title: CD44 and CD24 cannot act as cancer stem cell markers in human lung adenocarcinoma cell line A549.
abstract: Cancer stem cells (CSCs) are subpopulations of tumor cells that are responsible for tumor initiation, maintenance and metastasis. Recent studies suggested that lung cancer arises from CSCs. In this study, the expression of potential CSC markers in cell line A549 was evaluated. We applied flow cytometry to assess the expression of putative stem cell markers, including aldehyde dehydrogenase 1 (ALDH1), CD24, CD44, CD133 and ABCG2. Cells were then sorted according to the expression of CD44 and CD24 markers by fluorescence-activated cell sorting (FACS) Aria II and characterized using their clonogenic and sphere-forming capacity. A549 cells expressed the CSC markers CD44 and CD24 at 68.16% and 54.46%, respectively. The expression of the putative CSC marker ALDH1 was 4.20%, whereas the expression of ABCG2 and CD133 was 0.93%. Double-positive CD44/133 populations were rare. CD44(+)/24(+) and CD44(+)/CD24(-/low) subpopulations respectively exhibited 64% and 27.92% expression. The colony-forming potentials in the CD44(+)/CD24(+) and CD44(+)/CD24(-/low) subpopulations were 84.37 ± 2.86% and 90 ± 3.06%, respectively, while the parental A549 cells yielded 56.65 ± 2.33% using the colony-formation assay. Both isolated subpopulations formed spheres in serum-free medium supplemented with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). CD44 and CD24 cannot be considered potential markers for isolating lung CSCs in cell line A549, but further investigation using in vivo assays is required.
authors.affiliation: Department of Molecular Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Raheleh
authors.initials: R
authors.lastname: Roudi
authors.forename: Zahra
authors.initials: Z
authors.lastname: Madjd
authors.forename: Marzieh
authors.initials: M
authors.lastname: Ebrahimi
authors.forename: Fazel Sahraneshin
authors.initials: FS
authors.lastname: Samani
authors.forename: Ali
authors.initials: A
authors.lastname: Samadikuchaksaraei
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D000080924:Aldehyde Dehydrogenase 1 Family; D014408:Biomarkers, Tumor / Q000235:genetics*; D051927:CD24 Antigen / Q000235:genetics*; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics*; D007527:Isoenzymes / Q000235:genetics; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology; D050697:Retinal Dehydrogenase / Q000235:genetics
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D014408:Biomarkers, Tumor; D051927:CD24 Antigen; C497889:CD24 protein, human; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D007527:Isoenzymes; D009363:Neoplasm Proteins; D000080924:Aldehyde Dehydrogenase 1 Family; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase