MDM2 Derived from Dedifferentiated Liposarcoma Extracellular Vesicles Induces MMP2 Production from Preadipocytes

Dedifferentiated liposarcoma (DDLPS) is frequently diagnosed late, and patients typically respond poorly to treatments. DDLPS is molecularly characterized by wild-type p53 and amplification of the MDM2 gene, which results in overexpression of MDM2 protein, a key oncogenic process in DDLPS. In this study, we demonstrate that extracellular vesicles derived from patients with DDLPS or from DDLPS cell lines are carriers of MDM2 DNA that can be transferred to preadipocytes, a major and ubiquitous cellular component of the DDLPS tumor microenvironment, leading to impaired p53 activity in preadipocytes and increased proliferation, migration, and production of matrix metalloproteinase 2; treatment with MDM2 inhibitors repressed these effects. Overall, these findings indicate that MDM2 plays a crucial role in DDLPS by enabling cross-talk between tumor cells and the surrounding microenvironment and that targeting vesicular MDM2 could represent a therapeutic option for treating DDLPS. SIGNIFICANCE: Extracellular vesicles derived from dedifferentiated liposarcoma cells induce oncogenic properties in preadipocytes.

Abstract 1891: Oncogenic MDM2-containing exosomes promote pre-metastatic niche establishment

Extracellular vesicles (EVs) have an important role in the communication between cells for their ability to transfer proteins and other biologically active molecules. EVs have been also described to have unique functions during pre-metastatic niche establishment and maintenance. MDM2 oncoprotein is the best-characterized cellular antagonist of p53 and its amplification is one of the most known mechanisms for tumor development. MDM2 amplification occurs in more than forty different types of malignancies and in 100% of well-differentiated and dedifferentiated liposarcoma (DDLPS). Retroperitoneal DDLPS is especially concerning given its propensity for multifocal local and distant recurrence, accounting for an overall survival rate of 10% at 10 years. Here, we show the presence of MDM2 in tumor EVs and specifically in both DDLPS cell line-derived EVs and patient-serum EVs. We also show the ability of MDM2-cargo to be transferred to recipient preadipocytes. Furthermore, we also demonstrated that this transfer is able to promote a pre-metastatic niche establishment in the DDLPS tumor microenvironment fat bearing areas, inducing: (I) tumor associated phenotype such as enhanced proliferation and migration, in the recipient preadipocytes, by downregulation of MDM2 downstream pathway; (II) pro-inflammatory phenotype through the release of pro-inflammatory cytokines such as IL-8; (III) release of active metalloproteinases such as MMP2 which is crucial for the invasiveness of many disseminating tumors. In conclusion here we report the presence of MDM2, in the patient circulation; importantly showing that MDM2 triggers the release of active MMP-2, we also propose a possible mechanism for pre-metastatic niche establishment and DDLPS multifocal loco-regional recurrence.

Citation Format: Lucia Casadei, Federica Calore, Ameya Deshmukh, Abeba Zewdu, Danielle A. Braggio, Paolo Fadda, Martin Wabitsch, Gonzalo Lopez, Jennifer Leight, Dina Lev, Carlo M. Croce, Raphael E. Pollock. Oncogenic MDM2-containing exosomes promote pre-metastatic niche establishment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1891.

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.