Specific Activation of A3, A2A and A1 Adenosine Receptors in CD73-Knockout Mice Affects B16F10 Melanoma Growth, Neovascularization, Angiogenesis and Macrophage Infiltration

Abstract

CD73 (ecto-5'-nucleotidase), a cell surface enzyme hydrolyzing AMP to adenosine, was lately demonstrated to play a direct role in tumor progression including regulation of tumor vascularization. It was also shown to stimulate tumor macrophage infiltration. Interstitial adenosine, accumulating in solid tumors due to CD73 enzymatic activity, is recognized as a main mediator regulating the production of pro- and anti-angiogenic factors, but the engagement of specific adenosine receptors in tumor progression in vivo is still poorly researched. We have analyzed the role of high affinity adenosine receptors A1, A2A, and A3 in B16F10 melanoma progression using specific agonists (CCPA, CGS-21680 and IB-MECA, respectively). We limited endogenous extracellular adenosine background using CD73 knockout mice treated with CD73 chemical inhibitor, AOPCP (adenosine α,β-methylene 5’-diphosphate). Activation of any adenosine receptor significantly inhibited B16F10 melanoma growth but only at its early stage. At 14th day of growth, the decrease in tumor neovascularization and MAPK pathway activation induced by CD73 depletion was reversed by all agonists. Activation of A1AR primarily increased angiogenic activation measured by expression of VEGF-R2 on tumor blood vessels. However, mainly A3AR activation increased both the microvessel density and expression of pro-angiogenic factors. All agonists induced significant increase in macrophage tumor infiltration, with IB-MECA being most effective. This effect was accompanied by substantial changes in cytokines regulating macrophage polarization between pro-inflammatory and pro-angiogenic phenotype. Our results demonstrate an evidence that each of the analyzed receptors has a specific role in the stimulation of tumor angiogenesis and confirm significantly more multifaceted role of adenosine in its regulation than was already observed. They also reveal previously unexplored consequences to extracellular adenosine signaling depletion in recently proposed anti-CD73 cancer therapy.

Anti‐angiogenic effects of CD73‐specific siRNA‐loaded nanoparticles in breast cancer‐bearing mice

“…Our results were demonstrated that CD73‐targeting in the tumor microenvironment through an application of the CD73 siRNA‐loaded NPs could potently suppress the tumor growth, increase the mice survival‐time, and enhance anti‐tumor immune responses (Jadidi‐Niaragh et al, ). Regarding the importance of angiogenesis in the tumor progression and initiation of metastasis and the key function of the adenosine in the angiogenesis (Koszałka et al, ; Sorrentino, Miele, Porta, Pinto, & Morello, ), we examined the anti‐angiogenic potential of our previous therapeutic approach (Jadidi‐Niaragh et al, ) in the tumor‐bearing mice in the current study.…”

Adenosine deaminase inhibition suppresses progression of 4T1 murine breast cancer by adenosine receptor‐dependent mechanisms

“…Other antitumour mechanism of dCF could be related with the modulation of angiogenesis, an important aspect in tumour growth. Even though adenosine is known as a proangiogenic factor, dCF treatment increased the percentage of tumour necrosis while reducing tumour size in 4T1 mouse model, suggesting down‐regulation of tumour vascularization. As the effect of dCF on endothelial cell migration in vitro was minor, other antiangiogenic mechanisms should be considered, for example the inhibition of macrophage induced angiogenesis …”

The Adenosine A1 Receptor Antagonist DPCPX Inhibits Tumor Progression via the ERK/JNK Pathway in Renal Cell Carcinoma

“…However, the results are controversial. It has been documented that the A1R agonist could inhibit cell proliferation in colonic cancer, astrocytoma and melanoma cells [9, 10, 17]. In contrast, several studies also showed that the A1R antagonists could reduce cell proliferation [13, 18].…”