Adrenal precursor C19 steroids are potent stimulators of growth of androgen-sensitive mouse mammary carcinoma Shionogi cells in vitro

Molecular Specificity of 5-Androstenediol as a Systemic Radioprotectant in Mice

We compared in vivo radioprotective efficacy of 5-androstenediol (5-AED) to that of ten other steroids: 17alpha-androstenediol, dehydroepiandrosterone, 5-androstenetriol (AET), 4-androstenedione (AND), testosterone, estradiol, fluasterone, 16alpha-bromoepiandrosterone, 16alpha-fluoro-androst-5-en-17alpha-ol (alpha-fluorohydrin, AFH), and 16alpha-fluoro-androst-5-en-17beta-ol (beta-fluorohydrin). Steroids were administered 24 or 48 hr before, or 1 hr after, whole-body gamma-irradiation. Two days after irradiation at 3 Gy, blood elements were counted. In addition, after irradiation at 9-12.5 Gy, survival was recorded for 30 days. The results showed radioprotective efficacy was specific for 5-AED. One other steroid, AFH, demonstrated appreciable survival effects but was less efficacious than 5-AED. AND and AET produced slight enhancement of survival in some experiments. This is the first demonstration that the prophylactic window for survival enhancement by 1 subcutaneous (s.c.) injection of 5-AED is as long as 48 hr in mice. Moreover, the results indicate that 1 s.c. injection of 5-AED 1 hr after irradiation is much less effective than 1 injection 24-48 hr before irradiation. Comparing the molecular features of steroids with radioprotective efficacy leads to the following conclusions: 1) these effects are due to interaction with specific receptors, since s.c. injection of extremely similar molecules with the same physicochemical properties as 5-AED were not radioprotective; 2) the 17-hydroxyl group is essential; 3) this group must be in the beta configuration in the absence of nearby side groups; 4) a halogen atom at 16 changes the 17-hydroxyl specificity to alpha; 5) the 3beta-hydroxyl group is not essential; 6) addition of a 7beta-hydroxyl group is deleterious; and 7) the effects are not due to activation of sex steroid receptors.

Secondary Hormonal Manipulations in Prostate Cancer

Targeting AIPC with therapies that affect the mechanisms of androgen receptor signaling despite a castrate testosterone milieu is an active and growing area of clinical research. At present, for patients with AIPC, the data support the maintenance of the castrate state, recognition of the AAWD phenomenon,the sequential use of oral antiandrogens, and a trial of estrogens or adrenal androgen-targeted therapies. Novel agents are being developed that seek to prolong the duration of clinical responses and the overall response rate.

Secondary hormonal manipulations in prostate cancer

Virtually all patients treated with androgen deprivation eventually develop progressive clinical or biochemical disease despite this therapy. Despite low levels of androgen, the androgen receptor remains active, making secondary hormonal therapies a reasonable clinical approach. Considerations for such patients include antiandrogen withdrawal, sequential use of antiandrogens, adrenal cortex inhibitors, and estrogenic compounds. Collectively, the modest activity of these therapies challenges the notion that advancing prostate cancer will uniformly become "hormone refractory."

Comparative effects of DHEA vs. testosterone, dihydrotestosterone, and estradiol on proliferation and gene expression in human LNCaP prostate cancer cells

Serum levels of the adrenal androgen dehydroepiandrosterone (DHEA) peak in men and women in the third decade of life and decrease progressively with age. Increasing numbers of middle-aged and older individuals consume over-the-counter preparations of DHEA, hoping it will retard aging by increasing muscle and bone mass and strength, decreasing fat, and improving immunologic and neurobehavioral functions. Because DHEA can serve as a precursor to more potent androgens and estrogens, like testosterone (T), dihydrotestosterone (DHT), and 17beta-estradiol (E2), supplemental DHEA use may pose a cancer risk in patients with nascent or occult prostate cancer. The steroid-responsive human LNCaP prostate cancer cells, containing a functional but mutated androgen receptor (AR), were used to compare effects of DHEA with those of T, DHT, and E2 on cell proliferation and protein and/or gene expression of AR, prostate-specific antigen (PSA), IGF-I, IGF-I receptor (IGF-IR), IGF-II, IGF-binding proteins-2, -3, and -5, (IGFBPs-2, -3, and -5), and estrogen receptor-beta (ERbeta). Cell proliferation assays revealed significant stimulation by all four steroids. DHEA- and E2-induced responses were similar but delayed and reduced compared with that of T and DHT. All four hormones increased gene and/or protein expression of PSA, IGF-IR, IGF-I, and IGFBP-2 and decreased that of AR, ERbeta, IGF-II, and IGFBP-3. There were no significant effects of hormone treatment on IGFBP-5 mRNA. DHEA and E2 responses were similar, and distinct from those of DHT and T, in time- and dose-dependent studies. Further studies of the mechanisms of DHEA effects on prostate cancer epithelial cells of varying AR status, as well as on prostate stromal cells, will be required to discern the implications of DHEA supplementation on prostatic health.

Binding characteristics of [3H]delta(5)-androstene-3beta,17beta-diol to a nuclear protein in the rabbit vagina

In this study, we investigated the binding characteristics of [3H]Delta(5)-androstene-3beta,17beta-diol to rabbit vaginal cytosolic and nuclear extracts and in freshly excised intact tissue strips. [3H]delta(5)-Androstene-3beta,17beta-diol bound to a protein(s) in the vaginal nuclear extract with high affinity (K(d)=3-5 nM) and limited capacity (50-100 fmol/mg protein). No specific binding was detected in the cytoplasmic extracts. Competitive binding studies showed that binding of [3H]delta(5)-androstene-3beta,17beta-diol was effectively displaced with unlabeled delta(5)-androstene-3beta,17beta-diol but not with dehydroepiandrosterone, testosterone, dihydrotestosterone, triamcinolone acetonide, or progesterone. However, estradiol at high concentrations partially displaced bound [3H]delta(5)-androstene-3beta,17beta-diol. Incubation of freshly excised vaginal tissue strips with [3H]delta(5)-androstene-3beta,17beta-diol in the absence or presence of excess unlabeled delta(5)-androstene-3beta,17beta-diol for 1h at 37 degrees C resulted in specific binding to a soluble macromolecule in the nuclear KCl extracts. In addition, quantitative measurement of estrogen receptor, androgen receptor and delta(5)-androstene-3beta,17beta-diol binding protein was performed by equilibrium ligand binding assays using extracts of distal vaginal tissue from intact animals or ovariectomized animals treated for 2 weeks with vehicle, estradiol, testosterone, or estradiol plus testosterone. These changes in steroid hormone levels resulted in opposing trends between the estrogen receptor and delta(5)-androstene-3beta,17beta-diol binding protein, suggesting that delta(5)-androstene-3beta,17beta-diol binding protein is regulated differently by the hormonal milieu than the estrogen receptor. These data suggest that rabbit vaginal tissue expresses a novel binding protein which specifically binds delta(5)-androstene-3beta,17beta-diol and is distinct from the androgen and estrogen receptors.

Differential androgen sensitivity is associated with clonal heterogeneity in steroid metabolism, ornithine decarboxylase regulation and IL-1alpha action in mouse mammary tumor cells

Upon androgen deprivation, Shionogi (SC-115) mouse mammary tumors undergo phenotypic changes enabling their escape from growth dependence on androgens. Even within androgen-responsive cell populations, marked clonal heterogeneity is observed in the trophic effects of androgens. The present study compares several parameters of androgen action between three SC-115 cell clonal subpopulations exhibiting high (clone 107), low (clone S1A2) and no trophic response (clone 415) to androgens. These parameters pertain to (1) kinetics of androgen binding, (2) metabolism of 5alpha-dihydrotestosterone (DHT), 5alpha-androstane-3alpha,17beta-diol (3alpha-diol) and 5alpha-androstane-3beta,17beta-diol (3beta-diol), (3) ornithine decarboxylase (ODC) activity and (4) interleukin-1alpha (IL-1alpha) action on cell proliferation. Only marginal differences in the affinity and abundance of androgen-specific binding sites were detected between the three clones. While clone S1A2 degraded DHT to 3alpha-diol at a much faster rate than the highly androgen-sensitive 107 cells and androgen-insensitive 415 cells, differences in the rates of intracrine conversion of 3alpha-diol and 3beta-diol to DHT did not correlate with the ability of these steroids to stimulate cell proliferation. Induction of ODC activity at the onset of exponential growth was strongly DHT-dependent in 107 cells, whereas this dependence was markedly attenuated in androgen-hyposensitive cells. Unexpectedly, DHT strongly repressed the marked ODC induction resulting from fresh medium addition in 415 cells which show no growth response to androgens. Low IL-1alpha concentrations were mitogenic in all three SC-115 clones. Whereas the mitogenic action of IL-1alpha was completely androgen-dependent in 107 cells, this dependence was relieved in S1A2 cells, which responded to DHT and IL-1alpha in an additive fashion. Thus, clonal heterogeneity in the pattern of steroid metabolism within Shionogi tumors cannot solely account for loss of androgen dependence, which may rather correlate with the constitutive activation of transduction pathways controlling the expression of growth-associated genes (e.g. ODC) by serum growth factors, including IL-1alpha.

Maintenance of androgen-, glucocorticoid- or estrogen-responsive growth in shionogi carcinoma 115 subline sustained in castrated mice with high dose of estrogen for 30 generations (3 years)

Shionogi carcinoma 115 (SC115), an androgen-dependent mouse mammary tumor, rapidly loses its androgen responsiveness after androgen withdrawal. The growth of this tumor can also be stimulated by high doses of estrogen or glucocorticoid. In the present study, the maintenance of hormone-responsive growth of SC115 tumors with a high dose of estrogen was examined in castrated male mice using an SC115 subline obtained by serial transplantations of SC115 tumors in estrogen-treated castrated mice for 3 years (30 generations) (subline E2). Seed tumors from both SC115 and subline E2 could rapidly grow in castrated mice given daily injections of testosterone propionate (TP), 17 beta-estradiol (E2), or dexamethasone (Dex) (100 micrograms/mouse/day) but not in those given vehicle alone. Although SC115 and subline-E2 tumors grown with TP or Dex showed temporary regression after steroid withdrawal, the tumors grown with E2 did not show such temporary regression. The TP-, E2-, or Dex-induced growth of subline-E2 tumors was almost the same as that of the original SC115 tumors. However, responsiveness to androgen, estrogen or glucocorticoid of both tumors disappeared within one passage in steroid-depleted castrated mice. The present findings demonstrate that the loss of responsiveness to androgen as well as to high doses of estrogen or glucocorticoid of SC115 tumors can be prevented in castrated mice not only with androgen but also with high doses of estrogen.

Growth stimulation by androgens, glucocorticoids or fibroblast growth factors and the blocking of the stimulated growth by antibody against basic fibroblast growth factor in protein-free culture of Shionogi carcinoma 115 cells

Shionogi carcinoma 115 (SC115) has been accepted for 20 years as an androgen-responsive mouse mammary tumor. We have established an androgen-dependent cloned cell line (SC-3) from a SC115 tumor. In a serum-free medium, testosterone (T) or fibroblast growth factors (FGFs) markedly stimulate the growth of SC-3 cells, and the T-induced growth was shown to be mediated through FGF-like peptide(s) in an autocrine mechanism. Since we used the serum-free culture including 0.1% bovine serum albumin (BSA), a partially serum-containing condition, putative roles of BSA- or serum-borne growth factors in growth stimulation of autocrine production of FGF-like peptide(s) could not be excluded. This paper reports findings performed in a protein-free medium including plating [Ham's F-12:MEM (1:1; v/v)]. In the protein-free culture, the growth of SC-3 cells was significantly stimulated by the addition of greater than or equal to 10(-10) M T (up to 20-fold), greater than or equal to 10(-7) M dexamethasone (Dex; up to 7-fold) or greater than or equal to 1 ng/ml basic (b) or acidic FGF (up to 10-fold); other various growth factors had no such effects. Furthermore, DNA synthesis of SC-3 cells induced by T, Dex or bFGF was similarly and markedly inhibited by bFGF neutralizing antibody IgG. Therefore, the present findings seem to demonstrate that androgens or high levels of glucocorticoids induce the production and secretion of FGF-like peptide(s) from SC-3 cells for their growth even in the absence of additional support by other factors.