USP13 promotes colorectal cancer progression by deubiquitinating and stabilizing HIF-1α.

BACKGROUND: Hypoxia-inducible factor-1α (HIF-1α) is a key transcriptional regulator in tumor progression, tightly controlled by ubiquitination-mediated proteasomal degradation. While multiple deubiquitinases (DUBs) stabilize HIF-1α, the role of ubiquitin specific peptidase 13 (USP13) in colorectal cancer (CRC) remained undefined. This study aimed to elucidate whether USP13 regulates HIF-1α stability and contributes to CRC pathogenesis. METHODS: USP13-HIF-1α interaction was assessed via co-immunoprecipitation (co-IP), immunofluorescence, and domain mapping. Ubiquitination assays evaluated USP13-mediated HIF-1α deubiquitination using K-specific ubiquitin mutants. Functional impacts were tested in CRC cell lines using CRISPR/Cas9-mediated USP13 knockout and overexpression. In vitro assays included proliferation (CCK-8), colony formation, migration, invasion, and angiogenesis (HUVECs tube formation). In vivo relevance was validated in xenograft models, USP13-knockout mice, and an AOM/DSS-induced CRC model. Clinical correlation used IHC staining of CRC patient tissues and TCGA data analysis. RESULTS: USP13 directly bound HIF-1α via its C-terminal UBA domain, cleaving K48-linked polyubiquitin chains to stabilize HIF-1α and enhance its transcriptional activity. USP13 knockout reduced HIF-1α levels, suppressed CRC cell proliferation, migration, invasion, and angiogenesis in vitro, and attenuated tumor growth in xenografts. Conversely, USP13 overexpression exacerbated these effects. Clinically, USP13 and HIF-1α levels correlated positively in CRC tissues and with Ki-67 expression. USP13 deficiency in mice reduced tumor burden in AOM/DSS models, decreased vascular density (CD31+), and downregulated VEGFA/Ki-67. Rescue experiments confirmed HIF-1α dependency for USP13-mediated oncogenic effects. CONCLUSIONS: USP13 promotes CRC progression by deubiquitinating and stabilizing HIF-1α, driving tumor growth, metastasis, and angiogenesis. This identifies USP13 as a pro-tumorigenic factor and potential therapeutic target in CRC.