As a target of hsa-miR-214-3p, this miRNA inhibits breast cancer cell proliferation through the regulation of B7H3 expression, restores the activity and proliferation of CD8+ T cells and natural killer (NK) cells, and promotes the production of immune factors such as IL-2, IL-4, and IFN-γ, thereby mitigating breast cancer development. The gene discussed is CD276; the disease is breast carcinoma.