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Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni).

ABSTRACT: Steroid hormones are essential for the normal function of many organ systems in vertebrates. Reproductive activity in females and males, such as the differentiation, growth, and maintenance of the reproductive system, requires signaling by the sex steroids. Although extensively studied in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens, androgens, and progestins) action are poorly understood in reptiles. Here we evaluate hormone receptor ligand interactions in a freshwater turtle, the red-belly slider (Pseudemys nelsoni), after the isolation of cDNAs encoding an estrogen receptor alpha (ERalpha), an androgen receptor (AR), and a progesterone receptor (PR). The full-length red-belly slider turtle (t)ERalpha, tAR, and tPR cDNAs were obtained using 5' and 3' rapid amplification cDNA ends. The deduced amino acid sequences showed high identity to the chicken orthologs (tERalpha, 90%; tAR, 71%; tPR, 71%). Using transient transfection assays of mammalian cells, tERalpha protein displayed estrogen-dependent activation of transcription from an estrogen-responsive element-containing promoter. The other receptor proteins, tAR and tPR, also displayed androgen- or progestin-dependent activation of transcription from androgen- and progestin-responsive murine mammary tumor virus promoters. We further examined the transactivation of tERalpha, tAR and tPR by ligands using a modified GAL4-transactivation system. We found that the GAL4-transactivation system was not suitable for the measurement of tAR and tPR transactivations. This is the first report of the full coding regions of a reptilian AR and PR and the examination of their transactivation by steroid hormones.

SUBMITTER: Katsu Y

PROVIDER: S-EPMC2734501 | biostudies-literature | 2008 Jan

REPOSITORIES: biostudies-literature

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Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni).

Katsu Yoshinao Y Ichikawa Rie R Ikeuchi Toshitaka T Kohno Satomi S Guillette Louis J LJ Iguchi Taisen T

Endocrinology 20071004 1

Steroid hormones are essential for the normal function of many organ systems in vertebrates. Reproductive activity in females and males, such as the differentiation, growth, and maintenance of the reproductive system, requires signaling by the sex steroids. Although extensively studied in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens, androgens, and progestins) action are poorly understood in reptiles. Here we evaluate hormone re ...[more]

PMID: 17916628

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Project description:BackgroundAlthough estrogen (ERα/ERβ), progesterone (PGR), and androgen (AR) receptors are pathologically altered in colorectal cancer (CRC), their simultaneous expression within the same cohort of patients was not previously measured.MethodsERα/ERβ/PGR/AR proteins were measured in archived paired normal and malignant colon specimens (n =120 patients) by immunohistochemistry, and results were analyzed by gender, age (≤50 vs. ≥60 years), clinical stages (early-stage I/II vs. late-stage III/IV), and anatomical location (right; RSCs vs. left; LSCs). Effects of 17β-estradiol (E2), progesterone (P4), and testosterone alone or combined with the specific blockers of ERα (MPP dihydrochloride), ERβ (PHTPP), PGR (mifepristone), and AR (bicalutamide) on cell cycle and apoptosis were also measured in the SW480 male and HT29 female CRC cell lines.ResultsERα and AR proteins increased, whilst ERβ and PGR declined markedly in malignant specimens. Moreover, male neoplastic tissues showed highest AR expression, whilst ERβ and PGR weakest alongside ERα strongest expression was seen in cancerous tissues from women aged ≥60 years. Late-stage neoplasms also revealed maximal alterations in the expression of sex steroid receptors. By tumor location, LSCs disclosed significant elevations in ERα with marked declines in PGR compared with RSCs, and ERα strongest alongside PGR weakest expression was detected in advanced LSCs from women aged ≥60 years. Late-stage LSCs from females aged ≥60 years also showed weakest ERβ and strongest AR expression. In contrast, male RSC and LSC tissues exhibited equal ERβ and AR expression in all clinical stages. ERα and AR proteins also correlated positively, whereas ERβ and PGR inversely, with tumor characteristics. Concomitantly, E2 and P4 monotherapies triggered cell cycle arrest and apoptosis in the SW480 and HT29 cells, and while pre-treatment with ERα-blocker enhanced the effects of E2, ERβ-blocker and PGR-blocker suppressed the E2 and P4 anti-cancer actions, respectively. In contrast, treatment with the AR-blocker induced apoptosis, whilst co-treatment with testosterone hindered the effects.ConclusionsThis study advocates that protein expression of sex steroid receptors in malignant tissues could represent prognostic markers, as well as hormonal therapy could provide an alternative strategy against CRC, and their efficacies could be dependent on gender, clinical stage, and tumor location.

Dataset Information

Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni).

Publications

Molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (Pseudemys nelsoni).

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