A T3587G germ-line mutation of the MDR1 gene encodes a nonfunctional P-glycoprotein

Kazuyoshi Mutoh, Junko Mitsuhashi, Yasuhisa Kimura, Satomi Tsukahara, Etsuko Ishikawa, Kimie Sai, Shogo Ozawa, Jun Ichi Sawada, Kazumitsu Ueda, Kazuhiro Katayama, Yoshikazu Sugimoto

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The human multidrug resistance gene 1 (MDR1) encodes a plasma membrane P-glycoprotein (P-gp) that functions as an efflux pump for various structurally unrelated anticancer agents. We have identified two nonsynonymous germ-line mutations of the MDR1 gene, C3583T MDR1 and T3587G MDR1, in peripheral blood cell samples from Japanese cancer patients. Two patients carried the C3583T MDR1 allele that encodes H1195Y P-gp, whereas a further two carried T3587G MDR1 that encodes 11196S P-gp. Murine NIH3T3 cells were transfected with pCAL-MDR-IRES-ZEO constructs carrying either wild-type (WT), C3583T, or T3587G MDR1 cDNA and selected with zeocin. The resulting zeocin-resistant mixed populations of transfected cells were designated as 3T3/WT, 3T3/H1195Y, and 3T3/I1196S, respectively. The cell surface expression of I1196S P-gp in 3T3/I1196S cells could not be detected by fluorescence-activated cell sorting, although low expression of 11196S P-gp was found by Western blotting. H1195Y P-gp expression levels in 3T3/H1195Y cells were slightly lower than the corresponding WT P-gp levels in 3T3/WT cells. By immunoblotting analysis, both WT P-gp and H1195Y P-gp were detectable as a 145-kDa protein, whereas I1196S P-gp was visualized as a 140-kDa protein. 3T3/I1196S cells did not show any drug resistance unlike 3T3/H1195Y cells. Moreover, a vanadate-trap assay showed that the I1196S P-gp species lacks ATP-binding activity. Taken together, we conclude from these data that T3587G MDR1 expresses a nonfunctional P-gp and this is therefore the first description of such a germ-line mutation. We contend that the T3587G MDR1 mutation may affect the pharmacokinetics of MDR1-related anticancer agents in patients carrying this allele.

Original languageEnglish
Pages (from-to)877-884
Number of pages8
JournalMolecular cancer therapeutics
Volume5
Issue number4
DOIs
Publication statusPublished - 2006 Apr 1

    Fingerprint

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Mutoh, K., Mitsuhashi, J., Kimura, Y., Tsukahara, S., Ishikawa, E., Sai, K., Ozawa, S., Sawada, J. I., Ueda, K., Katayama, K., & Sugimoto, Y. (2006). A T3587G germ-line mutation of the MDR1 gene encodes a nonfunctional P-glycoprotein. Molecular cancer therapeutics, 5(4), 877-884. https://doi.org/10.1158/1535-7163.MCT-05-0240