altered levels of IR, IGF-IR and AR following PAD may be useful for the clinical evaluation of these patients.

Effects of &lt;i&gt;S&lt;/i&gt;-allyl-L-cysteine on phosphorylation of insulin-like growth factor type-I receptor tyrosine kinase in primary cultures of adult rat hepatocytes.

Effects of &lt;i&gt;S&lt;/i&gt;-allyl-L-cysteine on phosphorylation of insulin-like growth factor type-I receptor tyrosine kinase in primary cultures of adult rat hepatocytes.

EPIGENETIC FACTORS OF SERUM URIC ACID LEVEL AND RELATED GENE POLYMORPHISMS IN SHENYANG, CHINA.

The purpose of this study was to explore the influencing factors of serum uric acid (SUA) level and related gene polymorphisms in the healthy population. A total of 346 healthy individuals screened from different areas in Shenyang City and 195 patients with high SUA levels were included. The levels of TC (total cholesterol), HDL-C (high-density lipoprotein cholesterol), LDL-C (low-density lipoprotein cholesterol), TG (triglycerides), GLU (blood glucose) ALT (alanine aminotransferase), TBA (total bile acid), TBIL (total bilirubin), CR (creatinine) and CYSC (Cystatin C) were statistically different between the healthy and hyperuricemia population (P<0.05). However, there was no statistical difference in the UA level between the two groups (P>0.05). After adjusting for UA, TC, HDL-C, LDL-C, GLU, TBIL and CYSC, the additive and recessive models of rs2231142 were statistically significant in females (P<0.05). For males, haplotypes of A-C-A-A-G-G, A-C-G-C-G-G and A-T-G-A-A-G had significant difference between the healthy and hyperuricemia population (P<0.05). For females, the haplotypes of A-C-G-C-G-G and A-T-A-C-A-T had significant differences (P<0.05). The distributions of SLC2A9 (solute carrier family 2 and facilitated glucose transporter member 9), ABCG2 (ATP-binding cassette G2), GCKR (glucokinase regulatory protein), KCNQ1, IGFIR (Insulin-like growth factor-I receptor) and VEGFR (Vascular Endothelial Growth Factor Receptor) were balanced in the population in Shenyang City. The haplotypes of A-C-A-A-G-G, A-C-G-C-G-G and A-T-G-A-A-G were the influencing factors of high SUA in the population in Shenyang City.

Potential role of IGF-1/GLP-1 signaling activation in intracerebral hemorrhage.

IGF-1 and GLP-1 receptors are essential in all tissues, facilitating defense by upregulating anabolic processes. They are abundantly distributed throughout the central nervous system, promoting neuronal proliferation, survival, and differentiation. IGF-1/GLP-1 is a growth factor that stimulates neurons' development, reorganization, myelination, and survival. In primary and secondary brain injury, the IGF-1/GLP-1 receptors are impaired, resulting in further neuro complications such as cerebral tissue degradation, neuroinflammation, oxidative stress, and atrophy. Intracerebral hemorrhage (ICH) is a severe condition caused by a stroke for which there is currently no effective treatment. While some pre-clinical studies and medications are being developed as symptomatic therapies in clinical trials, there are specific pharmacological implications for improving post-operative conditions in patients with intensive treatment. Identifying the underlying molecular process and recognizing the worsening situation can assist researchers in developing effective therapeutic solutions to prevent post-hemorrhagic symptoms and the associated neural dysfunctions. As a result, in the current review, we have addressed the manifestations of the disease that are aggravated by the downregulation of IGF-1 and GLP-1 receptors, which can lead to ICH or other neurodegenerative disorders. Our review summarizes that IGF-1/GLP-1 activators may be useful for treating ICH and its related neurodegeneration.

Immunocytochemistry and western blot test for the in-situ detection of biomarkers of osteogenesis

There are two ways that bones can form: intramembranous and endochondral ossification. Specific osteogenic markers, such as insulin-like growth factor (IGF-1), osteocalcin (OCN), Runt-related transcription factor 2 (RUNX2), and osterix (OSX), accompany osteoblast differentiation from an undifferentiated state to a functional state. IGF-1 hormones are the main regulators in growth, differentiation, and apoptosis in cells and tissues mediated by IGF-1 receptors (IGF-1R). Biomolecular technology aims to study nucleic acids and their regulation and expression of proteins. Techniques that can be used when analyzing proteins include the Bradford protein assay, immunocytochemistry, immunohistochemistry, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, and the western blot test. To better understand the biomarkers of osteogenesis, the use of in-situ detection is suggested, such as immunocytochemistry and the western blot test. For this review, the author adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) standards. The research examined 50 articles; only 4 articles were selected for this review. In the immunocytochemical test, IGF-1 expression was found in the nucleus and IGF-1R expression in the cell membrane, and it was found that RUNX2, OSN, and OCN are important for osteogenesis. During the western blot test, it was found that the addition of IGF-1 in dental stem cells could increase the expression of RUNX2, OSX, and OCN proteins. Based on this information, it appears that both immunocytochemistry and western blot tests can detect the main biomarkers of osteogenesis.

A Role for ER-Beta in the Effects of Low-Density Lipoprotein Cholesterol and 27-Hydroxycholesterol on Breast Cancer Progression: Involvement of the IGF Signalling Pathway?

Cholesterol—in particular, high levels of low-density lipoprotein (LDL) and its metabolite, 27-hydroxycholesterol (27-OHC)—is correlated with increases in the risks of breast cancer and obesity. Although the high expression of LDL/27-OHC has been reported in breast cancer, its effects and mechanism of action remain to be fully elucidated. In this study, we found that the effects of LDL on cell proliferation were mediated by the activation of the cytochrome P450 enzyme, sterol 27 hydroxylase, and cholesterol 27-hydroxylase (CYP27A1) in both ER-α-positive and ER-α-negative breast cancer cells. We found that treatment with 27-OHC only increased cell growth in oestrogen receptor-α (ER-α)-positive breast cancer cells in an ER-α-dependent manner, but, interestingly, the effects of 27-OHC on cell migration and invasion were independent of ER-α. Using ER-α-negative MDA-MB-231 cells, we found that 27-OHC similarly promoted cell invasion and migration, and this was mediated by oestrogen receptor β (ER-β). These results suggest that 27-OHC promotes breast cancer cell proliferation in ER-α-positive breast cancer cells via ER-α, but migration and invasion are mediated via ER-β in ER-α positive and negative cell lines. The addition of LDL/27OHC increased the production of IGF-I and the abundance of IGF-IR in TNBC. We further found that modulating ER-β using an agonist or antagonist increased or decreased, respectively, levels of the IGF-I and EGF receptors in TNBC. The inhibition of the insulin-like growth factor receptor blocked the effects of cholesterol on cell growth and the migration of TNBC. Using TCGA and METABRIC microarray expression data from invasive breast cancer carcinomas, we also observed that higher levels of ER-beta were associated with higher levels of IGF-IR. Thus, this study shows novel evidence that ER-β is central to the effects of LDL/27OHC on invasion, migration, and the IGF and EGF axes. Our data suggest that targeting ER-β in TNBC could be an alternative approach for downregulating IGF/EGF signalling and controlling the impact of LDL in breast cancer patients.

Therapeutic IGF-I receptor inhibition alters fibrocyte immune phenotype in thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) represents a disfiguring and potentially blinding autoimmune component of Graves' disease. It appears to be driven, at least in part, by autoantibodies targeting the thyrotropin receptor (TSHR)/insulin-like growth factor I receptor (IGF-IR) complex. Actions mediated through either TSHR or IGF-IR are dependent on IGF-IR activity. CD34+ fibrocytes, monocyte lineage cells, reside uniquely in the TAO orbit, where they masquerade as CD34+ orbital fibroblasts. Fibrocytes present antigens to T cells through their display of the major histocompatibility complex class II (MHC II) while providing costimulation through B7 proteins (CD80, CD86, and programmed death-ligand 1 [PD-L1]). Here, we demonstrate that teprotumumab, an anti-IGF-IR inhibitor, attenuates constitutive expression and induction by the thyroid-stimulating hormone of MHC II and these B7 members in CD34+ fibrocytes. These actions are mediated through reduction of respective gene transcriptional activity. Other IGF-IR inhibitors (1H7 and linsitinib) and knocking down IGF-IR gene expression had similar effects. Interrogation of circulating fibrocytes collected from patients with TAO, prior to and following teprotumumab treatment invivo during a phase 2 clinical trial, demonstrated reductions in cell-surface MHC II and B7 proteins similar to those found following IGF-IR inhibitor treatment invitro. Teprotumumab therapy reduces levels of interferon-γ and IL-17A expression in circulating CD4+ T cells, effects that may be indirect and mediated through actions of the drug on fibrocytes. Teprotumumab was approved by the US Food and Drug Administration for TAO. Our current findings identify potential mechanisms through which teprotumumab might be eliciting its clinical response systemically in patients with TAO, potentially by restoring immune tolerance.

Loss of sensitivity to insulin-like growth factor I in orexin neurons is associated to perturbed sleep patterns during aging.

Sleep disturbances are common during aging. Old mice show altered sleep structure, with changes in both slow and fast electro-corticographic (ECG) activity, and less transitions between sleep and wake stages, as compared to young animals. Insulin-like growth factor I (IGF-I), that is involved in hormonal changes during aging, was previously shown to increase ECG patterns in young mice and monkeys. More recently, we observed that IGF-I shapes sleep architecture through modulation of the activity of mouse orexin neurons in the lateral hypothalamus (LH). We now report that both stimulation of ECG patterns and activation of orexin neurons by systemic IGF-I were abrogated in old mice. Further, activation of orthodromically stimulated LH neurons by either systemic or local IGF-I in young mice was absent in old mice. As orexin neurons of old mice show markedly increased IGF-I receptor (IGF-IR) levels, suggesting loss of sensitivity to IGF-I, we treated them with AIK3a305, a novel IGF-IR sensitizer, and observed restored responses to IGF-I and rejuvenation of ECG patterns. Thus, disturbed sleep structure in aging mice may be related to IGF-I resistance in orexin neurons, reflecting a broader loss of IGF-I activity in the aged mouse brain.

Cholinergic and cortical activity is recovered by insulin-like growth factor I in aging mice brains.

It is known that IGF-I facilitates a waking state and modulates sleep architecture through the activation of orexinergic neurons. However, IGF-I may activate other neurons that may facilitate waking states, such as the locus coeruleus and the basal forebrain, orchestrating an intricate role in brain and cortical regulation. The BF is a structure that contains cholinergic neurons that project entirely to the brain cortex and support cerebral activity and cognitive function. Besides, cholinergic dysfunction through aging has been related to AD and cognitive decline. This work aims to determine if IGF-I has a modulatory role in cortical and BF activity, facilitating waking state by activating cholinergic neurons in young and old mice. We use transgenic mice models with channel-rhodopsin specifically in cholinergic neurons, and C57 (less than 6 months and over 22 months of age). We take advantage of immunofluorescence, electrophysiology and optogenetics experiments. We demonstrate that ChAT neurons have IGF-I receptors and respond to intraparenchymal IGF-I diffusion, facilitating an increased firing rate in young but not in old mice. This facilitation of cholinergic activity by IGF-I increases the EEG activation (faster activity increases in the power spectrum). The effect depends on muscarinic receptors because their activity is blocked by atropine. Also, IGF-I facilitates theta rhythm generation that is a hallmark of the waking state in young rodents. After IGF-I chronic treatment, the waking state's effects, ChAT neuronal response, and cortical activity was recovered in old mice. Consequently with our results, IGF-I can activate wakefulness by synchronously activating structures that favor it. This finding may suggest that IGF-I or mimetic drugs of this peptide would favor cholinergic activity during aging.

Inhibition of TSH/IGF-1 Receptor Crosstalk by Teprotumumab as a Treatment Modality of Thyroid Eye Disease.

We previously presented evidence that TSH receptor (TSHR)-stimulating autoantibodies (TSAbs) bind to and activate TSHRs but do not bind to IGF1 receptors (IGF1Rs). Nevertheless, we showed that IGF1Rs were involved in thyroid eye disease (TED) pathogenesis because TSAbs activated crosstalk between TSHR and IGF1R. Teprotumumab, originally generated to inhibit IGF1 binding to IGF1R, was recently approved for the treatment of TED (Tepezza). To investigate the role of TSHR/IGF1R crosstalk in teprotumumab treatment of TED. We used orbital fibroblasts from patients with TED (TEDOFs) and measured stimulated hyaluronan (HA) secretion as a measure of orbital fibroblast activation by TED immunoglobulins (TED-Igs) and monoclonal TSAb M22. We previously showed that M22, which does not bind to IGF1R, stimulated HA in a biphasic dose-response with the higher potency phase dependent on TSHR/IGF1R crosstalk and the lower potency phase independent of IGF1R. Stimulation by TED-Igs and M22 was measured in the absence or presence of teprotumumab biosimilar (Tepro) or K1-70, an antibody that inhibits TSHR. We show: (1) Tepro dose-dependently inhibits stimulation by TED-Igs; (2) Tepro does not bind to TSHRs; (3) Tepro inhibits IGF1R-dependent M22-induced HA production, which is mediated by TSHR/IGF1R crosstalk, but not IGF1R-independent M22 stimulation; and (4) β-arrestin 1 knockdown, which blocks TSHR/IGF1R crosstalk and prevents Tepro inhibition of HA production by M22 and by a pool of TED-Igs. We conclude that Tepro inhibits HA production by TEDOFs by inhibiting TSHR/IGF1R crosstalk and suggest that inhibition of TSHR/IGF1R crosstalk is the mechanism of its action in treating TED.