Low cytoplasmic casein kinase 1 epsilon expression predicts poor prognosis in patients with hepatocellular carcinoma

Casein kinase 1 epsilon (CK1ε) is a member of the casein kinase 1 (CK1) family, which comprises highly conserved and ubiquitous serine/threonine protein kinases. Recent studies have demonstrated that CK1ε plays a role in human cancers; however, the role of CK1ε in hepatocellular carcinoma (HCC) remains unclear. The study used immunohistochemistry to examine CK1ε expression in 230 HCC specimens by tissue microarray (TMA) and assessed the effect of CK1ε knockdown on migration of human hepatoma cells in vitro. The immunohistochemical analyses showed that low CK1ε expression was significantly correlated with tumor differentiation (p = 0.008), T classification (p = 0.016), tumor vascular invasion (p = 0.002), and cancer stage (p = 0.010). The univariate and multivariate analyses showed that patients with low CK1ε expression had a considerably lower OS rate than that of the patients with high CK1ε expression (p = 0.041, hazard ratio = 1.4; p = 0.039, hazard ratio = 1.4). Moreover, CK1ε small interfering RNA (siRNA) treatment exerted an invasion-promoting effect in human hepatoma cells. In conclusion, our data indicated that low CK1ε expression is correlated with a low survival rate and CK1ε may play a role as a tumor suppressor in hepatocarcinogenesis.