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.
Slovak
M L
ML
Department of Cytogenetics, City of Hope National Medical Center, Duarte, California 91010.
Ho
J P
JP
Bhardwaj
G
G
Kurz
E U
EU
Deeley
R G
RG
Cole
S P
SP
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