title: Multidrug resistance proteins in gastrointestinal stromal tumors: site-dependent expression and initial response to imatinib.
abstract: Gastrointestinal stromal tumors (GIST) are the most frequent mesenchymal tumors of the digestive tract and respond poorly to chemotherapy. A tyrosine kinase inhibitor treatment, imatinib mesylate, was recently shown to have antitumor effects in metastatic patients. However, this drug is a substrate for multidrug resistance (MDR) proteins. Therefore, we investigated the expression of ABCB1 (P-glycoprotein), ABCC1 (MRP1), and ABCG2 (BCRP) by Western blotting in 21 GISTs and 3 leiomyosarcomas. All the GISTs were positive for either ABCB1 (86% of cases) or ABCC1 expression (62%), but negative for ABCG2. ABCB1 was expressed in all gastric GISTs, but in only 67% of nongastric GISTs. By contrast, ABCC1 expression was more common in nongastric tumors (78% versus 42%). The levels of these MDR proteins in gastric GISTs were higher for ABCB1 (P = 0.007) and lower for ABCC1 (P = 0.004) compared with nongastric GISTs. We found no correlation between MDR protein expression and the risk assessment. None of the six patients treated with imatinib was resistant, although all were positive for at least one MDR protein. These results confirm that gastric and nongastric GISTs have different biological characteristics and suggest that MDR proteins do not impair the initial response of the tumor to imatinib.
authors.affiliation: Pharmacy Department, Paul Brousse Hospital, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Théou
authors.forename: Sophie
authors.initials: S
authors.lastname: Gil
authors.forename: Anne
authors.initials: A
authors.lastname: Devocelle
authors.forename: Catherine
authors.initials: C
authors.lastname: Julié
authors.forename: Anne
authors.initials: A
authors.lastname: Lavergne-Slove
authors.forename: Alain
authors.initials: A
authors.lastname: Beauchet
authors.forename: Patrice
authors.initials: P
authors.lastname: Callard
authors.forename: Robert
authors.initials: R
authors.lastname: Farinotti
authors.forename: Axel
authors.initials: A
authors.lastname: Le Cesne
authors.forename: Antoinette
authors.initials: A
authors.lastname: Lemoine
authors.forename: Laurence
authors.initials: L
authors.lastname: Faivre-Bonhomme
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Emile
mesh_terms: 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; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology; D001549:Benzamides; D015153:Blotting, Western; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry; D007890:Leiomyosarcoma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis; D009363:Neoplasm Proteins / Q000096:biosynthesis; D010879:Piperazines / Q000627:therapeutic use*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011743:Pyrimidines / Q000627:therapeutic use*; D012306:Risk
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; D000970:Antineoplastic Agents; D001549:Benzamides; D004791:Enzyme Inhibitors; D000068877:Imatinib Mesylate; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011505:Protein-Tyrosine Kinases; D011743:Pyrimidines; C116614:ABCG2 protein, human; C421109:multidrug resistance-associated protein 1