Noval ceRNA axis-mediated high expression of TOP2A correlates with poor prognosis and tumor immune infiltration of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is a highly malignant tumor with limited treatment options, suboptimal efficacy, and poor prognosis, resulting in an economic burden to countries worldwide. TOP2A is a mammalian protein that plays a vital role in DNA replication. Previous studies have shown that upregulation of TOP2A expression is associated with tumorigenesis and progression in various cancers, but the exact mechanism of upregulation remains unclear.Methods: We first conducted a pan-cancer analysis using The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases to study the oncogenicity of TOP2A through the cBioPortal database. Next, using The Encyclopedia of RNA Interactomes (ENCORI) database, we identified microRNAs (miRNAs) that are associated with the downregulation of TOP2A and investigated potential long non-coding RNAs (lncRNAs) that may act as competing endogenous RNAs (ceRNAs) by binding to candidate miRNAs. We then analyzed immune cell infiltration and immune checkpoints using the TIMER database. Finally, we performed a multivariate regression analysis using lncRNAs and clinical pathological characteristics, constructed a nomogram to predict the prognosis of HCC based on the analysis results, and evaluated its diagnostic efficiency.Results: TOP2A was highly expressed in HCC and was associated with poor patient prognosis. TOP2A was subject to post-transcriptional regulation in HCC, with the ceRNA mechanism being a significant pathway. miR-139-5p was an important miRNA that suppressed the upregulation of TOP2A in HCC, and patients with low expression of miR-139-5p had worse overall survival (OS). After screening and analysis, three lncRNAs, AC078846.1, AC124798.1 and SNHG3, were found to inhibit the activity of miR-139-5p through the ceRNA mechanism, and patients with high expression of these three lncRNAs had worse prognosis. In addition, TOP2A was found to be closely related to tumor-infiltrating immune cells (TIICs) and immune checkpoints. A nomogram constructed using the three lncRNAs and selected clinicopathological features showed good predictive value for the prognosis of liver cancer.Conclusions: The TOP2A-miR-139-5p-AC078846.1/AC124798.1/SNHG3 axis plays a significant role in the progression of HCC and leads to poor patient outcomes. Additionally, TOP2A influences the development of HCC by affecting TIICs and immune checkpoints. A nomogram constructed using the three lncRNAs and clinicopathological features has good clinical utility.