Identification of steroid sulfate transport processes in the human mammary gland.
J Clin Endocrinol Metab
; 88(8): 3902-12, 2003 Aug.
Article
en En
| MEDLINE
| ID: mdl-12915686
Circulating hormones and local biotransformation of steroid precursors are both sources of estrogen in human mammary tissue. Estrone-3-sulfate (E(1)S) is an important estrogenic form in premenopausal women, and dehydroepiandrosterone sulfate (DHEAS) constitutes a major adrenal precursor. Membrane transport systems that govern delivery of these anionic steroid conjugates to the mammary gland were investigated. RNA was screened by RT-PCR and Northern blotting for expression of organic anion transporting polypeptide (OATP) (solute carrier family 21A) and organic anion transporter (OAT) (solute carrier family 22A) gene families. OATP-B (SLC21A9) was the major carrier expressed; OATP-D (SLC21A11) and OATP-E (SLC21A12) were less abundant. In normal sections, OATP-B immunolocalized to the myoepithelium that surrounds the ductal epithelial cells. In invasive carcinoma, ductal epithelial cells were positive. OATP-B was characterized in stable transfected Chinese hamster ovary cells. E(1)S affinity constant (K(m)) [K(m) = 5 micro mol/liter, maximum velocity (V(max)) V(max) = 777 pmol/mg.min] and DHEAS (K(m) = 9 micro mol/liter, V(max) = 85 pmol/mg.min) were substrates. The prostaglandins (PG) A(1) and PGA(2) stimulated uptake of E(1)S and DHEAS by increasing V(max) 2-fold but not changing K(m). The effect of PGA was selectively blocked by the lipophilic thiol reagent N-ethylmaleimide but not by the hydrophilic acetamido-4'(iodoacetyl)aminostilbene-2,2'-disulfonic acid, suggesting an interaction between the electrophilic cyclopentenone ring and specific cysteine residues of OATP-B.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Esteroides
/
Mama
/
Estrona
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
/
Female
/
Humans
Idioma:
En
Revista:
J Clin Endocrinol Metab
Año:
2003
Tipo del documento:
Article
País de afiliación:
Suiza
Pais de publicación:
Estados Unidos