Insulin-like growth factor II-mediated proliferation of human neuroblastoma

Preclinical Therapeutic Efficacy of RAF/MEK/ERK and IGF1R/AKT/mTOR Inhibition in Neuroblastoma

Activating mutations in the RAS/MAPK pathway are observed in relapsed neuroblastoma. Preclinical studies indicate that these tumors have an increased sensitivity to inhibitors of the RAS/MAPK pathway, such as MEK inhibitors. MEK inhibitors do not induce durable responses as single agents, indicating a need to identify synergistic combinations of targeted agents to provide therapeutic benefit. We previously showed preclinical therapeutic synergy between a MEK inhibitor, trametinib, and a monoclonal antibody specific for IGF1R, ganitumab in RAS-mutated rhabdomyosarcoma. Neuroblastoma cells, like rhabdomyosarcoma cells, are sensitive to the inhibition of the RAS/MAPK and IGF1R/AKT/mTOR pathways. We hypothesized that the combination of trametinib and ganitumab would be effective in RAS-mutated neuroblastoma. In this study, trametinib and ganitumab synergistically suppressed neuroblastoma cell proliferation and induced apoptosis in cell culture. We also observed a delay in tumor initiation and prolongation of survival in heterotopic and orthotopic xenograft models treated with trametinib and ganitumab. However, the growth of both primary and metastatic tumors was observed in animals receiving the combination of trametinib and ganitumab. Therefore, more preclinical work is necessary before testing this combination in patients with relapsed or refractory RAS-mutated neuroblastoma.

Targeting the myeloid microenvironment in neuroblastoma

Myeloid cells (granulocytes and monocytes/macrophages) play an important role in neuroblastoma. By inducing a complex immunosuppressive network, myeloid cells pose a challenge for the adaptive immune system to eliminate tumor cells, especially in high-risk neuroblastoma. This review first summarizes the pro- and anti-tumorigenic functions of myeloid cells, including granulocytes, monocytes, macrophages, and myeloid-derived suppressor cells (MDSC) during the development and progression of neuroblastoma. Secondly, we discuss how myeloid cells are engaged in the current treatment regimen and explore novel strategies to target these cells in neuroblastoma. These strategies include: (1) engaging myeloid cells as effector cells, (2) ablating myeloid cells or blocking the recruitment of myeloid cells to the tumor microenvironment and (3) reprogramming myeloid cells. Here we describe that despite their immunosuppressive traits, tumor-associated myeloid cells can still be engaged as effector cells, which is clear in anti-GD2 immunotherapy. However, their full potential is not yet reached, and myeloid cell engagement can be enhanced, for example by targeting the CD47/SIRPα axis. Though depletion of myeloid cells or blocking myeloid cell infiltration has been proven effective, this strategy also depletes possible effector cells for immunotherapy from the tumor microenvironment. Therefore, reprogramming of suppressive myeloid cells might be the optimal strategy, which reverses immunosuppressive traits, preserves myeloid cells as effectors of immunotherapy, and subsequently reactivates tumor-infiltrating T cells.

Targeting EP2 receptor with multifaceted mechanisms for high-risk neuroblastoma

Prostaglandin E₂ (PGE₂) promotes tumor cell proliferation, migration, and invasion, fostering an inflammation-enriched microenvironment that facilitates angiogenesis and immune evasion. However, the PGE₂ receptor subtype (EP1–EP4) involved in neuroblastoma (NB) growth remains elusive. Herein, we show that the EP2 receptor highly correlates with NB aggressiveness and acts as a predominant Gα_s-coupled receptor mediating PGE₂-initiated cyclic AMP (cAMP) signaling in NB cells with high-risk factors, including 11q deletion and MYCN amplification. Knockout of EP2 in NB cells blocks the development of xenografts, and its conditional knockdown prevents established tumors from progressing. Pharmacological inhibition of EP2 by our recently developed antagonist TG6-129 suppresses the growth of NB xenografts in nude mice and syngeneic allografts in immunocompetent hosts, accompanied by anti-inflammatory, antiangiogenic, and apoptotic effects. This proof-of-concept study suggests that the PGE₂/EP2 signaling pathway contributes to NB malignancy and that EP2 inhibition by our drug-like compounds provides a promising strategy to treat this deadly pediatric cancer.

Hou et al. discover that prostaglandin receptor EP2 highly correlates with the aggressiveness of neuroblastoma, where it acts as the primary PGE₂ receptor mediating cAMP signaling. EP2 deficiency or inhibition suppresses neuroblastoma with high-risk factors including 11q deletion and MYCN amplification, demonstrating EP2 as a promising therapeutic target for neuroblastoma.

Acute Maneb Exposure Significantly Alters Both Glycolysis and Mitochondrial Function in Neuroblastoma Cells

The pesticides paraquat (PQ) and maneb (MB) have been described as environmental risk factors for Parkinson's disease (PD), with mechanisms associated with mitochondrial dysfunction and reactive oxygen species generation. A combined exposure of PQ and MB in murine models and neuroblastoma cells has been utilized to further advance understanding of the PD phenotype. MB acts as a redox modulator through alkylation of protein thiols and has been previously characterized to inhibit complex III of the electron transport chain and uncouple the mitochondrial proton gradient. The purpose of this study was to analyze ATP-linked respiration and glycolysis in human neuroblastoma cells utilizing the Seahorse extracellular flux platform. Employing an acute, subtoxic exposure of MB, this investigation revealed a MB-mediated decrease in mitochondrial oxygen consumption at baseline and maximal respiration, with inhibition of ATP synthesis and coupling efficiency. Additionally, MB-treated cells showed an increase in nonmitochondrial respiration and proton leak. Further investigation into mitochondrial fuel flex revealed an elimination of fuel flexibility across all 3 major substrates, with a decrease in pyruvate capacity as well as glutamine dependency. Analyses of glycolytic function showed a substantial decrease in glycolytic acidification caused by lactic acid export. This inhibition of glycolytic parameters was also observed after titrating the MB dose as low as 6 μM, and appears to be dependent on the dithiocarbamate functional group, with manganese possibly potentiating the effect. Further studies into cellular ATP and NAD levels revealed a drastic decrease in cells treated with MB. In summary, MB significantly impacted both aerobic and anaerobic energy production; therefore, further characterization of MB's effect on cellular energetics may provide insight into the specificity of PD to dopaminergic neurons.

Chromogranin A regulates neuroblastoma proliferation and phenotype

Neuroblastoma is a commonly encountered solid tumor in early childhood with high neuroplasticity, and differentiation therapy is hypothesized to lead to tumor mass shrinkage and/or symptom relief. CgA is a tissue specific protein restricted to the diffuse neuroendocrine system, and widely expressed in neuroblastomas. Using knockdown and knockout approaches to deplete CgA levels, we demonstrated that CgA loss inhibits SH-SY5Y cell proliferation and leads to a morphological shift with increased expression of Schwann and extracellular matrix specific molecules, and suppression of chromaffin features. We further confirmed the effects of CgA in a series of neuroblastoma cells with [BE(2)-M17 and IMR-32] and without (SK-N-SH) N-Myc amplification. We demonstrated that CgA depletion reduced IGF-II and IGFBP-2 expression, increased IGFBP-3 levels, and suppresses IGF downstream signaling as evidenced by reduced AKT/ERK pathway activation. This was further supported by an increased anti-proliferative effect of the ERK inhibitor in the CgA depleted cells. In an in vivo xenograft neuroblastoma model, CgA knockdown led to increased S-phenotypic marker expression at both protein and mRNA levels. Together these results suggest that CgA maintains IGF secretion and intracellular signaling to regulate proliferation and differentiation in neuroblastomas.

Doxorubicin-provoked increase of mitotic activity and concomitant drain of G0-pool in therapy-resistant BE(2)-C neuroblastoma

In this study chemotherapy response in neuroblastoma (NB) was assessed for the first time in a transplantation model comprising non-malignant human embryonic microenvironment of pluripotent stem cell teratoma (PSCT) derived from diploid bona fide hESC. Two NB cell lines with known high-risk phenotypes; the multi-resistant BE(2)-C and the drug sensitive IMR-32, were transplanted to the PSCT model and the tumour growth was exposed to single or repeated treatments with doxorubicin, and thereafter evaluated for cell death, apoptosis, and proliferation. Dose dependent cytotoxic effects were observed, this way corroborating the experimental platform for this type of analysis. Notably, analysis of doxorubicin-resilient BE(2)-C growth in the PSCT model revealed an unexpected 1,5-fold increase in Ki67-index (p<0.05), indicating that non-cycling (G0) cells entered the cell cycle following the doxorubicin exposure. Support for this notion was obtained also in vitro. A pharmacologically relevant dose (1μM) resulted in a marked accumulation of Ki67 positive BE(2)-C cells (p<0.0001), as well as a >3-fold increase in active cell cycle (i.e. cells positive staining for PH3 together with incorporation of EdU) (p<0.01). Considering the clinical challenge for treating high-risk NB, the discovery of a therapy-provoked growth-stimulating effect in the multi-resistant and p53-mutated BE(2)-C cell line, but not in the drug-sensitive p53wt IMR-32 cell line, warrants further studies concerning generality and clinical significance of this new observation.

Increased motor neuron resilience by small molecule compounds that regulate IGF-II expression

The selective vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS) is evident by sparing of a few subpopulations during this fast progressing and debilitating degenerative disease. By studying the gene expression profile of resilient vs. vulnerable motor neuron populations we can gain insight in what biomolecules and pathways may contribute to the resilience and vulnerability. Several genes have been found to be differentially expressed in the vulnerable motor neurons of the cervical spinal cord as compared to the spared motor neurons in CNIII/IV. One gene that is differentially expressed and present at higher levels in less vulnerable motor neurons is insulin-like growth factor II (IGF-II). The motor neuron protective effect of IGF-II has been demonstrated both in vitro and in SOD1 transgenic mice. Here, we have screened a library of small molecule compounds and identified inducers of IGF-II mRNA and protein expression. Several identified compounds significantly protected motor neurons from glutamate excitotoxicity in vitro. One of the compounds, vardenafil, resulted in a complete motor neuron protection, an effect that was reversed by blocking receptors of IGF-II. When administered to naïve rats vardenafil was present in the cerebrospinal fluid and increased IGF-II mRNA expression in the spinal cord. When administered to SOD1 transgenic mice, there was a significant delay in motor symptom onset and prolonged survival. Vardenafil also increased IGF-II mRNA and protein levels in motor neurons derived from healthy subject and ALS patient iPSCs, activated a human IGF-II promoter and improved survival of ALS-patient derived motor neurons in culture. Our findings suggest that modulation of genes differentially expressed in vulnerable and resilient motor neurons may be a useful therapeutic approach for motor neuron disease.

A Phase I Study of Cixutumumab (IMC-A12) in Combination with Temsirolimus (CCI-779) in Children with Recurrent Solid Tumors: A Children's Oncology Group Phase I Consortium Report

PURPOSE

To determine the MTD, dose-limiting toxicities (DLT), pharmacokinetics, and biologic effects of cixutumumab administered in combination with temsirolimus to children with refractory solid tumors.

EXPERIMENTAL DESIGN

Cixutumumab and temsirolimus were administered intravenously once every 7 days in 28-day cycles. Pharmacokinetic and biology studies, including assessment of mTOR downstream targets in peripheral blood mononuclear cells, were performed during the first cycle.

RESULTS

Thirty-nine patients, median age 11.8 years (range, 1-21.5), with recurrent solid or central nervous system tumors were enrolled, of whom 33 were fully assessable for toxicity. There were four dose levels, which included two dose reductions and a subsequent intermediated dose escalation: (i) IMC-A12 6 mg/kg, temsirolimus 15 mg/m(2); (ii) IMC-A12 6 mg/kg, temsirolimus 10 mg/m(2); (iii) IMC-A12 4 mg/kg, temsirolimus 8 mg/m(2); and (iv) IMC-A12 6 mg/kg, temsirolimus 8 mg/m(2). Mucositis was the predominant DLT. Other DLTs included hypercholesterolemia, fatigue, thrombocytopenia, and increased alanine aminotransferase. Target inhibition (decreased S6K1 and PAkt) in peripheral blood mononuclear cells was noted at all dose levels. Marked interpatient variability in temsirolimus pharmacokinetic parameters was noted. At 8 mg/m(2), the median temsirolimus AUC was 2,946 ng • h/mL (range, 937-5,536) with a median sirolimus AUC of 767 ng • h/mL (range, 245-3,675).

CONCLUSIONS

The recommended pediatric phase II doses for the combination of cixutumumab and temsirolimus are 6 mg/kg and 8 mg/m(2), respectively.

IGF2 and cancer

Insulin-like growth factor 2 (IGF2) is a 7.5  kDa mitogenic peptide hormone expressed by liver and many other tissues. It is three times more abundant in serum than IGF1, but our understanding of its physiological and pathological roles has lagged behind that of IGF1. Expression of the IGF2 gene is strictly regulated. Over-expression occurs in many cancers and is associated with a poor prognosis. Elevated serum IGF2 is also associated with increased risk of developing various cancers including colorectal, breast, prostate and lung. There is established clinical utility for IGF2 measurement in the diagnosis of non-islet cell tumour hypoglycaemia, a condition characterised by a molar IGF2:IGF1 ratio >10. Recent advances in understanding of the pathophysiology of IGF2 in cancer have suggested much novel clinical utility for its measurement. Measurement of IGF2 in blood and genetic and epigenetic tests of the IGF2 gene may help assess cancer risk and prognosis. Further studies will determine whether these tests enter clinical practice. New therapeutic approaches are being developed to target IGF2 action. This review provides a clinical perspective on IGF2 and an update on recent research findings.

Combination testing (Stage 2) of the Anti-IGF-1 receptor antibody IMC-A12 with rapamycin by the pediatric preclinical testing program

BACKGROUND

IMC-A12, a fully human antibody that blocks ligand binding to the Type 1 insulin-like growth factor receptor, and rapamycin, a selective inhibitor of mTORC1 signaling, have both demonstrated significant antitumor activity against PPTP solid tumor models. Here we have evaluated antitumor activity of each agent individually and in combination against nine tumor models.

PROCEDURES

IMC-A12 was administered twice weekly and rapamycin was administered daily for 5 days per week for a planned 4 weeks. The impact of combining IMC-A12 with rapamycin was evaluated using two measures: (1) the "therapeutic enhancement" measure, and (2) a linear regression model for time-to-event to formally evaluate for sub- and supra-additivity for the combination compared to the agents used alone.

RESULTS

Two osteosarcomas, and one Ewing sarcoma of the nine xenografts tested showed therapeutic enhancement. The combination effect was most dramatic for EW-5 for which PD2 responses of short duration were observed for both single agents and a prolonged PR response was observed for the combination. Both OS-2 and OS-9 showed significantly longer times to progression with the combination compared to either of the single agents, although objective response criteria were not met.

CONCLUSIONS

The combination of IMC-A12 with rapamycin was well tolerated, and induced tumor responses that were superior to either single agent alone in several models. These studies confirm reports using other antibodies that inhibit IGF-1 receptor-mediated signaling that indicate enhanced therapeutic effect for this combination, and extend the range of histotypes to encompass additional tumors expressing IGF-1R where this approach may be effective.

Potent inhibition of angiogenesis by the IGF-1 receptor-targeting antibody SCH717454 is reversed by IGF-2

Previously, we reported that a predominant action of a type-1 insulin-like growth factor receptor (IGF-1R)-targeted antibody was through inhibiting tumor-derived VEGF, and indirectly, angiogenesis. Here, we examined the direct antiangiogenic activity of the IGF-1R-targeted antibody SCH717454 that inhibits ligand-receptor binding and the mechanism by which tumors circumvent its antiangiogenic activity. Inhibition of ligand-stimulated activation of IGF-1R, insulin receptor (IN-R), or downstream signaling [phosphorylation of Akt (Ser473)] was determined by receptor-specific immunoprecipitation and immunoblotting. Inhibition of angiogenesis was determined by proliferation and tube formation using human umbilical vein endothelial cells (HUVEC) in vitro and in Matrigel plugs implanted in mice. SCH717454 blocked IGF-1-stimulated but not IGF-2-stimulated phosphorylation of Akt in sarcoma cells. Immunoprecipitation using anti-IGF-1R and anti-IN-R antibodies revealed that SCH717454 equally blocked IGF-1-stimulated and IGF-2-stimulated IGF-1R phosphorylation, but not IGF-2-stimulated phosphorylation of IN-R. SCH717454 completely blocked VEGF-stimulated proliferation and tube formation of HUVECs, but exogenous IGF-2 and insulin circumvented these inhibitory effects. Coculture of HUVECs with IGF-2-secreting tumor cells completely abrogated SCH717454 inhibition of VEGF-stimulated HUVEC tube formation. In mice, SCH717454 inhibited angiogenesis in VEGF-infused Matrigel plugs, but had no inhibitory activity when plugs contained both VEGF + IGF-2. These results reveal for the first time, a role for IGF-1R signaling in VEGF-mediated angiogenesis in vitro and indicate direct antiangiogenic activity of SCH717454. Both in vitro and in vivo IGF-2 circumvented these effects through IN-R signaling. Many childhood cancers secrete IGF-2, suggesting that tumor-derived IGF-2 in the microenvironment maintains angiogenesis in the presence of IGF-1R-targeted antibodies allowing tumor progression.

Initial testing (stage 1) of the IGF-1 receptor inhibitor BMS-754807 by the pediatric preclinical testing program

BACKGROUND

BMS-754807 is a small molecule ATP-competitive inhibitor of the type-1 insulin-like growth factor receptor currently in phase 1 clinical trials.

PROCEDURES

BMS-754807 was tested against the Pediatric Preclinical Testing Program (PPTP) in vitro panel at concentrations ranging from 1.0 nM to 10 µM and was tested against the PPTP in vivo panels at a dose of 25 mg/kg administered orally BID for 6 days, repeated for 6 weeks.

RESULTS

In vitro BMS-754807 showed a median EC(50) value of 0.62 µM against the PPTP cell lines. The median EC(50) for the four Ewing sarcoma cell lines was less than that for the remaining PPTP cell lines (0.19 µM vs. 0.78 µM, P = 0.0470). In vivo BMS-754807 induced significant differences in EFS distribution compared to controls in 18 of 32 evaluable solid tumor xenografts (56%) tested, but in none of the ALL xenografts studied. Criteria for intermediate activity for the time to event activity measure (EFS T/C > 2) were met in 7 of 27 solid tumor xenografts evaluable for this measure. The best response was PD2 (progressive disease with growth delay), which was observed in 18 of 32 solid tumor xenografts. PD2 responses were most commonly observed in the rhabdomyosarcoma, neuroblastoma, osteosarcoma, Ewing sarcoma, and Wilms tumor panels.

CONCLUSIONS

BMS-754807 activity in vitro is consistent with a specific IGF-1R effect that has half-maximal response in the 0.1 µM range and that is observed in a minority of the PPTP cell lines. In vivo intermediate activity was most commonly observed in the neuroblastoma and rhabdomyosarcoma panels.

[Antidiabetic therapy--a new possibility in the complex therapy of cancer?]

Nowadays the lack of exercise and improper eating habits are main characteristics of modern life style. This favors not only formation of type 2 diabetes or cardiovascular diseases, but also increaseas the incidence and prevalence of malignant tumors. Today there are many epidemiologic trials that demonstrate the connection between type 2 diabetes and formation of several malignomas. Its cause should be searched in common paths of pathologic processes. One of this is the birth of hyperinsulinsulinemia, which accompanies insulin resistance. Hyperinsulinemia of the host leads to increased glucose uptake in the highly insuline sensitive tumor cells which supports tumor growth. This makes type 2 diabetes a metabolic state favoring tumor formation, suggesting a potential application of oral insulin sensitizers in cancer therapy. Currently several international trials are testing the anti-tumor activity of metformin and thiazolidinedions (TZD). Besides this, encouraging results were obtained with the use of anti-IGFR antibodies in the treatment of tumors. A common therapy of diabetes and tumor may lead to new possibilities in the treatment of malignant tumor diseases. By doing this we could be able to weaken the tumor and strengthen the body, enabling it to fight against cancer. Bánhegyi RJ, Rus-Gal PO, Nagy AK, Martyin T, Varga R, Pikó B. Correlation between type 2 diabetes and malignant tumors - new possibilities in the complex therapy of cancers?

Insulin-like growth factor-1 and childhood cancer risk

Overexpression of growth factors and/or their receptors is a common event in malignancy and provides the underlying mechanisms for one of the hallmarks of cancer, uncontrolled proliferation. Mounting evidence suggests that IGF-1 is involved in the pathogenesis and progression of different types of human cancer such as colon, breast, prostate and lung. However, only a few studies have investigated the association between IGF-1 levels and childhood cancer risk. We aimed to compare the IGF-1 serum level in children with de novo malignancies to healthy children, and to assess its relationship with cancer type, stage, metastasis and different disease characteristics. The study was carried out on 100 children; 50 children with de novo malignancies and 50 healthy children of matched age and gender as a control group. The patients were subjected to a routine work-up for their cancers according to our local standards. Estimation of the serum level of IGF-1 was carried out in the two groups using ELISA. Our results showed that children with cancer had significantly higher levels of IGF-1 than healthy controls of the same age and gender. No association was found between IGF-1 and tumor type, stage, metastasis and other disease characteristics. In conclusion, the IGF-1 serum level is an important indicator of risk for the most prevalent forms of childhood cancer. It may be used to identify children at the highest risk for these cancers and aid in determing who may benefit most from preventive strategies. Given the small number of children in our study, studies with larger populations are required to confirm these results.

Helianthin induces antiproliferative effect on human glioblastoma cells in vitro

A major focus of brain cancer research today is to translate understanding of glioma biology into advances in treatment, by exploring the potential of target therapy. Here we investigated the ability of three compounds belonging to the chemical class of azo dyes (methyl red, methyl yellow, and helianthin) to inhibit glioblastoma (GB) cell growth in vitro. Our results showed that helianthin induced cytotoxicity in two GB cell cultures, cell lines 18 and 38, whereas methyl red and methyl yellow were not cytotoxic. The effect of helianthin on EGFR, IGF-1R, and their common intracellular signaling via PI3-K and ERK1/2 was also analyzed. Treatment with helianthin down-regulated EGFR and IGF-1R activity in both cell lines. Helianthin treatment blocked ERK1/2 phosphorylation without affecting PI3K activity in cell line 18 and reduced both PI3K and ERK1/2 in GB 38 cell line. The cell death was accompanied by degradation of PARP without affecting BCL2 expression in both GB cell cultures. Because of the genetic heterogeneity of malignant gliomas, we tested the effect of helianthin on other two primary GB lines (11 and 15) and two early-passage GB cultures (BT1GB and BT2GB), to assess the general nature of the anti-tumor effect of the drug in GB cells. We found that helianthin treatment induced cell death in all the GB cell cultures analyzed. To our knowledge, this is the first report indicating that helianthin can reduce GB cell growth.

The insulin-like growth factor-1 receptor-targeting antibody, CP-751,871, suppresses tumor-derived VEGF and synergizes with rapamycin in models of childhood sarcoma

Signaling through the type 1 insulin-like growth factor receptor (IGF-1R) occurs in many human cancers, including childhood sarcomas. As a consequence, targeting the IGF-1R has become a focus for cancer drug development. We examined the antitumor activity of CP-751,871, a human antibody that blocks IGF-1R ligand binding, alone and in combination with rapamycin against sarcoma cell lines in vitro and xenograft models in vivo. In Ewing sarcoma (EWS) cell lines, CP751,871 inhibited growth poorly (<50%), but prevented rapamycin-induced hyperphosphorylation of AKT(Ser473) and induced greater than additive apoptosis. Rapamycin treatment also increased secretion of IGF-1 resulting in phosphorylation of IGF-1R (Tyr1131) that was blocked by CP751,871. In vivo CP-751,871, rapamycin, or the combination were evaluated against EWS, osteosarcoma, and rhabdomyosarcoma xenografts. CP751871 induced significant growth inhibition [EFS(T/C) >2] in four models. Rapamycin induced significant growth inhibition [EFS(T/C) >2] in nine models. Although neither agent given alone caused tumor regressions, in combination, these agents had greater than additive activity against 5 of 13 xenografts and induced complete remissions in one model each of rhabdomyosarcoma and EWS, and in three of four osteosarcoma models. CP751,871 caused complete IGF-1R down-regulation, suppression of AKT phosphorylation, and dramatically suppressed tumor-derived vascular endothelial growth factor (VEGF) in some sarcoma xenografts. Rapamycin treatment did not markedly suppress VEGF in tumors and synergized only in tumor lines where VEGF was dramatically inhibited by CP751,871. These data suggest a model in which blockade of IGF-1R suppresses tumor-derived VEGF to a level where rapamycin can effectively suppress the response in vascular endothelial cells.

The role of IGF-1R in pediatric malignancies

The insulin-like growth factor (IGF) family consists of ligands (IGF-I, IGF-II, insulin), several receptors (including IGF-1R), and six binding proteins (IGFBP-1 through IGFBP-6). Members of this family regulate key cellular activities and they also play an important role in the development and progression of both adult and childhood cancers. Binding of a ligand to the receptor leads to its activation, followed by signal transduction along several pathways. In some childhood malignancies, IGF-1R can be activated by endocrine, autocrine, or paracrine mechanisms. Although mutations in IGF-1R have not been identified, this signaling pathway is upregulated in many childhood cancers. These findings have led to the development of a host of IGF-1R signaling modulators that are currently being tested in clinical trials. This review explores the role of IGF-1R in a range of childhood malignancies.

Targeting the phosphoinositide 3-kinase isoform p110delta impairs growth and survival in neuroblastoma cells

PURPOSE

The phosphoinositide 3-kinase (PI3K)/Akt pathway is frequently activated in human cancer and plays a crucial role in neuroblastoma biology. We were interested in gaining further insight into the potential of targeting PI3K/Akt signaling as a novel antiproliferative approach in neuroblastoma.

EXPERIMENTAL DESIGN

The expression pattern and functions of class I(A) PI3K isoforms were investigated in tumor samples and cell lines. Effects on cell survival and downstream signaling were analyzed following down-regulation of p110alpha or p110delta in SH-SY5Y and LA-N-1 cells by means of RNA interference.

RESULTS

Overexpression of the catalytic p110delta and regulatory p85alpha isoforms was detected in a panel of primary neuroblastoma samples and cell lines, compared with normal adrenal gland tissue. Although down-regulation of either p110alpha or p110delta led to impaired cell growth, reduced expression of p110delta also had a selective effect on the survival of SH-SY5Y cells. Decreased levels of p110delta were found to induce apoptosis and lead to lower expression levels of antiapoptotic Bcl-2 family proteins. SH-SY5Y cells with decreased p110delta levels also displayed reduced activation of ribosomal protein S6 kinase in response to stimulation with epidermal growth factor and insulin-like growth factor-I.

CONCLUSIONS

Together, our data reveal a novel function of p110delta in neuroblastoma growth and survival.

Initial testing (stage 1) of a monoclonal antibody (SCH 717454) against the IGF-1 receptor by the pediatric preclinical testing program

BACKGROUND

SCH 717454 (19D12) is a fully human antibody directed against the insulin-like growth factor 1 receptor (IGF-1R), which is implicated in the growth and metastatic phenotype of a broad range of malignancies. The activity of SCH 717454 was evaluated against the in vitro and in vivo panels of the Pediatric Preclinical Testing Program (PPTP).

PROCEDURES

SCH 717454 was tested against the PPTP in vitro panel at concentrations ranging from 0.01 to 100 nM and was tested against the PPTP in vivo panel at a dose of 0.5 mg per mouse administered twice weekly for 4 weeks via intraperitoneal injection.

RESULTS

SCH 717454 was ineffective at retarding growth of cell lines in the in vitro panel. In vivo, SCH 717454 significantly increased event-free survival in 20 of 35 (57%) solid tumor xenograft models with tumor regressions in one Ewing sarcoma model (complete response) and 2 osteosarcoma models (maintained complete responses). Using the time to event activity measure, SCH 717454 had intermediate (n = 9) or high (n = 1) activity against 31 evaluable solid tumor xenografts, including xenografts from the rhabdoid tumor, Ewing, rhabdomyosarcoma, glioblastoma, neuroblastoma, and osteosarcoma panels. SCH 717454 showed little activity against the 8 xenografts of the acute lymphoblastic leukemia panel.

CONCLUSIONS

SCH 717454 demonstrated broad antitumor activity against the PPTP's in vivo solid tumor panels. Further characterization of the molecular predictors of response and of the activity of combinations of SCH 717454 with other anticancer agents are anticipated.

Insulin-like growth factor-II: a novel autocrine growth factor modulating the apoptosis and maturation of umbilical cord blood erythroid progenitors

OBJECTIVE

To search a novel function of erythroid progenitor cells circulating as the major nucleated cell population in umbilical cord blood (CB) cells.

MATERIALS AND METHODS

Human CB-derived CD36(+) erythroid progenitors were subjected to cDNA microarray. Gene expression and biological property of CB-erythroid progenitors and adult peripheral blood (PB)-erythroid progenitors were compared by using real-time polymerase chain reaction (PCR) and serum-free culture system with erythropoietin (EPO).

RESULTS

The microarray revealed 124-fold higher levels of insulin-like growth factor-II (IGF-II) gene expression in CB-CD36(+) erythroid progenitors than in stimulated lymphocytes of adult PB. Real-time PCR verified that IGF-II mRNA levels were highest in CB-CD36(+) erythroid progenitors compared to other CB- or adult PB-fractionated cells. When CB-CD36(+) erythroid progenitors were cultured with EPO in serum-free medium, anti-IGF-II-antibody (Ab) reduced the number of erythroid colonies. When CB- and adult PB-derived erythroid colony-forming cells (ECFCs) were cultured with interleukin-3, stem cell factor, and EPO, mRNA levels per cells of IGF-II peaked on day 12, but those of type 1 and type 2 receptors did not increase with ECFCs maturation. The maturation rate by IGF-II was higher in CB-ECFCs than in adult PB-ECFCs. The majority of CB-ECFCs expressed IGF-II protein. Anti-IGF-II-Ab, but not anti-IGF-I-Ab, reduced the number of CB-ECFCs in liquid culture with EPO. Anti-IGF-II-Ab accelerated apoptosis of ECFCs, assessed by dimethylthiazole tetrazolium bromide, bromodeoxyuridine, and flow cytometric analyses. ECFCs failed to attain full maturity in the presence of anti-IGF-II-Ab.

CONCLUSIONS

These results suggest that IGF-II is produced by erythroid progenitors themselves, and has a crucial role in fetal erythropoiesis by modulating apoptosis and maturation in an autocrine fashion.

IGF signaling as a therapeutic target in pediatric solid tumors of the central and peripheral nervous system

Similar to many other growth factor systems, the IGF system consists of more than a single ligand interacting with a single receptor. There are three ligands (IGF-I, IGF-II and insulin) that interact with at least four receptors. In addition, the IGF system also involves six well-characterized binding proteins that regulate IGF action. Type I IGF receptor-mediated signaling plays a fundamental role in cell growth and malignant transformation and is an important mediator of anti-apoptotic signals. This review describes the roles of IGF signaling in childhood tumors of the CNS and PNS, including neuroblastoma, medulloblastoma, atypical teratoid/rhabdoid tumors and craniopharyngioma. Moreover, it describes strategies to disrupt the IGF signaling as a potential cancer therapy.

Angiotensin I-converting enzyme insertion-related genotypes and allele are associated with higher susceptibility of endometriosis and leiomyoma

Endometriosis and leiomyoma display features similar to malignancy, requiring neovascularization to proliferation and growth. Altered vascular-related genes might be related to the development of endometriosis and leiomyoma. Polymorphisms of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) genes have been linked with some vascular diseases. This study investigates whether ACE I/D gene polymorphisms could be used as markers of susceptibility in endometriosis and leiomyoma. Women were divided into three groups: (1) endometriosis (n = 125); (2) leiomyoma (n = 120); (3) normal controls (n = 128). Genomic DNA was obtained from peripheral leukocyte. ACE I/D gene polymorphisms in intron 16 were amplified by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) Genotypes and allelic frequencies in both groups were compared. We observed the genotype distribution and allele frequency of ACE I/D gene polymorphisms in both groups were significantly different. Proportions of ACE*I homozygote/heterozygote/D homozygote in both groups were: (1) 50.4/24/25.6%; (2) 25/23.33/51.67%; (3) 10.2/29.7/60.1%. Proportions of I/D alleles in each group were: (1) 62.4/37.6%; (2) 36.7/63.3%; (3) 25/75%. We concluded that ACE*I/D gene polymorphisms are associated with endometriosis and leiomyoma susceptibilities. ACE*I-related genotypes and allele are strongly related to the occurrence of endometriosis and moderately related to the occurrence of leiomyoma.

A novel, potent, and selective insulin-like growth factor-I receptor kinase inhibitor blocks insulin-like growth factor-I receptor signaling in vitro and inhibits insulin-like growth factor-I receptor dependent tumor growth in vivo

Insulin-like growth factor-I receptor (IGF-IR) and its ligands, IGF-I and IGF-II, are up-regulated in a variety of human cancers. In tumors, such as colorectal, non-small cell lung, ovarian, and pediatric cancers, which may drive their own growth and survival through autocrine IGF-II expression, the role of IGF-IR is especially critical. Here, we present a novel small-molecule IGF-IR kinase inhibitor, cis-3-[3-(4-methyl-piperazin-l-yl)-cyclobutyl]-1-(2-phenyl-quinolin-7-yl)-imidazo[1,5-a]pyrazin-8-ylamine (PQIP), which displayed a cellular IC(50) of 19 nmol/L for inhibition of ligand-dependent autophosphorylation of human IGF-IR with 14-fold cellular selectivity relative to the human insulin receptor. PQIP showed minimal activity against a panel of 32 other protein kinases. It also abolished the ligand-induced activation of downstream phosphorylated AKT and phosphorylated extracellular signal-regulated kinase 1/2 in both IGF-IR transfectant cells and a GEO human colorectal cancer cell line. Analysis of GEO cells revealed a significant level of both phosphorylated IGF-IR and IGF-II expression. Furthermore, inactivation of IGF-II in conditioned GEO culture medium by a neutralizing antibody diminished IGF-IR activation, indicating the presence of a functional IGF-II/IGF-IR autocrine loop in GEO cells. Once daily oral dosing of PQIP induced robust antitumor efficacy in GEO xenografts. The antitumor efficacy correlated with the degree and duration of inhibition of tumor IGF-IR phosphorylation in vivo by this compound. Moreover, when mice were treated for 3 days with a dose of PQIP that maximally inhibited tumor growth, only minor changes in blood glucose were observed. Thus, PQIP represents a potent and selective IGF-IR kinase inhibitor that is especially efficacious in an IGF-II-driven human tumor model.

Genome-wide analysis of neuroblastomas using high-density single nucleotide polymorphism arrays

Background

Neuroblastomas are characterized by chromosomal alterations with biological and clinical significance. We analyzed paired blood and primary tumor samples from 22 children with high-risk neuroblastoma for loss of heterozygosity (LOH) and DNA copy number change using the Affymetrix 10K single nucleotide polymorphism (SNP) array.

Findings

Multiple areas of LOH and copy number gain were seen. The most commonly observed area of LOH was on chromosome arm 11q (15/22 samples; 68%). Chromosome 11q LOH was highly associated with occurrence of chromosome 3p LOH: 9 of the 15 samples with 11q LOH had concomitant 3p LOH (P = 0.016). Chromosome 1p LOH was seen in one-third of cases. LOH events on chromosomes 11q and 1p were generally accompanied by copy number loss, indicating hemizygous deletion within these regions. The one exception was on chromosome 11p, where LOH in all four cases was accompanied by normal copy number or diploidy, implying uniparental disomy. Gain of copy number was most frequently observed on chromosome arm 17q (21/22 samples; 95%) and was associated with allelic imbalance in six samples. Amplification of MYCN was also noted, and also amplification of a second gene, ALK, in a single case.

Conclusions

This analysis demonstrates the power of SNP arrays for high-resolution determination of LOH and DNA copy number change in neuroblastoma, a tumor in which specific allelic changes drive clinical outcome and selection of therapy.

Interleukin (IL)-12 receptor beta1 codon 378 G homozygote and allele, but not IL-1 (beta-511 promoter, 3953 exon 5, receptor antagonist), IL-2 114, IL-4-590 intron 3, IL-8 3'-UTR 2767, and IL-18 105, are associated with higher susceptibility to leiomyoma

OBJECTIVE

To investigate whether certain polymorphisms are correlated with leiomyoma susceptibility, i.e., interleukin (IL)-1, IL-2, IL-4, IL-8, IL-12, and IL-18, which are all immunomodulatory cytokines that play important roles in host immune responses against cancers.

SETTING

Departments of gynecology and genetics in a medical center.

PATIENT(S)

Women were divided into: [1] a leiomyoma group (n = 162) and [2] a nonleiomyoma group (n = 156).

INTERVENTION(S)

Genotyping for the IL-1beta-511 promoter, IL-1beta exon 5, IL-1Ra, IL-2 114, IL-4 -590 intron 3, IL-8 3'-UTR 2767, IL-12Rbeta1 codon 378, and IL-18 105 were evaluated by polymerase chain reaction-restriction fragment length polymorphism.

MAIN OUTCOME MEASUREMENT(S)

Genotypes and allelic frequencies in both groups were compared.

RESULT(S)

Proportions of IL-12Rbeta1 codon 378 *CC/CG/GG in the leiomyoma and nonleiomyoma groups were: [1] 7.4%/43.8%/48.8% and [2] 11.5%/54.5%/34%, respectively. Distributions of other polymorphisms in both groups were not significantly different. Proportions of IL-1beta-511 promoter *CC/CT/TT were: [1] 22.8%/50%/27.2% and [2] 21.8%/57.1%/21.1% in the leiomyoma and nonleiomyoma groups, respectively. The IL-1beta exon 5 *E1 homozygote/heterozygote/E2 homozygote were: [1] 96.3%/3.7%/0% and [2] 96.9%/3.1%/0% in the leiomyoma and nonleiomyoma groups, respectively. Alleles I/II/III/IV/V for IL-1Ra were: [1] 92.6%/7.1%/0.3%/0/0% and [2] 93.9%/5.7%/0%/0.4/0% in the leiomyoma and nonleiomyoma groups, respectively. The IL-2 114 G homozygote/heterozygote/T homozygote were: [1] 27.8%/49.4%/22.8% and [2] 20.5%/53.2%/26.3% in the leiomyoma and nonleiomyoma groups, respectively. The IL-4 -590 intron 3 *RP1 homozygote/heterozygote/RP2 homozygote were: [1] 64.8%/32.7%/2.5% and [2] 69.2%/26.9%/3.9% in the leiomyoma and nonleiomyoma groups, respectively. The IL-8 3'-UTR 2767 A homozygote/heterozygote/G homozygote were: [1] 14.2%/43.8%/42% and [2] 20.5%/41.7%/37.8% in the leiomyoma and nonleiomyoma groups, respectively. The IL-18 *AA/AC/CC were: [1] 56.8%/40.7%/2.5% and [2] 59%/39.7%/1.3% in the leiomyoma and nonleiomyoma groups, respectively.

CONCLUSION(S)

The IL-12Rbeta1 codon 378 *G homozygote and G allele are related to a higher susceptibility to leiomyoma. The IL-1beta-511 promoter, IL-1beta exon 5, and IL-1Ra, IL-2 114, IL-4 -590 intron 3, IL-8 3'-UTR 2767, and IL-18 105 gene polymorphisms are not correlated with the development of leiomyoma.

Protein kinase B modulates the sensitivity of human neuroblastoma cells to insulin-like growth factor receptor inhibition

The potential of the novel insulin-like growth factor receptor (IGF-IR) inhibitor NVP-AEW541 as an antiproliferative agent in human neuroblastoma was investigated. Proliferation of a panel of neuroblastoma cell lines was inhibited by NVP-AEW541 with IC(50) values ranging from 0.15 to 5 microM. Experiments using an IGF-IR neutralizing antibody confirmed that the IGF-IR was essential to support growth of neuroblastoma cell lines. The expression levels of the IGF-IR in individual neuroblastoma cell lines did not correlate with the sensitivities to NVP-AEW541, while coexpression of the IGF-IR and the insulin receptor (IR) correlated with lower sensitivity to the inhibitor in some cell lines. Intriguingly, high levels of activation of Akt/protein kinase B (PKB) and phosphorylation of the ribosomal S6 protein were observed in neuroblastoma cell lines with decreased sensitivities to NVP-AEW541. Inhibition of Akt/PKB activity restored the sensitivity of neuroblastoma cells to the IGF-IR inhibitor. Transfection of neuroblastoma cells with activated Akt or ribosomal protein S6 kinase (S6K) decreased the sensitivity of the cells to NVP-AEW541. IGF-I-stimulated proliferation of neuroblastoma cell lines was completely blocked by NVP-AEW541, or by a combination of an inhibitor of phosphoinositide 3-kinase and rapamycin. In addition to its antiproliferative effects, NVP-AEW541 sensitized neuroblastoma cells to cisplatin-induced apoptosis. Together, our data demonstrate that NVP-AEW541 in combination with Akt/PKB inhibitors or chemotherapeutic agents may represent a novel approach to target human neuroblastoma cell proliferation.

Down-Regulation of Insulin-Like Growth Factor I Receptor Activity by NVP-AEW541 Has an Antitumor Effect on Neuroblastoma Cells In vitro and In vivo

PURPOSE

Signaling through insulin-like growth factor I receptor (IGF-IR) is important for growth and survival of many tumor types. Neuroblastoma is sensitive to IGF.

EXPERIMENTAL DESIGN

We assessed the ability of NVP-AEW541, a recently developed small molecule that selectively inhibits IGF-IR activity, for neuroblastoma growth effects in vitro and in vivo. Our data showed that, in a panel of 10 neuroblastoma cell lines positive for IGF-IR expression, NVP-AEW541 inhibited in vitro proliferation in a submicromolar/micromolar (0.4-6.8) range of concentrations.

RESULTS

As expected, NVP-AEW541 inhibited IGF-II-mediated stimulation of IGF-IR and Akt. In addition to growth inhibition, the drug also induced apoptosis in vitro. Oral administration of NVP-AEW541 (50 mg/kg twice daily) inhibited tumor growth of neuroblastoma xenografts in nude mice. Analysis of tumors from the drug-treated animals revealed a marked apoptotic pattern and a decrease in microvascularization compared with controls. Interestingly, quantitative real-time PCR detected both in vitro and in vivo a significant down-regulation of mRNA for vascular endothelial growth factor (VEGF) caused by NVP-AEW541. In addition, in Matrigel-coated chambers and in severe combined immunodeficient mice tail vein injected with neuroblastoma cells, tumor invasiveness was significantly reduced by this agent. Analysis of IGF-IR expression in a series of 43 neuroblastoma primary tumors revealed IGF-IR positivity in 86% of cases.

CONCLUSIONS

Taken together, these data indicate that NVP-AEW541 can be considered as a novel promising candidate for treatment of neuroblastoma patients.

Estrogen receptor alpha-351 XbaI*G and -397 PvuII*C-related genotypes and alleles are associated with higher susceptibilities of endometriosis and leiomyoma

Endometriosis and leiomyoma are both common estrogen-related gynaecological diseases. We aimed to elucidate the association of estrogen receptor alpha (ERalpha)-351 A>G (XbaI) and -397 T>C (PvuII) gene polymorphisms with endometriosis and leiomyoma. Women were divided into three groups: (i) severe endometriosis (n = 112), (ii) leiomyoma (n = 106) and (iii) normal controls (n = 110). Genomic DNA was obtained from peripheral leukocytes. ERalpha-351 A/G XbaI and -397 T/C PvuII polymorphisms were assayed by the method of PCR and restriction fragment length polymorphism (RFLP). Genotypes and allelic frequencies in each group were compared. The genotype/allele frequencies of ERalpha-351 and -397 polymorphisms in endometriosis or leiomyoma groups were different from those of normal controls. ERalpha mutant-related genotypes/alleles (-351G and -397C) presented higher percentages in the endometriosis/leiomyoma population compared with normal controls. Proportions of ERalpha-351 AA/AG/GG genotypes and A/G alleles in each group were (i) 26.8/57.1/16.1 and 55.4/44.6%; (ii) 19.8/52.8/27.4 and 46.2/53.8% and (iii) 33.6/64.6/1.8 and 65.9/34.1%. Proportions of ERalpha-397 TT/TC/CC genotypes and T/C alleles in each group were (i) 24.1/60.7/15.2 and 54.5/45.5%; (ii) 23.6/70.8/5.6 and 59/41% and (iii) 54.5/40/5.5 and 74.5/25.5%. We concluded that ERalpha-351 XbaI*G- and -397 PvuII*C-related genotypes/alleles were correlated with higher susceptibilities of endometriosis or leiomyoma, which might be associated with related pathogeneses.

Bim-dependent apoptosis follows IGFBP-5 down-regulation in neuroblastoma cells

The insulin-like growth factor (IGF) axis is frequently activated in neuroblastoma (NB) tumors and cell lines. We show that silencing endogenous expression of IGF Binding Protein-5 (IGFBP-5) in NB cells by using microRNA and siRNA causes mitochondrial apoptosis that is characterized by: (a) release of cytochrome C in the cytoplasm and activation of caspase 9; (b) Erk1 and Erk2 inhibition; and (c) upregulation of pro-apoptotic proteins Bim and Bax. Bim upregulation is caused, at least in part, by protein stabilization that may depend on inhibition of Erk1 and Erk2. Of interest, Bim knock-down by siRNA decreases apoptosis in IGFBP-5-interfered cells. Thus, inhibition of endogenously produced IGFBP-5 is associated with Bim-dependent apoptosis in NB cells.

cDNA microarray analysis of cancer associated gene expression profiles in malignant peripheral nerve sheath tumours

BACKGROUND

Malignant peripheral nerve sheath tumour (MPNST) is a highly aggressive malignancy that arises within peripheral nerves, and is associated with poor prognosis. Little is known about the underlying biology of MPNST, especially the mechanisms involved in cell proliferation, invasion, or escape from apoptosis.

AIMS

To identify genes differentially expressed in MPNST compared with benign tumours, such as neurofibromas and schwannomas, by means of cDNA microarray analysis.

METHODS

Six MPNST cases and five benign cases (three schwannomas and two neurofibromas) were analysed.

RESULTS

Six genes (keratin 18, survivin, tenascin C, adenosine deaminase, collagen type VIa3, and collagen type VIIa1) were significantly upregulated in MPNST, whereas one gene, insulin-like growth factor binding protein 6, was downregulated in MPNST. Survivin and tenascin C expression was validated by reverse transcription polymerase chain reaction. Immunohistochemistry confirmed upregulation of survivin in MPNST at the protein level in six of eight cases compared with benign tumours. Tenascin C was also expressed at the invasive front and tumorous stroma in all MPNST cases. MPNST cells expressed tenascin C in four of nine cases.

CONCLUSIONS

Survivin and tenascin C may be associated with the malignant potential of MPNST and could be considered as potential therapeutic targets.

The insulin-like growth factor system and its pleiotropic functions in brain

In recent years, much interest has been devoted to defining the role of the IGF system in the nervous system. The ubiquitous IGFs, their cell membrane receptors, and their carrier binding proteins, the IGFBPs, are expressed early in the development of the nervous system and are therefore considered to play a key role in these processes. In vitro studies have demonstrated that the IGF system promotes differentiation and proliferation and sustains survival, preventing apoptosis of neuronal and brain derived cells. Furthermore, studies of transgenic mice overexpressing components of the IGF system or mice with disruptions of the same genes have clearly shown that the IGF system plays a key role in vivo.

Silencing of endogenous IGFBP-5 by micro RNA interference affects proliferation, apoptosis and differentiation of neuroblastoma cells

Signal transduction through the IGF axis is implicated in proliferation, differentiation and survival during development and adult life. The IGF axis includes the IGF binding proteins (IGFBPs) that bind IGFs with high affinity and modulate their activity. In neuroblastoma (NB), a malignant childhood tumor, we found that IGFBP-5 is frequently expressed. Since NB is an IGF2-sensitive tumor, we investigated the relevance and the function of endogenous IGFBP-5 in LAN-5 and in SY5Y(N) cell lines transfected with micro and small interfering RNAs directed to IGFBP-5 mRNA. Cells in which IGFBP-5 expression was suppressed were growth-inhibited and more prone to apoptosis than the parental cell line and controls. Apoptosis was further enhanced by X-ray irradiation. The ability of these cells to undergo neuronal differentiation was impaired after IGFBP-5 inhibition but the effect was reversed by exposure to recombinant IGFBP-5. Together, these data demonstrate the importance of IGFBP-5 for NB cell functions and suggest that IGFBP-5 might serve as a novel therapeutic target in NB.

Androgen receptor trinucleotide polymorphism in leiomyoma

OBJECTIVE

Androgen receptor (AR) was detected in leiomyoma. AR gene has a polymorphic microsatellite encoding cytosine, adenine, and guanine (CAG) repeats. We aimed to investigate the association between the AR gene CAG repeats and leiomyoma.

METHODS

Women were divided into two groups: (1) leiomyoma (n = 159); (2) non- leiomyoma groups (n = 129). Their CAG repeats were detected by polymerase chain reaction. The CAG repeats ranged in length from 168 bp (9 CAG repeats, genotype A) to 234 bp (31 CAG repeats, genotype W). Distributions of CAG repeats in both groups were compared.

RESULTS

Genotype proportions of different CAG repeats for AR gene in both groups were significantly different. The genotype S (27 CAG repeats) is associated with higher susceptibility of leiomyoma. Distribution of CAG repeats in both groups appeared mono-peak distributions. Percentages of genotypes K-S (19-27 CAG repeats) in leiomyoma and non-leiomyoma groups were: (1) 5,11,19.5, 10.4, 12.9, 8.8, 7.5, 5.7, 4.4%; (2) 5.4, 14.3,16.7, 12.8, 12.4, 5.8, 9.3, 7,1.2%.

CONCLUSIONS

AR trinucleotide polymorphism is associated with leiomyoma susceptibility. The 27 CAG repeats is related with higher risk of leiomyoma.

T homozygote and allele of epidermal growth factor receptor 2073 gene polymorphism are associated with higher susceptibility to endometriosis and leiomyomas

Epidermal growth factor receptor (EGFR) is a regulator of angiogenesis and mediator of sex steroid-induced cell growth and differentiation. We observed that EGFR gene 2073*T-related genotypes and allele are associated with higher susceptibilities to endometriosis and leiomyoma.

Integrin expression regulates neuroblastoma attachment and migration

Neuroblastoma (NBL) is the most common malignant disease of infancy, and children with bone metastasis have a mortality rate greater than 90%. Two major classes of proteins, integrins and growth factors, regulate the metastatic process. We have previously shown that tumorigenic NBL cells express higher levels of the type I insulin-like growth factor receptor (IGF-IR) and that beta1 integrin expression is inversely proportional to tumorigenic potential in NBL. In the current study, we analyze the effect of beta1 integrin and IGF-IR on NBL cell attachment and migration. Nontumorigenic S-cells express high levels of beta1 integrin, whereas tumorigenic N-cells express little beta1 integrin. Alterations in beta1 integrin are due to regulation at the protein level, as translation is decreased in N-type cells. Moreover, inhibition of protein synthesis shows that beta1 integrin is degraded more slowly in S-type cells (SHEP) than in N-type cells (SH-SY5Y and IMR32). Inhibition of alpha5beta1 integrin prevents SHEP (but not SH-SY5Y or IMR32) cell attachment to fibronectin and increases SHEP cell migration. Increases in IGF-IR decrease beta1 integrin expression, and enhance SHEP cell migration, potentially through increased expression of alphavbeta3. These data suggest that specific classes of integrins in concert with IGF-IR regulate NBL attachment and migration.

PROGINS Alu sequence insertion is associated with hyperprolactinaemia but not leiomyoma susceptibility

OBJECTIVE

Leiomyoma and hyperprolactinaemia are both progesterone-dependent diseases. Hormone-related genes, such as the progesterone receptor (PGR), might be involved in their pathogenesis.

DESIGN AND MEASUREMENTS

Subjects were divided into three groups: (i) leiomyoma (n = 120); (ii) hyperprolactinaemia (n = 101); (iii) normal controls (n = 140). We investigated the Alu (306-bp DNA) insertion in intron G of the PGR gene in all individuals. PGR gene polymorphisms [T1 (wild-type); T2 (PROGINS, with Alu insertion)] were determined by PCR and electrophoresis. Genotype and allele frequencies of the PROGINS in each group were detected and compared.

RESULTS

We observed no significant difference of the PGR*T1/T2 genotypes and allele frequencies between leiomyoma and other two groups. The proportions of T1 homozygote/heterozygote/T2 homozygote in each group were (i) 90/8.3/1.7%; (ii) 84.2/9.9/5.9%; (iii) 92.9/6.4/0.7%. In contrast, a higher percentage of T2-related genotype and allele were noted in hyperprolactinaemic women compared to other two groups. The proportions of T1/T2 alleles in each group were: (i) 94.2/5.8%; (ii) 89.1/10.9%; (iii) 96.1/3.9%.

CONCLUSIONS

The PROGIN*T2-related genotype and allele are related to a higher susceptibility to hyperprolactinaemia. The PROGINS polymorphism is not associated with leiomyoma development.

Levels of PTEN protein modulate Akt phosphorylation on serine 473, but not on threonine 308, in IGF-II-overexpressing rhabdomyosarcomas cells

Constitutive activation of Akt has been found in many types of human cancer, and is believed to promote proliferation and increased cell survival thereby contributing to cancer progression. In this study, we examined Akt phosphorylation on Ser473 and Thr308 in seven IGF-II-overexpressing rhabdomyosarcomas (RMS) cells. All the RMS cell lines tested had high levels of Akt phosphorylation on Thr308, whereas three cell lines (Rh5, Rh18, and CTR) had a much lower level of Akt phosphorylation on Ser473. To determine whether the difference in Akt phosphorylation on Ser473, but not on Thr308, observed among cell lines is a cell-specific phenomenon or due to other factors, which possibly downregulate Akt phosphorylation, we examined expression of PTEN protein, which acts as a negative regulator of the PI3K/Akt signaling pathway through its ability to dephosphorylate phosphatidylinositol 3,4,5-triphosphate (PIP3). The levels of PTEN expression inversely correlate with Akt phosphorylation on Ser473, but not on Thr308. Consistent with this finding, transfection of wild-type PTEN into RMS and mouse myoblast C2C12 cells resulted in reduced Akt phosphorylation on Ser473, but not on Thr308. Our data suggest that Ser473 may be a key target residue for PTEN to modulate the effects of IGF-II on activating the PI3K/Akt pathway in RMS cells. A better understanding of the pathway in RMS will likely contribute to insights into the biology of the RMS tumorigenesis and hopefully lead to novel therapeutic options.

Prenatal exposure of rats to Ginkgo biloba extract (EGb 761) increases neuronal survival/growth and alters gene expression in the developing fetal hippocampus

Hippocampal neuron survival/growth and gene expression have been examined after prenatal (in utero) exposure of rats to EGb 761, a leaf extract of Ginkgo biloba. Oral administration of EGb 761 (100 or 300 mg/kg/day) to pregnant dams for 5 days increased the number of hippocampal neurons (maintained in culture) of their fetuses, indicating a neurotrophic effect of the extract. Using large-scale oligonucleotide microarrays containing over 8000 combined rat genes and expressed sequence tag clusters, it was shown that treatment of pregnant dams with EGb 761 (25, 50 or 100 mg/kg/day for 5 days) altered the expression of 187 genes in the hippocampi of male fetuses and 160 genes in those of female fetuses. Using gene-cluster analysis, these genes were grouped into 18 distinct clusters for males and 17 distinct clusters for females. Among these clusters, 35 genes shared a common expression pattern in male and female hippocampal development. Of these genes, the changes observed in insulin growth factor II, insulin growth factor binding protein 2, testosterone repressed prostate message-2, glutathione-dependent dehydroascorbate reductase, lipoprotein lipase, guanylate cyclase and DNA binding protein Brn-2 were confirmed by real-time quantitative polymerase chain reaction. These findings, which have provided the first genetic profile of the effects of EGb 761 on the developing rat hippocampus, increase our understanding of the molecular and genetic programs that are activated by the extract. These effects of EGb 761 may underlie its neuroprotective properties.

The role of insulin-like growth factor-II in cancer growth and progression evidenced by the use of ribozymes and prostate cancer progression models

Towards understanding the IGF system during cancer growth and progression, progressive prostate cancer models, such as SV40 large T antigen immortalized human prostate epithelial cells (P69, M2182, M2205, and M12) and LNCaP sublines (C4, C4-2, and C4-2B4), were used. IGF-II mRNA levels progressively increase as prostate cancer cells become more tumorigenic and metastatic, suggesting that IGF-II contributes in part to prostate cancer progression. The role of IGF-II in cancer cell growth was evaluated in LNCaP, PC3, and M12 prostate cancer cell lines and MCF-7 breast cancer cell line by ribozyme/antisense strategies which were previously shown to suppress endogenous IGF-II expression and cell growth in PC-3 cells [Xu et al., Endocrinol 140 (1999) 2134]. Retroviral mediated transient expression of IGF-II-specific ribozyme (RZ) caused extensive cell death. In stably cloned cell lines, both RZ and mutant ribozyme (MRZ) inhibited cancer cell growth, suggesting that antisense effects of MRZ may be sufficient for cell growth inhibition. These results confirm an important role of IGF-II in cancer cell growth and progression, and support further development of gene therapy targeting IGF-II.

Estrogen receptor thymine-adenine dinucleotide repeat polymorphism is associated with susceptibility to leiomyoma

OBJECTIVE

To evaluate the association between leiomyomas and estrogen receptor gene polymorphism.

DESIGN

Prospective study.

SETTING

Department of gynecology and genetics.

PATIENT(S)

Women with (n = 159) or without leiomyomas (n = 131).

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction was used to detect dinucleotide (thymine-adenine [TA]) repeat polymorphisms upstream of the estrogen receptor gene. Genotypes were classified as A through P according to the number of the TA repeats from 12 to 27. Distributions of TA repeat for estrogen receptor in both groups were compared.

RESULT(S)

Genotypes A to E were detected in 10.7%, 18.9%, 15.7%, 16.4%, and 4.4%, respectively, of women with leiomyomas and 4.2%, 9.5%, 20.6%, 19.1%, and 10.3% of women without leiomyomas. Women with genotypes A and B (12 or 13 TA repeats) have a higher risk for leiomyomas, and those with genotype E (16 TA repeats) have a lower risk.

CONCLUSION(S)

Estrogen receptor gene polymorphism probably contributes to the pathogenesis of leiomyoma and may predict the susceptibility to leiomyoma. The 12 and 13 TA repeats are associated with a higher risk of leiomyoma.

Insulin-like growth factor binding protein-6 inhibits neuroblastoma cell proliferation and tumour development

In neuroblastoma cells, survival and proliferation are dependent upon the insulin-like growth factor (IGF) system. IGFs actively participate in cell growth, whereas IGFBP-6, is associated with the arrest of growth. With a view to blocking IGF-II action, we produced recombinant human IGFBP-6 capable of binding IGFs with affinities between 1.23 and 6.36 x 10(9) M(-1). Ex vivo mitogenic activities were tested on two human neuroblastoma cell lines, in which 100 ng/ml IGFBP-6 completely abolished the effects of both endogenous and exogenous IGF-II. In vivo, nude mice previously injected with neuroblastoma cells were submitted to either 15 daily injections of 4-20 microg IGFBP-6 or implantation of mini-pumps diffusing 20-100 microg IGFBP-6 over 2 weeks. The result was an average 18% reduction in the incidence and development of tumours. Delivery of the IGFBP-6 via mini-pumps also delayed tumour appearance by 6-15 days. Our results therefore show the involvement of IGFBP-6 in neuroblastoma cell growth, both ex vivo in terms of proliferation and in vivo in terms of tumour development.

Effect of insulin-like growth factor II on protecting myoblast cells against cisplatin-induced apoptosis through p70 S6 kinase pathway

Insulin-like growth factor (IGF-II) is overexpressed in a variety of human tumors and has both mitogenic and antiapoptotic activity. Although the mechanisms of IGF-II-induced proliferation have been well studied, the mechanisms underlying its survival signaling have been less well characterized. In this report, we investigated the role of IGF-II on cisplatin-induced apoptosis. We found that IGF-II overexpression was associated with an increase in p70 ribosomal protein S6 kinase (p70 S6K). Cisplatin treatment of C2C12 mouse myoblasts led to cell death associated with an inhibition of p70 S6K activity. Endogenous or exogenous IGF-II addition to C2C12 cells caused protection to cisplatin-induced apoptosis. This protection was associated in both cases with an increase in p70 S6K basal activity as well as resistance to cisplatin-induced decreased activity. Blockade of p70 S6K activation by rapamycin abrogated the IGF-II-mediated protection of cells to cisplatin-induced apoptosis. Furthermore, treatment of IGF-II-overexpressing Rh30 and CTR rhabdomyosarcoma cells with rapamycin restored sensitivity to cisplatin-induced apoptosis. These data together suggest that IGF-II-associated protection to cisplatin-induced apoptosis is mediated through an activation of the p70 S6K pathway. Thus, inhibition of the p70 S6 pathway may enhance chemotherapy-induced apoptosis in the treatment of IGF-II-overexpressing tumors.

Expression of insulin-like growth factor-binding protein 5 in neuroblastoma cells is regulated at the transcriptional level by c-Myb and B-Myb via direct and indirect mechanisms

Neuroblastoma (NB), a malignant childhood tumor deriving from the embryonic neural crest, is sensitive to the growth-stimulating effects of insulin-like growth factors (IGFs). Aggressive cases of this disease often acquire autocrine loops of IGF production, but the mechanisms through which the different components of the IGF axis are regulated in tumor cells remain unclear. Upon conditional expression of c-Myb in a NB cell line, we detected up-regulation of IGF1, IGF1 receptor, and insulin-like growth factor-binding protein 5 (IGFBP-5) expression. Analysis of the IGFBP-5 promoter revealed two potential Myb binding sites at position -59 to -54 (M1) and -429 to -424 (M2) from the transcription start site; both sites were bound by c-Myb and B-Myb in vitro and in vivo. Reporter assays carried out using the proximal region of the human IGFBP-5 promoter demonstrated that c-Myb and B-Myb enhanced transcription. However, site-directed mutagenesis and deletion of the Myb binding sites coupled with reporter assays revealed that M2 but not M1 was important for Myb-dependent transactivation of the IGFBP-5 promoter. The double mutant M1/M2 was still transactivated by c-Myb, suggesting the existence of Myb binding-independent mechanisms of IGFBP-5 promoter regulation. A constitutively active AKT transactivated the IGFBP-5 promoter, whereas the phosphatidylinositol 3-kinase inhibitor LY294002 suppressed it. Moreover, the kinase dead dominant negative K179M AKT mutant was able to inhibit transcription from the M2 and M1/M2 IGFBP-5 mutant promoters. Deletion analysis of the IGFBP-5 promoter revealed that the AKT-responsive region lies between nucleotides -334 and -83. Together, these data suggest that the Myb binding-independent transactivation of the IGFBP-5 promoter was due to the activation of the phosphatidylinositol 3-kinase/AKT pathway likely mediated by IGF1 receptor-dependent signals. Finally, IGFBP-5 was able to modulate proliferation of NB cells in a manner dependent on its concentration and on the presence of IGFs.

Amino acid transport in a human neuroblastoma cell line is regulated by the type I insulin-like growth factor receptor

Insulin-like growth factor I (IGF-I) and IGF-II stimulate cancer cell proliferation via interaction with the type I IGF receptor (IGF-IR). We put forward the hypothesis that IGF-IR mediates cancer cell growth by regulating amino acid transport, both when sufficient nutrients are present and when key nutrients such as glutamine are in limited supply. We examined the effects of alphaIR3, the monoclonal antibody recognizing IGF-IR, on cell growth and amino acid transport across the cell membrane in a human neuroblastoma cell line, SK-N-SH. In the presence of alphaIR3 (2 micro/ml), cell proliferation was significantly attenuated in both control (2 mM glutamine) and glutamine-deprived (0 mM glutamine) groups. Glutamine deprivation resulted in significantly increased glutamate (system X(AG)(-)), MeAIB (system A), and leucine (system L) transport, which was blocked by alphaIR3. Glutamine (system ASC) and MeAIB transport was significantly decreased by alphaIR3 in the control group. Addition of alphaIR3 significantly decreased DNA and protein biosynthesis in both groups. Glutamine deprivation increased the IGF-IR protein on the cell surface. Our results suggest that activation of IGF-IR promotes neuroblastoma cell proliferation by regulating trans-membrane amino acid transport.

Extensive neuronal localization and neurotrophic function of fibroblast growth factor 8 in the nervous system

Fibroblast growth factor (FGF) 8 has been well established to play a critical role in the early development of the central nervous system (CNS). We report here extensive neuronal localization and neurotrophic function of FGF8 in the nervous system. In sections of mouse embryos at E10.5, FGF8 was immunohistochemically found in neurons at the marginal zones of the CNS and in the dorsal root ganglia (DRG). Neuronal localization of FGF8 was marked at later embryonic stages and in adults, involving most of the central and peripheral neurons, including intermuscular enteric neurons, DRGs, and paraaortic sympathetic ganglia. Functionally, FGF8 promoted neurite outgrowth in human neuroblastoma SK-N-MC cells as well as in rat pheochromocytoma PC12 cells, suggesting that FGF8 acts as a neurotrophic factor. FGF8 also supported neuronal survival and differentiation in cultured human neural progenitor cells. In a cell growth assay, treatment with 50 ng/ml FGF8 on human cultured neuroblastoma SK-N-MC and IMR32 cells attenuated the growth of both. In accordance with these in vitro findings, the immunohistochemical analysis on human neurological diseases showed that FGF8 expression is evident in differentiating histological types of neuroblastoma and ganglioneuroblastoma, and that the levels of FGF8 immunoreactivity in the substantia nigra from Parkinson's disease are significantly lower than those in age-matched controls. Taken together, the present findings strongly suggest that FGF8 acts as a more generalized neurotrophic factor than previously reported.