C19-steroids as androgen receptor modulators: design, discovery, and structure-activity relationship of new steroidal androgen receptor antagonists.

Dehydroepiandrosterone (DHEA), the most abundant steroid in human circulating blood, is metabolized to sex hormones and other C19-steroids. Our previous collaborative study demonstrated that androst-5-ene-3beta,17beta-diol (Adiol) and androst-4-ene-3,17-dione (Adione), metabolites of DHEA, can activate androgen receptor (AR) target genes. Adiol is maintained at a high concentration in prostate cancer tissue; even after androgen deprivation therapy and its androgen activity is not inhibited by the antiandrogens currently used to treat prostate cancer patients. We have synthesized possible metabolites of DHEA and several synthetic analogues and evaluated their role in androgen receptor transactivation to identify AR modulators. Steroids with low androgenic potential in PC-3 cell lines were evaluated for anti-dihydrotestosterone (DHT) and anti-Adiol activity. We discovered three potent antiandrogens: 3beta-acetoxyandrosta-1,5-diene-17-one 17-ethylene ketal (ADEK), androsta-1,4-diene-3,17-dione 17-ethylene ketal (OAK), and 3beta-hydroxyandrosta-5,16-diene (HAD) that antagonized the effects of DHT as well as of Adiol on the growth of LNCaP cells and on the expression of prostate-specific antigen (PSA). In vivo tests of these compounds will reveal their potential as potent antiandrogens for the treatment of prostate cancer.

Mitotic and neurogenic effects of dehydroepiandrosterone (DHEA) on human neural stem cell cultures derived from the fetal cortex.

Dehydroepiandrosterone (DHEA) is a neurosteroid with potential effects on neurogenesis and neuronal survival in humans. However, most studies on DHEA have been performed in rodents, and there is little direct evidence for biological effects on the human nervous system. Furthermore, the mechanism of its action is unknown. Here, we show that DHEA significantly increased the growth rates of human neural stem cells derived from the fetal cortex and grown with both epidermal growth factor (EGF) and leukemia inhibitory factor (LIF). However, it had no effect on cultures grown in either factor alone, suggesting a specific action on the EGF/LIF-responsive cell. Precursors of DHEA such as pregnenolone or six of its major metabolites, had no significant effect on proliferation rates. DHEA did not alter the small number (<3%) of newly formed neuroblasts or the large number (>95%) of nestin-positive precursors. However, the number of glial fibrillary acidic protein-positive cells, its mRNA, and protein were significantly increased by DHEA. We found both N-methyl-d-aspartate and sigma 1 antagonists, but not GABA antagonists, could completely eliminate the effects of DHEA on stem cell proliferation. Finally we asked whether the EGF/LIF/DHEA-responsive stem cells had an increased potential for neurogenesis and found a 29% increase in neuronal production when compared to cultures grown in EGF/LIF alone. Together these data suggest that DHEA is involved in the maintenance and division of human neural stem cells. Given the wide availability of this neurosteroid, this finding has important implications for future use.

Molecular differences caused by differentiation of 3T3-L1 preadipocytes in the presence of either dehydroepiandrosterone (DHEA) or 7-oxo-DHEA.

The effects of dehydroepiandrosterone (DHEA) and 7-oxo-DHEA on the cell size, adiposity, and fatty acid composition of differentiating 3T3-L1 preadipocyte cells are correlated with stearoyl-CoA desaturase (SCD) expression (mRNA and protein levels) and enzyme activity. Fluorescence-activated cell sorting shows that preadipocyte cells treated with methylisobutylxanthine, dexamethasone, and insulin (MDI) plus DHEA comprise a population distribution of predominantly large cells with reduced adiposity. In contrast, cells treated with MDI plus 7-oxo-DHEA comprise a population distribution of almost equal proportions of small and large cells that have an adiposity equivalent to cells differentiated with MDI alone. The cells treated with MDI plus DHEA have significantly reduced levels of total fatty acid, mainly due to a dramatic reduction in the level of palmitoleic (Delta(9)-16:1) acid. The cells treated with MDI plus 7-oxo-DHEA have a significantly increased level of total fat, primarily due to increased levels of Delta(9)-16:1 and palmitic (16:0) acids. At the molecular level, the DHEA-treated cells contain lowered amounts of SCD1 mRNA and antibody-detectable desaturase protein, while 7-oxo-DHEA-treated cells contained elevated levels of SCD1 mRNA and protein. Inhibition of differentiation in DHEA-treated cells was also suggested by a reduction in the mRNA level of the adipogenic gene aP2. At the level of microsomal enzymatic activity, SCD activity was decreased in DHEA-treated cells while the SCD activity was increased in 7-oxo-DHEA-treated cells. The changes in mRNA levels and enzyme activity were concentration-dependent and appeared as early as day 3 of the differentiation protocol. The results show that DHEA and 7-oxo-DHEA have distinct modes of action with respect to the complex transcriptional cascade required for differentiation. Furthermore, differences in the insulin-stimulated uptake of 2-deoxyglucose and in the activity of carnitine palmitoyl transferase observed from either DHEA- or 7-oxo-DHEA-treated cells support the ability of DHEA to produce a thermogenic effect in differentiating preadipocytes, while 7-oxo-DHEA promotes differentiation without other changes typical of thermogenesis.