Therapeutic opportunities in Ewing sarcoma: EWS-FLI inhibition via LSD1 targeting

FLI1 in PBMCs contributes to elevated inflammation in combat-related posttraumatic stress disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition with significant public health implications that arise following exposure to traumatic events. Recent studies highlight the involvement of immune dysregulation in PTSD, characterized by elevated inflammatory markers. However, the precise mechanisms underlying this immune imbalance remain unclear. Previous research has implicated friend leukemia virus integration 1 (FLI1), an erythroblast transformation-specific (ETS) transcription factor, in inflammatory responses in sepsis and Alzheimer's disease. Elevated FLI1 levels in peripheral blood mononuclear cells (PBMCs) have been linked to lupus severity. Yet, FLI1's role in PTSD-related inflammation remains unexplored. In our study, PBMCs were collected from Veterans with and without PTSD. We found significantly increased FLI1 expression in PBMCs from PTSD-afflicted Veterans, particularly in CD4+ T cells, with no notable changes in CD8+ T cells. Stimulation with LPS led to heightened FLI1 expression and elevated levels of inflammatory cytokines IL-6 and IFNγ in PTSD PBMCs compared to controls. Knockdown of FLI1 using Gapmers in PTSD PBMCs resulted in a marked reduction in inflammatory cytokine levels, restoring them to control group levels. Additionally, co-culturing PBMCs from both control and PTSD Veterans with the human brain microglia cell line HMC3 revealed increased inflammatory mediator levels in HMC3. Remarkably, HMC3 cells co-cultured with PTSD PBMCs treated with FLI1 Gapmers exhibited significantly lower inflammatory mediator levels compared to control Gapmer-treated PTSD PBMCs. These findings suggest that suppressing FLI1 may rebalance immune activity in PBMCs and mitigate microglial activation in the brain. Such insights could provide novel therapeutic strategies for PTSD.

Characterization of transcriptional heterogeneity and novel therapeutic targets using single cell RNA-sequencing of primary and circulating Ewing sarcoma cells

Ewing sarcoma is the second most common bone cancer in children, accounting for 2% of pediatric cancer diagnoses. Patients who present with metastatic disease at the time of diagnosis have a dismal prognosis, compared to the >70% 5-year survival of those with localized disease. Here, we utilized single cell RNA-sequencing to characterize the transcriptional landscape of primary Ewing sarcoma tumors and surrounding tumor microenvironment (TME). Copy-number analysis identified subclonal evolution within patients prior to treatment. Primary tumor samples demonstrate a heterogenous transcriptional landscape with several conserved gene expression programs, including those composed of genes related to proliferation and EWS targets. Single cell RNA-sequencing and immunofluorescence of circulating tumor cells at the time of diagnosis identified TSPAN8 as a novel therapeutic target.

Cadherin-11 contributes to the heterogenous and dynamic Wnt-Wnt-β-catenin pathway activation in Ewing sarcoma

Ewing sarcoma is the second most common bone cancer in children, and while patients who present with metastatic disease at the time of diagnosis have a dismal prognosis. Ewing sarcoma tumors are driven by the fusion gene EWS/Fli1, and while these tumors are genetically homogenous, the transcriptional heterogeneity can lead to a variety of cellular processes including metastasis. In this study, we demonstrate that in Ewing sarcoma cells, the canonical Wnt/β-Catenin signaling pathway is heterogeneously activated in vitro and in vivo, correlating with hypoxia and EWS/Fli1 activity. Ewing sarcoma cells predominantly express β-Catenin on the cell membrane bound to CDH11, which can respond to exogenous Wnt ligands leading to the immediate activation of Wnt/β-Catenin signaling within a tumor. Knockdown of CDH11 leads to delayed and decreased response to exogenous Wnt ligand stimulation, and ultimately decreased metastatic propensity. Our findings strongly indicate that CDH11 is a key component of regulating Wnt//β-Catenin signaling heterogeneity within Ewing sarcoma tumors, and is a promising molecular target to alter Wnt//β-Catenin signaling in Ewing sarcoma patients.

Anticancer Drugs of Lysine Specific Histone Demethylase-1 (LSD1) Display Variable Inhibition on Nucleosome Substrates

Lysine specific demethylase-1 (LSD1) serves as a regulator of transcription and represents a promising epigenetic target for anticancer treatment. LSD1 inhibitors are in clinical trials for the treatment of Ewing's sarcoma (EWS), acute myeloid leukemia, and small cell lung cancer, and the development of robust inhibitors requires accurate methods for probing demethylation, potency, and selectivity. Here, the inhibition kinetics on the H3K4me2 peptide and nucleosome substrates was examined, comparing the rates of demethylation in the presence of reversible [CC-90011 (PD) and SP-2577 (SD)] and irreversible [ORY-1001 (ID) and tranylcypromine (TCP)] inhibitors. Inhibitors were also subject to viability studies in three human cell lines and Western blot assays to monitor H3K4me2 nucleosome levels in EWS (TC-32) cells, enabling a correlation of drug potency, inhibition in vitro, and cell-based studies. For example, SP-2577, a drug in clinical trials for EWS, inhibits activity on small peptide substrates (Ki = 60 ± 20 nM) using an indirect coupled assay but does not inhibit demethylation on H3K4me2 peptides or nucleosomes using direct Western blot approaches. In addition, the drug has no effect on H3K4me2 levels in TC-32 cells. These data show that SP-2577 is not an LSD1 enzyme inhibitor, although the drug may function independent of demethylation due to its cytotoxic selectivity in TC-32 cells. Taken together, this work highlights the pitfalls of using coupled assays to ascribe a drug's mode of action, emphasizes the use of physiologically relevant substrates in epigenetic drug targeting strategies, and provides insight into the development of substrate-selective inhibitors of LSD1.

Primary adrenal Ewing sarcoma: A systematic review of the literature

BACKGROUND

Ewing sarcoma (ES) is a malignant neoplasm of neuroectodermal origin and is commonly observed in children and young adults. The musculoskeletal system is the main body system impacted and ES is rarely seen in the visceral organs particularly the adrenal gland.

AIM

To present a comprehensive review of primary adrenal ES, with emphasis on diagnosis, therapy and oncological outcomes.

METHODS

A systematic review of the literature was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses 2020. PubMed/ MEDLINE, EMBASE and Google Scholar bibliographic databases were searched to identify articles from 1989 to 2022 and included patients with ES/primitive neuroectodermal tumor (PNET) of the adrenal gland. PubMed, Google Scholar and EMBASE medical databases were searched, combining the terms "adrenal", "ES" and "PNET". Demographic, clinical, pathological and oncological data of patients were analyzed by SPSS version 29.0.

RESULTS

A total of 52 studies were included for review (47 case reports and 5 case series) with 66 patients reported to have primary adrenal ES. Mean age at diagnosis was 26.4 ± 15.4 years (37.9% males, 57.6% females, sex not reported in 3 cases). The most frequent complaint was abdominal/flank pain or discomfort (46.4%) followed by a palpable mass (25.0%), and the average duration of symptoms was 2.6 ± 3.1 mo. The imaging modality of choice was computed tomography scan (81.5%), followed by magnetic resonance imaging (20.4%). Preoperative staging revealed that 17 tumors (27.9%) were metastatic and 14 patients had inferior vena cava or renal vein neoplastic thrombus at initial diagnosis. Open adrenalectomy was performed in the majority of cases (80.0%), of which 27.9% required more extensive resection. Minimally invasive surgery was attempted in 8.2% of tumors. Complete surgical resection was achieved in 89.4% of the patients. Adjuvant therapy was administered to 32 patients, in the form of chemotherapy (62.5%), radiotherapy (3.1%) or combination (34.4%). Median overall survival was 15 mo and 24-mo overall survival was 40.5%. Median disease-free survival was 10 mo and 24-mo disease-free survival was 33.3%.

CONCLUSION

The significant progress in molecular biology and genetics of ES does not reflect on patient outcomes. ES remains an aggressive tumor with a poor prognosis and high mortality.

The spectrum and significance of secondary (co-occurring) genetic alterations in sarcomas: the hallmarks of sarcomagenesis

Bone and soft tissue tumors are generally classified into complex karyotype sarcomas versus those with recurrent genetic alterations, often in the form of gene fusions. In this review, we provide an overview of important co-occurring genomic alterations, organized by biological mechanisms and covering a spectrum of genomic alteration types: mutations (single-nucleotide variations or indels) in oncogenes or tumor suppressor genes, copy number alterations, transcriptomic signatures, genomic complexity indices (e.g. CINSARC), and complex genomic structural variants. We discuss the biological and prognostic roles of these so-called secondary or co-occurring alterations, arguing that recognition and detection of these alterations may be significant for our understanding and management of mesenchymal tumors. On a related note, we also discuss major recurrent alterations in so-called complex karyotype sarcomas. These secondary alterations are essential to sarcomagenesis via a variety of mechanisms, such as inactivation of tumor suppressors, activation of proliferative signal transduction, telomere maintenance, and aberrant regulation of epigenomic/chromatin remodeling players. The use of comprehensive genomic profiling, including targeted next-generation sequencing panels or whole-exome sequencing, may be incorporated into clinical workflows to offer more comprehensive, potentially clinically actionable information. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Lysine specific demethylase 1 is a molecular driver and therapeutic target in sarcoma

Sarcomas are a diverse group of tumors with numerous oncogenic drivers, and display varied clinical behaviors and prognoses. This complexity makes diagnosis and the development of new and effective treatments challenging. An incomplete understanding of both cell of origin and the biological drivers of sarcomas complicates efforts to develop clinically relevant model systems and find new molecular targets. Notably, the histone lysine specific demethylase 1 (LSD1) is overexpressed in a number of different sarcomas and is a potential therapeutic target in these malignancies. With the ability to modify histone marks, LSD1 is a key player in many protein complexes that epigenetically regulate gene expression. It is a largely context dependent enzyme, having vastly different and often opposing roles depending on the cellular environment and which interaction partners are involved. LSD1 has been implicated in the development of many different types of cancer, but its role in bone and soft tissue sarcomas remains poorly understood. In this review, we compiled what is known about the LSD1 function in various sarcomas, to determine where knowledge is lacking and to find what theme emerge to characterize how LSD1 is a key molecular driver in bone and soft tissue sarcoma. We further discuss the current clinical landscape for the development of LSD1 inhibitors and where sarcomas have been included in early clinical trials.

Targeted Epigenetic Interventions in Cancer with an Emphasis on Pediatric Malignancies

Over the past two decades, novel hallmarks of cancer have been described, including the altered epigenetic landscape of malignant diseases. In addition to the methylation and hyd-roxymethylation of DNA, numerous novel forms of histone modifications and nucleosome remodeling have been discovered, giving rise to a wide variety of targeted therapeutic interventions. DNA hypomethylating drugs, histone deacetylase inhibitors and agents targeting histone methylation machinery are of distinguished clinical significance. The major focus of this review is placed on targeted epigenetic interventions in the most common pediatric malignancies, including acute leukemias, brain and kidney tumors, neuroblastoma and soft tissue sarcomas. Upcoming novel challenges include specificity and potential undesirable side effects. Different epigenetic patterns of pediatric and adult cancers should be noted. Biological significance of epigenetic alterations highly depends on the tissue microenvironment and widespread interactions. An individualized treatment approach requires detailed genetic, epigenetic and metabolomic evaluation of cancer. Advances in molecular technologies and clinical translation may contribute to the development of novel pediatric anticancer treatment strategies, aiming for improved survival and better patient quality of life.

The importance of fusion protein activity in Ewing sarcoma and the cell intrinsic and extrinsic factors that regulate it: A review

Accumulating evidence shows that despite clonal origins tumors eventually become complex communities comprised of phenotypically distinct cell subpopulations. This heterogeneity arises from both tumor cell intrinsic programs and signals from spatially and temporally dynamic microenvironments. While pediatric cancers usually lack the mutational burden of adult cancers, they still exhibit high levels of cellular heterogeneity that are largely mediated by epigenetic mechanisms. Ewing sarcomas are aggressive bone and soft tissue malignancies with peak incidence in adolescence and the prognosis for patients with relapsed and metastatic disease is dismal. Ewing sarcomas are driven by a single pathognomonic fusion between a FET protein and an ETS family transcription factor, the most common of which is EWS::FLI1. Despite sharing a single driver mutation, Ewing sarcoma cells demonstrate a high degree of transcriptional heterogeneity both between and within tumors. Recent studies have identified differential fusion protein activity as a key source of this heterogeneity which leads to profoundly different cellular phenotypes. Paradoxically, increased invasive and metastatic potential is associated with lower EWS::FLI1 activity. Here, we review what is currently understood about EWS::FLI1 activity, the cell autonomous and tumor microenvironmental factors that regulate it, and the downstream consequences of these activity states on tumor progression. We specifically highlight how transcription factor regulation, signaling pathway modulation, and the extracellular matrix intersect to create a complex network of tumor cell phenotypes. We propose that elucidation of the mechanisms by which these essential elements interact will enable the development of novel therapeutic approaches that are designed to target this complexity and ultimately improve patient outcomes.

Mitochondrial Dysfunction Is a Driver of SP-2509 Drug Resistance in Ewing Sarcoma

Expression of the fusion oncoprotein EWS/FLI causes Ewing sarcoma, an aggressive pediatric tumor characterized by widespread epigenetic deregulation. These epigenetic changes are targeted by novel lysine-specific demethylase-1 (LSD1) inhibitors, which are currently in early-phase clinical trials. Single-agent-targeted therapy often induces resistance, and successful clinical development requires knowledge of resistance mechanisms, enabling the design of effective combination strategies. Here, we used a genome-scale CRISPR-Cas9 loss-of-function screen to identify genes whose knockout (KO) conferred resistance to the LSD1 inhibitor SP-2509 in Ewing sarcoma cell lines. Multiple genes required for mitochondrial electron transport chain (ETC) complexes III and IV function were hits in our screen. We validated this finding using genetic and chemical approaches, including CRISPR KO, ETC inhibitors, and mitochondrial depletion. Further global transcriptional profiling revealed that altered complex III/IV function disrupted the oncogenic program mediated by EWS/FLI and LSD1 and blunted the transcriptomic response to SP-2509.

IMPLICATIONS

These findings demonstrate that mitochondrial dysfunction modulates SP-2509 efficacy and suggest that new therapeutic strategies combining LSD1 with agents that prevent mitochondrial dysfunction may benefit patients with this aggressive malignancy.

WEE1 inhibition augments CDC7 (DDK) inhibitor-induced cell death in Ewing sarcoma by forcing premature mitotic entry and mitotic catastrophe

Ewing sarcoma is an aggressive childhood cancer for which treatment options remain limited and toxic. There is an urgent need for the identification of novel therapeutic strategies. Our group has recently shown that Ewing cells rely on the S-phase kinase CDC7 (DDK) to maintain replication rates and cell viability and that DDK inhibition causes an increase in the phosphorylation of CDK1 and a significant delay in mitotic entry. Here, we expand on our previous findings and show that DDK inhibitor-induced mitotic entry delay is dependent upon WEE1 kinase. Specifically, WEE1 phosphorylates CDK1 and prevents mitotic entry upon DDK inhibition due to the presence of under-replicated DNA, potentially limiting the cytotoxic effects of DDK inhibition. To overcome this, we combined the inhibition of DDK with the inhibition of WEE1 and found that this results in elevated levels of premature mitotic entry, mitotic catastrophe, and apoptosis. Importantly, we have found that DDK and WEE1 inhibitors display a synergistic relationship with regards to reducing cell viability of Ewing sarcoma cells. Interestingly, the cytotoxic nature of this combination can be suppressed by the inhibition of CDK1 or microtubule polymerization, indicating that mitotic progression is required to elicit the cytotoxic effects. This is the first study to display the potential of utilizing the combined inhibition of DDK and WEE1 for the treatment of cancer. We believe this will offer a potential therapeutic strategy for the treatment of Ewing sarcoma as well as other tumor types that display sensitivity to DDK inhibitors.

Ewing sarcoma and related FET family translocation-associated round cell tumors: a century of clinical and scientific progress

The year 2021 marked the centenary of the first publication of a cancer termed diffuse endothelioma of bone by James Ewing. Its unique features were apparent even in the first case series he described. This new diagnosis was clearly distinct from osteogenic sarcoma and myeloma, which were already well recognized at the time. We undertake this summary to better understanding Ewing sarcoma, contrasting the logarithmic evolution of the standard of care of systemic therapy for this and related diagnoses to the exponential understanding of the molecular biology of this family of tumors. We also outline in this manuscript how the finding of genomic relatives within Ewing sarcoma itself and related tumors, first noted nearly 40 years ago, helps us appreciate the need to find therapeutic plans that are specific for each small round blue cell tumor subtype. The advent of next generation sequencing regarding previously unknown small round blue cell tumor subtypes in many ways puts us back in the shoes of James Ewing in 1921, searching anew for clues leading to better treatments for increasingly rare cancer subsets. This article is protected by copyright. All rights reserved.

Systemic Treatment of Ewing Sarcoma: Current Options and Future Perspectives

Ewing sarcoma (ES) is an uncommon malignant neoplasm, mostly affecting young adults and adolescents. Surgical excision, irradiation, and combinations of multiple chemotherapeutic agents are currently used as a multimodal strategy for the treatment of local and oligometastatic disease. Although ES usually responds to the primary treatment, relapsed and primarily refractory disease remains a difficult therapeutic challenge. The growing understanding of cancer biology and the subsequent development of new therapeutic strategies have been put at the service of research in recurrent and refractory ES, generating a great number of ongoing studies with compounds that could find superior clinical outcomes in the years to come. This review gathers the current available information on the treatment and clinical investigation of ES and aims to be a point of support for future research.

Suppression of Fli-1 protects against pericyte loss and cognitive deficits in Alzheimer's disease

Brain pericytes regulate cerebral blood flow, maintain the integrity of the blood-brain barrier (BBB) and facilitate the removal of amyloid β (Aβ) which is critical to healthy brain activity. Pericyte loss has been observed in brains from patients with Alzheimer's disease (AD) and animal models. Our previous data demonstrated that friend leukemia virus integration 1 (Fli-1), an ETS transcription factor, governs pericyte viability in murine sepsis; however, the role of Fli-1 and its impact on pericyte loss in AD remains unknown. Here, we demonstrated that Fli-1 expression was up-regulated in postmortem brains from a cohort of human AD donors and in 5xFAD mice, which corresponded with a decreased pericyte number, elevated inflammatory mediators, and increased Aβ accumulation as compared to cognitively normal individuals and WT mice. Antisense oligonucleotide Fli-1 Gapmer administrated via intrahippocampal injection decelerated pericyte loss, decreased inflammatory response, ameliorated cognitive deficits, improved BBB dysfunction, and reduced Aβ deposition in 5xFAD mice. Fli-1 Gapmer-mediated inhibition of Fli-1 protected against Aβ accumulation-induced human brain pericyte apoptosis in vitro. Overall, these studies indicate that Fli-1 contributes to pericyte loss, inflammatory response, Aβ deposition, vascular dysfunction and cognitive decline, and suggest that inhibition of Fli-1 may represent novel therapeutic strategies for AD.

Lipid metabolism within the bone micro-environment is closely associated with bone metabolism in physiological and pathophysiological stages

Recent advances in society have resulted in the emergence of both hyperlipidemia and obesity as life-threatening conditions in people with implications for various types of diseases, such as cardiovascular diseases and cancer. This is further complicated by a global rise in the aging population, especially menopausal women, who mostly suffer from overweight and bone loss simultaneously. Interestingly, clinical observations in these women suggest that osteoarthritis may be linked to a higher body mass index (BMI), which has led many to believe that there may be some degree of bone dysfunction associated with conditions such as obesity. It is also common practice in many outpatient settings to encourage patients to control their BMI and lose weight in an attempt to mitigate mechanical stress and thus reduce bone pain and joint dysfunction. Together, studies show that bone is not only a mechanical organ but also a critical component of metabolism, and various endocrine functions, such as calcium metabolism. Numerous studies have demonstrated a relationship between metabolic dysfunction in bone and abnormal lipid metabolism. Previous studies have also regarded obesity as a metabolic disorder. However, the relationship between lipid metabolism and bone metabolism has not been fully elucidated. In this narrative review, the data describing the close relationship between bone and lipid metabolism was summarized and the impact on both the normal physiology and pathophysiology of these tissues was discussed at both the molecular and cellular levels.

KDM1A and KDM3A promote tumor growth by upregulating cell cycle-associated genes in pancreatic cancer

Pancreatic cancer is a highly malignant cancer of the pancreas with a very poor prognosis. Methylation of histone lysine residues is essential for regulating cancer physiology and pathophysiology, mediated by a set of methyltransferases (KMTs) and demethylases (KDMs). This study surveyed the expression of methylation regulators functioning at lysine 9 of histone 3 (H3K9) in pancreatic lesions and explored the underlying mechanisms. We analyzed KDM1A and KDM3A expression in clinical samples by immunohistochemical staining and searching the TCGA PAAD program and GEO datasets. Next, we identified the variation in tumor growth in vitro and in vivo after knockdown of KDM1A or KDM3A and explored the downstream regulators of KDM1A and KDM3A via RNA-seq, and gain- and loss-of-function assays. Eleven H3K9 methylation regulators were highly expressed in pancreatic cancer, and only KDM1A and KDM3A expression positively correlated with the clinicopathological characteristics in pancreatic cancer. High expression of KDM1A or KDM3A positively correlated with pathological grade, lymphatic metastasis, invasion, and clinical stage. Kaplan-Meier analysis indicated that a higher level of KDM1A or KDM3A led to a shorter survival period. Knockdown of KDM1A or KDM3A led to markedly impaired tumor growth in vitro and in vivo. Mechanistically, CCNA2, a cell cycle-associated gene was partially responsible for KDM1A knockdown-mediated effect and CDK6, also a cell cycle-associated gene was partially responsible for KDM3A knockdown-mediated effect on pancreatic cancer cells. Our study demonstrates that KDM1A and KDM3A are highly expressed in pancreatic cancer and are intimately correlated with clinicopathological factors and prognosis. The mechanism of action of KDM1A or KDM3A was both linked to the regulation of cell cycle-associated genes, such as CCNA2 or CDK6, respectively, by an H3K9-dependent pathway.

Prospects for Epigenetic Targeted Therapies of Bone and Soft-Tissue Sarcomas

Targeted therapies have revolutionized cancer treatment. It is well established that alterations of chromatin configuration and modifications affect tumorigenesis of some, possibly most, bone and soft-tissue sarcomas. As epigenetic regulators play a major role in the development of bone and soft-tissue sarcomas, epigenetic drugs provide a novel potential avenue for rational targeted therapies for these aggressive cancers. The present review summarizes the application of epigenetic drugs for clinical utilization in bone and soft-tissue sarcomas and provides an overview of clinical trials currently evaluating epigenetic therapies in this space.

Epigenetic Deregulation of Apoptosis in Cancers

Cancer cells possess the ability to evade apoptosis. Genetic alterations through mutations in key genes of the apoptotic signaling pathway represent a major adaptive mechanism of apoptosis evasion. In parallel, epigenetic changes via aberrant modifications of DNA and histones to regulate the expression of pro- and antiapoptotic signal mediators represent a major complementary mechanism in apoptosis regulation and therapy response. Most epigenetic changes are governed by the activity of chromatin modifying enzymes that add, remove, or recognize different marks on histones and DNA. Here, we discuss how apoptosis signaling components are deregulated at epigenetic levels, particularly focusing on the roles of chromatin-modifying enzymes in this process. We also review the advances in cancer therapies with epigenetic drugs such as DNMT, HMT, HDAC, and BET inhibitors, as well as their effects on apoptosis modulation in cancer cells. Rewiring the epigenome by drug interventions can provide therapeutic advantage for various cancers by reverting therapy resistance and leading cancer cells to undergo apoptotic cell death.

Ewing sarcoma: investigational mono- and combination therapies in clinical trials

INTRODUCTION

Over the last decades, multi-institutional clinical trials have resulted in significant improvements in the outcomes of patients with localized Ewing sarcoma; however, those with metastatic and recurrent diseases continue to fare poorly. More recently, advancements made in understanding the biology of the disease and mechanisms of response to therapy have opened the door for the incorporation of targeted therapies. Here we review the current state of treatment for Ewing sarcoma and the most recent preclinical advancements that have the potential to translate to improved care.

AREAS COVERED

This review provides a general overview of the most recent clinical trials completed in Ewing sarcoma, as well as the preclinical and translational data that has the potential to be incorporated into clinical trials. A PubMed review as well as a review of published meeting abstracts was used to compose this review.

EXPERT OPINION

While dose-intenstifying strategies have failed to lead to improvements in outcomes for patients with the highest-risk disease, recent preclinical advancements have shed light on potential new targeted strategies. The lack of early-phase clinical trial responses should not deter us from further developing these agents, but instead should guide us in designing novel combination strategies.

Fusion protein EWS-FLI1 is incorporated into a protein granule in cells

Ewing sarcoma is driven by fusion proteins containing a low complexity (LC) domain that is intrinsically disordered and a powerful transcriptional regulator. The most common fusion protein found in Ewing sarcoma, EWS-FLI1, takes its LC domain from the RNA-binding protein EWSR1 (Ewing Sarcoma RNA-binding protein 1) and a DNA-binding domain from the transcription factor FLI1 (Friend Leukemia Virus Integration 1). EWS-FLI1 can bind RNA polymerase II (RNA Pol II) and self-assemble through its low-complexity (LC) domain. The ability of RNA-binding proteins like EWSR1 to self-assemble or phase separate in cells has raised questions about the contribution of this process to EWS-FLI1 activity. We examined EWSR1 and EWS-FLI1 activity in Ewing sarcoma cells by siRNA-mediated knockdown and RNA-seq analysis. More transcripts were affected by the EWSR1 knockdown than expected and these included many EWS-FLI1 regulated genes. We reevaluated physical interactions between EWS-FLI1, EWSR1, and RNA Pol II, and employed a cross-linking based strategy to investigate protein assemblies associated with the proteins. The LC domain of EWS-FLI1 was required for the assemblies observed to form in cells. These results offer new insights into a protein assembly that may enable EWS-FLI1 to bind its wide network of protein partners and contribute to regulation of gene expression in Ewing sarcoma.

Identification of a New Transcriptional Co-Regulator of STEAP1 in Ewing's Sarcoma

Ewing’s sarcoma (ES) is caused by a chromosomal translocation leading to the formation of the fused EWSFLI1 gene, which codes for an aberrant transcription factor EWSFLI1. The transcriptional targets of EWSFLI1 have been viewed as promising and novel drug targets in the treatment of ES. One such target is six transmembrane epithelial antigen of the prostate 1 (STEAP1), a transmembrane protein that is upregulated by EWSFLI1 in ES. STEAP1 is a hallmark of tumor invasiveness and an indicator of tumor responsiveness to therapy. EWSFLI1 binds to the STEAP1 promoter region, but the mechanism of action by which it upregulates STEAP1 expression in ES is not entirely understood. Upon analysis of the STEAP1 promoter, we predicted two binding sites for NKX2.2, another crucial transcription factor involved in ES pathogenesis. We confirmed the interaction of NKX2.2 with the STEAP1 promoter using chromatin immunoprecipitation (ChIP) analysis. We used single-molecule RNA imaging, biochemical, and genetic studies to identify the novel role of NKX2.2 in regulating STEAP1 expression in ES. Our results show that NKX2.2 is a co-regulator of STEAP1 expression and functions by interacting with the STEAP1 promoter at sites proximal to the reported EWSFLI1 sites. The co-operative interaction of NKX2.2 with EWSFLI1 in regulating STEAP1 holds potential as a new target for therapeutic interventions for ES.

Advances in the Management of Pediatric Sarcomas

PURPOSE OF REVIEW

The prognosis of pediatric patients who present with metastatic or recurrent sarcomas remains poor. In this review, we summarize the advances in the management of metastatic and relapsed pediatric sarcoma by highlighting recent and future clinical trials.

RECENT FINDINGS

Research into the identification of novel therapies for refractory pediatric sarcomas continues to advance. Outcomes have not improved in several decades underlying a need for improved understanding of the biology behind these tumors and the identification of novel therapeutic molecular targets that can be exploited pharmacologically. Multiple challenges remain for novel therapy in sarcomas such as the selection of effective targets, management of toxicities, and the tumor microenvironment. Many unique challenges remain in the treatment of patients with refractory pediatric sarcomas. Multiple strategies and targets are under investigation that hold promise.

Outcome of multidisciplinary treatment of peripheral primitive neuroectodermal tumor

Peripheral primitive neuroectodermal tumors (PNETs) constitute very rare and aggressive malignancies. To date, there are no standard guidelines for management of peripheral PNETs due to the paucity of cases arising in various body sites. Therapeutic approach is derived from Ewing sarcoma family, which currently remains multimodal. Our study retrospectively analyzed 86 PNET patients from February 1, 1998 to February 1, 2018 at Peking Union Medical College Hospital with an additional 75 patients from review of literature. The clinicopathologic and treatment plans associated with survival was investigated. Surgery, chemotherapy, female sex, small tumor size, no lymph node metastasis, R0 surgical resection, (vincristine + doxorubicin + cyclophosphamide)/(isophosphamide + etoposide) regimen, and more than 10 cycles of chemotherapy were associated with improved overall survival in univariate analysis. Surgery, more than 10 cycles of chemotherapy, and small tumor size were independent prognostic factors for higher overall survival. Our data indicates that multimodal therapy is the mainstay therapeutic approach for peripheral PNET.

Management of Refractory Pediatric Sarcoma: Current Challenges and Future Prospects

Paediatric sarcomas are a heterogeneous group of disorders constituting bone sarcoma and various soft tissue sarcomas. Almost one-third of these presents with metastasis at baseline and another one-third recur after initial curative treatment. There is a huge unmet need in this cohort in terms of curative options and/or prolongation of survival. In this review, we have discussed the current treatment options, challenges and future strategies of managing relapsed/refractory paediatric sarcomas. Upfront risk-adapted treatment with multidisciplinary management remains the main strategy to prevent future recurrence or relapse of the disease. In the case of limited local and/or systemic relapse or late relapse, initial multimodality management can be administered. In treatment-refractory cases or where cure is not feasible, the treatment options are limited to novel therapeutics, immunotherapeutic approach, targeted therapies, and metronomic therapies. A better understanding of disease biology, mechanism of treatment refractoriness, identifications of driver mutation, the discovery of novel targeted therapies, cellular vaccine and adapted therapies should be explored in relapsed/refractory cases. Close national and international collaboration for translation research is needed to fulfil the unmet need.

EWS-FLI1-regulated Serine Synthesis and Exogenous Serine are Necessary for Ewing Sarcoma Cellular Proliferation and Tumor Growth

Despite a growing body of knowledge about the genomic landscape of Ewing sarcoma, translation of basic discoveries into targeted therapies and significant clinical gains has remained elusive. Recent insights have revealed that the oncogenic transcription factor EWS-FLI1 can impact Ewing sarcoma cellular metabolism, regulating expression of 3-phosphoglycerate dehydrogenase (PHGDH), the first enzyme in de novo serine synthesis. Here, we have examined the importance of serine metabolism in Ewing sarcoma tumorigenesis and evaluated the therapeutic potential of targeting serine metabolism in preclinical models of Ewing sarcoma. We show that PHGDH knockdown resulted in decreased Ewing sarcoma cell proliferation, especially under serine limitation, and significantly inhibited xenograft tumorigenesis in preclinical orthotopic models of Ewing sarcoma. In addition, the PHGDH inhibitor NCT-503 caused a dose-dependent decrease in cellular proliferation. Moreover, we report a novel drug combination in which nicotinamide phosphoribosyltransferase (NAMPT) inhibition, which blocks production of the PHGDH substrate NAD⁺, synergized with NCT-503 to abolish Ewing sarcoma cell proliferation and tumor growth. Furthermore, we show that serine deprivation inhibited Ewing sarcoma cell proliferation and tumorigenesis, indicating that Ewing sarcoma cells depend on exogenous serine in addition to de novo serine synthesis. Our findings suggest that serine metabolism is critical for Ewing sarcoma tumorigenesis, and that targeting metabolic dependencies should be further investigated as a potential therapeutic strategy for Ewing sarcoma. In addition, the combination strategy presented herein may have broader clinical applications in other PHGDH-overexpressing cancers as well.

Management of Ewing Sarcoma Family of Tumors: A Short Description of a Rare Primitive Uterine pPNET and Literature Review

Purpose

To describe the outcome of a patient with a rare primitive uterine pPNET and to perform a review of the available data in literature, leading the clinicians to better face this rare disease.

Methods

We have rescued data regarding the multidisciplinary treatment of pPNET from the PUBMED database, highlighting also issues regarding the pathogenesis and the genetic landscape of the ESFTs (Ewing Sarcoma Family of Tumors).

Results

Ewing sarcoma and primitive neuroectodermal tumors (PNETs) are small round cell tumors presenting with different degrees of neuroectodermal differentiation. PNETs are further divided into central PNET and peripheral PNET (pPNET). Since pPNETs share the same genetic background of Ewing Sarcomas, they are considered to belong to the Ewing Sarcoma Family of Tumors (ESFTs). Multimodality treatment currently represents the best choice to offer to the affected patients.

Conclusion

Although pPNETs are generally diagnosed in children and young adults, an elderly woman aged 85 years came to our attention after a diagnosis of uterine pPNET. Her medical history is presented here, along with a literature review of the subject, highlighting the main biological, pathological and clinical features, with a hypothesis about the possible future therapeutic approaches for these rare malignancies.

Precision medicine in Ewing sarcoma: a translational point of view

Ewing sarcoma is a rare tumor that arises in bones of children and teenagers but, in 15% of the patients it is presented as a primary soft tissue tumor. Balanced reciprocal chimeric translocation t(11;22)(q24;q12), which encodes an oncogenic protein fusion (EWSR1/FLI1), is the most generalized and characteristic molecular event. Using conventional treatments, (chemotherapy, surgery and radiotherapy) long-term overall survival rate is 30% for patients with disseminated disease and 65-75% for patients with localized tumors. Urgent new effective drug development is a challenge. This review summarizes the preclinical and clinical investigational knowledge about prognostic and targetable biomarkers in Ewing sarcoma, finally suggesting a workflow for precision medicine committees.

Catalytic inhibition of KDM1A in Ewing sarcoma is insufficient as a therapeutic strategy

BACKGROUND

Ewing sarcoma and desmoplastic small round cell tumors (DSRCT) are rare and clinically aggressive sarcomas usually characterized by oncogenic fusion proteins involving EWS. Emerging studies of Ewing sarcoma have demonstrated EWS-FLI1-driven chromatin remodeling as a key aspect of tumorigenicity. In particular, the lysine-specific demethylase KDM1A/LSD1 is linked to transcriptional regulation of target genes orchestrated by the EWS portion of the fusion protein interacting with repressive chromatin-remodeling complexes. Consistent with this model, depletion of KDM1A supports it is a molecular therapeutic target in Ewing sarcoma cells, but effective drugs need to be identified.

PROCEDURE

A comprehensive phenotypic analysis of the effects of catalytic KDM1A inhibitors ORY-1001 and GSK2879552, including clinically relevant doses, was carried out in 2D and 3D spheroid models of Ewing sarcoma and DSRCT.

RESULTS

Catalytic inhibition of KDM1A did not affect cell viability in 2D and 3D assays and had no impact on invasion in a 3D assay.

CONCLUSIONS

Overall, evidence presented here does not support inhibition of KDM1A catalytic demethylase activity as an effective therapeutic strategy for Ewing sarcoma or DSRCT. However, roles of KDM1A beyond its demethylase activity should be considered for these sarcomas.

Immunotherapeutic Challenges for Pediatric Cancers

Solid tumors contain a mixture of malignant cells and non-malignant infiltrating cells that often create a chronic inflammatory and immunosuppressive microenvironment that restricts immunotherapeutic approaches. Although childhood and adult cancers share some similarities related to microenvironmental changes, pediatric cancers are unique, and adult cancer practices may not be wholly applicable to our pediatric patients. This review highlights the differences in tumorigenesis, viral infection, and immunologic response between children and adults that need to be considered when trying to apply experiences from experimental therapies in adult cancer patients to pediatric cancers.

EWSR1, a multifunctional protein, regulates cellular function and aging via genetic and epigenetic pathways

Ewing's sarcoma (EWS) is a bone cancer arising predominantly in young children. EWSR1 (Ewing Sarcoma breakpoint region 1/EWS RNA binding protein 1) gene is ubiquitously expressed in most cell types, indicating it has diverse roles in various cellular processes and organ development. Recently, several studies have shown that missense mutations of EWSR1 genes are known to be associated with central nervous system disorders such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Otherwise, EWSR1 plays epigenetic roles in gene expression, RNA processing, and cellular signal transduction. Interestingly, EWSR1 controls micro RNA (miRNA) levels via Drosha, leading to autophagy dysfunction and impaired dermal development. Ewsr1 deficiency also leads to premature senescence of blood cells and gamete cells with a high rate of apoptosis due to the abnormal meiosis. Despite these roles of EWSR1 in various cellular functions, the exact mechanisms are not yet understood. In this context, the current review overviews a large body of evidence and discusses on what EWSR1 genetic mutations are associated with brain diseases and on how EWSR1 modulates cellular function via the epigenetic pathway. This will provide a better understanding of bona fide roles of EWSR1 in aging and its association with brain disorders.

Investigating the role of LSD2 as an epigenetic regulator in Ewing sarcoma

Ewing sarcoma is the second most common solid bone malignancy diagnosed in pediatric and young adolescent populations. Despite aggressive multi-modal treatment strategies, 5-year event-free survival remains at 75% for patients with localized disease and 20% for patients with metastases. Thus, the need for novel therapeutic options is imperative. Recent studies have focused on epigenetic misregulation in Ewing sarcoma development and potential new oncotargets for treatment. This project focused on the study of LSD2, a flavin-dependent histone demethylase found to be overexpressed in numerous cancers. We previously demonstrated that Ewing sarcoma cell lines are extremely susceptible to small molecule LSD1 blockade with SP-2509. Drug sensitivity correlated with the degree of LSD2 induction following treatment. As such, the purpose of this study was to determine the role of LSD2 in the epigenetic regulation of Ewing sarcoma, characterize genes regulated by LSD2, and examine the impact of SP-2509 drug treatment on LSD2 gene regulation. Genetic depletion (shRNA) of LSD2 significantly impaired oncogenic transformation with only a modest impact on proliferation. Transcriptional analysis of Ewing sarcoma cells following LSD2knockdown revealed modulation of genes primarily involved in metabolic regulation and nervous system development. Gene set enrichment analysis showed that SP-2509 does not impact LSD2 targeted genes. Although there are currently no small molecule agents that specifically target LSD2, our results support further investigations into agents that can inhibit this histone demethylase as a possible treatment for Ewing sarcoma.

Current questions in bone sarcomas

PURPOSE OF REVIEW

Osteosarcoma and Ewing sarcoma, the most common primary bone tumours in young people, are curable in most patients. However, these tumours remain a significant challenge due to the complexity and intensity of treatment and its long-term morbidity and the significant proportion of patients in whom treatment is unsuccessful. This review addresses questions about current management and emerging therapeutic targets for patients with osteosarcoma, Ewing sarcoma and chondrosarcoma, the commonest bone sarcoma but more common in older patients.

RECENT FINDINGS

The largest collaborative international study in osteosarcoma, EURAMOS-1 determined that treatment of patients with resectable disease should not be altered on basis of pathological response to neoadjuvant chemotherapy. In view of little improvement in outcome being evident in recent years, novel therapeutic approaches are required. Putative targets and clinical trials of novel agents are discussed, including emerging targets such as poly (ADP-ribose) polymerase inhibition and isocitrate dehydrogenase inhibition in Ewing sarcoma and chondrosarcoma, respectively. Newer radiotherapy techniques including proton beam and particle ion therapy may be important for local tumour control in selected patients.

SUMMARY

Collaborative studies are essential to answer current questions and investigate novel therapies in these malignancies to improve outcome and quality of life for patients.

Emerging novel agents for patients with advanced Ewing sarcoma: a report from the Children's Oncology Group (COG) New Agents for Ewing Sarcoma Task Force

Ewing sarcoma is a small round blue cell malignancy arising from bone or soft tissue and most commonly affects adolescents and young adults. Metastatic and relapsed Ewing sarcoma have poor outcomes and recurrences remain common. Owing to the poor outcomes associated with advanced disease and the need for a clear research strategy, the Children's Oncology Group Bone Tumor Committee formed the New Agents for Ewing Sarcoma Task Force to bring together experts in the field to evaluate and prioritize new agents for incorporation into clinical trials. This group's mission was to evaluate scientific and clinical challenges in moving new agents forward and to recommend agents and trial designs to the Bone Tumor Committee. The task force generated a framework for vetting prospective agents that included critical evaluation of each drug by using both clinical and non-clinical parameters. Representative appraisal of agents of highest priority, including eribulin, dinutuximab, cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, anti-angiogenic tyrosine kinase inhibitors, and poly-ADP-ribose polymerase (PARP) inhibitors, is described. The task force continues to analyze new compounds by using the paradigm established.

Management of recurrent Ewing sarcoma: challenges and approaches

Although many patients with newly diagnosed Ewing sarcoma can become long-term survivors, relapse remains an important clinical problem for which there is no standard approach. Several prognostic factors have been identified, and these may help guide patient counseling and therapy decisions. A variety of chemotherapy regimens have produced responses in patients with recurrent Ewing sarcoma, but no comparative studies have been completed to show superiority of any one particular approach. In addition, the optimum length of therapy for salvage regimens and use of local control measures remains unknown. The likelihood of cure remains low and the gaps in our knowledge are great, and so enrollment on clinical trials should be strongly encouraged for these patients when feasible. Because Ewing sarcoma is relatively rare, some pediatric and adult oncologists may be less familiar with the management of relapsed patients. In this review, we address common questions facing the clinician and patient, and provide an update on new strategies for therapy.

Biology and targeting of the Jumonji-domain histone demethylase family in childhood neoplasia: a preclinical overview

INTRODUCTION

Epigenetic mechanisms of gene regulatory control play fundamental roles in developmental morphogenesis, and, as more recently appreciated, are heavily implicated in the onset and progression of neoplastic disease, including cancer. Many epigenetic mechanisms are therapeutically targetable, providing additional incentive for understanding of their contribution to cancer and other types of neoplasia. Areas covered: The Jumonji-domain histone demethylase (JHDM) family exemplifies many of the above traits. This review summarizes the current state of knowledge of the functions and pharmacologic targeting of JHDMs in cancer and other neoplastic processes, with an emphasis on diseases affecting the pediatric population. Expert opinion: To date, the JHDM family has largely been studied in the context of normal development and adult cancers. In contrast, comparatively few studies have addressed JHDM biology in cancer and other neoplastic diseases of childhood, especially solid (non-hematopoietic) neoplasms. Encouragingly, the few available examples support important roles for JHDMs in pediatric neoplasia, as well as potential roles for JHDM pharmacologic inhibition in disease management. Further investigations of JHDMs in cancer and other types of neoplasia of childhood can be expected to both enlighten disease biology and inform new approaches to improve disease outcomes.

Fli-1 transcription factor regulates the expression of caspase-1 in lung pericytes

Our previous data demonstrated that Friend leukemia virus integration 1 (Fli-1), an ETS transcription factor, governs pericyte loss and vascular dysfunction in cecal ligation and puncture-induced murine sepsis by regulating essential pyroptosis markers including caspase-1. However, whether Fli-1 regulates caspase-1 expression levels in vitro and how Fli-1 regulates caspase-1 remain unknown. Our present work further demonstrated that overexpressed Fli-1 significantly increased caspase-1 and IL-18 expression levels in cultured mouse lung pericytes. Bacterial outer membrane vesicles (OMVs) have been found to induce cell pyroptosis through transferring LPS intracellularly. Using OMVs to induce an in vitro model of pyroptosis, we observed that OMVs significantly increased protein levels of Fli-1 in mouse lung pericytes. Furthermore, knockdown of Fli-1 by siRNA blocked OMVs-induced caspase-1, caspase-11 and IL-18 expression levels. As caspase-1 was predicted as a potential target of Fli-1, we cloned murine caspase-1 promoter into a luciferase construct. Our data demonstrate for the first time that Fli-1 regulates caspase-1 expression by directly binding to its promoter regions measured by chromatin immunoprecipitation (ChIP) assay and luciferase reporter system. In summary, our findings demonstrated a novel role and mechanism of Fli-1 in regulating caspase-1 expression in lung pericytes.

Integration of genomic copy number variations and chemotherapy-response biomarkers in pediatric sarcoma

Background

While most pediatric sarcomas respond to front-line therapy, some bone sarcomas do not show radiographic response like soft-tissue sarcomas (rhabdomyosarccomas) but do show 90% necrosis. Though, new therapies are urgently needed to improve survival and quality of life in pediatric patients with sarcomas. Complex chromosomal aberrations such as amplifications and deletions of DNA sequences are frequently observed in pediatric sarcomas. Evaluation of copy number variations (CNVs) associated with pediatric sarcoma patients at the time of diagnosis or following therapy offers an opportunity to assess dysregulated molecular targets and signaling pathways that may drive sarcoma development, progression, or relapse. The objective of this study was to utilize publicly available data sets to identify potential predictive biomarkers of chemotherapeutic response in pediatric Osteosarcoma (OS), Rhabdomyosarcoma (RMS) and Ewing’s Sarcoma Family of Tumors (ESFTs) based on CNVs following chemotherapy (OS n = 117, RMS n = 64, ESFTs n = 25 tumor biopsies).

Methods

There were 206 CNV profiles derived from pediatric sarcoma biopsies collected from the public databases TARGET and NCBI-Gene Expression Omnibus (GEO). Through our comparative genomic analyses of OS, RMS, and ESFTs and 22,255 healthy individuals called from the Database of Genomic Variants (DGV), we identified CNVs (amplifications and deletions) pattern of genomic instability in these pediatric sarcomas. By integrating CNVs of Cancer Cell Line Encyclopedia (CCLE) identified in the pool of genes with drug-response data from sarcoma cell lines (n = 27) from Cancer Therapeutics Response Portal (CTRP) Version 2, potential predictive biomarkers of therapeutic response were identified.

Results

Genes associated with survival and/recurrence of these sarcomas with statistical significance were found on long arm of chromosome 8 and smaller aberrations were also identified at chromosomes 1q, 12q and x in OS, RMS, and ESFTs. A pool of 63 genes that harbored amplifications and/or deletions were frequently associated with recurrence across OS, RMS, and ESFTs. Correlation analysis of CNVs from CCLE with drug-response data of CTRP in 27 sarcoma cell lines, 33 CNVs out of 63 genes correlated with either sensitivity or resistance to 17 chemotherapies from which actionable CNV signatures such as IGF1R, MYC, MAPK1, ATF1, and MDM2 were identified. These CNV signatures could potentially be used to delineate patient populations that will respond versus those that will not respond to a particular chemotherapy.

Conclusions

The large-scale analyses of CNV-drug screening provides a platform to evaluate genetic alterations across aggressive pediatric sarcomas. Additionally, this study provides novel insights into the potential utilization of CNVs as not only prognostic but also as predictive biomarkers of therapeutic response. Information obtained in this study may help guide and prioritize patient-specific therapeutic options in pediatric bone and soft-tissue sarcomas.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0456-5) contains supplementary material, which is available to authorized users.

Fli-1 Governs Pericyte Dysfunction in a Murine Model of Sepsis

Background

Pericytes are vascular mural cells and are embedded in the basement membrane of the microvasculature. Recent studies suggest a role for pericytes in lipopolysaccharide (LPS)-induced microvascular dysfunction and mortality, but the mechanisms of pericyte loss in sepsis are largely unknown.

Methods

By using a cecal ligation and puncture (CLP)-induced murine model of sepsis, we observed that CLP led to lung and renal pericyte loss and reduced lung pericyte density and pericyte/endothelial cell (EC) coverage.

Results

Up-regulated Friend leukemia virus integration 1 (Fli-1) messenger ribonucleic acid (RNA) and protein levels were found in lung pericytes from CLP mice in vivo and in LPS-stimulated lung pericytes in vitro. Knockout of Fli-1 in Foxd1-derived pericytes prevented CLP-induced pericyte loss, vascular leak, and improved survival. Disrupted Fli-1 expression by small interfering RNA inhibited LPS-induced inflammatory cytokines and chemokines in cultured lung pericytes. Furthermore, CLP-induced pericyte pyroptosis was mitigated in pericyte Fli-1 knockout mice.

Conclusions

Our findings suggest that Fli-1 is a potential therapeutic target in sepsis.

Myelolytic Treatments Enhance Oncolytic Herpes Virotherapy in Models of Ewing Sarcoma by Modulating the Immune Microenvironment

Ewing sarcoma is a highly aggressive cancer that promotes the infiltration and activation of pro-tumor M2-like macrophages. Oncolytic virotherapy that selectively infects and destroys cancer cells is a promising option for treating Ewing sarcoma. The effect of tumor macrophages on oncolytic virus therapy, however, is variable among solid tumors and is unknown in Ewing sarcoma. We tested the effects of macrophage reduction using liposomal clodronate (Clodrosome) and trabectedin on the antitumor efficacy of intratumoral oncolytic herpes simplex virus, rRp450, in two Ewing sarcoma xenograft models. Both agents enhanced antitumor efficacy without increasing virus replication. The most profound effects were in A673 with only a transient effect on response rates in TC71. Interestingly, A673 was more dependent than TC71 on macrophages for its tumorigenesis. We found Clodrosome and virus together induced expression of antitumorigenic genes and reduced expression of protumorigenic genes in both the tumor-associated macrophages and the overall tumor stroma. Trabectedin reduced intratumoral natural killer (NK) cells, myeloid-derived suppressor cells, and M2-like macrophages, and prevented their increase following virotherapy. Our data suggest that a combination of trabectedin and oncolytic herpes virotherapy warrants testing in the clinical setting.

The combination of epigenetic drugs SAHA and HCI-2509 synergistically inhibits EWS-FLI1 and tumor growth in Ewing sarcoma

Purpose

Epigenetic regulation is crucial in mammalian development and maintenance of tissue-cell specific functions. Perturbation of epigenetic balance may lead to alterations in gene expression, resulting in cellular transformation and malignancy. Previous studies in Ewing sarcoma (ES) have shown that the Nucleosome Remodeling Deacetylase (NuRD) complex binds directly to EWS-FLI1 oncoprotein and modulates its transcriptional activity. The role of EWS-FLI1 as a driver of proliferation and transformation in ES is widely known, but the effect of epigenetic drugs on fusion activity remains poorly described. The present study evaluated the combination effects of the histone deacetylases inhibitor suberoylanilide hydroxamic acid (SAHA) and Lysine-specific demethylase1 inhibitor (HCI-2509) on different biological functions in ES and in comparison to monotherapy treatments.

Results

The study of proliferation and cell viability showed a synergistic effect in most ES cell lines analyzed. An enhanced effect was also observed in the induction of apoptosis, together with accumulation of cells in G1 phase and a blockage of the migratory capacity of ES cell lines. Treatment, either in monotherapy or in combination, caused a significant decrease of EWS-FLI1 mRNA and protein levels and this effect is mediated in part by fusion gene promoter regulation. The anti-tumor effect of this combination was confirmed in patient-derived xenograft mouse models, in which only the combination treatment led to a statistically significant decrease in tumor volume.

Conclusions

The combination of SAHA and HCI-2509 is proposed as a novel treatment strategy for ES patients to inhibit the essential driver of this sarcoma and tumor growth.

Therapeutic Targeting of KDM1A/LSD1 in Ewing Sarcoma with SP-2509 Engages the Endoplasmic Reticulum Stress Response

Multi-agent chemotherapeutic regimes remain the cornerstone treatment for Ewing sarcoma, the second most common bone malignancy diagnosed in pediatric and young adolescent populations. We have reached a therapeutic ceiling with conventional cytotoxic agents, highlighting the need to adopt novel approaches that specifically target the drivers of Ewing sarcoma oncogenesis. As KDM1A/lysine-specific demethylase 1 (LSD1) is highly expressed in Ewing sarcoma cell lines and tumors, with elevated expression levels associated with worse overall survival (P = 0.033), this study has examined biomarkers of sensitivity and mechanisms of cytotoxicity to targeted KDM1A inhibition using SP-2509 (reversible KDM1A inhibitor). We report, that innate resistance to SP-2509 was not observed in our Ewing sarcoma cell line cohort (n = 17; IC₅₀ range, 81 -1,593 nmol/L), in contrast resistance to the next-generation KDM1A irreversible inhibitor GSK-LSD1 was observed across multiple cell lines (IC₅₀ > 300 μmol/L). Although TP53/STAG2/CDKN2A status and basal KDM1A mRNA and protein levels did not correlate with SP-2509 response, induction of KDM1B following SP-2509 treatment was strongly associated with SP-2509 hypersensitivity. We show that the transcriptional profile driven by SP-2509 strongly mirrors KDM1A genetic depletion. Mechanistically, RNA-seq analysis revealed that SP-2509 imparts robust apoptosis through engagement of the endoplasmic reticulum stress pathway. In addition, ETS1/HIST1H2BM were specifically induced/repressed, respectively following SP-2509 treatment only in our hypersensitive cell lines. Together, our findings provide key insights into the mechanisms of SP-2509 cytotoxicity as well as biomarkers that can be used to predict KDM1A inhibitor sensitivity in Ewing sarcoma. Mol Cancer Ther; 17(9); 1902-16. ©2018 AACR.

Ewing sarcoma

Ewing sarcoma is the second most frequent bone tumour of childhood and adolescence that can also arise in soft tissue. Ewing sarcoma is a highly aggressive cancer, with a survival of 70-80% for patients with standard-risk and localized disease and ~30% for those with metastatic disease. Treatment comprises local surgery, radiotherapy and polychemotherapy, which are associated with acute and chronic adverse effects that may compromise quality of life in survivors. Histologically, Ewing sarcomas are composed of small round cells expressing high levels of CD99. Genetically, they are characterized by balanced chromosomal translocations in which a member of the FET gene family is fused with an ETS transcription factor, with the most common fusion being EWSR1-FLI1 (85% of cases). Ewing sarcoma breakpoint region 1 protein (EWSR1)-Friend leukaemia integration 1 transcription factor (FLI1) is a tumour-specific chimeric transcription factor (EWSR1-FLI1) with neomorphic effects that massively rewires the transcriptome. Additionally, EWSR1-FLI1 reprogrammes the epigenome by inducing de novo enhancers at GGAA microsatellites and by altering the state of gene regulatory elements, creating a unique epigenetic signature. Additional mutations at diagnosis are rare and mainly involve STAG2, TP53 and CDKN2A deletions. Emerging studies on the molecular mechanisms of Ewing sarcoma hold promise for improvements in early detection, disease monitoring, lower treatment-related toxicity, overall survival and quality of life.

Matricellular Proteins: Functional Insights From Non-mammalian Animal Models

The extracellular matrix (ECM) has central roles in tissue integrity and remodeling throughout the life span of animals. While collagens are the most abundant structural components of ECM in most tissues, tissue-specific molecular complexity is contributed by ECM glycoproteins. The matricellular glycoproteins are categorized primarily according to functional criteria and represented predominantly by the thrombospondin, tenascin, SPARC/osteonectin, and CCN families. These proteins do not self-assemble into ECM fibrils; nevertheless, they shape ECM properties through interactions with structural ECM proteins, growth factors, and cells. Matricellular proteins also promote cell migration or morphological changes through adhesion-modulating or counter-adhesive actions on cell-ECM adhesions, intracellular signaling, and the actin cytoskeleton. Typically, matricellular proteins are most highly expressed during embryonic development. In adult tissues, expression is more limited unless activated by cues for dynamic tissue remodeling and cell motility, such as occur during inflammatory response and wound repair. Many insights in the complex roles of matricellular proteins have been obtained from studies of gene knockout mice. However, with the exception of chordate-specific tenascins, these are highly conserved proteins that are encoded in many animal phyla. This review will consider the increasing body of research on matricellular proteins in nonmammalian animal models. These models provide better access to the very earliest stages of embryonic development and opportunities to study biological processes such as limb and organ regeneration. In aggregate, this research is expanding concepts of the functions and mechanisms of action of matricellular proteins.

Pencil beam scanned protons for the treatment of patients with Ewing sarcoma

BACKGROUND

Few data exist regarding the clinical outcome of patients with Ewing sarcoma (EWS) treated with pencil beam scanning proton therapy (PT). We report the outcome of children, adolescents and young adults (AYA) treated with PT at the Paul Scherrer Institute.

MATERIALS

Thirty-eight patients (median age, 9.9 years) received a median dose of 54.9 Gy(RBE) (where RBE is relative biologic effectiveness). Size of the tumor ranged from 1.7 to 24 cm. Most common primary site was axial/pelvic (n = 27; 71%). Four patients (11%) presented with metastases at diagnosis. Twenty (53%) patients had chemo-PT only. Median follow-up was 49.6 months (range, 9.2-131.7).

RESULTS

The 5-year actuarial rate of local control (LC), distant metastasis-free survival (DMFS), and overall survival (OS) were 81.5%, 76.4%, and 83.0%, respectively. All local recurrences occurred in field and in patients with nonextremity primaries. Six patients died, all of tumor progression. Age < 10 years was a favorable factor of borderline significance for LC (P = 0.05) and OS (P = 0.05), but was significant for DMFS (P = 0.003). Tumor volume <200 ml was a significant prognostic factors for DMFS (P = 0.03), but not for OS (P = 0.07). Metastasis at diagnosis was a strong predictor of local failure (P = 0.003). Only two grade 3 late toxicities were observed. The 5-year actuarial rate of grade 3 toxicity-free survival was 90.9%.

CONCLUSIONS

These preliminary data suggest that the outcomes of children and AYA with EWS are good and PT was well tolerated with few late adverse events. The local and distant tumor control for older patients with large pre-PT tumor volumes remains problematic.

Identification of downstream metastasis-associated target genes regulated by LSD1 in colon cancer cells

Purpose

This study aims to identify downstream target genes regulated by lysine-specific demethylase 1 (LSD1) in colon cancer cells and investigate the molecular mechanisms of LSD1 influencing invasion and metastasis of colon cancer.

Method

We obtained the expression changes of downstream target genes regulated by small-interfering RNA-LSD1 and LSD1-overexpression via gene expression profiling in two human colon cancer cell lines. An Affymetrix Human Transcriptome Array 2.0 was used to identify differentially expressed genes (DEGs). We screened out LSD1-target gene associated with proliferation, metastasis, and invasion from DEGs via Gene Ontology and Pathway Studio. Subsequently, four key genes (CABYR, FOXF2, TLE4, and CDH1) were computationally predicted as metastasis-related LSD1-target genes. ChIp-PCR was applied after RT-PCR and Western blot validations to detect the occupancy of LSD1-target gene promoter-bound LSD1.

Result

A total of 3633 DEGs were significantly upregulated, and 4642 DEGs were downregulated in LSD1-silenced SW620 cells. A total of 4047 DEGs and 4240 DEGs were upregulated and downregulated in LSD1-overexpressed HT-29 cells, respectively. RT-PCR and Western blot validated the microarray analysis results. ChIP assay results demonstrated that LSD1 might be negative regulators for target genes CABYR and CDH1. The expression level of LSD1 is negatively correlated with mono- and dimethylation of histone H3 lysine4(H3K4) at LSD1- target gene promoter region. No significant mono-methylation and dimethylation of H3 lysine9 methylation was detected at the promoter region of CABYR and CDH1.

Conclusion

LSD1- depletion contributed to the upregulation of CABYR and CDH1 through enhancing the dimethylation of H3K4 at the LSD1-target genes promoter. LSD1- overexpression mediated the downregulation of CABYR and CDH1expression through decreasing the mono- and dimethylation of H3K4 at LSD1-target gene promoter in colon cancer cells. CABYR and CDH1 might be potential LSD1-target genes in colon carcinogenesis.

LSD1 Inhibitor T-3775440 Inhibits SCLC Cell Proliferation by Disrupting LSD1 Interactions with SNAG Domain Proteins INSM1 and GFI1B

T-3775440 is an irreversible inhibitor of the chromatin demethylase LSD1, which exerts antiproliferative effects by disrupting the interaction between LSD1 and GFI1B, a SNAG domain transcription factor, inducing leukemia cell transdifferentiation. Here, we describe the anticancer effects and mechanism of action of T-3775440 in small-cell lung cancer (SCLC). T-3775440 inhibited proliferation of SCLC cells in vitro and retarded SCLC tumor growth in vivo T-3775440 disrupted the interaction between LSD1 and the transcriptional repressor INSM1, thereby inhibiting expression of neuroendocrine-associated genes, such as ASCL1 INSM1 silencing phenocopied the effects of T-3775440 on gene expression and cell proliferation, consistent with the likelihood T-3775440 mediated its effects in SCLC by inhibiting INSM1. T-3775440 also inhibited proliferation of an SCLC cell line that overexpressed GFI1B, rather than INSM1, by disrupting the interaction between LSD1 and GFI1B. Taken together, our results argue that LSD1 plays an important role in neuroendocrine-associated transcription and cell proliferation of SCLC via interactions with the SNAG domain proteins INSM1 and GFI1B. Targeting these critical interactions with LSD1 inhibitors offers a novel rational strategy to therapeutically manage SCLC. Cancer Res; 77(17); 4652-62. ©2017 AACR.

Upregulation of CD11b and CD86 through LSD1 inhibition promotes myeloid differentiation and suppresses cell proliferation in human monocytic leukemia cells

LSD1 (Lysine Specific Demethylase1)/KDM1A (Lysine Demethylase 1A), a flavin adenine dinucleotide (FAD)-dependent histone H3K4/K9 demethylase, sustains oncogenic potential of leukemia stem cells in primary human leukemia cells. However, the pro-differentiation and anti-proliferation effects of LSD1 inhibition in acute myeloid leukemia (AML) are not yet fully understood. Here, we report that small hairpin RNA (shRNA) mediated LSD1 inhibition causes a remarkable transcriptional activation of myeloid lineage marker genes (CD11b/ITGAM and CD86), reduction of cell proliferation and decrease of clonogenic ability of human AML cells. Cell surface expression of CD11b and CD86 is significantly and dynamically increased in human AML cells upon sustained LSD1 inhibition. Chromatin immunoprecipitation and quantitative PCR (ChIP-qPCR) analyses of histone marks revealed that there is a specific increase of H3K4me2 modification and an accompanied increase of H3K4me3 modification at the respective CD11b and CD86 promoter region, whereas the global H3K4me2 level remains constant. Consistently, inhibition of LSD1 in vivo significantly blocks tumor growth and induces a prominent increase of CD11b and CD86. Taken together, our results demonstrate the anti-tumor properties of LSD1 inhibition on human AML cell line and mouse xenograft model. Our findings provide mechanistic insights into the LSD1 functions in controlling both differentiation and proliferation in AML.