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Effects of the ABCB1 (1199G > A) Polymorphism on Steroid Sex Hormone-Induced P-Glycoprotein Expression, ATPase Activity, and Hormone Efflux

This study examined how the 1199G > A polymorphism in the ABCB1 gene encoding P-glycoprotein (P-gp) affects the protein’s expression, ATPase activity, and ability to pump female steroid sex hormones out of LLC-PK1 cells. The ABCB1 (1199G) or ABCB1 (1199A) allele was transfected into cells, which...

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Detalles Bibliográficos
Autores principales: Peng, Rui, Zhang, Hong, Zhang, Ying, Wei, Dan-Yun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5635765/
https://www.ncbi.nlm.nih.gov/pubmed/29083397
http://dx.doi.org/10.3390/medsci3040124
Descripción
Sumario:This study examined how the 1199G > A polymorphism in the ABCB1 gene encoding P-glycoprotein (P-gp) affects the protein’s expression, ATPase activity, and ability to pump female steroid sex hormones out of LLC-PK1 cells. The ABCB1 (1199G) or ABCB1 (1199A) allele was transfected into cells, which were incubated for 48 h with various hormone concentrations, then analyzed by Western blotting to examine expression of P-gp protein and by reverse transcription-polymerase chain reaction (RT-PCR) to examine expression of mRNA. Cells were also compared in terms of their transepithelial permeability to steroid sex hormones in the presence and absence of the specific P-gp inhibitor GF120918. P-gp ATPase activity induced by steroid sex hormones was also assayed. Estriol and ethynyl estradiol up-regulated levels of ABCB1 mRNA in a concentration-dependent manner, with ABCB1 (1199A) mRNA showing greater up-regulation than ABCB1 (1199G) mRNA. Estrone, estriol, and ethynyl estradiol were substrates of both types of P-gp in transepithelial permeability assays, and the ABCB1 (1199A) protein showed a significantly higher net efflux ratio for estrone (13.4 vs. 7.4, p < 0.005), estriol (5.6 vs. 3.3, p < 0.05), and ethynyl estradiol (12.7 vs. 5.3, p < 0.005). Induction of P-gp ATPase activity by ethynyl estradiol and progesterone increased with increasing hormone concentration, and the magnitude of stimulation was greater for ABCB1 (1199A) P-gp than for ABCB1 (1199G) P-gp. These results indicate that the ABCB1 (1199G > A) polymorphism influences steroid sex hormone-induced expression and function of P-gp, which may help to explain inter-patient differences in P-gp-mediated chemotherapy resistance in vivo.