von Willebrand factor and development of diabetic nephropathy in IDDM

We tested the hypothesis that dysfunction of vascular endothelium, indicated by an increase in plasma level of von Willebrand factor (vWF), is present in patients with insulin-dependent diabetes mellitus (IDDM) who develop diabetic nephropathy (DN). DN was classified as absent (urinary albumin excretion [UAE] rate less than 15 microgram/min), incipient (UAE rate 15-200 micrograms/min), or clinical (UAE rate greater than 200 micrograms/min). We followed a cohort of 59 patients for a median of 3 yr. At baseline, 52 patients had no DN, 6 had incipient DN, and 1 had clinical DN. At follow-up, 38 patients had no DN (group 1). Incipient DN had developed in 14 patients and worsened in 3 patients. Clinical DN had worsened in 1 patient. Together, these 18 patients comprised group 2. A decrease in UAE was observed in the remaining three patients with incipient DN at baseline (group 3). In group 1, vWF--measured by immunoelectrophoresis and expressed as a percentage of normal--increased slightly (median 10%, range -43 to 145, P = 0.009). In group 2, vWF increased in all patients (median 80%, range 14 to 206 [corrected], P = 0.0002 vs. baseline and group 1). In group 3, vWF decreased (median -19%, range -44 to -18). After correction for possible confounders, i.e., age, varying duration of follow-up, and initial level of vWF, the difference in vWF change between groups 1 and 2 remained significant (P = 0.009). Poor glycemic control at baseline, estimated by glycosylated hemoglobin, was a significant predictor of increases in vWF in both group 1 and groups 1 and 2 combined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Angiotensin II and growth factors in the pathogenesis of diabetic nephropathy

The renin-angiotensin system (RAS) and growth factors mediate structural and functional changes during the course of diabetic nephropathy (DN). Studies in humans and experimental models with DN suggest their involvement in the development and progression of DN. Activation of renal tissue RAS and increased expression of growth factors have been demonstrated at early stages of the disease. Angiotensin II and growth factors alter renal hemodynamics and exert trophic changes in renal cells that eventually result in fibrosis through direct mechanisms or through the release of other mediators. Their effects are likely modulated by metabolic changes including high glucose and free fatty acids. While blockade of the RAS ameliorates DN in humans, such evidence for blockade of growth factors is still lacking. It is likely that susceptibility to the development of DN and therapeutic efficacy are modulated by genetic polymorphisms in components of the RAS and growth factors including their receptors and other target molecules. Approaches to understand the intricate relationship between these systems and the mechanism(s) by which they alter capillary permeability and result in structural changes are areas of fruitful investigation.     

尿酸性肾病胰岛素样生长因子和成纤维细胞生长因子的表达

目的　探讨胰岛素样生长因子 1(IGF 1)和碱性成纤维细胞生长因子 (bFGF)与尿酸性肾病病变的关系。方法　采用原位杂交和免疫组织化学 (免疫组化 )方法 ,观察 30只腺嘌呤致尿酸性肾病模型大鼠肾病变发展过程中 ,IGF 1、bFGF、FGF受体 1(FGFR 1)、增殖细胞核抗原 (PCNA)及Ⅲ型胶原的表达。结果　受损伤及再生肾小管上皮细胞和肉芽肿内单个核细胞均有IGF 1mRNA和bFGFmRNA表达及蛋白合成 ,FGFR 1、PCNA和Ⅲ型胶原也广泛表达 ;肾小管间质bFGFmRNA和蛋白、FGFR 1、PCNA和Ⅲ型胶原阳性细胞随病程逐渐增多。结论　尿酸结晶对肾小管的损伤刺激IGF 1、bFGF在肾内表达增强且范围扩大 ,其表达程度与肾病变程度一致 ,提示IGF 1和bFGF在尿酸性肾病发展过程中发挥了重要作用。     

Insulin and insulin-like growth factors in central nervous system tumors. Part V: Production of insulin-like growth factors I and II in vitro.

The authors have previously reported the presence of insulin-like growth factor (IGF) receptors in central nervous system (CNS) tumors and the production of IGF's and their binding proteins by CNS tumors in situ. This study was designed to investigate whether CNS tumor cells are capable of autocrine secretion of IGF-I and IGF-II in vitro. Production of IGF's was studied by specific radioimmunoassay of tumor-cell-conditioned serum-free media from 34 CNS tumors: 12 gliomas, 12 meningiomas, and 10 miscellaneous tumors. Normal human serum and cerebrospinal fluid served as controls. Insulin-like growth factor I was detected in five of 12 meningiomas but in none of the gliomas studied. In contrast, IGF-II was detected in four of 12 gliomas and in six of 11 meningiomas studied. Four miscellaneous tumors produced IGF-I and/or IGF-II. These results suggest that CNS tumors differentially produce IGF-I and IGF-II in vitro. Preferential production of IGF's may be an important marker of the tumor-cell differentiation or malignancy and may be useful as a clinical diagnostic tool. These results add further support to the concept that IGF's may play a role in the regulation of the behavior of CNS tumors.     

Characterization of insulin-like growth factor I and epidermal growth factor receptors in meningioma

Receptors for insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) were localized and characterized in eight samples of human meningioma (four fibrous, two meningothelial, and two angioblastic types), using quantitative autoradiographic techniques. Effects of both growth factors on deoxyribonucleic acid (DNA) synthesis in the cultured meningioma cells were examined. High numbers of specific binding sites for both IGF-I and EGF were homogeneously present in tissue sections derived from fibrous and meningothelial types of meningiomas, whereas binding sites for these growth factors were not detectable in adjacent leptomeninges. While relatively large numbers of IGF-I binding sites were located in the wall of the intratumoral vasculature, the number of binding sites in the stromal component was lower in angioblastic-type meningiomas, including a low number of EGF binding sites detected only in the stromal portion. Scatchard analysis revealed the presence of a single class of high-affinity binding sites for both IGF-I and EGF in the meningiomas examined (dissociation constant (Kd) = 0.6 to 2.9 nM, and the maximum number of binding sites (Bmax) = 16 to 80 fmol/mg for IGF-I; and Kd = 0.6 to 4.0 nM, Bmax = 3 to 39 fmol/mg for EGF). Both growth factors increased the synthesis of DNA, in a dose-dependent manner, as measured by 3H-thymidine incorporation. The combination of IGF-I and EGF synergistically stimulated the synthesis of DNA, and the effects seen with 10% fetal bovine serum could be reproduced at a concentration of 10(-10) M. These observations can be interpreted to mean that both IGF-I and EGF may be involved in the growth modulation of meningiomas, possibly through paracrine or autocrine mechanisms.     

Preparation of cultured skin for transplantation using insulin-like growth factor I in conjunction with insulin-like growth factor binding protein 5, epidermal growth factor, and vitronectin

BACKGROUND: Cultured skin for transplantation is routinely prepared by growing patient keratinocytes in the presence of semidefined sources of growth factors including serum and feeder cells, but these materials require substantial risk remediation and can contribute to transplant rejection. METHODS: We have therefore investigated the potential of a novel combination of recombinant and purified growth factors to replace serum and feeder cells in cultures of human keratinocytes suitable for clinical application. Our technique was investigated with respect to culture establishment, serial propagation, colony-forming efficiency, immunocytochemistry, epidermal reconstruction, and suitability to support transplantation by aerosolization. RESULTS: We demonstrate that insulin-like growth factor (IGF)-I--used in conjunction with epidermal growth factor (EGF), insulin-like growth factor binding protein (IGFBP)-5 and vitronectin--supports growth in the absence of serum. Moreover, a threefold greater number of cells are generated within 7 days compared to those grown under current best practice conditions using serum (P<0.05). The resulting test cultures are suitable for epidermal reconstruction and support the option for delivery in the form of an aerosolized cell suspension. Serial propagation, with the view to producing confluent sheets for extensive injuries, was achieved but with less consistency and this result correlated with a significant decline in colony-forming efficiency compared to controls. CONCLUSIONS: IGF-I used in conjunction with IGFBP-5, EGF, and vitronectin provides a superior alternative to serum for the rapid expansion and transplantation of cultured keratinocytes within the first week of treatment. Nevertheless, further optimization is required with respect to elimination of feeder cells and serial expansion of cultures for treatment of extensive injuries.     

Risk factors for development of diabetic nephropathy and retinopathy in Jewish IDDM patients

Risk factors associated with diabetic microvascular complications, with special reference to ethnic origin, were looked for in 231 young Jewish insulin-dependent diabetes mellitus (IDDM) patients with duration of diabetes greater than or equal to 10 yr. Median age at diagnosis of diabetes was 9.2 yr (range 0.04-26.2 yr), and median duration of the disease was 15.3 yr (range 10.0-37.2 yr). Sixty-three percent of the patients were Ashkenazi Jews, and 37% were non-Ashkenazi Jews. HbA1 was evaluated every 3 mo in the last 10 yr of follow-up, and albumin excretion rate was tested in three 24-h urine collections. Direct and indirect ophthalmoscopy was performed every year since diagnosis of diabetes, and if retinal pathology was suspected, color photographs were taken. Microalbuminuria was detected in 31% and macroalbuminuria in 7% of the patients. Nonproliferative and proliferative retinopathy was found in 44 and 12% of the patients, respectively. On logistic regression analysis, two variables were significantly and independently associated with diabetic nephropathy--non-Ashkenazi origin and mean HbA1 values over the first 5 of 10 yr of follow-up. Variables significantly and independently related to diabetic retinopathy were non-Ashkenazi origin, mean HbA1 values over the last 10 yr of follow-up, and duration of diabetes. Because non-Ashkenazi Jews in Israel are of lower socioeconomic status than Ashkenazi Jews, we stratified our patients according to their socioeconomic parameters, median HbA1 values, and duration of diabetes. Non-Ashkenazi patients were at a higher risk to develop complications in all strata.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circulating levels of insulin-like growth factor binding protein 3 (IGFBP-3) and insulin-like growth factor I (IGF-I) in perimenopausal women

The study investigated possible menopause-related changes in circulating insulin-like growth factor binding protein 3 (IGFBP-3) levels and their relationship with insulin-like growth factor I (IGF-I) plasma levels. Forty-three healthy women, aged 45–55 years, were studied (22 premenopausal and 21 postmeno-pausal, matched for age and body mass index); in all subjects plasma IGF-I and IGFBP-3 levels were measured by radioimmunoassay. No difference was found between mean IGFBP-3 plasma levels in the two groups studied (premenopausal 3.42±0.49 v postmenopausal 3.46±0.58 mg/l), while mean IGF-I levels were significantly lower in postmenopausal as compared with premenopausal women (136.7±37.86 v 175.7±51.91 ng/ml,p<0.02). Multiple regression analysis showed no significant effect of age, body mass index and years since menopause on IGFBP-3 levels; however, considering the IGF-I/IGFBP-3 ratio as a possible parameter of circulating free somatomedin C, an inverse correlation was found with years since menopause (n=43,r=–0.499,p<0.001). We conclude that lack of oestrogen induces different effects on circulating IGF-I and IGFBP-3, possibly reflecting a real decrease in IGF-I activity.     

Gene expression of insulin-like growth factors I and II in rat membranous osteotomy healing.

Poorly healing mandibular osteotomies can be a difficult problem in reconstructive surgery. Many therapies have been attempted to augment the healing of mandibular fractures, defects, or osteotomies, but these methods have substantial drawbacks or have been ineffective. The difficulty in treating poorly healing bony defects has led to the exploration of gene therapy as a possible approach to supplement or accelerate mandibular fracture healing. To understand at what point the introduction of a suitable gene candidate might be of benefit in mandibular healing, it is imperative to examine the temporal expression of bone growth factors in a model of membranous bone healing. Insulinlike growth factors (IGFs) I and II are two such bone growth factor candidates because of their known potent in vitro as well as in vivo effects on bone formation. In this study the authors demonstrate the temporal pattern of IGF I and IGF II gene expression during mandibular osteotomy healing using a rat model. Their data reveal that IGF I and IGF II were elevated 7 days after a mandibular osteotomy that was held in external fixation. The upregulation of IGF I and IGF II during mandibular bone healing underscores the importance of these growth factors in bone repair. Gene therapy utilizing recombinant viral constructs containing IGFs I and II may be of benefit during mandibular bone healing in an effort to augment clinical scenarios of poor or retarded bony repair.     

Co-localization of insulin-like growth factor binding protein 3 and fibronectin in human articular cartilage

OBJECTIVE: The anabolic cytokine insulin-like growth factor I (IGF-I) stimulates chondrocyte synthesis of matrix macromolecules and several lines of evidence suggest that it has a major role in maintaining articular cartilage and possibly in cartilage repair. Despite the apparent importance of IGF-I in articular cartilage metabolism and its potential importance in joint diseases, little is known about the regulation of IGF-I activity within the tissue. Insulin-like growth factor binding proteins (IGFBPs) bind IGF-I and can modify its activity. At least three IGFBPs are expressed by chondrocytes: IGFBP-3, -4 and -5. Localization of IGFPBs in the articular cartilage extracellular matrix (ECM) could create reservoirs of IGF-I within the articular cartilage ECM and thereby regulate local IGF-I levels. We hypothesized that ECM molecules bind and concentrate IGFPBs in the pericellular/territorial matrix. DESIGN: Semi-quantitative immunohistological measures of co-localization were used to compare the spatial distribution of IGFBP-3, -4, and -5 with the distributions of three peri-cellularly-enriched matrix molecules fibronectin, tenascin-C, and type VI collagen in osteoarthritic and non-osteoarthritic human articular cartilage. Purified proteins were used in an agarose diffusion assay to compare IGFBP-3 binding to the same three matrix proteins. RESULTS: IGFBP-3 associated with fibronectin in the pericellular/territorial matrix (approximately 40% co-localization) but not with tenascin-C, or type VI collagen (approximately 6% and approximately 15% co-localization respectively, P< 0.05). Neither IGFBP-4, nor IGFBP-5 were associated with any of the three ECM proteins (P< 0.05). In agarose diffusion assays IGFBP-3 interacted with fibronectin and heparan sulfate proteoglycan but not with type VI collagen or tenascin-C. CONCLUSIONS: Direct binding between purified IGFBP-3 and fibronectin and the strong co-localization the two proteins in the cartilage matrix support the hypothesis that IGFPB-3 and fibronectin help regulate local IGF-I levels.     

Differential distribution of insulin-like growth factor-1 and insulin-like growth factor binding proteins in experimental diabetic rat kidney

Insulin-like growth factor-1 (IGF-1) is a peptide growth factor, and its activity is modulated by interaction with the family of IGF binding proteins (IGFBP-1 to 6). IGF-1 is detected in rat kidney and has metabolic and growth effects. To explore the possible involvement of IGFBPs in glomerular hypertrophy in streptozotocin (STZ)-induced diabetic rat, the immunolocalization of IGF-1 and IGFBPs were investigated. IGF-1 was gradually increased in the glomeruli of diabetic rats and correlated with glomerular hypertrophy. IGFBP-1 was transiently increased at 1 week after the STZ injection and declined to control level during the following period. In contrast, IGFBP-4 was increased in the diabetic glomeruli throughout the observation period. With insulin treatment, the levels of IGF-1, IGFBP-1 and 4 were normalized and glomerular hypertrophy was prevented. Initial glomerular hypertrophy of diabetic nephropathy is a related IGF-1 action, which may be modulated by IGFBP-1 and 4.     

Cellular basis of diabetic nephropathy: II. The transforming growth factor-beta system and diabetic nephropathy lesions in type 1 diabetes

Transforming growth factor-beta (TGF-beta) may be critical in the development of diabetic nephropathy (DN), and genetic predisposition is an important determinant of DN risk. We evaluated mRNA expression levels of TGF-beta system components in cultured skin fibroblasts (SFs) from type 1 diabetic patients with fast versus slow development of DN. A total of 125 long-standing type 1 diabetic patients were ranked by renal mesangial expansion score (MES) based on renal biopsy findings and diabetes duration. Patients in the highest quintile of MES who were also microalbuminuric or proteinuric (n = 16) were classified as "fast-track" for DN, while those in the lowest quintile who were also normoalbuminuric (n = 23) were classsified as "slow-track" for DN. Twenty-five normal subjects served as control subjects. SFs were cultured in medium with 25 mmol/l glucose for 36 h. SF mRNA expression levels for TGF-beta1, TGF-beta type II receptor (TGF-beta RII), thrombospondin-1, and latent TGF-beta binding protein-1 (LTBP-1) were measured by real-time RT-PCR. LTBP-1 mRNA expression was reduced in slow-track (0.99 +/- 0.38) versus fast-track patients (1.65 +/- 0.52, P = 0.001) and control subjects (1.41 +/- 0.7, P = 0.025). mRNA levels for TGF-beta1, TGF-beta RII, and thrombospondin-1 were similar in the three groups. Reduced LTBP-1 mRNA expression in SFs from slow-track patients may reflect genetically determined DN protection and suggests that LTBP-1 may be involved in the pathogenesis of DN through the regulation of TGF-beta activity.     

Regulation of transforming growth factor beta in diabetic nephropathy: implications for treatment

The recognition that the drivers of matrix accumulation is an appropriate therapeutic target for diabetic nephropathy is now accepted by the nephrology and pharmaceutical communities. Interventions focused around transforming growth factor-beta (TGF-beta) likely will be an important area of clinical investigation in the near future. Understanding the various pathways involved in stimulating TGF-beta in the diabetic kidney is of paramount importance in devising strategies to combat the development and progression of diabetic nephropathy. In this review we highlight the major pathways involved in stimulating TGF-beta production by increased glucose levels and discuss the therapeutic implications thereof.     

Mitogenic activity and receptor reactivity of hybrid molecules containing portions of the insulin-like growth factor I (IGF-I), IGF-II, and insulin molecules

Insulin and the insulin-like growth factors IGF-I and IGF-II are thought to exert their mitogenic effects in cultured chick embryo fibroblasts and human skin fibroblasts via IGF receptors rather than via insulin receptors. These effects appear to be mediated by the type I subtype of IGF receptor, which is structurally similar to the insulin receptor and exhibits significant cross-reactivity with insulin. As a first step in our long-range goal of defining those features of the IGF-I and IGF-II molecules that confer enhanced mitogenic activity and reactivity with these mitogenic type I IGF receptors, we have prepared two hybrid insulin-IGF molecules and examined their mitogenic and binding activities: (1) A27-insulin, containing an elongated 27-residue A-chain (in which the 6-residue D-domain of IGF-II was added to the carboxy-terminus of the 21-residue A-chain of insulin) combined with the B-chain of insulin; and (2) A insulin-B IGF-1, containing the A-chain of insulin and the synthetic 30-residue B-domain of IGF-I. Both hybrid molecules stimulated DNA synthesis and inhibited 125I-IGF-I binding to type I IGF receptors in both chick embryo and human fibroblast cultures. A27-insulin had considerably greater mitogenic potency and binding potency than A insulin-B IGF-I. Neither hybrid molecule was more potent in these assays than insulin, indicating that the presence of D IGF-II or B IGF-I by itself was not sufficient to increase the mitogenic potency of insulin in fibroblasts. By contrast, A insulin-B IGF-I showed enhanced reactivity with an antiserum to IGF-I. A27-insulin retained significant insulin-like metabolic activity despite the presence of the D-domain of IGF-II.     

Association between the levels of serum inflammatory cytokines high-mobility group box-1, insulin-like growth factor-1, vascular endothelial growth factor 165 and progression of diabetic nephropathy

Objectives To determine the association between serum levels of high-mobility group box-1 (HMGB1), insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor 165 (VEGF165) and occurrence and development of diabetic nephropathy (DN). Methods A total of 136 patients diagnosed as diabetic nephropathy (DN group) in Huai'an First People's Hospital between January 2016 to January 2018 were randomly selected in the study, including microalbuminuria group (n=62), macroalbuminuria group (n=50) and renal insufficiency group (n=24). Meanwhile, 115 healthy examiners during the same period were collected as normal control group. Serum glucose, serum total cholesterol (TC), serum triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and urinary albumin/urine creatinine ratio (UAlb/Cr) were detected in all subjects. Enzyme-linked immunosorbent assay (ELISA) was adopted to detect the serum concentrations of HMGB1, IGF-1 and VEGF165. Pearson correlation test was used to analyze the correlation between serum HMGB1, IGF-1 and VEGF165. Logistic ordered multi-classification regression was used to analyze the risk factors of DN progression, and the receiver operating characteristic curve (ROC) was drawn to evaluate the clinical predictive value of HMGB1, IGF-1 and VEGF165 in the progression of DN. Results The concentrations of serum HMGB1, IGF-1 and VEGF165 in DN patients were significantly higher than those in the control group (all P﹤0.05). There was a positive association between HMGB1 and IGF-1, HMGB1 and VEGF165, IGF-1 and VEGF165 (all P﹤0.01). Logistic regression analysis showed that elevated levels of HMGB1, IGF-1 and VEGF165 were independent risk factors for DN progression (OR=5.50, 1.05, 1.24, all P﹤0.05). The sensitivity, specificity and area under ROC curve of combined detection of HMGB1, IGF-1 and VEGF165 were higher than HMGB1, IGF-1 and VEGF165 alone (AUC=0.989, 0.984, 0.942, 0.878, P﹤0.05). Conclusions The serum levels of HMGB1, IGF-1 and VEGF165 are related to the severity of DN. The clinical predictive value of combined detection of HMGB1, IGF-1 and VEGF165 for DN progression is superior to that of single index detection of HMGB1, IGF-1 and VEGF165.     

Insulin-like growth factor I receptors and insulin-like growth factor-binding proteins in human parathyroid tumors

Studies have demonstrated the presence of epidermal growth factor receptors in human parathyroid tumors. However, there is little information on the effect of other peptide growth factors on parathyroid cell growth. We therefore studied the interaction of insulin-like growth factor I (IGF-I) with human parathyroid tumor cells. Parathyroid tissues were obtained from 24 patients with primary or secondary hyperparathyroidism. There were 15 solitary adenomas, 5 carcinomas, and 4 hyperplastic tissues. First, the binding of [¹²⁵I]IGF-I to the crude membrane fractions was studied by competitive inhibition with unlabeled IGF-I. Second, isolated parathyroid cells were cultured with IGF-I and examined for DNA synthesis. The IGF-binding protein (IGFBP) content of tissue homogenates was determined by ligand blot analysis. The binding of [¹²⁵I]IGF-I to parathyroid membranes was dependent on time, temperature, and pH of the medium. Maximum binding was obtained after incubation for 18 hours at 4°C. Specific binding to parathyroid cancer membranes (mean±SE, 10.75±10.55%/mg protein) was significantly (p<0.05) greater than that in adenoma tissues 3.71±2.11%/mg. The value in hyperplastic tissues (4.78±2.97%/mg) was not different from that in adenomas. Affinity cross-linking and autoradiography demonstrated the type I IGF receptors. Cultured parathyroid cells responded to IGF-I with increased DNA synthesis. The parathyroid tumor tissues expressed IGFBPs. These results suggest that IGF-I and IGFBPs are involved in the growth regulation of parathyroid tumor cells.

---

Resumen Estudios recientes han demostrado la presencia de receptores del factor de crecimiento epidérmico en tumores paratiroideos humanos. Sin embargo, existe escasa información sobre los efectos de otros factores peptídicos de crecimiento sobre el crecimiento de la célula paratiroidea. Es por ello que procedimos a estudiar la interacción del factor de crecimiento-I similar a la insulina (IGF-I) en las células de tumores paratiroideas. Los tejidos paratiroideos fueron obtenidos de 24 pacientes con hiperparatiroidismo primario o secundario; hubo 15 adenomas solitarias, 5 carcinomas y 4 tejidos hiperplásicos. En primer lugar se estudió la ligación del péptido ligado con yodo radioactivo [125-1] IGF-I, a fracciones crudas de membrana mediante la inhibicón competitiva con IGF-I no marcado. En segundo lugar se cultivaron células paratiroideas aisladas con IGF-I que fueron analizadas para síntesis de ADN. El contenido de proteína ligadora de IGF-I (IGFBP) fue determinado mediante el método ligand blot. La ligación de [125-I]IGF-I a las membranas paratiroideas demostró ser dependiente del tiempo, la temperatura y el pH del medio. Se logró la máxima ligación luego de incubación por 18 h a 4°C. La ligación especifica a las membranas del cáncer paratiroideo (10.75 [±10.55]% por mg de proteina) fue significativamente (P<0.05) mayor (P<0.05) que la de los tejidos adenomatosos (3.71±2.11). El valor para el tejido hiperplásico (4.78±2.97) no fue differente del de los adenomas. La afinidad cruzada y la autorradiografía demostraron la presencia de receptores de IGF-I. Las células paratiroideas cultivadas respondieron al IGF-I con un incremento de la síntesis de ADN. Los tejidos tumorales paratiroideos expresaron IGFBPs. Los anteriores resultados sugieren que el IGF-I y las IGFBPs se hallan involucradas en la regulación del crecimiento de las células de tumores paratiroideas.

---

Résumé Des études récentes ont démontré la présence de récepteurs de facteurs de croissance épidermiques dans les tumeurs parathyroïdes de l'homme. II existe cependant peu d'enseignement concernant l'effet des autres facteurs de crossance sur la cellule parathyroïde. Nous avons donc étudié l'interaction du facteur de croissance IGF-1 avec les cellules parathyroïdes de l'homme. Du tissu parathyroïde a été obtenu à partir de 24 patients ayant une hyperparathyroïdie primitive ou secondaire: 15 adénomes solitaires, 5 cancers et 4 parathyroïdes hyperplasiques. D'abord, on a étudié la liaison entre la GF-1[125] et des fractions de membrane brutes. On a ensuite mis en culture les cellules parathyroïdiennes isolées en présence d'IGF-1. Leur capacité de synthèse d'ADN a été mesurée. Le contenu en protéine de liaison (IGF-BP) dans les homogénéats de tissu a été déterminé par une analyse de ligand blot. La liaison de FIGF-1[125] aux membranes de la glande parathyroïde dépend du facteur temps, de la température et du pH. La liaison est maximale après une incubation de 18 h à 4°C. La liaison spécifique à la membrane de la parathyroïde cancéreuse (moyenne +/-ET [10.75 +/- 10.55]%/mg protéine) était significativement plus élevée (p<0.05) que pour les tissus d'adénome. (3.71+/-2.11). La valeur dans les tissus hyperplasiques (4.78 +/-2.97) n'étaient pas différente de celle des adénomes. Les récepteurs IGF ont pu être mis en évidence par le test d'affinité de cross-link et l'autoradiographie. La culture de cellules parathyroïdes ont répondu à l'IGF-1 par une augmentation de la synthèse d'ADN. On a trouvé que les IGF-BP sont fabriquées par les tissus parathyroïdes tumoraux. Ces résultats suggèrent que l'IGF-1 et l'IGFBP sont impliquées dans la régulation de la croissance des cellules parathyroïdes tumorales.

     

Insulin and insulin-like growth factor I in brain tumors: binding and in vitro effects

We have measured insulin and insulin-like growth factor I (IGF-I) binding in human gliomas, meningiomas, and normal brain and studied the effect of insulin on the morphology, proliferation, and differentiation of central nervous system tumor and normal fetal cells in culture. Specific 125I-insulin and 125I-IGF-I binding was demonstrated by competition-inhibition binding assays. Insulin binding was measured in plasma membrane preparations from 9 freshly isolated human meningiomas, 4 glioblastomas multiforme (GBMs), a low-grade glioma, a normal adult brain, and a fetal brain. IGF-I binding was measured in similar preparations from 5 meningiomas, 4 GBMs, a low-grade glioma, and a normal adult brain. Incubations were carried out at 4 degrees C for 18 to 20 hours. Meningiomas showed higher specific insulin binding per 0.25 mg of protein than GBMs (19% versus 3%, P less than 0.005), and this difference was not related to small differences observed in insulin degradation. By contrast, IGF-I binding was significantly higher in gliomas than in meningiomas (27% versus 12%, P less than 0.05). Also, IGF-I binding was significantly higher than insulin binding in GBMs (27% versus 3%, P less than 0.03); binding of both IGF and insulin was high in meningiomas. In normal adult brain IGF-I and insulin binding was 7 to 10%. The ability of insulin to support and enhance the growth of central nervous system tumor cells in culture was investigated. Cell cultures were derived from a freshly isolated glioblastoma, a low-grade glioma, and 3 meningiomas.(ABSTRACT TRUNCATED AT 250 WORDS)