Caprin-1 promotes HepG2 cell proliferation, invasion and migration and is associated with poor prognosis in patients with liver cancer.

The present study aimed to investigate the role of caprin-1 in liver cancer and its association with the clinicopathological features and prognosis of liver cancer, as well as the underlying mechanism of caprin-1 function. Caprin-1 expression levels in a tissue microarray containing 40 liver cancer tissues, 10 peritumoral tissues and 20 normal liver tissues were analyzed using immunohistochemistry. The clinical data of 154 patients with liver cancer were also collected from The Cancer Genome Atlas database. Kaplan-Meier analysis and a Cox proportional hazards regression model were used to assess the association between caprin-1 expression levels and survival in patients with liver cancer. The effects of caprin-1 knockdown on the mRNA levels of cyclin D1 and cyclin D2 as well as the proliferation, invasion and migration of HepG2 cells were also investigated. The expression level of caprin-1 in liver cancer tissues was significantly higher compared with normal liver tissues or cells (P<0.01). High caprin-1 expression levels were associated with advanced clinical stage (P<0.001) and enhanced tumor invasion (P<0.001). Kaplan-Meier analysis showed that the overall survival time and disease-free survival time in patients with liver cancer with high caprin-1 expression were significantly shorter compared with patients with low caprin-1 expression levels (P=0.002 and P=0.033, respectively). The Cox proportional hazards regression model showed that high caprin-1 expression levels were an independent prognostic factor for liver cancer (P<0.001). Knockdown of caprin-1 in HepG2 cells significantly downregulated mRNA expression levels of cyclin D1 and cyclin D2, inhibited cell proliferation and invasion and the cells were arrested at G/G phase. In conclusion, caprin-1 may be a novel prognostic indicator for patients with liver cancer.