IGF-1R Research Articles

DDDR-37. OHSV AND RADIATION THERAPIES SENSITIZE GLIOBLASTOMA TO IGF1R-TARGETED THERAPY AND SYNERGIZE IN TRIPLE COMBINATION THERAPY

Abstract Glioblastoma (GBM) continues to have a dismal prognosis despite remarkable advances in the field due to both tumor-intrinsic factors (i.e., IDH1 or EGFRvIII mutations) and extrinsic factors (i.e., relating to the tumor microenvironment (TME)), necessitating therapeutic innovation. Oncolytic herpes simplex virus-1 (oHSV) is an FDA-approved therapy that has shown promising results in clinical trials; however, therapeutic efficacy is limited to a small subset of patients. Thus, elucidating both the tumor-TME interplay and feedback/feedforward tumor-cell signaling in the context of viro-immunotherapy is essential in augmenting therapeutic outcomes. We recently discovered a novel mechanism of resistance to oHSVs, in which infection increases secretion of Insulin-like growth factor 2 (IGF2), activating the Insulin-like Growth Factor-1 Receptor (IGF1R). Upregulation of the IGF1R signaling pathway in GBM is correlated with poor prognosis and has been implicated in resistance to conventional therapies including radiotherapy (RTx). Herein, we further elucidate the impact of oHSVs on IGF1R activation, demonstrating a dose-dependent enhancement of downstream signaling. While IGF1R targeting therapies (e.g., OSI-966, Picropodophyllin (PPP)) have displayed limited efficacy in clinical trials, they significantly increased oHSV-induced cytotoxicity in all tested primary GBM cells compared to either agent alone in vitro and in vivo, resulting in a dose-dependent increase in PARP and caspase 3 activity by western blot and immunohistochemistry. We further found that RTx-induced IGF1 secretion and subsequent IGF1R activation were enhanced when combined with oHSV treatment. Triple combination therapy with oHSV, IGF1R inhibition, and RTx significantly increased tumor cell killing in vitro and improved survival of orthotopic GBM tumor-bearing mice. Collectively, our study provides preclinical evidence of enhanced therapeutic efficacy of oHSVs and RTx in combination with IGF1R blockade, supporting future use of IGF1R inhibitors in combination with the standard of care and FDA-approved oHSV therapies in patients with GBM.

TMIC-58. LEVERAGING VIRO-IMMUNOTHERAPY BY TARGETING IGF2-IGF1R SIGNALING

Abstract While an FDA-approved oncolytic herpes simplex-1 virus (oHSV) has shown therapeutic promise with superior safety, accumulating clinical data revealed that its therapeutic efficacy is observed in a small subset of patients. Here, we show that NFκB-mediated Insulin-like Growth Factor 2 (IGF2)/Insulin-like Growth Factor-1 Receptor (IGF1R) signaling pathway as a key modulator for oHSV therapy-mediated tumor resistance. RNA sequencing on the oHSV-infected primary glioblastoma (GBM) and breast cancer (BC) cells identified IGF2 as one of the top 10 upregulated secretomes. Transcriptomic analysis also revealed significant upregulation/enrichment of genes related to IGF2-IGF1R-MAPK pathway in oHSV-treated tumor cells. Infection with oHSV in GBM and BC cells up-regulated IGF2 transcription via direct binding of NFκB in the IGF2 promoter 3. Compromising the IGF2-IGF1R signaling pathway using IGF2 neutralizing antibody significantly increased oHSV-mediated tumor cell killing in vitro and mice survival in vivo. To circumvent this and promptly translate our findings in clinical settings, we have developed a novel oHSV, oHSV-D11mt, by incorporating modified IGF2R domain 11 into the parental oHSV genome to function as IGF2 decoy receptor as a single-agent modality. oHSV-D11mt specifically bind to IGF2 not IGF1, blocks oHSV-induced IGF2-IGF1R signaling, increases tumor cell killing, decreases oHSV-induced neutrophils/PMN-MDSCs infiltration, immune suppressive/proangiogenic cytokine secretion, and increases CD8+ cytotoxic T lymphocytes (CTLs) activation, resulting in increased virus propagation and mice survival. These findings suggest that IGF2-IGF1R signaling is a novel target to overcome oHSV therapy resistance and oHSV-D11mt could be used for improved viro-immunotherapy.

Metformin Impairs Linsitinib Anti-Tumor Effect on Ovarian Cancer Cell Lines

Ovarian cancer (OC) remains one of the leading causes of cancer-related mortality among women. Targeting the insulin-like growth factor 1 (IGF-1) signaling pathway has emerged as a promising therapeutic strategy. Linsitinib, an IGF-1 receptor (IGF-1R) inhibitor, has shown potential in disrupting this pathway. Additionally, metformin, commonly used in the treatment of type 2 diabetes, has been studied for its anti-cancer properties due to its ability to inhibit metabolic pathways that intersect with IGF-1 signaling, making it a candidate for combination therapy in cancer treatments. This study explores the anti-cancer effects of linsitinib and metformin on OVCAR3 cells by the suppression of the IGF-1 signaling pathway by siRNA-mediated IGF-1 gene silencing. The goal is to evaluate their efficacy as therapeutic agents and to emphasize the critical role of this pathway in OC cell proliferation. Cellular viability was evaluated by resazurin-based assay, and apoptosis was assessed by flux cytometry. The results of this study indicate that the combination of linsitinib and metformin exhibits an antagonistic effect (obtained by SynergyFinder 2.0 Software), reducing their anti-neoplastic efficacy in OC cell lines. Statistical analyses were performed using ordinary one-way or two-way ANOVA, followed by Tukey’s or Šídák’s multiple comparison tests. While linsitinib shows promise as a therapeutic option for OC, further research is needed to identify agents that could synergize with it to enhance its therapeutic efficacy, like the combination with standard chemotherapy in OC (carboplatin and paclitaxel).

Female sex hormones inversely regulate acute kidney disease susceptibility throughout life.

While epidemiological and experimental studies have demonstrated kidney-protective effects of estrogen and female sex in adulthood, some epidemiological data showed deterioration of kidney function during puberty when estrogen production increases. However, molecular mechanisms explaining these conflicting phenomena remain unknown. Here, we showed that the pubertal sex hormone surge in female mice increases susceptibility to kidney ischemia reperfusion injury partly via downregulation of insulin-like growth factor 1 receptor (IGF-1R) expression in proximal tubules. Adult mice ovariectomized pre-pubertally (at postnatal day 21) showed strong tolerance to kidney ischemia, which was partly reversed by the administration of 17β-estradiol, while adult mice ovariectomized post-pubertally (at 8 weeks of age) were vulnerable to kidney ischemia. Kidney tubular IGF-1R protein expression decreased during postnatal growth but was highly expressed in adult mice ovariectomized pre-pubertally and in infant mice, which might be partly explained by different expression of an E3 ligase (MDM2) of IGF-1R. Mice deficient of Igf-1r in proximal tubules (iIGF-1RKO mice) during postnatal kidney growth showed increased susceptibility to ischemic injury. RNA-seq and western blotting analysis using proximal tubular cells from pre-pubertally ovariectomized iIGF-1RKO and control mice revealed altered expression of cell cycle-associated molecules such as cyclin D1. These results suggest that Igf-1r deletion during postnatal growth renders proximal tubular cells susceptible to ischemia possibly via altered cell cycle regulation. Thus, our findings provide evidence that exposure to pubertal sex hormones leads to increased susceptibility to kidney ischemia, which is partly mediated by modulation of IGF-1R signaling.

Tumor Cytobiology of IGF-1R in Breast Tumor Activation and Propagation; And the Role of Celecoxib in its Inhibition

The Insulin-like Growth Factor 1 Receptor (IGF-1R) stands as a central orchestrator in cellular signaling, governing pivotal processes encompassing growth, proliferation, and differentiation. Its aberrant activation is intricately intertwined with the pathogenesis and progression of breast cancer, a heterogeneous disease presenting formidable clinical challenges. Amidst the burgeoning landscape of therapeutic interventions, Celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), has emerged as a promising candidate for targeting the dysregulated IGF-1R pathway. This review delineates the intricate molecular mechanisms underlying Celecoxib's modulation of the IGF-1R pathway, elucidating its pharmacokinetic properties and therapeutic implications in breast cancer management. Celecoxib exerts inhibitory effects on IGF-1R through multifaceted molecular interactions, impeding receptor activation and downstream signaling cascades pivotal for tumor proliferation and metastasis. Furthermore, it regulates IGF-1R expression at both transcriptional and translational levels, exerting nuanced control over cellular responses. Moreover, Celecoxib's therapeutic impact transcends mere IGF-1R inhibition, as it potentiates pro-apoptotic pathways and disrupts tumor-permissive microenvironments. A nuanced understanding of Celecoxib's pharmacokinetic profile is imperative, considering its sustained and targeted inhibition of IGF-1R signaling, and its potential synergistic effects in combinatorial therapeutic regimens for breast cancer. This comprehensive elucidation underscores the paramount importance of deciphering Celecoxib's intricate molecular interplay with the IGF-1R pathway, heralding novel avenues for precision medicine and tailored therapeutic interventions in the management of breast cancer.

Advances in Research on the Anticancer Properties and Mechanisms of Metformin in Lung Cancer.

Lung cancer is a leading cause of death globally with high mortality and morbidity. Patients are often diagnosed at an advanced stage. Metformin has become a primary medication used in the clinical management of type 2 diabetes mellitus (T2DM) due to its relative safety, low cost, and effectiveness, mainly exerting its hypoglycemic effect by inhibiting hepatic gluconeogenesis and insulin resistance. Research data indicate that metformin extends the distant metastasis-free survival (DMFS) and progression-free survival (PFS) of diabetic patients with lung cancer, improving overall survival rates. Metformin lowers the risk of tumour development through various mechanisms, including the adenosine 5'-monophosphate-activated protein kinase/liver kinase B1/mechanistic target of rapamycin (AMPK/LKB1/mTOR) pathway, insulin-like growth factor-1 receptor pathway, apoptosis, and autophagy. However, research findings are not entirely consistent. This article reviews the research progress of metformin in terms of lung cancer treatment within the past few years, aiming to provide a more comprehensive understanding of how metformin exerts its anti-cancer impact and how it can be clinically applied, as well as provide new insights for lung cancer treatment.

Endothelial insulin-like growth factor-1 signaling regulates vascular barrier function and atherogenesis

Abstract Background Progressive deposition of cholesterol in the arterial wall characterizes atherosclerosis, which underpins most cases of myocardial infarction and stroke. Insulin-like growth factor-1 (IGF-1) is a hormone that regulates systemic growth and metabolism and possesses anti-atherosclerotic properties. However, the role of IGF-1 in the endothelium remains unexplored. Purpose To study the effect of increased endothelial IGF-1 receptor (IGF-1R) expression on atherogenesis using in vivo and in vitro models. Methods We generated atherosclerosis prone ApoE-/- transgenic mice with endothelium restricted overexpression of human IGF-1R (hIGFREO-ApoE-/-) or signalling defective K1003R mutant IGF-1R (mIGFREO-ApoE-/-). ApoE-/- littermates were controls. Following 12 weeks of western diet, we assessed atherosclerosis, systemic metabolism, leukocyte homeostasis and vascular permeability using histology, flow cytometry, metabolic testing, bone marrow transplantation and in vivo perfusion with either VE-Cadherin, Evans blue or BODIPY-LDL. For in vitro studies, human umbilical vein endothelial cells were transduced with custom-made lentivirus particles allowing doxycyline-inducible wild-type or mutant K1003R IGF-1R overexpression; with transduced cells not exposed to doxycycline as controls. Confluent cells were exposed to 100mM hydrogen peroxide to model the permeability-inducing conditions observed in atherosclerosis. In vitro, we assessed junctional proteins, FITC-dextran permeability and transcellular BODIPY-LDL uptake. Results We show that mice with endothelial overexpression of IGF-1R have less atherosclerosis, arterial cholesterol uptake, and vascular leakage of multiple organs. Conversely, mice with endothelial overexpression of signalling defective IGF-1R did not exhibit these phenomena. We found no differences in systemic metabolism or growth. In complementary in vitro studies, overexpressing wildtype IGF-1R altered the localization of some tight junction proteins (VE-Cadherin and Claudin 5) and reduced leakage across human endothelial monolayers; this was not observed with signalling defective IGF-1R. Moreover, it reduced endothelial cell internalization of cholesterol-rich lipoproteins and increased the association of these particles with clathrin, but not caveolin-1, both of which participate in vesicular uptake of lipoproteins. Conclusion Overall, our findings indicate that endothelial IGF-1 signalling modulates both para- and trans-cellular vascular barrier function. This is particularly relevant to the phenomenon of atherosclerosis and suggests that increased vascular IGF-1 signalling reduces atherosclerosis. Beyond this, our data are potentially relevant to many disease processes associated with altered vascular barrier function. This discovery could lead to novel therapeutics to normalise vascular barrier function.

Deletion of nephrocystin 4 exacerbates cardiac function and survival rate in a mouse model of cardio-renal syndrome

Abstract Background Cardiorenal syndrome (CRS), characterized by cardiac and renal dysfunction, is an increasing health problem associated with high mortality rate. Nephrocystin 4 (NPHP4) gene is the major cause of end-stage renal disease in children. We have reported NPHP4 single nucleotide polymorphism is the genetic risk for CRS and subsequent cardiovascular events in general population. However, the functional role of Nphp4 in the development of CRS has never been examined yet. Methods and Results We generated systemic Nphp4 knockout (KO) mice deleting exon 3 to 8 using CRISPR-Cas9 system. RNA sequence analysis of heart and kidney tissues demonstrated that gene-sets related to mitochondrial function were significantly downregulated in Nphp4 KO mice compared to their wild-type (WT) littermates. Nphp4 KO mice showed less cardiac hypertrophy, however, exacerbated cardiac function and survival compared to WT mice in a CRS model induced by thoracic transverse aortic constriction. Nphp4 located in endosome and cell membrane in H9C2 cardiomyocytes. Immunoprecipitation confirmed protein interaction between Nphp4 and HECT-type E3 ligase Itch. Furthermore, we found that Itch targeted Lats2 and insulin-like growth factor-1 receptor in cardiomyocytes. Knockdown of Nphp4 activated Hippo signaling and worsened mitochondrial function in H9C2 cardiomyocytes through the inhibition of Itch-dependent Lats2 degradation. Knockdown of Nphp4 inhibited insulin-like growth factor-1 signaling through the disturbance of Itch-mediated endosome function. Conclusions Deletion of Nphp4 impaired compensatory cardiac hypertrophy and exacerbated cardiac function and survival in a mouse CRS model through mitochondrial dysfunction. Nphp4 mediated Hippo signaling and insulin-like growth factor-1 signaling through the interaction with Itch. NPHP4 could be the novel therapeutic target in CRS.figure1figure2

Characterization and Regulation of the Neonatal Growth Hormone Surge.

High neonatal growth hormone (GH) secretion has been described in several species. However, the neuroendocrine mechanisms behind this surge remain unknown. Thus, the pattern of postnatal GH secretion was investigated in mice and rats. Blood GH levels were very high on postnatal day (P)1 and progressively decreased until near zero by P17 in C57BL/6 mice without sex differences. This pattern was similar to that observed in rats, except that female rats showed higher GH levels on P1 than males. In comparison, follicle-stimulating hormone exhibited higher secretion in females during the first 3 weeks of life. Hypothalamic Sst mRNA and somatostatin neuroendocrine terminals in the median eminence were higher in P20/P21 mice than in newborns. Knockout mice for GH-releasing hormone (GHRH) receptor showed no GH surge, whereas knockdown mice for the Sst gene displayed increased neonatal GH peak. Leptin deficiency caused only minor effects on early-life GH secretion. GH receptor ablation in neurons or the entire body did not affect neonatal GH secretion, but the subsequent reduction in blood GH levels was attenuated or prevented by these genetic manipulations, respectively. This phenotype was also observed in knockout mice for the insulin-like growth factor-1 (IGF-1) receptor in GHRH neurons. Moreover, glucose-induced hyperglycemia overstimulated GH secretion in neonatal mice. In conclusion, GH surge in the first days of life is not regulated by negative feedback loops. However, neonatal GH secretion requires GHRH receptor, and is modulated by somatostatin and blood glucose levels, suggesting that this surge is controlled by hypothalamic-pituitary communication.

IGF1R signaling in perinatal mesenchymal stem cells determines definitive hematopoiesis in bone marrow

During the transition from embryonic to adult life, the sites of hematopoiesis undergo dynamic shifts across various tissues. In adults, while bone marrow becomes the primary site for definitive hematopoiesis, the establishment of the bone marrow niche for accommodating hematopoietic stem cells (HSCs) remains incompletely understood. Here, we reveal that perinatal bone marrow mesenchymal stem cells (BMSCs) exhibit highly activated insulin-like growth factor 1 receptor (IGF1R) signaling compared to adult BMSCs. Deletion of Igf1r in perinatal BMSCs hinders the transition of HSCs from the fetal liver to the bone marrow in perinatal mice and disrupts hematopoiesis in adult individuals. Conversely, the deletion of Igf1r in adult BMSCs, adipocytes, osteoblasts, or endothelial cells does not affect HSCs in the bone marrow. Mechanistically, IGF1R signaling activates the transcription factor nuclear factor of activated T cells c1 (NFATc1) in perinatal BMSCs, which upregulates CXCL12 and other niche factors for HSC retention. Overall, IGF1R signaling in perinatal BMSCs regulates the development of the bone marrow niche for hematopoiesis.

The TSH Receptor Antibody Reactome Contributes to Retro-Orbital Inflammation.

The thyroid eye disease (TED) of Graves disease is associated with high titers of stimulating TSH receptor antibodies, retro-orbital inflammation, fibroblast release of cytokines and chemokines, and adipogenesis, which in turn leads to proptosis, muscle fibrosis, and dysfunction. Part of this scenario is the induction of fibroblast proliferation and autophagy secondary to synergism between the TSH receptor (TSHR) and the insulin-like growth factor-1 receptor (IGF-1R). While TED is well associated with thyroid-stimulating antibodies to the TSHR, which is also well expressed on fibroblasts, in fact the TSHR reactome has a variety of TSHR antibodies with varying biological activity. Therefore, we have now evaluated the possible role of neutral TSHR antibodies (N-TSHR-mAbs), directed at the hinge region of the TSHR, which do not induce cell proliferation but are known to have effects on multiple proteins in thyroid cells including stress-related signaling molecules. We examined the consequences of an N-TSHR-mAb acting on TSHR-expressing fibroblasts and found marked cell stress, which initiated signaling pathways involving inflammasome activation. This response ended in widespread cell death by pyroptosis through activation of caspase 8 and gasdermin D. Hence, not only can stimulating TSHR autoantibodies influence TED inflammation but the N-TSHR antibodies, representing more of the reactome, may also exaggerate the retro-orbital inflammatory response seen in TED.

Catalytic activities of wild-type C. elegans DAF-2 kinase and dauer-associated mutants.

DAF-2, the Caenorhabditis elegans insulin-like receptor homolog, regulates larval development, metabolism, stress response, and lifespan. The availability of numerous daf-2 mutant alleles has made it possible to elucidate the genetic mechanisms underlying these physiological processes. The DAF-2 pathway is significantly conserved with the human insulin/IGF-1 signaling pathway; it includes proteins homologous to human IRS, GRB-2, and PI3K, making it an important model to investigate human pathological conditions. We expressed and purified the kinase domain of wild-type DAF-2 to examine the catalytic activity and substrate specificity of the enzyme. Like the human insulin receptor kinase, DAF-2 kinase phosphorylates tyrosines within specific YxN or YxxM motifs, which are important for recruiting downstream effectors. DAF-2 kinase phosphorylated peptides derived from the YxxM and YxN motifs located in the C-terminal extension of the receptor tyrosine kinase, consistent with the idea that the DAF-2 receptor may possess independent signaling capacity. Unlike the human insulin or IGF-1 receptor kinases, DAF-2 kinase was poorly inhibited by the small-molecule inhibitor linsitinib. We also expressed and purified mutant kinases corresponding to daf-2 alleles that result in partial loss-of-function phenotypes in C. elegans. These mutations caused a complete loss of kinase function in vitro. Our biochemical investigations provide new insights into DAF-2 kinase function, and the approach should be useful for studying other mutations to shed light on DAF-2 signaling in C. elegans physiology.

Evolutionary Sequences and Structural Information-driven Reconstruction of New Insulin-like Growth Factor-I Peptide Variants.

Insulin-like growth factor-I (IGF-I) is crucial in controlling cell growth, proliferation, and apoptosis. Its strong link to the development of cancers such as breast, prostate, lung, thyroid, and colorectal has positioned the IGF-1 signalling pathway as a promising target for novel cancer therapies. When activated, the IGF-1 receptor (IGF-1R) binds to IGF-I, playing a central role in promoting tumour cell growth and survival. In this study, we combined evolutionary sequences with structural and functional data of IGF-1 to reconstruct ancestral sequences and design novel IGF-1 peptide variants. The insulin-like growth factor system exhibits a vast sequence diversity, yet it shares a similar structural topology with conserved three pairs of disulfide linkages. Our study reveals that IGF-1 is associated with the IGF system of cell surface receptors through protein-protein interactions. Reconstructed IGF-1 variants show similar structure fold to reported viral IGF-1 competitive antagonists. This new insight guides the design of novel natural IGF-1 mimic peptides. It enhances our understanding of IGF-1's functionality and opens new avenues for the development of therapeutic peptides and small molecules as anticancer agents.

Follistatin drives neuropathic pain in mice through IGF1R signaling in nociceptive neurons.

Neuropathic pain is a debilitating chronic condition that lacks effective treatment. The role of cytokine- and chemokine-mediated neuroinflammation in its pathogenesis has been well documented. Follistatin (FST) is a secreted protein known to antagonize the biological activity of cytokines in the transforming growth factor-β (TGF-β) superfamily. The involvement of FST in neuropathic pain and the underlying mechanism remain largely unknown. Here, we report that FST was up-regulated in A-fiber sensory neurons after spinal nerve ligation (SNL) in mice. Inhibition or deletion of FST alleviated neuropathic pain and reduced the nociceptive neuron hyperexcitability induced by SNL. Conversely, intrathecal or intraplantar injection of recombinant FST, or overexpression of FST in the dorsal root ganglion (DRG) neurons, induced pain hypersensitivity. Furthermore, exogenous FST increased neuronal excitability in nociceptive neurons. The biolayer interferometry (BLI) assay and coimmunoprecipitation (co-IP) demonstrated direct binding of FST to the insulin-like growth factor-1 receptor (IGF1R), and IGF1R inhibition reduced FST-induced activation of extracellular signal-regulated kinase (ERK) and protein kinase B (AKT), as well as neuronal hyperexcitability. Further co-IP analysis revealed that the N-terminal domain of FST exhibits the highest affinity for IGF1R, and blocking this interaction with a peptide derived from FST attenuated Nav1.7-mediated neuronal hyperexcitability and neuropathic pain after SNL. In addition, FST enhanced neuronal excitability in human DRG neurons through IGF1R. Collectively, our findings suggest that FST, released from A-fiber neurons, enhances Nav1.7-mediated hyperexcitability of nociceptive neurons by binding to IGF1R, making it a potential target for neuropathic pain treatment.

Advances in the role of membrane-bound transcription factors in carcinogenesis and therapy.

Protein shuttling between the cytoplasm and nucleus is a unique phenomenon in eukaryotic organisms, integral to various cellular functions. Membrane-bound transcription factors (MTFs), a specialized class of nucleocytoplasmic shuttling proteins, are anchored to the cell membrane and enter the nucleus upon ligand binding to exert their transcriptional regulatory functions. MTFs are crucial in cellular signal transduction, and aberrant nucleocytoplasmic shuttling of MTFs is closely associated with tumor initiation, progression, and resistance to anticancer therapies. Studies have demonstrated that MTFs, such as human epidermal growth factor receptor (HER), fibroblast growth factor receptor (FGFR), β-catenin, Notch, insulin-like growth factor 1 receptor (IGF-1R), and insulin receptor (IR), play critical roles in tumorigenesis and cancer progression. Targeted therapies developed against HERs and FGFRs, among these MTFs, have yielded significant success in cancer treatment. However, the development of drug resistance remains a major challenge. As research on MTFs progress, it is anticipated that additional MTF-targeted therapies will be developed to enhance cancer treatment. In this review, we summarized recent advancements in the study of MTFs and their roles in carcinogenesis and therapy, aiming to provide valuable insights into the potential of targeting MTF pathways for the reseach of therapeutic strategies.

Spontaneous Dimerization and Distinct Packing Modes of Transmembrane Domains in Receptor Tyrosine Kinases.

The insulin receptor (IR) and the insulin-like growth factor-1 receptor (IGF1R) are homodimeric transmembrane glycoproteins that transduce signals across the membrane on binding of extracellular peptide ligands. The structures of IR/IGF1R fragments in apo and liganded states have revealed that the extracellular subunits of these receptors adopt Λ-shaped configurations to which are connected the intracellular tyrosine kinase (TK) domains. The binding of peptide ligands induces structural transitions in the extracellular subunits leading to potential dimerization of transmembrane domains (TMDs) and autophosphorylation in TKs. However, the activation mechanisms of IR/IGF1R, especially the role of TMDs in coordinating signal-inducing structural transitions, remain poorly understood, in part due to the lack of structures of full-length receptors in apo or liganded states. While atomistic simulations of IR/IGF1R TMDs showed that these domains can dimerize in single component membranes, spontaneous unbiased dimerization in a plasma membrane having a physiologically representative lipid composition has not been observed. We address this limitation by employing coarse-grained (CG) molecular dynamics simulations to probe the dimerization propensity of IR/IGF1R TMDs. We observed that TMDs in both receptors spontaneously dimerized independent of their initial orientations in their dissociated states, signifying their natural propensity for dimerization. In the dimeric state, IR TMDs predominantly adopted X-shaped configurations with asymmetric helical packing and significant tilt relative to the membrane normal, while IGF1R TMDs adopted symmetric V-shaped or parallel configurations with either no tilt or a small tilt relative to the membrane normal. Our results suggest that IR/IGF1R TMDs spontaneously dimerize and adopt distinct dimerized configurations.

Evaluation of alpha Klotho and fibroblast growth factor-23 levels in Iraqi patients with Graves’ disease

Background & Objective: Graves’ disease (GD) is an autoimmune condition that targets the thyroid gland, resulting in excessive stimulation and synthesis of thyroid hormones. Excessive synthesis of these hormones can lead to symptoms such as loss of body weight, accelerated heart rate, irritability, reduced tolerance to heat, and excessive perspiration. Alpha-Klotho (KL), a protein crucial for physiological processes, is also involved in GD. The defective immunological condition of GD patients may increase Klotho expression, and the enhanced expression of fibroblast growth factor-23 (FGF23) in GD may be linked to the disease pathophysiology. We investigated serum levels of KL and FGF23 in Iraqi patients with Graves’ disease, analyzing correlations with clinical status and evaluating their potential as biomarkers for disease activity. Methodology: We conducted this cross-sectional study at The National Diabetes Center, Mustansiriyah University, between December 2022 and April 2023. The study involved 103 patients diagnosed with GD, and 103 patients, aged 21-70 y, as a control group. Patients with multinodular goiter, single thyroid nodules, thyroiditis, pregnant women, and those on medications or oral contraceptives, were excluded. Result: clinical significance of FGF23 and Klotho (KL) levels in patients with Graves’ disease (GD) compared to a control group. Results indicate that the median of KL levels are significantly higher in GD patients (KL = 6.31) compared to the control group (KL = 2.40), with a highly significant difference (P < 0.001). In contrast, differences in median of FGF23 levels between GD patients (149) and controls (86.05) were not statistically significant (P = 0.07). Furthermore, KL levels were significantly higher in hyperthyroid patients compared to other thyroid statuses (P = 0.023), while FGF23 levels did not significantly differ across thyroid statuses (P = 0.255). Additionally, the study found a strong correlation between TRAb levels and both KL (r = 0.291, P < 0.001) and FGF23 (r = 0.211, P = 0.003), and between KL and FGF23 directly (r = 0.412, P < 0.001). These findings suggest that while KL may be a significant biomarker in GD, FGF23 relevance appears limited in this context. Conclusion: In Graves’ Disease patients have significantly higher levels of KL and FGF23 compared to controls, suggesting a distinct pathophysiological role for these biomarkers in mineral homeostasis and thyroid hormone regulation. Abbreviations: AITD - Autoimmune thyroid diseases; KL - Alpha-Klotho; FGF23 - fibroblast growth factor-23; GD - Graves’ disease; HT - Hashimoto's thyroiditis; IGF-1R - Insulin-like Growth Factor-1 Receptor; Keywords: Autoimmune Thyroid Disorders, Hyperthyroidism, Graves’ disease, Alpha-Klotho Citation: Rashid MF, Alammar HAJ, Rahmah AM. Evaluation of alpha Klotho and fibroblast growth factor-23 levels in Iraqi patients with Graves’ disease. Anaesth. pain intensive care 2024;28(5):836−841. DOI: 10.35975/apic.v28i5.2567 Received: June 16, 2024; Reviewed: July 07, 2024; Accepted: July 18, 2024

Interactions between androgen and IGF1 axes in prostate tumorigenesis.

Androgen signalling through the androgen receptor (AR)is essential for prostate tumorigenesis. However, androgen signalling pathways also interact with other growth factor-mediated signalling pathways to regulate the prostatic cell cycle, differentiation, apoptosis and proliferation in the initiation and progression of prostate cancer. Insulin-like growth factor 1 (IGF1) is one of the most prominent growth factors in prostate tumorigenesis. Clinical and experimental evidence has demonstrated that IGF1 signalling supports both androgen-dependent and androgen-independent prostate tumorigenesis, suggesting that improved understanding of the interactions between the IGF1 and androgen axes might aid the development of new therapeutic strategies. Available data have shown a dynamic role of androgen-AR signalling in the activation of IGF1-signalling pathways by augmenting transcription of the IGF1 receptor in prostatic basal epithelial cells and by increasing IGF1 secretion through the suppression of IGF-binding protein 3 expression in prostatic stromal cells. In turn, IGF1 stimulates Wnt-β-catenin signalling in prostatic basal progenitors to promote prostatic oncogenic transformation and prostate cancer development. These findings highlight the cooperative, autocrine and paracrine interactions that underlie the oncogenic effects of androgens and IGF1 and open up new opportunities for therapeutic targeting.

6509 IGF-1 receptor and insulin receptor in LepRb neurons coordinates body growth, reproduction, and metabolism

Abstract Disclosure: M. Wang: None. J.W. Hill: None. Growth and reproduction are tightly linked. Growth hormone (GH) deficiency results in a profound suppression of postnatal growth accompanied by severely delayed puberty and reproductive senescence, while GH excess is correlated with the reverse. The specific mechanism underlying this delay is undefined. Although leptin receptor (LepRb)-expressing neurons are known to link body growth and reproduction, the role of insulin-like growth factor 1 receptor (IGF1R) signaling in LepRb neuron function is unknown. Previous studies have shown that IGF-1 and insulin can bind to each other’s receptor, permitting IGF-1 signaling in the absence of IGF1R. Therefore, we created mice lacking IGF1R exclusively in LepRb neurons (IGF1RLepRb mice) and mice simultaneously lacking IGF1R and IR in LepRb neurons (IGF1R/IRLepRb mice) to test if IGF1R and insulin receptor (IR) cooperatively regulate metabolic and reproductive functions. IGF1RLepRb and IGF1R/IRLepRb mice displayed delayed onset of puberty and impaired fertility in both sexes, which suggested that both IGF1R and IR in LepRb neurons are required for normal reproduction. Additionally, we found transient growth retardation in IGF1RLepRb and IGF1R/IRLepRb mice. Loss of IGF1R in LepRb neurons led to lower serum IGF-1 and GH levels in male mice and impaired trabecular and cortical bone development in mice of both sexes. Only transient and mild changes were noticed in the body weight. However, we found IGF1R and IR in LepRb neurons jointly regulate body mass composition, energy homeostasis and glucose homeostasis, as shown by elevated fat mass composition, low energy expenditure and low physical activity in IGF1R/IRLepRb mice. Taken together, these studies identify the unique and cooperative role of LepRb IGF1R and IRs in the regulation of body growth, reproduction, and metabolism. Presentation: 6/3/2024

12422 Linsitinib Inhibits Proliferation And Induces Apoptosis Of IGF-1R And TSH-R Expressing Cells

Abstract Disclosure: M. Luffy: None. A. Ganz: None. J. Ropertz: None. R. Douglas: Employee; Self; Sling Therapeutics. R. Zeidan: Employee; Self; Sling Therapeutics. J. Kent: Employee; Self; Sling Therapeutics. J. Wolf: None. G.J. Kahaly: Grant Recipient; Self; Sling Therapeutics. Background: The insulin-like growth factor 1 receptor (IGF-1R) and the thyrotropin receptor (TSH-R) are expressed on orbital target cells and thyrocytes. Targeting these pathways effectively improves thyroid eye disease (TED). Methods: The inhibitory effect of Linsitinib, a small molecule targeting the IGF-1R (Sling Therapeutics, Ann Arbor, MI, USA), on cell proliferation was investigated in an IGF-1R expressing cell line, NCI-H295R (ATCC, Manassas, VA, USA) and a Chinese Hamster Ovary (CHO) cell line overexpressing the TSH-R (QuidelOrtho, San Diego, CA, USA). An IGF-1R antagonist, Teprotumumab (BioVision, Milpitas, CA, USA) served as control. Both cell lines were plated in a 96-well format and treated with four concentrations of both compounds for 24 hours. After addition of tetrazolium, absorbance was measured (GloMax luminometer, Promega, Madison, WI, USA). Furthermore, the half-maximal inhibitory concentration (IC50) of TSH-R-Ab induced stimulation (stimulatory monoclonal antibody, mAb, M22, RSR, Cardiff, UK) of the TSH-R cell line was evaluated with a cell-based bioassay for blocking TSH-R-Ab (Thyretain TBI, QuidelOrtho). Cells were treated with ten rising concentrations of either Linsitinib, Linsitinib + Metformin, Teprotumumab, or a blocking TSH-R mAb (K1-70, RSR). The Kruskal-Wallis and/or the two-tailed Mann-Whitney tests were used for statistical comparisons. Results: Linsitinib strongly inhibited the proliferation of both cell lines at the following concentrations: 31,612.5 ng/mL (-78%, P=0.0031, IGF-1R cell line and -75%, P=0.0059, TSH-R cell line), as well as at 63,225 ng/mL (-73%, P=0.0073, IGF-1R cell line and -73%, P=0.0108, TSH-R cell line). Linsitinib induced morphologically confirmed apoptosis of both cell lines across all tested concentrations (Luna-FL cell counter, Logos Biosystems, Annandale, VA, USA). Compared to Teprotumumab, Linsitinib inhibited markedly more the proliferation of the IGF-1R cell line at all concentrations (Linsitinib versus Teprotumumab, P=0.0286). Teprotumumab inhibition ranged from -21 to -31% of the IGF-1R cell line across all concentrations, while it was significant only at 15,806.25 ng/mL with the TSH-R cell line (-15%, P=0.0396). In addition, in the TSH-R-Ab blocking bioassay, all tested compounds demonstrated strong inhibition across all ten dilutions (100%). The IC50 of Linsitinib was lower than Teprotumumab (147.1 ng/mL versus 160.6 ng/mL). Combining Metformin to Linsitinib did not further lower the IC50. Not surprisingly, the TSH-R blocking mAb K1-70 had the lowest IC50 of 20.57 ng/mL. Conclusions: Linsitinib effectively induces apoptosis and inhibits proliferation of both IGF-1R and TSH-R expressing target cells, also displaying a lower IC50 in the blocking TSH-R-Ab bioassay compared to Teprotumumab, hence demonstrating its therapeutic potential for TED. Presentation: 6/2/2024