2002 Fiscal Year Final Research Report Summary
Functional analysis of human cancer cells which overexpress MXR
| Project/Area Number |
13671659
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Urology
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| Research Institution | Kagoshima University |
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Principal Investigator |
NISHIYAMA Kenryu Kagoshima University, Faculty of Medicine and University Hospital, Assistant Professor, 医学部附属病院, 講師 (80264422)
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| Co-Investigator(Kenkyū-buntansha) |
KUBO Hiroyuki Kagoshima University, University Hospital, Faculty of Medicine, Research Associate, 医学部附属病院, 助手 (60336344)
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| Project Period (FY) |
2001 – 2002
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| Keywords | MXR / multidrug resistance / GS-X pump |
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| Research Abstract |
(1) A rabbit anti-serum against MXR was raised against 15mer synthesized oligopeptide. About 70kDa band was detected in MXR overexpressing MCF-7 AdVp3000 cells by immunoblot analysis, confirming the serum recognized MXR. MXR localized mainly to plasma membrane of MCF-7 AdVp3000 cells by immunohistochemistry, indicating that MXR is a plasma membrane transporter.
(2) Expression of MXRmRNA in 20 renal cell carcinomas (RCCs) was determined by real time PCR. Although expression levels were low, RCCs expressed higher level of MXRmRNA than normal kidney tissues. This may indicate that MXR contribute to an intrinsic drug resistance in RCC.
(3) Flow cytometry demonstrated ATP-dependent rhodamine 123 efflux in MCF-7 AdVp3000 cells. However, the P-glycoprotein (P-gp) antagonist, PSC833 could not inhibit the efflux. In addition, these cells do not export calcein, substrate of multidrug resistance associated protein (MRP). Thus, transport property of MXR is distinct from P-gp and MRP.
(4) Membrane vesicles prepared from MCF-7 AdVp3000 cells showed ATP-dependent 3H-leukotriene C4 (LTC4) transport. This transport was inhibited by novobiocin, MXR antagonist, but not inhibited by GS-platinum. 3H-estradiol-17-β-D glucuronide, substrate of MRP, transport was not observed. These data may indicate that MXR is one of glutathione S-conjugate export pumps distinct from MRP and GS-X pump expressed in CDDP resistant cells.
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