New progesterone derivatives as inhibitors of 5α-reductase enzyme and prostate cancer cell growth

Novel pentacyclic derivatives and benzylidenes of the progesterone series cause anti-estrogenic and antiproliferative effects and induce apoptosis in breast cancer cells

The promising antitumor effects of progesterone derivatives have been identified in many studies. However, the specific mechanism of action of this class of compounds has not been fully described. Therefore, in this study, we investigated the antiproliferative and (anti)estrogenic activities of novel pentacyclic derivatives and benzylidenes of the progesterone series. The antiproliferative effects of the compounds were evaluated on hormone-dependent MCF7 breast cancer cells using the MTT test. Estrogen receptor α (ERα) activity was assessed by a luciferase-based reporter assay. Immunoblotting was used to evaluate the expression of signaling proteins. All benzylidenes demonstrated inhibitory effects with IC₅₀ values below 10 µM, whereas pentacyclic derivatives were less active. These patterns may be associated with the lability of the geometry of benzylidene molecules, which contributes to an increase in the affinity of interaction with the receptor. The selected compounds showed significant anti-estrogenic potency. Benzylidene 1d ((8 S,9 S,10R,13 S,14 S,17 S)-17-[(2E)-3-(4-fluorophenyl)prop-2-enoyl]-10,13-dimethyl-1,2,6,7,8,9,11,12,14,15-decahydrocyclopenta[a]phenanthren-3-one) was the most active in antiproliferative and anti-estrogenic assays. Apoptosis induced by compound 1d was accompanied by decreases in CDK4, ERα, and Cyclin D1 expression. Compounds 1d and 3d were characterized by high inhibitory potency against resistant breast cancer cells. Apoptosis induced by the leader compounds was confirmed by PARP cleavage and flow cytometry analysis. Compound 3d caused cell arrest in the G2/M phase. Further analysis of novel derivatives of the progesterone series is of great importance for medicinal chemistry, drug design, and oncology.

Recent Advances in Drug Design and Drug Discovery for Androgen- Dependent Diseases

This article summarizes the importance of different targets such as 5α-reductase, 17β-HSD, CYP17A, androgen receptor and protein kinase A for the treatment of prostate cancer and benign prostatic hyperplasia. It is a well known fact that dihydrotestosterone (DHT) is associated with the development of androgen-dependent afflictions. At the present time, several research groups are attempting to develop new steroidal and non-steroidal molecules with the purpose of inhibiting the synthesis and biological response of DHT. This review also discusses the most recent studies reported in the literature that describe the therapeutic potential of novel compounds, as well as the new drugs, principally inhibitors of 5α-reductase.

Steroidal 5α-reductase and 17α-hydroxylase/17,20-lyase (CYP17) inhibitors useful in the treatment of prostatic diseases

The role of steroidal inhibitors of androgen biosynthesis as potential weapons in the treatment of prostatic diseases, such as benign prostatic hyperplasia and prostatic cancer will be reviewed. Two enzymes have been targeted in the development of inhibitors that potentially could be useful in the management of such conditions. 5α-Reductase is primarily of interest in benign prostatic disease, though some role in the chemoprevention of prostatic carcinoma have been considered, whereas the 17α-hydroxylase/17,20-lyase (CYP17) enzyme is of interest in the treatment of malignant disease. An overview of the main achievements obtained during the past years will be presented, however special focus will be made on steroidal molecules that reached clinical trials or have been commercially launched. Relevant examples of such drugs are finasteride, dutasteride, abiraterone acetate and galeterone (TOK-001, formerly known as VN/124-1). This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Novel actions of progesterone: what we know today and what will be the scenario in the future?

Objectives

This article is aimed to review the novel actions of progesterone, which otherwise is considered as a female reproductive hormone. The article focuses on its important physiological actions in males too and gives an overview of its novel perspectives in disorders of central and peripheral nervous system.

Key findings

Progesterone may have a potential benefit in treatment of traumatic brain injury, various neurological disorders and male related diseases like benign prostatic hypertrophy (BPH), prostate cancer and osteoporosis. Norethisterone (NETA), a progesterone derivative, decreases bone mineral loss in male castrated mice suggesting its role in osteoporosis. In the future, progesterone may find use as a male contraceptive too, but still needs confirmatory trials for safety, tolerability and acceptability. Megestrol acetate, a progesterone derivative is preferred in prostatic cancer. Further, it may find utility in nicotine addiction, traumatic brain injury (recently entered Phase III trial) and Alzheimer's disease, diabetic neuropathy and crush injuries. Studies also suggest role of progesterone in stroke, for which further clinical trials are needed. The non genomic actions of progesterone may be in part responsible for these novel actions.

Summary

Although progesterone has shown promising role in various non-hormonal benefits, further clinical studies are needed to prove its usefulness in conditions like stroke, traumatic brain injury, neuropathy and crush injury. In male related illnesses like BPH and prostatic Ca, it may prove a boon in near future. New era of hormonal male contraception may be initiated by use of progesterone along with testosterone.

Self-organizing molecular field analysis on pregnane derivatives as human steroidal 5alpha-reductase inhibitors

Normal growth and development of human prostate is regulated by the androgens which balances cell proliferation and apoptosis. Testosterone (T) and dihydrotestosterone (DHT) are the two key androgens that stimulate most of the androgen action in prostate. Testosterone is converted to DHT by the membrane bound NADPH-dependent 5alpha-reductase enzyme. As a consequence of the important observation that progesterone and deoxycortisone inhibits the synthesis of DHT by competing with 4-en-3-one function of the testosterone for the 5alpha-reductase enzyme a number of pregnane derivatives were synthesized and have been reported as inhibitors of human 5alpha-reductase enzyme. Due to lack of information on the crystal structure of human 5alpha-reductase, ligand-based 3D-QSAR study has been performed on pregnane derivatives using self-organizing molecular field analysis (SOMFA) for rationalizing the molecular properties and human 5alpha-reductase inhibitory activities. The statistical results having good cross-validated r(cv)(2) (0.881), non-cross-validated r(2) (0.893) and F-test value (175.527), showed satisfied predictive ability r(pred)(2) (0.777). Analysis of SOMFA models through electrostatic and shape grids provide useful information for the design and optimization of steroidal structure as novel human 5alpha-reductase inhibitors.

Synthesis and biological effect of halogen substituted phenyl acetic acid derivatives of progesterone as potent progesterone receptor antagonists

In this paper, we report the relative binding affinities to the progesterone receptor (PR) of several progesterone derivatives containing an acetoxyphenyl substituent at C-17 and their structure-bioactivity relationship. The inhibitory effect to ovulation as well as their function as interrupters of endometrial maturation is also described. The biological activity of the novel steroids was determined in vivo and in vitro experiments using female cycling mice, which were synchronized for estrus with luteinizing hormone-releasing hormone (LHRH) and injected with the steroidal compounds. The cytosol used for the determination of the PR, was obtained from the uteri of adult estrogen-primed rabbits and the androgen (AR), mineralocorticoid (MR) and glucocorticoid (GR) receptors were determined in the cytosolic fractions from the prostate of castrated rats and from the kidneys and livers of adenalectomized male rats. We evaluated six related steroidal compounds 8a-8f differing in the nature of the 17alpha ester side chain for the inhibition of [3H] R5020 binding to the PR. The IC50 values for the displacement of [3H] R5020 binding to the PR and its relative binding affinities (RBAs) were determined. Progesterone and R5020 had similar IC(50) values; steroids 8a, 8f and 8c bind to the progesterone receptor with RBAs of 100%, whereas 8e, 8b and 8d have RBA values <100%. These data indicate that there is a relationship between the structure of these steroids and their binding activity to the progesterone receptors. Having demonstrated in this study that steroids 8a-8f bind to the PR, we also evaluated the receptor's selectivity, since some progesterone derivatives bind to AR, MR, GR receptors. We demonstrated that the tested steroids did not bind to the AR, MR, GR, since none of the steroids inhibited the labeled mibolerone, aldosterone or dexamethasone binding to the AR, MR or GR, respectively. These results show that the novel compounds have certain selectivity for the PR. After LHRH treatment, the mice of the control group showed the presence of ova in the oviduct, whereas the animals treated with steroids 8a, 8f, 8e and 8c with RBAs of 92-100%, did not exhibit any ovum in the oviducts. As a result of this study, it is evident that the novel steroids 8a, 8f, 8e and 8c inhibited the ovulation in these animals at dose of 0.22 mg/kg. After the treatment with LHRH, the uterus of the control group showed the typical progestational activity with an enlarged endometrial thickness with secretory activity. However, the endometrium of the mice treated with steroids 8a, 8f, 8e and 8c (with RBAs of 92-100%) neither did show any enlargement of the endometrium, nor a secretory activity could be detected. The diameter of the uterus was also significantly reduced compared to those of the control group, thus indicating that compounds 8a, 8f, 8e and 8c had antagonistic activity in this tissue. The overall data showed that steroids 8a, 8f, 8e and 8c have a high and selective binding activity to the PR. Furthermore there is a relationship between the structure of these steroids and their binding activity, since the presence of fluorine atom in meta position in the acetoxyphenyl substituent at C-17, improved the binding activity as compared to that for the ortho and para positions. These data also demonstrated that 8a-8f have an anti-progestational activity in vivo, and therefore they have better characteristics than the compounds previously reported.

Steroids with a carbamate function at C-17, a novel class of inhibitors for human and hamster steroid 5alpha-reductase

In order to study the biological activity of the two novel steroidal carbamates derivatives: 8a and 8b, we determined the concentration of both compounds that inhibit the 50% of the activity of human prostate 5alpha-reductase enzyme, as well as the in vivo effect of these compounds in the weight of hamster prostate and flank organs diameter size. We determined also, the capacity of these steroids to bind to the androgen receptors present in the rat prostate cytosol. Furthermore the activity of these compounds on the mRNA expression of glycerol 3-phosphate acyl transferase (GPAT) in flank organs was analyzed by RT-PCR. This enzyme induces the triglycerides synthesis, which is increased by T in flank organs. The results from this study indicated that steroids 8a and 8b inhibited the human 5alpha-reductase activity. Compound 8b, which contains a bromine atom in the molecule, decreased the inhibitory effect of the human 5alpha-reductase activity, whereas steroid 8a, which lacks a halogen atom did not show any decrease in the activity of this enzyme. The competition studies demonstrated that 8a and 8b did not inhibit mibolerone binding to the androgen receptor present in the rat prostate cytosol. However, the in vivo activity of both steroids was similar; steroids 8a and 8b had a tendency to decrease the weight of the hamster prostate although this parameter was not statistically significant. These compounds also significantly reduced the diameter of the pigmented spot of hamster flank organs, which are androgen dependent skin's pilosebaceous structures. Steroids 8a and 8b, decreased the transcription of mRNA encoding for GPAT in intact hamster's flank organs topically treated in a similar way as in gonadectomized non-treated animals. These results suggest that mRNA encoding for GPAT is induced by DHT in this tissue.