Fig. 8: Spatially resolved signatures pertaining to MGAT1_high/CD73_high are associated with unfavorable immune responses.

a Representative staining of MGAT1, CD73, and PanCK, followed by the selection of regions of interest (ROI) (n = 32) and subsequent auto-segmentation in TNBC tissue sections using GeoMX DSP. b, c CIBERSORTx analysis of the relative abundance of individual cell populations between MGAT1lo and MGAT1hi areas (b) or between MGAT1loCD73lo (DL) and MGAT1hiCD73hi areas (DH) (c) among nontumor compartments using transcriptomics data. d Representative composite image (left panel) with inset (right) of a breast cancer specimen stained by multicolor IHC comprising CD8, Ki67, CD3, CD73, MGAT1, PanCK, and DAPI. Scale bars: 100 μm. e The analysis of MGAT1 and membrane CD73 protein expression on TNBC (n = 146) using mIHC shows the positive correlation between MGAT1 with CD73. f Intensity of membrane CD73 was compared between MGAT1hi and MGAT1lo tumor regions. g Touching events between CD3⁺CD8⁺ T cells and PanCK⁺ tumor cells among DH relative to DL tumor regions. h, i UP-KW functional annotation (UniProt KeyWord Functional Annotations) analysis of post-translational modification (PTM) on the DEGs (different expressional genes) in PanCK⁺ epithelial tumor compartment between DL cases and DH cases (i), revealing selected Glycoprotein at increased levels in DH tumors (h). *p < 0.05. j, k GO Pathway analysis of DEGs in non-tumor areas between DL cases and DH cases, highlighting selected genes involving B cell receptor signaling and T cell activation at increased levels in DL cases (k). *p < 0.05. l The proposed working model. MGAT1, a glycosyltransferase, catalyzes CD73 for glycosylation at the Golgi body resulting in CD73 dimerization that enables CD73 plasma membrane translocation mediated by transport vesicles. Overactivation of MGAT1 due to aberrant THBS1 signaling leads to increased membrane-bound abundance of CD73 that enhances adenosine production and subsequently suppresses CD8⁺ T cell function. Pharmacological blockade of MGAT1 by an MGAT1 inhibitor (W-GTF01) reduces tumor growth by reinstating the capacity to elicit CD8⁺ effector T-cell responses through inhibition of CD73 glycosylation and membrane translocation. Data (means ± SEM), images, and flow cytometry are representative of at least three independent experiments. Statistical significance was determined using a two-tailed unpaired t test (b, c), two-tailed paired t test (f, g), or simple linear regression (e). Source data are provided as a Source Data file.