The Deubiquitinase OTUD3 Stabilizes ACTN4 to Activate NF-κB Signaling Pathway in Hepatocellular Carcinoma

Abstract

Background: OTUD3, a deubiquitinating enzyme, has emerged as important role in some cancer. It showed that OTUD3 plays suppressive role in breast cancer whereas oncogenic role in lung cancer. However, the function and mechanism of OTUD3 in hepatocellular carcinoma (HCC) progression remain elusive. Methods: Gene and protein expression of OTUD3 in HCC tissues were determined by qRT-PCR, western blot and immunohistochemistry. A series of gain- and loss-of-function assays were used to investigated the role of OTUD3 in HCC cells progression. Moreover, mass spectroscopic analysis and RNA-seq were used to identify the downstream targets of OTUD3 in HCC cells. The interaction between OTUD3 and ACTN4 was examined through co-IP experiment and in vitro ubiquitination assay.Results: In our research, OTUD3 was significantly overexpressed in HCC tissues and higher OTUD3 expression was correlated with bigger tumor size, more distant metastasis, and worse TNM stage. Additionally, OTUD3 promoted HCC cells growth and metastasis in vitro and in vivo. Furthermore, ACTN4 was identified as a downstream target of OTUD3 and ACTN4 protein level was significantly related to OTUD3 expression. Rescue experiments indicated that ACTN4 was essential for OTUD3-mediated HCC proliferation and metastasis in vitro and in vivo. Moreover, we identified that NF-κB signaling pathway was activated by OTUD3 through ACTN4 to promote HCC cells progression. Importantly, OTUD3 protein level was correlated with ACTN4 protein level and activity of NF-κB signaling pathway in HCC tissues. Conclusion: Our findings identify the oncogenic role of OTUD3 in HCC and suggest that OTUD3 can be considered as a pivotal prognostic biomarker and a potential therapeutic target.