Knockdown of ZBTB11 impedes R‐loop elimination and increases the sensitivity to cisplatin by inhibiting DDX1 transcription in bladder cancer

INTRODUCTION: Bladder cancer (BC) is one of the most common malignant cancers, with poor prognosis and high incidence. Cisplatin is the standard chemotherapy for muscle invasive bladder cancer; however, chemotherapy resistance remains a major challenge. Moreover, oncogenic signalling and the specific mechanisms underlying cisplatin resistance in BC remain largely unclear METHODS: In this study, RT‐PCR, Western blot, immunofluorescence, and immunohistochemistry were used to measure gene and protein expression. Colony formation assay and flow cytometry were performed to evaluate the proliferation of BC cells. Gene set enrichment analysis was performed to identify the function in which ZBTB11 was involved. Luciferase and chromatin immunoprecipitation experiments were performed to determine the transcriptional regulation mechanism of ZBTB11. The effects of ZBTB11 on the malignant phenotypes of BC cells were examined in vitro and in vivo RESULTS: The results showed that ZBTB11 was remarkably upregulated in BC tissues, which was associated with poor prognosis in patients with BC. Furthermore, we found that knockdown of ZBTB11 remarkably inhibited the proliferation and tumorigenesis of BC cells by inducing apoptosis. Mechanistically, the knockdown of ZBTB11 transcriptionally inhibited DDX1 to suppress R‐loop clearance, resulting in DNA damage in BC cells. Importantly, the ZBTB11/DDX1 axis is required for the chemotherapy resistance of BC cells to cisplatin CONCLUSION: Our findings not only reveal an underlying mechanism by which the ZBTB11/DDX1 axis promotes the tumorigenesis of BC but also provide a potential target for a combination strategy of cisplatin‐based chemotherapy for BC.