Oocyte-mediated suppression of follicle-stimulating hormone- and insulin-like growth factor-induced secretion of steroids and inhibin-related proteins by bovine granulosa cells in vitro: Possible role of transforming growth factor alpha

The objective was to investigate the potential role of the oocyte in modulating proliferation and basal, FSH-induced and insulin-like growth factor (IGF)-induced secretion of inhibin A (inh A), activin A (act A), follistatin (FS), estradiol (E-2), and progesterone (P-4) by mural bovine granulosa cells. Cells from 4- to 6-mm follicles were cultured in serum-free medium containing insulin and androstenedione, and the effects of ovine FSH and IGF analogue (LR3-IGF-1) were tested alone and in the presence of denuded bovine oocytes (2, 8, or 20 per well). Medium was changed every 48 h, cultures were terminated after 144 h, and viable cell number was determined. Results are based on combined data from four independent cultures and are presented for the last time period only when responses were maximal. Both FSH and IGF increased (P < 0.001) secretion of inh A, act A, FS, E-2, and P-4 and raised cell number. In the absence of FSH or IGF, coculture with oocytes had no effect on any of the measured hormones, although cell number was increased up to 1.8-fold (P < 0.0001). Addition of oocytes to FSH-stimulated cells dose-dependently suppressed (P < 0.0001) inh A (6-fold maximum suppression), act A (5.5-fold), FS (3.6-fold), E-2 (4.6-fold), and P-4 (2.4-fold), with suppression increasing with FSH dose. Likewise, oocytes suppressed (P < 0.001) IGF-induced secretion of inh A, act A, FS, and E-2 (P < 0.05) but enhanced IGF-induced P-4 secretion (1.7-fold; P < 0.05). Given the similarity of these oocyte-mediated actions to those we observed previously following epidermal growth factor (EGF) treatment, we used immunocytochemistry to determine whether bovine oocytes express EGF or transforming growth factor (TGF) alpha. Intense staining with TGFalpha antibody (but not with EGF antibody) was detected in oocytes both before and after coculture. Experiments involving addition of TGFalpha to granulosa cells confirmed that the peptide mimicked the effects of oocytes on cell proliferation and on FSH- and IGF-induced hormone secretion. These experiments indicate that bovine oocytes secrete a factor(s) capable of modulating granulosa cell proliferation and responsiveness to FSH and IGF in terms of steroidogenesis and production of inhibin-related peptides, bovine oocytes express TGFalpha but not EGF, and TGFalpha is a prime candidate for mediating the actions of oocytes on bovine granulosa cells.

Hepatic mRNA expression and plasma levels of insulin-like growth factor-I (IGF-I) in broiler chickens selected for different growth rates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Glucose,cholesterol,total proteins and insulin-like growth factor typeI values in the follicular fluid of female river buffaloes (Bubalus bubalis)

Twenty six Murrah female river buffaloes, between 45 and 70 d post-partum, empty, multiparae, with an average live weight of 675 ± 56 kg, and average body condition of 3.5 points, in a 1 to 5 scale, were used to determine the concentrations of glucose, cholesterol, total protein and insulin-like growth factor type I(IGF-I) in the follicular fluid. The fluid was collected from dominant follicles, with diameters between 8 and 12 mm, by in vivo follicular aspiration. The oestrous cycle stage was not taken into account. The wave of follicular development was synchronized six days prior to the collection. Biochemical analyses of glucose and cholesterol were performed by the enzymatic colorimetric method with the utilization of commercial kits of Glicose (GOD-PAP) and Cholesterol (CHOD-PAP) (Kovalent), respectively. For the determination of total protein, the commercial kit total Protein (Kovalent), method Biuret, was employed. Readings were carried out through absorption spectrophotometry with visible light. Through the radioimmunoanalysis (RIA) technique the concentration of IGF-I was obtained using commercial kits of IRMA IGF-I (IMMUNOTECH). Descriptive statistics was used, by applying the PROC MEANS procedure of the SAS (2009) statistical package. Glucose concentrations (4.0 ± 0.75 mmol/L) and IGF-I (340 ± 129.83 ng/mL) showed higher values in female river buffaloes and dairy cows regarding those reported in other studies. However, cholesterol levels (0.51 ± 0.12 mmol/L) and total proteins (58.4 ± 4.43 g/L) were lower. Results indicate that there is a relationship between the concentration of biochemical indicators, the nutritional aspects, the diameter of the aspired follicles and the productive period.

Lyophilized bovine colostrum as a source of immunoglobulins and insulin-like growth factor for newborn goat kids

The objective of this study was to evaluate lyophilized bovine colostrum as an alternative source of passive immunity and insulin like growth factor I (IGF-I) for goat kids, considering newborns consuming non-maternal colostrum. Twenty-nine male newborns received 5% of body weight of lyophilized bovine (LBC) or goat colostrum (GC), both with 55 mg/mL of IgG, at 0, 7 and 14 h of life. Blood samples were collected at 0, 7, 14, 18, 24, 36, 48, 72 and 96 h of life to determine serum IgG, total protein (TP), IGF-I and apparent efficiency of IgG absorption at 7, 14, 18 and 24 h (AEA(7hr), AEA(14hr), AEA(18hr), AEA(total), respectively). In LBC, the values of serum IgG at 14, 18,24 and 48 h (13.1, 13.4, 14.1 and 14.6 mg/mL, respectively) were higher than the values at 0 and 7 h (0.04 and 6.9 mg/mL, respectively). In GC, the serum IgG at 18 h (9.3 mg/mL) was higher than the value at 7 h (5.5 mg/mL). AEA(7hr) and AEA(14hr) in LBC were the same (19.2 and 18.5%, respectively, P>0.05) and the values of AEA(18hr) and AEA(total), 9.3 and 9.5%, respectively, were equal and smaller than AEA(7hr), and AEA(14hr). In GC, AEA(7hr), 20.8%, was higher than AEA(14hr), 16.1% (P<0.05) and AEA(18hr), and AEA(total), 9.2 and 8.0%, respectively, were equal and smaller than AEA(7hr) and AEA(14hr). The serum TP and IGF-I were not affected by colostrum feeding. Considering the variables study in the present work, lyophilized bovine colostrum constitutes a promising alternative substitute to goat colostrum in newborn goat kids, since the supply of immunoglobulins and IGF-I was suitable for the kids. (c) 2012 Elsevier B.V. All rights reserved.

Progression to Adrenocortical Tumorigenesis in Mice and Humans through Insulin-Like Growth Factor 2 and beta-Catenin

Dysregulation of the WNT and insulin-like growth factor 2 (IGF2) signaling pathways has been implicated in sporadic and syndromic forms of adrenocortical carcinoma (ACC). Abnormal beta-catenin staining and CTNNB1 mutations are reported to be common in both adrenocortical adenoma and ACC, whereas elevated IGF2 expression is associated primarily with ACC. To better understand the contribution of these pathways in the tumorigenesis of ACC, we examined clinicopathological and molecular data and used mouse models. Evaluation of adrenal tumors from 118 adult patients demonstrated an increase in CTNNB1 mutations and abnormal beta-catenin accumulation in both adrenocortical adenoma and ACC. In ACC, these features were adversely associated with survival. Mice with stabilized beta-catenin exhibited a temporal progression of increased adrenocortical hyperplasia, with subsequent microscopic and macroscopic adenoma formation. Elevated Igf2 expression alone did not cause hyperplasia. With the combination of stabilized beta-catenin and elevated Igf2 expression, adrenal glands were larger, displayed earlier onset of hyperplasia, and developed more frequent macroscopic adenomas (as well as one carcinoma). Our results are consistent with a model in which dysregulation of one pathway may result in adrenal hyperplasia, but accumulation of a second or multiple alterations is necessary for tumorigenesis. (Ant J Pathol 2012, 181:1017-1033; http://dx.doi.org/10.1016/j.ajpath.2012.05.026)

Insulin-like growth factor-I treatment in primary growth hormone insensitivity: effect of recombinant human IGF-I (rhIGF-I) and rhIGF-I/rhIGF-binding protein-3 complex

Growth hormone insensitivity syndrome (GHIS) is a rare cause of growth retardation characterized by high serum GH levels, and low serum insulin-like growth factor I (IGF-I) levels associated with a genetic defect of the GH receptor (GHR) as well post-GHR signaling pathway. Based on clinical, as well as biochemical characteristics, GHIS can be genetically classified as classical/Laron's syndrome and nonclassical/atypical GHIS. Recombinant human IGF-I (rhIGF-I) treatment is effective in promoting growth in subjects who have GHIS. Further, pharmacological studies of a IGF-I compound containing a 1:1 molar complex of rhIGF-I and rhIGF-binding protein-3 (BP-3) demonstrated that the complex was effective in increasing levels of circulating total and free IGF-I and that the administration in patients with GHIS should be safe, well-tolerated and more effective than rhIGF-I on its own.

Anti insulin-like growth factor I receptor immunoliposomes: a single formulation combining two anticancer treatments with enhanced therapeutic efficiency

Context: Through overexpression and aberrant activation in many human tumors, the IGF system plays a key role in tumor development and tumor cell proliferation. Different strategies targeting IGF-I receptor (IGFI-R) have been developed, and recent studies demonstrated that combined treatments with cytostatic drugs enhance the potency of anti-IGFI-R therapies. Objective: The objective of the study was to examine the IGFI-R expression status in neuroendocrine tumors of the gastroenteropancreatic system (GEP-NETs) in comparison with healthy tissues and use potential overexpression as a target for novel anti-IGFI-R immunoliposomes. Experimental Design: A human tumor tissue array and samples from different normal tissues were investigated by immunohistochemistry. An IGFI-R antagonistic antibody (1H7) was coupled to the surface of sterically stabilized liposomes loaded with doxorubicin. Cell lines from different tumor entities were investigated for liposomal association studies in vitro. For in vivo experiments, neuroendocrine tumor xenografts were used for evaluation of pharmacokinetic and therapeutic properties of the novel compound. Results: Immunohistochemistry revealed significant IGFI-R overexpression in all investigated GEP-NETs (n = 59; staining index, 229.1 +/- 3.1%) in comparison with normal tissues (115.7 +/- 3.7%). Furthermore, anti-IGFI-R immunoliposomes displayed specific tumor cell association (44.2 +/- 1.6% vs. IgG liposomes, 0.8 +/- 0.3%; P < 0.0001) and internalization in human neuroendocrine tumor cells in vitro and superior antitumor efficacy in vivo (life span 31.5 +/- 2.2 d vs. untreated control, 19 +/- 0.6, P = 0.008). Conclusion: IGFI-R overexpression seems to be a common characteristic of otherwise heterogenous NETs. Novel anti-IGFI-R immunoliposomes have been developed and successfully tested in a preclinical model for human GEP-NETs. Moreover in vitro experiments indicate that usage of this agent could also present a promising approach for other tumor entities.

Meta-analysis and dose-response metaregression: circulating insulin-like growth factor I (IGF-I) and mortality

Context: IGF-I plays a central role in metabolism and growth regulation. High IGF-I levels are associated with increased cancer risk and low IGF-I levels with increased risk for cardiovascular disease. Objective: Our objective was to determine the relationship between circulating IGF-I levels and mortality in the general population using random-effects meta-analysis and dose-response metaregression. Data Sources: We searched PubMed, EMBASE, Web of Science, and Cochrane Library from 1985 to September 2010 to identify relevant studies. Study Selection: Population-based cohort studies and (nested) case-control studies reporting on the relation between circulating IGF-I and mortality were assessed for eligibility. Data Extraction: Data extraction was performed by two investigators independently, using a standardized data extraction sheet. Data Synthesis: Twelve studies, with 14,906 participants, were included. Overall, risk of bias was limited. Mortality in subjects with low or high IGF-I levels was compared with mid-centile reference categories. All-cause mortality was increased in subjects with low as well as high IGF-I, with a hazard ratio (HR) of 1.27 (95% CI = 1.08–1.49) and HR of 1.18 (95% CI = 1.04–1.34), respectively. Dose-response metaregression showed a U-shaped relation of IGF-I and all-cause mortality (P = 0.003). The predicted HR for the increase in mortality comparing the 10th IGF-I with the 50th percentile was 1.56 (95% CI = 1.31–1.86); the predicted HR comparing the 90th with the 50th percentile was 1.29 (95% CI = 1.06–1.58). A U-shaped relationship was present for both cancer mortality and cardiovascular mortality. Conclusions: Both low and high IGF-I concentrations are associated with increased mortality in the general population.

Oestradiol enhances plasma growth hormone and insulin-like growth factor-I concentrations and increased the expression of their receptors mRNAs in the liver of ovariectomized cows

Many metabolic hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin affect ovarian functions. However, whether ovarian steroid hormones affect metabolic hormones in cattle remains unknown. This study aimed to determine the effect of sex steroids on the plasma profiles of GH, IGF-I and insulin and their receptors in the liver and adipose tissues of dairy cows. Ovariectomized cows (n = 14) were randomly divided into four groups: control group (n = 3) was treated with saline on Day 0; oestradiol (E2) group (n = 3), with saline and 1 mg oestradiol benzoate (EB) on Day 0 and 5, respectively; progesterone (P4) group (n = 4) with two CIDRs (Pfizer Inc., Tokyo, Japan) from Day 0; and E2 + P4 group (n = 4) with two CIDRs on Day 0 that were removed on Day 6 and were immediately injected with 1 mg EB. The animals were euthanized after the experiment, and liver and adipose tissues samples were quantitatively analysed using real-time PCR for the expression of mRNA for the GH (GHR), IGF-I (IGFR-I) and insulin (IR) receptor mRNAs. Oestradiol benzoate significantly increased the number of peaks (p < 0.05), pulse amplitude (p < 0.05) and area under the curve (AUC; p < 0.01) for plasma GH; moreover, it increased plasma IGF-I concentration (p < 0.05), but it had no effect on the plasma insulin profile. P4 significantly decreased the AUC (p < 0.01), compared with the control group, whereas it did not affect the number of peaks and the amplitude of GH pulses. P4 + E2 did not affect the GH pulse profile. E2 increased the mRNA expression of GHR, IGFR-I and IR in the liver (p < 0.05), whereas both P4 and E2 + P4 did not change their expressions. Our results provide evidence that the metabolic and reproductive endocrine axes may regulate each other to ensure optimal reproductive and metabolic function.

TYPE I INSULIN-LIKE GROWTH FACTOR RECEPTOR TYROSINE KINASE AS A MOLECULAR TARGET IN MANTLE CELL LYMPHOMA

Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoid malignancy representing 5-10% of all non-Hodgkin’s lymphomas. It is distinguished by the t(11;14)(q13;q32) chromosomal translocation that juxtaposes the proto-oncogene CCND1, which encodes cyclin D1 at 11q13 to the IgH gene at 14q32. MCL patients represent about 6% of all new cases of Non-Hodgkin’s lymphomas per year or about 3,500 new cases per year. MCL occurs more frequently in older adults – the average age at diagnosis is the mid-60s with a male-to-female ratio of 2-3:1. It is typically characterized by the proliferation of neoplastic B-lymphocytes in the mantle zone of the lymph node follicle that have a prominent inclination to disseminate to other lymphoid tissues, bone marrow, peripheral blood and other organs. MCL patients have a poor prognosis because they develop resistance/relapse to current non-specific therapeutic regimens. It is of note that the exact molecular mechanisms underlying the pathogenesis of MCL are not completely known. It is reasonable to anticipate that better characterization of these mechanisms could lead to the development of specific and likely more effective therapeutics to treat this aggressive disease. The type I insulin-like growth factor receptor (IGF-IR) is thought to be a key player in several different solid malignancies such as those of the prostate, breast, lung, ovary, skin and soft tissue. In addition, recent studies in our lab showed evidence to support a pathogenic role of IGF-IR in some types of T-cell lymphomas and chronic myeloid leukemia. Constitutively active IGF-IR induces its oncogenic effects through the inhibition of apoptosis and induction of transformation, metastasis, and angiogenesis. Previous studies have shown that signaling through IGF-IR leads to the vi activation of multiple signaling transduction pathways mediated by the receptor-associated tyrosine kinase domain. These pathways include PI3K/Akt, MAP kinase, and Jak/Stat. In the present study, we tested the possible role of IGF-IR in MCL. Our results demonstrate that IGF-IR is over-expressed in mantle cell lymphoma cell lines compared with normal peripheral blood B- lymphocytes. Furthermore, inhibition of IGF-IR by the cyclolignan picropodophyllin (PPP) decreased cell viability and cell proliferation in addition to induction of apoptosis and G2/M cell cycle arrest. Screening of downstream oncogenes and apoptotic proteins that are involved in both IGF-IR and MCL signaling after treatment with PPP or IGF-IR siRNA showed significant alterations that are consistent with the cellular changes observed after PPP treatment. Therefore, our findings suggest that IGF-IR signaling contributes to the survival of MCL and thus may prove to be a legitimate therapeutic target in the future.

Insulin-associated changes in carnitine palmitoyltransferase activity are mediated through the insulin-like growth factor I pathway in the cultured neonatal rat cardiac myocyte

The mitochondrial carnitine palmitoyltransferase (CPT) system is composed of two proteins, CPT-I and CPT-II, involved in the transport of fatty acids into the mitochondrial matrix to undergo $\beta$-oxidation. CPT-I is located outside the inner membrane and CPT-II is located on the inner aspect of the inner membrane. The CPT proteins are distinct with different molecular weights and activities. The malonyl-CoA sensitivity of CPT-I has been proposed as a regulatory step in $\beta$-oxidation. Using the neonatal rat cardiac myocyte, assays were designed to discriminate between these activities in situ using digitonin and Triton X-100. With this methodology, we are able to determine the involvement of the IGF-I pathway in the insulin-mediated increase in CPT activities. Concentrations of digitonin up to 25 $\mu$M fail to release citrate synthase from the mitochondrial matrix or alter the malonyl-CoA sensitivity of CPT-I. If the mitochondrial matrix was exposed, malonyl-CoA insensitive CPT-II would reduce malonyl-CoA sensitivity. In contrast to digitonin, Triton X-100 (0.15%) releases citrate synthase from the matrix and exposes CPT-II. CPT-II activity is confirmed by the absence of malonyl-CoA sensitivity. To examine the effects of various agents on the expression and/or activity of CPT, it is necessary to use serum-free medium to eliminate mitogenic effects of serum proteins. Comparison of different media to optimize CPT activity and cell viability resulted in the decision to use Dulbecco's Modified Eagle medium supplemented with transferrin. In three established models of cardiac hypertrophy using the neonatal rat cardiac myocyte there is a significant increase in CPT-I and CPT-II activity in the treated cells. Analogous to the situation seen in the hypertrophy model, insulin also significantly increases the activity of the mitochondrial proteins CPT-I, CPT-II and cytochrome oxidase with a coinciding increase the expression of CPT-II and cytochrome oxidase mRNA. The removal of serum increases the I$\sb{50}$ (concentration of inhibitor that halves enzyme activity) of CPT-I for malonyl-CoA by four-fold. Incubation with insulin returns I$\sb{50}$ values to serum levels. Incubation with insulin significantly increases malonyl-CoA and ATP levels in the cells with a resulting reduction in palmitate oxidation. Once malonyl-CoA inhibition of CPT-I is removed by permeabilizing the cells, insulin significantly increases the oxidation of palmitoyl-CoA in a manner which parallels the increase in CPT-I activity. Interestingly, CPT-II activity increases significantly only at the tissue culture concentration (1.7 $\mu$M) of insulin suggesting that the IGF-I pathway may be involved. Supporting a role for the IGF-I pathway in the insulin-induced increase in CPT activity is the significant increase in the synthesis of both cellular and mitochondrial proteins as well as increased synthesis of CPT-II. Consistent with an IGF-mediated pathway for the effect of insulin, IGF-I (10 ng/ml) significantly increases the activities of both CPT-I and -II. An IGF-I analogue which inhibits the autophosphorylation of the IGF-I receptor blunts the insulin-mediated increase in CPT-I and -II activity by greater than 70% and virtually eliminates the IGF-I response by greater than 90%. This is the first study to demonstrate the involvement of the IGF-I pathway in the regulation of mitochondrial protein expression, e.g. CPT. ^

Regulation of human trophoblast GLUT1 glucose transporter by insulin-like growth factor I (IGF-I)

Glucose transport to the fetus across the placenta takes place via glucose transporters in the opposing faces of the barrier layer, the microvillous and basal membranes of the syncytiotrophoblast. While basal membrane content of the GLUT1 glucose transporter appears to be the rate-limiting step in transplacental transport, the factors regulating transporter expression and activity are largely unknown. In view of the many studies showing an association between IGF-I and fetal growth, we investigated the effects of IGF-I on placental glucose transport and GLUT1 transporter expression. Treatment of BeWo choriocarcinoma cells with IGF-I increased cellular GLUT1 protein. There was increased basolateral (but not microvillous) uptake of glucose and increased transepithelial transport of glucose across the BeWo monolayer. Primary syncytial cells treated with IGF-I also demonstrated an increase in GLUT1 protein. Term placental explants treated with IGF-I showed an increase in syncytial basal membrane GLUT1 but microvillous membrane GLUT1 was not affected. The placental dual perfusion model was used to assess the effects of fetally perfused IGF-I on transplacental glucose transport and syncytial GLUT1 content. In control perfusions there was a decrease in transplacental glucose transport over the course of the perfusion, whereas in tissues perfused with IGF-I through the fetal circulation there was no change. Syncytial basal membranes from IGF-I perfused tissues showed an increase in GLUT1 content. These results demonstrate that IGF-I, whether acting via microvillous or basal membrane receptors, increases the basal membrane content of GLUT1 and up-regulates basal membrane transport of glucose, leading to increased transepithelial glucose transport. These observations provide a partial explanation for the mechanism by which IGF-I controls nutrient supply in the regulation of fetal growth.

Insulin-like growth factor binding protein 2 (IGFBP2) promotes glioma development and progression

Overexpression of insulin-like growth factor binding protein 2 (IGFBP2) is associated with progression and poor survival in many types of human cancer (such as prostate, ovarian, adrenocortical, breast, colorectal carcinomas, leukemia, and high-grade gliomas). We therefore hypothesize that IGFBP2 is a key regulator of tumor progression. We tested our hypothesis in gliomas using the somatic gene transfer RCAS-tva mouse model system, which permits the introduction of specific genes into specific, cell lineages, in this case glial cells (RCAS: Replication competent avian sarcomavirus, tv-a: avian RCAS virus receptor). Mice are transgenic and harbor the tv-a receptor under the control of a glial-specific promoter and study genes are cloned into the RCAS vector for post-natal intracranial delivery. For these experiments, the study genes were IGFBP2, platelet-derived growth factor B (PDGFB), K-Ras, Akt, and IIp45 (invasion inhibitory protein 45 kDa; known to bind and block IGFBP2 activity), which were delivered separately and in combination. Our results show that PDGFB signaling leads exclusively to the formation of low-grade (WHO grade II) oligodendrogliomas. PDGFB delivered in combination with IGFBP2 results in the formation of anaplastic oligodendrogliomas (WHO grade III), which are characterized by increased cellularity, vascular proliferation, small regions of necrosis, increased mitotic activity, and increased activation of the Akt pathway. IIp45 injected in combination with PDGFB and IGFBP2 ablates IGFBP2-induced tumor progression, which results in formation of low-grade oligodendrogliomas, and an overall reduction in tumor incidence. K-Ras expression was required to form astrocytomas with either IGFBP2 or Akt, indicating the activation of two separate pathways is necessary for gliomagenesis. In ex vivo experiments, blockade of Akt by an inhibitor led to decreased viability of cells co-expressing IGFBP2 versus PDGFB expression alone. This study provides definitive evidence, for the first time, that: (1) IGFBP2 plays a role in activation of the Akt pathway, (2) IGFBP2 collaborates with K-Ras or PDGFB in the development and progression of two major types of glioma, and (3) IGFBP2-induced tumor progression can be ablated by IIp45 or by specific inhibition of the Akt pathway. ^