title: P-glycoprotein confers acquired resistance to 17-DMAG in lung cancers with an ALK rearrangement.
abstract: BACKGROUND
  Because anaplastic lymphoma kinase (ALK) is dependent on Hsp90 for protein stability, Hsp90 inhibitors are effective in controlling growth of lung cancer cells with ALK rearrangement. We investigated the mechanism of acquired resistance to 17-(Dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG), a geldanamycin analogue Hsp90 inhibitor, in H3122 and H2228 non-small cell lung cancer cell lines with ALK rearrangement.
  
  
  METHODS
  Resistant cell lines (H3122/DR-1, H3122/DR-2 and H2228/DR) were established by repeated exposure to increasing concentrations of 17-DMAG. Mechanisms for resistance by either NAD(P)H/quinone oxidoreductase 1 (NQO1), previously known as a factor related to 17-DMAG resistance, or P-glycoprotein (P-gp; ABCB1/MDR1) were queried using RT-PCR, western blot analysis, chemical inhibitors, the MTT cell proliferation/survival assay, and cellular efflux of rhodamine 123.
  
  
  RESULTS
  The resistant cells showed no cross-resistance to AUY922 or ALK inhibitors, suggesting that ALK dependency persists in cells with acquired resistance to 17-DMAG. Although expression of NQO1 was decreased in H3122/DR-1 and H3122/DR-2, NQO1 inhibition by dicumarol did not affect the response of parental cells (H2228 and H3122) to 17-DMAG. Interestingly, all resistant cells showed the induction of P-gp at the protein and RNA levels, which was associated with an increased efflux of the P-gp substrate rhodamine 123 (Rho123). Transfection with siRNA directed against P-gp or treatment with verapamil, an inhibitor of P-gp, restored the sensitivity to the drug in all cells with acquired resistance to 17-DMAG. Furthermore, we also observed that the growth-inhibitory effect of 17-DMAG was decreased in A549/PR and H460/PR cells generated to over-express P-gp by long-term exposure to paclitaxel, and these cells recovered their sensitivity to 17-DMAG through the inhibition of P-gp.
  
  
  CONCLUSIONS
  P-gp over-expression is a possible mechanism of acquired resistance to 17-DMAG in cells with ALK rearrangement.
authors.affiliation: Department of Internal Medicine, Konkuk University Medical Center, Seoul, South Korea. hjkim@kuh.ac.kr.
authors.forename: Hee Joung
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Konkuk University Medical Center, Seoul, South Korea. 20050690@kuh.ac.kr.
authors.forename: Kye Young
authors.initials: KY
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Seoul National University College of Medicine, Seoul, South Korea. ywkim@snu.ac.kr.
authors.forename: Young Whan
authors.initials: YW
authors.lastname: Kim
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. choiyj@amc.seoul.kr.
authors.forename: Yun Jung
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. airis011@naver.com.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. ccm@amc.seoul.kr.|Department of Oncology, Asan Medical Center, College of Medicine, University of Ulsan, 86 Asanbyeongwon-gil, Songpa-gu, Seoul, 138-736, South Korea. ccm@amc.seoul.kr.
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Choi
authors.affiliation: Asan Institute for Life Sciences, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. ijbaek@amc.seoul.kr.
authors.forename: In-Jeoung
authors.initials: IJ
authors.lastname: Baek
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. jkrho@amc.seoul.kr.|Asan Institute for Life Sciences, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea. jkrho@amc.seoul.kr.
authors.forename: Jin Kyung
authors.initials: JK
authors.lastname: Rho
authors.affiliation: Department of Oncology, Asan Medical Center, College of Medicine, University of Ulsan, 86 Asanbyeongwon-gil, Songpa-gu, Seoul, 138-736, South Korea. jclee@amc.seoul.kr.
authors.forename: Jae Cheol
authors.initials: JC
authors.lastname: Lee
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D000077548:Anaplastic Lymphoma Kinase; D016227:Benzoquinones / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D001728:Dicumarol / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D016227:Benzoquinones; D047029:Lactams, Macrocyclic; C448659:17-(dimethylaminoethylamino)-17-demethoxygeldanamycin; D001728:Dicumarol; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases; D017239:Paclitaxel