Serum levels of insulin-like growth factor-I, -II and insulin-like growth factor binding proteins -2 and -3 in children with acute lymphoblastic leukaemia

Maternal obesity and acute lymphoblastic leukemia risk in offspring: A summary of trends, epidemiological evidence, and possible biological mechanisms

Acute lymphoblastic leukemia, a heterogenous malignancy characterized by uncontrolled proliferation of lymphoid progenitors and generally initiated in utero, is the most common pediatric cancer. Although incidence of ALL has been steadily increasing in recent decades, no clear reason for this trend has been identified. Rising concurrently with ALL incidence, increasing maternal obesity rates may be partially contributing to increasing ALL prevelance. Epidemiological studies, including a recent meta-analysis, have found an association between maternal obesity and leukemogenesis in offspring, although mechanisms underlying this association remain unknown. Therefore, the purpose of this review is to propose possible mechanisms connecting maternal obesity to ALL risk in offspring, including changes to fetal/neonatal epigenetics, altered insulin-like growth factor profiles and insulin resistance, modified adipokine production and secretion, changes to immune cell populations, and impacts on birthweight and childhood obesity/adiposity. We describe how each proposed mechanism is biologically plausible due to their connection with maternal obesity, presence in neonatal and/or fetal tissue, observation in pediatric ALL patients at diagnosis, and association with leukemogenesis, A description of ALL and maternal obesity trends, a summary of epidemiological evidence, a discussion of the pathway from intrauterine environment to subsequent malignancy, and propositions for future directions are also presented.

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-I predicts sinusoidal obstruction syndrome following pediatric hematopoietic stem cell transplantation

Sinusoidal obstruction syndrome (SOS) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT) initiated through damage of sinusoidal endothelium and inflammation. Insulin-like growth factor-l (IGF-l) maintains and repairs endothelium and intestinal mucosa. We hypothesized that low IGF-l levels may increase the risk of inflammatory complications, such as SOS, in HSCT-patients. We prospectively measured IGF-l concentrations in 121 pediatric patients before, during, and after allogeneic HSCT. Overall, IGF-l levels were significantly reduced compared with healthy sex- and age-matched children. IGF-I levels pre-HSCT and at day 0 were inversely associated with C-reactive protein levels, hyperbilirubinemia, and number of platelet transfusions within the first 21 days post-transplant. Low levels of IGF-I before conditioning and at day of transplant were associated with increased risk of SOS diagnosed by the modified Seattle criteria (pre-HSCT: OR = 1.7 (95% CI: 1.2-2.6, p = 0.01), and the pediatric EBMT criteria (pre-HSCT: 1.7 (1.2-2.5, p = 0.009) and day 0: 1.7 (1.3-2.5, p = 0.001)/SDS decrease in IGF-1). These data suggest that IGF-I is protective against cytotoxic damage and SOS, most likely through trophic effects on endothelial cells and anti-inflammatory properties, and may prove useful as a predictive biomarker of SOS.

Insulin-Like Growth Factor Gene Polymorphisms Predict Clinical Course in Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is challenged by significant toxicities that are propagated by systemic inflammation caused by cytotoxic damage. Insulin-like growth factor-1 (IGF-1) is key in repair of most tissues and is to a large extent genetically determined. We investigated eight single nucleotide polymorphisms (SNPs) in the genes encoding IGF-1 and its binding protein (IGFBP3) in 543 patients undergoing HSCT to access their impact on systemic inflammation and clinical outcomes. Overall, median serum levels of both IGF-1 and IGFBP3 were found reduced from the referral until 2 years post-HSCT compared with healthy sex- and age-matched individuals, but, for individuals homozygous of the known high-producer minor allele of rs1520220 (IGF1), rs978458 (IGF1), or rs2854744 (IGFBP3) serum levels remained normal during the whole period. In accordance, maximum C-reactive protein levels were lower for these genotypes of IGF1 (rs1520220: median 66 vs. 102 mg/L, P = 0.005 and rs978458: 53 vs. 104 mg/L, P < 0.001), translating into borderline significant superior survival (P = 0.060 for rs1520220) and reduced treatment-related mortality (P = 0.050 for rs978458). In conclusion, we found that three SNPs in the IGF-1 axis with known functional impact were associated with circulating IGF-1 or IGFBP-3 levels also in the setting of HSCT, and predictive of the severity of the toxic-inflammatory response during the treatment.

miR-196b/miR-1290 participate in the antitumor effect of resveratrol via regulation of IGFBP3 expression in acute lymphoblastic leukemia

MicroRNAs play critical roles in the progression of acute lymphoblastic leukemia (ALL). Previous studies have indicated that miR-196b and miR-1290 play critical roles in T-cell ALL (T-ALL) and B-cell ALL (B-ALL), respectively. Resveratrol, a natural edible polyphenolic phytoalexin, possesses certain anticancer activities. Nevertheless, the mechanism involved in the regulation of ALL by resveratrol is still poorly understood. The present study aimed to reveal the potential mechanism underlying the antitumor effect of resveratrol in ALL focusing on miRNAs. Research indicates that insulin-like growth factor binding protein 3 (IGFBP3) plays a critical role in the aetiology of ALL. In the present study, we first demonstrated that the expression of IGFBP3 was decreased in ALL patients. We further identified that miR-196b and miR-1290 were overexpressed in T-ALL TALL-104 and B-ALL SUP-B15 cell lines, respectively. Moreover, resveratrol markedly decreased the overexpression of miR-196b/miR-1290 and elevated IGFBP3 expression in the ALL cell lines. As an miR-196b/miR-1290 inhibitor, resveratrol was further demonstrated to exert antitumor effects on ALL cells including antiproliferation, cell cycle arrest, apoptosis and inhibition of migration. Dual-luciferase reporter assay revealed that miR-196b/miR-1290 directly bound to the 3'-untranslated (3'-UTR) region of IGFBP3 mRNA. Moreover, we observed that IGFBP3 short interfering RNA reversed the antitumor activity of resveratrol against ALL cells. Taken together, the present study provides evidence that resveratrol targets miR-196b and miR-1290 for its antitumor activity in T-ALL and B-ALL, respectively. The present study also confirms that both miR‑196b and miR-1290 target the IGFBP3 3'-UTR and are potential therapeutic targets for ALL.

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.

Molecular forms of the insulin-like growth factor-binding protein-2 in patients with colorectal cancer

The components of the insulin-like growth factor (IGF) system and molecules with which they interact are associated with the neoplastic transformation of cells in colorectal cancer. The IGF-binding protein-2 (IGFBP-2) plays a significant role in mitotic stimulation of the cancer cells and its concentration is significantly elevated in tumor states. Little is known about IGFBP-2 at the molecular level and the purpose of this study was to examine the interactions between IGFBP-2 and some other proteins, the fragmentation pattern and posttranslational modifications that might have occurred due to a disease. Results have shown that the amount of monomer IGFBP-2 was 20-30% greater in patients with cancer and the amount of fragmented IGFBP-2 was doubled compared to healthy people, whereas the portion of IGFBP-2 in complex with α2 macroglobulin (α2M) was 2.5 times lower in cancer patients. According to this distribution, IGFBP-2 was not only increasingly synthetized in patients with cancer, but also the amount involved in complexes with α2M was reduced favoring the existence of binary IGFBP-2/IGF complexes, free to leave the circulation. Both IGFBP-2 and α2M were significantly more oxidized in patients with colon cancer than in healthy individuals and α2M was additionally sialylated. It can be speculated that the formation of IGFBP-2/α2M complexes is part of the control mechanism involved in the regulation of IGFBP-2 and, consequently, IGF availability. It also seems that posttranslational modifications are more important factors in determining the amount of IGFBP-2/α2M complexes than the actual quantity of these two proteins.

Evaluation of four methods used to measure plasma insulin-like growth factor 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases

OBJECTIVE

To evaluate 4 methods used to measure plasma insulin-like growth factor (IGF) 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases.

ANIMALS

39 healthy cats, 7 cats with diabetes mellitus, and 33 cats with other diseases.

PROCEDURES

4 assays preceded by different sample preparation methods were evaluated, including acid chromatography followed by radioimmunoassay (AC-RIA), acid-ethanol extraction followed by immunoradiometry assay (AEE-IRMA), acidification followed by immunochemiluminescence assay (A-ICMA), and IGF-2 excess followed by RIA (IE-RIA). Validation of the methods included determination of precision, accuracy, and recovery. The concentration of IGF-1 was measured with all methods, and results were compared among cat groups.

RESULTS

The intra-assay coefficient of variation was < 10% for AC-RIA, A-ICMA, and AEE-IRMA and 14% to 22% for IE-RIA. The linearity of dilution was close to 1 for each method. Recovery rates ranged from 69% to 119%. Five healthy cats had IGF-1 concentrations > 1,000 ng/mL with the AEE-IRMA, but < 1,000 ng/mL with the other methods. Compared with healthy cats, hyperthyroid cats had significantly higher concentrations of IGF-1 with the A-ICMA method, but lower concentrations with the IE-RIA method. Cats with lymphoma had lower IGF-1 concentrations than did healthy cats regardless of the method used.

CONCLUSIONS AND CLINICAL RELEVANCE

Differences in the methodologies of assays for IGF-1 may explain, at least in part, the conflicting results previously reported in diabetic cats. Disorders such as hyperthyroidism and lymphoma affected IGF-1 concentrations, making interpretation of results more difficult if these conditions are present in cats with diabetes mellitus.

Effects of insulin-like growth factor-1 on B-cell precursor acute lymphoblastic leukemia

Insulin-like growth factor-1 (IGF-1) is known to be a major growth factor with effects on various cell types, including hematopoietic cells, as well as neoplasms, and is regulated by IGF-binding proteins (IGFBPs). In this study, we investigated the effects of IGF-1 on B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells. When the expression of IGF-1R in clinical samples of BCP-ALL was examined, five of thirty-two cases showed IGF-1R expression, whereas IGF-1R was expressed in most BCP-ALL cell lines. We observed that IGF-1 enhanced the proliferation of BCP-ALL cell lines that can be partially inhibited by IGFBP-1, -3, and -4, but not other IGFBPs. IGF-1 also partially inhibited dexamethasone-induced apoptosis, but not apoptosis mediated by VP-16 and irradiation. Interestingly, the proliferative effect of IGF-1 was partially blocked by inhibitors of MAPK and AKT, whereas the inhibition of dexamethasone-induced apoptosis was completely blocked by both inhibitors. Our data indicate that IGF-1 is involved in cell proliferation and apoptosis regulation in BCP-ALL cells. Since some BCP-ALL cases express IGF-1R, it appears to be a plausible target for prognostic evaluation and may represent a new therapeutic strategy.

Do insulin-like growth factor associated proteins qualify as a tumor marker? Results of a prospective study in 163 cancer patients

OBJECTIVE

Insulin-like growth factor (IGF)-1, -2 and Insulin like growth factor binding proteins (IGFBP) are involved in the proliferation and differentiation of cells. It has never been evaluated, if the IGF-system can serve as a tumor marker in neoplasms.

METHODS

In our prospective study 163 patients with colorectal cancer (22), prostate cancer (21), head and neck tumors (17), lymphomas (20), lung cancer (34) and other entities (49) were analysed for their IGF and IGFBP serum levels at the beginning and the end of radiotherapy and compared to 13 healthy people. Subgroups of patients with local tumor disease versus metastatic disease, primary and recurrent therapy and curative versus palliative therapy were compared.

RESULTS

The serum levels of IGF-2 were significantly elevated in patients with prostate and colorectal cancer. However, sensitivity and specificity were only 70%. IGFBP-2 serum levels were elevated in patients with head and neck tumors. Again sensitivity and specificity were only 73%. A difference between local disease and metastatic disease could not be found. A difference between IGF serum levels before and after radiotherapy could not be detected.

CONCLUSION

The IGF-system cannot serve as a new tumor marker. The detected differences are very small, sensitivity and specificity are too low. IGF measurement is not useful for the evaluation of the success of radiotherapy in malignancies.

Insulin-like growth factor binding protein-2: NMR analysis and structural characterization of the N-terminal domain

The insulin-like growth factor binding proteins are a family of six proteins (IGFBP-1 to -6) that bind insulin-like growth factors-I and -II (IGF-I/II) with high affinity. In addition to regulating IGF actions, IGFBPs have IGF-independent functions. IGFBP-2, the largest member of this family, is over-expressed in many cancers and has been proposed as a possible target for the development of novel anti-cancer therapeutics. The IGFBPs have a common architecture consisting of conserved N- and C-terminal domains joined by a variable linker domain. The solution structure and dynamics of the C-terminal domain of human IGFBP-2 have been reported (Kuang Z. et al. J. Mol. Biol. 364, 690-704, 2006) but neither the N-domain (N-BP-2) nor the linker domain have been characterised. Here we present NMR resonance assignments for human N-BP-2, achieved by recording spectra at low protein concentration using non-uniform sampling and maximum entropy reconstruction. Analysis of secondary chemical shifts shows that N-BP-2 possesses a secondary structure similar to that of other IGFBPs. Although aggregation hampered determination of the solution structure for N-BP-2, a homology model was generated based on the high degree of sequence and structure homology exhibited by the IGFBPs. This model was consistent with experimental NMR and SAXS data and displayed some unique features such as a Pro/Ala-rich non-polar insert, which formed a flexible solvent-exposed loop on the surface of the protein opposite to the IGF-binding interface. NMR data indicated that this loop could adopt either of two alternate conformations in solution - an entirely flexible conformation and one containing nascent helical structure. This loop and an adjacent poly-proline sequence may comprise a potential SH3 domain interaction site for binding to other proteins.

Involvement of the IGF system in fetal growth and childhood cancer: an overview of potential mechanisms

Fetal growth is determined by a complex interplay of genetic, nutritional, environmental, and hormonal factors. Greater than expected fetal growth has been positively associated with the risk of the development of some cancers in childhood, particularly acute lymphoblastic leukemia, and the biological mechanisms underlying such associations are thought to involve insulin-like growth factors (IGFs). Circulating IGF levels are highly correlated with fetal growth, and IGFs are believed to play an important role in carcinogenesis; however, these two bodies of evidence have not been well integrated and, as a result, the potential underlying biological mechanisms linking the IGF system with the development of specific childhood cancers have not been elucidated. This review aims to draw together and summarize the literature linking the IGF system, rapidity of fetal growth, and risk of some specific childhood cancers; suggest explanations for some of the inconsistencies observed in previous studies of these associations; and propose an integrated framework for the putative involvement of the IGF system in the development of at least some childhood cancers. If the challenges involved in studying the complex IGF system can be overcome, this field presents an exciting opportunity to elucidate etiological pathways to childhood malignancies.

AMPK-induced activation of Akt by AICAR is mediated by IGF-1R dependent and independent mechanisms in acute lymphoblastic leukemia

Background

Children with Acute Lymphoblastic Leukemia (ALL) diagnosed with resistant phenotypes and those who relapse have a dismal prognosis for cure. In search for novel treatment strategies, we identified the AMP activated protein kinase (AMPK) as a potential drug target based on its effects on cell growth and survival. We have shown previously that AICAR-induced AMPK activation also induced a compensatory survival mechanism via PI3K/Akt signaling.

Results

In the present study, we further investigated the downstream signaling induced by AMPK activation in ALL cells. We found that AICAR-induced AMPK activation resulted in up-regulation of P-Akt (Ser473 and Thr308) and decrease of P-mTOR (Ser2448) expression and downstream signaling. We determined that activation of P-Akt (Thr308) was mediated by AMPK-induced IGF-1R activation via phosphorylation of the insulin receptor substrate-1 (IRS-1) at Ser794. Inhibition of IGF-1R signaling using the tyrosine kinase inhibitor HNMPA(AM)₃ resulted in significant decrease in P-IRS-1 (Ser794) and P-Akt (Thr308). Co-treatment of AICAR plus HNMPA(AM)₃ prevented AMPK-induced up-regulation of P-Akt (Thr308) but did not alter the activation of P-Akt (Ser473). Inhibition of AMPK using compound-C resulted in decreased P-Akt expression at both residues, suggesting a central role for AMPK in Akt activation. In addition, inhibition of IGF-1R signaling in ALL cells resulted in cell growth arrest and apoptosis. Additional Western blots revealed that P-IGF-1R (Tyr1131) and P-IRS-1 (Ser794) levels were higher in NALM6 (Bp-ALL) than CEM (T-ALL), and found differences in IGF-1R signaling within Bp-ALL cell line models NALM6, REH (TEL-AML1, [t(12;21)]), and SupB15 (BCR-ABL, [t(9;22)]). In these models, higher sensitivity to IGF-1R inhibitors correlated with increased levels of IGF-1R expression. Combined therapy simultaneously targeting IGF-1R, AMPK, Akt, and mTOR pathways resulted in synergistic growth inhibition and cell death.

Conclusions

Our study demonstrates that AMPK activates Akt through IGF-1R dependent and independent mechanisms. Co-targeting IGF-1R and related downstream metabolic and oncogenic signaling pathways represent a potential strategy for future translation into novel ALL therapies.

Assessment of bone mineral density and risk factors in children completing treatment for acute lymphoblastic leukemia

BACKGROUND

Reduced bone mineral density and increased fracture risk have been reported in children with cancer. In this study, we aimed to determine the growth and bone mineral density (BMD) of the children off chemotherapy for acute lymphoblastic leukemia, and the probable risk factors.

PROCEDURE

The age, anthropometric measurements, lumbar spine BMDs were recorded in 70 children. The risk factors on BMD; daily calcium intake, the time interval from the completion of the chemotherapy, cranial radiotherapy, cumulative steroid dose, decrease in physical activity were investigated. Serum calcium, phosphate, alkaline phosphates, magnesium, insulin-like growth factor-1 (IGF-1) and 25 (OH) vitamin D levels were determined.

RESULTS

The mean height percentile at the time of diagnosis was decreased from the value of 53 to a value of 47 at the beginning of the study (P=0.071). Of them; 44% had osteoporosis, 41% had osteopenia, and the rest had normal BMD. BMD z-scores were decreased during the first 2 years from the completion of the treatment. There was a positive correlation between BMD z-scores and daily calcium intake (CC=0.366, P=0.0015). A negative correlation was determined between the time spent on TV and computers and BMD z-scores (CC=-0.464, P=0.0019). Serum IGF-1 and 25 (OH) vitamin D levels of patients were significantly lower than controls (P=0.033).

CONCLUSIONS

Our data revealed that 85% of the survivors had bone mineralization defect. BMDs and z scores were decreased during the first 2 years from the completion of the treatment and then gradually began to increase. The most important risk factor for decreased BMD was low daily calcium intake. Therefore, patients and their families should be encouraged to take sufficient amount of calcium. Prophylactic vitamin D may also be supplemented.

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

Insulin-like growth factor (IGF) signaling plays a pivotal role in cell proliferation and mitogenesis. Secreted IGF-binding proteins (IGFBPs) are important modulators of IGF bioavailability; however, their intracellular functions remain elusive. We sought to assess the antiapoptotic properties of intracellular IGFBP-2 in lung adenocarcinomas. IGFBP-2 overexpression resulted in a decrease in procaspase-3 expression; however, it did not influence the phosphorylation status of either IGF receptor or its downstream targets, including Akt and extracellular signal-regulated kinase. Apoptosis induced by camptothecin was significantly inhibited by IGFBP-2 overexpression in NCI-H522 cells. Conversely, selective knockdown of IGFBP-2 using small-interfering RNA resulted in an increase in procaspase-3 expression and sensitization to camptothecin-induced apoptosis in NCI-H522 cells. LY294002, an inhibitor of phosphatidyl-inositol 3-kinase, caused a decrease in IGFBP-2 levels and enhanced apoptosis in combination with camptothecin. Immunohistochemistry demonstrated that intracellular IGFBP-2 was highly expressed in lung adenocarcinomas compared with normal epithelium. Intracellular IGFBP-2 and procaspase-3 were expressed in a mutually exclusive manner. These findings suggest that intracellular IGFBP-2 regulates caspase-3 expression and contributes to the inhibitory effect on apoptosis independent of IGF. IGFBP-2, therefore, may offer a novel therapeutic target and serve as an antiapoptotic biomarker for lung adenocarcinoma.

Lactic acidosis and hypoglycemia with ALL relapse following engrafted bone marrow transplant

Lactic acidosis together with hypoglycemia in the face of hematologic malignancy is a grave development. A 7-year-old male with pre-B-cell ALL following hematopoietic cell transplant was admitted to our hospital in his second relapse. On hospital days 4 and 5, he developed refractory hypoglycemia, lactic acidosis, central respiratory failure, and acute renal failure. Bicarbonate infusion, B vitamins, and hemodialysis were not effective. Care was withdrawn on hospital day 9. Further understanding of the mechanisms that cause the combined onset of lactic acidosis and hypoglycemia will help clinicians in implementing timely therapies that may reduce mortality.

Plasma IGFBP-2 levels predict clinical outcomes of patients with high-grade gliomas

Insulin-like growth factor binding protein 2 (IGFBP-2) is a malignancy-associated protein measurable in tumors and blood. Increased IGFBP-2 is associated with shortened survival of advanced glioma patients. Thus, we examined plasma IGFBP-2 levels in glioma patients and healthy controls to evaluate its value as a plasma biomarker for glioma. Plasma IGFBP-2 levels in 196 patients with newly diagnosed glioma and 55 healthy controls were analyzed using an IGFBP-2 ELISA kit. Blood was collected before surgery, after two-cycle adjuvant chemotherapy, and at recurrence. Plasma IGFBP-2 levels were correlated with disease-free survival (DFS) using Cox regression analyses. We found that preoperative plasma IGFBP-2 levels were significantly higher in high-grade glioma patients (n = 43 for grade III glioma; n = 72 for glioblastoma multiforme [GBM]) than in healthy controls (n = 55; p < 0.001) and low-grade (grade II) glioma patients (n = 81; p < 0.001). No significant differences in preoperative plasma IGFBP-2 levels were observed between grade III glioma and GBM patients or between grade II glioma patients and healthy controls. After recurrence, plasma IGFBP-2 levels were significantly increased in GBM patients (n = 26; p < 0.001). Preoperative plasma IGFBP-2 levels were significantly correlated with DFS in GBM patients (hazard ratio, 1.404; 95% confidence interval, 1.078-1.828; p = 0.012). We conclude that preoperative plasma IGFBP-2 levels are significantly higher in high-grade glioma patients than in low-grade glioma patients and healthy subjects, and are significantly correlated with recurrence and DFS in patients with GBM. Longitudinal studies with a larger study population are needed to confirm these findings.

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.

Insulin-like growth factor binding protein 2 promotes glioma development and progression

Overexpression of insulin-like growth factor binding protein 2 (IGFBP2) is associated with progression in many types of human cancer. In this study we used a glial-specific transgenic mouse model to examine the active role of IGFBP2 in tumorigenesis and progression. Our studies show that IGFBP2 coexpression results in progression to a higher-grade glioma in platelet-derived growth factor beta (PDGFB)-driven tumors. These anaplastic oligodendrogliomas are characterized by increased cellularity, vascular proliferation, small regions of necrosis, increased mitotic activity, and increased activation of the Akt pathway. Combined expression of IGFBP2 or Akt with K-Ras was required to form astrocytomas, indicating that activation of two separate pathways is necessary for gliomagenesis. In ex vivo experiments, blockade of Akt by an inhibitor led to decreased viability of cells coexpressing IGFBP2 versus PDGFB expression alone. Thus, this study provides definitive evidence that IGFBP2 plays a key role in activation of the Akt pathway and collaborates with K-Ras or PDGFB in the development and progression of two major types of glioma.

Expression of insulin-like growth factor binding protein-2 by MCF-7 breast cancer cells is regulated through the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin pathway

IGF binding protein-2 (IGFBP-2) has been implicated in the development and spread of a number of tumor types, and its abrogation in experimental models of cancer is associated with decreased tumor growth. This suggests that targeted inhibition of IGFBP-2 expression in some cancers may have therapeutic benefit. In this study, we investigated signaling pathways involved in extracellular IGFBP-2 expression in an IGF- and estrogen-responsive breast cancer cell line, MCF-7. IGFBP-2 was present at approximately 150 ng per 10(6) cells in serum-free MCF-7-conditioned medium and constituted the predominant IGFBP. Inhibition of the phosphatidylinositol 3-kinase signaling pathway using LY294002, or the downstream signaling intermediate mammalian target of rapamycin using rapamycin, markedly reduced IGFBP-2 in conditioned medium to approximately 25% of untreated levels (P < 0.001); there was no effect of inhibition of p38 MAPK, and an inhibitor of p44/42 MAPK activation, PD98059, caused only a slight reduction in extracellular IGFBP-2. IGFBP-2 levels were increased 25-30% by estradiol, whereas IGF-I (100 ng/ml) increased IGFBP-2 levels 2-fold (P < 0.001) by a type 1 IGF receptor (IGFR1)-dependent mechanism. Estradiol enhanced the effect of IGF-I on IGFBP-2 levels, and this was associated with increased phosphorylation of IGFR1. Basal, IGF-, or estradiol-stimulated IGFBP-2 was abrogated by LY294002 and rapamycin and an inhibitor of IGFR1 tyrosine kinase activity, AG1024. Modulation of intracellular hypoxia-inducible factor-1alpha had no effect on IGFBP-2 expression. These findings indicate that IGFBP-2 is regulated predominantly through the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway, the target of a number of anticancer agents currently in clinical trial and use.

Evaluation of Plasma Insulin-like Growth Factor Binding Protein 2 and Her-2 Extracellular Domain as Biomarkers for 17-Allylamino-17-Demethoxygeldanamycin Treatment of Adult Patients with Advanced Solid Tumors

PURPOSE

Interaction of 17-allylamino-17-demethoxygeldanamycin (17-AAG) with heat shock protein 90 results in proteasomal degradation of many proteins, including Her-2-neu, with subsequent decreased expression of insulin-like growth factor binding protein-2 (IGFBP-2). Concentrations of both IGFBP-2 and Her-2 extracellular domain (Her-2 ECD) in sera of mice bearing BT474 human breast cancer xenografts decrease after 17-AAG treatment. We investigated whether this phenomenon occurred in patients.

MATERIALS AND METHODS

Eight to 15 plasma samples were obtained between 0 and 72 h from 27 patients treated with single-agent 17-AAG at doses between 10 and 307 mg/m(2) and 18 patients treated with 17-AAG at doses between 220 and 450 mg/m(2) combined with 70 to 75 mg/m(2) of docetaxel. Pretreatment plasma samples were also obtained from 12 healthy volunteers. Plasma IGFBP-2 and Her-2 ECD concentrations were quantitated by ELISA.

RESULTS

Pretreatment plasma IGFBP-2 concentrations in patients (171 +/- 116 ng/mL) were 2-fold higher than those in healthy volunteers (85 +/- 44 ng/mL; P < 0.05). Following 17-AAG treatment, there were no consistent dose-dependent or time-dependent changes in plasma IGFBP-2 and Her-2 ECD concentrations. IGFBP-2 concentrations decreased by >or=40% in 8 patients, increased 2- to 5-fold in 8 patients, and remained essentially unchanged in 29 patients. Her-2 ECD concentrations decreased by >or=40% in 10 patients, increased 1.5- to 5-fold in 2 patients, and remained essentially unchanged in 25 patients.

CONCLUSIONS

As previously reported, IGFBP-2 concentrations in plasma of cancer patients are significantly higher than those in healthy volunteers. In contrast to a mouse model, 17-AAG treatment was not consistently associated with decreases in IGFBP-2 or Her-2 ECD concentrations in patient plasma.

Identification of novel genes with prognostic value in childhood leukemia using cDNA microarray and quantitative RT-PCR

The aim of this study was to identify genes distinctively expressed or suppressed in childhood leukemia with different prognoses, using cDNA microarray and quantitative reverse transcription-polymerase chain reaction (RT-PCR). The expression levels of the selected genes by cDNA microarray were quantified in primary leukemic blasts from 44 patients (acute lymphoblastic leukemia, 28; acute myelogenous leukemia (AML), 13; transient myeloproliferative disorder, 3). The expression levels of CDKN2C, CRADD, and IGFBP-2 genes were significantly associated with the event-free survival of the patients in AML. The present results suggest that a combination of cDNA microarray and quantitative RT-PCR may be useful to identify novel genes with prognostic value in childhood AML.

Insulin-like growth factor binding protein-2 binding to extracellular matrix plays a critical role in neuroblastoma cell proliferation, migration, and invasion

IGF binding proteins (IGFBPs) modulate IGF cellular bioavailability and may directly regulate tumor growth and invasion. We have previously shown that IGFBP-2 binds and localizes IGF-I to the pericellular matrix and have provided some evidence suggesting that the heparin binding domain (HBD) or the arginine-glycine-aspartic acid (RGD) integrin binding motif may be involved in these interactions. However, the precise mechanisms involved remain to be elucidated. We therefore mutated the HBD or RGD sequence of IGFBP-2 and investigated consequent effects on extracellular matrix (ECM) binding, IGF-induced proliferation, and migration of neuroblastoma cells. IGFBP-2 and its arginine-glycine-glutamic acid (RGE) mutant similarly bound ECM components, whereas binding of mutant HBD-IGFBP-2 to each of the ECM substrates was markedly reduced by 70-80% (P < 0.05). IGF-I (100 ng/ml) increased incorporation of 3H-thymidine in neuroblastoma SK-N-SHEP cells by approximately 30%, an effect blunted by exogenously added native or either mutant IGFBP-2. Overexpression of IGFBP-2 and its RGE mutant potently promoted SHEP cell proliferation (5-fold), whereas SHEP cell proliferation was negligible when HBD-IGFBP-2 was overexpressed. Addition or overexpression of IGFBP-2 and its RGE mutant potently (P < 0.05) enhanced SHEP cell migration/invasion through the ECM. However, overexpression of the HBD-IGFBP-2 mutant potently inhibited (50-60%) SHEP cell invasion through ECM. Thus, IGFBP-2, which binds to the ECM, enhances proliferation and metastatic behavior of neuroblastoma cells, functions that directly or indirectly use the HBD but not the integrin binding sequence. Our novel findings thus point to a key role for the HBD of IGFBP-2 in the control and regulation of neuroblastoma growth and invasion.

Insulin-like Growth Factor-Binding Protein 4 in Children with Acute Lymphoblastic Leukemia

Insulin-like growth factor-binding protein 4 (IGFBP-4) is a potent inhibitor of IGF-mediated cell proliferation. To investigate the functional relevance of IGFBP-4 in leukemia, we measured plasma IGFBP-4 levels and messenger RNA expression in leukemic cell clones of patients with acute lymphoblastic leukemia (ALL) and in control subjects. The IGFBP-4 levels of ALL patients at diagnosis were significantly lower than the levels of healthy control subjects. We evaluated the patients at diagnosis and after 33 days of chemotherapy and found plasma IGFBP-4 levels at day 33 to be significantly lower than the levels at diagnosis. There was no correlation of plasma IGFBP-4 level with age, sex, immunophenotype, or ALL risk group, and there was no correlation of IGFBP-4 level with plasma IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3 levels. Gene expression analysis of the leukemic blast population at diagnosis revealed that the leukemic clones did not significantly contribute to systemic IGFBP-4 levels. The decrease in plasma IGFBP-4 levels during chemotherapy represents an indirect effect, probably caused by the chemotherapeutic effects on IGFBP-4-expressing cells of the liver and other organs. In addition, IGFBP-4 gene expression was investigated in 13 human immune cell-related cell lines by reverse transcription-polymerase chain reaction analysis. IGFBP-4 was exclusively expressed in cell lines derived either from B-cells or from myelomonocytic cells, whereas IGFBP-4 was not expressed in T-cell lines.

Improvement in bone mineral density and body composition in survivors of childhood acute lymphoblastic leukemia: a 1-year prospective study

OBJECTIVES

Abnormalities in bone mineral density (BMD), body composition, and bone metabolism have been reported in children who were treated for acute lymphoblastic leukemia (ALL) during and after completion of therapy. However, these studies are cross-sectional, and no longitudinal data are available in a large group of patients after completion of therapy. In the present study, 1-year longitudinal changes in BMD, body composition, and bone metabolism were evaluated in children with ALL during the first 3 years after completion of therapy without cranial irradiation.

METHODS

BMD of total body (TB; g/cm(2)), areal and apparent volumetric lumbar spine (L2-L4), lean body mass, and percentage of body fat were measured by dual-energy x-ray absorptiometry in 37 children (median age: 7.9 years; range: 4.7-20.6 years) who were treated for ALL at a median age of 3.3 years (range: 1.1-16.6 years), after a median time of 2.2 years after the completion of treatment, and after a 1-year follow-up period. Two control subjects (n = 74) who were matched for gender, age, and pubertal stage were also longitudinally investigated for body composition for 1 year. Usual serum biochemical markers of calcium metabolism and bone turnover were measured in patients during the study period.

RESULTS

A slight decrease in TB BMD was found after a median time of 2.2 years after the completion of therapy for ALL in childhood. Patients showed a significantly lower median TB BMD when evaluated <1.5 years as compared with those at >or=1.5 years since completion of therapy. At the time of first evaluation, the percentage of body fat mass was significantly higher and patients were physically less active than their matched control subjects. Although, as expected, during the 1 year of follow-up both groups showed an annual increment in their BMD measurements, a significantly higher increase in TB BMD was observed in patients in comparison with control subjects. During this same period, the increase in the percentage of body fat mass was slightly lower in ALL patients as compared with control subjects. At the end of the follow-up year, BMD, body-composition parameters, and physical activity of ALL patients were similar to those observed in matched control subjects. Serum biochemical markers of bone turnover were normal at both evaluations.

CONCLUSIONS

A significant increase in TB BMD and a tendency to a lesser increase in percentage of body fat mass were observed during the study period in ALL patients as compared with chronological age-, gender-, and pubertal stage-matched control subjects. These findings suggest a positive effect of long-term completion therapy and increase in physical activity on BMD, body composition, and bone metabolism in patients who have been treated for ALL.

Acute lymphocytic leukemia in a child with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by neonatal hypoglycemia, abdominal wall defects, macroglossia, organomegaly, ear pits and creases, hemihypertrophy, and increased birthweight. Children with BWS have an increased risk of malignancy. The authors present the case of a 3-year-old boy diagnosed with both BWS and acute lymphocytic leukemia (ALL). This case report will elaborate on the possibilities as to how BWS and ALL may be associated due to abnormal genomic imprinting and IGF dysregulation.

Loss of imprinting of IGF-II gene in children with acute lymphoblastic leukemia

Insulin-like growth factor-II (IGF-II) is known to be involved in the regulation of growth, differentiation and cell death in normal human tissues. In a variety of human tumors, the IGF-II gene is overexpressed and considered to be a stimulator for tumor growth through autocrine and paracrine mechanisms. The IGF-II gene is normally parental imprinted, only the paternal allele being expressed in most tissues. Several reports about biallelic expression (loss of imprinting (LOI)) of the IGF-II gene in different tumors suggest a role of dysregulation of IGF-II imprinting in tumorigenesis. However, biallelic expression of IGF-II gene has also been reported in different tissues of a significant number of normal controls, indicating either a normal phenomenon or an elevated cancer risk in this group of persons. Although LOI of IGF-II presumably promotes tumorigenesis by increasing IGF-II expression, elevated IGF-II levels in those patients have not been reported. We studied IGF-II gene expression in malignant lymphoblasts of 124 children suffering from acute lymphoblastic leukemia, 196 cord blood samples from healthy newborns and mononuclear cells (MNC) from 50 healthy age matched children. The ApaI polymorphism in exon 9 of the IGF-II gene and allele-specific exon-connection RT-PCR was used for determination of the imprinting status. From 44 informative ALL-patients, 24 (54%) showed LOI of the IGF-II gene. Twenty percent of the informative cord blood samples (N=56) and 14% of the informative MNC samples from healthy controls (N=22) showed biallelic expression of IGF-II. In the ALL-patients, no statistical significant correlation between LOI patients and relapse rate, surviving rate and risk groups could be detected. We conclude that LOI of IGF-II occurs in malignant lymphoblasts of children suffering from acute lymphoblastic leukemia in more than 50% of the patients. In MNC from cord blood and peripheral MNC from healthy controls, biallelic expression could be detected in up to 20% of all cases. The importance of LOI in ALL-patients needs to be further evaluated to determine its impact in leukemogenesis.

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

SUMMARY

Insulin-like growth factors (IGFs) and IGF-binding proteins (IGFBPs) may play an important role in tumor proliferation. This study aimed to investigate the IGF system in children with acute leukemia prior to and after hematological stem cell transplantation (HSCT). In 51 patients (AML n=27; ALL n=24; mean age 11.2+/-4.8 years), serum parameters (IGF-I,-II, IGFBP-2,-3) were investigated up to 18 months after HSCT by RIA. Patients with AML showed a significant increase of IGFBP-2 up to 100 days after HSCT (mean +/-s.d. prior to HSCT: 3.2+/-3.6 SDS vs 100 days after HSCT: 5.3 degrees +/-3.4 SDS, P=0.005). Furthermore, IGF-I and IGFBP-3 were significantly decreased (IGF-I: -0.3+/-1.5 vs -0.7 +/-1.2 SDS, P=0.001; IGFBP-3: -0.3+/-1.1 vs -1.0+/-1.1 SDS, P=0.02). Children with AML showed significantly higher IGFBP-2 (P=0.04) and significantly lower IGF-I (P=0.03) and IGFBP-3 (P=0.05) levels than children with ALL at day 100 after HSCT. We conclude that children with acute leukemia show important changes in the IGF system after HSCT. In particular, IGFBP-2 was significantly elevated at day 100 after HSCT. Increased IGFBP-2 and decreased IGF-I and IGFBP-3 may be associated with the increased proliferation rate of transplanted bone marrow.

Expression of components of the IGF signalling system in childhood acute lymphoblastic leukaemia

BACKGROUND

Alterations in the insulin-like growth factor (IGF) system have been reported for different tumours. They are of particular interest in the search for new prognostic and therapeutic approaches in cancer. In childhood acute lymphoblastic leukaemia (ALL) the amount of "tumour mass" at diagnosis can exceed 1 kg. To understand the endocrine, paracrine, and autocrine potential of the malignant transformed progenitor cells, the ability of these cells to express components of the IGF system needs to be investigated.

AIM

To characterise the expression pattern of genes of the IGF system in malignant lymphoblasts of children suffering from ALL.

METHODS

Reverse transcription polymerase chain reaction of Ficoll separated mononuclear cells from 142 children with ALL, 127 cord blood samples, and 55 blood samples of age matched controls were studied.

RESULTS

The expression of IGF-I, IGF-II, IGF binding protein 5 (IGFBP-5), and CTGF (IGFBP-rP2) was seen in a higher proportion of mononuclear cells of patients with ALL than in controls. Patients with ALL who were in continuous remission had a lower percentage of IGFBP-2 and IGFBP-3 expressing mononuclear cells at diagnosis than did those who developed a relapse. Only malignant lymphoblasts of B cell origin showed expression of CTGF (IGFBP-rP2). Malignant lymphoblasts of T cell origin more often expressed IGFBP-2 and IGFBP-5, whereas IGF-II and IGFBP-3 expression was seen more often in lymphoblasts of B cell origin.

CONCLUSIONS

Malignant lymphoblasts of patients with ALL express components of the IGF system and therefore promote their own growth in an autocrine, paracrine, or endocrine manner. Whether these components will be useful as prognostic factors in the stratification of ALL treatment in children needs to be evaluated.

Association of preoperative plasma levels of insulin-like growth factor I and insulin-like growth factor binding proteins-2 and -3 with prostate cancer invasion, progression, and metastasis

PURPOSE

We tested the hypothesis that preoperative plasma levels of insulin-like growth factor (IGF) binding protein (BP)-2 or IGFBP-3 would predict cancer stage and prognosis in patients undergoing radical prostatectomy.

MATERIAL AND METHODS

Plasma levels of IGF-I, IGFBP-2, and IGFBP-3 were measured preoperatively in 120 consecutive patients who underwent radical prostatectomy for clinically localized disease, postoperatively in 51 of these patients, in 44 healthy men, in 19 patients with metastases to regional lymph nodes, and in 10 patients with bone metastases.

RESULTS

Plasma IGFBP-3 levels were lowest in patients with bone metastases (P < or = .043). IGFBP-2 levels were elevated in prostate cancer patients compared with healthy subjects (P < or = .006). However, within the group of prostatectomy patients, preoperative plasma IGFBP-2 levels were lower in patients with advanced disease (P < or = .033), were inversely correlated with prostatic tumor volume (P =.037), and declined after prostate removal (P =.044). Lower preoperative IGFBP-2 and IGFBP-3 levels and biopsy Gleason score were independent predictors of biochemical progression (P =.043, P =.040, and P =.020, respectively). In patients with disease progression, preoperative plasma IGFBP-3 levels were lower in those with aggressive than in those with nonaggressive failure (P =.042).

CONCLUSION

Elevation of plasma IGFBP-2 levels in prostate cancer patients apparently is due to increased release directly from the prostate. For patients with clinically localized prostate cancer, preoperative plasma IGFBP-2 levels are inversely associated with biologically aggressive disease and disease progression. Preoperative plasma IGFBP-3 levels were decreased in patients with prostate cancer metastases and were an independent predictor of biochemical progression after surgery, presumably because of an association with occult metastatic disease present at the time of radical prostatectomy.

Lactic acidosis: a metabolic complication of hematologic malignancies: case report and review of the literature

BACKGROUND

Lactic acidosis (LA) associated with hematologic malignancies is rare, ominous, and generally occurs in adults. Its pathogenesis is poorly understood.

METHODS

The authors present one case of childhood lymphoma and two cases of childhood leukemia associated with LA, and they review the available literature. Plasma concentrations of insulin-like growth factors (IGFs), IGF binding proteins (IGFBPs), and tumor necrosis factor (TNF)-alpha were retrospectively measured to elucidate the pathogenesis of LA.

RESULTS

Lactic acidosis has been reported to date in 28 cases of lymphoma and 25 cases of leukemia, including the authors' cases. Ongoing rapid cellular proliferation was indicated in all leukemia cases. The liver was involved in 43 of the 53 cases, and hypoglycemia was present in 20. The acidosis improved only if the disease responded to chemotherapy. Remission was achieved in only five of the reported cases. In the authors' three cases, LA was associated with altered concentrations of IGFs, IGFBPs, and TNF-alpha, although causality was not established.

CONCLUSIONS

Lactic acidosis in association with hematologic malignancies carries an extremely poor prognosis. Because cancer cells have a high rate of glycolysis and produce a large quantity of lactate, this condition may result from an imbalance between lactate production and hepatic lactate utilization. The authors speculate that the IGF system is involved in the pathophysiology of LA in these patients. Only chemotherapy so far has been effective in correcting the acute acidosis in a few patients; however, it has not necessarily improved ultimate outcome.

IGFs and IGFBPs: surrogate markers for diagnosis and surveillance of tumour growth?

Insulin-like growth factors (IGFs), IGF receptors, and IGF binding proteins (IGFBPs) constitute the IGF system. Comprehensive data indicate that these factors play a pivotal role in tumorigenesis. Epidemiological data indicate that cancer risk is associated with high serum IGF-I values. Because dysregulation of the IGF system is a frequent pattern in malignancy, IGFs/IGFBPs might represent novel tumour markers that could be useful both for diagnosis and surveillance.

Transactivation of the IGFBP-2 promoter in human tumor cell lines

Many cancers produce high amounts of the insulin-like growth factor binding protein (IGFBP)-2, which can influence the tumorigenicity and growth of tumor cells. In order to study the possible cause of elevated expression of IGFBP-2 in tumors, we investigated the transcriptional regulation by IGF of a 633-bp fragment of the human IGFBP-2 promoter in a transiently transfected choriocarcinoma (JAR) and a leukemic T-cell line (Molt-4) that express IGFBP-2 highly, and in a leukemic B-cell line (Raji) that expresses little IGFBP-2. Strong basal promoter activity, i.e. luciferase activity was measurable in all of the tumor cell lines. The introduction of equal amounts of normal IGF-I and IGF-II stimulated the transcription of IGFBP-2 only slightly. Synthetic IGF analogues with increased biological activity, however, caused a specific 2.0-3.3-fo1d transactivation of the promoter, as well as a 25% increase in IGFBP-2 mRNA. Synchronously, IGF analogues caused a decrease in the level of IGFBP-3 mRNA of about 45%, while the production of IGFBP-2 as measured by RIA increased in relation to IGFBP-3 by up to 15 times. Blocking with the IGF antagonist JB1 revealed partial involvement of the IGF-I receptor in the regulation of IGFBP-2 expression by locally produced IGF. We conclude, that the reduced ability of IGF analogues to form complexes with locally produced IGFBP may account for their increased biological activity in the stimulation of expression of IGFBP-2 and of cell growth. Since increased biological activity had also been demonstrated for natural pro-IGF forms often produced by tumors, pro-IGFs may be involved in the mechanism leading to elevated IGFBP-2 expression of tumors in vivo.

Elevated serum insulin-like growth factor (IGF)-II and IGF binding protein-2 in patients with colorectal cancer

This study explored the relationships of serum insulin-like growth factors, IGF-I and IGF-II, and their binding proteins (IGFBP)-2 and IGFBP-3, with key clinicopathological parameters in 92 patients with colorectal cancer (cases). Comparisons were made with 57 individuals who had a normal colonoscopy (controls). Serial changes were examined in 27 cases. As IGF-related peptides are age- and sex-dependent, absolute concentrations were converted to standard deviation scores (SDS). Mean IGF-II SDS were elevated in Dukes A (n = 12, P< 0.001) and Dukes B (n = 25, P< 0.001) cases compared with controls, but not in advanced disease. Compared with controls, mean IGFBP-2 SDS were significantly elevated in patients with Dukes B (P< 0.001), Dukes C (n = 13, P< 0.001) and advanced disease (n = 42, P< 0.0001), with a significant trend from early to advanced disease (one-way ANOVA, P< 0.001). Furthermore, IGFBP-2 SDS were positively related to tumour size (P = 0.01) and fell significantly in patients following curative resection (P = 0.04), suggesting that circulating levels reflect tumour load. We tested the potential tumour marker characteristics of IGFBP-2 SDS against three endpoints: metastasis alone; local pelvic recurrence alone; and metastasis and recurrence combined. The sensitivities for IGFBP-2 alone (>/= + 2SD) were modest at 55%, 46%, and 52%, but in combination with CEA, increased substantially to 90%, 77% and 86%, respectively. We conclude that the serum IGF-II and IGFBP-2 profiles may provide insights into underlying biological mechanisms, and that serum IGFBP-2 may have an adjunct role in cancer surveillance in patients with colorectal cancer.

Bone turnover and growth during and after continuing chemotherapy in children with acute lymphoblastic leukemia

Children treated for acute lymphoblastic leukemia may develop reduced bone mineral density during treatment, but there is little information on the mechanisms involved. In a prospective, longitudinal study on 15 children with ALL, we undertook serial measurements of markers of bone and collagen turnover, insulin-like growth factor (IGF)-I and its binding proteins (IGFBPs)-3 and -2 during the second year of continuing chemotherapy. In eight patients we also measured lower leg length by knemometry. Height SD scores, lower leg length velocity, IGF-I, and markers of bone collagen turnover did not differ significantly from healthy children. However, bone alkaline phosphatase, a marker of the differentiated osteoblast, was lower (mean SD score, -0.64; p < 0.0001), whereas procollagen type III N-terminal propeptide (P3NP, a marker of soft tissue collagen turnover; mean SD score, +0.93, p < 0.05), IGFBP-3 (mean SD score, +0.76; p < 0.01), and IGFBP-2 (mean SD score, +1.24, p = 0.01) were all higher than in healthy children. IGFBP-3 decreased during episodes of afebrile neutropenia (p < 0.05). Within 3 mo after completion of treatment, bone ALP increased in all eight patients, but collagen markers showed little change. IGFBP-2 returned to normal posttreatment, but P3NP and IGFBP-3 remained significantly elevated compared with healthy children (mean SD scores, +1.51 and +1.36, respectively; p < 0.01). We conclude that continuing chemotherapy was associated with normal growth and bone collagen turnover but enhanced soft tissue collagen turnover. Bone bone alkaline phosphatase was low throughout treatment, which suggests impaired osteoblast differentiation resulting from a direct effect of chemotherapy on bone. Although the effect was reversible, the long-term implications for bone health in survivors remain uncertain.

CTGF (IGFBP-rP2) is specifically expressed in malignant lymphoblasts of patients with acute lymphoblastic leukaemia (ALL)

Connective tissue growth factor (CTGF) is a major chemotactic and mitogenic factor for connective tissue cells. The amino acid sequence shares an overall 28-38% identity to IGFBPs and contains critical conserved sequences in the amino terminus. It has been demonstrated that human CTGF specifically binds IGFs with low affinity and is considered to be a member of the IGFBP superfamily (IGFBP-rP2). In the present study, the expression of CTGF (IGFBP-rP2) in human leukaemic lymphoblasts from children with acute lymphoblastic leukaemia (ALL) was investigated. RNA samples from tumour clones enriched by ficoll separation of bone marrow or peripheral blood mononuclear cells (MNC) from 107 patients with childhood ALL at diagnosis and 57 adult patients with chronic myeloid leukaemia (CML) were studied by RT-PCR. In addition MNC samples from children with IDDM and cord blood samples from healthy newborns were investigated as control groups. Sixty-one percent of the patients with ALL (65 of 107) were positive for CTGF (IGFBP-rP2) expression. In the control groups, no expression of CTGF (IGFBP-rP2) in peripheral MNC was detected, and in the group of adult CML patients only 3.5% (2 of 57) were positive for this gene. The role of CTGF (IGFBP-rP2) in lymphoblastic leukaemogenesis requires further evaluation, as does its potential utility as a tumour marker.

Insulin-like growth factor-I and insulin-like growth factor binding protein-3 during maintenance chemotherapy of acute lymphoblastic leukemia in children

PURPOSE

To assess the effect of maintenance chemotherapy (MT) on growth factors and growth in children with acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

Twenty-one children (10 girls, 11 boys) with standard risk pre-B ALL treated with chemotherapy had serum insulin-like growth factor-I (IGF-I), serum IGF binding protein-3 (IGFBP-3) levels, and linear growth and weight data measured every 3 months during MT. The levels of the cytotoxic metabolites of methotrexate (MTX) and 6-mercaptopurine (6MP) (i.e., erythrocyte MTX polyglutamates [E-MTX], and erythrocyte 6-thioguanine nucleotides [E-6TGN]), s-aminotransferases, and white blood counts (WBC) were measured at least monthly.

RESULTS

At the beginning of MT, the median IGF-I standard deviation scores (SDS) and IGFBP-3 SDS were -0.52 and -0.09, respectively, which declined during MT to -1.67 (P < 0.001) and -1.82 (P < 0.001), respectively. At the time of diagnosis, the median height SDS was -0.4, which declined during MT to a median height SDS of -0.9 at cessation of therapy. No significant correlations were found between growth factor levels, growth and body mass index (BMI) versus the doses of MTX, and 6MP, E-MTX, E-6TGN, s-aminotransferases, or WBC.

CONCLUSIONS

A significant decline in IGF-I, IGFBP-3, and growth retardation may not be directly related to the treatment intensity during MT.

Acute and short-term effects of growth hormone on insulin-like growth factors and their binding proteins: serum levels and hepatic messenger ribonucleic acid responses in humans

We investigated the acute (4-5 h) and short-term (5 days) effects of GH treatment on hepatic messenger RNA (mRNA) levels of the genes for the insulin-like growth factors (IGFs), insulin-like growth factor binding protein-1, -2, and -3 (IGFBPs), and the acid labile subunit (ALS), as well as serum levels of these proteins in humans. At the mRNA level, we observed an increase in IGF-1 transcription (+173%) following GH treatment in the acute group, which remained elevated in the short-term treatment group. IGFBP-2 mRNA decreased after short-term GH treatment, without changes in IGFBP-1 or -3 expression. The ALS transcript level increased after 5 days. In serum, we found increased levels of IGF-I and insulin, and decreased levels of IGF-II, in the short-term treatment group. IGFBP-1 decreased in both treatment groups, whereas IGFBP-2 was reduced after 5 days treatment. ALS increased in the short-term group. We observed increased IGFBP-3 serum levels after 5 days of GH treatment, likely due to increased formation of the ternary complex. Our results show that the metabolic effects by GH on the IGF axis are complex. In addition to a direct stimulation of IGF-I and ALS expression, GH inhibits IGFBP-1 serum levels and IGFBP-2 expression in an indirect manner, possibly facilitating enhanced IGF bioavailability to target tissues.

Elevated serum levels of IGFBP-2 found in children suffering from acute leukaemia is accompanied by the occurrence of IGFBP-2 mRNA in the tumour clone

Insulin-like growth factor-binding proteins (IGFBPs) are important modulators of IGF action. In 50 children suffering from acute lymphoblastic leukaemia (ALL), we studied the serum levels of IGFBP-1,-2 and-3. The mean standard deviation score (SDS) values were estimated to be 0.7, 3.1 and -1.7 for the IGFBP-1,-2 and-3, respectively, compared with the normal range defined by a SDS from -2 to +2. IGFBP-1 and-3 were normal, but for IGFBP-2 we found a significantly elevated serum level compared with control groups (P < 0.05). However, during chemotherapy this increased serum IGFBP-2 normalized. In addition, we found a correlation between higher serum levels and the detection rate of the IGFBP-2 transcript in corresponding cells. In patients with ALL, the detection rates of IGFBP-2 mRNA were estimated to be 72% and 35% at the time of diagnosis and at day 33 of chemotherapy respectively; in the control groups (healthy children and children at their initial presentation of diabetes mellitus), the values were 28% and 33% respectively. Based on the correlation between IGFBP-2 serum levels and the corresponding gene expression as well as the normalization of IGFBP-2 levels during chemotherapy, we concluded that the increased serum level mainly originated from the tumour clone itself. Furthermore, possible functional consequences of elevated IGFBP-2 were outlined.

Activation-dependent expression of the insulin-like growth factor binding protein-2 in human lymphocytes

The expression of the insulin-like growth factor binding protein-2 (IGFBP-2) was assayed in mononuclear cells originating from different organs of the immune system. All mononuclear cells studied did express IGFBP-2, but the expression level was found to be dependent on the cell type and origin of the cell. T cells showed a higher expression of IGFBP-2 mRNA than did B cells, and CD34+ stem cells expressed IGFBP-2 mRNA at a high level. Expression was highest in bone marrow and thymus. Stimulation of peripheral mononuclear cells resulted in a marked increase of IGFBP-2 mRNA and also intracellular IGFBP-2, as analysed by fluorescence staining. This increase parallels the increase of other known T-cell activation markers. Furthermore, the increase of intracellular IGFBP-2 seems to precede T-cell blast formation and all T cells in active phases of the cell cycle have high levels of IGFBP-2. Our results provide a basis for further investigations on the contribution of the IGF-system to the regulation of T-cell proliferation and differentiation. IGFBP-2, in particular, may have an important influence in the regulation of T-cell activation and proliferation.