Molecular analysis of multidrug resistance in feline lymphoma cells.
OBJECTIVE
To evaluate the mechanism of multidrug resistance in feline lymphoma cell lines.


METHODS
A feline lymphoma cell line (FT-1) and its adriamycin (ADM)-resistant subline (FT-1/ADM).


METHODS
The FT-1 cell line was cultivated in the presence of a gradually increasing concentration of ADM to generate its ADM-resistant subline (FT-1/ADM). Susceptibility of cells from the parental FT-1 cell line and the FT-1/ADM subline to antineoplastic drugs was determined. From the complementary DNA (cDNA) template of FT-1/ADM cells, feline MDR1 cDNA was amplified by use of polymerase chain reaction (PCR) and sequenced. Reverse transcription (RT)-PCR and Western blot analyses were performed to assess expression of the MDR1 gene and P-glycoprotein (P-gp) in FT-1/ADM cells, compared with that in FT-1 cells.


RESULTS
A drug sensitivity assay revealed that FT-1/ADM cells were much more resistant to ADM and vincristine than the parental FT-1 cells. The feline MDR7 cDNA amplified by use of PCR was 3,489 base pairs long, corresponding to approximately 90% of the whole open reading frame of human MDR1 cDNA; its amino acid sequence was 91.5, 87.0, and 79.4% identical to that of human MDR1, mouse mdr1a, and mdr1b cDNA, respectively. By RT-PCR analysis, expression of MDR1 messenger RNA was clearly detected in FT-1/ADM cells but not in the parental FT-1 cells. Western blot analysis also revealed the expression of P-gp encoded by the MDR1 gene in FT-1/ADM cells but not in FT-1 cells.


CONCLUSIONS
The basic structure of the feline MDR1 gene was essentially the same as that of multidrug-resistance genes of other species. Expression of P-gp appeared to be one of the mechanisms responsible for the development of multidrug resistance in feline lymphoma cell lines in vitro.
Okai
Y
Y
Department of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan.
Nakamura
N
N
Matsushiro
H
H
Kato
H
H
Setoguchi
A
A
Yazawa
M
M
Okuda
M
M
Watari
T
T
Hasegawa
A
A
Tsujimoto
H
H
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western / Q000662:veterinary; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D006801:Humans; D008223:Lymphoma / Q000188:drug therapy / Q000662:veterinary*; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D004317:Doxorubicin