Progesterone receptor (PR) isoforms PRA and PRB differentially regulate expression of the breast cancer resistance protein in human placental choriocarcinoma BeWo cells.
Breast cancer resistance protein (BCRP) plays a significant role in drug disposition and in conferring multidrug resistance in cancer cells. Previous studies have shown that steroid hormones such as 17beta-estradiol and progesterone can affect BCRP expression in cancer cells. In this study, we investigated the molecular mechanism by which BCRP expression in human placental choriocarcinoma BeWo cells is regulated by progesterone. Transfection of the progesterone receptor (PR) isoforms PRA and PRB resulted in a similarly increased expression of PRA and PRB, respectively. However, progesterone significantly increased BCRP expression and activity only in PRB-transfected cells. This stimulatory effect of progesterone was abrogated by the PR antagonist mifepristone (RU-486). Consistently, transcriptional activity of the BCRP promoter was induced 2- to 6-fold by 10(-8) to 10(-5) M progesterone in PRB-transfected cells. Progesterone had little effect on BCRP expression and activity and transcriptional activity of the BCRP promoter in PRA-transfected cells; however, cotransfection of PRA and PRB significantly decreased the progesterone-response compared with that in cells transfected with only PRB. Mutations in a novel progesterone response element (PRE) identified between -243 to -115 bp of the BCRP promoter region significantly attenuated the progesterone-response in PRB-transfected cells, and deletion of the PRE nearly completely abrogated the progesterone effect. Specific binding of both PRA and PRB to the BCRP promoter through the identified PRE was confirmed using the electrophoretic mobility shift assay. Collectively, progesterone induces BCRP expression in BeWo cells via PRB but not PRA. PRA represses the PRB activity. Thus, PRA and PRB differentially regulate BCRP expression in BeWo cells.
Wang
Honggang
H
Department of Pharmaceutics, School of Pharmacy, Box 357610, University of Washington, Seattle, WA 98195-7610, USA.
Lee
Eun-Woo
EW
Zhou
Lin
L
Leung
Peter C K
PC
Ross
Douglas D
DD
Unadkat
Jashvant D
JD
Mao
Qingcheng
Q
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002822:Choriocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D015735:Mifepristone / Q000032:analysis / Q000494:pharmacology; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D010920:Placenta / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011247:Pregnancy; D011374:Progesterone / Q000032:analysis / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D013223:Statistics as Topic; D014158:Transcription, Genetic; D014162:Transfection; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D011980:Receptors, Progesterone; C101118:progesterone receptor A; C097314:progesterone receptor B; D015735:Mifepristone; D011374:Progesterone; D008156:Luciferases