KNTC1 initiates a KNTC1/E2F8/MYC positive feedback loop to facilitate tumorigenesis and enhance chemoresistance in bladder cancer.

BACKGROUND: Bladder cancer (BLCA) is a lethal malignancy frequently challenged by chemoresistance and limited therapeutic options. Kinetochore-associated 1 (KNTC1) has been implicated in cancer, yet its precise role, regulatory mechanism, and therapeutic potential in BLCA remain largely unexplored. METHODS: We analyzed KNTC1 expression and its clinical relevance using public databases (TCGA, GEO) and clinical specimens. Functional roles of KNTC1 in proliferation, invasion, metastasis, and gemcitabine resistance were assessed through in vitro and in vivo experiments (CCK-8, transwell, xenograft models). Mechanistic insights were gained via RNA-seq, co-immunoprecipitation, chromatin immunoprecipitation (ChIP), and luciferase reporter assays. A poly (ß-amino ester) (PAE)-based nanoparticle was synthesized for targeted in vivo delivery of KNTC1 siRNA. RESULTS: KNTC1 was significantly upregulated in BLCA tissues, and its high expression correlated with poor patient prognosis. Functionally, KNTC1 promoted BLCA cell proliferation, invasion, metastasis, and gemcitabine resistance. Mechanistically, KNTC1 bound to the transcription factor E2F8 and facilitated its nuclear translocation, thereby enhancing E2F8-mediated transcriptional activation of MYC. MYC, in turn, transcriptionally upregulated KNTC1, forming a positive feedback loop that drove hyperactivation of the oncogenic PI3K/AKT/mTOR pathway. Silencing KNTC1, especially in combination with a MYC inhibitor (10058-F4), overcame gemcitabine resistance in vitro and in vivo. Therapeutic delivery of KNTC1 siRNA via a novel PAE nanocarrier (PAE@shKNTC1) significantly suppressed lung metastasis in a preclinical model. CONCLUSION: Our study identifies a novel KNTC1/E2F8/MYC positive feedback axis that drives BLCA tumorigenesis and chemoresistance. KNTC1 serves as both a prognostic biomarker and a promising therapeutic target, with targeted inhibition offering a potential novel strategy for BLCA treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13046-026-03651-4.