Microvesicles expressing adenosinergic ectoenzymes and their potential role in modulating bone marrow infiltration by neuroblastoma cells

Abstract

Metastatic diffusion of Neuroblastoma (NB) cells in the bone marrow (BM) represents the most negative prognostic factors for NB patients. Multiple immune escape mechanisms are postulated as responsible. Our working hypothesis is that adenosine (ADO), an immunosuppressive molecule along with the ectoenzymatic pathways (CD39-CD73 and CD38-CD203a/PC-1-CD73) controlling its production, are involved in the dynamics of NB cells in the BM. The results indicate that ectonucleotidases are expressed by i) NB cell lines, ii) metastatic NB cells isolated from NB patients' BM, iii) microvesicles (MV) derived from both NB cell types and iv) resident BM cell populations. BM infiltration by NB cells increased CD203a/PC-1 and CD73 expression on lymphoid and myeloid cells, respectively. Expressions of ectoenzymes and GD2 (NB-associated marker) were higher on MV from NB patients' BM than in controls. Moreover, CD203a/PC-1 expression on BM-derived MV provide a basis for distinguishing NB patients with high or low BM infiltration. ADO production and consumption of related by-products were significantly higher when assessed on NB patients' MV than those from controls. MV isolated from NB patients' BM significantly downregulated in vitro T cell proliferation. Lastly, NB patients with worse prognosis are identified by a high percentage of CD38 + or CD73 + MV in the BM. In conclusion, ectonucleotidases are present and functional on NB cells, as well as in NB-infiltrated BM and in MV derived from BM. It is reasonable that MV are involved in BM infiltration by NB cells. Therefore, targeting these molecules may widen the therapeutic armamentarium for metastatic NB patients. ARTICLE HISTORY

CD38, a Receptor with Multifunctional Activities: From Modulatory Functions on Regulatory Cell Subsets and Extracellular Vesicles, to a Target for Therapeutic Strategies

“…Similar results were obtained analyzing EVs from NB patients [71]. Constitutive high levels of CD38, CD203a, CD39 and CD73 expression have been described (superior to those from healthy controls) in terms of (i) percentage of positive EVs, and (ii) levels of expression, witnessed by a higher fluorescence intensity.…”

“…Interestingly, our study also described as CD38 + and CD73 + EVs in the BM negatively affected the event-free survival of NB patients, confirming their critical impact on the immune-privileged microenvironment of neoplastic cells, that, in turn, support the metastatic spread of NB cells [71].…”

“…Our group has recently carried out two different sets of studies aimed to characterize the expression and function of CD38, along with other ecto-enzymes, on EVs isolated from patients with MM [70] and neuroblastoma (NB) [71].…”

On the mechanism of anti-CD39 immune checkpoint therapy

“…92 Various tumor cell types have been reported to generate CD39 + EVs, including ovarian cancer, prostate cancer, multiple myeloma, neuroblastoma, and head and neck cancer. [92][93][94][95] More recently, it was shown that B cells also produce high levels of EVs expressing CD39 and CD73, which significantly suppress antitumor immunity, particularly in response to chemotherapy. Notably, administration of B cell-derived EVs abrogated chemotherapymediated tumor-specific CD8 + T cells increase in mice, which was prevented by pretreatment of EVs with a CD39 inhibitor (POM-1) or a CD73 inhibitor (APCP).…”

Human Amnion Epithelial Cells Impair T Cell Proliferation: The Role of HLA-G and HLA-E Molecules

“…Among other surface molecules, microvesicles express integrins, selectins, CD40 or CD81, and are involved in intercellular communications, being captured by target cells through endocytosis, receptor-mediated endocytosis or fusion with the plasma membrane [38,39]. We have previously described that EVs released by tumor cells may carry some immunomodulatory molecules (i.e., adenosinergic ectoenzymes), contributing to the inhibition of the host antitumor immune response [40,41]. Moreover, several studies reported the role of HLA-G-bearing EV in modulation of an immune response in normal pregnancy or neoplastic context [42].…”