Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Almost 60% of elderly men suffer from symptoms of BPH, which have significant impact on their daily lives. Transurethral resection of the prostate (TURP) is currently the most effective therapy for relieve of obstruction and obstructive symptoms. Morbidity of TURP and disappointing results in patients with mild or moderate symptoms make surgery not suitable for all patients. 2 groups of drugs were currently developed, and showed efficacy in double-blinded placebo-controlled studies: alpha-blocking agents and 5 alpha-reductase inhibitors. Inhibition of alpha-adrenoreceptors significantly increases urinary flow rates and improves symptoms of BPH. Long-acting drugs, who selectively block alpha 1-adrenoreceptors (terazosin, doxazosin, tamsulosin) have the advantage, when compared with non-selective-alpha-blockers, that they have generally less adrenergic side effects. After intake alpha-adrenorceptor antagonists develop almost immediate action. 5 alpha-reductase inhibitors (finasteride) reduce prostatic size by 27%, they increase urinary flow rates and improve prostatic symptom scores, whilst adverse effects are extremely low. Full medical action is after 4 to 6 weeks. Both, alpha-Blockers and 5 alpha-reductase inhibitors need permanent administration for maintenance of action. Yet, synergistic effects, using their different modes of action have not been demonstrated after application of both drugs. Herbal products have not proved efficacious inspite of singular surprising results in clinical trials, their efficacy to treat BPH related symptoms was classified as placebo alike. Prior to therapy urological diagnosis and exclusion of prostate cancer is mandatory. Pharmacotherapy with alpha 1-adrenoreceptor antagonists and 5 alpha-reductase inhibitors have a place in the management of BPH patients with mild to moderate disease, who are bothered by their symptoms, or for those awaiting or wishing to delay surgery.
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PMID:[Current drug therapy of benign prostatic hyperplasia]. 876

The prevalence of BPH is high in elderly men with more than 60% of patients over the age of 60 experiencing some form of prostatism. Balancing the superior benefit of TUR/P are the small but significant risks and complications of surgery and the high cost of the procedure. The WHO guidelines recommend finasteride or alpha-blockers as treatment options for men with bothersome symptoms. Finasteride therapy reduces the volume of the hyperplastic prostate gland by more than 20%, improves the urinary flow rate and the symptoms associated with bladder outlet obstruction. Although statistically significant, results obtained with finasteride are just slightly better than placebo and TUR/P still offers the greatest improvement of symptoms. Finasteride is well tolerated and adverse events are rare. However, it decreases serum PSA (prostate specific antigen) by 50%, suggesting careful monitoring and exclusion of prostate cancer before initiation and during therapy. Current research is focusing on developing new 5-alpha-reductase inhibitors (type I and II) using polyunsaturated fatty acids and nonsteroidal inhibitors. Given the multifactorial nature of BPH, further clinical trials combining 5-alpha-reductors inhibitors and 5-alpha-receptor blockers are still needed.
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PMID:[The effect of 5-alpha-reductase inhibitors on benign prostatic hyperplasia]. 876 1

The conversion of testosterone (T) to dihydrotestosterone (DHT) has been demonstrated to be catalysed by at least two isoforms of human steroid 5 alpha-reductase, designated types I and II. Type II 5 alpha-reductase expression predominates in human accessory sex tissues, localized to the fibromuscular stromal compartment. The type I isoform predominates in skin, prostatic epithelia and, to a lesser extent, in prostatic fibromuscular stroma. The significance of the type I isoform to prostatic cellular growth and function remains undefined. In cultured DU145 cells, we evaluated the metabolism of [14C]-T and demonstrated the time-dependent formation of [14C]-DHT. Oxidative metabolism (conversion of [14C]-T to [14C]-androstenedione) and the formation of conjugated androgen metabolites occurred at a relatively low rate in the DU145 cells. Using human type I 5 alpha-reductase cDNA, Northern blot analysis of DU145 cell mRNA revealed high levels of type I isoform expression. Analogous probing of the DU145 cells with a human 5 alpha-reductase II cDNA failed to reveal expression of the type II isoform. The expression of functional type I activity has been confirmed pharmacologically using isoform-selective 5 alpha-reductase inhibitors. Reductive metabolism of [3H]-T in the DU145 cells was inhibited in a concentration-dependent manner by LY306089, a potent non-steroidal type I-selective inhibitor (IC50 = 10.0 nM). SKF105657, a steroidal type II-specific inhibitor was distinctly less active at inhibiting [3H]-DHT formation. LY306089 was a non-competitive inhibitor of type I 5 alpha-reductase in DU145 cellular homogenates with an apparent Ki value of 4.0 nM. These studies have identified and pharmacologically defined type I 5 alpha-reductase activity in an androgen-insensitive prostatic cancer cell line and provide the basis for additional investigations into the significance of type I 5 alpha-reductase to human prostatic pathophysiology.
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PMID:Characterization of type I 5 alpha-reductase activity in DU145 human prostatic adenocarcinoma cells. 880 1

Finasteride is a potent 5 alpha-reductase inhibitor that has shown limited success in men treated for benign prostatic hyperplasia (success is defined as a decrease in the symptoms associated with urinary tract obstruction, and as increases in the urinary flow rate). 5 alpha-reductase is necessary for the prostatic conversion of testosterone to dihydrotesterone (DHT), the specific steroid that stimulates prostate transitional zone growth. Finasteride reduces the size of the prostate gland by 20%, but this does not correlate well with improvement in symptoms. Finasteride is well absorbed after oral administration and, while the rate of absorption may be slowed postprandially, the presence of food has no effect on the total bioavailability. Finasteride is widely distributed, but since its pharmacological effects are very specific to inhibition of 5 alpha-reductase, and since only the prostate gland, the scalp, and the genital skin contain high concentrations of this enzyme, few adverse reactions will be seen in other organ systems. Finasteride undergoes extensive hepatic metabolism to essentially inactive metabolites, which are eliminated through the bile and urine. The terminal elimination half-life (t1/2z) is 4.7 to 7.1 hours; but despite this, slow accumulation occurs with multiple doses. Values of t1/2z are higher in elderly men, but no dosage adjustments are necessary. Likewise, no dosage adjustments are necessary for patients with renal dysfunction, since the metabolites which accumulate are relatively inactive and well tolerated, and because greater faecal excretion of the metabolites occurs in these patients. The effect of hepatic dysfunction on the metabolism of finasteride is unknown. Therapeutic doses of finasteride produce a rapid and pronounced effect in reducing both plasma and prostate tissue levels of DHT. Doses below 0.5 mg/day do not produce much suppression of DHT levels, and doses above 5 mg/day have little additional benefit. A single dose of finasteride suppresses serum DHT levels for up to 4 days, longer than would be expected from the serum terminal elimination half-life (t1/2z) of the drug: this is probably due to the high affinity that finasteride has for the 5 alpha-reductase enzyme. Serum testosterone levels increase in patients receiving finasteride, but are not normally outside the upper limits of the normal range. Serum prostate-specific antigen (PSA) levels decrease with finasteride administration; the baseline for investigation of prostate cancer with elevated PSA levels should be one-half of the normal range. In responders to finasteride, the prostate gland shrinks in volume by about 20%, urinary flow rate improves by approximately 3 ml/s, and symptoms are relieved. The response to finasteride appears to be maximal at doses of 5 mg/day. For most men receiving finasteride, these effects will persist for at least the 5 years that long term studies have been conducted. Serum DHT levels increase again when finasteride therapy is discontinued, probably resulting in the return of the hyperplasia, decreased urine flow and obstructive symptoms. Finasteride is well tolerated, with loss of libido and sexual potency being the most commonly reported adverse reactions. No drug interactions with finasteride have been reported.
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PMID:Clinical pharmacokinetics and pharmacodynamics of finasteride. 884 25

Finasteride, an orally active type II 5 alpha-reductase (5 alpha R) inhibitor, blocks conversion of testosterone (T) to dihydrotestosterone (DHT). The utility of finasteride in effectively managing benign prostatic hyperplasia has been documented. Use of the drug results in reduced prostate volume and serum levels. Patients receiving finasteride should be monitored with periodic digital-rectal examination (DRE) and serum PSA measurement. Patients with a sustained increase in serum PSA or an abnormal DRE require additional evaluation. There is no evidence that use of finasteride has an adverse effect on prostate cancer detection, if the drug's effect on serum PSA is recognized and accounted for.
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PMID:Evaluation of men on finasteride. 886 75

When the human prostate cancer cell line, LNCaP 104-S, the growth of which is stimulated by physiological levels of androgen, is cultured in androgen-depleted medium for > 100 passages, the cells, now called LNCaP 104-R2, are proliferatively repressed by low concentrations of androgens. LNCaP 104-R2 cells formed tumors in castrated male athymic nude mice. Testosterone propionate (TP) treatment prevented LNCaP 104-R2 tumor growth and caused regression of established tumors in these mice. Such a tumor-suppressive effect was not observed with tumors derived from LNCaP 104-S cells or androgen receptor-negative human prostate cancer PC-3 cells. 5 alpha-Dihydrotestosterone, but not 5 beta-dihydrotestosterone, 17 beta-estradiol, or medroxyprogesterone acetate, also inhibited LNCaP 104-R2 tumor growth. Removal of TP or implantation of finasteride, a 5 alpha-reductase inhibitor, in nude mice bearing TP implants resulted in the regrowth of LNCaP 104-R2 tumors. Within 1 week after TP implantation, LNCaP 104-R2 tumors exhibited massive necrosis with severe hemorrhage. Three weeks later, these tumors showed fibrosis with infiltration of chronic inflammatory cells and scattered carcinoma cells exhibiting degeneration. TP treatment of mice with LNCaP 104-R2 tumors reduced tumor androgen receptor and c-myc mRNA levels but increased prostate-specific antigen in serum- and prostate-specific antigen mRNA in tumors. Although androgen ablation has been the standard treatment for metastatic prostate cancer for > 50 years, our study shows that androgen supplementation therapy may be beneficial for treatment of certain types of human prostate cancer and that the use of 5 alpha-reductase inhibitors, such as finasteride or anti-androgens, in the general treatment of metastatic prostate cancer may require careful assessment.
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PMID:Human prostate tumor growth in athymic mice: inhibition by androgens and stimulation by finasteride. 887 18

AR gene mutations occur in both early-stage prostate cancers (28, 51, our unpublished data) and late-stage disease (36, 37, 55-57). One common feature is that both types of mutations retain ligand-dependent transcriptional activity. We speculate that AR mutations may characterize a more aggressive disease, or confer an ability to survive androgen ablation therapy. A large percentage of tumors appears to have no AR gene mutation, but the possibility has not been ruled out that tumors without an AR gene mutation may nonetheless produce variant AR, for example, by alternative splicing. The apparent absence of AR gene mutations in the majority of early-stage tumors indicates that the role of androgen in the development of clinical prostate cancer is mediated predominantly by a normal AR gene, which exists as multiple alleles that differ in glutamine and glycine repeat length, and that potentially differ in signal-transducing activity. Glutamine and glycine repeat length may thereby modulate the effect of androgen on tumor cell proliferation. The effect of glutamine and glycine repeat length on AR function may determine the sensitivity of tumor cells to existing tissue levels of dihydrotestosterone, but tissue dihydrotestosterone levels depend on circulating androgen levels and the amount of 5 alpha-reductase activity in the tissue. Therefore, although potential AR activity may be affected by the length of the glutamine and/or glycine repeat, actual AR activity will depend also on these other factors.
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PMID:Androgen receptor mutations in prostate cancer. 889 47

Androgen-receptor (AR) gene mutations have been found in clinical prostate cancer, both prior to hormonal therapy and in hormone-refractory disease that persists despite androgen-ablative therapy. Thus, mutations that are present in late-stage disease might arise prior to therapy rather than as a result of therapy. A common feature of mutations in untreated prostate cancer and in hormone-refractory prostate cancer is that the AR retains activity as a ligand-dependent transcription factor. Some AR mutations in prostate cancer show broadened ligand specificity, such that the transcription-factor activity of the AR can be stimulated not just by dihydrotestosterone (DHT) but also by estradiol and other androgen metabolites that have a low affinity for the AR. The activation of mutant AR by estrogen and weak androgens could confer on prostate cancer cells an ability to survive testicular androgen ablation by allowing activation of the AR by adrenal androgens or exogenous estrogen. Such mutations might confer an advantage even prior to androgen ablation, since prostate cancer has lower levels of 5 alpha-reductase and, therefore, of DHT, than normal. Thus, AR mutations that occur prior to therapy may characterize a more aggressive disease. A large percentage of tumors appear to have no AR gene mutation. In tumors without an AR gene mutation, AR function might be affected via other mechanisms (e.g., AR gene amplification, which could increase the amount of AR activity at a given DHT level). Importantly, the apparent absence of AR gene mutations in the majority of earlystage tumors indicates that the role of androgen in the development of clinical prostate cancer is mediated predominantly by a normal AR gene. There are actually multiple alleles of the normal AR gene; these allelic variants differ in glutamine and glycine repeat length in the transactivation domain of the protein, and they may differ in signal-transducing activity. The glutamine and glycine repeat length may thereby modulate the effect of androgen on tumor-cell proliferation that occurs during clonal expansion.
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PMID:Androgen-receptor gene structure and function in prostate cancer. 891 73

This study represents a continuing effort to find a new biomarker for the diagnosis and management of prostatic cancer. Polyclonal antibodies were prepared to a peptide (CAKP) representing amino acids 28 to 43 of the 5 alpha-reductase type 2 isozyme. Using immunoaffinity-purified antibodies, the sera of 62 patients were examined by Western blot following polyacrylamide gel electrophoresis. A positive band was detected in the sera of several patients at 42 kDa compatible with the purified native glycosylated 5 alpha-reductase type 2. These bands were nullified on coincubation of the antibody with the CAKP peptide. Analysis by high-performance liquid chromatography and amino acid sequencing by N-terminal Edman degradation of the immunoaffinity-purified antigen to the antipeptide antibodies of a patient with adenocarcinoma of the prostate suggests that the 5 alpha-reductase type 2 isozyme may be linked to an immunoglobulin. An identical immunoaffinity-purified antigen to the CAKP peptide was isolated from a section of prostatic tissue from a different patient showing benign prostatic hypertrophy with severe dysplasia. It is suggested that an immunological response to the 5 alpha-reductase type 2 isozyme was elicited in both instances.
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PMID:Immunochemical detection of 5 alpha-reductase in human serum. 891 60

Many of the most common cancers occur in sites that are under hormonal regulation by the steroid sex hormones. These include the breast, ovary, endometrium and possibly the colon for women, and the prostate and testes for men. Much information on chemoprevention of these cancers has accrued indirectly as a result of the use of estrogens and progestagens for contraception or postmenopausal hormone replacement therapy. Estrogen-based contraceptives clearly reduce the risk of ovarian cancer, but without an opposing progestagen they increase the risk of endometrial cancer. Progestagens reduce the risk of endometrial cancer and when used premenopausally appear to be able to more than counteract the carcinogenic effect of exogenous estrogens at this site. The effect of oral contraceptives on breast cancer appears to be quite minimal, but probably increases risk when taken for long periods at a young age. Recent studies suggest that the use of an agonist of leuteinizing hormone releasing hormone as a contraceptive may reduce the risk of breast cancer. Estrogens used in postmenopausal hormone replacement therapy increase the risk of both breast and endometrial cancer, but addition of a progestagen may counteract the increased risk to the endometrium. The agent most intensively under study for breast cancer prevention is tamoxifen, which has proven effectiveness as a therapeutic agent. When taken for more than two years it has been shown to reduce the occurrence of new contralateral tumours by about 50% in women who have had breast cancer. Three large international trials are currently evaluating its role in a preventive setting. For men, interest has centred on the use of 5 alpha-reductase inhibitors to block the prostatic conversion of testosterone to dehydrotestosterone and potentially inhibit the development of prostate cancer. The 5 alpha-reductase inhibitor finasteride is currently under test in a prevention trial.
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PMID:Medicinal drugs with hormonal activity as chemopreventive agents. 892 22


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