New Insights from IGF-IR Stimulating Activity Analyses: Pathological Considerations

Insulin-like growth factor family and prostate cancer: new insights and emerging opportunities

Prostate cancer is the second most commonly diagnosed cancer in men. The mammalian insulin-like growth factor (IGF) family is made up of three ligands (IGF-I, IGF-II, and insulin), three receptors (IGF-I receptor (IGF-1R), insulin receptor (IR), and IGF-II receptor (IGF-2R)), and six IGF-binding proteins (IGFBPs). IGF-I and IGF-II were identified as potent mitogens and were previously associated with an increased risk of cancer development including prostate cancer. Several reports showed controversy about the expression of the IGF family and their connection to prostate cancer risk due to the high degree of heterogeneity among prostate tumors, sampling bias, and evaluation techniques. Despite that, it is clear that several IGF family members play a role in prostate cancer development, metastasis, and androgen-independent progression. In this review, we aim to expand our understanding of prostate tumorigenesis and regulation through the IGF system. Further understanding of the role of IGF signaling in PCa shows promise and needs to be considered in the context of a comprehensive treatment strategy.

GRK5 is required for adipocyte differentiation through ERK activation

Previous studies have identified G protein-coupled receptor (GPCR) kinase 5 (GRK5) as a genetic factor contributing to obesity pathogenesis, but the underlying mechanism remains unclear. We demonstrate here that Grk5 mRNA is more abundant in stromal vascular fractions of mouse white adipose tissue, the fraction that contains adipose progenitor cells, or committed pre-adipocytes, than in adipocyte fractions. Thus, we generated a GRK5 knockout (KO) 3T3-L1 pre-adipocyte to further investigate the mechanistic role of GRK5 in regulating adipocyte differentiation. During adipogenic stimulation, GRK5 KO pre-adipocytes were unable to achieve mature adipocyte morphology and lipid accumulation compared to wildtype cells coupled with suppressed adipogenic and lipogenic gene expression. Beside GPCR signaling, RNA sequencing and pathway analysis identified insulin-like growth factor 1 (IGF-1) signaling to be one of the top 5 significantly dysregulated pathways in GRK5 KO cells. GRK5 KO cells also displayed decreased insulin-stimulated ERK phosphorylation, a downstream target of insulin-stimulated IGF-1 receptor activation, suggesting that GRK5 acts through this critical pathway to impact 3T3-L1 adipocyte differentiation. To find a more translational approach, we identified a new small molecule GRK5 inhibitor that was able to reduce 3T3-L1 adipogenesis. These data suggest that GRK5 is required for adipocyte differentiation through IGF-1 receptor/ERK activation and may be a promising translational target for obesity.

Topical Insulin for Ocular Surface Disease

Background: Insulin and insulin-like growth factor (IGF)-1 receptors are present in ocular tissues such as corneal epithelium, keratocytes, and conjunctival cells. Insulin plays a crucial role in the growth, differentiation, and proliferation of corneal epithelial cells, as well as in wound healing processes in various tissues. Purpose: This review explores the potential role of topical insulin in the treatment of ocular surface diseases. Specifically, it examines its impact on corneal nerve regeneration, sub-basal plexus corneal nerves, and its application in conditions like corneal epithelial defects, dry eye disease, and diabetic keratopathy. Methods: The review analyzes studies conducted over the past decade that have investigated the use of topical insulin in ocular surface diseases. It focuses on indications, drug preparation methods, side effects, efficacy outcomes, and variations in insulin concentrations and dosages used. Results: While off-label use of topical insulin has shown promising results in refractory corneal epithelial defects, its efficacy in dry eye disease is yet to be demonstrated. Variations in concentrations, dilutions, and dosing guidelines have been reported. However, limited data on ocular penetration, ocular toxicity, and systemic side effects pose challenges to its widespread utility. Conclusion: This review synthesizes findings from ocular investigations on topical insulin to assess its potential applicability in treating ocular surface and corneal diseases. By highlighting indications, preparation methods, side effects, and efficacy outcomes, it aims to provide insights into the current status and future prospects of using topical insulin in ophthalmic practice.

Transcriptomic profiling of Polycystic Kidney Disease identifies paracrine factors in the early cyst microenvironment

Initial cysts that are formed upon Pkd1 loss in mice impose persistent stress on surrounding tissue and trigger a cystic snowball effect, in which local aberrant PKD-related signaling increases the likelihood of new cyst formation, ultimately leading to accelerated disease progression. Although many pathways have been associated with PKD progression, the knowledge of early changes near initial cysts is limited. To perform an unbiased analysis of transcriptomic alterations in the cyst microenvironment, microdomains were collected from kidney sections of iKsp-Pkd1del mice with scattered Pkd1-deletion using Laser Capture Microdissection. These microdomains were defined as F4/80-low cystic, representing early alterations in the cyst microenvironment, F4/80-high cystic, with more advanced alterations, or non-cystic. RNA sequencing and differential gene expression analysis revealed 953 and 8088 dysregulated genes in the F4/80-low and F4/80-high cyst microenvironment, respectively, when compared to non-cystic microdomains. In the early cyst microenvironment, several injury-repair, growth, and tissue remodeling-related pathways were activated, accompanied by mild metabolic changes. In the more advanced F4/80-high microdomains, these pathways were potentiated and the metabolism was highly dysregulated. Upstream regulator analysis revealed a series of paracrine factors with increased activity in the early cyst microenvironment, including TNFSF12 and OSM. In line with the upstream regulator analysis, TWEAK and Oncostatin-M promoted cell proliferation and inflammatory gene expression in renal epithelial cells and fibroblasts in vitro. Collectively, our data provide an overview of molecular alterations that specifically occur in the cyst microenvironment and identify paracrine factors that may mediate early and advanced alterations in the cyst microenvironment.

Enhancing Immunotherapy in Ovarian Cancer: The Emerging Role of Metformin and Statins

Ovarian cancer metastization is accompanied by the development of malignant ascites, which are associated with poor prognosis. The acellular fraction of this ascitic fluid contains tumor-promoting soluble factors, bioactive lipids, cytokines, and extracellular vesicles, all of which communicate with the tumor cells within this peritoneal fluid. Metabolomic profiling of ovarian cancer ascites has revealed significant differences in the pathways of fatty acids, cholesterol, glucose, and insulin. The proteins involved in these pathways promote tumor growth, resistance to chemotherapy, and immune evasion. Unveiling the key role of this liquid tumor microenvironment is crucial for discovering more efficient treatment options. This review focuses on the cholesterol and insulin pathways in ovarian cancer, identifying statins and metformin as viable treatment options when combined with standard chemotherapy. These findings are supported by clinical trials showing improved overall survival with these combinations. Additionally, statins and metformin are associated with the reversal of T-cell exhaustion, positioning these drugs as potential combinatory strategies to improve immunotherapy outcomes in ovarian cancer patients.

Insulin-like growth factor (IGF) performance in ovarian function and applications in reproductive biotechnologies

The role of the insulin-like growth factor (IGF) system has attracted close attention. The activity of IGF binding proteins (IGFBPs) within the ovary has not been fully elucidated to date. These proteins bind to IGF with an equal, or greater, affinity than to the IGF1 receptor, thus being in the main position to regulate IGF signalling, in addition to extending the half-life of IGFs within the bloodstream and promoting IGF storage in specific tissue niches. IGF1 has an important part in cell proliferation, differentiation and apoptosis. Considering the importance of IGFs in oocyte maturation, this review sought to elucidate aspects including: IGF production mechanisms; constituent members of their family and their respective functions; the role that these factors play during folliculogenesis, together with their functions during oocyte maturation and apoptosis, and their performance during luteal development. This review also explores the role of IGFs in biotechnological applications, focusing specifically on animal genetic gain.

IGF-1R down regulates the sensitivity of hepatocellular carcinoma to sorafenib through the PI3K / akt and RAS / raf / ERK signaling pathways

BACKGROUND

Insulin-like growth factor-1 receptor (IGF-1R) promotes cell proliferation and migration and inhibitsapoptosis, all of which can contribute to the development of cancers.

METHOD

This study investigated the effect and mechanism of IGF-1R in mediating the desensitization of hepatocellular carcinoma (HCC) to sorafenib.

RESULTS

IGF-1R, highly expressed in the HCC cell lines SK-Hep1 and HepG2, promotes cell proliferation, migration, and anti-apoptosis through PI3K / Akt and RAS / Raf / ERK signaling pathways, resulting in HCC resistance to sorafenib. Knockdown of IGF-1R by RNA interference decreased proliferation and cell migration and upregulation of sorafenib-induced apoptosis of HCC cells. In vivo studies demonstrated that IGF-1R knockdown inhibited the growth of SK-Hep1 xenografts.

CONCLUSION

These data are evidence that IGF-1R participates in regulating the survival and cell growth of HCC through the PI3K / Akt and RAS / Raf / ERK signaling pathways. Intervention in the expression of IGF-1R may increase the inhibitory effect of sorafenib on HCC.

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

CONTEXT

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).

OBJECTIVE

To investigate the role of TSHR/IGF1R crosstalk in teprotumumab treatment of TED.

DESIGN

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.

RESULTS

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.

CONCLUSION

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.

Survival Risk Analysis of Small Cell Lung Cancer Patients with Pre-Existing Type 2 Diabetes Mellitus: A Single-Center Retrospective Cohort Study

Purpose

We aimed to investigate the clinicopathological characteristics and survival risk factors in small cell lung cancer (SCLC) patients with preexisting type 2 diabetes mellitus (preDM).

Patients and Methods

All patients with SCLC admitted to our hospital between January 2013 and August 2018 were followed up until August 2020 and retrospectively analyzed. Clinical characteristics of SCLC patients with and without preDM were extracted. Cox proportional hazards models were conducted to identify potential independent prognostic factors.

Results

Of 628 eligible individuals, 88 individuals had preDM. preDM was independently significantly associated with distant metastasis in all SCLC patients (p =0.016, OR=1.80, 95% CI 1.11–2.91), while preDM did not affect the outcome of SCLC patients (p=0.803, HR=1.04, 95% CI 0.79–1.36) by multivariate analysis. In the preDM group, the median overall survival (OS) was shorter in the insulin group than in the non insulin group (13.93 months versus 21.77 months, p=0.024). Multivariate analysis identified that insulin treatment was an independent unfavorable factor associated with OS (p =0.009, HR=2.10, 95% CI 1.19–3.64). In addition, poorer performance status (PS) and liver metastasis were also independent unfavorable prognostic factors (all p<0.01), while thoracic therapy significantly improved OS and decreased mortality risk in diabetic patients with SCLC (p<0.05).

Conclusion

preDM may promote distant metastasis of SCLC while it is insulin therapy and not preDM which adversely affects the prognosis of SCLC patients. These findings indicate that enhancing blood glucose control and reducing insulin analog use may be essential to the improvement of the long-term survival of the diabetic population with SCLC.

Biglycan Interacts with Type I Insulin-like Receptor (IGF-IR) Signaling Pathway to Regulate Osteosarcoma Cell Growth and Response to Chemotherapy

Simple Summary

Osteosarcoma (OS) is an aggressive, primary bone cancer. OS cells produce altered osteoid whose components participate in signaling correlated to the development of this cancer. Biglycan (BGN), a proteoglycan, is correlated to aggressive OS type and resistance to chemotherapy. A constitutive signaling of insulin-like growth factor receptor I (IGF-IR) signaling in sarcoma progression was established. We showed that biglycan binds IGF-IR resulting in prolonged IGF-IR activation, nuclear translocation, and growth response of the poorly-differentiated MG63 cells correlated to increased aggressiveness markers expression and enhanced chemoresistance. This mechanism is not valid in moderately and well-differentiated, biglycan non-expressing U-2OS and Saos-2 OS cells.

Abstract

Osteosarcoma (OS) is a mesenchymally derived, aggressive bone cancer. OS cells produce an aberrant nonmineralized or partly mineralized extracellular matrix (ECM) whose components participate in signaling pathways connected to specific pathogenic phenotypes of this bone cancer. The expression of biglycan (BGN), a secreted small leucine-rich proteoglycan (SLRP), is correlated to aggressive OS phenotype and resistance to chemotherapy. A constitutive signaling of IGF-IR signaling input in sarcoma progression has been established. Here, we show that biglycan activates the IGF-IR signaling pathway to promote MG63 biglycan-secreting OS cell growth by forming a complex with the receptor. Computational models of IGF-IR and biglycan docking suggest that biglycan binds IGF-IR dimer via its concave surface. Our binding free energy calculations indicate the formation of a stable complex. Biglycan binding results in prolonged IGF-IR activation leading to protracted IGF-IR-dependent cell growth response of the poorly-differentiated MG63 cells. Moreover, biglycan facilitates the internalization (p ≤ 0.01, p ≤ 0.001) and sumoylation-enhanced nuclear translocation of IGF-IR (p ≤ 0.05) and its DNA binding in MG63 cells (p ≤ 0.001). The tyrosine kinase activity of the receptor mediates this mechanism. Furthermore, biglycan downregulates the expression of the tumor-suppressor gene, PTEN (p ≤ 0.01), and increases the expression of endothelial–mesenchymal transition (EMT) and aggressiveness markers vimentin (p ≤ 0.01) and fibronectin (p ≤ 0.01) in MG63 cells. Interestingly, this mechanism is not valid in moderately and well-differentiated, biglycan non-expressing U-2OS and Saos-2 OS cells. Furthermore, biglycan exhibits protective effects against the chemotherapeutic drug, doxorubicin, in MG63 OS cells (p ≤ 0.01). In conclusion, these data indicate a potential direct and adjunct therapeutical role of biglycan in osteosarcoma.

IGF Signaling in Intervertebral Disc Health and Disease

Low back pain (LBP) is a common musculoskeletal symptom, which brings a lot of pain and economic loss to patients. One of the most common causes of LBP is intervertebral disc degeneration (IVDD). However, pathogenesis is still debated, and therapeutic options are limited. Insulin-like growth factor (IGF) signaling pathways play an important role in regulating different cell processes, including proliferation, differentiation, migration, or cell death, which are critical to the homeostasis of tissues and organs. The IGF signaling is crucial in the occurrence and progression of IVDD. The activation of IGF signaling retards IVDD by increasing cell proliferation, promoting extracellular matrix (ECM) synthesis, inhibiting ECM decomposition, and preventing apoptosis and senescence of disc cells. However, abnormal activation of IGF signaling may promote the process of IVDD. IGF signaling is currently considered to have a promising treatment prospect for IVDD. An in-depth understanding of the role of IGF signaling in IVDD may help find a novel approach for IVDD treatment.

IGF1R is a mediator of sex-specific metabolism in mice: Effects of age and high-fat diet

OBJECTIVE

We aimed to investigate the short and long-term metabolic consequences of IGF1R systemic gene deficiency in mice.

METHODS

UBC-CreERT2, Igf1r^fl/fl mutant mice were used to suppress IGF1R signaling in adult tissues by inducing postnatal generalized Igf1r deletion with tamoxifen. Animals were analyzed at two different ages: i) 13-weeks old young mice, and ii) 12-months old middle-aged mice. In addition, the effects of 10 weeks-long high-fat diet (HFD) were investigated in middle-aged mice.

RESULTS

Young IGF1R-deficient mice were insulin-resistant, with high IGF1, growth hormone (GH) and IGFBP3, as well as low IGFBP2 circulating levels. Males also presented increased triglycerides in liver. In contrast, middle-aged mice did not clearly show all of these alterations, suggesting possible compensatory effects. Middle-aged IGF1R-deficient male mice were able to counteract the negative effects induced by aging and HFD in adiposity, inflammation and glucose metabolism. A metabolic sexual dimorphism dependent on IGF1R was observed, especially in middle-aged mice.

CONCLUSIONS

These results demonstrate that IGF1R is involved in metabolic homeostasis, with effects modulated by diet-induced obesity and aging in a sex dependent manner. Thus, IGF1R deficiency in mice is proposed as a useful tool to understand metabolic alterations observed in patients with IGF1R gene deletions.

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 in vivo 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 in vitro. 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.

Cabozantinib Is Effective in Melanoma Brain Metastasis Cell Lines and Affects Key Signaling Pathways

Melanomas have a high potential to metastasize to the brain. Recent advances in targeted therapies and immunotherapies have changed the therapeutical landscape of extracranial melanomas. However, few patients with melanoma brain metastasis (MBM) respond effectively to these treatments and new therapeutic strategies are needed. Cabozantinib is a receptor tyrosine kinase (RTK) inhibitor, already approved for the treatment of non-skin-related cancers. The drug targets several of the proteins that are known to be dysregulated in melanomas. The anti-tumor activity of cabozantinib was investigated using three human MBM cell lines. Cabozantinib treatment decreased the viability of all cell lines both when grown in monolayer cultures and as tumor spheroids. The in vitro cell migration was also inhibited and apoptosis was induced by cabozantinib. The phosphorylated RTKs p-PDGF-Rα, p-IGF-1R, p-MERTK and p-DDR1 were found to be downregulated in the p-RTK array of the MBM cells after cabozantinib treatment. Western blot validated these results and showed that cabozantinib treatment inhibited p-Akt and p-MEK 1/2. Further investigations are warranted to elucidate the therapeutic potential of cabozantinib for patients with MBM.

Biological Aspects of Selected Myokines in Skeletal Muscle: Focus on Aging

In the last decade, clear evidence has emerged that the cellular components of skeletal muscle are important sites for the release of proteins and peptides called "myokines", suggesting that skeletal muscle plays the role of a secretory organ. After their secretion by muscles, these factors serve many biological functions, including the exertion of complex autocrine, paracrine and/or endocrine effects. In sum, myokines affect complex multi-organ processes, such as skeletal muscle trophism, metabolism, angiogenesis and immunological response to different physiological (physical activity, aging, etc.) or pathological states (cachexia, dysmetabolic conditions, chronic inflammation, etc.). The aim of this review is to describe in detail a number of myokines that are, to varying degrees, involved in skeletal muscle aging processes and belong to the group of proteins present in the functional environment surrounding the muscle cell known as the "Niche". The particular myokines described are those that, acting both from within the cell and in an autocrine manner, have a defined relationship with the modulation of oxidative stress in muscle cells (mature or stem) involved in the regulatory (metabolic or regenerative) processes of muscle aging. Myostatin, IGF-1, NGF, S100 and irisin are examples of specific myokines that have peculiar features in their mechanisms of action. In particular, the potential role of one of the most recently characterized myokines-irisin, directly linked to an active lifestyle-in reducing if not reversing senescence-induced oxidative damage is discussed in terms of its possible application as an agent able to counteract the deleterious effects of muscle aging.

Trop2 binding IGF2R induces gefitinib resistance in NSCLC by remodeling the tumor microenvironment

Gefitinib has shown good efficacy in treating recurrent or advanced non-small cell lung cancer (NSCLC), but the drug resistance remains a clinical challenge in medical oncology. In addition, the complex interaction between tumor cells and heterogeneous stromal cells in the adjacent tumor microenvironment (TME) is also an important contributor to drug resistance. So, it is very necessary to detect the related target genes before and after gefitinib treatment dynamically. In this study, the relationship between Trop2 and gefitinib resistance in NSCLC was investigated, and the underlying mechanism was explored. Results showed that Trop2 was associated with EGFR gene mutation and drug resistance in clinical tissues. Trop2 was confirmed to induce gefitinib resistance in NSCLC, and Trop2 binding IGF2R promoted the IGF2-IGF1R-Akt axis to enhance gefitinib resistance and remodeling the TME in NSCLC. Notably, silencing of Trop2 in cancer cells combined with IGF1R inhibitor significantly decreased the proliferation of tumor cells and reshaped the NSCLC TME in vivo and in vitro, including the recruitment of macrophages. These findings deepened the understanding of the function of Trop2 and the involved mechanisms of gefitinib resistance, and may provide new molecular targets for NSCLC with gefitinib resistance.

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

The Role of IGF/IGF-IR-Signaling and Extracellular Matrix Effectors in Bone Sarcoma Pathogenesis

Simple Summary

Bone sarcomas are mesenchymal origin tumors. Bone sarcoma patients show a variable response or do not respond to chemotherapy. Notably, improving efficient chemotherapy approaches, dealing with chemoresistance, and preventing metastasis pose unmet challenges in sarcoma therapy. Insulin-like growth factors 1 and 2 (IGF-1 and -2) and their respective receptors are a multifactorial system that significantly contributes to bone sarcoma pathogenesis. Most clinical trials aiming at the IGF pathway have had limited success. Developing combinatorial strategies to enhance antitumor responses and better classify the patients that could best benefit from IGF-axis targeting therapies is in order. A plausible approach for developing a combinatorial strategy is to focus on the tumor microenvironment (TME) and processes executed therein. Herewith, we will discuss how the interplay between IGF-signaling and the TME constituents affects bone sarcomas’ basal functions and their response to therapy. Potential direct and adjunct therapeutical implications of the extracellular matrix (ECM) effectors will also be summarized.

Abstract

Bone sarcomas, mesenchymal origin tumors, represent a substantial group of varying neoplasms of a distinct entity. Bone sarcoma patients show a limited response or do not respond to chemotherapy. Notably, developing efficient chemotherapy approaches, dealing with chemoresistance, and preventing metastasis pose unmet challenges in sarcoma therapy. Insulin-like growth factors 1 and 2 (IGF-1 and -2) and their respective receptors are a multifactorial system that significantly contributes to bone sarcoma pathogenesis. Whereas failures have been registered in creating novel targeted therapeutics aiming at the IGF pathway, new agent development should continue, evaluating combinatorial strategies for enhancing antitumor responses and better classifying the patients that could best benefit from these therapies. A plausible approach for developing a combinatorial strategy is to focus on the tumor microenvironment (TME) and processes executed therein. Herewith, we will discuss how the interplay between IGF-signaling and the TME constituents affects sarcomas’ basal functions and their response to therapy. This review highlights key studies focusing on IGF signaling in bone sarcomas, specifically studies underscoring novel properties that make this system an attractive therapeutic target and identifies new relationships that may be exploited. Potential direct and adjunct therapeutical implications of the extracellular matrix (ECM) effectors will also be summarized.

The Role of Nuclear Insulin and IGF1 Receptors in Metabolism and Cancer

Insulin (InsR) and insulin-like growth factor-1 (IGF1R) receptors mediate the metabolic and growth-promoting actions of insulin and IGF1/IGF2, respectively. Evidence accumulated in recent years indicates that, in addition to their typical cell-surface localization pattern and ligand-activated mechanism of action, InsR and IGF1R are present in the cell nucleus of both normal and transformed cells. Nuclear translocation seems to involve interaction with a small, ubiquitin-like modifier protein (SUMO-1), although this modification is not always a prerequisite. Nuclear InsR and IGF1R exhibit a number of biological activities that classically fit within the definition of transcription factors. These nuclear activities include, among others, sequence-specific DNA binding and transcriptional control. Of particular interest, nuclear IGF1R was capable of binding and stimulating its cognate gene promoter. The physiological relevance of this autoregulatory mechanism needs to be further investigated. In addition to its nuclear localization, studies have identified IGF1R in the Golgi apparatus, and this particular distribution correlated with a migratory phenotype. In summary, the newly described roles of InsR and IGF1R as gene regulators, in concert with their atypical pattern of subcellular distribution, add a further layer of complexity to traditional models of cell signaling. Furthermore, and in view of the emerging role of IGF1R as a potential therapeutic target, a better understanding of the mechanisms responsible for nuclear IGF1R transport and identification of IGF1R interactors might help optimize target directed therapies in oncology.

Lessons Learned from Targeting IGF-I Receptor in Thyroid-Associated Ophthalmopathy

Complex immunological mechanisms underlie the pathogenesis of thyroid-associated ophthalmopathy (TAO). Historical models of Graves’ disease and TAO have focused almost entirely on autoimmune reactivity directed against the thyrotropin receptor (TSHR). The insulin-like growth factor-I receptor (IGF-IR) has been proposed as a second participating antigen in TAO by virtue of its interactions with IGFs and anti-IGF-IR antibodies generated in Graves’ disease. Furthermore, the IGF-IR forms with TSHR a physical and functional complex which is involved in signaling downstream from both receptors. Inhibition of IGF-IR activity results in attenuation of signaling initiated at either receptor. Based on the aggregate of findings implicating IGF-IR in TAO, the receptor has become an attractive therapeutic target. Recently, teprotumumab, a human monoclonal antibody IGF-IR inhibitor was evaluated in two clinical trials of patients with moderate to severe, active TAO. Those studies revealed that teprotumumab was safe and highly effective in reducing disease activity and severity. Targeting IGF-IR with specific biologic agents may result in a paradigm shift in the therapy of TAO.

Tyrosine phosphorylation-dependent localization of TmaR that controls activity of a major bacterial sugar regulator by polar sequestration

The poles of Escherichia coli cells are emerging as hubs for major sensory systems, but the polar determinants that allocate their components to the pole are largely unknown. Here, we describe the discovery of a previously unannotated protein, TmaR, which localizes to the E. coli cell pole when phosphorylated on a tyrosine residue. TmaR is shown here to control the subcellular localization and activity of the general PTS protein Enzyme I (EI) by binding and polar sequestration of EI, thus regulating sugar uptake and metabolism. Depletion or overexpression of TmaR results in EI release from the pole or enhanced recruitment to the pole, which leads to increasing or decreasing the rate of sugar consumption, respectively. Notably, phosphorylation of TmaR is required to release EI and enable its activity. Like TmaR, the ability of EI to be recruited to the pole depends on phosphorylation of one of its tyrosines. In addition to hyperactivity in sugar consumption, the absence of TmaR also leads to detrimental effects on the ability of cells to survive in mild acidic conditions. Our results suggest that this survival defect, which is sugar- and EI-dependent, reflects the difficulty of cells lacking TmaR to enter stationary phase. Our study identifies TmaR as the first, to our knowledge, E. coli protein reported to localize in a tyrosine-dependent manner and to control the activity of other proteins by their polar sequestration and release.

Insulin-Like Growth Factor Pathway and the Thyroid

The insulin-like growth factor (IGF) pathway comprises two activating ligands (IGF-I and IGF-II), two cell-surface receptors (IGF-IR and IGF-IIR), six IGF binding proteins (IGFBP) and nine IGFBP related proteins. IGF-I and the IGF-IR share substantial structural and functional similarities to those of insulin and its receptor. IGF-I plays important regulatory roles in the development, growth, and function of many human tissues. Its pathway intersects with those mediating the actions of many cytokines, growth factors and hormones. Among these, IGFs impact the thyroid and the hormones that it generates. Further, thyroid hormones and thyrotropin (TSH) can influence the biological effects of growth hormone and IGF-I on target tissues. The consequences of this two-way interplay can be far-reaching on many metabolic and immunologic processes. Specifically, IGF-I supports normal function, volume and hormone synthesis of the thyroid gland. Some of these effects are mediated through enhancement of sensitivity to the actions of TSH while others may be independent of pituitary function. IGF-I also participates in pathological conditions of the thyroid, including benign enlargement and tumorigenesis, such as those occurring in acromegaly. With regard to Graves' disease (GD) and the periocular process frequently associated with it, namely thyroid-associated ophthalmopathy (TAO), IGF-IR has been found overexpressed in orbital connective tissues, T and B cells in GD and TAO. Autoantibodies of the IgG class are generated in patients with GD that bind to IGF-IR and initiate the signaling from the TSHR/IGF-IR physical and functional protein complex. Further, inhibition of IGF-IR with monoclonal antibody inhibitors can attenuate signaling from either TSHR or IGF-IR. Based on those findings, the development of teprotumumab, a β-arrestin biased agonist as a therapeutic has resulted in the first medication approved by the US FDA for the treatment of TAO. Teprotumumab is now in wide clinical use in North America.

Insulin-Like Growth Factors in Development, Cancers and Aging

Since their discovery in the late 1950s, insulin-like growth factors (IGFs) have attracted significant interest in multiple areas of biology and medicine, including endocrinology, pediatrics, growth, metabolism, nutrition, aging, and oncology [...].

Novel peptide derived from IGF-2 displays anti-angiogenic activity in vitro and inhibits retinal angiogenesis in a model of oxygen-induced retinopathy

BACKGROUND

Retinopathy of prematurity (ROP), a major cause of significant visual morbidity and blindness in preterm infants, is closely related to pathological angiogenesis. The aim of the study is to evaluate the effect of a new 12-aa peptide (named peptide CW-703) from human insulin-like growth factor-2, against angiogenesis in ROP.

METHODS

In order to evaluate the inhibitory effect of CW-703 on the proliferation, migration, tube formation and apoptosis of human umbilical vein endothelial cells (ScienCell) in vitro, we used MTS assays, a modified Boyden chamber, Matrigel system and TUNEL assays. Effects in vivo were assayed using chorioallantoic membrane assays and oxygen-induced retinopathy (OIR) models in mice. We also performed eletrophysiological and histologic examinations to evaluate the possible toxicity of the peptide. Real-time PCR, ELISA and western blotting were used to elucidate the mechanism of CW-703.

RESULTS

CW-703 inhibited angiogenesis in vitro by suppressing endothelial cell proliferation, migration and tube formation. CW-703 also prevented angiogenesis in chicken chorioallantoic membrane assays and OIR assays in mice. No evident functional or morphologic abnormalities in neuroretina after CW-703 injection were revealed in electrophysiological tests and histological examinations. Moreover, we elucidated that CW-703 competed for binding to IGF-1R and inhibited angiogenesis by inhibiting IGF-1R/PI3K/AKT activation and downregulating vascular endothelial growth factor expression.

CONCLUSION

The novel peptide CW-703 may act as an effective inhibitor of ocular pathologic angiogenesis, especially in treating ROP.