The differentially expressed genes identified in oncospheres derived from CRC108 and its metastatic variants.

Migrating cancer stem cells (MCSCs) are believed to be tumorigenic initiators of metastasis. However, the relevance of MCSCs for organ-specific metastasis in colorectal cancer remains unclear. Using in vivo selection, transcriptomic analysis and functional verification, we cultured colorectal cancer stem cells and discovered specific cell surface markers of MCSCs exhibiting distinct abilities to metastasize to the liver and lung. These results have important clinical implications as selection criterion for post-operative adjuvant therapy. The human primary colorectal cancer cells from colorectal cancer patient (CRC108) were orthotopically injected into NOG mice. The cancer cells in the liver or lung metastases were orthotopically injected into a new set of mice. After six selection cycles, we obtained cancer cells that produce spontaneous liver (CRC108LM) or lung metastases (CRC108PM). Under serum-free conditions, all individual cells produced nonadherent, multicellular oncospheres. Total RNA extracted from oncospheres of organ-specific metastasizing variants and their parental cells was used to generate biotinylated complementary RNA (cRNA) by following the standard Agilent GeneChip protocol.