Effective enrichment of prostate cancer stem cells from spheres in a suspension culture system

Background: Stem-like prostate cancer cells are also called prostate cancer stem cells (PrCSCs). These rare cells are supposed to be highly tumorigenic and to be involved in maintenance of tumor homeostasis and mediation of tumor metastasis. Methods for sorting PrCSCs are mainly based on sorting cells with the marker (CD133(+)/CD44(+)) or side population cells. However, CD133(+)/CD44(+) cells or side population cells are very rare or even undetectable. The scarcity of approaches for isolation and purification of PrCSCs is the main obstacle to studying PrCSCs. Methods: In the present study, suspension culture was used for enrichment of PrCSCs. And PrCSCs were verified by side population technology, drug sensitivity assays, and the molecular marker analysis of prostate cancer stem cell. Results: PC3 cells survived and formed spheres in nonadherent suspension culture. The percentage of CD44(+)/CD133(+) cells was 18-fold higher in the nonadherent sphere-forming cell population than in the adherent PC3 cell population (13.94% vs. 0.77%, respectively). This side population was increased to 3.1% in the nonadherent population but undetectable in adherent population. Resistance to cisplatin was higher in the nonadherent cells than adherent cells. Conclusion: Suspension culture can be used to enrich for PrCSCs. This approach will aid prostate stem cell biology research and facilitate identification of novel therapeutic agents for prostate cancer. (C) 2012 Elsevier Inc. All rights reserved.