Localization of a novel multidrug resistance-associated gene in the HT1080/DR4 and H69AR human tumor cell lines.
Two doxorubicin-selected human tumor cell lines, H69AR and HT1080/DR4, display a multidrug resistance phenotype but do not overexpress P-glycoprotein. Recently, a 6.5-kilobase mRNA encoding a novel member of the ATP-binding cassette superfamily of transport proteins, designated multidrug resistance-associated protein (MRP), has been identified in the H69AR cell line. In the present study, the levels of MRP mRNA were found to be 14-fold higher in HT1080/DR4 cells relative to sensitive HT1080 cells. Southern blotting indicates that gene amplification contributes to the overexpression of MRP in HT1080/DR4 cells. Using a 4-kilobase MRP complementary DNA probe, MRP genes were localized to 2-5 chromosomes bearing homogeneously staining regions and to multiple double minute chromosomes in H69AR cells. Resistant H69AR cells also contained a new der(16) with a structural aberration affecting 16p13.1, the normal cellular locus of the MRP gene. The MRP probe hybridized to two small homogeneously staining regions (hsr) in HT1080/DR4 cells including hsr(7)(p12p15). MRP localization was restricted to the normal cellular locus, 16p13.1, in the parental H69 and HT1080 cells and the drug-sensitive H69PR revertant cells. Our data provide combined evidence that amplification of the MRP gene is associated with the expression of drug resistance in selected solid tumor cell lines.
Department of Cytogenetics, City of Hope National Medical Center, Duarte, California 91010.
M L
ML
Slovak
J P
JP
Ho
G
G
Bhardwaj
E U
EU
Kurz
R G
RG
Deeley
S P
SP
Cole
D018288:Carcinoma, Small Cell / Q000737:chemistry / Q000188:drug therapy / Q000235:genetics*; D002885:Chromosomes, Human, Pair 16; D004317:Doxorubicin; D004351:Drug Resistance / Q000235:genetics*; D005354:Fibrosarcoma / Q000737:chemistry / Q000188:drug therapy / Q000235:genetics*; D005784:Gene Amplification; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008175:Lung Neoplasms / Q000737:chemistry / Q000188:drug therapy / Q000235:genetics*; D009363:Neoplasm Proteins / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D012334:RNA, Neoplasm / Q000032:analysis*; D014407:Tumor Cells, Cultured
D005819:Genetic Markers; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D004317:Doxorubicin