UBA3 promotes the occurrence and metastasis of intrahepatic cholangiocarcinoma through MAPK signaling pathway

Abstract

Intrahepatic cholangiocarcinoma (ICC) accounts for approximately 15% of primary liver cancers, and the incidence rate has been increasing in recent years. Surgical resection is the best treatment for ICC, but the 5-year survival rate is less than 30%. ICC signature genes are crucial for the early diagnosis of ICC, so it is especially important to identify signature genes. The aim of this study is to screen the signature genes of ICC and find the potential target for the treatment of ICC. We find that UBA3 is highly expressed in ICC, and knockdown of UBA3 inhibits ICC proliferation, invasion and migration. Mechanistic experiments show that UBA3 promotes ICC proliferation, invasion and migration by affecting ANXA2 through the MAPK signaling pathway. UBA3 is a target of bufalin, and bufalin targeting UBA3 inhibits ICC development and progression through the MAPK signaling pathway. In conclusion, our study shows that bufalin inhibits ICC by targeting UBA3, which has emerged as a new biomarker and potential therapeutic target for ICC.

1. Introduction

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer after hepatocellular carcinoma (HCC), and its incidence and mortality rates are increasing worldwide [1‒3]. ICC is a tumor of the bile ducts within the liver that arises primarily from the uncontrolled proliferation of transformed cholangiocytes [4,5]. ICC usually presents as an intrahepatic mass lesion, and no solid mass lesion is found on cross-sectional images [6]. ICC has no obvious clinical symptoms in the early stage, and most patients have lost the opportunity to undergo surgery when diagnosed, which is associated with a poor prognosis [7]. Therefore, more diagnostic tools for identifying early biomarkers are needed.

UBA3 has been implicated in various biological processes and diseases. For example, UBA3 is induced in differentiated preadipocytes and regulates adipogenesis and lipid droplet formation [8]. UBA3 also modulates oxidative phosphorylation and the tricarboxylic acid cycle in breast cancer cells by affecting the neddylation of mitochondrial proteins, and the activity of the PI3K/AKT signaling pathway is positively correlated with the expression of UBA3 [9]. Moreover, UBA3 expression is influenced by glucose level and epigenetic modifications, and UBA3 mediates the neddylation of PTEN, a tumor suppressor gene, in breast cancer [10,11]. In addition, UBA3 has been reported to be involved in liver cancer. A study showed that UBA3 deficiency caused fatty liver and hepatocyte damage in mice [8]. Another study revealed that UBA3 was overexpressed in hepatocellular carcinoma tissues and cell lines and that its knockdown inhibited cell proliferation and induced apoptosis [12].

UBA3 has also emerged as a potential drug target for cancer therapy. MLN4924 is a selective inhibitor of NAE that covalently binds to the cysteine residue of UBA3 and blocks its interaction with NEDD8 [13‒15]. MLN4924 has displayed preclinical anti-tumor activity in vitro and in vivo against various types of cancers, including leukemia, lymphoma, multiple myeloma, glioblastoma, ovarian cancer, pancreatic cancer, prostate cancer, and lung cancer. MLN4924 exerts its anti-cancer effects by disrupting neddylation-dependent processes such as proteasome function, DNA replication, the DNA damage response, cell cycle progression, apoptosis, autophagy, and signal transduction. MLN4924 has also shown promising clinical activity in patients with refractory hematologic malignancies. However, studies focused on the role of UBA3 in ICC are lacking.