Adenosine A3 receptor elicits chemoresistance mediated by multiple resistance-associated protein-1 in human glioblastoma stem-like cells

Abstract

MRP1 transporter correlates positively with glioma malignancy and the Multiple Drug Resistance (MDR) phenotype in Glioblastoma Multiforme (GBM). Evidence shows that the MRP1 transporter is controlled by the adenosine signalling axis. The aim of this study was to identify the role of adenosine on the MDR phenotype in Glioblastoma Stem-like Cells (GSCs), the cell population responsible for the tumorigenic and chemoresistance capabilities of this tumour. We found that GSCs have increased intrinsic capacity to generate extracellular adenosine, thus controlling MRP1 transporter expression and activity via activation of the adenosine A3 receptor (A3AR). We showed PI3K/Akt and MEK/ERK1/2 signaling pathways downstream A3AR to control MRP1 in GSCs. In vitro pharmacological blockade of A3AR had a chemosensitizing effect, enhancing the actions of antitumour drugs and decreasing cell viability and proliferation of GSCs. In addition, we produced an in vivo xenograft model by subcutaneous inoculation of human GSCs in NOD/SCID-IL2Rg null mice. Pharmacological blockade of A3AR generated a chemosensitizing effect, enhancing the effectiveness of the MRP1 transporter substrate, vincristine, reducing tumour size and the levels of CD44 and Nestin stem cell markers as well as the Ki-67 proliferation indicator. In conclusion, we demonstrated the chemosensitizing effect of A3AR blockade on GSCs.

A3 Adenosine Receptors as Modulators of Inflammation: From Medicinal Chemistry to Therapy

“…As a consequence, A 3 AR antagonist administration provoked a potentiating effect on the reduction in tumor size induced by the chemotherapic vincristine. 245 In addition, an increase of glioblastoma cell invasion, through A 3 AR and MMP-9 stimulation, was found, as already shown in macrophages. 74,291 However, a potential therapeutic effect of agonists in cancer has been also reported moving from initial studies on the observation that tumor metastases were infrequent in striated muscles.…”

“…Furthermore, a basal stimulation through A 3 AR was responsible for an increased MRP1 expression in glioblastoma cells. As a consequence, A 3 AR antagonist administration provoked a potentiating effect on the reduction in tumor size induced by the chemotherapic vincristine . In addition, an increase of glioblastoma cell invasion, through A 3 AR and MMP‐9 stimulation, was found, as already shown in macrophages .…”

“…74,244 MEK/ERK1/2 and PI3K/Akt signaling pathways downstream of the A 3 AR control multiple resistance-associated protein 1 (MRP1) transporter substrate in glioblastoma cells, demonstrating a chemosensitizing effect by pharmacological blockade of A 3 AR and consequent reduction in tumor size. 245 A pathway involving Akt phosphorylation protects RBL-2H3 and glioblastoma cells from apoptosis, while the same pathway produced an antiproliferative effect and increase in MMP-9 in A375 and glioblastoma cells, respectively. 74,236,246,247 On the other hand, A 3 AR-mediated activation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt signaling pathway enhances pigmentation in B16 melanoma cells and in human skin explants.…”

“…Concerning c‐Jun N‐terminal kinase (JNK), its activation by A 3 AR has been retrieved in microglia and glioblastoma cells, leading to cell migration and matrix metalloproteinase 9 (MMP‐9) stimulation, respectively . MEK/ERK1/2 and PI3K/Akt signaling pathways downstream of the A 3 AR control multiple resistance‐associated protein 1 (MRP1) transporter substrate in glioblastoma cells, demonstrating a chemosensitizing effect by pharmacological blockade of A 3 AR and consequent reduction in tumor size …”

Extracellular Vesicles in Glioblastoma Tumor Microenvironment

“…GBMs infiltrate rapidly infiltrating by generating satellite tumors making complete surgical resection impossible eventually resulting in recurrence (109). The stemness phenotype of GSCs, glutamate induced Ca 2+ influx (110), Wnt (111,112), and PI3/Akt (113) signaling pathway induced MMP release, β catenin degradation pathway (114) as well as the release of soluble factors, proteases, glycosidases allow GBM cells to invade and migrate locally (115).…”