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Supplementary Table S1 - RT-PCR Primer sequences used in the study Supplementary Table S2 - CDK2 shRNA sequences used in the study Supplementary Table S3 - Cell lines and genes used in the analysis from Project Achilles Supplementary Table S4 - EC50 values for compounds from primary screen for OVCAR3 and SKOV3 cell lines Supplementary Table S5 - EC50 values for compounds from primary screen for OVCAR3 and OVCAR3-R1 cell lines Supplementary Table S7 - List of compounds and their primary targets tested in the secondary screen for OVCAR3 and OVCAR3-R1 cell lines Supplementary Table S8 - List of combination indexes and type of interaction between compounds tested in the matrix screen

IL-6 RTPCR primers

Selected compounds for secondary screen

Primary hits-JHOC-5

Low-grade serous ovarian carcinomas (LGSC) are associated with a poor response to chemotherapy and are molecularly characterized by RAS pathway activation. Using exome and whole genome sequencing, we identified recurrent mutations in the protein translational regulator EIF1AX and in NF1, USP9X, KRAS, BRAF, and NRAS. RAS pathway mutations were mutually exclusive; however, we found significant co-occurrence of mutations in NRAS and EIF1AX. Missense EIF1AX mutations were clustered at the N-terminus of the protein in a region associated with its role in ensuring translational initiation fidelity. Coexpression of mutant NRAS and EIF1AX proteins promoted proliferation and clonogenic survival in LGSC cells, providing the first example of co-occurring, growth-promoting mutational events in ovarian cancer. Cancer Res; 77(16); 4268–78. ©2017 AACR.

Purpose: Cyclin E1 (CCNE1) amplification is associated with primary treatment resistance and poor outcome in high-grade serous ovarian cancer (HGSC). Here, we explore approaches to target CCNE1-amplified cancers and potential strategies to overcome resistance to targeted agents.Experimental Design: To examine dependency on CDK2 in CCNE1-amplified HGSC, we utilized siRNA and conditional shRNA gene suppression, and chemical inhibition using dinaciclib, a small-molecule CDK2 inhibitor. High-throughput compound screening was used to identify selective synergistic drug combinations, as well as combinations that may overcome drug resistance. An observed relationship between CCNE1 and the AKT pathway was further explored in genomic data from primary tumors, and functional studies in fallopian tube secretory cells.Results: We validate CDK2 as a therapeutic target by demonstrating selective sensitivity to gene suppression. However, we found that dinaciclib did not trigger amplicon-dependent sensitivity in a panel of HGSC cell lines. A high-throughput compound screen identified synergistic combinations in CCNE1-amplified HGSC, including dinaciclib and AKT inhibitors. Analysis of genomic data from TCGA demonstrated coamplification of CCNE1 and AKT2. Overexpression of Cyclin E1 and AKT isoforms, in addition to mutant TP53, imparted malignant characteristics in untransformed fallopian tube secretory cells, the dominant site of origin of HGSC.Conclusions: These findings suggest a specific dependency of CCNE1-amplified tumors for AKT activity, and point to a novel combination of dinaciclib and AKT inhibitors that may selectively target patients with CCNE1-amplified HGSC. Clin Cancer Res; 23(7); 1862–74. ©2016 AACR.

Supplemental Material - Group Authorship from EIF1AX and NRAS Mutations Co-occur and Cooperate in Low-Grade Serous Ovarian Carcinomas

Primary hits-TOV21G

Supplementary Figure S1 - Validation of CCNE1 and CDK2 siRNA-mediated knockdown Supplementary Figure S2 - Validation of CDK2 knockdown mediated by shRNA in vitro and in vivo Supplementary Figure S3 - FACS plots validating incorporation and induction of shRNA into OVCAR3 and CAOV3 cells Supplementary Figure S4 - Characterisation of CDK resistant lines and supplementary data supporting drug treatment Supplementary Figure S5 - Extended Oncoprint figure from TCGA Supplementary Figure S6 - Validation of FT282 over-expression constructs

Supplemental materials and methods

RPPA Antibody List

Supplementary Table S1. Patient characteristics; Supplementary Table S2. Ki67 proliferation index; Supplementary Table S3. WES and WGS performance statistics; Supplementary Table S4. Amplicon sequencing primers; Supplementary Table S5. High confidence variants from exome and whole genome sequencing; Supplementary Table S6. Summary of SNVs and indels by sample; Supplementary Table S7. Significantly mutated genes (MuSiC output); Supplementary Table S8. Somatic variants in recurrently mutated genes; Supplementary Table S9. Validation cohort variants; Supplementary Table S10. TP53 variants in validation cohort; Supplementary Table S11. EIF1AX mutations reported in cancer

Ovarian clear cell adenocarcinoma (OCCA) is characterized by a particularly poor response to conventional chemotherapy and a short overall survival time in women with established disease. The development of targeted treatments for OCCA relies on a better understanding of its molecular characteristics. IL6 is strongly expressed in OCCA and may therefore provide a novel therapeutic target. Here we use CRISPR/Cas9 and conditional short hairpin interfering RNA to perform loss-of-function studies in human OCCA cell lines to explore the requirement for IL6 in vitro and in vivo. While reduction of IL6 expression exerted limited effects in vitro, its attenuation significantly impaired tumor growth and neovascularization in vivo. In contrast to typical signaling via STAT3, IL6 in OCCA signaled via a noncanonical pathway involving gp130, Src, and the Hippo pathway protein YAP. A high-throughput combination drug screen identified agents that enhanced cell killing following reduction of IL6 signaling. Intersection of screen hits obtained from two cell lines and orthogonal approaches to attenuation of IL6 yielded AKT and EGFR inhibitors as enhancers of the inhibitory monoclonal IL6 receptor antibody tocilizumab. This study defines for the first time the requirements for, and mechanisms of, signaling by IL6 in human OCCA cell lines and identifies potential combinatory therapeutic approaches. Given the molecular diversity of OCCA, further in vitro and in vivo studies are warranted to determine whether such approaches will overcome the limited efficacy of tocilizumab observed in ovarian cancer to date.Significance:This study defines the requirements for and mechanisms of noncanonical signaling by IL6 in human ovarian clear cell adenocarcinoma cell lines and identifies combinatory therapeutic approaches to be explored clinically.

Supplementary Figures

Additional description of methods for gene suppression studies, Western blot, immunohistochemistry, flow cytometry and cellular assays

Supplementary Figure S1. Representative hematoxylin and eosin stained sections from sequenced LGSC; Supplementary Figure S2. Age distribution analysis of patients from the Australian Ovarian Cancer Study. Includes patients with advanced stage, serous epithelial ovarian cancer (n = 684); Supplementary Figure S3. RAS pathway mutations in LGSC; Supplementary Figure S4. Verification of EIF1AX mutations; Supplementary Figure S5. Characterization of the AOCS2 cell line; Supplementary Figure S6. Functional effect of EIF1AX mutations and gene suppression in a LGSC cell line; Supplementary Figure S7. (a) EIF1AX and NRAS function in the mTOR and RAS/ERK signaling pathways to regulate protein translation, cell proliferation and cell survival

Ovarian clear cell adenocarcinoma (OCCA) is characterized by a particularly poor response to conventional chemotherapy and a short overall survival time in women with established disease. The development of targeted treatments for OCCA relies on a better understanding of its molecular characteristics. IL6 is strongly expressed in OCCA and may therefore provide a novel therapeutic target. Here we use CRISPR/Cas9 and conditional short hairpin interfering RNA to perform loss-of-function studies in human OCCA cell lines to explore the requirement for IL6 in vitro and in vivo. While reduction of IL6 expression exerted limited effects in vitro, its attenuation significantly impaired tumor growth and neovascularization in vivo. In contrast to typical signaling via STAT3, IL6 in OCCA signaled via a noncanonical pathway involving gp130, Src, and the Hippo pathway protein YAP. A high-throughput combination drug screen identified agents that enhanced cell killing following reduction of IL6 signaling. Intersection of screen hits obtained from two cell lines and orthogonal approaches to attenuation of IL6 yielded AKT and EGFR inhibitors as enhancers of the inhibitory monoclonal IL6 receptor antibody tocilizumab. This study defines for the first time the requirements for, and mechanisms of, signaling by IL6 in human OCCA cell lines and identifies potential combinatory therapeutic approaches. Given the molecular diversity of OCCA, further in vitro and in vivo studies are warranted to determine whether such approaches will overcome the limited efficacy of tocilizumab observed in ovarian cancer to date. Significance: This study defines the requirements for and mechanisms of noncanonical signaling by IL6 in human ovarian clear cell adenocarcinoma cell lines and identifies combinatory therapeutic approaches to be explored clinically.

Low-grade serous ovarian carcinomas (LGSC) are associated with a poor response to chemotherapy and are molecularly characterized by RAS pathway activation. Using exome and whole genome sequencing, we identified recurrent mutations in the protein translational regulator EIF1AX and in NF1, USP9X, KRAS, BRAF, and NRAS. RAS pathway mutations were mutually exclusive; however, we found significant co-occurrence of mutations in NRAS and EIF1AX. Missense EIF1AX mutations were clustered at the N-terminus of the protein in a region associated with its role in ensuring translational initiation fidelity. Coexpression of mutant NRAS and EIF1AX proteins promoted proliferation and clonogenic survival in LGSC cells, providing the first example of co-occurring, growth-promoting mutational events in ovarian cancer. Cancer Res; 77(16); 4268–78. ©2017 AACR.

Purpose: Cyclin E1 (CCNE1) amplification is associated with primary treatment resistance and poor outcome in high-grade serous ovarian cancer (HGSC). Here, we explore approaches to target CCNE1-amplified cancers and potential strategies to overcome resistance to targeted agents. Experimental Design: To examine dependency on CDK2 in CCNE1-amplified HGSC, we utilized siRNA and conditional shRNA gene suppression, and chemical inhibition using dinaciclib, a small-molecule CDK2 inhibitor. High-throughput compound screening was used to identify selective synergistic drug combinations, as well as combinations that may overcome drug resistance. An observed relationship between CCNE1 and the AKT pathway was further explored in genomic data from primary tumors, and functional studies in fallopian tube secretory cells. Results: We validate CDK2 as a therapeutic target by demonstrating selective sensitivity to gene suppression. However, we found that dinaciclib did not trigger amplicon-dependent sensitivity in a panel of HGSC cell lines. A high-throughput compound screen identified synergistic combinations in CCNE1-amplified HGSC, including dinaciclib and AKT inhibitors. Analysis of genomic data from TCGA demonstrated coamplification of CCNE1 and AKT2. Overexpression of Cyclin E1 and AKT isoforms, in addition to mutant TP53, imparted malignant characteristics in untransformed fallopian tube secretory cells, the dominant site of origin of HGSC. Conclusions: These findings suggest a specific dependency of CCNE1-amplified tumors for AKT activity, and point to a novel combination of dinaciclib and AKT inhibitors that may selectively target patients with CCNE1-amplified HGSC. Clin Cancer Res; 23(7); 1862–74. ©2016 AACR.

Objectives p53 is a critical tumour suppressor and is mutated in 70% of oesophageal adenocarcinomas (OACs), resulting in chemoresistance and poor survival. APR-246 is a first-in-class reactivator of mutant p53 and is currently in clinical trials. In this study, we characterised the activity of APR-246 and its effect on p53 signalling in a large panel of cell line xenograft (CLX) and patient-derived xenograft (PDX) models of OAC. Design In vitro response to APR-246 was assessed using clonogenic survival, cell cycle and apoptosis assays. Ectopic expression, gene knockdown and CRISPR/Cas9-mediated knockout studies of mutant p53 were performed to investigate p53-dependent drug effects. p53 signalling was examined using quantitative RT-PCR and western blot. Synergistic interactions between APR-246 and conventional chemotherapies were evaluated in vitro and in vivo using CLX and PDX models. Results APR-246 upregulated p53 target genes, inhibited clonogenic survival and induced cell cycle arrest as well as apoptosis in OAC cells harbouring p53 mutations. Sensitivity to APR-246 correlated with cellular levels of mutant p53 protein. Ectopic expression of mutant p53 sensitised p53-null cells to APR-246, while p53 gene knockdown and knockout diminished drug activity. Importantly, APR-246 synergistically enhanced the inhibitory effects of cisplatin and 5-fluorouracil through p53 accumulation. Finally, APR-246 demonstrated potent antitumour activity in CLX and PDX models, and restored chemosensitivity to a cisplatin/5-fluorouracil-resistant xenograft model. Conclusions APR-246 has significant antitumour activity in OAC. Given that APR-246 is safe at therapeutic levels our study strongly suggests that APR-246 can be translated into improving the clinical outcomes for OAC patients.

TP53, a critical tumour suppressor gene, is mutated in over half of all cancers resulting in mutant-p53 protein accumulation and poor patient survival. Therapeutic strategies to target mutant-p53 cancers are urgently needed. We show that accumulated mutant-p53 protein suppresses the expression of SLC7A11, a component of the cystine/glutamate antiporter, system xC−, through binding to the master antioxidant transcription factor NRF2. This diminishes glutathione synthesis, rendering mutant-p53 tumours susceptible to oxidative damage. System xC− inhibitors specifically exploit this vulnerability to preferentially kill cancer cells with stabilized mutant-p53 protein. Moreover, we demonstrate that SLC7A11 expression is a novel and robust predictive biomarker for APR-246, a first-in-class mutant-p53 reactivator that also binds and depletes glutathione in tumours, triggering lipid peroxidative cell death. Importantly, system xC− antagonism strongly synergizes with APR-246 to induce apoptosis in mutant-p53 tumours. We propose a new paradigm for targeting cancers that accumulate mutant-p53 protein by inhibiting the SLC7A11–glutathione axis., Efficient therapeutic strategies to target mutant-p53 cancers are needed. Here, the authors demonstrate the molecular mechanism through which mutant-p53 tumours are susceptible to oxidative damage and propose a potential strategy for targeting such cancers by inhibiting the SLC7A11-glutathione axis.

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

Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.

The ubiquitous nature of the IGF system, expressed early in embryonic development throughout postnatal and adult life, indicates a key role for this system in human biology. Studies of transgenic mice over-expressing components of the IGF system or mice with disruptions of the same genes have clearly shown that the IGF system plays an important role in vivo. The activity of the IGF ligands, elicited via their receptors and transduced by various intracellular signal pathways, is modulated by the IGFBPs. Among all the IGFBPs, IGFBP-2 has been implicated in the regulation of IGF activity in the nervous system, peripheral tissue and organs. Besides binding to IGFs in the circulation, these IGF-regulatory activities of IGFBP-2 involve interactions with components of the extracellular matrix and cell surface proteoglycans and integrin receptors. In addition to these "local" peri-cellular activities of IGFBP-2, it became evident that IGFBP-2 exerts other key functions within the cell. In the cytoplasm IGFBP-2, most likely in the absence of the IGFs, interacts with regulatory proteins including transcription factors and cytoplasm-nuclear transporters. Within the nucleus IGFBP-2, directly or indirectly, promotes transcriptional activation of specific genes. These intrinsic activities of IGFBP-2 are mediated via specific functional domains. All of these IGFBP-2 activities, intrinsic or dependent on IGFs, contribute to its functional roles in growth/development, metabolism and malignancy as evidenced by studies in IGFBP-2 animal models and also by many in vitro studies. Finally, preclinical studies have demonstrated that IGFBP-2 administration can be beneficial in improving metabolic responses (inhibition of adipogenesis and enhanced insulin sensitivity), while blockade of IGFBP-2 appears to be an effective approach to inhibiting tumor growth and metastasis.

IGFBP-2 is highly expressed in both the serum and tumor tissues of most cancers, and is considered one of the most significant genes in the signature of major cancers. IGFBP-2 mainly modulates IGF actions in the pericellular space; however, there is considerable evidence to suggest that IGFBP-2 may also act independently of the IGFs. These IGF-independent actions of IGFBP-2 are exerted either via interactions at the cell surface or intracellularly, via interaction with cytoplasmic or nuclear-binding partners. The precise mechanism underlying the intracellular/intranuclear localization of IGFBP-2 remains unclear. In this study, we investigated IGFBP-2 nuclear localization in several common cancer cells with the aim of dissecting the mechanism of its nuclear trafficking. IGFBP-2 is detected in the nuclei of common cancer cells, including breast, prostate and several neuroblastoma cell lines, using cell fractionation and confocal microscopy. Via nuclear import assays, we show that nuclear entry of IGFBP-2 is mediated by the classical nuclear import mechanisms, primarily through importin-α, as demonstrated by the use of blocking, competition and co-immunoprecipitation assays. Bioinformatics analysis of the IGFBP-2 protein sequence with PSORT II identified a classical nuclear localization signal (cNLS) sequence at 179PKKLRPP185, within the IGFBP-2 linker domain, mutagenesis of which abolishes IGFBP-2 nuclear import. Accordingly, the NLSmutIGFBP-2 fails to activate the VEGF promoter, which would otherwise occur in the presence of wild-type IGFBP-2. As a consequence, no activation of angiogenic processes were observed in NLSmutIGFBP-2 expressing SHEP cells when implanted onto our in vivo quail chorio-allantoic membrane model. Taken together, these data show for the first time that IGFBP-2 possesses a functional NLS sequence and that IGFBP-2 actively translocates into the nucleus by a classical nuclear import mechanism, involving formation of IGFBP-2 complexes with importin-α. Nuclear IGFBP-2 is required for the activation of VEGF expression and consequent angiogenesis.

Background Desert hedgehog (DHH) belongs to the hedgehog gene family that act as secreted intercellular signal transducers. DHH is an essential morphogen for normal testicular development and function in both mice and humans but is not present in the avian lineage. Like other hedgehog proteins, DHH signals through the patched (PTCH) receptors 1 and 2. Here we examine the expression and protein distribution of DHH, PTCH1 and PTCH2 in the developing testes of a marsupial mammal (the tammar wallaby) to determine whether DHH signalling is a conserved factor in gonadal development in all therian mammals. Results DHH, PTCH1 and PTCH2 were present in the marsupial genome and highly conserved with their eutherian orthologues. Phylogenetic analyses indicate that DHH has recently evolved and is a mammal-specific hedgehog orthologue. The marsupial PTCH2 receptor had an additional exon (exon 21a) not annotated in eutherian PTCH2 proteins. Interestingly we found evidence of this exon in humans and show that its translation would result in a truncated protein with functions similar to PTCH1. We also show that DHH expression was not restricted to the testes during gonadal development (as in mice), but was also expressed in the developing ovary. Expression of DHH, PTCH1 and PTCH2 in the adult tammar testis and ovary was consistent with findings in the adult mouse. Conclusions These data suggest that there is a highly conserved role for DHH signalling in the differentiation and function of the mammalian testis and that DHH may be necessary for marsupial ovarian development. The receptors PTCH1 and PTCH2 are highly conserved mediators of hedgehog signalling in both the developing and adult marsupial gonads. Together these findings indicate DHH is an essential therian mammal-specific morphogen in gonadal development and gametogenesis.

The growth hormone/insulin-like growth factor-I (IGF-I) axis is at the centre of normal human childhood growth. Six well characterised binding proteins (IGFBP-1 to IGFBP-6) act as general carriers of IGF-I, but they also modulate IGF-I bioavailability and activity in a tissue-specific, and developmentally appropriate, manner. Recent findings also point to several binding proteins possessing specific 'lGF-independent' actions and, in particular, there is now substantial evidence linking IGFBP-2 with nutritional status and insulin sensitivity. IGFBP-2 concentrations are reduced in obesity, and further reductions are seen in those with Type 2 diabetes. As IGFBP-2 is the major IGFBP expressed in infancy, and is also the predominant IGFBP produced from adipocytes, it is ideally positioned to act as a keystone between nutrition, growth and metabolism. Childhood obesity is associated with an increased risk of long-term morbidity and mortality, but the factors that determine which obese children will develop these long-term complications are not fully understood. IGFBP-2 may be integrally involved in the molecular processes that govern the development of obesity and subsequent weight-related disease. Within this manuscript, we explore the associations between IGFBP-2 and obesity with a particular emphasis on how an increased understanding of the role of IGFBP-2 in metabolism may lead to improvements in the prevention and treatment of childhood obesity.

IGF binding protein (IGFBP)-2 is one of the most significant genes in the signature of major aggressive cancers. Previously, we have shown that IGFBP-2 enhances proliferation and invasion of neuroblastoma cells, suggesting that IGFBP-2 activates a protumorigenic gene expression program in these cells. Gene expression profiling in human neuroblastoma SK-N-SHEP (SHEP)-BP-2 cells indicated that IGFBP-2 overexpression activated a gene expression program consistent with enhancement of tumorigenesis. Regulation was significant for genes involved in proliferation/survival, migration/adhesion, and angiogenesis, including the up-regulation of vascular endothelial growth factor (VEGF) mRNA (>2-fold). Specific transcriptional activation of the VEGF gene by IGFBP-2 overexpression was demonstrated via cotransfection of a VEGF promoter Luciferase construct in SHEP-BP-2. Cotransfection of VEGF promoter Luciferase construct with IGFBP-2 protein in wild-type SHEP cells indicated that transactivation of VEGF promoter only occurs in the presence of intracellular IGFBP-2. Cell fractionation and immunofluorescence in SHEP-BP-2 cells demonstrated nuclear localization of IGFBP-2. These findings suggest that transcriptional activation of VEGF promoter is likely to be mediated by nuclear IGFBP-2. The levels of secreted VEGF (up to 400 pg/106 cells) suggested that VEGF might elicit angiogenic activity. Hence, SHEP-BP-2 cells and control clones cultured in collagen sponge were xenografted onto chick embryo chorioallantoic membrane. Neomicrovascularization was observed by 72 h, solely in the SHEP-BP-2 cell xenografts. In conclusion, our data indicate that IGFBP-2 is an activator of aggressive behavior in cancer cells, involving nuclear entry and activation of a protumorigenic gene expression program, including transcriptional regulation of the VEGF gene and consequent proangiogenic activity of NB cell xenografts in vivo.

Aromatase inhibitors have been increasingly used in boys with growth retardation to prolong the duration of growth and increase final height. Multiple important roles of oestrogen in males point to potential adverse effects of this strategy. Although the deleterious effects of aromatase deficiency in early childhood and adulthood are well documented, there is limited information about the potential long-term adverse effects of peripubertal aromatase inhibition. To address this issue, we evaluated short-term and long-term effects of peripubertal aromatase inhibition in an animal model. Peripubertal male Wistar rats were treated with aromatase inhibitor letrozole or placebo and followed until adulthood. Letrozole treatment caused sustained reduction in bone strength and alteration in skeletal geometry, lowering of IGF1 levels, inhibition of growth resulting in significantly lower weight and length of treated animals and development of focal prostatic hyperplasia. Our observation of adverse long-term effects after peripubertal male rats were exposed to aromatase inhibitors highlights the need for further characterisation of long-term adverse effects of aromatase inhibitors in peripubertal boys before further widespread use is accepted. Furthermore, this suggests the need to develop more selective oestrogen inhibition strategies in order to inhibit oestrogen action on the growth plate, while beneficial effects in other tissues are preserved.

Insulin-like growth factor binding protein-2 (IGFBP-2) is widely abundant in fetal life and remains highly expressed in the brain throughout life. It plays a key role in targeting IGFs to their receptors in developing organs [1]. It is also highly expressed by a broad range of aggressive cancers such that its ablation reduces cancer growth. IGFBP-2 has also recently been recognised to play a key role in metabolic regulation. We have been investigating the role and mechanisms of action of IGFBP-2, and have developed unique insights into its structure-function relationships. Our work has mostly focused on neuroblastoma cell lines of varying aggressiveness and motility, and our manipulations of the IGFBP-2 molecule have allowed functional characterisation. We have demonstrated that the IGFBP-2 molecule contains a critical central basic region, the heparin-binding domain (HBD), which accounts for its binding to cell surface, critical in targeting IGFs to their receptors. Ablation of this domain dramatically reduces both proliferation and motility of these cancer cells, a process also involving integrin receptors [2]. This same region of the molecule also contains a Nuclear Localisation Sequence (NLS) accounting for the ability of IGFBP-2 to enter the cell nucleus. This process leads to induction of transcription of a range of cancer-promoting genes including VEGF, promoting angiogenesis in a chick embryo model, intrinsic to carcinogenesis. Ablation of the NLS blocks these processes [2,3]. Circulating IGFBP-2 is reduced in obesity and other insulin-resistant states and in animal models can enhance insulin sensitivity. It is regulated by the insulin sensitiser, leptin, and in a sheep model we have demonstrated that centrally administered leptin induces IGFBP-2 expression in skeletal muscle, via the sympathetic nervous system. Similarly, leptin applied directly to cultured skeletal muscle cells induces IGFBP-2 expression, leading to enhanced insulin sensitivity. This suggests that IGFBP-2 may mediate leptin’s insulin-sensitising effects [4]. IGFBP-2 also acts on visceral, but not subcutaneous adipose tissue, inhibiting fat accumulation, an effect not seen when the HBD region is mutated or integrin blockade is applied. Thus IGFBP-2 appears to play a beneficial role in regulating the function of visceral fat, which is critical in the pathogenesis of metabolic complications of obesity. IGFBP-2 is thus a critical player in both cancer biology and in metabolic syndrome. There is potential for targeted pharmacologic manipulation of IGFBP-2 activity in order to reduce the morbidity and mortality of these major diseases in our society.