CRTAM promotes antitumor immune response in triple negative breast cancer by enhancing CD8+ T cell infiltration

Abstract Background Immunomodulatory (IM) subtype triple negative breast cancer (TNBC) has high immune cell signaling, cytokine signaling gene expression, and is more responsive to immunotherapy. The mechanism responsible for this phenomenon is not clear, but the gene, the cytotoxic and regulatory T cell molecule (CRTAM), seems to be involved in this process. Methods A total of 360 TNBC patients diagnosed with TNBC without any treatment before surgery at Fudan University Shanghai Cancer Center (FUSCC) was analyzed and their primary tumor tissue subjected to RNA sequencing. Combined with three RNA-seq datasets obtained from GEO database, LASSO regression analysis was used to screen for IM type TNBC specific genes. Survival analysis were made by Kaplan-Meier method. GO, KEGG and GSEA analysis were used to explored the effect of CRTAM on the tumor immune response. RT-qPCR and western blot were used to assay the IFN response. Immunocompetent mice were injected in situ with mice triple negative breast cancer cells stably overexpressing CRTAM. Flow cytometry and IHC were used to determine tumor infiltrated immune cells of mice tumor model. Results In this study, we found that CRTAM expression was elevated in IM type TNBC and predicted favorable overall survival and recurrence-free survival in FUSCC and TCGA TNBC patients cohorts. GO and KEGG analysis suggested that CRTAM was highly associated with immune responses and immune system processes. Notably, CRTAM overexpression induced STAT1 phosphorylation and increased the expression of interferon-stimulated genes. We also found that CRTAM enhanced tumor-associated immune cell infiltration, especially CD8 + T cells, which may be related to the increased expression of MHC class I molecules caused by CRTAM overexpression. And it suggested that CRTAM had the potential to predict the efficacy of immunotherapy in TNBC. Conclusions In summary, these results suggest that CRTAM plays an important role in enhancing the immune inflammatory response and promoting CD8 + T cell infiltration in TNBC, which has the potential to be a new biomarker for predicting patients’ immune checkpoint inhibitor responses.