A subcutaneous xenograft tumor model in immunocompetent mice confirmed that miR-148a-3p overexpression inhibited PD-L1 expression, thereby regulating the proportion of CD4+ T cells, CD8+ T cells, and Tregs in the PC immune microenvironment, as well as the apoptosis, function, and exhaustion of CD8+ T cell. The gene discussed is CD274; the disease is neoplasm.