Prostate cancer extracellular vesicles mediate intercellular communication with bone marrow cells and promote metastasis in a cholesterol‐dependent manner

Abstract

Primary tumours can establish long‐range communication with distant organs to transform them into fertile soil for circulating tumour cells to implant and proliferate, a process called pre‐metastatic niche (PMN) formation. Tumour‐derived extracellular vesicles (EV) are potent mediators of PMN formation due to their diverse complement of pro‐malignant molecular cargo and their propensity to target specific cell types (Costa‐Silva et al., 2015; Hoshino et al., 2015; Peinado et al., 2012; Peinado et al., 2017). While significant progress has been made to understand the mechanisms by which pro‐metastatic EVs create tumour‐favouring microenvironments at pre‐metastatic organ sites, comparatively little attention has been paid to the factors intrinsic to recipient cells that may modify the extent to which pro‐metastatic EV signalling is received and transduced. Here, we investigated the role of recipient cell cholesterol homeostasis in prostate cancer (PCa) EV‐mediated signalling and metastasis. Using a bone metastatic model of enzalutamide‐resistant PCa, we first characterized an axis of EV‐mediated communication between PCa cells and bone marrow that is marked by in vitro and in vivo PCa EV uptake by bone marrow myeloid cells, activation of NF‐κB signalling, enhanced osteoclast differentiation, and reduced myeloid thrombospondin‐1 expression. We then employed a targeted, biomimetic approach to reduce myeloid cell cholesterol in vitro and in vivo prior to conditioning with PCa EVs. Reducing myeloid cell cholesterol prevented the uptake of PCa EVs by recipient myeloid cells, abolished NF‐κB activity and osteoclast differentiation, stabilized thrombospondin‐1 expression, and reduced metastatic burden by 77%. These results demonstrate that cholesterol homeostasis in bone marrow myeloid cells regulates pro‐metastatic EV signalling and metastasis by acting as a gatekeeper for EV signal transduction.

Extracellular Vesicles Facilitate Large-Scale, Homogenizing Dynamic Exchange of Proteins and RNA Among Cultured Chinese Hamster Ovary (CHO) and Human Cells

“…As observed in this study, EVs from the acute megakaryoblastic leukemia cell line CHRF-288-11 were readily taken up by HSPCs in coculture, suggesting cancer cells can influence the expression of stem cells. Studies have reported on the effects of cancer cell derived EVs on stem cells (Chin & Wang, 2016; Daßler-Plenker, Küttner, & Egeblad, 2020; Henrich et al, 2020) and in this study we were able to observe the large extent of cancer-derived EVs uptake by HSPCs.…”

Role of Exosomes in Prostate Cancer Metastasis

“…The formation of PMN involves persistent long-range intercellular communication mediated by soluble or membrane-bound factors originating from the primary tumor [113,116]. These factors traverse through vascular and interstitial spaces and eventually engage with the cholesterolrich plasma membrane of recipient cells at pre-metastatic organ sites [117]. Tumor-derived exosomes remodel the ECM by accumulating fibronectin and promoting ECM-modifying enzyme lysyl oxidase (LOX) crosslinking to enhance the adhesion of the bone-marrowderived cells which are essential pre-metastatic niche components [113,118,119].…”

“…Tumor-derived exosomes remodel the ECM by accumulating fibronectin and promoting ECM-modifying enzyme lysyl oxidase (LOX) crosslinking to enhance the adhesion of the bone-marrowderived cells which are essential pre-metastatic niche components [113,118,119]. Interestingly, a recent study elegantly demonstrates that EV-mediated communication between PCa cells and bone marrow is mediated by cholesterol homeostasis in bone marrow myeloid cells [117]. They showed that PCa EV uptake by bone marrow myeloid cells in vitro and in vivo leads to activated NF-κB signaling, reduced myeloid thrombospondin-1 expression and enhanced osteoclast differentiation.…”

“…They showed that PCa EV uptake by bone marrow myeloid cells in vitro and in vivo leads to activated NF-κB signaling, reduced myeloid thrombospondin-1 expression and enhanced osteoclast differentiation. A reduction of myeloid cell cholesterol in vitro and in vivo via a targeted, biomimetic approach prior to conditioning with PCa EVs prevented the uptake of PCa EVs by recipient myeloid cells, abolished NF-κB activity, decreased osteoclast differentiation, stabilized thrombospondin-1 expression and led to reduction of metastatic burden by 77% [117]. In another study, the authors demonstrate a role for phospholipase D2 in stimulating exosome secretion in PCa cell line models as well as a potential to increase osteoblast activity, thereby promoting the establishment of PCa bone metastasis [120].…”

Emerging Role of Extracellular Vesicles in Prostate Cancer

“…The protein transfer of pyruvate kinase M2 from EVs to these recipient cells led to increased levels of the chemokine CXCL12 in a HIF-1α–dependent mechanism ( 77 ), which likely contributed to an inflammatory response ( 78 ) that prepared the premetastatic niche. Additionally, the introduction of EVs derived from the enzalutamide resistant PCa cell line CW-R1 resulted in NF-κB signaling and enhanced osteoclast differentiation in bone marrow stromal cells ( 79 ), which is an initial step in reprogramming the bone microenvironment to allow for tumor cell proliferation and metastasis ( 80 ).…”