Cancer cells modulate the recruitment and function of inflammatory cells to create an immunosuppressive microenvironment that favors tumor growth and metastasis. However, the tumor-derived regulatory programs that promote intratumoral immunosuppression remain poorly defined. Here, we show in a KrasLA1/+p53R172HΔg/+-based mouse model that bone morphogenetic protein-4 (BMP4) augments the expression of the T cell co-inhibitory receptor ligand PD-L1 in the mesenchymal subset of lung cancer cells, leading to profound CD8+ T cell-mediated immunosuppression, producing tumor growth and metastasis. We previously reported in this model that BMP4 functions as a pro-tumorigenic factor regulated by miR-200 via GATA4/6. Thus, BMP4-mediated immunosuppression is part of a larger miR-200-directed gene expression program in tumors that promotes tumor progression, which could have important implications for cancer treatment.
Keywords: BMP4; EMT; PD-L1; immunotherapy; lung cancer; miR-200.