title: The Proportion of ALDEFLUOR-Positive Cancer Stem Cells Changes with Cell Culture Density Due to the Expression of Different ALDH Isoforms.
abstract: A significant number of discrepancies exist within the literature regarding ALDEFLUOR-positive stem cell populations in cell lines. We hypothesized that these inconsistencies resulted from differences in culture conditions, particularly cell density. We cultured several colon cancer cell lines (N=8) at high and low densities and found a significant decrease in ALDEFLUOR-positive cell populations at high density. However, we found no changes in the CD166-positive stem cell population, self-renewal, or cell cycle distribution of cells cultured at different densities. Interestingly, when we sorted both ALDEFLUOR positive and negative populations from the different density cultures, we identified a significant number of Aldehyde dehydrogenase (ALDH) isoforms whose expression was decreased in ALDEFLUOR-positive stem cells cultured at high density. This novel finding suggests that multiple ALDH isoforms contribute to ALDEFLUOR activity in colon cancer stem cells and decreases in ALDEFLUOR-positive stem cells at high cell density are due to decreased expression of multiple ALDH isoforms. Thus, designing therapeutics to target ALDEFLUOR-positive cancer stem cells may require inhibition of multiple ALDH isoforms.
authors.affiliation: Department of Biological Sciences, University of Delaware, 118 Wolf Hall, Newark, DE 19716, USA; Center for Translational Cancer Research, Helen F. Graham Cancer Center and Research Institute, 4701 Ogletown-Stanton Rd, Newark, DE 19713, USA.
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Opdenaker
authors.affiliation: Department of Biological Sciences, University of Delaware, 118 Wolf Hall, Newark, DE 19716, USA; Center for Translational Cancer Research, Helen F. Graham Cancer Center and Research Institute, 4701 Ogletown-Stanton Rd, Newark, DE 19713, USA.
authors.forename: Shirin R
authors.initials: SR
authors.lastname: Modarai
authors.affiliation: Department of Biological Sciences, University of Delaware, 118 Wolf Hall, Newark, DE 19716, USA; Center for Translational Cancer Research, Helen F. Graham Cancer Center and Research Institute, 4701 Ogletown-Stanton Rd, Newark, DE 19713, USA.
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Boman
keywords: ALDEFLUOR; ALDH isoforms; Cancer stem cells; Density