OTUB1 Promotes Stem-like Properties in Bladder Cancer by Stabilising SLC7A11 and Suppressing Ferroptosis through Deubiquitination.

BACKGROUND

Cancer stem cells (CSCs) contribute to bladder cancer (BCa) progression and treatment resistance. Ferroptosis, an iron-dependent cell death, influences CSC maintenance, but its post-translational regulation remains unclear. This study investigated how the deubiquitinase OTUB1 regulated ferroptosis and CSC-like traits in BCa through interaction with SLC7A11.

METHODS

OTUB1 expression was assessed in clinical BCa tissue pairs (tumour vs adjacent normal) collected from patients undergoing surgical resection and in cell lines. Gain- and loss-of-function models were established in BCa cells. Cell viability, stemness capacity and ferroptosis markers were evaluated using Cell Counting Kit-8 (CCK-8) assay, Western blot, sphere formation assay, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence, reactive oxygen species (ROS) detection, enzyme-linked immunosorbent assay (ELISA) and co-immunoprecipitation.

RESULTS

OTUB1 was significantly upregulated in BCa cells and tissues relative to normal controls (p < 0.01). OTUB1 overexpression significantly enhanced BCa cell viability, self-renewal capacity and stemness marker expression but reduced ferroptosisassociated indicators (ROS, malondialdehyde (MDA) and ferrous iron (Fe2+)) (p < 0.01). Conversely, OTUB1 knockdown impaired stem-like traits (p < 0.01) and triggered ferroptosis (p < 0.01). Mechanistically, OTUB1 directly interacted with SLC7A11, decreased its ubiquitination and stabilised its protein expression (p < 0.01). Notably, ectopic SLC7A11 expression rescued the impaired stemness and ferroptosis induction caused by OTUB1 knockdown (p < 0.01).

CONCLUSIONS

OTUB1 inhibits ferroptosis and sustains CSC-like features in BCa by deubiquitinating and stabilising SLC7A11. The OTUB1-SLC7A11 axis represents a novel regulatory mechanism of CSC maintenance and may serve as an intervention point in BCa.