Caveolin-1 overexpression is associated with hepatocellular carcinoma tumourigenesis and metastasis

Caveolin-1 (Cav1) has been implicated in diverse human cancers, yet its role in hepatocellular carcinoma (HCC) tumourigenesis and metastasis remains elusive. In the current study, we aim to provide a comprehensive understanding regarding the functional role of Cav1 in HCC tumourigenesis and metastasis. Cav1 expression was examined in a panel of human HCC cell lines using western blotting analysis and quantitative RT-PCR and human tissues by immunohistochemistry. Cav1 was not detected in normal liver cell line and all non-tumourous liver tissues but exclusively expressed in HCC cell lines and tissues. Dramatic expression of Cav1 was found in metastatic HCC cell lines and tumours, indicating a progressive increase of Cav1 expression along disease progression. Cav1 overexpression was significantly correlated with venous invasion (p = 0.036). To investigate the functions of Cav1 in HCC, Cav1 overexpressing and knockdown stable clones were established in HCC cells and their tumourigenicity and metastatic potential were examined. Overexpression of Cav1 promoted HCC cell growth, motility, and invasiveness, as well as tumourigenicity in vivo. Conversely, knockdown of Cav1 in metastatic HCC cells inhibited the motility and invasiveness and markedly suppressed the tumour growth and metastatic potential in vivo. Collectively, our findings have shown the exclusive expression of Cav1 in HCC cell lines and clinical samples and revealed an up-regulation of Cav1 along HCC progression. The definitive role of Cav1 in promoting HCC tumourigenesis was demonstrated, and we have shown for the first time in a mouse model that Cav1 promotes HCC metastasis.