Longitudinal Analysis of Ocular Disease in Children with Mucopolysaccharidosis I after Hematopoietic Cell Transplantation.

Corneal clouding, causing visual impairment, is seen in nearly all patients with mucopolysaccharidosis type 1 (MPS-1). Hematopoietic cell transplantation (HCT) is able to stabilize disease in many organs. Residual disease in several tissues is being increasingly recognized, however. Data on the effect of HCT on ocular disease in patients with MPS-1 are contradictory. With this study, we aim to clarify the long-term effects of HCT on ocular disease in these patients. Best corrected visual acuity (BCVA), refraction, intraocular pressure (IOP), and slit-lamp biomicroscopic and fundoscopic examinations, including corneal clouding, were collected prospectively from 24 patients with MPS-1 who underwent HCT successfully between 2003 and 2018 (92% with >95% chimerism and normal enzyme activity after HCT). The course of corneal clouding and BCVA after HCT were analyzed using a linear mixed model. Other parameters studied were clinical phenotype, age at time of transplantation, and hematologic enzyme activity after transplantation. Outcomes of additional ophthalmologic tests were described. In addition, IDUA and α-galactosidase A (AGAL) enzyme activity and glycosaminoglycan (GAG) concentration in tear fluid were determined. Corneal clouding stabilized in the first years after HCT but increased rapidly beyond 3 years (P < .0001). BCVA and IOP also worsened over time (P = .01 and P < .0001, respectively). IDUA activity in tear fluid remained very low (P < .0001). After initial stabilization in the cornea, ongoing ocular disease and low IDUA activity in tear fluid is seen in patients with MPS-1 despite treatment with HCT, unveiling a weak spot of current standard therapy. New therapies that overcome these shortcomings are needed to improve the late outcomes of patients.

Salivary α-Iduronidase Activity as a Potential New Biomarker for the Diagnosis and Monitoring the Effect of Therapy in Mucopolysaccharidosis Type I.

Although disease progression in mucopolysaccharidosis type I (MPS-I) can be attenuated by hematopoietic cell transplantation (HCT), it is increasingly recognized that residual disease is substantial. Biomarkers that would allow us to evaluate the efficacy of HCT (and upcoming new therapies) in nonhematologic tissues are needed. Current biomarkers, including the iduronidase (IDUA) activity in leukocytes, are not suitable for this purpose because they are assessed in tissues of hematologic origin and may not reflect enzyme availability in nonhematologic tissues. Saliva is a nonhematologic body fluid that can be collected easily and noninvasively. We hypothesized that the extent of recovery of IDUA activity in saliva after HCT could provide a better understanding of the penetration of donor-derived enzyme into nonhematologic compartments. This study in 20 patients with MPS-I shows that the measurement of IDUA activity in saliva is possible and allows diagnosis of IDUA deficiency (P < .0001), with values a magnitude further deviating from the normal range than when assayed in corresponding dried blood spots (DBSs). Furthermore, it could possibly differentiate between phenotypes (P = .045). More importantly, patients exhibit strikingly low values of IDUA in saliva after HCT, far below the normal range of control subjects (P = .013), contrasting the normal IDUA levels in DBSs. We postulate that the limited recovery of donor-derived IDUA activity in saliva after treatment reflects the situation in poorly responding nonhematologic tissue compartments, unveiling enzyme delivery as a weak spot of the current therapy. Salivary IDUA activity could be used as a biomarker for the evaluation of the effect of new therapies in well-vascularized nonhematologic tissues.

The potential of exosomes in diagnosis and treatment of inborn errors of metabolism.

Extracellular vesicles, in particular exosomes, have gained much attention as potent mediators of intercellular signaling. Exosomes are 50-130 nm intraluminal vesicles of multivesicular bodies (MVB) that are secreted into the extracellular environment upon fusion of MVB with the plasma membrane. Current research on exosomes focuses on their biogenesis, including specific sorting mechanisms, their potential to transfer proteins and RNA from their cells of origin to target cells, specific methods of vesicle isolation, and their possible application as diagnostic and therapeutic devices. Exosomes are vesicles of endocytic origin that contain a portion of the cytoplasm. Their molecular components represent the composition and thereby the physiological state of the cells from which they originate. In this review, we recapitulate the discovery of exosomes and the subsequent expansion of exosome research into a variety of different areas of interest, with a specific focus on how exosomes could prove to be invaluable for both diagnostic and therapeutic applications within the research field of inborn errors of metabolism.

'Big'-insulin-like growth factor-II signaling is an autocrine survival pathway in gastrointestinal stromal tumors.

New treatment targets need to be identified in gastrointestinal stromal tumors (GISTs) to extend the treatment options for patients experiencing failure with small-molecule tyrosine kinase inhibitors, such as imatinib. Insulin-like growth factor (IGF)-II acts as an autocrine factor in several tumor types by binding to IGF receptor type 1 (IGF-1R) and/or the insulin receptor (IR) isoform A. The aim of the present study was to investigate the putative role of unprocessed pro-IGF-II, called 'big'-IGF-II, in GISTs. The imatinib-sensitive GIST882 and imatinib-resistant GIST48 cell lines secrete high levels of big-IGF-II as demonstrated by ELISA and Western blotting analyses. IR isoform A mRNA and protein expression, but not that of IGF-1R, was found in these KIT mutant cell lines and in KIT and platelet-derived growth factor receptor α-mutant GIST specimens. Down-regulation of either big-IGF-II or IR affected AKT and MAPK signaling and reduced survival in both cell lines. Disruption of big-IGF-II signaling in combination with imatinib had additive cytotoxic effects on GIST882 cells. IGF-II mRNA as determined by in situ hybridization was present in 91% of 60 primary GISTs. Immunohistochemical analysis of big-IGF-II protein expression was associated with moderate- to high-risk tumors compared with tumors with a lower risk classification (P < 0.028). Our data put forth the big-IGF-II/IR isoform A axis as an autocrine survival pathway and potential therapeutic target in GISTs.

Atypical STAT5B deficiency, severe short stature and mild immunodeficiency associated with a novel homozygous STAT5B Variant.

STAT5B deficiency, a rare autosomal recessive disorder characterized by severe growth hormone insensitivity (GHI) and immunodeficiency, can manifest as fatal pulmonary complications. We describe atypical STAT5B deficiency associated with a novel homozygous frame-shift STAT5B variant [c.1453delG, p.(Asp485Thrfs*29)] identified in a young 17.6 yr old female subject who had severe postnatal growth impairment, biochemistries typical of GHI, an immune profile notable for hypergammaglobulinaemia and elevated B lymphocytes, and lack of pulmonary disease. Marked elevation of serum prolactin and pathologically diagnosed eczema were evident. In reconstitution studies, the STAT5B p.(Asp485Thrfs*29) was expressed although expression was reduced compared to wild-type STAT5B and a previously identified STAT5B p.(Gln368Profs*9) variant. Both truncated STAT5B peptides could not be activated by GH, nor mobilize to the nucleus. We conclude that an intact, functional, STAT5B is essential for normal GH-mediated growth, while expressed loss-of-function STAT5B variants may alleviate severe immune and pulmonary issues normally associated with STAT5B deficiency.

Insulin-like growth factor-II and bioactive proteins containing a part of the E-domain of pro-insulin-like growth factor-II.

Insulin-like growth factor (IGF)-II is considered to function as an important fetal growth factor, which is structurally and functionally related to IGF-I and proinsulin. At least in vitro, IGF-II actions are mediated through the IGF-I receptor and to a lesser extent the insulin receptor. After birth, the function of IGF-II is less clear although in adults the serum level of IGF-II exceeds that of IGF-I several fold. The IGF-II gene is maternally imprinted, with exception of the liver and several parts of the brain, where it is expressed from both alleles. The regulation, organization, and translation of the IGF-II gene is complex, with five different putative promotors leading to a range of noncoding and coding mRNAs. The 180-amino acid pre-pro-IGF-II translation product can be divided into five domains and include a N-terminal signal peptide of 24 amino acid residues, the 67 amino acid long mature protein, and an 89 residues extension at the COOH terminus, designated as the E-domain. After removal of the signal peptide, the processing of pro-IGF-II into mature IGF-II requires various steps including glycosylation of the E-domain followed by the action of endo-proteases. Several of these processing intermediates can be found in the human circulation. There is increasing evidence that, besides IGF-II, several incompletely processed precursor forms of the protein, and even a 34-amino acid peptide (preptin) derived from the E-domain of pro-IGF-II, exhibit distinct biological activities. This review will focus on the current insights regarding the specific roles of the latter proteins in cancer, glucose homeostasis, and bone physiology. To address this topic clearly in the right context, a concise overview of the biological and biochemical properties of IGF-II and several relevant aspects of the IGF system will be provided.

Hurdles in treating Hurler disease: potential routes to achieve a "real" cure.

Mucopolysaccharidoses (MPSs) are multiorgan devastating diseases for which hematopoietic cell transplantation (HCT) and, to a lesser extent, enzyme replacement therapy have substantially altered the course of the disease. Furthermore, they have resulted in increased overall survival, especially for Hurler disease (MPS-1). However, despite the identification of clinical predictors and harmonized transplantation protocols, disease progression still poses a significant burden to patients, although at a slower pace. To design better therapies, we need to understand why and where current therapies fail. In this review, we discuss important aspects of the underlying disease and the disease progression. We note that the majority of progressive symptoms that occur in "hard-to-treat" tissues are actually tissues that are difficult to reach, such as avascular connective tissue or tissues isolated from the circulation by a specific barrier (eg, blood-brain barrier, blood-retina barrier). Although easily reached tissues are effectively cured by HCT, disease progression is observed in these "hard-to-reach" tissues. We used these insights to critically appraise ongoing experimental endeavors with regard to their potential to overcome the encountered hurdles and improve long-term clinical outcomes in MPS patients treated with HCT.

Current Insights into the Role of the Growth Hormone-Insulin-Like Growth Factor System in Short Children Born Small for Gestational Age.

BACKGROUND: The reason for the insufficient catch-up growth seen in 10% of children born small for gestational age (SGA) is poorly understood. Disturbances in the growth hormone (GH) - insulin-like growth factor (IGF) axis might underlie this failure to show sufficient catch-up growth. CONCLUSION: This review summarizes insights gained in the molecular and (epi) genetic mechanisms of the GH-IGF axis in short children born SGA. The most notable anomalies of the IGF system are the lowered IGF-I levels in both cord blood and the placenta, and the increased expression of IGF-binding proteins (IGFBP)-1 and IGFBP-2, which inhibit IGF-I, in the placenta of SGA neonates. These observations suggest a decreased bioactivity of IGF-I in utero. IGF-I levels remain reduced in SGA children with short stature, as well as IGFBP-3 and acid-labile subunit levels. Proteolysis of IGFBP-3 appears to be increased.

Various components of the insulin-like growth factor system in tumor tissue, cerebrospinal fluid and peripheral blood of pediatric medulloblastoma and ependymoma patients.

The insulin-like growth factor (IGF) system plays an important role in neuronal development and may contribute to the development of brain tumors. In this study, we studied mRNA expression levels of IGFs, insulin-like growth factor binding proteins (IGFBPs) and insulin-like growth factor receptors (IGFRs) in 27 pediatric medulloblastomas, 13 pediatric ependymomas and 5 control cerebella. Compared to normal cerebellum, mRNA levels of IGFBP-2 and IGFBP-3 were significantly increased in medulloblastomas and ependymomas. IGFBP-2 expression was indicative of poor prognosis in medulloblastomas, whereas IGFBP-3 mRNA levels were especially high in anaplastic ependymomas. IGFBP-5 and IGF-II mRNA levels were significantly increased in ependymomas compared to control cerebellum. Protein expression levels of IGFs and IGFBPs were analyzed in the cerebrospinal fluid (CSF) of 16 medulloblastoma, 4 ependymoma and 23 control patients by radioimmuno assay to determine whether they could be used as markers for residual disease after surgery. No aberrant CSF protein expression levels were found for ependymoma patients. In medulloblastoma patients, the IGFBP-3 protein levels were significantly higher than in ependymoma patients and controls. Moreover, enhanced levels of proteolytic fragments of IGFBP-3 were found in the CSF of medulloblastoma patients, being in concordance with a significantly increased IGFBP-3 proteolytic activity in the CSF of these patients. In conclusion, our data suggest that the IGF system is of importance in pediatric medulloblastomas and ependymomas. Larger studies should be conducted to validate the predictive values of the levels of intact IGFBP-3 and proteolytic fragments in CSF in the follow-up of medulloblastomas.

No effect of red clover-derived isoflavone intervention on the insulin-like growth factor system in women at increased risk of colorectal cancer.

BACKGROUND: Increased insulin-like growth factor (IGF)-I and IGF-II concentrations are related to increased colorectal cancer risk. Isoflavones have been associated with reduced colorectal cancer risk, and may affect the IGF system because of their weak estrogenic activity. The aim of the study was to investigate the effect of isolated isoflavones on serum concentrations of IGF system components. MATERIALS AND METHODS: We conducted a randomized, placebo-controlled, double-blinded, crossover trial in four hospitals in the Netherlands to investigate the effect of an 8-week supplementation with red clover-derived isoflavones (84 mg/d) on serum IGF-I concentrations. In addition, serum concentrations of IGF-II and IGF binding proteins (IGFBP)-1, IGFBP-2, and IGFBP-3 were assessed. Normal colorectal tissue biopsies were obtained after the first intervention period and mRNA expression of IGF-I, IGF-II, IGFBP-3, and IGF-IR was evaluated. Our study population consisted of 34 postmenopausal women with a family history of colorectal cancer or a personal history of colorectal adenomas. RESULTS: Isoflavone supplementation did not significantly affect serum concentrations of total IGF-I (mean relative within-person difference; IGF-I, -2.0%; 95% confidence interval, -8.0% to 3.9%). IGF-II and IGFBPs were also not significantly altered after isoflavone supplementation. Colorectal tissue mRNA expression of IGF system components did not significantly differ between individuals on isoflavone supplementation and those who received placebo. CONCLUSIONS: The results of our trial, supported by a qualitative review of soy trials published to date, suggest that isoflavones do not significantly affect circulating levels of IGF system components. Increased levels of IGF-I, as observed in most of these trials, are likely due to simultaneous protein supplementation.

Non-islet cell tumour-induced hypoglycaemia: a review of the literature including two new cases.

This review focuses on the tumour types and symptoms associated with non-islet cell tumour-induced hypoglycaemia (NICTH) as well as the pathogenesis, diagnosis and treatment of this rare paraneoplastic phenomenon. In addition, we report two illustrative cases of patients suffering from NICTH caused by a solid fibrous tumour and a haemangiopericytoma respectively. In the first case, NICTH resolved following complete resection of the tumour, but in the second case the patient needed long-term treatment aimed at controlling hypoglycaemia because of non-resectable metastases. Many tumour types have been associated with NICTH. The crucial event in the development of NICTH seems to be overexpression of the IGF-II gene by the tumour. NICTH is characterised by recurrent fasting hypoglycaemia and is associated with the secretion of incompletely processed precursors of IGF-II ('big'-IGF-II) by the tumour. This induces dramatic secondary changes in the circulating levels of insulin, GH, IGF-I and IGF-binding proteins, resulting in an insulin-like hypoglycaemic activity of 'big'-IGF-II.

Free/dissociable insulin-like growth factor (IGF)-I, not total IGF-I, correlates with growth response during growth hormone treatment in children born small for gestational age.

CONTEXT: IGF-I plays an important role in pre- and postnatal growth. Its serum levels are regulated by metabolic and genetic factors. Mean total IGF-I in short, small for gestational age (SGA) children is reduced, but within the normal range. Free/dissociable IGF-I is the bioactive form of IGF-I. OBJECTIVES: The aim of the study was to investigate changes in free IGF-I during GH treatment in short SGA children and to evaluate whether free IGF-I levels contribute to predicting first-year growth response and/or adult height. DESIGN, SETTING, AND INTERVENTION: We conducted a randomized, double-blind GH dose-response study with a GH dose of either 1 mg/m(2).d (group A) or 2 mg/m(2).d (group B). Free IGF-I, total IGF-I, and IGF binding protein (IGFBP)-3 were determined at baseline, after 1 and 5 yr, at stop, and 6 months after GH discontinuation. PATIENTS: We studied 73 (46 male) short SGA children (36 group A) with a baseline mean age of 7.7 (2.2) yr and a mean GH duration of 8.2 (2.1) yr. MAIN OUTCOME MEASURES: Untreated SGA children had a mean free IGF-I sd score (SDS) of -0.2 (1.2), not related to total IGF-I. During GH therapy, free IGF-I significantly increased to 1.6 (0.7) SDS, as did total IGF-I and IGFBP-3 [2.0 (0.8) and 1.3 (0.9), respectively]. Multiple regression analysis showed that baseline free IGF-I and IGFBP-3 were negatively correlated with adult height SDS, whereas baseline bone age delay, target height SDS, baseline height SDS, and GH dose were positively correlated. Free IGF-I was also negatively correlated with first-year growth response. CONCLUSIONS: Circulating baseline free IGF-I and IGFBP-3 were better predictors for adult height in GH-treated SGA children than total IGF-I, or total IGF-I to IGFBP-3 ratio. This suggests a possible role for free IGF-I measurement in predicting the effect of GH therapy in short SGA children.

Lycopene supplementation elevates circulating insulin-like growth factor binding protein-1 and -2 concentrations in persons at greater risk of colorectal cancer.

BACKGROUND: Higher circulating insulin-like growth factor I (IGF-I) concentrations have been related to a greater risk of cancer. Lycopene intake is inversely associated with cancer risk, and experimental studies have shown that it may affect the IGF system, possibly through an effect on IGF-binding proteins (IGFBPs). OBJECTIVE: The objective of our study was to investigate the effect of an 8-wk supplementation with tomato-derived lycopene (30 mg/d) on serum concentrations of total IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3. DESIGN: We conducted a randomized, placebo-controlled, double-blinded crossover study in 40 men and 31 postmenopausal women with a family history of colorectal cancer, a personal history of colorectal adenoma, or both. RESULTS: Lycopene supplementation significantly (P = 0.01) increased serum IGFBP-1 concentrations in women (median relative difference between serum IGFBP-1 concentrations after lycopene supplementation and after placebo, 21.7%). Serum IGFBP-2 concentrations were higher in both men and women after lycopene supplementation than after placebo, but to a lesser extent (mean relative difference 8.2%; 95% CI: 0.7%, 15.6% in men and 7.8%; 95% CI: -5.0%, 20.6% in women). Total IGF-I, IGF-II, and IGFBP-3 concentrations were not significantly altered by lycopene supplementation. CONCLUSIONS: This is the first study known to show that lycopene supplementation may increase circulating IGFBP-1 and IGFBP-2 concentrations. Because of high interindividual variations in IGFBP-1 and IGFBP-2 effects, these results should be confirmed in larger randomized intervention studies.

Growth hormone secretion and immunological function of a male patient with a homozygous STAT5b mutation.

OBJECTIVE: STAT5b is a component of the GH signaling pathway. Recently, we described a 31-year-old male patient (height, -5.9 SDS) with a novel homozygous inactivating mutation in the STAT5b gene. The purpose of this study is to describe the phenotype in detail, including GH secretion and immunological function. In addition, we report four family members of this patient, all heterozygous carriers of the mutation. DESIGN AND METHODS: Twenty-four hour GH and prolactin secretion characteristics were assessed by blood sampling at 10-min intervals. An IGF-I generation test was performed. Monocyte function was tested by stimulation of whole blood with lipopolysaccharide (LPS) in the presence or absence of Interferon-gamma (IFN-gamma). In addition, T cell function was determined by measuring proliferative responses of peripheral blood mononuclear cells (PBMC) after stimulation by various polyclonal activators and Interleukin-2 (IL-2). Clinical and biochemical characteristics were determined in the carriers of the mutation. RESULTS: GH secretory parameters were comparable with that of healthy male controls (mean fat percentage 25), but likely increased in relation to the patient's 40% body fat. The regularity of GH secretion was diminished. Prolactin secretion was increased by sixfold. The IGF-I generation test showed a small increase in IGF-I and IGF-binding protein-3 on lower GH doses and an increase in IGF-I to -2.4 SDS on the highest dose of GH. In vitro, IL-12p40, IL 10, and tumour necrosis factor-alpha (TNF-alpha) production rates by PBMC increased to values within the normal range upon stimulation of LPS. Heterozygous carriers of the mutation did not show abnormalities, although the height of the males was below the normal range. CONCLUSIONS: This report shows that GH and prolactin secretion were increased in this patient homozygous for a new STAT5b mutation. Although STAT5b plays a role in signaling within immune cells, clinical immunodeficiency is not an obligatory phenomenon of STAT5b deficiency per se. Heterozygous carriers of a STAT5b mutation show no signs of GH insensitivity.

Clinical and biochemical characteristics and bone mineral density of homozygous, compound heterozygous and heterozygous carriers of three novel IGFALS mutations.

OBJECTIVE: Acid-labile subunit (ALS) deficiency (ACLSD), caused by homozygous or compound heterozygous IGFALS mutations, is associated with moderate short stature, delayed puberty, low serum IGF-I and ALS and extremely low serum IGFBP-3. Its effect on birth weight, head circumference, bone mineral density (BMD), serum IGF-II and IGFBP-2 is uncertain, as well as the phenotype of heterozygous carriers of IGFALS mutations (partial ACLSD). DESIGN: From all available members of five Turkish families, carrying three mutations in exon 2 of IGFALS (c.1462G > A, p.Asp488Asn (families A, B, E); c.251A > G, p.Asn84Ser (families C and E) and c.1477del, p.Arg493fs (family D)), clinical, laboratory and BMD data were collected. METHODS: Auxological and biochemical findings were expressed as SDS for age and gender. Ternary complex formation in serum was investigated by size-exclusion chromatography. BMD using DXA bone densitometry was adjusted for height and age (Ha-BMD z-score). RESULTS: In ACLSD (n = 24), mean ± s.d. height SDS (-2.7 ± 1.2), head circumference SDS (-2.3 ± 0.5) and body mass index (BMI) (-0.6 ± 1.0 SDS) were lower than those in partial ACLSD (n = 26, P ≤ 0.01) and birth weight SDS (n = 7) tended to be lower (-2.2 ± 1.1 vs -0.6 ± 0.3 in partial ACLSD (P = 0.07)). Serum IGF-I was -3.7 ± 1.4 vs -1.0 ± 1.0, IGF-II: -5.6 ± 0.7 vs -1.3 ± 0.7, ALS: <-4.4 ± 1.2 vs -2.1 ± 0.9 and IGFBP-3: -9.0 ± 1.9 vs -1.6 ± 0.8 SDS respectively (P < 0.001). Ha-BMD z-score was similar and normal in both groups. CONCLUSIONS: To the known phenotype of ACLSD (i.e. short stature, reduced serum levels of IGF-I and ALS, extremely low serum IGFBP-3 and disturbed ternary complex formation), we add reduced birth weight, head circumference and serum IGF-II.

Clinical and biochemical characteristics of a male patient with a novel homozygous STAT5b mutation.

CONTEXT: GH insensitivity can be caused by defects in the GH receptor (GHR) or in the postreceptor signaling pathway. Recently, two female patients with severe growth retardation and pulmonary and immunological problems were described with a defect in STAT5b, a critical intermediary of downstream GHR signaling. OBJECTIVE: The objective was to determine the functional characteristics of a novel STAT5b mutation and describe the phenotype. PATIENT: We describe an adult male patient with short stature [-5.9 sd score (SDS)], delayed puberty, and no history of pulmonary or immunological problems. GH-binding protein level as well as GH secretion characteristics were normal. Plasma prolactin level was elevated. Extremely low levels of IGF-I (-6.9 SDS), IGF-binding protein-3 (-12 SDS), and acid-labile subunit (-7.5 SDS) were found. RESULTS: We found a homozygous frameshift mutation in the STAT5b gene (nucleotide 1102-3insC, Q368fsX376), resulting in an inactive truncated protein, lacking most of the DNA binding domain and the SH2-domain. CONCLUSIONS: This report confirms the essential role of STAT5b in GH signaling in the human. We show for the first time that immunological or pulmonary problems or elevated GH secretion are not obligatory signs of STAT5b deficiency, whereas hyperprolactinemia appears to be part of the syndrome. Therefore, in patients with severe short stature, signs of GH insensitivity, and a normal GHR, analysis of the STAT5b gene is recommended.

Ethinylestradiol and testosterone have divergent effects on circulating IGF system components in adolescents with constitutional tall stature.

OBJECTIVE: Pharmacological doses of estrogens or testosterone are used to limit the final height of girls or boys with constitutional tall stature but the mechanism behind this growth inhibition is still debated. We therefore studied the changes in the circulating components of the insulin-like growth factor (IGF) system during high dose sex steroid therapy. DESIGN AND METHODS: Twenty three girls and twenty boys with constitutional tall stature were treated with 100 microg ethinylestradiol per day or 250 mg testosterone ester every 14 days respectively. In 19 girls and 18 boys, the levels of IGF-I, free IGF-I, IGF-II, acid-labile subunit (ALS) and IGF binding proteins (IGFBP)-2 to -6 were measured before and 3-6 months after the start of therapy (group 1). In 18 girls and 11 boys, samples were collected at the end of therapy and 3 to 6 months afterwards (group 2). Fourteen girls and nine boys belonged to both groups. All parameters were measured by radioimmunoassay or ELISA. RESULTS: Levels of IGF-I were decreased significantly by estrogen treatment but remained unchanged during testosterone treatment. Free IGF-I decreased during estrogen treatment but increased during testosterone therapy. Estrogens increased IGF-II and testosterone reduced it. The important reduction of IGFBP-2 during estrogen therapy is not reproduced by androgen therapy, neither is the stimulation by estrogens of IGFBP-4. IGFBP-3 is not modulated by either sex steroid. We found that IGFBP-6 is up-regulated by testosterone but not by estrogens; the reverse is true for ALS, which increased during estrogen treatment but remained unchanged during testosterone treatment. CONCLUSIONS: Our findings demonstrate that androgens and estrogens exert differential effects on the circulating levels of several IGF components.

Quantitative analysis of the concentrations of IGFs and several IGF-binding proteins in a large fibrous abdominal tumor and the circulation of a patient with hypoglycemia.

The syndrome of nonislet cell tumor induced hypoglycemia (NICTH) represent extreme cases of excessive expression and production of incompletely processed high-molecular-mass pro-IGF-II forms (big IGF-II) by an often large tumor. Tumor-derived big IGF-II is responsible for enhanced insulin-like effects in the body through complicated mechanisms, leading to hypoglycemia. Case studies on NICTH usually focus on measurements of diagnostic parameters in the circulation of patients. Some studies have also reported on qualitative immunohistochemical analysis of tumor tissue, in particular with respect to the expression of IGF-II at the mRNA or protein level. However, quantitative data on the concentrations of IGFs and IGFBPs in tumor specimen causing NICTH, in relation to their corresponding plasma levels are lacking. Such an analysis would provide an estimate of the total potential of (big) IGF-II retained by the tumor and more insight in the relative levels of different IGFBPs and their origin in the circulation, that is, systemically induced by tumor related factors or directly tumor-derived. Here we investigated quantitatively the levels of IGFs and IGFBPs in a large, 1.76 kg weighing, solitary fibrous tumor from a typical case of NICTH using highly specific immunometric assays. Besides a high level of big IGF-II, patient's plasma also contained increased levels of both IGFBP-2 and -6 which declined after removal of the tumor. These IGFBPs have a higher affinity for (pro-) IGF-II than IGF-I and exhibit intrinsic IGF-independent bioactivities. Tumor tissue contained high amounts of big IGF-II and IGFBP-6, exceeding that in patient's circulation many-fold. A relatively low tumor content of IGFBP-2 was found suggesting that the preoperative high levels in plasma were attributable to systemic mechanisms. The background literature and possible implications of these findings are briefly discussed. Based on the present results we postulate that tumor tissue is not the source of the elevated levels of IGFBP-2 often seen in NICTH patients. Large tumors that cause NICTH can produce IGFBP-6 leading to enhanced levels of this IGFBP in the circulation. Hence, the measurement of IGFBP-6 in plasma may serve as an additional marker of this disease pattern.

IGF-I, IGF-II, 'free' IGF-I and IGF-binding proteins-2 to -6 during high-dose oestrogen treatment in constitutionally tall girls.

OBJECTIVE: To investigate the effect of high-dose oestrogen treatment on IGF-I, IGF-II, free-dissociable IGF-I and the IGF-binding proteins (IGFBP)-2 to -6 in girls with constitutional tall stature. METHODS: In patient cohort 1, blood samples were drawn before and after 3 months of daily oral treatment with 0.1 mg ethinyloestradiol. In cohort 2, samples were collected at the end of the treatment period and 3 to 6 months afterwards. IGFs and IGFBPs were analysed by specific immunoassays and by Western ligand blot. RESULTS: Total IGF-I decreased significantly on oestrogen treatment and increased again after oestrogen withdrawal. Ligand blot analysis showed a clear reduction in a 34 kDa band, corresponding to IGFBP-2, and a strong induction of a 24 kDa band, corresponding to the non-glycosylated form of IGFBP-4. These changes were confirmed by specific immunological methods. The serum levels of IGFBP-3, IGFBP-5 and IGFBP-6 remained unchanged during the first 3 months of treatment. In cohort 2, IGFBP-3 and IGFBP-6 increased after oestrogen withdrawal. Free-dissociable IGF-I fell to 35+/-4% during oestrogen therapy and rose again when the treatment was stopped. CONCLUSIONS: Oestrogens modulate the serum concentrations of several components of the IGF system. The fall in total IGF-I is not explained by a decrease in IGFBPs but probably results from a decreased synthesis.

The insulin-like growth factor-system in a patient with diffuse large B-cell non-Hodgkin's lymphoma and lactic acidosis.

Lactic acidosis is a rare complication of haematological malignancies with a poor prognostic outcome and unclear aetiology. Possible mechanisms include high rate of glycolysis by cancer cells, in part due to over-expression of hexokinase II. The insulin-like growth factor (IGF)-system has an important role in normal as well as tumour cell growth. We present a case of a 79-year-old man with a diffuse large B-cell lymphoma and lactic acidosis. Initially, the patient was successfully treated according to the R-CHOP scheme. After recurrence of disease, the patient was treated according to a protocol of the Dutch-Belgian Haemato-Oncology Group (HOVON-85 study). Eleven months after completion of the last therapy, the patient still appeared to be in complete remission. Serum levels of IGFs, pro-IGF-IIE[68-88], IGF binding proteins (IGFBPs)-1 to -4, acid labile subunit (ALS), as well as ternary IGF-I-IGFBP-3-ALS complex formation, were determined in samples taken before, during and after treatment, respectively. Before treatment patient's serum concentration of the growth hormone-dependent parameters of the IGF-system and IGF-II were clearly reduced when compared with patient's values during remission of disease. On the other hand, during acidosis a relatively higher proportion of IGFs is present in binary complexes, instead of 150 kDa complexes, that may allow an increased access of IGFs to target cells including the malignant ones. Pretreatment serum levels of IGFBP-1 and -2 were elevated, decreased during therapy and normalized at remission. Especially IGFBP-2 seems a suitable marker for disease activity.