The Origination of Growth Hormone/Insulin-Like Growth Factor System: A Story From Ancient Basal Chordate Amphioxus

The growth hormone/insulin-like growth factor (GH/IGF) system, also called the pituitary-liver axis, has a somatotrophic role in the body. Although the GH/IGF system has always been regarded as a vertebrate-specific endocrine system, its actual origin remained unknown for a long time. The basal chordate, amphioxus, occupies an evolutionary position between vertebrates and invertebrates. Impressively, most of the members of the GH/IGF system are present in the amphioxus. The GH-like molecule in the amphioxus is mainly expressed in Hatschek's pit. It functions similarly to vertebrate GH and has a GH receptor-like binding partner. The amphioxus IGF-like peptide shows mitogenic activity and an expression pattern resembling that of vertebrate IGF-I. The receptor of IGF-like peptide and IGF binding protein (IGFBP) have also been demonstrated to exist in the amphioxus. These results reveal the origin of the gene families in the GH/IGF system, providing strong evidence that this system emerged in the amphioxus.

LPS-enhanced IGF-IIR pathway to induce H9c2 cardiomyoblast cell hypertrophy was attenuated by Carthamus tinctorius extract via IGF-IR activation

The use of herbs as alternative cardiovascular disease treatment has attracted a great deal of attention owing to their lower toxicity. Whether Carthamus tinctorius extract prevent cardiomyoblast cell hypertrophy remains unclear. The present study was performed to investigate the effect of C tinctorius extract (CTF) on rat cardiomyoblast cell H9c2 and the possible molecular mechanisms. H9c2 cells were treated with lipopolysaccharide (LPS; 2 μg/mL) for 12 hours, subsequently treated with CTF (1-25 μg/mL) The incubation continued for another 24 hours, and the cells were analyzed with actin staining assay, western blot analysis, and siRNA transfection assays. In the present study, the increased cell size induced by LPS was significantly decreased by pretreating at a concentration of 1-25 μg/mL CTF. It was found that CTF could inhibit cardiac hypertrophy induced by LPS and decrease hypertrophic proteins calcineurin, p-GATA-4, GATA-4, atrial natriuretic peptide, and B-type natriuretic peptide levels in H9c2 cells. Additionally, LPS-induced insulin-like growth factor-II receptor (IGF-IIR) hypertrophy pathway was downregulated by CTF. Moreover, IGF-IR siRNA or inhibitors both reversed the CTF effects, confirming that CTF activates IGF-1R to prevent LPS-induced H9c2 cardiomyoblast cell hypertrophy. The current findings indicate that CTF activates IGF-IR to inhibit IGF-IIR signaling pathway which resulted in reducing H9c2 cardiomyoblast cell hypertrophy induced by LPS.

Thyroid-associated ophthalmopathy: Emergence of teprotumumab as a promising medical therapy

Thyroid-associated ophthalmopathy (TAO) remains a vexing autoimmune component of Graves' disease that can diminish the quality of life as a consequence of its impact on visual function, physical appearance and emotional well-being. Because of its relative rarity and variable presentation, the development of highly effective and well-tolerated medical therapies for TAO has been slow relative to other autoimmune diseases. Contributing to the barriers of greater insight into TAO has been the historical absence of high-fidelity preclinical animal models. Despite these challenges, several agents, most developed for treatment of other diseases, have found their way into consideration for use in active TAO through repurposing. Among these, teprotumumab is a fully human inhibitory monoclonal antibody against the insulin-like growth factor I receptor. It has shown remarkable effectiveness in moderate to severe, active TAO in two completed multicenter, double masked, and placebo controlled clinical trials. The drug exhibits a favorable safety profile. Teprotumumab has recently been approved by the U.S. F.D.A, and may rapidly become the first line therapy for this disfiguring and potentially blinding condition.

TAE226, a dual inhibitor of focal adhesion kinase and insulin-like growth factor-I receptor, is effective for Ewing sarcoma

The outcomes for relapsed and metastatic Ewing sarcoma (EWS) is extremely poor. Therefore, it is important to identify the tumor‐specific targets in these intractable diseases. High focal adhesion kinase (FAK) transcript expression levels in EWS cell lines are known. TAE226 is a dual inhibitor of FAK and insulin‐like growth factor‐I receptor (IGF‐IR), while PF‐562,271 is a dual inhibitor of FAK and proline‐rich tyrosine kinase 2. We compared the cytotoxicity of TAE226 and PF‐562,271 toward three EWS cell lines. TAE226 strongly inhibited proliferation of three cell lines when compared with PF‐562,271. Furthermore, we investigated the efficacy of TAE226 as well as its mechanism of action against EWS. A stable EWS cell line with FAK and IGF‐IR knocked down was established, and microarray analysis revealed dysregulated expression in various pathways. TAE226 treatment of EWS cell lines induced cell cycle arrest, apoptosis, AKT dephosphorylation, and inhibition of invasion. We demonstrated that TAE226 drastically inhibits the local growth of primary tumors and metastasis in EWS using mouse models. Furthermore, the combination of TAE226 and conventional chemotherapy proved to exert synergistic effects. TAE226 may be a candidate single agent or combined therapy drug to be developed for patients who have relapse and metastatic EWS tumors in future.

Insulin-like Growth Factor I Receptor: A Novel Target for Hepatocellular Carcinoma Gene Therapy

Human insulin-like growth factor (IGF) axis affects the molecular pathogenesis of hepatocellular carcinoma (HCC), especially in the abnormality of hepatic IGF-I receptor (IGF-IR) or IGF-II expression as a key molecule in hepatocarcinogenesis. However, the over-expression of hepatic IGFIR is associated with HCC progression with largely unknown mechanisms. The IGF-IR as one key molecule of the IGF signal pathway plays an important role in the hepatocyte malignant transformation. Attaching importance to IGF-IR might improve the prognostic or the therapeutic technique of HCC. This article reviews IGF-IR alteration during HCC development, and the effects of silencing IGF-IR gene by specific short hairpin RNA on the inhibition of cell proliferation in vitro or HCC xenograft growth in vivo to elucidate it as a novel molecular-targeted therapy for HCC.

Combined and individual tumor-specific expression of insulin-like growth factor-I receptor, insulin receptor and phospho-insulin-like growth factor-I receptor/insulin receptor in primary breast cancer: Implications for prognosis in different treatment groups

Clinical trials examining insulin-like growth factor-I receptor (IGF1R)-targeting strategies have emphasized that better predictive biomarkers are required to improve patient selection.

Immunohistochemical tumor-specific protein expression of IGF1R, insulin receptor (InsR), and phosphorylated IGF1R/InsR (pIGF1R/InsR) individually and combined in relation to breast cancer prognosis was evaluated in a population-based cohort of 1,026 primary invasive breast cancer patients without preoperative treatment diagnosed in Sweden. IGF1R (n = 923), InsR (n = 900), and pIGF1R/InsR (n = 904) combined cytoplasmic and membrane staining was dichotomized. IGF1R^strong/InsR^mod/strong/pIGF1R/InsR^pos tumors were borderline associated with 2-fold risk for events, HR_adj (2.00; 95%CI 0.96-4.18). Combined IGF1R and pIGF1R/InsR status only impacted prognosis in patients with InsR^mod/strong expressing tumors (P_interaction = 0.041). IGF1R^strong expression impacted endocrine treatment response differently depending on patients’ age and type of endocrine therapy. Phospho-IGF1R/InsR^pos was associated with lower risk for events among non-endocrine-treated patients irrespective of ER status, HR_adj (0.32; 95%CI 0.16-0.63), but not among endocrine-treated patients (P_interaction = 0.024). In non-endocrine-treated patients, pIGF1R/InsR^pos was associated with lower risk for events after radiotherapy, HR_adj (0.31; 95%CI 0.12-0.80), and chemotherapy, HR_adj (0.29; 95%CI 0.09-0.99). This study highlights the complexity of IGF hetero-and homodimer signaling network and its interplay with endocrine treatment, suggesting that combinations of involved factors may improve patient selection for IGF1R-targeted therapy.

Bone Status in a Patient with Insulin-Like Growth Factor-1 Receptor Deletion Syndrome: Bone Quality and Structure Evaluation Using Dual-Energy X-Ray Absorptiometry, Peripheral Quantitative Computed Tomography, and Quantitative Ultrasonography

Haploinsufficiency of the insulin-like growth factor (IGF)-1 receptor (IGF1R) gene is a rare, probably under-diagnosed, cause of short stature. However, the effects of IGF1R haploinsufficiency on glucose metabolism, bone status, and metabolism have rarely been investigated. We report the case of a patient referred to our center at the age of 18 months for short stature, failure to thrive, and Silver-Russell-like phenotype. Genetic analysis did not show hypomethylation of the 11p15.5 region or uniparental disomy of chromosome 7. Growth hormone (GH) stimulation tests revealed GH deficiency, whereas IGF-1 was 248 ng/mL. r-hGH treatment showed only a slight improvement (from -4.4 to -3.5 SDS). At 10 years of age, the child was re-evaluated: CGH-array identified a heterozygous de novo 4.92 Mb deletion in 15q26.2, including the IGF1R gene. Dual-energy X-ray absorptiometry showed a normal bone mineral density z-score, while peripheral quantitative computed tomography revealed reduced cortical and increased trabecular elements. A phalangeal bone quantitative ultrasonography showed significantly reduced amplitude-dependent speed of sound and bone transmission time values. The changes in bone architecture, quality, and metabolism in heterozygous IGF1R deletion patients, support the hypothesis that IGF-1 can be a key factor in bone modeling and accrual.

IGF-I induces upregulation of DDR1 collagen receptor in breast cancer cells by suppressing MIR-199a-5p through the PI3K/AKT pathway

Discoidin Domain Receptor 1 (DDR1) is a collagen receptor tyrosine-kinase that contributes to epithelial-to-mesenchymal transition and enhances cancer progression. Our previous data indicate that, in breast cancer cells, DDR1 interacts with IGF-1R and positively modulates IGF-1R expression and biological responses, suggesting that the DDR1-IGF-IR cross-talk may play an important role in cancer.

In this study, we set out to evaluate whether IGF-I stimulation may affect DDR1 expression. Indeed, in breast cancer cells (MCF-7 and MDA-MB-231) IGF-I induced significant increase of DDR1 protein expression, in a time and dose dependent manner. However, we did not observe parallel changes in DDR1 mRNA. DDR1 upregulation required the activation of the PI3K/AKT pathway while the ERK1/2, the p70/mTOR and the PKC pathways were not involved. Moreover, we observed that DDR1 protein upregulation was induced by translational mechanisms involving miR-199a-5p suppression through PI3K/AKT activation. This effect was confirmed by both IGF-II produced by cancer-associated fibroblasts from human breast cancer and by stable transfection of breast cancer cells with a human IGF-II expression construct. Transfection with a constitutively active form of AKT was sufficient to decrease miR-199a-5p and upregulate DDR1. Accordingly, IGF-I-induced DDR1 upregulation was inhibited by transfection with pre-miR-199a-5p, which also impaired AKT activation and cell migration and proliferation in response to IGF-I.

These results demonstrate that, in breast cancer cells, a novel pathway involving AKT/miR-199a-5p/DDR1 plays a role in modulating IGFs biological responses. Therefore, this signaling pathway may represent an important target for breast cancers with over-activation of the IGF-IR axis.

Novel cross talk between IGF-IR and DDR1 regulates IGF-IR trafficking, signaling and biological responses

The insulin-like growth factor-I receptor (IGF-IR), plays a key role in regulating mammalian development and growth, and is frequently deregulated in cancer contributing to tumor initiation and progression. Discoidin domain receptor 1 (DDR1), a collagen receptor tyrosine-kinase, is as well frequently overexpressed in cancer and implicated in cancer progression. Thus, we investigated whether a functional cross-talk between the IGF-IR and DDR1 exists and plays any role in cancer progression.

Using human breast cancer cells we found that DDR1 constitutively associated with the IGF-IR. However, this interaction was enhanced by IGF-I stimulation, which promoted rapid DDR1 tyrosine-phosphorylation and co-internalization with the IGF-IR. Significantly, DDR1 was critical for IGF-IR endocytosis and trafficking into early endosomes, IGF-IR protein expression and IGF-I intracellular signaling and biological effects, including cell proliferation, migration and colony formation. These biological responses were inhibited by DDR1 silencing and enhanced by DDR1 overexpression.

Experiments in mouse fibroblasts co-transfected with the human IGF-IR and DDR1 gave similar results and indicated that, in the absence of IGF-IR, collagen-dependent phosphorylation of DDR1 is impaired.

These results demonstrate a critical role of DDR1 in the regulation of IGF-IR action, and identify DDR1 as a novel important target for breast cancers that overexpress IGF-IR.

Cross-Talk between Adiponectin and IGF-IR in Breast Cancer

Obesity is a chronic and multifactorial disorder that is reaching epidemic proportions. It is characterized by an enlarged mass of adipose tissue caused by a combination of size increase of preexisting adipocytes (hypertrophy) and de novo adipocyte differentiation (hyperplasia). Obesity is related to many metabolic disorders like hypertension, type 2 diabetes, metabolic syndrome, and cardiovascular disease, and it is associated with an increased risk of cancer development in different tissues including breast. Adipose tissue is now regarded as not just a storage reservoir for excess energy, but rather as an endocrine organ, secreting a large number of bioactive molecules called adipokines. Among these, adiponectin represents the most abundant adipose tissue-excreted protein, which exhibits insulin sensitizing, anti-inflammatory, and antiatherogenic properties. The serum concentrations of adiponectin are inversely correlated with body mass index. Recently, low levels of plasma adiponectin have been associated with an increased risk for obesity-related cancers and development of more aggressive phenotype, concomitantly with alterations in the bioavailability of insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) signaling pathways. In this review, we discuss the cross-talk between adiponectin/AdipoR1 and IGF-I/IGF-IR in breast cancer.

Insulin-like growth factor-I induces epithelial to mesenchymal transition via GSK-3β and ZEB2 in the BGC-823 gastric cancer cell line

Metastasis is the most common cause of mortality in patients with gastric cancer. Epithelial-to-mesenchymal transition (EMT), which may be stimulated by insulin-like growth factor-I (IGF-I) is involved in the metastasis of numerous tumors; however, the molecular mechanism by which IGF-I may induce tumor cell EMT remains to be elucidated in gastric cancer. The present study aimed to investigate the induction of EMT in BGC-823 gastric cancer cells. It was identified that IGF-I induced EMT by upregulating the levels of ZEB2 transcription factor, and this was dependent on the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway in these cells. In addition, glycogen synthase kinase 3β (GSK-3β), an intracellular downstream effector of PI3K/Akt, sustained the epithelial phenotype by repressing ZEB2 expression and the subsequent inhibition of EMT induced by IGF-I, suggesting the involvement of a potential PI3K/Akt-GSK-3β-ZEB2 signaling pathway in IGF-I-induced EMT in gastric cancer BGC-823 cells. Overall, the results of the present study suggest that IGF-I induced EMT by the activation of a PI3K/Akt-GSK-3β-ZEB2 signaling pathway in gastric cancer BGC-823 cells. Therefore, this study may provide more useful information regarding the mechanism of gastric cancer metastasis.

Diabetic nephropathy in a nonobese mouse model of type 2 diabetes mellitus

A large body of research has contributed to our understanding of the pathophysiology of diabetic nephropathy. Yet, many questions remain regarding the progression of a disease that accounts for nearly half the patients entering dialysis yearly. Several murine models of diabetic nephropathy secondary to Type 2 diabetes mellitus (T2DM) do exist, and some are more representative than others, but all have limitations. In this study, we aimed to identify a new mouse model of diabetic nephropathy secondary to T2DM in a previously described T2DM model, the MKR (MCK-KR-hIGF-IR) mouse. In this mouse model, T2DM develops as a result of functional inactivation of insulin-like growth factor-1 receptor (IGF-1R) in the skeletal muscle. These mice are lean, with marked insulin resistance, hyperinsulinemia, hyperglycemia, and dyslipidemia and thus are representative of nonobese human T2DM. We show that the MKR mice, when under stress (high-fat diet or unilateral nephrectomy), develop progressive diabetic nephropathy with marked albuminuria and meet the histopathological criteria as defined by the Animal Models of Diabetic Complications Consortium. Finally, these MKR mice are fertile and are on a common background strain, making it a novel model to study the progression of diabetic nephropathy.

Phase 2 trial of cixutumumab in children, adolescents, and young adults with refractory solid tumors: a report from the Children's Oncology Group

PURPOSE

This phase 2 study was designed to assess the efficacy of single agent cixutumumab (IMC-A12) and gain further information about associated toxicities and pharmacodynamics in children, adolescents, and young adults with recurrent or refractory solid tumors.

PATIENTS AND METHODS

Patients with relapsed or refractory solid tumors were treated with 9 mg/kg of cixutumumab as a 1-hour IV infusion once weekly. Strata included: osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, neuroblastoma (evaluable disease), neuroblastoma (measurable disease), Wilms tumor, adrenocortical carcinoma, synovial sarcoma, hepatoblastoma, and retinoblastoma. Correlative studies in consenting patients included an assessment of c-peptide, IGFBP-3, IGF-1, IGF-2, hGH, and insulin in consenting patients.

RESULTS

One hundred sixteen patients with 114 eligible having a median age of 12 years (range, 2-30) were enrolled. Five patients achieved a partial response: 4/20 with neuroblastoma (evaluable only) and 1/20 with rhabdomyosarcoma. Fourteen patients had stable disease for a median of 10 cycles. Hematologic and non-hematologic toxicities were generally mild and infrequent. Serum IGF-1 and IGFBP-3 increased in response to therapy with cixutumumab.

CONCLUSION

Cixutumumab is well tolerated in children with refractory solid tumors. Limited objective single-agent activity of cixutumumab was observed; however, prolonged stable disease was observed in 15% of patients. Ongoing studies are evaluating the toxicity and benefit of cixutumumab in combination with other agents that inhibit the IGF pathway.