Establishment of an adriamycin-resistant subline of human small cell lung cancer showing multifactorial mechanisms of resistance.
A subline highly resistant to Adriamycin (SBC-3/ADM100) was isolated in vitro from the human small cell lung cancer cell line, SBC-3, by culturing in progressively higher concentrations of Adriamycin. The SBC-3/ADM100 cells were 106-fold more resistant to the drug than the parent cells in an inhibitory concentration of 50% determined by the MTT assay. The population-doubling time was much longer in SBC-3/ADM100 than in the parent cells. Northern blot hybridization revealed marked overexpression of the MDR1 mRNA in the resistant cells. P-glycoprotein overexpression and a decrease in intracellular accumulation of Adriamycin were demonstrated in SBC-3/ADM100, indicating that outward drug transport was the major mechanism of resistance in this subline. Additionally, a significant elevation of the intracellular glutathione content coupled with the glutathione S-transferase (GST) pi level and a decrease in DNA topoisomerase II (Topo II) activity were noted in this resistant subline. These results indicate that the mechanism of resistance to Adriamycin is multifactorial; involving altered growth characteristics, an enhanced outward transport, enhanced drug detoxification process, and decreased target enzyme activity. The resistant subline will serve as a useful tool in the search for ways to overcome drug resistance.
Kiura
K
K
Second Department of Medicine, Okayama University Medical School, Japan.
Ohnoshi
T
T
Tabata
M
M
Shibayama
T
T
Kimura
I
I
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018288:Carcinoma, Small Cell / Q000188:drug therapy*; D002352:Carrier Proteins / Q000032:analysis; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D004351:Drug Resistance; D005978:Glutathione / Q000032:analysis; D005982:Glutathione Transferase / Q000032:analysis; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy*; D008562:Membrane Glycoproteins / Q000032:analysis; D009363:Neoplasm Proteins / Q000032:analysis; D012333:RNA, Messenger / Q000096:biosynthesis; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D004317:Doxorubicin; D005982:Glutathione Transferase; D004250:DNA Topoisomerases, Type II; D005978:Glutathione