Transfection of human insulin-like growth factor-binding protein 3 gene inhibits cell growth and tumorigenicity: a cell culture model for lung cancer

Construction and validation of a novel IGFBP3-related signature to predict prognosis and therapeutic decision making for Hepatocellular Carcinoma

Background

IGFBP3 plays a pivotal role in carcinogenesis by being anomalously expressed in some malignancies. However, the clinical value of IGFBP3 and the role of IGFBP3-related signature in HCC remain unclear.

Methods

Multiple bioinformatics methods were used to determine the expression and diagnostic values of IGFBP3. The expression level of IGFBP3 was validated by RT-qPCR and IHC. A IGFBP3-related risk score (IGRS) was built via correlation analysis and LASSO Cox regression analysis. Further analyses, including functional enrichment, immune status of risk groups were analyzed, and the role of IGRS in guiding clinical treatment was also evaluated.

Results

IGFBP3 expression was significantly downregulated in HCC. IGFBP3 expression correlated with multiple clinicopathological characteristics and demonstrated a powerful diagnostic capability for HCC. In addition, a novel IGRS signature was developed in TCGA, which exhibited good performance for prognosis prediction and its role was further validated in GSE14520. In TCGA and GSE14520, Cox analysis also confirmed that the IGRS could serve as an independent prognostic factor for HCC. Moreover, a nomogram with good accuracy for predicting the survival of HCC was further formulated. Additionally, enrichment analysis showed that the high-IGRS group was enriched in cancer-related pathways and immune-related pathways. Additionally, patients with high IGRS exhibited an immunosuppressive phenotype. Therefore, patients with low IGRS scores may benefit from immunotherapy.

Conclusions

IGFBP3 can act as a new diagnostic factor for HCC. IGRS signature represents a valuable predictive tool in the prognosis prediction and therapeutic decision making for Hepatocellular Carcinoma.

IGFBP3 inhibits tumor growth and invasion of lung cancer cells and is associated with improved survival in lung cancer patients

The insulin-like growth factor (IGF)-pathway is involved in tumor cell proliferation, metastasis, and survival. We aimed to find out what effects IGF binding protein 3 (IGFBP3) exerted on H1299 lung cancer (LC) cells in terms of tumor growth and invasion and whether IGFBP3 was associated with clinical and pathological parameters in a prospective cohort of LC patients. H1299 cells were transfected with an IGFBP3-expressing vector. Its influence on apoptosis induction via flow cytometry annexin V FITC assay, cell proliferation in 2D and 3D cell culture, and invasion were examined. Expression of several matrix metalloproteinases (MMPs) and inhibitors (TIMP-1) were also investigated in IGFBP3-transfected LC cells. Further, data on LC patients (n = 131), tumor characteristics, and survival were prospectively collected and correlated with IGFBP3 plasma levels. IGFBP3 did not influence apoptosis induction and 2D cell proliferation. However, both spheroid growth (3D proliferation) and invasion of IGFBP3-transfected cells planted in an extracellular matrix-based gel were significantly inhibited. IGFBP3 inhibited MMP-1 release, and the total MMP activity. In LC patients, higher IGFBP3 plasma levels correlated with both lower clinical tumor stage, grading, Ki-67 staining, and the absence of necrosis (P < 0.05, respectively). Increased IGFBP3 plasma levels were associated with improved overall survival (hazard ratio 0.37, P = 0.01). In conclusion, overexpressed IGFBP3 in a LC cell line inhibited tumor growth and invasion. Translating from bench to bedside, investigation of clinicopathological parameters confirmed these experimental results showing that higher IGFBP3 plasma levels were associated with less aggressive tumor growth, reduced tumor spread, and improved survival of LC patients.

Gene expression and prognosis of insulin‑like growth factor‑binding protein family members in non‑small cell lung cancer

Lung cancer is the leading cause of cancer mortality worldwide. Approximately 85% of all lung cancer cases are classified as non-small cell lung cancer (NSCLC). Currently, there is no standard method to predict the survival of patients with NSCLC. Insulin-like growth factor-binding proteins (IGFBPs) function as modulators of IGF signaling and are attracting increasing attention for their role in NSCLC. However, the prognostic values of individual IGFBPs in NSCLC, particularly at the mRNA level, remain unknown. In the present study, the distinct expression patterns and prognostic values of IGFBP family members in patients with NSCLC through bioinformatics analysis were reported using a series of databases, including Gene Expression Profiling Interactive Analysis, Kaplan-Meier Plotter, cBioPortal, GeneMANIA, and the Database for Annotation, Visualization and Integrated Discovery. In patients with NSCLC, IGFBP2 and IGFBP3 were significantly upregulated, while IGFBP6 was downregulated. High IGFBP1/2/4 expression was correlated with poor overall survival (OS) in all NSCLC types, especially adenocarcinoma; however, high IGFBP2/5 expression was significantly correlated with favorable OS only in patients with squamous cell carcinoma. In addition, aberrant IGFBP1/2/3/4/5 mRNA levels were associated with the prognosis of subsets of NSCLC with different clinicopathological features. These results indicated that various IGFBPs can serve as useful prognostic biomarkers and as potential targets for NSCLC therapies.

A Hospital Based Study to Establish the Correlation between Recurrent Wheeze and Vitamin D Deficiency Among Children of Age Group Less than 3 Years in Indian Scenario

INTRODUCTION

Early childhood wheezing is a heterogeneous condition, which has several phenotypic expressions and a complex relationship with the development of asthma later in life. New studies indicate the prevalence of recurrent wheeze to be associated with Vitamin D deficiency. This has not been explored in Indian settings widely, mandating this exploration.

AIM

To determine the severity of Vitamin D deficiency and its association with recurrent wheeze in children less than 3 years of age.

MATERIALS AND METHODS

Consecutive type of non-probability sampling was followed for selection of study subjects with a total sample size to be 122 children in the Hospital setting. A pre- formed, pre- tested, structured interview schedule was used to obtain information. Estimation of 25 (OH) Vitamin D was done using ELISA method. Kit used for estimation was DLD Diagnostika GMBH 25(OH) Vitamin D ELISA from Germany. Standard statistical tools were used including Logistic regression analysis, and ROC curve, p value <0.05 was considered to be statistically significant. SPSS software version 17.0 was used.

RESULTS

Each 10ng/ml decrease in Vitamin D level is associated with 7.25% greater odds of wheezing. Our study also suggests, exclusive breast feeding and delaying of complementary feeding beyond 6 months of age are significant predictors of Vitamin D deficiency and have indirect association with increased incidence of wheezing in children.

CONCLUSION

The study concluded that Vitamin D deficiency is associated with increased risk of recurrent wheezing.

shRNA constructs targeting IGFBP-3 alleviate age related erectile dysfunction in the rat

PURPOSE

We investigated whether injecting shRNA constructs targeting IGFBP-3 in the penis of old rats would improve erectile function.

MATERIALS AND METHODS

The most validated IGFBP-3 shRNA plasmid vector (pGPU6/GFP/Neo-shIGFBP-3) was prepared and injected in penile corpus cavernosum tissue. A total of 30 old (age 24 months) male Sprague Dawley® rats were randomly divided into 3 groups, including 10 each that received phosphate buffered saline only (100 μl), pGPU6/GFP/Neo-shNC (100 μg) and the most validated plasmid constructs pGPU6/GFP/Neo-shIGFBP-3 (100 μg). At 4 weeks the erectile response was measured as intracavernous pressure. The percent of smooth muscle in corpus cavernosum tissue was evaluated. Nitric oxide synthase activity and the cGMP concentration in penile tissue were also analyzed. IGFBP-3 was estimated in penile tissue by Western blot, real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry.

RESULTS

pGPU6/GFP/Neo-shIGFBP-3 corrected the impaired erectile response in aged rats compared with the response in those injected with phosphate buffered saline and pGPU6/GFP/Neo-shNC (each p <0.01). The percent of cavernous smooth muscle was increased in the pGPU6/GFP/Neo-shIGFBP-3 group. Nitric oxide synthase activity and the cGMP concentration were also significantly increased in rats treated with pGPU6/GFP/Neo-shIGFBP-3. IGFBP-3 shRNA effectively reduced IGFBP-3 mRNA and protein expression in penile corpus cavernosum tissue.

CONCLUSIONS

Decreasing IGFBP-3 expression by plasmid expressed shRNA improved erectile function in aged rats. The therapy may modulate smooth muscle integrity and increase the cGMP concentration. This may be a new direction for treating erectile dysfunction in clinical practice.

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.

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

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

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.

IGFBP3 impedes aggressive growth of pediatric liver cancer and is epigenetically silenced in vascular invasive and metastatic tumors

Background

Hepatoblastoma (HB) is an embryonal liver neoplasm of early childhood with a poor prognosis for patients with distant metastases and vascular invasion. We and others have previously shown that the overexpression of insulin-like growth factor 2 (IGF2), loss of imprinting at the IGF2/H19 locus, and amplification of pleomorphic adenoma gene 1 (PLAG1) are common features in HB, suggesting a critical role of the IGF axis in hepatoblastomagenesis. In this study, we investigated the role of the insulin-like growth factor binding protein 3 (IGFBP3), a known competitor of the IGF axis, in pediatric liver cancers.

Results

The IGFBP3 gene was highly expressed in normal pediatric livers but was heavily downregulated in four HB cell lines and the majority of HB primary tumors (26/36). Detailed methylation analysis of CpG sites in the IGFBP3 promoter region by bisulfite sequencing revealed a high degree of DNA methylation, which is causatively associated with the suppression of IGFBP3 in HB cell lines. Consequently, the treatment of HB cell lines with 5-aza-2'-deoxycytidine resulted in DNA demethylation and reactivation of the epigenetically silenced IGFBP3 expression. Interestingly, IGFBP3 promoter methylation predominantly occurred in metastatic HB with vascular invasion. Restoring IGFBP3 expression in HB cells resulted in reduced colony formation, migration, and invasion.

Conclusion

This study provides the first direct evidence that the reactivation of IGFBP3 decreases aggressive properties of pediatric liver cancer cells and that IGFBP3 promoter methylation might be used as an indicator for vessel-invasive tumor growth in HB patients.

RRR-alpha-vitamin E succinate potentiates the antitumor effect of calcitriol in prostate cancer without overt side effects

PURPOSE

To determine the antitumor efficacy of using calcitriol combined with RRR-alpha-vitamin E succinate (VES) on prostate cancer.

EXPERIMENTAL DESIGN

The effects of VES or VES in combination with calcitriol on the calcitriol target genes were evaluated by Western blot and real-time PCR. The antiproliferation effect of the combination in prostate cancer cells was evaluated by the combination index method. The role of the vitamin D(3) receptor (VDR) in the enhanced antitumor effects of the combination was confirmed by small interfering RNA knockdown strategy. Xenograft-bearing mice were used to reaffirm the antitumor efficacy of this combination. Pathohistology analyses and expressions of VDR and its target genes were analyzed in untreated and treated tumors.

RESULTS

VES selectively increased VDR protein in different prostate cancer cells. Low doses of calcitriol combined with VES were significantly superior to the additive effect of individual treatments against prostate cancer cell proliferation. The expression of VDR target genes involved in antiproliferation were further sensitized in the presence of VES. Knockdown of VDR expression abolished the combination benefits in LNCaP and PC3 cells. Consistently, in prostate cancer xenograft models, VES enhanced the therapeutic efficacy of a tolerated dose of calcitriol yet without overt evidence of systemic toxicity and hypercalcemia. This notable in vivo effect was also accompanied by up-regulation of VDR target genes.

CONCLUSIONS

Low-dose calcitriol combined with vitamin E analogue could be a solution to the calcemic side effect. The demonstration of superior antitumor activity of low-dose calcitriol plus VES provides the preclinical basis for developing a useful therapeutic strategy for prostate cancer.

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.

Associations of insulin-like growth factor (IGF)-I and IGF-binding protein-3 with HIV disease progression in women

BACKGROUND

The insulin-like growth factor (IGF) axis has been hypothesized to influence the rate of human immunodeficiency virus (HIV) disease progression. This premise is based largely on laboratory models showing that IGF-I stimulates thymic growth and increases lymphocyte numbers and that IGF-binding protein (IGFBP)-3 has an opposing effect, inhibiting hematopoietic stem cell development.

METHODS

We studied 1422 HIV-infected women enrolled in a large cohort that entailed semiannual follow-up (initiated in 1994). Baseline serum samples were tested for IGF-I and IGFBP-3 to determine their associations with incident clinical acquired immunodeficiency syndrome (AIDS) and CD4+ T cell count decline prior to April 1996 (before the era of highly active antiretroviral therapy [HAART]).

RESULTS

Low IGF-I levels (Ptrend= .02) and high IGFBP-3 levels (Ptrend= .02) were associated with rapid CD4+ T cell count decline. Only IGFBP-3, however, was significantly associated with AIDS incidence (hazard ratio for highest vs. lowest quartile, 2.65 [95% confidence interval, 1.30-5.42]; Ptrend= .02) in multivariable models.

CONCLUSIONS

These findings suggest that serum levels of IGFBP-3 (and possibly IGF-I) are associated with the rate of HIV disease progression in women and, more broadly, that interindividual heterogeneity in the IGF axis may influence HIV pathogenesis. If correct, the IGF axis could be a target for interventions to slow HIV disease progression and extend the time before use of HAART becomes necessary.

IGFBP-3 regulates esophageal tumor growth through IGF-dependent and independent mechanisms

Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-Ras(V12)-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-1 from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery due to the usual finding of advanced disease at diagnosis. Attempts to improve survival in advanced disease using various combinations of chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Techniques have been developed that allow transfer of functional genes into mammalian cells, such as those that block activated tumor-promoting oncogenes and/or those that replace inactivated tumor-suppressing or apoptosis-promoting genes. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas, and will then review the status of gene therapies for treatment of lung cancer.

1alpha,25-dihydroxy-vitamin D3 stimulation of bronchial smooth muscle cells induces autocrine, contractility, and remodeling processes

Genetic variants in the vitamin D receptor (VDR) gene were recently associated with asthma. The biological mechanisms explaining this association are unknown but are likely to involve many cell types given the pleiotropic effect of its ligand, 1alpha,25-dihydroxy-vitamin D3 [1alpha,25(OH)2D3]. Considering the prominent role of bronchial smooth muscle cells (BSMCs) in the pathogenesis of asthma, experiments were conducted to explore the gene regulatory effects of 1alpha,25(OH)2D3 in these cells. Using RT-PCR and Western blot, we showed that VDR is present both at the mRNA transcript and protein levels in human BSMCs. The functionality of the receptor was then demonstrated by showing a >200-fold change in the expression of the 24-hydroxylase (CYP24A1) gene following 1alpha,25(OH)2D3 stimulation. Microarray experiments were then performed to identify differentially regulated genes and pathways in BMSCs treated or not with 1alpha,25(OH)2D3. A total of 729 probe sets on the U133 plus 2.0 Affymetrix GeneChip showed fold-change differences above the 1.5 threshold using the Robust Multichip Average intensities. This corresponds to 231 unique genes that were upregulated and 215 unique genes that were down-regulated following 1alpha,25(OH)2D3 stimulation. A high similarity between microarray and real-time PCR results was observed for 13 random genes, with a concordance correlation coefficient of 0.91. Real-time PCR was also performed to confirm the regulation of asthma candidate genes. To identify the biological relevance of this regulation, biological pathways analyses were performed. The most significant network of upregulated genes included genes involved in morphogenesis, cell growth, and survival as well as genes encoding structural proteins, which are potentially involved in airway remodeling.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery. This unacceptably low survival rate is due to the usual finding of advanced disease at diagnosis. However, multimodality strategies using conventional therapies only minimally improve survival rates even in early stages of lung cancer. Attempts to improve survival in advanced disease using various combinations of platinum-based chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Over the past three decades, the genetic etiology of cancer has been gradually delineated, albeit not yet completely. Understanding the molecular events that occur during the multistep process of bronchogenic carcinogenesis may make these tasks more surmountable. During these same three decades, techniques have been developed which allow transfer of functional genes into mammalian cells. For example, blockade of activated tumor-promoting oncogenes or replacement of inactivated tumor-suppressing or apoptosis-promoting genes can be achieved by gene therapy. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas and will then review the status of gene therapies for treatment of lung cancer.

Recombinant human insulin-like growth factor binding protein 3 inhibits growth of human epidermal growth factor receptor-2-overexpressing breast tumors and potentiates herceptin activity in vivo

Clinical studies indicate that Herceptin (trastuzumab), a recombinant humanized monoclonal antibody directed against the human epidermal growth factor receptor-2 (HER-2) tyrosine kinase growth factor receptor, provides a significant but transient survival advantage to a subset of patients with HER-2-overexpressing metastatic breast cancer when given as a first-line agent. Increased insulin-like growth factor (IGF)-I receptor (IGF-IR) signaling has recently been identified as a potential factor adversely influencing the response to Herceptin. We examined the effect of recombinant human IGF binding protein 3 (rhIGFBP-3), an antagonist of IGF-IR signaling, in Herceptin-resistant breast cells in vitro and in tumors in vivo. Consistent with results obtained using HER-2- or IGF-IR-transfected cells (MCF-7/HER2-18 and SKBR3/IGF-IR, respectively), we found that rhIGFBP-3 significantly reduced IGF-I-induced IGF-IR phosphorylation and displayed a synergistic interaction with Herceptin against cultured HER-2-overexpressing breast cancer cells in vitro. We show, for the first time, the antitumor activity of rhIGFBP-3 against advanced-stage MCF-7/HER2-18-transfected human breast cancer xenografts and its potentiation of Herceptin activity. We also provide evidence that IGF-IR activation counters the early suppressive effect of Herceptin on HER-2 signaling via Akt and p44/p42 mitogen-activated protein kinase (MAPK), and that inhibition of HER-2-overexpressing human breast tumor growth by rhIGFBP-3 is associated with restored down-regulation of Akt and p44/p42 MAPK phosphorylation in vitro and in vivo. These results emphasize the merit of evaluating simultaneous blockade of the HER-2 and IGF-IR pathways using combination therapy with rhIGFBP-3 plus Herceptin in human clinical trials of patients with HER-2-positive breast cancer.

Nonsecreted insulin-like growth factor binding protein-3 (IGFBP-3) can induce apoptosis in human prostate cancer cells by IGF-independent mechanisms without being concentrated in the nucleus

Insulin-like growth factor binding protein-3 (IGFBP-3), a secreted protein, has the intrinsic ability to induce apoptosis directly without binding insulin-like growth factors. Previous studies suggested that IGFBP-3 must be secreted to exert its biological functions. IGFBP-3 contains a nuclear localization signal (NLS), and exogenous IGFBP-3 is translocated into the nucleus, suggesting that both secretion and nuclear localization may play important roles in IGFBP-3 action. To address these questions, we fused yellow fluorescent protein (YFP) to mature IGFBP-3 lacking its signal peptide so that it would remain intracellular and mutated the C-terminal NLS of IGFBP-3, (228)KGRKR(232), to MDGEA. Following transfection of PC-3 human prostate cancer cells with these constructs, Western blots indicated that YFP-IGFBP-3 lacking a signal peptide was cell-associated and not present in the extracellular media. Moreover, the fusion protein was not N-glycosylated, indicating that it had not entered the secretory pathway. Confocal imaging showed that intracellular YFP-MDGEA-IGFBP-3 was predominantly cytoplasmic. Transient transfection of nonsecreted YFP-wild-type IGFBP-3 decreased cell viability, as assessed by staining with annexin V followed by flow cytometry. Induction of cell death was caspase-dependent, indicative of apoptosis. Apoptosis also was induced by the nonsecreted NLS mutant (YFP-MDGEA-IGFBP-3) alone and when the IGF-binding site also had been mutated. These results indicate that IGFBP-3 can induce apoptosis in an IGF-independent manner without being secreted or concentrated in the nucleus.

Loss of Betaig-h3 protein is frequent in primary lung carcinoma and related to tumorigenic phenotype in lung cancer cells

Betaig-h3 as a secreted protein induced by transforming growth factor-beta has been suggested to modulate cell adhesion and tumor formation. Although we have previously shown that downregulation of Betaig-h3 gene is involved in the cellular transformation of human bronchial epithelial cells induced by radiation, its regulation in primary human lung cancers is not clearly understood. In this study, Betaig-h3 expression was studied in 130 primary human lung carcinomas by immunohistochemistry. Betaig-h3 protein was absent or reduced by more than two-fold in 45 of 130 primary lung carcinomas relative to normal lung tissues examined. Recovery of Betaig-h3 expression in H522 lung cancer cells lacking endogenous Betaig-h3 protein significantly suppressed their in vitro cellular growth and in vivo tumorigenicity. In addition, parental H522 cancer cells are resistant to the etoposide induced apoptosis compared with normal human bronchial epithelial cells. However, recovery of Betaig-h3 expression in H522 cancer cells results in significantly higher sensitivity to apoptotic induction than parental tumor cells. IGFBP3 is upregulated in Betaigh3-transfected H522 cells that may mediate the apoptotic sensitivity and antitumor function of Betaig-h3 gene. These observations demonstrate that downregulation of Betaig-h3 gene is a frequent event and related to the tumor progression in human lung cancer.

Identification of a novel insulin-like growth factor binding protein gene homologue with tumor suppressor like properties

Here we report the identification of a new insulin-like growth factor binding protein homologue, provisionally designated insulin-like growth factor binding related protein-4 (IGFBP-rP4). IGFBP-rP4 was found to be most closely related to IGFBP-7 with 52% amino acid homology and 43% amino acid identity, and shares a similar domain structure. Semi-quantitative RT-PCR expression analysis demonstrated a pattern of downregulation of this gene in multiple tumor samples including lung and colon cancer, compared to matched adjacent normal tissue. Western blotting revealed a protein of approximately 38kDa expressed in both the cell pellet and secreted into the supernatant of transiently transfected Cos-7 cells. Cos-7 supernatants containing IGFBP-RP4 protein were observed to suppress the growth of HeLa cells in culture compared to vector controls. IGFBP-RP4 directly transiently transfected into HeLa cells also further confirmed the growth suppressive properties of this protein. Together these data suggest that IGFBP-RP4 may be a novel putative tumor suppressor protein.

IGFBP-3 Is a Direct Target of Transcriptional Regulation by ΔNp63α in Squamous Epithelium

DeltaNp63alpha is a nuclear transcription factor that maintains epithelial progenitor cell populations, is overexpressed in several epithelial cancers, and can negatively regulate apoptosis. However, the mechanisms by which DeltaNp63alpha promotes cell survival are unclear. DeltaNp63alpha has been reported to act as a transcriptional repressor, but specific target genes directly repressed by DeltaNp63alpha remain unidentified. Here, we present evidence that DeltaNp63alpha functions to negatively regulate the proapoptotic protein IGFBP-3. Disruption of p63 expression in squamous epithelial cells increases IGFBP-3 expression, whereas ectopic expression of DeltaNp63alpha down-regulates IGFBP-3. DeltaNp63alpha binds to sites in the IGFBP-3 gene in vivo and can modulate transcription through these sites. Furthermore, DeltaNp63alpha and IGFBP-3 expression patterns are inversely correlated in normal squamous epithelium and squamous cell carcinomas. These data suggest that IGFBP-3 is a target of transcriptional repression by DeltaNp63alpha and that this repression represents a mechanism by which tumors that overexpress p63 may be protected from apoptosis.

Immunological advantages of advanced laparoscopy

Surgical trauma causes significant alterations in host immune function. Compared with open surgery, laparoscopic surgery is associated with reduced postoperative pain and more rapid return to normal activity. Experimental data have also shown more aggressive tumor establishment and growth rates following open surgery and laparoscopic surgery. Surgery-related immunosuppression may be partly responsible for the differences in cancer growth and outcome noted. It is clear that the choice of abdominal surgical approach has immunologic consequences. Further studies are needed to better the time course and extent of surgery-related alterations in the immune system and their clinical importance. A better understanding of the impact of surgery on the immune system may provide opportunities for pharmacologic manipulation of postoperative immune function to improve clinical results.

The Consequences of Insulin-Like Growth Factors/Receptors Dysfunction in Lung Cancer

The aim of this study was to investigate the consequences of insulin-like growth factors (IGF) and IGF receptor dysfunction in lung carcinomas. A correlation between increased expression (at mRNA and protein levels) for IGF-1 and IGF-1R and decreased apoptosis were found in large-cell carcinomas and adenocarcinomas. In 40% of informative adenocarcinomas expressing the highest values of IGF-2 and Ki-67 proteins, M6P/IGF-2R gene had LOH at one allele and a mutation in another allele. All four squamous cell carcinoma samples expressed LOH/mutation in the M6P/IGF-2R gene. The alphaIR3 strongly diminished proliferation and increased apoptosis in cultures established from squamous cell carcinomas overexpressing IGF-2 and IGF-1R. Telomerase activity was assessed in four squamous cell carcinomas. Cell treatment with IGF-1 increased telomerase activity. The opposite was observed when the cells were treated with alphaIR3, which inhibits the activity of IGF-1 receptors. Our findings suggest that disruption of the IGF/IGF receptors axis is involved in lung cancer formation.

IGFBP-3, a marker of cellular senescence, is overexpressed in human papillomavirus-immortalized cervical cells and enhances IGF-1-induced mitogenesis

Human ectocervical cells, following retroviral transduction with the human papillomavirus type 16 E6/E7 oncogenes, are altered in their array of transcribed cellular genes, including increased mRNA for the insulin-like growth factor binding protein 3 (IGFBP-3). IGFBP-3 expression is associated with cellular senescence, and its addition to many cell types inhibits growth or induces apoptosis. By immunoblotting and enzyme-linked immunosorbent assay methods, we demonstrate that late-passage, immortalized E6/E7-transduced cells secrete high levels of IGFBP-3 (25 ng/ml), which represent a 500-fold increase compared to levels in early-passage, nonimmortalized transduced cells (<0.05 ng/ml). Concomitantly, these late-passage cervical cells exhibit an increase in sensitivity to IGF-1, including enhanced phosphorylation of the IGF receptor (IGF-R) and insulin receptor substrate as well as increased DNA synthesis (5-fold) and cell proliferation (3.7-fold). However, there was no change in the level of IGF-R in these cells (surface or total), and the cells did not synthesize IGF-1, indicating that these arms of the IGF pathway were independently regulated and not responsible for the augmented signaling. Consistent with a causal relationship between IGFBP-3 expression and enhanced IGF-1 responses, we found that early-passage cells could be converted to the late-passage, IGF-1-responsive phenotype by preincubation with IGFBP-3. Thus, in contrast to findings with some cell types, IGFBP-3 expression in cervical cells is associated with augmented IGF-1 signaling and cell proliferation and correlates with the timing of cellular immortalization.

Insulin-like growth factor binding protein-3 expression is associated with growth stimulation of T47D human breast cancer cells: the role of altered epidermal growth factor signaling

IGF binding protein (IGFBP)-3 has antiproliferative and proapoptotic effects on the growth of human breast cancer cells in vitro. However, clinical studies suggest that high levels of IGFBP-3 in breast tumor tissue are associated with large, highly proliferative tumors. In this study, we examined the effects of stable transfection with human IGFBP-3 cDNA on the growth of T47D human breast cancer cells in vitro and in vivo. Expression of IGFBP-3 initially inhibited the growth of T47D in vitro but was associated with enhanced growth in vivo. Furthermore, IGFBP-3-expressing cells in vitro became growth stimulated at higher passages post transfection, suggesting breast cancer cells may switch their response to IGFBP-3 with increasing tumorigenicity. These stimulatory effects observed in IGFBP-3-expressing cells were associated with an enhanced responsiveness to the proliferative effects of epidermal growth factor (EGF). When EGF receptor (EGFR) kinase activity was blocked using PD153035, high passage IGFBP-3 transfectants were growth inhibited compared with controls treated with inhibitor. These findings suggest that the interaction between IGFBP-3 and the EGFR system is central to whether IGFBP-3 acts as a growth stimulator or inhibitor in breast cancer cells and that therapies targeting EGFR may have increased efficacy in breast tumors expressing high levels of IGFBP-3.

A functional genomics approach for the identification of putative tumor suppressor genes: Dickkopf-1 as suppressor of HeLa cell transformation

We described previously the isolation and characterization of two non-tumorigenic revertants from the HeLa cervical carcinoma cell line, and demonstrated that loss of the transformed phenotype in these cells was the result of dominant somatic mutations. The goal of the present study was to use cDNA microarrays to identify candidate tumor suppressors among the set of genes whose increased expression correlated with loss of tumorigenicity in both revertants. Among the genes with significantly increased expression levels in both HA and HF revertants we identified Insulin Growth Factor Binding Protein-3 (IGFBP-3) and the Dickkopf-1 (DKK-1) genes. Both of these genes encode secreted proteins implicated in the modulation cell growth and differentiation, and IGFBP-3 was shown previously to have tumor suppressing activity. To test the hypothesis that increased expression of IGFBP-3 or the DKK-1 genes could have contributed to the suppression of tumorigenicity in the revertants, we expressed IGFBP-3 or DKK-1 in HeLa cells, and assessed their effects on anchorage dependent and independent growth, and tumor formation in athymic nude mice. Ectopic expression of IGFBP-3 or DKK-1 resulted in significantly decreased growth in soft agar. HeLa cells expressing ectopic IGFBP-3 or DKK-1 showed statistically significant differences in the kinetics of tumor formation. In any tumors that arose in animals injected with the IGFBP-3 expressing cells, there was a complete loss of IGFBP-3 activity, as measured by binding to IGF-1 and IGF-2 proteins. All tumors that arose after injection of cells expressing DKK-1, invariably showed almost a complete loss of ectopic DKK-1 expression. The observations that loss of DKK-1 expression or IGFBP-3 activity was required for tumorigenicity suggested that both proteins encode putative tumor suppressor genes. We also show that while DKK-1 expression does not affect cell growth in vitro, the protein does sensitize cells to apoptosis. We also demonstrated that effect of DKK-1 was not due to inhibition of beta-catenin/TCF4-regulated transcription. Taken together, our results indicate that somatic cell genetics combining with gene expression profiling may be a useful approach for the identification of functional suppressors of malignant cell growth.

Lung cancer. 9: Molecular biology of lung cancer: clinical implications

It has been hypothesised that clinically evident lung cancers have accumulated many different genetic or epigenetic abnormalities in oncogenes and/or tumour suppressor genes. This notion has important clinical ramifications. Recent developments in our knowledge of the molecular biology of lung cancer are reviewed, with particular reference to genetic abnormalities in tumour suppressor gene inactivation and overactivity of growth promoting oncogenes. These changes lead to the "hallmarks of lung cancer". These hallmarks are the new rational targets for early detection, prevention, and treatment of lung cancer.

Endotoxin decreases serum IGFBP-3 and liver IGFBP-3 mRNA: comparison between Lewis and Wistar rats

We studied the IGFBP-3 response to endotoxin, in Wistar and Lewis rats. Compared to Wistar rats, Lewis rats have a reduced adrenal and IGF-I response to inflammatory stimuli. Rats received two injections of 1 mg/kg of lipopolysaccharide (LPS) and were killed 4 h after the second injection. LPS decreased serum concentrations of GH in Wistar (P<0.05), but not in Lewis rats. However, serum IGFBP-3 was decreased both in Wistar and in Lewis rats. Furthermore, LPS administration decreased IGFBP-3 gene expression in the liver in both rat strains (P<0.01). Lewis rats had lower serum IGFBP-3 than Wistar rats (P<0.01). This difference could be secondary to the increased IGFBP-3 proteolysis in serum observed in Lewis rats. These data indicate that acute inflammation inhibits serum concentrations of IGFBP-3 by decreasing its synthesis in the liver, rather than increasing its proteolysis. This effect seems to be GH and IGF-I independent.

Cellular actions of the insulin-like growth factor binding proteins

In addition to their roles in IGF transport, the six IGF-binding proteins (IGFBPs) regulate cell activity in various ways. By sequestering IGFs away from the type I IGF receptor, they may inhibit mitogenesis, differentiation, survival, and other IGF-stimulated events. IGFBP proteolysis can reverse this inhibition or generate IGFBP fragments with novel bioactivity. Alternatively, IGFBP interaction with cell or matrix components may concentrate IGFs near their receptor, enhancing IGF activity. IGF receptor-independent IGFBP actions are also increasingly recognized. IGFBP-1 interacts with alpha(5)beta(1) integrin, influencing cell adhesion and migration. IGFBP-2, -3, -5, and -6 have heparin-binding domains and can bind glycosaminoglycans. IGFBP-3 and -5 have carboxyl-terminal basic motifs incorporating heparin-binding and additional basic residues that interact with the cell surface and matrix, the nuclear transporter importin-beta, and other proteins. Serine/threonine kinase receptors are proposed for IGFBP-3 and -5, but their signaling functions are poorly understood. Other cell surface IGFBP-interacting proteins are uncharacterized as functional receptors. However, IGFBP-3 binds and modulates the retinoid X receptor-alpha, interacts with TGFbeta signaling through Smad proteins, and influences other signaling pathways. These interactions can modulate cell cycle and apoptosis. Because IGFBPs regulate cell functions by diverse mechanisms, manipulation of IGFBP-regulated pathways is speculated to offer therapeutic opportunities in cancer and other diseases.

Insulin-like growth factor-I inhibits cell growth in the a549 non-small lung cancer cell line

Insulin-like growth factors (IGFs) are potent mitogenic and antiapoptotic factors for many cell types, including some normal and neoplastic lung cells in vitro. However, in this study we show that IGF-I, at concentrations of 10 ng/ml or greater, significantly inhibits DNA synthesis and cell proliferation in a human lung adenocarcinoma cell line, A549. Inhibition of DNA synthesis was completely reversed by an IGF-I receptor-neutralizing antibody, alphaIR-3, indicating that IGF-I receptor activation is involved in its inhibitory effect. Attenuation of the p44/42 mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3'-kinase (PI 3'-kinase) pathways downstream of the IGF-I receptor using the inhibitors PD98059 and LY294002, respectively, partially reversed IGF-I-induced inhibition. Acute (2-60 min) and chronic (24 h) exposure of A549 cells to 100 ng/ml IGF-I resulted in sustained phosphorylation of Akt/protein kinase B downstream of PI 3'-kinase, whereas p44/42 MAPK phosphorylation was decreased in response to chronic exposure to IGF-I. An IGF-I dose-dependent increase in the cyclin-dependent kinase inhibitor p21(Cip1/WAF1) was also observed over 24 h of treatment. Collectively, these data suggest that IGF-I is growth inhibitory to A549 cells, possibly via sustained activation of the PI 3'-kinase signaling pathway, and induction of p21(Cip1/WAF1).

Differential expression of insulin-like growth factor I and II mRNAs during embryogenesis and early larval development in rabbitfish, Siganus guttatus

In rodents, the expression of insulin-like growth factor II (IGF-II) is higher than that of insulin-like growth factor I (IGF-I) during fetal life while the reverse is true after birth. We wanted to examine whether this is also true in fish and whether IGF-I and IGF-II are differentially regulated during different stages of embryogenesis and early larval development in rabbitfish. We first cloned the cDNAs of rabbitfish IGF-I and IGF-II from the liver. Rabbitfish IGF-I has an open reading frame of 558 bp that codes for a signal peptide of 44 amino acids (aa), a mature protein of 68 aa, and a single form of E domain of 74 aa. Rabbitfish IGF-II, on the other hand, has an open reading frame of 645 bp that codes for a signal peptide of 47 aa, a mature protein of 70 aa, and an E domain of 98 aa. On the amino acid level, rabbitfish IGF-I shares 68% similarity with IGF-II. We then examined the relative expression of the two IGFs in unfertilized eggs, during different stages of embryogenesis, and in early larval stages of rabbitfish by a semiquantitative reverse transcription-polymerase chain reaction. Primers that amplify the mature peptide region of both IGFs were used and PCR for both peptides was done simultaneously, with identical PCR conditions for both. The identity of the PCR products was confirmed by direct sequencing. Contrary to published reports for seabream and rainbow trout, IGF-I mRNA was not detected in rabbitfish unfertilized eggs; it was first expressed in larvae soon after hatching. IGF-II mRNA, however, was expressed in unfertilized eggs, albeit weakly, and was already strongly expressed during the cleavage stage. mRNAs for both peptides were strongly expressed in the larvae, although IGF-II mRNA expression was higher than IGF-I expression.

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 (IGF)-binding protein-3 (IGFBP-3) can stimulate apoptosis and inhibit cell proliferation directly and independently of binding IGFs or indirectly by forming complexes with IGF-I and IGF-II that prevent them from activating the IGF-I receptor to stimulate cell survival and proliferation. To date, IGF-independent actions only have been demonstrated in a limited number of cells that do not synthesize or respond to IGFs. To assess the general importance of IGF-independent mechanisms, we have generated human IGFBP-3 mutants that cannot bind IGF-I or IGF-II by substituting alanine for six residues in the proposed IGF binding site, Ile(56)/Tyr(57)/Arg(75)/Leu(77)/Leu(80)/Leu(81), and expressing the 6m-hIGFBP-3 mutant construct in Chinese hamster ovary cells. Binding of both IGF-I and IGF-II to 6m-hIGFBP-3 was reduced >80-fold. The nonbinding 6m-hIGFBP-3 mutant still was able to inhibit DNA synthesis in a mink lung epithelial cell line in which inhibition by wild-type hIGFBP-3 previously had been shown to be exclusively IGF-independent. 6m-hIGFBP-3 only can act by IGF-independent mechanisms since it is unable to form complexes with the IGFs that inhibit their action. We next compared the ability of wild-type and 6m-hIGFBP-3 to stimulate apoptosis in serum-deprived PC-3 human prostate cancer cells. PC-3 cells are known to synthesize and respond to IGF-II, so that IGFBP-3 could potentially act by either IGF-dependent or IGF-independent mechanisms. In fact, 6m-hIGFBP-3 stimulated PC-3 cell death and stimulated apoptosis-induced DNA fragmentation to the same extent and with the same concentration dependence as wild-type hIGFBP-3. These results indicate that IGF-independent mechanisms are major contributors to IGFBP-3-induced apoptosis in PC-3 cells and may play a wider role in the antiproliferative and antitumorigenic actions of IGFBP-3.

Reduced expression of insulin-like growth factor binding protein-3 and its promoter hypermethylation in human hepatocellular carcinoma

Insulin-like growth factor binding protein-3 (IGFBP-3) is postulated to be a mediator of growth suppression signals. Reduced expression of the IGFBP-3 was observed in nine out of 12 human hepatocellular carcinomas (HCC) (75%). Promoter hypermethylation of the IGFBP-3 was detected in four out of 12 HCCs (33%) although mutations were not identified. The expression of IGFBP-3 was restored by the demethylating agent 5-aza-2'-deoxycytidine in HCC cell line with promoter hypermethylation (HepG2). As IGFBP-3 functions like a tumor suppressor gene, it may be used as a therapeutic target for HCC.