Role Of Insulin-like Growth Factor-1 Receptor Research Articles

IGF1R acts as a cancer-promoting factor in the tumor microenvironment facilitating lung metastasis implantation and progression

Given the long-term ineffectiveness of current therapies and late-stage diagnoses, lung cancer is a leading cause of malignant diseases. Tumor progression is influenced by cancer cell interactions with the tumor microenvironment (TME). Insulin-like growth factor 1 receptor (IGF1R) was reported to affect the TME; however, the role of IGF1R in lung TME has not been investigated. First, we assessed IGF1R genomic alterations and expression in NSCLC patient tissue samples, as well as IGF1R serum levels. Next, we performed tumor heterotopic transplantation and pulmonary metastases in IGF1R-deficient mice using melanoma and Lewis lung carcinoma (LLC) cells. Herein we report increased amplification and mRNA expression, as well as increased protein expression (IGF1R/p-IGF1R) and IGF1R levels in tumor samples and serum from NSCLC patients, respectively. Moreover, IGF1R deficiency in mice reduced tumor growth, proliferation, inflammation and vascularization, and increased apoptosis after tumor heterotopic transplantation. Following induction of lung metastasis, IGF1R-deficient lungs also demonstrated a reduced tumor burden, and decreased expression of tumor progression markers, p-IGF1R and p-ERK1/2. Additionally, IGF1R-deficient lungs showed increased apoptosis and diminished proliferation, vascularization, EMT and fibrosis, along with attenuated inflammation and immunosuppression. Accordingly, IGF1R deficiency decreased expression of p-IGF1R in blood vessels, fibroblasts, tumor-associated macrophages and FOXP3+ tumor-infiltrating lymphocytes. Our results demonstrate that IGF1R promotes metastatic tumor initiation and progression in lung TME. Furthermore, our research indicates that IGF1R could be a potential biomarker for early prediction of drug response and clinical evolution in NSCLC patients.

SUMO1 modification of IGF-1R combining with SNAI2 inhibited osteogenic differentiation of PDLSCs stimulated by high glucose

BackgroundPeriodontal disease, an oral disease characterized by loss of alveolar bone and progressive teeth loss, is the sixth major complication of diabetes. It is spreading worldwide as it is difficult to be cured. The insulin-like growth factor 1 receptor (IGF-1R) plays an important role in regulating functional impairment associated with diabetes. However, it is unclear whether IGF-1R expression in periodontal tissue is related to alveolar bone destruction in diabetic patients. SUMO modification has been reported in various diseases and is associated with an increasing number of biological processes, but previous studies have not focused on diabetic periodontitis. This study aimed to explore the role of IGF-1R in osteogenic differentiation of periodontal ligament stem cells (PDLSCs) in high glucose and control the multiple downstream damage signal factors.MethodsPDLSCs were isolated and cultured after extraction of impacted teeth from healthy donors or subtractive orthodontic extraction in adolescents. PDLSCs were cultured in the osteogenic medium with different glucose concentrations prepared by medical 5% sterile glucose solution. The effects of different glucose concentrations on the osteogenic differentiation ability of PDLSCs were studied at the genetic and cellular levels by staining assay, Western Blot, RT-PCR, Co-IP and cytofluorescence.ResultsWe found that SNAI2, RUNX2 expression decreased in PDLSCs cultured in high glucose osteogenic medium compared with that in normal glucose osteogenic medium, which were osteogenesis-related marker. In addition, the IGF-1R expression, sumoylation of IGF-1R and osteogenic differentiation in PDLSCs cultured in high glucose osteogenic medium were not consistent with those cultured in normal glucose osteogenic medium. However, osteogenic differentiation of PDLCSs enhanced after adding IGF-1R inhibitors to high glucose osteogenic medium.ConclusionOur data demonstrated that SUMO1 modification of IGF-1R inhibited osteogenic differentiation of PDLSCs by binding to SNAI2 in high glucose environment, a key factor leading to alveolar bone loss in diabetic patients. Thus we could maximize the control of multiple downstream damage signaling factors and bring new hope for alveolar bone regeneration in diabetic patients.

Identification of nucleolar protein NOM1 as a novel nuclear IGF1R-interacting protein

The insulin-like growth factor-1 receptor (IGF1R) mediates the biological actions of both IGF1 and IGF2. In recent years, evidence has accumulated showing that, in addition to its classical cell-surface distribution, IGF1R translocates to cell nucleus via an apparently SUMO-1-dependent mechanism. While the role of IGF1R in nucleus has not yet been settled, available information suggests that the nuclear receptor displays activities usually linked to transcription factors, including DNA binding and transcription regulation. To gain insight into the biological pathways associated with nuclear IGF1R action we conducted a mass spectrometry-based proteomic analysis aimed at identifying interactors of IGF1R in nucleus of both benign and malignant breast cells. The nucleolar NOM1 molecule belongs to a family of proteins that contain the middle domain of eukaryotic initiation factor 4G (MIF4G) and/or interaction module (MA3), and functions in translation, cell growth and proliferation. Using a combination of co-immunoprecipitation and silencing assays we provide evidence of a complex, bi-directional interplay between nuclear IGF1R and nucleolar protein NOM1. Inhibition of nuclear IGF1R translocation by dansylcadaverine reduced NOM1 levels in nuclei of MCF7 cells. On the other hand, IGF1R overexpression enhanced NOM1 levels in the nuclear fraction. Of interest, NOM1 silencing led to a major increase in IGF1R biosynthesis. In summary, results are consistent with a physiologically-relevant interplay between the nuclear IGF1 signaling pathway and nucleolar protein NOM1.

Role of IGF1R(+) MSCs in modulating neuroplasticity via CXCR4 cross-interaction.

To guide the use of human mesenchymal stem cells (MSCs) toward clinical applications, identifying pluripotent-like-markers for selecting MSCs that retain potent self-renewal-ability should be addressed. Here, an insulin-like growth factor 1 receptor (IGF1R)–expressing sub-population in human dental pulp MSCs (hDSCs), displayed multipotent properties. IGF1R expression could be maintained in hDSCs when they were cultured in 2% human cord blood serum (hUCS) in contrast to that in 10% fetal calf serum (FCS). Cytokine array showed that hUCS contained higher amount of several growth factors compared to FCS, including IGF-1 and platelet-derived growth factor (PDGF-BB). These cytokines modulates the signaling events in the hDSCs and potentially enhances engraftment upon transplantation. Specifically, a bidirectional cross-talk between IGF1R/IGF1 and CXCR4/SDF-1α signaling pathways in hDSCs, as revealed by interaction of the two receptors and synergistic activation of both signaling pathways. In rat stroke model, animals receiving IGF1R+ hDSCs transplantation, interaction between IGF1R and CXCR4 was demonstrated to promote neuroplasticity, therefore improving neurological function through increasing glucose metabolic activity, enhancing angiogenesis and anti-inflammatiory effects. Therefore, PDGF in hUCS-culture system contributed to the maintenance of the expression of IGF1R in hDSCs. Furthermore, implantation of IGF1R+ hDSCs exerted enhanced neuroplasticity via integrating inputs from both CXCR4 and IGF1R signaling pathways.

Role of IGF1R in Tubular Remodeling of the Mouse Kidney

Loop diuretics, commonly prescribed to treat hypertension and edema, increase sodium excretion by inhibiting the sodium‐potassium 2 chloride cotransporter (NKCC2) in the thick ascending limb. Chronic furosemide use leads to diuretic resistance in humans, but the molecular mechanisms are largely unknown. We developed a mouse model of chronic furosemide use to explore its effects on sodium transport and tubular remodeling. Mice treated with furosemide for seven days had greater sensitivity for thiazide diuretics with significantly increased levels of sodium‐chloride cotransporter (NCC), demonstrating compensatory sodium reabsorption of the distal nephron. Furosemide‐treated mice also exhibited tubular hyperplasia. After 21 days, mice treated with furosemide vs. vehicle, had persistently‐elevated NCC expression increased kidney‐to‐body weight ratio, increased tubular hypertrophy of distal convoluted tubule and connecting tubular segments, and changes in IGF‐1 signaling. There was no increase in IGF‐1 mRNA expression, but specific increases in IGF binding proteins (IGFBPs) which are known to sequester IGF‐1 in kidney cells, and IGF‐1 receptor. To further explore the role of IGF‐1 in tubular remodeling, we developed an inducible, pan‐tubular IGF‐1 receptor knockout mouse. Interestingly, furosemide‐treated IGF‐1 receptor (IGF1R) knockout mice lacked the increased kidney‐to‐body mass increase ratio seen in wild‐type mice, but they developed comparable hypertrophy in distal nephron segments and higher expression of NCC compared with furosemide‐treated wild‐type mice. These results suggest IGF1R signaling is involved in renal tubular remodeling of more proximal nephron segments and distinct factors control the tubular hypertrophy of the distal nephron beyond an increase in NCC expression.Support or Funding InformationNIH/NIDDK

Deletion of IGF-1 Receptors in Cardiomyocytes Attenuates Cardiac Aging in Male Mice.

IGF-1 receptor (IGF-1R) signaling is implicated in cardiac hypertrophy and longevity. However, the role of IGF-1R in age-related cardiac remodeling is only partially understood. We therefore sought to determine whether the deletion of the IGF-1R in cardiomyocytes might delay the development of aging-associated myocardial pathologies by examining 2-year-old male cardiomyocyte-specific IGF-1R knockout (CIGF1RKO) mice. Aging was associated with the induction of IGF-1R expression in hearts. Cardiomyocytes hypertrophied with age in wild-type (WT) mice. In contrast, the cardiac hypertrophic response associated with aging was blunted in CIGF1RKO mice. Concomitantly, fibrosis was reduced in aged CIGF1RKO compared with aged WT hearts. Expression of proinflammatory cytokines such as IL-1α, IL-1β, IL-6, and receptor activator of nuclear factor-κB ligand was increased in aged WT hearts, but this increase was attenuated in aged CIGF1RKO hearts. Phosphorylation of Akt was increased in aged WT, but not in aged CIGF1RKO, hearts. In cultured cardiomyocytes, IGF-1 induced senescence as demonstrated by increased senescence-associated β-galactosidase staining, and a phosphoinositide 3-kinase inhibitor inhibited this effect. Furthermore, inhibition of phosphoinositide 3-kinase significantly prevented the increase in IL-1α, IL-1β, receptor activator of nuclear factor-κB ligand, and p21 protein expression by IGF-1. These data reveal an essential role for the IGF-1-IGF-1R-Akt pathway in mediating cardiomyocyte senescence.

Abstract 836: Insulin-like growth factor-I receptor (IGF-IR) dowregulation in cisplatin-resistant human ovarian cancer cells

Abstract Introduction: Ovarian cancer is the most lethal of the gynecological malignancies and the 5th leading cause of cancer related deaths amongst women in the US. It is a chemotherapy-sensitive disease, and about 85% of patients respond to first line treatment with platinum-based chemotherapeutic agents. However, 15% of all patients present with primary platinum-resistant disease, and those with recurrent ovarian cancer develop resistance. Resistance to platinum-based drugs is a major obstacle in ovarian cancer treatment, and mechanisms of platinum resistance are not well understood. Insulin-like growth factor-1 receptor (IGF-1R) signaling has not only been implicated in ovarian cancer development, but has also been suggested to mediate platinum-resistance. The IGF-1R has been proposed as a potential molecular target for ovarian cancer, and clinical trials evaluating the use of small molecule kinase inhibitors or humanized monoclonal antibodies against the IGF-1R are currently under way. This study examines the role of IGF-1R in cisplatin resistance in human ovarian carcinoma. Experimental Procedures: Differential gene expression in two pairs of cisplatin-resistant cell lines (SKOV3-CisR and OVCAR-CisR) and their syngeneic cisplatin-sensitive counterpart (SKOV3 and OVCAR5, respectively) was analyzed using the Affymetrix GeneChip Human Genome U133 Plus 2.0 Array. IGF-1R mRNA transcripts and protein levels were verified via qRT-PCR and immunoblotting, respectively. Protein expression levels of IGF-1Rα and IGF-1Rα (immunoblotting) were correlated with cisplatin IC50 (XTT cell viability) in a panel of 12 ovarian cancer cell lines. IGF-1R was overexpressed (stable transfection) in SKOV3-CisR cells and the effect on cisplatin sensitivity evaluated. The effect of short-term cisplatin treatment on IGF-1Rα and IGF-1Rα protein levels was studied in SKOV3 and OVCAR5 cells. Results: Cisplatin-resistant SKOV3-CisR and OVCAR5-CisR cells exhibited 2-3 fold lower levels of IGF-1R mRNA transcripts compared to cisplatin-sensitive SKOV3 and OVCAR5 cells in the DNA microarray and via qRT-PCR. Correspondingly, decreased levels of IGF-1Rα and IGF-1Rα protein were found in immunoblot analyses. IGF-1Rα (r = −0.6118; p = 0.0345) and IGF-1Rα (r = −0.5839; p = 0.0462) protein levels and cisplatin IC50were negatively correlated. IGF-1R overexpression in SKOV3-CisR cells sensitized the cells to cisplatin, from 5 μg/ml (SKOV3-CisR) to 10-12 μg/ml (SKOV3-CisR-IGF-1R). Cisplatin induced a decrease in IGF-1Rα and IGF-1Rα levels after 24 and 48 hours treatment. Conclusions: Cisplatin treatment of ovarian cancer cells results in IGF-1R downregulation, which in turn decreases cisplatin sensitivity. Our results have important implications in the design of IGF-1R targeting strategies in clinical trials for ovarian cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 836. doi:1538-7445.AM2012-836

Role of IGF-1 Receptor in Radiation Response

Insulin-like growth factor 1 receptor (IGF-1R) is a transmembrane receptor tyrosine kinase involved in the development and progression of cancer whose activation strongly promotes cell growth and survival. IGF-1R exerts its main actions through the activation of the mitogen-activated protein kinase and phosphoinositide 3-kinase pathways. In addition to their traditional roles, IGF-1R activation has been associated with increased radioresistance both in vitro and in vivo, although the molecular mechanisms behind this process are still unclear. Recently, IGF-1R has been associated to new partners as major vault proteins, BCL-2, BAX, or Ku70/80, related to radiochemotherapy resistance, regulation of apoptosis, and nonhomologous end-joining DNA repair. Here, we review these novel associations of IGF-1R trying to explain the resistance to radiotherapy mediated by IGF-1R. Finally, we revised the role of new therapies leading to block the receptor to enhance the efficacy of radiation.

Calcium and osteoprotegerin regulate IGF1R expression to inhibit vascular calcification

Osteoprotegerin (OPG) inhibits vascular calcification in vitro, and OPG(-/-) mice develop vascular calcification. Insulin-like growth factor-1 (IGF1) signalling has been implicated in vascular smooth muscle cell (VSMC) survival; however, the role of IGF1-receptor (IGF1R) expression in calcification is unclear. We sought to determine whether the protective effects of OPG in vascular calcification were mediated by IGF1R. Calcium-induced mineralization of VSMCs was blocked in cells expressing the IGF1R and by treatment with OPG. OPG induced IGF1R mRNA, protein, and transcription optimally at 1 ng/mL. Calcium also positively regulated both OPG and IGF1R, and siRNA targeting of OPG inhibited calcium-inducible IGF1R mRNA. Addition of calcium to VSMCs reduced camptothecin-stimulated apoptosis and increased expression of survival genes Bcl2 and nuclear factor-kappa B without altering levels of proliferation. Calcium's induction of IGF1R and OPG was dose and time dependent but was blunted at higher calcium doses. Calcium- and OPG-inducible IGF1R transcription occurred between -446 and -188 bp of the IGF1R promoter, and inducible-IGF1R expression was blocked by specificity protein-1 (Sp1) silencing studies. Furthermore, elevated IGF1R and OPG protein levels were present in calcified atherosclerotic tissue. We have shown for the first time that IGF1R expression and activity via OPG can modulate VSMC calcification in vitro. We suggest a feedback mechanism: moderate calcium levels increase OPG, which then increases IGF1R to enhance VSMC survival and block calcification induced by calcium. In contrast, high calcium leads to inhibition of IGF1R expression and activity to stimulate VSMC calcification further.

The Role of IGF-1 Receptor and Insulin Receptor Signaling for the Pathogenesis of Alzheimers Disease: From Model Organisms to Human Disease

In different clinical studies, an association of type 2 diabetes and Alzheimer's disease (AD) has been described. However, the underlying mechanisms are still unclear. One explanation could be that vascular complications of diabetes result in neurodegeneration. Alternatively, the mechanism might be directly related to insulin and insulin-like growth factor(IGF)-1 signaling, leading to the proposal that AD is a "brain-type diabetes". Furthermore, postmortem analyses of brains from patients with AD revealed a markedly downregulated expression of insulin receptor (IR), IGF-1 receptor (IGF-1R), insulin receptor substrate (IRS)-1 and IRS-2, and these changes progress with severity of neurodegeneration. These findings raise the question, whether this phenomenon is cause or consequence of neurodegeneration. Recently, Cohen and coworkers have show that knocking down DAF-2 in C. elegans, the homolog of the mammalian IR/IGF-1R, reduces beta-amyloid(Abeta)(1-42) toxicity. Cell based experiments suggest a specific role for the IGF 1/IRS-2 signaling pathway in regulating alpha-/beta-secretase activity. Moreover circulating IGF-1 might influence Abeta clearance from the brain by promoting Abeta transport over the blood brain barrier. Interestingly, brain specific deletion of IRS-2 increases life span, suggesting that long term neuronal IGF-1R signaling might be harmful. Taken together, the data from humans and different model organisms indicate a role of IR/IGF-1R signaling in Abeta metabolism, and clearance as well as longevity. Since more studies are needed to elucidate the impact of insulin and/or IGF-1 treatment in AD, the time to propose these hormones as a potential treatment option for AD has not come yet.

The potential role of IGF1r in young adult patients with gastroinetstinal stromal tumor (GIST)

10562 Background: The insulin-like growth factor 1 receptor (IGF1r) is a tyrosine kinase receptor that plays a key role in the growth of normal tissues. The aberration of IGF system has been found in many cancers. Some interesting results about IGF1r were published on GISTs. However, until now the real role on the pathogenesis of this disease and its clinical implications still needs to be defined. Methods: We studied IGF1r in 8 patients affected by gastric GIST. Seven patients underwent surgery at diagnosis, whereas one patient was operated after imatinib and sunitinib treatment. Two patients were young (< 30 years old), and other patients ranged between 54 and 85 years. IGF1r was studied as gene expression profiling performed with Affymetrix GeneChip HG-U133 Plus 2.0 arrays, as genomic copy number with SNP array analysis Affymetrix Genome Wide Human SNP 6.0 arrays, and with western blotting (WB) usinganti-IGF-IRβ (Santa Cruz Biotechnology). Results: The unsupervised analysis of gene expression profiling of our patients merged with a data set from a gastric GIST identified two groups with different regulation of IGF1r (FDR threshold to 0.2%). In particular, IGF1r was up-regulated in the two youngest patients (28 and 30 years-old). The SNPs array analysis gene copy number showed that none of the patients bore IGF1r amplification. The quantitative analysis of protein level by WB again showed that only the two youngest patients had an over-expression of IGF1r. In all the other patients the WB analysis was negative. Conclusions: These results suggest that IGF1r seems to be a novel signalling pathway other than KIT and PDGFRA in a subset of GISTs. The young adult patients had a strongly different molecular background in comparison to the other older ones. The correlation between IGF1r and mutational status of KIT and PDGFRA, clinical outcome, treatments responsiveness as well as its role as potential target deserves to be further investigated. No significant financial relationships to disclose.

Mechanisms of Disease: signaling of the insulin-like growth factor 1 receptor pathway—therapeutic perspectives in cancer

The insulin-like growth factor 1 (IGF1) signaling pathway is implicated in the development of cancer. High levels of circulating IGF1 and certain genetic polymorphisms of IGF1 and IGFBP3 are associated with an increased risk of several common cancers. The IGF1 receptor (IGF1R) has been shown to be expressed in a wide range of tumors, and IGF1R signaling is crucial for tumor transformation and the survival of malignant cells. Several monoclonal antibodies and small-molecule inhibitors have been tested in preclinical studies and early-phase clinical studies. IGF1R signaling interferes with numerous growth factors and receptors such as VEGF and EGFR. In the experimental system, IGF1R signaling has been found to correlate with resistance to therapies based on the inhibition of EGFR and HER2. This Review highlights the most relevant studies in this exciting area of research, focusing in particular on the role of IGF1R in resistance to other receptor-targeted therapies for cancer.

A novel role for IGF-1R in p53-mediated apoptosis through translational modulation of the p53-Mdm2 feedback loop

Insulin-like growth factor 1 receptor (IGF-1R) is important in cancer cell growth and survival and has been implicated in cancer pathophysiology and treatment. Here we report a novel function for IGF-1R in p53-dependent apoptotic response. We show that inhibition or loss of IGF-1R activity reduces translational synthesis of p53 and Mdm2 protein. Notably, IGF-1R inhibition increases p53 protein stability by reducing p53 ubiquitination and maintains p53 at low levels by decreasing p53 synthesis, thus rendering p53 insensitive to stabilization after DNA damage. The accumulation and apoptosis of DNA-damage–induced p53 is therefore reduced in Igf-1r−/− mouse embryonic fibroblasts or tumor cells treated with the IGF-1R inhibitor. Furthermore, we find that inhibition of IGF-1R reduces p53 and Mdm2 translation through a gene-specific mechanism mediated by the respective 5′ untranslated region of p53 and mdm2 messenger RNA. The eukaryotic translation initiation factor 4F complex is also involved in this translational inhibition. These results demonstrate an unexpected role for translational control by IGF-1R in p53-mediated apoptosis.

Vascular smooth muscle cell NAD(P)H oxidase activity during the development of hypertension: Effect of angiotensin II and role of insulinlike growth factor-1 receptor transactivation

We investigated whether angiotensin II (Ang II)-induced reactive oxygen species (ROS) generation is altered in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) during the phases of prehypertension, developing hypertension, and established hypertension and assessed the putative role of insulinlike growth factor-1 receptor (IGF-1R) in Ang II-mediated actions. The VSMCs from SHR and Wistar-Kyoto rats (WKY) aged 4 (prehypertensive), 9 (developing hypertension), and 16 (established hypertension) weeks were studied. The ROS production and NAD(P)H oxidase activation were determined by fluorescence and chemiluminescence, respectively. The role of IGF-1R was assessed with the selective inhibitor AG1024. The ROS bioavailability was manipulated with Tiron (10(-5) mol/L) and diphenylene iodonium (DPI) (10(-6) mol/L). Angiotensin II dose dependently increased ROS production in WKY and SHR at all ages. The Ang II-induced responses were greater in SHR versus WKY at 9 and 16 weeks (P < .05). The Ang II-stimulated ROS increase was greater in 9- and 16-week-old SHR versus 4-week SHR (P < .05). These effects were reduced by AG 1024. Basal NAD(P)H oxidase activity was higher in VSMCs from 9-week-old SHR versus 4-week-old rats (P < .05). Angiotensin II induced a significant increase in oxidase activity in VSMCs from 9- and 16-week-old SHR (P < .001), without influencing responses in cells from 4-week-old SHR. Pretreatment of 9- and 16-week-old SHR cells with AG1024 reduced Ang II-mediated NAD(P)H oxidase activation (P < .05). Basal and Ang II-induced NAD(P)H-driven ROS generation are enhanced in VSMCs from SHR during development of hypertension, but not in cells from prehypertensive rats. Transactivation of IGF-1R by Ang II may be important in vascular oxidative excess in the development of hypertension in SHR.