To our best knowledge, this is the first report of circulating miRNA profile of CTEPH. The results of this study provided us some clue and candidate for further pathogenesis investigation and clinical biomarker screening of this miscellaneous disease. Colorectal cancer is a major health concern worldwide. Although substantial progress has been made in the past decade, the challenges of treating CRC and its metastases remain formidable. Currently, despite the use of specific active drugs for the treatment of metastatic CRC becoming more popular, cure rates are low and the underlying molecular mechanisms for the organ-oriented metastasis of CRC are not fully understood. Chemokines are 8- to 12-kDa peptides that function as chemoattractant cytokines and exert their biological effects by interacting with G protein-linked transmembrane chemokine receptors. A number of chemokines and their corresponding receptors are known to play an important role in leukocyte trafficking and homing, especially at sites of inflammation, tissue damage and malignant cell migration. Interestingly, while most chemokine receptors bind to multiple chemokines, the chemokine receptor CCR6 has only one chemokine ligand, CCL20. CCR6 is primarily expressed on leukocytes, with expression in mature lymphocytes, especially in memory cells, immature dendritic cells of particular lineages and migrating regulatory T cells. In most cases, CCR6 is absent from granulocytes, monocytic cells, immature lymphocytes, and mature DCs. CCL20 shows both constitutive and inducible expression, mainly in mucosaassociated lymphoid tissues and the liver, and the basal expression rate is increased under inflammatory conditions. The basal expression level of CCL20 is thought to regulate the migration of CCR6-expressing immature DCs and memory lymphocytes from the blood for homeostatic surveillance. The upregulation of CCL20 during inflammation may enhance the migration of both of these cell types into the tissue. For human cancers, accumulated data imply an association between the chemokine-chemokine receptor system and the metastatic potential of cancer cells. For example, tumor cells from at least 23 different types of human LEE011 cancers of epithelial, mesenchymal and hematopoietic origin express CXCR4. CCR7 was also found in breast, gastric, and esophageal squamous cancer, and its expression was correlated with poor prognosis. All these studies show that the expression of chemokine receptors in cancer metastasis is not random. The chemokine receptor CCR6 is of particular interest in the liver metastasis of colorectal cancer. Its unique chemokine ligand CCL20 is predominantly expressed in lymphatic tissue and in the liver. The aberrant expression of the chemokine receptor CCR6 on CRC cells is reportedly involved in organ-selective tumor metastasis. However, the direct in vivo evidence supporting a role for CCR6 in the metastasis of CRC is lacking. In the present study we found that upregulated CCR6 expression in metastatic CRC cell lines predicted poor survival for CRC patients. The overexpression of CCR6 was sufficient to promote CRC cell metastasis both in vitro and in vivo.