title: The molecular mechanisms responsible for resistance to ET-743 (Trabectidin; Yondelis) in the Ewing's sarcoma cell line, TC-71.
abstract: Identification of new active agents against sarcoma is considered an important challenge in medical oncology. ET-743 (Trabectidin; Yondelis) has recently emerged as the first active drug developed against sarcoma in the last two decades, with promising results especially against soft-tissue sarcoma and Ewing's sarcoma (ES). In this study, we analyzed the molecular mechanisms responsible for resistance to ET-743 in ES cells. Three resistant cell variants (TC/ET 3 nM, TC/ET 6 nM and TC/ET 12 nM) were obtained, showing 28-, 47- and 102-fold increase in ET-743 resistance. Cross-resistance to other drugs was analyzed. Comparative genomic hybridization and cDNA microarray technology were employed to characterize and compare the gene expression profile of two TC/ET variants with the parental cell line. TC/ET cells show a conventional multidrug resistance phenotype and P-glycoprotein overexpression was found to significantly contribute to ET-743 resistance. However, functional studies with the cyclosporine analogue, PSC-833, indicate that other mechanisms are involved in resistance to ET-743. The gene expression profile of TC/ET cells indicated, among up-regulated genes, an increase in expression of insulin-like growth factor receptor-I (IGF-IR) and one of its major intracellular mediators, insulin receptor substrate-1. Functional studies using a neutralizing antibody anti-IGF-IR confirmed involvement of this signaling pathway in resistance to ET-743. Simultaneous blockage of both P-glycoprotein and IGF-IR completely restored sensitivity to ET-743 in ES cells. Overall, these findings provide impetus for future studies testing the therapeutic value of new specific inhibitors of P-glycoprotein and IGF-IR, which could represent a concrete therapeutic option for ES patients refractory to conventional agents.
authors.affiliation: Laboratorio di Ricerca Oncologica, Istituti Ortopedici Rizzoli, I-40136 Bologna, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Manara
authors.forename: S
authors.initials: S
authors.lastname: Perdichizzi
authors.forename: M
authors.initials: M
authors.lastname: Serra
authors.forename: R
authors.initials: R
authors.lastname: Pierini
authors.forename: S
authors.initials: S
authors.lastname: Benini
authors.forename: C M
authors.initials: CM
authors.lastname: Hattinger
authors.forename: A
authors.initials: A
authors.lastname: Astolfi
authors.forename: R
authors.initials: R
authors.lastname: Bagnati
authors.forename: M
authors.initials: M
authors.lastname: D'Incalci
authors.forename: P
authors.initials: P
authors.lastname: Picci
authors.forename: K
authors.initials: K
authors.lastname: Scotlandi
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003524:Cyclosporins / Q000494:pharmacology; D004149:Dioxoles / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D015894:Genome, Human; D006801:Humans; D020128:Inhibitory Concentration 50; D007546:Isoquinolines / Q000494:pharmacology*; D009693:Nucleic Acid Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D017526:Receptor, IGF Type 1 / Q000235:genetics; D012512:Sarcoma, Ewing / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D044005:Tetrahydroisoquinolines; D013997:Time Factors; D000077606:Trabectedin
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018906:Antineoplastic Agents, Alkylating; D003524:Cyclosporins; D004149:Dioxoles; D007546:Isoquinolines; D044005:Tetrahydroisoquinolines; D017526:Receptor, IGF Type 1; D000077606:Trabectedin; C070272:valspodar