Enrichment of prostate cancer stemlike cells from human prostate cancer cell lines by culture in serum-free medium and chemoradiotherapy. Int J Biol Sci 9: 472–479. doi: 10.7150/ijbs.5855 PMID: 23781140

licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. Received: 2013.01.10; Accepted: 2013.05.09; Published: 2013.05.15 The discovery of rare subpopulations of cancer stem cells (CSCs) has created a new focus in cancer research. As CSCs demonstrate resistance to chemoradiation therapy relative to other cancer cells, this allows the enrichment of CSC populations by killing apoptosis-susceptible cancer cells. In this study, three commonly used human prostate cancer (PCa) cell lines (DU145, PC-3 and LNCaP) were examined for their expression of the putative stem cell markers CD133 and CD44 via flow cytometric analysis. Under normal culture conditions, CD133+/CD44+ cells were only present in the DU145 cell line, and comprised only a minor percentage (0.1 % ± 0.01%) of the total population. However, the proportion of these CD133+/CD44+ prostate CSCs could be increased in these cell lines via culture in serum-free medium (SFM), or through chemotherapy or radio-therapy. Indeed, after culture in SFM, the proportion of CD133+/CD44+ cells in DU145 and PC-3 had increased to 10.3 % and 3.0%, respectively. Moreover, the proportion had increased to 9.8% enriched by chemotherapy and 3.5 % by radiotherapy in DU145. Colony-formation tests, cell in