Expression of STK15 mRNA in hepatocellular carcinoma and its prognostic significance

To investigate whether the STK15 mRNA expression correlates with clinicopathologic features and the prognosis of HCC patients.

Three hepatoma cell lines, two normal liver epithelial cell lines, hepatoma tissues, adjacent tumor tissues and normal liver tissues were obtained from 46 HCC patients. Semi-quantitative RT-PCR assays were performed to detect the expression of STK15 mRNA in above cell lines and tissues. Moreover, the expression of STK15 protein in hepatoma tissues, adjacent tumor tissues and normal liver tissues was also examined by immunohistochemical staining. Finally, correlations between STK15 mRNA expression and the clinicopathological features and prognosis of HCC patients were evaluated.

STK15 mRNA showed higher levels in hepatoma cell lines than in normal liver epithelial cell lines. Moreover, the mean levels of STK15 mRNA and protein expression showed statistical difference between tumor tissues, tumor adjacent tissues and normal liver tissues (P<0.01). By immunohistochemical analysis, we found that paraffin-embedded archival HCC tissues showed higher expression of STK15 than adjacent tumors and normal liver tissues. Furthermore, HCC patients with higher STK15 mRNA expression showed poorer prognosis than those with lower STK15 mRNA expression. The high level of STK15 mRNA expression was significantly correlated with tumor stage (P=0.0081), more frequent lymph node (P=0.0380) or hematogenous metastasis (P=0.0066), and a higher incidence of cancer-related death (P=0.0083). Furthermore, the disease-free survival (DFS) and overall survival (OS) rates of HCC patients with higher STK15 mRNA expression group (47.6% and 52.7%) were significantly lower than those of patients with low STK15 mRNA expression group (56.9% and 68.8%, P=0.0018 and 0.0047).

STK15 mRNA might be a good marker for predicting the prognosis of HCC patients.