Esophageal cancer tumorspheres involve cancer stem-like populations             with elevated aldehyde dehydrogenase enzymatic activity.
Cancer stem cells (CSCs) form spheres in vitro in serum-free suspension             culture. Sphere formation is particularly useful to enrich the potential CSC subpopulations             as a functional approach. Few reports are currently available on tumorspheres             in esophageal cancer (EC). The present study focused on evaluating the cancer             stem-like properties and analyzing the difference between spheroid and adherent             cells of the Eca109 human EC cell line. Immunofluorescence and immunoblotting             analysis revealed that EC tumorspheres expressed the stem cell markers Nanog and             Oct4 more highly, but showed a decreased expression of the differentiation marker             CK5/6. The spheroids were chemoresistant to cisplatin compared to the adherent             cells (32.5 vs. 135.8 µM in IC50). Side population cells increased in tumorspheres             compared to adherent cells (0.7 vs. 5.6%). A marked upregulation of drug-resistant             genes (ABCG2 and MDR1) was observed in sphere-forming cells. We compared the profiles             of adherent and spheroid cells by microarrays and obtained one representative             differentially expressed gene, aldehyde dehydrogenase (ALDH). We also verified             that the cancer stem-like cells of EC contained a high ALDH enzymatic activity.             ALDH-positive cells were enriched by 11- to 12-fold in spheroids, compared to             adherent cells (2.5 vs. 28.6%). Immunofluorescence and immunoblotting analysis             also revealed a higher expression of ALDH in EC tumorspheres. In conclusion, our             study verified that sphere-forming culturing can be utilized to demonstrate the             putative esophageal CSCs, and identified a potential esophageal CSC surface marker,             ALDH.
Cancer Research Institute of Southern Medical University, Internal Medical Department of Guangzhou Medical University Cancer Institute and Hospital, Guangzhou 510515, PR China.
Gong
G
Zhang
Lei
L
Ma
You-Ke
YK
Xie
Xiao-Bo
XB
Miao
Chuan
C
Jin
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D002945:Cisplatin / Q000633:toxicity; D016895:Culture Media, Serum-Free; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004938:Esophageal Neoplasms / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D020869:Gene Expression Profiling; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D018874:Spheroids, Cellular / Q000201:enzymology / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
C116614:ABCG2 protein, human; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D016895:Culture Media, Serum-Free; D009363:Neoplasm Proteins; D000444:Aldehyde Dehydrogenase; D002945:Cisplatin