Research Project
Grant-in-Aid for Scientific Research (C)
1.We have isolated aesenite-resistant human epidermoid carcinoma KB cells, termed KAS. KAS cells are resistant to both sodium arsenite and cisplatin compared to the parental KB-3-1 cells. To identify the genes responsible for the resistance to these agents, we employed microarray analysis, using a platform dedicated to drug resistance. The ABC-ToxChip and real-time PCR analyses revealed the increased expression of the mitocondrial ABC transporter ABCB6 in KAS cells. We established KB-B6 cells, KB-3-1 cells stably transfected with ABCB6 expression vector, to study the role of the transporter in arsenite resistance. KB-B6 cells were resistant to sodium arsenite and Accurnulation of cisplatin in KB-B6 cisplatin in KB-B6 cells was decreassed compared with the KB/CV cells cisplatin.The decleased DNA adduct in both genome and mitochondrial DNAs in KB-B6 cells was observed. Our results suggest that ABCB6 is also localized in plasma membranes and transports cisplatin outside the cells.2.We studied the mechanism of drug transport by MRP1 that confers resistance to arsenite. We investigated the function of the signature sequences in NBDs of MRP1 using the mutant MRP1s that have mutations of the signature sequences (G771D and G1433D). Our findings suggested that both signature sequences of MRP1 are involved in ATP hydrolysis and must be intact for the ATP hydrolysis and transport by MRP1.The accumulated evidence has proved that GSH interacts with MRP1 and stimulates drug transport. However, the mechanism of GSH-dependent drug trasport by MRP1 remains unclear. In this study, we used limited tryptic digestion of MRP1 in isolated membrane vesicles, in the presence and absence of GSH, to investigate the influence of GSH on MRP1 conformation. Our results suggested that GSH induces a conformational change at a site within the MRP1 that is indispensable for the interaction of MRP1 with its substrates.
All 2005 2004 2003 Other
All Journal Article (15 results) Publications (7 results)
J.Biol.Chem. 280
Pages: 6231-6237
Cancer Sci 96
Pages: 327-376
Cancer Res. 64
Pages: 1749-1801
Mol.Pharmacol 65
Pages: 1536-1542
Tetrahedron 60
Pages: 7053-7059
Biochem Pharmacol. 68
Pages: 1363-1370
Biochem.Biophys.Res.Commun. 326
Pages: 100-107
Mol.Pharmacol. 65
Mol.Pharmacol. 63
Pages: 65-72
Br.J.Pharmacol. 138
Pages: 1553-1561
Biochem.Biophys.Res.Commun. 301
Pages: 358-363
Biochemical Pharmacol. (in press)