Androgen-induced proliferative quiescence in prostate cancer cells: The role of AS3 as its mediator

In the prostate gland of adult mammals, most epithelial cells are in a state of proliferative quiescence. Androgens regulate this effect by inducing cell cycle arrest in the G0/G1 phase. Potential mediators of this androgen-induced proliferative shutoff were identified by means of subtracted cDNA libraries. The expression pattern of one of these sequences, AS3, strongly correlated with the expression of the androgen-induced proliferative shutoff both temporally and dosewise. The AS3 gene is located on chromosome 13 q12.3, in close proximity to the BRCA2 gene. The loss of chromosomal regions where AS3 alleles are located correlates with various human cancers, including prostate. The biological effect of AS3 was tested in two stable cell lines, one expressing sense and another expressing antisense AS3 constructs, both under tetracycline regulation. S9 cells were obtained by retroviral infection with virions containing a tetracycline-regulated sense AS3 construct. In these cells, sense AS3 was negatively regulated by tetracycline. Tetracycline withdrawal increased the expression of AS3 mRNA and protein. The expression of tetracycline-regulated AS3 resulted in inhibition of cell proliferation. A4 cells were obtained by retroviral infection with virions containing a tetracycline-regulated antisense AS3 construct. Vector-driven expression of antisense-AS3 blocked the induction of androgen-induced endogenous AS3 mRNA and blocked the inhibitory effect of androgens on cell proliferation. Tetracycline-regulated expression of the empty vector control had no effect on cell proliferation. These experiments strongly suggest that AS3 is a mediator of the androgen-induced proliferative shutoff.

Endothelial cell death, angiogenesis, and microvascular function after castration in an androgen-dependent tumor: Role of vascular endothelial growth factor

The sequence of events that leads to tumor vessel regression and the functional characteristics of these vessels during hormone–ablation therapy are not known. This is because of the lack of an appropriate animal model and monitoring technology. By using in vivo microscopy and in situ molecular analysis of the androgen-dependent Shionogi carcinoma grown in severe combined immunodeficient mice, we show that castration of these mice leads to tumor regression and a concomitant decrease in vascular endothelial growth factor (VEGF) expression. Androgen withdrawal is known to induce apoptosis in Shionogi tumor cells. Surprisingly, tumor endothelial cells begin to undergo apoptosis before neoplastic cells, and rarefaction of tumor vessels precedes the decrease in tumor size. The regressing vessels begin to exhibit normal phenotype, i.e., lower diameter, tortuosity, vascular permeability, and leukocyte adhesion. Two weeks after castration, a second wave of angiogenesis and tumor growth begins with a concomitant increase in VEGF expression. Because human tumors often relapse following hormone–ablation therapy, our data suggest that these patients may benefit from combined anti-VEGF therapy.

Estrogen receptor-dependent sexual differentiation of dopaminergic neurons in the preoptic region of the mouse

Although it has been known for some time that estrogen exerts a profound influence on brain development a definitive demonstration of the role of the classical estrogen receptor (ERα) in sexual differentiation has remained elusive. In the present study we used a sexually dimorphic population of dopaminergic neurons in the anteroventral periventricular nucleus of the hypothalamus (AVPV) to test the dependence of sexual differentiation on a functional ERα by comparing the number of tyrosine hydroxylase (TH)-immunoreactive neurons in the AVPV of wild-type (WT) mice with that of mice in which the ERα had been disrupted by homologous recombination (ERKOα). Only a few ERα-immunoreactive neurons were detected in the AVPV of ERKOα mice, and the number of TH-immunoreactive neurons was three times that of WT mice, suggesting that disruption of the ERα gene feminized the number of TH-immunoreactive neurons. In contrast, the AVPV contains the same number of TH-immunoreactive neurons in testicular feminized male mice as in WT males, indicating that sexual differentiation of this population of neurons is not dependent on an intact androgen receptor. The number of TH-immunoreactive neurons in the AVPV of female ERKOα mice remained higher than that of WT males, but TH staining appeared to be lower than that of WT females. Thus, the sexual differentiation of dopamine neurons in the AVPV appears to be receptor specific and dependent on the perinatal steroid environment.

Numbers of deaths related to intrapartum asphyxia and timing of birth in all Wales perinatal survey, 1993-5

Objectives: To investigate the relation between the timing of birth and the occurrence of death related to an intrapartum event.

Perinatal death associated with planned home birth in Australia: population based study

Objective: To assess the risk of perinatal death in planned home births in Australia.

From transforming growth factor-β signaling to androgen action: Identification of Smad3 as an androgen receptor coregulator in prostate cancer cells

Although transforming growth factor-β (TGF-β) has been identified to mainly inhibit cell growth, the correlation of elevated TGF-β with increasing serum prostate-specific antigen (PSA) levels in metastatic stages of prostate cancer has also been well documented. The molecular mechanism for these two contrasting effects of TGF-β, however, remains unclear. Here we report that Smad3, a downstream mediator of the TGF-β signaling pathway, functions as a coregulator to enhance androgen receptor (AR)-mediated transactivation. Compared with the wild-type AR, Smad3 acts as a strong coregulator in the presence of 1 nM 5α-dihydrotestosterone, 10 nM 17β-estradiol, or 1 μM hydroxyflutamide for the LNCaP mutant AR (mtAR T877A), found in many prostate tumor patients. We further showed that endogenous PSA expression in LNCaP cells can be induced by 5α-dihydrotestosterone, and the addition of the Smad3 further induces PSA expression. Together, our findings establish Smad3 as an important coregulator for the androgen-signaling pathway and provide a possible explanation for the positive role of TGF-β in androgen-promoted prostate cancer growth.

Hyposecretion of the adrenal androgen dehydroepiandrosterone sulfate and its relation to clinical variables in inflammatory arthritis

Hypothalamic–pituitary–adrenal underactivity has been reported in rheumatoid arthritis (RA). This phenomenon has implications with regard to the pathogenesis and treatment of the disease. The present study was designed to evaluate the secretion of the adrenal androgen dehydroepiandrosterone sulfate (DHEAS) and its relation to clinical variables in RA, spondyloarthropathy (Spa), and undifferentiated inflammatory arthritis (UIA). Eighty-seven patients (38 with RA, 29 with Spa, and 20 with UIA) were studied, of whom 54 were women. Only 12 patients (14%) had taken glucocorticoids previously. Age-matched, healthy women (134) and men (149) served as controls. Fasting blood samples were taken for determination of the erythrocyte sedimentation rate (ESR), serum DHEAS and insulin, and plasma glucose. Insulin resistance was estimated by the homeostasis-model assessment (HOMAIR). DHEAS concentrations were significantly decreased in both women and men with inflammatory arthritis (IA) (P < 0.001). In 24 patients (28%), DHEAS levels were below the lower extreme ranges found for controls. Multiple intergroup comparisons revealed similarly decreased concentrations in each disease subset in both women and men. After the ESR, previous glucocorticoid usage, current treatment with nonsteroidal anti-inflammatory drugs, duration of disease and HOMAIR were controlled for, the differences in DHEAS levels between patients and controls were markedly attenuated in women (P = 0.050) and were no longer present in men (P = 0.133). We concluded that low DHEAS concentrations are commonly encountered in IA and, in women, this may not be fully explainable by disease-related parameters. The role of hypoadrenalism in the pathophysiology of IA deserves further elucidation. DHEA replacement may be indicated in many patients with IA, even in those not taking glucocorticoids.

Crystallographic structures of the ligand-binding domains of the androgen receptor and its T877A mutant complexed with the natural agonist dihydrotestosterone

The structures of the ligand-binding domains (LBD) of the wild-type androgen receptor (AR) and the T877A mutant corresponding to that in LNCaP cells, both bound to dihydrotestosterone, have been refined at 2.0 Å resolution. In contrast to the homodimer seen in the retinoid-X receptor and estrogen receptor LBD structures, the AR LBD is monomeric, possibly because of the extended C terminus of AR, which lies in a groove at the dimerization interface. Binding of the natural ligand dihydrotestosterone by the mutant LBD involves interactions with the same residues as in the wild-type receptor, with the exception of the side chain of threonine 877, which is an alanine residue in the mutant. This structural difference in the binding pocket can explain the ability of the mutant AR found in LNCaP cells (T877A) to accommodate progesterone and other ligands that the wild-type receptor cannot.