Bradley S. Miller

Type I insulin-like growth factor receptor as a therapeutic target in cancer.

Data from experimental model systems and population studies have implicated type I insulin-like growth factor receptor (IGF1R) signaling in many different human cancers. Drugs to disrupt IGF1R function have been developed and are now entering clinical trial. This brief review will identify key areas to consider as these clinical trials move forward.

ACTIVATION OF C-JUN N-TERMINAL KINASE/STRESS-ACTIVATED PROTEIN KINASE IN PRIMARY GLIAL CULTURES

Glial cells in the mammalian CNS are subject to environmental stress resulting from a variety of neuropathological conditions. In this study, we have examined the activation of a stress signal responsive kinase, i.e., stress‐activated protein kinase (SAPK) or c‐Jun N‐terminal kinase (JNK), in primary cultures of rat brain glial cells (i.e., astrocytes and oligodendrocytes) and an oligodendrocyte progenitor cell line, CG4, in response to cytokines and other stress inducers. JNK/SAPK activity was measured by an immune complex kinase assay using polyclonal anti‐JNK antibodies along with GST c‐Jun (1‐79) as the substrate. Among the cytokines tested, TNF‐α had the strongest effect on JNK activation followed by TNF‐β in both the glial cell types while a substantial level of kinase activation was observed in response to IL‐1 in astrocytes. JNK activation by TNF‐α in astrocytes, but not in oligodendrocytes, showed a biphasic response. An in‐gel kinase assay of cell extracts and immunoprecipitated JNK confirmed the activation of JNK1 in cells treated with TNF‐α. JNK was also activated by several other stress‐inducing factors including UV light, heat shock, inhibitors of protein synthesis, and mechanical injury. Incubation of cells with bacterial sphingomyelinase and a cell‐permeable ceramide stimulated JNK activity, suggesting that the ceramide pathway may play a role in JNK activation, although the time course of activation did not correspond to that of TNF‐α. The results are discussed in terms of possible roles of JNK activation in signaling for gliosis in astrocytes and as a protective/toxic response in oligodendrocytes.

Growth and endocrine function in patients with Hurler syndrome after hematopoietic stem cell transplantation.

Short stature is characteristic of Hurler syndrome, or mucopolysaccharidosis type IH (MPS IH). Hematopoietic stem cell transplantation (HSCT) is used to treat children with MPS IH. While HSCT corrects some of the metabolic features of MPS IH, its effects on growth are not well delineated. We investigated growth in patients with MPS IH after HSCT and described accompanying endocrine abnormalities. A cohort of 48 patients with MPS IH who had received HSCT between 1983 and 2005 were included. The prevalence of short stature (height <−2 s.d. score, SDS) before HSCT was 9%, and increased to 71% at last follow-up (6.9±5.1 years after HSCT). Short stature was positively associated with increased age at HSCT (P=0.002) and TBI (P=0.009). In total, 23% had growth hormone deficiency and/or low insulin-like growth factor-1, one female patient had premature adrenarche, one precocious puberty and 27% had clinical or subclinical hypothyroidism. Growth failure is highly prevalent in children with MPS IH after HSCT. Children who had no TBI exposure and were younger at the time of HSCT had a better height outcome.

Delayed platelet recovery after allogeneic transplantation: a predictor of increased treatment-related mortality and poorer survival

Delayed platelet recovery (DPR) is common after allo-SCT. Insufficient data on risk factors and association with OS and TRM are available. We conducted a retrospective analysis of all allografts at the University of Minnesota between 2000 and 2005 to characterize the frequency of DPR (platelets <50 000/μL by day 60), risk factors and related complications. A total of 850 patients with hematological malignancies and benign disorders were included. Myeloablative (MA) conditioning was used in 65% of the patients and 45% received umbilical cord blood (UCB) grafts. The 60-day cumulative incidence of platelet recovery was 40% in UCB, 57% in unrelated donor (URD) and 74% in sibling donor. Multivariate analysis confirmed that the variables associated with DPR were MA (versus reduced intensity) conditioning, graft source other than sibling donor, ABO major mismatch, recipient CMV-positive serostatus, the presence of grade II–IV acute GVHD and slower neutrophil recovery. These data demonstrate that DPR is frequent after allogeneic hematopoietic cell transplantation, especially after UCB. DPR is a significant independent risk factor for increased TRM and poorer OS along with HLA-mismatched URD, but not UCB, grade II–IV acute GVHD, old age and advanced disease stage.

Risk of Neoplasia in Pediatric Patients Receiving Growth Hormone Therapy--A Report From the Pediatric Endocrine Society Drug and Therapeutics Committee.

CONTEXT GH and IGF-1 have been shown to affect tumor growth in vitro and in some animal models. This report summarizes the available evidence on whether GH therapy in childhood is associated with an increased risk of neoplasia during treatment or after treatment is completed. EVIDENCE ACQUISITION A PubMed search conducted through February 2014 retrieved original articles written in English addressing GH therapy and neoplasia risk. Subsequent searches were done to include additional relevant publications. EVIDENCE SYNTHESIS In children without prior cancer or known risk factors for developing cancer, the clinical evidence does not affirm an association between GH therapy during childhood and neoplasia. GH therapy has not been reported to increase the risk for neoplasia in this population, although most of these data are derived from postmarketing surveillance studies lacking rigorous controls. In patients who are at higher risk for developing cancer, current evidence is insufficient to conclude whether or not GH further increases cancer risk. GH treatment of pediatric cancer survivors does not appear to increase the risk of recurrence but may increase their risk for subsequent primary neoplasms. CONCLUSIONS In children without known risk factors for malignancy, GH therapy can be safely administered without concerns about an increased risk for neoplasia. GH use in children with medical diagnoses predisposing them to the development of malignancies should be critically analyzed on an individual basis, and if chosen, appropriate surveillance for malignancies should be undertaken. GH can be used to treat GH-deficient childhood cancer survivors who are in remission with the understanding that GH therapy may increase their risk for second neoplasms.

Gestational-neonatal iron deficiency suppresses and iron treatment reactivates IGF signaling in developing rat hippocampus.

Gestational-neonatal iron deficiency, a common micronutrient deficiency affecting the offspring of more than 30% of pregnancies worldwide, leads to long-term cognitive and behavioral abnormalities. Preclinical models of gestational-neonatal iron deficiency result in reduced energy metabolism and expression of genes critical for neuronal plasticity and cognitive function, which are associated with a smaller hippocampal volume and abnormal neuronal dendrite growth. Because insulin-like growth factor (IGF) modulates early postnatal cellular growth, differentiation, and survival, we used a dietary-induced rat model to assess the effects of gestational iron deficiency on activity of the IGF system. We hypothesized that gestational iron deficiency attenuates postnatal hippocampal IGF signaling and results in downstream effects that contribute to hippocampal anatomic and functional deficits. At postnatal day (P) 15 untreated gestational-neonatal iron deficiency markedly suppressed hippocampal IGF activation and protein kinase B signaling, and reduced neurogenesis, while elevating extracellular signal-regulated kinase 1/2 signaling and hypoxia-inducible factor-1α expression. Iron treatment beginning at P7 restored IGF signaling, increased neurogenesis, and normalized all parameters by the end of rapid hippocampal differentiation (P30). Expression of the neuron-specific synaptogenesis marker, disc-large homolog 4 (PSD95), increased more rapidly than the glia-specific myelination marker, myelin basic protein, following iron treatment, suggesting a more robust response to iron therapy in IGF-I-dependent neurons than IGF-II-dependent glia. Collectively, our findings suggest that IGF dysfunction is in part responsible for hippocampal abnormalities in untreated iron deficiency. Early postnatal iron treatment of gestational iron deficiency reactivates the IGF system and promotes neurogenesis and differentiation in the hippocampus during a critical developmental period.

Application of Ultrasound for Bone Age Estimation in Clinical Practice

OBJECTIVE To assess the validity of bone age assessment by ultrasonography (US). STUDY DESIGN Wrist US was performed on children (n = 100) undergoing radiographic bone age and compared with bone age estimation by a radiologist in the clinic and by endocrinologists under blinded conditions with Greulich and Pyle (GP) and Tanner and Whitehouse (TW3) methods. RESULTS The strongest correlation (r(2)) was seen in the radiographic bone age assessment between the 2 endocrinologists using the GP method (96.7%). The poorest correlation was seen when comparing radiographic methods to US of either wrist (74.6% to 82.6%). When bone age correlations were divided into normal, delayed or advanced, the highest correlation between the radiographic and US methods was found in the normal bone age group (80.9% to 86.1%) with weaker correlations for the delayed bone age group (77.1% to 86.9%) and the advanced bone age group (62.2% to 81.1%). US tended to overread delayed bone age and underread advanced bone age. US had poor positive and negative predictive value for identification of a normal or delayed bone age. The negative predictive value of US was 91% for an advanced bone age. CONCLUSIONS On the basis of our data, US assessment should not yet be considered a valid replacement for radiographic bone age determination.

New disorders in carbohydrate metabolism: Congenital disorders of glycosylation and their impact on the endocrine system

Protein glycosylation occurs in all cells. It can be used to insure proper folding of nascent proteins, impart protease resistance, dictate intracellular trafficking, cellsubstratum and cell-cell specific interactions, leukocyte trafficking, and growth regulation [1–9]. For some proteins, a highly specific sugar chain is essential for function. In others, complete absence of any glycosylation seems inconsequential [10,11]. Glycoproteins are involved in virtually every endocrine axis. Protein glycosylation can affect the stability, binding affinity and ligand specificity of polypeptide hormones, hormone carrier proteins and hormone receptors. Therefore, an abnormality of protein glycosylation would be expected to have an impact on many endocrine functions. In this review of the Congenital Disorders of Glycosylation (CDG) we cover the basics of protein Nglycosylation and the known types of CDG. Then we focus on endocrine functions of CDG patients and attempt to describe and interpret the effect of hypoglycosylation on these complex processes. In addition, we hope to make physicians in the fields of endocrinology and metabolic diseases more aware of the broad spectrum of these disorders.

Iron Deficiency in International Adoptees from Eastern Europe

OBJECTIVE To assess iron deficiency (ID) in international adoptees after adoption. STUDY DESIGN Participants (n = 37) were adopted into the United States from Eastern Europe before they were 24 months of age. Baseline (within 1 month post-adoption) and follow-up (6 months post-adoption) assessments included routine post-adoption clinical evaluations, anthropometrics, dietary intakes, and iron measures (hemogram and serum analysis). RESULTS At adoption and follow-up, mean percent transferrin saturation and mean corpucuscular volume were low compared with the US population. Mean serum ferritin concentration became lower than the US population at follow-up, although the mean daily iron intake was more than the Recommended Dietary Allowance. Participants with Giardia lamblia at baseline had more compromised iron status at baseline and follow-up. Growth rate (change in z-score/months between assessments) was negatively correlated with change in serum ferritin concentrations between baseline and follow-up (r = -0.34; P < .05). CONCLUSIONS International adoptees had compromised iron status, with ID more prevalent in participants with G lamblia, a parasite that may interfere with iron absorption. The persistent ID at follow-up was likely caused by the erythropoietic demands of catch-up growth.

Pregnancy associated plasma protein-A is necessary for expeditious fracture healing in mice

Pregnancy-associated plasma protein A (PAPP-A), a metalloproteinase that regulates IGF bioavailability in vitro through cleavage of inhibitory IGF-binding protein-4 (IGFBP-4), has been implicated in skeletal development and injury repair responses. However, direct in vivo data are lacking. In this study, we used PAPP-A knock-out (KO) mice to determine the role of PAPP-A in fracture repair. Stabilized mid-shaft fractures were produced in femurs of 3-month-old mice. At 14 days post-fracture, complete bony bridging of the fracture callus was seen radiographically in wild-type but not in PAPP-A KO mice. Histological examination 5 to 28 days post-fracture showed reductions in the amount of intramembranous bone formation, cartilage production, endochondral ossification and remodeling in PAPP-A KO compared with wild-type mice. However, fracture healing appeared similar in both groups at 42 days post-fracture when analyzed by histology. A similar degree of healing strength in wild-type and PAPP-A KO femurs was demonstrated by mechanical testing at 28 and 42 days post-fracture. Untreated cultures of day 5 fracture calluses from wild-type mice showed robust IGFBP-4 protease activity and IGF receptor phosphorylation, whereas fracture calluses from PAPP-A KO mice had no IGFBP-4 protease activity and reduced IGF receptor phosphorylation. These data demonstrate a marked delay in fracture healing in PAPP-A KO compared with wild-type mice, and suggest that PAPP-A is necessary in the early phases of the process for expeditious fracture repair. The ability of PAPP-A to enhance local IGF action may be an important mechanism for optimizing the fracture repair response.