Novel Insulin-Like Growth Factor 1 Gene Mutation: Broadening of the Phenotype and Implications for Insulin Resistance.

CONTEXT: Insulin-like growth factor (IGF)1 gene mutations are extremely rare causes of pre- and postnatal growth retardation. Phenotype can be heterogenous with varying degrees of neurosensory deafness, cognitive defects, glucose metabolism impairment and short stature. OBJECTIVE: This study describes a 12.6-year-old girl presenting with severe short stature and insulin resistance, but with normal hearing and neurological development at the lower limit of normal. METHODS: DNA was obtained from the proband and both parents for whole exome sequencing (WES). In silico analysis was performed to predict the impact of the IGF1 variant on IGF1 and insulin receptors (IGF1R and IR) signaling. Phosphorylation of the IGF1R at activating Tyr residues and cell proliferation analyses were used to assess the ability of each subject's IGF1 to bind and activate IGF1R. RESULTS: The proband had low immunoreactive IGF1 in serum and WES revealed a novel homozygous IGF1 missense variant (c.247A>T), causing a change of serine 83 for cysteine (p.Ser83Cys; p.Ser35Cys in mature peptide). The proband's parents were heterozygous for this mutation. In silico analyses indicated the pathogenic potential of the variant with electrostatic variations with the potential of hampering the interaction with the IGF1R but strengthening the binding to IR. The mutant IGF1 protein had a significantly reduced activity on in vitro bioassays. CONCLUSION: We describe a novel IGF1 mutation leading to severe loss of circulating IGF1 immunoreactivity and bioactivity. In silico modeling predicts that the mutant IGF1 could interfere with IR signaling, providing a possible explanation for the severe insulin resistance observed in the patient. The absence of significant hearing and neurodevelopmental involvement in the present case is unusual and broadens the clinical spectrum of IGF1 mutations.

Type 1 Insulin-Like Growth Factor Receptor Nuclear Localization in High-Grade Glioma Cells Enhances Motility, Metabolism, and In Vivo Tumorigenesis.

Gliomas are the most frequent solid tumors in children. Among these, high-grade gliomas are less common in children than in adults, though they are similar in their aggressive clinical behavior. In adults, glioblastoma is the most lethal tumor of the central nervous system. Insulin-like growth factor 1 receptor (IGF1R) plays an important role in cancer biology, and its nuclear localization has been described as an adverse prognostic factor in different tumors. Previously, we have demonstrated that, in pediatric gliomas, IGF1R nuclear localization is significantly associated with high-grade tumors, worst clinical outcome, and increased risk of death. Herein we explore the role of IGF1R intracellular localization by comparing two glioblastoma cell lines that differ only in their IGF1R capacity to translocate to the nucleus. In vitro, IGF1R nuclear localization enhances glioblastoma cell motility and metabolism without affecting their proliferation. In vivo, IGF1R has the capacity to translocate to the nucleus and allows not only a higher proliferation rate and the earlier development of tumors but also renders the cells sensitive to OSI906 therapy. With this work, we provide evidence supporting the implications of the presence of IGF1R in the nucleus of glioma cells and a potential therapeutic opportunity for patients harboring gliomas with IGF1R nuclear localization.

VHL-P138R and VHL-L163R Novel Variants: Mechanisms of VHL Pathogenicity Involving HIF-Dependent and HIF-Independent Actions.

The von Hippel-Lindau (VHL) disease is an autosomal dominant cancer syndrome caused by mutations in the VHL tumor suppressor gene. VHL protein (pVHL) forms a complex (VBC) with Elongins B-C, Cullin2, and Rbx1. Although other functions have been discovered, the most described function of pVHL is to recognize and target hypoxia-inducible factor (HIF) for degradation. This work comprises the functional characterization of two novel variants of the VHL gene (P138R and L163R) that have been described in our center in patients with VHL disease by in vitro, in vivo, and in silico approaches. In vitro, we found that these variants have a significantly shorter half-life compared to wild-type VHL but still form a functional VBC complex. Altered fibronectin deposition was evidenced for both variants using immunofluorescence. In vivo studies revealed that both variants failed to suppress tumor growth. By means of molecular dynamics simulations, we inspected in silico the nature of the changes introduced by each variant in the VBC complex. We have demonstrated the pathogenicity of P138R and L163R novel variants, involving HIF-dependent and HIF-independent mechanisms. These results provide the basis for future studies regarding the impact of structural alterations on posttranslational modifications that drive pVHL's fate and functions.

New Insights into Pheochromocytoma Biology: the Role of the Insulin - Like Growth Factor 1 (IGF1) System.

Pheochromocytomas/paragangliomas (PCCs/PGLs) are rare neuroendocrine tumors, developed from chromaffin cells derived from the neural crest. From a genetic point of view PCCs/PGLs are divided as sporadic cases, and inherited cases as part of hereditary (familial) syndromes. While the majority is benign, up to 26% of PCCs/PGLs will undergo malignant transformation. Validated prognostic pathological parameters for malignant PCCs/PGLs are still lacking. Signaling that follows the interactions between IGFs and their receptor/s in tumor cells received extensive attention when investigating the role of IGF1R in cancer. Increased IGF1R expression has been shown during progression to metastatic phenotypes and associated with worse prognosis in several types of cancer. In this review we provide evidence supporting a role for the IGFs system on PCC/PGL tumor biology and malignant behavior, endocrine actions to sustain tumor phenotype as well as heterotypic interaction´s regulation by IGF1, encouraging further research for targeted therapeutic options for these tumors.

Cytochrome 450 metabolites of arachidonic acid (20-HETE, 11,12-EET and 14,15-EET) promote pheochromocytoma cell growth and tumor associated angiogenesis.

The importance of cytochrome P450 (CYP)-derived arachidonic acid (AA) metabolites, 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) as tumor growth promotors has already been described in several cancer types. The aim of this study was to evaluate the role of these compounds in the biology of pheochromocytoma/paraganglioma. These tumors originate from chromaffin cells derived from adrenal medulla (pheochromocytomas) or extra-adrenal autonomic paraganglia (paragangliomas), and they represent the most common hereditary endocrine neoplasia. According to mutations in the driver genes, these tumors are divided in two clusters: pseudo-hypoxic and kinase-signaling EETs, but not 20-HETE, exhibited a potent ability to sustain growth in a murine pheochromocytoma cell line (MPC) in vitro, EETs promoted an increase in cell proliferation and a decrease in cell apoptosis. In a mouse model of pheochromocytoma, the inhibition of CYP-mediated AA metabolism using 1-aminobenzotriazol resulted in slower tumor growth, a decreased vascularization, and a lower final volume. Also, the expression of AA-metabolizing CYP monooxygenases was detected in tumor samples from human origin, being their apparent abundance and the production of both metabolites higher in tumors from the kinase-signaling cluster. This is the first evidence of the importance of CYP- derived AA metabolites in the biology and development of pheochromocytoma/paraganglioma tumors.

A homozygous mutation in the highly conserved Tyr60 of the mature IGF1 peptide broadens the spectrum of IGF1 deficiency.

BACKGROUND: IGF1 is a key factor in fetal and postnatal growth. To date, only three homozygous IGF1 gene defects leading to complete or partial loss of IGF1 activity have been reported in three short patients born small for gestational age. We describe the fourth patient with severe short stature presenting a novel homozygous IGF1 gene mutation. RESULTS: We report a boy born from consanguineous parents at 40 weeks of gestational age with intrauterine growth restriction and severe postnatal growth failure. Physical examination revealed proportionate short stature, microcephaly, facial dysmorphism, bilateral sensorineural deafness and mild global developmental delay. Basal growth hormone (GH) fluctuated from 0.2 to 29 ng/mL, while IGF1 levels ranged from -1.15 to 2.95 SDS. IGFBP3 was normal-high. SNP array delimited chromosomal regions of homozygosity, including 12q23.2 where IGF1 is located. IGF1 screening by HRM revealed a homozygous missense variant NM_000618.4(IGF1):c.322T>C, p.(Tyr108His). The change of the highly conserved Tyr60 in the mature IGF1 peptide was consistently predicted as pathogenic by multiple bioinformatic tools. Tyr60 has been described to be critical for IGF1 interaction with type 1 IGF receptor (IGF1R). In vitro, HEK293T cells showed a marked reduction of IGF1R phosphorylation after stimulation with serum from the patient as compared to sera from age-matched controls. Mutant IGF1 was also less efficient in inducing cell growth. CONCLUSION: The present report broadens the spectrum of clinical and biochemical presentation of homozygous IGF1 defects and underscores the variability these patients may present depending on the IGF/IGF1R pathway activity.

Fibroblast deficiency of insulin-like growth factor 1 receptor type 1 (IGF1R) impairs initial steps of murine pheochromocytoma development.

Insulin-like growth factor 1 (IGF1) has a critical role in maintaining tumor phenotype and survival of already transformed murine pheochromocytoma (pheo) cells (MPC4/30) and it is required for the initial establishment of these tumors. However, the role of local IGF1/IGF1R system in tumor microenvironment has not been fully understood. In vivo, by subcutaneous injection of pheo cells in heterozygous IGF1R knockout mice (L/n), we found that the time of noticeable tumor appearance was delayed, and incidence was decreased in L/n group compared to control (L/L) mice. Once established, tumor proliferation, vascularization or growth rate did not differ between groups. In vitro, fibroblast from L/n and L/L mice were cultured to generate conditioned media (CM) and differential matrixes on which pheo cells were seeded. Proliferation rate was higher when pheo cells were cultured with CM, or in differential matrix generated by L/L murine fibroblasts. A diminished fibronectin (FN) expression and secretion from L/n fibroblast was associated with decreased expression of integrin subunits in tumor cells. Also, soluble factors as IGF1 and insulin-like growth factor binding protein 2 (IGFBP2) were reduced. Our data suggest that IGF1 signaling through IGF1R may contribute to tumor cells anchorage and survival by interaction with both matrix and soluble factors produced by tumor microenvironment fibroblasts.

[Association between body mass index and aggressiveness of papillary thyroid carcinoma]. / Asociación entre índice de masa corporal y agresividad del carcinoma papilar de tiroides.

The aim of the study was to evaluate the association of the body mass index (BMI) with the clinical-pathological characteristics and the recurrence of papillary thyroid carcinoma. The cohort consisted of 208 patients with papillary thyroid carcinoma diagnosed in 2003-2014, in Buenos Aires, Argentina. The patients were grouped according to the BMI as follows: BMI <18.5 kg/m2 (low weight); BMI ≥ 18.5 and < 25 kg/m2 (normal weight); BMI ≥ 25 and < 30 kg/m2 (overweight); BMI ≥ 30 kg/m2 (obesity). Two experienced pathologists reviewed and cross-checked all pathology specimens to confirm diagnosis, tumor characteristics and extent of the disease. All patients were followed every 6 months for 2 years, and annually thereafter. Recurrences were searched by using diagnostic imaging and histological confi rmation when necessary. Regression analysis was applied to defi ne associations of BMI with clinical, pathological, and prognosis features of the disease. A 5-point increase in BMI was significantly associated with tumor size (OR 1.21; 95% CI 1.1-1.5; p = 0.01) and greater extranodal extension in cervical metastases (OR 1.11; 95% CI 1.06-1.21; p = 0.03). The analysis of prognostic variables showed no association between increase in BMI and risk of recurrence (HR 1.11; 95% CI 0.91-1.22). In conclusion, we found that BMI relates directly with tumor size and extranodal extension, but not with recurrence.

Asociación entre índice de masa corporal y agresividad del carcinoma papilar de tiroides / Association between body mass index and aggressiveness of papillary thyroid carcinoma

El objetivo del estudio fue evaluar la asociación del índice de masa corporal (IMC) con las características clínico-patológicas y la recurrencia del carcinoma papilar de tiroides. La cohorte consistió en 208 pacientes con carcinoma papilar de tiroides diagnosticado en 2003-2014, en Buenos Aires, Argentina. El seguimiento fue semestral los primeros 2 años y luego anual. Los pacientes fueron agrupados según el IMC de la siguiente manera: IMC < 18.5 kg/m² (bajo peso); IMC ≥ 18.5 y < 25 kg/m² (peso normal); IMC ≥ 25 y < 30 kg/m² (sobrepeso); IMC ≥ 30 kg/m² (obesidad). Dos patólogos experimentados revisaron todas las muestras para determinar las características del tumor y la extensión de la enfermedad. La recurrencia tumoral fue evaluada mediante diagnóstico por imágenes y confirmación histológica. Se utilizó un análisis de regresión para identificar la asociación del IMC con las características clínico-patológicas del tumor y con la recurrencia. El aumento de 5 puntos en el IMC se asoció significativamente con mayor tamaño tumoral (OR 1.21; IC 95% 1.1-1.5; p = 0.01) y con mayor extensión extranodal de las metástasis cervicales (OR 1.11; IC95% 1.06-1.21; p = 0.03). No se observó asociación entre el aumento del IMC y el riesgo de recurrencia (HR 1.11; IC95% 0.91-1.22). En conclusión, se demostró una asociación directa del IMC con el tamaño tumoral y la extensión extranodal pero no con la recurrencia del tumor.

The aim of the study was to evaluate the association of the body mass index (BMI) with the clinical-pathological characteristics and the recurrence of papillary thyroid carcinoma. The cohort consisted of 208 patients with papillary thyroid carcinoma diagnosed in 2003-2014, in Buenos Aires, Argentina. The patients were grouped according to the BMI as follows: BMI <18.5 kg/m² (low weight); BMI ≥ 18.5 and < 25 kg/m² (normal weight); BMI ≥ 25 and < 30 kg/m² (overweight); BMI ≥ 30 kg/m² (obesity). Two experienced pathologists reviewed and cross-checked all pathology specimens to confirm diagnosis, tumor characteristics and extent of the disease. All patients were followed every 6 months for 2 years, and annually thereafter. Recurrences were searched by using diagnostic imaging and histological confirmation when necessary. Regression analysis was applied to define associations of BMI with clinical, pathological, and prognosis features of the disease. A 5-point increase in BMI was significantly associated with tumor size (OR 1.21; 95% CI 1.1-1.5; p = 0.01) and greater extranodal extension in cervical metastases (OR 1.11; 95% CI 1.06-1.21; p = 0.03). The analysis of prognostic variables showed no association between increase in BMI and risk of recurrence (HR 1.11; 95% CI 0.91-1.22). In conclusion, we found that BMI relates directly with tumor size and extranodal extension, but not with recurrence.

Type 1 IGF Receptor Localization in Paediatric Gliomas: Significant Association with WHO Grading and Clinical Outcome.

Nuclear localization of insulin-like growth factor receptor type 1 (IGF-1R) has been described as adverse prognostic factor in some cancers. We studied the expression and localization of IGF-1R in paediatric patients with gliomas, as well as its association with World Health Organization (WHO) grading and survival. We conducted a single cohort, prospective study of paediatric patients with gliomas. Samples were taken at the time of the initial surgery; IGF-1R expression and localization were characterized by immunohistochemistry (IHC), subcellular fractionation and western blotting. Tumours (47/53) showed positive staining for IGF-1R by IHC. IGF-1R nuclear labelling was observed in 10/47 cases. IGF-1R staining was mostly non-nuclear in low-grade tumours, while IGF-1R nuclear labelling was predominant in high-grade gliomas (p = 0.0001). Survival was significantly longer in patients with gliomas having non-nuclear IGF-1R localization than in patients with nuclear IGF-1R tumours (p = 0.016). In gliomas, IGF-1R nuclear localization was significantly associated with both high-grade tumours and increased risk of death. Based on a prospective design, we provide evidence of a potential usefulness of intracellular localization of IGF-1R as prognostic factor in paediatric patients with gliomas.

Partial growth hormone insensitivity and dysregulatory immune disease associated with de novo germline activating STAT3 mutations.

Germinal heterozygous activating STAT3 mutations represent a novel monogenic defect associated with multi-organ autoimmune disease and, in some cases, severe growth retardation. By using whole-exome sequencing, we identified two novel STAT3 mutations, p.E616del and p.C426R, in two unrelated pediatric patients with IGF-I deficiency and immune dysregulation. The functional analyses showed that both variants were gain-of-function (GOF), although they were not constitutively phosphorylated. They presented differences in their dephosphorylation kinetics and transcriptional activities under interleukin-6 stimulation. Both variants increased their transcriptional activities in response to growth hormone (GH) treatment. Nonetheless, STAT5b transcriptional activity was diminished in the presence of STAT3 GOF variants, suggesting a disruptive role of STAT3 GOF variants in the GH signaling pathway. This study highlights the broad clinical spectrum of patients presenting activating STAT3 mutations and explores the underlying molecular pathway responsible for this condition, suggesting that different mutations may drive increased activity by slightly different mechanisms.

[Hypoglycemia induced by a solitary fibrous tumor of the lung or Doege-Potter syndrome: Report of one case]. / Hipoglicemia inducida por tumor fibroso solitario pulmonar: Síndrome de Doege-Potter.

We report the case of a 75-year-old man who was admitted to the hospital with symptoms of severe hypoglycemia. He had a history of solitary fibrous tumor diagnosed by Pathology after its complete surgical resection eight years before. The laboratory examination reported hypoglycemia with inhibited Insulin secretion. A computed tomography of the thorax revealed a large solid heterogeneous mass in the left hemithorax. Solitary fibrous tumor is a rare neoplasm. The association of solitary fibrous tumor and paraneoplastic hypoglycemia is known as Doege-Potter syndrome and occurs in less than 5% of all solitary fibrous tumors.

Hipoglicemia inducida por tumor fibroso solitario pulmonar: síndrome de Doege-Potter / Hypoglycemia induced by a solitary fibrous tumor of the lung or Doege-Potter syndrome: report of one case

We report the case of a 75-year-old man who was admitted to the hospital with symptoms of severe hypoglycemia. He had a history of solitary fibrous tumor diagnosed by Pathology after its complete surgical resection eight years before. The laboratory examination reported hypoglycemia with inhibited Insulin secretion. A computed tomography of the thorax revealed a large solid heterogeneous mass in the left hemithorax. Solitary fibrous tumor is a rare neoplasm. The association of solitary fibrous tumor and paraneoplastic hypoglycemia is known as Doege-Potter syndrome and occurs in less than 5% of all solitary fibrous tumors.

Overexpression of the insulin-like growth factor 1 receptor (IGF-1R) is associated with malignancy in familial pheochromocytomas and paragangliomas.

CONTEXT: Pheochromocytomas and paragangliomas (pheo/pgl) are neuroendocrine tumours derived from chromaffin cells. Although mostly benign, up to 26% of pheo/pgl will undergo malignant transformation. Reliable histological signs to differentiate benign pheo/pgl from malignant tumours are currently lacking. Increased IGF-1R expression has been shown during progression to metastatic phenotypes of several types of cancer. OBJECTIVE: To analyse the distribution and expression of the IGF-1R in pheo/pgl of different genetic origin and degree of malignancy. MEASUREMENTS: We studied the expression of the IGF-1R protein by immunohistochemistry, in 40 primary tumours from patients with pheo/pgl from different genetic aetiology (11 of 29 metastatic/nonmetastatic diseases). RESULTS: We found a strong association between increased expression of IGF-1R and malignant behaviour regardless of the age at diagnosis and the genetic aetiology. IGF-1R labelling was mostly weak in primary tumours from patients with nonmetastatic pheo/pgl. Conversely, intense IGF-1R labelling was predominant in cases of pheo/pgl with confirmed metastatic disease. The risk of metastases was 11·7 times higher if tumour IGF-1R labelling was intense independently of age at diagnosis. The probability of remaining free of metastases was higher in patients with pheo/pgl scored weak for IGF-1R at 60 months and more than twofold higher at 120 months of follow-up than in patients with intense IGF-1R labelling in their primary tumours. CONCLUSIONS: Our results strongly suggest that IGF-1R is associated with malignancy in familial pheo/pgl and that IGF-1R expression in the primary tumour might be a useful tool to detect those patients harbouring pheo/pgl who have an increased risk of metastasis.