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)

Flutamide, a nonsteroidal antiandrogen, was given to 11 men with prostate cancer, in doses of 750 to 1500 mg daily for 0.5--7 months. Four patients had a clinical remission and seven showed no response. All the patients showed a profound change in the peripheral metabolism of testosterone: markedly increased conversion to androsterone (A) and correspondingly decreased conversion to etiocholanolone (E); the A/E ratio rose to levels never before observed consistently in any group of healthy or diseased humans. This change was probably due to alteration by flutamide of the relative activities of steroid 5alpha and 5beta reductase in favor of the former. 24-Hour mean plasma testosterone was increased in five of the six patients studied for this parameter, for the group as a whole, testosterone rose from 279 ng/dl to 484 ng/dl (P less than .05). 24-Hour mean values for plasma dihydrotestosterone, dehydroisoandrosterone, LH and FSH showed no significant change, for the group as a whole, in the same six patients. Since flutamide did not change the metabolic clearance rate or volume of distribution of testosterone tracers, the increased plasma levels of the hormone were probably due to increased production.
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PMID:The effect of flutamide on testosterone metabolism and the plasma levels of androgens and gonadotropins. 59 17

A number of chemotherapeutic agents have been tested in two systems which could be useful as models in the search for effective drugs for cancer of the prostate. One system involved the effects of the administered drugs on rat prostatic 5 alpha-reductase and arginase activities. Since both enzymic systems are androgen dependent and essential for prostatic function and anatomy, the effectiveness of a drug in these systems could be indicative of its value in the treatment of prostatic cancer. Michaelis constants were obtained with Lineweaver-Burk plots and the conclusions are based on a comparison of these plots with those of the controls. Thus, the following results were obtained: (a) isophosphamide, bleomycin, and procarbazine produced definite inhibition of 5 alpha-reductase in either or both the ventral and dorsolateral glands of the rat; (b) 5-fluorouracil, vincristine, bleomycin, procarbazine, adriamycin, and hexamethyl-melamine inhibited arginase activity significantly in both glands; (c) streptozotocin and 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (NSC-45388) produced inhibition of arginase in the ventral gland only; (d) in contrast to the noncompetitive or uncompetitive inhibition of most of the drugs, particularly in the ventral gland, procarbazine, hexamethylmelamine, bleomycin, adriamycin, and NSC-45388 produced competitive inhibition of arginase in the dorsolateral gland; and (e) seven of the drugs led to an activation of 5 alpha-reductase (5-fluorouracil, vincristine, NSC-45388, hexamethylmelamine, CCNU, streptozotocin, and diglycolaldehyde). The second model system utilized the deposition of labeled estriol and testosterone in the dog prostate and the effects of drug therapy as a possible index of effectiveness in prostatic cancer. Streptozotocin and procarbazine definitely interfered with the deposition of both estriol and testosterone. On the basis of the data obtained, the model systems investigated by us could potentially serve as reliable indicators for the clinical use of drugs against cancer of the prostate.
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PMID:Potential test systems for drugs against prostatic cancer. 113 3

Epidemiological studies strongly support the contention that surgical castration prior to age forty prevents both benign prostatic hypertrophy (BPH) and prostate cancer. 5 alpha-Reductase deficiency in humans, an experiment of nature, is an uncommon genetically transmitted disorder in which prostate size remains very small throughout adult life. A 5 alpha-reductase inhibitor, finasteride, has recently been shown in double-blind, placebo-controlled trials in patients with BPH to statistically decrease prostate size and improve clinical symptoms in comparison to placebo controls. In the untreated BPH prostate, tissue levels of dihydrotestosterone (DHT) and testosterone (T) averaged 4.2 and 0.2 ng/g, respectively. Following one week of finasteride therapy, T levels rose to a mean of 1.32 ng/g while DHT levels decreased to 0.62 ng/g. These values contrast with values in prostate tissue from surgical castrates in which DHT and T values average 1.14 ng/g and 0.1 ng/g, respectively. If we use the relative binding affinity of T and DHT to the androgen receptor as a criterion of biological androgen potency, T would appear to be one-fourth as potent as DHT. Using this 1:4 ratio to convert prostatic T to a biologically equivalent amount of prostatic DHT, the total biologically active DHT equivalent in the prostate following one week of finasteride averages 0.95 ng/g compared to a mean of 1.14 ng/g in surgical castrates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Castration-like effects on the human prostate of a 5 alpha-reductase inhibitor, finasteride. 128 93

Prostate cancer is a major health problem for the aging male population. Despite hormonal dependence, the inevitable emergence of androgen insensitive tumors, which have a dismal prognosis, highlights the need to develop prevention strategies such as chemoprevention. An acceptable agent must interfere with either the process of carcinogenesis or tumor growth, and have minimal toxicity. In clinical studies, 5 alpha-reductase inhibitors have been shown to suppress serum and intraprostatic levels of dihydrotestosterone, an important promoter of prostate cancer, leading to reduction in prostate size and suppression of glandular cell activity as measured by prostate specific antigen secretion. In addition, 5 alpha-reductase inhibitors have demonstrated an excellent safety profile and tolerability in 12 month controlled clinical trials. No significant metabolic effects have been observed in gonadotropin secretion, spermatogenesis, serum lipids or glucose tolerance. The efficacy and safety of 5 alpha-reductase inhibitors in studies to date, combined with the androgen dependence of tumor production, strongly supports investigating their use for chemoprevention of prostate cancer.
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PMID:Chemoprevention strategies for prostate cancer: the role of 5 alpha-reductase inhibitors. 128 94

Similarities between pancreatic, prostate and mammary tumors in possession of steroidal receptors and enzymes led to investigation of the responsiveness of pancreatic cancer to steroids with potential for tumor inhibition. The compounds were tested in vitro against human (HPAF and PANC-1) and hamster (HP-1) pancreatic ductal tumor cell lines using a colorimetric enzyme-based assay (MTT) to assess both cytotoxic and cytostatic effects and the 3H-thymidine uptake assay for cytostatic effects. Only certain 6-methylenic steroidal 3-ketones and the anti-estrogen tamoxifen citrate exerted appreciable anti-tumor effects. Marked cytotoxic and cytostatic activity was shown by some 6-methylenic congeners of progesterone, testosterone and its acetate, and 4-androstene-3,17-dione on both human and hamster pancreatic tumor cell lines. In contrast to prostate cancer, testosterone, but not 5 alpha-dihydrotestosterone, enhanced growth of the well differentiated HPAF cell line as well as the poorly differentiated PANC-1 cell line. It is therefore surprising that the 6-methylene derivative of testosterone acetate, which is both a potent androgen and 5 alpha-reductase inhibitor, is a very active tumor inhibitor in our assay.
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PMID:Growth modulatory effects of some 6-methylenic steroids on human and hamster pancreatic adenocarcinoma cells in vitro. 133 65

The incidence of prostate cancer varies widely between countries and ethnic groups. Black-Americans have the highest incidence rates world wide, whereas native Japanese have among the lowest. The reasons for this risk differential are unknown, although we have previously shown that higher circulating testosterone concentrations in young adult black men compared with young adult white men may explain the underlying differences in subsequent prostate cancer incidence between these two populations. We have now compared serum testosterone concentrations in young adult Japanese men with those of young adult whites and blacks, but found no significant differences. However, these white and black men had significantly higher values of 3 alpha, 17 beta androstanediol glucuronide (31% and 25% higher, respectively) and androsterone glucuronide (50% and 41% higher, respectively) than Japanese subjects. These two androgens are indices of 5 alpha-reductase activity. Our results raise the possibility that reduced 5 alpha-reductase activity has a role in producing the low prostate cancer incidence rates among Japanese. This finding may have important implications for prostate cancer prevention.
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PMID:5-alpha-reductase activity and risk of prostate cancer among Japanese and US white and black males. 134 96

Recent approaches to inhibiting testicular function for the purposes of male contraception, treatment of precocious puberty, and palliation of prostatic disease (prostatic carcinoma and benign prostatic hypertrophy) are addressed. By refined approaches inhibition of testicular function can be achieved at points of the reproductive axis, including the hypothalamus, pituitary testis, and peripheral sites of androgen action. Azoospermia and severe oligozoo/azoospermia can be achieved with combined gonadotropin releasing hormone (GnRH) antagonists and replacement doses of testosterone. In recent developments with reversible hormonal agents, the use of gonadotropin inhibitors for male contraception was based on observations that hypophysectomized and hypogonadotropic men (deficient in luteinizing hormones [LH] and follicle stimulating hormone [FSH] are aznoospermic. Long term suppression of LH and FSH with steroids and GnRH analogues has proven to be reversible with discontinuation of medication suggesting that inhibitors of LH and FSH secretion would prove to be effective and reversible male contraceptive agents. Steroid hormones suppress gonadotropin output and secondarily suppress testicular function including the production of spermatozoa. The androgen testosterone enanthate in doses of 200 mg every week suppressed LH and FSH concentrations to 50% of pretreatment baseline. True precocious puberty can be managed more effectively by suppression of gonadotropin secretion with GnRH analogues. Metastatic prostate cancer, previously treatable with either castration or estrogens, now responds to suppression of androgen secretion. Benign prostate hyperplasia previously manageable only by surgery can respond favorably to 5 alpha-reductase inhibitors and/or selective alpha-adrenergic blockers in some patients according to recent data.
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PMID:Developments in the control of testicular function. 137 67

A total of 28 untreated patients with asymptomatic, stage D prostate cancer was randomized in a double-blinded fashion to receive finasteride (10 mg. per day), a 5 alpha-reductase inhibitor or placebo. Patients were evaluated at 3-week intervals by rectal examination, and serum prostate specific antigen (PSA) and prostatic acid phosphatase (PAP) levels, and at 6-week intervals by bone scan and transrectal ultrasound determinations of prostatic volume. Patients stopped the medication at week 6 at the discretion of the investigator when PSA levels increased from baseline. After 12 weeks all patients were reevaluated. Of the patients 13 received finasteride and 15 received placebo. The 2 groups did not differ statistically with respect to patient age, initial PSA and PAP level, or the extent of metastases on initial bone scan. A statistically significant decrease in the median percentage change from baseline in PSA at weeks 3 and 6 occurred in the finasteride group compared to the placebo group (-22.9% versus -2.9% and -15.1% versus +11.7%, respectively, p less than 0.05). Finasteride had no effect upon PAP, serum testosterone, prostatic volume or appearance of bone scans. A decrease in serum PSA in the finasteride treatment group suggests that finasteride exerts a minor effect in patients with prostate cancer. This effect does not approach that seen with medical or surgical castration yet because of the potency preserving feature and the lack of toxicity finasteride may warrant further study in the treatment of prostate cancer.
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PMID:Multicenter, randomized, double-blind, placebo controlled study to investigate the effect of finasteride (MK-906) on stage D prostate cancer. 138 74

The best known activity of steroid 5 alpha-reductase is the transformation of testosterone into dihydrotestosterone, the most potent androgen. Two types of human steroid 5 alpha-reductase cDNAs and the type I gene have previously been isolated and characterized. This report describes the isolation and characterization of the human type II 5 alpha-reductase gene, the gene most likely responsible for male pseudohermaphroditism due to 5 alpha-reductase deficiency as well as the one presumed to be involved in a major androgen-related diseases such as prostate cancer and benign prostatic hyperplasia. The type II 5 alpha-reductase gene contains five exons of 352, 164, 102, 151 and 1695 bp, respectively, which share 43.8% to 64.1% homology with exons of the corresponding type I gene. These exons are separated by four introns of greater than 29, and approximately 2.3, 2.0 and 3.0 kb. Analysis of primer extension products by polyacrylamide gel electrophoresis as well as by subcloning and sequencing reveals a start site located 71 nucleotides upstream the ATG initiating codon.
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PMID:Structure of human type II 5 alpha-reductase gene. 150 84

Liarozole reduced tumor growth in the androgen-dependent Dunning-G and the androgen-independent Dunning MatLu rat prostate carcinoma models as well as in patients with metastatic prostate cancer who had relapsed after orchiectomy. In vitro, liarozole did not have cytostatic properties, as measured by cell proliferation in breast MCF-7 and prostate DU145 and LNCaP carcinoma cell lines. It did not alter the metabolism of labeled testosterone i.e. the 5 alpha-reductase in cultured rat prostatic cells. In mouse F9 teratocarcinoma cells liarozole did not show any retinoid-like properties but enhanced the plasminogen activator production induced by retinoic acid. Furthermore, liarozole and retinoic acid similarly reduced the growth of the androgen-dependent Dunning-G tumor in nude mice and inhibited tumor promotion elicited by phorbol ester in mouse skin. These data have raised the hypothesis that the antitumoral properties of liarozole may be related to inhibition of retinoic acid degradation, catalyzed by a P-450-dependent enzyme that is blocked by the drug.
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PMID:Experimental studies with liarozole (R 75,251): an antitumoral agent which inhibits retinoic acid breakdown. 152 60


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