IGFBP-2 - taking the lead in growth, metabolism and cancer

Plasma Insulin-Like Growth Factor-Binding Protein-2 Levels Predict Severe Septic Acute Kidney Injury: A Mendelian Randomization Analysis

BACKGROUND

 Sepsis-associated acute kidney injury (SA-AKI) currently lacks highly sensitive biomarkers for early detection, resulting in delayed identification and intervention during its early stages and an independent risk of death.

OBJECTIVE

 This study aimed to investigate the relationship between insulin-like growth factor-binding protein-2 (IGFBP-2) levels and the occurrence of sepsis-induced kidney injury and to evaluate the causal relationship between the two through Mendelian randomization (MR) analysis.

METHODS

 This study employed a single-center, prospective cohort design involving 79 sepsis patients from the Intensive Care Unit (ICU) at the First Affiliated Hospital of Xinjiang Medical University, Ürümqi, China. The patients were divided into two groups, the SA-AKI group and the non-SA-AKI group, on the basis of whether they developed SA-AKI. The primary endpoint was whether SA-AKI occurred within 48 hours of admission. MR and sensitivity analyses were conducted to explore the causal relationships.

RESULTS

 The IGFBP-2 level had high diagnostic value for the prediction of SA-AKI. Receiver operating characteristic (ROC) curve analysis revealed that IGFBP-2 alone predicted SA-AKI, with an area under the curve (AUC) of 0.8994, a cut-off value of 709.004, a sensitivity of 88.64%, and a specificity of 85.71%. The combined prediction of the IGFBP-2 score, acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score, and use of vasopressors had an AUC of 0.9604, a sensitivity of 93.18%, and a specificity of 82.86%. MR analysis revealed no causal relationship between genetically predicted IGFBP-2 levels and AKI (OR: 1.1507, 95% CI: 0.88-1.50, p = 0.2995).

CONCLUSION

 Plasma IGFBP-2 levels can predict the occurrence of SA-AKI in sepsis patients. However, MR analysis suggests that there is no direct causal relationship between plasma IGFBP-2 levels and septic kidney injury, and the underlying mechanisms need to be further investigated in randomized controlled trials.

Identification of Disease-Relevant, Sex-Based Proteomic Differences in iPSC-Derived Vascular Smooth Muscle Cells

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insights into some aspects of human biology; however, not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle cells than iPSCs. We also identified sex-based differences in iPSC-derived vascular smooth muscle cells in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease.

Diagnostic Accuracy of a Blood-Based Biomarker Panel for Colorectal Cancer Detection: A Pilot Study

Background: Colorectal cancer (CRC) is a leading cause of death worldwide. Despite its preventability through screening, compliance still needs to improve due to the invasiveness of current tools. There is a growing demand for validated molecular biomarker panels for minimally invasive blood-based CRC screening. This study assessed the diagnostic accuracy of four promising blood-based CRC biomarkers, individually and in combination. Methods: This case-control study involved plasma samples from 124 CRC cases and 124 age- and sex-matched controls. Biomarkers tested included methylated DNA encoding the Septin-9 gene (mSEPT9) using Epi proColon® 2.0 CE, insulin-like growth factor binding protein 2 (IGFBP2), dickkopf-3 (DKK3), and pyruvate kinase M2 (PKM2) by ELISA. Diagnostic accuracy was measured using the receiver operating characteristic (ROC), area under the curve (AUC), as well as sensitivity and specificity. Results: Diagnostic accuracy for mSEPT9, IGFBP2, DKK3, and PKM2 was 62.9% (95% CI: 56.8-62.9%), 69.7% (95% CI: 63.1-69.7%), 61.6% (95% CI: 54.6-61.6%), and 50.8% (95% CI: 43.4-50.8%), respectively. The combined biomarkers yielded an AUC of 74.4% (95% CI: 68.1-80.6%), outperforming all biomarkers except IGFBP2. Conclusions: These biomarkers show potential for developing a minimally invasive CRC detection tool as an alternative to existing approaches, potentially increasing adherence, early detection, and survivorship.

IGFBP-2 in Critical Illness: A Prognostic Marker in the Growth Hormone/Insulin-like Growth Factor Axis

Critical illness (CI) triggers complex disruptions in the growth hormone (GH)/insulin-like growth factor (IGF) axis, significantly affecting the dynamics of insulin-like growth-factor-binding proteins (IGFBPs). Among these, IGFBP-2 shows a sustained elevation during CI, which inversely correlates with serum levels of IGF-1, IGFBP-3, and the acid-labile subunit (ALS). Although IGFBP-2 does not directly interact with ALS, it may influence the availability of IGFs by competing with other IGFBPs for binding to IGF-1 and IGF-2. Research suggests that this persistent elevation of IGFBP-2 is largely driven by cytokine activity during CI, reflecting an adaptive response rather than a direct result of GH/IGF axis dysregulation. The clinical importance of IGFBP-2 is emphasized by its correlation with disease severity in conditions like sepsis and coronavirus disease 2019 (COVID-19), where its levels are markedly elevated compared to healthy controls and are similar to those observed in sepsis from various causes. Beyond its role in endocrine regulation, IGFBP-2 appears to play a part in metabolic and inflammatory pathways. Elevated IGFBP-2 levels have been linked to increased mortality and longer hospital stays, indicating its potential utility as a prognostic marker. Furthermore, measuring plasma IGFBP-2 may have other diagnostic applications, aiding in the assessment of CI when traditional biomarkers are inconclusive.

A spatiotemporal molecular atlas of mouse spinal cord injury identifies a distinct astrocyte subpopulation and therapeutic potential of IGFBP2

Spinal cord injury (SCI) triggers a cascade of intricate molecular and cellular changes that determine the outcome. In this study, we resolve the spatiotemporal organization of the injured mouse spinal cord and quantitatively assess in situ cell-cell communication following SCI. By analyzing existing single-cell RNA sequencing datasets alongside our spatial data, we delineate a subpopulation of Igfbp2-expressing astrocytes that migrate from the white matter (WM) to gray matter (GM) and become reactive upon SCI, termed Astro-GMii. Further, Igfbp2 upregulation promotes astrocyte migration, proliferation, and reactivity, and the secreted IGFBP2 protein fosters neurite outgrowth. Finally, we show that IGFBP2 significantly reduces neuronal loss and remarkably improves the functional recovery in a mouse model of SCI in vivo. Together, this study not only provides a comprehensive molecular atlas of SCI but also exemplifies how this rich resource can be applied to endow cells and genes with functional insight and therapeutic potential.

Identification of Disease-relevant, Sex-based Proteomic Differences in iPSC-derived Vascular Smooth Muscle

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insight into some aspects of human biology, however not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle than iPSCs. We also identified sex-based differences in iPSC- derived vascular smooth muscle in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease.

Significance

In this work, we have differentiated 4 male and 4 female iPSC lines into vascular smooth muscle cells, giving us the ability to identify statistically-significant sex-specific proteomic markers that are relevant to cardiovascular disease risk (such as PCK2, MTOR, IGFBP2, PTGR2, and SULTE1).

IGF Signaling in the Heart in Health and Disease

One of the most vital processes of the body is the cardiovascular system's proper operation. Physiological processes in the heart are regulated by the balance of cardioprotective and pathological mechanisms. The insulin-like growth factor system (IGF system, IGF signaling pathway) plays a pivotal role in regulating growth and development of various cells and tissues. In myocardium, the IGF system provides cardioprotective effects as well as participates in pathological processes. This review summarizes recent data on the role of IGF signaling in cardioprotection and pathogenesis of various cardiovascular diseases, as well as analyzes severity of these effects in various scenarios.

Predictive potential of various plasma inflammation-, angiogenesis-, and extracellular matrix remodeling-associated mediators for intra-amniotic inflammation and/or microbial invasion of the amniotic cavity in preterm labor

PURPOSE

To determine whether various inflammatory-, angiogenic/anti-angiogenic-, and extracellular matrix remodeling-associated proteins in plasma, alone or in combination with conventional blood-based markers, can predict intra-amniotic inflammation and/or microbial invasion of the amniotic cavity (IAI/MIAC) in women with spontaneous preterm labor (PTL).

METHODS

A total of 193 singleton pregnant women with PTL (23-33 weeks) were included in this retrospective cohort study. Plasma samples were obtained at the time of amniocentesis. Amniotic fluid (AF) was cultured for microorganism detection and consequent MIAC diagnosis. IL-6 levels were determined in AF and used to identify IAI (AF IL-6 ≥ 2.6 ng/mL). Endostatin, haptoglobin, IGFBP-2/3, LBP, M-CSF, MMP-2/8, pentraxin 3, PlGF, S100A8/A9, and VEGFR-1 levels were assayed in plasma samples by ELISA. CRP levels and neutrophil-to-lymphocyte ratio (NLR) were measured.

RESULTS

Plasma LBP, MMP-8, and S100A8/A9 levels, CRP levels, and NLR were significantly higher, and plasma IGFBP-2 and MMP-2 levels were significantly lower in women with IAI/MIAC than in those without this condition, whereas no baseline variables differed significantly between the two groups. Using a stepwise regression analysis, a noninvasive prediction model for IAI/MIAC was developed, which included plasma LBP, MMP-2, and MMP-8 levels (area under the curve [AUC], 0.785). The AUC for this prediction model was significantly or borderline greater than that of any single factor included in the model.

CONCLUSIONS

IGFBP-2, LBP, MMP-2, MMP-8, and S100A8/A9 may represent valuable plasma biomarkers for predicting IAI/MIAC in women with PTL. Combination of LBP, MMP-2, and MMP-8 expression data can significantly improve the predictive potential for IAI/MIAC.

Cross-species transcriptomics identifies obesity associated genes between human and mouse studies

BACKGROUND

Fundamentally defined by an imbalance in energy consumption and energy expenditure, obesity is a significant risk factor of several musculoskeletal conditions including osteoarthritis (OA). High-fat diets and sedentary lifestyle leads to increased adiposity resulting in systemic inflammation due to the endocrine properties of adipose tissue producing inflammatory cytokines and adipokines. We previously showed serum levels of specific adipokines are associated with biomarkers of bone remodelling and cartilage volume loss in knee OA patients. Whilst more recently we find the metabolic consequence of obesity drives the enrichment of pro-inflammatory fibroblast subsets within joint synovial tissues in obese individuals compared to those of BMI defined 'health weight'. As such this present study identifies obesity-associated genes in OA joint tissues which are conserved across species and conditions.

METHODS

The study utilised 6 publicly available bulk and single-cell transcriptomic datasets from human and mice studies downloaded from Gene Expression Omnibus (GEO). Machine learning models were employed to model and statistically test datasets for conserved gene expression profiles. Identified genes were validated in OA tissues from obese and healthy weight individuals using quantitative PCR method (N = 38). Obese and healthy-weight patients were categorised by BMI > 30 and BMI between 18 and 24.9 respectively. Informed consent was obtained from all study participants who were scheduled to undergo elective arthroplasty.

RESULTS

Principal component analysis (PCA) was used to investigate the variations between classes of mouse and human data which confirmed variation between obese and healthy populations. Differential gene expression analysis filtered on adjusted p-values of p < 0.05, identified differentially expressed genes (DEGs) in mouse and human datasets. DEGs were analysed further using area under curve (AUC) which identified 12 genes. Pathway enrichment analysis suggests these genes were involved in the biosynthesis and elongation of fatty acids and the transport, oxidation, and catabolic processing of lipids. qPCR validation found the majority of genes showed a tendency to be upregulated in joint tissues from obese participants. Three validated genes, IGFBP2 (p = 0.0363), DOK6 (0.0451) and CASP1 (0.0412) were found to be significantly different in obese joint tissues compared to lean-weight joint tissues.

CONCLUSIONS

The present study has employed machine learning models across several published obesity datasets to identify obesity-associated genes which are validated in joint tissues from OA. These results suggest obesity-associated genes are conserved across conditions and may be fundamental in accelerating disease in obese individuals. Whilst further validations and additional conditions remain to be tested in this model, identifying obesity-associated genes in this way may serve as a global aid for patient stratification giving rise to the potential of targeted therapeutic interventions in such patient subpopulations.

The diverging roles of insulin-like growth factor binding proteins in pulmonary arterial hypertension

Pulmonary hypertension (PH) is a progressive, severe and to date not curable disease of the pulmonary vasculature. Alterations of the insulin-like growth factor 1 (IGF-1) system are known to play a role in vascular pathologies and IGF-binding proteins (IGFBPs) are important regulators of the bioavailability and function of IGFs. In this study, we show that circulating plasma levels of IGFBP-1, IGFBP-2 and IGFBP-3 are increased in idiopathic pulmonary arterial hypertension (IPAH) patients compared to healthy individuals. These binding proteins inhibit the IGF-1 induced IGF-1 receptor (IGF1R) phosphorylation and exhibit diverging effects on the IGF-1 induced signaling pathways in human pulmonary arterial cells (i.e. healthy as well as IPAH-hPASMCs, and healthy hPAECs). Furthermore, IGFBPs are differentially expressed in an experimental mouse model of PH. In hypoxic mouse lungs, IGFBP-1 mRNA expression is decreased whereas the mRNA for IGFBP-2 is increased. In contrast to IGFBP-1, IGFBP-2 shows vaso-constrictive properties in the murine pulmonary vasculature. Our analyses show that IGFBP-1 and IGFBP-2 exhibit diverging effects on IGF-1 signaling and display a unique IGF1R-independent kinase activation pattern in human pulmonary arterial smooth muscle cells (hPASMCs), which represent a major contributor of PAH pathobiology. Furthermore, we could show that IGFBP-2, in contrast to IGFBP-1, induces epidermal growth factor receptor (EGFR) signaling, Stat-3 activation and expression of Stat-3 target genes. Based on our results, we conclude that the IGFBP family, especially IGFBP-1, IGFBP-2 and IGFBP-3, are deregulated in PAH, that they affect IGF signaling and thereby regulate the cellular phenotype in PH.

Recombinant Phytase Modulates Blood Amino Acids and Proteomics Profiles in Pigs Fed with Low-Protein, -Calcium, and -Phosphorous Diets

A beneficial effect of corn-expressed phytase (CEP) on the growth performance of pigs fed with very low-protein (VLP) diets was previously shown. Little is known whether this improvement is related to alterations in the expression profiles of blood proteins and amino acids (AAs). The objective of this study was to investigate whether supplementation of VLP, low-calcium (Ca), and low-P diets with a CEP would alter the blood AAs and protein expression profiles in pigs. Forty-eight pigs were subjected to one of the following groups (n = 8/group) for 4 weeks: positive control (PC), negative control-reduced protein (NC), NC + low-dose CEP (LD), NC + high-dose CEP (HD), LD with reduced Ca/P (LDR), and HD with reduced Ca/P (HDR). Plasma leucine and phenylalanine concentrations were reduced in NC; however, the LD diet recovered the concentration of these AAs. Serum proteomics analysis revealed that proteins involved with growth regulation, such as selenoprotein P were upregulated while the IGF-binding proteins family proteins were differentially expressed in CEP-supplemented groups. Furthermore, a positive correlation was detected between growth and abundance of proteins involved in bone mineralization and muscle structure development. Taken together, CEP improved the blood profile of some essential AAs and affected the expression of proteins involved in the regulation of growth.

Plasma Insulin-like Growth Factor-Binding Protein-2 of Critically Ill Patients Is Related to Disease Severity and Survival

Insulin-like growth factor-binding protein (IGFBP)-2 regulates the bioactivity of the anabolic hormone's insulin-like growth factors, which are decreased in sepsis and contribute to the catabolic status of severely ill patients. The circulating levels of IGFBP-2 in critical illness have been rarely studied; therefore, we evaluated IGFBP-2 plasma levels in patients with systemic inflammatory response syndrome (SIRS) or sepsis as well as healthy controls. Our analysis of 157 SIRS/sepsis patients revealed higher plasma IGFBP-2 levels compared to 22 healthy controls. Plasma IGFBP-2 levels correlated positively with procalcitonin but not with C-reactive protein, interleukin-6, or the leukocyte count. Septic shock patients exhibited higher IGFBP-2 levels than those with SIRS. Bacterial or SARS-CoV-2 infection did not influence plasma IGFBP-2 levels. There was no difference in the IGFBP-2 levels between ventilated and non-ventilated SIRS/sepsis patients, and vasopressor therapy did not alter these levels. Dialysis patients had elevated plasma IGFBP-2 levels. Survivors had lower plasma IGFBP-2 levels than non-survivors. In conclusion, our study indicates that plasma IGFBP-2 levels are associated with disease severity, renal failure, and mortality in SIRS/sepsis patients.

IGFBP2 promotes proliferation and cell migration through STAT3 signaling in Sonic hedgehog medulloblastoma

Medulloblastoma (MB) is the most common pediatric brain malignancy and is divided into four molecularly distinct subgroups: WNT, Sonic Hedgehog (SHHp53mut and SHHp53wt), Group 3, and Group 4. Previous reports suggest that SHH MB features a unique tumor microenvironment compared with other MB groups. To better understand how SHH MB tumor cells interact with and potentially modify their microenvironment, we performed cytokine array analysis of culture media from freshly isolated MB patient tumor cells, spontaneous SHH MB mouse tumor cells and mouse and human MB cell lines. We found that the SHH MB cells produced elevated levels of IGFBP2 compared to non-SHH MBs. We confirmed these results using ELISA, western blotting, and immunofluorescence staining. IGFBP2 is a pleiotropic member of the IGFBP super-family with secreted and intracellular functions that can modulate tumor cell proliferation, metastasis, and drug resistance, but has been understudied in medulloblastoma. We found that IGFBP2 is required for SHH MB cell proliferation, colony formation, and cell migration, through promoting STAT3 activation and upregulation of epithelial to mesenchymal transition markers; indeed, ectopic STAT3 expression fully compensated for IGFBP2 knockdown in wound healing assays. Taken together, our findings reveal novel roles for IGFBP2 in SHH medulloblastoma growth and metastasis, which is associated with very poor prognosis, and they indicate an IGFBP2-STAT3 axis that could represent a novel therapeutic target in medulloblastoma.

Adiponectin, IGFBP-1 and -2 are independent predictors in forecasting prediabetes and type 2 diabetes

Objective

Adiponectin and insulin-like growth factor (IGF) binding proteins IGFBP-1 and IGFBP-2 are biomarkers of insulin sensitivity. IGFBP-1 reflects insulin sensitivity in the liver, adiponectin in adipose tissue and IGFBP-2 in both tissues. Here, we study the power of the biomarkers adiponectin, IGFBP-1, IGFBP-2, and also included IGF-I and IGF-II, in predicting prediabetes and type 2 diabetes (T2D) in men and women with normal oral glucose tolerance (NGT).

Design

Subjects with NGT (35-56 years) recruited during 1992-1998 were re-investigated 8-10 years later. In a nested case control study, subjects progressing to prediabetes (133 women, 164 men) or to T2D (55 women, 98 men) were compared with age and sex matched NGT controls (200 women and 277 men).

Methods

The evaluation included questionnaires, health status, anthropometry, biochemistry and oral glucose tolerance test.

Results

After adjustment, the lowest quartile of adiponectin, IGFBP-1 and IGFBP-2 associated independently with future abnormal glucose tolerance (AGT) in both genders in multivariate analyses. High IGFs predicted weakly AGT in women. In women, low IGFBP-2 was the strongest predictor for prediabetes (OR:7.5), and low adiponectin for T2D (OR:29.4). In men, low IGFBP-1 was the strongest predictor for both prediabetes (OR:13.4) and T2D (OR:14.9). When adiponectin, IGFBP-1 and IGFBP-2 were combined, the ROC-AUC reached 0.87 for women and 0.79 for men, higher than for BMI alone.

Conclusion

Differences were observed comparing adipocyte- and hepatocyte-derived biomarkers in forecasting AGT in NGT subjects. In women the strongest predictor for T2D was adiponectin and in men IGFBP-1, and for prediabetes IGFBP-2 in women and IGFBP-1 in men.

Mutual connected IL-6, EGFR and LIN28/Let7-related mechanisms modulate PD-L1 and IGF upregulation in HNSCC using immunotherapy

The development of techniques and immunotherapies are widely applied in cancer treatment such as checkpoint inhibitors, adoptive cell therapy, and cancer vaccines apart from radiation therapy, surgery, and chemotherapy give enduring anti-tumor effects. Minority people utilize single-agent immunotherapy, and most people adopt multiple-agent immunotherapy. The difficulties are resolved by including the biomarkers to choose the non-responders' and responders' potentials. The possibility of the potential complications and side effects are examined to improve cancer therapy effects. The Head and Neck Squamous Cell Carcinoma (HNSCC) is analyzed with the help of programmed cell death ligand 1 (PD-L1) and Insulin-like growth factor (IGF). But how IGF and PD-L1 upregulation depends on IL-6, EGFR, and LIN28/Let7-related mechanisms are poorly understood. Briefly, IL-6 stimulates gene expressions of IGF-1/2, and IL-6 cross-activates IGF-1R signaling, NF-κB, and STAT3. NF-κB, up-regulating PD-L1 expressions. IL-6/JAK1 primes PD-L1 for STT3-mediated PD-L1 glycosylation, stabilizes PD-L1 and trafficks it to the cell surface. Moreover, ΔNp63 is predominantly overexpressed over TAp63 in HNSCC, elevates circulating IGF-1 levels by repressing IGFBP3, and activates insulin receptor substrate 1 (IRS1).TP63 and SOX2 form a complex with CCAT1 to promote EGFR expression. EGFR activation through EGF binding extends STAT3 activation, and EGFR and its downstream signaling prolong PD-L1 mRNA half-life. PLC-γ1 binding to a cytoplasmic motif of elevated PD-L1 improves EGF-induced activation of inositol 1,4,5-tri-phosphate (IP3), and diacylglycerol (DAG) subsequently elevates RAC1-GTP. RAC1-GTP was convincingly demonstrated to induce the autocrine production and action of IL-6/IL-6R, forming a feedback loop for IGF and PD-L1 upregulation. Furthermore, the LIN28-Let7 axis mediates the NF-κB-IL-6-STAT3 amplification loop, activated LIN28-Let7 axis up-regulates RAS, AKT, IL-6, IGF-1/2, IGF-1R, Myc, and PD-L1, plays pivotal roles in IGF-1R activation and Myc, NF-κB, STAT3 concomitant activation. Therefore, based on a detailed mechanisms review, our article firstly reveals that IL-6, EGFR, and LIN28/Let7-related mechanisms mediate PD-L1 and IGF upregulation in HNSCC, which comprehensively influences immunity, inflammation, metabolism, and metastasis in the tumor microenvironment, and might be fundamental for overcoming therapy resistance.

Reduced IGFBP-2 related immunoreactivity in human serum correlates with arterial stiffness in a healthy Chinese population

BACKGROUND

Circulating insulin-like growth factor binding protein 2 (IGFBP-2) is associated with metabolic changes in both physiological and pathological conditions. The aim of this study was to investigate the correlation between IGFBP-2 related immunoreactivity in serum and arterial stiffness in a healthy Chinese population.

METHODS

In this cross-sectional study, 360 healthy participants aged 37-87 years were recruited from 1500 and were divided into three groups according to serum IGFBP-2 related immunoreactivity (Tertile I, 25.437 ng/ml-120.870 ng/ml; Tertile II, 120.871 ng/ml-161.914 ng/ml; Tertile III, 161.915 ng/ml-321.636 ng/ml). Arterial stiffness was evaluated by measuring the brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI), and carotid intima-media thickness (cIMT). The association between IGFBP-2 related immunoreactivity and arterial stiffness was estimated by multiple stepwise regression.

RESULTS

Compared with the other two groups population, the individuals in Tertile I had significantly older age (62.66 ± 13.30 years, P < 0.01), lower level of triglyceride (1.08 ± 0.70 mmol/l, P < 0.01) and E/A (peak velocity of early filling and preak velocity of atrial filling ratio) (0.90 ± 0.33, P < 0.05). IGFBP-2 related immunoreactivity was inversely related with baPWV in the total population (r = -0.171, P < 0.01) and in Tertile I (r = -0.275, P < 0.01). After adjusting for age and the other confounders, no association was found between IGFBP-2 related immunoreactivity and baPWV in the total population. However, In Tertile I, reduced IGFBP-2 related immunoreactivity in serum was an independent risk factor of baPWV acceleration in three different adjustment models: Model 1 (no adjustment, P < 0.01), Model 2 (adjusted for age, P < 0.05), and Model 3 (adjusted for all variables, P < 0.05).

CONCLUSION

IGFBP-2 related immunoreactivity in serum is inversely associated with baPWV in a healthy Chinese population. This association did not change after adjustment for conventional risk factors for cardiovascular diseases in the subjects with the lowest IGFBP-2 related immunoreactivity. Consequently, reduction of IGFBP-2 related immunoreactivity may be a predictor of arterial stiffness. IGFBP-2 seems to be a potential intervention target in early atherosclerosis.

A genome-wide screen for resilient responses in growing pigs

Background

There is a growing interest to decipher the genetic background of resilience and its possible improvement through selective breeding. The objective of the present study was to provide new insights into the genetic make-up of resilience in growing pigs by identifying genomic regions and candidate genes associated with resilience indicators. Commercial Duroc pigs were challenged with an attenuated Aujeszky vaccine at 12 weeks of age. Two resilience indicators were used: deviation from the expected body weight at 16 weeks of age given the growth curve of non-vaccinated pigs (∆BW) and the increase in acute-phase protein haptoglobin at four days post-vaccination (∆HP). Genome-wide association analyses were carried out on 445 pigs, using genotypes at 41,165 single nucleotide polymorphisms (SNPs) and single-marker and Bayesian multiple-marker regression approaches.

Results

Genomic regions on pig chromosomes 2, 8, 9, 11 (∆BW) and 8, 9, 13 (∆HP) were found to be associated with the resilience indicators and explained high proportions of their genetic variance. The genomic regions that were associated explained 27 and 5% of the genetic variance of ∆BW and ∆HP, respectively. These genomic regions harbour promising candidate genes that are involved in pathways related to immune response, response to stress, or signal transduction (CD6, PTGDR2, IKZF1, RNASEL and MYD88), and growth (GRB10 and LCORL).

Conclusions

Our study identified novel genomic regions that are associated with two resilience indicators (∆BW and ∆HP) in pigs. These associated genomic regions harbour potential candidate genes involved in immune response and growth pathways, which emphasise the strong relationship between resilience and immune response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-022-00739-1.

Lectin-Based Protein Microarray for the Glycan Analysis of Colorectal Cancer Biomarkers: The Insulin-Like Growth Factor System

Lectin-based protein microarrays are used for glycoprofiling of various kinds of biological samples. Here we describe lectin-based microarray assay in the reverse-phase format where glycoprotein samples are spotted onto microarray slide and then are incubated with set of lectins. This configuration allows high-throughput screening of a large cohort of samples by a set of lectins without need of separation of glycans from glycoproteins. We applied the described method for glycan analysis of glycoprotein biomarkers of colorectal cancer associated with the insulin-like growth factor system.

Bladder Cancer Extracellular Vesicles Elicit a CD8 T Cell-Mediated Antitumor Immunity

Tumor-derived extracellular vesicles (TEVs) play crucial roles in mediating immune responses, as they carry and present functional MHC-peptide complexes that enable them to modulate antigen-specific CD8⁺ T-cell responses. However, the therapeutic potential and immunogenicity of TEV-based therapies against bladder cancer (BC) have not yet been tested. Here, we demonstrated that priming with immunogenic Extracellular Vesicles (EVs) derived from murine MB49 BC cells was sufficient to prevent MB49 tumor growth in mice. Importantly, antibody-mediated CD8⁺ T-cell depletion diminished the protective effect of MB49 EVs, suggesting that MB49 EVs elicit cytotoxic CD8⁺ T-cell-mediated protection against MB49 tumor growth. Such antitumor activity may be augmented by TEV-enhanced immune cell infiltration into the tumors. Interestingly, MB49 EV priming was unable to completely prevent, but significantly delayed, unrelated syngeneic murine colon MC-38 tumor growth. Cytokine array analyses revealed that MB49 EVs were enriched with pro-inflammatory factors that might contribute to increasing tumor-infiltrating immune cells in EV-primed MC-38 tumors. These results support the potential application of TEVs in personalized medicine, and open new avenues for the development of adjuvant therapies based on patient-derived EVs aimed at preventing disease progression.

Lipid droplet availability affects neural stem/progenitor cell metabolism and proliferation

Neural stem/progenitor cells (NSPCs) generate new neurons throughout adulthood. However, the underlying regulatory processes are still not fully understood. Lipid metabolism plays an important role in regulating NSPC activity: build-up of lipids is crucial for NSPC proliferation, whereas break-down of lipids has been shown to regulate NSPC quiescence. Despite their central role for cellular lipid metabolism, the role of lipid droplets (LDs), the lipid storing organelles, in NSPCs remains underexplored. Here we show that LDs are highly abundant in adult mouse NSPCs, and that LD accumulation is significantly altered upon fate changes such as quiescence and differentiation. NSPC proliferation is influenced by the number of LDs, inhibition of LD build-up, breakdown or usage, and the asymmetric inheritance of LDs during mitosis. Furthermore, high LD-containing NSPCs have increased metabolic activity and capacity, but do not suffer from increased oxidative damage. Together, these data indicate an instructive role for LDs in driving NSPC behaviour.

Targeting the HIF-1α-IGFBP2 axis therapeutically reduces IGF1-AKT signaling and blocks the growth and metastasis of relapsed anaplastic Wilms tumor

For patients with anaplastic Wilms tumor (WiT), metastasis and recurrence are common, and prognosis is generally poor. Novel therapies are needed to improve outcomes for patients with this high-risk WiT. A potential contributor to WiT development is constitutive activation of AKT by insulin-like growth factor 1 (IGF1) and its receptor (IGF1R) signaling pathway, but the complete underlying mechanism remains unclear. Here, we demonstrate that the hypoxia-inducible factor 1α (HIF-1α)-IGF binding protein 2 (IGFBP2) axis and the tumor-specific IGF1A are key players for constitutive activation of IGF1-AKT signaling leading to the tumor malignancy. HIF-1α and IGFBP2 are highly expressed in a majority of WiT patient samples. Deficiency of either HIF-1α or IGFBP2 or IGF1 in the tumor cells significantly impairs tumor growth and nearly abrogates metastasis in xenografted mice. Pharmacologic targeting of HIF-1α by echinomycin delivered via nanoliposomes can efficiently restrain growth and metastasis of patient-derived relapsed anaplastic WiT xenografts. Liposomal echinomycin is more potent and effective in inhibiting WiT growth than vincristine in an anaplastic WiT mouse model, and eliminates metastasis by suppressing HIF-1α targets and the HIF-1α-IGFBP2 axis, which governs IGF1-AKT signaling.

IGFBP2 Is a Potential Master Regulator Driving the Dysregulated Gene Network Responsible for Short Survival in Glioblastoma Multiforme

Only 2% of glioblastoma multiforme (GBM) patients respond to standard therapy and survive beyond 36 months (long-term survivors, LTS), while the majority survive less than 12 months (short-term survivors, STS). To understand the mechanism leading to poor survival, we analyzed publicly available datasets of 113 STS and 58 LTS. This analysis revealed 198 differentially expressed genes (DEGs) that characterize aggressive tumor growth and may be responsible for the poor prognosis. These genes belong largely to the Gene Ontology (GO) categories “epithelial-to-mesenchymal transition” and “response to hypoxia.” In this article, we applied an upstream analysis approach that involves state-of-the-art promoter analysis and network analysis of the dysregulated genes potentially responsible for short survival in GBM. Binding sites for transcription factors (TFs) associated with GBM pathology like NANOG, NF-κB, REST, FRA-1, PPARG, and seven others were found enriched in the promoters of the dysregulated genes. We reconstructed the gene regulatory network with several positive feedback loops controlled by five master regulators [insulin-like growth factor binding protein 2 (IGFBP2), vascular endothelial growth factor A (VEGFA), VEGF165, platelet-derived growth factor A (PDGFA), adipocyte enhancer-binding protein (AEBP1), and oncostatin M (OSMR)], which can be proposed as biomarkers and as therapeutic targets for enhancing GBM prognosis. A critical analysis of this gene regulatory network gives insights into the mechanism of gene regulation by IGFBP2 via several TFs including the key molecule of GBM tumor invasiveness and progression, FRA-1. All the observations were validated in independent cohorts, and their impact on overall survival has been investigated.

Inflammatory profile of induced sputum composition in systemic sclerosis and comparison with healthy volunteers

Systemic sclerosis (SSc) is a potentially serious and disabling connective tissue disease specially in case of interstitial lung disease (SSc-ILD). The aim of our study was to evaluate the potential utility of dosing in the induced sputum (IS) and to compare their levels in SSc-ILD and SSc-nonILD patients, as well as in healthy volunteers (HV). IS and sera values were also compared. In a prospective cross-sectional analysis, we studied the IS and serum provided from 25 SSc patients, 15 SSc-nonILD and 10 SSc-ILD, compared to 25 HV. We analyzed sputum cell composition and quantified in the supernatant and corresponding serum by commercially available immunoassays: IGFBP-1, IGFBP-2, IGFBP-3, TGF-β, IL-8, TNF-α, YKL-40, MMP-7 and MMP-9. Lung function was studied by the determination of FEV-1 (%), FVC (%), DLCO (%) and KCO (%). The IS of SSc patients had a lower weight than HV (p<0.05, p<0.01) without any significant difference with regard to the cellularity. IGFBP-1 (p < 0.0001), TGF-β (p < 0.05), IL-8 (p < 0.05), YKL-40 (p < 0.0001) and MMP-7 (p < 0.01) levels were increased in the IS of SSc patients compared to HV. Only IL-8 serum levels (p < 0.001) were increased in SSc patients compared to HV. Neither in IS nor in serum were observed differences between SSc-ILD and SSc-nonILD patients. Correlations were observed between IS IL-8 levels and FEV-1 (%) (r =  = − 0.53, p < 0.01), FVC (%) (r = − 0.51, p < 0.01) and annualized ∆KCO (%) (r = 0.57, p < 0.05), between IS TGF-β levels and annualized ∆FEV-1 (%) (r =  = − 0.57, p < 0.05), between IS IGFBP-2 levels and annualized ∆KCO (%) (r = 0.56, p < 0.05). Our study showed that SSc patients exhibit raised IS levels of IGFBP-1, TGF-β, IL-8, YKL-40 and MMP-7, molecules known to be involved in lung remodeling and fibrotic process, without any significant difference between SSc-ILD and SSc-nonILD patients. IL-8, TGF-β and IGFBP-2 are correlated with lung function in SSc patients which emphasize clinical relevance. IS analysis represents a new approach to understand lung inflammatory process in SSc patients. A longitudinal study is needed to evaluate their pathophysiological relevance.

IGFBP-1 and IGFBP-2 are associated with a decreased pulse-wave velocity in young, healthy adults

Background and aims

In healthy, young adults we analyzed a panel of cardiovascular disease related proteins in plasma and compared them with the vascular health of the subjects. The aim was to identify proteins with a relationship to the early atherosclerotic process in healthy individuals.

Methods

We employed the proximity extension assay from OLINK proteomics to analyze 92 cardiovascular disease (CVD) related proteins on 833 subjects (men and women, ages 18–26). The women were further divided into an estrogen-using group and non-users. Protein expression was analyzed using principal component analysis (PCA). The following vascular examinations were performed: Pulse-wave velocity (PWV), augmentation index (AIX), carotid-intima media thickness (cIMT).

Results

Three principal components were obtained using PCA to analyze the protein expression. None of the obtained principal components correlated significantly with AIX or cIMT. One of the components, explaining 6% of the total variance of the data, was significantly correlated with PWV. Upon examination of the proteins with the highest factor loadings on this component independently in a multivariable model, adjusting for established CVD risk biomarkers, insulin-like growth factor-binding protein 1 (IGFBP-1) and insulin-like growth factor-binding protein 2 (IGFBP-2) were found to independently, negatively correlate with PWV. Among the established risk factors included in the multivariable model, age was significantly and adversely correlated with all vascular measurements.

Conclusions

In this population of healthy, young adults, groups of CVD related proteins correlate with PWV, but not AIX or cIMT. This group of proteins, of which IGFBP-1 and IGFBP-2 were independently, negatively correlated in a multivariable model with PWV, could have benificial effects on vascular stiffness. The robust association between age and PWV, AIX and cIMT provide insight into the impact of aging on the vasculature, which is detectable even in a population of young, healthy, non-smoking individuals of ages spanning only 8 years.

Supplementary information

The online version contains supplementary material available at 10.1186/s12872-021-01914-w.

Circulating IGFBP-2 levels reveal atherogenic metabolic risk in schizophrenic patients using atypical antipsychotics

OBJECTIVES

Second generation antipsychotics (SGAs) induce weight gain and dyslipidemia, albeit with important intervariability. Insulin-like growth factor binding protein (IGFBP)-2 is proposed as a circulating biomarker negatively associated with waist circumference and hypertriglyceridemia. Thus, we tested whether metabolic alterations developed upon the use of SGAs are associated with plasma IGFBP-2 levels.

METHODS

A cross-sectional study was performed in 87 men newly diagnosed with schizophrenia and administered for approximately 20 months with olanzapine or risperidone as their first antipsychotic treatment. Plasma IGFBP-2 concentration, anthropometric data, as well as glucose and lipid profiles were determined at the end of the treatments.

RESULTS

IGFBP-2 levels were similar between patients using olanzapine or risperidone and were negatively correlated with waist circumference, insulin sensitivity, and plasma triglycerides (TG). A higher proportion of men with a hypertriglyceridemic (hyperTG) waist phenotype was found in patients with IGFBP-2 levels lower than 220 ng/mL (43% for olanzapine and 13% for risperidone) compared to those with IGFBP-2 above this threshold (10% and 0%, respectively).

CONCLUSIONS

IGFBP-2 may have a role in altering metabolic risk in schizophrenic patients using SGAs. Longitudinal studies are required to evaluate whether IGFBP-2 can predict the development of a hyperTG waist phenotype in this population.

Revealing the role of the human blood plasma proteome in obesity using genetic drivers

Blood circulating proteins are confounded readouts of the biological processes that occur in different tissues and organs. Many proteins have been linked to complex disorders and are also under substantial genetic control. Here, we investigate the associations between over 1000 blood circulating proteins and body mass index (BMI) in three studies including over 4600 participants. We show that BMI is associated with widespread changes in the plasma proteome. We observe 152 replicated protein associations with BMI. 24 proteins also associate with a genome-wide polygenic score (GPS) for BMI. These proteins are involved in lipid metabolism and inflammatory pathways impacting clinically relevant pathways of adiposity. Mendelian randomization suggests a bi-directional causal relationship of BMI with LEPR/LEP, IGFBP1, and WFIKKN2, a protein-to-BMI relationship for AGER, DPT, and CTSA, and a BMI-to-protein relationship for another 21 proteins. Combined with animal model and tissue-specific gene expression data, our findings suggest potential therapeutic targets further elucidating the role of these proteins in obesity associated pathologies.

The Roles of Insulin-Like Growth Factor Binding Protein Family in Development and Diseases

The insulin-like growth factor (IGF) system comprises ligands of IGF-I/II, IGF receptors (IGFR), IGF binding proteins (IGFBPs), and IGFBP hydrolases. The IGF system plays multiple roles during various disease development as IGFs are widely involved in cell proliferation and differentiation through regulating DNA transcription. Meanwhile, IGFBPs, which are mainly synthesized in the liver, can bind to IGFs and perform two different functions: either inhibition of IGFs by forming inactive compounds with IGF or enhancement of the function of IGFs by strengthening the IGF-IGFR interaction. Interestingly, IGFBPs may have wider functions through IGF-independent mechanisms. Studies have shown that IGFBPs play important roles in cardiovascular disease, tumor progression, fetal growth, and neuro-nutrition. In this review, we emphasize that different IGFBP family members have common or unique functions in numerous diseases; moreover, IGFBPs may serve as biomarkers for disease diagnosis and prediction.

Compensatory Response of the Somatotropic Axis from IGFBP-2b Gene Editing in Rainbow Trout (Oncorhynchus mykiss)

Rainbow trout with gene editing-induced reductions in serum insulin-like growth factor binding protein (IGFBP)-2b exhibit similar growth performance compared to fish without IGFBP-2b gene disruption. The objective of this study is to determine how the components of the insulin-like growth factor (IGF)/IGFBP system respond to a reduction in serum IGFBP-2b abundance. Editing the IGFBP-2b genes in rainbow trout resulted in an 83% decrease in serum IGFBP-2b in mutants. This resulted in a 35% reduction in serum IGF-I, which was offset by reduced expression of hepatic igfbp-1a2 and increased muscle igfr-1a; these responses suggest that an increased IGF-I signaling capacity offset reductions in serum IGF-I. During feed deprivation, the differential expression of igfbp genes supports the attenuation of the growth inhibitory response, likely due to the further reduction in serum IGF-I that alleviated the need for an IGF-inhibitory response. Unique igfbp expression patterns occurred during refeeding, suggesting an enhanced IGF-I signaling capacity in controls. Collectively, these findings support that the role of IGFBP-2b is to regulate serum IGF-I concentrations. The compensatory regulation of IGF/IGFBP system genes indicates that adjustments in other IGFBP, both circulating and at the local level, maintain IGF-I signaling at a level appropriate for the nutritional state of the fish.

Pediatric pulmonary hypertension: insulin-like growth factor-binding protein 2 is a novel marker associated with disease severity and survival

BACKGROUND

Insulin-like growth factors (IGFs), and their binding proteins (IGFBPs), play a significant role in cardiovascular function and may influence the pathobiology of PAH. We determined the diagnostic and prognostic value of IGF1 and IGFBP2 in pediatric PAH.

METHODS

Serum was analyzed by ELISA for IGF1 and IGFBP2 in pediatric PAH subjects from the NHLBI PAH Biobank (PAHB, n = 175) and a cohort of asthmatic subjects (n = 46, age 0-21 years) as a chronic pediatric pulmonary disease control. Biomarkers were analyzed with demographic and clinical variables for PAH severity.

RESULTS

Serum IGF1 was significantly lower in PAH compared to controls, while IGFBP2 was elevated in PAH subjects compared to controls. In the PAHB, IGF1 was negatively associated with mPAP and PVR, while IGFBP2 was positively associated with PVR and negatively associated with cardiac output and 6-min walk distance. Higher IGFBP2 levels were associated with use of prostacyclin therapy. IGFBP2 was associated with death, transplant, or palliative shunt with a Cox proportional hazard ratio of 8.8 (p < 0.001) but not IGF1 (p = 0.13).

CONCLUSIONS

Circulating IGFBP2 is a novel marker for pediatric PAH, which is associated with worse functional status, and survival. IGF axis dysregulation may be an important mechanistic target in pediatric pulmonary arterial hypertension.

IMPACT

Pediatric pulmonary hypertension is a severe disease, with poorly understood pathobiology. There are few studies looking at the pathobiology of pulmonary hypertension only in children. The IGF axis is dysregulated in pediatric pulmonary arterial hypertension. IGF axis dysregulation, with increased IGFBP2, is associated with worse clinical outcomes in pediatric pulmonary artery hypertension. IGF axis dysregulation gives new insight into the disease process and may be a mechanistic or therapeutic target.

Insulin Resistance and Endometrial Cancer: Emerging Role for microRNA

Endometrial cancer (EC) remains one of the most common cancers of the female reproductive system. Epidemiological and clinical data implicate insulin resistance (IR) and its accompanying hyperinsulinemia as key factors in the development of EC. MicroRNAs (miRNAs) are short molecules of non-coding endogenous RNA that function as post-transcriptional regulators. Accumulating evidence has shown that the miRNA expression pattern is also likely to be associated with EC risk factors. The aim of this work was the verification of the relationships between IR, EC, and miRNA, and, as based on the literature data, elucidation of miRNA's potential utility for EC prevention in IR patients. The pathways affected in IR relate to the insulin receptors, insulin-like growth factors and their receptors, insulin-like growth factor binding proteins, sex hormone-binding globulin, and estrogens. Herein, we present and discuss arguments for miRNAs as a plausible molecular link between IR and EC development. Specifically, our careful literature search indicated that dysregulation of at least 13 miRNAs has been ascribed to both conditions. We conclude that there is a reasonable possibility for miRNAs to become a predictive factor of future EC in IR patients.

Regulation of β-catenin by IGFBP2 and its cytoplasmic actions in glioma

PURPOSE

IGFBP2 is one of the highly expressed genes in glioblastoma (GBM). It has both IGF dependent and independent activities. IGF independent actions are mediated by the activation of integrin signalling through its RGD motif present at C-terminal domain. One of the actions of IGFBP2 is to regulate β-catenin by the inactivation of GSK3β, which preferentially accumulates in the cytoplasm. The mechanism of nuclear β-catenin regulation by IGFBP2 and role of cytoplasmic β-catenin is not clear. We aimed to understand the mechanism in GBM cell lines.

METHODS

The gene expression studies were performed by RT-PCR, western blot analysis; the knockdown of genes was performed by shRNA transfection; RNAIP and luciferase reporter assays were utilized to study the cytoplasmic regulation of genes by β-catenin; neurosphere assays were performed to study the stemness of cells.

RESULTS

IGFBP2 overexpression or treatment in GBM cells regulates β-catenin, TRIM33 (E3 ubiquitin ligase) and Oct4 genes. TRIM33 was induced by IGFBP2. β-catenin was found to accumulate predominantly in the cytoplasm and nuclear β-catenin was depleted by IGFBP2 induced TRIM33. IGFBP2 regulated cytoplasmic β-catenin binds to 3' UTR of Oct4 RNA. IGFBP2 was also able to induce stemness of glioma cells.

CONCLUSIONS

IGFBP2 induces TRIM33 which regulates the nuclear β-catenin protein. In addition, IGFBP2 stabilizes the cytoplasmic β-catenin which is involved in the regulation of Oct4 transcript and consequently induction of stemness of glioma cells.

Serum minerals (Ca, P, Co, Mn, Ni, Cd) and growth hormone (IGF-1 and IGF-2) levels in postmenopausal Saudi women with osteoporosis

Osteoporosis is reported to be common among Saudi women. Several minerals appear to be important determinants of insulin-like growth factor (IGF), the bioactivity of which regulates bone and mineral metabolism. Here we proposed that mineral status may alter the IGF system among individuals with osteoporosis. This study aims to evaluate the relationships between essential elements and IGF levels among postmenopausal Saudi women with osteoporosis. A total of 128 postmenopausal Saudi women aged ≥50 years old were recruited in this study. Diagnosis of osteoporosis was done by using dual-energy x-ray absorptiometry to determine the bone minerals density (BMD). Serum calcium and phosphate were determined using routine chemical analyzer. Serum Co, Mn, Ni, Cd were measured using inductively coupled plasma mass spectrometry. Serum IGF-1 and IGF-2 were determined using Luminex xMAP. Using stepwise linear regression analysis, only Cd was identified to be significantly associated with IGF1 in osteoporosis, explaining 3% (confidence interval 0.01-0.05; P = 0001) of the variance perceived. Our results suggest that Cd exposure indirectly affects BMD which may increase the risk of osteoporosis in postmenopausal women. Further longitudinal study using a larger sample size is recommended to determine causality of Cd levels and IGF-1.

IGF-1 and hyperglycaemia-induced FOXA1 and IGFBP-2 affect epithelial to mesenchymal transition in prostate epithelial cells

Localized prostate cancer (PCa) is a manageable disease but for most men with metastatic disease, it is often fatal. A western diet has been linked with PCa progression and hyperglycaemia has been associated with the risk of lethal and fatal prostate cancer. Using PCa cell lines, we examined the impact of IGF-I and glucose on markers of epithelial-to-mesenchymal transition (EMT), migration and invasion. We examined the underlying mechanisms using cell lines and tumour tissue samples. IGF-I had differential effects on the process of EMT: inhibiting in normal and promoting in cancer cells, whereas hyperglycamia alone had a stimulatory effect in both. These effects were independent of IGF and in both cases, hyperglycaemia induced an increase IGFBP-2(tumour promoter) and FOXA1. A positive correlation existed between levels of IGFBP-2 and FOXA1 in benign and cancerous prostate tissue samples and in vitro and in vivo data indicated that FOXA1 strongly interacted with the IGFBP-2 gene in normal prostate epithelial cells that was associated with a negative regulation of IGFBP-2, whereas in cancer cells the level of FOXA1 associating with the IGFBP-2 gene was minimal, suggesting loss of this negative regulation. IGF-I and hyperglycaemia-induced FOXA1/IGFBP-2 play important roles in EMT.

Characterizing the heterogeneity in 5-aminolevulinic acid-induced fluorescence in glioblastoma

OBJECTIVE

5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence is an effective surgical adjunct for the intraoperative identification of tumor tissue during resection of high-grade gliomas. The use of 5-ALA-induced PpIX fluorescence in glioblastoma (GBM) has been shown to double the extent of gross-total resection and 6-month progression-free survival. The heterogeneity of 5-ALA-induced PpIX fluorescence observed during surgery presents a technical and diagnostic challenge when utilizing this tool intraoperatively. While some regions show bright fluorescence after 5-ALA administration, other regions do not, despite that both regions of the tumor may be histopathologically indistinguishable. The authors examined the biological basis of this heterogeneity using computational methods.

METHODS

The authors collected both fluorescent and nonfluorescent GBM specimens from a total of 14 patients undergoing surgery and examined their gene expression profiles.

RESULTS

In this study, the authors found that the gene expression patterns characterizing fluorescent and nonfluorescent GBM surgical specimens were profoundly different and were associated with distinct cellular functions and different biological pathways. Nonfluorescent tumor tissue tended to resemble the neural subtype of GBM; meanwhile, fluorescent tumor tissue did not exhibit a prominent pattern corresponding to known subtypes of GBM. Consistent with this observation, neural GBM samples from The Cancer Genome Atlas database exhibited a significantly lower fluorescence score than nonneural GBM samples as determined by a fluorescence gene signature developed by the authors.

CONCLUSIONS

These results provide a greater understanding regarding the biological basis of differential fluorescence observed intraoperatively and can provide a basis to identify novel strategies to maximize the effectiveness of fluorescence agents.

Intracellular Insulin-like growth factor binding protein 2 (IGFBP2) contributes to the senescence of keratinocytes in psoriasis by stabilizing cytoplasmic p21

Psoriasis is a chronic Th1/Th17 lymphocytes-mediated inflammatory skin disease, in which epidermal keratinocytes exhibit a peculiar senescent state, resistance to apoptosis and the acquisition of senescence-associated secretory phenotype (SASP). SASP consists of the release of soluble factors, including IGFBPs, that exert extracellular and intracellular functions in IGF-dependent or independent manner.In this report, we investigated the expression and function of IGFBP2 in senescent keratinocytes isolated from the skin of patients with plaque psoriasis. We found that IGFBP2 is aberrantly expressed and released by these cells in vivo, as well as in vitro in keratinocyte cultures undergoing progressive senescence, and it associates with the cyclin-dependent kinase inhibitors p21 and p16 expression. For the first time, we provide evidence for a dual action of IGFBP2 in psoriatic keratinocytes during growth and senescence processes. While extracellular IGFBP2 counter-regulates IGF-induced keratinocyte hyper-proliferation, intracellular IGFBP2 inhibits apoptosis by interacting with p21 and protecting it from ubiquitin-dependent degradation. Indeed, we found that cytoplasmic p21 sustains anti-apoptotic processes, by inhibiting pro-caspase 3 cleavage and JNK phosphorylation in senescent psoriatic keratinocytes. As a consequence, abrogation of p21, as well as that of IGFBP2, found to stabilize cytoplasmic p21 levels, lead to the restoration of apoptosis mechanisms in psoriatic keratinocytes, commonly observed in healthy cells.

Development of a novel assay for IGFBP-2 complexed with IGF-I and-II in human serum

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.

Differential stromal reprogramming in benign and malignant naturally occurring canine mammary tumours identifies disease-modulating stromal components

While cancer-associated stroma (CAS) in malignant tumours is well described, stromal changes in benign forms of naturally occurring tumours remain poorly characterized. Spontaneous canine mammary carcinomas (mCA) are viewed as excellent models of human mCA. We have recently reported highly conserved stromal reprogramming between canine and human mCA based on transcriptome analysis of laser-capture-microdissected FFPE specimen. To identify stromal changes between benign and malignant mammary tumours, we have analysed matched normal and adenoma-associated stroma (AAS) from 13 canine mammary adenomas and compared them to previous data from 15 canine mCA. Our analyses reveal distinct stromal reprogramming even in small benign tumours. While similarities between AAS and CAS exist, the stromal signature clearly distinguished adenomas from mCA. The distinction between AAS and CAS is further substantiated by differential enrichment in several hallmark signalling pathways as well as differential abundance in cellular composition. Finally, we identify COL11A1, VIT, CD74, HLA-DRA, STRA6, IGFBP4, PIGR, and TNIP1 as strongly discriminatory stromal genes between adenoma and mCA, and demonstrate their prognostic value for human breast cancer. Given the relevance of canine CAS as a model for the human disease, our approach identifies disease-modulating stromal components with implications for both human and canine breast cancer.

Identifying Protein-metabolite Networks Associated with COPD Phenotypes

Chronic obstructive pulmonary disease (COPD) is a disease in which airflow obstruction in the lung makes it difficult for patients to breathe. Although COPD occurs predominantly in smokers, there are still deficits in our understanding of the additional risk factors in smokers. To gain a deeper understanding of the COPD molecular signatures, we used Sparse Multiple Canonical Correlation Network (SmCCNet), a recently developed tool that uses sparse multiple canonical correlation analysis, to integrate proteomic and metabolomic data from the blood of 1008 participants of the COPDGene study to identify novel protein-metabolite networks associated with lung function and emphysema. Our aim was to integrate -omic data through SmCCNet to build interpretable networks that could assist in the discovery of novel biomarkers that may have been overlooked in alternative biomarker discovery methods. We found a protein-metabolite network consisting of 13 proteins and 7 metabolites which had a -0.34 correlation (p-value = 2.5 × 10^-28) to lung function. We also found a network of 13 proteins and 10 metabolites that had a -0.27 correlation (p-value = 2.6 × 10^-17) to percent emphysema. Protein-metabolite networks can provide additional information on the progression of COPD that complements single biomarker or single -omic analyses.

An Active and Soft Hydrogel Actuator to Stimulate Live Cell Clusters by Self-folding

The hydrogels are widely used in various applications, and their successful uses depend on controlling the mechanical properties. In this study, we present an advanced strategy to develop hydrogel actuator designed to stimulate live cell clusters by self-folding. The hydrogel actuator consisting of two layers with different expansion ratios were fabricated to have various curvatures in self-folding. The expansion ratio of the hydrogel tuned with the molecular weight and concentration of gel-forming polymers, and temperature-sensitive molecules in a controlled manner. As a result, the hydrogel actuator could stimulate live cell clusters by compression and tension repeatedly, in response to temperature. The cell clusters were compressed in the 0.7-fold decreases of the radius of curvature with 1.0 mm in room temperature, as compared to that of 1.4 mm in 37 °C. Interestingly, the vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein-2 (IGFBP-2) in MCF-7 tumor cells exposed by mechanical stimulation was expressed more than in those without stimulation. Overall, this new strategy to prepare the active and soft hydrogel actuator would be actively used in tissue engineering, drug delivery, and micro-scale actuators.

Nuclear localization and actions of the insulin-like growth factor 1 (IGF-1) system components: Transcriptional regulation and DNA damage response

Insulin-like growth factor (IGF) system stimulates growth, proliferation, and regulates differentiation of cells in a tissue-specific manner. It is composed of two insulin-like growth factors (IGF-1 and IGF-2), six insulin-like growth factor-binding proteins (IGFBPs), and two insulin-like growth factor receptors (IGF-1R and IGF-2R). IGF actions take place mostly through the activation of the plasma membrane-bound IGF-Rs by the circulating ligands (IGFs) released from the IGFBPs that stabilize their levels in the serum. This review focuses on the IGF-1 part of the system. The IGF-1 gene, which is expressed mainly in the liver as well as in other tissues, comprises six alternatively spliced exons that code for three protein isoforms (pro-IGF-1A, pro-IGF-1B, and pro-IGF-1C), which are processed to mature IGF-1 and E-peptides. The IGF-1R undergoes autophosphorylation, resulting in a signaling cascade involving numerous cytoplasmic proteins such as AKT and MAPKs, which regulate the expression of target genes. However, a more complex picture of the axis has recently emerged with all its components being translocated to the nuclear compartment. IGF-1R takes part in the regulation of gene expression by forming transcription complexes, modifying the activity of chromatin remodeling proteins, and participating in DNA damage tolerance mechanisms. Four IGFBPs contain a nuclear localization signal (NLS), which targets them to the nucleus, where they regulate gene expression (IGFBP-2, IGFBP-3, IGFBP-5, IGFBP-6) and DNA damage repair (IGFBP-3 and IGFBP-6). Last but not least, the IGF-1B isoform has been reported to be localized in the nuclear compartment. However, no specific molecular actions have been assigned to the nuclear pro-IGF-1B or its derivative EB peptide. Therefore, further studies are needed to shed light on their nuclear activity. These recently uncovered nuclear actions of different components of the IGF-1 axis are relevant in cancer cell biology and are discussed in this review.

Polyploid Adipose Stem Cells Shift the Balance of IGF1/IGFBP2 to Promote the Growth of Breast Cancer

Background: The close proximity of adipose tissue and mammary epithelium predispose involvement of adipose cells in breast cancer development. Adipose-tissue stem cells (ASCs) contribute to tumor stroma and promote growth of cancer cells. In our previous study, we have shown that murine ASCs, which undergo polyploidization during their prolonged in vitro culturing, enhanced the proliferation of 4T1 murine breast cancer cells in IGF1 dependent manner.

Aims: In the present study, our aim was to clarify the regulation of ASC-derived IGF1.

Methods: 4T1 murine breast carcinoma cells were co-transplanted with visceral fat-derived ASCs (vASC) or with the polyploid ASC.B6 cell line into female BALB/c mice and tumor growth and lung metastasis were monitored. The conditioned media of vASCs and ASC.B6 cells were subjected to LC-MS/MS analysis and the production of IGFBP2 was verified by Western blotting. The regulatory effect was examined by adding recombinant IGFBP2 to the co-culture of ASC.B6 and 4T1. Akt/protein kinase B (PKB) activation was detected by Western blotting.

Results: Polyploid ASCs promoted the tumor growth and metastasis more potently than vASCs with normal karyotype. vASCs produced the IGF1 regulator IGFBP2, which inhibited proliferation of 4T1 cells. Downregulation of IGFBP2 by polyploidization of ASCs and enhanced secretion of IGF1 allowed survival signaling in 4T1 cells, leading to Akt phosphorylation.

Conclusions: Our results implicate that ASCs in the tumor microenvironment actively regulate the growth of breast cancer cells through the IGF/IGFBP system.

IGFBP-2 in cervical cancer development

OBJECTIVE

Increased expression of insulin-like growth factor binding protein 2, IGFBP-2, is associated with many cancers, though its role in cervical cancer is unclear. The aim of this study was to investigate the expression of IGFBP-2 protein and the transcriptomics profile of genes involved in the IGF signaling pathway during cervical cancer development.

DESIGN

Immunohistochemical expression of IGFBP-2 protein was semi-quantitatively assessed in tissue microarrays containing 9 normal cervix, 10 low grade cervical intraepithelial neoplasia (LGCIN), 10 high grade cervical intraepithelial neoplasia (HGCIN) and 42 squamous cell carcinoma (SCC) cases. The gene expression profiles of IGFBP-2, IGF-1, IGF-1R, PTEN, MDM2, AKT1 and TP53 were determined in three cervical tissue samples each from normal cervix, human papillomavirus (HPV)-infected LGCIN, HGCIN and SCC, using Human Transcriptome Array 2.0.

RESULTS

IGFBP-2 protein was highly expressed in the cytoplasm of SCC cells compared to normal cervix (p = .013). The expression was not significantly associated with CIN grade or SCC stage. Transcriptomics profiling demonstrated upregulation of IGFBP-2 and TP53 in HGCIN and SCC compared to normal cervix. IGF-1, IGF-1R and PTEN genes were downregulated in all histological groups. IGF-1 gene was significantly downregulated in SCC (p = .031), while PTEN gene was significantly downregulated in HGCIN (p = .012), compared to normal cervix. MDM2 and AKT1 genes were downregulated in LGCIN and HGCIN, while upregulated in SCC.

CONCLUSION

In cervical carcinogenesis, IGFBP-2 appears to play an oncogenic role, probably through an IGF-independent mechanism.

Fibroblast deficiency of insulin-like growth factor 1 receptor type 1 (IGF1R) impairs initial steps of murine pheochromocytoma development

Insulin-like growth factor 1 (IGF1) has a critical role in maintaining tumor phenotype and survival of already transformed murine pheochromocytoma (pheo) cells (MPC4/30) and it is required for the initial establishment of these tumors. However, the role of local IGF1/IGF1R system in tumor microenvironment has not been fully understood. In vivo, by subcutaneous injection of pheo cells in heterozygous IGF1R knockout mice (L/n), we found that the time of noticeable tumor appearance was delayed, and incidence was decreased in L/n group compared to control (L/L) mice. Once established, tumor proliferation, vascularization or growth rate did not differ between groups. In vitro, fibroblast from L/n and L/L mice were cultured to generate conditioned media (CM) and differential matrixes on which pheo cells were seeded. Proliferation rate was higher when pheo cells were cultured with CM, or in differential matrix generated by L/L murine fibroblasts. A diminished fibronectin (FN) expression and secretion from L/n fibroblast was associated with decreased expression of integrin subunits in tumor cells. Also, soluble factors as IGF1 and insulin-like growth factor binding protein 2 (IGFBP2) were reduced. Our data suggest that IGF1 signaling through IGF1R may contribute to tumor cells anchorage and survival by interaction with both matrix and soluble factors produced by tumor microenvironment fibroblasts.

IGFBP-2 and aging: a 20-year longitudinal study on IGFBP-2, IGF-I, BMI, insulin sensitivity and mortality in an aging population

Objective Insulin-like growth factor-binding protein-2 (IGFBP-2) concentrations are low in subjects with metabolic syndrome and type 2 diabetes. Intriguingly, recent studies have demonstrated an association between high IGFBP-2 concentrations and increased mortality not only in populations with certain types of cancer, but also in relatively healthy populations. We evaluated the role of IGFBP-2 in relation to BMI and mortality. Design and Participants BMI, insulin sensitivity, insulin-like growth factor 1 (IGF-I) and IGFBP-2 were assessed repeatedly in 539 participants of the Baltimore Longitudinal Study of Aging around the ages of 55, 65 and 75 years. Results IGFBP-2 concentrations positively correlated with insulin sensitivity and inversely with BMI, both at baseline and follow-up. Independent of IGF-I, sex, BMI and insulin sensitivity, circulating IGFBP-2 levels positively correlated with age (P < 0.001). Changes over time in BMI were associated with an inverse correlation in IGFBP-2 concentrations. Furthermore, we found indications of a relationship between low baseline IGFBP-2 levels and mortality. Remarkably, after adjustment for insulin sensitivity, the opposite association was found, as a unit increase of log(IGFBP2) was associated with an increase in the log hazard by 1.43 (95% CI: 0.3-2.6). This accounted for both baseline (P = 0.02) as well as serial (P < 0.001) measurements of IGFBP2. Finally, in this longitudinal study, we found that IGF-I concentrations increased with age (0.82 ± 0.2 (µg/L)/year, P < 0.001). Conclusion This is the first study investigating the relationship between IGFBP-2 levels and age in a longitudinal setting. Serum IGFBP-2 levels increase with age after the age of 50 years and evolve in parallel with insulin sensitivity. IGFBP-2 may therefore be a potential marker for insulin sensitivity. We further show that IGFBP-2 levels can predict mortality in this aging population. However, its predictive value for mortality can only be interpreted in relation to insulin sensitivity. After adjustment for insulin sensitivity, high IGFBP-2 levels are predictive of increased mortality.

Extracellular Matrix Imaging of Breast Tissue Pathologies by MALDI-Imaging Mass Spectrometry

PURPOSE

A new method accessing proteins from extracellular matrix by imaging mass spectrometry (ECM IMS) has been recently reported. ECM IMS is evaluated for use in exploring breast tissue pathologies.

EXPERIMENTAL DESIGN

A tissue microarray (TMA) is analyzed that has 176 cores of biopsies and lumpectomies spanning breast pathologies of inflammation, hyperplasia, fibroadenoma, invasive ductal carcinoma, and invasive lobular carcinoma and normal adjacent to tumor (NAT). NAT is compared to subtypes by area under the receiver operating curve (ROC) >0.7. A lumpectomy is also characterized for collagen organization by microscopy and stromal protein distribution by IMS. LC-based high-resolution accurate mass (HRAM) proteomics is used to identify proteins from the lumpectomy.

RESULTS

TMA analysis shows distinct spectral signatures reflecting a heterogeneous tissue microenvironment. Ninety-four peaks show an ROC > 0.7 compared to NAT; NAT has overall higher intensities. Lumpectomy analysis by IMS visualizes a complex central tumor region with distal tumor regions. A total of 39 stromal proteins are identified by HRAM LC-based proteomics. Accurate mass matches between image data and LC-based proteomics demonstrate a heterogeneous collagen type environment in the central tumor.

CONCLUSIONS

Data portray the heterogeneous stromal microenvironment of breast pathologies, including alteration of multiple collagen-type patterns. ECM IMS is a promising new tool for investigating the stromal microenvironment of breast tissue including cancer.

Protein array profiling of circulating angiogenesis-related factors during bevacizumab containing treatment in metastatic colorectal cancer

BACKGROUND

Prolonged angiogenesis inhibition may improve treatment outcome in metastatic colorectal cancer (mCRC) patients. However, due to the complexity of the angiogenic pathways there is a lack of valid predictive biomarkers for anti-angiogenic agents. Here, we describe and optimize a procedure for simultaneous dynamic profiling of multiple angiogenesis related proteins in patient serum to explore associations with the response and acquired resistance to anti-angiogenic therapy.

MATERIALS AND METHODS

Patients (n=22) were selected from a clinical trial investigating maintenance treatment with bevacizumab alone after response to induction chemotherapy + bevacizumab in mCRC. Serum samples were analysed for 55 unique angiogenesis related proteins using a commercial proteome profiler array and a publicly available image analysis program for quantification. Samples were collected at baseline before induction treatment start, at start of maintenance treatment, and at end of treatment after tumour progression.

MAIN RESULTS AND CONCLUSION

For eight proteins, the antibody array signals were below detection range in all patient samples. None of the proteins showed levels at baseline or at start of maintenance with strong evidence for correlation to time to progression (lowest nominal p-value 0.03). The dynamic ranges of protein levels measured during the induction treatment period and during the maintenance period were analysed separately for time trends. Evidence for changing trends (up/down) in the levels of MMP-8, TIMP-4 and EGF was observed both during response to induction treatment and at progressive disease, respectively. For three of the proteins (IL-8, Activin A and IGFBP-2), weak evidence for correlation between increasing protein levels during induction with chemotherapy and bevacizumab and time to progression was observed. In conclusion, semi-quantitative profiling of angiogenesis related proteins in patient serum may be a versatile tool to screen for protein patterns aiming at identifying resistance mechanisms of anti-angiogenic treatment in patients with mCRC.

WITHDRAWN: Modulation on gallbladder carcinoma by TGF-β1 via IGFBP-2

Ahead of Print article withdrawn by publisher. Gallbladder carcinoma (GC) occupies more than 90% of all cancers in biliary tract with an increasing incidence. Most patients with GC are already at terminal stage at the time of primary diagnosis, causing unfavorable prognosis and high mortality. Transformation growth factor-beta (TGF-β) is up-regulated in GC. However, the mechanism by how TGF-β is involved in GC remains unclear. The aim of this study was to investigate the effect and mechanism of TGF-β in GC using GC cell line NOZ cells.In vitro cultured NOZ cell was randomly assigned into control, si-NC and TGF-β1 siRNA groups and were transfected with siRNA negative control (NC) or TGF-β1 siRNA followed by analysis of TGF-β1 expression by Real-time PCR, cell proliferation by MTT assay, cell apoptosis and cell invasion, as well as expression of proteins in epithelial-mesenchymal transition (EMT), p38, Smad2/3 and Smad4 phosphorylation by Western blot, Insulin-like growth factor-binding protein-2 (IGFBP-2) level by ELISA. After transfecting TGF-β1 siRNA into NOZ cells, TGF-β1 expression was suppressed and cell proliferation and invasion were inhibited, together with enhanced Caspase-3 activity. Meanwhile, E-cadherin expression was increased, with decreased Vimentin, IGFBP-2, p38, Smad2/3 and Smad4 phosphorylation (P< 0.05 comparing to control group). In conclusion, inhibition of TGF-β1 expression facilitates GC cell apoptosis, inhibits GC cell proliferation, invasion and EMT occurrence.

A peptide containing the receptor binding site of insulin-like growth factor binding protein-2 enhances bone mass in ovariectomized rats

Male Igfbp2−/− mice have a significant reduction in bone mass and administration of a peptide that contains the insulin-like growth factor binding protein-2(IGFBP-2) receptor-binding domain stimulates bone formation in these animals. Female Igfbp2−/− mice do not have this phenotype but following ovariectomy (OVX) lose more bone than OVX wild-type mice. This suggests that in the absence of estrogen, IGFBP-2 is required to maintain bone mass. Therefore these studies were undertaken to determine if this peptide could stimulate bone acquisition in OVX rats. OVX rats were divided into seven treatment groups: sham animals, OVX animals, OVX animals receiving a control scrambled peptide, or one of three doses of the active peptide termed PEG-HBD-1 (0.7, 2, and 6 mg·kg^-1) and an OVX group receiving parathyroid hormone (PTH) (50 µg·kg^-1 per day). The peptides were administered for 8 weeks. DXA revealed a significant reduction in femoral and tibial areal bone mineral density (aBMD) after OVX, whereas treatment with the high-dose peptide increased aBMD by 6.2% ± 2.4% (P < 0.01) compared to control peptide; similar to the increase noted with PTH (5.6% ± 3.0%, P < 0.01). Similar increases were noted with two lower doses of the peptide (3.8% ± 1.5%, P < 0.05 for low dose; 3.1% ± 1.6%, P = 0.07 for middle dose). Micro CT showed that the OVX control peptide animals had reductions of 41% and 64% in femoral trabecular BV/TV and trabecular number, respectively. All three doses of the peptide increased bone volume/total volume (BV/TV) significantly, while the low and middle doses increased trabecular number. Cortical BV/TV and thickness at the midshaft increased significantly with each dose of peptide (18.9% ± 9.8%, P < 0.01 and 14.2% ± 7.9%, P < 0.01 for low dose; 23.7% ± 10.7%, P < 0.001 and 15.8% ± 6.1%, P < 0.001 for middle dose; 19.0% ± 6.9%, P < 0.01 and 16.2% ± 9.7%, P < 0.001 for high dose) and with PTH (25.8% ± 9.2%, P < 0.001 and 19.4% ± 8.8%, P < 0.001). Histomorphometry showed that the lowest dose of peptide stimulated BV/TV, trabecular thickness, mineral apposition rate (MAR), bone formation rate/bone surface (BFR/BS), number of osteoblasts/bone perimeter (N.ob/B.pm), and decreased osteoclast surface/bone perimeter (Oc.S/B.Pm). The highest dose stimulated each of these parameters except MAR and BFR/BS. Thus, the heparin-binding domain receptor region of IGFBP-2 accounts for its anabolic activity in bone. Importantly, this peptide enhances bone mass in estrogen-deficient animals.

An experimental peptide stimulates bone acquisition in female rats who have had their ovaries removed, raising the prospect a new drug for osteoporosis.

IGFBP-2 is an insulin-like growth factor (IGF) binding protein, which regulates the amount of IGF-I and II that are transported out of the blood and are available to influence the growth and proliferation of bone-producing osteoblasts. Previous studies have suggested that IGFBP-2 is required to maintain bone mass in the absence of estrogen, and that a 13 amino acid peptide (HBD1) from the core of the protein could provide a substitute for it.

In this study, David Clemmons at the University of North Carolina at Chapel Hill and his colleagues demonstrate that injecting the peptide into ovariectomized female rats prompts significant increases in bone mass, whereas control animals lost bone.