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Pregnancy-associated plasma protein-A (PAPP-A) and PAPP-A2 modulate insulin-like growth factor (IGF) action and are inhibited by the stanniocalcins (STC1 and STC2). We previously demonstrated increased PAPP-A and IGF activity in ascites from women with ovarian carcinomas. In this prospective, longitudinal study of 107 women with ovarian cancer and ascites accumulation, we determined corresponding serum and ascites levels of IGF-1, IGF-2, PAPP-A, PAPP-A2, STC1, and STC2 and assessed their relationship with mortality. As compared to serum, we found highly increased ascites levels of PAPP-A (51-fold) and PAPP-A2 (4-fold). Elevated levels were also observed for IGF-1 (12%), STC1 (90%) and STC2 (68%). In contrast, IGF-2 was reduced by 29% in ascites. Patients were followed for a median of 38.4 months (range: 45 days to 8.9 years), during which 73 patients (68.2%) died. Overall survival was longer for patients with high serum IGF-1 (hazard ratio (HR) per doubling in protein concentration: 0.60, 95% CI: 0.40-0.90). However, patients with high ascites levels of IGF-1 showed a poorer prognosis (HR: 2.00 (1.26-3.27)). High serum and ascites IGF-2 levels were associated with increased risk of mortality (HR: 2.01 (1.22-3.30) and HR: 1.78 (1.24-2.54), respectively). Similarly, serum PAPP-A2 was associated with mortality (HR: 1.26 (1.08-1.48)). Our findings demonstrate the presence and activity of the IGF system in the local tumor ecosystem, which is likely a characteristic feature of malignant disease and plays a role in its peritoneal dissemination. The potential clinical implications are supported by our finding that serum levels of the proteins are associated with patient prognosis.
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Glicoproteínas , Fator de Crescimento Insulin-Like I , Neoplasias Ovarianas , Humanos , Feminino , Fator de Crescimento Insulin-Like I/metabolismo , Fator de Crescimento Insulin-Like II , Proteína Plasmática A Associada à Gravidez/metabolismo , Ascite , Estudos Prospectivos , Ecossistema , Estudos Longitudinais , Neoplasias Ovarianas/complicaçõesRESUMO
A single nucleotide substitution in the third intron of insulin-like growth factor 2 (IGF2) is associated with increased muscle mass and reduced subcutaneous fat in domestic pigs. This mutation disrupts the binding of the ZBED6 transcription factor and leads to a threefold up-regulation of IGF2 expression in pig skeletal muscle. Here, we investigated the biological significance of ZBED6-IGF2 interaction in the growth of placental mammals using two mouse models, ZBED6 knock-out (Zbed6-/-) and Igf2 knock-in mice that carry the pig IGF2 mutation. These transgenic mice exhibit markedly higher serum IGF2 concentrations, higher growth rate, increased lean mass, and larger heart, kidney, and liver; no significant changes were observed for white adipose tissues. The changes in body and lean mass were most pronounced in female mice. The phenotypic changes were concomitant with a remarkable up-regulation of Igf2 expression in adult tissues. Transcriptome analysis of skeletal muscle identified differential expression of genes belonging to the extracellular region category. Expression analysis using fetal muscles indicated a minor role of ZBED6 in regulating Igf2 expression prenatally. Furthermore, transcriptome analysis of the adult skeletal muscle revealed that this elevated expression of Igf2 was derived from the P1 and P2 promoters. The results revealed very similar phenotypic effects in the Zbed6 knock-out mouse and in the Igf2 knock-in mouse, showing that the effect of ZBED6 on growth of muscle and internal organs is mediated through the binding site in the Igf2 gene. The results explain why this ZBED6 binding site is extremely well conserved among placental mammals.
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Fator de Crescimento Insulin-Like II/fisiologia , Músculo Esquelético/crescimento & desenvolvimento , Proteínas Repressoras/genética , Proteínas Repressoras/fisiologia , Alelos , Animais , Sítios de Ligação , Sequência Conservada , Ilhas de CpG , Elementos de DNA Transponíveis , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Fenótipo , Regiões Promotoras Genéticas , Análise de Sequência de RNA , Transcriptoma , Regulação para CimaRESUMO
BACKGROUND: Patients with inflammatory bowel disease (IBD) present with reduced serum insulin-like growth factor I (IGF-I). Anti-inflammatory treatment with prednisolone or infliximab ameliorates symptoms and increases circulating IGF-I, but prednisolone induces catabolism, whereas infliximab may promote protein synthesis. Recently, stanniocalcin-2 (STC2) was discovered as a novel inhibitor of the enzyme pregnancy-associated plasma protein-A (PAPP-A), which modulates IGF-I activity. PAPP-A can cleave IGF binding protein-4 (IGFBP-4), upon which IGF-I is liberated. We hypothesized that prednisolone and infliximab exert different effects on levels of STC2, PAPP-A, and IGFBP-4, thereby explaining the distinct metabolic effects of prednisolone and infliximab. METHODS: Thirty-eight patients with active IBD treated with either prednisolone (n = 17) or infliximab (n = 21) were examined before and after 7 days of treatment. Circulating levels of IGF-I, IGF-II, IGFBP-3, PAPP-A, and STC2 were measured by immunoassays. Intact IGFBP-4 and two IGFBP-4 fragments were determined by a novel immunoassay. Bioactive IGF was assessed by cell-based IGF receptor activation assay. Concentrations of IGFBP-4, PAPP-A, and STC2 on day 0 and 7 were compared to healthy control subjects. RESULTS: Following seven days of prednisolone treatment, total and bioactive IGF-I were increased (p < 0.001 and p < 0.05, respectively). Upon infliximab treatment, total IGF-I levels were augmented (p < 0.05), yet IGF bioactivity remained unaltered. Intact IGFBP-4 and the two IGFBP-4 fragments generated upon cleavage by PAPP-A were all decreased following treatment with either prednisolone or infliximab (all p < 0.05). PAPP-A levels were only increased by infliximab (p = 0.005), whereas the inhibitor STC2 did not respond to any of the treatments. CONCLUSION: IGF-I and IGFBP-4 concentrations were markedly altered in patients with IBD and near-normalized with disease remission following treatment with prednisolone or infliximab. Thus, IGFBP-4 may modulate IGF bioavailability in IBD. The effect of immunosuppression did not appear to extend beyond the regulation of IGF and IGFBP-4, as neither PAPP-A nor STC2 were discernibly affected. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00955123 . Date of registration: August 7, 2009 (retrospectively registered).
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Glicoproteínas/sangue , Doenças Inflamatórias Intestinais/tratamento farmacológico , Infliximab/farmacocinética , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/efeitos dos fármacos , Fator de Crescimento Insulin-Like I/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intercelular/sangue , Prednisolona/farmacocinética , Proteína Plasmática A Associada à Gravidez/efeitos dos fármacos , Adulto , Disponibilidade Biológica , Feminino , Humanos , Terapia de Imunossupressão , Quimioterapia de Indução , Doenças Inflamatórias Intestinais/sangue , MasculinoRESUMO
Introduction: Pregnancy-associated plasma protein-A (PAPP-A) is an IGF-activating enzyme suggested to influence aging-related diseases. However, knowledge on serum PAPP-A concentration and regulation in elderly subjects is limited. Therefore, we measured serum PAPP-A in elderly same-sex monozygotic (MZ) and dizygotic (DZ) twins, as this allowed us to describe the age-relationship of PAPP-A, and to test the hypothesis that serum PAPP-A concentrations are genetically determined. As PAPP-A is functionally related to stanniocalcin-2 (STC2), an endogenous PAPP-A inhibitor, we included measurements on STC2 as well as IGF-I and IGF-II. Methods: The twin cohort contained 596 subjects (250 MZ twins, 346 DZ twins), whereof 33% were males. The age ranged from 73.2 to 94.3 (mean 78.8) years. Serum was analyzed for PAPP-A, STC2, IGF-I, and IGF-II by commercial immunoassays. Results: In the twin cohort, PAPP-A increased with age (r=0.19; P<0.05), whereas IGF-I decreased (r=-0.12; P<0.05). Neither STC2 nor IGF-II showed any age relationship. When analyzed according to sex, PAPP-A correlated positively with age in males (r=0.18; P<0.05) and females (r=0.25; P<0.01), whereas IGF-I correlated inversely in females only (r=-0.15; P<0.01). Males had higher levels of PAPP-A (29%), STC2 (18%) and IGF-I (19%), whereas serum IGF-II was 28% higher in females (all P<0.001). For all four proteins, within-pair correlations were significantly higher for MZ twins than for DZ twins, and they demonstrated substantial and significant heritability, which after adjustment for age and sex averaged 59% for PAPP-A, 66% for STC2, 58% for IGF-I, and 52% for IGF-II. Discussion: This twin study confirms our hypothesis that the heritability of PAPP-A serum concentrations is substantial, and the same is true for STC2. As regards the age relationship, PAPP-A increases with age, whereas STC2 remains unchanged, thereby supporting the idea that the ability of STC2 to inhibit PAPP-A enzymatic activity decreases with increasing age.
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Fator de Crescimento Insulin-Like I , Hormônios Peptídicos , Masculino , Feminino , Humanos , Idoso , Idoso de 80 Anos ou mais , Fator de Crescimento Insulin-Like I/metabolismo , Fator de Crescimento Insulin-Like II/metabolismo , Proteína Plasmática A Associada à Gravidez/genética , Proteína Plasmática A Associada à Gravidez/metabolismo , Gêmeos DizigóticosRESUMO
Objective: Physiologically, pregnancy-associated plasma protein-A (PAPP-A) serves to liberate bound IGF1 by enzymatic cleavage of IGF-binding proteins (IGFBPs), IGFBP4 in particular. Clinically, PAPP-A has been linked to cardiovascular disease (CVD). Stanniocalcin-2 (STC2) is a natural inhibitor of PAPP-A enzymatic activity, but its association with CVD is unsettled. Therefore, we examined associations between the STC2-PAPP-A-IGFBP4-IGF1 axis and all-cause mortality and CVD in patients with type 2 diabetes (T2D). Design: We followed 1284 participants with T2D from the ADDITION trial for 5 years. Methods: Circulating concentrations of STC2, PAPP-A, total and intact IGFBP4 and IGF1 and -2 were measured at inclusion. End-points were all-cause mortality and a composite CVD event: death from CVD, myocardial infarction, stroke, revascularisation or amputation. Survival analysis was performed by Cox proportional hazards model. Results: During follow-up, 179 subjects presented with an event. After multivariable adjustment, higher levels of STC2, PAPP-A, as well as intact and total IGFBP4, were associated with all-cause mortality; STC2: hazard ratio (HR) = 1.84 (1.09-3.12) (95% CI); P = 0.023, PAPP-A: HR = 2.81 (1.98-3.98); P < 0.001, intact IGFBP4: HR = 1.43 (1.11-1.85); P = 0.006 and total IGFBP4: HR = 3.06 (1.91-4.91); P < 0.001. Higher PAPP-A levels were also associated with CVD events: HR = 1.74 (1.16-2.62); P = 0.008, whereas lower IGF1 levels were associated with all-cause mortality: HR = 0.51 (0.34-0.76); P = 0.001. Conclusions: This study supports that PAPP-A promotes CVD and increases mortality. However, STC2 is also associated with mortality. Given that STC2 inhibits the enzymatic effects of PAPP-A, we speculate that STC2 either serves to counteract harmful PAPP-A actions or possesses effects independently of the PAPP-A-IGF1 axis. Significance statement: PAPP-A has pro-atherosclerotic effects and exerts these most likely through IGF1. IGF1 is regulated by the STC2-PAPP-A-IGFBP4-IGF1 axis, where STC2, an irreversible inhibitor of PAPP-A, has been shown to reduce the development of atherosclerotic lesions in mice. We examined the association of this axis to mortality and CVD in T2D. We demonstrated an association between PAPP-A and CVD. All components of the STC2-PAPP-A-IGFBP4-IGF1 axis were associated with mortality and it is novel that STC2 was associated with mortality in T2D. Our study supports that inhibition of PAPP-A may be a new approach to reducing mortality and CVD. Whether modification of STC2 could serve as potential intervention warrants further investigation.
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INTRODUCTION: Contrast-enhanced CT (CECT) is widely used for diagnostic purposes. The use of contrast medium carries a risk for postcontrast acute kidney injury (PC-AKI), especially in patients with AKI or chronic kidney disease (CKD). Current guidelines recommend prophylactic intravenous hydration to prevent PC-AKI in high-risk patients. Oral hydration is non-inferior to intravenous hydration in patients with moderate CKD, but it has not been evaluated in high-risk patients. METHODS AND ANALYSIS: The ENRICH trial will enrol 254 patients with estimated glomerular filtration rate ≤30 mL/min/1.73 m2 undergoing intravenous CECT, who are block randomised (2-4-2) with stratification for CKD stage, diabetes status, and indication for referral to prophylactic treatment with oral or intravenous hydration. PC-AKI is defined as an absolute increase in SCr of >0.3 mg/dL or >1.5 from baseline at 2-5 days. Renal function will also be evaluated <90 days, <7 days and 1-3 days before intravenous CECT, and 25-40 days after intravenous CECT. Secondary outcomes include dialysis, renal adverse events, hospitalisation due to hydration-related or contrast-related sequelae, and all-cause mortality ≤30 days postcontrast. Pre- and postcontrast plasma and urinary biomarkers will be evaluated for diagnostic and prognostic accuracy of the primary and secondary outcomes. ETHICS AND DISSEMINATION: Oral hydration is patient-friendly and less costly compared with intravenous hydration. If oral hydration is non-inferior to intravenous hydration in high-risk patients, it could be implemented as new hydration strategy, which will facilitate the clinical diagnosing of elective patients with severe CKD without unnecessary resource utilisation. The protocol is approved by the Regional Scientific Ethical Committee for Southern Denmark (S-20210126), and the Data Protection Agency (21/66779). The study is conducted in accordance with the Declaration of Helsinki. Positive as well as negative findings will be reported in international peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05283512.
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Injúria Renal Aguda , Insuficiência Renal Crônica , Humanos , Diálise Renal , Injúria Renal Aguda/induzido quimicamente , Injúria Renal Aguda/prevenção & controle , Insuficiência Renal Crônica/complicações , Dinamarca , Tomografia Computadorizada por Raios X , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
AIMS: Serum insulin-like growth factor binding protein-2 (IGFBP-2) is low in persons with type 2 diabetes mellitus (T2D) and possibly regulated by metformin. Counter-intuitively, high IGFBP-2 associates with mortality. We investigated the association between IGFBP-2, metformin-treatment, and indices of insulin sensitivity, and assessed IGFBP-2 in relation to prior comorbidity and mortality during five-year follow-up. METHODS: The study included 859 treatment-naive and 558 metformin-treated persons enrolled in the Danish Centre for Strategic Research in T2D and followed for 4.9 (3.9-5.9) years through national health registries. All proteins were determined in serum collected at enrollment. RESULTS: Following adjustment for age, metformin-treated and treatment-naive persons has similar IGFBP-2 levels. Low IGFBP-2 level was associated with increased BMI, fasting glucose, and C-peptide. IGFBP-2 was higher in the 437 persons who had comorbidities at enrollment than in those with T2D only (343 (213;528) vs. 242 (169;378) ng/mL). During follow-up, 87 persons died, and IGFBP-2 predicted mortality with an unadjusted HR (95% CI) per doubling in IGFBP-2 concentration of 2.62 (2.04;3.37) and a HR of 2.21 (1.61;3.01) following full adjustment. CONCLUSIONS: In T2D, high IGFBP-2 associates with low glucose and insulin secretion, is unaffected by metformin treatment, and associates with risk of prior comorbidity and mortality.
Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Metformina , Humanos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Metformina/uso terapêutico , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina , Glucose , Insulina , Fator de Crescimento Insulin-Like I/metabolismoRESUMO
Objective: Androgen deprivation therapy (ADT), a principal therapy in patients with prostate cancer, is associated with the development of obesity, insulin resistance, and hyperinsulinemia. Recent evidence indicates that metformin may slow cancer progression and improves survival in prostate cancer patients, but the mechanism is not well understood. Circulating insulin-like growth factors (IGFs) are bound to high-affinity binding proteins, which not only modulate the bioavailability and signalling of IGFs but also have independent actions on cell growth and survival. The aim of this study was to investigate whether metformin modulates IGFs, IGF-binding proteins (IGFBPs), and the pregnancy-associated plasma protein A (PAPP-A) - stanniocalcin 2 (STC2) axis. Design and methods: In a blinded, randomised, cross-over design, 15 patients with prostate cancer on stable ADT received metformin and placebo treatment for 6 weeks each. Glucose metabolism along with circulating IGFs and IGFBPs was assessed. Results: Metformin significantly reduced the homeostasis model assessment as an index of insulin resistance (HOMA IR) and hepatic insulin resistance. Metformin also reduced circulating IGF-2 (P < 0.05) and IGFBP-3 (P < 0.01) but increased IGF bioactivity (P < 0.05). At baseline, IGF-2 correlated significantly with the hepatic insulin resistance (r2= 0.28, P < 0.05). PAPP-A remained unchanged but STC2 declined significantly (P < 0.05) following metformin administration. During metformin treatment, change in HOMA IR correlated with the change in STC2 (r2= 0.35, P < 0.05). Conclusion: Metformin administration alters many components of the circulating IGF system, either directly or indirectly via improved insulin sensitivity. Reduction in IGF-2 and STC2 may provide a novel mechanism for a potential metformin-induced antineoplastic effect.
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BACKGROUND: Pregnancy-associated plasma protein-A (PAPP-A) is an enzyme that increases IGF-activity through cleavage of IGF-binding proteins (IGFBPs), primarily IGFBP-4, whereby bound IGF-I becomes released as a free molecule. The enzymatic activity of PAPP-A is irreversibly suppressed by the glycoprotein stanniocalcin-2 (STC2). Pre-clinical and clinical studies suggest that the STC2 - PAPP-A - IGFBP-4 axis is important in controlling local IGF-action. STC2, PAPP-A and IGFBP-4 are expressed in adipose tissue, and as bariatric surgery markedly reduces the amount of fat, we found it relevant to study the impact of Roux-en-Y gastric bypass (RYGB) on circulating concentrations of this IGF-regulatory network. METHODS: Analysis of fasting blood samples from 20 obese subjects, hereof 10 with preoperative type 2 diabetes, investigated before RYGB, and 1â¯week, 3â¯months and 12â¯months post-surgery. Members of the IGF-system were analyzed by immunoassays, bioactive IGF by cell-based IGF-I receptor activation assay. We compared changes in IGF-system components with changes in fasting plasma insulin and glucose, and HbA1c. RESULTS: PAPP-A remained unchanged, but STC2 decreased following RYGB (pâ¯<â¯0.05). The PAPP-A substrate IGFBP-4 declined (pâ¯<â¯0.01), whereas levels of PAPP-A specific IGFBP-4 fragments increased (pâ¯<â¯0.05), indicating an increased PAPP-A enzymatic activity post-RYGB. Further, the reduction in intact IGFBP-4 correlated with increased levels of bioactive IGF (pâ¯<â¯0.05). In multivariable regression analyses, an improved glucose metabolism correlated with reductions in STC2 and IGFBP-4, and with increases in bioactive IGF and IGF-I (pâ¯<â¯0.05). CONCLUSION: After 12â¯months, RYGB caused reduced serum concentrations of intact IGFBP-4 and STC2, whereas serum PAPP-A remained at pre-operative levels. However, concentrations of PAPP-A generated IGFBP-4 fragments increased, pointing to an overall increased PAPP-A enzymatic activity following RYGB. Notably, reductions in intact IGFBP-4 and STC2 associated with improvements in glucose metabolism. Therefore, we propose that STC2 and IGFBP-4 are involved in the metabolic improvement that follows RYGB.
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Derivação Gástrica , Glicoproteínas/sangue , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Fator de Crescimento Insulin-Like I/análise , Peptídeos e Proteínas de Sinalização Intercelular/sangue , Obesidade Mórbida/cirurgia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade Mórbida/sangue , Proteína Plasmática A Associada à Gravidez/análiseRESUMO
OBJECTIVE: Women experience an unhealthy change in metabolic risk profile at menopause. The purpose of the present study was to determine effects of resistance training with or without transdermal estrogen therapy (ET) on adipose tissue mass and metabolic risk profile in early postmenopausal women. METHODS: A double-blinded randomized controlled trial, where healthy, untrained postmenopausal women were allocated to supervised resistance training with placebo (PLC, nâ=â16) or transdermal ET (nâ=â15) for 12âweeks. Endpoints with prespecified hypotheses were the change in total fat mass (FM) (main endpoint) and the change in visceral FM (secondary endpoint) from before to after the intervention. Additionally, prespecified endpoints of body composition, metabolic health-related blood markers, fat%, fat cell size, and lipogenic markers in subcutaneous adipose tissue (SAT) from abdominal and femoral region were explored. RESULTS: Compared with the ET group, the PLC group experienced a greater reduction (time × treatment interaction Pâ<â0.05) in total FM (PLC vs ET: -5.6% vs -1.1%) and visceral FM (-18.6% vs -6.8%), and femoral SAT (-5.6% vs 1.0%), but not abdominal SAT mass (-8.5% vs -2.8%, Pâ=â0.15).The ET group improved their metabolic blood profile by reduced low-density lipoprotein, glucose and hemoglobin A1c compared with PLC (time × treatment interaction Pâ<â0.05). The intervention induced changes in lipolytic markers of abdominal SAT, whereas no changes were detected in femoral SAT. CONCLUSION: Use of transdermal ET reduced adipose tissue loss, but improved metabolic blood markers when combined with 12âweeks of progressive resistance training in early postmenopausal women.
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Treinamento Resistido , Composição Corporal , Estrogênios , Feminino , Humanos , Gordura Intra-Abdominal , Pós-MenopausaRESUMO
IGF-I was originally discovered as a GH-dependent growth factor stimulating longitudinal growth. Currently, however, it has become evident that the biological activities of IGF-I extend well beyond those of a simple growth factor and impact such processes as insulin sensitivity, aging, cancer and cardiovascular disease. The vast majority of IGF-I is tightly bound to IGF-binding proteins (IGFBPs), which renders IGF-I unable to stimulate the IGF-I receptor (IGF-IR) in vivo. This binding means that liberation of IGF-I from the IGFBPs is an important step controlling IGF-I action. In this context, IGFBP-cleaving enzymes appear to play a key role. Enzymatic cleavage of the IGFBPs markedly lowers their ligand affinity, and as a consequence, IGF-I becomes liberated and hence available for stimulation of the IGF-IR. Two of the best-characterized IGFBP-cleaving enzymes are pregnancy-associated plasma protein-A (PAPP-A) and its paralog PAPP-A2. The two enzymes (often referred to as pappalysins) regulate the liberation of IGF-I in a highly controlled manner. PAPP-A is believed to act predominantly in tissues, serving to liberate IGF-I at the cell surface in close proximity to the IGF-IR. In keeping with this notion, mice lacking PAPP-A exhibit reduced body size, despite having normal circulating IGF-I concentrations. In contrast, human findings indicate that altered PAPP-A2 activity changes circulating IGF-I concentrations, although PAPP-A2 is also present in high concentrations in tissues. Thus, PAPP-A2 appears to impact circulating, as well as tissue, IGF-I activity. The enzymatic activity of PAPP-A and PAPP-A2 was recently discovered to be regulated by the protein Stanniocalcin-2 (STC2). By binding to the enzymatic sites of PAPP-A and PAPP-A2, STC2 inhibits their activity. To date, the majority of findings demonstrating the ability of pappalysins and STC2 to regulate IGF-I action are from preclinical studies. However, clinical studies are now beginning to emerge. In this review, we will summarize our data on STC2, PAPP-A and PAPP-A2 in humans. These results indicate that pappalysins and STC2 constitute an important IGF-I activity-regulating system that warrants further investigation.
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Glicoproteínas/metabolismo , Fator de Crescimento Insulin-Like I/fisiologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteína Plasmática A Associada à Gravidez/metabolismo , Animais , Feminino , Humanos , Camundongos , GravidezRESUMO
BACKGROUND: Insulin-like growth factor binding-protein 2 (IGFBP-2) was originally identified as an IGF-carrier, governing IGF half-life, tissue accessibility and biological effects. Later, IGFBP-2 was discovered to possess IGF-independent effects. IGFBP-2 circulates in several forms, as free protein, complexed with IGF-I or IGF-II, or as IGFBP-2 fragments. The various IGFBP-2 forms are all included when measuring serum IGFBP-2 concentrations by immunoassay (i.e., immunoreactive (ir-)IGFBP-2). In this study, we describe a novel method to measure the amount of IGF that circulates bound to IGFBP-2. METHOD: IGFBP-2 was immunoprecipitated from human serum using magnetic beads, which were subsequently eluted by acidification. After neutralization, eluates were assayed for ir-IGFBP-2, IGF-I and IGF-II and compared to serum concentrations. This allowed measurement of IGFBP-2-compexed IGF-I and IGF-II, respectively. To test the method clinically, serum from 146 patients with lung cancer, 151 patients with non-cancer pulmonary diseases and 28 healthy controls were analyzed. RESULTS: We immuno-precipitated 97 ± 3.3% of serum IGFBP-2 and recovered > 75% of IGFBP-2-complexed IGFs, with intra- and inter-assay coefficient of variations (CVs) averaging < 5% and < 13%, respectively. No co-precipitation with IGFBP-1, -3 or - 4 was detected. Serum levels of ir-IGFBP-2 (median [25;75%]) differed between groups (cancer patients vs. non-cancer patients vs. healthy controls): 342 [260;480] vs. 262 [189;388] vs. 190 [141;269] µg/l (p < .0001). In parallel with this, concentrations of IGF-II carried by IGFBP-2 averaged: 45.0 [33.3;52.5] vs. 34.2 [25.4;46.1] vs. 19.8 [14.1;26.0] µg/l (p < .0001), and concentrations of IGF-I 8.0 [5.2;11.8] vs. 5.4 [3.6;7.3] vs. 7.0 [3.8;13.0] µg/l (p < .0001). Thus, IGFBP-2 carried more IGF-II than IGF-I in all groups (p < .0001). When expressed relative to IGF-concentrations, IGFBP-2 carried 9.0 [5.3;15.5] % of the IGF-I and 4.8 [2.9;5.8] % of the IGF-II in serum from healthy subjects. Notably, in patients, IGFBP-2 carried relatively less IGF-I, but more IGF-II (p < .0001). CONCLUSION: Using our novel assay, we demonstrate: that IGFBP-2 carries ≈10% of circulating IGF-I and ≈5% of circulating IGF-II in healthy subjects; that IGF-II is the primary ligand for IGFBP-2; and that IGFBP-2 carries even more IGF-II in patients than in healthy subjects. Thus, our assay may provide information on IGFBP-2 beyond what is achievable by simply measuring ir-IGFBP-2.
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Imunoensaio/métodos , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Fator de Crescimento Insulin-Like II/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Estudos de Casos e Controles , Técnicas de Diagnóstico Endócrino , Humanos , Imunoprecipitação , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Pneumopatias/sangue , Neoplasias Pulmonares/sangue , Reprodutibilidade dos TestesRESUMO
Pregnancy-associated plasma protein-A (PAPP-A) and its homolog PAPP-A2 are enzymes that modulate the availability and mitogenic activity of insulin-like growth factor-I (IGF-I). PAPP-A has been implicated in numerous cancers but reports on PAPP-A2 in malignancy are non-existent. In a prospective observational study of 689 patients under suspicion of lung cancer, we examined levels of PAPP-A and PAPP-A2 and their relationship with mortality. Serum PAPP-A and PAPP-A2 concentrations were determined in pre-diagnostic blood samples using ELISA, and immunohistochemical staining of PAPP-A and PAPP-A2 was performed in malignant tissue from five operable patients. A total of 144 patients were diagnosed with lung cancer, whereas the diagnosis was rejected in 545 subjects, who served as a control group. PAPP-A2 concentrations were higher in patients with lung cancer [median (IQR): 0.33 (0.21-0.56) ng/mL] than in controls [0.27 (0.17-0.39) ng/mL], p < 0.001, whereas PAPP-A levels did not differ. Presence of PAPP-A and PAPP-A2 were confirmed in tumor specimens, and staining occurred in a heterogeneous pattern. Patients were observed for a median (range) of 7 (6; 8) years, during which 114 patients (79.2%) died. Patient mortality differed according to PAPP-A2 tertile (p < 0.001). PAPP-A2 was associated with mortality with an unadjusted hazard ratio (95% CI) per doubling in protein concentration of 1.30 (1.12; 1.53), p = 0.001. In a multivariable model adjusted for age, sex, and BMI, PAPP-A2 remained predictive of the endpoint with a hazard ratio per doubling in protein concentration of 1.25 (1.05; 1.48), p = 0.013. Collectively, PAPP-A2, but not PAPP-A, is elevated in patients with lung cancer and associated with mortality. This novel role of PAPP-A2 in cancer warrants further functional studies as well as validation in external cohorts.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/sangue , Neoplasias Pulmonares/sangue , Proteína Plasmática A Associada à Gravidez/metabolismo , Carcinoma de Pequenas Células do Pulmão/sangue , Idoso , Idoso de 80 Anos ou mais , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Feminino , Humanos , Neoplasias Pulmonares/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Carcinoma de Pequenas Células do Pulmão/mortalidadeRESUMO
OBJECTIVE: Pregnancy-associated plasma protein-A (PAPP-A) has been suggested as a proatherogenic enzyme by its ability to locally increase insulin-like growth factor (IGF) activity through proteolytic cleavage of IGF binding protein-4 (IGFBP-4). Recently, stanniocalcin-2 (STC2) was discovered as an inhibitor of PAPP-A. This study aimed to investigate IGFBP-4, PAPP-A, and STC2 as local regulators of IGF bioactivity in the cardiac microenvironment by comparing levels in the pericardial fluid with those in the circulation of patients with cardiovascular disease. METHODS: Plasma and pericardial fluid were obtained from 39 patients undergoing elective cardiothoracic surgery, hereof 15 patients with type 2 diabetes. Concentrations of IGF-I, intact and fragmented IGFBP-4, PAPP-A, and STC2 were determined by immunoassays and IGF bioactivity by a cell-based assay. RESULTS: In pericardial fluid, the concentrations of total IGF-I, intact IGFBP-4, and STC2 were 72 ± 10%, 91 ± 5%, and 40 ± 24% lower than in plasma, while PAPP-A was 15 times more concentrated. The levels of the 2 IGFBP-4 fragments generated by PAPP-A and reflecting PAPP-A activity were elevated by more than 25%. IGF bioactivity was 62 ± 81% higher in the pericardial fluid than plasma. Moreover, pericardial fluid levels of both IGFBP-4 fragments correlated with the concentration of PAPP-A and with the bioactivity of IGF. All protein levels were similar in pericardial fluid from nondiabetic and diabetic subjects. CONCLUSIONS: PAPP-A increases IGF bioactivity by cleavage of IGFBP-4 in the pericardial cavity of cardiovascular disease patients. This study provides evidence for a distinct local activity of the IGF system, which may promote cardiac dysfunction and coronary atherosclerosis.
Assuntos
Doenças Cardiovasculares/metabolismo , Líquido Pericárdico/metabolismo , Pericárdio/metabolismo , Proteína Plasmática A Associada à Gravidez/metabolismo , Somatomedinas/metabolismo , Idoso , Doenças Cardiovasculares/cirurgia , Ponte de Artéria Coronária , Diabetes Mellitus Tipo 2/metabolismo , Glicoproteínas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Masculino , Pessoa de Meia-IdadeRESUMO
Insulin-like growth factor (IGF) binding protein-4 (IGFBP-4) is a modulator of the IGF system, exerting both inhibitory and stimulatory effects on IGF-induced cellular growth. IGFBP-4 is the principal substrate for the enzyme pregnancy-associated plasma protein-A (PAPP-A). Through IGF-dependent cleavage of IGFBP-4 in the vicinity of the IGF receptor, PAPP-A is able to increase IGF bioavailability and stimulate IGF-mediated growth. Recently, the stanniocalcins (STCs) were identified as novel inhibitors of PAPP-A proteolytic activity, hereby adding additional members to the seemingly endless list of proteins belonging to the IGF family. Our understanding of these proteins has advanced throughout recent years, and there is evidence to suggest that the role of IGFBP-4 and PAPP-A in defining the relationship between total IGF and IGF bioactivity can be linked to a number of pathological conditions. This review provides an overview of the experimental and clinical findings on the IGFBP-4/PAPP-A/STC axis as a regulator of IGF activity and examines the conundrum surrounding extrapolation of circulating concentrations to tissue action of these proteins. The primary focus will be on the biological significance of IGFBP-4 and PAPP-A in normal physiology and in pathophysiology with emphasis on metabolic disorders, cardiovascular diseases, and cancer. Finally, the review assesses current new trajectories of IGFBP-4 and PAPP-A research.
Assuntos
Biomarcadores/metabolismo , Doenças Cardiovasculares/fisiopatologia , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Doenças Metabólicas/fisiopatologia , Neoplasias/fisiopatologia , Proteína Plasmática A Associada à Gravidez/metabolismo , Humanos , PrognósticoRESUMO
Cardiovascular diseases are the leading cause of death around the world and the insulin-like growth factor (IGF)-system has multiple functions for the pathological conditions of atherosclerosis. IGF binding proteins (IGFBPs) are widely investigated as biomarkers for pathological disorders, including those of the heart. At the tissue level, IGFBP-1 to -6 decrease bioactivity of IGF-I and -II due to their high affinity IGF-binding sites. By contrast, in the circulation, the IGFBPs increase biological half-life of the IGFs and may therefore be regarded as positive regulators of IGF-effects. The IGFBPs may also exert IGF-independent functions inside or outside the cell. Importantly, the circulating IGFBP-concentrations are regulated by trophic, metabolic, and reproductive hormones. In a multitude of studies of healthy subjects and patients with coronary heart diseases, various significant associations between circulating IGFBP-levels and defined parameters have been reported. However, the complex hormonal and conditional control of IGFBPs may explain the lack of clear associations between IGFBPs and parameters of cardiac failure in broader studies including larger populations. Furthermore, the IGFBPs are subject to posttranslational modifications and proteolytic degradation by proteases, upon which the IGFs are released. In this review, we emphasize that, with the exception of IGFBP-4 and in sharp contrast to the preclinical studies, virtually all clinical studies do not have structural or functional information on their biomarker. The use of analytical systems with no discriminatory potential toward intact vs. fragmented IGFBPs represents a major issue in IGFBP-related biomarker research and an important focus point for the future. Overall, measurements of selected IGFBPs or more complex IGFBP-signatures of the family of IGFBPs have potential to identify pathophysiological alterations in the heart or patients with high cardiovascular risk, particularly if defined cohorts are to be assessed. However, a more thorough understanding of the dynamic IGF-IGFBP system as well as its proteases and protease inhibitors in both normal physiology and in cardiovascular diseases is necessary.
RESUMO
INTRODUCTION: Pregnancy-associated plasma protein-A (PAPP-A) stimulates insulin-like growth factor (IGF)-I action through proteolytic cleavage of IGF binding protein-4 (IGFBP-4). Recently, stanniocalcin-2 (STC2) was discovered as an inhibitor of PAPP-A. Most members of the IGF system are expressed in adipose tissue (AT), but there is a relative paucity of information on the distribution of IGFBP-4, PAPP-A, and STC2 in different AT depots. Since IGF-I expression in AT is highly GH-dependent, we used bovine GH transgenic (bGH) and GH receptor knockout (GHR-/-) mice to investigate AT depot-specific expression patterns of IGFBP-4, PAPP-A, and STC2, and whether the regulation is GH-dependent. METHODS: Seven-month-old male bGH, GHR-/- and wild type (WT) control mice were used. Body composition was determined, and subcutaneous, epididymal, retroperitoneal, mesenteric and brown adipose tissue (BAT) depots were collected. RNA expression of Igfbp4, Pappa, and Stc2 was assessed by reverse transcription quantitative PCR and IGFBP-4 protein by Western blotting. RESULTS: Igfbp4, Pappa, and Stc2 RNA levels were differentially expressed in an AT depot-dependent manner in WT mice. Igfbp4 RNA levels were significantly higher in all white AT depots than in BAT. Pappa was most highly expressed in the mesenteric depot: levels were 7.5-fold higher in mesenteric than in subcutaneous AT (pâ¯<â¯.001). Although intraabdominal in origin, epididymal and retroperitoneal Pappa expression levels were 69% and 68% lower, respectively, as compared to mesenteric levels (pâ¯<â¯.001). Stc2 RNA expression was significantly higher in all intraabdominal white AT as compared to subcutaneous AT and BAT; levels in epididymal, retroperitoneal, and mesenteric were all more than three-fold higher than in subcutaneous AT (pâ¯<â¯.001) and 12-fold higher than in BAT (pâ¯<â¯.001). Gene expression patterns in bGH and GHR-/- mice mimicked those in WT mice, suggesting that GH does not affect the transcription of the STC2-PAPP-A-IGFBP-4-axis in AT. However, proteins levels of intact IGFBP-4 were significantly increased in bGH mice and decreased in GHR-/- mice, whereas the PAPP-A-generated IGFBP-4 fragment level was unaltered. CONCLUSION: Expression of Igfbp4, Pappa, and Stc2 differ between AT depots and is generally higher in white AT than in BAT. The transcription appears to occur in a GH-independent manner, whereas IGFBP-4 protein levels are highly influenced by altered GH activity.
Assuntos
Tecido Adiposo/metabolismo , Proteínas de Transporte/fisiologia , Glicoproteínas/metabolismo , Hormônio do Crescimento/fisiologia , Hormônio do Crescimento Humano/administração & dosagem , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteína Plasmática A Associada à Gravidez/metabolismo , Tecido Adiposo/citologia , Tecido Adiposo/efeitos dos fármacos , Animais , Composição Corporal , Bovinos , Células Cultivadas , Feminino , Regulação da Expressão Gênica , Glicoproteínas/genética , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Peptídeos e Proteínas de Sinalização Intercelular , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Gravidez , Proteína Plasmática A Associada à Gravidez/genéticaRESUMO
BACKGROUND: Fragments of insulin-like growth factor binding protein 4 (IGFBP-4) are potential new biomarkers for cardiac risk assessment. The fragments are generated on specific cleavage by pregnancy-associated plasma protein-A, which exerts proatherogenic activity. This study investigated the prognostic value of IGFBP-4 fragments in patients with ST-segment elevation myocardial infarction. METHODS AND RESULTS: We prospectively included 656 patients with ST-segment elevation myocardial infarction treated with percutaneous coronary intervention from September 2006 to December 2008. Blood samples were drawn before percutaneous coronary intervention, and levels of intact IGFBP-4 and N-terminal and C-terminal IGFBP-4 fragments were measured by specific assays. End points were 5-year all-cause and cardiovascular mortality and the combined end point of major adverse cardiac events. Prognostic potential was evaluated on top of a clinical model in terms of discrimination, calibration, and reclassification analysis. During follow-up, 166 patients experienced a major adverse cardiac event and 136 patients died, of whom 69 died from cardiovascular causes. Both IGFBP-4 fragments were associated with all end points (P<0.001). After multivariable adjustments, both N-terminal and C-terminal IGFBP-4 fragment levels remained associated with all end points, including cardiovascular mortality with hazard ratios per doubling in protein concentration of 2.54 (95% CI 1.59-4.07; P<0.001) and 2.07 (95% CI 1.41-3.04; P<0.001), respectively. Incorporation of IGFBP-4 fragments into a clinical model with 15 risk factors improved C-statistics and model calibration and provided incremental prognostic contribution, as assessed by net reclassification improvement and integrated discrimination improvement. CONCLUSIONS: IGFBP-4 fragments are associated with increased risk of all-cause mortality, cardiovascular mortality, and major adverse cardiac events in patients with ST-segment elevation myocardial infarction.
Assuntos
Doenças Cardiovasculares/mortalidade , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Fragmentos de Peptídeos/sangue , Infarto do Miocárdio com Supradesnível do Segmento ST/sangue , Idoso , Idoso de 80 Anos ou mais , Causas de Morte , Feminino , Insuficiência Cardíaca/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Mortalidade , Infarto do Miocárdio/epidemiologia , Readmissão do Paciente , Intervenção Coronária Percutânea , Prognóstico , Modelos de Riscos Proporcionais , Infarto do Miocárdio com Supradesnível do Segmento ST/cirurgia , Acidente Vascular Cerebral/epidemiologiaRESUMO
OBJECTIVE: Perturbations in the insulin-like growth factor (IGF) system may contribute to the accelerated cardiovascular disease (CVD) that occurs in patients with type 2 diabetes (T2D). However, it remains unknown whether the IGF system is also involved in the development of early, subclinical CVD. We characterised the IGF system in T2D patients and matched controls and examined the associations with markers of subclinical target organ damage. METHODS: The study included 99 patients with recently diagnosed T2D and 99 age- and sex-matched controls. IGF-1 and IGFBP-1 to -4 were measured by immunoassays, as were pregnancy-associated plasma protein-A (PAPP-A) and the PAPP-A-generated N-terminal (NT) and C-terminal (CT) IGFBP-4 fragments, which are novel CVD risk markers. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (PWV). Cerebral white matter lesions (WMLs) and carotid artery remodelling were determined by MRI. RESULTS: After multivariate adjustments, patients with T2D had lower concentrations of IGFBP-2, IGFBP-4, NT- and CT-IGFBP-4, when compared with controls. IGFBP-2 was inversely correlated to PWV in all subjects in multivariate analysis (P < 0.05), and IGFBP-3 was inversely associated with severity of WMLs (P < 0.05). The NT-IGFBP-4 fragment was associated with the degree of carotid artery remodelling among all subjects (regression coefficient (95% CI): 2.95 (0.70, 5.16), P = 0.011). Levels of NT- and CT-IGFBP-4 were reduced in T2D patients receiving metformin compared to those in controls and patients not receiving metformin. CONCLUSIONS: Even in recently diagnosed and well-controlled T2D patients, IGF protein levels are altered and associated with CVD risk factors.
Assuntos
Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/diagnóstico , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Idoso , Biomarcadores/sangue , Doenças Cardiovasculares/epidemiologia , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Humanos , Proteína 1 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/sangue , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Pessoa de Meia-Idade , GravidezRESUMO
Galectin-1 (Gal-1) is known to regulate cell signaling within the immune system and may be a target for new anticancer immune therapy. In patients with chronic lymphocytic leukemia (CLL) and classical Hodgkin lymphoma (cHL), high levels of Gal-1 within the tumor microenvironment were associated with worse disease state or poor outcome. Gal-1 can be secreted from cells by an unknown mechanism, and levels in blood samples were associated with high tumor burden and worse disease state in cHL and CLL patients. However, serum levels of Gal-1 have never been investigated in patients with multiple myeloma (MM). We measured serum Gal-1 levels in samples from patients with treatment demanding MM at the time of diagnosis (n=102) and after treatment (n=24) and examined associations of serum Gal-1 with clinicopathological information obtained from patient medical records, as well as data on bone marrow angiogenesis and the macrophage activation biomarkers soluble CD163 (sCD163) and soluble mannose receptor. Serum Gal-1 levels were not elevated in patients with MM at diagnosis compared with healthy donors (median values 8.48 vs 11.93 ng/mL, P=0.05), which is in contrast to results in cHL and CLL. Furthermore, Gal-1 levels did not show association with bone marrow angiogenesis, clinicopathological parameters, overall survival, or response to treatment. There was a statically significant association between Gal-1 and sCD163 levels (R=0.24, P=0.02), but not with soluble mannose receptor (P=0.92). In conclusion, our results indicate that Gal-1 is not an important serum biomarker in MM, which is in contrast to data from patients with cHL and CLL. However, the association with sCD163 is in line with previous data showing that Gal-1 may be involved in alternative (M2-like) activation of macrophages.