@article{oai:rakuno.repo.nii.ac.jp:00002202,
 author = {NAKAICHI, Munekazu and TAKESHITA, Yoko and OKUDA, Masaru and NAKAMOTO, Yuya and ITAMOTO, Kazuhito and UNE, Satoshi and SASAKI, Nobuo and KADOSAWA, Tsuyoshi and TAKAHASHI, Tomoko and TAURA, Yasuho},
 issue = {2},
 journal = {The Journal of Veterinary Medical Science},
 month = {Feb},
 note = {Article, Cellular drug resistance to antineoplastic drugs is often due to the presence of a drug efflux pump that reduces intracellular drug accumulation and chemosensitivity. P-glycoprotein (P-gp), which is encoded by the MDR1 gene, is considered to function as an ATP-driven membrane drug efflux pump and appears to play an important role in tumor cell resistance. In the present report, we assessed the expression of MDR1 by RT-PCR in three canine mast cell tumor cell lines, TiMC, CoMS and LuMC, originating from a cutaneous tumor, an oral-mucosal tumor and a gastrointestinal tumor, respectively. P-gp expression was also examined by Western blot analysis, while the functional activity of P-gp was assessed by flowcytometric analysis of intracellular rhodamine-123 (Rhd-123) uptake. The results revealed that MDR1 gene and P-gp were both expressed in CoMS and LuMC cells, whereas neither was present in TiMC cells. In CoMS and LuMC cells, intracellular uptake of Rhd-123 increased in the presence of verapamil, a functional modulator of P-gp. In contrast, TiMC cells did not show any changes in the intracellular accumulation of Rhd-123 after the verapamil addition. These findings suggest that the expressions of MDR1 gene and P-gp probably contribute to cellular drug resistance in canine mast cell tumors.},
 pages = {111--115},
 title = {Expression of the MDR1 gene and P-glycoprotein in canine mast cell tumor cell lines},
 volume = {69},
 year = {2007}
}