Insulin-like growth factor binding protein-4 gene silencing in lung adenocarcinomas

Activation of IGFBP4 via unconventional mechanism of miRNA attenuates metastasis of intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver malignancy. Although its incidence is lower than that of hepatocellular carcinoma (HCC), ICC has a worse prognosis, and it is more prone to recur and metastasize, resulting in a far greater level of malignancy.

METHODS

Bioinformatics analysis and qRT-PCR were applied to assess the level of miR-122-5p and IGFBP4. Western blot, transwell assays, wound-healing assays, real-time cellular invasion monitoring, in vivo study were applied to explore the function of miR-122-5p and IGFBP4. Dual luciferase reporter assays and chromatin isolation by RNA purification (ChiRP) were applied to explore the regulation of IGFBP4 by miR-122-5p.

RESULTS

Using The Cancer Genome Atlas (TCGA) data set, Sir Run Run Shaw hospital data set and bioinformatics analyses, we identified miR-122-5p as a potential tumor suppressor in ICC and validated its suppressive effect in metastasis and invasion of ICC. Transcriptome sequencing, rescue and complement experiments were used to identify insulin-like growth factor binding protein 4 (IGFBP4) as a target of miR-122-5p. The mechanism by which miR-122-5p regulates IGFBP4 was clarified by chromatin separation RNA purification technology, and dual-luciferase reporter assays. We discovered a rare novel mechanism by which miR-122-5p promotes IGFBP4 mRNA transcription by binding to its promoter region. Furthermore, in mouse orthotopic metastasis model, miR-122-5p inhibited the invasion of ICC.

CONCLUSION

In summary, our study revealed a novel mechanism of miR-122-5p and function of the miR-122-5p/IGFBP4 axis in the metastasis of ICC. We also highlighted the clinical value of miR-122-5p and IGFBP4 in inhibiting ICC invasion and metastasis.

AKAP12 and IGFBP4 Are Prognostic Factors for Chronic Lymphocytic Leukemia

INTRODUCTION

The aim of this study was to develop a prognostic model for chronic lymphocytic leukemia (CLL).

METHODS

GEO2R was used to retrieve the gene expression data of CLL and normal B cells from the Gene Expression Omnibus (GEO; GSE22529 and GSE50006 datasets) database. Practical Extraction and Report Language was used to extract the gene expression and overall survival (OS) data of CLL patients from the Chronic Lymphocytic Leukemia - ES (CLLE-ES) project in the International Cancer Genome Consortium (ICGC) database. Cox regression with Lasso was used to create and validate a prognostic model for CLL.

RESULTS

A total of 267 genes exhibited differential expression between CLL and normal B cells. Cox univariate analysis identified 14 DEGs that correlated with OS. Lasso multivariate evaluation demonstrated that AKAP12 and IGFBP4 are independent prognostic factors for CLL. Kaplan-Meier survival analysis revealed a significant association between the estimated risk score and survival. The area under the receiver operating characteristic curve was calculated to be 0.97, indicating high predictive accuracy. In addition, high AKAP12 and IGFBP4 risk scores were associated with the high incidence of trisomy 12q.

CONCLUSION

Taken together, AKAP12 and IGFBP4 are independent prognostic factors for CLL.

Regulation of Metabolic Reprogramming by Long Non-Coding RNAs in Cancer

Metabolic reprogramming is a well described hallmark of cancer. Oncogenic stimuli and the microenvironment shape the metabolic phenotype of cancer cells, causing pathological modifications of carbohydrate, amino acid and lipid metabolism that support the uncontrolled growth and proliferation of cancer cells. Conversely, metabolic alterations in cancer can drive changes in genetic programs affecting cell proliferation and differentiation. In recent years, the role of non-coding RNAs in metabolic reprogramming in cancer has been extensively studied. Here, we review this topic, with a focus on glucose, glutamine, and lipid metabolism and point to some evidence that metabolic alterations occurring in cancer can drive changes in non-coding RNA expression, thus adding an additional level of complexity in the relationship between metabolism and genetic programs in cancer cells.

Anticancer mechanism of breviscapine in non-small cell lung cancer A549 cells acts via ROS-mediated upregulation of IGFBP4

Background

The overall 5-year survival rate of non-small cell lung cancer (NSCLC) is less than 15% because of multiple drug resistance to chemotherapy and the limitations of early diagnosis. Thus, safe and effective drugs to treat NSCLC are required. The present study aimed to investigate the effects of breviscapine (BVP) on NSCLC cell apoptosis and proliferation, and to study its possible mechanisms.

Methods

Using the NSCLC A549 cell line and BVP (0, 25, 50, and 100 µM), the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect A549 cell proliferation, and flow cytometry was used to assess cell apoptosis. Insulin-like growth factor binding protein 4 (IGFBP4) levels was assessed using enzyme-linked immunosorbent assays and western blotting. Flow cytometry of hydrogen peroxide and superoxide was used to assess intracellular reactive oxygen species (ROS) generation. Western blotting was used to assess the levels of BCL2-associated X, apoptosis regulator (BAX) and B-cell CLL/lymphoma 2 (BCL2). Quantitative real-time reverse transcription PCR (qRT-PCR) was used to assess IGFBP4 mRNA expression.

Results

BVP induced apoptosis, inhibited cell proliferation, and increased ROS in A549 cells. Western blotting and qRT-PCR showed that BVP increased IGFBP4 protein and mRNA expressions in A549 cells. Compared with BVP treatment alone, IGFBP4 expression decreased in A549 cells treated with BVP and the ROS scavenger N-acetylcysteine. IGFBP4 overexpression increased BVP-induced proliferation inhibition, while increasing BAX expression and decreasing BCL2 expression. Silencing IGFBP4 had the opposite effects.

Conclusions

BVP could inhibit the growth of NSCLC A549 cells by promoting apoptosis via ROS-mediated upregulation of IGFBP4.

The Interplay Between Non-coding RNAs and Insulin-Like Growth Factor Signaling in the Pathogenesis of Neoplasia

The insulin-like growth factors (IGFs) are polypeptides with similar sequences with insulin. These factors regulate cell growth, development, maturation, and aging via different processes including the interplay with MAPK, Akt, and PI3K. IGF signaling participates in the pathogenesis of neoplasia, insulin resistance, diabetes mellitus, polycystic ovarian syndrome, cerebral ischemic injury, fatty liver disease, and several other conditions. Recent investigations have demonstrated the interplay between non-coding RNAs and IGF signaling. This interplay has fundamental roles in the development of the mentioned disorders. We designed the current study to search the available data about the role of IGF-associated non-coding RNAs in the evolution of neoplasia and other conditions. As novel therapeutic strategies have been designed for modification of IGF signaling, identification of the impact of non-coding RNAs in this pathway is necessary for the prediction of response to these modalities.

IGFBP-4: A promising biomarker for lung cancer

Background: Insulin-like growth factor binding protein-4 (IGFBP-4), a member of the insulin-like growth factor (IGF) family, transports, and regulates the activity of IGFs. The pregnancy-associated plasma protein-A (PAPP-A) has proteolytic activity towards IGFBP-4, and both proteins have been associated with a variety of cancers, including lung cancer. Thus, we aimed to evaluate the use of IGFBP-4 and PAPP-A as potential biomarkers for lung cancer. Methods: Eighty-three volunteers, including 60 patients with lung cancer and 23 healthy individuals, were included in this study. The patients with lung cancer were selected based on their treatment status, histological subgroup, and stage of the disease. Enzyme-linked immunosorbent assays were used to assess the serum levels of IGFBP-4 and PAPPA, whereas the IGF-1 levels were measured using a chemiluminescent immunometric assay. Results: The serum IGFBP-4 levels in all patient groups, regardless of the treatment status and histological differences, were significantly higher than those in the control group (p<0.005). However, the serum PAPP-A levels in the untreated patient group were found to be higher than those in the control group, but this difference was not statistically significant (p=0.086). Conclusions: The serum PAPP-A and IGFBP-4 levels are elevated in lung cancer. However, IGFBP-4 may have better potential than PAPP-A as a lung cancer biomarker.

DNA methylome and transcriptome alterations and cancer prevention by curcumin in colitis-accelerated colon cancer in mice

Inflammation is highly associated with colon carcinogenesis. Epigenetic mechanisms could play an important role in the initiation and progression of colon cancer. Curcumin, a dietary phytochemical, shows promising effects in suppressing colitis-associated colon cancer in azoxymethane-dextran sulfate sodium (AOM-DSS) mice. However, the potential epigenetic mechanisms of curcumin in colon cancer remain unknown. In this study, the anticancer effect of curcumin in suppressing colon cancer in an 18-week AOM-DSS colon cancer mouse model was confirmed. We identified lists of differentially expressed and differentially methylated genes in pairwise comparisons and several pathways involved in the potential anticancer effect of curcumin. These pathways include LPS/IL-1-mediated inhibition of RXR function, Nrf2-mediated oxidative stress response, production of NO and ROS in macrophages and IL-6 signaling. Among these genes, Tnf stood out with decreased DNA CpG methylation of Tnf in the AOM-DSS group and reversal of the AOM-DSS induced Tnf demethylation by curcumin. These observations in Tnf methylation correlated with increased and decreased Tnf expression in RNA-seq. The functional role of DNA methylation of Tnf was further confirmed by in vitro luciferase transcriptional activity assay. In addition, the DNA methylation level in a group of inflammatory genes was decreased in the AOM+DSS group but restored by curcumin and was validated by pyrosequencing. This study shows for the first time epigenomic changes in DNA CpG methylation in the inflammatory response from colitis-associated colon cancer and the reversal of their CpG methylation changes by curcumin. Future clinical epigenetic studies with curcumin in inflammation-associated colon cancer would be warranted.

IGFBP-4 and PAPP-A in normal physiology and disease

Insulin-like growth factor (IGF) binding protein-4 (IGFBP-4) is a modulator of the IGF system, exerting both inhibitory and stimulatory effects on IGF-induced cellular growth. IGFBP-4 is the principal substrate for the enzyme pregnancy-associated plasma protein-A (PAPP-A). Through IGF-dependent cleavage of IGFBP-4 in the vicinity of the IGF receptor, PAPP-A is able to increase IGF bioavailability and stimulate IGF-mediated growth. Recently, the stanniocalcins (STCs) were identified as novel inhibitors of PAPP-A proteolytic activity, hereby adding additional members to the seemingly endless list of proteins belonging to the IGF family. Our understanding of these proteins has advanced throughout recent years, and there is evidence to suggest that the role of IGFBP-4 and PAPP-A in defining the relationship between total IGF and IGF bioactivity can be linked to a number of pathological conditions. This review provides an overview of the experimental and clinical findings on the IGFBP-4/PAPP-A/STC axis as a regulator of IGF activity and examines the conundrum surrounding extrapolation of circulating concentrations to tissue action of these proteins. The primary focus will be on the biological significance of IGFBP-4 and PAPP-A in normal physiology and in pathophysiology with emphasis on metabolic disorders, cardiovascular diseases, and cancer. Finally, the review assesses current new trajectories of IGFBP-4 and PAPP-A research.

IGF-binding proteins

Insulin-like growth factor-binding proteins (IGFBPs) 1-6 bind IGFs but not insulin with high affinity. They were initially identified as serum carriers and passive inhibitors of IGF actions. However, subsequent studies showed that, although IGFBPs inhibit IGF actions in many circumstances, they may also potentiate these actions. IGFBPs are widely expressed in most tissues, and they are flexible endocrine and autocrine/paracrine regulators of IGF activity, which is essential for this important physiological system. More recently, individual IGFBPs have been shown to have IGF-independent actions. Mechanisms underlying these actions include (i) interaction with non-IGF proteins in compartments including the extracellular space and matrix, the cell surface and intracellular space, (ii) interaction with and modulation of other growth factor pathways including EGF, TGF-β and VEGF, and (iii) direct or indirect transcriptional effects following nuclear entry of IGFBPs. Through these IGF-dependent and IGF-independent actions, IGFBPs modulate essential cellular processes including proliferation, survival, migration, senescence, autophagy and angiogenesis. They have been implicated in a range of disorders including malignant, metabolic, neurological and immune diseases. A more complete understanding of their cellular roles may lead to the development of novel IGFBP-based therapeutic opportunities.

What Happened to the IGF Binding Proteins?

Insulinlike growth factor (IGF) binding proteins (IGFBPs) 1 to 6 are high-affinity regulators of IGF activity. They generally inhibit IGF actions by preventing binding to the IGF-I receptor but can also enhance their actions under some conditions. Posttranslational modifications such as glycosylation and phosphorylation modulate IGFBP properties, and IGFBP proteolysis results in IGF release. IGFBPs have more recently been shown to have IGF-independent actions. A number of mechanisms are involved, including modulation of other growth factor pathways, nuclear localization and transcriptional regulation, interaction with the sphingolipid pathway, and binding to non-IGF biomolecules in the extracellular space and matrix, on the cell surface and intracellularly. IGFBPs modulate important biological processes, including cell proliferation, survival, migration, senescence, autophagy, and angiogenesis. Their actions have been implicated in growth, metabolism, cancer, stem cell maintenance and differentiation, and immune regulation. Recent studies have shown that epigenetic mechanisms are involved in the regulation of IGFBP abundance. A more complete understanding of IGFBP biology is necessary to further define their cellular roles and determine their therapeutic potential.

Overexpression of lncRNA IGFBP4-1 reprograms energy metabolism to promote lung cancer progression

BACKGROUND

Reprogrammed energy metabolism as an emerging hallmark of cancer has recently drawn special attention since it facilitate cell growth and proliferation. Recently, long noncoding RNAs (lncRNAs) have been served as key regulators implicated in tumor development and progression by promoting proliferation, invasion and metastasis. However, the associations of lncRNAs with cellular energy metabolism in lung cancer (LC) need to be clarified.

METHODS

Here, we conducted bioinformatics analysis and found insulin-like growth factor binding protein 4-1 (IGFBP4-1) as a new candidate lncRNA located in the upstream region of IGFBP4 gene. The expression levels of lnc-IGFBP4-1, mRNA levels of IGFBP4 in 159 paired lung cancer samples and adjacent, histological normal tissues by qRT-PCR. Over-expression and RNA interference (RNAi) approaches were adopted to investigate the biological functions of lnc-IGFBP4-1. The intracellular ATP level was measured using the Cell Titer-Glo Luminescent Cell Viability Assay kit, and changes in metabolic enzymes were examined in cancer cells and normal pulmonary epithelial cells with qRT-PCR.

RESULTS

Our results showed that lnc-IGFBP4-1 was significantly up-regulated in LC tissues compared with corresponding non-tumor tissues (P < 0.01), and its expression level was significantly correlated with TNM stage (P < 0.01) and lymph node metastasis (P < 0.05). Further investigation showed that overexpression of lnc-IGFBP4-1 significantly promoted LC cell proliferation in vitro and in vivo, while downregulation of endogenous lnc-IGFBP4-1 could inhibited cell proliferation and induce apoptosis. Moreover, we found lnc-IGFBP4-1 could influences ATP production levels and expression of enzymes including HK2, PDK1 and LDHA, in addition, decline in both ATP production and these enzymes in response to 2-DG and 2-DG-combined Rho123, respectively, was observed in lnc-IGFBP4-1-overespressing LC cells, indicative of an enhanced aerobic glycolysis rate. Finally, lnc-IGFBP4-1 was observed to negatively correlate with gene IGFBP4, and lower expression level of IGFPB4 was found after lnc-IGFBP4-1-overexpression was transfected into PC9 cells, higher expression level of IGFPB4 was also found after lnc-IGFBP4-1-downregulation was transfected into GLC-82 cells, which indicates that IGFBP4 may exert its targeting function regulated by lnc-IGFBP4-1.

CONCLUSIONS

Taken together, these findings provide the first evidence that lnc-IGFBP4-1 is significantly up-regulated in LC tissues and plays a positive role in cell proliferation and metastasis through possible mechanism of reprogramming tumor cell energy metabolism, which suggests that lnc-IGFBP4-1 may be a promising biomarker in LC development and progression and as a potential therapeutic target for LC intervention.

Insulin treatment before resuscitation following hemorrhagic shock improves cardiac contractility and protects the myocardium in the isolated rat heart

Background:

Insulin has been shown to exert positive inotropic effects in several in vivoex vivo models and in human hearts. Resuscitation following hemorrhagic shock results in myocardial contractile dysfunction. However, the optimal timing for treatment with insulin for the cardioprotection effects is unclear.

Objectives:

The objective of this study was to test the hypothesis that treatment with insulin before resuscitation provides better cardioprotection than treatment with insulin after resuscitation.

Materials and Methods:

Rats were assigned to 3 experimental groups (n = 6 per group): (1) Hemorrhagic shock and resuscitation, (2) hemorrhagic shock resuscitated then treated with insulin and (3) hemorrhagic shock treated with insulin before resuscitation. Rats were hemorrhaged for 60 min to rach mean arterial blood pressure of 40 mmHg. Rats were resuscitated in vivo by reinfusion of the shedded blood to restore normotension and monitored for 60 min. Rats were treated or not with insulin 200 μU/g body weight intramuscularly either before or after resuscitation. The maximum of the left ventricular developed pressure (+dP/dt) was measured for 60 min in the isolated perfused hearts using the Langendorff method. Blood samples were obtained for measurements of tumor necrosis factor-alpha (TNF-α).

Results:

Treatment with insulin before resuscitation following hemorrhagic shock significantly elevated max dP/dt compared with insulin treatment after resuscitation and the untreated group. TNF-α levels were lower in the insulin treatment before resuscitation compared to the treatment after resuscitation and the untreated group.

Conclusion:

Insulin treatment before resuscitation following hemorrhagic shock provides better cardiac protection than treatment with insulin after resuscitation, as evidenced by the improved myocardial contractility, preservation of myocardial structure. The mechanism of cardiac protection involves decrease in the inflammatory response to shock by lowering the levels of TNF.

IGF binding proteins in cancer: mechanistic and clinical insights

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

Characterization of the insulin-like growth factor axis in term pregnancies complicated by maternal obesity

STUDY QUESTION

Does maternal obesity affect insulin-like growth factor (IGF) axis protein expression patterns in maternal and cord blood?

SUMMARY ANSWER

Maternal obesity attenuates cord blood expression of IGF-binding protein (IGFBP)-4.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

The IGF axis plays a critical role in fetal growth and development. Maternal obesity compromises IGF axis protein expression in fetal circulation, which is consistent with the findings of epidemiological studies suggesting that maternal obesity has an independent effect on fetal growth signals during in utero development.

STUDY DESIGN

This cross-sectional case-control study involved 12 lean [body mass index (BMI) 18.5-24.9 kg/m2] and 12 obese (BMI≥30 kg/m2) women and their neonates at term. At the completion of the study, IGF axis protein expression and hormone concentrations in both maternal and cord blood were examined.

PARTICIPANTS AND SETTING

We obtained fasting serum samples from cases and controls matched for age, gestation, mode of delivery, parity and glucose tolerance prior to and immediately following elective caesarean section. The corresponding umbilical cord blood was also collected at birth.

MAIN RESULTS AND THE ROLE OF CHANCE

Between-group comparisons revealed elevated maternal insulin (P=0.03) and leptin (P<0.01) concentrations in obese gravidas. After adjustment, the maternal homeostasis model of assessment-insulin resistance (HOMA-IR) score was positively correlated with both maternal BMI and leptin levels (P<0.01). Umbilical cord blood levels of IGFBP-3 showed an inverse trend to maternal HOMA-IR (P=0.03) but were directly related to the fetal-placental weight ratio (P<0.01). In cord serum from obese mothers, IGFBP-4 expression was attenuated compared with the controls (P<0.05).

LIMITATIONS

The limitations of our study include the cross-sectional design and relatively small sample size.

WIDER IMPLICATIONS

Our results provide preliminary evidence for the applicability of our findings to other ethnic groups when pregnancy is complicated by obesity.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the University of Ottawa, Faculty of Health Sciences/Children's Hospital of Eastern Ontario Research Partnership Grant awarded to K.B.A. and Z.M.F. The authors have no conflicts of interest to declare.