Sterol transport by the human breast cancer resistance protein (ABCG2) expressed in Lactococcus lactis.
The human breast cancer resistance protein (BCRP, also know as ABCG2, MXR, or ABCP) is one of the more recently discovered ATP-binding cassette (ABC) transporters that confer resistance on cancer cells by mediating multidrug efflux. In the present study, we have obtained functional expression of human BCRP in the Gram-positive bacterium Lactococcus lactis. BCRP expression conferred multidrug resistance on the lactococcal cells, which was based on ATP-dependent drug extrusion. BCRP-mediated ATPase and drug transport activities were inhibited by the BCRP-specific modulator fumitremorgin C. To our knowledge these data represent the first example of the functional expression of a mammalian ABC half-transporter in bacteria. Although members of the ABCG subfamily (such as ABCG1 and ABCG5/8) have been implicated in the transport of sterols, such a role has not yet been established for BCRP. Interestingly, the BCRP-associated ATPase activity in L. lactis was significantly stimulated by (i) sterols including cholesterol and estradiol, (ii) natural steroids such as progesterone and testosterone, and (iii) the anti-estrogen anticancer drug tamoxifen. In addition, BCRP mediated the efflux of [3H]estradiol from lactococcal cells. Our findings suggest that BCRP may play a role in the transport of sterols in human, in addition to its ability to transport multiple drugs and toxins.
Janvilisri
Tavan
T
Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
Venter
Henrietta
H
Shahi
Sanjay
S
Reuter
Galya
G
Balakrishnan
Lekshmy
L
van Veen
Hendrik W
HW
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D018931:Antineoplastic Agents, Hormonal / Q000493:pharmacokinetics; D002784:Cholesterol / Q000493:pharmacokinetics; D004958:Estradiol / Q000493:pharmacokinetics; D015870:Gene Expression; D006801:Humans; D013294:Lactococcus lactis / Q000235:genetics; D009363:Neoplasm Proteins; D011374:Progesterone / Q000493:pharmacokinetics; D013261:Sterols / Q000493:pharmacokinetics*; D013629:Tamoxifen / Q000493:pharmacokinetics; D013739:Testosterone / Q000493:pharmacokinetics; D014316:Tritium
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D018931:Antineoplastic Agents, Hormonal; D009363:Neoplasm Proteins; D013261:Sterols; D013629:Tamoxifen; D014316:Tritium; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D002784:Cholesterol