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PubMed1976

Modification of testicular steroid metabolism in the rat during gonadotrophin administration.

The administration of human chorionic gonadotrophins to adult rats stimulates the formation of testosterone, 7alpha-hydroxy-testosterone and 5alpha-androstanediol in incubated testes. When the gonadotrophins are injected for several days, the testosterone formation is maintained at a high level; however, the transformation to 7alpha-hydroxy-testosterone decreases progressively to subcontrol levels, while 5alpha-androstanediol is produced in greater amounts.

Androstane-3,17-diol↗
PubMed2000

Cloning and characterization of UROC28, a novel gene overexpressed in prostate, breast, and bladder cancers.

A novel gene, designated UROC28, was identified by an agarose gel-based differential display technique, and it was found to be up-regulated in prostate, breast, and bladder cancer. Expression of UROC28 was also up-regulated in prostate cancer cells in the presence of androgens as demonstrated by relative quantitative reverse transcription-PCR. The elevated expression of this gene was observed to increase in surgically removed tissues concomitantly with rising Gleason grade and was most elevated in metastatic tissue. UROC28 protein was detected in serum by Western slot blot analyses, and a significant higher UROC28 protein level was found in sera of prostate cancer individuals compared with normal individuals and individuals with nonmalignant prostatic hyperplasia. Northern analyses in normal tissues showed that the UROC28 cDNA hybridizes to two mRNAs at about 2.1 and 2.5 kb. Nucleic acid sequence analyses indicated that these two alternatively spliced mRNA variants differ only at the 3' untranslated region. These two mRNAs encode the same protein with 135 amino acids. Bioinformation analyses suggest that there is a possible transmembrane domain from amino acid aa34 to aa50, three protein kinase-C phosphorylation sites at aa62 (SQK), aa89 (TMK), and aa94 (SMK), and one myristylation site at aa118 (GLECCL). Genomic Southern hybridization and chromosomal mapping demonstrated that UROC28 is encoded by a single copy of gene at chromosome 6q23-24. In situ hybridization and immunohistochemistry experiments further confirmed up-regulation of this gene in prostate and breast cancers with the expression localizing to the glandular epithelium. This gene did not demonstrate increased expression in lung and colon cancer tissues.

3' Untranslated Regions↗
PubMed2001

Semiautomatic macroencapsulation of fresh or cryopreserved porcine hepatocytes maintain their ability for treatment of acute liver failure.

We have previously demonstrated that fresh or cryopreserved xenogeneic hepatocytes manually macroencapsulated in AN69 polymer and transplanted intraperitoneally in rats were able to improve the survival rate after 95% hepatectomy without immunosuppression. In addition, we developed a semiautomatic device where porcine hepatocytes were coextruded with AN69 hydrogel in order to macroencapsulate large amounts of cells. The purpose of the present study was to 1) test whether transplanted porcine hepatocytes macroencapsulated in this device remained functional as evaluated by their ability to prevent death from acute liver failure, and 2) compare the efficiency of cryopreserved or freshly isolated hepatocytes. Fresh or cryopreserved porcine hepatocytes were macroencapsulated in the semiautomatic device by coextrusion in AN69 polymer in 2-m minitubes containing 6 x 10(7) cells. Acute liver failure was induced in rats by two-step 95% hepatectomy. At the time of completion of liver resection, rats were either not transplanted with minitubes (control group I, n = 13), or were implanted with two minitubes containing culture medium (control group II, n = 11), hepatocytes killed by heat treatment (control group III, n = 10), coextruded fresh hepatocytes (group IV, n = 11), or coextruded cryopreserved hepatocytes (group V, n = 11), without immunosuppression. The survival rate at day 7 was between 0% and 31% in the three control groups. By contrast, coextruded fresh hepatocytes significantly improved the survival rate (group IV, 82%) as did cryopreserved cells (group V, 91% survival). In surviving rats, minitubes were explanted after 20 days; either fresh or cryopreserved hepatocytes appeared morphologically viable and their ultrastructure was preserved. Their detoxification capacities evaluated by the activity of the cyt P450 CYP3A4 were partly maintained. In conclusion, porcine hepatocytes macroencapsulated by coextrusion using a semiautomatic device and transplanted without immunosuppression were able to prevent death from acute liver failure in rats. Cryopreserved cells were as efficient as fresh hepatocytes.

Animals↗
PubMed1991

Species differences in the toxicity and cytochrome P450 IIIA-dependent metabolism of digitoxin.

In rats, cytochrome P450 (P450) IIIA enzymes are an important determinant of digitoxin toxicity. Induction of these liver microsomal enzymes decreases the toxicity of digitoxin by increasing its oxidative cleavage to digitoxigenin bis- and monodigitoxoside (dt2 and dt1). The present study shows that the susceptibility of different mammalian species to digitoxin toxicity is inversely related to liver microsomal P450 IIIA activity (measured as testosterone 6 beta-hydroxylase activity). Based on this correlation, we correctly predicted that hamsters, which have the highest P450 IIIA activity, are extremely resistant to digitoxin toxicity. To further examine the relationship between digitoxin toxicity and P450 IIIA activity, the pathways of digitoxin metabolism catalyzed by liver microsomes from nine mammalian species were examined by high performance liquid chromatography. The overall rate of digitoxin metabolism varied approximately 90-fold and followed the rank order: hamster greater than rat greater than guinea pig greater than dog greater than mouse approximately monkey greater than rabbit approximately cat greater than human. The qualitative differences in digitoxin metabolism were as striking as the quantitative differences. Formation of 16- and/or 17-hydroxydigitoxin was the major pathway of digitoxin oxidation catalyzed by liver microsomes from hamster, guinea pig, rabbit, cat, dog, and cynomolgus monkey. Guinea pig and, to a lesser extent, hamster liver microsomes also converted digitoxin to an unknown metabolite, the formation of which was catalyzed by P450. None of the species examined catalyzed the 12-hydroxylation of digitoxin to digoxin at a high rate. Similarly, none of the species examined catalyzed a high rate of conversion of digitoxin to dt2, with the notable exception of the rat. However, dt2 formation was the major pathway of digitoxin metabolism catalyzed by human liver microsomes, although humans were much less active (approximately 2%) than rats in this regard. The rate of dt2 formation varied approximately 41-fold among 22 samples of human liver microsomes, which was highly correlated (r = 0.841) with the rate of testosterone 6 beta-hydroxylation. Antibody against rat P450 IIIA1 inhibited the high rate of dt2 formation by rat liver microsomes and the low rate catalyzed by mouse, guinea pig, dog, monkey, and human liver microsomes. In contrast, anti-P450 IIIA1 did not inhibit the 12-, 16-, or 17-hydroxylation of digitoxin (or the formation of the unknown metabolite), despite the fact that anti-P450 IIIA1 strongly inhibited (greater than 70%) the 6 beta-hydroxylation of testosterone by liver microsomes from each of the species examined (except rabbit liver microsomes, which were inhibited only approximately 30%).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1977

[Hormones and hair growth in man].

A literature review tries to diminish the ambiguity between hormones and hairs. Therefore the hormonal action in general (regulation of the protein synthesis indirectly by enzymatical regulation of the AMP-system or directly by hormones as active metabolites) and the methods to explore hormones-hair-interaction are discussed. Hormones pertaining to the pituitary-adrenal-gonadal axis are regarded as the paramount hormones; therefore the results of research in testosterone, 5-alpha-dihydrotestosterone, estrogens, progesterone, glucocorticoids, the hypophysis and its tropins are recapitulated. The main disorders of hair-growth, pattern baldness and "idiopathic" hirsutism, which would be dependent on a similar disturbance of androgen metabolism, are discussed. Pathology in hair-growth may arise in any point of the cascade of hormone action.

Adenylyl Cyclases↗
PubMedDate not supplied

Influence of an aromatase inhibitor (4-acetoxy-4-androstene-3,17-dione) on experimentally induced impairment of spermatogenesis in immature rats.

Subcutaneous treatment of immature male rats with an estrogen precursor, 19-hydroxy-testosterone (19-OHT), at a daily dose of 1 mg/animal for 14 days leads to a significant decrease in the weight of testis, ventral prostate and seminal vesicle. The peripheral levels of LH are lowered. Testicular histology indicates that the effects of 19-OHT are very similar to the known of effect induced by estradiol-17 beta. 19OHT induces a marked impairment of spermato- and spermiogenesis. The maturation division is completely inhibited. The effect of 19-OHT on spermatogenesis is partially reversed by concomitant administration of an aromatase inhibitor (4-acetoxy-4-androstene-3.17-dione, (4-AA] at a dose of 1 mg/animal/day s.c. Meiotic activity is restored, and the weights of genital organs and the serum LH values increase. 4-AA alone has no appreciable effect on the parameters examined in this study. The present results suggest that specific inhibitors of estrogen biosynthesis might not only be useful to investigate the patho-physiological role of estrogens on spermatogenesis, but also be suitable to some extent for the treatment of estrogen-induced infertility in men suffering from idiopathic oligozoospermia.

Androstenedione↗
PubMed1979

Sex steroid control of intermale fighting in mice.

The data presented here are based on over 700 mice and employed over 13,000 injections. The results obtained provide good evidence that the influences of sex steroids on fighting motivation in aggressive mice are discrete from the somatic influences of these hormones. Further, it seems possible that some of the effects of naturally occurring endogenous androgens in the mouse are consequent upon local neural aromatization of these compounds to estrogenic metabolites, before they exert an influence on aggressive motivation. It seems possible that this is a physiological effect as well as a consequence of pharmacological influence, as the doses of steroid employed in this present study are quite low. However, this model of hormone action cannot be the entire story, as 5 alpha DHT is behaviorally effective even though its A ring cannot be aromatized. Aggressive mice seem useful behavioral models for these effects. These studies indicate some of the likely sources of variability in the literature, as well as providing a number of considerations for clinical behavior therapy. They also indicate some of the features of steroid hormones (such as an aromatized A ring; the presence of a hydroxyl group at position 19; the influence of alpha hydroxyl groups, etc.) which may change the behavioral and somatic influences of these compounds.

Aggression↗
PubMed1996

Models of estrogen receptor regulation by estrogens and antiestrogens in breast cancer cell lines.

The expression and stability of the estrogen receptor (ER) is the result of a complex process that is modulated by estrogens and antiestrogens. Regulation of the steady-state ER mRNA and protein levels in breast cancer cells appears to be the result of either of two distinct regulatory mechanisms. Estrogen exposure causes a rapid down-regulation of the steady-state level of ER mRNA and protein in model I regulation, as exemplified by the MCF-7:WS8 cell line. Conversely, in model II regulation, as observed in the T47D:A18 cell line, estrogen exposure causes an increase in the steady-state ER mRNA level and a maintenance of the ER protein level. In both these cell lines, the nonsteroidal antiestrogen 4-hydroxytamoxifen has little effect on the mRNA level but causes a net accumulation of the ER protein over time. In contrast, the pure antiestrogen ICI 182,780 causes a dramatic reduction of the ER protein in both the MCF-7:WS8 and T47D:A18 cell lines. This loss has little effect upon the ER mRNA level in the MCF-7:WS8 cells but leads to a decline in the ER mRNA in the T47D:Al8 cells. The estrogen-independent MCF-7:2A cell line, which has adapted to growth in estrogen free media, expresses two forms of the ER, a wild-type Mr66,000 ER and a mutant Mr77,000 ER (ER77). ER77 is the product of a genomic rearrangement resulting in a tandem duplication of exons 6 and 7 (J. J. Pink et al, Nucleic Acids Res., 24:962-969,1996). This exon duplication has abolished ligand binding by this protein. Here we demonstrate that the loss of ligand binding has eliminated the effects of 4-OHT and ICI 182,780 on the steady-state ER77 protein level. However, in the MCF-7:2A cells, antiestrogens affect the wild-type ER protein in the same manner as observed in the MCF-7:WS8 and T47D:A18 cells. Estrogen regulates the ER mRNA and wild-type ER and ER77 proteins in the MCF-7:2A cells in the same manner as observed in the MCF-7:WS8 cells. Interestingly, treatment of the MCF-7:2A cells with ICI 182,780 causes a slight increase in ER mRNA, which is reflected in a net increase in the ER77 protein but a dramatic decrease in the wild-type ER. The models presented here describe the response of two human breast cancer cell lines in short-term studies. These distinct regulation pathways are predictive of the response of these cell lines to long-term estrogen deprivation. This study illustrates two alternative regulation pathways that are present in ER-positive, estrogen-dependent breast cancer cells. This variable response highlights the diversity of responses potentially present in the heterogeneous cell populations of clinically observed breast cancer.

Adenocarcinoma↗
PubMed1995

Variants of the human prostate LNCaP cell line as tools to study discrete components of the androgen-mediated proliferative response.

Androgens regulate the proliferation of their target cells through a sequential two-step mechanism. In the first step, androgens increase proliferation rates; following this proliferative response, a second step of proliferative shutoff ensues. Human prostate LNCaP cell variants were used to assess whether the proliferative and shutoff effects of androgens could be segregated selectively by manipulating the hormonal milieu. The LNCaP-FGC and LNCaP-LNO cell lines were derived from the same biopsy specimen but exhibited different proliferative responses. Cell proliferation was inhibited by treatment with 10% charcoal-dextran stripped human serum in the LNCaP-FGC variant but not in LNCaP-LNO cells. Physiological androgen concentrations induced a proliferative shutoff in LNCaP-LNO cells (G1 arrest), an effect also expressed by LNCaP-FGC cells. This G1 arrest was irreversible in the LNCaP-FGC variant but was reversed upon androgen withdrawal in LNCaP-LNO cells. A new variant (LNCaP-TJA) was selected from LNCaP-LNO cells treated with 30 nM methyltrienolone for 4 months; these cells proliferated maximally regardless of the presence of androgens. All three cell variants had functional androgen receptors, and androgens induced prostate-specific antigen secretion. The androgen-induced proliferative shutoff in LNCaP-FGC and LNO cells was partially antagonized by antiandrogens and was not mediated by autocrine factors. Finally, the variant LNCaP cell lines described herein are probably representative of phenotypes present in prostate cancer patients during the course of this disease and may arise from selective pressure imposed by therapeutic protocols aimed at modifying the hormonal milieu of the host.

Androgen Antagonists↗