OTUD7B Activates the Caspase-8-RIPK1-NEMO Complex-Regulated NF-κB Pathway to Promote Triple-Negative Breast Cancer Metastasis.

Abstract

Background: Metastatic dissemination of triple-negative breast cancer (TNBC) to distant organs, such as the lungs and brain, poses a significant threat to patient survival. Nevertheless, the molecular basis driving TNBC metastasis remains largely elusive. In the present study, we elucidated the role and underlying mechanism of OTU deubiquitinase 7B (OTUD7B) in promoting TNBC metastasis. Methods: The Cancer Genome Atlas (TCGA)/K-M Plotter databases were used for determining the prognostic significance of OTUD7B in TNBC patients. Cell migration and lung colony-forming assays were performed to evaluate the metastatic potential of TNBC cells. A cycloheximide-chase assay was employed to examine the effect of OTUD7B on Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) Essential Modulator (NEMO) protein degradation in TNBC cells. Flow-cytometric analyses were performed to examine OTUD7B effects on TNBC necroptosis. Results: OTUD7B is significantly (p < 0.001) upregulated in TNBC and correlates with poor distant metastasis-free survival (log-rank p < 0.001, n = 424). Its knockdown suppresses, whereas overexpression enhances, the metastatic potential of TNBC cells in vitro and in vivo, dependent on its deubiquitinating activity. Mechanistically, OTUD7B regulates the ubiquitination of Caspase-8 and NEMO, thereby modulating NF-κB signaling through the Caspase-8-RIPK1-NEMO axis. OTUD7B depletion increases Caspase-8 activity by approximately three-fold, promotes NEMO degradation, suppresses NF-κB activation, and induces necroptosis. Conversely, OTUD7B overexpression exerts opposite effects. Pharmacological inhibition of NEMO or NF-κB attenuates OTUD7B-driven cell migration by 40-90%. Conclusions: The deubiquitinating activity of OTUD7B promotes TNBC metastasis by stabilizing the Caspase-8-RIPK1-NEMO axis, thereby activating the NF-κB signaling pathway. These results further suggest that targeting OTUD7B activity may be a promising therapeutic strategy for metastatic TNBC.