Clinical Implications of Upregulated RSAD2 Gene Expression in Hepatocellular Carcinoma.

Background:JAK/STAT interferon signaling interacts with the PI3K/AKT/mTOR pathway to drive hepatocellular carcinoma (HCC) progression and metastasis. RSAD2, an interferon-inducible gene, is upregulated by the PI3K/AKT/mTOR pathway and serves as a key factor for metabolic reprogramming to promote stem-like properties of cancer stem cells and tumor proliferation. In patients with resected HCC, RSAD2 upregulation showed an association with microvascular invasion, which is a proven risk factor for developing HCC metastasis. This clinical observation was compatible with preclinical findings. On the other hand, RSAD2 upregulation has been reported to confer poor prognosis in breast and gastric cancers. However, further clinical study of RSAD2 in HCC is lacking. As a result, we investigated the clinical implications of RSAD2 gene expression in HCC patients, in terms of its associations with survival, the presence of extra-hepatic metastasis, and other clinical manifestations. Methods: We studied 309 treatment-naïve HCC patients, as well as data from the TCGA and GTEx databases. Results:RSAD2 gene expression was differentially upregulated in HCC tumors when compared to normal liver tissues (p < 0.01). Elevated RSAD2 mRNA levels in the blood and the presence of extra-hepatic metastasis were independent prognostic factors for poor overall survival (OS) (p < 0.01). The median OS of patients with high RSAD2 expression vs. low expression were 5.4 vs. 14.2 months, respectively (p < 0.01). A high RSAD2 mRNA level was significantly correlated with the presence of extra-hepatic metastasis, nutritional disturbance, and functional impairment after controlling for confounding clinical factors (p < 0.05). Conclusions: High RSAD2 gene expression is associated with poorer OS, the presence of extra-hepatic metastasis, and quality-of-life disturbances in HCC patients.