Pharmacologic Inhibition of EIF4A Blocks NRF2 Synthesis to Prevent Osteosarcoma Metastasis.

Purpose: Effective therapies for metastatic osteosarcoma (OS) remain a critical unmet need. Targeting mRNA translation in metastatic OS offers a promising option, as selective translation drives the synthesis of cytoprotective proteins under harsh microenvironmental conditions to facilitate metastatic competence.

Experimental Design: We assessed the expression levels of eukaryotic translation factors in OS, revealing the high expression of the eukaryotic initiation factor 4A1 (EIF4A1).

The HACE1 E3 ligase mediates RAC1-dependent control of mTOR signaling complexes.

HACE1 is a HECT family E3 ubiquitin-protein ligase with broad but incompletely understood tumor suppressor activity. Here, we report a previously unrecognized link between HACE1 and signaling complexes containing mammalian target of rapamycin (mTOR). HACE1 blocks mTORC1 and mTORC2 activities by reducing mTOR stability in an E3 ligase-dependent manner.

Surface and Global Proteome Analyses Identify ENPP1 and Other Surface Proteins as Actionable Immunotherapeutic Targets in Ewing Sarcoma.

Purpose: Ewing sarcoma is the second most common bone sarcoma in children, with 1 case per 1.5 million in the United States. Although the survival rate of patients diagnosed with localized disease is approximately 70%, this decreases to approximately 30% for patients with metastatic disease and only approximately 10% for treatment-refractory disease, which have not changed for decades.

A MYCN-independent mechanism mediating secretome reprogramming and metastasis in -amplified neuroblastoma.

amplification () is a defining feature of high-risk neuroblastoma (NB) and predicts poor prognosis. However, whether genes within or in close proximity to the amplicon also contribute to NB remains poorly understood. Here, we identify that , a transcription factor encoding gene neighboring the locus, is frequently coexpressed with and promotes cell survival in NB.

NSG Mice Facilitate Characterization of Ewing Sarcoma Lung Metastasis Using the PuMA Model.

Ewing sarcoma (EwS) is a highly malignant bone and soft tissue tumor primarily affecting children and young adults. While most patients initially respond well to conventional front-line therapy, frequent metastasis results in poor 5-year overall survival rates for this disease. Accordingly, there is a critical need to develop better models to understand EwS metastasis.

Understanding and Modeling Metastasis Biology to Improve Therapeutic Strategies for Combating Osteosarcoma Progression.

Osteosarcoma is a malignant primary tumor of bone, arising from transformed progenitor cells with osteoblastic differentiation and osteoid production. While categorized as a rare tumor, most patients diagnosed with osteosarcoma are adolescents in their second decade of life and underscores the potential for life changing consequences in this vulnerable population. In the setting of localized disease, conventional treatment for osteosarcoma affords a cure rate approaching 70%; however, survival for patients suffering from metastatic disease remain disappointing with only 20% of individuals being alive past 5 years post-diagnosis.

Provocative questions in osteosarcoma basic and translational biology: A report from the Children's Oncology Group.

Patients who are diagnosed with osteosarcoma (OS) today receive the same therapy that patients have received over the last 4 decades. Extensive efforts to identify more effective or less toxic regimens have proved disappointing. As we enter a postgenomic era in which we now recognize OS not as a cancer of mutations but as one defined by p53 loss, chromosomal complexity, copy number alteration, and profound heterogeneity, emerging threads of discovery leave many hopeful that an improving understanding of biology will drive discoveries that improve clinical care.

Corrigendum: Positively selected enhancer elements endow osteosarcoma cells with metastatic competence.

This corrects the article DOI: 10.1038/nm.4475.

Practical Considerations in Studying Metastatic Lung Colonization in Osteosarcoma Using the Pulmonary Metastasis Assay.

The pulmonary metastasis assay (PuMA) is an ex vivo lung explant and closed cell culture system that permits researchers to study the biology of lung colonization in osteosarcoma (OS) by fluorescence microscopy. This article provides a detailed description of the protocol, and discusses examples of obtaining image data on metastatic growth using widefield or confocal fluorescence microscopy platforms. The flexibility of the PuMA model permits researchers to study not only the growth of OS cells in the lung microenvironment, but also to assess the effects of anti-metastatic therapeutics over time.

Positively selected enhancer elements endow osteosarcoma cells with metastatic competence.

Metastasis results from a complex set of traits acquired by tumor cells, distinct from those necessary for tumorigenesis. Here, we investigate the contribution of enhancer elements to the metastatic phenotype of osteosarcoma. Through epigenomic profiling, we identify substantial differences in enhancer activity between primary and metastatic human tumors and between near isogenic pairs of highly lung metastatic and nonmetastatic osteosarcoma cell lines.

Upregulation of Glucose-Regulated Protein 78 in Metastatic Cancer Cells Is Necessary for Lung Metastasis Progression.

Metastasis is the cause of more than 90% of all cancer deaths. Despite this fact, most anticancer therapeutics currently in clinical use have limited efficacy in treating established metastases. Here, we identify the endoplasmic reticulum chaperone protein, glucose-regulated protein 78 (GRP78), as a metastatic dependency in several highly metastatic cancer cell models.

mTOR Inhibition Mitigates Enhanced mRNA Translation Associated with the Metastatic Phenotype of Osteosarcoma Cells In Vivo.

Purpose: To successfully metastasize, tumor cells must respond appropriately to biological stressors encountered during metastatic progression. We sought to test the hypothesis that enhanced efficiency of mRNA translation during periods of metastatic stress is required for metastatic competence of osteosarcoma and that this metastasis-specific adaptation is amenable to therapeutic intervention.

Experimental Design: We employ novel reporter and proteomic systems that enable tracking of mRNA translation efficiency and output in metastatic osteosarcoma cells as they colonize the lungs.

Characterization of the metastatic phenotype of a panel of established osteosarcoma cells.

Osteosarcoma (OS) is the most common bone tumor in pediatric patients. Metastasis is a major cause of mortality and morbidity. The rarity of this disease coupled with the challenges of drug development for metastatic cancers have slowed the delivery of improvements in long-term outcomes for these patients.

Tumor microenvironment-based feed-forward regulation of NOS2 in breast cancer progression.

Inflammation is widely recognized as an inducer of cancer progression. The inflammation-associated enzyme, inducible nitric oxide synthase (NOS2), has emerged as a candidate oncogene in estrogen receptor (ER)-negative breast cancer, and its increased expression is associated with disease aggressiveness and poor survival. Although these observations implicate NOS2 as an attractive therapeutic target, the mechanisms of both NOS2 induction in tumors and nitric oxide (NO)-driven cancer progression are not fully understood.

Nitric oxide synthase and breast cancer: role of TIMP-1 in NO-mediated Akt activation.

Prediction of therapeutic response and cancer patient survival can be improved by the identification of molecular markers including tumor Akt status. A direct correlation between NOS2 expression and elevated Akt phosphorylation status has been observed in breast tumors. Tissue inhibitor matrix metalloproteinase-1 (TIMP-1) has been proposed to exert oncogenic properties through CD63 cell surface receptor pathway initiation of pro-survival PI3k/Akt signaling.

Imaging the impact of chemically inducible proteins on cellular dynamics in vivo.

The analysis of dynamic events in the tumor microenvironment during cancer progression is limited by the complexity of current in vivo imaging models. This is coupled with an inability to rapidly modulate and visualize protein activity in real time and to understand the consequence of these perturbations in vivo. We developed an intravital imaging approach that allows the rapid induction and subsequent depletion of target protein levels within human cancer xenografts while assessing the impact on cell behavior and morphology in real time.

Dysregulation of ezrin phosphorylation prevents metastasis and alters cellular metabolism in osteosarcoma.

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.