title: Multidrug resistance mediated by ABC transporters in osteosarcoma cell lines: mRNA analysis and functional radiotracer studies.
abstract: Drug resistance remains a significant impediment to successful chemotherapy and constitutes a major prognostic factor in osteosarcoma (OS) patients. This study was designed to identify the role and prognostic significance of multidrug-resistance (MDR)-related transporters, such as multidrug resistance protein 1 (MDR1), multidrug-resistance-associated protein (MRP1) and breast-cancer-related protein (BCRP), in OS using cationic lipophilic radiotracers. We evaluated the chemosensitivity of four OS cell lines (Saos-2, 143B, MNNG/HOS and U-2OS) to doxorubicin (DOX), cisplatin (CIS) and methotrexate. The expression of MDR-related transporters was analyzed at mRNA level by quantitative polymerase chain reaction and at functional level by 99mTc sestamibi and 99mTc tetrofosmin. The effectiveness of MDR modulators [cyclosporin A (CsA) and imatinib] on transporter inhibition and on the reversal of resistance was also assessed. MNNG/HOS and U-2OS cells expressing high levels of MDR1 were highly resistant to DOX and showed reduced accumulation and higher efflux for radiotracers. Although MRP1 was uniformly expressed in all cells, only U-2OS was resistant to CIS. CsA restored sensitivity to DOX and CIS, and enhanced the accumulation and efflux half-life of radiotracers in MDR1-expressing cell lines. The chemosensitivity of OS cells to DOX was strongly dependent on mRNA MDR1 expression and could be circumvented by adding CsA. The kinetic parameters of radiotracers correlated with MDR1 expression levels, hence predicting DOX resistance. We concluded that sensitivity to chemotherapy is strongly dependent on the expression of MDR1 transporter and that radiotracer studies could prove clinically useful in predicting chemotherapy response and in evaluating the efficacy of MDR-reversing agents.
authors.affiliation: Department of Pathology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands. cgomes@ibili.uc.pt
authors.forename: Celia Maria Freitas
authors.initials: CM
authors.lastname: Gomes
authors.forename: Heidi
authors.initials: H
authors.lastname: van Paassen
authors.forename: Salvatore
authors.initials: S
authors.lastname: Romeo
authors.forename: Mick M
authors.initials: MM
authors.lastname: Welling
authors.forename: R I J
authors.initials: RI
authors.lastname: Feitsma
authors.forename: Antero J
authors.initials: AJ
authors.lastname: Abrunhosa
authors.forename: M Filomena
authors.initials: MF
authors.lastname: Botelho
authors.forename: Pancras C W
authors.initials: PC
authors.lastname: Hogendoorn
authors.forename: Ernest
authors.initials: E
authors.lastname: Pauwels
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Cleton-Jansen
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D012516:Osteosarcoma / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D011865:Radioisotope Dilution Technique
chemical_list: D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger