Changes of serum growth factors (IGF-I,-II and IGFBP-2,-3) prior to and after stem cell transplantation in children with acute leukemia

Hsa_circ_0036872 has an important promotional effect in enhancing osteogenesis of dental pulp stem cells by regulating the miR-143-3p/IGF2 axis

BACKGROUND

Circular RNAs (circRNAs), an extremely stable group of RNAs, possess a covalent closed-loop configuration. Numerous studies have highlighted the involvement of circRNAs in physiological processes and the development of various diseases. The present study aimed to investigate how circRNA regulates the osteogenic differentiation of human dental pulp stem cells (hDPSCs).

METHODS

We isolated hDPSCs from dental pulp and used next-generation sequencing analysis to determine the differentially-expressed circRNAs during osteogenic differentiation. Bioinformatics and dual-luciferase reporter assays identified the downstream targets. The role of circRNAs in osteogenic differentiation was further confirmed through the use of heterotopic bone models.

RESULTS

We found that hsa_circ_0036872 expression was increased during osteogenic differentiation of hDPSCs, and downregulation of hsa_circ_0036872 inhibited their osteogenic differentiation. Dual-luciferase reporter assays showed that both miR-143-3p and IGF2 were downstream targets of hsa_circ_0036872. Overexpression of IGF2 or inhibition of miR-143-3p restored the osteogenic differentiation ability of hDPSCs after silencing hsa_circ_0036872. Overexpression of IGF2 reversed the inhibitory effect of miR-143-3p on osteogenic differentiation.

CONCLUSION

Taken together, our results show that hsa_circ_0036872 exerts an important promotional effect in enhancing the osteogenesis of dental pulp stem cells by regulating the miR-143-3p/IGF2 axis. These data suggest a novel therapeutic strategy for osteoporosis treatment and periodontal tissue regeneration.

Concentrations of Insulin-like Growth Factors and Insulin-like Growth Factor-Binding Proteins and Respective Gene Expressions in Children before and after Hematopoietic Stem Cell Transplantation

Insulin-like growth factors (IGF-1 and IGF-2) and insulin-like growth factor-binding proteins (IGFBP-1 to -7) are involved in the regulation of cell proliferation and differentiation and may be associated with various metabolic parameters. The aim of our study was to compare levels of IGFs and IGFBPs and the expressions of their genes in children before and after hematopoietic stem cell transplantation (HSCT) to assess their potential as markers of late metabolic complications of HSCT. We also conducted additional comparisons with healthy controls and of correlations of IGF and IGFBP levels with anthropometric and biochemical parameters. We analyzed 19 children treated with HSCT and 21 healthy controls. We found no significant differences in the levels of IGFs and IGFBPs and expressions of their genes before and after HSCT, while IGF and IGFBP levels were significantly lower in children treated with HSCT compared with controls. We conclude that our results did not reveal significant differences between the levels of IGFs and IGFBPs before and after HSCT, which would make them obvious candidates for markers of late complications of the procedure in children. However, due to the very low number of patients this conclusion must be taken with caution and may be altered by further research.

Insulin-like growth factor 2-enhanced osteogenic differentiation of stem cell spheroids by regulation of Runx2 and Col1 expression

Insulin-like growth factor 2 (IGF-2) is a growth factor that is involved in various functions of cells, including stem cells. The effects of IGF-2 on the cellular viability and osteogenic differentiation of stem cell spheroids were investigated in the present study. Stem cell spheroids were formed using concave microwells in the presence of IGF-2 at final concentrations of 0, 10 and 100 ng/ml. Cellular viability was measured qualitatively using a microscope and quantitatively using an assay kit based on water-soluble tetrazolium salt. The level of alkaline phosphatase activity, and an anthraquinone dye assay for calcium deposit evaluation, were used to assess osteogenic differentiation. A quantitative PCR analysis was conducted to evaluate the expression of Runx2 and Col1. Spheroid formation was noticed on day 1 in the microwells, and the spheroidal shape was maintained up to day 7. The cell viability assay values for IGF-2 at 0, 10 and 100 ng/ml at day 1 were 0.193±0.002, 0.191±0.002 and 0.201±0.006, respectively (P>0.05). The absorbance values at 405 nm for the alkaline phosphatase activity assays on day 21 were 0.221±0.006, 0.375±0.010 and 0.280±0.015 for IGF-2 at 0, 10 and 100 ng/ml, respectively. There were significantly higher values for IGF-2 in the 10 and 100 ng/ml groups when compared with the control (P<0.05). Significantly higher Alizarin red staining was noted for IGF-2 in the 10 ng/ml group when compared with the unloaded control at day 21 (P<0.05). Quantitative PCR revealed that mRNA levels of Runx2 and Col1 were significantly higher at 100 ng/ml on day 7. Conclusively, the present study demonstrated that the application of IGF-2 increased alkaline phosphatase activity, Alizarin red staining, and Runx2 and Col1 expression of stem cell spheroids.

IGFBP2: integrative hub of developmental and oncogenic signaling network

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

Gestational age and childhood leukemia: A meta-analysis of epidemiologic studies

OBJECTIVE

An increasing amount of evidence shows that childhood leukemia is initiated in utero. Birth characteristics initiated in utero, such as gestational age, may play a role in leukemogenesis. The purpose of our meta-analysis is to explore the association between gestational age and childhood leukemia.

METHODS

Relevant studies up to 21 April 2017 were collected by searching PubMed and EMBASE databases. Subgroup analysis, sensitivity analysis and publication bias assessment were conducted.

RESULTS

A total of 13 studies were included. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) for preterm birth and postterm birth were 1.06 (0.98, 1.13) and 1.01 (0.90, 1.13) for childhood leukemia, 1.04 (0.97, 1.11) and 1.03 (0.95, 1.12) for acute lymphocytic leukemia (ALL), 1.20 (1.00, 1.44) and 1.20 (1.00, 1.43) for acute myeloid leukemia (AML), compared with full-term birth. Study type and study region were the reasons behind the heterogeneity. In subgroup analyses, the summary ORs with 95% CI for childhood leukemia and ALL were 1.23 (1.07, 1.41) and 1.21 (1.06, 1.39) for postterm birth in cohort studies. No significant changes in sensitivity analyses and no publication bias were observed in our analysis.

CONCLUSION

Our results suggest that both preterm and postterm infants have an elevated risk of developing AML. In addition, postterm birth increased the risk of childhood leukemia and ALL in cohort studies. However, more studies are warranted to validate these results and explore the biologic mechanisms underlying these relationships.

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

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

All in the family: Clueing into the link between metabolic syndrome and hematologic malignancies

Metabolic syndrome constitutes a constellation of findings including central obesity, insulin resistance/type 2 diabetes mellitus (DM), dyslipidemia and hypertension. Metabolic syndrome affects 1 in 4 adults in the United States and is rapidly rising in prevalence, largely driven by the dramatic rise in obesity and insulin resistance/DM. Being central to the development of metabolic syndrome and its other related diseases, much focus has been placed on identifying the mitogenic effects of obesity and insulin resistance/DM as mechanistic clues of the link between metabolic syndrome and cancer. Pertinent mechanisms identified include altered lipid signaling, adipokine and inflammatory cytokine effects, and activation of PI3K/Akt/mTOR and RAS/RAF/MAPK/ERK pathways via dysregulated insulin/insulin-like growth factor-1 (IGF-1) signaling. Through variable activation of these multiple pathways, obesity and insulin resistance/DM pre-dispose to hematologic malignancies, imposing the aggressive and chemo-resistant phenotypes typically seen in cancer patients with underlying metabolic syndrome. Growing understanding of these pathways has identified druggable cancer targets, rationalizing the development and testing of agents like PI3K inhibitor idelalisib, mTOR inhibitors everolimus and temsirolimus, and IGF-1 receptor inhibitor linsitinib. It has also led to exploration of obesity and diabetes-directed therapies including statins and oral hypoglycemic for the management of metabolic syndrome-related hematologic neoplasms.

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

BACKGROUND

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

METHODS AND RESULTS

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

RESULTS

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

CONCLUSION

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

Fulminant and fatal course of acute lymphoblastic leukemia due to lactic acidosis and suspected abdominal compartment syndrome

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy and its prognosis has considerably improved over the past 2 decades due to new therapeutic approaches. In some cases, however, it can develop very rapidly and cause possibly fatal complications. We report on the case of an 11-year-old boy with ALL, who rapidly developed severe lactic acidosis and abdominal compartment syndrome. He died of multiorgan failure only 5 days after diagnosis of ALL had been established. Autopsy revealed systemic leukemic infiltrations. We suppose that the mass of tumor cells induced a cascade of metabolic and endocrine reactions, which not only triggered the rapid progression of the disease but were also accountable for the lack of response to treatment. The pathophysiology of abdominal compartment syndrome as a rare and in our case ultimately fatal complication of ALL is described.

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

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

BAALC-associated gene expression profiles define IGFBP7 as a novel molecular marker in acute leukemia

Over expression of BAALC (brain and acute leukemia, cytoplasmic) predicts an inferior outcome in acute myeloid leukemia (AML) and acute lymphoblastic leukemia patients. To identify BAALC-associated genes that give insights into its functional role in chemotherapy resistance, gene expression signatures differentiating high from low BAALC expressers were generated from normal CD34(+) progenitors, T-acute lymphoblastic leukemia (T-ALL) and AML samples. The insulin-like growth factor binding protein 7 (IGFBP7) was one of the four genes (CD34, CD133, natriuretic peptide receptor C (NPR3), IGFBP7) coexpressed with BAALC and common to the three entities. In T-ALL, high IGFBP7-expression was associated with an immature phenotype of early T-ALL (P<0.001), expression of CD34 (P<0.001) and CD33 (P<0.001). Moreover, high IGFBP7-expression predicted primary therapy resistance (P=0.03) and inferior survival in T-ALL (P=0.03). In vitro studies revealed that IGFBP7 protein significantly inhibited the proliferation of leukemia cell lines (Jurkat cells: 42% reduction, P=0.002; KG1a cells: 65% reduction, P<0.001). In conclusion, IGFBP7 was identified as a BAALC coexpressed gene. Furthermore, high IGFBP7 was associated with stem cell features and treatment failure in T-ALL. In contrast to BAALC, which likely represents only a surrogate marker of treatment failure in acute leukemia, IGFBP7 regulates the proliferation of leukemic cells and might be involved in chemotherapy resistance.

Expression of components of the IGF axis in childhood acute myelogenous leukemia

BACKGROUND

Insulin-like growth factor (IGF) system as regulator for cellular proliferation is of particular interest in search for new prognostic approaches in cancer treatment.

PROCEDURE

We analyzed the mRNA expression profile of IGF-I, -II, and IGFBP-2, -3 in 50 children with previously untreated AML (mean age 10.8 +/- 4.8 years; patients in CCR n = 20, patients with relapse during later course of disease n = 15). MNC samples from peripheral blood as well as bone marrow of healthy donors were used as controls.

RESULTS

IGFBP-2 expression was significantly higher in AML cells than in healthy cells of peripheral MNC (P < 0.001) and of bone marrow cells (P < 0.01). Conversely, AML cells showed significantly lower IGFBP-3 and IGF-I gene expression compared to controls (P = 0.02; P < 0.001). Patients with relapse (median +/- range: 0.0929 +/- 0.049) during later course of disease demonstrated higher IGFBP-2 expression compared to patients in CCR (0.0121 +/- 0.047; P = 0.06) at time of diagnosis. A multivariate analysis identified the IGFBP-2 mRNA expression as an independent factor for the prediction of relapse. Furthermore, the probability of relapse-free survival (RFS) in patients with IGFBP-2 mRNA level >0.1000 was 28%; whereas, the probability of RFS in patients with IGFBP-2 mRNA level <0.1000 was 62% (P = 0.04, log-rank test). No prognostic influence could be found for the other investigated genes.

CONCLUSIONS

Results identified different expressions of IGF components between normal and AML cells. Patients with IGFBP-2 mRNA levels up to 0.1000 (relative to KG1 cell line) more likely developed a relapse. Identification of these patients at diagnosis may allow more individualized treatment.

Autocrine insulin-like growth factor-I signaling promotes growth and survival of human acute myeloid leukemia cells via the phosphoinositide 3-kinase/Akt pathway

Insulin-like growth factor (IGF) signaling plays an important role in various human cancers. Therefore, the role of insulin-like growth factor I (IGF-I) signaling in growth and survival of acute myeloid leukemia (AML) cells was investigated. Expression of the IGF-I receptor (IGF-IR) and its ligand IGF-I were detected in a panel of human AML blasts and cell lines. IGF-I and insulin promoted the growth of human AML blasts in vitro and activated the phosphoinositide 3-kinase (PI3K)/Akt and the extracellular signal-regulated kinase (Erk) pathways. IGF-I-stimulated growth of AML blasts was blocked by an inhibitor of the PI3K/Akt pathway. Moreover, downregulation of the class Ia PI3K isoforms p110beta and p110delta by RNA interference impaired IGF-I-stimulated Akt activation, cell growth and survival in AML cells. Proliferation of a panel of AML cell lines and blasts isolated from patients with AML was inhibited by the IGF-IR kinase inhibitor NVP-AEW541 or by an IGF-IR neutralizing antibody. In addition to its antiproliferative effects, NVP-AEW541 sensitized primary AML blasts and cell lines to etoposide-induced apoptosis. Together, our data describe a novel role for autocrine IGF-I signaling in the growth and survival of primary AML cells. IGF-IR inhibitors in combination with chemotherapeutic agents may represent a novel approach to target human AML.

Elevated serum insulin-like growth factor binding protein-2 is associated with a high relapse risk after hematopoietic stem cell transplantation in childhood AML

Insulin-like growth factor binding protein (IGFBP)-2 has mitogenic effects in normal and neoplastic cells. The purpose of this study is to examine the diagnostic and prognostic significance of elevated IGFBP-2 levels in children with AML after hematopoietic stem cell transplantation (HSCT) at relapse and continuous complete remission (CCR). In 27 children with AML (mean age 13.6+/-5.3 years; patients in remission n=15 with relapse n=12) serum parameters of IGFBP-2, IGFBP-3, IGF-I and IGF-II were analyzed up to 18 months after HSCT by RIA. AML-patients with evidence of relapse demonstrated a continuous increase of IGFBP-2 levels during the follow-up. At day 100 after HSCT, IGFBP-2 concentrations were significantly higher in patients with relapse than in children without relapse (7.4+/-4.0 standard deviation score (SDS) vs 3.9+/-1.7 SDS; P=0.01). Serum IGFBP-2 was identified as an independent factor for the prediction of relapse. Furthermore, the probability of relapse-free survival (RFS) in patients with IGFBP-2 >4.5 SDS at day 100 after HSCT was 31% compared to patients with IGFBP-2 <4.5 SDS was 72% (P=0.004). Patients with IGFBP-2 concentration up to 4.5 SDS more likely developed a relapse and had a poorer outcome. Identification of these patients allows a more individualized and aggressive adjuvant treatment and follow-up.