Large Oncosomes in Human Prostate Cancer Tissues and in the Circulation of Mice with Metastatic Disease

Abstract

Oncosomes are tumor-derived microvesicles that transmit signaling complexes between cell and tissue compartments. Herein, we show that amoeboid tumor cells export large (1- to 10-μm diameter) vesicles, derived from bulky cellular protrusions, that contain metalloproteinases, RNA, caveolin-1, and the GTPase ADP-ribosylation factor 6, and are biologically active toward tumor cells, endothelial cells, and fibroblasts. We describe methods by which large oncosomes can be selectively sorted by flow cytometry and analyzed independently of vesicles <1 μm. Structures resembling large oncosomes were identified in the circulation of different mouse models of prostate cancer, and their abundance correlated with tumor progression. Similar large vesicles were also identified in human tumor tissues, but they were not detected in the benign compartment. They were more abundant in metastases. Our results suggest that tumor microvesicles substantially larger than exosome-sized particles can be visualized and quantified in tissues and in the circulation, and isolated and characterized using clinically adaptable methods. These findings also suggest a mechanism by which migrating tumor cells condition the tumor microenvironment and distant sites, thereby potentiating advanced disease.

Large extracellular vesicles carry most of the tumour DNA circulating in prostate cancer patient plasma

“…DNA was also extracted from the EV supernatants (EV-free DNA). Quantification of the DNA in each fraction confirmed inter-patient variability, but nevertheless, L-EVs consistently contained more DNA than S-EVs (Figure 2(a)), corroborating our findings in this study (Figure 3(d)) and previous reports [7,8]. Also in line with our in vitro and in vivo results, the ssDNA:dsDNA ratio was 5:1 in three out of four patients (Figure 2(a)).…”

“…Even though L-EVs are produced by cancer cells and we did not expect to find them in plasma of control subjects, we quantified the amount of DNA in L-EVs from plasma of cancer-free individuals. Our results showed complete absence of DNA not only in L-EVs from normal plasma but also in S-EVs (Figure 3(d)), corroborating previous findings that circulating L-EVs are cancer-specific and they are the EV population carrying most of the DNA [7,8]. …”

Metabolic alterations in urine extracellular vesicles are associated to prostate cancer pathogenesis and progression

“…Importantly, in agreement with our result, it has already been reported that prostate cancer cells release large EVs named oncosomes with a size between 1 and 10 microns [31] that contain a distinct protein cargo [32]. They have also been detected in circulation in models of PCa and shown that their abundance correlate with tumoral progression [31]. Although, our studies have been focused in the smaller EVs, it is interesting that we have also observed this size effect.…”

“…Given that our EV isolation procedure (filtration through 0.22 microns, and ultracentrifugation at 10,000 × g) removed most of the large EVs from the sample, and enrich in small EVs (mostly exosomes and small microvesicles), this difference could be underestimated in our samples. Importantly, in agreement with our result, it has already been reported that prostate cancer cells release large EVs named oncosomes with a size between 1 and 10 microns [31] that contain a distinct protein cargo [32]. They have also been detected in circulation in models of PCa and shown that their abundance correlate with tumoral progression [31].…”

Prostasomes as a source of diagnostic biomarkers for prostate cancer

“…Tumor cell-derived EVs have been described for different types of cancer (38) and are reported to contain cancer-specific content, including oncoproteins, mutant transcripts, and cancer-specific microRNAs (miRNAs) (39,40). Both neoplastic and metastatic PCa cells have been demonstrated to release prostasomes (27,36,(41)(42)(43)(44)(45)(46). Observations that prostasomes isolated from PCa patients stimulated in vitro tumor cell proliferation and invasion are consistent with the general idea that EVs from tumor cells can stimulate tumor growth and metastasis and can modulate surrounding cells to promote tumor growth (9,(47)(48)(49)(50).…”