Hepatic metastatic niche: from normal to pre-metastatic and metastatic niche.

Liver is the organ responsible for hematopoiesis during fetal life, which is also a target organ of metastasis for several cancers. In order to recognize the hepatic metastatic changes, obtain a better grasp of cancer prevention, treatment, and inhibition mode of hepatic metastasis progression, we investigate the changes and transformation of normal hepatic niche cells to metastatic niche ones in this review. On the other hand, since metastatic diseases alter the liver function, the changes in a number of cancers that metastasize to the liver have also been reviewed. Relevant English-language literature was searched and retrieved from PubMed (1994-2014) using the following keywords: hepatic stem cell niche, hepatic metastatic niche, chemokine, and microRNAs (miRNAs). Also, over 86 published studies were investigated, and bioinformatics analysis of differentially expressed miRNAs in hepatic cancer and metastasis was performed. Metastasis is developed in several stages with specific changes and mechanisms in each stage. Recognition of these changes would lead to detection of new biomarkers and clinical targets involved in specific stages of liver metastasis. Investigation of the hepatic stem cell niche, development of metastasis in liver tissue, as well as changes in chemokines and miRNAs in metastatic hepatic niche can significantly contribute to faster detection of liver metastasis progression.