The APC/C E3 ligase subunit ANAPC11 mediates FOXO3 protein degradation to promote cell proliferation and lymph node metastasis of urothelial bladder cancer

Abstract Urothelial bladder cancer (UBC) is one of the most prevalent malignancies worldwide with striking tumor heterogeneity. Elucidating the molecular mechanism for the treatment of aggressive UBC is particularly relevant. Protein ubiquitination is critical constitution of post-translational modification (PTM) that mediates the degradation of target protein through proteasome. However, the roles of aberrant protein ubiquitination in UBC development and the underlying mechanism in driving tumor progression remain unclear. In this study, taking the advantage of CRISPR/Cas9 technology, we identified ubiquitin E3 ligase ANAPC11, a critical subunit of anaphase-promoting complex/cyclosome (APC/C), as a potential oncogenic molecule in UBC cells. Our clinical analysis showed that the elevated expression of ANAPC11 was significantly correlated with high T stage, positive lymph node metastasis and poor outcomes of UBC patients. By employing a series of in vitro experiments, we demonstrated that ANAPC11 boosted the proliferation and invasiveness of UBC cells, while knockout of ANAPC11 inhibited the growth and lymph node metastasis of UBC cells in vivo. By conducting immunoprecipitation coupled to mass spectrometry assays, we confirmed that ANAPC11 increased the ubiquitination level of Forkhead transcription factor FOXO3. As a result, the decrease of FOXO3 protein stability led to the down-regulation of the cell cycle regulator p21 and the abrogation of GULP1, a downstream effector of androgen receptor signaling. Taken together, ANAPC11 showed oncogenic functions in UBC by modulating the FOXO3 protein degradation. ANAPC11-FOXO3 regulatory axis might serve as a novel therapeutic target for UBC.