The metabolism of testosterone and dihydrotestosterone in an androgen-dependent tumour. A possible correlation between dihydrotestosterone and tumour growth in vivo

Inhibition of type 2 17beta-hydroxysteroid dehydrogenase by estradiol derivatives bearing a lactone on the D-ring: structure-activity relationships

The peripheral conversion of steroid precursors into biologically active forms can be a major source of steroid synthesis, and these steroids support the growth of hormone-dependent diseases. The 17beta-hydroxysteroid dehydrogenase (17beta-HSD) enzyme family is involved in the biosynthesis of active steroids and its inhibition constitutes an interesting approach for treating estrogen- and androgen-dependent cancers. We previously found that a compound formed by the introduction of a spiro-gamma-lactone at position 17 of estradiol (E2) produces a significant inhibition of type 2 17beta-HSD. To optimize the inhibitory potency of such compounds, we synthesized a series of estradiol derivatives bearing a lactone on the D-ring and tested their ability to inhibit the type 2 17beta-HSD transformation of 4-androstenedione into testosterone. The results of our structure-activity relationship study determined the importance of the 17beta-orientation of the oxygen atom. Indeed, the 17beta-O-isomer of spiro-gamma-lactone-E2 is a much more potent inhibitor than the 17alpha-O-analog (respectively 85 and 9% of inhibition at 1 microM). The carbonyl function is essential since the percentage of inhibition shifts from 85 to 30%, 15, or 3%, when the carbonyl group is transformed into a hydroxyl, a methoxy or a methylene (cycloether) group, respectively. Our results lead us to realize the importance of the spirolactone versus the C17beta-O/C16beta lactone (respectively 32 and 2% of inhibition at 0.1 microM, for the same size of lactone ring). The optimal size for the spirolactone was also established to be six members. All the types of substituents (methyl, dimethyl, allyl, propyl, and methoxycarbonyl) that we added on the spiro-delta-lactone moiety decreased the inhibitory activity, suggesting steric restrictions for the space that can be occupied in proximity of the spiro-delta-lactone functionality. 17-(Spiro-delta-lactone)-E2, compound 6, was thus the most potent inhibitor of type 2 17beta-HSD with a K(i) value of 29 +/- 5 nM. This compound reversibly inhibits type 2 17beta-HSD in a non-competitive manner.

Use of neoadjuvant and adjuvant therapy to prevent or delay recurrence of prostate cancer in patients undergoing surgical treatment for prostate cancer

There have been improvements in the outcome of patients with clinically localized prostate cancer treated by radical prostatectomy. However, some patients treated with radical prostatectomy will have clinical or biochemical progression. These men are at increased risk of dying of their disease. Identification of patients with adverse features at the time of radical prostatectomy may permit the use of additional multimodality therapies to improve outcomes. Whether this additional multimodality therapy should be administered in the neoadjuvant or adjuvant setting remains controversial. Further, whether a patient at increased risk for progression after radical prostatectomy requires additional therapy before the development of documented progression remains controversial. This article reviews the potential multimodality approaches to prevent or delay recurrence of prostate cancer in patients undergoing surgical treatment for prostate cancer.

Therapeutic strategies for localized prostate cancer

Prostate-specific antigen determinations for prostate cancer screening have led to a dramatic increase in the number of men who are diagnosed with organ-confined and therefore potentially curable prostate cancer. Advances in predicting outcomes with artificial neural networks may help to recommend one therapy over another. Less invasive forms of treatment, such as high-intensity focused ultrasound, may ultimately give patients additional options for treatment. Furthermore, attempts to better define the role of both neoadjuvant hormonal therapy and chemotherapy may give higher-risk patients better outcomes than with current treatments. These advances as well as continued research will likely lead to a day when more and more men with organ-confined disease will be cured.

Growth factor involvement in progression of prostate cancer

Understanding how the regulation of growth factor pathways alters during prostate cancer (PC) progression may enable researchers to develop targeted therapeutic strategies for advanced disease. PC progression involves the shifting of cells from androgen-dependent growth to an androgen-independent state, sometimes with the loss or mutation of the androgen receptors in PC cells. Both autocrine and paracrine pathways are up-regulated in androgen-independent tumors and may replace androgens as primary growth stimulatory factors in cancer progression. Our discussion focuses on growth factor families that maintain homeostasis between epithelial and stromal cells in the normal prostate and that undergo changes as PC progresses, often making stromal cells redundant. These growth factors include fibroblast growth factor, insulin-like growth factors, epidermal growth factor, transforming growth factor α, retinoic acid, vitamin D3, and the transforming growth factor β families. We review their role in normal prostate development and in cancer progression, using evidence from clinical specimens and models of PC cell growth.

Role of testosterone in the induction of hepatic peroxisome proliferation by clofibrate

Hepatic peroxisome proliferation is induced by a number of agents, including clofibrate. Sustained proliferation of peroxisomes is associated with the development of hepatocellular carcinoma. In the present study, we have investigated the role of testosterone in peroxisome proliferation induced by clofibrate. Three groups of male rats (intact, castrated, and castrated replaced with testosterone) were studied. Proliferation of peroxisomes was induced by feeding clofibrate (0.25%, 0.50%, and 1.0% of diet) for 2 weeks. Peroxisome proliferation was monitored by measuring total peroxisomal beta-oxidation activity. In intact rats, the peroxisomal beta-oxidation activity (nmol/min/mg protein) increased in a dose-dependent manner and was 7.2 +/- 0.4, 52.6 +/- 7.5, 63.2 +/- 3.7, and 92.4 +/- 4.0 at clofibrate doses of 0%, 0.25%, 0.50%, and 1.0%, respectively. In contrast, in castrated rats, the total peroxisomal beta-oxidation activity was significantly (P < .01) lower at clofibrate levels of 0.25% and 0.50% (25.8 +/- 2.7 and 42.5 +/- 2.2, respectively), but not at the clofibrate level of 1.0% (85.0 +/- 6.3). Testosterone replacement of castrated rats restored the peroxisomal beta-oxidation activity. To determine whether the above results were related to the metabolism of clofibrate in the absence or presence of testosterone, we measured serum clofibrate levels. These levels were 50% lower in castrated rats than in intact rats or in testosterone-treated castrated rats. The activity of hepatic uridine diphosphate (UDP)-glucuronyltransferase, the enzyme catalyzing the glucuronidation of clofibrate, was measured using either bilirubin or 4-methylumbelliferone as substrates and was found to be unaffected by castration or testosterone treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intermittent androgen suppression on androgen-dependent tumors. Apoptosis and serum prostate-specific antigen

BACKGROUND

Since postcastration progression of tumors to an androgen-independent state appears to be linked to the cessation of androgen-induced differentiation of tumorigenic stem cells, the authors hypothesized that the replacement of androgens at the end of a period of apoptotic regression might result in the regeneration of differentiated tumor cells with further apoptotic potential.

METHODS AND RESULTS

To determine the effect of intermittent exposure of androgens on the androgen-dependent Shionogi carcinoma, the tumor was transplanted into a succession of male mice, each of which was castrated when the estimated tumor weight became about 3 g. After the tumor had regressed to 30% of the original weight, it was transplanted into the next noncastrated male. This cycle of transplantation and castration-induced apoptosis was repeated successfully four times before growth became androgen-independent during the fifth cycle. In four of Stage C and three of Stage D patients with prostate cancer, androgen withdrawal was initiated with cyproterone acetate (100 mg/d) and diethylstilbestrol (0.1 mg/d) and then maintained with cyproterone acetate in combination with the luteinizing hormone-releasing hormone agonist, goserelin acetate (3.6 mg/month). After 6 or more months of suppression of serum prostate-specific antigen (PSA) into the normal range, treatment was interrupted for 2 to 11 months. After recovery of testicular function, androgen-withdrawal therapy was resumed when serum PSA increased to a level of about 20 micrograms/l. This cycle was repeated sequentially to a total of two to four times over treatment periods of 21 to 47 months with no loss of androgen dependence.

CONCLUSIONS

These results demonstrate that intermittent androgen suppression can be used to induce multiple apoptotic regressions of a tumor; they also suggest that the cyclic effects of such treatment on prostate cancer can be followed by the sequential measurement of serum PSA levels.

Effects of antiandrogens on growth of androgen-dependent mouse mammary tumor (Shionogi carcinoma 115) in vivo and in vitro

Binding affinities of modified steroidal anthrasteroids, 3 beta-hydroxy-3a beta,6-dimethyl-2,3,3a,4,5,8,9,10,10a beta,11,11a beta, 11b alpha-dodecahydro-1H-cyclopenta[a]anthracene-8-one (1) and 3a beta,6-dimethyl-2,3,3a,4,5,8,9,10,10a beta,11,11a beta,11b alpha-dodecahydro-1H-cyclopenta[a]anthracene-3,8-dione (2), the steroid oxendolone and the nonsteroid AA560, for the androgen receptor (AR) of Shionogi carcinoma 115 (SC115) and their effects on the growth of SC115 were investigated in vivo and in vitro. The inhibitory effects of these compounds on testosterone 5 alpha-reductase of SC115 tissues were also measured. The relative binding affinities of these compounds were 3.17-0.03% of that of dihydrotestosterone, and their rank order was (1) greater than AA560 greater than oxendolone much greater than (2). In the presence of 10(-9) M testosterone, anthrasteroids and AA560 inhibited the growth of SC115 cells at 10(-7) M in a serum-free medium, but oxendolone did not. In the absence of testosterone, (1), (2) and oxendolone promoted cell growth at 10(-6), 10(-7) and 10(-7) M, respectively. However, AA560 nearly completely blocked cell growth at 10(-5) M. At a 2 mg daily dose for 13 days, (1) and AA560 powerfully inhibited tumor growth in castrated DS mice treated with testosterone propionate but oxendolone had almost no effect. Anthrasteroids and oxendolone showed weak but significant agonistic activity in vivo. Anthrasteroids markedly inhibited 5 alpha-reductase activity of SC115, oxendolone weakly and AA560 not at all. The remarkable antiandrogenic activities of (1) and AA560 may partially result from their higher affinities for the AR of SC115 but other yet unknown mechanisms may also contribute to these activities.

The effect of several sex steroid hormones on the growth rate of three Morris hepatoma tumor lines

Morris hepatoma 44, whose growth is sensitive to thyroid hormones and prolactin, contains specific receptors for these hormones. In the present experiments, male Buffalo rats bearing Morris hepatoma 7787 were studied to determine the effects of several sex steroid hormones. Castration 1 week postimplantation inhibited tumor growth relative to controls (-53%). Replacement with testosterone propionate (1 mg per day s.c. injection) restored tumor growth to control levels, whereas administration of testosterone (2 mg per day s.c. injection) to castrated controls resulted in significant stimulation. Testosterone administered to control animals at a dose of 1 mg per day stimulated tumor growth (62%), whereas 2 mg per day failed to do so. Progesterone (4-pregnon-3,20-dione) at doses of 125 or 250 micrograms per day (Silastic implants) had no effect on tumor growth, whereas 500 micrograms per day stimulated tumor growth relative to controls. Estrogen (17 beta-estradiol) at doses of 6, 12, or 24 micrograms per day (Silastic implants) did not influence tumor growth. Cytoplasmic testosterone receptors have been demonstrated in tumors (2.2 +/- 0.8 fmoles per mg cytoplasm), although specific cytoplasmic estrogen and progesterone receptors could not be identified in this model. In female rats bearing either Morris hepatoma 44, 7787 or 5123-D, testosterone markedly stimulated tumor growth (226, 328 and 58%, respectively, relative to controls). In conclusion, although Morris hepatoma 7787 appears to be androgen (testosterone) dependent and contains cytoplastic androgen receptors, it lacks specific cytoplasmic receptors for estrogen and progesterone and is not influenced by these hormones except at very high doses of progesterone.

An androgen-dependent pilosebaceous tumor spontaneously developed in the Japanese house musk shrew Suncus murinus

Following administration of [3H]testosterone to castrated male Japanese house musk shrews (Suncus murinus), radioactive metabolites were detected in sidegland nuclei and the major one of them was dihydrotestosterone (DHT). The androgen binding capacity of the cytoplasmic fraction of sideglands was measured in vitro by the use of [3H]R1881 as a ligand. The binding showed a high affinity for R1881 (Kd = 6.2 X 10(-10) M) and a low capacity (Bmax = 22 fmol/mg protein). Sucrose density gradient centrifugation brought about a peak of [3H]R1881 in the 7S region in low ionic strength buffer. Their characteristics as described above are consistent with those of other androgen target organs. A cutaneous pilosebaceous tumor, which spontaneously developed on the sidegland of old male S. murinus, was transplanted to nude athymic mice. It grew in males only and failed to grow in females and castrated males. A specific androgen binding was found in this tumor (Kd = 7.8 X 10(-10) M, Bmax = 100 fmol/mg protein). Therefore, this transplantable pilosebaceous tumor is androgen-dependent and can be utilized as a new suitable model in the study of the mechanism of androgen on tumor development.

Characterization of androgen uptake by purified nuclei from an androgen-dependent and two androgen-independent cell lines of the Shionogi mouse mammary carcinoma

Properties of androgen uptake by nuclei prepared from an androgen-dependent tumour cell line occurred after 2 h incubation at 20 degrees C; 2. Nuclei from three tumour cell lines displayed similar affinity for DHT but the two androgen-independent cell lines had less than one-quarter the number of uptake sites; 3. Loss of label from nuclei which had been pre-incubated with [3H]-DHT for 18 h at 20 degrees C was greater from the AD cell line nuclei than from the androgen-independent cell lines; 4. Whole cell contamination of the nuclear preparations did not contribute to specific DHT uptake.

Androgen glucuronides. I. Direct formation in rat accessory sex organs

A simple one-step procedure is described on the isolation of androgen glucuronides from various rat tissues. This procedure uses polyacrylamide gel electrophoresis, and permits a quantitative isolation of a single band containing the total androgen glucuronides without the contamination of free androgens and androgen sulfates. This procedure was used to determine the ability of various tissues of the rat to form androgen glucuronides directly when they were incubated with 1,2-[3H]-testosterone (0.1 micronm) in vitro. Of eleven organs studied, only the accessory sex organs (ventral prostate, seminal vesicle, and coagulating gland), liver, and kidney were capable of forming androgen glucuronides. At the end of a one-hour incubation period, approximately 1% of the total radiolabeled steroids in the prostatic tissue minces were in the form of glucuronide conjugates. The predominant androgen glucuronide formed in the accessory sex organs was 5 alpha -androstane-3 alpha, 17 beta-diol 17 beta-D-glucuronide. This is in contrast to the rat liver and kidney in which testosterone glucuronide was the predominant conjugate.

Development of methods for the quantitative in vitro analysis of androgen-dependent and autonomous Shionogi carcinoma 115 cells

Androgen-dependent and androgen-independent (autonomous), cloned, cultured cell lines of the androgen-dependent mouse mammary adenocarcinoma, Shionogi carcinoma 115, have been established. Growth of the dependent cells requires the presence of androgen, provided they are growth in suspension culture in medium containing dextran-charcoal-treated fetal calf serum. The growth rate of autonomous cells in the presence or absence of DHT is similar to that of dependent cells grown in its presence. An agar culture method has been developed that enables the proportion of dependent and autonomous cells in mixed populations to be determined. Autonomous cells appear in dependent clones, and their frequency increases with increasing time of subculture. Dependent cells form tumors preferentially in male animals and dependent cell cytosols contain significant amounts (approximately 300 femtomoles per mg protein) of a specific androgen-binding macromolecule. Autonomous cells formed tumors equally well in both male and female mice, and autonomous cell cytols contain very low levels (less than or equal to 7 femtomoles per mg protein) of the specific androgen-binding macromolecule(s). These studies delineate a system which can be used to investigate the mechanism of steroid hormone-dependent and autonomous tumor growth, and the transitions between the hormone-dependent and autonomous states.

Cloned mouse mammary cell lines requiring androgens for growth in culture

Clonally derived cell lines have been established from the mouse mammary tumor Shionogi carcinoma 115. Physiological concentrations of androgens markedly increase the growth rate and saturation density of these clones. The cells fail to grow in 1% fetal bovine serum-supplemented medium, but addition of 10-50 nM androstanolone or testosterone results in resumption of exponential growth. Some other androgens, but not estrogens or progesterone, stimulate growth of these cells. Steroid receptors can be isolated from the cells. In addition to their effect on growth, androgens also cause a marked alteration in the cell and colony morphology of the clones.

Ammonium sulfate precipitation as a tool for the study of androgen receptor proteins in rat prostate and mouse kidney

Ammonium sulfate precipitation has been used for the separation of bound and free steroids in rat prostate and mouse kidney cytosol equilibrated with tritiated androgens. A high affinity, low capacity binding protein has been identified in the 35% saturation precipitate. Biochemical and physiological data indicate that this protein is identical with the previously described 8-10 S androgen receptor. It has been demonstrated that this receptor protein binds 17 beta - hydroxy-5alpha-androstan-3-one (DHT) and testosterone in both tissues. The apparent dissociation constant (Kd) of the prostatic receptor for DHT and of the renal receptor for testosterone is 1-2 nM. The number of binding sites equals 57 and 23 fmoles/mg protein in prostate and kidney respectively. Dterminations of apparent inhibition constants (Ki) for 26 steroidal and non-steroidal compounds suggest that the binding sites in these tissues is similar or identical.

Studies on the regulation of the concentration of androgens and androgen receptors in nuclei of prostatic cells

Experiments were performed to assess the effect of intracellular androgen metabolism and the availability of cytoplasmic receptors on the concentration of androgens and androgen receptors in nuclei of prostatic cells. It was found that androgens are incorporated into the nucleus by a regulated, selective process which appears to limit the type and amount of androgen transported across the nuclear membrane. The metabolic conversion of testosterone to dihydrotestosterone which takes place in cytoplasm does not reduce transport and, very likely, affects only the ratio of testosterone and dihydrotestosterone transferred into the nucleus. In vivo, when the intranuclear concentration of androgens approaches 250 nM (8 pmol per mg DNA), an apparent concentration ceiling is reached even in the presence of a downward concentration gradient that would be expected to promote further transport across the nuclear membrane. This finding strongly suggests that in vivo the nuclear membrane acts as a barrier to the passage of androgens and, therefore, mitigates against the possibility that passive diffusion is an important mechanism of afferent transport of androgens into the nucleus. The ability of the nucleus to concentrate testosterone and dihydrotestosterone was clearly demonstrated in vivo when cytoplasmic concentrations of androgens of approximately 20 nM were accompanied by intranuclear concentrations in the vicinity of 250 nM. Since the measured concentration of testosterone and dihydrotestosterone in prostate of several species fall within the 5-20 nM range, it is evident that androgen concentrations in the nucleus as high as 250 nM may be typical of the physiological steady state. At the latter concentration the nucleus contains 60 000 androgen molecules: in approximate terms one third of this total is bound to a large molecular weight component of the nucleus, one third is bound to a 3.3 S receptor and one third is free or loosely bound. Since 60 000 androgen molecules and 20 000 receptor molecules appear in the nucleus before transport stops, it seems that the quantity of 4.4 S cytoplasmic receptor estimated at 174 plus or minus 24 pmol per mg protein (equivalent to about 8000 molecules per cell) is insufficient to account for the total influx of androgens and androgen receptors into the nucleus. Thus, although these results support the view that cytoplasmic receptors and the capacity to transport androgens are closely linked phenotypic markers of intracellular steroid hormone action, they suggest that the control of androgen concentration in the nucleus is achieved in a more intricate fashion than simply through a dependence on the presumed translocation of 4.4 S androgen-receptor complex into the nucleus.

Androgen receptors: relationship to growth response and to intracellular androgen transport in nine variant lines of the Shionogi mouse mammary carcinoma

Aspects of the biological significance of androgen receptors have been studied in nine variant lines of the Shionogi carcinoma, two of which are androgen dependent and seven of which are autonomous. The dependent lines, and two of the seven autonomous lines, contain androgen receptors; this finding demonstrates that the presence of receptors is not an accurate marker of hormonal dependence in vivo. Since the ability to transport androgens into the nucleus, as judged from the relative maximal rates of transport, is virtually restricted to dependent and autonomous lines which possess cytoplasmic receptors, it is clear that such receptors may play a role in regulating the intranuclear concentration of androgens. The absence of cytoplasmic receptors and the comparative lack of perceptible transfer of androgens across the nuclear membrane are features peculiar to the autonomous condition.

In vivo androgen retention in mouse kidney

The in vivo retention of 3-H-testosterone, dihydrotestosterone (DHT), 3alpha-androstanediol (3alpha-DIOL), 3beta-DIOL, androstenedione, progesterone and cortisol by renal cytoplasm and nuclei of male and female mice was studied. Testosterone was the major androgen isolated from cytoplasm and nuclei following testosterone or androstenedione administration. By contrast, DHT was the major intracellular androgen after DHT, 3alpha- or 3beta-DIOL injection. The uptake of 3-H-testosterone or 3-H-DHT was abolished by excess unlabeled testosterone, DHT or cyproterone acetate. Androgen concentrations in kidney fractions from female mice were similar to those from males. There was no appreciable concentration of the isolated steroids following 3-H-progesterone administration. 3H-cortisol was concentrated in both cytoplasm and nuclei but was not displaced by non-radioactive androgens. These findings suggest that in contrast to prostate, mouse kidney can concentrate both testosterone and DHT. However, since testosterone is the major androgen in blood and since it is not metabolized in kidney, it is the major effector androgen in this organ. Androstenedione is active via conversion to testosterone while DIOLS are androgenic via metabolism to DHT.