MST1R as a potential new target antigen of chimeric antigen receptor T cells to treat solid tumors.

Although chimeric antigen receptor T cell (CAR-T) is a promising immunotherapy in hematological malignancies, there remain many obstacles to CAR-T cell therapy for solid tumors. Identifying appropriate tumor-associated antigens (TAAs) is especially critical for success. Using a bioinformatics approach, we identified common potential TAAs for CAR-T cell immunotherapy in solid tumors. We used the GEO database as a training dataset to find differentially expressed genes (DEGs) and verified candidates using the TCGA database, obtaining seven common DEGs (HM13, SDC1, MST1R, HMMR, MIF, CD24, and PDIA4). Then, we used MERAV to analyze the expression of six genes in normal tissues to determine the ideal target genes. Finally, we analyzed tumor microenvironment factors. The results of major microenvironment factor analyses showed that MDSCs, CXCL1, CXCL12, CXCL5, CCL2, CCL5, TGF-β, CTLA-4, and IFN-γ were significantly overexpressed in breast cancer. The expression of MST1R was positively correlated with TGF-β, CTLA-4, and IFN-γ. In lung adenocarcinoma, MDSCs, Tregs, CXCL12, CXCL5, CCL2, PD-L1, CTLA-4, and IFN-γ were significantly overexpressed in tumor tissues. The expression of MST1R was positively correlated with TGF-β, CTLA-4, and IFN-γ. In bladder cancer, CXCL12, CCL2, and CXCL5 were significantly overexpressed in tumor tissues. MST1R expression was positively correlated with TGF-β. Our results demonstrate that MST1R has the potential as a new target antigen for treating breast cancer, lung adenocarcinoma, and bladder cancer and may be used as a progression indicator for bladder cancer.