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Cytotoxicity profiles of NSC305787 and the hits from MMV400 library on K12 and K7M2 mouse osteosarcoma cells as generated by xCELLigence RTCA during 48 hr incubation

Supplemental Figure Legends

Chemical structures of the small molecule inhibitor of ezrin, NSC305787, and quinoline-containing antimalarial agents

Representative images of embryos treated with NSC305787 and the hit compounds from MMV400 library are presented with different degrees of phenotypic abnormalities at later stages of embryonic development from 1 to 5 dpf

Representative steady-state affinity curve of primary hits from MMV400 library for binding to ezrin as measured by SPR

Initial screening of primary hits for reduced cell motility phenotypes in zebrafish embryonic developmental assays

Effect of NSC305787 and the hits from MMV400 library on ezrin T567 phoshorylation

Ezrin is a member of the ERM (ezrin, radixin, moesin) family of proteins and functions as a linker between the plasma membrane and the actin cytoskeleton. Ezrin is a key driver of tumor progression and metastatic spread of osteosarcoma. We discovered a quinoline-based small molecule, NSC305787, that directly binds to ezrin and inhibits its functions in promoting invasive phenotype. NSC305787 possesses a very close structural similarity to commonly used quinoline-containing antimalarial drugs. On the basis of this similarity and of recent findings that ezrin has a likely role in the pathogenesis of malaria infection, we screened antimalarial compounds in an attempt to identify novel ezrin inhibitors with better efficacy and drug properties. Screening of Medicines for Malaria Venture (MMV) Malaria Box compounds for their ability to bind to recombinant ezrin protein yielded 12 primary hits with high selective binding activity. The specificity of the hits on ezrin function was confirmed by inhibition of the ezrin-mediated cell motility of osteosarcoma cells. Compounds were further tested for phenocopying the morphologic defects associated with ezrin suppression in zebrafish embryos as well as for inhibiting the lung metastasis of high ezrin-expressing osteosarcoma cells. The compound MMV667492 exhibited potent anti-ezrin activity in all biologic assays and had better physicochemical properties for drug-likeness than NSC305787. The drug-like compounds MMV020549 and MMV666069 also showed promising activities in functional assays. Thus, our study suggests further evaluation of antimalarial compounds as a novel class of antimetastatic agents for the treatment of metastatic osteosarcoma. Mol Cancer Ther; 14(11); 2497–507. ©2015 AACR.

Representative real time migration curves for K12 and K7M2 cells in response to vehicle (DMSO) or compound treatment as determined by electrical impedance expressed as cell index during 21 hr incubation

Ezrin links the plasma membrane to the actin cytoskeleton where it plays a pivotal role in the metastatic progression of several human cancers; however, the precise mechanistic basis for its role remains unknown. Here, we define transitions between active (phosphorylated open) and inactive (dephosphorylated closed) forms of Ezrin that occur during metastatic progression in osteosarcoma. In our evaluation of these conformations we expressed C-terminal mutant forms of Ezrin that are open (phosphomimetic T567D) or closed (phosphodeficient T567A) and compared their biologic characteristics to full-length wild-type Ezrin in osteosarcoma cells. Unexpectedly, cells expressing open, active Ezrin could form neither primary orthotopic tumors nor lung metastases. In contrast, cells expressing closed, inactive Ezrin were also deficient in metastasis but were unaffected in their capacity for primary tumor growth. By imaging single metastatic cells in the lung, we found that cells expressing either open or closed Ezrin displayed increased levels of apoptosis early after their arrival in the lung. Gene expression analysis suggested dysregulation of genes that are functionally linked to carbohydrate and amino acid metabolism. In particular, cells expressing closed, inactive Ezrin exhibited reduced lactate production and basal or ATP-dependent oxygen consumption. Collectively, our results suggest that dynamic regulation of Ezrin phosphorylation at amino acid T567 that controls structural transitions of this protein plays a pivotal role in tumor progression and metastasis, possibly in part by altering cellular metabolism. Cancer Res; 72(4); 1001–12. ©2011 AACR.

Supplementary Figure 4C-D from Insulin-Like Growth Factor-I Regulates the Liver Microenvironment in Obese Mice and Promotes Liver Metastasis

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Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chlonic IGF-1 deficiency. In contrast, these changes occured in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment. Cancer Res; 70(1); 57–67

Supplementary Figure 4A-B from Insulin-Like Growth Factor-I Regulates the Liver Microenvironment in Obese Mice and Promotes Liver Metastasis

TheAPOE4allele increases the risk for Alzheimer’s disease (AD) in a dose-dependent manner and is also associated with cognitive decline in non-demented elderly controls. In mice with targeted gene replacement (TR) of murineAPOEwith humanAPOE3orAPOE4, the latter show reduced neuronal dendritic complexity and impaired learning.APOE4TR mice also show reduced gamma oscillation power and sharp wave ripple (SWR) abundance, neuronal population activities important to learning and memory. Published work has shown that brain extracellular matrix (ECM) can reduce neuroplasticity as well as gamma power and SWR abundance, while attenuation of ECM can instead enhance these endpoints. In the present study we examine human cerebrospinal fluid (CSF) samples fromAPOE3andAPOE4individuals and brain lysates fromAPOE3andAPOE4TR mice for levels of ECM effectors that can increase matrix deposition and restrict neuroplasticity. We find that CCL5, a molecule linked to ECM deposition in liver and kidney, is increased in CSF samples fromAPOE4individuals. Levels of tissue inhibitor of metalloproteinases (TIMPs), which inhibit the activity of ECM-degrading enzymes, are also increased inAPOE4CSF as well as protein lysates fromAPOE4TR mice. Importantly, as compared to wildtype/APOE4heterozygotes, CCR5 knockout/APOE4heterozygotes show reduced TIMP levels and enhanced EEG gamma power. The latter also show improved learning and memory, suggesting that the CCR5/CCL5 axis could represent a therapeutic target forAPOE4individuals.

Neuroblastoma (NB) is a pediatric tumor of the peripheral nervous system. Treatment of the disease represents an unsolved clinical problem, as survival of patients with aggressive form of NB remains below 50%. Despite recent identification of numerous potential therapeutic targets, clinical trials validating them are challenging due to the rarity of the disease and its high patient-to-patient heterogeneity. Hence, there is a need for the accurate preclinical models that would allow testing novel therapeutic approaches and prioritizing the clinical studies, preferentially in personalized way. Here, we propose using conditional reprogramming (CR) technology for rapid development of primary NB cell cultures that could become a new model for such tests. This newly established method allowed for indefinite propagation of normal and tumor cells of epithelial origin in an undifferentiated state by their culture in the presence of Rho-associated kinase (ROCK) inhibitor, Y-27632, and irradiated mouse feeder cells. Using a modification of this approach, we isolated cell lines from tumors arising in the TH-MYCN murine transgenic model of NB (CR-NB). The cells were positive for neuronal markers, including Phox2B and peripherin and consisted of two distinct populations: mesenchymal and adrenergic expressing corresponding markers of their specific lineage. This heterogeneity of the CR-NB cells mimicked the different tumor cell phenotypes in TH-MYCN tumor tissues. The CR-NB cells preserved anchorage-independent growth capability and were successfully passaged, frozen and biobanked. Further studies are required to determine the utility of this method for isolation of human NB cultures, which can become a novel model for basic, translational, and clinical research, including individualized drug testing.

Although neuropeptide Y (NPY) is known mainly as a sympathetic neurotransmitter, growing evidence indicates its role in tumor biology. Previous studies from our laboratory and other groups suggested associations of high expression of NPY and its Y5 receptor (Y5R) with invasive and metastatic phenotypes of various tumor types; yet the direct evidence for the metastatic activity was lacking. Our recent work began to fill this gap. Using Ewing sarcoma (ES) as a model of NPY-rich tumor, we identified the NPY/Y5R axis as a crucial pathway responsible for hypoxia-induced ES bone metastasis. This osseous dissemination was driven by hypoxia-dependent over-activation of the NPY/Y5R/RhoA pathway, which led to cytokinesis defects and formation of the aneuploid ES cell population with high propensity to bone metastasis. Here, we sought to determine the impact of the Y5R signaling on overall, hypoxia-independent metastatic capabilities of ES cells. To this end, a doxycycline-inducible CRIPSR/Cas9 system was used to knockout Y5R in ES orthotopic xenografts and test its impact on metastasis and cell migration assessed by a transwell assay. The frequency of the NPY5R gene modifications was determined by sequencing and confirmed by immunohistochemistry. FISH was used to identify NPY5R gene gains in ES xenografts. RhoA activity was measured by immunocytochemistry and pull-down assay. As expected, ES/Y5R-sgRNA primary tumors in doxycycline-treated mice consisted of a heterogeneous ES cell population with variable Y5R levels. In contrast, metastases developing from these xenografts were primarily initiated by ES clones with an intact NPY5R gene. The frequency of NPY5R gene modifications in metastases from the doxycycline-treated group was markedly reduced, as compared to the primary tumors. No metastases arising from ES clones lacking intact NPY5R gene were detected. Similarly, metastasis from wild type ES xenografts was associated with a selection of clones with the NPY5R gene gain that was present in a small percent of the parental cells. Subsequent in vitro assays implicated Y5R-dependent ES cell motility driven by the activation of a key cytoskeleton regulator, RhoA, as the mechanism underlying the metastatic effects of NPY. The above results, along with our previously published data, provide direct evidence for the crucial role of the NPY/Y5R axis in metastasis. We have shown that under basal conditions the NPY/Y5R/RhoA axis promotes tumor cell motility and overall cancer cell dissemination, while over-activation of this pathway under hypoxic conditions leads to genomic instability and bone metastasis. While our study focused on ES due to its high endogenous expression of NPY and its receptors, our findings may be relevant to other malignancies rich in NPY and Y5R, such as neuroblastoma, breast and prostate cancer. Given availability of the FDA approved Y5R antagonist, NPY/Y5R pathway may be a promising target for therapies preventing cancer progression. Yet, further research is required to establish effectiveness of such pharmacological interventions. Citation Format: Mina Adnani, Sung-Hyeok Hong, Susana Galli, Akanksha Mahajan, Nouran Abualsaud, Lindsay Caprio, Jason U. Tilan, Olga Rodriguez, Hingkun Wang, Christopher Albanese, Luciane R. Cavalli, Joanna Kitlinska. Neuropeptide Y as a metastatic factor [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR018.

Retinoic acid receptor responder 1 (RARRES1) is among the most commonly methylated loci in multiple cancers. RARRES1 regulates mitochondrial and fatty acid metabolism, stem cell differentiation, and survival of immortalized cell lines

Despite Ewing sarcoma (ES) being the second most common pediatric malignancy of bone and soft tissue, few novel therapeutic approaches have been introduced over the past few decades. ES contains a pathognomonic chromosomal translocation that leads to a fusion protein between EWSR1 and an ets family member, most often FLI1. EWS-FLI1 is the most common type of fusion protein and is a well-vetted therapeutic target. A small molecule inhibitor of EWS-FLI1, YK-4-279 (YK) was developed with the intention to serve as a targeted therapy option for patients with ES. The present study investigated resistance mechanisms by developing an ES cell line specifically resistant to YK. The ES cell line A4573 was treated with YK to create resistant cells by long term continuous exposure. The results revealed that resistance in A4573 was robust and sustainable, with a >27-fold increase in IC(50) lasting up to 16 weeks in the absence of the compound. Resistant ES cells were still sensitive to standard of care drugs, including doxorubicin, vincristine and etoposide, which may be valuable in future combination treatments in the clinic. Resistant ES cells revealed an increased expression of CD99. RNA sequencing and qPCR validation of resistant ES cells confirmed an increased expression of ANO1, BRSK2 and IGSF21, and a reduced expression of COL24A1, PRSS23 and RAB38 genes. A functional association between these genes and mechanism of resistance remains to be investigated. The present study created a cell line to investigate YK resistance.

Ewing sarcoma (ES) is the second most prevalent malignant bone tumor after osteosarcoma in children and adolescents. While survival of patients with localized ES has improved, patients with metastatic ES still lack adequate therapies, which results in poor survival rates. Thus, there is an important need for new therapies targeting ES metastases and preventing its dissemnation. Previously, we have shown that ES cells constitutively express high levels of NPY and its receptors - Y1R and Y5R. However, tumor hypoxia changes expression pattern and functions of NPY system, leading to the activation of its Y2R and Y5R, which stimulate ES cell motility and invasiveness under these conditions. Hence, the goal of this study was to determine the role of NPY in hypoxia-induced ES metastases. Here, we focused on Y5R, since our data from other malignancies implicated this receptor as the major mediator of NPY's pro-metastatic effects. To this end, we used doxycycline (DOX)-inducible CRIPSR/Cas9 system to create an SK-ES1/Y5R knockout (KO) cell line. The Y5R KO significantly decreased motility of SK-ES1 cells. To determine the impact of this phenomenon on ES metastases, SK-ES1/Cas9/Y5RsgRNA cells were injected into gastrocnemius muscles of SCID/bg mice and the animals were fed with DOX+ or control diet. The Y5R KO did not affect primary tumor growth. Once the xenografts reached a volume of 0.25cm3, a femoral artery ligation (FAL) was performed in the tumor-bearing limbs to induce hypoxic conditions. Both primary tumors and their corresponding metastases were sequenced to confirm the efficiency of gene editing. Notably, majority of metastases arising in mice bearing SKES-1/Y5RsgRNA+DOX xenografts were initiated by the clones without Y5R gene modification, confirming the role of Y5R in ES dissemination. The frequency of metastases with efficient Y5R KO originating from hypoxic tumors was markedly decreased, as compared to the control group (-DOX). Moreover, Y5R KO prevented hypoxia-induced increase in osseous metastases previously reported by our group. Collectively, these data validate NPY/Y5R axis as a crucial mediator of the hypoxia-induced ES metastasis and implicate Y5R receptor as a novel target for therapies preventing ES dissemination. Importantly, the Y5R antagonist is already available and used in clinical trials. Citation Format: Mina T. Adnani, Susana Galli, Sung Hyeok Hong, Jason U. Tilan, Joanna Kitlinska. Blocking neuropeptide Y Y5 receptor prevents hypoxia-induced Ewing sarcoma metastasis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6159.

Neuroblastoma (NB) is a pediatric malignancy that originates from precursors of sympathetic neurons and expresses neuronal proteins, such as neuropeptide Y (NPY) and its receptors. NB cells constitutively express NPY Y2 receptor (Y2R), which maintains their proliferation and tumor vascularization. However, pro-apoptotic conditions additionally induce expression of Y5 receptor (Y5R), which acts as a survival factor for tumor cells. High Y5R expression was also observed in angioinvasive NB cells surrounding blood vessels, suggesting a role for this receptor in NB dissemination. Indeed, in NB patients, high serum levels of NPY associated with the presence of metastases. Hence, the goal of this study was to identify mechanisms that may underlie potential pro-metastatic effects of NPY. We have found that NPY, acting via Y5R, stimulates NB cell motility and acts as a chemotactic factor for these cells in a concentration-dependent manner. Hypoxia, a known condition promoting metastasis, increased expression of Y5R in SK-N-BE(2) and SK-N-AS NB cell lines. Consequently, hypoxic NB cells had increased motility and a chemotactic response to NPY. This increase in NPY-driven migration was fully blocked by Y5R antagonist. Pre-incubation of NB cells in hypoxia before orthotopic injections into adrenal glands of SCID/bg mice exacerbated metastasis in xenografts from both NB cell lines. In mice bearing non-MYCN amplified SK-N-AS tumors, the hypoxia-driven metastases were located in soft tissues, while MYCN-amplified SK-N-BE(2) xenografts derived from hypoxic cells exhibited enhanced dissemination to lungs. The latter pattern of metastases is also observed in NB patients with MYCN amplification. Further studies are required to determine if the hypoxia-driven increase in NB metastasis is Y5R-dependent. Altogether, our data support the role of tumor hypoxia and NPY/Y5R axis in NB dissemination. Since this pathway is also activated during chemotherapy and promotes NB cells resistance to treatment, NPY/Y5R may also be involved in the secondary dissemination of the recurrent tumors. If the role of Y5R in NB metastasis is validated in preclinical models, this NPY receptor may become a potential therapeutic target preventing the disease dissemination. Citation Format: Nouran Abualsaud, Lindsay Caprio, Sung Hyeok Hong, Susana Galli, Joanna Kitlinska. Hypoxia increases motility of neuroblastoma cells induced by the neuropeptide Y/Y5 receptor pathway and exacerbates their metastatic potential [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6157.

Ewing sarcoma is an aggressive tumor of bone and soft tissue affecting predominantly children and young adults. Tumor-specific chromosomal translocations create EWS-FLI1 and similar aberrant ETS fusion proteins that drive sarcoma development in patients. ETS family fusion proteins and over-expressed ETS proteins are also found in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) patients. Transgenic expression of EWS-FLI1 in mice promotes high penetrance erythroid leukemia with dense hepatic and splenic infiltrations. We identified a small molecule, YK-4-279, that directly binds to EWS-FLI1 and inhibits its oncogenic activity in Ewing sarcoma cell lines and xenograft mouse models. Herein, we tested in vivo therapeutic efficacy and potential side effects of YK-4-279 in the transgenic mouse model with EWS-FLI1 induced leukemia. A two-week course of treatment with YK-4-279 significantly reduced white blood cell count, nucleated erythroblasts in the peripheral blood, splenomegaly, and hepatomegaly of erythroleukemic mice. YK-4-279 inhibited EWS-FLI1 target gene expression in neoplastic cells. Treated animals showed significantly better overall survival compared to control mice that rapidly succumbed to leukemia. YK-4-279 treated mice did not show overt toxicity in liver, spleen, or bone marrow. In conclusion, this in vivo study highlights the efficacy of YK-4-279 to treat EWS-FLI1 expressing neoplasms and support its therapeutic potential for patients with Ewing sarcoma and other ETS-driven malignancies.

Ewing sarcoma (ES) develops in bones or soft tissues of children and adolescents. The presence of bone metastases is one of the most adverse prognostic factors, yet the mechanisms governing their formation remain unclear. As a transcriptional target of EWS-FLI1, the fusion protein driving ES transformation, neuropeptide Y (NPY) is highly expressed and released from ES tumors. Hypoxia up-regulates NPY and activates its pro-metastatic functions. To test the impact of NPY on ES metastatic pattern, ES cell lines, SK-ES1 and TC71, with high and low peptide release, respectively, were used in an orthotopic xenograft model. ES cells were injected into gastrocnemius muscles of SCID/beige mice, the primary tumors excised, and mice monitored for the presence of metastases. SK-ES1 xenografts resulted in thoracic extra-osseous metastases (67%) and dissemination to bone (50%) and brain (25%), while TC71 tumors metastasized to the lungs (70%). Bone dissemination in SK-ES1 xenografts associated with increased NPY expression in bone metastases and its accumulation in bone invasion areas. The genetic silencing of NPY in SK-ES1 cells reduced bone degradation. Our study supports the role for NPY in ES bone invasion and provides new models for identifying pathways driving ES metastases to specific niches and testing anti-metastatic therapeutics.

Ewing’s sarcoma (ES) is a rare and highly malignant cancer that grows in the bones or surrounding tissues mostly affecting adolescents and young adults. A chimeric fusion between the RNA binding protein EWS and the ETS family transcription factor FLI1 (EWS-FLI1), which is generated from a chromosomal translocation, is implicated in driving most ES cases by modulation of transcription and alternative splicing. The small-molecule YK-4-279 inhibits EWS-FLI1 function and induces apoptosis in ES cells. We aimed to identify both the underlying mechanism of the drug and potential combination therapies that might enhance its antitumor activity. We tested 69 anticancer drugs in combination with YK-4-279 and found that vinca alkaloids exhibited synergy with YK-4-279 in five ES cell lines. The combination of YK-4-279 and vincristine reduced tumor burden and increased survival in mice bearing ES xenografts. We determined that independent drug-induced events converged to cause this synergistic therapeutic effect. YK-4-279 rapidly induced G(2)-M arrest, increased the abundance of cyclin B1, and decreased EWS-FLI1-mediated generation of microtubule-associated proteins, which rendered cells more susceptible to microtubule depolymerization by vincristine. YK-4-279 reduced the expression of the EWS-FLI1 target gene encoding the ubiquitin ligase UBE2C, which, in part, contributed to the increase in cyclin B1. YK-4-279 also increased the abundance of proapoptotic isoforms of MCL1 and BCL2, presumably through inhibition of alternative splicing by EWS-FLI1, thus promoting cell death in response to vincristine. Thus, a combination of vincristine and YK-4-279 might be therapeutically effective in ES patients.

Hypoxia has been implicated in the metastasis of Ewing sarcoma (ES) by clinical observations and in vitro data, yet direct evidence for its pro-metastatic effect is lacking and the exact mechanisms of its action are unclear. Here, we report an animal model that allows for direct testing of the effects of tumor hypoxia on ES dissemination and investigation into the underlying pathways involved. This approach combines two well-established experimental strategies, orthotopic xenografting of ES cells and femoral artery ligation (FAL), which induces hindlimb ischemia. Human ES cells were injected into the gastrocnemius muscles of SCID/beige mice and the primary tumors were allowed to grow to a size of 250 mm3. At this stage either the tumors were excised (control group) or the animals were subjected to FAL to create tumor hypoxia, followed by tumor excision 3 days later. The efficiency of FAL was confirmed by a significant increase in binding of hypoxyprobe-1 in the tumor tissue, severe tumor necrosis and complete inhibition of primary tumor growth. Importantly, despite these direct effects of ischemia, an enhanced dissemination of tumor cells from the hypoxic tumors was observed. This experimental strategy enables comparative analysis of the metastatic properties of primary tumors of the same size, yet significantly different levels of hypoxia. It also provides a new platform to further assess the mechanistic basis for the hypoxia-induced alterations that occur during metastatic tumor progression in vivo. In addition, while this model was established using ES cells, we anticipate that this experimental strategy can be used to test the effect of hypoxia in other sarcomas, as well as tumors orthotopically implanted in sites with a well-defined blood supply route.

Neuroblastomas (NBs) are pediatric tumors that lack adequate treatment for their aggressive form, despite many efforts focusing on novel therapies. Although the disease is known to have a genetic background, its etiology cannot be explained solely by genetics. Yet, the role of environment in NB development is understudied. Thus, there are no established risk factors for NB aside from rare genetic predispositions and therefore no preventative measures. NBs arise due to defects in sympathetic neuron (SN) differentiation, which occurs in the fetus. Thus, we hypothesize that prenatal or pre-conception exposures may interfere with this process and promote NB. Maternal stress during pregnancy and paternal pre-conception stress induce neurodevelopmental defects in offspring by direct effects on fetal development or epigenetic changes, respectively. Indeed, we have previously shown that in a mouse model of NB prenatal stress interferes with SN differentiation in offspring, accelerating NB development and leading to its increased frequency and malignancy. The goal of the current study was to determine if a similar increase in risk of NB development can result from paternal pre-conception stress. To test the effect of paternal stress on NB, we subjected TH-MYCN males to 6 weeks of chronic unpredictable stress (CUS) prior to mating with wild type females and assessed the impact of stress on 1) miRNA content in the germline (RNAseq); 2) fertility and fetal survival; 3) NB frequency, latency, growth and metastasis in their hemizygous TH-MYCN offspring (periodic MRI, histological analyses). CUS resulted in significant changes in non-coding RNA content of the germline, including miRNAs and tsRNAs. Of particular interest was a stress-induced down-regulation of sperm miRNAs, including miR-200b and miR-128, which are involved in neuroblast differentiation, inhibit NB invasiveness and are inactivated in NB tumors. Paternal stress decreased the rate of successful pregnancies from 75% in controls to 37.5% and increased frequency of death in utero from 5.5% to 29.2% (p=0.02). Moreover, offspring of stressed fathers exhibited accelerated NB development (60% vs 0% of mice with tumors at 6 weeks of age for CUS and control groups, respectively; p=0.03) and growth (p=0.3), higher tumor frequency (60% vs 25% at 14 weeks of age, p=0.03), as well as a trend toward a more metastatic phenotype. However, these effects on NB formation and phenotype were observed solely in male offspring. In summary, our data provide the first evidence for the role of paternal preconception stress in NB development. If confirmed, our findings may open new avenues for NB prevention and identifying biomarkers of increased NB risk. Citation Format: Sung-Hyeok Hong, Susana Galli, Raquel Santana da Cruz, Lu Jin, Larissa Wetlisbach, Shiya Zhu, Abir Malik, Jason Tilan, Sonia de Assis, Joanna B. Kitlinska. Paternal pre-conception stress as a potential risk factor for neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2890.

Ewing Sarcoma (ES) is an aggressive malignancy that arises in children and young adults. Although the survival for patients with localized tumors is relatively high, the metastatic form carries a dismal prognosis, particularly when bone metastases are present. The frequency of metastases and osseous dissemination increases in patients with necrotic ES tumors. In line with this, hypoxia, the major cause of tumor necrosis, has been shown to increase metastatic potential of ES cells. Previous data from our laboratory demonstrated that in an ES orthotopic xenograft model, primary tumor hypoxia specifically promotes bone metastasis, which is associated with accumulation of cells with enlarged nuclei and frequent chromosome gains in bone invasion areas. We have also shown that the progeny of hypoxia-induced polyploid ES cells (ES≈4n cells) preferentially metastasized to bone. Thus, the goal of our study was to determine the mechanisms enabling osseous dissemination of ES≈4n cells. To this end, we used FUCCI Cell Cycle Sensor followed by DNA staining with Hoechst 33342 and cell sorting to isolate tetraploid cells (4n) from hypoxia-exposed SK-ES1 ES cells. Subsequently, we compared the metastatic properties of their progeny (H-SK-ES1≈4n) with a diploid cell population selected from normoxic SK-ES1 cells (N-SK-ES1-2n cells). We have found that H-SK-ES1≈4n cells have increased motility and invasiveness, as compared to the N-SK-ES1-2n cells. H-SK-ES1≈4n cells had also an increased ability to grow in hypoxia in 2D culture and in soft agar. In line with this, H-SK-ES1≈4n cells were highly sensitive to a glycolysis inhibitor, 2D-glucose, but not an inhibitor of oxidative phosphorylation, metformin. Moreover, H-SK-ES1≈4n cells were more sensitive than controls to a growth-inhibitory effect of AICAR, a blocker of anabolic metabolism. In contrary, the tetraploid cell progeny were highly resistant to doxorubicin, particularly under hypoxic conditions, which in contrast sensitized N-SK-ES1-2n and wild type SK-ES1 cells to chemotherapy. Altogether, our data implicate the following mechanisms underlying osseous dissemination of the hypoxia-induced poplyploid cell progeny: 1) increased motility and invasiveness facilitating escape from the primary tumor; 2) ability to survive under low oxygen tension characteristic for bone tissue. Moreover, we have shown that the cells initiating bone dissemination are highly resistant to conventional chemotherapy, while strategies targeting their metabolic dependencies may be more successful in treatment of patients with bone metastases. Citation Format: Shiya Zhu, Akanksha Mahajan, Sung-Hyeok Hong, Susana Galli, Congyi Lu, You-Shin Chen, Sara Misiukiewicz, Stacey Chung, Jason Tilan, Joanna B. Kitlinska. Hypoxia-induced phenotypic and metabolic changes in Ewing sarcoma cells trigger bone metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3664.

Neuroblastoma (NB) is a pediatric malignancy that originates from precursors of the sympathetic neurons and expresses neuronal proteins, such as neuropeptide Y (NPY). NPY is a neurotransmitter released from sympathetic nerves, acting via its Y1-Y5 receptors (Y1R-Y5R). NB cells constitutively express Y2R, while Y5R is induced in pro-apoptotic conditions. Our previous data indicated that Y2R is involved in NB cell proliferation and angiogenesis, while Y5R acts as a pro-survival factor. In NB patients, elevated serum NPY levels are associated with poor prognosis and metastasis. Interestingly, in NB tissues, tumor cells with angioinvasive phenotype have a strong expression of Y5R on the leading edge of the penetrating cell. Thus, the goal of our study was to determine the role of NPY and its receptors in NB dissemination. To this end, we assessed the effect of NPY system perturbations on NB cell motility (IncuCyte Live Cell Analysis system), cytoskeleton organization (phalloidin staining) and activity of a cytoskeleton regulator, RhoA (ICC, pull-down assay). The role of particular NPY receptors in these processes was validated by their overexpression in CHO-K1 cells. Treating NB cells with NPY stimulated NB cell migration in a dose-dependent manner, with a peak of activity at 10-8M and lower effects at higher and lower peptide concentrations. This effect was inhibited by Y5R antagonist, while in some cell lines further reduction was observed when combining Y5R and Y2R antagonists. The stimulatory effect of NPY on cell migration was associated with cytoskeleton remodeling, which included a higher number of filopodia positive for Y5R and co-localization of Y5R with an active form of RhoA at both leading and trailing edges of a migrating cell. In line with this role for Y5R in NB motility, expression of this receptor was up-regulated by hypoxia, a known pro-metastatic factor. Consistent with the results on native NB cells, overexpression of Y5R in CHO-K1 cells significantly increased their motility, while transfection with Y1R or Y2R had no such effect. Stimulation of CHO-K1/Y5R cells with NPY increased migration in a dose-dependent manner, while blocking Y5R inhibited cell motility. Moreover, NPY exerted a chemotactic effect for CHO-K1/Y5R cells. Like in NB cells, in CHO-K1 transfectants, Y5R co-localized with active RhoA in both leading and trailing edges of migrating cells. In line with this, CHO-K1/Y5R cells had elevated basal RhoA activity, while NPY stimulation further increased RhoA-GTP levels. Altogether, our data implicate Y5R as the main NPY receptor mediating its stimulatory effect on cell motility. In NB cells, Y2R may further enhance this effect. The Y5R-induced cell motility is associated with cytoskeleton remodeling driven by RhoA activation. The concentration-dependent activity of NPY and its chemotactic effect indicates that the peptide may spatially regulate NB cell migration within tumor tissue. Citation Format: Nouran Abualsaud, Lindsay Caprio, Abrar Bakr, Lamia Alamri, Ewa Krawczyk, Susana Galli, Sung Hyeok Hong, Joanna Kitlinska. Neuropeptide Y stimulates neuroblastoma cell migration via Y5R/RhoA pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3663.

// Sung-Hyeok Hong 1,* , Sarah. E. Youbi 1,* , S. Peter Hong 2 , Bhaskar Kallakury 3 , Phillip Monroe 2 , Hayriye V Erkizan 1 , Julie S. Barber-Rotenberg 1 , Peter Houghton 4 , Aykut Uren 1 , Jeffrey A. Toretsky 1 1 Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA 2 Battelle Memorial Institute, Health and Life Sciences, Columbus, OH, USA 3 Department of Pathology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA 4 Nationwide Children’s Research Institute, Center for Childhood Cancer, Columbus, USA * These authors contributed equally Correspondence: Jeffrey A. Toretsky, email: // Keywords : YK-4-279, EWS-FLI1, Ewing Sarcoma, rat xenograft, pharmacokinetic modeling Received : October 11, 2013 Accepted : November 9, 2013 Published : November 11, 2013 Abstract Transcription factors have long been deemed ‘undruggable’ targets for therapeutics. Enhanced recognition of protein biochemistry as well as the need to have more targeted approaches to treat cancer has rendered transcription factors approachable for therapeutic development. Since transcription factors lack enzymatic domains, the specific targeting of these proteins has unique challenges. One challenge is the hydrophobic microenvironment that affects small molecules gaining access to block protein interactions. The most attractive transcription factors to target are those formed from tumor specific chromosomal translocations that are validated oncogenic driver proteins. EWS-FLI1 is a fusion protein that results from the pathognomonic translocation of Ewing sarcoma (ES). Our past work created the small molecule YK-4-279 that blocks EWS-FLI1 from interacting with RNA Helicase A (RHA). To fulfill long-standing promise in the field by creating a clinically useful drug, steps are required to allow for in vivo administration. These investigations identify the need for continuous presence of the small molecule protein-protein inhibitor for a period of days. We describe the pharmacokinetics of YK-4-279 and its individual enantiomers. In vivo studies confirm prior in vitro experiments showing (S)-YK-4-279 as the EWS-FLI1 specific enantiomer demonstrating both induction of apoptosis and reduction of EWS-FLI1 regulated caveolin-1 protein. We have created the first rat xenograft model of ES, treated with (S)-YK-4-279 dosing based upon PK modeling leading to a sustained complete response in 2 of 6 ES tumors. Combining laboratory studies, pharmacokinetic measurements, and modeling has allowed us to create a paradigm that can be optimized for in vivo systems using both in vitro data and pharmacokinetic simulations. Thus, (S)-YK-4-279 as a small molecule drug is ready for continued development towards a first-in-human, first-in-class, clinical trial.

International audience; Ewing sarcoma (ES) involves a tumor-specific chromosomal translocation that produces the EWS-FLI1 protein, which is required for the growth of ES cells both in vitro and in vivo. However, an EWS-FLI1-driven transgenic mouse model is not currently available. Here, we present data from six independent laboratories seeking an alternative approach to express EWS-FLI1 in different murine tissues. We used the Runx2, Col1a2.3, Col1a3.6, Prx1, CAG, Nse, NEFL, Dermo1, P0, Sox9 and Osterix promoters to target EWS-FLI1 or Cre expression. Additional approaches included the induction of an endogenous chromosomal translocation, in utero knock-in, and the injection of Cre-expressing adenovirus to induce EWS-FLI1 expression locally in multiple lineages. Most models resulted in embryonic lethality or developmental defects. EWS-FLI1-induced apoptosis, promoter leakiness, the lack of potential cofactors, and the difficulty of expressing EWS-FLI1 in specific sites were considered the primary reasons for the failed attempts to create a transgenic mouse model of ES.

Ezrin is a member of the ERM (ezrin/radixin/moesin) family of proteins that links cortical cytoskeleton to the plasma membrane. High expression of ezrin correlates with poor prognosis and metastasis in osteosarcoma. In this study, to uncover specific cellular responses evoked by ezrin inhibition that can be used as a specific pharmacodynamic marker(s), we profiled global gene expression in osteosarcoma cells after treatment with small molecule ezrin inhibitors, NSC305787 and NSC668394. We identified and validated several up-regulated integrated stress response genes including PTGS2, ATF3, DDIT3, DDIT4, TRIB3, and ATF4 as novel ezrin-regulated transcripts. Analysis of transcriptional response in skin and peripheral blood mononuclear cells from NSC305787-treated mice compared with a control group revealed that, among those genes, the stress gene DDIT4/REDD1 may be used as a surrogate pharmacodynamic marker of ezrin inhibitor compound activity. In addition, we validated the anti-metastatic effects of NSC305787 in reducing the incidence of lung metastasis in a genetically engineered mouse model of osteosarcoma and evaluated the pharmacokinetics of NSC305787 and NSC668394 in mice. In conclusion, our findings suggest that cytoplasmic ezrin, previously considered a dormant and inactive protein, has important functions in regulating gene expression that may result in down-regulation of stress response genes.

Ezrin links the plasma membrane to the actin cytoskeleton where it plays a pivotal role in the metastatic progression of several human cancers; however, the precise mechanistic basis for its role remains unknown. Here, we define transitions between active (phosphorylated open) and inactive (dephosphorylated closed) forms of Ezrin that occur during metastatic progression in osteosarcoma. In our evaluation of these conformations we expressed C-terminal mutant forms of Ezrin that are open (phosphomimetic T567D) or closed (phosphodeficient T567A) and compared their biologic characteristics to full-length wild-type Ezrin in osteosarcoma cells. Unexpectedly, cells expressing open, active Ezrin could form neither primary orthotopic tumors nor lung metastases. In contrast, cells expressing closed, inactive Ezrin were also deficient in metastasis but were unaffected in their capacity for primary tumor growth. By imaging single metastatic cells in the lung, we found that cells expressing either open or closed Ezrin displayed increased levels of apoptosis early after their arrival in the lung. Gene expression analysis suggested dysregulation of genes that are functionally linked to carbohydrate and amino acid metabolism. In particular, cells expressing closed, inactive Ezrin exhibited reduced lactate production and basal or ATP-dependent oxygen consumption. Collectively, our results suggest that dynamic regulation of Ezrin phosphorylation at amino acid T567 that controls structural transitions of this protein plays a pivotal role in tumor progression and metastasis, possibly in part by altering cellular metabolism. Cancer Res; 72(4); 1001–12. ©2011 AACR.

Neuroblastoma (NB) is a pediatric malignant neoplasm of sympathoadrenal origin. Challenges in its management include stratification of this heterogeneous disease and a lack of both adequate treatments for high-risk patients and noninvasive biomarkers of disease progression. Our previous studies have identified neuropeptide Y (NPY), a sympathetic neurotransmitter expressed in NB, as a potential therapeutic target for these tumors by virtue of its Y5 receptor (Y5R)–mediated chemoresistance and Y2 receptor (Y2R)–mediated proliferative and angiogenic activities. The goal of this study was to determine the clinical relevance and utility of these findings. Expression of NPY and its receptors was evaluated in corresponding samples of tumor RNA, tissues, and sera from 87 patients with neuroblastic tumors and in tumor tissues from the TH-MYCN NB mouse model. Elevated serum NPY levels correlated with an adverse clinical presentation, poor survival, metastasis, and relapse, whereas strong Y5R immunoreactivity was a marker of angioinvasive tumor cells. In NB tissues from TH-MYCN mice, high immunoreactivity of both NPY and Y5R marked angioinvasive NB cells. Y2R was uniformly expressed in undifferentiated tumor cells, which supports its previously reported role in NB cell proliferation. Our findings validate NPY as a therapeutic target for advanced NB and implicate the NPY/Y5R axis in disease dissemination. The correlation between elevated systemic NPY and NB progression identifies serum NPY as a novel NB biomarker.

The development of metastasis is the most significant cause of death for both canine and human patients with osteosarcoma (OS). Ezrin has been associated with tumour progression and metastasis in human, canine and murine OS. Ezrin activation is dynamically regulated by protein kinase C (PKC) during metastatic progression in human and murine OS. To include the dog in the development of therapeutics that target ezrin biology, we characterized four new canine OS cell lines and confirmed the relationship between PKC and ezrin in these cells. Three of four cell lines formed tumours in mice that were histologically consistent with OS. All cell lines were markedly aneuploid and expressed ezrin and PKC. Finally, both ezrin phosphorylation and cell migration were inhibited using a PKC inhibitor. These data suggest that an association between PKC-mediated activation of ezrin and the metastatic phenotype in canine OS cells.

Tumor dissemination and relapse are the major problems in Ewing sarcoma (ES) treatment, yet the mechanisms driving these processes are unknown. To elucidate the routes of ES metastatic spread, we used an orthotopic xenograft model. ES cells were injected into the gastrocnemius muscles of SCID/beige mice. Once the primary tumors reached the desired volume, they were excised by limb amputation. Subsequently, tumor dissemination was monitored by MRI and confirmed by histopathologic analysis. Interestingly, aside from typical hematogenous metastases, such as bone and lung lesions, we have also observed frequent perineural tumor dissemination manifested by the presence of migratory ES cells along the nerves adjacent to the primary tumors. This phenomenon was associated with formation of recurrent tumors at the amputation sites, as well as pelvic tumors with spine involvement. Interestingly, the level of perineural invasion (PNI) was dependent on the expression of neuropeptide Y (NPY) in ES cells. NPY is a neuronal protein released from peripheral sympathetic neurons, but also highly expressed in ES cells along with its receptors. The xenografts derived from ES cell lines not releasing endogenous NPY (TC71, TC32) exhibited frequent PNI in tumor-bearing limbs, as well as a high number of recurrent tumors at the surgery site and spine metastases (70% and 100% of mice with evidence of PNI for TC71 and TC32 xenografts, respectively). This phenomenon was less common in ES xenografts derived from NPY-rich SK-ES1 cells (17% of mice with signs of PNI). In line with these observations, NPY knockdown in SK-ES1 xenografts drastically accelerated formation of spinal tumors (60% of mice). Notably, in 40% of mice bearing SK-ES1/NPY shRNA xenografts the spinal tumors developed before the primary tumor growth was detectable at the site of ES cell injection. Thus, our in vivo experiments suggested that a lack of endogenous NPY in ES cells expressing high levels of its receptors triggers chemotactic effects of this peptide released from neighboring peripheral nerves, facilitating PNI. Indeed, in a transwell migration assay, NPY exerted significant chemotactic activity in SK-ES1/NPY shRNA cells, but not in the original SK-ES1 cell line. An even more profound chemotactic effect specific to the SK-ES1/NPY shRNA cells was observed with NPY-rich conditioned media obtained from neuroblastoma cells, which can serve as a model of peripheral sympathetic neurons. Further studies are required to determine which NPY receptors are responsible for its chemotactic properties. If the presence of perineural tumor growth is confirmed in human tumors, factors responsible for PNI in ES, e.g., NPY receptors, may become targets for novel therapies preventing disease dissemination and recurrence. Citation Format: Susana Galli, Sung-Hyeok Hong, Jason U. Tilan, Mina Adnani, Shiya Zhu, Yassi Fallah, Yi-Chien Lee, Olga Rodriguez, Chris Albanese, Ewa Izycka-Swieszewska, Joanna Kitlinska. Perineural invasion in Ewing sarcoma—a novel mechanism and new therapeutic opportunities [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B13.

Treating metastatic disease remains a major obstacle in oncology. Neuropeptide Y (NPY) and its Y5 receptor (Y5R) are expressed in a number of malignancies, including pediatric tumors Ewing sarcoma (ES) and neuroblastoma (NB). Our previous clinical and experimental data implicated NPY/Y5R axis in ES and NB metastasis. We have shown that Y5R is highly expressed in angioinvasive NB cells, while elevated release of NPY from NB tumors associates with metastatic disease and poor clinical outcome. Additionally, hypoxia-induced over-activation of NPY/Y5R pathway in ES tumors, which express particularly high levels of Y5R, led to formation of polyploid cells that give rise to chromosomally unstable, metastatic progeny. This phenomenon was reproduced in CHO-K1 cells over-expressing Y5R, which became polyploid due to a cytokinesis defect. Altogether, our data suggested a role of the NPY/Y5R pathway in the regulation of cell migration and cytokinesis, processes essential in tumor growth and dissemination. Thus, the goal of our study was to determine mechanisms of NPY/Y5R actions. We have found that in both CHO-K1/Y5R transfectants and ES cells, Y5R stimulation activated an essential cytoskeleton regulator, RhoA, activity of which is tightly controlled in a spatial and temporal manner during both cell migration and cytokinesis. This data was confirmed by strong co-localization of Y5R and active RhoA in all cell types. In non-dividing cells, expression of Y5R and active RhoA was limited, while their levels were higher in mitotic cells. Notably, in CHO-K1 cells over-expressing Y5R, both Y5R and RhoA accumulated in the narrow zone of the cleavage furrow at the abscission phase of cytokinesis. Such RhoA activation at this stage was previously shown to trigger cytokinesis defects. The concurrent changes in subcellular localization of Y5R and active RhoA were also observed in migratory cells. In single cell migration, both Y5R and active RhoA accumulated on the trailing and leading edges of the cells, while in the cells migrating collectively their expression was elevated in those present at the front of the moving colony. Strong Y5R/active Rho-A co-localization was also observed in membrane blebs of cells in amoebal migration mode. The role of Y5R in stimulation of cell migration was confirmed by transwell assay, in which Y5R antagonist significantly inhibited NPY-induced migration of NB and ES cells. Altogether, our data support the role of NPY/Y5R/RhoA pathway in regulation of cytoskeleton functions. The stimulation of this pathway promotes cell migration, while its over-activation may lead to cytokinesis defects and chromosomal instability, both of which are essential processes in tumor progression. Further studies are required to determine if these functions of the NPY/Y5R/RhoA pathway contribute to metastasis and validate Y5R as a potential therapeutic target. Citation Format: Nouran Abualsaud, Congyi Lu, Akanksha Mahajan, Abrar Bakr, Shiya Zhu, Lindsay Caprio, Sung Hyeok Hong, Joanna Kitlinska. The role of neuropeptide Y and its Y5 receptor in RhoA-mediated regulation of cytokinesis and cell motility [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4143.

Ewing sarcoma (ES) is a pediatric malignancy affecting bones and soft tissues. The presence of metastases is associated with poor prognosis, particularly in patients with dissemination to the bone. ES cells produce and secrete high levels of neuropeptide Y (NPY), a 36-amino acid neurotransmitter normally released from peripheral sympathetic neurons, and express its receptors. Our previous studies in an ES xenograft model demonstrated that the severity of bone destruction in primary tumors and incidence of osseous metastases positively correlate with levels of NPY release and are significantly decreased with NPY shRNA. Thus, the goal of our study was to determine the mechanism of this NPY-induced osteolytic effect. Since tumor bone invasion and metastasis is associated with changes in osteolytic and osteogenic activity within bone, we assessed osteoblast and osteoclast content in bones adjacent to the ES xenografts. No significant difference in osteoblast number was observed between bones within ES xenografts with high and low NPY levels. However, TRAP assay showed that ES tumors secreting high NPY levels had significantly increased osteoclast density on the border of the bone-tumor interface, as compared to tumor tissues with minimal NPY secretion or treated with NPY shRNA. To identify the mechanisms underlying these osteolytic actions of NPY, we tested its effect on osteoclast recruitment and differentiation. Transwell migration assay showed that osteoclast precursors, RAW 264.7 murine macrophages, were recruited at significantly higher levels to the conditioned media from ES cells with high NPY release, as compared to those cells exposed to conditioned media from NPY-low ES cells. Similarly, ES-conditioned media with high NPY content had a higher ability to stimulate differentiation of RAW 264.7 cells into osteoclasts than those obtained from NPY-low ES cells. Both of these effects were exacerbated by hypoxic conditions, known to upregulate NPY and its Y5 receptors (Y5R) in ES cells. Blocking the expression of NPY and Y5R in ES cells with shRNA inhibited macrophage recruitment and osteoclastogenesis, and decreased RANKL content in conditioned media from NPY-high ES cells. Altogether, these data suggest that the NPY/Y5R autocrine loop stimulates the release of RANKL from ES cells, promoting macrophage recruitment and consequent osteoclast differentiation. Therefore, increased NPY secretion could have a significant impact on shifting bone homeostasis to promote osteolysis, bone invasion, and osseous metastasis. Further studies are needed to identify other factors released by tumor cells secreting high NPY levels and to test Y5R antagonists as a potential therapeutic option to inhibit these processes. Importantly, aside from ES, the above findings may be relevant to other NPY-rich tumors metastasizing to the bone, such as neuroblastoma. Citation Format: Richard Garner, Emily Hong, Shiya Zhu, Mina Adnani, Sung-Hyeok Hong, Susana Galli, Joanna Kitlinska. Neuropeptide Y promotes osteolytic activity during bone invasion and metastasis in Ewing sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4147.

Ewing sarcoma (ES) is a pediatric tumor driven by EWS-ETS fusion proteins that carries dismal prognosis in its metastatic form. Nevertheless, the factors triggering metastatic processes in ES remain unknown. Even though ES is not considered genomically unstable, the presence of tumor cells with complex karyotypes and high chromosome number is one of a few known adverse prognostic factors, suggesting an acquired chromosomal instability (CIN) as a driver of ES progression. Moreover, worse patient survival correlates with tumor hypoxia, which associates with multiple metastases and dissemination to the bone. Interestingly, hypoxia is also a factor up-regulating neuropeptide Y (NPY) and its Y5 receptor (Y5R) in ES cells. Such an up-regulation has been shown to activate growth-promoting and prometastatic functions of the NPY in these tumors. Previously we have shown that: 1) metastatic progression of ES associates with increase in frequency of polyploid cells and CIN; 2) this effect is triggered by tumor hypoxia; 3) tumor hypoxia promotes formation of bone metastases and the large polyploid cells accumulate in the areas of bone invasion; 4) overactivation of NPY/Y5R pathway leads to cytokinesis defects and polyploidy; and 5) expression of NPY and Y5R increases in bone, but not soft tissue metastases. Based on these observations we hypothesize that polyploid tumor cells arising in hypoxic tumors are responsible for ES bone metastases and thereby poor clinical outcome observed in ES patients with hypoxic tumors. We also propose NPY/Y5R as a trigger of these processes. Thus, the goal of our study was to test the metastatic potential of ES polyploid cells and determine if blocking NPY/Y5R pathway will prevent their formation. To this end, we performed in vitro purification of the 4N-G1 phase cell population from hypoxic SK-ES-1 cell line using FUCCI technology. The progeny of these cells, SK-ES1-4N cells, was characterized for its tumorigenic and metastatic potential in vitro and in vivo. Using soft agar and proliferation assays in standard and low attachment plates, we have shown that under hypoxic conditions SK-ES1-4N cells have enhanced anchorage-independent growth and capability to form colonies. In an orthotopic xenograft model, tissues and cells derived from primary tumors and metastases exhibited broader range of cell and nuclear sizes and increased ploidy, as compared to the tumors from original SK-ES-1 cells, confirming their high CIN. Strikingly, in this model the SK-ES1-4N xenografts metastasized almost exclusively to bones. Bone lesions constituted 83% of total metastases in mice bearing SK-ES1-4N tumors, while only 25% of metastases from the original SK-ES1 xenografts were localized to the bones. To determine if the increase in CIN accompanying ES progression can be prevented by blocking NPY/Y5R pathway, the SK-ES1 primary tumors were treated with Y5R antagonists, CGP 71683. The Y5R blockade decreased frequency of polyploid cells in the large, hypoxic tumors to the levels observed in nonhypoxic ES. Altogether, our findings support the role for polyploidy in ES bone metastasis and implicate the hypoxia-induced activation of the NPY/Y5R axis as its potential trigger. This abstract is also being presented as Poster B34. Citation Format: Akanksha Mahajan, Sung-Hyeok Hong, Susana Galli, Congyi Lu, Shiya Zhu, Jason Tilan, Luciane Cavalli, Joanna Kitlinska. Hypoxia, polyploidy, neuropeptide Y, and Ewing sarcoma bone metastases: Is there a link? [abstract]. In: Proceedings of the AACR Conference on Advances in Sarcomas: From Basic Science to Clinical Translation; May 16-19, 2017; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(2_Suppl):Abstract nr PR15.

Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chlonic IGF-1 deficiency. In contrast, these changes occured in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment. Cancer Res; 70(1); 57–67

The insulin-like growth factor I (IGF-I) signaling pathway has been shown to play an important role in several aspects of cancer biology, including metastasis. The aim of this study was to define the contribution of serum (endocrine) and local (tumour microenvironment) IGF-I on osteosarcoma tumour growth and metastasis, a cancer that is known to be dependent on the IGF-I axis. To test this hypothesis, we evaluated the primary tumour growth and metastatic progression of K7M2 murine osteosarcoma cells injected to a genetically engineered mouse [liver-specific IGF-I deficient (LID)] in which serum IGF-I levels are reduced by 75%, while maintaining expression of IGF-I in normal tissues. We first demonstrated that IGF-I in the tumour and the tumour-microenvironment were maintained in the LID mice. Within this designed model, there was no difference in primary tumour growth or in pulmonary metastasis in LID mice compared to control mice. Furthermore, there was no difference in the number or localization of single metastatic cells immediately after their arrival in the lungs of LID mice and control mice, as analysed by single cell video microscopy. Collectively, these data suggest that marked reduction in serum IGF-I is not sufficient to slow the progression of either primary or metastatic models of osteosarcoma.

Ezrin is a member of the ERM (ezrin, radixin, moesin) protein family and links F-actin to the cell membrane following phosphorylation. Ezrin has been associated with tumor progression and metastasis in several cancers including the pediatric solid tumors, osteosarcoma and rhabdomyosarcoma. In this study, we were surprised to find that ezrin was not constitutively phosphorylated but rather was dynamically regulated during metastatic progression in osteosarcoma. Metastatic osteosarcoma cells expressed phosphorylated ERM early after their arrival in the lung, and then late in progression, only at the invasive front of larger metastatic lesions. To pursue mechanisms for this regulation, we found that inhibitors of PKC (protein kinase C) blocked phosphorylation of ezrin, and that ezrin coimmunoprecipitated in cells with PKCalpha, PKCiota and PKCgamma. Furthermore, phosphorylated forms of ezrin and PKC had identical expression patterns at the invasive front of pulmonary metastatic lesions in murine and human patient samples. Finally, we showed that the promigratory effects of PKC were linked to ezrin phosphorylation. These data are the first to suggest a dynamic regulation of ezrin phosphorylation during metastasis and to connect the PKC family members with this regulation.