REG3β modifies cell tumor function by impairing extracellular vesicle uptake

Abstract

Extracellular vesicles (EVs), including exosomes and microvesicles, are nano-sized membrane vesicles containing proteins and nucleic acids, which act as intercellular messengers. They play an important role in a variety of physiological processes, as well as in pathological situations such as inflammation or cancer. Here, we show that in the case of pancreatic ductal adenocarcinoma (PDAC), the healthy pancreatic tissue surrounding the tumor releases REG3β, a lectin that binds to the glycoproteins present in the surface of EVs, thus interfering with their uptake and internalization by target cells. In vitro, the disruption of the signaling mediated by EVs due to the presence of REG3β, prevents the EV-induced phenotypic switch in macrophages, inhibits the increased cell migration of cancer cells and reverses a number of metabolomic changes promoted by EVs. In vivo, the uptake of REG3β+ EVs by tumor cells is significantly impaired. Furthermore, it results in an increase of circulating REG3β+ EVs in blood of pancreatic cancer patients. Our findings highlight the effect of a lectin released by the healthy pancreatic tissue surrounding the tumor in modulating the EV-mediated interactions between different cell types in PDAC.

Analysis of extracellular vesicles generated from monocytes under conditions of lytic cell death

“…Equal amounts of protein were separated via SDS-PAGE in the presence of SeeBlue Plus2 Pre-stained Protein Standard (Thermo Fisher) followed by western transfer onto PVDF membrane. Membrane was blocked with 5% skim milk powder in 1 × PBS followed by overnight incubation with the primary antibodies to Alix [3A9] (Cell Signaling Technology, Danvers, MA) 32 , ARF6 [ab77581] (Abcam, Cambridge, UK) 33 , CD81 [M38] (Life technologies) 34 and Calreticulin [ab22683] (Abcam) 35 in 1% BSA in PBST at 4 °C, followed by three 10 min wash steps in PBST. Membranes were then incubated with HRP-conjugated sheep anti-mouse antibodies (1:5000, Millenium Science), Li-Cor goat-anti rabbit or goat anti-mouse IRDye 800CW (1:10000, Millennium Science) in 1% BSA in PBST for 1 h at RT, followed by washing as described for primary antibodies.…”

Extracellular vesicles as mediators of the progression and chemoresistance of pancreatic cancer and their potential clinical applications

“…In addition to suppressing EV secretion, inhibition of EV uptake may be another strategy in PC treatment. REG3β, a lectin that binds to EV surface, released by the normal pancreatic tissues surrounding tumor impaired the uptake of EVs by tumor cells both in vitro and vivo and inhibited the migration and metabolic changes in cancer cells [ 120 ]. All of these studies indicate that EVs may be a potential therapeutic target for the treatment of PC.…”

The Role of Extracellular Vesicles in Cancer: Cargo, Function, and Therapeutic Implications

“…In contrast to integrins, which direct EVs to their preferred targets, additional proteins have been identified which function to modify or block EV uptake. Along these lines, REG3β interferes with the uptake of EVs into target cells by binding to glycoproteins on the EV surface [ 113 ]. Similarly, CD47, an anti-phagocytic signal, was found to block uptake of EVs by immune cells, thus prolonging their time in circulation [ 114 ].…”