The αvβ3 integrin has been shown to promote aggressive phenotypes in many types of cancers, including prostate cancer. We show that GFP-labeled αvβ3 derived from cancer cells circulates in the blood and is detected in distant lesions in NOD scid gamma (NSG) mice. We, therefore, hypothesized that αvβ3 travels through exosomes and tested its levels in pools of vesicles, which we designate extracellular vesicles highly enriched in exosomes (ExVs), and in exosomes isolated from the plasma of prostate cancer patients. Here, we show that the αvβ3 integrin is found in patient blood exosomes purified by sucrose or iodixanol density gradients. In addition, we provide evidence that the αvβ3 integrin is transferred through ExVs isolated from prostate cancer patient plasma to β3-negative recipient cells. We also demonstrate the intracellular localization of β3-GFP transferred via cancer cell-derived ExVs. We show that the ExVs present in plasma from prostate cancer patients contain higher levels of αvβ3 and CD9 as compared to plasma ExVs from age-matched subjects who are not affected by cancer. Furthermore, using PSMA antibody-bead mediated immunocapture, we show that the αvβ3 integrin is expressed in a subset of exosomes characterized by PSMA, CD9, CD63, and an epithelial-specific marker, Trop-2. Finally, we present evidence that the levels of αvβ3, CD63, and CD9 remain unaltered in ExVs isolated from the blood of prostate cancer patients treated with enzalutamide. Our results suggest that detecting exosomal αvβ3 integrin in prostate cancer patients could be a clinically useful and non-invasive biomarker to follow prostate cancer progression. Moreover, the ability of αvβ3 integrin to be transferred from ExVs to recipient cells provides a strong rationale for further investigating the role of αvβ3 integrin in the pathogenesis of prostate cancer and as a potential therapeutic target.

Therapeutic approaches aimed at curing prostate cancer are only partially successful given the occurrence of highly metastatic resistant phenotypes that frequently develop in response to therapies. Recently, we have described αvβ6, a surface receptor of the integrin family as a novel therapeutic target for prostate cancer; this epithelial-specific molecule is an ideal target since, unlike other integrins, it is found in different types of cancer but not in normal tissues. We describe a novel αvβ6-mediated signaling pathway that has profound effects on the microenvironment. We show that αvβ6 is transferred from cancer cells to monocytes, including β6-null monocytes, by exosomes and that monocytes from prostate cancer patients, but not from healthy volunteers, express αvβ6. Cancer cell exosomes, purified via density gradients, promote M2 polarization, whereas αvβ6 down-regulation in exosomes inhibits M2 polarization in recipient monocytes. Also, as evaluated by our proteomic analysis, αvβ6 down-regulation causes a significant increase in donor cancer cells, and their exosomes, of two molecules that have a tumor suppressive role, STAT1 and MX1/2. Finally, using the Pten prostate cancer mouse model, which carries a prostate epithelial-specific Pten deletion, we demonstrate that αvβ6 inhibition in vivo causes up-regulation of STAT1 in cancer cells. Our results provide evidence of a novel mechanism that regulates M2 polarization and prostate cancer progression through transfer of αvβ6 from cancer cells to monocytes through exosomes.

PURPOSE Germline testing (GT) for prostate cancer (PCA) is now central to treatment and hereditary cancer assessment. With rising demand for and shortage of genetic counseling (GC), tools to deliver pretest informed consent across practice settings are needed to improve access to GT and precision care. Here, we report on Evaluation and Management for Prostate Oncology, Wellness, and Risk (EMPOWER), a patient-choice study for pretest video-based genetic education (VBGE) versus GC to inform urgent practice needs. PATIENTS AND METHODS Men with PCA or at risk for PCA (family history of PCA) were eligible and could choose pretest VBGE or GC. Outcomes included decisional conflict for GT, change in genetics knowledge, satisfaction, and intention to share results with family and/or providers. Descriptive statistics summarized results with counts and percentages for categorical variables and mean ± standard deviation for continuous variables. Data were compared with Fisher's exact, chi-squared, or Wilcoxon two-sample tests. Mean change in genetics knowledge was compared with t tests. The significance level was set a priori at .05. RESULTS Data on the first 127 participants were analyzed. Characteristics were White (85.8%), bachelor's degree (66.9%), and PCA diagnosis (90.6%). The majority chose VBGE (71%) versus GC (29%; P < .001). No differences were observed in decisional conflict for GT or satisfaction. Cancer genetics knowledge improved in both groups without significant difference (+0.9 VBGE, +1.8 GC, P = .056). Men who chose VBGE had higher intention to share GT results (96.4% VBGE v 86.4% GC, P = .02). Both groups had high rates of GT uptake (VBGE 94.4%, GC 92%). CONCLUSION A substantial proportion of men opted for pretest VBGE, with comparable patient-reported outcomes and uptake of GT. The results support the use of pretest video to address the critical GC shortage in the precision era.

Cells are known to release different types of vesicles such as small extracellular vesicles (sEVs) and large extracellular vesicles (LEVs). sEVs and LEVs play important roles in intercellular communication, pre-metastatic niche formation, and disease progression; both can be detected cell culture media and biological fluids. sEVs and LEVs contain a variety of protein and RNA cargo, and they are believed to impact many biological functions of the recipient cells upon their internalization or binding to cell surface proteins. It has recently been established that standard isolation techniques, such as differential ultracentrifugation, yield a mixed population of EVs. However, density gradient ultracentrifugation has been reported to allow the isolation of sEVs without cellular debris. Here, we describe the most common methods used to isolate sEVs from cell culture medium, mouse and human plasma, and a new technique for isolating sEVs from tissues as well. This article also provides detailed procedures to isolate LEVs.