Tumor microenviroment and hepatocellular carcinoma metastasis.

The cross talk between tumor cells and the surrounding peritumoral stroma has been extensively studied as a dynamic system involving the processes of hepatocarcinogenesis, tumor invasion, and metastasis in recent few decades. Besides hepatocytes, liver tumor microenvironments are generally classified into cellular and noncellular components, including hepatic stellate cells, fibroblasts, immune, endothelial, mesenchymal stem cells, together with growth factors, cytokines, extracellular matrix, hormone as well as viruses et al. The noncellular components manipulate hepatocellular carcinoma invasion and metastasis by facilitating epithelial-mesenchymal transition, increasing proteolytic activity of matrix metalloproteinases, and regulating antitumor immunity, etc. Because the main cause of death in hepatocellular carcinoma patients is tumor progression with metastasis, a better understanding of the interplay between hepatocytes and their environment during tumor metastasis may be helpful for the discovery of novel molecular targets.