Enrichment of ornithine decarboxylase degron transduced colorectal cancer cells for extended application of cancer stem cell models [colorectal cancer]

Cancer stem cells (CSCs) are present in small quantities in tumor populations. To permit various analyses of CSCs, we attempted to enrich and expand ornithine decarboxylase (ODC) degron-transduced colorectal cancer (CRC) cells, which retain low proteasome activity. ZsGreen fluorescence-positive (ZsGreen+) cells were collected by sorting the ODC degron-transduced HCT116, DLD1, and SW480 cells, which were defined as enriched ZsGreen+ cells. ZsGreen+ cells still maintained CSC properties. These cells had higher stem cell marker expression and increased resistance to chemotherapy with 5-fluorouracil and oxaliplatin. ZsGreen+ HCT116 and DLD1 cells had greater sphere-forming ability and enhanced tumorigenicity compared to ZsGreen- control cells. Time-lapse microscopy showed that a single enriched ZsGreen+ HCT116 cell had asymmetric cell division. Thus, model CSCs were acquired in sufficient quantity. Using these cells, we performed a comprehensive microRNA analysis; miR- 491-3p was a candidate to suppress cancer stemness. Finally, we found that up- regulated genes in the enriched HCT116 ZsGreen+ cells correlated with those up- regulated in human clinical spheroid samples established from patient-derived xenografts derived from CRC tissue samples, further supporting the acquisition of enriched model CSCs. These cells would be useful in identifying novel CSC markers and developing medicine for anti-CSC therapy.