Our transcriptome-based analysis revealed three key findings: (1) PLK1 overexpression correlates with advanced clinicopathological stages (T/N/M) and poor survival outcomes; (2) PLK1 co-expressed genes are enriched in cell cycle regulation networks; (3) high PLK1 expression is associated with an immunosuppressive tumor microenvironment characterized by Treg infiltration and CD8+ T cell exclusion. This evidence concerns the gene CD8A and neoplasm.