Role of insulin-like growth factor binding protein 2 in lung adenocarcinoma: IGF-independent antiapoptotic effect via caspase-3

IGFBP2/ITGA5 promotes gefitinib resistance via activating STAT3/CXCL1 axis in non-small cell lung cancer

There is a paucity of comprehensive knowledge pertaining to the underlying mechanisms leading to gefitinib resistance in individuals diagnosed NSCLC harboring EGFR-sensitive mutations who inevitably develop resistance to gefitinib treatment within six months to one year. In our preceding investigations, we have noted a marked upregulation of IGFBP2 in the neoplastic tissues of NSCLC, predominantly in the periphery of the tissue, implying its plausible significance in NSCLC. Consequently, in the current research, we delved into the matter and ascertained the molecular mechanisms that underlie the participation of IGFBP2 in the emergence of gefitinib resistance in NSCLC cells. Firstly, the expression of IGFBP2 in the bronchoalveolar lavage fluid and lung cancer tissues of 20 NSCLC patients with gefitinib tolerance was found to be significantly higher than that of non-tolerant patients. Furthermore, in vitro and in vivo experiments demonstrated that IGFBP2 plays a significant role in the acquisition of gefitinib resistance. Mechanistically, IGFBP2 can activate STAT3 to enhance the transcriptional activity of CXCL1, thereby increasing the intracellular expression level of CXCL1, which contributes to the survival of lung cancer cells in the gefitinib environment. Additionally, we identified ITGA5 as a key player in IGFBP2-mediated gefitinib resistance, but it does not function as a membrane receptor in the process of linking IGFBP2 to intracellular signaling transduction. In conclusion, this study demonstrates the promoting role and mechanism of IGFBP2 in acquired gefitinib resistance caused by non-EGFR secondary mutations, suggesting the potential of IGFBP2 as a biomarker for gefitinib resistance and a potential intervention target.

Gold Nanoparticles Disrupt the IGFBP2/mTOR/PTEN Axis to Inhibit Ovarian Cancer Growth

By exploiting the self-therapeutic properties of gold nanoparticles (GNPs) a molecular axis that promotes the growth of high-grade serous ovarian cancer (HGSOC), one of the deadliest gynecologic malignancies with poorly understood underlying molecular mechanisms, has been identified. The biodistribution and toxicity of GNPs administered by intravenous or intraperitoneal injection, both as a single dose or by repeated dosing over two weeks are first assessed; no biochemical or histological toxicity to vital organs is found. Using an orthotopic patient-derived xenograft (PDX) model of HGSOC, the authors then show that GNP treatment robustly inhibits tumor growth. Investigating the molecular mechanisms underlying the GNP efficacy reveals that GNPs downregulate insulin growth factor binding protein 2 (IGFBP2) by disrupting its autoregulation via the IGFBP2/mTOR/PTEN axis. This mechanism is validated by treating a cell line-based human xenograft tumor with GNPs and an mTOR dual-kinase inhibitor (PI-103), either individually or in combination with GNPs; GNP and PI-103 combination therapy inhibit ovarian tumor growth similarly to GNPs alone. This report illustrates how the self-therapeutic properties of GNPs can be exploited as a discovery tool to identify a critical signaling axis responsible for poor prognosis in ovarian cancer and provides an opportunity to interrogate the axis to improve patient outcomes.

Autologous treatment for ALS with implication for broad neuroprotection

Background

Amyotrophic lateral sclerosis (ALS) is characterized by a progressive loss of motor neurons (MNs), leading to paralysis, respiratory failure and death within 2–5 years of diagnosis. The exact mechanisms of sporadic ALS, which comprises 90% of all cases, remain unknown. In familial ALS, mutations in superoxide dismutase (SOD1) cause 10% of cases.

Methods

ALS patient-derived human-induced pluripotent stem cells (ALS hiPSCs, harboring the SOD1^AV4 mutation), were differentiated to MNs (ALS-MNs). The neuroprotective effects of conditioned medium (CM) of hESCs (H9), wt hiPSCs (WTC-11) and the ALS iPSCs, on MN apoptosis and viability, formation and maintenance of neurites, mitochondrial activity and expression of inflammatory genes, were examined. For in vivo studies, 200 μl of CM from the ALS iPSCs (CS07 and CS053) was injected subcutaneously into the ALS model mice (transgenic for the human SOD1^G93A mutation). Animal agility and strength, muscle innervation and mass, neurological score, onset of paralysis and lifespan of the ALS mice were assayed. After observing significant disease-modifying effects, the CM was characterized biochemically by fractionation, comparative proteomics, and epigenetic screens for the dependence on pluripotency. CM of fibroblasts that were differentiated from the wt hiPSCs lacked any neuroprotective activity and was used as a negative control throughout the studies.

Results

The secretome of PSCs including the ALS patient iPSCs was neuroprotective in the H₂O₂ model. In the model with pathogenic SOD1 mutation, ALS iPSC-CM attenuated all examined hallmarks of ALS pathology, rescued human ALS-MNs from denervation and death, restored mitochondrial health, and reduced the expression of inflammatory genes. The ALS iPSC-CM also improved neuro-muscular health and function, and delayed paralysis and morbidity in ALS mice. Compared side by side, cyclosporine (CsA), a mitochondrial membrane blocker that prevents the leakage of mitochondrial DNA, failed to avert the death of ALS-MNs, although CsA and ALS iPSC-CM equally stabilized MN mitochondria and attenuated inflammatory genes. Biochemical characterization, comparative proteomics, and epigenetic screen all suggested that it was the interactome of several key proteins from different fractions of PSC-CM that delivered the multifaceted neuroprotection.

Conclusions

This work introduces and mechanistically characterizes a new biologic for treating ALS and other complex neurodegenerative diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40035-022-00290-5.

Anticancer properties of dried-pericarp water extracts of Camellia japonica L. fermented with Aspergillus oryzae through regulation of IGFBP-2/mTOR pathway

This study aimed to investigate the anticancer activity of dried-pericarp water extract of fermented C. japonicus (CJ). The dried-pericarp water extracts of CJ were fermented using Aspergillus oryzae and Saccharomyces cerevisiae at 30 °C and 35 °C. The anticancer activities of both water extracts fermented at 30 °C and 35 °C using A. oryzae against FaDu cells were remarkably changed compared with unfermented dried-pericarp water extract of CJ, which has no anticancer activity. Cleaved-PARP, caspase 3, and apoptotic cells stained with annexin V/PI were significantly increased by treatment with A. oryzae extracts fermented at 30 °C. The insulin-like growth factor-binding protein 2 (IGFBP-2) protein level and mTOR phosphorylation by A. oryzae fermented extracts (AOFE) were dramatically reduced, and the expression levels of IGFBP-2 and phosphorylated mTOR were significantly increased depending on the glucose concentrations in FaDu cells. These results suggested that the cell viabilities in AOFE were restored as the glucose concentrations increased. Furthermore, it was confirmed LC/MS/MS that the content of gallic acid was increased by fermentation of Aspergillus oryzae (5.596 ± 0.1746 μg/mg) compared to the unfermented extract (1.620 ± 0.0432 μg/mg). Based on these results, the anticancer effect of AOFE was achieved through inhibition of the IGFBP-2/mTOR signaling pathway. These results suggest that AOFE may be a potential treatment for head and neck cancer.

Serum insulin-like growth factor binding protein 2 levels as biomarker for pancreatic ductal adenocarcinoma-associated malnutrition and muscle wasting

BACKGROUND

Malnutrition and muscle wasting are common features frequently observed in pancreatic ductal adenocarcinoma (PDAC) patients with cancer cachexia. They are associated with reduced survival and quality of life. Nutrition therapy is an important part of multimodal cancer care in PDAC. However, due to the complexity of nutrition assessment, only 30-60% of patients with nutritional risks receive nutritional treatment at present. It is important to identify biomarkers that may be used to improve management of PDAC-associated malnutrition. Serum insulin-like growth factor binding protein 2 (IGFBP2) has emerged as a potential serum biomarker in a variety of tumours. However, its association with malnutrition and muscle wasting in PDAC is unclear.

METHODS

We evaluated the tumour IGFBP2 expression and serum IGFBP2 level in 98 PDAC patients using immunohistochemistry and enzyme-linked immunosorbent assay and analysed the correlation between them. Furthermore, we explored the relationship between IGFBP2 of both tumour and serum and nutritional status (Patient-Generated Subjective Global Assessment and skeletal muscle index). Pan02 IGFBP2 stable transfection cell lines, Pan02 PLV-IGFBP2 cells, and PLKO-IGFBP2 cells were injected subcutaneously into the flank of C57BL/6 mouse. Serum IGFBP2 levels, food intake, and body weight of these mice were measured. The degree of muscle atrophy is characterized by haematoxylin and eosin, Oil Red O, and Masson's trichrome staining. The mRNA and protein expression of several essential muscle-related signal proteins such as atrogin-1 and muscle RING finger 1 was measured.

RESULTS

Among 98 patients, we found that tumour IGFBP2 expression is related to plasma IGFBP2 levels (r_s  = 0.562, P < 0.001), and they significantly increased among patients with Patient-Generated Subjective Global Assessment ≥9 and correlated with overall survival. Moreover, serum IGFBP2 level is negatively correlated with skeletal muscle index (r_s  = -0.600, P < 0.001) and Hounsfield units (r_s  = -0.532, P < 0.001). In mice injected with Pan02 PLV-IGFBP2 cell, circulating IGFBP2 was elevated while body weight and food intake were decreased when compared with Pan02 PLV-Control group. These mice also exhibited significantly aggravated muscle fibre atrophy, lipid deposition, and increased collagen tissue, and the expression of mRNA and protein of atrogin-1 and muscle RING finger 1 in the gastrocnemius muscle is increased. Conversely, these symptoms were alleviated in the PLKO-IGFBP2 group.

CONCLUSIONS

In the current study, there is a significant correlation between serum IGFBP2 levels, malnutrition, and muscle atrophy in PDAC. Our results suggested that serum IGFBP2 level might be a promising biomarker and intervention targets for PDAC-associated severe malnutrition and muscle wasting.

Differences in the Loin Tenderness of Iberian Pigs Explained through Dissimilarities in Their Transcriptome Expression Profile

Simple Summary

The Iberian pig is the most representative autochthonous breed of the Mediterranean region with unique genetic and phenotypic characteristics. The breed has been successfully preserved by its high-quality meat and high-priced products. Tenderness is one of the most relevant meat quality traits, and meat tenderization is influenced by genetic and environmental effects such as pre-slaughter handling and post-mortem conditions. Tenderness could be included in Iberian pig breeding programs, mainly focused on the improvement of premium-cuts percentage, in order to avoid the meat quality decline. A better biological understanding of this trait is needed. In the current study, we analyze the transcriptome of pigs divergent for Warner–Bratzler shear force through RNA-seq technique for the identification, characterization and quantification of candidate genes involved in biological pathways, networks and functions affecting meat tenderness.

Abstract

Tenderness is one of the most important meat quality traits and it can be measured through shear force with the Warner–Bratzler test. In the current study, we use the RNA-seq technique to analyze the transcriptome of Longissimus dorsi (LD) muscle in two groups of Iberian pigs (Tough and Tender) divergent for shear force breeding values. We identified 200 annotated differentially expressed genes (DEGs) and 245 newly predicted isoforms. The RNAseq expression results of 10 genes were validated with quantitative PCR (qPCR). Functional analyses showed an enrichment of DE genes in biological processes related to proteolysis (CTSC, RHOD, MYH8, ACTC1, GADD45B, CASQ2, CHRNA9 and ANKRD1), skeletal muscle tissue development (ANKRD1, DMD, FOS and MSTN), lipid metabolism (FABP3 and PPARGC1A) and collagen metabolism (COL14A1). The upstream analysis revealed a total of 11 transcription regulatory factors that could regulate the expression of some DEGs. Among them, IGF1, VGLL3 and PPARG can be highlighted since they regulate the expression of genes involved in biological pathways that could affect tenderness. The experiment revealed a set of candidate genes and regulatory factors suggestive to search polymorphisms that could be incorporated in a breeding program for improving meat tenderness.

IGFBP2: integrative hub of developmental and oncogenic signaling network

Insulin-like growth factor (IGF) binding protein 2 (IGFBP2) was discovered and identified as an IGF system regulator, controlling the distribution, function, and activity of IGFs in the pericellular space. IGFBP2 is a developmentally regulated gene that is highly expressed in embryonic and fetal tissues and markedly decreases after birth. Studies over the last decades have shown that in solid tumors, IGFBP2 is upregulated and promotes several key oncogenic processes, such as epithelial-to-mesenchymal transition, cellular migration, invasion, angiogenesis, stemness, transcriptional activation, and epigenetic programming via signaling that is often independent of IGFs. Growing evidence indicates that aberrant expression of IGFBP2 in cancer acts as a hub of an oncogenic network, integrating multiple cancer signaling pathways and serving as a potential therapeutic target for cancer treatment.

Breed, Diet, and Interaction Effects on Adipose Tissue Transcriptome in Iberian and Duroc Pigs Fed Different Energy Sources

In this study, we analyzed the effects of breed, diet energy source, and their interaction on adipose tissue transcriptome in growing Iberian and Duroc pigs. The study comprised 29 Iberian and 19 Duroc males, which were kept under identical management conditions except the nutritional treatment. Two isoenergetic diets were used with 6% high oleic sunflower oil (HO) or carbohydrates (CH) as energy sources. All animals were slaughtered after 47 days of treatment at an average live weight of 51.2 kg. Twelve animals from each breed (six fed each diet) were employed for ham subcutaneous adipose tissue RNA-Seq analysis. The data analysis was performed using two different bioinformatic pipelines. We detected 837 and 1456 differentially expressed genes (DEGs) according to breed, depending on the pipeline. Due to the strong effect of breed on transcriptome, the effect of the diet was separately evaluated in the two breeds. We identified 207 and 57 DEGs depending on diet in Iberian and Duroc pigs, respectively. A joint analysis of both effects allowed the detection of some breed–diet interactions on transcriptome, which were inferred from RNA-Seq and quantitative PCR data. The functional analysis showed the enrichment of functions related to growth and tissue development, inflammatory response, immune cell trafficking, and carbohydrate and lipid metabolism, and allowed the identification of potential regulators. The results indicate different effects of diet on adipose tissue gene expression between breeds, affecting relevant biological pathways.

Overexpression of IGFBP2 mRNA predicts poor survival in patients with glioblastoma

The prognosis of patients with glioblastoma (GBM) is dismal. It has been reported that Insulin-like growth factor (IGF) binding protein 2 (IGFBP2) is associated with the mobility and invasion of tumor cells. We investigated the expression of IGFBP2 mRNA in GBMs and its clinical relevance, using tissue microarrays and RNAscope in situ hybridization in 180 GBMs and 13 normal or edematous tissues. The correlations between the expression and clinical pathological parameters as well as some other biomarkers were analyzed. Overexpression of IGFBP2 mRNA was observed in 23.9% of tumors tested. No expression of IGFBP2 mRNA was detected in normal or edematous tissues. Kaplan–Meier survival analysis showed that the survival time of all the patients with high IGFBP2 tumors had shorter survival than those with low IGFBP2 (P<0.01). Univariate regression and multivariate regression both indicated that the expression of IGFBP2 transcript level was an independent prognostic factor (P=0.008 and 0.007, respectively). Furthermore, expression of IGFBP2 mRNA was related to the occurrence of isocitrate dehydrogenase 1 (IDH1) mutation, high heat shock protein 27 (Hsp27) expression and telomerase reverse transcriptase (TERT) promoter mutation (TERTp⁺) (P=0.013, 0.015 and 0.016, respectively), and patients with TERTp⁺/IGFBP2^high showed the shortest survival. In conclusion, IGFBP2 mRNA expression status is an independent prognostic biomarker in GBMs, and the combination of IGFBP2 mRNA and TERTp status might serve as a prognostic indicator in patients with GBM.

Activation of EGFR-DNA-PKcs pathway by IGFBP2 protects esophageal adenocarcinoma cells from acidic bile salts-induced DNA damage

Background

The incidence of esophageal adenocarcinoma (EAC) is rising rapidly in the US and Western countries. The development of Barrett’s esophagus (BE) and its progression to EAC have been linked to chronic gastroesophageal reflux disease (GERD). Exposure of BE and EAC cells to acidic bile salts (ABS) in GERD conditions induces high levels of oxidative stress and DNA damage. In this study, we investigated the role of insulin-like growth factor binding protein 2 (IGFBP2) in regulating ABS-induced DNA double-strand breaks.

Methods

Real-time RT-PCR, western blot, immunohistochemistry, immunofluorescence, co-immunoprecipitation, flow cytometry, and cycloheximide (CHX) chase assays were used in this study. To mimic GERD conditions, a cocktail of acidic bile salts (pH 4) was used in 2D and 3D organotypic culture models. Overexpression and knockdown of IGFBP2 in EAC cells were established to examine the functional and mechanistic roles of IGFBP2 in ABS-induced DNA damage.

Results

Our results demonstrated high levels of IGFBP2 mRNA and protein in EAC cell lines as compared to precancerous Barrett’s cell lines, and IGFBP2 is frequently overexpressed in EACs (31/57). Treatment of EAC cells with ABS, to mimic GERD conditions, induced high levels of IGFBP2 expression. Knocking down endogenous IGFBP2 in FLO1 cells (with constitutive high levels of IGFBP2) led to a significant increase in DNA double-strand breaks and apoptosis, following transient exposure to ABS. On the other hand, overexpression of exogenous IGFBP2 in OE33 cells (with low endogenous levels of IGFBP2) had a protective effect against ABS-induced double-strand breaks and apoptosis. We found that IGFBP2 is required for ABS-induced nuclear accumulation and phosphorylation of EGFR and DNA-PKcs, which are necessary for DNA damage repair activity. Using co-immunoprecipitation assay, we detected co-localization of IGFBP2 with EGFR and DNA-PKcs, following acidic bile salts treatment. We further demonstrated, using cycloheximide chase assay, that IGFBP2 promotes EGFR protein stability in response to ABS exposure.

Conclusions

IGFBP2 protects EAC cells against ABS-induced DNA damage and apoptosis through stabilization and activation of EGFR - DNA-PKcs signaling axis.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-1021-y) contains supplementary material, which is available to authorized users.

IGFBP2 promotes salivary adenoid cystic carcinoma metastasis by activating the NF-κB/ZEB1 signaling pathway

Metastasis is a major cause of poor prognosis in patients suffered with salivary adenoid cystic carcinoma (SACC), in which many factors are implicated. In this study, we identified that IGFBP2, overexpressed in SACC, correlated positively with perineural invasion or metastasis and indicated worse outcome. Moreover, IGFBP2 overexpression could dramatically improve motility and invasion capacity of SACC cells in vitro. Mechanically, IGFBP2 enhanced expression of ZEB1 in a NF-κB (p65)-dependent manner and then promoted epithelial-mesenchymal transition (EMT) in SACC. In addition, IGFBP2 mutation in the nuclear localization signal could impede nuclear translocation of p65, lower ZEB1 expression, and abrogate the EMT process. In xenograft models, IGFBP2 overexpression promoted lung and liver metastases of SACC cells; while if nuclear IGFBP2 was reduced, the formation of metastases in lung and liver was weakened. Together, these results for the first time demonstrate that IGFBP2 plays an important role in invasion and metastasis of SACC through the NF-κB/ZEB1 signaling pathway and IGFBP2 may be a novel biomarker and target for SACC.

Hypoxia negates hyperglycaemia-induced chemo-resistance in breast cancer cells: the role of insulin-like growth factor binding protein 2

Background

Women who suffer from breast cancer and type II diabetes with associated hyperglycaemia respond less well to chemotherapy. We have shown that hyperglycaemia induces resistance to chemotherapy through upregulation of fatty acid synthase (FASN) in breast cancer cells and increased insulin-like binding protein 2 (IGFBP-2) in prostate cancer cells. As a tumour develops the tumour mass can outgrow the blood supply resulting in the cancer cells being exposed to hypoxia that stimulates many tumorigenic signalling pathways.

Methods

We used MCF-7 and T47D breast cancer cell lines. Trypan blue dye exclusion assay was employed to assess cell death and Western immunoblotting was used to determine changes in protein abundance. Hypoxia was induced both chemically by the addition of cobalt chloride (CoCl₂) and using a hypoxia chamber.

Results

IGFBP-2 abundance increased with increasing concentrations of glucose (0-25 mM) that contributed to hyperglycaemia-induced chemo-resistance as it was abrogated by downregulating IGFBP-2 using siRNA. Production of IGFBP-2 is ER dependent: pre-treatment of MCF-7 cells with β-estradiol increased IGFBP-2 and induced chemo-resistance to doxorubicin. The hyperglycaemia-induced chemo-resistance and increases in FASN and IGFBP-2 were negated in a hypoxic environment, with levels of cell death unaffected by glucose concentrations.

Conclusions

The sensitivity of breast cancer cells to chemotherapy is reduced in hyperglycaemic conditions but this effect is negated by hypoxia. These effects appear to be mediated via regulation of IGFBP-2 and FASN. Understanding the role of FASN and IGFBP-2 in chemo-resistance could provide a novel target for improving the effectiveness of breast cancer treatment.

IGFBP2 modulates the chemoresistant phenotype in esophageal adenocarcinoma

Esophageal adenocarcinoma (EAC) patients commonly present with advanced stage disease and demonstrate resistance to therapy, with response rates below 40%. Understanding the molecular mechanisms of resistance is crucial for improvement of clinical outcomes. IGFBP2 is a member of the IGFBP family of proteins that has been reported to modulate both IGF and integrin signaling and is a mediator of cell growth, invasion and resistance in other tumor types. In this study, high IGFBP2 expression was observed in a subset of primary EACs and was found to be significantly higher in patients with shorter disease-free intervals as well as in treatment-resistant EACs as compared to chemonaive EACs. Modulation of IGFBP2 expression in EAC cell lines promoted cell proliferation, migration and invasion, implicating a role in the metastatic potential of these cells. Additionally, knockdown of IGFBP2 sensitized EAC cells to cisplatin in a serum-dependent manner. Further in vitro exploration into this chemosensitization implicated both the AKT and ERK pathways. Silencing of IGFBP2 enhanced IGF1-induced immediate activation of AKT and reduced cisplatin-induced ERK activation. Addition of MEK1/2 (selumetinib or trametinib) or AKT (AKT Inhibitor VIII) inhibitors enhanced siIGFBP2-induced sensitization of EAC cells to cisplatin. These results suggest that targeted inhibition of IGFBP2 alone or together with either the MAPK or PI3K/AKT signaling pathway in IGFBP2-overexpressing EAC tumors may be an effective approach for sensitizing resistant EACs to standard neoadjuvant chemotherapy.

IGF-binding protein 2 is a candidate target of therapeutic potential in cancer

Insulin-like growth factor (IGF)-binding protein 2(IGFBP2), a key member of IGF family, has been reported as a notable oncogene in most human epithelium cancers. Increasing evidences suggested that IGFBP2 might be a candidate target of therapuetic potential by regulating key cancer metastasis and invasion-associated signaling networks, but there is still confusion about the mechanism on how IGFBP2 takes part in these processes. In this review, we summarized the current points of view that IGFBP2 functions in signaling pathways during tumorigenesis and tumor progression and discussed its potential clinical applications as a therapeutic target.

TRIB3 enhances cell viability during glucose deprivation in HEK293-derived cells by upregulating IGFBP2, a novel nutrient deficiency survival factor

Glucose deprivation occurs in several human diseases, including infarctions and solid tumors, and leads to cell death. In this article, we investigate the role of the pseudokinase Tribbles homolog 3 (TRIB3) in the cellular stress response to glucose starvation using cell lines derived from HEK293, which is highly glycolytic under standard conditions. Our results show that TRIB3 mRNA and protein levels are strongly upregulated in glucose-deprived cells via the induction of activating transcription factor 4 (ATF4) by the endoplasmic reticulum (ER) stress sensor kinase PERK. Cell survival in glucose-deficient conditions is enhanced by TRIB3 overexpression and reduced by TRIB3 knockdown. Genome-wide gene expression profiling uncovered approximately 40 glucose deprivation-responsive genes that are affected by TRIB3, including several genes involved in signaling processes and metabolism. Based on transcription factor motif analysis, the majority of TRIB3-downregulated genes are target genes of ATF4, which TRIB3 is known to inhibit. The gene most substantially upregulated by TRIB3 is insulin-like growth factor binding protein 2 (IGFBP2). IGFBP2 mRNA and protein levels are downregulated in cells subjected to glucose deprivation, and reduced IGFBP2 expression aggravates cell death during glucose deficiency, while overexpression of IGFBP2 prolongs cell survival. Moreover, IGFBP2 silencing abrogates the pro-survival effect of TRIB3. Since TRIB3 augments IGFBP2 expression in glucose-starved cells, the data indicate that IGFBP2 contributes to the attenuation of cell death by TRIB3. These results implicate TRIB3 and IGFBP2, both of which are known to be overexpressed in several types of cancers, as pro-survival modulators of cell viability in nutrient-deficient microenvironments.

Inhibition of IGFBP-2 improves the sensitivity of bladder cancer cells to cisplatin via upregulating the expression of maspin

The present study aimed to reveal the association between insulin-like growth factor binding protein-2 (IGFBP-2) and the sensitivity of bladder cancer cells to cisplatin, and determine the underlying mechanism involving maspin. A total of 32 bladder cancer tissue samples were collected for analysis. Cells of the BIU87 human bladder cancer cell line were cultured and a cisplatin-resistant subline (BIU87-CisR) was established by continuous exposure of the cells to cisplatin. Targeted inhibition of IGFBP-2 in the BIU87-CisR cells was performed using small interfering RNA technology. The expression levels of IGFBP-2 and maspin in the tissue samples and cells were analyzed using reverse transcription-quantitative polymerase chain reaction and western blot analyses. Cell viability following treatment in each group was evaluated using a Cell Counting Kit-8 assay subsequent to treatment with 3 μM cisplatin. The cell cycle and apoptotic rate of the BIU87-CisR cells were analyzed using flow cytometry. Finally, maspin-overexpressing BIU87-CisR cells were used to confirm the effect of maspin on the sensitivity of the cells to cisplatin. The expression levels of IGFBP-2 in chemoresistant patients and BIU87-CisR cells were significantly increased, compared with those in the chemosensitive patients and BIU87 cells, respectively. However, the expression levels of maspin were lower in the cisplatin-resistant tissue and cells, and was enhanced by IGFBP-2 inhibition. Cisplatin (3 μM) caused marked proliferation inhibition, cell cycle arrest and apoptosis of the BIU87-CisR cells, the effect of which was enhanced by IGFBP-2 silencing. Overexpression of maspin also improved the sensitivity of the BIU87-CisR cells to cisplatin. In conclusion, inhibition of IGFBP-2 improved the sensitivity of bladder cancer cells to cisplatin by elevating the expression of maspin.

Novel anti IGFBP2 single chain variable fragment inhibits glioma cell migration and invasion

Insulin like growth factor binding protein 2 (IGFBP2) is highly up regulated in glioblastoma (GBM) tissues and has been one of the prognostic indicators. There are compelling evidences suggesting important roles for IGFBP2 in glioma cell proliferation, migration and invasion. Extracellular IGFBP2 through its carboxy terminal arginine glycine aspartate (RGD) motif can bind to cell surface α5β1 integrins and activate pathways downstream to integrin signaling. This IGFBP2 activated integrin signaling is known to play a crucial role in IGFBP2 mediated invasion of glioma cells. Hence a molecular inhibitor of carboxy terminal domain of IGFBP2 which can inhibit IGFBP2-cell surface interaction is of great therapeutic importance. In an attempt to develop molecular inhibitors of IGFBP2, we screened single chain variable fragment (scFv) phage display libraries, Tomlinson I (Library size 1.47 × 10(8)) and Tomlinson J (Library size 1.37 × 10(8)) using human recombinant IGFBP2. After screening we obtained three IGFBP2 specific binders out of which one scFv B7J showed better binding to IGFBP2 at its carboxy terminal domain, blocked IGFBP2-cell surface association, reduced activity of matrix metalloprotease 2 in the conditioned medium of glioma cells and inhibited IGFBP2 induced migration and invasion of glioma cells. We demonstrate for the first time that in vitro inhibition of extracellular IGFBP2 activity by using human scFv results in significant reduction of glioma cell migration and invasion. Therefore, the inhibition of IGFBP2 can serve as a potential therapeutic strategy in the management of GBM.

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

The activity of the Insulin-like Growth Factors (IGFs) ligands elicited via their receptors and transduced by various intracellular signal pathways is modulated by the IGF Binding Proteins (IGFBPs). Among all the IGFBPs, IGFBP-2 has been implicated in the regulation of IGF activity in most tissue and organs. Besides binding to IGFs in the circulation these IGF-regulatory activities of IGFBP-2 involve interactions with components of the extracellular matrix, cell surface proteoglycans and integrin receptors. In addition to these local peri-cellular activities, IGFBP-2 exerts other key functions within the nucleus, where IGFBP-2 directly or indirectly promotes transcriptional activation of specific genes. All of these IGFBP-2 activities, intrinsic or dependent on IGFs, contribute to its functional roles in growth/development, metabolism and malignancy as evidenced by studies in IGFBP-2 animal models and also by many in vitro studies. Finally, preclinical studies have demonstrated that IGFBP-2 administration can be beneficial in improving metabolic responses (inhibition of adipogenesis and enhanced insulin sensitivity), while blockade of IGFBP-2 appears to be an effective approach to inhibiting tumour growth and metastasis.

IGF-Binding Protein 2 - Oncogene or Tumor Suppressor?

The role of insulin-like growth factor binding protein 2 (IGFBP2) in cancer is unclear. In general, IGFBP2 is considered to be oncogenic and its expression is often observed to be elevated in cancer. However, there are a number of conflicting reports in vitro and in vivo where IGFBP2 acts in a tumor suppressor manner. In this mini-review, we discuss the factors influencing the variation in IGFBP2 expression in cancer and our interpretation of these findings.

Proteomic analysis of human vitreous humor

Background

The vitreous humor is a transparent, gelatinous mass whose main constituent is water. It plays an important role in providing metabolic nutrient requirements of the lens, coordinating eye growth and providing support to the retina. It is in close proximity to the retina and reflects many of the changes occurring in this tissue. The biochemical changes occurring in the vitreous could provide a better understanding about the pathophysiological processes that occur in vitreoretinopathy. In this study, we investigated the proteome of normal human vitreous humor using high resolution Fourier transform mass spectrometry.

Results

The vitreous humor was subjected to multiple fractionation techniques followed by LC-MS/MS analysis. We identified 1,205 proteins, 682 of which have not been described previously in the vitreous humor. Most proteins were localized to the extracellular space (24%), cytoplasm (20%) or plasma membrane (14%). Classification based on molecular function showed that 27% had catalytic activity, 10% structural activity, 10% binding activity, 4% cell and 4% transporter activity. Categorization for biological processes showed 28% participate in metabolism, 20% in cell communication and 13% in cell growth. The data have been deposited to the ProteomeXchange with identifier PXD000957.

Conclusion

This large catalog of vitreous proteins should facilitate biomedical research into pathological conditions of the eye including diabetic retinopathy, retinal detachment and cataract.

Is insulin-like growth factor binding protein 2 associated with metastasis in lung cancer?

Insulin-like growth factor binding protein 2 (IGFBP2) is involved in the progression of many epithelial cancers. However, its role in non-small cell lung cancer (NSCLC), another type of epithelial cancer, remains unclear. We detected IGFBP2 expression using immunohistochemistry in surgically resected tumors from 110 NSCLC patients, 37 of which had metastases. The positive rate of IGFBP2 expression was compared between the metastatic and the non-metastatic group, and correlations of IGFBP2 expression with metastasis and overall survival were analyzed. We also investigated the expression of IGFBP2 in microvesicles (MVs) collected from primary lung cancer cell cultures, and in different locations of newly resected NSCLC tumors, using immunoblotting. The overall positive rate of IGFBP2 expression in lung cancer was 51.8 % and it was significantly higher in the metastatic group than in the non-metastatic group (70.3 and 42.5 % respectively, p < 0.01). And the higher the lymph node stage, the higher the positive rate. Cytoplasmic expression was predominant in the majority of the tumors. Based on multivariate regression analysis, IGFBP2 was correlated with metastasis and poor overall survival (Hazard ratio: 3.56 and 3.23 respectively). IGFBP2 was detectable in the MVs collected from IGFBP2 positive cell lines, and its expression was most abundant in the marginal region of the newly resected tumors. IGFBP2 is associated with metastasis and poor survival of lung cancer. Its presence in MVs and high abundance in the marginal region of tumors suggest that its association with metastasis may be related to tumor microenviroment remodeling in NSCLC.

IGF binding protein 2 is a cell-autonomous factor supporting survival and migration of acute leukemia cells

BACKGROUND

The role of IGF binding protein 2 (IGFBP2) in cancer development is intriguing. Previously we identified IGFBP2 as an extrinsic factor that supports the activity of hematopoietic stem cells (HSCs).

METHODS AND RESULTS

Here we investigated the role of IGFBP2 in in human leukemia cells and in the retroviral AML1-ETO9a transplantation acute myeloid leukemia (AML) mouse model.

RESULTS

IGFBP2 is highly expressed in certain human AML and acute lymphoblastic leukemia (ALL) cells. Inhibition of expression of endogenous IGFBP2 in human leukemia cells led to elevated apoptosis and decreased migration and, consistently, to decreased activation of AKT and other signaling molecules. We also studied the effects of IGFBP2 knockout in the retroviral AML1-ETO9a transplantation AML mouse model. The deletion of IGFBP2 in donor AML cells significantly decreased leukemia development in transplanted mice. Lack of IGFBP2 resulted in upregulation of PTEN expression and downregulation of AKT activation, in the mouse AML cells. The treatment of IGFBP2 deficient AML cells with a PTEN inhibitor restored the wild-type colony forming ability. The deletion of IGFBP2 also led to decreased AML infiltration into peripheral organs and tissues, suggesting that IGFBP2 is required for the migration of AML cells out of bone marrow.

CONCLUSION

IGFBP2 is a critical cell-autonomous factor that promotes the survival and migration of acute leukemia cells.

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.

Insulin-like growth factor binding protein 2 (IGFBP-2) promotes growth and survival of breast epithelial cells: novel regulation of the estrogen receptor

In breast tumors IGF binding protein-2 (IGFBP-2) is elevated, and the presence of IGFBP-2 has been shown to correlate with malignancy. However, how IGFBP-2 contributes to the malignant state is still unclear. Silencing IGFBP-2 blocked cell proliferation and in MCF-7 cells increased cell death, indicating that IGFBP-2 was acting in both a mitogenic and a survival capacity. Exogenous IGFBP-2 acting via integrin receptors to reduce phosphatase and tensin homolog deleted from chromosome 10 (PTEN) levels protected these cells against death induced by various chemotherapeutic agents. This was dependent on a functional estrogen receptor (ER)-α because silencing ER-α blocked the ability of IGFBP-2 to confer cell survival. Loss of IGFBP-2 increased levels of PTEN and improved chemosensitivity of the cells, confirming its role as a survival factor. Silencing IGFBP-2 had no effect on the response to IGF-II, but responses to estrogen and tamoxifen were no longer observed due to loss of ER-α, which could be prevented by the inhibition of PTEN. Conversely, exogenous IGFBP-2 increased ER-α mRNA and protein in both normal and cancer cells via its interaction with integrin receptors. These actions of IGFBP-2 on ER-α involved the IGF-I receptor and activation of phosphatidylinositol 3-kinase in the cancer cells but were independent of this in normal breast cells. The production of IGFBP-2 by breast cancer cells enhances their proliferative potential, increases their survival, and protects them against chemotherapy-induced death. IGFBP-2 not only modulates IGFs and directly regulates PTEN but also has a role in maintaining ER-α expression.

Autoantibodies against insulin-like growth factor‑binding protein-2 as a serological biomarker in the diagnosis of lung cancer

Insulin-like growth factor-binding protein-2 (IGFBP-2) is considered to be a human tumor antigen, and the tumor-specific immunity of IGFBP-2 has been reported in several types of cancer. The purpose of this study was to evaluate whether autoantibodies to IGFBP-2 can be used as diagnostic markers in lung cancer. The results demonstrated that serum anti-IGFBP-2 autoantibody levels were significantly elevated in lung cancer (mean, 1,633.318 ng/ml; median, 1,651.462 ng/ml; range, 342.732–4932.582 ng/ml) compared with benign lung disease (1,210.139, 1,035.900, 547.596–2,331.167 ng/ml) and normal controls (1,303.369, 1,194.800, 528.200–2140.500 ng/ml). The sensitivity and specificity of anti-IGFBP-2 autoantibodies in diagnosing lung cancer was 73.2 and 60.6%, respectively. When serum IGFBP-2 and anti-IGFBP-2 autoantibody were used together in the diagnosis of lung cancer, it can increase the discriminative power for lung cancer with a sensitivity of 85.7% and a specificity of 57.5%. In conclusion, this study demonstrates that circulating anti-IGFBP-2 autoantibodies can be used as a potential biomarker in diagnosing lung cancer.

Protein signature of lung cancer tissues

Lung cancer remains the most common cause of cancer-related mortality. We applied a highly multiplexed proteomic technology (SOMAscan) to compare protein expression signatures of non small-cell lung cancer (NSCLC) tissues with healthy adjacent and distant tissues from surgical resections. In this first report of SOMAscan applied to tissues, we highlight 36 proteins that exhibit the largest expression differences between matched tumor and non-tumor tissues. The concentrations of twenty proteins increased and sixteen decreased in tumor tissue, thirteen of which are novel for NSCLC. NSCLC tissue biomarkers identified here overlap with a core set identified in a large serum-based NSCLC study with SOMAscan. We show that large-scale comparative analysis of protein expression can be used to develop novel histochemical probes. As expected, relative differences in protein expression are greater in tissues than in serum. The combined results from tissue and serum present the most extensive view to date of the complex changes in NSCLC protein expression and provide important implications for diagnosis and treatment.

Targeting the insulin-like growth factor receptor pathway in lung cancer: problems and pitfalls

The insulin-like growth factor (IGF) pathway is a complex pathway involving interactions between membrane-bound receptors, ligands, binding proteins, downstream effectors, and other receptor tyrosine kinase signaling cascades. The IGF pathway has been identified as a potential therapeutic target in non-small cell lung cancer (NSCLC) based on the following provocative factors. Preclinical observations in NSCLC have shown that this pathway is involved in tumor cell proliferation, survival, and invasiveness. In addition, IGF-1R protein expression is found in a significant number of non-small cell tumor specimens. Initial therapeutic efforts involved the development of monoclonal antibodies and tyrosine kinase inhibitors that target IGF-1R, a transmembrane receptor tyrosine kinase. Enthusiasm for targeting this pathway increased when a randomized phase II study showed that combining an anti-IGF-1R monoclonal antibody (figitumumab) with a platinum doublet resulted in a higher response rate and trends for superior progression-free survival and overall survival. Subsequently, a phase III study failed to confirm the promising results observed in the phase II trial. Currently, investigators are studying different monoclonal antibodies and tyrosine kinases targeting IGF-1R. In unselected patients, results presented thus far do not suggest efficacy of this agent. However, retrospective subgroup analyses suggest that circulating IGF-1 levels might identify patients who could benefit from treatment with an IGF-1R monoclonal antibody and may warrant further exploratory studies for predictive molecular markers. The purpose of this paper is to briefly discuss the IGF pathway and its relationship with other signaling pathways in lung cancer and to review the ongoing IGF clinical trials and efforts to identify predictive molecular markers.

Aberrant expression of proteins involved in signal transduction and DNA repair pathways in lung cancer and their association with clinical parameters

BACKGROUND

Because cell signaling and cell metabolic pathways are executed through proteins, protein signatures in primary tumors are useful for identifying key nodes in signaling networks whose alteration is associated with malignancy and/or clinical outcomes. This study aimed to determine protein signatures in primary lung cancer tissues.

METHODOLOGY/ PRINCIPAL FINDINGS

We analyzed 126 proteins and/or protein phosphorylation sites in case-matched normal and tumor samples from 101 lung cancer patients with reverse-phase protein array (RPPA) assay. The results showed that 18 molecules were significantly different (p<0.05) by at least 30% between normal and tumor tissues. Most of those molecules play roles in cell proliferation, DNA repair, signal transduction and lipid metabolism, or function as cell surface/matrix proteins. We also validated RPPA results by Western blot and/or immunohistochemical analyses for some of those molecules. Statistical analyses showed that Ku80 levels were significantly higher in tumors of nonsmokers than in those of smokers. Cyclin B1 levels were significantly overexpressed in poorly differentiated tumors while Cox2 levels were significantly overexpressed in neuroendocrinal tumors. A high level of Stat5 is associated with favorable survival outcome for patients treated with surgery.

CONCLUSIONS/ SIGNIFICANCE

Our results revealed that some molecules involved in DNA damage/repair, signal transductions, lipid metabolism, and cell proliferation were drastically aberrant in lung cancer tissues, and Stat5 may serve a molecular marker for prognosis of lung cancers.

IGF binding protein 2 supports the survival and cycling of hematopoietic stem cells

The role of IGF binding protein 2 (IGFBP2) in cell growth is intriguing and largely undefined. Previously we identified IGFBP2 as an extrinsic factor that supports ex vivo expansion of hematopoietic stem cells (HSCs). Here we showed that IGFBP2-null mice have fewer HSCs than wild-type mice. While IGFBP2 has little cell-autonomous effect on HSC function, we found decreased in vivo repopulation of HSCs in primary and secondary transplanted IGFBP2-null recipients. Importantly, bone marrow stromal cells that are deficient for IGFBP2 have significantly decreased ability to support the expansion of repopulating HSCs. To investigate the mechanism by which IGFBP2 supports HSC activity, we demonstrated that HSCs in IGFBP2-null mice had decreased survival and cycling, down-regulated expression of antiapoptotic factor Bcl-2, and up-regulated expression of cell cycle inhibitors p21, p16, p19, p57, and PTEN. Moreover, we found that the C-terminus, but not the RGD domain, of extrinsic IGFBP2 was essential for support of HSC activity. Defective signaling of the IGF type I receptor did not rescue the decreased repopulation of HSCs in IGFBP2-null recipients, suggesting that the environmental effect of IGFBP2 on HSCs is independent of IGF-IR mediated signaling. Therefore, as an environmental factor, IGFBP2 supports the survival and cycling of HSCs.