1995 Fiscal Year Final Research Report Summary
Structure and function of an active efflux pump for cisplatin
| Project/Area Number |
06807015
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Pathological medical chemistry
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| Research Institution | Kagoshima University |
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Principal Investigator |
AKIYAMA Shinichi Kagoshima University, Faculty of Medicine, Professor, 医学部, 教授 (60117413)
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| Co-Investigator(Kenkyū-buntansha) |
FURUKAWA Tatsuhiko Kagoshima University, Faculty of Medicine, Research Associate, 医学部, 助手 (40219100)
HARAGUCHI Misako Kagoshima University, Faculty of Medicine, Research Associate, 医学部, 助手 (10244229)
SUMIZAWA Tomoyuki Kagoshima University, Faculty of Medicine, Research Associate, 医学部, 助手 (90206582)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Cisplatin-resistance / Leukotriene C4 / GS-X pump / MRP |
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| Research Abstract |
An active efflux pump for cis-diamminedichloroplatinum (II) (cisplatin) has been identified in cisplatin-resistant KCP-4 cells isolated from human epidermoid carcinoma KB-3-1 cells. The adesnosine triphosphate (ATP) -dependent transport of leukotriene C_4 (LTC_4) , an endogenous substrate for the glutathione S-conjugate export pump (GS-X pump), has been found in membrane vesicles prepared from KCP-4 cells. Multidrug resistance-associated protein (MRP) has also been identified as an ATP-dependent LTC_4 transporter. To examine whether the GS-X pump expressed in KCP-4 cells is MRP,we investigated the expression of MRP in KCP-4 cells and compared the LTC_4 transporting activity of GS-X pump expressed in KCP-4 cells with that of MRP.The level of MRP gene expression in KCP-4 cells was low and similar to that in KB-3-1 cells. MRP was not detected in membrane vesicles prepared from KB-3-1 and KCP-4 cells by immunoblotting analysis. The ATP-dependent transport of [^3H]LTC_4 was apparent in KCP-4 amd C-A120 vesicles but only slight in KB-3-1 and KB-C2 vesicles. The ATP-dependent transport of LTC_4 in KCP-4 and C-A120 vesicles showed saturable kinetics with an apparent Km of 0.445muM and 1.55muM,respectively. [^3H]LTC_4 transport in KCP-4 vesicles was more inhibited by 2,4-dinitrophenyl-S-glutathione (DNP-SG), bis- (glutathionato) -platinum (II) (GS-platinum) complex and glutathione disulfide (GS-SG) and less by LTD_4 compared with that in C-A120 vesicles. The character of the LTC_4 transporter expressed in KCP-4 vesicles is similar but not identical to that of MRP.Our results suggest that a glutathione S-conjugate export pump which is different from MRP exists in cisplatin-resistant KCP-4 cells.
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