Inactivation of EMILIN-1 by Proteolysis and Secretion in Small Extracellular Vesicles Favors Melanoma Progression and Metastasis.

Ana Amor López,Eva Muñoz,Paola Spessotto,Diego Megías,Fátima Al-Shahrour,Marina S Mazariegos,Javier Muñoz,Pilar Ximénez-Embún,Juan Ángel Recio,Marta Hergueta-Redondo,Alessandra Capuano,Roberto Doliana,Héctor Peinado

doi:10.3390/ijms22147406

Abstract

Several studies have demonstrated that melanoma-derived extracellular vesicles (EVs) are involved in lymph node metastasis; however, the molecular mechanisms involved are not completely defined. Here, we found that EMILIN-1 is proteolyzed and secreted in small EVs (sEVs) as a novel mechanism to reduce its intracellular levels favoring metastasis in mouse melanoma lymph node metastatic cells. Interestingly, we observed that EMILIN-1 has intrinsic tumor and metastasis suppressive-like properties reducing effective migration, cell viability, primary tumor growth, and metastasis. Overall, our analysis suggests that the inactivation of EMILIN-1 by proteolysis and secretion in sEVs reduce its intrinsic tumor suppressive activities in melanoma favoring tumor progression and metastasis.

Highlights

The tumor microenvironment has been found to play an active role in tumor progression [1]
We have found a specific signature of genes over-expressed in cells and proteins hyper-secreted in small EVs (sEVs) including Elastin microfibrillar interface proteins (EMILINs)-1, a protein involved in lymph node physiology and pathology [18,19]
We observed that sEVs from lymph node metastatic (B16-F1R2) and high metastatic models (B16-F10) secrete higher amounts of protein in sEV than poorly metastatic cell line B16-F1

Summary

Introduction

The tumor microenvironment has been found to play an active role in tumor progression [1]. Tumors induce the formation of microenvironments at distant organs that are conducive to the survival and outgrowth of tumor cells prior to their arrival at these sites. These microenvironments were termed “pre-metastatic niches” (PMNs) [2]. This concept proposes the ability of primary tumor cells to precondition regional and distal organs for future metastatic disease before the arrival of circulating tumor cells via tumor-derived factors. Several reports have highlighted the role of extracellular vesicles (EVs) during PMN formation [3,4]. EVs are composed of a lipid bilayer that contains molecular cargo representative from the cell of origin (e.g., proteins, RNA, DNA, etc.) [5]. We ensured to follow MISEV guidelines recommend [10], such as (i) defining quantitatively the source of EVs, (ii) characterization of the abundance of EV particle number and protein content, (iii) proteomic characterization, and (iv) purity of the preparation

Methods

Results

Conclusion