Dutasteride in men receiving testosterone therapy: a randomised, double-blind study.

We investigate the impact of dutasteride on prostate specific antigen (PSA) and prostate volume in men receiving testosterone (T) therapy. Twenty-three men on stable dose T therapy were randomised to receive either dutasteride or placebo for 12 months. Serum levels of PSA, T and dihydrotestosterone (DHT) and responses to the International Index of Erectile Function (IIEF) and Male Sexual Health Questionnaire (MSHQ) questionnaires were determined at baseline and at 3, 6, 9 and 12 months. Prostate volume (PV) was measured using transrectal ultrasound (TRUS) at baseline and again after 12 months. A total of 22 men (mean age 57.3) completed the study, with 11 men receiving placebo and 11 receiving dutasteride. Men receiving dutasteride had a significant decrease in PSA (-0.46 ± 0.81 ng ml(-1) ; P = 0.04) and in PV (-6.65 ± 11.0%; P = 0.03) from baseline over 12 months. DHT decreased significantly for men on dutasteride compared with men receiving placebo (P = 0.02). When compared with men who received placebo, men who received dutasteride demonstrated nonsignificant trends towards decreased PSA (-0.46 versus 0.21 ng ml(-1) ; P = 0.11), PV (-6.65% versus 3.4%; P = 0.08) and MSHQ scores (-10.2 versus 5.6; P = 0.06). Dutasteride reduces PSA and PV for men on T therapy, but perhaps less so than in men without T therapy.

Statin use and risk of prostate cancer and high-grade prostate cancer: results from the REDUCE study.

BACKGROUND: Statins are associated with lower PSA levels. As PSA is the primary method for prostate cancer (PC) screening, this confounds any associations between statins and risk of being diagnosed with PC. Thus, we examined the association between statins and cancer and high-grade cancer in REDUCE, where biopsies were largely PSA-independent. METHODS: Post-hoc secondary analysis of REDUCE, which was a prospective multinational randomized controlled trial of dutasteride vs placebo for 4 years among men aged 50-75 years with PSA of 2.5-10.0 ng ml(-1) and a negative biopsy at baseline, and included PSA-independent biopsies mandated at 2- and 4-years. Analyses were limited to men who underwent at least one biopsy while under study (n=6729). The association between baseline statin use and risk of overall, high-grade (Gleason ≥ 7) or low-grade (Gleason ≤ 6) PC vs no cancer was examined using multinomial logistic regression adjusting for age, race, baseline PSA, prostate volume, rectal examination findings, body mass index (BMI), comorbidities, smoking, alcohol intake and treatment arm. RESULTS: Of 6729 men who had at least one biopsy while on study, 1174 (17.5%) were taking a statin at baseline. Men taking statins were older, had lower PSA levels, higher BMI values and lower serum testosterone and dihydrotestosterone levels, though differences, were slight. Statin use was not associated with overall PC diagnosis (multivariable OR 1.05, 95% CI 0.89-1.24, P=0.54). When stratified by grade, statin use was not associated with low-grade (multivariable OR 1.03, 95% CI 0.85-1.25, P=0.75) or high-grade cancer (multivariable OR 1.11, 95% CI 0.85-1.45, P=0.46). The major limitation is the inclusion of only men with a negative baseline biopsy. CONCLUSIONS: Among men with a negative baseline biopsy and follow-up biopsies largely independent of PSA, statins were not associated with cancer or high-grade cancer.

Diabetes and prostate cancer risk in the REDUCE trial.

Men with diabetes mellitus are less likely to be diagnosed with prostate cancer (PCa). As diabetic men have lower serum PSA, it is unclear if this is due to lower PCa incidence or reflects detection bias from fewer PSA-triggered biopsies. To account for differential biopsy rates, we used multivariate regression to examine the link between diabetes and PCa risk in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial, which required all subjects to undergo biopsy regardless of PSA. We further tested for interaction between diabetes and obesity. Diabetes status and body mass index (BMI) measurements were obtained at baseline. On multivariate analysis, diabetes was not associated with PCa risk (odds ratio (OR) 1.01, 95% confidence interval 0.79-1.30, P=0.92) or risk of low- or high-grade disease (all P ≥ 0.65). When stratified by obesity, diabetes was also not associated with PCa risk in any BMI category (all P ≥ 0.15). However, there was suggestion of effect modification by obesity for high-grade disease (P-interaction=0.053). Specifically, diabetes was associated with decreased risk of high-grade PCa in normal-weight men but increased risk in obese men (OR 0.35 vs 1.38). In the REDUCE trial, when all men underwent biopsy, diabetes was not associated with lower PCa risk, but rather equal risk of PCa, low-grade PCa and high-grade PCa.

Fetal distribution of 5alpha-reductase 1 and 5alpha-reductase 2, and their input on human prostate development.

PURPOSE: Human prostate development starts in the tenth week of gestation. Initial interactions between the epithelium and mesenchyma are stimulated by androgens. The transformation of circulating testosterone to 5alpha-dihydrotestosterone by tissue linked 5alpha-reductase is a key event in androgen metabolism. The 5alpha-dihydrotestosterone mediates androgen effects in the urogenital sinus and external genitalia, leading to the formation of a male phenotype and androgen mediated prostate growth. Supposedly 5alpha-reductase 2 is the predominant isoenzyme in human accessory sex tissue, whereas the function of 5alpha-reductase 1 remains unclear. We focused on the detection, distribution and effects of the 2 isoenzymes during gestation and infancy. MATERIALS AND METHODS: Serial sections from fetuses and infants were immunostained using antibodies directed against 5alpha-reductase 1 and 2. Additionally, to detect the downstream products of androgen synthesis reverse transcriptase-polymerase chain reaction analyses were done for 17 beta-hydroxysteroid dehydrogenase types 2, 3 and 7. RESULTS: Immunohistochemistry revealed positive staining for each isoenzyme throughout fetal development. Moreover, reverse transcriptase-polymerase chain reaction for 5alpha-reductase 1 and 2 confirmed these findings on the transcription level. Additionally, the most relevant enzymatic downstream products of cellular androgen synthesis (17 beta-hydroxysteroid dehydrogenase 2, 3 and 7) were also detected by reverse transcriptase-polymerase chain reaction. CONCLUSIONS: To our knowledge this is the first study revealing the expression and distribution of each 5alpha-reductase isoenzyme as well as the potential contribution of 5alpha-reductase 1 during fetal human prostate development.

The effect of dutasteride on intraprostatic dihydrotestosterone concentrations in men with benign prostatic hyperplasia.

The dual 5alpha-reductase inhibitor, dutasteride has been shown to suppress serum dihydrotestosterone (DHT) by >90%. In the present study, the effect of dutasteride 0.5 mg/day on intraprostatic DHT levels was investigated. In this multicenter, double-blind trial, 43 men with benign prostatic hyperplasia (BPH) scheduled to undergo transurethral resection of the prostate (TURP) were randomized to receive dutasteride, 0.5 mg/day or placebo for 3 months before surgery. Intraprostatic DHT, testosterone and dutasteride levels were determined at the time of TURP. Changes in serum DHT and testosterone from baseline, and both serum and intraprostatic dutasteride levels at the time of TURP were also assessed. Dutasteride reduced intraprostatic DHT by 94% relative to placebo (P<0.001); the adjusted mean intraprostatic DHT concentration was 3.23 and 0.209 ng/g in the placebo and dutasteride groups, respectively. In the dutasteride group, serum DHT was reduced from baseline by 93% at month 3, a significantly greater reduction (P<0.001) than the 15% decrease observed in the placebo group. There was a reciprocal increase in intraprostatic testosterone but the level of intraprostatic testosterone in the dutasteride group tended to be lower than the intraprostatic DHT level in the placebo group (P=0.06). Significant intraprostatic DHT suppression was achieved in all subjects who received dutasteride, regardless of the level of intraprostatic dutasteride. There was a strong positive correlation between serum and intraprostatic dutasteride concentrations (R(2)=0.73). After 3 months of treatment, dutasteride 0.5 mg/day provided near-complete suppression of both intraprostatic and serum DHT in men with BPH.

The effects of the dual 5alpha-reductase inhibitor dutasteride on localized prostate cancer--results from a 4-month pre-radical prostatectomy study.

BACKGROUND: As dihydrotestosterone (DHT) is the most potent androgen in the prostate, inhibition of the 5alpha-reductase isoenzymes, which convert testosterone to DHT, could be an appropriate target for the treatment of prostate cancer. METHODS: Eighty-one men with clinically localized prostate cancer received daily dutasteride 3.5 or 0.5 mg, or no therapy for 4 months before radical prostatectomy. Histopathological assessments were conducted on prostatectomy specimens. RESULTS: Treatment with dutasteride was associated with reductions in serum and intraprostatic DHT of >or=90%, and a decrease in total prostate and tumor volumes. No effect of dutasteride was noted on Gleason grade. Histopathological effects on benign tissue were similar but less prominent than those seen with androgen ablation, whereas there was no significant difference in cancer histology among the groups. CONCLUSIONS: Dutasteride treatment results in similar but less marked changes compared with androgen ablation.

Differential alterations in 5alpha-reductase type 1 and type 2 levels during development and progression of prostate cancer.

BACKGROUND: In the prostate, conversion of testosterone to dihydrotestosterone (DHT), by the enzymes 5alpha-reductase types 1 and 2 (5alphaR1, 5alphaR2) is required for normal growth and probably also for development of prostate cancer (PCa). Finasteride, a 5alphaR2 inhibitor, was shown to reduce the prevalence of PCa in the Prostate Cancer Prevention Trial. However, inhibition of both 5alphaR isoenzymes causes a greater decrease in serum DHT. The aim of this study was to assess differential expression of these enzymes at various stages of PCa development. METHODS: Immunostaining for 5alphaR1 and 5alphaR2, using specific, well-validated antibodies, was evaluated in 26 benign prostatic hyperplasia (BPH) (16 for 5alphaR2), 53 primary PCa (21 for 5alphaR2), 18 prostatic intraepithelial neoplasia (PIN), 12 primary PCa treated with neoadjuvant androgen ablation, 15 locally recurrent PCa specimens, and 18 PCa metastases. RESULTS: The mean area of moderate plus high intensity staining for 5alphaR1 increased from 4.8 +/- 2.8% of total epithelial area in BPH, to 18.9 +/- 5.7% in PIN, 17.0 +/- 3.2% in primary cancer, 38.0 +/- 7.3% in recurrent cancer, and 55.8 +/- 8.5% in PCa metastases. The mean staining area for 5alphaR2 decreased from 58.8 +/- 7.2% in BPH, to 21.1 +/- 5.5% in PIN and 34.8 +/- 6.7% in primary PCa. Staining for 5alphaR2 was increased in recurrent cancer and PCa metastases compared to primary PCa, at 58.7 +/- 5.2% and 69.2 +/- 8.7%, respectively. CONCLUSIONS: 5alphaR1 immunostaining is increased and 5alphaR2 immunostaining is decreased during development of PCa. In addition, there is increased expression of both 5alphaR isozymes in recurrent and metastatic cancers, suggesting that both isozymes may be important in the development and progression of PCa.

Effect of dutasteride on the detection of prostate cancer in men with benign prostatic hyperplasia.

OBJECTIVES: To examine the rate of prostate cancer detection in three large randomized placebo-controlled benign prostatic hyperplasia trials of dutasteride. Dutasteride, which lowers serum dihydrotestosterone more than 93% by inhibiting type 1 and type 2 5-alpha-reductase, is effective in the treatment of benign prostatic hyperplasia. However, its effect on the development of prostate cancer is unknown. METHODS: A total of 4325 men with benign prostatic hyperplasia but without a history, or evidence, of prostate cancer, and a serum prostate-specific antigen level of 1.5 to 10 ng/mL, were randomized to 0.5 mg/day dutasteride or placebo for 24 months. The prostate cancer detection rates for subjects were determined by non-protocol-mandated biopsies, either during the double-blind phase of the study or during the first 3 months of the open-label extension. A follow-up questionnaire was administered to a subset of consenting subjects to ascertain the number, outcomes, and reasons for the prostate biopsies. RESULTS: The cumulative incidence of prostate cancer as an adverse event was significantly lower in the dutasteride versus placebo group at 24 months (1.1% versus 1.9%, P = 0.025) and 27 months (1.2% versus 2.5%, P = 0.002). There were no differences in the diagnosis rates of prostate cancer during the first 15 months, after which time the detection rate of prostate cancer increased in the placebo group and remained low in the dutasteride group. CONCLUSIONS: Prostate cancer detection was significantly lower in subjects randomized to dutasteride compared with the placebo group. These results have prompted the initiation of the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study, which was designed and powered to test the hypothesis that treatment with dutasteride decreases the incidence and progression of prostate cancer.

Effect of the dual 5alpha-reductase inhibitor dutasteride on markers of tumor regression in prostate cancer.

PURPOSE: In the prostate testosterone is converted to dihydrotestosterone (DHT) by the enzymes 5alpha-reductase (5alphaR) types 1 and 2 (5alphaR1 and 5alphaR2). Suppression of DHT formation by 5alphaR inhibition may be beneficial in early treatment or prevention of prostate cancer. Although 5alphaR2 is the dominant enzyme in the prostate, evidence indicates that 5alphaR1 may be up-regulated in some prostate cancers. This suggests that dual inhibition of both isoenzymes may be more effective than suppression of 5alphaR2 alone in prostate cancer treatment or prevention. In this short-term pilot study we examined the effect of the dual 5alphaR inhibitor dutasteride on markers of tumor regression. MATERIALS AND METHODS: A total of 46 men with clinically staged T1 or T2 prostate cancer were randomized to receive 5 mg per day of placebo or dutasteride for 6 to 10 weeks before radical prostatectomy. Resected tissues were analyzed to determine the effect of dutasteride on intraprostatic androgen levels, and indices of apoptosis and microvessel density (MVD) in malignant tissue, as well as degree of atrophy in benign tissue. RESULTS: Treatment with dutasteride caused a 97% decrease in intraprostatic DHT and was associated with a trend toward increased apoptosis. In patients receiving dutasteride for 45 days or more, a significant increase in apoptosis and a trend toward decreased MVD in prostate cancer tissue was observed. Dutasteride treatment was also associated with an 18% decrease in mean benign epithelial cell width compared with placebo (p < 0.0001). CONCLUSIONS: In this pilot study dutasteride treatment resulted in almost complete suppression of intraprostatic DHT, increased apoptosis and a trend toward decreased MVD. These findings suggest that short-term treatment with dutasteride can cause regression in some prostate cancers.

Dutasteride, the dual 5alpha-reductase inhibitor, inhibits androgen action and promotes cell death in the LNCaP prostate cancer cell line.

BACKGROUND: Reduction of T to DHT by 5alphaR in the prostate enhances androgenic activity for most targets. Inhibition of 5alphaR activity with finasteride attenuates androgen action in men and animal models. The objective of this study was to compare and contrast the effects of a potent new 5alphaR inhibitor, dutasteride, with finasteride in the LNCaP prostate cancer cell line. METHODS: LNCaP cells were incubated for varying times with T or DHT in steroid-free medium in the absence or presence of increasing doses of dutasteride or finasteride and the effects on 5alphaR activity, PSA accumulation in the medium, and on cell proliferation were determined. Drug effects on apoptosis were investigated using Annexin V staining and a cell death ELISA assay. Effects of the drugs on AR ligand-binding activity and on AR protein levels were determined. RESULTS: Dutasteride inhibited (3)H-T conversion to (3)H-DHT and, as anticipated, inhibited T-induced secretion of PSA and proliferation. However the drug also inhibited DHT-induced PSA secretion and cell proliferation (IC(50) approximately 1 microM). Finasteride also inhibited DHT action but was less potent than dutasteride. Dutasteride competed for binding the LNCaP cell AR with an IC(50) approximately 1.5 microM. High concentrations of dutasteride (10-50 microM), but not finasteride, in steroid-free medium, resulted in enhanced cell death, possibly by apoptosis. This was accompanied by loss of AR protein and decreased AR ligand-binding activity. Occupation of AR by R1881 partly protected against cell death and loss of AR protein. PC-3 prostate cancer cells, which do not contain AR, also were killed by high concentrations of dutasteride, as well as by 50 microM finasteride. CONCLUSIONS: Dutasteride exhibited some inhibitory actions in LNCaP cells possibly related to 5alphaR inhibition but also had antiandrogenic effects at relatively low concentrations and cell death-promoting effects at higher concentrations. Finasteride also was antiandrogenic, but less than dutasteride. The antiandrogenic effects may be mediated by the mutant LNCaP cell AR. Promotion of cell death by dutasteride can be blocked, but only in part, by androgens.

5alpha-reductase type 1 immunostaining is enhanced in some prostate cancers compared with benign prostatic hyperplasia epithelium.

PURPOSE: In the prostate testosterone is converted to the more potent androgen dihydrotestosterone by the enzymes 5alpha-reductase (5alphaR) types 1 (5alphaR1) and 2 (5alphaR2). Since 5alphaR2 is the dominant prostatic enzyme, the 5alphaR2 selective inhibitor finasteride has been widely used to treat benign prostatic hyperplasia (BPH). However, inhibition of both 5alphaR enzymes provides a greater decrease in serum dihydrotestosterone. We developed a specific antibody to 5alphaR1 and assessed expression in BPH and prostate cancer (pCa) tissue. The presence of this isoenzyme in localized prostate cancer would provide a rationale for assessing the efficacy of dual inhibition for prostate cancer prevention. MATERIALS AND METHODS: A polyclonal antibody to 5alphaR1 was developed and validated using 5alphaR1 and 5alphaR2 transfected COS-1 cells. A total of 26 BPH and 53 pCa specimens were assessed for 5alphaR1 protein expression using immunocytochemical methods. Also, 29 BPH and 37 pCa specimens were assayed for 5alphaR1 and 5alphaR2 enzyme activity. RESULTS: Specificity of the 5alphaR1 antibody was confirmed using transfected COS-1 cells. Cells transfected with 5alphaR1 showed specific staining in immunocytochemistry experiments and on Western blotting of cell lysates the expected 24 kDa band was observed. High intensity immunoreactivity for 5alphaR1 was observed in the tumor epithelium of 28% of pCa specimens. No high intensity epithelial staining was observed in BPH specimens. In 19% of pCa and 7% of BPH specimens 5alphaR1 enzyme activity was detected. CONCLUSIONS: The presence of increased 5alphaR1 in some prostatic malignancies suggests that it is worthwhile to investigate the use of a dual 5alphaR inhibitor to prevent or treat early stage prostate cancer.

[Dihydrotestosterone and the role of 5 alpha-reductase inhibitors in benign prostatic hyperplasia]. / Dihydrotestosteron und die Rolle der 5 alpha-Reduktasehemmer bei der benignen Prostatahyperplasie.

The genesis of benign prostate hyperplasia (BPH) depends on two factors: testicular androgen and the aging process. The most important androgen in the prostate is dihydrotestosterone (DHT). In the aging male the level of DHT in the prostate remains largely constant although the plasma level of testosterone decreases. DHT is formed by the reduction of testosterone by the enzyme 5-alpha-reductase, which has two isoenzymes. The 5-alpha-reductase type 2 is the predominant isoenzyme in genital tissue and thus also in the prostate. Finasteride is a 5-alpha-reductase inhibitor, which is applied in the treatment of BHP and male baldness. In the doses used finasteride acts mainly by inhibiting the 5-alpha-reductase type 2, thereby reducing the serum level of DHT by approximately 70% and by about 85-90% in the prostate. Indeed the effect of finasteride in BPH was proven in clinical studies. However, the circulating and intraprostatic DHT could be further reduced by a more effective dual 5-alpha-reductase inhibitor, which would be efficacious in the treatment of benign prostate hyperplasia and other DHT-related disorders.

Dihydrotestosterone and the concept of 5alpha-reductase inhibition in human benign prostatic hyperplasia.

The development of human benign prostatic hyperplasia (BPH) clearly requires a combination of testicular androgens and the ageing process. Although the role of androgens as the causative factor for human benign prostatic hyperplasia is debated, they undoubtedly play, at least, a permissive role. The principal prostatic androgen is dihydrotestosterone. Although not elevated in human benign prostatic hyperplasia, dihydrotestosterone levels in the prostate remain at a normal level with ageing, despite a decrease in the plasma testosterone. Dihydrotestosterone (DHT) is generated by a reduction in testosterone. Two isoenzymes of 5alpha-reductase have been discovered. Type 1 is present in most tissues in the body where 5alpha-reductase is expressed, and is the dominant form in sebaceous glands. Type 2 5alpha-reductase is the dominant isoenzyme in genital tissues, including the prostate. Finasteride is a 5alpha-reductase inhibitor that has been used to treat BPH and male-pattern baldness. At doses used clinically, its major effect is to suppress type 2 5alpha-reductase, because it has a much lower affinity for the type 1 isoenzyme. Finasteride suppresses DHT by about 70% in serum and by as much as 85%-90% in the prostate. The remaining DHT in the prostate is likely to be the result of type 1 5alpha-reductase. The suppression of both 5alpha-reductase isoenzymes with GI198745 results in greater and more consistent containment of serum dihydrotestosterone than that observed with a selective inhibitor of type 2 5alpha-reductase. Physiological and clinical studies comparing dual 5alpha-reductase inhibitors, such as GI198745, with selective type 2, such as finasteride, will be needed to determine the clinical relevance of type 1 5alpha-reductase within the prostate. There have been two large, international multicentre, phase III trials published documenting the safety and efficacy of finasteride in treating human benign prostatic hyperplasia. Combining these two studies, randomised, controlled data are available for 12 months. Non-controlled extension of these data from a subset of patients, who elected to continue on the drug for 3, 4 and 5 years, are also available. Long-term medical therapy with finasteride can reduce clinically significant endpoints, such as acute urinary retention or surgery. According to the meta-analysis of six randomised, clinical trials with finasteride, finasteride is most effective in men with large prostates. A more effective dual inhibitor of type 1 and 2 human 5alpha-reductase may lower circulating dihydrotestosterone to a greater extent than finasteride and show advantages in treating human benign prostatic hyperplasia and other disease states that depend on dihydrotestosterone. A clinical evaluation of potent dual 5alpha-reductase inhibitors may help to define the relative roles of human type 1 and 2 5alpha-reductase in the pathophysiology of benign prostatic hyperplasia and other androgen-dependent diseases.

Enhancement of bone mass in osteoporotic women with parathyroid hormone followed by alendronate.

Treatment of osteoporosis with PTH causes a marked increase in vertebral bone mineral density (BMD). However, this effect is rapidly reversed when the treatment is stopped. The purpose of the present study was to determine whether the bisphosphonate alendronate could preserve or enhance bone density in patients previously treated with PTH. Sixty-six postmenopausal osteoporotic women were treated for 1 yr with 50, 75, or 100 microg recombinant human PTH-(1-84) or placebo, and then were given 10 mg alendronate daily for an additional year. BMD was measured in the femoral neck, lumbar spine, and whole body. Markers of bone turnover included skeletal alkaline phosphatase, osteocalcin, and N-telopeptide. During the first year, changes in BMD (mean +/- SD) in women receiving PTH (all doses combined) were 7.1 +/- 5.6% (spine), 0.3 +/- 6.2% (femoral neck), and -2.3 +/- 3.3% (total body). After switching to alendronate for 1 yr in women who previously had received PTH, mean changes in BMD were 13.4 +/- 6.4% (spine), 4.4 +/- 7.2% (femoral neck), and 2.6 +/- 3.1% (whole body). In the subgroup of patients who had received the highest dose of PTH, the mean increase in vertebral BMD was 14.6 +/- 7.9%. All markers of bone turnover increased during treatment with PTH and decreased to below baseline after 1 yr of alendronate. In conclusion, sequential treatment of osteoporosis with PTH and alendronate results in an increase in vertebral bone density that is considerably more than has been reported with alendronate or estrogens alone. This combination of drugs may be a useful approach to maximizing bone density in women with vertebral osteoporosis.

Dihydrotestosterone and the concept of 5alpha-reductase inhibition in human benign prostatic hyperplasia.

OBJECTIVE: The development of the human benign prostatic hyperplasia clearly requires a combination of testicular androgens and aging. Although the role of androgens as the causative factor for human benign prostatic hyperplasia is debated, they undoubtedly have at least a permissive role. The principal prostatic androgen is dihydrotestosterone (DHT). Although not elevated in human benign prostatic hyperplasia, DHT levels in the prostate remain at a normal level with aging, despite a decrease in the plasma testosterone. RESULTS: DHT is generated by reduction of testosterone. Two isoenzymes of 5alpha-reductase have been discovered. Type 1 is present in most tissues of the body where 5alpha-reductase is expressed and is the dominant form in sebaceous glands. Type2 5alpha-reductase is the dominant isoenzyme in genital tissues, including the prostate. Finasteride is a 5alpha-reductase inhibitor that has been used for the treatment of benign prostatic hyperplasia and male-pattern baldness. At doses used clinically, its major effect is through suppression of type 2 5alpha-reductase, because it has a much lower affinity for the type 1 isoenzyme. Finasteride suppresses DHT by about 70% in serum and by as much as 85-90% in the prostate. The remaining DHT in the prostate is likely to be the result of type 1 5alpha-reductase. Suppression of both 5alpha-reductase isoenzymes with GI198745 result in greater and more consistent suppression of serum dihydrotestosterone than that observed with a selective inhibitor of type 2 5alpha-reductase. Physiological and clinical studies comparing dual 5alpha-reductase inhibitors, such as GI198745, with selective type 2, such as finasteride, will be needed to determine the clinical relevance of type 1 5alpha-reductase within the prostate. Two large international multicenter, phase III trials have been published documenting the safety and efficacy of finasteride in the treatment of human benign prostatic hyperplasia. Combining these two studies, randomized, controlled data are available for 12 months. Noncontrolled extension of these data from a subset of patients, who elected to continue drug treatment for 3, 4 or 5 years, are also available. Long-term medical therapy with finasteride can reduce clinically significant endpoints such as acute urinary retention or surgery. According to the meta-analysis of six randomised clinical trial with finasteride, finasteride is most effective in men with large prostates. A more effective dual inhibitor of type 1 and 2 human 5alpha-reductase may lower circulating DHT to a greater extent than finasteride and show advantages in the treatment of human benign prostatic hyperplasia and other disease states that depend on DHT. CONCLUSION: Clinical evaluation of potent dual 5alpha-reductase inhibitors may help define the relative roles of human type 1 and 2 5alpha-reductase in the pathophysiology of benign prostatic hyperplasia and other androgen-dependent diseases.

Prostatic involution in men taking finasteride is associated with elevated levels of insulin-like growth factor-binding proteins (IGFBPs)-2, -4, and -5 .

BACKGROUND: Insulin-like growth factor-binding proteins (IGFBPs)-2, -4, and -5 are associated with upregulation of apoptosis in the ovary. The purpose of this study was to assess the roles of IGF-I and IGFBPs during involution of the prostate. Frozen and fixed tissue was collected by transurethral prostatectomy from Caucasian men, aged 52-82 years, scheduled for prostatectomy for benign prostatic hyperplasia, who took either placebo (n = 7) or the 5alpha-reductase inhibitor finasteride for 6 days to 6 years (n = 15) prior to surgery. METHODS: Intraprostatic androgen levels were measured by radioimmunoassay. Tissues were immunostained for IGF-I and IGFBP-2, -3, -4, and -5, and staining was quantitated by computerized image analysis. Serial sections were stained for markers of apoptosis (TUNEL and tissue transglutaminase) and IGFBP-2, -4, or -5. RESULTS: IGF-I staining was significantly decreased in the medium-term (18-43 days) treatment group and remained so for the duration of the study (P = 0.026). IGFBP-3 staining was unchanged in the early and medium-term treatment groups; however, a transient earlier rise in the level of this proapoptotic protein cannot be ruled out. The percentage of epithelial cell area staining positively for IGFBP-2 increased significantly, from 1.6 +/- 0.5 in the placebo group to 12.0 +/- 2.0 (P < 0.0001), and 7.6 +/- 1.9 (P = 0.003) in the short (6-13 days) and medium-term treatment groups, respectively. IGFBP-4 staining increased from 2.2 +/- 0.6 to 9.8 +/- 1.9 (P < 0.0001) and 7.4 +/- 1.2 (P = 0.004) in the short and medium-term groups, respectively, and IGFBP-5 staining increased from 0.2 +/- 0.1 to 3.8 +/- 2.0 (P = 0.004) in the medium-term group. The results from serial sections showed that IGFBP-2 and -4 costained with markers of apoptosis, while IGFBP-5 did not. CONCLUSIONS: These results indicate that IGFBP-2, -4, and -5 are associated with prostatic involution. Because of the timing and distribution of expression, we hypothesize that IGFBP-2 and -4 have a role as signals for apoptosis, but that IGFBP-5 likely does not.

The utility of tissue transglutaminase as a marker of apoptosis during treatment and progression of prostate cancer.

PURPOSE: To determine the extent of cell proliferation and apoptosis during treatment and progression of prostate cancer and to determine whether staining for tissue transglutaminase is a better histological marker than TUNEL for neoadjuvant androgen ablation treatment of localized prostate cancer. MATERIALS AND METHODS: Immunocytochemistry techniques were used on archival prostate tissue from four groups of men: 14 men with BPH, 18 men with untreated, localized prostate cancer, 21 men with localized prostate cancer who received neoadjuvant hormone therapy prior to prostatectomy and 18 men with metastatic androgen-independent prostate cancer. Cell proliferation was evaluated by staining for the Ki67 nuclear antigen, and apoptosis was evaluated by staining for DNA fragmentation (TUNEL technique) and tissue transglutaminase (tTG). Image analysis was used to quantitate the results. RESULTS: TUNEL staining increased by 37% in localized prostate cancer compared with BPH, with a further increase of 43% seen after neoadjuvant therapy, although variation was such that neither was statistically significant. In androgen-independent cancer, TUNEL staining was decreased compared with neoadjuvant hormone treated cancer (p = 0.02). Staining for tTG was not increased in untreated prostate cancer compared with BPH; however, staining more than doubled after neoadjuvant therapy, compared with untreated prostate cancer (p = 0.04). Staining for tTG was markedly decreased in androgen-independent cancer (p = 0.07 compared with BPH and p = 0.0004 compared with neoadjuvant hormone treated cancer). Ki67 immunoreactivity did not significantly change in localized prostate cancer, either before or after neoadjuvant therapy, compared with BPH, but it more than doubled in androgen-independent prostate cancer (p = 0.07 compared with BPH and p = 0.05 compared with untreated prostate cancer). CONCLUSIONS: This study shows that cell proliferation increases and apoptosis decreases as prostate cancer progresses to androgen independence, and, that of the markers used in this study, tissue transglutaminase most accurately reflects the anticipated effect of neoadjuvant hormone therapy on localized prostate cancer. An assessment of these parameters provides a valuable tool for appraising new prostate cancer therapies.

Androgen-induced regrowth in the castrated rat ventral prostate: role of 5alpha-reductase.

Testosterone (T), the major circulating androgen, must be converted to dihydrotestosterone (DHT) by the enzyme 5alpha-reductase (5alpha-R) to be maximally active in the prostate. The present study was designed to determine the relative potency of T and DHT on regrowth of the involuted prostate and to elucidate the role of 5alpha-R in the growing prostate. To create dose-response curves for intraprostatic T or DHT, rats were castrated for 2 weeks to allow their prostates to fully regress and then given T implants of various sizes in the presence or absence of the 5alpha-R inhibitor, finasteride. Markers for androgen effects on regrowth of the prostate were prostate weight, duct mass (a measure of secretory activity) and DNA content (a measure of cell number). To assess the relative uptake of T and DHT by the prostate, a comparison was made of intraprostatic DHT levels resulting from T and DHT implants. In the prostate, 1.6-1.9 times more T than DHT was required to achieve a half-maximal response for each of the three markers of prostate regrowth. The dose-response curves revealed that thresholds for intraprostatic T and DHT had to be attained before significant growth was observed. The threshold for T was 2- to 3-fold greater than that for DHT. However, at high intraprostatic concentrations, the effects of T mimicked those of DHT. When the relationship between serum T levels and prostate regrowth was considered, 13 times more serum T was required for half-maximal prostate regrowth when its conversion to DHT was blocked by finasteride. This is partly due to decreased androgen accumulation in the prostate when T was the major intraprostatic androgen. Finally, T or DHT implants in the absence of finasteride resulted in similar intraprostatic DHT levels, indicating that uptake of each serum androgen into the prostate was similar. However, to achieve similar levels of DHT or T in serum, much larger DHT pellets were needed, suggesting more rapid metabolism of DHT in tissues other than the prostate. We conclude that the role of 5alpha-R is 2-fold: it converts testosterone into a modestly more potent androgen and enhances prostatic accumulation of androgen. DHT, in principle, could serve equally well as T as the circulating androgen, although the rate of DHT production would have to be considerably higher to counter the apparent rapid clearance from serum. In addition, we hypothesize that T has arisen as the major circulating androgen instead of DHT because it can be aromatized to estradiol, which itself has important roles in male reproductive function and bone physiology.

Antiandrogen treatment of polycystic ovary syndrome.

Although hirsutism and androgenetic alopecia are cosmetic problems, they can be psychologically devastating for women. Mechanical hair removal may control the cosmetic appearance of hirsutism, but the underlying problem usually continues to progress. Topical therapies for androgenetic alopecia provide for modest improvement at best, and no topical therapy has been shown to be effective for hirsutism. Antiandrogens, combined with ovarian suppression, offer the best hope for the improvement of hirsutism and androgenetic alopecia in women with PCOS. Improvement will occur in most women. Unless the underlying cause of the PCOS is corrected, medical therapy will need to be continued indefinitely.

Insulin-like growth factor binding protein 5 is associated with involution of the ventral prostate in castrated and finasteride-treated rats.

BACKGROUND: Insulin-like growth factor binding protein (IGFBP)-5 has been proposed as a signal for apoptosis in the ovary. To determine the relationship between IGFBP-5 and apoptosis during regression of the androgen-deprived prostate, rats were castrated or treated with the 5alpha-reductase inhibitor finasteride for 4, 9, 14, 21, and 28 days. METHODS: Ventral prostate tissue was immunostained for IGFBP-5, and apoptotic cells were identified by in situ end-labeling of fragmented DNA (TUNEL). To compare the distribution of IGFBP-5 with the distribution of apoptotic cells, mirror-image serial sections of prostate tissues from normal and day 4 finasteride-treated rats were examined. RESULTS: In normal rats, 4+/-1% of prostate epithelial cells stained positively for IGFBP-5, and 0.1+/-0.03% demonstrated DNA fragmentation. IGFBP-5 staining peaked at day 9 with 93 +/-2% and 64+/-13% of epithelial cells staining positively in castrated and finasteride-treated rats, respectively. In contrast, DNA fragmentation peaked at day 4 in tissues from both castrated and finasteride-treated rats with 7+/-1% and 0.7+/-0.3% of epithelial cells, respectively, staining. In the serial sections, TUNEL and IGFBP-5 staining were not usually expressed in the same cells. CONCLUSIONS: Prostatic involution involves both programmed cell death and inhibition of cell growth. Because of the distribution of staining and the delayed expression of IGFBP-5 relative to initiation of apoptosis, we postulate that IGFBP-5 functions as an inhibitor of cell proliferation rather than as a signal for apoptosis.