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Fertility and Sterility Aug 1976Luteal metabolism was investigated in corpora lutea of early pregnant rats treated with four abortifacient agents. In corpora lutea of rats treated with prostaglandin...
Luteal metabolism was investigated in corpora lutea of early pregnant rats treated with four abortifacient agents. In corpora lutea of rats treated with prostaglandin F2alpha or of rats 1 day postpartum, glucose-6-phosphate dehydrogenase (G6PDH) activity increased 140 to 170% and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) was activated to significantly high levels, whereas malic enzyme activity decreased to 29% of control values. In aminoglutethimide-treated rats, the activities of G6PDH and malic enzyme decreased, while 20alpha-HSD activity was maintained at a very low level. With the increased dose, complete abortion was observed. In corpora lutea of these aborted rats, 20alpha-HSD was activated moderately and G6PDH values were slightly higher than control values, whereas malic enzyme activity fell to lower levels. All rats treated with clomiphene citrate aborted within 63 hours after the last injection. The activities of G6PDH, malic enzyme, and ATP citrate lyase in these corpora lutea decreased to 66, 68, and 72% of control levels, respectively; 20alpha-HSD activity was maintained at a very low level, and activities of 3beta-hydroxysteroid dehydrogenase, 6-phosphogluconate dehydrogenase, and pyruvate kinase were not appreciably altered. These findings indicated that, at the beginning of luteolysis and fetal resorption, the activities of steroidogenic enzymes decreased and 20alpha-HSD was not yet activated. Therefore, we could gauge the early changes of luteolysis by measuring the activities of G6PDH, MALIC ENZYME, AND ATP citrate lyase as well as 20alpha-HSD.
Topics: ATP Citrate (pro-S)-Lyase; Abortifacient Agents; Aminoglutethimide; Animals; Clomiphene; Corpus Luteum; Estradiol; Female; Glucosephosphate Dehydrogenase; Hydroxysteroid Dehydrogenases; Malate Dehydrogenase; Oxidoreductases; Phosphogluconate Dehydrogenase; Pregnancy; Prostaglandins F; Rats
PubMed: 955139
DOI: 10.1016/s0015-0282(16)42018-2 -
Molecular Human Reproduction Jan 2018Does 27-hydroxycholesterol (27OH) actively facilitate the progression of luteolysis?
STUDY QUESTION
Does 27-hydroxycholesterol (27OH) actively facilitate the progression of luteolysis?
SUMMARY ANSWER
There is increased mRNA expression of the enzyme that produces 27OH during luteolysis in vivo in rhesus macaques and sheep, and 27OH reduces progesterone secretion from human luteinized granulosa cells.
WHAT IS KNOWN ALREADY
There is an increase in mRNA expression of liver x receptor (LXR) and a decrease in sterol regulatory element binding protein 2 (SREBP2) target genes during spontaneous luteolysis in primates, which could result in reduced cholesterol availability for steroidogenesis. Concentrations of 27OH are also increased in primate corpora lutea (CL) during luteolysis, and 27OH is a dual LXR agonist and SREBP2 inhibitor.
STUDY DESIGN SIZE, DURATION
This was an in vitro study using primary human luteinized granulosa cells in a control versus treatment(s) design. Analyses of CL from sheep undergoing induced or spontaneous luteolysis were also performed, along with database mining of microarray data from rhesus macaque CL.
PARTICIPANTS/MATERIALS, SETTING, METHODS
Primary luteinizing granulosa cells were obtained from 37 women aged 24-44 who were undergoing oocyte donation or IVF for male factor or idiopathic infertility, and cells were further luteinized in vitro using human chorionic gonadotropin. Three approaches to test the effect of 27OH produced via CYP27A1 (cytochrome p450, family 27, subfamily A, polypeptide 1) on luteinized granulosa cells were used: (i) direct 27OH supplementation, (ii) induction of endogenous CYP27A1 activity via pharmacologic inhibition of steroidogenesis, and (iii) siRNA-mediated knockdown to directly inhibit CYP27A1 as well as cholesterol transport into the mitochondria via the steroidogenic acute regulatory protein (STAR). Endpoints included: progesterone (P4) secretion into culture media determined by enzyme immunoassay, cholesterol efflux and uptake assays using fluorescent lipid analogs, and mRNA expression determined via semi-quantitative real-time PCR (QPCR). An additional experiment involved QPCR analysis of 40 CL collected from ewes undergoing induced or spontaneous luteolysis, as well as database mining of microarray data generated from 16 rhesus macaque CL collected during spontaneous luteolysis and 13 macaque CL collected during a luteinizing hormone ablation and replacement protocol.
MAIN RESULTS AND THE ROLE OF CHANCE
The mRNA expression of CYP27A1 was significantly increased during luteolysis in rhesus macaques and sheep in vivo, and CYP27A1 transcription was suppressed by luteinizing hormone and hCG. There was a significant decrease in hCG-stimulated P4 secretion from human luteinized granulosa cells caused by 27OH treatment, and a significant increase in basal and hCG-stimulated P4 synthesis when endogenous 27OH production was inhibited via CYP27A1 knockdown, indicating that 27OH inhibits steroidogenesis. Pharmacologic inhibition of steroidogenesis by aminoglutethimide significantly induced LXR and inhibited SREBP2 target gene mRNA expression, indicating that increased oxysterol production occurs when steroidogenesis is suppressed. Inhibiting cholesterol delivery into the mitochondria via knockdown of STAR resulted in reduced SREBP2 target gene mRNA expression, indicating that STAR function is necessary to maintain SREBP2-mediated transcription. The effects of 27OH treatment on markers of LXR and SREBP2 activity were moderate, and knockdown of CYP27A1 did not prevent aminoglutethimide-induced changes in LXR and SREBP2 target gene mRNA expression. These observations indicate that 27OH inhibits P4 secretion partially via mechanisms separate from its role as an LXR agonist and SREBP2 inhibitor, and also demonstrate that other oxysterols are involved in modulating LXR and SREBP2-mediated transcription when steroidogenesis is suppressed.
LARGE SCALE DATA
None.
LIMITATIONS REASONS FOR CAUTION
Luteinized granulosa cells may differ from luteal cells, and the effect on luteal function in vivo was not directly tested. The mechanisms that cause the initial rise in CYP27A1 mRNA expression during luteolysis are also not clear.
WIDER IMPLICATIONS OF THE FINDINGS
The factors causing luteolysis in primates have not yet been determined. This study provides functional evidence of a novel mechanism via increased 27OH synthesis during luteolysis, which subsequently represses progesterone secretion. Increased 27OH may also facilitate the progression of luteolysis in domestic animal species.
STUDY FUNDING AND COMPETING INTEREST(S)
The authors have nothing to disclose. Support was provided by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD) of the National Institutes of Health (NIH), award number R00HD067678 to R.L.B.
Topics: Adult; Aminoglutethimide; Cells, Cultured; Cholestanetriol 26-Monooxygenase; Cholesterol; Chorionic Gonadotropin; Female; Humans; Hydroxycholesterols; Immunoenzyme Techniques; Luteinizing Hormone; Luteolysis; Progesterone; RNA, Small Interfering; Real-Time Polymerase Chain Reaction; Sterol Regulatory Element Binding Protein 2
PubMed: 29177442
DOI: 10.1093/molehr/gax061 -
British Journal of Cancer May 2004Two-thirds of breast tumours are oestrogen-receptor positive and 60-70% of these tumours respond to interventions that reduce the effects of oestrogen. Until recently,... (Comparative Study)
Comparative Study Review
Two-thirds of breast tumours are oestrogen-receptor positive and 60-70% of these tumours respond to interventions that reduce the effects of oestrogen. Until recently, tamoxifen was the drug of choice for the treatment of hormone-responsive early and advanced breast cancer. However, tamoxifen is associated with increased incidences of endometrial cancer and thromboembolic disease, and many tumours eventually become resistant to treatment with tamoxifen. Thus, there is a need for alternative therapies with different mechanisms of action. In postmenopausal women, aromatase inhibitors (AIs) suppress oestrogen levels by inhibiting oestrogen synthesis via the aromatase enzyme pathway. The third-generation AIs (anastrozole, letrozole and exemestane) are more potent than the earlier AIs (aminoglutethimide, formestane and fadrozole) with respect to both aromatase inhibition and oestrogen suppression. While the earlier AIs were unable to show any benefit over megestrol acetate or tamoxifen as second- and first-line therapy, respectively, in postmenopausal women with advanced breast cancer, third-generation AIs have shown significant benefits in both settings. Comparison of aromatase inhibition and oestrogen suppression between the third-generation AIs anastrozole and letrozole showed a small but significantly greater difference in the degree of suppression of oestrone and oestrone sulphate (but not oestradiol), with letrozole. In an open-label trial, there were no significant differences between letrozole and anastrozole for the clinical end points of time to progression (primary end point), time to treatment failure, overall survival, clinical benefit, duration of clinical benefit, time to response, duration of response or objective response rate in patients with confirmed hormone receptor-positive tumours. Together these data suggest that once a certain threshold of aromatase inhibition is reached, small differences in oestrogen suppression between the third-generation AIs do not lead to clinically significant differences in overall efficacy.
Topics: Anastrozole; Androstadienes; Antineoplastic Agents, Hormonal; Aromatase; Aromatase Inhibitors; Breast Neoplasms; Female; Humans; Letrozole; Middle Aged; Nitriles; Randomized Controlled Trials as Topic; Tamoxifen; Triazoles
PubMed: 15150604
DOI: 10.1038/sj.bjc.6601731 -
Oncology (Williston Park, N.Y.) Mar 1998The new generation of potent steroidal and nonsteroidal inhibitors of the enzyme aromatase act by decreasing estrogen production throughout the body in postmenopausal... (Review)
Review
The new generation of potent steroidal and nonsteroidal inhibitors of the enzyme aromatase act by decreasing estrogen production throughout the body in postmenopausal women. The most potent of these agents may also inhibit estrogen synthesis within metastatic breast cancer tissue. The newly developed, orally administered, nonsteroidal competitive inhibitors, such as anastrozole (Arimidex), letrozole (Femara), and vorozole (Rizivor), are a thousand times more potent inhibitors of aromatase than is aminoglutethimide. Furthermore, these agents are highly selective. In several large randomized trials, the new inhibitors produced similar response rates as megestrol acetate (160 mg/d) in postmenopausal women with hormone-dependent breast cancer, but showed a trend toward improved response duration and survival. They also produced less weight gain and fewer cardiovascular and thromboembolic side effects. In addition, letrozole proved superior to aminoglutethimide in another randomized trial. Both anastrozole (1.0 mg/d) and letrozole (2.5 mg/d) have now been approved as second-line treatment for hormone-dependent breast cancer in postmenopausal women in whom disease has progressed following tamoxifen treatment. Either drug should replace the routine use of megestrol acetate in this setting. Ongoing clinical studies are comparing anastrozole and letrozole to antiestrogens as first-line endocrine therapy for metastatic breast cancer. Other trials will study the possible roles of these compounds as adjuvant therapy and chemoprevention for breast cancer.
Topics: Aged; Aminoglutethimide; Anastrozole; Antineoplastic Agents, Hormonal; Aromatase Inhibitors; Breast Neoplasms; Enzyme Inhibitors; Estrogens; Female; Humans; Letrozole; Megestrol Acetate; Middle Aged; Neoplasms, Hormone-Dependent; Nitriles; Randomized Controlled Trials as Topic; Triazoles
PubMed: 9556789
DOI: No ID Found -
Endocrinologia Japonica Apr 1984Rat adrenocortical cell suspensions (10(6) cells) were incubated with ACTH (40 nM) in 2 ml of Krebs-Ringer bicarbonate buffer for 90 min. About 42 nmol of corticosterone...
Rat adrenocortical cell suspensions (10(6) cells) were incubated with ACTH (40 nM) in 2 ml of Krebs-Ringer bicarbonate buffer for 90 min. About 42 nmol of corticosterone and 14 nmol of 18-hydroxydeoxycorticosterone were generated and released into the medium. Aminoglutethimide at 50 microM inhibited the steroidogenesis to 16%. Mitochondrial pellets were prepared from the cells incubated in the absence, or in the presence, of ACTH and aminoglutethimide, and cholesterol content was determined. The mitochondria of the cells incubated without the drugs contained 25.2 micrograms cholesterol/mg protein. Cholesterol content increased by 10% in the mitochondria of the ACTH-stimulated cells. The mitochondria of the cells incubated in the presence of both ACTH and aminoglutethimide contained 143% of cholesterol compared to those of the nontreated cells. When rats were subjected to ether stress after aminoglutethimide pretreatment, cholesterol content of the mitochondrial fraction increased to about 200% compared to that of the control rats. These results suggest that a cholesterol pool exists in the adrenocortical mitochondria and that the amount increases during the steroidogenic stimulation of the cells. The mitochondria were fixed with filipin-containing fixative and examined by freeze-fracture electron microscopy. Accumulations of filipin-cholesterol complexes were observed in the inner membrane of the mitochondria as protuberances or pits 25 nm in diameter.
Topics: Adrenal Cortex; Adrenocorticotropic Hormone; Aminoglutethimide; Animals; Cholesterol; Female; Freeze Fracturing; Microscopy, Electron; Mitochondria; Rats; Rats, Inbred Strains; Stress, Physiological
PubMed: 6086296
DOI: 10.1507/endocrj1954.31.177 -
The International Journal of... Nov 2012The discovery that 7-dehydrocholesterol (7DHC) is an excellent substrate for cytochrome P450scc (CYP11A1) opens up new possibilities in biochemistry. To elucidate its...
The discovery that 7-dehydrocholesterol (7DHC) is an excellent substrate for cytochrome P450scc (CYP11A1) opens up new possibilities in biochemistry. To elucidate its biological significance we tested ex vivo P450scc-dependent metabolism of 7DHC by tissues expressing high and low levels of P450scc activity, placenta and epidermal keratinocytes, respectively. Incubation of human placenta fragments with 7DHC led to its conversion to 7-dehydropregnenolone (7DHP), which was inhibited by dl-aminoglutethimide, and stimulated by forskolin. Final proof for P450scc involvement was provided in isolated placental mitochondria where production of 7DHP was almost completely inhibited by 22R-hydroxycholesterol. 7DHC was metabolized by placental mitochondria at a faster rate than exogenous cholesterol, under both limiting and saturating conditions of substrate transport, consistent with higher catalytic efficiency (k(cat)/K(m)) with 7DHC as substrate than with cholesterol. Ex vivo experiments showed five 5,7-dienal intermediates with MS spectra of dihydroxy and mono-hydroxy-7DHC and retention time corresponding to 20,22(OH)(2)7DHC and 22(OH)7DHC. The chemical structure of 20,22(OH)(2)7DHC was defined by NMR. 7DHP was further metabolized by either placental fragments or placental microsomes to 7-dehydroprogesterone as defined by UV, MS and NMR, and to an additional product with a 5,7-dienal structure and MS corresponding to hydroxy-7DHP. Furthermore, epidermal keratinocytes transformed either exogenous or endogenous 7DHC to 7DHP. 7DHP inhibited keratinocytes proliferation, while the product of its pholytic transformation, pregcalciferol, lost this capability. In conclusion, tissues expressing P450scc can metabolize 7DHC to biologically active 7DHP with 22(OH)7DHC and 20,22(OH)(2)7DHC serving as intermediates, and with further metabolism to 7-dehydroprogesterone and (OH)7DHP.
Topics: Adolescent; Adult; Animals; Cholesterol Side-Chain Cleavage Enzyme; Chromatography, High Pressure Liquid; Colforsin; Dehydrocholesterols; Epidermal Cells; Female; Humans; Keratinocytes; Magnetic Resonance Spectroscopy; Mass Spectrometry; Metabolic Networks and Pathways; Microsomes; Mitochondria; Placenta; Pregnancy; Pregnenolone; Sus scrofa; Time Factors; Young Adult
PubMed: 22877869
DOI: 10.1016/j.biocel.2012.07.027 -
British Journal of Cancer Apr 2013There exists evidence that body mass index (BMI) impacts on the efficacy of aromatase inhibitors in patients with breast cancer. The relationship between BMI and the... (Randomized Controlled Trial)
Randomized Controlled Trial
Efficacy of tamoxifen ± aminoglutethimide in normal weight and overweight postmenopausal patients with hormone receptor-positive breast cancer: an analysis of 1509 patients of the ABCSG-06 trial.
BACKGROUND
There exists evidence that body mass index (BMI) impacts on the efficacy of aromatase inhibitors in patients with breast cancer. The relationship between BMI and the efficacy of tamoxifen is conflicting. We investigated the impact of BMI on the efficacy of single tamoxifen and tamoxifen plus an aromatase inhibitor in the well-defined prospective study population of the ABCSG-06 trial.
METHODS
ABCSG-06 investigated the efficacy of tamoxifen vs tamoxifen plus aminoglutethimide in postmenopausal women with hormone receptor-positive breast cancer. Taking BMI at baseline, patients were classified as normal weight (BMI=18.5-24.9 kg m(-)(2)), overweight (BMI=25-29.9 kg m(-)(2)), and obese (30 kg m(-)(2)) according to WHO criteria.
RESULTS
Overweight+obese patients had an increased risk for distant recurrences (hazard ratio (HR): 1.51; Cox P=0·018) and a worse overall survival (OS; HR: 1·49; Cox P=0·052) compared with normal weight patients. Analysing patients treated with single tamoxifen only, no difference between overweight+obese patients and normal weight patients regarding distant recurrence-free survival (HR: 1.35; Cox P=0·24) and OS (HR: 0.99; Cox P=0·97) could be observed. In contrast, in the group of patients treated with the combination of tamoxifen plus aminoglutethimide, overweight+obese patients had an increased risk for distant recurrences (1.67; Cox P=0·03) and a worse OS (1.47; Cox P=0·11) compared with normal weight patients.
CONCLUSION
BMI impacts on the efficacy of aromatase inhibitor-based treatment but not single tamoxifen.
Topics: Aged; Aged, 80 and over; Aminoglutethimide; Antineoplastic Agents, Hormonal; Antineoplastic Combined Chemotherapy Protocols; Aromatase Inhibitors; Body Mass Index; Breast Neoplasms; Female; Humans; Middle Aged; Overweight; Postmenopause; Prospective Studies; Receptors, Cell Surface; Tamoxifen; Treatment Outcome
PubMed: 23511562
DOI: 10.1038/bjc.2013.114 -
British Journal of Cancer Dec 1984Forty patients with metastatic adenocarcinoma of the prostate were evaluated for response to treatment with aminoglutethimide plus cortisone acetate. All had relapsed...
Forty patients with metastatic adenocarcinoma of the prostate were evaluated for response to treatment with aminoglutethimide plus cortisone acetate. All had relapsed from or failed to respond to primary endocrine treatment with orchidectomy or stilboestrol. Nineteen patients (48%) showed subjective response, in most cases relief of bone pain. Side effects limited treatment in only 3 patients. We conclude that aminoglutethimide plus cortisone acetate is a useful addition to the treatment available for this difficult group of patients. The mechanism by which this treatment has a beneficial effect remains unclear.
Topics: Adenocarcinoma; Aged; Aminoglutethimide; Androstenedione; Antineoplastic Combined Chemotherapy Protocols; Cortisone; Dehydroepiandrosterone; Dihydrotestosterone; Humans; Male; Middle Aged; Prostatic Neoplasms; Sleep Stages; Testosterone
PubMed: 6238616
DOI: 10.1038/bjc.1984.253 -
British Journal of Cancer Dec 1993Trilostane and Aminoglutethimide, each given with a physiological replacement dose of hydrocortisone, were randomly allocated to 72 eligible postmenopausal advanced... (Clinical Trial)
Clinical Trial Comparative Study Randomized Controlled Trial
Trilostane and Aminoglutethimide, each given with a physiological replacement dose of hydrocortisone, were randomly allocated to 72 eligible postmenopausal advanced breast cancer patients; following treatment failure on either drug the patient continued with the other drug, if in a suitable clinical condition. Thirty-eight patients initially received Trilostane of whom 19 subsequently received Aminoglutethimide; 34 patients initially had Aminoglutethimide and seven of these then received Trilostane. Both groups of patients were comparable in all respects. There was no difference in the objective response rate to either drug, Trilostane 11/38 = 29%, Aminoglutethimide 12/34 = 35%, nor in the average time to disease progression for the two drugs, Trilostane 64 weeks, Aminoglutethimide 68 weeks. Of the 26 patients who received both drugs, four showed a response to both suggesting no cross resistance. Side effects were seen to both drugs in approximately half of the patients, but were mainly gastro-intestinal with Trilostane and rash and drowsiness with Aminoglutethimide. There was no evidence of cross over patient susceptibility to side effects.
Topics: 3-Hydroxysteroid Dehydrogenases; Adrenal Cortex Hormones; Aged; Aminoglutethimide; Antineoplastic Agents; Aromatase Inhibitors; Breast Neoplasms; Dihydrotestosterone; Drug Resistance; Estrogen Antagonists; Female; Humans; Hydrocortisone; Lyases; Menopause; Middle Aged; Treatment Outcome
PubMed: 8260375
DOI: 10.1038/bjc.1993.506 -
The Journal of Pharmacology and... Sep 2003Buprenorphine (BUP) is a partial opiate agonist used for treatment of the adult and the pregnant addicted to this class of narcotics. The kinetic parameters for...
Buprenorphine (BUP) is a partial opiate agonist used for treatment of the adult and the pregnant addicted to this class of narcotics. The kinetic parameters for transplacental transfer and the metabolism of BUP during its perfusion in a placental lobule were the subject of an earlier report from our laboratory. The aim of this investigation is to identify and characterize the enzyme catalyzing the metabolism of BUP in term human placenta. Norbuprenorphine (norBUP) is the only metabolite formed as determined by high performance liquid chromatography and mass spectrometry. The activity of the enzyme responsible for BUP metabolism is highest in the microsomal fraction and lowest in the cytosolic, with the mitochondrial in between. Compounds with selective affinity to the enzyme aromatase (CYP 19), namely 4-hydroxyandrostenedione and aminoglutethimide, caused >70% inhibition of norBUP formation. Monoclonal antibodies raised against CYP 19 were the most potent inhibitors of BUP dealkylation. A comparison between the data obtained from the saturation isotherm for BUP dealkylation by placental microsomes and a commercially available system of cDNA-expressed CYP 19 indicated similar kinetic parameters, with apparent Km values of 12 +/- 4.0 and 14 +/- 8.0 microM, respectively. Therefore, aromatase is the major enzyme catalyzing the biotransformation of BUP to norBUP in term human placentas obtained from healthy pregnancies. The minor involvement of other cytochrome P450 isoforms or enzyme(s) in the metabolism of BUP in placental tissue cannot be ruled out.
Topics: Alkylation; Antibodies; Aromatase; Aromatase Inhibitors; Buprenorphine; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; DNA, Complementary; Enzyme Inhibitors; Female; Humans; Kinetics; Mixed Function Oxygenases; Narcotics; Placenta; Pregnancy; Subcellular Fractions
PubMed: 12808001
DOI: 10.1124/jpet.103.053199