Intrathecal IGF2 siRNA injection provides long-lasting anti-allodynic effect in a spared nerve injury rat model of neuropathic pain.

Previous studies have shown an increase of insulin-like growth factor-2 (IGF2) in animal models of neuropathic pain. We aimed to examine the hypothesis that reducing the expression of IGF2 using intrathecal IGF2 small-interfering RNA (siRNA) would attenuate the development of neuropathic pain in rats after spared nerve injury (SNI). Male Wistar rats were divided into three groups: sham-operated group, in which surgery was performed to cut the muscles without injuring the nerves; SNI group, in which SNI surgery was performed to sever the nerves; and SNI + siRNA IGF2 group, in which SNI surgery was performed, and IGF2-siRNA was administered intrathecally 1 day after SNI. The rats were assessed for mechanical allodynia and cold allodynia 1 day before surgery (baseline), and at 2, 4, 6, 8, and 10 days after siRNA treatment. The rat spinal cord was collected for quantitative polymerase chain reaction and western blot analysis. Compared with the SNI group, rats that received IGF2 siRNA showed a significantly increased SNI-induced paw-withdrawal threshold to metal filament stimulation from Day 4 to Day 10 after SNI surgery. IGF2 siRNA significantly decreased the response duration from the acetone test from Day 2 to Day 10 following SNI surgery. SNI increased IGF2 mRNA expression on Day 2 and increased IGF2 protein expression on Day 8 and Day 10 in the spinal cord of the SNI rats. However, the above-mentioned effects of IGF2 mRNA and protein expression were significantly inhibited in the SNI + IGF2 siRNA group. We demonstrated that intrathecal administration of IGF2 siRNA provided significant inhibition of SNI-induced neuropathic pain via inhibition of IGF2 expression in the spinal cord. The analgesic effect lasted for 10 days. Further exploration of intrathecal IGF2 siRNA administration as a potential therapeutic strategy for neuropathic pain is warranted.

M2­like tumour­associated macrophage­secreted IGF promotes thyroid cancer stemness and metastasis by activating the PI3K/AKT/mTOR pathway.

M2­like tumour­associated macrophages (TAMs) have been demonstrated to promote the growth of anaplastic thyroid carcinoma (ATC). However, the underlying mechanism of M2­like TAMs in ATC remains unclear. Thus, in the present study, the role and mechanism of M2­like TAMs in ATC were investigated. M2­like TAMs were induced by treatment with PMA, plus IL­4 and IL­13, and identified by flow cytometry. Transwell and sphere formation assays were applied to assess the invasion and stemness of ATC cells. The expression levels of insulin­like growth factor (IGF)­1 and IGF­2 were examined by ELISA and reverse transcription­quantitative PCR. Proteins related to the epithelial­mesenchymal transition (EMT), stemness and the PI3K/AKT/mTOR pathway were examined via western blotting. Immunohistochemistry (IHC) was used to detect the expression of the M2­like TAM markers CD68 and CD206 in ATC tissues and thyroid adenoma tissues. It was found that treatment with PMA plus IL­4 and IL­13 successfully induced M2­like TAMs. Following co­culture with M2­like TAMs, the invasive ability and stemness of ATC cells were significantly increased. The expression levels of the EMT­related markers N­cadherin and Vimentin, the stemness­related markers Oct4, Sox2 and CD133, and the insulin receptor (IR)­A/IGF1 receptor (IGF1R) were markedly upregulated, whereas E­cadherin expression was significantly decreased. In addition, the production of IGF­1 and IGF­2 was significantly increased. Of note, exogenous IGF­1/IGF­2 promoted the invasion and stemness of C643 cells, whereas blocking IGF­1 and IGF­2 inhibited metastasis and stemness by repressing IR­A/IGF­1R­mediated PI3K/AKT/mTOR signalling in the co­culture system. IHC results showed that the expression of CD68 and CD206 was obviously increased in ATC tissues. To conclude, M2­like TAMs accelerated the metastasis and increased the stemness of ATC cells, and the underlying mechanism may be related to the section of IGF by M2­like TAMs, which activates the IR­A/IGF1R­mediated PI3K/AKT/mTOR signalling pathway.

Two first-in-human studies of xentuzumab, a humanised insulin-like growth factor (IGF)-neutralising antibody, in patients with advanced solid tumours.

BACKGROUND: Xentuzumab, an insulin-like growth factor (IGF)-1/IGF-2-neutralising antibody, binds IGF-1 and IGF-2, inhibiting their growth-promoting signalling. Two first-in-human trials assessed the maximum-tolerated/relevant biological dose (MTD/RBD), safety, pharmacokinetics, pharmacodynamics, and activity of xentuzumab in advanced/metastatic solid cancers. METHODS: These phase 1, open-label trials comprised dose-finding (part I; 3 + 3 design) and expansion cohorts (part II; selected tumours; RBD [weekly dosing]). Primary endpoints were MTD/RBD. RESULTS: Study 1280.1 involved 61 patients (part I: xentuzumab 10-1800 mg weekly, n = 48; part II: 1000 mg weekly, n = 13); study 1280.2, 64 patients (part I: 10-3600 mg three-weekly, n = 33; part II: 1000 mg weekly, n = 31). One dose-limiting toxicity occurred; the MTD was not reached for either schedule. Adverse events were generally grade 1/2, mostly gastrointestinal. Xentuzumab showed dose-proportional pharmacokinetics. Total plasma IGF-1 increased dose dependently, plateauing at ~1000 mg/week; at ≥450 mg/week, IGF bioactivity was almost undetectable. Two partial responses occurred (poorly differentiated nasopharyngeal carcinoma and peripheral primitive neuroectodermal tumour). Integration of biomarker and response data by Bayesian Logistic Regression Modeling (BLRM) confirmed the RBD. CONCLUSIONS: Xentuzumab was well tolerated; MTD was not reached. RBD was 1000 mg weekly, confirmed by BLRM. Xentuzumab showed preliminary anti-tumour activity. CLINICAL TRIAL REGISTRATION: NCT01403974; NCT01317420.

Antitumor Activity of the IGF-1/IGF-2-Neutralizing Antibody Xentuzumab (BI 836845) in Combination with Enzalutamide in Prostate Cancer Models.

Androgen deprivation therapy and second-generation androgen receptor signaling inhibitors such as enzalutamide are standard treatments for advanced/metastatic prostate cancer. Unfortunately, most men develop resistance and relapse; signaling via insulin-like growth factor (IGF) has been implicated in castration-resistant prostate cancer. We evaluated the antitumor activity of xentuzumab (IGF ligand-neutralizing antibody), alone and in combination with enzalutamide, in prostate cancer cell lines (VCaP, DuCaP, MDA PCa 2b, LNCaP, and PC-3) using established in vitro assays, and in vivo, using LuCaP 96CR, a prostate cancer patient-derived xenograft (PDX) model. Xentuzumab + enzalutamide reduced the viability of phosphatase and tensin homolog (PTEN)-expressing VCaP, DuCaP, and MDA PCa 2b cells more than either single agent, and increased antiproliferative activity and apoptosis induction in VCaP. Xentuzumab or xentuzumab + enzalutamide inhibited IGF type 1 receptor and AKT serine/threonine kinase (AKT) phosphorylation in VCaP, DuCaP, and MDA PCa 2b cells; xentuzumab had no effect on AKT phosphorylation and proliferation in PTEN-null LNCaP or PC-3 cells. Knockdown of PTEN led to loss of antiproliferative activity of xentuzumab and reduced activity of xentuzumab + enzalutamide in VCaP cells. Xentuzumab + enzalutamide inhibited the growth of castration-resistant LuCaP 96CR PDX with acquired resistance to enzalutamide, and improved survival in vivo The data suggest that xentuzumab + enzalutamide combination therapy may overcome castration resistance and could be effective in patients who are resistant to enzalutamide alone. PTEN status as a biomarker of responsiveness to combination therapy needs further investigation.

MiR-210-3p attenuates lipid accumulation and inflammation in atherosclerosis by repressing IGF2.

Previous studies have shown that miR-210-3p is involved in the development and progression of atherosclerosis, but its specific mechanisms are still unclear. This study aims to reveal the mechanism of miR-210-3p and its target genes in macrophage lipid deposition and inflammatory response, and provide new ideas for the treatment of atherosclerosis. We found miR-210-3p increased sharply in the first 12 h induced by higher doses of ox-LDL in THP-1 macrophages and then gradually decreased. MiR-210-3p mimic transfection inhibited lipid uptake and inflammatory cytokine production in ox-LDL-induced macrophages. By inhibiting IGF2/IGF2R, miR-210-3p suppressed the expression of fatty acid transcriptase CD36 and transcription factor NF-κB in ox-LDL-induced macrophages. In conclusion, miR-210-3p inhibits the expression of CD36 and NF-κB by inhibiting IGF2 / IGF2R, thereby reducing lipid accumulation and inflammatory response in ox-LDL-induced macrophages. Enhancing miR-210-3p expression may be a new strategy for the treatment of atherosclerosis.

IGF-2 Preprograms Maturing Macrophages to Acquire Oxidative Phosphorylation-Dependent Anti-inflammatory Properties.

Recent investigations revealed that macrophages could be trained with an altered responsiveness, raising the possibility of combating autoimmune diseases by imparting anti-inflammatory capabilities to these cells. While investigating the effect of mesenchymal stem cells on experimental autoimmune encephalomyelitis (EAE), we found a critical role of insulin-like growth factor 2 (IGF-2) in training macrophages to become anti-inflammatory during their maturation. IGF-2 exerts its effects by preprogramming maturing macrophages to commit oxidative phosphorylation (OXPHOS). IGF-2-preprogrammed macrophages maintained the mitochondrial complex V activities even upon pro-inflammation stimulation, thus enabling an elevated programmed death-ligand 1 (PD-L1) expression. PD-L1 neutralization abolished the beneficial effect of IGF-2 on EAE. Furthermore, adoptive transfer of IGF-2-preprogrammed macrophages to EAE mice increased Tregs and alleviated the diseases. Our results demonstrate that shaping macrophage responsiveness by IGF-2 is effective in managing inflammatory diseases, and the OXPHOS commitment can be preset to determine the anti-inflammatory fate of macrophages.

Immune targeting of autocrine IGF2 hampers rhabdomyosarcoma growth and metastasis.

BACKGROUND: Insulin-like Growth Factor Receptor-1 (IGF1R) system sustains the genesis of rhabdomyosarcoma through IGF2 autocrine overexpression. While several IGF1R-targeted strategies have been investigated to interphere with rhabdomyosarcoma growth, no attempt to neutralize IGF2 has been reported. We therefore studied the possibility to hamper rhabdomyosarcoma growth with passive and active immune approaches targeting IGF2. METHODS: A murine model developing IGF2-overexpressing pelvic rhabdomyosarcoma, along with IGF2-independent salivary carcinoma, was used to investigate the efficacy and specificity of passive anti-IGFs antibody treatment. Active vaccinations with electroporated DNA plasmids encoding murine or human IGF2 were performed to elicit autochthonous anti-IGF2 antibodies. Vaccinated mice received the intravenous injection of rhabdomyosarcoma cells to study the effects of anti-IGF2 antibodies against developing metastases. RESULTS: Passive administration of antibodies neutralizing IGFs delayed the onset of IGF2-overexpressing rhabdomyosarcoma but not of IGF2-independent salivary carcinoma. A DNA vaccine against murine IGF2 did not elicit antibodies, even when combined with Treg-depletion, while a DNA vaccine encoding the human IGF2 gene elicited antibodies crossreacting with murine IGF2. Mice with anti-IGF2 antibodies were partially protected against the metastatic growth of IGF2-addicted rhabdomyosarcoma cells. CONCLUSIONS: Immune targeting of autocrine IGF2 inhibited rhabdomyosarcoma genesis and metastatic growth.

MicroRNA 615-3p Inhibits the Tumor Growth and Metastasis of NSCLC via Inhibiting IGF2.

MicroRNAs are essential regulators of cancer-associated genes at the posttranscriptional level, and their expression is altered in cancer tissues. Herein we sought to identify the regulation of miR-615-3p in NSCLC progression and its mechanism. miR-615-3p expression was significantly downregulated in NSCLC tissue compared to control normal tissue. Exogenous overexpression of miR-615-3p inhibited the growth and metastasis of NSCLC cells. In addition, the in vivo mouse xenograft model showed that overexpression of miR-615-3p inhibited NSCLC growth and lung metastasis, whereas decreased expression of miR-615-3p caused an opposite outcome. Furthermore, we revealed that insulin-like growth factor 2 (IGF2) expression was negatively correlated with the miR-615-3p level in NSCLC specimens, and IGF2 knockdown mimicked the effect of miR-615-3p inhibition on NSCLC cell proliferation, migration, and invasion. In addition, overexpression of IGF2 rescued the inhibition of miR-615-3p in NSCLC cells. Together, our results indicated that miR-615-3p played important roles in the regulation of NSCLC growth and metastasis by targeting IGF2.

microRNA­3941 targets IGF2 to control LPS­induced acute pneumonia in A549 cells.

The present study aimed to investigate the potential roles and regulatory mechanism of microRNA (miR)-3941 in lipopolysaccharides (LPS)­induced acute pneumonia. The expression of miR­3941 in child patients with acute pneumonia was detected and A549 cells were treated with LPS to establish the cellular model of acute pneumonia. The effects of miR­3941 in LPS­induced cell injury were investigated by assessing cell viability, apoptosis and inflammation. In addition, the regulatory relationship between miR­3941 and insulin­like growth factor 2 (IGF2) was explored, as well as the association between miR­3941 and the phosphatidylinositol­4,5­bisphosphate 3­kinase/protein kinase B (PI3K/AKT) pathway. miR­3941 was significantly down­regulated in patients with acute pneumonia (P<0.01). In the cell model of acute pneumonia, LPS treatment significantly induced cell injury via inhibiting cell viability (P<0.05 or P<0.01), inducing cell apoptosis (P<0.01) and enhancing the production of cytokines [interleukin (IL)­6, IL­8 and tumor necrosis factor­α; P<0.01 or P<0.001]. LPS treatment also resulted in a significantly decreased expression of miR­3941 in A549 cells (P<0.01) and the overexpression of miR­3941 significantly alleviated LPS­induced cell injury (P<0.05). In addition, IGF2 was confirmed as a direct target gene of miR­3941. Knockdown of IGF2 significantly alleviated LPS­induced cell injury (P<0.05, P<0.01 or P<0.001), which was significantly reversed by suppression of miR­3941 (P<0.05, P<0.01 or P<0.001). Furthermore, inhibition of miR­3941 was demonstrated to activate the PI3K/AKT pathway, which was inhibited following knockdown of IGF2. The present study indicates that miR­3941 is downregulated in child patients with acute pneumonia and that downregulation of miR­3941 may promote LPS­induced cell injury in A549 cells via targeting IGF2 to regulate the activation of the PI3K/AKT pathway. Therefore, miR­3941 may be a potential therapeutic target for the treatment of acute pneumonia in child patients.

The IGF1R/INSR Inhibitor BI 885578 Selectively Inhibits Growth of IGF2-Overexpressing Colorectal Cancer Tumors and Potentiates the Efficacy of Anti-VEGF Therapy.

Clinical studies of pharmacologic agents targeting the insulin-like growth factor (IGF) pathway in unselected cancer patients have so far demonstrated modest efficacy outcomes, with objective responses being rare. As such, the identification of selection biomarkers for enrichment of potential responders represents a high priority for future trials of these agents. Several reports have described high IGF2 expression in a subset of colorectal cancers, with focal IGF2 amplification being responsible for some of these cases. We defined a novel cut-off value for IGF2 overexpression based on differential expression between colorectal tumors and normal tissue samples. Analysis of two independent colorectal cancer datasets revealed IGF2 to be overexpressed at a frequency of 13% to 22%. An in vitro screen of 34 colorectal cancer cell lines revealed IGF2 expression to significantly correlate with sensitivity to the IGF1R/INSR inhibitor BI 885578. Furthermore, autocrine IGF2 constitutively activated IGF1R and Akt phosphorylation, which was inhibited by BI 885578 treatment. BI 885578 significantly delayed the growth of IGF2-high colorectal cancer xenograft tumors in mice, while combination with a VEGF-A antibody increased efficacy and induced tumor regression. Besides colorectal cancer, IGF2 overexpression was detected in more than 10% of bladder carcinoma, hepatocellular carcinoma and non-small cell lung cancer patient samples. Meanwhile, IGF2-high non-colorectal cancer cells lines displayed constitutive IGF1R phosphorylation and were sensitive to BI 885578. Our findings suggest that IGF2 may represent an attractive patient selection biomarker for IGF pathway inhibitors and that combination with VEGF-targeting agents may further improve clinical outcomes. Mol Cancer Ther; 16(10); 2223-33. ©2017 AACR.

Curcumin inhibits urothelial tumor development by suppressing IGF2 and IGF2-mediated PI3K/AKT/mTOR signaling pathway.

We have previously reported that curcumin inhibits urothelial tumor development in a rat bladder carcinogenesis model. In this study, we report that curcumin inhibits urothelial tumor development by suppressing IGF2 and IGF2-mediated PI3K/AKT/mTOR signaling pathway. Curcumin inhibits IGF2 expression at the transcriptional level and decreases the phosphorylation levels of IGF1R and IRS-1 in bladder cancer cells and N-methyl-N-nitrosourea (MNU)-induced urothelial tumor tissue. Ectopic expression of IGF2 and IGF1R, but not IGF1, in bladder cancer cells restored this process, suggesting that IGF2 is a target of curcumin. Moreover, introduction of constitutively active AKT1 abolished the inhibitory effect of curcumin on cell proliferation, migration, and restored the phosphorylation levels of 4E-BP1 and S6K1, suggesting that curcumin functions via suppressing IGF2-mediated AKT/mTOR signaling pathway. In summary, our results reveal that suppressing IGF2 and IGF2-mediated PI3K/AKT/mTOR signaling pathway is one of the mechanisms of action of curcumin. Our findings suggest a new therapeutic strategy against human bladder cancer caused by aberrant activation of IGF2, which are useful for translational application of curcumin.

Overproduction of IGF-2 drives a subset of colorectal cancer cells, which specifically respond to an anti-IGF therapeutic antibody and combination therapies.

Colorectal cancer (CRC) is a heterogeneous disease with a broad spectrum of genetic and epigenetic changes. A comprehensive molecular characterization of CRC by The Cancer Genome Atlas Network detected the overexpression of the insulin-like growth factor 2 (IGF2) gene, encoding a ligand for the insulin-like growth factor 1 receptor (IGF-1R), in a subset of CRC tumors. In this study, we investigated the oncogenic potential of IGF-2 in IGF2-overexpressing CRC models and the efficacy of MEDI-573, an IGF-1/2-neutralizing antibody. We found that a subset of CRC cell lines express high IGF-2 levels owing to an increased DNA copy number and hypermethylation in the H19 promoter of the IGF2 gene. MEDI-573 efficiently neutralized IGF-2 and induced apoptosis, which resulted in significant tumor growth inhibition in CRC mouse models that express high levels of IGF-2. These effects were specific to CRCs overexpressing IGF-2, as MEDI-573 did not affect the growth CRC cell lines with normal levels. Moreover, blockade of IGF-2 by MEDI-573 modulated other signaling pathways, suggesting combination therapies with inhibitors of these pathways. Indeed, in vivo efficacy was significantly enhanced when MEDI-573 was used in combination with trastuzumab, AZD2014 (dual mTORC1/2i), AZD5363 (AKTi) and selumetinib (AZD6244/ARRY-142886, MEK1/2i) or cetuximab. These results demonstrate that overexpressed IGF-2 is the major tumorigenic driver in a subset of CRCs and encourage testing of MEDI-573, alone and in combinations, in IGF2-overexpressing CRC patients.

Current ideas on the biology of IGFBP-6: More than an IGF-II inhibitor?

IGFBP-6 binds IGF-II with higher affinity than IGF-I and it is a relatively specific inhibitor of IGF-II actions. More recently, IGFBP-6 has also been reported to have IGF-independent effects on cell proliferation, survival, differentiation and migration. IGFBP-6 binds to several ligands in the extracellular space, cytoplasm and nucleus. These interactions, together with activation of distinct intracellular signaling pathways, may contribute to its IGF-independent actions; for example, IGF-independent migration induced by IGFBP-6 involves interaction with prohibitin-2 and activation of MAP kinase pathways. A major challenge for the future is delineating the relative roles of the IGF-dependent and -independent actions of IGFBP-6, which may lead to the development of therapeutic approaches for diseases including cancer.

Maternal folic acid supplementation modulates DNA methylation and gene expression in the rat offspring in a gestation period-dependent and organ-specific manner.

Maternal folic acid supplementation can alter DNA methylation and gene expression in the developing fetus, which may confer disease susceptibility later in life. We determined which gestation period and organ were most sensitive to the modifying effect of folic acid supplementation during pregnancy on DNA methylation and gene expression in the offspring. Pregnant rats were randomized to a control diet throughout pregnancy; folic acid supplementation at 2.5× the control during the 1st, 2nd or 3rd week of gestation only; or folic acid supplementation throughout pregnancy. The brain, liver, kidney and colon from newborn pups were analyzed for folate concentrations, global DNA methylation and gene expression of the Igf2, Er-α, Gr, Ppar-α and Ppar-γ genes. Folic acid supplementation during the 2nd or 3rd week gestation or throughout pregnancy significantly increased brain folate concentrations (P<.001), while only folic acid supplementation throughout pregnancy significantly increased liver folate concentrations (P=.005), in newborn pups. Brain global DNA methylation incrementally decreased from early to late gestational folic acid supplementation and was the lowest with folic acid supplementation throughout pregnancy (P=.026). Folic acid supplementation in late gestation or throughout pregnancy significantly decreased Er-α, Gr and Ppar-α gene expression in the liver (P<.05). The kidney and colon were resistant to the effect of folic acid supplementation. Maternal folic acid supplementation affects tissue folate concentrations, DNA methylation and gene expression in the offspring in a gestation-period-dependent and organ-specific manner.

Tanshinone IIA Prevents Leu27IGF-II-Induced Cardiomyocyte Hypertrophy Mediated by Estrogen Receptor and Subsequent Akt Activation.

IGF-IIR plays important roles as a key regulator in myocardial pathological hypertrophy and apoptosis, which subsequently lead to heart failure. Salvia miltiorrhiza Bunge (Danshen) is a traditional Chinese medicinal herb used to treat cardiovascular diseases. Tanshinone IIA is an active compound in Danshen and is structurally similar to 17[Formula: see text]-estradiol (E[Formula: see text]. However, whether tanshinone IIA improves cardiomyocyte survival in pathological hypertrophy through estrogen receptor (ER) regulation remains unclear. This study investigates the role of ER signaling in mediating the protective effects of tanshinone IIA on IGF-IIR-induced myocardial hypertrophy. Leu27IGF-II (IGF-II analog) was shown in this study to specifically activate IGF-IIR expression and ICI 182,780 (ICI), an ER antagonist used to investigate tanshinone IIA estrogenic activity. We demonstrated that tanshinone IIA significantly enhanced Akt phosphorylation through ER activation to inhibit Leu27IGF-II-induced calcineurin expression and subsequent NFATc3 nuclear translocation to suppress myocardial hypertrophy. Tanshinone IIA reduced the cell size and suppressed ANP and BNP, inhibiting antihypertrophic effects induced by Leu27IGF-II. The cardioprotective properties of tanshinone IIA that inhibit Leu27IGF-II-induced cell hypertrophy and promote cell survival were reversed by ICI. Furthermore, ICI significantly reduced phospho-Akt, Ly294002 (PI3K inhibitor), and PI3K siRNA significantly reduced the tanshinone IIA-induced protective effect. The above results suggest that tanshinone IIA inhibited cardiomyocyte hypertrophy, which was mediated through ER, by activating the PI3K/Akt pathway and inhibiting Leu27IGF-II-induced calcineurin and NFATC3. Tanshinone IIA exerted strong estrogenic activity and therefore represented a novel selective ER modulator that inhibits IGF-IIR signaling to block cardiac hypertrophy.

Increased In Vitro Osteopotential in SHED Associated with Higher IGF2 Expression When Compared with hASCs.

Mesenchymal stem cell (MSC) osteogenic differentiation potential varies according to factors such as tissue source and cell population heterogeneity. Pre-selection of cell subpopulations harboring higher osteopotential is a promising strategy to achieve a thorough translation of MSC-based therapies to the clinic. Here, we searched for novel molecular markers predictive of osteopotential by comparing MSC populations from two sources harboring different osteogenic potentials. We show that MSCs from human deciduous teeth (SHED) have an intrinsically higher osteogenic potential when compared with MSCs from human adipose tissue (hASCs) under the same in vitro controlled induction system. Transcriptome profiling revealed IGF2 to be one of the top upregulated transcripts before and during early in vitro osteogenic differentiation. Further, exogenous IGF2 supplementation enhanced alkaline phosphatase activity and matrix mineralization, and inhibition of IGF2 lessened these parameters in SHED and hASCs, validating IGF2 as an osteogenic factor in these MSCs. Further, we found IGF2 to be biallelically expressed in SHED, but not in hASCs. We observed a 4 % methylation increase in the imprinting control region within the IGF2-H19 locus in SHED, and this is mainly due to 2 specific CpG sites. Thus, we suggest that IGF2 upregulation in SHED is due to loss of imprinting. This study unravels osteogenic properties in SHED, implying IGF2 as a potential biomarker of MSCs with higher osteopotential, and unveils IGF2 loss-of-imprinting in SHED.

A dual-specific anti-IGF-1/IGF-2 human monoclonal antibody alone and in combination with temsirolimus for therapy of neuroblastoma.

The insulin-like growth factors (IGFs), IGF-1 and IGF-2, have been implicated in the growth, survival and metastasis of a broad range of malignancies including pediatric tumors. They bind to the IGF receptor type 1 (IGF-1R) and the insulin receptor (IR) which are overexpressed in many types of solid malignancies. Activation of the IR by IGF-2 results in increased survival of tumor cells. We have previously identified a novel human monoclonal antibody, m708.5, which binds with high (pM) affinity to both human IGF-1 and IGF-2, and potently inhibits phosphorylation of the IGF-1R and the IR in tumor cells. m708.5 exhibited strong antitumor activity as a single agent against most cell lines derived from neuroblastoma, Ewing family of tumor, rhabdomyosarcoma and osteosarcoma. When tested in neuroblastoma cell lines, it showed strong synergy with temsirolimus and synergy with chemotherapeutic agents in vitro. In xenograft models, the combination of m708.5 and temsirolimus significantly inhibited neuroblastoma growth and prolonged mouse survival. Taken together, these results support the clinical development of m708.5 for pediatric solid tumors with potential for synergy with chemotherapy and mTOR inhibitors.

Biologic roles of estrogen receptor-ß and insulin-like growth factor-2 in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) occurs in 10-15% of patients yet accounts for almost half of all breast cancer deaths. TNBCs lack expression of estrogen and progesterone receptors and HER-2 overexpression and cannot be treated with current targeted therapies. TNBCs often occur in African American and younger women. Although initially responsive to some chemotherapies, TNBCs tend to relapse and metastasize. Thus, it is critical to find new therapeutic targets. A second ER gene product, termed ERß, in the absence of ERα may be such a target. Using human TNBC specimens with known clinical outcomes to assess ERß expression, we find that ERß1 associates with significantly worse 5-year overall survival. Further, a panel of TNBC cell lines exhibit significant levels of ERß protein. To assess ERß effects on proliferation, ERß expression in TNBC cells was silenced using shRNA, resulting in a significant reduction in TNBC proliferation. ERß-specific antagonists similarly suppressed TNBC growth. Growth-stimulating effects of ERß may be due in part to downstream actions that promote VEGF, amphiregulin, and Wnt-10b secretion, other factors associated with tumor promotion. In vivo, insulin-like growth factor-2 (IGF-2), along with ERß1, is significantly expressed in TNBC and stimulates high ERß mRNA in TNBC cells. This work may help elucidate the interplay of metabolic and growth factors in TNBC.

Phase I dose-escalation study evaluating safety, tolerability and pharmacokinetics of MEDI-573, a dual IGF-I/II neutralizing antibody, in Japanese patients with advanced solid tumours.

PURPOSE: This Phase I, open-label, single-arm, dose-escalation study aimed to evaluate the safety and tolerability of the insulin-like growth factor (IGF-I/II) neutralizing antibody, MEDI-573, in Japanese patients with advanced solid tumours refractory to standard therapy or for which no standard therapy exists. The pharmacokinetics, pharmacodynamics and antitumour activity of MEDI-573 were also evaluated. METHODS: Three cohorts of patients received MEDI-573 in escalating order: cohort 1, 5 mg/kg on Day 1, 8 and 15; cohort 2, 15 mg/kg on Day 1, 8 and 15; cohort 3, 45 mg/kg on Day 1, of 21-day cycles. RESULTS: Ten patients who received at least one dose of MEDI-573 were evaluated. The median number of treatment cycles was 2.0 (range 1-6) and the median number of MEDI-573 doses received was 4.0 (range 1-17). The most commonly reported drug-related adverse events were fatigue (n = 2 patients), pyrexia (n = 2), diarrhoea (n = 2) and electrocardiogram QT prolongation (n = 2). No patients experienced a dose-limiting toxicity. Pharmacokinetics of MEDI-573 were linear with a dose-dependent increase. There were no complete or partial responses; four patients had an overall best response of stable disease. CONCLUSIONS: MEDI-573 is well tolerated at the doses investigated.

A new bispecific antibody targeting non-overlapping epitopes on IGF2: design, in vitro characterization and pharmacokinetics in macaques.

The insulin-like growth factor 2 (IGF2) is an important target for cancer therapy. We have previously proposed an approach for fast and irreversible removal of IGF2 from the circulation by using monoclonal antibodies (mAbs) that bind to two or more non-overlapping epitopes on the same molecule. We provided initial evidence for the formation of oligomeric antibody-ligand complexes that can bind to cells expressing Fc gamma receptors (FcγRs) with high avidity using an antibody domain with relatively low affinity as one of the anti-IGF2 mAbs. Recently, we identified a mAb, m708.5, in a scFv format which binds to both IGF2 and IGF1 with very high (pM) affinity. Interestingly, and rather surprisingly, this mAb did not compete with our other high affinity mAb, m610.27, for binding to IGF2. Therefore, we generated a new bispecific mAb, m67, by combining m708.5 and m610.27. As expected m67 potently inhibited binding of IGF2 to cells expressing the IGF1R and its phosphorylation, and resulted in formation of multimolecular complexes when incubated with IGF2 and bound with high avidity to cells expressing FcγRII; the complexes were internalized in a macrophage-like cell line. However, although m67 exhibited a reasonably long half-life (6.4 ± 0.6 days) in cynomolgus macaques and high stability in serum, its administration to three animals did not result in any measurable decrease in the IGF2 concentration likely due to the complexity of the IGF2 interactions in the blood and the relatively low (2mg/kg) dose of the mAb leading to a relatively low maximal blood concentration of 120nM. In spite of the lack of effect on the IGF2 concentration in this particular experimental setup, m67 exhibited good drugability properties and could be highly effective in other animal models and in humans. Studies with animal models of cancer are ongoing to evaluate the potential of m67 as a new candidate mAb-based therapeutic.