Isolation and Phenotypic Characterization of Colorectal Cancer Stem Cells With Organ-Specific Metastatic Potential

Abstract

Migrating cancer stem cells (MCSCs) are believed to form metastases. We sought to identify markers of MCSCs from human colorectal cancers (CRCs) and determine their roles in organ-specific metastasis. To identify colorectal MCSCs that contribute to organ-specific metastasis, we developed a model of liver or lung metastasis using primary tumor cells from patients with CRC who had liver and lung metastases. Distinct organ-specific metastatic cells were isolated by 6 cycles of selecting for cells that formed liver and lung tumors after subcutaneous injection into mice. Microarray analysis was used to identify markers of the organ-specific MCSCs. We then measured levels of these markers in CRC cell lines and 128 CRC samples. We characterized the functional roles of these markers in organ-specific metastasis. We identified CD110 and CDCP1 as cell surface markers of MCSCs from human colorectal tumors that metastasized to liver and lung. We observed a distinct pattern of CD110 and CDCP1 in a panel of primary colorectal tumor samples and their matched liver or pulmonary metastases, indicating that these proteins might serve as biomarkers of organ-specific metastasis. Functional studies showed that thrombopoietin attracts CD110(+) CSCs and increases their self-renewal to promote formation of liver metastases. CDCP1 promoted adhesion of CRC cells to the lung endothelium. We isolated MCSCs from primary human CRCs and found that the CD110(+) and CDCP1(+) subpopulations mediate organ-specific metastasis. These findings might be used to aid in selection of patients for postoperative adjuvant therapy.