Identification of a novel cell death receptor mediating IGFBP-3-induced anti-tumor effects in breast and prostate cancer

Low expression levels of insulin-like growth factor binding protein-3 are correlated with poor prognosis for patients with hepatocellular carcinoma

Insulin-like growth factor binding protein-3 (IGFBP-3) has previously been identified as a putative tumor suppressor gene. The present study investigated the clinical and prognostic significance of IGFBP-3 expression levels in patients with hepatocellular carcinoma (HCC). Immunohistochemistry (IHC) probing for IGFBP-3 was performed on paraffin-embedded tissue samples obtained from 120 patients with HCC, including tissue samples from 120 primary cancer sites and 50 matched adjacent non-malignant sites. Receiver-operator curve (ROC) analysis was used to determine the cut-off scores for the presence of IGFBP-3-positive tumor cells and to estimate the survival time of the patients. The threshold for marking the positive expression of IGFBP-3 was 65%, based on the area under the ROC. Positive expression of IGFBP-3 was observed in 65/120 (54.2%) of the HCC tissues, and in 36/50 (72%) of the adjacent non-malignant liver tissues. Low levels of IGFBP-3 expression were correlated with tumor size (P=0.003), tumor multiplicity (P=0.044), node (P=0.008), metastasis (P=0.001) and clinical stage (P=0.001), as well as reduced survival time (P=0.015). Using univariate survival analysis, a significant direct correlation between high and low IGFBP-3 expression levels, and patient survival time (mean survival time high IGFBP-3, 39.4 vs. low IGFBP-3, 18.7 months) was identified. Kaplan-Meier analysis demonstrated that IGFBP-3 expression levels and patients survival time were significantly correlated (P<0.001). Multivariate analysis revealed IGFBP-3 expression to be an independent parameter (P=0.003). Therefore, low levels of IGFBP-3 expression are associated with advance clinicopathological classification and may be a predictor of poor survival in patients with HCC. Furthermore, these findings suggest that IGFBP-3 may serve as an independent molecular marker for the evaluation of prognosis in patients with HCC.

IGFBP3 Modulates Lung Tumorigenesis and Cell Growth through IGF1 Signaling

Insulin-like growth factor binding protein 3 (IGFBP3) modulates cell growth through IGF-dependent and -independent mechanisms. Reports suggest that the serum levels of IGFBP3 are associated with various cancers and that IGFBP3 expression is significantly decreased in cisplatin (CDDP)-resistant lung cancer cells. Based on these findings, we investigated whether Igfbp3 deficiency accelerates mouse lung tumorigenesis and if expression of IGFBP3 enhances CDDP response by focusing on the IGF1 signaling cascade. To this end, an Igfbp3-null mouse model was generated in combination with Kras^G12D to compare the tumor burden. Then, IGF-dependent signaling was assessed after expressing wild-type or a mutant IGFBP3 without IGF binding capacity in non-small cell lung cancer (NSCLC) cells. Finally, the treatment response to CDDP chemotherapy was evaluated under conditions of IGFBP3 overexpression. Igfbp3-null mice had increased lung tumor burden (>2-fold) and only half of human lung cancer cells survived after expression of IGFBP3, which corresponded to increased cleaved caspase-3 (10-fold), inactivation of IGF1 and MAPK signaling. In addition, overexpression of IGFBP3 increased susceptibility to CDDP treatment in lung cancer cells. These results, for the first time, demonstrate that IGFBP3 mediates lung cancer progression in a Kras^G12D mouse model. Furthermore, overexpression of IGFBP3 induced apoptosis and enhanced cisplatin response in vitro and confirmed that the suppression is in part by blocking IGF1 signaling.Implications: These findings reveal that IGFBP3 is effective in lung cancer cells with high IGF1 signaling activity and imply that relevant biomarkers are essential in selecting lung cancer patients for IGF1-targeted therapy. Mol Cancer Res; 15(7); 896-904. ©2017 AACR.

IL-13Rα2 uses TMEM219 in chitinase 3-like-1-induced signalling and effector responses

Recent studies demonstrated that chitinase 3-like-1 (Chi3l1) binds to and signals via IL-13Rα2. However, the mechanism that IL-13Rα2 uses to mediate the effects of Chi3l1 has not been defined. Here, we demonstrate that the membrane protein, TMEM219, is a binding partner of IL-13Rα2 using yeast two-hybrid, co-immunoprecipitation, co-localization and bimolecular fluorescence complementation assays. Furthermore, fluorescence anisotropy nanodisc assays revealed a direct physical interaction between TMEM219 and IL-13Rα2-Chi3l1 complexes. Null mutations or siRNA silencing of TMEM219 or IL-13Rα2 similarly decreased Chi3l1-stimulated epithelial cell HB-EGF production and macrophage MAPK/Erk and PKB/Akt activation. Null mutations of TMEM219 or IL-13Rα2 also phenocopied one another as regards the ability of Chi3l1 to inhibit oxidant-induced apoptosis and lung injury, promote melanoma metastasis and stimulate TGF-β1. TMEM219 also contributed to the decoy function of IL-13Rα2. These studies demonstrate that TMEM219 plays a critical role in Chi3l1-induced IL-13Rα2 mediated signalling and tissue responses.

Suppression of IGF binding protein-3 by palmitate promotes hepatic inflammatory responses

IGF-binding protein-3 (IGFBP-3) is a liver-derived, anti-inflammatory molecule that is decreased in obesity, a key risk factor for nonalcoholic fatty liver disease (NAFLD). It was not known whether IGFBP-3 levels were altered in NAFLD, whether such alterations could be the result of lipotoxicity, and whether altered IGFBP-3 could affect pathways that are involved in hepatic and systemic inflammation. Serum IGFBP-3 was decreased in patients with NAFLD, whereas liver and circulating IL-8 levels were increased. Palmitate inhibited IGFBP-3 secretion by THP-1 macrophages and enhanced IL-8 expression. Exposure of palmitate-treated THP-1 macrophages to IGFBP-3-deficient conditioned medium led to a 20-fold increase in palmitate-induced IL-8 expression by hepatocytes. Conversely, overexpression of IGFBP-3 suppressed JNK and NF-κB activation and blocked palmitate-induced IL-8 expression in hepatocytes. Silencing IGFBP-3 in Huh7 cells enhanced JNK and NF-κB activity and increased palmitate-induced IL-8 secretion. These data indicate that IGFBP-3 serves as an anti-inflammatory brake in hepatocytes against JNK and NF-κB and limits their activation and downstream production of proinflammatory cytokines. Under lipotoxic conditions, palmitate inhibits hepatic macrophage secretion of IGFBP-3, thereby releasing the brake and enhancing palmitate-induced IL-8 synthesis and secretion.-Min, H.-K., Maruyama, H., Jang, B. K., Shimada, M., Mirshahi, F., Ren, S., Oh, Y., Puri, P., Sanyal, A. J. Suppression of IGF binding protein-3 by palmitate promotes hepatic inflammatory responses.

Role of IGF Binding Proteins in Regulating Metabolism

Insulin-like growth factors (IGFs) circulate in extracellular fluids bound to a family of binding proteins. Although they function in a classical manner to limit the access of the IGFs to their receptors they also have a multiplicity of actions that are independent of this property; they bind to their own receptors or are transported to intracellular and intranuclear sites to influence cellular functions that may directly or indirectly modify IGF actions. The availability of genetically modified animals has helped to determine their functions in a physiological context. These results show that many of their actions are cell type- and context-specific, and have led to a broader understanding of how these proteins function coordinately with IGF-I and -II to regulate growth and metabolism.

Role of insulin-like growth factor-binding proteins in the pathophysiology and tumorigenesis of gastroesophageal cancers

The insulin family of proteins include insulin-like growth factor binding proteins (IGFBPs) that are classified into two groups based on their differential affinities to IGFs: IGF high-affinity binding proteins (IGFBP1-6) and IGF low-affinity IGFBP-related proteins (IGFBP-rP1-10). IGFBPs interact with many proteins, including their canonical ligands insulin-like growth factor 1 (IGF-I) and IGF-II. Together with insulin-like growth factor 1 (IGF1) receptor (IGF1R), IGF2R, and ligands (IGF1 and IGF2), IGFBPs participate in a complex signaling axis called IGF-IGFR-IGFBP. Numerous studies have demonstrated that the IGF-IGFR-IGFBP axis is relevant in gastrointestinal (GI) and other cancers. The presence of different IGFBPs have been reported in gastrointestinal cancers, including esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAD or EAC), and gastric adenocarcinoma (GAD or GAC). A literature-based survey clearly indicates that an urgent need exists for a focused review of the role of IGFBPs in gastrointestinal cancers. The aim of this review is to present the biochemical and molecular characteristics of IGFBPs with an emphasis specifically on the role of these proteins in the pathophysiology and tumorigenesis of gastroesophageal cancers.

Inhibition of IGF1-R overcomes IGFBP7-induced chemotherapy resistance in T-ALL

BACKGROUND

T-cell acute lymphoblastic leukemia (T-ALL) is a genetically heterogeneous disease with the need for treatment optimization. Previously, high expression of Insulin-like growth factor binding protein 7 (IGFBP7), a member of the IGF system, was identified as negative prognostic factor in adult T-ALL patients. Since aberrant IGFBP7 expression was observed in a variety of neoplasia and was relevant for prognosis in T-ALL, we investigated the functional role of IGFBP7 in Jurkat and Molt-4 cells as in vitro models for T-ALL.

METHODS

Jurkat and Molt-4 cells were stably transfected with an IGFBP7 over-expression vector or the empty vector as control. Proliferation of the cells was assessed by WST-1 assays and cell cycle status was measured by flow-cytometry after BrDU/7-AAD staining. The effect of IGFBP7 over-expression on sensitivity to cytostatic drugs was determined in AnnexinV/7-AAD assays. IGF1-R protein expression was measured by Western Blot and flow-cytometric analysis. IGF1-R associated gene expression profiles were generated from microarray gene expression data of 86 T-ALL patients from the Microarrays Innovations in Leukemia (MILE) multicenter study.

RESULTS

IGFBP7-transfected Jurkat cells proliferated less, leading to a longer survival in a nutrient-limited environment. Both IGFBP7-transfected Jurkat and Molt-4 cells showed an arrest in the G0/G1 cell cycle phase. Furthermore, Jurkat IGFBP7-transfected cells were resistant to vincristine and asparaginase treatment. Surface expression and whole protein measurement of IGF1-R protein expression showed a reduced abundance of the receptor after IGFBP7 transfection in Jurkat cells. Interestingly, combination of the IGF1-R inhibitor NPV-AEW541 restored sensitivity to vincristine in IGFBP7-transfected cells. Additionally, IGF1-R associated GEP revealed an up-regulation of important drivers of T-ALL pathogenesis and regulators of chemo-resistance and apoptosis such as NOTCH1, BCL-2, PRKCI, and TP53.

CONCLUSION

This study revealed a proliferation inhibiting effect of IGFBP7 by G0/G1 arrest and a drug resistance-inducing effect of IGFBP7 against vincristine and asparaginase in T-ALL. These results provide a model for the previously observed association between high IGFBP7 expression and chemotherapy failure in T-ALL patients. Since the resistance against vincristine was abolished by IGF1-R inhibition, IGFBP7 could serve as biomarker for patients who may benefit from therapies including IGF1-R inhibitors in combination with chemotherapy.

Understanding the Key to Targeting the IGF Axis in Cancer: A Biomarker Assessment

Type 1 insulin like growth factor receptor (IGF-1R) targeted therapies showed compelling pre-clinical evidence; however, to date, this has failed to translate into patient benefit in Phase 2/3 trials in unselected patients. This was further complicated by the toxicity, including hyperglycemia, which largely results from the overlap between IGF and insulin signaling systems and associated feedback mechanisms. This has halted the clinical development of inhibitors targeting IGF signaling, which has limited the availability of biopsy samples for correlative studies to understand biomarkers of response. Indeed, a major factor contributing to lack of clinical benefit of IGF targeting agents has been difficulty in identifying patients with tumors driven by IGF signaling due to the lack of predictive biomarkers. In this review, we will describe the IGF system, rationale for targeting IGF signaling, the potential liabilities of targeting strategies, and potential biomarkers that may improve success.

Association between height and malignancy among children in the north of Iran

BACKGROUND

This study aim to determine the association between height and cancer in the children aged 14 years at the time of diagnosis in Rasht, Iran.

MATERIALS AND METHODS

In this cross-sectional study, height of patients with a malignancy (≤14) at the time of diagnosis measured in the standard charts of United States National Center for the Health Statistics (NCHS). Data were reported by descriptive statistics and analyzed by Regression tests in SPSS version 19.

RESULTS

Overall, 78 male (38.6%) and 124 female (61.4%) patients with various kinds of malignancies were evaluated for their heights. Leukemia was the most common type of cancer. The median height of the patients was more than 20(th) percentile and under 50(th) percentile of the NCHS. No significant association was found between height and leukemia.

CONCLUSION

Previously, the median height of Iranian girls and boys (≤15) reported under 20(th) percentile of the NCHS. In this study, the median height of the patients at the time of diagnosis was more than 20(th) percentile of the NCHS. There was a correlation between height and cancer among our patients, although, this correlation can be assessed by further cohort study.

The coordinate cellular response to insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-2 (IGFBP-2) is regulated through vimentin binding to receptor tyrosine phosphatase β (RPTPβ)

Insulin-like growth factor-binding protein-2 (IGFBP-2) functions coordinately with IGF-I to stimulate cellular proliferation and differentiation. IGFBP-2 binds to receptor tyrosine phosphatase β (RPTPβ), and this binding in conjunction with IGF-I receptor stimulation induces RPTPβ polymerization leading to phosphatase and tensin homolog inactivation, AKT stimulation, and enhanced cell proliferation. To determine the mechanism by which RPTPβ polymerization is regulated, we analyzed the protein(s) that associated with RPTPβ in response to IGF-I and IGFBP-2 in vascular smooth muscle cells. Proteomic experiments revealed that IGF-I stimulated the intermediate filament protein vimentin to bind to RPTPβ, and knockdown of vimentin resulted in failure of IGFBP-2 and IGF-I to stimulate RPTPβ polymerization. Knockdown of IGFBP-2 or inhibition of IGF-IR tyrosine kinase disrupted vimentin/RPTPβ association. Vimentin binding to RPTPβ was mediated through vimentin serine phosphorylation. The serine threonine kinase PKCζ was recruited to vimentin in response to IGF-I and inhibition of PKCζ activation blocked these signaling events. A cell-permeable peptide that contained the vimentin phosphorylation site disrupted vimentin/RPTPβ association, and IGF-I stimulated RPTPβ polymerization and AKT activation. Integrin-linked kinase recruited PKCζ to SHPS-1-associated vimentin in response to IGF-I and inhibition of integrin-linked kinase/PKCζ association reduced vimentin serine phosphorylation. PKCζ stimulation of vimentin phosphorylation required high glucose and vimentin/RPTPβ-association occurred only during hyperglycemia. Disruption of vimetin/RPTPβ in diabetic mice inhibited RPTPβ polymerization, vimentin serine phosphorylation, and AKT activation in response to IGF-I, whereas nondiabetic mice showed no difference. The induction of vimentin phosphorylation is important for IGFBP-2-mediated enhancement of IGF-I-stimulated proliferation during hyperglycemia, and it coordinates signaling between these two receptor-linked signaling systems.

Insulin-like growth factor binding protein-3 enhances etoposide-induced cell growth inhibition by suppressing the NF-κB activity in gastric cancer cells

Nuclear factor-kappaB (NF-κB) is a transcription factor that is activated in various neoplasms, including gastric cancer. Insulin-like growth factor binding protein-3 (IGFBP-3) is a potent tumor suppressor and is significantly suppressed in a variety of cancers. Although IGFBP-3 has been reported to have antiproliferative and proapoptotic effects, the precise mechanisms underlying the action of IGFBP-3 have not been elucidated. In this study, we found an inverse correlation between NF-κB activity and IGFBP-3 expression in patients with gastric cancer. Overexpression of IGFBP-3 resulted in significant inhibition of total and phosphorylated p65 NF-κB and IκB proteins in gastric cancer cells. IGFBP-3 further inhibited the expression of NF-κB-regulated cell adhesion molecules, ICAM-1 and VCAM-1. Finally, the growth inhibition induced by etoposide was significantly enhanced by IGFBP-3 overexpression along with concomitant suppression of NF-κB activity. These findings indicate that IGFBP-3 enhances etoposide-induced cell growth inhibition by blocking the NF-κB signaling pathway in gastric cancer cells. Furthermore, our data suggest that IGFBP-3 could be used as an adjuvant in the treatment of gastric cancer.

Novel acid-labile subunit ( IGFALS ) mutation p.T145K (c.434C>A) in a patient with ALS deficiency, normal stature and immunological dysfunction

We report a novel missense mutation p.T145K in the insulin-like growth factor (IGF) acid-labile subunit (IGFALS) gene identified in a Turkish patient with normal growth, transient pancytopenic episodes and signs of immunological dysfunction. Because of recurrent cutaneous mycoses and absence of pubertal development until the age of 14.75 years we determined several endocrine parameters in order to rule out autoimmune-polyendocrine syndromes. Despite a normal height between the 25th and 50th percentile we found severely decreased IGF-1 and undetectably low IGFBP-3 levels. Laboratory signs of immunological dysfunction included reduced total lymphocyte count with diminished B and T helper cell fractions, decreased serum concentrations of IgM and IgG subclass 4, and elevated antinuclear antibody and anti-dsDNA titers as well as persistently high interleukin-2-receptor levels. Further endocrine work-up revealed elevated fasting insulin and undetectably low ALS serum levels, leading to the diagnosis of ALS deficiency. Sequencing of the coding region of the IGFALS gene showed a novel homozygous missense mutation (c.434C>A; p.T145K). Since immunological abnormalities have not been reported in more than 20 ALS-deficient patients so far and our patient was born to consanguineous parents, a second autosomal recessive defect is likely to underlie the immunological phenotype, although a causative role of IGFALS p.T145K cannot be entirely ruled out.

Dissection of a novel autocrine signaling pathway via quantitative secretome and interactome mapping

Epidermal homeostasis is a balancing act governed by a multitude of underlying regulatory events, and several growth factors and signaling pathways have been implicated in regulation of the balance between proliferation and differentiation in keratinocytes. We show here that the signal transducer/transcription factor FIZ1 (Flt3 interacting zinc finger protein-1) is a previously unknown player in this regulatory axis, promoting an increase in proliferation of HaCaT human immortalized keratinocytes that is driven by more rapid G1/S progression and mediated by activation of the MAP/ERK kinase pathway. Utilizing quantitative SILAC-based secretome analysis, we identified the insulin growth factor binding protein IGFBP3 as the key mediating factor, demonstrating that elevated FIZ1 levels promote increased IGFBP3 expression and secretion and a concurrent increased sensitivity to IGF1 signaling, while antibody-based neutralization of IGFBP3 abrogates the FIZ1-induced growth advantage. To identify underlying protein-protein interactions likely to govern these events, we mapped the interactome of FIZ1 and found eight novel binding partners that form complexes with the protein in the cytoplasm and nucleus. These include signal transduction and transcription factors and the cell cycle regulatory NDR (Nuclear Dbf2-related) kinases. Our results provide further insight into the complex balance of epidermal homeostasis and identify FIZ1 as a novel therapeutic target.

Brain MRI abnormalities and spectrum of neurological and clinical findings in three patients with proximal 16p11.2 microduplication

The phenotype of recurrent ∼600 kb microdeletion and microduplication on proximal 16p11.2 is characterized by a spectrum of neurodevelopmental impairments including developmental delay and intellectual disability, epilepsy, autism and psychiatric disorders which are all subject to incomplete penetrance and variable expressivity. A variety of brain MRI abnormalities were reported in patients with 16p11.2 rearrangements, but no systematic correlation has been studied among patients with similar brain anomalies, their neurodevelopmental and clinical phenotypes. We present three patients with the proximal 16p11.2 microduplication exhibiting significant developmental delay, anxiety disorder and other variable clinical features. Our patients have abnormal brain MRI findings of cerebral T2 hyperintense foci (3/3) and ventriculomegaly (2/3). The neuroradiological or neurological findings in two cases prompted an extensive diagnostic work-up. One patient has exhibited neurological regression and progressive vision impairment and was diagnosed with juvenile neuronal ceroid-lipofuscinosis. We compare the clinical course and phenotype of these patients in regard to the clinical significance of the cerebral lesions and the need for MRI surveillance. We conclude that in all three patients the lesions were not progressive, did not show any sign of malignant transformation and could not be correlated to specific clinical features. We discuss potential etiologic mechanisms that may include overexpression of genes within the duplicated region involved in control of cell proliferation and complex molecular mechanisms such as the MAPK/ERK pathway. Systematic studies in larger cohorts are needed to confirm our observation and to establish the prevalence and clinical significance of these neuroanatomical abnormalities in patients with 16p11.2 duplications.

IGF binding proteins in cancer: mechanistic and clinical insights

The six members of the family of insulin-like growth factor (IGF) binding proteins (IGFBPs) were originally characterized as passive reservoirs of circulating IGFs, but they are now understood to have many actions beyond their endocrine role in IGF transport. IGFBPs also function in the pericellular and intracellular compartments to regulate cell growth and survival - they interact with many proteins, in addition to their canonical ligands IGF-I and IGF-II. Intranuclear roles of IGFBPs in transcriptional regulation, induction of apoptosis and DNA damage repair point to their intimate involvement in tumour development, progression and resistance to treatment. Tissue or circulating IGFBPs might also be useful as prognostic biomarkers.

Targeting insulin-like growth factor-I and insulin-like growth factor-binding protein-3 signaling pathways. A novel therapeutic approach for asthma

Insulin-like growth factor (IGF)-I has been recognized to play critical roles in the pathogenesis of asthma, whereas IGF-binding protein (IGFBP)-3 blocks crucial physiologic manifestations of asthma. IGF-I enhances subepithelial fibrosis, airway inflammation, airway hyperresponsiveness, and airway smooth muscle hyperplasia by interacting with various inflammatory mediators and complex signaling pathways, such as intercellular adhesion molecule-1, and the hypoxia-inducible factor/vascular endothelial growth factor axis. On the other hand, IGFBP-3 decreases airway inflammation and airway hyperresponsiveness through IGFBP-3 receptor-mediated activation of caspases, which subsequently inhibits NF-κB signaling pathway. It also inhibits the IGF-I/hypoxia-inducible factor/vascular endothelial growth factor axis via IGF-I-dependent and/or IGF-I-independent mechanisms. This Translational Review summarizes the role of IGF-I and IGFBP-3 in the context of allergic airway disease, and discusses the therapeutic potential of various strategies targeting the IGF-I and IGFBP-3 signaling pathways for the management of asthma.

Emerging role of insulin-like growth factor-binding protein 7 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a vicious and highly vascular cancer with a dismal prognosis. It is a life-threatening illness worldwide that ranks fifth in terms of cancer prevalence and third in cancer deaths. Most patients are diagnosed at an advanced stage by which time conventional therapies are no longer effective. Targeted molecular therapies, such as the multikinase inhibitor sorafenib, provide a modest increase in survival for advanced HCC patients and display significant toxicity. Thus, there is an immense need to identify novel regulators of HCC that might be targeted effectively. The insulin-like growth factor (IGF) axis is commonly abnormal in HCC. Upon activation, the IGF axis controls metabolism, tissue homeostasis, and survival. Insulin-like growth factor-binding protein 7 (IGFBP7) is a secreted protein of a family of low-affinity IGF-binding proteins termed “IGFBP-related proteins” that have been identified as a potential tumor suppressor in HCC. IGFBP7 has been implicated in regulating cellular proliferation, senescence, and angiogenesis. In this review, we provide a comprehensive discussion of the role of IGFBP7 in HCC and the potential use of IGFBP7 as a novel biomarker for drug resistance and as an effective therapeutic strategy.

Antitumor activity and immunogenicity of recombinant vaccinia virus expressing HPV 16 E7 protein SigE7LAMP is enhanced by high-level coexpression of IGFBP-3

We constructed recombinant vaccinia viruses (VACVs) coexpressing the insulin-like growth factor-binding protein-3 (IGFBP-3) gene and the fusion gene encoding the SigE7Lamp antigen. The expression of the IGFBP-3 transgene was regulated either by the early H5 promoter or by the synthetic early/late (E/L) promoter. We have shown that IGFBP-3 expression regulated by the H5 promoter yielded higher amount of IGFBP-3 protein when compared with the E/L promoter. The immunization with P13-SigE7Lamp-H5-IGFBP-3 virus was more effective in inhibiting the growth of TC-1 tumors in mice and elicited higher T-cell response against VACV-encoded antigen than the P13-SigE7Lamp-TK(-) control virus. We found that high-level production of IGFBP-3 enhanced virus replication both in vitro and in vivo, resulting in more profound antigen stimulation. Production of IGFBP-3 was associated with a higher adsorption rate of P13-SigE7Lamp-H5-IGFBP-3 to CV-1 cells when compared with P13-SigE7Lamp-TK(-). Intracellular mature virions (IMVs) of the IGFBP-3-expressing virus P13-SigE7Lamp-H5-IGFBP-3 have two structural differences: they incorporate the IGFBP-3 protein and they have elevated phosphatidylserine (PS) exposure on outer membrane that could result in increased uptake of IMVs by macropinocytosis. The IMV PS content was measured by flow cytometry using microbeads covered with immobilized purified VACV virions.

Activation of various downstream signaling molecules by IGFBP-3

Insulin-like growth factor binding protein-3 (IGFBP-3), a secretory protein, is the most abundant IGF binding protein present in human serum among all IGF binding proteins. IGFBP-3 shows decreased level of expression in cancerous cells but has been known to be present in significant amounts in normal or non-cancerous cells. IGFBP-3 can induce apoptosis in prostate cancer cells either in an IGF-dependent manner or independently of IGF binding. Although putative cell death specific Insulin-like growth factor binding protein-3 (IGFBP-3R) receptor(s) has recently been identified by which IGFBP-3 may induce its anti-tumor effects, IGFBP-3 has also been known to activate various downstream intracellular signaling molecules via a different mechanistic pathway. Stat-1 has been known to be one of the candidate molecules activated by IGFBP-3. IGFBP-3 can also inhibit Akt/IGF-1 survival pathway in MCF- 7 breast cancer cells which ultimately leads to the induction of apoptosis in these cells. All these studies clearly demonstrate that IGFBP-3 regulates cell proliferation and promotes its pro-apoptotic effects in cancer cells in two different pathways,1) sequester IGF-I to bind to IGF-I receptor to inhibit cell proliferation and induce apoptosis, 2) independent of IGF-I pathway, IGFBP-3 binds to some putative receptor and activate various downstream pro-apoptotic molecules involved in cell death.

Regulation of retinal endothelial cell apoptosis through activation of the IGFBP-3 receptor

The goal of this study was to investigate whether insulin-like growth factor binding protein-3 receptor (IGFBP-3 receptor) is required for IGFBP-3 to inhibit retinal endothelial cell (REC) apoptosis. REC were grown in normal glucose (5 mM) or high glucose medium (25 mM) for 3 days. Once cells reached confluence, they were transfected with an endothelial- specific IGFBP-3 plasmid DNA (non-IGF binding; IGFBP-3 NB) at 1 μg/ml for 24 h. Cell proteins were extracted and analyzed for IGFBP-3 receptor expression by Western blotting or use in coimmunoprecipitation or co-localization experiments for detection of IGFBP-3 and IGFBP-3 receptor binding. REC were also transfected with or without IGFBP-3 receptor siRNA before IGFBP-3NB plasmid DNA transfection. Cell lysates were processed for a cell death ELISA, a cleaved caspase 3 ELISA, and Western blotting to measure key pro- and anti-apoptotic markers: Bcl-xL, Bax, Cytochrome C and Akt. The IGFBP-3 receptor is present on REC. Overexpression of IGFBP-3 in REC significantly increased protein levels of IGFBP-3 receptor (p < 0.05). Significant increases in cell death were found in cells transfected with IGFBP-3 receptor siRNA versus not treated samples (p < 0.05). Data suggest that IGFBP-3 inhibits retinal endothelial cell death through activation of an IGFBP-3 receptor in a hyperglycemic environment. This is the first demonstration of the involvement of IGFBP-3 receptor in inhibition of REC cell death. Future studies will investigate the mechanism by which IGFBP-3 receptor may inhibit retinal endothelial cell death.

Prohibitin-2 binding modulates insulin-like growth factor-binding protein-6 (IGFBP-6)-induced rhabdomyosarcoma cell migration

Insulin-like growth factor (IGF)-binding protein (IGFBP)-6 decreases cancer cell proliferation and survival by inhibiting the effects of IGF-II. More recently, IGFBP-6 was found to promote the migration of rhabdomyosarcoma (RMS) cells in an IGF-independent manner, and MAPK pathways were involved in this process. However, the precise molecular mechanisms of these IGF-independent migratory actions of IGFBP-6 are largely unknown. Here, we report that prohibitin-2 (PHB2), a single-span membrane protein, is a key regulator of IGFBP-6-induced RMS cell migration. PHB2 and IGFBP-6 co-localize on the RMS cell surface, and they specifically interact, as demonstrated by affinity chromatography, co-immunoprecipitation, biosensor analysis, and confocal microscopy. Binding affinities for PHB2 are 9.0 ± 1.0 nM for IGFBP-6 and 10.2 ± 0.5 nM for mIGFBP-6, a non-IGF-binding mutant of IGFBP-6. The C-domain but not the N-domain of IGFBP-6 is involved in PHB2 binding. In addition, IGFBP-6 indirectly increases PHB2 tyrosine phosphorylation on RMS membranes. Importantly, PHB2 knockdown completely abolished IGFBP-6-mediated RMS cell migration. In contrast, IGFBP-6-induced MAPK pathway activation was not affected, suggesting that PHB2 may act as a downstream effector of these pathways. These results indicate that PHB2 plays a key role in this IGF-independent action of IGFBP-6 and suggest a possible therapeutic target for RMS.

Insulin-like growth factor binding protein-3 (IGFBP-3): Novel ligands mediate unexpected functions

In addition to its important role in the regulation of somatic growth by acting as the major circulating transport protein for the insulin-like growth factors (IGFs), IGF binding protein-3 (IGFBP-3) has a variety of intracellular ligands that point to its function within major signaling pathways. The discovery of its interaction with the retinoid X receptor has led to the elucidation of roles in regulating the function of several nuclear hormone receptors including retinoic acid receptor-α, Nur77 and vitamin D receptor. Its interaction with the nuclear hormone receptor peroxisome proliferator-activated receptor-γ is believed to be involved in regulating adipocyte differentiation, which is also modulated by IGFBP-3 through an interaction with TGFβ/Smad signaling. IGFBP-3 can induce apoptosis alone or in conjunction with other agents, and in different systems can activate caspases -8 and -9. At least two unrelated proteins (LRP1 and TMEM219) have been designated as receptors for IGFBP-3, the latter with a demonstrated role in inducing caspase-8-dependent apoptosis. In contrast, IGFBP-3 also has demonstrated roles in survival-related functions, including the repair of DNA double-strand breaks through interaction with the epidermal growth factor receptor and DNA-dependent protein kinase, and the induction of autophagy through interaction with GRP78. The ability of IGFBP-3 to modulate the balance between pro-apoptotic and pro-survival sphingolipids by regulating sphingosine kinase 1 and sphingomyelinases may be integral to its role at the crossroads between cell death and survival in response to a variety of stimuli. The pleiotropic nature of IGFBP-3 activity supports the idea that IGFBP-3 itself, or pathways with which it interacts, should be investigated as targets of therapy for a variety of diseases.

An ocular view of the IGF-IGFBP system

IGFs and their binding proteins have been shown to exhibit both protective and deleterious effects in ocular disease. Recent studies have characterized the expression patterns of different IGFBPs in retinal layers and within the vitreous. IGFBP-3 has roles in vascular protection stimulating proliferation, migration, and differentiation of vascular progenitor cells to sites of injury. IGFBP-3 increases pericyte ensheathment and shows anti-inflammatory effects by reducing microglia activation in diabetes. IGFBP-5 has recently been linked to mediating fibrosis in proliferative vitreoretinopathy but also reduces neovascularization. Thus, the regulatory balance between IGF and IGFBPs can have profound impact on target tissues. This review discusses recent findings of IGF and IGFBP expression in the eye with relevance to different retinopathies.

Tobacco specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone suppresses a newly identified anti-tumor IGFBP-3/IGFBP-3R system in lung cancer cells

IGFBP-3 is a tumor suppressor whose expression is frequently suppressed in lung cancer. NNK, the most potent tobacco carcinogen, enhanced cell proliferation of BEAS-2B normal lung epithelial cells and concomitantly suppressed IGFBP-3 expression through DNA methylation. Decreased IGFBP-3 expression and elevated levels of phospho-Akt, phospho-p65-NF-κB, and cyclin D1 were detected in tobacco carcinogen-induced tumorigenic derivatives of BEAS-2B. Overexpression of IGFBP-3 in NNKA, one of the derivatives, suppressed NF-κB activity and induced apoptosis, which was hindered by knocking-down of endogenous IGFBP-3R, an IGFBP-3 specific receptor. These results suggest that NNK inhibits IGFBP-3 expression to abrogate anti-tumor actions of the IGFBP-3/IGFBP-3R system in smoking-induced lung cancer.

IGF binding protein-3 mediates stress-induced apoptosis in non-transformed mammary epithelial cells

Mammary epithelial cell (MEC) number is an important determinant of milk production in lactating dairy cows. IGF-I increases IGF binding protein-3 (IGFBP-3) production in these cells, which plays a role in its ability to enhance proliferation. In the present study, we show that the apoptotic factor anisomycin (ANS) also increases IGFBP-3 mRNA and protein in a dose- and concentration-dependent manner that mirrors activation of caspase-3 and -7, with significant increases in both IGFBP-3 protein and caspase activation observed by 3 h. Knock-down of IGFBP-3 with small interfering (si) RNA attenuated the ability of ANS to induce apoptosis, while knock-down of IGFBP-2, the other major IGFBP made by bovine MEC, had no effect. Reducing IGFBP-3 also decreased the ability of ANS to induce mitochondrial cytochrome c release, indicating its involvement in the intrinsic apoptotic pathway. In contrast, transfection with IGFBP-3 in the absence of ANS failed to induce apoptosis. Since both the mitogen IGF-I and the apoptotic inducer ANS increase IGFBP-3 production in MEC, we proposed that cellular localization might determine IGFBP-3 action. While both IGF-I and ANS stimulated the release of IGFBP-3 into conditioned media, only ANS induced nuclear localization of IGFBP-3. A pan-caspase inhibitor had no effect on ANS-induced nuclear localization of IGFBP-3, indicating that nuclear entry of IGFBP-3 precedes caspase activation. Treatment with IGF-I had no effect on ANS-induced nuclear localization, but did block ANS-induced apoptosis. In summary, our data indicate that IGFBP-3 plays a role in stress-induced apoptosis that may require nuclear localization in non-transformed MEC.

Role of insulin-like growth factor binding protein-3 in 1, 25-dihydroxyvitamin-d 3 -induced breast cancer cell apoptosis

Insulin-like growth factor I (IGF-I) is implicated in breast cancer development and 1, 25-dihydroxyvitamin D₃ (1, 25-D₃) has been shown to attenuate prosurvival effects of IGF-I on breast cancer cells. In this study the role of IGF binding protein-3 (IGFBP-3) in 1, 25-D₃-induced apoptosis was investigated using parental MCF-7 breast cancer cells and MCF-7/VD^R cells, which are resistant to the growth inhibitory effects of 1, 25-D₃. Treatment with 1, 25-D₃ increased IGFBP-3 mRNA expression in both cell lines but increases in intracellular IGFBP-3 protein and its secretion were observed only in MCF-7. 1, 25-D₃-induced apoptosis was not associated with activation of any caspase but PARP-1 cleavage was detected in parental cells. IGFBP-3 treatment alone produced cleavage of caspases 7, 8, and 9 and PARP-1 in MCF-7 cells. IGFBP-3 failed to activate caspases in MCF-7/VD^R cells; however PARP-1 cleavage was detected. 1, 25-D₃ treatment inhibited IGF-I/Akt survival signalling in MCF-7 but not in MCF-7/VD^R cells. In contrast, IGFBP-3 treatment was effective in inhibiting IGF-I/Akt pathways in both breast cancer lines. These results suggest a role for IGFBP-3 in 1, 25-D₃ apoptotic signalling and that impaired secretion of IGFBP-3 may be involved in acquired resistance to vitamin D in breast cancer.

Insulin-like growth factor binding protein-3 inhibits monocyte adhesion to retinal endothelial cells in high glucose conditions

PURPOSE

Insulin-like growth factor binding protein-3 (IGFBP-3) is cytoprotective in the retina. The goal of this study was to investigate whether IGFBP-3 inhibits monocyte-endothelial cell adhesion associated with hyperglycemia.

METHODS

Human retinal vascular endothelial cells (RECs) were grown in normal (5 mM), medium (15 mM), or high glucose medium (25 mM) for 72 h. After 48 h, cells were transfected with endothelial-cell-specific, non-IGF binding IGFBP-3 plasmid DNA (IGFBP-3NB) at 1 μg/ml for 24 h. Cells were serum starved for 16 h and treated with tumor necrosis factor-alpha (TNF-α; 10 ng/ml) for 4 h. Cell proteins were extracted and analyzed for intercellular adhesion molecule-1 (ICAM-1) expression with enzyme-linked immunosorbent assay. Additional RECs were plated onto attachment factor-coated slides, grown to 90% confluence in high glucose medium, and transfected with IGFBP-3 NB plasmid DNA or ICAM-1 small interfering RNA before treatment with or without TNF-α (10 ng/ml) for 4 h. Slides were then mounted in a parallel-plate flow chamber and subjected to a continuous flow of U937 human monocytes (10(5)/ml) in culture medium at shear stresses of 2 dynes/cm(2), with continual exposure to TNF-α.

RESULTS

In high ambient glucose, overexpression of IGFBP-3 in RECs significantly decreased ICAM-1 expression when compared to the TNF-α-treated samples, whereas TNF-α increased monocyte-endothelial cell adhesion. IGFBP-3 significantly decreased monocyte adhesion to RECs in the high glucose condition. RECs transfected with ICAM-1 siRNA also had a decreased number of monocytes attached compared with the scrambled siRNA control.

CONCLUSIONS

Data suggest that IGFBP-3 reduces monocyte-endothelial cell adhesion through decreased ICAM-1 levels in a hyperglycemic environment. This is the first demonstration of the role of IGFBP-3 in inhibiting monocyte-endothelial cell adhesion.

RETRACTED: Insulin-like growth factor-binding protein-7 (IGFBP7): a promising gene therapeutic for hepatocellular carcinoma (HCC)

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the editor-in-chief. Similarities were found between images within this article. Image analysis performed by the editorial office confirmed findings of image duplication in Figures 1B, 4, and 8A. This reuse (and in part misrepresentation) of data without appropriate attribution represents a severe abuse of the scientific publishing system. No authors responded when contacted about the retraction.

IGFBP-3 inhibits cytokine-induced insulin resistance and early manifestations of atherosclerosis

Metabolic syndrome is associated with visceral obesity, insulin resistance and an increased risk of cardiovascular diseases. Visceral fat tissue primarily consists of adipocytes that secrete cytokines leading to a state of systemic inflammation in obese conditions. One of the IGF-independent functions of IGFBP-3 is its role as an anti-inflammatory molecule. Our study in obese adolescents show a decrease in total IGFBP-3 levels and increase in proteolyzed IGFBP-3 in circulation when compared to their normal counterparts and establishes a positive correlation between IGFBP-3 proteolysis and adiposity parameters as well as insulin resistance. In human adipocytes, we show that IGFBP-3 inhibits TNF-α-induced NF-κB activity in an IGF-independent manner, thereby restoring the deregulated insulin signaling and negating TNF-α-induced inhibition of glucose uptake. IGFBP-3 further inhibits TNF-α, CRP and high glucose-induced NF-κB activity in human aortic endothelial cells (HAECs) and subsequently suppresses monocyte adhesion to HAEC through the IGFBP-3 receptor. In conclusion, these findings suggest that reduced levels of IGFBP-3 in circulation and reduced expression of IGFBP-3 in macrophages in obesity may result in suppression of its anti-inflammatory functions and therefore IGFBP-3 may present itself as a therapeutic for obesity-induced insulin resistance and for events occurring in the early stages of atherosclerosis.

Insulin-like growth factor-binding protein-6 and cancer

The IGF (insulin-like growth factor) system is essential for physiological growth and it is also implicated in a number of diseases including cancer. IGF activity is modulated by a family of high-affinity IGF-binding proteins, and IGFBP-6 is distinctive because of its marked binding preference for IGF-II over IGF-I. A principal role for IGFBP-6 is inhibition of IGF-II actions, but recent studies have indicated that IGFBP-6 also has IGF-independent effects, including inhibition of angiogenesis and promotion of cancer cell migration. The present review briefly summarizes the IGF system in physiology and disease before focusing on recent studies on the regulation and actions of IGFBP-6, and its potential roles in cancer cells. Given the widespread interest in IGF inhibition in cancer therapeutics, increasing our understanding of the mechanisms underlying the actions of the IGF ligands, receptors and binding proteins, including IGFBP-6, will enhance our ability to develop optimal treatments that can be targeted to the most appropriate patients.

IGFBP-3 nuclear localization predicts human prostate cancer recurrence

Insulin-like growth factor binding protein-3 (IGFBP-3) is a pro-apoptotic, anti-metastasic, and anti-angiogenic protein. Low serum IGFBP-3 has been associated with risk of more aggressive prostate cancer (PCa). We investigated the impact of nuclear and cytoplasmic IGFBP-3 protein expression levels in PCa by examining their in situ expression across a wide spectrum of primary tumors by immunohistochemical analysis of tissue microarrays. Immunohistochemistry was performed on PCa microarrays constructed from 226 hormone naïve patients who underwent radical prostatectomy. Both cytoplasmic and nuclear IGFBP-3 expressions were scored in a semi-quantitative fashion using an integrated measure of intensity and positivity. The distribution of IGFBP-3 protein expression was examined across the spectrum of epithelial tissues, and its association with standard clinicopathological covariates and tumor recurrence was examined. There was a broad range of IGFBP-3 staining across all histologies examined. Tumor had higher IGFBP-3 cytoplasmic and nuclear staining than benign histologies. For IGFBP-3 nuclear staining, PCa was significantly different than benign prostatic hyperplasia, normal prostate, and prostate intraepithelial neoplasia. As both a continuous and dichotomized variable, higher nuclear IGFBP-3 expression had statistically significant associations with PCa recurrence. The cytoplasmic staining had no significance in any patient subgroup. In patients with low-grade cancer, IGFBP-3 nuclear positivity was a better predictor of recurrence than baseline PSA, tumor margin status, TNM tumor stage, or presence of capsular invasion. High nuclear IGFBP-3 is amongst the strongest predictors of cancer recurrence in patients with low-grade prostate cancers and may therefore play an important role in risk stratification.

Protein arginine methyltransferase 6-dependent gene expression and splicing: association with breast cancer outcomes

Protein arginine methyltransferase-6 (PRMT6) regulates steroid-dependent transcription and alternative splicing and is implicated in endocrine system development and function, cell death, cell cycle, gene expression and cancer. Despite its role in these processes, little is known about its function and cellular targets in breast cancer. To identify novel gene targets regulated by PRMT6 in breast cancer cells, we used a combination of small interfering RNA and exon-specific microarray profiling in vitro coupled to in vivo validation in normal breast and primary human breast tumours. This approach, which allows the examination of genome-wide changes in individual exon usage and total transcript levels, demonstrated that PRMT6 knockdown significantly affected i) the transcription of 159 genes and ii) alternate splicing of 449 genes. The PRMT6-dependent transcriptional and alternative splicing targets identified in vitro were validated in human breast tumours. Using the list of genes differentially expressed between normal and PRMT6 knockdown cells, we generated a PRMT6-dependent gene expression signature that provides an indication of PRMT6 dysfunction in breast cancer cells. Interrogation of several well-studied breast cancer microarray expression datasets with the PRMT6 gene expression signature demonstrated that PRMT6 dysfunction is associated with better overall relapse-free and distant metastasis-free survival in the oestrogen receptor (ER (ESR1)) breast cancer subgroup. These results suggest that dysregulation of PRMT6-dependent transcription and alternative splicing may be involved in breast cancer pathophysiology and the molecular consequences identifying a unique and informative biomarker profile.

IGFBP-3 sensitizes antiestrogen-resistant breast cancer cells through interaction with GRP78

IGFBP-3 is known to possess intrinsic biological activities such as anti-tumor property in addition to its IGF/IGF-R axis-dependent actions in a variety of human cancers including breast cancer. To investigate the molecular mechanisms underlying the intrinsic biological actions of IGFBP-3 on breast cancer cells, we performed yeast two-hybrid screening and found GRP78, known to cause drug-resistance, as a binding partner of IGFBP-3. Overexpression of IGFBP-3 in antiestrogen-resistant LCC9 cells showed that IGFBP-3 interacted with GRP78, resulting in disruption of the GRP78-caspase-7 complex, thereby activating caspase-7, and further inducing apoptosis. Combination of overexpression of IGFBP-3 and application of siRNAs against GRP78 led to decrease in cell viability upon ICI 182,780 treatment. These data suggest that IGFBP-3 could sensitize antiestrogen-resistant breast cancer cells to ICI 182,780 by preventing the anti-apoptotic function of GRP78.

Protection of blood retinal barrier and systemic vasculature by insulin-like growth factor binding protein-3

Previously, we showed that insulin growth factor (IGF)-1 binding protein-3 (IGFBP-3), independent of IGF-1, reduces pathological angiogenesis in a mouse model of the oxygen-induced retinopathy (OIR). The current study evaluates novel endothelium-dependent functions of IGFBP-3 including blood retinal barrier (BRB) integrity and vasorelaxation. To evaluate vascular barrier function, either plasmid expressing IGFBP-3 under the regulation of an endothelial-specific promoter or a control plasmid was injected into the vitreous humor of mouse pups (P1) and compared to the non-injected eyes of the same pups undergoing standard OIR protocol. Prior to sacrifice, the mice were given an injection of horseradish peroxidase (HRP). IGFBP-3 plasmid-injected eyes displayed near-normal vessel morphology and enhanced vascular barrier function. Further, in vitro IGFBP-3 protects retinal endothelial cells from VEGF-induced loss of junctional integrity by antagonizing the dissociation of the junctional complexes. To assess the vasodilatory effects of IGFBP-3, rat posterior cerebral arteries were examined in vitro. Intraluminal IGFBP-3 decreased both pressure- and serotonin-induced constrictions by stimulating nitric oxide (NO) release that were blocked by L-NAME or scavenger receptor-B1 neutralizing antibody (SRB1-Ab). Both wild-type and IGF-1-nonbinding mutant IGFBP-3 (IGFBP-3NB) stimulated eNOS activity/NO release to a similar extent in human microvascular endothelial cells (HMVECs). NO release was neither associated with an increase in intracellular calcium nor decreased by Ca²⁺/calmodulin-dependent protein kinase II (CamKII) blockade; however, dephosphorylation of eNOS-Thr⁴⁹⁵ was observed. Phosphatidylinositol 3-kinase (PI3K) activity and Akt-Ser⁴⁷³ phosphorylation were both increased by IGFBP-3 and selectively blocked by the SRB1-Ab or PI3K blocker LY294002. In conclusion, IGFBP-3 mediates protective effects on BRB integrity and mediates robust NO release to stimulate vasorelaxation via activation of SRB1. This response is IGF-1- and calcium-independent, but requires PI3K/Akt activation, suggesting that IGFBP-3 has novel protective effects on retinal and systemic vasculature and may be a therapeutic candidate for ocular complications such as diabetic retinopathy.

Homeobox D10 gene, a candidate tumor suppressor, is downregulated through promoter hypermethylation and associated with gastric carcinogenesis

Homeobox D10 (HoxD10 ) gene plays a critical role in cell differentiation and morphogenesis during development. However, the function of HoxD10 in tumor progression remains largely unknown. We demonstrate that the expression of HoxD10 is commonly downregulated in gastric cancer tissues (n = 33) and cell lines (n = 8) relative to normal stomach tissues. Functionally, reexpression of HoxD10 results in significant inhibition of cell survival, induction of cell apoptosis, and impairment of cell migration and invasion. Moreover, ectopic expression of HoxD10 suppresses gastric tumor growth in a mouse xenograft model. To identify target candidates of HoxD10, we performed cDNA microarray and showed that HoxD10 regulates multiple downstream genes including IGFBP3. Reintroduction of HoxD10 transcriptionally upregulates IGFBP3, activates caspase 3 and caspase 8, and subsequently induces cell apoptosis. Methylation specific PCR revealed that HoxD10 promoter DNA was hypermethylated in gastric cancer cell lines. Additionally, 5-aza demethylation treatment could transiently reactivate the expression of HoxD10 in gastric cancer cells. HoxD10 promoter methylation frequently was detected in gastric cancer tissues obtained from endoscopic biopsies (85.7%, 24/28) and surgically resected samples (82.6%, 57/69). Intestinal metaplasia tissues showed a 60% methylation rate (18/30), but no detectable methylation in normal stomach tissues (0%, 0/10). Taken together, our results suggest that HoxD10 functions as a candidate tumor suppressor in gastric cancer, which is inactivated through promoter hypermethylation.

Importance of metabolic changes induced by chemotherapy on prognosis of early-stage breast cancer patients: a review of potential mechanisms

Weight variation has been reported as a side effect of chemotherapy treatment in early breast cancer patients and has been identified as a factor of poor prognosis. Causes of weight variation during chemotherapy and mechanisms involved in the poor prognosis have been little studied. Here is reviewed the current knowledge about the main causes and mechanisms involved in body weight change. Special emphasis is placed on factors associated with weight variation which could potentially be involved in the risk of relapse in breast cancer survivors. In recent decades, some studies have investigated the causes of weight variation by studying energy balance of breast cancer patients during chemotherapy. Weight gain or loss may be the consequence of energy imbalance through different factors linked with chemotherapy, such as poor treatment tolerance, decreased muscle mass and function, or hormonal alterations. This results in body composition modifications in favour of fat gain and/or lean body mass loss. Increased adipose tissue, especially in the abdominal region, could induce metabolic disturbances such as insulin resistance, through various pathways involving adipokines. These molecules have growth properties and could therefore play a role in cancer relapse. Understanding such mechanisms is key to developing preventive strategies for improving the prognosis of early-stage breast cancer patients.

The insulin-like growth factor system in chronic kidney disease: Pathophysiology and therapeutic opportunities

The growth hormone-insulin-like growth factor-insulin-like growth factor binding protein (GH-IGF-IGFBP) axis plays a critical role in the maintenance of normal renal function and the pathogenesis and progression of chronic kidney disease (CKD). Serum IGF-I and IGFBPs are altered with different stages of CKD, the speed of onset, the amount of proteinuria, and the potential of remission. Recent studies demonstrate that growth failure in children with CKD is due to a relative GH insensitivity and functional IGF deficiency. The functional IGF deficiency in CKD results from either IGF resistance due to increased circulating levels of IGFBPs or IGF deficiency due to increased urinary excretion of serum IGF-IGFBP complexes. In addition, not only GH and IGFs in circulation, but locally produced IGFs, the high-affinity IGFBPs, and low-affinity insulin-like growth factor binding protein-related proteins (IGFBP-rPs) may also affect the kidney. With respect to diabetic kidney disease, there is growing evidence suggesting that GH, IGF-I, and IGFBPs are involved in the pathogenesis of diabetic nephropathy (DN). Thus, prevention of GH action by blockade either at the receptor level or along its signal transduction pathway offers the potential for effective therapeutic opportunities. Similarly, interrupting IGF-I and IGFBP actions also may offer a way to inhibit the development or progression of DN. Furthermore, it is well accepted that the systemic inflammatory response is a key player for progression of CKD, and how to prevent and treat this response is currently of great interest. Recent studies demonstrate existence of IGF-independent actions of high-affinity and low-affinity-IGFBPs, in particular, antiinflammatory action of IGFBP-3 and profibrotic action of IGFBP-rP2/CTGF. These findings reinforce the concept in support of the clinical significance of the IGF-independent action of IGFBPs in the assessment of pathophysiology of kidney disease and its therapeutic potential for CKD. Further understanding of GH-IGF-IGFBP etiopathophysiology in CKD may lead to the development of therapeutic strategies for this devastating disease. It would hold promise to use of GH, somatostatin analogs, IGFs, IGF agonists, GHR and insulin-like growth factor-I receptor (IGF-IR) antagonists, IGFBP displacer, and IGFBP antagonists as well as a combination treatment as therapeutic agents for CKD.

Preoperative insulin-like growth factor-binding protein-3 (IGFBP-3) blood level predicts gleason sum upgrading

BACKGROUND

About 43% of men with low Gleason grade prostate cancer (PCa) at biopsy will be finally diagnosed with high-grade PCa at radical prostatectomy (RP). Gleason sum at RP is a good indicator of biochemical recurrence and poor clinical outcome. Therefore, there is a need to improve clinical evaluation of PCa aggressiveness in order to choice appropriate treatment. To this aim an easy-available tool is represented by circulating biomarkers. Among these, the best candidates are some molecules involved in PCa pathogenesis such as IGFBP-2 and IGFBP-3, IL-6, and its soluble receptor (SIL-6R).

METHODS

In this study, we evaluated the ability of preoperative IGFBP-2, IGFBP-3, IL-6, and SIL-6R serum levels to predict Gleason score upgrade in 52 PCa patients.

RESULTS

We found that IGFBP-3 median levels were significantly lower in patients who showed Gleason upgrading from biopsy to RP (P = 0.024). We also found an association between biopsy T-stage and Gleason Upgrade (P = 0.011). Using multivariate logistic regression model, we demonstrated that the association of IGFBP-3 serum levels together with biopsy T-stage and biopsy Gleason score was useful to calculate a prognostic risk score. ROC curve analysis of risk score showed a good ability to predict GSU (AUC = 0.81; 95% CI 0.69-0.93).

CONCLUSIONS

Our results suggest that preoperative IGFBP-3 circulating levels determination may be useful to predict Gleason score upgrading alone and/or in combination with biopsy T-stage and biopsy Gleason score.

Insulin-like growth factor: current concepts and new developments in cancer therapy

The insulin-like growth factor (IGF) family and the IGF-1 receptor (IGF-1R) play an important role in cancer. This intricate and complex signaling pathway provides many opportunities for therapeutic intervention, and several novel therapeutics aimed at the IGF-1R, particularly monoclonal antibodies and small molecule tyrosine kinase inhibitors, are under clinical investigation. This article provides a patent overview of the IGF signaling pathway and its complexity, addresses the justification for the use of IGF-1R-targeted therapy, and reviews the results of in vivo and in vitro novel therapeutics. Over the past year, the completion of several phase I, II, and III trials have provided interesting new information about the clinical activity of these novel compounds, particularly CP-751,871, IMC-A12, R1507, AMG-479, AVE-1642, MK-0646, XL-228, OSI-906, and BMS-754807. We review the important preliminary results from clinical trials with these compounds and conclude with a discussion about future therapeutic efforts.

Signalling pathways of insulin-like growth factors (IGFs) and IGF binding protein-3

Although the insulin-like growth factor (IGF) system is essential for normal growth and development, its dysregulation has been implicated in a range of pathological states. The peptide growth factors IGF-I and IGF-II exert their effects by binding to cell-surface heterotetrameric tyrosine kinase receptors and activating multiple intracellular signalling cascades, leading to changes in the expression of proteins essential for cell proliferation, survival and differentiation. The IGF system comprises multiple ligands, receptors and high-affinity IGF binding proteins (IGFBPs), with added complexity arising from crosstalk between its receptors and other key growth-regulatory pathways such as those activated by steroid hormones, integrins and other receptor tyrosine kinases. The IGFBPs are also increasingly recognised for their intrinsic growth-regulatory activity, and the ability of IGFBP-3 to modulate signalling pathways of nuclear hormone and growth factor receptors, as well as novel receptors, is believed to play a role both in normal physiology and in disease.

IGFBP7 reduces breast tumor growth by induction of senescence and apoptosis pathways

Insulin-like growth factor binding protein 7 (IGFBP7) has been shown to be a tumor suppressor in a variety of cancers. We previously have shown that IGFBP7 expression is inversely correlated with disease progression and poor outcome in breast cancer. Overexpression of IGFBP7 in MDA-MB-468, a triple-negative breast cancer (TNBC) cell line, resulted in inhibition of growth and migration. Xenografted tumors bearing ectopic IGFBP7 expression were significantly growth-impaired compared to IGFBP7-negative controls, which suggested that IGFBP7 treatment could inhibit breast cancer cell growth. To confirm this notion, 14 human patient primary breast tumors were analyzed by qRTPCR for IGFBP7 expression. The TNBC tumors expressed the lowest levels of IGFBP7 expression, which also correlated with higher tumorigenicity in mice. Furthermore, when breast cancer cell lines were treated with IGFBP7, only the TNBC cell lines were growth inhibited. Treatment of NOD/SCID mice harboring xenografts of TNBC cells with IGFBP7 systemically every 3-4 days inhibited tumorigenesis, with associated anti-angiogenic effects, together with increased apoptosis. Upon examining the mechanism of IGFBP7-mediated growth inhibition in TNBC cells, we found that cells not only were arrested in G1 phase of the cell cycle but also underwent senescence as a result of treatment with IGFBP7. Interestingly, IGFBP7 treatment was also associated with strong activation of the stress-associated p38 MAPK pathway, together with upregulation of p53 and the cyclin-dependent protein kinase (CDK) inhibitor, p21(cip1). Prolonged treatment of cells with IGFBP7 resulted in increased cell death, marked by an increase in apoptotic cells and associated cleaved PARP. This is the first study showing that exogenous IGFBP7 inhibits TNBC cell growth both in vitro and in vivo. Taken together, these results suggest IGFBP7 treatment might have therapeutic potential for TNBC.

The link between the metabolic syndrome and cancer

Since the incidence of the metabolic syndrome is on the rise in the western world, its coherence to cancer is becoming more apparent. In this review we discuss the different potential factors involved in the increase of cancer in the metabolic syndrome including obesity, dyslipidemia and Type 2 Diabetes Mellitus (T2DM) as well as inflammation and hypoxia. We especially focus on the insulin and IGF systems with their intracellular signaling cascades mediated by different receptor subtypes, and suggest that they may play major roles in this process. Understanding the mechanisms involved will be helpful in developing potential therapeutics.

Novel protective properties of IGFBP-3 result in enhanced pericyte ensheathment, reduced microglial activation, increased microglial apoptosis, and neuronal protection after ischemic retinal injury

This study was conducted to determine the perivascular cell responses to increased endothelial cell expression of insulin-like growth factor binding protein-3 (IGFBP-3) in mouse retina. The contribution of bone marrow cells in the IGFBP-3-mediated response was examined using green fluorescent protein-positive (GFP(+)) adult chimeric mice subjected to laser-induced retinal vessel occlusion injury. Intravitreal injection of an endothelial-specific IGFBP-3-expressing plasmid resulted in increased differentiation of GFP(+) hematopoietic stem cells (HSCs) into pericytes and astrocytes as determined by immunohistochemical analysis. Administration of IGFBP-3 plasmid to mouse pups that underwent the oxygen-induced retinopathy model resulted in increased pericyte ensheathment and reduced pericyte apoptosis in the developing retina. Increased IGFBP-3 expression reduced the number of activated microglial cells and decreased apoptosis of neuronal cells in the oxygen-induced retinopathy model. In summary, IGFBP-3 increased differentiation of GFP(+) HSCs into pericytes and astrocytes while increasing vascular ensheathment of pericytes and decreasing apoptosis of pericytes and retinal neurons. All of these cytoprotective effects exhibited by IGFBP-3 overexpression can result in a more stable retinal vascular bed. Thus, endothelial expression of IGFBP-3 may represent a physiologic response to injury and may represent a therapeutic strategy for the treatment of ischemic vascular eye diseases, such as diabetic retinopathy and retinopathy of prematurity.

Antiangiogenic antitumor activities of IGFBP-3 are mediated by IGF-independent suppression of Erk1/2 activation and Egr-1-mediated transcriptional events

Most antiangiogenic therapies currently being evaluated in clinical trials target the vascular endothelial growth factor pathway; however, the tumor vasculature can acquire resistance to vascular endothelial growth factor-targeted therapy by shifting to other angiogenesis mechanisms. Insulin-like growth factor binding protein-3 (IGFBP-3) has been reported to suppress tumor growth and angiogenesis by both IGF-dependent and IGF-independent mechanisms; however, understanding of its IGF-independent mechanisms is limited. We observed that IGFBP-3 blocked tumor angiogenesis and growth in non-small cell lung cancer and head and neck squamous cell carcinoma. Conditioned media from an IGFBP-3-treated non-small cell lung cancer cell line displayed a significantly decreased capacity to induce HUVEC proliferation and aortic sprouting. In cancer cells, IGFBP-3 directly interacted with Erk1/2, leading to inactivation of Erk1/2 and Elk-1, and suppressed transcription of early growth response protein 1 and its target genes, basic fibroblast growth factor and platelet-derived growth factor. These data suggest that IGF-independent Erk1/2 inactivation and decreased IGFBP-3-induced Egr-1 expression block the autocrine and paracrine loops of angiogenic factors in vascular endothelial and cancer cells. Together, these findings provide a molecular framework of IGFBP-3's IGF-independent antiangiogenic antitumor activities. Future studies are needed for development of IGFBP-3 as a new line of antiangiogengic cancer drug.

Insulin-like growth factor-binding protein-3 suppresses tumor growth via activation of caspase-dependent apoptosis and cross-talk with NF-κB signaling

Nuclear factor-kappaB (NF-κB) is constitutively activated in a variety of human cancers including prostate cancer and involved in tumorigenesis, tumor progression and chemo-resistance. Insulin-like growth factor-binding protein-3 (IGFBP-3) is a potent tumor suppressor and is significantly suppressed in a variety of cancers. Diverse biological effects of IGFBP-3 have been reported to be both dependent and independent of the IGF/IGF-I receptor (IGF-IR) axis. The precise underlying mechanisms of IGF/IGF-IR-independent, antiproliferative actions of IGFBP-3 are yet to be elucidated. We found an inverse correlation between NF-κB activity and IGFBP-3 expression during prostate cancer progression using an in vitro prostate cancer progression model. Restoration of IGFBP-3 resulted in significant inhibition of constitutively elevated NF-κB activity in prostate cancer cells. IGFBP-3 further inhibited the expression of NF-κB-regulated angiogenic factors such as VEGF and IL-8, and cell adhesion molecules, ICAM-1 and VCAM-1. This inhibitory action of IGFBP-3 was IGF/IGF-IR-independent since IGFBP-3 mutant devoid of IGF binding affinity had a similar inhibitory effect. We identified that IGFBP-3 degrades the key NF-κB regulatory molecules-IκBα and p65-NF-κB proteins through activation of caspase-8 and -3/-7, thereby inhibiting elevated NF-κB activity in prostate cancer. Finally intratumoral administration of IGFBP-3 resulted in significant tumor suppression as well as sensitization of antitumor effect of doxorubicin. Our findings indicate that IGFBP-3 exerts antitumor effects via IGF-independent mechanisms which involve activation of caspase-dependent apoptosis and cross-talk with NF-κB signaling. The use of IGFBP-3 as a cancer therapeutic with this distinctive suppression mechanism may offer alternate means to treat chemotherapy resistant tumors.

Insulin-like growth factor-binding protein-3 (IGFBP-3) blocks the effects of asthma by negatively regulating NF-κB signaling through IGFBP-3R-mediated activation of caspases

Insulin-like growth factor-binding protein-3 (IGFBP-3) is a multifunctional protein known for modulating mitogenic and metabolic actions of IGFs as well as exerting a variety of biological actions not involving IGFs. Here, we show that IGFBP-3 blocks specific physiological consequences of asthma in an IGF-independent manner in vitro and in vivo. IGFBP-3 treatment effectively reduced all physiological manifestations of asthma examined in vivo (airway hyper-responsiveness, cellular and pathological changes in bronchoalveolar lavage fluid and lung tissue, and expression of numerous proinflammatory molecules). These unique IGFBP-3 effects were further confirmed in IGFBP-3-transgenic mice, thus strengthening the notion of IGFBP-3 actions within the respiratory system. Using human epithelial cells, we demonstrated the following: 1) IGFBP-3 blocks TNF-α-induced expression of proinflammatory molecules; 2) IGFBP-3 attenuates the TNF-α-induced migratory response of eosinophils; and 3) IGFBP-3 negatively regulates TNF-α-induced expression of the key NF-κB regulatory molecules IκBα and p65-NF-κB at the post-translational level. We identified that IGFBP-3 degrades IκBα and p65-NF-κB proteins through IGFBP-3 receptor (IGFBP-3R)-mediated activation of caspases thereby inhibiting TNF-α-induced activation of NF-κB signaling cascades. This unique IGFBP-3/IGFBP-3R action was further confirmed by demonstrating complete inhibition of IGFBP-3 action in the presence of caspase inhibitors as well as IGFBP-3R siRNAs. Non-IGF-binding IGFBP-3 mutants further proved the IGF-independent action of IGFBP-3. Our findings indicate that IGFBP-3 inhibits airway inflammation and hyper-responsiveness via an IGF-independent mechanism that involves activation of IGFBP-3R signaling and cross-talk with NF-κB signaling. The IGFBP-3/IGFBP-3R system therefore plays a pivotal role in the pathogenesis of asthma and can serve as a newly identified potential therapeutic target for this debilitating disease.

Intrinsic, Pro-Apoptotic Effects of IGFBP-3 on Breast Cancer Cells are Reversible: Involvement of PKA, Rho, and Ceramide

We established previously that IGFBP-3 could exert positive or negative effects on cell function depending upon the extracellular matrix composition and by interacting with integrin signaling. To elicit its pro-apoptotic effects IGFBP-3 bound to caveolin-1 and the beta 1 integrin receptor and increased their association culminating in MAPK activation. Disruption of these complexes or blocking the beta 1 integrin receptor reversed these intrinsic actions of IGFBP-3. In this study we have examined the signaling pathway between integrin receptor binding and MAPK activation that mediates the intrinsic, pro-apoptotic actions of IGFBP-3. We found on inhibiting protein kinase A (PKA), Rho associated kinase (ROCK), and ceramide, the accentuating effects of IGFBP-3 on apoptotic triggers were reversed, such that IGFBP-3 then conferred cell survival. We established that IGFBP-3 activated Rho, the upstream regulator of ROCK and that beta1 integrin and PKA were upstream of Rho activation, whereas the involvement of ceramide was downstream. The beta 1 integrin, PKA, Rho, and ceramide were all upstream of MAPK activation. These data highlight key components involved in the pro-apoptotic effects of IGFBP-3 and that inhibiting them leads to a reversal in the action of IGFBP-3.