Characterization of canine MDR1 mRNA: its abundance in drug resistant cell lines and in vivo.
BACKGROUND
Overexpression of the MDR1 gene often contributes to antineoplastic drug resistance. The purpose of this study was to characterize the canine MDR1 mRNA homologue and evaluate its expression in both canine cell lines and lymphomas.


METHODS
The abundance of the canine MDR1 transcript was assessed in three resistant cell lines and in pretreatment canine lymphoma using semi-quantitative RT/PCR.


RESULTS
Canine transcript was 4.5 Kb with 93% sequence homology to human MDR1, and 90% homology to mouse and hamster equivalent genes. Increase in MDR1 transcript levels was observed in three progressively resistant canine cell lines. De novo MDR1 transcript expression was independent of response to therapy in dogs with lymphoma.


CONCLUSIONS
We conclude that the canine MDR1 mRNA homologue is structurally similar to the human transcript. Expression of MDR1 mRNA correlates with in vitro drug sensitivity but does not correlate with in vivo doxorubicin sensitivity in canine lymphoma.
Steingold
S F
SF
North Carolina State University, College of Veterinary Medicine, Raleigh 27606, USA.
Sharp
N J
NJ
McGahan
M C
MC
Hughes
C S
CS
Dunn
S E
SE
Page
R L
RL
D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004283:Dog Diseases / Q000188:drug therapy; D004285:Dogs / Q000235:genetics*; D004317:Doxorubicin / Q000627:therapeutic use; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D019450:Genes, MDR; D006801:Humans; D008099:Liver / Q000378:metabolism; D008223:Lymphoma / Q000188:drug therapy / Q000662:veterinary; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D012333:RNA, Messenger; D004317:Doxorubicin