Oncosome Formation in Prostate Cancer: Association with a Region of Frequent Chromosomal Deletion in Metastatic Disease

Abstract

Oncosomes have recently been described as membranederived microvesicles secreted by cancer cells, which transfer oncogenic signals and protein complexes across cell boundaries. Here, we show the rapid formation and secretion of oncosomes from DU145 and LNCaP human prostate cancer cells. Oncosome formation was stimulated by epidermal growth factor receptor activation and also by overexpression of membrane-targeted Akt1. Microvesicles shed from prostate cancer cells contained numerous signal transduction proteins and were capable of activating rapid phospho-tyrosine and Akt pathway signaling, and stimulating proliferation and migration, in recipient tumor cells. They also induced a stromal reaction in recipient normal cells. Knockdown of the actin nucleating protein Diaphanous Related Formin 3 (DRF3/ Dia2) by RNA interference enhanced rates of oncosome formation, indicating that these structures resemble, and may be identical to, nonapoptotic membrane blebs, a feature of the amoeboid form of cell motility. Analysis of primary and metastatic human prostate tumors using 100K single nucleotide polymorphism arrays revealed a significantly higher frequency of deletion of the locus encoding DRF3 (DIAPH3) in metastatic tumors (P = 0.001) in comparison with organconfined tumors. Fluorescence in situ hybridization confirmed increased chromosomal loss of DIAPH3 in metastatic tumors in a different cohort of patients (P = 0.006). These data suggest that microvesicles shed from prostate cancer cells can alter the tumor microenvironment in a manner that may promote disease progression. They also show that DRF3 is a physiologically relevant protein that seems to regulate this process. [Cancer Res 2009;69(13):5601-9]

Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes

“…Finally, our results will also provide leads to identify specific markers of the medium-sized EVs, which probably correspond to large oncosomes described in some tumor cells (27,35,36). We show here that actinin-4 is abundant in medium-EVs, and underrepresented in sEVs.…”

Microvesicles: mediators of extracellular communication during cancer progression

“…In turn, the activated fibroblasts shed microvesicles to facilitate the migration and invasion of the prostate cancer line (Castellana et al, 2009). A similar feedback phenomenon was reported in yet another study, confirming the role of prostate-tumor-derived microvesicles in the 'activation' of stromal cells in the tumor microenvironment (Di Vizio et al, 2009). This study also identified increased chromosomal loss of the DIAPH3 locus in a cohort of prostate cancer patients, which encodes the diaphanous homolog 3 (DIAPH3) gene, suggesting that DIAPH3 is a physiologically relevant protein involved in this process.…”

Quantitative Proteomics Identifies a β-Catenin Network as an Element of the Signaling Response to Frizzled-8 Protein-Related Antiproliferative Factor

“…The "heavy" and "light" protein mixtures were resolved on a 12.5% SDS-PAGE gel, and visualized with Coomassie Blue R-250 staining solution. Each gel lane was excised into seven slices of similar size and cut into ϳ1 mm 3 particles prior to in-gel reduction, alkylation, and tryptic digestion as described (17,18). Tryptic peptides were extracted, dried down in a SpeedVac (Thermo Savant, Holbrook, NY), and stored at Ϫ80°C until mass spectrometric analysis.…”