Exosomal ITGA3 interferes with non‐cancerous prostate cell functions and is increased in urine exosomes of metastatic prostate cancer patients

Abstract

BackgroundCancer cells are able to change the protein expression and behavior of non-cancerous surrounding cells. Exosomes, secreted by prostate cancer (PCa) cells, may have a functional role in cancer metastasis and present a promising source for protein biomarkers. The aim of the present study was to identify which proteins in exosomes can influence non-cancerous cells, and to determine whether we can use urine exosomal proteins to identify high-risk PCa patients.MethodExosomes were isolated by ultracentrifugation. Migration and invasion were studied by the transwell (invasion) assay. Proteomics was performed by LC-MS/MS and identified proteins were validated by Western blotting. Cellular uptake of fluorescent labeled PKH67-exosomes was measured by FACS.ResultsBased on comparative protein profiling by mass spectrometry-based proteomics of LNCaP- and PC3-exosomes, we selected ITGA3 and ITGB1, involved in migration/invasion, for further analyses. Inhibition of exosomal ITGA3 reduced the migration and invasion of non-cancerous prostate epithelial cells (prEC) almost completely. Cellular uptake of exosomes by prEC was higher with PC3-exosomes compared to LNCaP exosomes. Finally, ITGA3 and ITGB1 were more abundant in urine exosomes of metastatic patients (p<0.05), compared to benign prostate hyperplasia or PCa.ConclusionThese data indicate exosomal ITGA3 and ITGB1 may play a role in manipulating non-cancerous surrounding cells and that measurement of ITGA3 and ITGB1 in urine exosomes has the potential to identify patients with metastatic PCa in a non-invasive manner.

The αvβ6 Integrin Is Transferred Intercellularly via Exosomes

“…Finally, our study is the first to show that the ␣ v ␤ 6 integrin that is transferred between different subsets of PrCa cells is functional and promotes cell adhesion and migration on LAP-TGF␤ in an ␣ v ␤ 6 integrin-dependent manner. Previous studies have suggested but not proven, or excluded, that exosomal transfer of integrins, as well as of other molecules such as heparanase, promotes cell motility on ECM in recipient cells (29,39). In contrast, Lee et al (40) demonstrate that exosomes released from human macrophages negatively regulate endothelial cell migration, promoting the internalization and degradation of the ␤ 1 integrin subunit in the recipient cells.…”

“…Proteomic analysis has shown that ␣ 2 , ␣ 3 , ␣ 6 , ␤ 1 , and ␤ 4 integrin subunits are found in microvesicles from PrCa cells (28). In addition, a recent study has shown that the presence of the ␣ 3 integrin subunit in PrCa cell derived-exosomes interferes with non-cancerous prostate cell functions (29). Moreover, Clayton et al (30) have shown that B cell-derived exosomes express functional ␤ 1 and ␤ 2 integrins that are capable of mediating anchorage to the extracellular matrix (ECM).…”

The emerging role of extracellular vesicles as biomarkers for urogenital cancers

“…129 Other studies have also investigated the proteo mic cargo of prostate-derived extracellular vesicles from urine. [130][131][132][133] Increased levels of α1-integrin and β1-integrin were found in urine exosomes of patients with metastatic prostate cancer, compared with patients The flowchart shows a step-by-step process by which the profiling and discovery of exosomal cargo molecules could ultimately be translated into a clinically applicable biomarker signature. At each step defined goals and criteria must be met in order to proceed to the next level.…”

“…163 with nonmetastatic disease or those with BPH. 130 Likewise, δ-catenin associated with extracellular vesicles has been found at high levels in urine, 131 whereas prostate-specific membrane antigen and prostate stem cell antigen have also been identified in urine-derived exosomes of patients with prostate cancer. 26,29,129 In addition to exosomal protein markers, some transcriptomic changes have also been identified, including those affecting the expression of TMPRSS2 and, of course, PCA3.…”

Role of exosomes and microvesicles in hypoxia‐associated tumour development and cardiovascular disease

“…EV release appears to be a general biological process, and EVs have been detected in biological fluids such as blood, breastmilk, saliva [55,56] and urine [57]. EVs can thus be recovered from biological fluids and cell cultures for monitoring of specific pathophysiological processes.…”