FIGURE 2 from Epithelial Expressed B7-H4 Drives Differential Immunotherapy Response in Murine and Human Breast Cancer

B7-H4 (VTCN1) is highly correlated with epithelial gene markers in mouse and human cells unlike other checkpoint ligands. A, In human breast cancer cell lines (CCLE), B7-H4 is the only checkpoint ligand positively correlated with epithelial markers and negatively correlated with mesenchymal markers. Data shown are Spearman correlations between genes. Significant correlations (P < 0.05) are indicated by asterisk. B, Genes downregulated during EMT are positively correlated with VTCN1 in human cell lines (CCLE). C, Murine cancer cell lines express B7-H4. D, B7-H4 is only expressed on epithelial EpCAM⁺ cells in murine and human cells. E, The MMTV-neu cell line with highest B7-H4 levels is comprised of phenotypically epithelial-like (abbreviated E) and mesenchymal-like (M) cells. F, In MMTV-neu cells, the CD44⁺ M cells do not express B7-H4 but all the EpCAM⁺ E cells do. G, MMTV-neu E and M cells express hallmark markers. H, Single-cell RNA sequencing of the heterogenous MMTV-neu cells confirms Vtcn1 is solely expressed in the epithelial cell population. I, A cohort of human tumors including both TNBC and ER⁺HER2⁻ were stained for B7-H4, EpCAM, and CD44 by mIF. Data shown are log₂ of % B7-H4⁺ tumor cells and include 132 samples with >1% B7-H4 expression (paired t test of transformed data).