Gene signatures associated with brain-topical proliferative activity in breast cancer

Breast cancer is a type of cancer with relatively good prognosis; however, once it metastasizes to the brain, it deteriorates clinical outcomes. Previously, we compared the brain-topical proliferative activity of multiple breast cancer cell lines by intracranial injection and identified UACC-893 cells as highly proliferative in the brain. In this study, we performed RNA-seq analysis of brains harboring UACC-893 tumors and explored the genes characteristically expressed in tumor cells colonizing the brain and in their surrounding brain tissue. Enrichment analysis suggested that immune-related signals may be involved in the brain-topical proliferative activity of tumor cells. In addition, ligand-coding genes were extracted among those characteristically expressed in the intracranial tumor or in the brain containing it. This result was validated by quantitative real-time PCR analysis. NicheNet analysis using RNA-seq data suggested the interaction between tumor cells and the brain microenvironment, which suggested possible communications via the ligand-receptor axis. In summary, this study highlights the genes and signals characteristic of highly proliferative tumor cells and the affected brain tissue influencing tumor colonization.