title: Molecular changes to HeLa cells on continuous exposure to SN-38, an active metabolite of irinotecan hydrochloride.
abstract: It is important to clarify the molecular characteristics of tumor cells showing multidrug resistance (MDR) and to identify the novel targets or biomarkers for chemotherapy. The aim of this study is to establish resistant HeLa sublines through exposure to SN-38, an active metabolite of irinotecan hydrochloride, and to investigate their molecular changes. HeLa cells were exposed to SN-38 at 1, 10, or 100 nM, and resistant clones were isolated and named HeLa/SN1, HeLa/SN10, and HeLa/SN100, respectively. Their cellular changes were examined based on growth inhibition assays, the function of ABCG2/BCRP, and a RT-PCR analysis of MDR-related protein. The sublines showed a decrease in sensitivity to not only SN-38 but also other chemotherapeutic agents as compared with HeLa cells. mRNA and protein levels of ABCG2/BCRP were increased, and the transport activity of ABCG2/BCRP was enhanced, in the resistant cells. In addition, the expression levels of ABCC1/MRP1, ABCC3/MRP3, and ABCC5/MRP5 were higher than in HeLa cells. The mRNA levels of GGT1 encoding a gamma-glutamyl transferase, but not GCS encoding a gamma-glutamyl cysteine synthetase, were also higher. Other factors examined, i.e., topoisomerase, SLCO1B1, and apoptosis-regulating factors, were comparable among the cells. The overexpression of ABCG2/BCRP was involved in the mechanism of resistance in SN-38-tolerant cells, and ABCC1/MRP1, ABCC3/MRP3, ABCC5/MRP5, and GGT1 may also have participated.
authors.affiliation: Department of Clinical Pharmacy, Division of Clinical Pharmaceutical Sciences, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan. takara@mb.kyoto-phu.ac.jp
authors.forename: Kohji
authors.initials: K
authors.lastname: Takara
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kitada
authors.forename: Eri
authors.initials: E
authors.lastname: Yoshikawa
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Sayo
authors.initials: S
authors.lastname: Horibe
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakaeda
authors.forename: Kohshi
authors.initials: K
authors.lastname: Nishiguchi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ohnishi
authors.forename: Teruyoshi
authors.initials: T
authors.lastname: Yokoyama
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004361:Drug Tolerance; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D000077146:Irinotecan; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000972:Antineoplastic Agents, Phytogenic; D002166:Camptothecin; D000077146:Irinotecan; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; C120809:ABCC5 protein, human; C116614:ABCG2 protein, human; C114462:multidrug resistance-associated protein 3