Stephanie T. Page

Advances in Male Contraception

Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.

Castration resistance in human prostate cancer is conferred by a frequently occurring androgen receptor splice variant

Progression of prostate cancer following castration is associated with increased androgen receptor (AR) expression and signaling despite AR blockade. Recent studies suggest that these activities are due to the generation of constitutively active AR splice variants, but the mechanisms by which these splice variants could mediate such effects are not fully understood. Here we have identified what we believe to be a novel human AR splice variant in which exons 5, 6, and 7 are deleted (ARv567es) and demonstrated that this variant can contribute to cancer progression in human prostate cancer xenograft models in mice following castration. We determined that, in human prostate cancer cell lines, ARv567es functioned as a constitutively active receptor, increased expression of full-length AR (ARfl), and enhanced the transcriptional activity of AR. In human xenografts, human prostate cancer cells transfected with ARv567es cDNA formed tumors that were resistant to castration. Furthermore, the ratio of ARv567es to ARfl expression within the xenografts positively correlated with resistance to castration. Importantly, we also detected ARv567es frequently in human prostate cancer metastases. In summary, these data indicate that constitutively active AR splice variants can contribute to the development of castration-resistant prostate cancers and may serve as biomarkers for patients who are likely to suffer from early recurrence and are candidates for therapies directly targeting the AR rather than ligand.

Intraprostatic androgens and androgen-regulated gene expression persist after testosterone suppression: therapeutic implications for castration-resistant prostate cancer.

Androgen deprivation therapy (ADT) remains the primary treatment for advanced prostate cancer. The efficacy of ADT has not been rigorously evaluated by demonstrating suppression of prostatic androgen activity at the target tissue and molecular level. We determined the efficacy and consistency of medical castration in suppressing prostatic androgen levels and androgen-regulated gene expression. Androgen levels and androgen-regulated gene expression (by microarray profiling, quantitative reverse transcription-PCR, and immunohistochemistry) were measured in prostate samples from a clinical trial of short-term castration (1 month) using the gonadotropin-releasing hormone antagonist, Acyline, versus placebo in healthy men. To assess the effects of long-term ADT, gene expression measurements were evaluated at baseline and after 3, 6, and 9 months of neoadjuvant ADT in prostatectomy samples from men with localized prostate cancer. Medical castration reduced tissue androgens by 75% and reduced the expression of several androgen-regulated genes (NDRG1, FKBP5, and TMPRSS2). However, many androgen-responsive genes, including the androgen receptor (AR) and prostate-specific antigen (PSA), were not suppressed after short-term castration or after 9 months of neoadjuvant ADT. Significant heterogeneity in PSA and AR protein expression was observed in prostate cancer samples at each time point of ADT. Medical castration based on serum testosterone levels cannot be equated with androgen ablation in the prostate microenvironment. Standard androgen deprivation does not consistently suppress androgen-dependent gene expression. Suboptimal suppression of tumoral androgen activity may lead to adaptive cellular changes allowing prostate cancer cell survival in a low androgen environment. Optimal clinical efficacy will require testing of novel approaches targeting complete suppression of systemic and intracrine contributions to the prostatic androgen microenvironment.

Treatment of male infertility secondary to morbid obesity

Background A 29-year-old man presented to a clinic with infertility and hypogonadism in the setting of morbid obesity. On presentation, he had notable gynecomastia and a low testicular volume. The patients weight was 154 kg and his height was 168 cm (BMI 54.5 kg/m2). Before referral to the clinic, the patient had been treated with testosterone therapy for 4 months for hypogonadism. This treatment had caused his initially low sperm concentration to fall to undetectable levels.Investigations Measurement of reproductive hormone levels, pituitary MRI, and semen analysis.Diagnosis Infertility secondary to hypogonadotropic hypogonadism and an elevated estrogen:testosterone ratio.Management Treatment with an aromatase inhibitor, anastrozole, led to normalization of the patients testosterone, luteinizing hormone and follicle-stimulating hormone levels, suppression of serum estradiol levels, and to normalization of spermatogenesis and fertility.

The Effect of 5α-Reductase Inhibition With Dutasteride and Finasteride on Bone Mineral Density, Serum Lipoproteins, Hemoglobin, Prostate Specific Antigen and Sexual Function in Healthy Young Men

PURPOSE Dutasteride and finasteride are 5alpha-reductase inhibitors that dramatically decrease serum levels of dihydrotestosterone. Because androgens affect bone, lipids, hematopoiesis, prostate and sexual function, we determined the impact of 5alpha-reductase inhibitors on these end points. MATERIALS AND METHODS We conducted a randomized, double-blinded, placebo controlled trial of 99 men 18 to 55 years old randomly assigned to receive 0.5 mg dutasteride (33), 5 mg finasteride (34) or placebo (32) daily for 1 year. Bone mineral density was measured at baseline, after 1 year of treatment and 6 months after drug discontinuation. In addition, markers of bone turnover, fasting serum lipoprotein concentrations, hemoglobin and prostate specific antigen were measured at baseline, after 26 and 52 weeks of treatment, and again 24 weeks after drug discontinuation. Sexual function was assessed at these points by a validated questionnaire. RESULTS Significant suppression of circulating dihydrotestosterone levels with the administration of dutasteride or finasteride did not significantly affect bone mineral density or markers of bone metabolism. Similarly serum lipoproteins and hemoglobin were unaffected. Serum prostate specific antigen and self-assessed sexual function decreased slightly during treatment with both 5alpha-reductase inhibitors but returned to baseline during followup. CONCLUSIONS Profound suppression of circulating serum dihydrotestosterone induced by 5alpha-reductase inhibitors during 1 year does not adversely impact bone, serum lipoproteins or hemoglobin, and has a minimal, reversible effect on serum prostate specific antigen and sexual function in normal men. Circulating dihydrotestosterone does not appear to have a clinically significant role in modulating bone mass, hematopoiesis or lipid metabolism in normal men.

Developmentally regulated expression of three slow isoforms of myosin heavy chain: Diversity among the first fibers to form in avian muscle

At least three slow myosin heavy chain (MHC) isoforms were expressed in skeletal muscles of the developing chicken hindlimb, and differential expression of these slow MHC isoforms produced distinct fiber types from the outset of skeletal muscle myogenesis. Immunohistochemistry with isoform-specific monoclonal antibodies demonstrated differences in MHC content among the fibers of the dorsal and ventral premuscle masses and distinctions among fibers before splitting of the premuscle masses into individual muscles (Hamburger and Hamilton Stage 25). Immunoblot analyses by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of myosin extracted from the hindlimb demonstrated the presence throughout development of different mobility classes of MHCs with epitopes associated with slow MHC isoforms. Immunopeptide mapping showed that one of the MHCs expressed in the embryonic limb was the same slow MHC isoform, slow MHC1 (SMHC1), that is expressed in adult slow muscles. SMHC1 was expressed in the dorsal and ventral premuscle masses, embryonic, fetal, and some neonatal and adult hindlimb muscles. In the embryo and fetus SMHC1 was expressed in future fast, as well as future slow muscles, whereas in the adult only the slow muscles retained expression of SMHC1. Those embryonic muscles destined in the adult to contain slow fibers or mixed fast/slow fibers not only expressed SMHC1, but also an additional slow MHC not previously described, designated as slow MHC3 (SMHC3). Slow MHC3 was shown by immunopeptide mapping to contain a slow MHC epitope (reactive with mAb S58) and to be structurally similar to a MHC expressed in the atria of the adult chicken heart. SMHC3 was designated as a slow MHC isoform because (i) it was expressed only in those muscles destined to be of the slow type in the adult, (ii) it was expressed only in primary fibers of muscles that subsequently are of the slow type, and (iii) it had an epitope demonstrated to be present on other slow, but not fast, isoforms of avian MHC. This study demonstrates that a difference in phenotype between fibers is established very early in the chicken embryo and is based on the fiber type-specific expression of three slow MHC isoforms.

Do Statins Affect Androgen Levels in Men? Results from the Boston Area Community Health Survey

Background: In 2005, statins were among the most commonly used prescription medications in the United States. Some data suggest statins may affect cancer risk and/or disease severity. Because cholesterol is a required intermediate in sex steroid synthesis, it is possible that statins influence prostate cancer risk through effects on steroid hormone metabolism. We investigated whether levels of circulating androgens and their carrier protein, sex hormone–binding globulin (SHBG), varied by statin exposure among a sample of 1,812 men from a population-based epidemiologic study, the Boston Area Community Health Survey. Methods: We measured serum total testosterone, free testosterone, dehydroepiandrosterone sulfate, luteinizing hormone, and SHBG. Statin exposure was collected through participant self-report and/or interviewer-recorded information. Multivariate linear models were constructed to account for potential confounding. Results: The prevalence of statin use was 12.4% [95% confidence interval (95% CI), 10.3-14.9]. On average, statin users were older, had larger body mass index and more chronic illnesses, and used more medications. We found no relationship between statin use and free testosterone, dehydroepiandrosterone sulfate, or luteinizing hormone. A significant association between statin use and total testosterone was initially observed but was not robust to covariate control in a multivariate model that included age, body mass index, time since awakening, and history of cardiovascular disease and diabetes (−5.5%; 95% CI, −13.2 to 2.9%). In multivariate models adjusted similarly, SHBG levels among statin users were statistically significantly lower compared with nonusers (−10.6%; 95% CI, −18.8 to −1.6%). Conclusion: In this sample, it is unlikely that statins affect circulating androgens and prostate cancer risk through a hormonal mechanism. (Cancer Epidemiol Biomarkers Prev 2007;16(8):1587–94)

Dihydrotestosterone Administration Does Not Increase Intraprostatic Androgen Concentrations or Alter Prostate Androgen Action in Healthy Men: A Randomized-Controlled Trial

CONTEXT Concern exists that androgen treatment might adversely impact prostate health in older men. Dihydrotestosterone (DHT), derived from local conversion of testosterone to DHT by 5α-reductase enzymes, is the principal androgen within the prostate. Exogenous androgens raise serum DHT concentrations, but their effects on the prostate are not clear. OBJECTIVE To determine the impact of large increases in serum DHT concentrations on intraprostatic androgen concentrations and androgen action within the prostate. DESIGN Double-blind, randomized, placebo-controlled. SETTING Single academic medical center. PARTICIPANTS 31 healthy men ages 35-55. INTERVENTION Daily transdermal DHT or placebo gel. MAIN OUTCOME MEASURES Serum and prostate tissue androgen concentrations and prostate epithelial cell gene expression after 4 wk of treatment. RESULTS Twenty-seven men completed all study procedures. Serum DHT levels increased nearly sevenfold, while testosterone levels decreased in men treated with daily transdermal DHT gel but were unchanged in the placebo-treated group (P < 0.01 between groups). In contrast, intraprostatic DHT and testosterone concentrations on d 28 were not different between groups (DHT: placebo = 2.8 ± 0.2 vs. DHT gel = 3.1 ± 0.5 ng/g; T: placebo = 0.6 ± 0.2 vs. DHT gel = 0.4 ± 0.1, mean ± se). Similarly, prostate volume, prostate-specific antigen, epithelial cell proliferation, and androgen-regulated gene expression were not different between groups. CONCLUSIONS Robust supraphysiologic increases in serum DHT, associated with decreased serum T, do not significantly alter intraprostatic levels of DHT, testosterone, or prostate epithelial cell androgen-regulated gene expression in healthy men. Changes in circulating androgen concentrations are not necessarily mimicked within the prostate microenvironment, a finding with implications for understanding the impact of androgen therapies in men.

Drug Insight: recent advances in male hormonal contraception

As there are limitations to current methods of male contraception, research has been undertaken to develop hormonal contraceptives for men, analogous to the methods for women based on estrogen and progestogens. When testosterone is administered to a man, it functions as a contraceptive by suppressing the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. Since these hormones are the main stimulatory signals for spermatogenesis, low levels of LH and FSH markedly impair sperm production. After 3–4 months of testosterone treatment, 60–70% of men no longer have sperm in their ejaculate, and most other men exhibit markedly diminished sperm counts. Male hormonal contraception is well tolerated, free of serious adverse side effects, and 95% effective in the prevention of pregnancy. Importantly, male hormonal contraception is reversible, with sperm counts usually recovering within 4 months of the discontinuation of hormone treatment. Because exogenous testosterone administration alone does not completely suppress sperm production in all men, researchers have combined testosterone with second agents, such as progestogens or gonadotropin-releasing-hormone antagonists, to further suppress secretion of LH and FSH and improve suppression of spermatogenesis. Recent trials have used combinations of long-acting injectable or implantable forms of testosterone with progestogens, which can be administered orally, by injection or by a long-acting implant. Such combinations suppress spermatogenesis to zero without severe side effects in 80–90% of men, with near-complete suppression in the remainder of individuals. One of these testosterone and progestogen combination regimens might soon bring the promise of male hormonal contraception to fruition.

Combined Transdermal Testosterone Gel and the Progestin Nestorone Suppresses Serum Gonadotropins in Men

CONTEXT Testosterone (T) plus progestin combinations are the most promising hormonal male contraceptives. Nestorone (NES), a progestin without estrogenic or androgenic activity, when combined with T may be an excellent candidate for male contraception. OBJECTIVE Our objective was to determine the effect of transdermal NES gel alone or with T gel on gonadotropin suppression. DESIGN AND SETTING The randomized, unblinded clinical trial was conducted at two academic medical centers. PARTICIPANTS A total of 140 healthy male volunteers participated. INTERVENTIONS One hundred subjects were randomized initially (20 per group) to apply NES gel 2 or 4 mg, T gel 10 g, or T gel 10 g plus NES gel 2 or 4 mg daily for 20 d. Because only about half of the subjects in T plus NES 4 mg group suppressed serum gonadotropins to 0.5 IU/liter or less (suboptimal suppression), two additional groups of 20 men were randomized to apply daily T gel 10 g plus NES gel 6 or 8 mg. MAIN OUTCOME VARIABLE Suppression of serum LH and FSH concentrations to 0.5 IU/liter or less after treatment was the main outcome variable. RESULTS A total of 119 subjects were compliant with gel applications with few study-related adverse events. NES alone reduced gonadotropins significantly but less than T gel alone. Combined T gel 10g plus NES gel 6 or 8 mg suppressed both serum gonadotropins to 0.5 IU/liter or less in significantly more men than either gel alone. CONCLUSION Transdermal NES gel alone had gonadotropin suppression activity. Combined transdermal NES (6 or 8 mg) plus T gel demonstrated safe and effective suppression of gonadotropins, justifying a longer-term study of this combination for suppression of spermatogenesis.