Synthesis and characterization of insulin-like growth factor-binding protein (IGFBP)-7. Recombinant human mac25 protein specifically binds IGF-I and -II

Exosomal Serum Biomarkers as Predictors for Laryngeal Carcinoma

BACKGROUND

The lack of screening methods for LSCC is a critical issue, as treatment options and the treatment outcome greatly depend on the stage of LSCC at initial diagnosis. Therefore, the objective of this study was to identify potential exosomal serum biomarkers that can diagnose LSCC and distinguish between early- and late-stage disease.

METHODS

A multiplexed proteomic array was used to identify differentially expressed proteins in exosomes isolated from the serum samples of LSCC patients compared to the control group (septorhinoplasty, SRP). The most promising proteins for diagnosis and differentiation were calculated using biostatistical methods and were validated by immunohistochemistry (IHC), Western blots (WB), and ELISA.

RESULTS

Exosomal insulin-like growth factor binding protein 7 (IGFBP7) and Annexin A1 (ANXA1) were the most promising exosomal biomarkers for distinguishing between control and LSCC patients and also between different stages of LSCC (fold change up to 15.9, p < 0.001 for all).

CONCLUSION

The identified proteins represent potentially novel non-invasive biomarkers. However, these results need to be validated in larger cohorts with a long-term follow-up. Exosomal biomarkers show a superior signal-to-noise ratio compared to whole serum and may therefore be an important tool for non-invasive biomarker profiling for laryngeal carcinoma in the future.

Structural insight into CD93 recognition by IGFBP7

The CD93/IGFBP7 axis proteins are key factors expressed in endothelial cells (EC) that mediate EC angiogenesis and migration. Their upregulation contributes to tumor vascular abnormality and a blockade of this interaction promotes a favorable tumor microenvironment for therapeutic interventions. However, the interactions of these proteins with each other remain unclear. In this study, we determined a partial structure of the human CD93-IGFBP7 complex comprising the EGF1 domain of CD93 and the IB domain of IGFBP7. Mutagenesis studies confirmed interactions and specificities. Cellular and mouse tumor studies demonstrated the physiological relevance of the CD93-IGFBP7 interaction in EC angiogenesis. Our study provides leads for the development of therapeutic agents to precisely disrupt unwanted CD93-IGFBP7 signaling in the tumor microenvironment. Additionally, analysis of the CD93 full-length architecture provides insights into how CD93 protrudes on the cell surface and forms a flexible platform for binding to IGFBP7 and other ligands.

The Role of Insulin-like Growth Factor (IGF) System in the Corneal Epithelium Homeostasis-From Limbal Epithelial Stem Cells to Therapeutic Applications

The corneal epithelium, comprising three layers of cells, represents the outermost portion of the eye and functions as a vital protective barrier while concurrently serving as a critical refractive structure. Maintaining its homeostasis involves a complex regenerative process facilitated by the functions of the lacrimal gland, tear film, and corneal nerves. Crucially, limbal epithelial stem cells located in the limbus (transitional zone between the cornea and the conjunctiva) are instrumental for the corneal epithelium integrity by replenishing and renewing cells. Re-epithelialization failure results in persistent defects, often associated with various ocular conditions including diabetic keratopathy. The insulin-like growth factor (IGF) system is a sophisticated network of insulin and other proteins essential for numerous physiological processes. This review examines its role in maintaining the corneal epithelium homeostasis, with a special focus on the interplay with corneal limbal stem cells and the potential therapeutic applications of the system components.

Human archetypal pluripotent stem cells differentiate into trophoblast stem cells via endogenous BMP5/7 induction without transitioning through naive state

Primary human trophoblast stem cells (TSCs) and TSCs derived from human pluripotent stem cells (hPSCs) can potentially model placental processes in vitro. Yet, the pluripotent states and factors involved in the differentiation of hPSCs to TSCs remain poorly understood. In this study, we demonstrate that the primed pluripotent state can generate TSCs by activating pathways such as Epidermal Growth Factor (EGF) and Wingless-related integration site (WNT), and by suppressing tumor growth factor beta (TGFβ), histone deacetylases (HDAC), and Rho-associated protein kinase (ROCK) signaling pathways, all without the addition of exogenous Bone morphogenetic protein 4 (BMP4)-a condition we refer to as the TS condition. We characterized this process using temporal single-cell RNA sequencing to compare TS conditions with differentiation protocols involving BMP4 activation alone or BMP4 activation in conjunction with WNT inhibition. The TS condition consistently produced a stable, proliferative cell type that closely mimics first-trimester placental cytotrophoblasts, marked by the activation of endogenous retroviral genes and the absence of amnion expression. This was observed across multiple cell lines, including various primed induced pluripotent stem cell (iPSC) and embryonic stem cell (ESC) lines. Primed-derived TSCs can proliferate for over 30 passages and further specify into multinucleated syncytiotrophoblasts and extravillous trophoblast cells. Our research establishes that the differentiation of primed hPSCs to TSC under TS conditions triggers the induction of TMSB4X, BMP5/7, GATA3, and TFAP2A without progressing through a naive state. These findings propose that the primed hPSC state is part of a continuum of potency with the capacity to differentiate into TSCs through multiple routes.

Elevated Norepinephrine Stimulates Adipocyte Hyperplasia in Ovine Fetuses With Placental Insufficiency and IUGR

Prevailing hypoxemia and hypoglycemia in near-term fetuses with placental insufficiency-induced intrauterine growth restriction (IUGR) chronically increases norepinephrine concentrations, which lower adrenergic sensitivity and lipid mobilization postnatally, indicating a predisposition for adiposity. To determine adrenergic-induced responses, we examined the perirenal adipose tissue transcriptome from IUGR fetuses with or without hypercatecholaminemia. IUGR was induced in sheep with maternal hyperthermia, and hypercatecholaminemia in IUGR was prevented with bilateral adrenal demedullation. Adipose tissue was collected from sham-operated control (CON) and IUGR fetuses and adrenal-demedullated control (CAD) and IUGR (IAD) fetuses. Norepinephrine concentrations were lower in IAD fetuses than in IUGR fetuses despite both being hypoxemic and hypoglycemic. In IUGR fetuses, perirenal adipose tissue mass relative to body mass was greater compared with the CON, adrenal-demedullated control, and IAD groups. Transcriptomic analysis identified 581 differentially expressed genes (DEGs) in CON vs IUGR adipose tissue and 193 DEGs in IUGR vs IAD adipose tissue. Integrated functional analysis of these 2 comparisons showed enrichment for proliferator-activated receptor signaling and metabolic pathways and identified adrenergic responsive genes. Within the adrenergic-regulated DEGs, we identified transcripts that regulate adipocyte proliferation and differentiation: adipogenesis regulatory factor, C/CCAAT/enhancer binding protein α, and sterol carrier protein 2. DEGs associated with the metabolic pathway included pyruvate dehydrogenase kinase 4, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4, IGF-binding proteins (IGFBP-5 and IGFBP-7). Sex-specific expression differences were also found for adipogenesis regulatory factor, pyruvate dehydrogenase kinase 4, IGFBP5, and IGFBP7. These findings indicate that sustained adrenergic stimulation during IUGR leads to adipocyte hyperplasia with alterations in metabolism, proliferation, and preadipocyte differentiation pathways.

Sustained Nrf2 Overexpression-Induced Metabolic Deregulation Can Be Attenuated by Modulating Insulin/Insulin-like Growth Factor Signaling

The modulation of insulin/insulin-like growth factor signaling (IIS) is associated with altered nutritional and metabolic states. The Drosophila genome encodes eight insulin-like peptides, whose activity is regulated by a group of secreted factors, including Ecdysone-inducible gene L2 (ImpL2), which acts as a potent IIS inhibitor. We recently reported that cncC (cncC/Nrf2), the fly ortholog of Nrf2, is a positive transcriptional regulator of ImpL2, as part of a negative feedback loop aiming to suppress cncC/Nrf2 activity. This finding correlated with our observation that sustained cncC/Nrf2 overexpression/activation (cncCOE; a condition that signals organismal stress) deregulates IIS, causing hyperglycemia, the exhaustion of energy stores in flies' tissues, and accelerated aging. Here, we extend these studies in Drosophila by assaying the functional implication of ImpL2 in cncCOE-mediated metabolic deregulation. We found that ImpL2 knockdown (KD) in cncCOE flies partially reactivated IIS, attenuated hyperglycemia and restored tissue energetics. Moreover, ImpL2 KD largely suppressed cncCOE-mediated premature aging. In support, pharmacological treatment of cncCOE flies with Metformin, a first-line medication for type 2 diabetes, restored (dose-dependently) IIS functionality and extended cncCOE flies' longevity. These findings exemplify the effect of chronic stress in predisposition to diabetic phenotypes, indicating the potential prophylactic role of maintaining normal IIS functionality.

Depletion of Igfbp7 alleviates zebrafish NAFLD progression through inhibiting hepatic ferroptosis

AIMS

The global increased expression of Insulin-like growth factor binding protein 7 (IGFBP7) has been detected in non-alcoholic fatty liver disease (NAFLD) patients, however, its roles in NAFLD and the mechanism remain largely unclear. The goal of this study is to investigate the effect and mechanism of Igfbp7 using a zebrafish NAFLD model.

MAIN METHODS

The igfbp7-/- null zebrafish mutant and the Igfbp7 liver overexpressed (LOE) transgenic zebrafish based on Gal4/UAS system were generated by CRISPR/Cas9 and Tol2 transgenic technique, respectively. The zebrafish NAFLD models in wildtypes, igfbp7-/- mutants and Igfbp7 LOE fishes have been established by high-fat diet feeding. The Igfbp7 dynamic expression and its effects on NAFLD progression have been detected and analyzed in both human NAFLD patients and zebrafish models. And the potential mechanism has been investigated through transcriptome analysis and subsequent detection and verification.

KEY FINDINGS

High Igfbp7 levels in NASH and fibrosis stages have been detected in liver tissues of both human NAFLD patients and zebrafish models. Depletion of Igfbp7 significantly alleviated liver steatosis, inflammation, and fibrosis, whereas liver specific Igfbp7 overexpression dramatically exacerbated liver fibrosis in zebrafish NAFLD model. The hepatic iron deposition, lipid peroxidation products, and ferroptosis-related index were also significantly reduced at the NASH stage in the absence of Igfbp7. Igfbp7 promotes NAFLD progression through regulating ferroptosis, and Ncoa4-mediated ferritinophagy may be the pathway of Igfbp7-regulated ferroptosis.

SIGNIFICANCE

Igfbp7 is confirmed as an important regulator in NAFLD progression. Depleting Igfbp7 effectively alleviates zebrafish NAFLD progression by inhibiting hepatic ferroptosis, suggesting a novel potential target for NAFLD treatment.

Crosstalk between Cancer Cells and Cancer-Associated Fibroblasts Mediated by TGF-β1-IGFBP7 Signaling Promotes the Progression of Infiltrative Gastric Cancer

Patients with infiltrative-type gastric cancer (GC) (Ming's classification) have a poor prognosis due to more metastasis and recurrence. Cancer-associated fibroblasts (CAFs) in infiltrative-type extracellular matrix (ECM) have specific characteristics compared with those of expansive types with respect to metastasis, but the mechanism is still unclear. Based on our proteomics data, TCGA data analysis, and immunohistochemical staining results, significantly higher expression of IGFBP7 was observed in GC, especially in the infiltrative type, and was associated with a poor prognosis. Combining single-cell transcriptome data from GEO and multiple immunofluorescence staining on tissue showed that the differential expression of IGFBP7 mainly originated from myofibroblastic CAFs, the subgroup with higher expression of PDGFRB and α-SMA. After treating primary normal fibroblasts (NFs) with conditional medium or recombined protein, it was demonstrated that XGC-1-derived TGF-β1 upregulated the expression of IGFBP7 in the cells and its secretion via the P-Smad2/3 pathway and mediated its activation with higher FAP, PDGFRB, and α-SMA expression. Then, either conditional medium from CAFs with IGFBP7 overexpression or recombined IGFBP7 protein promoted the migration, invasion, colony formation, and sphere growth ability of XGC-1 and MGC-803, respectively. Moreover, IGFBP7 induced EMT in XGC-1. Therefore, our study clarified that in the tumor microenvironment, tumor-cell-derived TGF-β1 induces the appearance of the IGFBP7+ CAF subgroup, and its higher IGFBP7 extracellular secretion level accelerates the progression of tumors.

Low-affinity insulin-like growth factor binding protein 7 and its association with pulmonary arterial hypertension severity and survival

Insulin-like growth factor (IGF) binding proteins (IGFBPs) are a family of growth factor modifiers, some of which are known to be independently associated with pulmonary arterial hypertension (PAH) survival. IGF factor binding protein 7 (IGFBP7) is a unique low-affinity IGFBP that, independent of IGF, stimulates prostacyclin production. This study proposed to establish associations between IGFBP7 and PAH severity and survival, using enrollment and longitudinal samples. Serum IGFBP7 levels were significantly elevated in patients with PAH compared to controls. After adjusting for age and sex, logarithmic increases in IGFBP7 were associated with a 20 m shorter six-minute walk distance (6MWD; p < 0.001), a 2-3 mmHg higher mean right atrial pressure (p < 0.001 and 0.02), and a higher likelihood of a greater REVEAL 2.0 risk category placement (p < 0.001). Kaplan-Meier analysis demonstrated significantly decreased survival with IGFBP7 above the median and Cox multivariable analysis adjusted for age and sex, demonstrated higher serum IGFBP7 was an independent predictor of survival. Though the exact mechanism is still unknown, given IGFBP7's role as a prostacyclin stimulant, it has potential use as a therapeutic target for disease modulation.

Structural insight into CD93 recognition by IGFBP7

The CD93/IGFBP7 axis are key factors expressed in endothelial cells (EC) that mediate EC angiogenesis and migration. Upregulation of them contributes to tumor vascular abnormality and blockade of this interaction promotes a favorable tumor microenvironment for therapeutic interventions. However, how these two proteins associated to each other remains unclear. In this study, we solved the human CD93-IGFBP7 complex structure to elucidate the interaction between the EGF 1 domain of CD93 and the IB domain of IGFBP7. Mutagenesis studies confirmed the binding interactions and specificities. Cellular and mouse tumor studies demonstrated the physiological relevance of the CD93-IGFBP7 interaction in EC angiogenesis. Our study provides hints for development of therapeutic agents to precisely disrupt unwanted CD93-IGFBP7 signaling in the tumor microenvironment. Additionally, analysis of the CD93 full-length architecture provides insights into how CD93 protrudes on the cell surface and forms a flexible platform for binding to IGFBP7 and other ligands.

The diagnostic value of serum insulin-like growth factor binding protein 7 in gastric cancer

Backgrounds

Early detection might help in reducing the burden and promoting the survival rate of gastric cancers. Herein, we tried to explore the diagnostic value of insulin-like growth factor binding protein 7 (IGFBP7) in gastric cancers.

Methods

In this study, we first analyzed the expression levels and prognostic value of IGFBP7 mRNA in gastric cancers from The Cancer Genome Atlas (TCGA) database. Then, we recruited 169 gastric cancer patients and 100 normal controls as training cohort, and 55 gastric cancer patients and 55 normal controls as independent validation cohort. Enzyme-linked immunosorbent assay was applied to test the serum levels of IGFBP7. The receiver operating characteristic curve (ROC) and the area under the curve (AUC) were applied to evaluation the diagnostic value.

Results

TCGA showed that IGFBP7 mRNA was dysregulated and associated with prognosis in gastric cancer patients. Then, we examined the expression of serum IGFBP7 and found that serum IGFBP7 expressed lower in gastric cancer patients than normal controls both in training and independent validation cohorts (p < 0.0001). In training cohort, with the cutoff value of 1.515 ng/ml, the AUC for distinguishing gastric cancer patients was 0.774 (95% CI [0.713-0.836]) with sensitivity of 36.7% (95% CI [29.5-44.5]) and specificity of 90.0% (95% CI [82.0-94.8]). As for early-stage EJA, the AUC was 0.773 (95% CI [0.701-0.845]) with the sensitivity of 33.3% (95% CI [14.4-58.8]). In independent validation cohort, with the same cutoff value, the AUC reached to 0.758 (95% CI [0.664-0.852]). Similarly, for early-stage gastric cancer diagnosis in the independent validation cohort, the AUC value was 0.778 (95% CI [0.673-0.882]).

Conclusions

This study indicated that serum IGFBP7 might act as a potential early diagnostic marker for gastric cancers.

Regional Handling and Prognostic Performance of Circulating Insulin-Like Growth Factor Binding Protein-7 in Heart Failure

BACKGROUND

Regional handling and the prognostic performance of insulin-like growth factor binding protein (IGFBP)-7, in contrast or in combination with other candidate biomarkers, in chronic heart failure (CHF) remain uncertain.

OBJECTIVES

The authors investigated the regional handling of plasma IGFBP-7 and its association with long-term outcomes in CHF in comparison with selected circulating biomarkers.

METHODS

Plasma concentrations of IGFBP-7, N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity troponin-T, growth differentiation factor-15, and high-sensitivity C-reactive protein were measured prospectively in a cohort with CHF (n = 863). The primary outcome was the composite of heart failure (HF) hospitalization or all-cause mortality. In a separate non-HF cohort (n = 66) undergoing cardiac catheterization, transorgan gradients of plasma IGFBP-7 concentrations were evaluated.

RESULTS

Among 863 patients (age 69 ± 14 years, 30% female, 36% HF with preserved ejection fraction), IGFBP-7 (median: 121 [IQR: 99-156] ng/mL) related inversely to left ventricular volumes but directly to diastolic function. Above the optimal cutoff, IGFBP-7 ≥110 ng/mL was independently associated with 32% increased hazard of the primary outcome: 1.32 (95% CI: 1.06-1.64). Among the 5 markers, IGFBP-7 had the highest hazard for a proportional increment in plasma concentrations independent of HF phenotype in single- and double-biomarker models, and provided incremental prognostic value beyond clinical predictors plus NT-proBNP, high-sensitivity troponin-T, and high-sensitivity C-reactive protein (P < 0.05). Assessment of regional concentrations indicated renal secretion of IGFBP-7 in contrast to renal extraction of NT-proBNP, possible cardiac extraction of IGFBP-7 in contrast to secretion of NT-proBNP, and common hepatic extraction of both peptides.

CONCLUSIONS

Transorgan regulation of IGFBP-7 is distinct from NT-proBNP. Circulating IGFBP-7 independently predicts adverse outcomes in CHF with a strong prognostic performance when compared with other well-recognized cardiac-specific or noncardiac prognostic markers.

Novel single nucleotide polymorphisms of insulin-like growth factor-binding protein 7 (IGFBP7) gene significantly associated with growth traits in striped catfish (Pangasianodon hypophthalmus Sauvage, 1878)

Breeding program to improve economically important growth traits in striped catfish (Pangasianodon hypophthalmus) requires effective molecular markers. This study was conducted to identify single nucleotide polymorphisms (SNPs) of Insulin-like Growth Factor-Binding Protein 7 (IGFBP7) gene which plays multiple roles in regulating growth, energy metabolism and development. The association between SNPs in IGFBP7 gene and growth traits in striped catfish was analyzed in order to uncover the SNPs that have potential to be valuable markers for improving growth traits. Firstly, fragments of IGFBP7 gene from ten fast-growing fish and ten slow-growing fish were sequenced in order to discover SNPs. After filtering the detected SNPs, an intronic SNP (2060A > G) and two non-synonymous SNPs (344 T > C and 4559C > A) causing Leu78Pro and Leu189Met in protein, respectively, were subjected to further validated by individual genotyping in 70 fast-growing fish and 70 slow-growing fish using single base extension method. Our results showed that two SNPs (2060A > G and 4559 C > A (p. Leu189Met)) were significantly associated with the growth in P. hypophthalmus (p < 0.001), thus being candidate SNP markers for the growth traits of this fish. Moreover, linkage disequilibrium and association analysis with growth traits of haplotypes generated from the 3 filtered SNPs (344 T > C, 2060 A > G and 4559 C > A) were examined. These revealed that the non-coding SNP locus (2060A > G) had higher genetic diversity at which the G allele was predominant over the A allele in the fast-growing fish. Furthermore, the results of qPCR showed that expression of IGFBP7 gene with genotype GG (at locus 2060) in fast-growing group was significantly higher than that with genotype AA in slow-growing group (p < 0.05). Our study provides insights into the genetic variants of IGFBP7 gene and useful data source for development molecular marker for growth traits in breeding of the striped catfish.

Expression characteristics and their functional role of IGFBP gene family in pan-cancer

BACKGROUND

Insulin-like growth factor binding proteins (IGFBPs) are critical regulators of the biological activities of insulin-like growth factors. The IGFBP family plays diverse roles in different types of cancer, which we still lack comprehensive and pleiotropic understandings so far.

METHODS

Multi-source and multi-dimensional data, extracted from The Cancer Genome Atlas (TCGA), Oncomine, Cancer Cell Line Encyclopedia (CCLE), and the Human Protein Atlas (HPA) was used for bioinformatics analysis by R language. Immunohistochemistry and qRT-PCR were performed to validate the results of the database analysis results. Bibliometrics and literature review were used for summarizing the research progress of IGFBPs in the field of tumor.

RESULTS

The members of IGFBP gene family are differentially expressed in various cancer types. IGFBPs expression can affect prognosis of different cancers. The expression of IGFBPs expression is associated with multiple signal transduction pathways. The expression of IGFBPs is significantly correlated with tumor mutational burden, microsatellite instability, tumor stemness and tumor immune microenvironment. The qRT-PCR experiments verified the lower expression of IGFBP2 and IGFBP6 in gastric cancer and the lower expression of IGFBP6 in colorectal cancer. Immunohistochemistry validated a marked downregulation of IGFBP2 protein in gastric cancer tissues. The keywords co-occurrence analysis of IGFBP related publications in cancer showed relative research have been more concentrating on the potential of IGFBPs as tumor diagnostic and prognostic markers and developing cancer therapies.

CONCLUSIONS

These findings provide frontier trend of IGFBPs related research and new clues for identifying novel therapeutic targets for various cancers.

Insulin‐like growth factor‐2 is a promising candidate for the treatment and prevention of Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia. Current AD treatments slow the rate of cognitive decline, but do not restore lost function. One reason for the low efficacy of current treatments is that they fail to target neurotrophic processes, which are thought to be essential for functional recovery. Bolstering neurotrophic processes may also be a viable strategy for preventative treatment, since structural losses are thought to underlie cognitive decline in AD. The challenge of identifying presymptomatic patients who might benefit from preventative treatment means that any such treatment must meet a high standard of safety and tolerability. The neurotrophic peptide insulin-like growth factor-2 (IGF2) is a promising candidate for both treating and preventing AD-induced cognitive decline. Brain IGF2 expression declines in AD patients. In rodent models of AD, exogenous IGF2 modulates multiple aspects of AD pathology, resulting in (1) improved cognitive function; (2) stimulation of neurogenesis and synaptogenesis; and, (3) neuroprotection against cholinergic dysfunction and beta amyloid-induced neurotoxicity. Preclinical evidence suggests that IGF2 is likely to be safe and tolerable at therapeutic doses. In the preventative treatment context, the intranasal route of administration is likely to be the preferred method for achieving the therapeutic effect without risking adverse side effects. For patients already experiencing AD dementia, routes of administration that deliver IGF2 directly access the CNS may be necessary. Finally, we discuss several strategies for improving the translational validity of animal models used to study the therapeutic potential of IGF2.

Insulin-like growth factor binding protein 5: Diverse roles in cancer

Insulin-like growth factor binding proteins (IGFBPs) and the associated signaling components in the insulin-like growth factor (IGF) pathway regulate cell differentiation, proliferation, apoptosis, and adhesion. Of the IGFBPs, insulin-like growth factor binding protein 5 (IGFBP5) is the most evolutionarily conserved with a dynamic range of IGF-dependent and -independent functions, and studies on the actions of IGFBP5 in cancer have been somewhat paradoxical. In cancer, the IGFBPs respond to external stimuli to modulate disease progression and therapeutic responsiveness in a context specific manner. This review discusses the different roles of IGF signaling and IGFBP5 in disease with an emphasis on discoveries within the last twenty years, which underscore a need to clarify the IGF-independent actions of IGFBP5, the impact of its subcellular localization, the differential activities of each of the subdomains, and the response to elements of the tumor microenvironment (TME). Additionally, recent advances addressing the role of IGFBP5 in resistance to cancer therapeutics will be discussed. A better understanding of the contexts in which IGFBP5 functions will facilitate the discovery of new mechanisms of cancer progression that may lead to novel therapeutic opportunities.

IGFBP7 enhances trophoblast invasion via IGF-1R/c-Jun signaling in unexplained recurrent spontaneous abortion

In brief

Insufficient trophoblast invasion at the maternal-fetal interface contributes to abortion-prone pregnancy. Our study shows that decreased levels of IGFBP7 in unexplained recurrent spontaneous abortion (URSA) trophoblast cells inhibit MMP2 and Slug expression as well as trophoblast invasion, suggesting that IGFBP7 should be considered a potential therapeutic protein target in URSA.

Abstract

Insufficient trophoblast invasion at the maternal-fetal interface contributes to abortion-prone pregnancy. Cyclosporine A (CsA) can exert therapeutic effects on URSA by promoting trophoblast invasion. A previous study showed decreased expression of insulin-like growth factor-binding protein 7 (IGFBP7) in the sera of recurrent spontaneous abortion patients. However, the role of IGFBP7 in URSA remains unknown. The aim of this study was to determine whether IGFBP7 modulates trophoblast invasion in URSA and the underlying molecular mechanisms. We found that IGFBP7 was expressed at lower levels in villous specimens from URSA patients. Manipulating IGFBP7 expression significantly affected the MMP2 and Slug expression in HTR-8/SVneo cells as well as trophoblast invasion in vitro. Inactivation of IGF-1R by IGFBP7 was observed, and IGF-1R inhibition increased the IGFBP7-induced MMP2 and Slug expression in HTR-8/SVneo cells. Moreover, the level of c-Jun was significantly upregulated in the URSA group. Silencing IGFBP7 increased the binding of downstream c-Jun to the MMP2 and Slug promoter regions in HTR-8/SVneo cells, thus suppressing transcription. In addition, increased expression of IGFBP7 in HTR-8/SVneo cells was observed upon CsA treatment. Knockdown of IGFBP7 inhibited the CsA-enhanced MMP2 and Slug expression in HTR-8/SVneo cells. Our results suggest that in normal pregnancy, IGFBP7 induces MMP2 and Slug expression via the IGF-1R-mediated c-Jun signaling pathway, thereby promoting trophoblast invasion. IGFBP7 depletion in URSA inhibits MMP2 and Slug expression as well as trophoblast invasion. Moreover, IGFBP7 participates in CsA-induced trophoblast invasion, suggesting that IGFBP7 is a potential therapeutic target for URSA.

Insulin-like Growth Factor 2 (IGF-2) and Insulin-like Growth Factor Binding Protein 7 (IGFBP-7) Are Upregulated after Atypical Antipsychotics in Spanish Schizophrenia Patients

Insulin-like growth factor 2 (IGF-2) and IGF binding protein 7 (IGFBP-7) have been related to schizophrenia (SZ) due to their implication in neurodevelopment. The purpose of this study was to assess whether the alterations in IGF-2 and IGFBP-7 in SZ patients are intrinsically related to the psychiatric disorder itself or are a secondary phenomenon due to antipsychotic treatment. In order to test this hypothesis, we measured plasma IGF-2 and IGFBP-7 in drug-naïve first episode (FE) and multiple episodes or chronic (ME) SZ Caucasian patients who have been following treatment for years. A total of 55 SZ patients (FE = 15, ME = 40) and 45 healthy controls were recruited. The Positive and Negative Syndrome Scale (PANSS) and the Self-Assessment Anhedonia Scale (SAAS) were employed to check schizophrenic symptomatology and anhedonia, respectively. Plasma IGF-2 and IGFBP-7 levels were measured by Enzyme-Linked Immunosorbent Assay (ELISA). The FE SZ patients had much lower IGF-2, but not IGFBP-7, than controls. Moreover, both IGF-2 and IGFBP-7 significantly increased after atypical antipsychotic treatment (aripiprazole, olanzapine, or risperidone) in these patients. On the other hand, chronic patients showed higher levels of both proteins when compared to controls. Our study suggests that circulatory IGF-2 and IGFBP-7 increase after antipsychotic treatment, regardless of long-term conditions and being lower in drug-naïve FE patients.

Molecular identification and putative role of insulin growth factor binding protein-related protein (IGFBP-rp) in the swimming crab Portunus trituberculatus

The insulin-like growth factor/insulin-like polypeptide (IGF/ILP) signaling is vital for growth, physiological metabolism, development, and reproduction. Insulin-like growth factor-binding protein (IGFBP) is involved in the insulin signaling pathway in both vertebrates and invertebrates and is critical for various physiology functions. Herein, we cloned and characterized the full-length cDNA of IGFBP-rp in the swimming crab, Portunus trituberculatus (PtIGFBP-rp). The deduced amino acid sequence of PtIGFBP-rp was found to contain three key domains (insulin-like binding (IB) domain, the kazale-type serine protease inhibitor (KAZAL) domain, and the immunoglobulin-like C2 (IGc2) domain). Results showed that PtIGFBP-rp shared the same expression pattern as P. trituberculatus insulin androgenic gland hormone (PtIAG) transcripts during the embryonic larval, juvenile crab stage and the androgenic gland (AG) developmental cycle. Moreover, PtIGFBP-rp transcripts were also present in high abundance in hepatopancreas, muscle, and androgenic glands. The regulatory relationship between PtIGFBP-rp and PtIAG was investigated by RNA interference and co-localization assays, which showed a co-localization relationship and feedback regulation between them. Bilateral eye stalk ablation (ESA) increased the expression of PtIGFBP-rp in the AG at 7 d after surgery. These results demonstrate the involvement of PtIGFBP-rp in the signaling regulatory network of IAG in P. trituberculatus.

IGFBP7 and the Tumor Immune Landscape: A Novel Target for Immunotherapy in Bladder Cancer

Insulin-like growth factor binding protein-7 (IGFBP7) was recently reported to be a ligand of CD93, a potential target to normalize vasculature and attenuate immunotherapy. However, its role in the tumor microenvironment (TME) and immunotherapy response of bladder cancer (BLCA) remains unclear. We comprehensively evaluated the correlation between IGFBP7 and multiple immunological characteristics of BLCA across The Cancer Genome Atlas (TCGA) and two external cohorts. Importantly, the response of IGFBP7-grouped BLCA patients to immunotherapy was predicted and validated by five real-word immunotherapy cohorts. Finally, we developed an IGFBP7-based immune risk model validated by five independent cohorts. IGFBP7 modulated the TME across pan-caners. In BLCA, high expression of IGFBP7 was correlated with more aggressive clinical features. IGFBP7 was positively associated with immunomodulators and promoted tumor-infiltrating lymphocyte trafficking into the tumor microenvironment. However, T cells recognition and tumor cell killing were lower in the high-IGFBP7 group. In addition, high expression of IGFBP7 displayed lower enrichment scores for most pro-immunotherapy pathways. Clinical data from IMvigor210 and GSE176307 indicated that IGFBP7 negatively correlated with the BLCA immunotherapy response. The same trend was also observed in a renal cell carcinoma (RCC) cohort and two melanoma cohorts. Notably, urothelial and luminal differentiation were less frequently observed in the high-IGFBP7 group, while neuroendocrine differentiation was more frequently observed. Mechanistically, high IGFBP7 was associated with an enriched hypoxia pathway and higher expression of key genes in ERBB therapy and antiangiogenic therapy. Furthermore, our IGFBP7-based immune risk model was able to predict the prognosis and response to immunotherapy with good accuracy (5-year AUC = 0.734). Overall, IGFBP7 plays a critical role in the immunoregulation and TME of BLCA and may serve as a novel potential target for combination treatment with immunotherapy for BLCA.

Downregulation of IGFBP5 contributes to replicative senescence via ERK2 activation in mouse embryonic fibroblasts

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) are secretory proteins that regulate IGF signaling. In this study, we investigated the role of IGFBP5 in replicative senescence in embryonic mouse fibroblasts (MEFs). During passages according to the 3T3 method, MEFs underwent senescence after the 5th passage (P5) based on cell growth arrest, an increase in the number of cells positive for senescence-associated β-galactosidase (SA-β-GAL) staining, and upregulation of p16 and p19. In P8 MEFs, IGFBP5 mRNA level was markedly reduced compared with that in P2 MEFs. Downregulation of IGFBP5 via siRNA in P2 MEFs increased the number of SA-β-GAL-positive cells, upregulated p16 and p19, and inhibited cell growth. Incubation of MEFs with IGFBP5 during serial passage increased the cumulative population doubling and decreased SA-β-GAL positivity compared with those in vehicle-treated cells. IGFBP5 knockdown in P2 MEFs increased phosphorylation levels of ERK1 and ERK2. Silencing of ERK2, but not that of ERK1, blocked the increase in the number of SA-β-GAL-positive cells in IGFBP5-knockdown cells. The reduction in the cell number and upregulation of p16 and p21 in IGFBP5-knockdown cells were attenuated by ERK2 knockdown. Our results suggest that downregulation of IGFBP5 during serial passage contributes to replicative senescence via ERK2 in MEFs.

The Rise of IGFBP4 in People with Obstructive Sleep Apnea and Multilevel Sleep Surgery Recovers Its Basal Levels

IGFBP4 is the smallest member of the insulin-like growth factor binding protein family (IGFBP). It is a hepatic protein that plays a role in modulating the activity and bioavailability of IGF-I. The expression of IGFBP4 was found to increase under conditions of hypoxia. Obstructive sleep apnea (OSA) is a common disorder, characterized by cyclic episodes of intermittent hypoxia and fragmented sleep. Our aim was to quantify levels of circulating IGFBP1, IGFBP2, IGFBP3, IGFBP4, and IGFBP7 in fasting plasma samples of 69 Kuwaiti participants and explore its correlation with indices of OSA. The quantification was performed using multiplexing assay. The study involved 28 controls and 41 patients with OSA. Levels of circulating IGFBP4 were significantly higher in people with OSA (289.74 ± 23.30 ng/ml) compared to the control group (217.60 ± 21.74 ng/ml, p = 0.028). The increase in IGFBP4 correlated significantly and positively with AHI (r = .574, p = .01) and AI (r = .794, p = .001) in people with moderate and severe OSA. There was a significant decline in circulating IGFBP4 after 3 months of surgery (225.89 ± 18.16 ng/ml, p = 0.012). This was accompanied by a prominent improvement in OSA (AHI 8.97 ± 2.37 events/h, p = 0.001). In this study, our data showed a significant increase in circulating IGFBP4 in people with OSA. We also report a significant positive correlation between IGFBP4 and indices of OSA at baseline, which suggests IGFBP4 as a potential diagnostic biomarker for OSA. There was a significant improvement in OSA after 3 months of surgical intervention, which concurred with a significant decline in IGFBP4 levels. Altogether, the detected change suggests a potential link between IGFBP4 and OSA or an OSA-related factor, whereby OSA might play a role in triggering the induction of IGFBP4 expression.

A porcine brain-wide RNA editing landscape

Adenosine-to-inosine (A-to-I) RNA editing, catalyzed by ADAR enzymes, is an essential post-transcriptional modification. Although hundreds of thousands of RNA editing sites have been reported in mammals, brain-wide analysis of the RNA editing in the mammalian brain remains rare. Here, a genome-wide RNA-editing investigation is performed in 119 samples, representing 30 anatomically defined subregions in the pig brain. We identify a total of 682,037 A-to-I RNA editing sites of which 97% are not identified before. Within the pig brain, cerebellum and olfactory bulb are regions with most edited transcripts. The editing level of sites residing in protein-coding regions are similar across brain regions, whereas region-distinct editing is observed in repetitive sequences. Highly edited conserved recoding events in pig and human brain are found in neurotransmitter receptors, demonstrating the evolutionary importance of RNA editing in neurotransmission functions. Although potential data biases caused by age, sex or health status are not considered, this study provides a rich resource to better understand the evolutionary importance of post-transcriptional RNA editing.

Huang et al performed a genome-wide RNA editing investigation in the porcine brain in which they found over 680,000 A-to-I RNA editing sites. They identified conserved recoding events between pig and human brains thus providing an extensive resource to aid our understanding of the evolutionary importance of post-transcriptional RNA editing.

Signs of carcinogenicity induced by parathion, malathion, and estrogen in human breast epithelial cells (Review)

Cancer development is a multistep process that may be induced by a variety of compounds. Environmental substances, such as pesticides, have been associated with different human diseases. Organophosphorus pesticides (OPs) are among the most commonly used insecticides. Despite the fact that organophosphorus has been associated with an increased risk of cancer, particularly hormone-mediated cancer, few prospective studies have examined the use of individual insecticides. Reported results have demonstrated that OPs and estrogen induce a cascade of events indicative of the transformation of human breast epithelial cells. In vitro studies analyzing an immortalized non-tumorigenic human breast epithelial cell line may provide us with an approach to analyzing cell transformation under the effects of OPs in the presence of estrogen. The results suggested hormone-mediated effects of these insecticides on the risk of cancer among women. It can be concluded that, through experimental models, the initiation of cancer can be studied by analyzing the steps that transform normal breast cells to malignant ones through certain substances, such as pesticides and estrogen. Such substances cause genomic instability, and therefore tumor formation in the animal, and signs of carcinogenesis in vitro. Cancer initiation has been associated with an increase in genomic instability, indicated by the inactivation of tumor-suppressor genes and activation of oncogenes in the presence of malathion, parathion, and estrogen. In the present study, a comprehensive summary of the impact of OPs in human and rat breast cancer, specifically their effects on the cell cycle, signaling pathways linked to epidermal growth factor, drug metabolism, and genomic instability in an MCF-10F estrogen receptor-negative breast cell line is provided.

Increased IGFBP7 Expression Correlates with Poor Prognosis and Immune Infiltration in Gastric Cancer

Background: Insulin-like growth factor binding protein-7 (IGFBP7) contributes to multiple biological processes in various tumors. However, the role of IGFBP7 in gastric cancer (GC) is still undetermined. The study aims to explore the role of IGFBP7 in GC via an integrated bioinformatics analysis.

Methods: IGFBP7 expression levels in GC and its normal gastric tissues were analyzed using multiple databases, including the Tumor Immune Estimation Resource (TIMER), Oncomine, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, as well as by our clinical gastric specimens. The methylation analysis was conducted with MEXPRESS, UALCAN and Xena online tools. The survival analysis was conducted using the Kaplan-Meier Plotter and Gene Expression Profiling Interactive Analysis (GEPIA) databases. Coexpressed genes of IGFBP7 were selected with the cBioPortal tool and enrichment analysis was conducted with the clusterProfiler package in R software. Gene set enrichment analysis (GSEA) was performed to explore the IGFBP7-related biological processes involved in GC. Correlations between IGFBP7 and immune cell infiltrates were analyzed using the TIMER database.

Results: IGFBP7 expression was significantly upregulated in GC and correlated with stage, grade, tumor status and Helicobacter pylori infection. High IGFBP7 expression and low IGFBP7 methylation levels were significantly associated with short survival of patients with GC. Univariate and multivariate analyses revealed that IGFBP7 was an independent risk factor for GC. The coexpressed genes LHFPL6, SEPTIN4, HSPB2, LAYN and GGT5 predicted unfavorable outcomes of GC. Enrichment analysis showed that the coexpressed genes were involved in extracellular matrix (ECM)-related processes. GSEA indicated that IGFBP7 was positively related to ECM and inflammation-related pathways. TIMER analysis indicated that the mRNA level of IGFBP7 was strongly correlated with genes related to various infiltrating immune cells in GC, especially with gene markers of tumor associated macrophages (TAMs).

Conclusions: Increased IGFBP7 expression correlates with poor prognosis and immune cell infiltration in GC, which might be a potential biomarker for the diagnosis of GC.

Serum Insulin-Like Growth Factor Binding Protein 7 as a Potential Biomarker in the Diagnosis and Prognosis of Esophagogastric Junction Adenocarcinoma

BACKGROUND/AIMS

Esophagogastric junction adenocarcinoma (EJA) is a malignant tumor associated with high morbidity and has attracted increasing attention due to a rising incidence and low survival rate. Pathological biopsy is the gold standard for diagnosis, but noninvasive and effective tests are lacking, resulting in diagnoses at advanced stages. This study explored the diagnostic value of insulin-like growth factor binding protein 7 (IGFBP7) in EJA.

METHODS

A total of 120 EJA patients and 88 normal controls were recruited, and their serum levels of IGFBP7 were measured by enzymelinked immunosorbent assay. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic value, and Pearson chi-square analysis was used to evaluate the correlation between IGFBP7 and clinical parameters. Kaplan- Meier survival analysis was carried out to assess the effect of IGFBP7 on overall survival (OS).

RESULTS

The levels of IGFBP7 were higher in both early- and late-stage EJA patients than in normal controls (p<0.001). The area under the ROC curve for EJA patients was 0.794 (95% confidence interval [CI], 0.733 to 0.854), with a cutoff value of 2.716 ng/mL, a sensitivity of 63.3% (95% CI, 54.0% to 71.8%) and a specificity of 90.9% (95% CI, 82.4% to 95.7%). For the diagnosis of early-stage EJA, the same cutoff value and specificity were obtained, but the sensitivity of IGFBP7 was 54.3% (95% CI, 36.9% to 70.8%). Patients with low IGFBP7 protein expression had lower OS than those with high expression (p=0.034). The multivariate analysis showed that IGFBP7 is an independent prognostic factor for EJA (p=0.011).

CONCLUSIONS

Serum IGFBP7 acts as a potential diagnostic and prognostic marker for EJA.

Effects of IGF-1 on Proliferation, Angiogenesis, Tumor Stem Cell Populations and Activation of AKT and Hedgehog Pathways in Oral Squamous Cell Carcinoma

(1) Background: Activation of the PI3K-AKT pathway controls most hallmarks of cancer, and the hedgehog (HH) pathway has been associated with oral squamous cell carcinoma (OSCC) development and progression. We hypothesized that fibroblast-derived insulin-like growth factor-1 (IGF-1) acts in oral squamous cell carcinoma (OSCC) cells, leading to the non-canonical activation of the HH pathway, maintaining AKT activity and promoting tumor aggressiveness. (2) Methods: Primary fibroblasts (MF1) were genetically engineered for IGF-1 overexpression (MF1-IGF1) and CRISPR/Cas9-mediated IGF1R silencing was performed in SCC-4 cells. SCC-4 cells were co-cultured with fibroblasts or incubated with fibroblast conditioned medium (CM) or rIGF-1 for functional assays and the evaluation of AKT and HH pathways. (3) Results: Gene expression analysis confirmed IGF-1 overexpression in MF1-IGF1 and the absence of IGF-1 expression in SCC-4, while elevated IGF1R expression was detected. IGF1R silencing was associated with decreased survival of SCC-4 cells. Ihh was expressed in both MF1 and MF1-IGF1, and increased levels of GLI1 mRNA were observed in SCC-4 after stimulation with CM-MF1. Activation of both PI3K-AKT and the HH pathway (GLI1, Ihh and SMO) were identified in SCC-4 cells cultured in the presence of MF1-IGF1-CM. rIGF-1 promoted tumor cell proliferation, migration, invasion and tumorsphere formation, whereas CM-MF1 significantly stimulated angiogenesis. (4) Conclusions: IGF-1 exerts pro-tumorigenic effects by stimulating SCC-4 cell proliferation, migration, invasion and stemness. AKT and HH pathways were activated by IGF-1 in SCC-4, reinforcing its influence on the regulation of these signaling pathways.

IGF-Binding Proteins, Adiponectin, and Survival in Metastatic Colorectal Cancer: Results From CALGB (Alliance)/SWOG 80405

Background

Energy balance-related biomarkers are associated with risk and prognosis of various malignancies. Their relationship to survival in metastatic colorectal cancer (mCRC) requires further study.

Methods

Baseline plasma insulin-like growth factor (IGF)-1, IGF-binding protein (IGFBP)-3, IGFBP-7, C-peptide, and adiponectin were measured at time of trial registration in a prospective cohort of patients with mCRC participating in a National Cancer Institute–sponsored trial of first-line systemic therapy. We used Cox proportional hazards regression to adjust for confounders and examine associations of each biomarker with overall survival (OS) and progression-free survival (PFS). P values are 2-sided.

Results

Median follow-up for 1086 patients was 6.2 years. Compared with patients in the lowest IGFBP-3 quintile, patients in the highest IGFBP-3 quintile experienced an adjusted hazard ratio (HR) for OS of 0.57 (95% confidence interval [CI] = 0.42 to 0.78; P_nonlinearity < .001) and for PFS of 0.61 (95% CI = 0.45 to 0.82; P_trend = .003). Compared with patients in the lowest IGFBP-7 quintile, patients in the highest IGFBP-7 quintile experienced an adjusted hazard ratio for OS of 1.60 (95% CI = 1.30 to 1.97; P_trend < .001) and for PFS of 1.38 (95% CI = 1.13 to 1.69; P_trend < .001). Plasma C-peptide and IGF-1 were not associated with patient outcomes. Adiponectin was not associated with OS; there was a nonlinear U-shaped association between adiponectin and PFS (P_nonlinearity = .03).

Conclusions

Among patients with mCRC, high plasma IGFBP-3 and low IGFBP-7 were associated with longer OS and PFS. Extreme levels of adiponectin were associated with shorter PFS. These findings suggest potential avenues for prognostic and therapeutic innovation.

IGFBP5 modulates lipid metabolism and insulin sensitivity through activating AMPK pathway in non-alcoholic fatty liver disease

AIMS

Non-alcoholic fatty liver disease (NAFLD) characterized by excessive hepatic fat deposition is an increasing public health issue worldwide. Insulin resistance is a pivotal factor in NAFLD progression. Studies have found that IGFBP5 was related to insulin sensitivity. Nevertheless, the role of IGFBP5 in NAFLD remains unclear.

MATERIALS AND METHODS

NAFLD models were established in vitro and in vivo by treating HepG2 cells with free fatty acids (FFA) and feeding mice with high-fat diet (HFD), respectively. IGFBP5 expression was then analyzed in these models. The effects and mechanism of IGFBP5 on lipid lipogenesis, fatty acid β-oxidation, and insulin resistance were investigated following IGFBP5 overexpression. Additionally, AMPK inhibitor compound C was used to treat HepG2 cells to confirm whether IGFBP5 functioned via activating AMPK pathway.

KEY FINDINGS

IGFBP5 expression was decreased in both NAFLD models. IGFBP5 overexpression reduced levels of lipogenesis-associated proteins (SREBP-1c, FAS and ACC1), elevated expression of fatty acid β-oxidation-related genes (PPARα, CPT1A and ACOX1), decreased intracellular lipid droplets, promoted glucose uptake and glycogenesis, and activated IRS1/Akt and AMPK pathways. Administration of IGFBP5 vectors also decreased body weight and relieved liver damage in HFD-treated mice. In contrast, compound C abrogated the influences of IGFBP5 overexpression on cell models.

SIGNIFICANCE

IGFBP5 dampened hepatic lipid accumulation and insulin resistance in NAFLD development via activating AMPK pathway. This study indicates that IGFBP5 may be a novel therapeutic agent for NAFLD.

Elevated plasma sRAGE and IGFBP7 in heart failure decrease after heart transplantation in association with haemodynamics

Aims

Metabolic derangement is implicated in the pathophysiology of heart failure (HF) and pulmonary hypertension (PH). We aimed to identify the dynamics of metabolic plasma proteins linked to end‐stage HF and associated PH in relation to haemodynamics, before and after heart transplantation (HT).

Methods and results

Twenty‐one metabolic plasma proteins were analysed with proximity extension assay in 20 controls and 26 patients before and 1 year after HT. Right heart catheterizations were performed in the HF patients pre‐operatively and 1 year after HT. Plasma levels of soluble receptor for advanced glycation end products (sRAGE) and insulin‐like growth factor‐binding protein 7 (IGFBP7) were higher in HF patients compared with controls (P < 0.0001) and decreased after HT (P < 0.0001), matching controls' levels. The decrease in sRAGE after HT correlated with improved mean pulmonary arterial pressure (r_s = 0.7; P < 0.0001), pulmonary arterial wedge pressure (r_s = 0.73; P < 0.0001), pulmonary vascular resistance (r_s = 0.65; P = 0.00062), and pulmonary arterial compliance (r_s = −0.52; P = 0.0074). The change in plasma IGFBP7 after HT correlated with improved mean right atrial pressure (r_s = 0.71; P = 0.00011) and N‐terminal pro‐brain natriuretic peptide (r_s = 0.71; P < 0.0001).

Conclusions

Our results indicate that plasma sRAGE may reflect passive pulmonary vascular congestion and the ‘mechanical’ state of the pulmonary vasculature in HF patients with or without related PH. Furthermore, sRAGE and IGFBP7 may provide additional insight into the pathophysiological mechanisms in HF and associated PH. Their potential clinical and therapeutic relevance in HF and associated PH need further investigation.

Insulin Growth Factor Binding Protein 7 (IGFBP7)-Related Cancer and IGFBP3 and IGFBP7 Crosstalk

The insulin/insulin-like growth factors (IGFs) have crucial tasks in the growth, differentiation, and proliferation of healthy and pernicious cells. They are involved in coordinated complexes, including receptors, ligands, binding proteins, and proteases. However, the systems can become dysregulated in tumorigenesis. Insulin-like growth factor-binding protein 7 (IGFBP7) is a protein belonging to the IGFBP superfamily (also termed GFBP-related proteins). Numerous studies have provided evidence that IGFBP3 and IGFBP7 are involved in a variety of cancers, including hepatocellular carcinoma (HCC), breast cancer, gastroesophageal cancer, colon cancer, prostate cancer, among many others. Still, very few suggest an interaction between these two molecules. In studying several cancer types in our laboratories, we found that both proteins share some crucial signaling pathways. The objective of this review is to present a comprehensive overview of the relationship between IGFBP7 and cancer, as well as highlighting IGFBP3 crosstalk with IGFBP7 reported in recent studies.

Associations between IGF1, IGFBP2 and TGFß3 Genes Polymorphisms and Growth Performance of Broiler Chicken Lines

Marker-assisted selection based on fast and accurate molecular analysis of individual genes is considered an acceptable tool in the speed-up of the genetic improvement of production performance in chickens. The objective of this study was to detect the single nucleotide polymorphisms (SNPs) in the IGF1, IGFBP2 and TGFß3 genes, and to investigate their associations with growth performance (body weight (BW) and average daily gain (ADG) at 14, 21, 28, 35 and 42 days of age) and carcass traits in broilers. Performance (carcass) data (weight before slaughter; weights of the trunk, giblets, abdominal fat, breast muscle and thigh muscle; slaughter value and slaughter percentage), as well as blood samples for DNA extraction and SNP analysis, were obtained from 97 chickens belonging to two different lines (Hubbard F15 and Cobb E) equally divided between the two sexes. The genotypes were detected using polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP) methods with specific primers and restrictase for each gene. The statistical analysis discovered significant associations (p < 0.05) between the TGFβ3 SNP and the following parameters: BW at 21, 28 and 35 days, trunk weight and slaughter value. Association analysis of BWs (at 21, 28 and 35 days) and SNPs was always significant for codominant, dominant and overdominant genetic models, showing a possible path for genomic selection in these chicken lines. Slaughter value was significant for codominant, recessive and overdominant patterns, whereas other carcass traits were not influenced by SNPs. Based on the results of this study, we suggested that the TGFβ3 gene could be used as a candidate gene marker for chicken growth traits in the Hubbard F15 and Cobb E population selection programs, whereas for carcass traits further investigation is needed.

Diagnostic Value of Serum Insulin-Like Growth Factor Binding Protein 7 (IGFBP7) in Colorectal Cancer

PURPOSE

High serum insulin-like growth factor binding protein-7 (IGFBP-7) has been found in several malignant tumors. Here, we aimed to assess the diagnostic potential of serum IGFBP7 in patients with colorectal cancer (CRC).

PATIENTS AND METHODS

An enzyme-linked immunosorbent assay (ELISA) was performed to detect IGFBP7 level in the serum of 115 CRC patients and 107 healthy controls, and receiver operating characteristics (ROC) was used to evaluate the accuracy of diagnosis.

RESULTS

The levels of serum IGFBP7 were significantly higher in CRC than those in normal controls (P < 0.001). With optimized cutoff of 2.050 ng/mL, IGFBP7 showed certain diagnostic value with specificity of 93.9%, sensitivity of 64.5% and an area under the curve (AUC) of 0.815 (95% CI: 0.754-0.877) in CRC. In early-stage CRC, IGFBP7 provided an AUC of 0.826 (95% CI: 0.757-0.896), a sensitivity of 64.5%, and a specificity of 95.8%. Furthermore, when compared with carcinoembryonic antigen (CEA), the accuracy of serum IGFBP7 in the diagnosis of CRC and early-stage CRC were significantly improved. Analysis of clinical data shows that there are no significant differences between IGFBP7 and clinical factors.

CONCLUSION

Our study suggested that serum IGFBP7 might serve as a potential biomarker for early-stage CRC diagnosis.

Eleutheroside B Protects against Acute Kidney Injury by Activating IGF Pathway

Acute kidney injury (AKI) is a common, complex, and severe clinical syndrome characterized by rapid decline in renal function, combined with tissue damage. Currently, the prevention and treatment of AKI are focused on symptomatic treatment, rather than treating the underlying causes. Therefore, there is no specific treatment to prevent renal injury except for renal dialysis. In this study, we used cisplatin-induced AKI mouse and human kidney-2 (HK-2) cell models to evaluate the renal protective effect of eleutheroside B, an active compound in traditional Chinese medicines. MTT assay was used to detect the effect of eleutheroside B on proliferation of human HK-2 cells in presence and in absence of cisplatin. Western blot and immunostaining were used to detect the protein level of kidney injury molecule-1 (KIM-1), cleaved caspase-3, receptor-interacting protein kinase (RIPK)-1, and RIPK-3. Real-time PCR was used to detect the mRNA levels of chemokines (like monocyte chemotactic protein 1, MCP-1) and pro-inflammatory cytokines including interleukin-6 (IL-6) and tumor necrosis factor (TNF-α). Flow cytometry assay was used to detect apoptosis of HK-2 cells. In vivo results showed that eleutheroside B reduced the increase in serum creatinine and blood urea nitrogen (BUN) levels in the AKI model. Periodic acid-Schiff staining and Western blot analysis of KIM-1 showed that eleutheroside B alleviated tubular cell injury. Further, eleutheroside B reduced macrophage infiltration and production of inflammatory cytokines, inhibited the activation of nuclear factor (NF)-κB, and inhibited apoptosis and programmed necrosis. The mechanism may be that eleutheroside B can activate the insulin-like growth factor (IGF) pathway and its downstream pathway by downregulating the expression of IGFBP-7, thus promoting cell proliferation. Therefore, our results suggest that eleutheroside B is a potential drug for AKI treatment.

Nausea and vomiting of pregnancy and hyperemesis gravidarum

Nausea and vomiting of pregnancy (NVP) is a common condition that affects as many as 70% of pregnant women. Although no consensus definition is available for hyperemesis gravidarum (HG), it is typically viewed as the severe form of NVP and has been reported to occur in 0.3-10.8% of pregnant women. HG can be associated with poor maternal, fetal and child outcomes. The majority of women with NVP can be managed with dietary and lifestyle changes, but more than one-third of patients experience clinically relevant symptoms that may require fluid and vitamin supplementation and/or antiemetic therapy such as, for example, combined doxylamine/pyridoxine, which is not teratogenic and may be effective in treating NVP. Ondansetron is commonly used to treat HG, but studies are urgently needed to determine whether it is safer and more effective than using first-line antiemetics. Thiamine (vitamin B1) should be introduced following protocols to prevent refeeding syndrome and Wernicke encephalopathy. Recent advances in the genetic study of NVP and HG suggest a placental component to the aetiology by implicating common variants in genes encoding placental proteins (namely GDF15 and IGFBP7) and hormone receptors (namely GFRAL and PGR). New studies on aetiology, diagnosis, management and treatment are under way. In the next decade, progress in these areas may improve maternal quality of life and limit the adverse outcomes associated with HG.

IGFBP7 downregulation or overexpression effect on bovine preadipocyte differentiation

The insulin-like growth factor binding-protein 7 (IGFBP7) has binding affinities to IGFs and is able to either positively or negatively regulate the IGFs signaling pathway. It also plays a crucial role in cell growth, differentiation and development in an IGF-independent manner. Herein, we investigated the specific regulation of the gene encoding for IGFBP7during the differentiation process of the adipocyte cells of the Yan Yellow Cattle by interfering with or by overexpressing the IGFBP7 gene. As a result, we found that the mRNA expression levels of IGFBP7 were significantly increased during the formation of progenitor cells. In addition, the expression levels of the lipoprotein lipase (LPL) and transcription factors (PPARγ, C/EBPα) were also significantly increased. IGFBP7 gene overexpression and RNA interfering promoted and inhibited respectively the lipid accumulation and triglyceride production in mature adipocytes, and the expression of the LPL and transcription factors (PPARγ, C/EBPα). The changes in the protein expression levels of IGFBP7 and adipogenic factors were in accord with the changes observed in the mRNA levels. In conclusion, our results indicate that IGFBP7 plays an important regulatory role in the differentiation of preadipocyte cells.

IGF-1 reverses the osteogenic inhibitory effect of dexamethasone on BMP9-induced osteogenic differentiation in mouse embryonic fibroblasts via PI3K/AKT/COX-2 pathway

Glucocorticoid-Induced Osteoporosis (GIOP) is a prevalent clinical complication caused by large dose administration of glucocorticoids, such as Dexamethasone (Dex) and Prednisone. GIOP may lead to fractures and even Osteonecrosis of the Femoral Head (ONFH). It has been reported that glucocorticoids inhibit osteogenesis via the suppression of osteogenic differentiation in Mesenchymal Stem Cells (MSCs), but the precise mechanism underlying this suppression awaits further investigation. Meanwhile, novel and efficacious therapies are recommended to cope with GIOP. In this study, we demonstrated that Dex had the inhibitory effect on Bone Morphogenetic Protein 9 (BMP9)-induced ALP activities and matrix mineralization in Mouse Embryonic Fibroblasts (MEFs). In addition, the study confirmed that Dex decreased the expression of osteogenic markers such as Runx2 and OPN. However, the inhibitory effect of Dex on these osteogenic markers can be reversed when combined with insulin-like growth factor 1 (IGF-1). Regarding the inhibitory mechanism, we found that the level of AKT and p-AKT can be decreased by Dex and that Ly294002, the PI3K inhibitor, can block the reversal effect of IGF-1. Moreover, the knockdown or inhibition of COX-2 produced similar results to those of Ly294002. Our findings indicated that IGF-1 may reverse the osteogenic inhibitory effect of Dex via PI3K/AKT pathway, which may be associated with the up-regulation of COX-2. This study may provide new clinical management strategy for GIOP cases.

Insulin-like growth factor binding protein-7: A marker of conjunctivalization in an animal model of limbal stem cell deficiency

PURPOSE

Limbal stem cell deficiency (LSCD) is characterized by the loss of limbal epithelial stem cells, resulting in a pathological process termed 'conjunctivalization' which compromises corneal transparency, leading to blindness. Current diagnosis for LSCD is limited because reliable conjunctiva-specific biomarkers are lacking. This study sought to address this shortcoming through the serendipitous discovery of insulin-like growth factor binding protein (IGFBP)-7.

METHODS

IGFBP-7 expression was determined in normal (n=83) and conjunctivalized (n=52) mouse corneas with experimentally-induced LSCD, and in cadaveric normal human corneas (n=7) and human pterygia (n=15); a disease characterized by the invasion of a conjunctivalized, fibrovascular pannus. Clinical assessments including slit-lamp microscopy, fluorescein staining and impression cytology, and biochemical, molecular and immunological assays were also conducted.

RESULTS

Mass spectrometry of conditioned media from mouse limbal explant-derived cells revealed the presence of IGFBP-7. This factor was expressed in normal limbal and conjunctival epithelium and conjunctivalized corneas from mice with LSCD, and in human pterygium epithelium but not in normal mouse or human corneal epithelium. Four weeks after inducing LSCD, IGFBP-7 staining was increased by 2.9-fold in mouse corneas compared to steady-state, and by 1.6-fold in impression cytology specimens derived from the same mice. Notably, IGFBP-7 was detected approximately 2-weeks earlier than Muc5AC.

CONCLUSIONS

This study provides novel insights into the specificity of IGFBP-7 for the mammalian conjunctival epithelium in health and disease. A point-of-care test for IGFBP-7 could be developed to assist clinicians in early diagnosis, and in monitoring disease progression, severity and therapeutic outcomes in patients with LSCD.

Insulin-like growth factor binding proteins and angiogenesis: from cancer to cardiovascular disease

Angiogenesis is a tightly regulated activity that is vital during embryonic development and for normal physiological repair processes and reproduction in healthy adults. Pathological angiogenesis is a driving force behind a variety of diseases including cancer and retinopathies, and inhibition of angiogenesis is a therapeutic option that has been the subject of much research, with several inhibitory agents now available for medical therapy. Conversely, therapeutic angiogenesis has been mooted as having significant potential in the treatment of ischemic conditions such as angina pectoris and peripheral arterial disease, but so far there has been less translation from lab to bedside. The insulin-like growth factor binding proteins (IGFBP) are a family of seven proteins essential for the binding and transport of the insulin-like growth factors (IGF). It is being increasingly recognised that IGFBPs have a significant role beyond simply modulating IGF activity, with evidence of both IGF dependent and independent actions through a variety of mechanisms. Moreover, the action of the IGFBPs can be stimulatory or inhibitory depending on the cell type and environment. Specifically the IGFBPs have been heavily implicated in angiogenesis, both pathological and physiological, and they have significant promise as targeted cell therapy agents for both pathological angiogenesis inhibition and therapeutic angiogenesis following ischemic injury. In this short review we will explore the current understanding of the individual impact of each IGFBP on angiogenesis, and the pathways through which these effects occur.

IGFBP7 contributes to epithelial-mesenchymal transition of HPAEpiC cells in response to radiation

Radiation-induced lung injury (RILI) frequently occurs in patients with thoracic malignancies. In response to radiation, alveolar epithelial cells (AEC) undergo epithelial-mesenchymal transition (EMT) and contribute to the pathogenesis of RILI. Insulin-like growth factor binding protein 7 (IGFBP7) is reported as a downstream mediator of transforming growth factor-β1 (TGF-β1) pathway, which plays a crucial role in radiation-induced EMT. In the present study, the levels of IGFBP7 and TGF-β1 were simultaneously increased in experimental RILI models and radiation-treated AEC (human pulmonary alveolar epithelial cells [HPAEpic]). The expression of IGFBP7 in radiation-treated HPAEpic cells was obviously inhibited by the specific inhibitor of TGF-β receptor antagonist SB431542 and TGF-β1 neutralizing antibody, and time-dependently enhanced by TGF-β1 treatment. Moreover, IGFBP7 knockdown significantly attenuated the effects of radiation on morphology change, cell migration, expression of EMT-related markers (E-cadherin, α-SMA, and Vimentin), and phosphorylation of extracellular-signal-regulated kinase (ERK). The effects of IGFBP7 overexpression on the expression of EMT-related markers were partially reversed by the ERK inhibitor PD98059. In conclusion, IGFBP7, was enhanced by TGF-β1, may be involved in radiation-induced EMT of AEC via the ERK signaling pathway, thus contributing to the pathogenesis of RILI.

IGFBP-rP1, a strongly conserved member of the androgenic hormone signalling pathway in Isopoda

The first protein which has been described to interact with the malacostracan Androgenic Gland Hormone (AGH) is a binding protein called IGFBP-rP1. It has been identified and studied in several species of decapods, in which its interaction with the masculinizing hormone and its expression patterns have been established in several ways. However, this protein remains uncharacterised to date in the other malacostracan orders, like Amphipoda and Isopoda, although they were historically the first ones in which the androgenic gland and the corresponding hormone were respectively described. In this article, we identified the IGFBP-rP1 of isopods and established its implication in the pathway of the AGH with a silencing approach in the model species Armadillidium vulgare. We also showed that this gene is expressed in all the tissues of males and females, with a similar pattern in animals infected with Wolbachia, a feminizing endosymbiont of several isopod species. The expression pattern did not differ during the development of uninfected and infected animals either. We finally studied the evolution of the IGFBP-rP1 in 68 isopod species, looking for conserved motifs and evidence of natural selection. Altogether, our results showed that this gene is constitutively expressed and strongly conserved in isopods, in which it likely constitutes a key element of the insulin/IGF signalling pathway. However, we also illustrated that IGFBP-rP1 is not sufficient on its own to explain the different developmental paths taken by the males and the females or feminized genetic males.

Characterization of insulin and IGF-1 receptor binding in equine liver and lamellar tissue: implications for endocrinopathic laminitis

Although it is well established that equine laminitis can be triggered by extreme hyperinsulinemia, the mechanism of insulin action is not known. High concentrations of insulin lead to separation of the weight-bearing apparatus from the hoof wall and are associated with an increased cycle of cell death and proliferation in the lamellae. Gene expression and immunohistochemistry studies have indicated that the lamellae are sparsely populated with insulin receptors, whereas IGF-1 receptors (IGF-1R) are abundant, suggesting that the action of insulin may be mediated by insulin binding to the IGF-1R. To investigate this possibility, cell membrane fragments containing IGF-1R were extracted from the livers of 6 horses and the lamellae of >50 horses euthanized for nonresearch purposes at an abattoir. Radioligand-binding studies using ¹²⁵I-IGF-1 and ¹²⁵I-insulin confirmed an abundance of high-affinity IGF-1R in the liver (K_D 0.11 nM, B_max 223 fmol/mg protein) and lamellae (K_D 0.16 nM, B_max 243 fmol/mg protein). However, the affinity of insulin for binding to the lamellar IGF-1R (K_i 934 nM) was >5,800 fold less than that of IGF-1, suggesting that insulin is unlikely to bind to equine IGF-1R at physiological concentrations. Although insulin receptors could be detected in the liver (K_D 0.48 nM, B_max 123 fmol/mg protein), they were barely detectable in lamellae (estimated B_max 14 fmol/mg protein). There was no evidence to support the presence of insulin/IGF-1 hybrid receptors in either tissue. These findings suggest that insulin does not act directly through IGF-1 receptors and that an alternative theory is required to explain the mechanism of insulin action in laminitis.

The insulin like growth factor and binding protein family: Novel therapeutic targets in obesity & diabetes

Background

Recent changes in nutrition and lifestyle have provoked an unprecedented increase in the prevalence of obesity and metabolic disorders. Recognition of the adverse effects on health has prompted intense efforts to understand the molecular determinants of insulin sensitivity and dysglycemia. In many respects, actions of insulin-like growth factors (IGFs) mirror those of insulin in metabolic regulation. Unlike insulin, however, the bioactivity of IGFs is regulated by a family of seven high-affinity binding proteins (IGFBPs) which confer temporospatial modulation with implications for metabolic homeostasis. In addition, evidence is accumulating that IGF-independent actions of certain of the IGFBPs can directly modulate insulin sensitivity.

Scope of review

In this review, we discuss the experimental data indicating a critical role for IGF/IGFBP axis in metabolic regulation. We highlight key discoveries through which IGFBPs have emerged as biomarkers or putative therapeutic targets in obesity and diabetes.

Major conclusions

Growing evidence suggests that several components of the IGF-IGFBP system could be explored for therapeutic potential in metabolic disorders. Both IGFBP-1 and IGFBP-2 have been favorably linked with insulin sensitivity in humans and preclinical data implicate direct involvement in the molecular regulation of insulin signaling and adiposity respectively. Further studies are warranted to evaluate clinical translation of these findings.

Structures of insect Imp-L2 suggest an alternative strategy for regulating the bioavailability of insulin-like hormones

The insulin/insulin-like growth factor signalling axis is an evolutionary ancient and highly conserved hormonal system involved in the regulation of metabolism, growth and lifespan in animals. Human insulin is stored in the pancreas, while insulin-like growth factor-1 (IGF-1) is maintained in blood in complexes with IGF-binding proteins (IGFBP1-6). Insect insulin-like polypeptide binding proteins (IBPs) have been considered as IGFBP-like structural and functional homologues. Here, we report structures of the Drosophila IBP Imp-L2 in its free form and bound to Drosophila insulin-like peptide 5 and human IGF-1. Imp-L2 contains two immunoglobulin-like fold domains and its architecture is unrelated to human IGFBPs, suggesting a distinct strategy for bioavailability regulation of insulin-like hormones. Similar hormone binding modes may exist in other insect vectors, as the IBP sequences are highly conserved. Therefore, these findings may open research routes towards a rational interference of transmission of diseases such as malaria, dengue and yellow fevers.

Elevated HTRA1 and HTRA4 in severe preeclampsia and their roles in trophoblast functions

Aberrant gene expression during placental development may affect fetal growth and contribute to preeclampsia. The high‑temperature requirement A (HTRA) family of proteins are serine proteases that may serve in the quality control of misfolded or mislocalized proteins. Recently, the potential involvement of HTRA1 and HTRA4 in the normal development of the placenta and in the pathogenesis of preeclampsia has been reported. The present study collected placental tissues from patients with severe preeclampsia and gestational age‑matched control samples. The expression of HTRA1 and HTRA4 was analyzed using reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemistry. The human trophoblast line HTR‑8 was transfected with HTRA1 or HTRA4, and cell function was assessed. The present study also detected the expression of HTRA1 and HTRA4 in HTR‑8/SVneo transfected cells under hypoxia (1% O2) and further studied the effects of hypoxia on HTR‑8 cell migration. HTRA1 and HTRA4 were mainly localized to the cytoplasm of syncytiotrophoblasts. The expression levels of the two genes were elevated in the placental tissues of patients with severe preeclampsia. Finally, it was determined in vitro that ectopic expression of HTRA1 and HTRA4 significantly attenuated HTR‑8 cell migration, and elevated HTRA1 limited HTR‑8 cell growth. Under hypoxic conditions, the expression levels of HTRA1 and HTRA4 improved significantly. It was hypothesized that the aberrant expression of HTRA1 or HTRA4 may be involved in the onset of preeclampsia, and increased HTRA1 or HTRA4 expression may affect trophoblast functions.

Comparison of Prognostic Usefulness of Serum Insulin-Like Growth Factor-Binding Protein 7 in Patients With Heart Failure and Preserved Versus Reduced Left Ventricular Ejection Fraction

We aimed to characterize of the role of insulin-like growth factor-binding protein 7 (IGFBP-7) in heart failure (HF) pathophysiology. IGFBP-7 has been associated with cardiac hypertrophy and diastolic dysfunction in HF. In 86 patients with HF with a preserved ejection fraction (HFpEF) (ejection fraction [EF] ≥45%) and 79 with HF with a reduced ejection fraction (HFrEF), we assessed concentrations of serum IGFBP-7, correlations between serum IGFBP-7 and clinical data, diastolic function, and associations with outcome. IGFBP-7 was lower in HFpEF than HFrEF (102 vs 152 µg/L, p <0.001) and correlated with New York Heart Association class (HFpEF: r = 0.25, p = 0.020; HFrEF: r = 0.26, p = 0.022), N-terminal pro-brain natriuretic peptide (NT-proBNP) (HFpEF: r = 0.53, p <0.001; HFrEF: r = 0.50, p <0.001), and estimated glomerular filtration rate (eGFR) (HFpEF: r = -0.47, p <0.001; HFrEF: r = -0.45, p <0.001). In HFpEF, IGFBP-7 correlated with E/e' (r = 0.31, p = 0.012) and E/A ratio (r = 0.31, p = 0.011). In HFrEF, but not HFpEF, IGFBP-7 correlated with age (r = 0.29, p = 0.009) and atrial fibrillation (r = 0.34, p = 0.002). IGFBP-7 predicted the outcome in HFpEF (hazard ratio 4.19 [1.01 to 17.35], p = 0.048]) but not in HFrEF (0.72 [0.24 to 2.14], p = 0.554). In conclusion in HFrEF, IGFBP-7 was elevated and associated with HF severity but not prognostic, suggesting a marker of risk. In HFpEF, IGFBP-7 was less elevated but associated with markers of diastolic dysfunction, HF severity, and prognosis. IGFBP-7 may contribute to the progression of HFpEF possibly through inflammation and oxidative stress.

Biomarkers of Sepsis-Induced Acute Kidney Injury

Sepsis, an infection-induced systemic disease, leads to pathological, physiological, and biochemical abnormalities in the body. Organ dysfunction is caused by a dysregulated host response to infection during sepsis which is a major contributing factor to acute kidney injury (AKI) and the mortality rate for sepsis doubles due to coincidence of AKI. Sepsis-induced AKI is strongly associated with increased mortality and other adverse outcomes. More timely diagnosis would allow for earlier intervention and could improve patient outcomes. Sepsis-induced AKI is characterized by a distinct pathophysiology compared with other diseases and may also have unique patterns of plasma and urinary biomarkers. This concise review summarizes properties and perspectives of the biomarkers for their individual clinical utilization.

Linkage disequilibrium and functional analysis of PRE1 insertion together with SNPs in the promoter region of IGFBP7 gene in different pig breeds

Polymorphisms in regions upstream of transcription initiation site may modify the transcriptional activity of target genes by changing promoter activity. This study aims to determine whether or not polymorphisms at porcine IGFBP7 promoter region affect gene expression. In this study, eight SNPs and one PRE1 insertion in this region were first confirmed. The PRE1 insertion was widespread in 20 Chinese indigenous breeds, but was not observed in three commercial breeds. A perfect linkage disequilibrium, consisting of six of those SNPs and a PRE1, was observed with two haplotypes (h1 and h2) in five pig breeds. The h1 haplotype had an overwhelming superiority distribution in Large White, Landrace, and Bama mini-pig; in turn, the h2 only existed in the PRE1 presence breeds. As the haplotypes and PRE1 were located at gene promoter regions, we further investigated the transfection of plasmids with three different fragments of IGFBP-7 promoter region (H1, H2, RF). The CMV promoter of the pEGFP-N1 was substituted by these three different fragments, respectively. Different transcriptional and translational activities of EGFP in PK-15 cells were observed in these three recombinant plasmids by quantitative real-time PCR and flow cytometric analysis. The results indicated that H1 had the higher transcriptional and translational activities of EGFP as compared to the H2 (P < 0.05, P < 0.05). As compared to the RF group, EGFP mRNA expression level was significantly higher in H1 groups (P < 0.05). The IGFBP-7 promoter polymorphisms detected in this study may be important functional variants and potential genetic markers for pig population genetic study.

Epigenetic Downregulation and Growth Inhibition of IGFBP7 in Gastric Cancer

Background:

Insulin-like growth factor-binding protein 7 (IGFBP7) has been found to be a tumor suppressor in several human cancers, but the role of IGFBP7 in gastric cancer has not yet been fully investigated. Herein, we examined the epigenetic downregulation of IGFBP7 expression in gastric cancer.

Methods:

Expression and methylation of IGFBP7 in gastric cancer cells and primary gastric cancer patients were determined using qRT-PCR, western blot, immunohistochemistry, and methylation specific-PCR, respectively. The effects of IGFBP7 on gastric cancer cells were investigated by various experimental conditions, such as proliferation, colony formation, apoptosis, invasion, and migration assay.

Results:

IGFBP7 methylation was inversely correlated with IGFBP7 expression in gastric cancer. Univariate and multivariate analysis showed that IGFBP7 expression and tumor stage were independent prognostic factors. IGFBP7 knockdown increased gastric cancer cell growth, invasion, and migration, whereas IGFBP7 overexpression in gastric cancer cells induced cell growth inhibition and apoptosis.

Conclusion:

Our data suggest that IGFBP7 functions as a tumor suppressor in gastric cancer via an epigenetic pathway.