Degree of MDM2 Amplification Affects Clinical Outcomes in Dedifferentiated Liposarcoma.

BACKGROUND: Dedifferentiated liposarcomas (DDLPS) are mesenchymal tumors associated with universally poor response to treatment. Genomic amplification of murine double minute 2 (MDM2) is used as a diagnostic biomarker; however, no established biomarkers exist to guide DDLPS treatment. In the largest study of its kind, we report that the extent of MDM2 amplification, not simply the presence of MDM2 amplification, may be biologically important to the actions of DDLPS. PATIENTS AND METHODS: The distribution of MDM2 amplification in DDLPS was assessed using data from a commercial sequencing laboratory (n = 642) and The Cancer Genome Atlas (n = 57). Data from two retrospective clinical trials (n = 15, n = 16) and one prospective clinical trial (n = 25) were used to test MDM2's utility as a clinical biomarker. in vitro and in vivo assessments were conducted in DDLPS cell lines. RESULTS: Genomic MDM2 amplification follows a highly reproducible log-normal distribution. In patients with DDLPS treated with complete tumor resection, elevated MDM2 was associated with shortened time to recurrence as measured by genomic amplification (p = .003) and mRNA expression (p = .04). In patients requiring systemic therapy, higher MDM2 amplification was associated with reduced overall survival (p = .04). Doxorubicin treatment of DDLPS cells in vitro demonstrated variable sensitivity based on baseline MDM2 levels, and doxorubicin treatment elevated MDM2 expression. In vivo, treatment with doxorubicin followed by an MDM2 inhibitor improved doxorubicin sensitivity. CONCLUSION: MDM2 amplification levels in DDLPS follow a reproducible distribution and are associated with clinical outcomes and drug sensitivity. These results suggest that a prospective study of MDM2 as a predictive biomarker in DDLPS is warranted. IMPLICATIONS FOR PRACTICE: No validated biomarkers exist for treatment selection in dedifferentiated liposarcoma (DDLPS). Although murine double minute 2 (MDM2) is currently used for diagnosis, the clinical relevance of MDM2 amplification has yet to be fully assessed. This study found that MDM2 amplification follows a predictable distribution in DDLPS and correlates with clinical and biological outcomes. These data suggests that MDM2 amplification may be a useful biomarker in DDLPS.

miR-133a function in the pathogenesis of dedifferentiated liposarcoma.

BACKGROUND: Sarcomas are malignant heterogeneous tumors of mesenchymal derivation. Dedifferentiated liposarcoma (DDLPS) is aggressive with recurrence in 80% and metastasis in 20% of patients. We previously found that miR-133a was significantly underexpressed in liposarcoma tissues. As this miRNA has recently been shown to be a tumor suppressor in many cancers, the objective of this study was to characterize the biological and molecular consequences of miR-133a underexpression in DDLPS. METHODS: Real-time PCR was used to evaluate expression levels of miR-133a in human DDLPS tissue, normal fat tissue, and human DDLPS cell lines. DDLPS cells were stably transduced with miR-133a vector to assess the effects in vitro on proliferation, cell cycle, cell death, migration, and metabolism. A Seahorse Bioanalyzer system was also used to assess metabolism in vivo by measuring glycolysis and oxidative phosphorylation (OXPHOS) in subcutaneous xenograft tumors from immunocompromised mice. RESULTS: miR-133a expression was significantly decreased in human DDLPS tissue and cell lines. Enforced expression of miR-133a decreased cell proliferation, impacted cell cycle progression kinetics, decreased glycolysis, and increased OXPHOS. There was no significant effect on cell death or migration. Using an in vivo xenograft mouse study, we showed that tumors with increased miR-133a expression had no difference in tumor growth compared to control, but did exhibit an increase in OXPHOS metabolic respiration. CONCLUSIONS: Based on our collective findings, we propose that in DDPLS, loss of miR-133a induces a metabolic shift due to a reduction in oxidative metabolism favoring a Warburg effect in DDLPS tumors, but this regulation on metabolism was not sufficient to affect DDPLS.

Liposarcoma: molecular targets and therapeutic implications.

Liposarcoma (LPS) is the most common soft tissue sarcoma and accounts for approximately 20 % of all adult sarcomas. Current treatment modalities (surgery, chemotherapy, and radiotherapy) all have limitations; therefore, molecularly driven studies are needed to improve the identification and increased understanding of genetic and epigenetic deregulations in LPS if we are to successfully target specific tumorigenic drivers. It can be anticipated that such biology-driven therapeutics will improve treatments by selectively deleting cancer cells while sparing normal tissues. This review will focus on several therapeutically actionable molecular markers identified in well-differentiated LPS and dedifferentiated LPS, highlighting their potential clinical applicability.

The hepatocyte growth factor receptor as a potential therapeutic target for dedifferentiated liposarcoma.

Dedifferentiated liposarcomas (DDLPS) are highly resistant to conventional chemo- and radiotherapies, with surgical resection remaining the classic treatment strategy; therefore, there is a pressing need for novel anti-DDLPS-targeted chemotherapeutics. Hepatocyte growth factor receptor (Met) expression is elevated in DDLPS, but the functional role of Met signaling in this disease is not known. We found that the in vitro stimulation of DDLPS cells with hepatocyte growth factor (HGF) elevated the degree of PI3K/AKT and MAPK pathway signaling, and that pro-tumorigenic phenotypes such as cell proliferation, invasion, and migration were significantly enhanced. Conversely, Met knockdown using shRNA-mediated interference decreased HGF-induced Met signaling, the invasive and migratory nature of DDLPS cells in vitro, and the tumorigenicity of DDLPS cells in vivo. These data strongly support the role for Met as a DDLPS therapeutic target. To that end, using EMD1214063, an ATP-competitive kinase inhibitor that targets Met more specifically than other kinases, inhibited Met-dependent signaling, reduced the oncogenicity of DDLPS cells in vitro, and significantly increased the survival of nude mice bearing subcutaneous DDLPS xenografts. These findings support further investigations of HGF-induced Met signaling inhibition in DDLPS, as a potential strategy to enhance clinical outcomes for this disease.

MDM2-Dependent Rewiring of Metabolomic and Lipidomic Profiles in Dedifferentiated Liposarcoma Models.

Dedifferentiated liposarcoma (DDLPS) is an aggressive mesenchymal cancer marked by amplification of MDM2, an inhibitor of the tumor suppressor TP53. DDLPS patients with higher MDM2 amplification have lower chemotherapy sensitivity and worse outcome than patients with lower MDM2 amplification. We hypothesized that MDM2 amplification levels may be associated with changes in DDLPS metabolism. Six patient-derived DDLPS cell line models were subject to comprehensive metabolomic (Metabolon) and lipidomic (SCIEX 5600 TripleTOF-MS) profiling to assess associations with MDM2 amplification and their responses to metabolic perturbations. Comparing metabolomic profiles between MDM2 higher and lower amplification cells yielded a total of 17 differentially abundant metabolites across both panels (FDR < 0.05, log2 fold change < 0.75), including ceramides, glycosylated ceramides, and sphingomyelins. Disruption of lipid metabolism through statin administration resulted in a chemo-sensitive phenotype in MDM2 lower cell lines only, suggesting that lipid metabolism may be a large contributor to the more aggressive nature of MDM2 higher DDLPS tumors. This study is the first to provide comprehensive metabolomic and lipidomic characterization of DDLPS cell lines and provides evidence for MDM2-dependent differential molecular mechanisms that are critical factors in chemoresistance and could thus affect patient outcome.

Exosome-Derived miR-25-3p and miR-92a-3p Stimulate Liposarcoma Progression.

Despite the development of combined modality treatments against liposarcoma in recent years, a significant proportion of patients respond only modestly to such approaches, possibly contributing to local or distant recurrence. Early detection of recurrent or metastatic disease could improve patient prognosis by triggering earlier clinical intervention. However, useful biomarkers for such purposes are lacking. Using both patient plasma samples and cell lines, we demonstrate here that miR-25-3p and miR-92a-3p are secreted by liposarcoma cells through extracellular vesicles and may be useful as potential biomarkers of disease. Both miR-25-3p and miR-92a-3p stimulated secretion of proinflammatory cytokine IL6 from tumor-associated macrophages in a TLR7/8-dependent manner, which in turn promoted liposarcoma cell proliferation, invasion, and metastasis via this interaction with the surrounding microenvironment. Our findings provide novel and previously unreported insight into liposarcoma progression, identifying communication between liposarcoma cells and their microenvironment as a process critically involved in liposarcoma progression. This study establishes the possibility that the pattern of circulating miRNAs may identify recurrence prior to radiological detectability while providing insight into disease outcome and as a possible approach to monitor treatment efficacy. Cancer Res; 77(14); 3846-56. ©2017 AACR.

HDAC Inhibition for the Treatment of Epithelioid Sarcoma: Novel Cross Talk Between Epigenetic Components.

UNLABELLED: Epithelioid sarcoma is a rare neoplasm uniquely comprised of cells exhibiting both mesenchymal and epithelial features. Having propensity for local and distant recurrence, it poses a diagnostic dilemma secondary to pathologic complexity. Patients have dismal prognosis due to lack of effective therapy. HDAC inhibitors (HDACi) exhibit marked antitumor effects in various malignancies. The studies here demonstrate that pan-HDAC inhibitors constitute novel therapeutics versus epithelioid sarcoma. Human ES cells (VAESBJ, HS-ES, Epi-544) were studied in preclinical models to evaluate HDACi effects. Immunoblot and RT-PCR were used to evaluate expression of acetylated tubulin, histones H3/H4, EZH2 upon HDACi. MTS and clonogenic assays were used to assess the impact of HDACi on cell growth. Cell culture assays were used to evaluate the impact of HDACi and EZH2-specific siRNA inhibition on cell-cycle progression and survival. Unbiased gene array analysis was used to identify the impact of HDACi on epithelioid sarcoma gene expression. Xenografts were used to evaluate epithelioid sarcoma tumor growth in response to HDACi. HDAC inhibition increased target protein acetylation and abrogated cell growth and colony formation in epithelioid sarcoma cells. HDACi induced G(2) cell-cycle arrest and marked apoptosis, and reduced tumor growth in xenograft models. HDACi induced widespread gene expression changes, and EZH2 was significantly downregulated. EZH2 knockdown resulted in abrogated cell growth in vitro. IMPLICATIONS: The current study suggests a clinical role for HDACi in human epithelioid sarcoma, which, when combined with EZH2 inhibitors, could serve as a novel therapeutic strategy for epithelioid sarcoma patients. Future investigations targeting specific HDAC isoforms along with EZH2 may potentially maximizing treatment efficacy.

SAR405838: A Novel and Potent Inhibitor of the MDM2:p53 Axis for the Treatment of Dedifferentiated Liposarcoma.

PURPOSE: Dedifferentiated liposarcoma (DDLPS) is an aggressive malignancy that can recur locally or disseminate even after multidisciplinary care. Genetically amplified and expressed MDM2, often referred to as a "hallmark" of DDLPS, mostly sustains a wild-type p53 genotype, substantiating the MDM2:p53 axis as a potential therapeutic target for DDLPS. Here, we report on the preclinical effects of SAR405838, a novel and highly selective MDM2 small-molecule inhibitor, in both in vitro and in vivo DDLPS models. EXPERIMENTAL DESIGN: The therapeutic effectiveness of SAR405838 was compared with the known MDM2 antagonists Nutlin-3a and MI-219. The effects of MDM2 inhibition were assessed in both in vitro and in vivo. In vitro and in vivo microarray analyses were performed to assess differentially expressed genes induced by SAR405838, as well as the pathways that these modulated genes enriched. RESULTS: SAR405838 effectively stabilized p53 and activated the p53 pathway, resulting in abrogated cellular proliferation, cell-cycle arrest, and apoptosis. Similar results were observed with Nutlin-3a and MI-219; however, significantly higher concentrations were required. In vitro effectiveness of SAR405838 activity was recapitulated in DDLPS xenograft models where significant decreases in tumorigenicity were observed. Microarray analyses revealed genes enriching the p53 signaling pathway as well as genomic stability and DNA damage following SAR405838 treatment. CONCLUSIONS: SAR405838 is currently in early-phase clinical trials for a number of malignancies, including sarcoma, and our in vitro and in vivo results support its use as a potential therapeutic strategy for the treatment of DDLPS.

HDAC8, A Potential Therapeutic Target for the Treatment of Malignant Peripheral Nerve Sheath Tumors (MPNST).

INTRODUCTION: HDAC isoform-specific inhibitors may improve the therapeutic window while limiting toxicities. Developing inhibitors against class I isoforms poses difficulties as they share high homology among their catalytic sites; however, HDAC8 is structurally unique compared to other class I isoforms. HDAC8 inhibitors are novel compounds and have affinity for class I HDAC isoforms demonstrating anti-cancer effects; little is known about their activity in malignant peripheral nerve sheath tumors (MPNST). Recently, we demonstrated anti-MPNST efficacy of HDAC8i in human and murine-derived MPNST pre-clinical models; we now seek to consider the potential therapeutic inhibition of HDAC8 in MPNST. METHODS: Four Human MPNST cell lines, a murine-derived MPNST cell line, and two HDAC8 inhibitors (PCI-34051, PCI-48012; Pharmacyclics, Inc. Sunnyvale, CA) were studied. Proliferation was determined using MTS and clonogenic assays. Effects on cell cycle were determined via PI FACS analysis; effects on apoptosis were determined using Annexin V-PI FACS analysis and cleaved caspase 3 expression. In vivo growth effects of HDAC8i were evaluated using MPNST xenograft models. 2D gel electrophoresis and mass spectrometry were used to identify potential HDAC8 deacetylation substrates. RESULTS: HDAC8i induced cell growth inhibition and marked S-phase cell cycle arrest in human and murine-derived MPNST cells. Relative to control, HDAC8i induced apoptosis in both human and murine-derived MPNST cells. HDAC8i exhibited significant effects on MPNST xenograft growth (p=0.001) and tumor weight (p=0.02). Four potential HDAC8 substrate targets were identified using a proteomic approach: PARK7, HMGB1, PGAM1, PRDX6. CONCLUSIONS: MPNST is an aggressive sarcoma that is notoriously therapy-resistant, hence the urgent need for improved anti-MPNST therapies. HDAC8 inhibition may be useful for MPNST by improving efficacy while limiting toxicities as compared to pan-HDACis.