Insulin-Like Growth Factor-I Receptor Expression Regulates Neuroblastoma Metastasis to Bone

Insulin-like growth factor family and prostate cancer: new insights and emerging opportunities

Prostate cancer is the second most commonly diagnosed cancer in men. The mammalian insulin-like growth factor (IGF) family is made up of three ligands (IGF-I, IGF-II, and insulin), three receptors (IGF-I receptor (IGF-1R), insulin receptor (IR), and IGF-II receptor (IGF-2R)), and six IGF-binding proteins (IGFBPs). IGF-I and IGF-II were identified as potent mitogens and were previously associated with an increased risk of cancer development including prostate cancer. Several reports showed controversy about the expression of the IGF family and their connection to prostate cancer risk due to the high degree of heterogeneity among prostate tumors, sampling bias, and evaluation techniques. Despite that, it is clear that several IGF family members play a role in prostate cancer development, metastasis, and androgen-independent progression. In this review, we aim to expand our understanding of prostate tumorigenesis and regulation through the IGF system. Further understanding of the role of IGF signaling in PCa shows promise and needs to be considered in the context of a comprehensive treatment strategy.

Guidelines for outpatient administration of naxitamab: Experience from Atrium Health Levine Children's Hospital

AIM

In this publication, we will share our experience of AE management, provide guidance for appropriate staffing, and the discuss the importance of patient education when treating patients with R/R HR neuroblastoma using naxitamab.

BACKGROUND

Approved treatments for patients with refractory and/or relapsed (R/R) high-risk (HR) neuroblastoma are limited, and there is a high unmet need for new treatment combinations. Naxitamab is a disialoganglioside 2 (GD2)-binding antibody that was approved by the United States Food and Drug Administration in 2020 for use in combination with granulocyte-macrophage colony-stimulating factor for the treatment of patients with R/R HR neuroblastoma in the bone and/or bone marrow and who have demonstrated a partial response, minor response, or stable disease with prior therapy.

METHODS

The pediatric oncology team at Atrium Health Levine Children's Hospital has successfully treated several patients with naxitamab both alone and in combination with chemotherapy, with no patients requiring unplanned overnight hospitalization and few severe adverse events (AEs). To accomplish this, the team at Levine Children's Hospital established standard operating procedures for naxitamab, a therapy defined as high acuity due to the potential for acute AEs with rapid onset and that benefits from continuous monitoring by a nursing team and a dedicated provider.

CONCLUSIONS

This will provide a practical guide for institutions offering naxitamab to their patients, and ensure successful administration of this high acuity treatment in the outpatient setting.

The role of surgery in the treatment of neuroblastoma metastases at rare sites

PURPOSE

Treatment of neuroblastoma metastases usually consists of chemotherapy and irradiation. However, in selected cases, surgical treatment is also indicated. In this study, we present three cases of patients with neuroblastoma metastases at rare sites that underwent surgery.

MATERIALS AND METHODS

We retrospectively analyzed data of patients who underwent surgery for neuroblastoma at our department of Pediatric Surgery and Pediatric Urology at the University Children's Hospital in Tuebingen and selected those patients who had surgery explicitly for a metastasis.

RESULTS

Between 2002 and 2020, 277 children underwent surgical treatment for neuroblastoma. Three cases with metastases at exceptional sites are presented here after therapy according to protocols. One patient had a penile metastasis and received surgery including a plastic reconstruction. The patient showed no signs of erectile or urinary dysfunction at follow-up. Another patient had a metastasis in the proximal ulna, which remained vital even after exhausted treatment after two relapses. Afterward there was no restriction of movement of the extremity. The third patient had, amongst others, metastases to the pancreatic body and to the liver. Both were surgically removed during primary tumor resection. This patient died after local tumor relapse. The other two patients showed no evidence of tumor relapse after a follow-up of 18 and 17 months, respectively.

CONCLUSION

Although children with neuroblastoma often present with metastases, there is no recommendation for surgical treatment other than diagnostic biopsies. In case of persistence of metastasis or after exhaustion of high-risk therapy, surgical resection must be considered.

Engineering human mini-bones for the standardized modeling of healthy hematopoiesis, leukemia, and solid tumor metastasis

The bone marrow microenvironment provides indispensable factors to sustain blood production throughout life. It is also a hotspot for the progression of hematologic disorders and the most frequent site of solid tumor metastasis. Preclinical research relies on xenograft mouse models, but these models preclude the human-specific functional interactions of stem cells with their bone marrow microenvironment. Instead, human mesenchymal cells can be exploited for the in vivo engineering of humanized niches, which confer robust engraftment of human healthy and malignant blood samples. However, mesenchymal cells are associated with major reproducibility issues in tissue formation. Here, we report the fast and standardized generation of human mini-bones by a custom-designed human mesenchymal cell line. These resulting humanized ossicles (hOss) consist of fully mature bone and bone marrow structures hosting a human mesenchymal niche with retained stem cell properties. As compared to mouse bones, we demonstrate superior engraftment of human cord blood hematopoietic cells and primary acute myeloid leukemia samples and also validate hOss as a metastatic site for breast cancer cells. We further report the engraftment of neuroblastoma patient-derived xenograft cells in a humanized model, recapitulating clinically described osteolytic lesions. Collectively, our human mini-bones constitute a powerful preclinical platform to model bone-developing tumors using patient-derived materials.

How we approach the treatment of patients with high-risk neuroblastoma with naxitamab: experience from the Hospital Sant Joan de Déu in Barcelona, Spain

Naxitamab [humanized 3f8 (hu3F8)] is a humanized monoclonal antibody (mAb) targeting the disialoganglioside GD2. It was approved in 2020 by the United States Food and Drug Administration (FDA) in combination with granulocyte–macrophage colony-stimulating factor (GM-CSF) for treatment of pediatric and adult patients with relapsed/refractory high-risk neuroblastoma, limited to the bone or bone marrow (BM). The team at Sant Joan de Déu Children’s Hospital in Barcelona, Spain, have been using naxitamab to treat neuroblastoma under clinical trial protocols [e.g. Trial 201, and hu3F8, irinotecan, temozolomide, and sargramostim (GM-CSF) (HITS) study] and compassionate use since 2017. The team has experience with two primary regimens: naxitamab with GM-CSF only, or naxitamab in combination with irinotecan, temozolomide, and GM-CSF (chemoimmunotherapy). This article aims to provide a practical overview of the team’s experience with naxitamab to date, including preparing the treatment room and selecting the team. Adverse event management, including the use of ketamine to manage pain during anti-GD2 mAb infusions, is also discussed. We hope this will provide practical information for other health care providers considering offering this treatment.

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Immunotherapy with anti-GD2 antibodies has revolutionized the treatment of patients with high-risk neuroblastoma.

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In 2020, FDA approved naxitamab + GM-CSF for treatment of patients with R/R neuroblastoma in the bone and/or BM.

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Outpatient treatment with naxitamab-based immunotherapy may improve health-related quality of life.

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Naxitamab infusions require specific training and teamwork to prevent and efficiently manage most frequent adverse events.

Systematic review of the receptor tyrosine kinase superfamily in neuroblastoma pathophysiology

BACKGROUND

Neuroblastoma is a devastating disease accounting for 15% of all childhood cancer deaths. Yet, our understanding of key molecular drivers such as receptor tyrosine kinases (RTKs) in this pathology remains poorly clarified. Here, we provide a systematic analysis of the RTK superfamily in the context of neuroblastoma pathogenesis.

METHODS

Statistical correlations for all RTK family members' expression to neuroblastoma patient survival across 10 independent patient cohorts were annotated, synthesized, and ranked using the R2: Genomics Analysis and Visualization Platform. Gene expression of selected members across different cancer cell lines was further analyzed in the Cancer Cell Line Encyclopedia, part of the Cancer Dependency Map portal (depmap portal ( http://depmap.org )). Finally, we provide a detailed literature review for highly ranked candidates.

RESULTS

Our analysis defined two subsets of RTKs showing robust associations with either better or worse survival, constituting potential novel players in neuroblastoma pathophysiology, diagnosis, and therapy. We review the available literature regarding the oncogenic functions of these RTKs, their roles in neuroblastoma pathophysiology, and potential utility as therapeutic targets.

CONCLUSIONS

Our systematic analysis and review of the RTK superfamily in neuroblastoma pathogenesis provides a new resource to guide the research community towards focused efforts investigating signaling pathways that contribute to neuroblastoma tumor establishment, growth, and/or aggressiveness and targeting these druggable molecules in novel therapeutic strategies.

Connecting the Dots Between the Gut-IGF-1-Prostate Axis: A Role of IGF-1 in Prostate Carcinogenesis

Prostate cancer (PCa) is the most common malignancy in men worldwide, thus developing effective prevention strategies remain a critical challenge. Insulin-like growth factor 1 (IGF-1) is produced mainly in the liver by growth hormone signaling and is necessary for normal physical growth. However, several studies have shown an association between increased levels of circulating IGF-1 and the risk of developing solid malignancies, including PCa. Because the IGF-1 receptor is overexpressed in PCa, IGF-1 can accelerate PCa growth by activating phosphoinositide 3-kinase and mitogen-activated protein kinase, or increasing sex hormone sensitivity. Short-chain fatty acids (SCFAs) are beneficial gut microbial metabolites, mainly because of their anti-inflammatory effects. However, we have demonstrated that gut microbiota-derived SCFAs increase the production of IGF-1 in the liver and prostate. This promotes the progression of PCa by the activation of IGF-1 receptor downstream signaling. In addition, the relative abundance of SCFA-producing bacteria, such as Alistipes, are increased in gut microbiomes of patients with high-grade PCa. IGF-1 production is therefore affected by the gut microbiome, dietary habits, and genetic background, and may play a central role in prostate carcinogenesis. The pro-tumor effects of bacteria and diet-derived metabolites might be potentially countered through dietary regimens and supplements. The specific diets or supplements that are effective are unclear. Further research into the "Gut-IGF-1-Prostate Axis" may help discover optimal diets and nutritional supplements that could be implemented for prevention of PCa.

m6 A modification of lncRNA PCAT6 promotes bone metastasis in prostate cancer through IGF2BP2-mediated IGF1R mRNA stabilization

BACKGROUND

Bone metastasis is the leading cause of tumor-related death in prostate cancer (PCa) patients. Long noncoding RNAs (lncRNAs) have been well documented to be involved in the progression of multiple cancers. Nevertheless, the role of lncRNAs in PCa bone metastasis remains largely unclear.

METHODS

The expression of prostate cancer-associated transcripts was analyzed in published datasets and further verified in clinical samples and cell lines by RT-qPCR and in situ hybridization assays. Colony formation assay, MTT assay, cell cycle analysis, EdU assay, Transwell migration and invasion assays, wound healing assay, and in vivo experiments were carried out to investigate the function of prostate cancer-associated transcript 6 (PCAT6) in bone metastasis and tumor growth of PCa. Bioinformatic analysis, RNA pull-down, and RIP assays were conducted to identify the proteins binding to PCAT6 and the potential targets of PCAT6. The therapeutic potential of targeting PCAT6 by antisense oligonucleotides (ASO) was further explored in vivo.

RESULTS

PCAT6 was upregulated in PCa tissues with bone metastasis and increased PCAT6 expression predicted poor prognosis in PCa patients. Functional experiments found that PCAT6 knockdown significantly inhibited PCa cell invasion, migration, and proliferation in vitro, as well as bone metastasis and tumor growth in vivo. Mechanistically, METTL3-mediated m6 A modification contributed to PCAT6 upregulation in an IGF2BP2-dependent manner. Furthermore, PCAT6 upregulated IGF1R expression by enhancing IGF1R mRNA stability through the PCAT6/IGF2BP2/IGF1R RNA-protein three-dimensional complex. Importantly, PCAT6 inhibition by ASO in vivo showed therapeutic potential against bone metastasis in PCa. Finally, the clinical correlation of METTL3, IGF2BP2, IGF1R, and PCAT6 was further demonstrated in PCa tissues and cells.

CONCLUSIONS

Our study uncovers a novel molecular mechanism by which the m6 A-induced PCAT6/IGF2BP2/IGF1R axis promotes PCa bone metastasis and tumor growth, suggesting that PCAT6 may serve as a promising prognostic marker and therapeutic target against bone-metastatic PCa.

Mesenchymal Stromal Cells in Neuroblastoma: Exploring Crosstalk and Therapeutic Implications

Neuroblastoma (NB) is the second most common solid cancer in childhood, accounting for 15% of cancer-related deaths in children. In high-risk NB patients, the majority suffers from metastasis. Despite intensive multimodal treatment, long-term survival remains <40%. The bone marrow (BM) is among the most common sites of distant metastasis in patients with high-risk NB. In this environment, small populations of tumor cells can persist after treatment (minimal residual disease) and induce relapse. Therapy resistance of these residual tumor cells in BM remains a major obstacle for the cure of NB. A detailed understanding of the microenvironment and its role in tumor progression is of utmost importance for improving the treatment efficiency of NB. In BM, mesenchymal stromal cells (MSCs) constitute an important part of the microenvironment, where they support hematopoiesis and modulate immune responses. Their role in tumor progression is not completely understood, especially for NB. Although MSCs have been found to promote epithelial-mesenchymal transition, tumor growth, and metastasis and to induce chemoresistance, some reports point toward a tumor-suppressive effect of MSCs. In this review, we aim to compile current knowledge about the role of MSCs in NB development and progression. We evaluate arguments that depict tumor-supportive versus -suppressive properties of MSCs in the context of NB and give an overview of factors involved in MSC-NB crosstalk. A focus lies on the BM as a metastatic niche, since that is the predominant site for NB metastasis and relapse. Finally, we will present opportunities and challenges for therapeutic targeting of MSCs in the BM microenvironment.

Preclinical models for neuroblastoma: Advances and challenges

Neuroblastoma is a paediatric cancer of the sympathetic nervous system and the most common solid tumour of infancy, contributing to 15% of paediatric oncology deaths. Current therapies are not effective in the long-term treatment of almost 80% of patients with this clinically aggressive disease. The primary challenge in the identification and validation of new agents for paediatric drug development is the accurate representation of tumour biology and diversity. In addition to this limitation, the low incidence of neuroblastoma makes the recruitment of eligible patients for early phase clinical trials highly challenging and highlights the need for robust preclinical testing to ensure that the best treatments are selected. The research field requires new preclinical models, technologies, and concepts to tackle these problems. Tissue engineering offers attractive tools to assist in the development of three-dimensional (3D) cell models using various biomaterials and manufacturing approaches that recreate the geometry, mechanics, heterogeneity, metabolic gradients, and cell communication of the native tumour microenvironment. In this review, we discuss current experimental models and assess their abilities to reflect the structural organisation and physiological conditions of the human body, in addition to current and new techniques to recapitulate the tumour niche using tissue-engineered platforms. Finally, we will discuss the possible use of novel 3D in vitro culture systems to address open questions in neuroblastoma biology.

Downregulation of CDKL1 suppresses neuroblastoma cell proliferation, migration and invasion

Background

Cyclin-dependent kinase-like 1 (CDKL1) is a member of the cell division control protein 2-related serine–threonine protein kinase family. It is known to occur in various malignant tumors, but its role in neuroblastoma (NB) remains unclear.

Methods

We constructed a CDKL1-silenced NB cell strain (SH-SY5Y) and used real-time PCR and western blotting to confirm the silencing. Functional analyses were performed using the MTT, colony-formation, FACS, wound-healing and transwell invasion assays.

Results

The expression of CDKL1 was significantly upregulated in NB tissue as compared to the adjacent normal tissue. CDKL1 knockdown significantly suppressed cell viability and colony formation ability. It also induced cell cycle G0/G1 phase arrest and apoptosis, and suppressed the migration and invasion ability of SH-SY5Y cells. CDKL1 knockdown decreased the CDK4, cyclin D1 and vimentin expression levels, and increased the caspase-3, PARP and E-cadherin expression levels in SH-SY5Y cells.

Conclusions

Our findings suggest that CDKL1 plays an important role in NB cell proliferation, migration and invasion. It might serve as a potential target for NB therapy.

Bone metastasis: Interaction between cancer cells and bone microenvironment

BACKGROUND

Bone is one of the most common target organs for cancer metastasis, especially in patients with advanced breast and prostate cancers. Despite recent advances in therapeutic approaches, bone metastases remain incurable and produce multiple complications called skeletal-related events, including hypercalcemia, pathological fractures, spinal compression, and bone pain, which are associated with poor prognosis.

HIGHLIGHT

Although the precise mechanisms are yet to be fully elucidated, accumulating evidence suggests that bone provides a favorable microenvironment that enables circulating cancer cells to home, proliferate, and colonize, resulting in the formation of metastasis. Cancer cells that metastasize to bone also possess unique features, enabling them to utilize the bone microenvironment. Thus, communication between cancer cells and bone is believed to be critical for the development and progression of bone metastases.

CONCLUSION

Continued studies are warranted to understand the molecular mechanisms underlying bone metastases and to develop mechanism-based and effective therapeutic interventions.

Bad to the Bone: The Role of the Insulin-Like Growth Factor Axis in Osseous Metastasis

Bone metastases are a frequent complication of cancer that are associated with considerable morbidity. Current treatments may temporarily palliate the symptoms of bone metastases but often fail to delay their progression. Bones provide a permissive environment because they are characterized by dynamic turnover, secreting factors required for bone maintenance but also stimulating the establishment and growth of metastases. Insulin-like growth factors (IGF) are the most abundant growth factors in bone and are required for normal skeletal development and function. Via activation of the IGF-1 receptors (IGF-1R) and variant insulin receptors, IGFs promote cancer progression, aggressiveness, and treatment resistance. Of specific relevance to bone biology, IGFs contribute to the homing, dormancy, colonization, and expansion of bone metastases. Furthermore, preclinical evidence suggests that tumor cells can be primed to metastasize to bone by a high IGF-1 environment in the primary tumor, suggesting that bone metastases may reflect IGF dependency. Therapeutic targeting of the IGF axis may therefore provide an effective method for treating bone metastases. Indeed, anti-IGF-1R antibodies, IGF-1R tyrosine kinase inhibitors, and anti-IGF-1/2 antibodies have demonstrated antitumor activity in preclinical models of prostate and breast cancer metastases, either alone or in combination with other agents. Several studies suggest that such treatments can inhibit bone metastases without affecting growth of the primary tumor. Although previous trials of anti-IGF-1R drugs have generated negative results in unselected patients, these considerations suggest that future clinical trials of IGF-targeted agents may be warranted in patients with bone metastases.

Suppression of IGF1R in Melanoma Cells by an Adenovirus-Mediated One-Step Knockdown System

Abnormal activation of the IGF1R signaling pathway accelerates melanoma development and metastases. RNAi systems with complex cloning procedures and unsatisfactory efficiency in suppressing gene expression have become the technical difficulties that hinder their utility when studying gene knockdown. Here we established a simplified adenovirus-mediated gene knockdown system by which a single adenoviral vector carries multiple siRNA fragments that can effectively suppress IGF1R expression in melanoma cells. We first generated the adenovirus that simultaneously expresses three human or mouse siRNAs targeting IGF1R (AdRIGF1R-OK). qRT-PCR and immunofluorescence staining revealed that IGF1R expression was significantly decreased in the melanoma cells that were infected with AdRIGF1R-OK. Bioluminescence imaging showed that the size of the tumor formed by the xenografts infected with AdRIGF1R-OK was significantly smaller than that of the controls. Annexin V-FITC flow cytometry assay, immunofluorescence staining for cleaved caspase-3, and Hoechst staining showed that more cells underwent apoptosis after infection with AdRIGF1R-OK. Luciferase reporter assay, crystal violet cell viability assay, and cell-cycle analysis showed that the proliferation of melanoma cells infected with AdRIGF1R-OK was significantly decreased compared to the controls. This study demonstrates that the OK system is effective in silencing gene expression, with promising potential to treat melanoma and other diseases.

Bone turnover markers and novel biomarkers in lung cancer bone metastases

CONTEXT

Lung cancer still remains the leading cause of cancer-related mortality worldwide. Bone is one of preferred metastatic sites for lung cancer cells. So far, both accurate diagnosis and effective treatment of lung cancer bone metastases are difficult.

OBJECTIVE

This review aimed to evaluate roles of bone turnover markers (BTMs), microRNAs (miRNAs), dickkopf1 (DKK1) and insulin like growth factor binding protein 3 (IGFBP-3) in lung cancer bone metastases.

METHODS

We searched articles about these four biomarkers in lung cancer bone metastases mainly in PubMed.

RESULT

The levels of bone specific alkaline phosphatase (BALP), cross-linked carboxy-terminal telopeptide of type-I collagen (ICTP) and N-terminal telopeptides of type-I collagen (NTX) were reported to be significantly increased in lung cancer patients with bone metastases. ALP, NTX and bone sialoprotein were thought to be associated with prognosis of lung cancer patients with bone metastases. MiRNA-335, miRNA-33a, miRNA-21, DKK1 and IGFBP-3 were revealed to be novel biomarkers in lung cancer bone metastases.

DISCUSSION AND CONCLUSION

Current researches have revealed that BTMs, miRNAs, DKK1 and IGFBP-3 may be useful in diagnosis, prognosis evaluation or treatment of lung cancer bone metastases. More studies about these biomarkers in lung cancer bone metastases are needed.

IGF-IEc expression is increased in secondary compared to primary foci in neuroendocrine neoplasms

Different Insulin-like growth factor-I (IGF-I) mRNA transcripts are produced by alternative splicing and particularly the IGF-IEc isoform has been implicated in the development and/or progression of various types of cancer. In the present study, we examined the potential role of IGF-IEc expression as a new immunohistochemical marker of aggressiveness in neuroendocrine neoplasms (NENs). We utilized immunohistochemical analysis in tissue specimens of 47 patients with NENs, to evaluate the expression of IGF-IEc (%) and Ki-67 proliferation index (%). Specimens from patients with tumors of different tissue origin, of either primary or metastatic lesions and of different grade were examined. Cytoplasmic IGF-IEc staining was found in 23 specimens of NENs or NECs: 10 pancreatic, 4 small bowel, 3 gastric, 1 lung, 1 uterine and 4 poorly differentiated of unknown primary origin. Ki-67 and IGF-IEc expression was positively correlated in all the samples studied (r=0.31, p=0.03). IGF-1Ec expression was more prevalent in specimens originating from metastatic foci with high Ki-67 compared to primary sites with low Ki-67 expression (p=0.036). These findings suggest a possible role of IGF-IEc in NEN tumorigenesis and progression to metastases that could be used as an additional new marker of a more aggressive behavior and a potential drugable target.

Replacement of quaternary ammonium headgroups by tri-ornithine in cationic lipids for the improvement of gene delivery in vitro and in vivo

Replacement of quaternary ammonium headgroups by tri-ornithine in lipids improved gene delivery in vitro and in vivo with little toxicity.

More than the genes, the tumor microenvironment in neuroblastoma

Neuroblastoma is the second most common solid tumor in children. Since the seminal discovery of the role of amplification of the MYCN oncogene in the pathogenesis of neuroblastoma in the 1980s, much focus has been on the contribution of genetic alterations in the progression of this cancer. However it is now clear that not only genetic events play a role but that the tumor microenvironment (TME) substantially contributes to the biology of neuroblastoma. In this article, we present a comprehensive review of the literature on the contribution of the TME to the ten hallmarks of cancer in neuroblastoma and discuss the mechanisms of communication between neuroblastoma cells and the TME that underlie the influence of the TME on neuroblastoma progression. We end our review by discussing how the knowledge acquired over the last two decades in this field is now leading to new clinical trials targeting the TME.

The role of mechano-growth factor E peptide in the regulation of osteosarcoma

Osteosarcoma is one of the most common bone tumors, and exhibits a high degree of malignancy. Gene therapy is a novel approach to its treatment, however, specific target genes are required to enable effective use of this therapy. In order to investigate the effects of the mechano-growth factor E (MGF-E) peptide, which is derived from the IGF-I alternative splicing isoform, on the regulation of the development of osteosarcoma, the expression of MGF was detected in osteosarcoma cell lines with different degrees of malignancy. Concomitantly, exogenous MGF-E peptide was used to stimulate these osteosarcoma cell lines. The results demonstrated that MGF was overexpressed in malignant osteosarcoma cells, while it was not expressed in the least malignant osteosarcoma cells. Furthermore, MGF-E treatment altered the cell cycle distribution, and promoted the proliferation, migration and invasion of osteosarcoma cells. The possible mechanisms underlying these effects were detected by quantitative polymerase chain reaction and western blotting. Based on these results, it was hypothesized that MGF may be a suitable biomarker for malignant osteosarcoma phenotypes.

A dual-specific anti-IGF-1/IGF-2 human monoclonal antibody alone and in combination with temsirolimus for therapy of neuroblastoma

The insulin-like growth factors (IGFs), IGF-1 and IGF-2, have been implicated in the growth, survival and metastasis of a broad range of malignancies including pediatric tumors. They bind to the IGF receptor type 1 (IGF-1R) and the insulin receptor (IR) which are overexpressed in many types of solid malignancies. Activation of the IR by IGF-2 results in increased survival of tumor cells. We have previously identified a novel human monoclonal antibody, m708.5, which binds with high (pM) affinity to both human IGF-1 and IGF-2, and potently inhibits phosphorylation of the IGF-1R and the IR in tumor cells. m708.5 exhibited strong antitumor activity as a single agent against most cell lines derived from neuroblastoma, Ewing family of tumor, rhabdomyosarcoma and osteosarcoma. When tested in neuroblastoma cell lines, it showed strong synergy with temsirolimus and synergy with chemotherapeutic agents in vitro. In xenograft models, the combination of m708.5 and temsirolimus significantly inhibited neuroblastoma growth and prolonged mouse survival. Taken together, these results support the clinical development of m708.5 for pediatric solid tumors with potential for synergy with chemotherapy and mTOR inhibitors.

Mesenchymal stromal cell secretome up-regulates 47 kDa CXCR4 expression, and induce invasiveness in neuroblastoma cell lines

Neuroblastoma accounts for 15% of childhood cancer deaths and presents with metastatic disease of the bone and the bone marrow at diagnosis in 70% of the cases. Previous studies have shown that the Mesenchymal Stromal Cell (MSC) secretome, triggers metastases in several cancer types such as breast and prostate cancer, but the specific role of the MSC factors in neuroblastoma metastasis is unclear. To better understand the effect of MSC secretome on chemokine receptors in neuroblastoma, and its role in metastasis, we studied a panel of 20 neuroblastoma cell lines, and compared their invasive potential towards MSC-conditioned-RPMI (mRPMI) and their cytokine receptor expression profiles. Western blot analysis revealed the expression of multiple CXCR4 isoforms in neuroblastoma cells. Among the five major isoforms, the expression of the 47 kDa isoform showed significant correlation with high invasiveness. Pretreatment with mRPMI up-regulated the expression of the 47 kDa CXCR4 isoform and also increased MMP-9 secretion, expression of integrin α3 and integrin β1, and the invasive potential of the cell; while blocking CXCR4 either with AMD 3100, a CXCR4 antagonist, or with an anti-47 kDa CXCR4 neutralizing antibody decreased the secretion of MMP-9, the expression of integrin α3 and integrin β1, and the invasive potential of the cell. Pretreatment with mRPMI also protected the 47 kDa CXCR4 isoform from ubiquitination and subsequent degradation. Our data suggest a modulatory role of the MSC secretome on the expression of the 47 kDa CXCR4 isoform and invasion potential of the neuroblastoma cells to the bone marrow.

GALNT2 suppresses malignant phenotypes through IGF-1 receptor and predicts favorable prognosis in neuroblastoma

Aberrant expression of the simple mucin-type carbohydrate antigens such as Tn antigen is associated with malignant transformation and cancer progression. N-acetylgalactosaminyltransferase 2 (GALNT2), one of the enzymes that mediate the initial step of mucin-type O-glycosylation, is responsible for forming Tn antigen. GALNT2 is expressed differentially in nervous tissues during mouse embryogenesis; however, the role of GALNT2 in neuroblastoma (NB) remains unclear. Here we showed that increased GALNT2 expression evaluated using immunohistochemistry in NB tumor tissues correlated well with the histological grade of differentiation as well as younger age at diagnosis, early clinical stage, primary tumor originated from the extra-adrenal site, favorable INPC histology, and MYCN non-amplification. Multivariate analysis showed that GALNT2 expression is an independent prognostic factor for better survival for NB patients. GALNT2 overexpression suppressed IGF-1-induced cell growth, migration, and invasion of NB cells, whereas GALNT2 knockdown enhanced these NB phenotypes. Mechanistic investigations demonstrated that GALNT2 overexpression modified O-glycans on IGF-1R, which suppressed IGF-1-triggered IGF-1R dimerization and subsequent downstream signaling events. Conversely, these properties were reversed by GALNT2 knockdown in NB cells. Our findings suggest that GALNT2 regulates malignant phenotypes of NB cells through the IGF-1R signaling pathway, suggesting a critical role for GALNT2 in the pathogenesis of NB.

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.

The SK-N-AS human neuroblastoma cell line develops osteolytic bone metastases with increased angiogenesis and COX-2 expression

Neuroblastoma (NB), which arises from embryonic neural crest cells, is the most common extra-cranial solid tumor of childhood. Approximately half of NB patients manifest bone metastasis accompanied with bone pain, fractures and bone marrow failure, leading to disturbed quality of life and poor survival. To study the mechanism of bone metastasis of NB, we established an animal model in which intracardiac inoculation of the SK-N-AS human NB cells in nude mice developed osteolytic bone metastases with increased osteoclastogenesis. SK-N-AS cells induced the expression of receptor activator of NF-κB ligand and osteoclastogenesis in mouse bone marrow cells in the co-culture. SK-N-AS cells expressed COX-2 mRNA and produced substantial amounts of prostaglandin E₂ (PGE₂). In contrast, the SK-N-DZ and SK-N-FI human NB cells failed to develop bone metastases, induce osteoclastogenesis, express COX-2 mRNA and produce PGE₂. Immunohistochemical examination of SK-N-AS bone metastasis and subcutaneous tumor showed strong expression of COX-2. The selective COX-2 inhibitor NS-398 inhibited PGE₂ production and suppressed bone metastases with reduced osteoclastogenesis. NS-398 also inhibited subcutaneous SK-N-AS tumor development with decreased angiogenesis and vascular endothelial growth factor-A expression. Of interest, metastasis to the adrenal gland, a preferential site for NB development, was also diminished by NS-398. Our results suggest that COX2/PGE₂ axis plays a critical role in the pathophysiology of osteolytic bone metastases and tumor development of the SK-NS-AS human NB. Inhibition of angiogenesis by suppressing COX-2/PGE₂ may be an effective therapeutic approach for children with NB.

Intermittent hypoxia effect on osteoclastogenesis stimulated by neuroblastoma cells

Background

Neuroblastoma is the most common extracranial pediatric solid tumor. Intermittent hypoxia, which is characterized by cyclic periods of hypoxia and reoxygenation, has been shown to positively modulate tumor development and thereby induce tumor growth, angiogenic processes, and metastasis. Bone is one of the target organs of metastasis in advanced neuroblastoma Neuroblastoma cells produce osteoclast-activating factors that increase bone resorption by the osteoclasts. The present study focuses on how intermittent hypoxia preconditioned SH-SY5Y neuroblastoma cells modulate osteoclastogenesis in RAW 264.7 cells compared with neuroblastoma cells grown at normoxic conditions.

Methods

We inhibited HIF-1α and HIF-2α in neuroblastoma SH-SY5Y cells by siRNA/shRNA approaches. Protein expression of HIF-1α, HIF-2α and MAPKs were investigated by western blotting. Expression of osteoclastogenic factors were determined by real-time RT-PCR. The influence of intermittent hypoxia and HIF-1α siRNA on migration of neuroblastoma cells and in vitro differentiation of RAW 264.7 cells were assessed. Intratibial injection was performed with SH-SY5Y stable luciferase-expressing cells and in vivo bioluminescence imaging was used in the analysis of tumor growth in bone.

Results

Upregulation of mRNAs of osteoclastogenic factors VEGF and RANKL was observed in intermittent hypoxia-exposed neuroblastoma cells. Conditioned medium from the intermittent hypoxia-exposed neuroblastoma cells was found to enhance osteoclastogenesis, up-regulate the mRNAs of osteoclast marker genes including TRAP, CaSR and cathepsin K and induce the activation of ERK, JNK, and p38 in RAW 264.7 cells. Intermittent hypoxia-exposed neuroblastoma cells showed an increased migratory pattern compared with the parental cells. A significant increase of tumor volume was found in animals that received the intermittent hypoxia-exposed cells intratibially compared with parental cells.

Conclusions

Intermittent hypoxic exposure enhanced capabilities of neuroblastoma cells in induction of osteoclast differentiation in RAW 264.7 cells. Increased migration and intratibial tumor growth was observed in intermittent hypoxia-exposed neuroblastoma cells compared with parental cells.

Inhibition of type I insulin-like growth factor receptor tyrosine kinase by picropodophyllin induces apoptosis and cell cycle arrest in T lymphoblastic leukemia/lymphoma

It has been recently shown that the type I insulin-like growth factor receptor (IGF-IR) contributes significantly to the survival of T lymphoblastic leukemia/lymphoma (T-LBL) cells, and it was therefore suggested that IGF-IR could represent a legitimate therapeutic target in this aggressive disease. Picropodophyllin (PPP) is a potent, selective inhibitor of IGF-IR that is currently used with notable success in clinical trials that include patients with aggressive types of epithelial tumors. In the present study, we tested the effects of PPP on Jurkat and Molt-3 cells; two prototype T-LBL cell lines. Our results demonstrate that PPP efficiently induced apoptotic cell death and cell cycle arrest of these two cells. These effects were attributable to alterations of downstream target proteins. By using proteomic analysis, seven different proteins were found to be affected by PPP treatment of Jurkat cells. These proteins are involved in various aspects of cellular metabolism, cytoskeleton organization and signal transduction pathways. The results suggest that PPP affects multiple signaling molecules and inhibits fundamental pathways that control cell growth and survival. Our study also provides novel evidence that PPP could be potentially utilized for the treatment of aggressive T-LBL.

Quantitative phosphoproteomic analysis identifies activation of the RET and IGF-1R/IR signaling pathways in neuroblastoma

Neuroblastoma is an embryonal tumor of childhood with a heterogenous clinical presentation that reflects differences in activation of complex biological signaling pathways. Protein phosphorylation is a key component of cellular signal transduction and plays a critical role in processes that control cancer cell growth and survival. We used shotgun LC/MS to compare phosphorylation between a human MYCN amplified neuroblastoma cell line (NB10), modeling a resistant tumor, and a human neural precursor cell line (NPC), modeling a normal baseline neural crest cell. 2181 unique phosphorylation sites representing 1171 proteins and 2598 phosphopeptides were found. Protein kinases accounted for 6% of the proteome, with a predominance of tyrosine kinases, supporting their prominent role in oncogenic signaling pathways. Highly abundant receptor tyrosine kinase (RTK) phosphopeptides in the NB10 cell line relative to the NPC cell line included RET, insulin-like growth factor 1 receptor/insulin receptor (IGF-1R/IR), and fibroblast growth factor receptor 1 (FGFR1). Multiple phosphorylated peptides from downstream mediators of the PI3K/AKT/mTOR and RAS pathways were also highly abundant in NB10 relative to NPC. Our analysis highlights the importance of RET, IGF-1R/IR and FGFR1 as RTKs in neuroblastoma and suggests a methodology that can be used to identify potential novel biological therapeutic targets. Furthermore, application of this previously unexploited technology in the clinic opens the possibility of providing a new wide-scale molecular signature to assess disease progression and prognosis.

Type 1 insulin-like growth factor receptor targeted therapies in pediatric cancer

Data from over 20 years ago demonstrated potential use for insulin-like growth factor (IGF) signaling modulators, specifically with IGF-1R antagonists, in a variety of pediatric and adolescent cancers, particularly in sarcomas. However, in spite of promising preclinical data, IGF-1R inhibitors have not had the success as single agents that was originally hoped for in clinical trials. Several potential mechanisms exist by which tumors are resistant to IGF-1R inhibitors. Notably, these resistance mechanisms are currently best understood in Ewing sarcoma and alveolar rhabdomyosarcoma. Various treatment schema have been proposed as a potential way to overcome this resistance. The use of IGF-1R inhibitors, mechanisms of resistance, and current ongoing clinical studies using IGF-1R inhibitors in pediatric cancers are reviewed here.

Establishment and characterization of xenograft models of human neuroblastoma bone metastasis

OBJECTS

To improve the therapy of advanced neuroblastoma (NB), it is critical to develop animal models that mimic NB bone metastases. Unlike the human disease, NB xenograft models rarely metastasize spontaneously to bone from the orthotopic site of primary tumor growth.

METHODS

Single-cell suspensions of SY5Y, KCNR NB cells were injected directly into the femur of nude mice. Radiological and histological analyses and immunohistochemistry analyses were performed to characterize these osseous NB models. SY5Y and KCNR result in osteolytic responses.

RESULTS

We have detected osteoprotegerin, receptor activator of nuclear factor kappa B ligand, parathyroid hormone-related protein, and endothelin-1, proteins associated with bone growth and osteolysis, and C-X-C chemokine receptor type 4 (CXCR4) involved in tumor growth and tumor cell migration in the NB cells grown in the bone.

CONCLUSIONS

These animal models can be used to study biological interactions, pathways, and potential therapeutic targets and also to evaluate new agents for treatment and prevention of NB bone metastasis.

Bone-derived IGF mediates crosstalk between bone and breast cancer cells in bony metastases

The continuous release of bone-stored growth factors after bone resorption promotes the colonization of circulating cancer cells. However, the precise role of each of the various growth factors remains unclear. In this study, we investigated the role of bone-derived insulin-like growth factor (IGF) in the development of bone metastases in an animal model of breast cancer. We found that local stimulation of calvarial bone resorption before cell inoculation stimulated subsequent bone metastases to that site in vivo, although inhibition of bone resorption inhibited bone metastases. Anchorage-independent growth of cancer cells was stimulated by the culture supernatants from resorbed bones, which contained elevated levels of IGF-I. This stimulation was blocked by IGF type I receptor (IGF-IR) neutralizing antibody, but not antibody targeting other bone-stored growth factors including TGF-β, fibroblast growth factors, and platelet-derived growth factors. Although recombinant human IGF-I caused IGF-IR tyrosine autophosphorylation, followed by activation of Akt and NF-κB in cancer cells, dominant-negative inhibition of IGF-IR, Akt, or NF-κB significantly reduced bone metastases with increased apoptosis and decreased mitosis in metastatic cells. Together, our findings suggest that bone-derived IGF-I bridges the crosstalk between bone and metastasized cancer cells via activation of the IGF-IR/Akt/NF-κB pathway. Disruption of this pathway therefore may represent a promising therapeutic intervention for bone metastasis.

Homing of cancer cells to the bone

A variety of tumor cells preferentially home to the bone. The homing of cancer cells to the bone represents a multi-step process that involves malignant progression of the tumor, invasion of the tumor through the extracellular matrix and the blood vessels and settling of the tumor cells in the bone. Gaining a greater understanding as to the mechanisms used by cancer cells in these processes will facilitate the design of drugs which could specifically target the homing process. In this review we will discuss the properties of tumor cells and the bone microenvironment which promote homing of a cancer cell to the bone. We will highlight the different steps and the molecular pathways involved when a cancer cell metastasize to the bone. Since bone is the major home for hematopoietic stem cells (HSCs), we will also highlight the similarities between the homing of cancer and HSC to the bone. Finally we will conclude with therapeutic and early detection strategies which can prevent homing of a cancer cell to the bone.

Insulin regulates GLUT1-mediated glucose transport in MG-63 human osteosarcoma cells

Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. Because cancer cells utilize glucose as their primary energy substrate, the expression and regulation of glucose transporters (GLUT) may be important in tumor development and progression. GLUT expression has not been studied previously in human osteosarcoma cell lines. Furthermore, although insulin and insulin-like growth factor (IGF-I) play an important role in cell proliferation and tumor progression, the role of these hormones on GLUT expression and glucose uptake, and their possible relation to osteosarcoma, have also not been studied. We determined the effect of insulin and IGF-I on GLUT expression and glucose transport in three well-characterized human osteosarcoma cell lines (MG-63, SaOs-2, and U2-Os) using immunocytochemical, RT-PCR and functional kinetic analyses. Furthermore we also studied GLUT isoform expression in osteosarcoma primary tumors and metastases by in situ hybridization and immunohistochemical analyses. RT-PCR and immunostaining show that GLUT1 is the main isoform expressed in the cell lines and tissues studied, respectively. Immunocytochemical analysis shows that although insulin does not affect levels of GLUT1 expression it does induce a translocation of the transporter to the plasma membrane. This translocation is associated with increased transport of glucose into the cell. GLUT1 is the main glucose transporter expressed in osteosarcoma, furthermore, this transporter is regulated by insulin in human MG-63 cells. One possible mechanism through which insulin is involved in cancer progression is by increasing the amount of glucose available to the cancer cell.

The connections between neural crest development and neuroblastoma

Neuroblastoma (NB), the most common extracranial solid tumor in childhood, is an extremely heterogeneous disease both biologically and clinically. Although significant progress has been made in identifying molecular and genetic markers for NB, this disease remains an enigmatic challenge. Since NB is thought to be an embryonal tumor that is derived from precursor cells of the peripheral (sympathetic) nervous system, understanding the development of normal sympathetic nervous system may highlight abnormal events that contribute to NB initiation. Therefore, this review focuses on the development of the peripheral trunk neural crest, the current understanding of how developmental factors may contribute to NB and on recent advances in the identification of important genetic lesions and signaling pathways involved in NB tumorigenesis and metastasis. Finally, we discuss how future advances in identification of molecular alterations in NB may lead to more effective, less toxic therapies, and improve the prognosis for NB patients.

Selective activation of Akt1 by mammalian target of rapamycin complex 2 regulates cancer cell migration, invasion, and metastasis

Mammalian target of rapamycin complex (mTORC) regulates a variety of cellular responses including proliferation, growth, differentiation and cell migration. In this study, we show that mammalian target of rapamycin complex 2 (mTORC2) regulates invasive cancer cell migration through selective activation of Akt1. Insulin-like growth factor-1 (IGF-1)-induced SKOV-3 cell migration was completely abolished by phosphatidylinositol 3-kinase (PI3K) (LY294002, 10 μM) or Akt inhibitors (SH-5, 50 μM), whereas inhibition of extracellular-regulated kinase by an ERK inhibitor (PD98059, 10 μM) or inhibition of mammalian target of rapamycin complex 1 (mTORC1) by an mTORC1 inhibitor (Rapamycin, 100 nM) did not affect IGF-1-induced SKOV-3 cell migration. Inactivation of mTORC2 by silencing Rapamycin-insensitive companion of mTOR (Rictor), abolished IGF-1-induced SKOV-3 cell migration as well as activation of Akt. However, inactivation of mTORC1 by silencing of Raptor had no effect. Silencing of Akt1 but not Akt2 attenuated IGF-1-induced SKOV-3 cell migration. Rictor was preferentially associated with Akt1 rather than Akt2, and over-expression of Rictor facilitated IGF-1-induced Akt1 activation. Expression of PIP3-dependent Rac exchanger1 (P-Rex1), a Rac guanosine exchange factor and a component of the mTOR complex, strongly stimulated activation of Akt1. Furthermore, knockdown of P-Rex1 attenuated Akt activation as well as IGF-1-induced SKOV-3 cell migration. Silencing of Akt1 or P-Rex1 abolished IGF-1-induced SKOV-3 cell invasion. Finally, silencing of Akt1 blocked in vivo metastasis, whereas silencing of Akt2 did not. Given these results, we suggest that selective activation of Akt1 through mTORC2 and P-Rex1 regulates cancer cell migration, invasion and metastasis.

Epithelial plasticity, cancer stem cells and bone metastasis formation

Acquisition of an invasive phenotype of cancer cells in primary tumors is an absolute requirement for bone metastasis. The majority of bone metastases is derived from epithelial cancers, particularly those of the breast and prostate. Accumulating evidence suggest that transformed epithelial cells can activate embryonic programs of epithelial plasticity and switch from a sessile, epithelial phenotype to a motile, mesenchymal phenotype also referred to as epithelial-to-mesenchymal transition (EMT). Induction of EMT can, therefore, lead to invasion of surrounding stroma, intravasation, dissemination and colonization of distant sites. In bone/bone marrow disseminated tumor cells can partially regain their original epithelial characteristics via a mesenchymal-to-epithelial transition (MET) as glandular structures in bone metastasis are frequently observed. To date, the importance of epithelial plasticity in cancer cells disseminated to the bone/bone marrow microenvironment has remained largely elusive. Interestingly, a number of growth factors that play a prominent role in EMT induction in the primary tumor have been identified as important stimulators of skeletal metastasis formation. Recent studies have demonstrated that EMT may render cancer cells with properties of stem cells, which in turn can lead to escape from immune surveillance, increased resistance to apoptosis, diminished senescence and, last-but-not least, therapy resistance. This review will discuss current concepts regarding the role of epithelial plasticity in the multistep processes of bone metastasis, the issue of minimal residual disease, cancer stem cells and the importance of EMT in the development of novel targeted drug therapy.

Pharmacokinetically guided phase 1 trial of the IGF-1 receptor antagonist RG1507 in children with recurrent or refractory solid tumors

PURPOSE

This pediatric phase I study was designed to identify the doses of RG1507, a monoclonal antibody against the Type 1 Insulin-like Growth Factor Receptor (IGF1R), that achieves exposures equivalent to those achieved in adults at recommended doses.

EXPERIMENTAL DESIGN

Children with relapsed or refractory solid tumors were treated using the same doses and administration schedules of RG1507 (3 and 9 mg/kg/wk, and 16 mg/kg every 3 weeks [q3W]) as those studied in adults. Detailed pharmacokinetic (PK) sampling was performed after the first dose; selected peak and trough levels were subsequently obtained. Target exposures were ≥85% of mean areas under concentration x time curves (AUCs) in adults at doses of 9 mg/kg/wk and 16 mg/kg q3W. A maximum tolerated dose could be identified if dose-limiting toxicities (DLT) occurred.

RESULTS

Thirty-one evaluable patients aged 3-17 years were enrolled at 3 mg/kg/wk (n = 3), 9 mg/kg/wk (n = 18), or 16 mg/kg q3W (n = 10). There were no DLTs. At 9 mg/kg/wk the mean AUC(0-7d) (21,000 μg h/mL) exceeded the target (16,000 μg h/mL). At 16 mg/kg q3W, the mean AUC(021d) (70,000 μg h/mL) exceeded the target (59,400 μg h/mL). Clearance normalized to body weight was age dependent. There were no objective responses. Seven patients had stable disease for >12 weeks, including two patients with osteosarcoma with stable disease for 52+ and 78+ weeks.

CONCLUSIONS

The recommended doses of RG1507 in children with solid tumors are 9 mg/kg/wk and 16 mg/kg q3W. This flexible design is well suited for trials of agents associated with limited toxicity.

Anti-insulin-like growth factor 1 receptor antibody EM164 (murine AVE1642) exhibits anti-tumour activity alone and in combination with temozolomide against neuroblastoma

Insulin-like growth factor 1 receptor (IGF-1R) is overexpressed in many tumours and contributes to tumourigenicity, cell proliferation, metastasis and resistance, thus representing a promising therapeutic target. The human IGF-1R antagonistic monoclonal antibody EM164 (murine AVE1642) has shown activity in adult cancers and is being evaluated in patients with advanced malignancies. We investigated the EM164 for its therapeutic potential against childhood neuroblastoma. EM164 at 0.07, 0.7 and 7 μg/mL exhibited anti-proliferative activity against all nine cell lines tested in (3)H-thymidine incorporation assay in vitro. Cell proliferation after EM164 exposure ranged between 24% and 80% compared to controls. Sensitivity was independent from culture serum conditions, intensity of IGF-1R expression and IGF-II secretion, although associated with inhibition of AKT activation. In vivo, EM164 administered intravenously at 40 mg/kg twice weekly for 4 weeks yielded significant tumour growth delays (TGD) of 13.4d in advanced stage IGR-N91 and 12.9 d in SK-N-AS tumours compared to controls (p = 0.02 and p = 0.0059, respectively). Simultaneous treatment of EM164 0.7 μg/mL and temozolomide resulted in enhanced activity in vitro. In vivo, treatment with temozolomide at the maximum tolerated dose (100mg/kg/d for 5 consecutive days) and EM164 yielded a significantly greater TGD of 29.1d (p<0.01) and two complete tumour regressions (CR) compared to 18.1d (p = ns) and one CR for EM164 alone and 16.1d (p = ns) for temozolomide alone. Our results demonstrate the potential of the anti-IGF-1R antibody alone and in combination with alkylating agents and support the therapeutic development of the AVE1642 for aggressive neuroblastoma.

Elevated IGFIR expression regulating VEGF and VEGF-C predicts lymph node metastasis in human colorectal cancer

BACKGROUND

Insulin-like growth factor-I receptor (IGFIR) has been shown to regulate the tumor development. The objective of the current study is to determine the association of IGFIR with lymph node metastasis and to explore the related mechanism in human colorectal cancer in clinic.

METHODS

In a random series of 98 colorectal cancer patients, the expressions of IGFIR, vascular endothelial growth factor (VEGF) and VEGF-C were investigated by immunohistochemistry, and the association of these expressions with lymph node metastasis was statistically analyzed. The expressions of VEGF and VEGF-C in colorectal cancer cells stimulated with IGF-I were also examined by real-time quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

Higher rates of IGFIR (46%), VEGF (53%), and VEGF-C (46%) expression were found in colorectal cancer tissues than in normal and colorectal adenoma tissues. These expressions were significantly associated with clinicopathologic factors and lymph node status. We also found the concomitant high expressions of IGFIR/VEGF (P < 0.001) and IGFIR/VEGF-C (P = 0.001) had a stronger correlation with lymph node metastasis than did each alone or both low expressions. In addition, IGF-I could effectively induce the VEGF and VEGF-C mRNA expression and protein secretion in colorectal cancer cells expressing IGFIR molecules. Moreover, Patients who had strong staining for IGFIR, VEGF and VEGF-C showed significantly less favorable survival rates compared with patients who had low staining for these molecules (P < 0.001). The survival rates of patients who were both high expression of IGFIR/VEGF and IGFIR/VEGF-C also were significantly lower compared with patients who were negative or one of high expression of these molecules (P < 0.001).

CONCLUSIONS

Together the findings indicated for the first time that simultaneous examination of the expressions of IGFIR, VEGF and VEGF-C will benefit the diagnosis of lymph node metastasis in order to assay the prognosis and determine the treatment strategy in patients with colorectal cancer undergoing surgery.

Unusual association of alveolar rhabdomyosarcoma with pancreatic metastasis: emerging role of PET-CT in tumor staging

BACKGROUND

Pancreatic metastases in childhood cancer have been rarely reported in the radiology literature although ample evidence exists in pathology reports for its occurrence in patients with alveolar rhabdomyosarcomas (RMS).

OBJECTIVE

Assess the occurrence of pancreatic metastases in alveolar rhabdomyosarcomas, increase awareness of this association and reassess current staging protocols.

MATERIALS AND METHODS

Three major oncology centers reviewed their records and imaging examinations. Patients' history and demographics, primary tumor site and histology, presence of tumor recurrence, and presence and location of other metastases were reviewed.

RESULTS

Pancreatic metastases occurred in eight patients with alveolar RMS. Four of these presented at diagnosis and four with disease recurrence. In recurrent disease, the duration between the diagnosis of the primary tumor and pancreatic metastases varied from 8 months to 6 years (mean +/- SD: 2.38 +/- 2.49 years). In all patients who received PET scans, pancreatic metastases showed a marked FDG-uptake, but had variable detectability with CT. Pancreatic metastases were not associated with certain primary tumor locations or presence of other metastases, mandating an evaluation of the pancreas in all cases of alveolar rhabdomyosarcomas.

CONCLUSION

Radiologists should be sensitized and actively evaluate the pancreas in patients with alveolar RMS. Optimizing CT and PET-CT protocols may increase the diagnostic yield.

The type I insulin-like growth factor receptor regulates cancer metastasis independently of primary tumor growth by promoting invasion and survival

The type I insulin-like growth factor receptor (IGF1R) regulates multiple aspects of malignancy and is the target of several drugs currently in clinical trials. While IGF1R’s role in proliferation and survival is well-studied, the regulation of metastasis by IGF1R is not as clearly delineated. Previous work showed that disruption of IGF1R signaling via overexpression of a dominant negative IGF1R inhibited metastasis. To establish a clinically applicable approach to inhibition of metastasis by targeting IGF1R, the effect of an inhibitory antibody against IGF1R, EM164 and its humanized version, AVE1642 on metastasis of cancer cells was examined. EM164 and AVE1642 did not affect primary tumor growth of MDA-435A/LCC6 cells but inhibited metastasis of these cells. Consistent with this inhibition in the formation of metastatic nodules, disruption of IGF1R also resulted in a decreased number of circulating tumor cells in blood of tumor-bearing mice. Disruption of IGF1R with a dominant negative construct or antibody inhibited invasion across Matrigel in vitro. When tumor cells were directly injected into the circulation via the lateral tail vein of mice, IGF1R disruption also resulted in significant reduction of pulmonary nodules, suggesting that regulation of invasion is not the only function of IGF1R signaling. Further, disruption of IGF1R rendered cells more susceptible to anoikis. Thus, IGF1R regulated metastasis independently of tumor growth. The multiple phenotypes regulated by IGF1R must be considered during development of this therapeutic strategy as inhibition of metastasis independent of inhibition of tumor growth is not easily assessed in phase II clinical trials.

Inhibition of IGF-IR tyrosine kinase induces apoptosis and cell cycle arrest in imatinib-resistant chronic myeloid leukaemia cells

Although signalling through the type I insulin-like growth factor receptor (IGF-IR) maintains the survival of haematopoietic cells, a specific role of IGF-IR in haematological neoplasms remains largely unknown. Chronic myeloid leukaemia (CML) is the most common subtype of chronic myeloproliferative diseases. Typically, CML evolves as a chronic phase (CP) disease that progresses into accelerated (AP) and blast phase (BP) stages. In this study, we show that IGF-IR is universally expressed in four CML cell lines. IGF-IR was expressed in only 30% and 25% of CP and AP patients, respectively, but its frequency of expression increased to 73% of BP patients. Increased expression levels of IGF-IR with CML progression was supported by quantitative real-time PCR that demonstrated significantly higher levels of IGF-IR mRNA in BP patients. Inhibition of IGF-IR decreased the viability and proliferation of CML cell lines and abrogated their growth in soft agar. Importantly, inhibition of IGF-IR decreased the viability of cells resistant to imatinib mesylate including BaF3 cells transfected with p210 BCR-ABL mutants, CML cell lines and primary neoplastic cells from patients. The negative effects of inhibition of IGF-IR were attributable to apoptosis and cell cycle arrest due to alterations of downstream target proteins. Our findings suggest that IGF-IR could represent a potential molecular target particularly for advanced stage or imatinib-resistant cases.

IGF-IR tyrosine kinase interacts with NPM-ALK oncogene to induce survival of T-cell ALK+ anaplastic large-cell lymphoma cells

Type I insulin-like growth factor receptor (IGF-IR) tyrosine kinase plays important roles in the pathogenesis of several malignancies. Although it promotes the growth of stimulated hematopoietic cells, a direct role of IGF-IR in malignant lymphoma has not been identified. Anaplastic lymphoma kinase-positive anaplastic large-cell lymphoma (ALK(+) ALCL) is a unique type of T-cell lymphoma. Approximately 85% of ALK(+) ALCL cases harbor the translocation t(2;5)(p23;q35), which generates the chimeric oncogene NPM-ALK. In the present study, we explored a possible role of IGF-IR in ALK(+) ALCL. Our results demonstrate that IGF-IR and IGF-I are widely expressed in ALK(+) ALCL cell lines and primary tumors. Importantly, we identified novel reciprocal functional interactions between IGF-IR and NPM-ALK. Antagonism of IGF-IR decreased the viability, induced apoptosis and cell-cycle arrest, and decreased proliferation and colony formation of ALK(+) ALCL cell lines. These effects could be explained by alterations of cell survival regulatory proteins downstream of IGF-IR signaling. Our findings improve current understanding of the biology of IGF-IR and NPM-ALK and have significant therapeutic implications as they identify IGF-IR signaling as a potential therapeutic target in ALK(+) ALCL and possibly other types of malignant lymphoma.

Regulation of breast cancer metastasis by IGF signaling

The insulin-like growth factors (IGFs) signaling via the type I insulin-like growth factor receptor (IGF-1R) regulate multiple aspects of malignancy. The importance of IGF-1R in regulating the malignant phenotype is currently being validated in numerous clinical trials for cancer including breast cancer. This review discusses the regulation of breast cancer metastasis by IGF-1R. IGF-1R stimulates invasion and survival in anchorage independent conditions. The regulation of metastasis independently of tumor growth by IGF-1R is also discussed. Finally, the impact of this on clinical trial design and outcomes, and the need for biomarkers, other than reduction in tumor size, are discussed in light of the fact that inhibition of metastasis is not measured in conventional clinical trial design.

Differential gene expression in murine large cell B-cell lymphoma metastatic variants

Previous studies from this laboratory have characterized RAW117-P murine large cell B-cell lymphoma and its in vivo selected highly malignant and liver metastatic RAW117-H10 subline for their biological and biochemical properties. In this study, to understand the molecular basis of low and high metastatic behavior of these variant sublines, we have investigated the molecular phenotypes of these cells using differential display techniques and cDNA array analysis. Differential display analysis indicated a significant difference in expression of several genes between these two metastatic variant lymphoma cells. Further analyses of these cells using microarray showed an increased expression of several genes including uPAR1, CRE-BP1, Chop-10, IGF, insulin-like growth factor-IA, STAT6, Cyclin-D1, Cyclin-E, ERBB-3, Alpha NGF, Kruppel-like factor LKLF, (P)19INK4 in metastatic RAW117-H10 cells compared to parental RAW117-P cells. On the other hand, MIP1beta, CD14 antigen, Cathepsin B and MOD are expressed more in RAW117-P cells compared to RAW117-H10 cells. Differential expression of the selected genes was confirmed using semiquantitative RT-PCR techniques. The combination of plasminogen activator and its receptor and IGF-like growth factors, cell cycle regulatory molecules and transcription factors might provide an ideal environment for RAW117-H10 cells to metastasize to distant organs and colonize. Thus these results identify certain differentially expressed genes that are involved in the metastatic properties of these lymphoma cells and lay foundation for further in depth analyses to use this information to develop therapy for metastatic lymphoma.

Molecular biology of bone metastasis

Metastasis is a final stage of tumor progression. Breast and prostate cancer cells preferentially metastasize to bone, wherein they cause incurable osteolytic and osteoblastic lesions. The bone matrix is rich in factors, such as transforming growth factor-beta and insulin-like growth factors, which are released into the tumor microenvironment by osteolysis. These factors stimulate the growth of tumor cells and alter their phenotype, thus promoting a vicious cycle of metastasis and bone pathology. Physical factors within the bone microenvironment, including low oxygen levels, acidic pH, and high extracellular calcium concentrations, may also enhance tumor growth. These elements of the microenvironment are potential targets for chemotherapeutic intervention to halt tumor growth and suppress bone metastasis.

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.