Journal: bioRxiv
Article Title: Inhibition of the Adenosine pathway activates the immune response against Mesothelioma
doi: 10.64898/2026.05.08.722957
Figure Lengend Snippet: Western blot analyses confirmed the expression of A2Br and CD73 in murine Me cell lines: AB1 (sarcomatoid), AB22 (biphasic) and AB12 (epithelioid). Band densities were normalized against their respective GAPDH ( 4a ). A schematic representation of the program followed during the development of the orthotopic model of the Me was reported ( 4b ). Immunocompetent BALB/C mice were inoculated with 10^5 AB1-B/c-LUC cells i.p.----Three days after, mice were randomized into six groups and treated q3days × 3 weeks: 1) PBS 100 μl (control= ctr); 2) aPD-1 (4.4 mg/Kg); 3) TT-4 (a clinic ready, selective A2Bri, Ki = 9.1nM, Portage Biotech, 3 mg/Kg); 4) AB680 (CD73i, 3 mg/Kg); 5) TT-4 plus aPD-1; 6) AB680 plus aPD-1. Tumor volumes were monitored over 21 days via IVIS bioluminescence imaging following luciferin administration. Signal intensity (ROI) was quantified using Living Image Software 4.1 (Revvity). Representative bioluminescence images of three mice/group at the start (T0) and end of treatment (T21) are shown, normalized to the fluorescence scale on the right ( 4c ). The curves report the mean ± standard error of the mean (SEM) of individual tumor volumes of mice at the indicated time point (n=5). Statistical differences were assessed by two-way ANOVA with Tukey’s multiple comparisons test (** p < 0.01, **** p< 0.0001, 4d ). Body was tracked throughout the study as an indicator of treatment-related toxicity and is presented as means ± SEM in the graph ( 4e ). Formalin-fixed, paraffin-embedded tumor samples were sectioned (41μm), stained with hematoxylin and eosin for morphological assessment, and evaluated under a light microscope (40× magnification). Stained sections were semi-quantitatively evaluated for the percentage and localization of positive cells, focusing on CD3 + , CD45 + and PD-L1 markers ( 4f ). Across all groups, neoplastic cells displayed typical mesothelioma morphology-intertwined bundles with mild to moderate extracellular matrix and moderate mitotic activity (2–3/HPF). Inflammatory infiltrate was minimal in the control and aPD-1-only groups. In contrast, tumors from the TT-4 and AB680 groups exhibited moderate to severe lymphoplasmacytic infiltration (arrows), with no significant differences between them. Combination treatments (TT-4 + aPD-1 and AB680 + aPD-1) showed multifocal, chronic lymphoplasmacytic infiltrates often localized around necrotic areas (asterisks), again with no significant difference between these two groups. Immunohistochemical analysis confirmed T and B cell infiltration (CD3+ and CD45+), with CD45 expression significantly higher in all treatment groups compared to control. PD-L1 was expressed in neoplastic cells across all groups compared to control and aPD-1 monotherapy groups.
Article Snippet: MCSs were generated as described above in 96 multi-well plates and treated with the CD73 inhibitor AB680 (Cat. No.: HY-125286, MedChemExpress).
Techniques: Western Blot, Expressing, Control, Imaging, Software, Fluorescence, Formalin-fixed Paraffin-Embedded, Staining, Light Microscopy, Activity Assay, Immunohistochemical staining