title: Stem cell-like side populations in esophageal cancer: a source of chemotherapy resistance and metastases.
abstract: Dye-effluxing side population (SP) cells can be resistant to chemotherapy and are thought to resemble cancer stem cells. We characterized the relevance of the SP subpopulation in esophageal cancer cell lines and their relation to chemotherapy resistance and metastasis. The SP subpopulation was detected using Hoechst 33342 staining in five esophageal cancer cell lines OE19, OE21, OE33, PT1590, and LN1590. CTx-resistant cell lines were developed after long-term exposure to 5-fluorouracil (5-FU) and cisplatin and validated by analysis of resistance markers, thymidylate synthase and ERCC1. While neither LN1590 nor PT1590 had detectable SP cells, OE19, OE21, and OE33 cells were found to contain varying levels of SP cells. With increasing duration of 5-FU or cisplatin therapy, the SP subpopulation substantially emerged in PT1590 and LN1590. OE19-SP cells displayed significant higher tumorigenicity than OE19- non-SP (NSP) cells after subcutaneous tumor cell injection in vivo. SP cells isolated from OE19 and OE19/5-FUres were subsequently analyzed by an epithelial-to-mesenchymal transition (EMT) polymerase chain reaction array. Interestingly, the SP fraction of OE19/5-FUres showed a dramatic upregulation of EMT-related genes compared to the SP fraction of OE19. Our results provide evidence that (1) the proportion of SP cells is different in esophageal cancer, (2) SP cells exhibit stem cell properties and are associated to chemotherapy resistance, and (3) long-term CTx selects for SP cells with an upregulated EMT gene profile, which might be the source of systemic disease relapse. Further investigations are necessary to ideally target these EMT-associated SP cells in esophageal cancer.
authors.affiliation: 1 Department of Surgery, University of Munich , Munich, Germany .
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.forename: Qi
authors.initials: Q
authors.lastname: Bao
authors.forename: Bettina
authors.initials: B
authors.lastname: Schwarz
authors.forename: Lu
authors.initials: L
authors.lastname: Zhao
authors.forename: Josef
authors.initials: J
authors.lastname: Mysliwietz
authors.forename: Joachim
authors.initials: J
authors.lastname: Ellwart
authors.forename: Andera
authors.initials: A
authors.lastname: Renner
authors.forename: Heidrun
authors.initials: H
authors.lastname: Hirner
authors.forename: Hanno
authors.initials: H
authors.lastname: Niess
authors.forename: Peter
authors.initials: P
authors.lastname: Camaj
authors.forename: Martin
authors.initials: M
authors.lastname: Angele
authors.forename: Stephanie
authors.initials: S
authors.lastname: Gros
authors.forename: Jakob
authors.initials: J
authors.lastname: Izbicki
authors.forename: Karl-Walter
authors.initials: KW
authors.lastname: Jauch
authors.forename: Peter Jon
authors.initials: PJ
authors.lastname: Nelson
authors.forename: Christiane J
authors.initials: CJ
authors.lastname: Bruns
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis; D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000473:pathology*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D019008:Drug Resistance, Neoplasm; D004720:Endonucleases / Q000096:biosynthesis; D058750:Epithelial-Mesenchymal Transition; D004938:Esophageal Neoplasms / Q000188:drug therapy / Q000473:pathology*; D000077277:Esophageal Squamous Cell Carcinoma; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis; D009362:Neoplasm Metastasis / Q000473:pathology*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D014411:Neoplastic Stem Cells / Q000166:cytology*; D058985:Side-Population Cells / Q000166:cytology*; D013940:Thymidylate Synthase / Q000096:biosynthesis; D051176:beta Catenin / Q000096:biosynthesis
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000963:Antimetabolites; D000970:Antineoplastic Agents; D002945:Cisplatin; D004268:DNA-Binding Proteins; D004720:Endonucleases; D005472:Fluorouracil; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D013940:Thymidylate Synthase; D051176:beta Catenin; C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; C114462:multidrug resistance-associated protein 3; C071447:ERCC1 protein, human