Knockdown of PLK1 suppresses malignant phenotypes and tumor growth in bladder cancer via activating Hippo pathway

Bladder cancer (BLCA) is a prevalent urological malignancy. We aim to identify novel biomarkers for BLCA and elucidate the specific regulatory mechanisms of polo-like kinase 1 (PLK1). Using differentially expressed genes (DEGs) screened from GSE38264 and GSE130598 datasets, we constructed protein-protein interaction networks to identify hub genes, whose expression was validated using reverse transcription-quantitative polymerase chain reaction. The malignant phenotype of BLCA cells was assessed by Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, Transwell, and wound-healing assays. Hematoxylin-eosin and immunohistochemical staining were employed to evaluate BLCA development in mouse xenograft models. The protein expression was detected by Western blot. PLK1, AURKA, AURKB, CDK1, ERBB2, ERBB3, FGFR1, FYN, ABL1, and PRKDC were hub genes with predictive value for BLCA. Among them, PLK1 was selected as a key target of BLCA. PLK1 knockdown inhibited the viability, proliferation, migration, and invasion of BLCA cells. In vivo, PLK1 knockdown inhibited tumor growth. Silencing PLK1 activated the Hippo pathway in BLCA cells and tumor tissues. The Hippo pathway inhibitor reversed the inhibitory effects of PLK1 silencing on malignant phenotype of BLCA cells. PLK1 knockdown exerts an inhibitory effect on BLCA via activating the Hippo pathway, which presents promising therapeutic strategies for BLCA.