Insulin-like growth factor (IGF)-binding protein-3 mutants that do not bind IGF-I or IGF-II stimulate apoptosis in human prostate cancer cells

Insulin-like growth factor family and prostate cancer: new insights and emerging opportunities

Prostate cancer is the second most commonly diagnosed cancer in men. The mammalian insulin-like growth factor (IGF) family is made up of three ligands (IGF-I, IGF-II, and insulin), three receptors (IGF-I receptor (IGF-1R), insulin receptor (IR), and IGF-II receptor (IGF-2R)), and six IGF-binding proteins (IGFBPs). IGF-I and IGF-II were identified as potent mitogens and were previously associated with an increased risk of cancer development including prostate cancer. Several reports showed controversy about the expression of the IGF family and their connection to prostate cancer risk due to the high degree of heterogeneity among prostate tumors, sampling bias, and evaluation techniques. Despite that, it is clear that several IGF family members play a role in prostate cancer development, metastasis, and androgen-independent progression. In this review, we aim to expand our understanding of prostate tumorigenesis and regulation through the IGF system. Further understanding of the role of IGF signaling in PCa shows promise and needs to be considered in the context of a comprehensive treatment strategy.

Plasmodium vivax tryptophan-rich antigen reduces type I collagen secretion via the NF-κBp65 pathway in splenic fibroblasts

BACKGROUND

The spleen plays a critical role in the immune response against malaria parasite infection, where splenic fibroblasts (SFs) are abundantly present and contribute to immune function by secreting type I collagen (collagen I). The protein family is characterized by Plasmodium vivax tryptophan-rich antigens (PvTRAgs), comprising 40 members. PvTRAg23 has been reported to bind to human SFs (HSFs) and affect collagen I levels. Given the role of type I collagen in splenic immune function, it is important to investigate the functions of the other members within the PvTRAg protein family.

METHODS

Protein structural prediction was conducted utilizing bioinformatics analysis tools and software. A total of 23 PvTRAgs were successfully expressed and purified using an Escherichia coli prokaryotic expression system, and the purified proteins were used for co-culture with HSFs. The collagen I levels and collagen-related signaling pathway protein levels were detected by immunoblotting, and the relative expression levels of inflammatory factors were determined by quantitative real-time PCR.

RESULTS

In silico analysis showed that P. vivax has 40 genes encoding the TRAg family. The C-terminal region of all PvTRAgs is characterized by the presence of a domain rich in tryptophan residues. A total of 23 recombinant PvTRAgs were successfully expressed and purified. Only five PvTRAgs (PvTRAg5, PvTRAg16, PvTRAg23, PvTRAg30, and PvTRAg32) mediated the activation of the NF-κBp65 signaling pathway, which resulted in the production of inflammatory molecules and ultimately a significant reduction in collagen I levels in HSFs.

CONCLUSIONS

Our research contributes to the expansion of knowledge regarding the functional role of PvTRAgs, while it also enhances our understanding of the immune evasion mechanisms utilized by parasites.

Fluoroquinolones upregulate insulin-like growth factor-binding protein 3, inhibit cell growth and insulin-like growth factor signaling

Fluoroquinolones (FQs), commonly known for their antibiotic properties, exhibit additional pharmacological potential with anti-proliferative effects on various malignant cell types and immunomodulatory responses. Despite these observed effects, the precise mechanisms of action remain elusive. This study elucidates the biological impact of FQs on insulin-like growth factor-binding protein 3 (IGFBP-3) productions in a p53-dependent manner. Cultured cells and mouse models treated with FQs demonstrated increased IGFBP-3 mRNA expression and protein secretion. The FQ-induced IGFBP-3 was identified to impede cell growth by inhibiting IGF-I signaling and exerting effects through an IGF-independent pathway. Notably, FQ-mediated suppression of cell proliferation was reversed in p53-null and p53 knockdown cells, suggesting the pivotal role of p53 in FQ-induced IGFBP-3 production and IGFBP-3-mediated growth inhibition. Additionally, ciprofloxacin, a clinically used FQ, exhibited the induction of tumor cell apoptosis and attenuation of tumor growth in a syngeneic mouse hepatocellular carcinoma (HCC) model. These findings unveil a novel mechanism through which FQs act as anti-proliferative agents, prompting further exploration of their potential utility or derivative compounds in cancer treatment and prevention.

Sleep disorders and prostate cancer prognosis: biology, epidemiology, and association with cancer development risk

Sleep is crucial for the maintenance of health and well-being. Sleep disorders can result in physiological consequences and are associated with several health issues, including cancer. Cancer is one of the most significant health problems in the world. In Western countries, prostate cancer is the most prevalent noncutaneous cancer among men. Epidemiological studies showed that one in nine men will have this disease during their life. Many factors influence prostate cancer and the tumor niche, including endogenous hormones, family history, diet, and gene mutations. Disruption of the circadian cycle by sleep disorders or other factors has been suggested as a novel and important risk factor for prostate cancer and its tumorigenesis. This review presents information regarding the epidemiological and biological aspects of prostate cancer, and discusses the impact of sleep physiology and sleep disorders on this type of cancer, highlighting possible associations with risk of cancer development.

CCNI2 promotes the progression of human gastric cancer through HDGF

BACKGROUND

Gastric cancer is a highly aggressive malignant tumor with heterogeneity and is still a global health problem. The present study aimed to investigate the role of Cyclin I-like (CCNI2) in the regulation of phenotype and tumorigenesis, as well as its underlying mechanisms.

METHOD

The expression profile of CCNI2 in gastric cancer was determined based on The Cancer Genome Atlas (TCGA) database and immunohistochemical staining. The effects of altered CCNI2 expression on the biological phenotypes such as proliferation, clone formation, apoptosis and migration of gastric cancer cell lines BGC-823 and SGC-7901 were investigated. Mice xenograft models were established to reveal the role of CCNI2 knockdown on tumorigenesis. The potential mechanism of CCNI2 regulating gastric cancer was preliminarily determined by RNA sequencing.

RESULT

CCNI2 was abundantly expressed in gastric cancer and was positively correlated with pathological stage. Knockdown of CCNI2 slowed down the malignant progression of gastric cancer by inhibiting tumor cell proliferation, increasing the susceptibility to apoptosis and suppressing migration. Moreover, downregulation of CCNI2 attenuated the ability of gastric cancer cells to form tumors in mice. Additionally, there was an interaction between CCNI2 and transcription factor hepatoma-derived growth factor (HDGF) in SGC-7901 cells. Knockdown of CCNI2 alleviated the promoting effects of HDGF overexpression in gastric cancer cells.

CONCLUSIONS

CCNI2 promoted the progression of human gastric cancer through HDGF, which drew further interest regarding its clinical application as a potential therapeutic target.

IGFBP3 gene promoter methylation analysis and its association with clinicopathological characteristics of colorectal carcinoma

Promoter methylation mediated silencing of tumor suppressor genes plays an important role in the tumorigenesis of colorectal carcinoma (CRC). Tumor suppressor gene, Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) expression is frequently downregulated in CRC due to promoter methylations. The aim of this study was to analyze the methylation status of IGFBP-3 gene promoter in stage II and III of CRC cases; find its association with clinicopathological characteristics of CRC patients and the methylation patterns as a prognostic biomarker. 58 histopathologically confirmed cases of CRC were included in the study. Methylation status of IGFBP-3 gene promoter was determined by using methylation specific PCR (MS-PCR) and bisulfite sequencing. Kaplan-Meier survival curve and univariate cox regression analysis were used for survival analysis; Chi-square test used for association analysis. IGFBP3 promoter methylation was found in 37 (63.8%) out of 58 CRC cases. This promoter methylation status was significantly associated with lymph-node metastasis (P = 0.013) and the survival period. In stage II CRC cases, unmethylated gene promoter status showed better survival than the methylated. Mean overall survival (OS) of methylated and unmethylated group was 22.23 months, and 49.15 months respectively (P = 0.045), HR = 6.432, 95% CI 0.986-41.943. The IGFBP-3 promoter methylations found in 63.8% CRC cases in this study. The methylations was found to be associated with lymph-node metastasis and overall survival of the patients particularly in stage II CRC patients. However, promoter methylation was not associated with other clinocopathological characteristics such as age, gender, tumor location etc.

Insulin-like growth factor binding protein 3 gene of golden pompano (TroIGFBP3) promotes antimicrobial immune defense

Insulin-like growth factor binding protein 3 (IGFBP3), an important member of the IGFBP family, plays an important biological role in regulating cellular proliferation, differentiation, growth, apoptosis, and innate immunity. However, studies concerning IGFBP3 in teleosts are very limited and IGFBP3 function remains unclear. In this study, we conducted both in vivo and in vitro functional analyses of an IGFBP3 (TroIGFBP3) from the teleost fish golden pompano (Trachinotus ovatus). TroIGFBP3 is composed of 286 amino acid residues and shares a high amino acid sequence similarity (50.18%-93.71%) with other IGFBP3 sequences in humans and teleosts. TroIGFBP3 was widely distributed in various tissues, with the highest expression in the liver. TroIGFBP3 expression was significantly upregulated following Vibrio harveyi infection. The results of in vitro assays showed that TroIGFBP3 could stimulate macrophage activation and promote peripheral blood leukocytes (PBLs) proliferation. Meanwhile, TroIGFBP3 overexpression significantly inhibited bacterial infection in fish tissues, whereas TroIGFBP3 knockdown resulted in increased bacterial dissemination and colonization in golden pompano tissues in vivo. Furthermore, recombinant TroIGFBP3 could inhibit cellular proliferation and promote apoptosis of mouse tumor cells. Taken together, these results indicated that TroIGFBP3 plays a significant role in innate antibacterial immunity and provides a theoretical foundation for investigating the function of IGFBP3 in fish immune response.

Salvianolic acid B improves myocardial function in diabetic cardiomyopathy by suppressing IGFBP3

BACKGROUND

Salvianolic acid B (Sal B) is the representative component of phenolic acids derived from the dried root and rhizome of Salvia miltiorrhiza Bge. (Labiatae), which has been widely used for the treatment of cardiovascular and cerebrovascular diseases. However, the effect of Sal B on diabetic cardiomyopathy (DCM) is still unclear.

METHODS

Type 1 diabetes mellitus was induced in C57BL/6 J mice by streptozotocin (STZ) treatment, whereas meanwhile Salvianolic Acid B (Sal B (15 or 30 mg/kg/d) was intraperitoneally injected for 16 weeks. At the end of this period, cardiac function was assessed by echocardiography, and total collagen deposition was evaluated by Masson's trichrome and Picrosirius Red staining. Human umbilical vein endothelial cells exposed to hypoxia were used to investigate the effect of different doses of Sal B on angiogenesis and tube formation in vitro. Transcriptome sequencing was performed to identify potential targets of Sal B.

RESULTS

Sal B ameliorated left ventricular dysfunction and remodeling, and decreased collagen deposition in the heart of diabetic mice. Administration of Sal B increased the expression of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) and VEGFA in a dose-dependent manner and promoted angiogenesis both in vivo and in vitro. Furthermore, Sal B reduced HG-induced insulin-like growth factor-binding protein 3 (IGFBP3) expression, induced the phosphorylation of extracellular signal-regulated protein kinase and protein kinase B (AKT) activities, enhanced cell proliferation, and activated VEGFR2/VEGFA signaling in endothelial cells. The underlying mechanisms involve SalB that enhances IGFBP3 promoter DNA methylation and induce nuclear translocation of IGFBP3 in HUVECs under hypoxia.

CONCLUSIONS

Sal B promoted angiogenesis and alleviated cardiac fibrosis and cardiac remodeling in DCM by suppressing IGFBP3.

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

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

ROS- and HIF1α-dependent IGFBP3 upregulation blocks IGF1 survival signaling and thereby mediates high-glucose-induced cardiomyocyte apoptosis

The prevalence of chronic hyperglycemia and its complications, imposing a critical burden on the worldwide economy and the global healthcare system, is a pressing issue. Mounting evidence indicates that oxidative stress and hypoxia, two noticeable features of hyperglycemia, play a joint crucial role in mediating cellular apoptosis. However, the underlying detailed molecular mechanism remains elusive. Triggered by the observation that insulin-like growth factor (IGF1)-binding protein 3 (IGFBP3) can mediate, in renal cells, high-glucose-induced apoptosis by elevating oxidative stress, we wish to, in this study, know whether or not the similar scenario holds in cardiac cells and, if so, to find its relevant molecular key players, thereby dissecting the underlying molecular pathway. Specifically, we used a combination of three different cellular sources (H9c2 cells, diabetic rats, and neonatal rat ventricular cardiomyocytes) as our model systems of study. We made use of Co-IP assay and western blot analysis in conjunction with loss-of-function reasoning, gain-of-function logic, and inhibitor treatment as our main analytical tools. As a result, briefly, our main findings are that hyperglycemia can induce cardiac IGFBP3 overexpression and secretion, that high levels of IGFBP3 can sequester IGF1 from IGF1 survival pathway, leading to apoptosis, and that IGFBP3 gene upregulation is hypoxia-inducible factor (HIF)1α-dependent and reactive oxygen species dependent. Piecing these findings together allows us to propose the improved molecular regulatory mechanism. In conclusion, we have established the molecular roles of IGFBP3, HIF1, and prolyl hydroxylase domain in connecting oxidative stress with hypoxia and in cellular apoptosis under hyperglycemia.

In silico interaction of insulin-like growth factor binding protein 3 with insulin-like growth factor 1

Insulin-like growth factor binding protein-3 (IGFBP-3) is a vital protein exist in circulation which interacts with high affinity to insulin-like growth factor (IGFs) altering their activities. Therefore, the interaction between IGFs and IGFBP-3 has a key role altering large spectrum of activities such as cell cycle progression, proliferation and apoptosis. Despite decades of research, the crystal structure of IGFBP-3 has not been identified possibly due to some technical challenge in its crystallizing. The three-dimensional (3D) structure of IGFBP-3 was predicted using homology modeling, Phyre2, and molecular dynamic. Its interaction with IGF-1 was also identified by HADDOCK software. IGFBP-3 has the most identity with other IGFBPs in N and C-domain; however, its linker domain has lower identity. Our data predicted that IGF-1 structurally interacts with N-domain and linker domain of IGFBP-3. Some conserved residues of IGFBP-3 such as Glu33, Arg36, Gly39, Arg60, Arg66, Asn109, and Ile146 interacts with Glu3, Asp12, Phe16, Gly19, Asp20, Arg21, and Glu58 of IGF-1. In addition, our data predict that the linker domain has a loop structure which covers post translational modification and interacts with IGF-1. The phosphorylation of Ser111 in linker domain, which previously has been shown to induce apoptosis make a repulsive force interrupting this interaction to IGF-1, which enables IGFBP-3 to induce apoptosis. The present study suggests that the linker domain has a key role in recognition of IGFBP-3 with IGF-1.

Associations of alcohol intake, smoking, physical activity and obesity with survival following colorectal cancer diagnosis by stage, anatomic site and tumor molecular subtype

The influence of lifestyle factors on survival following a diagnosis of colorectal cancer (CRC) is not well established. We examined associations between lifestyle factors measured before diagnosis and CRC survival. The Melbourne Collaborative Cohort Study collected data on alcohol intake, cigarette smoking and physical activity, and body measurements at baseline (1990-1994) and wave 2 (2003-2007). We included participants diagnosed to 31 August 2015 with incident stages I-III CRC within 10-years post exposure assessment. Information on tumor characteristics and vital status was obtained. Tumor DNA was tested for microsatellite instability (MSI) and somatic mutations in oncogenes BRAF (V600E) and KRAS. We estimated hazard ratios (HRs) for associations between lifestyle factors and overall and CRC-specific mortality using Cox regression. Of 724 eligible CRC cases, 339 died (170 from CRC) during follow-up (average 9.0 years). Exercise (non-occupational/leisure-time) was associated with higher CRC-specific survival for stage II (HR = 0.25, 95% CI: 0.10-0.60) but not stages I/III disease (p for interaction = 0.01), and possibly for colon and KRAS wild-type tumors. Waist circumference was inversely associated with CRC-specific survival (HR = 1.25 per 10 cm increment, 95% CI: 1.08-1.44), independent of stage, anatomic site and tumor molecular status. Cigarette smoking was associated with lower overall survival, with suggestive evidence of worse survival for BRAF mutated CRC, but not with CRC-specific survival. Alcohol intake was not associated with survival. Survival did not differ by MSI status. We have identified pre-diagnostic predictors of survival following CRC that may have clinical and public health relevance.

Understanding Insulin Endocrinology in Decapod Crustacea: Molecular Modelling Characterization of an Insulin-Binding Protein and Insulin-Like Peptides in the Eastern Spiny Lobster, Sagmariasus verreauxi

The insulin signalling system is one of the most conserved endocrine systems of Animalia from mollusc to man. In decapod Crustacea, such as the Eastern spiny lobster, Sagmariasus verreauxi (Sv) and the red-claw crayfish, Cherax quadricarinatus (Cq), insulin endocrinology governs male sexual differentiation through the action of a male-specific, insulin-like androgenic gland peptide (IAG). To understand the bioactivity of IAG it is necessary to consider its bio-regulators such as the insulin-like growth factor binding protein (IGFBP). This work has employed various molecular modelling approaches to represent S. verreauxi IGFBP and IAG, along with additional Sv-ILP ligands, in order to characterise their binding interactions. Firstly, we present Sv- and Cq-ILP2: neuroendocrine factors that share closest homology with Drosophila ILP8 (Dilp8). We then describe the binding interaction of the N-terminal domain of Sv-IGFBP and each ILP through a synergy of computational analyses. In-depth interaction mapping and computational alanine scanning of IGFBP_N' highlight the conserved involvement of the hotspot residues Q₆₇, G₇₀, D₇₁, S₇₂, G₉₁, G₉₂, T₉₃ and D₉₄. The significance of the negatively charged residues D₇₁ and D₉₄ was then further exemplified by structural electrostatics. The functional importance of the negative surface charge of IGFBP is exemplified in the complementary electropositive charge on the reciprocal binding interface of all three ILP ligands. When examined, this electrostatic complementarity is the inverse of vertebrate homologues; such physicochemical divergences elucidate towards ligand-binding specificity between Phyla.

Involvement of p53 in insulin-like growth factor binding protein-3 regulation in the breast cancer cell response to DNA damage

Chemotherapy drugs that induce apoptosis by causing DNA double-strand breaks, upregulate the tumor suppressor p53. This study investigated the regulation of the growth-regulatory protein insulin-like growth factor binding protein-3 (IGFBP-3), a p53 target, by DNA-damaging agents in breast cancer cells. IGFBP-3 was upregulated 1.4- to 13-fold in response to doxorubicin and etoposide in MCF-10A, Hs578T, MCF-7 and T47D cells, which express low to moderate basal levels of IGFBP-3. In contrast, IGFBP-3 was strongly downregulated by these agents in cells with high basal levels of IGFBP-3 (MDA-MB-231, MDA-MB-436 and MDA-MB-468). In MDA-MB-468 cells containing the R273H p53 mutation, reported to display gain-of-function properties, chemotherapy-induced suppression of IGFBP-3 was not reversed by the p53 reactivating drug, PRIMA-1, or by p53 silencing, suggesting that the decrease in IGFBP-3 following DNA damage is not a mutant p53 gain-of-function response. SiRNA-mediated downregulation of endogenous IGFBP-3 modestly attenuated doxorubicin-induced apoptosis in MDA-MB-468 and Hs578T cells. IGFBP-3 downregulation in some breast cancer cell lines in response to DNA-damaging chemotherapy may have clinical implications because suppression of IGFBP-3 may modulate the apoptotic response. These observations provide further evidence that endogenous IGFBP-3 plays a role in breast cancer cell responsiveness to DNA damaging therapy.

Physical activity as a risk factor for prostate cancer diagnosis: a prospective biopsy cohort analysis

OBJECTIVES

To assess the association between physical activity, evaluated by the Physical Activity Scale for the Elderly (PASE) questionnaire, and prostate cancer risk in a consecutive series of men undergoing prostate biopsy.

PATIENTS AND METHOD

From 2011 onwards, consecutive men undergoing 12-core prostate biopsy were enrolled into a prospective database. Indications for a prostatic biopsy were a prostate-specific antigen (PSA) value of ≥4 ng/mL and/or a positive digital rectal examination. Body mass index (BMI) and waist circumferences were measured before the biopsy. Fasting blood samples were collected before biopsy and tested for: total PSA, glucose, high-density lipoprotein cholesterol, and trygliceride levels. Blood pressure was recorded. Metabolic syndrome (MetS) was defined according to the Adult Treatment panel III. The PASE questionnaire was completed before the biopsy.

RESULTS

In all, 286 patients were enrolled with a median (interquartile range, IQR) age and PSA level of 68 (62-74) years and 6.1 (5-8.8) ng/mL, respectively. The median (IQR) BMI was 26.4 (24.6-29) kg/m(2) and waist circumference was 102 (97-108) cm, with 75 patients (26%) presenting with MetS. In all, 106 patients (37%) had prostate cancer at biopsy. Patients with prostate cancer had higher PSA levels (median [IQR] 6.7 [5-10] vs 5.6 [4.8-8] ng/mL; P = 0.007) and lower LogPASE scores (median [IQR] 2.03 [1.82-2.18] vs 2.10 [1.92-2.29]; P = 0.005). On multivariate analysis, in addition to well-recognised risk factors such as age, PSA level and prostate volume, LogPASE score was an independent risk factor for prostate cancer diagnosis (odds ratio [OR] 0.146, 95% confidence interval [CI] 0.037-0.577; P = 0.006]. LogPASE score was also an independent predictor of high-grade cancer (OR 0.07, 95% CI 0.006-0.764; P = 0.029).

CONCLUSION

In our single-centre study, increased physical activity, evaluated by the PASE questionnaire, is associated with a reduced risk of prostate cancer and of high-grade prostate cancer at biopsy. Further studies should clarify the molecular pathways behind this association.

Germ line knockout of IGFBP-3 reveals influences of the gene on mammary gland neoplasia

Insulin-like growth factor binding protein-3 (IGFBP-3) is an important carrier protein for insulin-like growth factors (IGFs) in the circulation. IGFBP-3 antagonizes the growth-promoting and anti-apoptotic activities of IGFs in experimental systems, but in certain contexts can increase IGF bioactivity, probably by increasing its half-life. The goal of this study was to investigate the role of IGFBP-3 in breast carcinogenesis and breast cancer metastasis. In the first part of the study, we exposed IGFBP-3 knockout and wild-type female mice to dimethylbenz[a]anthracene (DMBA) and followed them for appearance of primary tumors for up to 13 months. In the second part, mice of each genotype received an IV injection of 4T1 mammary carcinoma cells and then lung nodules were counted. Our results show that IGFBP-3 knockout mice developed breast tumors significantly earlier than the wild-type (13.9 ± 1.1 versus 22.5 ± 3.3 weeks, respectively, P = 0.0144), suggesting tumor suppression activity of IGFBP-3. In tumors of IGFBP-3 knockout mice, levels of phospho-AKT(Ser473) were increased compared to wild-type mice. The lung metastasis assay showed significantly more and larger lung nodules in IGFBP-3 knockout mice than in wild-type mice. While we observed increased levels of IGFBP-5 protein in the IGFBP-3 knockout mice, our findings suggest that this was not sufficient to completely compensate for the absence of IGFBP-3. Even though knockout of IGFBP-3 is associated with only a subtle phenotype under control conditions, our results reveal that loss of this gene has measurable effects on breast carcinogenesis and breast cancer metastasis.

IGFBP-3: a cell fate pivot in cancer and disease

One of the hallmarks in the advancement of cancer cells is an ability to overcome and acquire resistance to adverse conditions. There has been a large amount of cancer research on IGFBP-3 as a pro-apoptotic molecule in vitro. These pro-apoptotic properties, however, do not correlate with several studies linking high IGFBP-3 levels in breast cancer tissue to rapid growth and poor prognosis. Evidence is emerging that IGFBP-3 also exhibits pro-survival and growth-promoting properties in vitro. How IGFBP-3 pivots cell fate to either death or survival, it seems, comes down to a complex interplay between cells' microenvironments and the presence of cellular IGFBP-3 binding partners and growth factor receptors. The cytoprotective actions of IGFBP-3 are not restricted to cancer but are also observed in other disease states, such as retinopathy and brain ischaemia. Here we review the literature on this paradoxical nature of IGFBP-3, its pro-apoptotic and growth-inhibitory actions versus its cytoprotective and growth-potentiating properties, and discuss the implications of targeting IGFBP-3 for treatment of disease.

IGF axis and other factors in HPV-related and HPV-unrelated carcinogenesis (review)

The insulin-like growth factor (IGF) axis promotes the growth of cells, tissues and organs. IGF-1 is mainly produced in the liver but is also secreted from local tissues. In the circulation, IGF-1 is bound to insulin-like binding proteins (IGFBPs), and when released it activates the insulin-like growth factor receptor (IGF-1R). The signal is further transmitted by intracellular signaling pathways leading to gene expression that regulates, among others, cell proliferation and survival. This review presents the IGF axis in the context of cell transformation and cancer development. Aspects involving IGF-1 deficiency and protection from cancer are also briefly described. Furthermore, human papillomaviruses (HPVs) interplaying with IGF axis components in cervical cancer development are described. These small dsDNA viruses are divided into low-risk and high-risk HPVs with regard to the potency of their oncogenic actions; they mainly infect epithelial or mucosal cells. Special attention is drawn to expression of two major HPV oncogenes (E6 and E7) initiating and maintaining cervical carcinogenesis, which is a multistep and multifactorial process; therefore, involvement of additional factors such as mitochondrial DNA changes, sex hormones, retinoic and folic acids are also discussed. Finally, IGF axis components and HPV oncogenes as targets in anticancer treatment are presented which include IGF-1R downregulation, RNA interference and anti-HPV therapeutic vaccines. The review concludes that despite an enormous advancement in research on IGF and HPV-related cancers, more molecular studies and clinical trials are needed before commercialized therapies are widely available for oncology patients.

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.

Structural and functional analysis of the amphioxus IGFBP gene uncovers ancient origin of IGF-independent functions

IGFs play key roles in regulating vertebrate development, growth, reproduction, and aging. In extracellular fluids, IGFs are bound and regulated by a family of IGF-binding proteins (IGFBPs). Although all known IGFBPs are secreted proteins, some are also found in the nucleus and possess IGF-independent activities. When and how these distinct modes of biological actions have evolved is unknown. In this study, we identified and analyzed an IGFBP gene from amphioxus. Amphioxus shares a common ancestor with the modern vertebrate lineage that dates back to more than 520 million years ago. The amphioxus IGFBP shares all major structural characteristics of vertebrate IGFBPs. Phylogenetic analyses place it in a basal position in the IGFBP lineage. Ligand blot analysis reveals that amphioxus IGFBP does not bind to IGF-I or -II. Changing its Phe70 into Leu, however, is sufficient to convert it into a functional IGF binder. When tested in cultured cells, amphioxus IGFBP is localized in the nucleus, and this is attributed to 2 redundant nuclear localization sequences in its L domain. Furthermore, the amphioxus IGFBP N-terminal domain has strong transcriptional activation activity. Forced expression of amphioxus IGFBP in zebrafish embryos results in dorsalized phenotypes. This action requires nuclear localization. These results suggest that the nuclear localization and transcription activation activity of IGFBPs are ancient functions and the IGF-binding function may have been acquired by opportunistic gain-of-functional mutations later in evolution.

A crayfish insulin-like-binding protein: another piece in the androgenic gland insulin-like hormone puzzle is revealed

Across the animal kingdom, the involvement of insulin-like peptide (ILP) signaling in sex-related differentiation processes is attracting increasing attention. Recently, a gender-specific ILP was identified as the androgenic sex hormone in Crustacea. However, moieties modulating the actions of this androgenic insulin-like growth factor were yet to be revealed. Through molecular screening of an androgenic gland (AG) cDNA library prepared from the crayfish Cherax quadricarinatus, we have identified a novel insulin-like growth factor-binding protein (IGFBP) termed Cq-IGFBP. Based on bioinformatics analyses, the deduced Cq-IGFBP was shown to share high sequence homology with IGFBP family members from both invertebrates and vertebrates. The protein also includes a sequence determinant proven crucial for ligand binding, which according to three-dimensional modeling is assigned to the exposed outer surface of the protein. Recombinant Cq-IGFBP (rCq-IGFBP) protein was produced and, using a "pulldown" methodology, was shown to specifically interact with the insulin-like AG hormone of the crayfish (Cq-IAG). Particularly, using both mass spectral analysis and an immunological tool, rCq-IGFBP was shown to bind the Cq-IAG prohormone. Furthermore, a peptide corresponding to residues 23-38 of the Cq-IAG A-chain was found sufficient for in vitro recognition by rCq-IGFBP. Cq-IGFBP is the first IGFBP family member shown to specifically interact with a gender-specific ILP. Unlike their ILP ligands, IGFBPs are highly conserved across evolution, from ancient arthropods, like crustaceans, to humans. Such conservation places ILP signaling at the center of sex-related phenomena in early animal development.

Signal Transduction Pathways Mediated by Secreted and Non-secreted Forms of intact Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) and its 1-97 N-terminal Fragment in PC-3 Human Prostate Cancer Cells

Our previous results indicated that both the secreted and the intracellular form of full length and 1-97 N-terminal fragment of IGFBP-3 induces apoptosis in PC-3 human prostate cancer cells in an IGF-dependent and independent manner. This study was undertaken to delineate possible down-stream signaling pathways that are involved in this process. Intact IGFBP-3 and its N-terminal 1-97 fragments with or without a signal pro-peptide was fused to YFP and expressed in PC-3 human prostate cancer cells. In some cases, the putative IGF-binding site present in full length IGFBP-3 and its N-terminal fragment was also mutated. Extent of apoptosis was quantified using FACS. Up-regulation of total Stat-1 and activation of phospho-Stat-1 was shown by western blot. TGF-β signal was measured by luciferase reporter assay. Results from inhibitor studies indicated that both the Caspase 8 and caspase 9 pathways are involved in IGFBP-3 (non-secreted form) induced apoptosis in PC-3 cells. Exogenous addition of IGFBP-3 to PC-3 cells increased Stat-1 protein expression/tyrosine phosphorylation. Interestingly, results also showed that knockdown of Stat-1 by siRNA potentiated the IGFBP-3 induced apoptosis in PC-3 cells. In addition, both full-length IGFBP-3 and its 1-97 N-terminal fragments inhibited TGFβ signaling in these cells. This is the first report that compares the signal transduction pathways involved in apoptotic pathways mediated by IGFBP-3 in PC-3 human prostate cancer cells. Non-secreted form of full length IGFBP-3 and its N-terminal fragments induced apoptosis in PC-3 cells via activation of caspase 8 and caspase 9. We noted that both secreted and non-secreted forms of IGFBP-3 are involved in modulating Stat-1 and TGF-β pathways to induce apoptotic actions in PC-3 cells. Surprisingly, only non-secreted form of IGFBP-3 and its N-terminal fragments are involved in the induction of apoptosis in PC-3 cells via caspase 8 and caspase 9 activation. These studies clearly demonstrate that secreted and non-secreted FL and its 1-97 N-terminal fragments induce apoptosis in PC-3 cells by regulating different mechanistic pathways.

Molecular characterization and expression pattern of insulin-like growth factor binding protein-3 (IGFBP-3) in common carp, Cyprinus carpio

A full-length cDNA encoding the insulin-like growth factor binding protein-3 (IGFBP-3) was cloned from the liver of common carp (Cyprinus carpio) by RT-PCR. The IGFBP-3 cDNA sequence is 1,680 bp long and has an open reading frame of 882 bp encoding a predicted polypeptide of 293 amino acid residues. The deduced amino acid sequence contains a putative signal peptide of 25 amino acid residues resulting in a mature protein of 268 amino acids. A single band of approximate 1.9 kb was found in liver by Northern blot analysis. IGFBP-3 mRNA was observed in all regions of brain with high levels. In peripheral tissues, high levels of IGFBP-3 mRNA were found in retina, red muscle, liver, heart, posterior intestine, spleen, and testis. Relatively lower levels were found in white muscle, kidney, thymus gland, and ovary, while in head kidney, blood, skin, gill, middle intestine, and anterior intestine, the IGFBP-3 mRNA levels were much lower. IGFBP-3 mRNA was first detected in the blastula stage with significantly high level. The level sharply decreased in gastrula stage, and it became to increase in the following stages. During the reproductive cycle, the abundance of IGFBP-3 mRNA significantly decreased between the recrudescing stage and the matured stage in ovary, although in testis, IGFBP-3 mRNA expression level did not exhibit a significant change. The mRNA expression profiles in the present study imply that the IGFBP-3 may play important physiological functions in common carp development and reproduction.

Colocalization and identification of interaction sites between IGFBP-3 and GalNAc-T14

GalNAc-T14 was identified as a novel IGFBP-3 binding partner in previous studies. Here, we furtherly confirmed the interaction between them by confocal microscopy, and identified the binding domain and probable interaction sites of GalNAc-T14 with IGFBP-3. The result of subcellular localization indicated that GalNAc-T14 was distributed in the cytosol, whereas IGFBP-3 existed in the cytosol and nucleolus. Confocal analyses demonstrated that IGFBP-3 and GalNAc-T14 colocalized in the cytosol. The result from yeast two hybrid assay showed that the C terminus of GalNAc-T14 (408-552aa) was essential for the interaction between GalNAc-T14 and IGFBP-3, especially Tyr(408), Pro(409), and Glu(410) of GalNAc-T14 may play key roles in the interaction with IGFBP-3. In conclusion, these studies demonstrated that IGFBP-3 and GalNAc-T14 are colocalized in MCF-7 cells and confirmed the interaction between IGFBP-3 and GalNAc-T14. This interaction may play an important role in the functional regulation of IGFBP-3.

Role of insulin-like growth factors (IGFs), their receptors and genetic regulation in the chondrogenesis and growth of the mandibular condylar cartilage

Growth of the mandibular condylar cartilage (MCC) is reviewed as a function of genetic and epigenetic factors. The growth centers around the differential spatial concentration of the chondrocytes, influence of growth factors like TGF-β and heterogeneity in the number of IGF receptors, control the action of IGF. Besides these factors, growth of the mandibular condyle is influenced by differential response of chondrocytes as a function of their source/ageing, which in turn is regulated by TGF-β, BMPs and IGFs. While IGF-1 promotes proteoglycan synthesis and survival of the chondrocytes to maintain cartilage homeostasis, TGF-β synergistically catalysed the effect of IGF-1, while BMPs catalysed proteolysis as and when physiologically needed. To understand these processes, role of IGF-1 and its six receptors is at the center to a number of physiological processes being regulated by its mode of application for the growth and differentiation. Probing deeper, biological functions of IGFs seemed to depend on their level of free status rather than bound status to respective IGF-binding proteins (IGF-BPs), considered prerequisite to modulate their biological functions. Genetic regulation of their secretion has thrown light on their insulin-like structural homology, level and response in osteo-arthritis (OA), rheumatic arthritis (RA) and diabetes type-II. Biochemistry and spatial distribution of IGF receptors in different domains exerts control on IGF-1 activities. In ultimate analysis, IGF-axis conserved during the evolution to regulate cell growth and proliferation affect nearly every organ in the body as judged from the techniques determining skeletal maturity and decision making dependent on it for orthodontic, orthognathic/orthopedic and dental implant applications.

Elevated IGFBP3 levels in diabetic tears: a negative regulator of IGF-1 signaling in the corneal epithelium

To determine the ratio of IGFBP3:IGF-1 in normal and diabetic human tears, and in telomerase-immortalized human corneal epithelial cells (hTCEpi) cultured under elevated glucose conditions and to correlate these changes with total and phosphorylated levels of IGF-1R. Tear samples were collected noninvasively from diabetic subjects and non-diabetic controls; corneal sensitivity was assessed using a Cochet-Bonnet Aesthesiometer. Conditioned media were collected following culture of hTCEpi cells in normal (5 mM) and elevated (25 mM) glucose conditions; mannitol was used as an osmotic control. IGFBP3, IGF-1, and phosphorylated IGF-1R levels were assessed by ELISA. IGFBP3 and IGF-1R mRNA were assessed by real-time polymerase chain reaction (PCR). Total and phosphorylated IGF-1R expression in whole cell lysates was assessed by western blot. There was a 2.8-fold increase in IGFBP3 in diabetic tears compared to non-diabetic controls (P=0.006); IGF-1 levels were not significantly altered. No difference in corneal sensitivity was detected between groups. The concentration of IGFBP3 in tears was independent of IGF-1. Consistent with human tear measurements in vivo, IGFBP3 secretion was increased 2.2 fold (P<0.001) following culture of hTCEpi cells under elevated glucose conditions in vitro. Treatment with glucose and the mannitol control reduced IGFBP3 mRNA (P<0.001). Total IGF-1R levels were unchanged. The increase in the IGFBP3:IGF-1 ratio detected in diabetic tears compared to normal controls blocked phosphorylation of the IGF-1R by IGF-1 (P<0.001) when tested in vitro. Taken together, these in vivo and confirmatory in vitro findings suggest that the observed increase in IGFBP3 found in human tears may attenuate IGF-1R signaling in the diabetic cornea. A long-term increase in IGFBP3 may contribute to epithelial compromise and the pathogenesis of ocular surface complications reported in diabetes.

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.

Analysis of the cellular uptake and nuclear delivery of insulin-like growth factor binding protein-3 in human osteosarcoma cells

Insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) regulates cell proliferation and survival by extracellular interaction and inactivation of the growth factor IGF-I. Beyond that, IGF-independent actions mediated by intracellular IGFBP-3 including nuclear-IGFBP-3, have also been described. We here show, using both confocal and electron microscopy and cell fractionation, that the extracellular addition of IGFBP-3 to living cells results in rapid uptake and nuclear delivery of IGFBP-3, by yet partly unknown mechanisms. IGFBP-3 is internalized through a dynamin-dependent pathway, traffics through endocytic compartments and is finally delivered into the nucleus. We observed docking of IGFBP-3 containing structures to the nuclear envelope and found IGFBP-3 containing dot-like structures to permeate the nuclear envelope. In summary, our findings establish the pathway by which this tumor suppressor protein is delivered from extracellular space to the nucleus.

IGF binding protein 3 exerts its ligand-independent action by antagonizing BMP in zebrafish embryos

IGFBP3 is a multi-functional protein that has IGF-dependent and IGF-independent actions in cultured cells. Here we show that the IGF binding domain (IBD), nuclear localization signal (NLS) and transactivation domain (TA) are conserved and functional in zebrafish Igfbp3. The in vivo roles of these domains were investigated by expression of Igfbp3 and its mutants in zebrafish embryos. Igfbp3, and its NLS and TA mutants had equally strong dorsalizing effects. Human IGFBP3 had similar dorsalizing effects in zebrafish embryos. The activities of IBD and IBD+NLS mutants were lower, but they still caused dorsalization. Thus, the IGF-independent action of Igfbp3 is not related to NLS or TA in this in vivo model. We next tested the hypothesis that Igfbp3 exerts its IGF-independent action by affecting Bmp signaling. Co-expression of Igfbp3 with Bmp2b abolished Bmp2b-induced gene expression and inhibited its ventralizing activity. Biochemical assays and in vitro experiments revealed that IGFBP3 bound BMP2 and inhibited BMP2-induced Smad signaling in cultured human cells. In vivo expression of Igfbp3 increased chordin expression in zebrafish embryos by alleviating the negative regulation of Bmp2. The elevated level of Chordin acted together with Igfbp3 to inhibit the actions of Bmp2. Knockdown of Igfbp3 enhanced the ventralized phenotype caused by chordin knockdown. These results suggest that Igfbp3 exerts its IGF-independent actions by antagonizing Bmp signaling and that this mechanism is conserved.

Relationship of insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) gene polymorphism with the susceptibility to development of prostate cancer and influence on serum levels of IGF-I, and IGFBP-3

The bioavailability of IGF-I is controlled by the binding protein, IGF binding protein-3 (IGFBP-3). In addition, IGFBP-3 is a strong anti-proliferative protein that provokes apoptosis and inhibits cell proliferation in prostate cancer. We conducted this study to investigate the association between IGFBP-3 gene polymorphism and serum levels of IGF-I and IGFBP-3 and the incidence of prostate cancer (PCa) and benign prostatic hyperplasia (BPH). DNA isolation was performed in peripheral blood samples obtained from all participants. Required areas were amplified with polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique by using proper primers belonging to this gene area. We also measured serum IGF-I and IGFBP-3 levels. The IGFBP-3 -202 A/C polymorphism genotype frequencies showed a significant difference between PCa patients and controls (χ(2)=6.27, df=2.0, P=0.026), as well as between BPH patients and controls (χ(2)=11.57, df=4.0, P=0.014). The AA genotype frequency was significantly decreased in PCa and BPH patients compared to control group and the risk of PCa and BPH occurrence of this genotype was decreased accordingly (PCa; OR=0.28, 95% CI=0.17-0.44, P=0.0001; BPH: OR=0.48, 95% CI=0.29-0.77, P=0.001). Age-adjusted mean serum IGFBP-3 concentrations were highest in the individuals with the AA genotype and diminished significantly in a stepwise manner in the presence of 1 or 2 copies of the C allele (4577 ng/ml, 3929 ng/ml and 3349 ng/ml, respectively). Patients with PCa and BPH had lower serum IGF-1 (P=0.001, and P=0.01, respectively) and IGFBP-3 levels (P=0.001, and P=0.01, respectively) compared with controls. The AA genotype at IGFBP-3 gene polymorphism is associated with reduced risks of PCa and BPH. Both IGF-I and IGFBP-3 concentrations, are associated with modified risks of PCa and BPH.

Purification and characterization of native human insulin-like growth factor binding protein-6

Insulin-like growth factor binding proteins (IGFBPs) are key regulators of insulin-like growth factor (IGF) mediated signal transduction and thereby can profoundly influence cellular phenotypes and cell fate. Whereas IGFBPs are extracellular proteins, intracellular activities were described for several IGFBP family members, such as IGFBP-3, which can be reinternalized by endocytosis and reaches the nucleus through routes that remain to be fully established. Within the family of IGFBPs, IGFBP-6 is unique for its specific binding to IGF-II. IGFBP-6 was described to possess additional IGF-independent activities, which have in part been attributed to its translocation to the nucleus; however, cellular uptake of IGFBP-6 was not described. To further explore IGFBP-6 functions, we developed a new method for the purification of native human IGFBP-6 from cell culture supernatants, involving a four-step affinity purification procedure, which yields highly enriched IGFBP-6. Whereas protein purified in this way retained the capacity to interact with IGF-II and modulate IGF-dependent signal transduction, our data suggest that, unlike IGFBP-3, human IGFBP-6 is not readily internalized by human tumor cells. To summarize, this work describes a novel and efficient method for the purification of native human insulin-like growth factor binding protein 6 (IGFBP-6) from human cell culture supernatants, applying a four-step chromatography procedure. Intactness of purified IGFBP-6 was confirmed by IGF ligand Western blot and ability to modulate IGF-dependent signal transduction. Cellular uptake studies were performed to further characterize the purified protein, showing no short-term uptake of IGFBP-6, in contrast to IGFBP-3.

Effect of shock wave treatment on platelet-rich plasma added to osteoblast cultures

The aim of this study was to verify the effects on osteoblast cultures of adding a platelet-rich plasma (PRP) concentrate pretreated with 500 shock wave (SW) at an energy flow density of 0.17 mJ/mm(2), emitted by an electromagnetic generator Minilith SL1 (STORZ, Germany), reproducing the conditions of our previous study in which we apply SW directly on osteoblasts. Real-time PCR showed that in osteoblast cultures with added PRP pretreated with SW, there was an increased expression at 48 h of insulin-like growth factor binding protein 3 (IGFBP-3) and runt-related transcription factor 2 (RUNX2) and at 72 h, of collagen type I, osteocalcin, insulin-like growth factor 1 (IGF-1) as well as IGFBP-3. Western blotting confirmed the increased protein synthesis of IGFBP-3. This experience suggests that extracorporeal shock wave treatment (ESWT) should stimulate osteogenesis also by indirect platelets-mediated network. It therefore seems possible that combining the two methods, ESWT and bioengineering procedures to infiltrate PRP and growth factors, could be a successful approach.

Toward an automatic method for extracting cancer- and other disease-related point mutations from the biomedical literature

MOTIVATION

A major goal of biomedical research in personalized medicine is to find relationships between mutations and their corresponding disease phenotypes. However, most of the disease-related mutational data are currently buried in the biomedical literature in textual form and lack the necessary structure to allow easy retrieval and visualization. We introduce a high-throughput computational method for the identification of relevant disease mutations in PubMed abstracts applied to prostate (PCa) and breast cancer (BCa) mutations.

RESULTS

We developed the extractor of mutations (EMU) tool to identify mutations and their associated genes. We benchmarked EMU against MutationFinder--a tool to extract point mutations from text. Our results show that both methods achieve comparable performance on two manually curated datasets. We also benchmarked EMU's performance for extracting the complete mutational information and phenotype. Remarkably, we show that one of the steps in our approach, a filter based on sequence analysis, increases the precision for that task from 0.34 to 0.59 (PCa) and from 0.39 to 0.61 (BCa). We also show that this high-throughput approach can be extended to other diseases.

DISCUSSION

Our method improves the current status of disease-mutation databases by significantly increasing the number of annotated mutations. We found 51 and 128 mutations manually verified to be related to PCa and Bca, respectively, that are not currently annotated for these cancer types in the OMIM or Swiss-Prot databases. EMU's retrieval performance represents a 2-fold improvement in the number of annotated mutations for PCa and BCa. We further show that our method can benefit from full-text analysis once there is an increase in Open Access availability of full-text articles.

AVAILABILITY

Freely available at: http://bioinf.umbc.edu/EMU/ftp.

Quercetin regulates insulin like growth factor signaling and induces intrinsic and extrinsic pathway mediated apoptosis in androgen independent prostate cancer cells (PC-3)

Progression of prostate cancer is facilitated by growth factors that activate critical signaling cascades thereby promote prostate cancer cell growth, survival, and migration. To investigate the effect of quercetin on insulin-like growth factor signaling and apoptosis in androgen independent prostate cancer cells (PC-3), IGF-IR, PI-3K, p-Akt, Akt, cyclin D1, Bad, cytochrome c, PARP, caspases-9 and 10 protein levels were assessed by western blot analysis. Mitochondrial membrane potency was detected by rhodamine-123 staining. Quercetin induced caspase-3 activity assay was performed for activation of apoptosis. Further, RT-PCR was also performed for Bad, IGF-I, II, IR, and IGFBP-3 mRNA expression. Quercetin significantly increases the proapoptotic mRNA levels of Bad, IGFBP-3 and protein levels of Bad, cytochrome C, cleaved caspase-9, caspase-10, cleaved PARP and caspase-3 activity in PC-3 cells. IGF-IRβ, PI3K, p-Akt, and cyclin D1 protein expression and mRNA levels of IGF-I, II and IGF-IR were decreased significantly. Further, treatment with PI3K inhibitor (LY294002) and quercetin showed decreased p-Akt levels. Apoptosis is confirmed by loss of mitochondrial membrane potential in quercetin treated PC-3 cells. This study suggests that quercetin decreases the survival of androgen independent prostate cancer cells by modulating the expression of insulin-like growth factors (IGF) system components, signaling molecules and induces apoptosis, which could be very useful for the androgen independent prostate cancer treatment.

IGF-I, insulin and prostate cancer

Prostate cancer is the second most frequent malignancy diagnosed in adult men. Androgens are considered the primary growth factors for prostate normal and cancer cells. However, other non-androgenic growth factors are involved in the growth regulation of prostate cancer cells. The association between IGF-I and prostate cancer risk is well established. However, there is no evidence that the measurement of IGF-I enhances the specificity of prostate cancer detection beyond that achievable by serum prostate-specific antigen (PSA) levels. Until now, there is no consensus on the possible association between IGFBP-3 and prostate cancer risk. Although not well established, it seems that high insulin levels are particularly associated with risk of aggressive prostatic tumours. This review describes the physiopathological basis, epidemiological evidence, and animal models that support the association of the IGFs family and insulin with prostate cancer. It also describes the potential therapies targeting these growth factors that, in the future, can be used to treat patients with prostate cancer.

Nuclear export and mitochondrial and endoplasmic reticulum localization of IGF-binding protein 3 regulate its apoptotic properties

Tumor suppression by IGF-binding protein 3 (IGFBP3) may occur in an IGF-independent manner, in addition to its role as a regulator of IGF bioavailability. After secretion, IGFBP3 is internalized, rapidly localized to the nucleus, and is later detected in the cytoplasm. We identified a putative nuclear export sequence (NES) in IGFBP3 between amino acids 217 and 228, analogous to the leucine-rich NES sequence of p53 and HIV Rev. Mutation of the NES prevents nucleocytoplasmic shuttling of IGFBP3 and blocks its ability to induce apoptosis. Targeting of IGFBP3 to the mitochondria and endoplasmic reticulum (ER) was confirmed by co-localization with organelle markers using fluorescence confocal microscopy and subcellular fractionation. Mitochondrial targeting was also demonstrated in vivo in IGFBP3-treated prostate cancer xenografts. These results show that IGFBP3 shuttles from the nucleus to the mitochondria and ER, and that nuclear export is essential for its effects on prostate cancer apoptosis.

Urinary excretion of IGFBP-1 and -3 correlates with disease activity and differentiates focal segmental glomerulosclerosis and minimal change disease

The glomerular microenvironment is influenced by circulating growth factors that are filtered from the blood stream and pass the glomerular filtration barrier. In this study, we wanted to explore the role of IGF-binding proteins (IGFBPs) in two diseases that concern podocytes. We analyzed glomerular expression and urinary excretion of IGFBP-1, -2, and -3 in patients with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). We found that patients with active FSGS excrete high amounts of podocalyxin positive cells as well as IGFBP-1 and -3. In human podocytes, we can induce mRNA expression of IGFBP-3 in response to TGF-beta and in human microvascular endothelial cells expression of IGFBP-1 and -3 in response to TGF-beta and Bradykinin. We conclude that the local expression of IGFBPs in podocytes and endothelial cells might contribute to the pathogenesis of glomerular disease and that IGFBP-1 and -3 are potential non-invasive markers of FSGS.

The insulin-like growth factor family: molecular mechanisms, redox regulation, and clinical implications

Insulin-like growth factor (IGF)-induced signaling networks are vital in modulating multiple fundamental cellular processes, such as cell growth, survival, proliferation, and differentiation. Aberrations in the generation or action of IGF have been suggested to play an important role in several pathological conditions, including metabolic disorders, neurodegenerative diseases, and multiple types of cancer. Yet the exact mechanism involved in the pathogenesis of these diseases by IGFs remains obscure. Redox pathways involving reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the pathogenetic mechanism of various diseases by modifying key signaling pathways involved in cell growth, proliferation, survival, and apoptosis. Furthermore, ROS and RNS have been demonstrated to alter IGF production and/or action, and vice versa, and thereby have the ability to modulate cellular functions, leading to clinical manifestations of diseases. In this review, we provide an overview on the IGF system and discuss the potential role of IGF-1/IGF-1 receptor and redox pathways in the pathophysiology of several diseases.

Perspectives in mammalian IGFBP-3 biology: local vs. systemic action

Insulin-like growth factor (IGF) binding protein (IGFBP)-3 has traditionally been defined by its role as a binding protein and its association with IGF delivery and availability. Development of non-IGF binding IGFBP-3 analogs and the use of cell lines devoid of type 1 IGF receptors (IGF-R) have led to critical advances in the field of IGFBP-3 biology. These studies show that IGFBP-3 has IGF-independent roles in inhibiting cell proliferation in cancer cell lines. Nuclear transcription factor, retinoid X receptor (RXR)-alpha, and IGFBP-3 functionally interact to reduce prostate tumor growth and prostate-specific antigen in vivo. Moreover, IGFBP-3 inhibits insulin-stimulated glucose uptake into adipocytes independent of IGF. The purpose of this review is to highlight IGFBP-3 as a novel effector molecule and not just another "binding protein" by discussing its IGF-independent actions on metabolism and cell growth. Although this review presents studies that assume the role of IGFBP-3 as either an endocrine or autocrine/paracrine molecule, these systems may not exist as distinct entities, justifying the examination of IGFBP-3 in an integrated model. Also, we provide an overview of factors that regulate IGFBP-3 availability, including its production, methylation, and ubiquitination. We conclude with the role of IGFBP-3 in whole body systems and possible future applications of IGFBP-3 in physiology.

NKX3.1 activates expression of insulin-like growth factor binding protein-3 to mediate insulin-like growth factor-I signaling and cell proliferation

NKX3.1 is a homeobox gene that codes for a haploinsufficient prostate cancer tumor suppressor. NKX3.1 protein levels are down-regulated in the majority of primary prostate cancer tissues. NKX3.1 expression in PC-3 cells increased insulin-like growth factor binding protein-3 (IGFBP-3) mRNA expression 10-fold as determined by expression microarray analysis. In both stably and transiently transfected PC-3 cells and in LNCaP cells, NKX3.1 expression increased IGFBP-3 mRNA and protein expression. In prostates of Nkx3.1 gene-targeted mice Igfbp-3 mRNA levels correlated with Nkx3.1 copy number. NKX3.1 expression in PC-3 cells attenuated the ability of insulin-like growth factor-I (IGF-I) to induce phosphorylation of type I IGF receptor (IGF-IR), insulin receptor substrate 1, phosphatidylinositol 3-kinase, and AKT. The effect of NKX3.1 on IGF-I signaling was not seen when cells were exposed to long-R3-IGF-I, an IGF-I variant peptide that does not bind to IGFBP-3. Additionally, small interfering RNA-induced knockdown of IGFBP-3 expression partially reversed the attenuation of IGF-IR signaling by NKX3.1 and abrogated NKX3.1 suppression of PC-3 cell proliferation. Thus, there is a close relationship in vitro and in vivo between NKX3.1 and IGFBP-3. The growth-suppressive effects of NKX3.1 in prostate cells are mediated, in part, by activation of IGFBP-3 expression.

Gene expression profile in colon cancer cells with respect to XIAP expression status

BACKGROUND AND AIMS

We observed a marked synergism between peroxisome proliferator-activated receptor gamma (PPARgamma) ligands and X-linked inhibitor of apoptosis (XIAP) down-regulation in colon cancer. In the current study, we detected the gene expression profile in HCT116 cells treated with or without PPARgamma ligand troglitazone.

MATERIALS AND METHODS

HCT116-XIAP(+/+) and HCT116-XIAP(-/-) cells were treated with or without 50 microM troglitazone for 48 h. Gene expressions were detected by microarray, and selected genes were validated by reverse-transcriptase polymerase chain reaction (PCR), real-time PCR, and Western blot.

RESULTS

Relative to HCT116-XIAP(+/+) cells, 58 genes were up-regulated and 33 genes down-regulated in HCT116-XIAP(-/-) cells, all by > or =4-fold. These genes could be classified into a wide variety of functional classes, but we focused on those related to angiogenesis, apoptosis, and proliferation. Thus, two pro-apoptotic genes and one pro-proliferation gene were up-regulated in HCT116-XIAP(-/-) cells. Two pro-proliferation genes, one pro-angiogenesis gene, one anti-angiogenesis gene, and one anti-apoptosis gene were down-regulated in HCT116-XIAP(-/-) cells. Relative to HCT116-XIAP(+/+) cells treated with troglitazone, 137 genes were up-regulated, and 31 genes were down-regulated in troglitazone-treated HCT116-XIAP(-/-) cells, all by > or =4-fold. Among the up-regulated genes were two anti-angiogenesis genes, seven pro-apoptosis genes, and six anti-proliferation genes. Among the down-regulated genes were one anti-angiogenesis gene, one pro-angiogenesis gene, one anti-apoptosis gene, one anti-proliferation gene, and two pro-proliferation genes.

CONCLUSION

Down-regulation of XIAP in HCT116 cells with or without troglitazone treatment was associated with changes of gene expression that favor increased tendency of apoptosis, decreased cell proliferation, and angiogenesis potential.

The role of insulin-like growth factor-I and its binding proteins in glucose homeostasis and type 2 diabetes

This review addresses the possible role of the insulin-like growth factor (IGF)-axis in normal glucose homoeostasis and in the etiopathogenesis of type 2 diabetes. IGF-I, a peptide hormone, shares amino acid sequence homology with insulin and has insulin-like activity; most notably, the promotion of glucose uptake by peripheral tissues. Type 2 diabetes as well as pre-diabetic states, including impaired fasting glucose and impaired glucose tolerance, are associated cross-sectionally with altered circulating levels of IGF-I and its binding proteins (IGFBPs). Administration of recombinant human IGF-I has been reported to improve insulin sensitivity in healthy individuals as well as in patients with insulin resistance and type 2 diabetes. Further, IGF-I may have beneficial effects on systemic inflammation, a risk factor for type 2 diabetes, and on pancreatic beta-cell mass and function. There is considerable inter-individual heterogeneity in endogenous levels of IGF-I and its binding proteins; however, the relationship between these variations and the risk of developing type 2 diabetes has not been extensively investigated. Large prospective studies are required to evaluate this association.

An N-terminal fragment of insulin-like growth factor binding protein-3 (IGFBP-3) induces apoptosis in human prostate cancer cells in an IGF-independent manner

OBJECTIVE

IGF-binding protein-3 (IGFBP-3) can induce apoptosis in human prostate cancer cells by direct, IGF-independent mechanisms that are poorly understood. IGFBP-3 undergoes limited proteolysis by plasmin and other proteases to generate small N-terminal fragments (e.g., amino acids 1-97) that have lost their affinity for IGF-I and IGF-II yet still can inhibit mitogenesis. The present study examines whether the N-terminal 1-97-IGFBP-3 fragment can induce apoptosis in human prostate cancer cells in an IGF-independent manner.

DESIGN

N-terminal 1-97-IGFBP-3 with or without a signal prepeptide was fused to yellow fluorescent protein (YFP) and expressed in PC-3 human prostate cancer cells. In some cases, the N-terminal IGF-binding site was mutated. Subcellular localization was determined by confocal microscopy. Loss of cell viability was determined by Annexin V-APC staining in the presence and absence of a general caspase inhibitor, z-VAD-fmk.

RESULTS

All of the fusion proteins, including those synthesized with a signal peptide, were predominantly intracellular, suggesting that they had been internalized following secretion. YFP-1-97-IGFBP-3 is present at comparable concentrations in the nucleus and cytoplasm, indicating that it does not contain a nuclear localization signal. Cells transfected with YFP-1-97-IGFBP-3 lost viability. Cell death was blocked by incubation with a caspase inhibitor suggesting that it resulted from apoptosis. Similar results were obtained with YFP-1-97-IGFBP-3 mutants that do not bind IGFs.

CONCLUSIONS

The N-terminal 1-97-IGFBP-3 fragment induces apoptosis in human prostate cancer cells in an IGF-independent manner. Generation of the fragment might contribute to the proapoptotic activity of IGFBP-3 in vivo.

Local IGFBP-3 mRNA expression, apoptosis and risk of colorectal adenomas

Background

IGF binding protein-3 (IGFBP-3) regulates the bioavailability of insulin-like growth factors I and II, and has both anti-proliferative and pro-apoptotic properties. Elevated plasma IGFBP-3 has been associated with reduced risk of colorectal cancer (CRC), but the role of tissue IGFBP-3 is not well defined. We evaluated the association between tissue or plasma IGFBP-3 and risk of colorectal adenomas or low apoptosis.

Methods

Subjects were consenting patients who underwent a clinically indicated colonoscopy at UNC Hospitals and provided information on diet and lifestyle. IGFBP-3 mRNA in normal colon was assessed by real time RT-PCR. Plasma IGFBP-3 was measured by ELISA and apoptosis was determined by morphology on H & E slides. Logistic regression was used to compute odds ratio (OR) and 95% confidence intervals.

Results

We observed a modest correlation between plasma IGFBP-3 and tissue IGFBP-3 expression (p = 0.007). There was no significant association between plasma IGFBP-3 and adenomas or apoptosis. Tissue IGFBP-3 mRNA expression was significantly lower in cases than controls. Subjects in the lowest three quartiles of tissue IGFBP-3 gene expression were more likely to have adenomas. Consistent with previous reports, low apoptosis was significantly associated with increased risk of adenomas (p = 0.003). Surprisingly, local IGFBP-3 mRNA expression was inversely associated with apoptosis.

Conclusion

Low expression of IGFBP-3 mRNA in normal colonic mucosa predicts increased risk of adenomas. Our findings suggest that local IGFBP-3 in the colon may directly increase adenoma risk but IGFBP-3 may act through a pathway other than apoptosis to influence adenoma risk.

Induction of apoptosis in human prostate cancer cells by insulin-like growth factor binding protein-3 does not require binding to retinoid X receptor-alpha

IGF binding protein (IGFBP)-3 can induce apoptosis in human prostate cancer cells directly without sequestering IGF-I and -II. The molecular mechanisms responsible for the IGF-independent actions of IGFBP-3 remain unclear. IGFBP-3, a secreted protein, can be internalized and translocate to the nucleus. It binds to the nuclear retinoid X receptor (RXR)-alpha. Binding to RXR-alpha has been proposed to be required for IGFBP-3 to induce apoptosis. The present study tests this hypothesis in the PC-3 human prostate cancer cell line. PC-3 cells express RXR-alpha, and apoptosis is induced by incubation with RXR-specific ligand. A COOH-terminal region in IGFBP-3 (residues 215-232) contains a nuclear localization signal, and binding domains for RXR-alpha and heparin (HBD). Different combinations of the 11 amino acids in this region that differ from IGFBP-1, a related IGFBP, which does not localize to the nucleus or bind RXR-alpha, were mutated to the IGFBP-1 sequence. By confocal imaging, mutation of residues 228-KGRKR-232 in nonsecreted IGFBP-3 diminished its nuclear localization. IGFBP-3 binding to glutathione S-transferase-RXR-alpha only was lost when all 11 sites were mutated (HBD-11m-IGFBP-3). Expressed nuclear RXR-alpha did not transport cytoplasmic IGFBP-3 nuclear localization signal mutants that can bind RXR-alpha to the nucleus even after treatment with RXR ligand. Expressed HBD-11m-IGFBP-3 still induced apoptosis in PC-3 cells in an IGF-independent manner as determined by flow cytometric analysis of Annexin V staining. We conclude that in PC-3 cells, RXR-alpha is not required for the nuclear translocation of IGFBP-3 and that IGFBP-3 can induce apoptosis in human prostate cancer cells without binding RXR-alpha.

IGFBP3 promoter methylation in colorectal cancer: relationship with microsatellite instability, CpG island methylator phenotype, and p53

Insulin-like growth factor binding protein 3 (IGFBP3), which is induced by wild-type p53, regulates IGF and interacts with the TGF-beta pathway. IGFBP3 promoter methylation may occur in colorectal cancer with or without the CpG island methylator phenotype (CIMP), which is associated with microsatellite instability (MSI) and TGFBR2 mutation. We examined the relationship between IGFBP3 methylation, p53 expression, CIMP and MSI in 902 population-based colorectal cancers. Utilizing real-time PCR (MethyLight), we quantified promoter methylation in IGFBP3 and eight other CIMP-high-specific promoters (CACNA1G, CDKN2A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1). IGFBP3 methylation was far more frequent in non-MSI-high CIMP-high tumors (85% = 35/41) than in MSI-high CIMP-high (49% = 44/90, P < .0001), MSI-high non-CIMP-high (17% = 6/36, P < .0001), and non-MSI-high non-CIMP-high tumors (22% = 152/680, P < .0001). Among CIMP-high tumors, the inverse relationship between MSI and IGFBP3 methylation persisted in p53-negative tumors (P < .0001), but not in p53-positive tumors. IGFBP3 methylation was associated inversely with TGFBR2 mutation in MSI-high non-CIMP-high tumors (P = .02). In conclusion, IGFBP3 methylation is inversely associated with MSI in CIMP-high colorectal cancers, and this relationship is limited to p53-negative tumors. Our data suggest complex relationship between global genomic/epigenomic phenomena (such as MSI/CIMP), single molecular events (e.g., IGFBP3 methylation, TP53 mutation, and TGFBR2 mutation), and the related pathways.