Phosphoproteins in extracellular vesicles as candidate markers for breast cancer

Abstract

Significance Protein phosphorylation is a major regulatory mechanism for many cellular functions, but no phosphoprotein in biofluids has been developed for disease diagnosis because of the presence of active phosphatases. This study presents a general strategy to isolate and identify phosphoproteins in extracellular vesicles (EVs) from human plasma as potential markers to differentiate disease from healthy states. We identified close to 10,000 unique phosphopeptides in EVs from small volumes of plasma samples and more than 100 phosphoproteins in plasma EVs that are significantly higher in patients diagnosed with breast cancer as compared with healthy controls. This study demonstrates that the development of phosphoproteins in plasma EVs as disease biomarkers is highly feasible and may transform cancer screening and monitoring.

Ubiquitin Conjugation Probed by Inflammation in Myeloid-Derived Suppressor Cell Extracellular Vesicles

“…3,4 Bioactive roles have been proposed by others for modified proteoforms in tumor EV, most notably phosphorylation. 8,12 Since ubiquitination is thought to play a role in the selection of exosomal protein cargo, we have examined and report here the effect of inflammation on ubiquitin-conjugated proteins in EV produced by MDSC.…”

The biology of extracellular microvesicles

“…A recent analysis of MVs in the blood of patients with locally advanced or metastatic lung, breast, colorectal or head & neck cancers indicated that the profile of the protein markers MUC1, EGFR and EpCAM correlated with tumor subtype, whereas the MMP‐inducer EMMPRIN was increased regardless of tumor type and the increased abundance of EMMPRIN‐positive MVs correlated strongly with poor overall survival . Another recent study demonstrated the differential phosphorylation of an array of proteins found in exosomes and MVs isolated from plasma in breast cancer patients as compared to healthy controls . In plasma cell dyscrasias such as multiple myeloma, free antibody light chains in the blood are a prominent characteristic of disease, and these may be circulated through the bloodstream within MVs that also contain Hsp70, annexin V and c‐src, presenting diagnostic possibilities and indicating the mode of cargo transfer between cells.…”

Extracellular vesicles in the tumor microenvironment: Therapeutic resistance, clinical biomarkers, and targeting strategies

“…A novel strategy was recently established to isolate and identify phosphoproteins in human plasma EVs, revealing 144 phosphoproteins of circulating EVs significantly higher in breast cancer patients than in healthy controls . Liquid biopsies with biofluids including plasma and urine have attracted substantial attention in recent years, by offering diverse advantages in clinical settings due to their noninvasive nature.…”

“…Liquid biopsies with biofluids including plasma and urine have attracted substantial attention in recent years, by offering diverse advantages in clinical settings due to their noninvasive nature. In contrast to circulating tumor cell (CTC) and circulating tumor DNA (ctDNA), which frequently have sampling limitation in clinics, EVs act as a potential substitute for these tools, and their phosphoproteins are practically subject to mass spectrometry (MS) based proteomic quantitation and molecular profiling . Thus, the clinical value of phosphoproteins in plasma EVs is demonstrated as important biomarkers, which may provide a new modality of cancer screening and monitoring in future medicine.…”