Design and validation of a reporter mouse to study the dynamic regulation of TFEB and TFE3 activity through in vivo imaging techniques

TFEB and TFE3 belong to the MiT/TFE family of transcription factors that bind identical DNA responsive elements in the regulatory regions of target genes. They are involved in regulating lysosomal biogenesis, function, exocytosis, autophagy, and lipid catabolism. Precise control of TFEB and TFE3 activity is crucial for processes such as senescence, stress response, energy metabolism, and cellular catabolism. Dysregulation of these factors is implicated in various diseases, thus researchers have explored pharmacological approaches to modulate MiT/TFE activity, considering these transcription factors as potential therapeutic targets. However, the physiological complexity of their functions and the lack of suitable in vivo tools have limited the development of selective MiT/TFE modulating agents. Here, we have created a reporter-based biosensor, named CLEARoptimized, facilitating the pharmacological profiling of TFEB- and TFE3-mediated transcription. This innovative tool enables the measurement of TFEB and TFE3 activity in living cells and mice through imaging and biochemical techniques. CLEARoptimized consists of a promoter with six coordinated lysosomal expression and regulation motifs identified through an in-depth bioinformatic analysis of the promoters of 128 TFEB-target genes. The biosensor drives the expression of luciferase and tdTomato reporter genes, allowing the quantification of TFEB and TFE3 activity in cells and in animals through optical imaging and biochemical assays. The biosensor's validity was confirmed by modulating MiT/TFE activity in both cell culture and reporter mice using physiological and pharmacological stimuli. Overall, this study introduces an innovative tool for studying autophagy and lysosomal pathway modulation at various biological levels, from individual cells to the entire organism.Abbreviations: CLEAR: coordinated lysosomal expression and regulation; MAR: matrix attachment regions; MiT: microphthalmia-associated transcription factor; ROI: region of interest; TBS: tris-buffered saline; TF: transcription factor; TFE3: transcription factor binding to IGHM enhancer 3; TFEB: transcription factor EB; TH: tyrosine hydroxylase; TK: thymidine kinase; TSS: transcription start site.

Measurement of the Gerasimov-Drell-Hearn Integrand for 2H from 200 to 800 MeV

A measurement of the helicity dependence of the total inclusive photoabsorption cross section on the deuteron was carried out at MAMI (Mainz) in the energy range 200<Egamma<800 MeV. The experiment used a 4pi detection system, a circularly polarized tagged photon beam and a frozen-spin target which provided longitudinally polarized deuterons. The contribution to the Gerasimov-Drell-Hearn sum rule for the deuteron determined from the data is 407+/-20(stat)+/-24(syst) mu b for 200<Egamma<800 MeV.

Measurement of helicity-dependent photoabsorption cross sections on the neutron from 815 to 1825 MeV

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

Experimental check of the Gerasimov-Drell-Hearn sum rule for 1H

For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.

First Measurement of the Gerasimov-Drell-Hearn Sum Rule for 1H from 0.7 to 1.8 GeV at ELSA

To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.

Helicity amplitudes A1/2 and A3/2 for the D13(1520) resonance obtained from the gamma-->p-->-->ppi(0) Reaction

The helicity dependence of the gamma-->p-->-->ppi(0) reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.

Helicity dependence of gammap --> Npi below 450 MeV and contribution to the Gerasimov-Drell-Hearn sum rule

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

Combined treatment of Dunning R3327 rat prostatic tumor with the 5alpha-reductase inhibitor PNU 157706 and the antiandrogen bicalutamide

PNU 157706 [N-(1,1,1,3,3,3-hexafluorophenyl-propyl)-3-oxo-4-aza- 5alpha-androst-1-ene-17beta-carboxamide], a novel, potent and selective dual 5alpha-reductase inhibitor, was reported to be effective in inhibiting the growth of established tumors in the Dunning R3327 rat prostatic carcinoma model.

PURPOSE

We investigated the efficacy of treatment with PNU 157706 in combination with the antiandrogen bicalutamide in this prostatic tumor model.

METHODS

Rats with tumor diameters of about 1 cm were treated orally 6 days a week for 9 weeks with PNU 157706 (10 mg/kg per day) alone or in combination with bicalutamide (0.2 and 1 mg kg per day). Animals were killed 24 h after the last treatment, and ventral prostates were removed for testosterone (T) and dihydrotestosterone (DHT) determination.

RESULTS

PNU 157706 reduced the growth of established tumors by 39%; bicalutamide proved ineffective at 0.2 mg/kg per day, but reduced tumor growth by 45% at a dose of 1 mg/kg per day. The combination of PNU 157706 with both doses of bicalutamide caused an additive tumor growth inhibition (50% and 64%). Castration resulted in marked tumor growth inhibition (72%). Ventral prostate weight was markedly reduced by PNU 157706 (78%) treatment and by bicalutamide (59% and 77%); combined treatment was as effective as castration. Prostatic DHT content was markedly reduced by PNU 157706 (88%), whereas prostatic T increased slightly (60%). Concomitant treatment with bicalutamide antagonized the T increase induced by PNU 157706 and did not modify the already remarkable suppression of DHT.

CONCLUSIONS

These data show that the inhibitory effect of PNU 157706 and bicalutamide on Dunning prostatic tumor growth is additive, thus suggesting a possible role of PNU 157706 in the therapy of advanced prostate cancer, in combination with antiandrogens, to provide an effective peripheral androgen ablation therapy with minimal side effects.

Reduction of renal cortical blood flow assessed by Doppler in cirrhotic patients with refractory ascites

The usefulness in cirrhotic patients of hemodynamic measurements by Doppler ultrasonography (US) is still not defined. We investigated the relationships between Doppler measurements and the severity of ascites. Portal blood flow velocity and volume, and hepatic and renal arterial resistance indexes (RI) were measured in 57 cirrhotic patients (19 without ascites, 28 with responsive ascites, and 10 with refractory ascites) and 15 healthy controls. The renal arterial RI were obtained for the main renal artery, interlobar vessels, and cortical vessels. Cirrhotic patients had decreased portal blood flow and an increased congestion index (CI). Only the CI was correlated to the severity of ascites, showing that it is also a reliable measure of the severity of portal hypertension in patients with ascites. The hepatic and renal artery RI were increased in cirrhotic patients, and the two values were correlated (r = .68; P = .00001). The RI of renal interlobar and cortical vessels were higher in patients with refractory ascites than in patients without ascites (P < .02 and P < .009), and correlated with sodium excretion rate (r = -.45; P < .003), the renin-aldosterone system, and creatinine clearance (r = -.62; P < .0002). The RI decreased from the hilum of the kidney to the outer parenchyma in healthy subjects and patients with responsive ascites, but this difference disappeared in patients with refractory ascites. This indicates that the degree of renal vasoconstriction varies in different areas according to the severity of the ascites. Cortical vessels are involved mainly in patients with refractory ascites, suggesting that the intrarenal blood flow distribution in cirrhosis tends to preserve the cortical area and that severe cortical ischemia is a feature of refractory ascites.

Effect of the 5 alpha-reductase inhibitor PNU 156765, alone or in combination with flutamide, in the Dunning R3327 prostatic carcinoma model in rats

The efficacy of treatment with the 5 alpha-reductase inhibitor PNU 156765 (FCE 28260) was investigated in the Dunning R3327 prostatic tumor in rats. The compound, given orally at the doses of 10 and 50 mg/kg/day, for 8 weeks, reduced the growth of established tumors by 49-50%, an effect similar to that of flutamide at 5 mg/kg/day (46% inhibition). In a further experiment, the combination of PNU 156765 10 mg/kg/day and flutamide 5 mg/kg/day resulted in greater inhibition than either treatment alone (70 vs. 20% in PNU-156765-treated and 51% in flutamide-treated groups). The effect of the combination was similar to that of castration (75% inhibition). Ventral prostate weight was more markedly reduced by PNU 156765 than by flutamide, and combined treatment was as effective as castration. Prostatic dihydrotestosterone content was markedly reduced by PNU 156765 while prostatic testosterone increased. Concomitant treatment with flutamide antagonized the testosterone increase induced by PNU 156765. These data indicate a role for 5 alpha-reductase inhibitors in the therapy of prostate cancer, in combination with antiandrogens, in order to achieve adequate androgen blockade with minimal side effects.

PNU 157706, a novel dual type I and II 5alpha-reductase inhibitor

PNU 157706 is a novel dual inhibitor of 5alpha-reductase (5alpha-R), the enzyme responsible for the conversion of testosterone (T) to 5alpha-dihydrotestosterone (DHT). Tested on a crude preparation of human or rat prostatic 5alpha-R, PNU 157706 caused enzyme inhibition with IC50 values of 20 and 34 nM, respectively, compared to the values of 32 and 58 nM shown by finasteride. Furthermore, PNU 157706 was highly potent in inhibiting human recombinant 5alpha-R type I and II isozymes, showing IC50 values of 3.9 and 1.8 nM and, therefore, it was several folds more potent than finasteride (IC50 values of 313 and 11.3 nM), particularly on the type I isozyme. PNU 157706 was shown to have no binding affinity for the rat prostate androgen receptor (RBA 0.009% that of DHT). In adult male rats, a single oral dose of 10 mg/kg of PNU 157706 caused a marked and longer lasting reduction of prostatic DHT than did finasteride (at 24 h inhibition by 89 and 47%, respectively). In prepubertal, T- or DHT-implanted castrated rats, PNU 157706, given orally for 7 days at the dose of 10 mg/kg/day, markedly reduced ventral prostate weight in T- but not in DHT-implanted animals, thus showing to be devoid of any anti-androgen activity. In adult rats treated orally for 28 days, PNU 157706 resulted markedly more potent (16-fold) than finasteride in reducing prostate weight, the ED50 values being 0.12 and 1.9 mg/kg/day, respectively. These results indicate that PNU 157706 is a promising, potent inhibitor of both type II and I human 5alpha-R with a very marked antiprostatic effect in the rat.

Prevalence and incidence of cholelithiasis in patients with liver cirrhosis

AIMS

To evaluate the prevalence, the incidence and the history of cholelithiasis in liver cirrhosis.

PATIENTS AND METHODS

A series of 233 consecutive cirrhotic patients (193 Child A, 35 Child B and 5 Child C) were assessed for cholelithiasis by ultrasonography. Of these, 201 (those who had never had cholecystectomy) were followed-up with repeated ultrasonographies.

RESULTS

The prevalence of cholelithiasis was 38% (22% gallstones and 16% previous cholecystectomies). No relationships with the usual risk factors for cholesterol gallstones, such as age, sex, body mass index, serum glucose or triglycerides, were found. On the contrary, close correlations were observed with serum albumin, bilirubin, prothrombin time and Pugh score. By multivariate analysis, only serum bilirubin was independently correlated with cholelithiasis. Histories of biliary pain were more frequent in patients with previous cholecystectomy (62% cases) than in those with gallstones (21%) and those without cholelithiasis (7%). On the contrary, complaints of dyspepsia were similar in the three groups of patients. During a mean follow-up of 34.4 +/- 0.9 months, there was a 4.9% annual rate of development of new stones in 127 patients without cholelithiasis at the first investigation. This rate is markedly higher than that reported for normal subjects in a previous survey carried out in a similar geographic area. During a mean follow-up of 31.8 +/- 1.2 months, symptoms or complications were seen in 2 out of 45 patients with initial gallstones (4.4%). The annual rate of complications was estimated to be less than 2%.

CONCLUSIONS

Cholelithiasis is frequently associated with cirrhosis and the risk of developing new stones remains high during the natural history of the disease.

Prevention of variceal rebleeding and treatment of liver carcinoma by consecutive transjugular intrahepatic portosystemic shunt and hepatic artery chemoembolization

Variceal bleeding and hepatocellular carcinoma are two severe complications of cirrhosis. One of our patients who bled from oesophageal varices was found to have a malignant hepatic nodule. As the patient refused liver transplantation, a transjugular intrahepatic portosystemic stent was carried out for portal hypertension, and transcatheter arterial chemoembolization for cancer. Both procedures were successful and one year later liver function has not deteriorated. This case shows that intrahepatic stent placement and selective arterial chemoembolization can be safely performed in cirrhotic patients with a solitary hepatocarcinoma nodule and a good liver function reserve.

FCE 28260, a new 5 alpha-reductase inhibitor: in vitro and in vivo effects

FCE 28260 is a novel inhibitor of 5 alpha-reductase (5 alpha R), the enzyme responsible for the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The compound caused inhibition of rat and human prostatic enzymes, with IC50 values of 15 and 16 nM, respectively, compared to the values of 30 and 52 nM shown by finasteride. Furthermore, FCE 28260 was highly potent in inhibiting human recombinant 5 alpha R type 2 and 1 isozymes, showing IC50 values of 3.3 and 36 nM, and therefore it was more potent than finasteride (IC50 values of 8.5 and 470 nM) on both isozymes. In prepubertal, T-implanted castrated rats, FCE 28260, given orally for 7 days, reduced ventral prostate growth with an ED50 of 0.8 mg/kg, i.e. five times lower than that shown by finasteride. No anti-androgenic activity in DHT-implanted castrated rats was found up to 10 mg/kg/day. In adult male rats, FCE 28260 reduced prostatic DHT concentrations 6 h after oral dosing with a potency similar to that of finasteride (65% reduction at 1 mg/kg) but was found to be markedly more potent than the reference compound at 24 h (74% reduction in prostate DHT at 10 mg/kg, compared to 26% reduction induced by finasteride). These results indicate that FCE 28260 represents a marked improvement over finasteride.

Effects of 5 alpha-reductase inhibitors on intraprostatic androgens in the rat

FCE 27837 is a novel inhibitor of 5 alpha-reductase, the enzyme responsible for the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The compound caused inhibition of human and rat prostatic enzymes, with IC50 values of 51 and 60 nM, respectively. The in vivo effect of FCE 27837 on 5 alpha-reductase was evaluated in adult male rats, treated orally at 10 mg/kg/day for 10 days. The compound caused 33 and 42% reductions in ventral prostate and seminal vesicle weights, respectively. The prostatic content of DHT, measured 6 h after the 10th dose of FCE 27837, was reduced by 75%, whereas T content increased by 442%. Similar effects were observed with 10 mg/kg/day of finasteride, whereas epristeride, tested at the same oral dose, was found to be the least effective compound, decreasing prostate weight by 22% and DHT content by 46%. Castration caused > 90% reductions in prostatic weight and prostatic DHT.

Novel aromatase and 5 alpha-reductase inhibitors

Inhibitors of aromatase and 5 alpha-reductase may be of use for the therapy of postmenopausal breast cancer and benign prostatic hyperplasia, respectively. FCE 27993 is a novel steroidal irreversible aromatase inhibitor structurally related to exemestane (FCE 24304). The compound was found to be a very potent competitive inhibitor of human placental aromatase, with a Ki of 7.2 nM (4.3 nM for exemestane). In preincubation studies with placental aromatase FCE 27993, like exemestane, was found to cause time-dependent inhibition with a higher rate of inactivation (t1/2 4.5 vs 15.1 min) and a similar Ki(inact) (56 vs 66 nM). The compound was found to have a very low binding affinity to the androgen receptor (RBA 0.09% of dihydrotestosterone) and, in contrast to exemestane, no androgenic activity up to 100 mg/kg/day s.c. in immature castrated rats. Among a series of novel 4-azasteroids with fluoro-substituted-17 beta-amidic side chains, three compounds, namely FCE 28260, FCE 28175 and FCE 27837, were identified as potent in vitro and in vivo inhibitors of prostatic 5 alpha-reductase. Their IC50 values were found to be 16, 38 and 51 nM for the inhibition of the human enzyme, and 15, 20 and 60 nM for the inhibition of the rat enzyme, respectively. When given orally for 7 days in castrated and testosterone (Silastic implants) supplemented rats, the new compounds were very effective in reducing prostate growth. At a dose of 0.3 mg/kg/day inhibitions of 42, 36 and 41% were caused by FCE 28260, FCE 28175 and FCE 27837, respectively.

Radioimmunoassay for the testosterone 5 alpha-reductase inhibitor turosteride in biological fluids

An antiserum against turosteride (code name FCE 26073), a potent testosterone 5 alpha-reductase inhibitor, has been raised in rabbits by immunization with an immunogen produced by conjugation of a derivative of FCE 26073 (FCE 27424) to bovine serum albumin. The antiserum was able to distinguish FCE 26073 from its derivatives modified at the 17 beta position and from all the endogenous steroids tested. A radioimmunoassay for the determination of FCE 26073 in human plasma and urine was developed using this antiserum and tritium labeled turosteride. FCE 26073 was extracted from 50 microliters of plasma or 25 microliters of urine using ethyl-ether with a recovery greater than 90%. Using this procedure it was possible to achieve a final limit of quantitation of 142 pg/ml in plasma and 284 pg/ml in urine. The assay was validated in terms of reproducibility, accuracy and precision in the range 3.9-250 pg/50 microliters of plasma and 25 microliters of urine. The plasma concentration of FCE 26073 in a healthy male volunteer who received 0.2 mg of the drug was measured using the radioimmunoassay.

Endocrine properties of the testosterone 5 alpha-reductase inhibitor turosteride (FCE 26073)

Turosteride was tested in a series of studies for its effect on 5 alpha-reductase and for its possible influence on other steroidogenic enzymes and on steroid receptors. The compound was found to inhibit human and rat prostatic 5 alpha-reductases with IC50 values of 55 and 53 nM, respectively, whereas it caused a less marked inhibition of the dog enzyme (IC50 2.2 microM). Turosteride showed no relevant effect on rat adrenal C20,22-desmolase (IC50 254 microM) and human placental aromatase (IC50 > 100 microM), and only at relatively high concentrations it caused inhibition of human placental 5-ene-3 beta-hydroxysteroid dehydrogenase-isomerase (3 beta-HSD-I) (IC50 2.5 microM). Turosteride was found to be a selective 5 alpha-reductase inhibitor showing no noteworthy binding to receptors for androgens (relative binding affinity, RBA, 0.004%), estrogens (< or = 0.005%), progesterone (< 0.005%), glucocorticoids (< 0.01%) and mineralocorticoids (< 0.03%). Its biochemical profile was similar to that of finasteride, whereas 4-MA (17 beta-N,N-diethyl-carbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one) was confirmed to be a non-selective 5 alpha-reductase inhibitor, showing a degree of binding affinity to the androgen receptor (RBA 0.1%) and a marked inhibition of 3 beta-HSD-I (IC50 32 nM). When given orally in immature castrated rats together with subcutaneous testosterone propionate (TP) for 7 consecutive days, turosteride reduced the ventral prostate and seminal vesicle growth promoting effect of TP, with IC50 values of approximately 5 and 6.7 mg/kg/day, whereas levator ani weight was unchanged. In comparison, 4-MA was approx. 3-fold less potent than turosteride in reducing the prostate and seminal vesicle weights and caused a marked reduction of levator ani weight, thus showing its unselectivity.

Hormonal effects of turosteride, a 5 alpha-reductase inhibitor, in the rat

Turosteride [FCE 26073; 1-(4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carbonyl)-1,3- diisopropylurea] is a novel inhibitor of 5 alpha-reductase, the enzyme responsible for the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The compound caused inhibition of rat and human prostatic enzymes, with IC50 values of 55 and 53 nM, respectively. In addition, turosteride did not show any relevant binding affinity to the rat prostate androgen receptor (IC50 84 microM; relative binding affinity 0.004% of DHT). The endocrine effects of turosteride were evaluated in adult male rats, treated orally at daily doses of 3, 10 and 30 mg/kg for 20 days. At these doses, the compound reduced the ventral prostate weight by 10, 33 and 42% and the intraprostatic total DHT content by 61, 74 and 78%, respectively, whereas no change in the intraprostatic content of T was observed. Turosteride caused a 40% reduction of serum DHT levels which, however, did not reach statistical significance, whereas serum T levels were similar to control animals. No effect on serum luteinizing hormone or prolactin was observed. These results indicate that the antiprostatic effect of turosteride in the adult rat is related to inhibition of the conversion of T to DHT. However, at variance with other 5 alpha-reductase inhibitors (e.g. finasteride), turosteride caused a decrease in prostatic DHT not associated with a secondary increase in T content. This peculiarity of turosteride may represent an improvement of the compound over other inhibitors.

17 beta-acylurea derivatives of 4-azasteroids as inhibitors of testosterone 5 alpha-reductase

A series of 17 beta-acylurea-4-aza-5 alpha-androstan-3-one derivatives has been assayed in vitro as inhibitors of testosterone 5 alpha-reductase, using the particulate fraction of human hyperplastic prostate and rat prostate as enzyme sources. The most active derivatives were 1-[4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carbonyl]- 1,3-dicyclohexylurea (compound 1) and 1-[4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carbonyl]- 1,3-diisopropylurea (compound 3) which demonstrated IC50 values of 41 and 55 nM for the human enzyme and of 83 and 53 nM for the rat enzyme, respectively. Neither compound showed any relevant binding affinity to the rat prostate androgen receptor (IC50 of approximately 100 and 84 microM). When given orally in immature castrated rats together with subcutaneous testosterone propionate (TP) for 7 consecutive days, compound 3 (laboratory code FCE 26073), at 3 mg/kg/day, significantly decreased the ventral prostate growth promoting effect of TP by 40-50%, whereas compound 1 was ineffective up to the dose of 10 mg/kg/day.

Comparison of the effects of the irreversible aromatase inhibitor exemestane with atamestane and MDL 18962 in rats with DMBA-induced mammary tumours

The antitumour activity of the steroidal aromatase inhibitors exemestane (FCE 24304), MDL 18962 and atamestane (SH 489) was evaluated on 7,12-dimethylbenzanthracene (DMBA)-induced mammary tumours in rats. The compounds were given subcutaneously at daily doses of 10 and 50 mg/kg for 4 weeks. Exemestane was also given orally, at daily doses of 100 and 200 mg/kg. Subcutaneous exemestane induced 30% (10 mg/kg) and 73% (50 mg/kg) regressions of established tumours and strongly reduced the appearance of new tumours. Conversely, atamestane, MDL 18962 and oral exemestane did not affect growth of established tumours nor influenced the appearance of new neoplasms. Aromatase activity of ovarian microsomes (OAA) was reduced by 85%-93% after subcutaneous exemestane and by 25%-59% after MDL 18962, and was unaffected after atamestane. Oral exemestane caused a reduction in OAA of 72%-74%. Serum luteinising hormone (LH) levels were reduced at both the subcutaneous doses of exemestane and at the higher dose of MDL 18962. Atamestane caused an increase in LH levels, while no effect was observed with oral exemestane. The LH-lowering effect of subcutaneous exemestane, the less marked effect of MDL 18962, and the ineffectiveness of oral exemestane were also observed after 10 days of treatment in ovariectomised rats. The antigonadotrophic effect of subcutaneous exemestane, which is probably due to its slight androgenic effect, could contribute to its antitumour activity in the DMBA tumour model in intact rats, through a counteraction of the negative feedback of oestrogens on gonadotropin secretion.

Synthesis and biochemical evaluation of the novel steroid androsta-4,6,8(9)-triene-3,17-dione

According to a proposed aromatisation mechanism by which estrogens are biosynthesized from androgens, the novel steroid androsta-4,6,8(9)-triene-3,17-dione (FCE 24918) should behave as a suicide substrate for aromatase. The synthesis of this triene steroid has been accomplished starting from androsta-4,7-diene-3,17-dione (4) by the acid-catalysed cleavage of the corresponding 7,8 alpha-epoxide, 5, and it was obtained together with androsta-4,6,8(14)-triene-3,17-dione (FCE 24917) as a side product. The time-dependent inactivation of placental aromatase by the two isomers was studied comparatively and showed that the 4,6,8(9)-triene moiety acts as a latent alkylating group.