CD73 Downregulation Decreases In Vitro and In Vivo Glioblastoma Growth

Abstract

Glioblastoma is the worst and most common primary brain tumor. Here, we demonstrated the role of CD73, an enzyme responsible for adenosine (ADO) production, in glioblastoma progression. ADO increased glioma cell viability via A1 receptor sensitization. CD73 downregulation decreased glioma cell migration and invasion by reducing metalloproteinase-2 and vimentin expression and reduced cell proliferation by 40%, which was related to necrosis and sub-G1 phase blockage of cell cycle. Those effects also involved the stimulation of Akt/NF-kB pathways. Additionally, CD73 knockdown or enzyme inhibition potentiated temozolomide cytotoxic effect on glioma cells by decreasing the IC value and sensitizing cells to a non-cytotoxic drug concentration. CD73 inhibition also decreased in vivo rat glioblastoma progression. Delivery of siRNA-CD73 or APCP reduced tumor size by 45 and 40%, respectively, when compared with control. This effect was followed by a parallel 95% reduction of ADO levels in cerebrospinal fluid, indicating the role of extracellular ADO in in vivo glioma growth. Treatment did not induce systemic damage or mortality. Altogether, we conclude that CD73 is an interesting target for glioblastoma treatment and its inhibition may provide new opportunities to improve the treatment of brain tumors. Graphical Abstract ᅟ.

High Adenosine Extracellular Levels Induce Glioblastoma Aggressive Traits Modulating the Mesenchymal Stromal Cell Secretome

“…The variation of gene expression not completely reflect the profile of GMT protein expression demonstrating that, even though ADO could induce some traits of the mesenchymal phenotype, it is not able to trigger a complete transition. These results are in accordance with the ability of ADO to promote the Vimentin gene expression in C6 rat glioma cells [ 76 ] and strengthen the pivotal role exerted by extracellular ADO in the control of glioma aggressive traits in human cells. Interestingly, ADO regulates the induction of GMT in U343MG almost in part through the increase of ERK1/2 phosphorylation.…”

“…Herein, we demonstrate that the prolonged exposure to a high ADO concentration (100 µM) promotes the glioma motility in vitro. This result is in accordance with the ability of CD73 to enhance cell adhesion through ADO production, thereby promoting cell migration and invasion in different cancer cells and in glioma cells [ 29 , 38 , 76 , 82 ].…”

“…Our results demonstrate that the chronic exposure of up to micromolar extracellular ADO concentration does not significantly modify glioblastoma cell proliferation. The reduction of ADO production by the CD73 inhibition causes the decrease of glioma proliferation in vitro and in vivo [ 33 , 76 ]. Similarly, a single administration of 100 µM ADO concentration enhances the human U138MG glioma cell proliferation in vitro [ 77 ].…”

Immune checkpoint molecules in natural killer cells as potential targets for cancer immunotherapy

“…242 , 291 Part of the evidence to support the role of CD39 and CD73 in tumorigenesis and inflammation is that mice deficient in CD73 or CD39 are susceptible to autoimmunity/inflammation and be tumor resistant as a result of ADO-mediated immunosuppression alleviation. 292 – 294 …”

Single-Cell Approaches to Profile the Response to Immune Checkpoint Inhibitors

“…Through mass cytometry and scRNA-seq, in GMB a unique subset of macrophages expressing high levels of CD73 able to persist after anti-PD-1 therapy was observed (88). Notably, a number of reports have shown that CD73 can induce immunosuppression in GMB (157,158).…”