A Multivalent Peptoid Conjugate Modulates Androgen Receptor Transcriptional Activity to Inhibit Therapy-resistant Prostate Cancer.

Prostate cancers adapt to androgen receptor (AR) pathway inhibitors and progress to castration resistance due to ongoing AR expression and function. To counter this, we developed a new approach to modulate the AR and inhibit castration-resistant prostate cancer (CRPC) using multivalent peptoid conjugates (MPC) that contain multiple copies of the AR-targeting ligand ethisterone attached to a peptidomimetic scaffold. Here, we investigated the antitumor effects of compound MPC309, a trivalent display of ethisterone conjugated to a peptoid oligomer backbone that binds to the AR with nanomolar affinity. MPC309 exhibited potent antiproliferative effects on various enzalutamide-resistant prostate cancer models, including those with AR splice variants, ligand-binding mutations, and noncanonical AR gene expression programs, as well as mouse prostate organoids harboring defined genetic alterations that mimic lethal human prostate cancer subtypes. MPC309 is taken up by cells through macropinocytosis, an endocytic process more prevalent in cancer cells than in normal ones, thus providing an opportunity to target tumors selectively. MPC309 triggers a distinct AR transcriptome compared with DHT and enzalutamide, a clinically used antiandrogen. Specifically, MPC309 enhances the expression of differentiation genes while reducing the expression of genes needed for cell division and metabolism. Mechanistically, MPC309 increases AR chromatin occupancy and alters AR interactions with coregulatory proteins in a pattern distinct from DHT. In xenograft studies, MPC309 produced significantly greater tumor suppression than enzalutamide. Altogether, MPC309 represents a promising new AR modulator that can combat resistant disease by promoting an AR antiproliferative gene expression program.

Facile, Single-Step Synthesis of a Series of D-Ring Ethisterones Substituted with 1,4-1,2,3-Triazoles: Preliminary Evaluation of Cytotoxic Activities.

A series of new D-ring ethisterones substituted with 1,4-1,2,3-triazoles were obtained in a facile manner via click chemistry reactions. The new compounds were characterized by multinuclear NMR spectroscopy, mass spectrometry, IR and unequivocally by single crystal X-ray diffraction studies for compound 1. The cytotoxic activity of these derivatives was tested against a series of human cancer cell lines including human glioblastoma (U-251), human prostatic adenocarcinoma (PC-3), human colorectal adenocarcinoma (HCT-15), human mammary adenocarcinoma (MCF-7), human chronic myelogenous leukemia (K562), and human lung adenocarcinoma (SKLU-1). Derivatives (3, X=Cl) and (5, X=I) showed promising cytotoxicity activities for leukemia adenocarcinoma (K562) and lung adenocarcinoma (SKLU). CI50% of K562: 11.72±0.9 µM (3) and 24.50±1.0 µM (5). CI50% of SKLU: 14.9±0.8 µM (3) and 46.0±2.8 µM (5). In addition, DNA docking simulations showed that all compounds interact with DNA through crosslink instrastrand p-alkyl-like interactions.

Synthesis and preliminary evaluation of a 18 F-labeled ethisterone derivative [18 F]EAEF for progesterone receptor targeting.

To develop a novel progesterone receptor-targeting probe for positron emission tomography imaging, an ethisterone derivative [18 F]EAEF was designed and prepared in high decay-corrected radiochemical yield (30-35%) with good radiochemical purity (>98%). [18 F]EAEF is a lipophilic tracer (logP = 0.53 ± 0.06) with very good stability in saline and serum. In the biodistribution study, high radioactivity accumulation of [18 F]EAEF were found in uterus (5.73 ± 1.83% ID/g) and ovary (4.05 ± 0.73% ID/g) at 2 hr postinjection (p.i.), which have high progesterone receptor expression after treated with estradiol, while the muscle background has very low uptake (0.50 ± 0.17% ID/g). For positron emission tomography imaging, [18 F]EAEF showed high uptake in progesterone receptor-positive MCF-7 tumor (3.15 ± 0.07% ID/g at 2 hr p.i.) with good tumor to muscle ratio (2.90), and obvious lower tumor uptakes were observed in MCF-7 with EAEF blocking (1.84 ± 0.05% ID/g at 2 hr p.i.) or in progesterone receptor-negative MDA-MB-231 tumor (1.80 ± 0.03% ID/g at 2 hr p.i.). Based on the good stability and specificity of [18 F]EAEF, it may be a good candidate for imaging progesterone receptor and worth further investigation.

A Silver(I)-Estrogen Nanocluster: GSH Sensitivity and Targeting Suppression on HepG2 Cell.

A structure-determined silver nanocluster of [Ag10 (Eth)4 (CF3 COO)6 (CH3 OH)3 ]·3C-H3 OH (Eth = ethisterone) (1), is firstly demonstrated by self-assembly of silver salt and ethisterone. Due to the thiophilicity of silver(I) ions, complex 1 shows reactivity with glutathione (GSH) molecules in solution and induces the fluorescence quenching behavior. Thus, complex 1 can be used as a fluorescent sensor for GSH. In consideration of the higher level of GSH in cancerous cells, complex 1 presents significant tumor suppression reactivity toward the human hepatocellular carcinoma (HepG2) cells with IC50 value of 165 × 10-9 m. Especially, complex 1 displays 3.4-fold higher in vitro cytotoxicity to HepG2 cells than that of the normal CCC-HEL-1 cells, which makes complex 1 a potential targeting suppression agent for cancerous cells. The molecular design of complex 1 not only generates a new medicine-silver(I) cluster family, but also opens a new avenue to the targeting anticancer organosilver(I) materials.

Androgen receptor antagonism by divalent ethisterone conjugates in castrate-resistant prostate cancer cells.

Sustained treatment of prostate cancer with androgen receptor (AR) antagonists can evoke drug resistance, leading to castrate-resistant disease. Elevated activity of the AR is often associated with this highly aggressive disease state. Therefore, new therapeutic regimens that target and modulate AR activity could prove beneficial. We previously introduced a versatile chemical platform to generate competitive and non-competitive multivalent peptoid oligomer conjugates that modulate AR activity. In particular, we identified a linear and a cyclic divalent ethisterone conjugate that exhibit potent anti-proliferative properties in LNCaP-abl cells, a model of castrate-resistant prostate cancer. Here, we characterize the mechanism of action of these compounds utilizing confocal microscopy, time-resolved fluorescence resonance energy transfer, chromatin immunoprecipitation, flow cytometry, and microarray analysis. The linear conjugate competitively blocks AR action by inhibiting DNA binding. In addition, the linear conjugate does not promote AR nuclear localization or co-activator binding. In contrast, the cyclic conjugate promotes AR nuclear localization and induces cell-cycle arrest, despite its inability to compete against endogenous ligand for binding to AR in vitro. Genome-wide expression analysis reveals that gene transcripts are differentially affected by treatment with the linear or cyclic conjugate. Although the divalent ethisterone conjugates share extensive chemical similarities, we illustrate that they can antagonize the AR via distinct mechanisms of action, establishing new therapeutic strategies for potential applications in AR pharmacology.

Novel C,N-chelate platinum(II) antitumor complexes bearing a lipophilic ethisterone pendant.

The novel steroidal carrier ligand 17-α-[4'-ethynyl-dimethylbenzylamine]-17-ß-testosterone (ET-dmba 1) and the steroid--C,N-chelate platinum(II) derivatives [Pt(ET-dmba)Cl(L)] (L = DMSO (2) and PTA (3; PTA =1,3,5-triaza-7-phosphaadamantane)) have been prepared. Values of IC(50) were calculated for the new platinum complexes 2 and 3 against a panel of human tumor cell lines representative of ovarian (A2780 and A2780cisR) and breast cancers (T47D). At 48h incubation time complexes 2 and 3 show very low resistance factors (RF of <2) against an A2780 cell line which has acquired resistant to cisplatin and were more active than cisplatin (about 4-fold for 3) in T47D (AR+, AR=androgen receptor). Compound 1 retains a moderate degree of relative binding affinity (RBA=0.94%) for androgen receptors. The cytotoxicity of the non steroidal platinum analogues [Pt(dmba)Cl(L)] (dmba=dimethylbenzylamine; L=DMSO (4) and PTA (5)) has also been studied for comparison purposes. Theoretical calculations at the BP86/def2-TZVP level of theory on complex 3 have been undertaken.

Structure-activity relationships of synthetic progestins in a yeast-based in vitro androgen bioassay.

The recent identification of tetrahydrogestrinone (THG), a non-marketed designer androgen used for sports doping but previously undetectable by established mass spectrometry-based urine drug screens, and its production by a facile chemical modification of gestrinone has raised concerns about the risks of developing designer androgens from numerous marketed progestins. We therefore have used yeast-based in vitro androgen and progesterone bioassays to conduct a structure-activity study assessing the intrinsic androgenic potential of commercially available progestins and their derivatives, to identify those compounds or structures with the highest risk of forming a basis for such misapplication. Progestins had a wide range of androgenic bioactivity that was not reliably predicted for individual steroids by their progestin bioactivity. 17alpha-Hydroxyprogesterone and 19-norprogesterone derivatives with their bulky 17beta-substituents were strong progestins but generally weak androgens. 17alpha-Ethynylated derivatives of testosterone, 19-nortestosterone and 18-methyl-19-nortestosterone such as gestrinone, ethisterone, norethisterone and norgestrel had the most significant intrinsic androgenicity of all the commercially marketed progestins. Facile chemical modification of the 17alpha-ethynyl group of each of these progestins produces 17alpha-methyl, ethyl and allyl derivatives, including THG and norbolethone, which further enhanced androgenic bioactivity. Thus by using the rapid and sensitive yeast bioassay we have screened a comprehensive set of progestins and associated structures and identified the ethynylated testosterone, 19-nortestosterone and 18-methyl-19-nortestosterone derivatives as possessing the highest risk for abuse and potential for conversion to still more potent androgens. By contrast, modern progestins such as progesterone, 17alpha-hydroxyprogesterone and 19-norprogesterone derivatives had minimal androgenic bioactivity and pose low risk.

Microbial transformation of 17alpha-ethynyl- and 17alpha-ethylsteroids, and tyrosinase inhibitory activity of transformed products.

The microbial transformation of the 17alpha-ethynyl-17beta-hydroxyandrost-4-en-3-one (1) (ethisterone) and 17alpha-ethyl-17beta-hydroxyandrost-4-en-3-one (2) by the fungi Cephalosporium aphidicola and Cunninghamella elegans were investigated. Incubation of compound 1 with C. aphidicola afforded oxidized derivative, 17alpha-ethynyl-17beta-hydroxyandrosta-1,4-dien-3-one (3), while with C. elegans afforded a new hydroxy derivative, 17alpha-ethynyl-11alpha,17beta-dihydroxyandrost-4-en-3-one (4). On the other hand, the incubation of compound 2 with the fungus C. aphidicola afforded 17alpha-ethyl-17beta-hydroxyandrosta-1,4-dien-3-one (5). Two new hydroxylated derivatives, 17alpha-ethyl-11alpha,17beta-dihydroxyandrost-4-en-3-one (6) and 17alpha-ethyl-6alpha,17beta-dihydroxy-5alpha-androstan-3-one (7) were obtained from the incubation of compound 2 with C. elegans. Compounds 1-6 exhibited tyrosinase inhibitory activity, with compound 6 being the most potent member (IC(50)=1.72 microM).

Effects of nitric oxide on aldosterone synthesis and nitric oxide synthase activity in glomerulosa cells from bovine adrenal gland.

This study investigated the effects of two NO-releasing agents, diethylenetriamine-NO (deta-NO) and sodium nitroprusside (SNP), on basal, ACTH-, and angiotensin II (AngII)-stimulated aldosterone production in glomerulosa cells from bovine adrenal gland. NO donors inhibited basal and ACTH- or AngII-stimulated aldosterone synthesis in a concentration-dependent manner. Deta-NO and SNP also provoked a concentration-dependent stimulation of cGMP production. However, cGMP was not responsible for the inhibition of aldosterone secretion, because a cGMP analog did not reproduce the inhibitory effect. Moreover, soluble guanylyl cyclase or protein kinase G inhibitors did not revert the inhibitory effect of NO on aldosterone production. NO donors did not modify ACTH-stimulated cAMP production or AngII-stimulated PLC activity stimulation, but inhibited 22[R] hydroxycholesterol- or pregnenolone-stimulated aldosteronogenesis. NO can be synthesized in bovine glomerulosa cells because nitrite production was determined and characterization of NOS activity was also performed. Nitrite accumulation was not modified in the presence of ACTH, AngII, or other factors used to induce iNOS. NOS activity that showed a Michaelis-Menten kinetic was NADPH- and calcium-dependent and was inhibited by two competitive inhibitors, L-NAME and L-NMMA. These results show that NO inhibits aldosterone production in glomerulosa cells acting on P450scc and other P450-dependent steroidogenic enzymes, and these cells display NOS activity suggesting that NO can be produced by constitutive NOS isozymes.

5alpha-reduction of norethisterone enhances its binding affinity for androgen receptors but diminishes its androgenic potency.

Norethisterone (NET), a 19-nor synthetic progestin, undergoes enzyme-mediated 5alpha-reduction and exerts potent androgenic effects in target organs. To investigate its mode of androgenic action we examined, in a comparative manner, the in vitro metabolism of NET and testosterone (T), as well as the binding affinities to androgen receptors (AR) and the androgenic potency of NET, T, and their 5alpha-reduced derivatives. Bioconversion of [3H]-NET and [3H]-T was studied in rat prostate homogenates, AR binding affinity was assessed in rat ventral prostates using [3H]-mibolerone as the radioligand, and the androgenic potency was evaluated by the increase of beta-glucuronidase activity in the mouse kidney, and by the growth of accessory sex organs in castrated male rats. The results demonstrated that 5alpha-NET displayed a higher AR binding affinity but a significantly lower androgenic potency than unchanged NET. The bioconversion studies indicated that the metabolism of NET was similar to that of T, although to a lesser extent, thus ruling out the possibility that the synthetic progestin metabolizes rapidly into less active derivatives. To investigate the nature of the paradoxical effect of 5alpha-reduction upon the NET molecule, the interaction with AR and the androgenic potency of T, 19-nortestosterone (19norT), 17alpha-ethynyl testosterone (ET) and their 5alpha-reduced derivatives were examined. The results of AR binding studies revealed that 5alpha-reduction of T and ET significantly enhanced their affinities, and that the 5alpha-derivative of 19norT displayed a similar binding affinity to that exhibited by 19norT. In terms of biological activity, the results showed that 5alpha-reduction of T and 19norT significantly increased their androgenic potency, whereas 5alpha-reduction of ET resulted in a significant diminution of its androgenicity in a manner similar to that observed with the 5alpha-reduction of NET. When NET and 19norT were simultaneously administered with 5alpha-dihydrotestosterone they exhibited a potent synandrogenic activity, an effect that was cancelled by their 5alpha-reduction. Interestingly, ET displayed an antiandrogenic activity, an effect that was also suppressed by its 5alpha-reduction. The overall results demonstrated a distinctive, paradoxical effect of 5alpha-reduction upon the NET molecule, which was different from that seen in naturally occurring androgens, and which suggests that the presence of the 17alpha-ethynyl group plays a key role in this phenomenon. The data provided further evidence that the metabolism of synthetic contraceptive progestins modulates the expression of their hormone-like actions.

Identification of progesterone binding sites in the plasma membrane of the filamentous fungus Cochliobolus lunatus.

Plasma membrane associated binding sites for progesterone have been identified in the filamentous fungus Cochliobolus lunatus (C. lunatus). The Kd for progesterone determined by Scatchard analysis was 13.9 +/- 5.7 nM and the Bmax was 250-360 fmol/mg protein. A broad ligand specificity of these binding sites is suggested by the observation that all tested steroids, regardless of their capability to act as inducers of the 11 beta-steroid hydroxylase, competed at 250-fold excess with [3H]progesterone binding. A biological role of these plasma membrane associated steroid binding sites is nevertheless suggested since in protoplasts which were devoid of them, 11 beta-steroid hydroxylase could not be induced. Progesterone binding sites were present in the plasma membrane as well as in the cytosol and were detected in this fraction, in contrast to the plasma membrane fraction, only under special experimental conditions in respect to redox state. Kd and Bmax of cytosol binding sites were of the same order of magnitude compared to the plasma membrane progesterone binding sites. Ethisterone and 4-cholesten-3-one which cannot induce 11 beta-hydroxylase competed efficiently for plasma membrane binding sites; ethisterone, however also competed for cytosol binding sites and acted, in contrast with 4-cholesten-3-one, as antagonist in the induction of 11 beta-steroid hydroxylase in C. lunatus. On the basis of presented evidence we concluded that C. lunatus contains binding sites for steroids in the plasma membrane and in the cytosol and that both types of binding site are involved in the process of induction of enzymes which transform steroids in this fungus.

Progesterone receptor induction by danazol in cultured cancer cells and the rat uterus.

We have previously reported that clinical trials relating to the use of danazol in the management of benign breast disease show a positive correlation between favourable clinical response and an induction of progesterone receptors in the affected tissue which is maintained for a period of at least 6 months subsequent to the cessation of treatment. Further studies designed at elucidating more clearly the actions of danazol at the cellular and molecular levels have confirmed that progesterone receptors are down-regulated by short-term progestin action at the level of the mRNA transcript, but that danazol is subsequently able to produce an enhanced cellular response, inducing progesterone receptors in the presence of oestrogenic agents. Uteri from danazol-treated rats showed a doubling of progesterone receptor concentrations compared with the control uteri. In the mammary cancer cell line T-47D, cells treated with danazol had increased progesterone receptor concentrations of 558.4 +/- 32.0 compared with 152.6 +/- 7.0 fmol/mg protein in the control cells. In both cases, these inductions were observed following a period of progesterone receptor suppression. Short-term molecular studies on T-47D cells indicated that progesterone and danazol initially inhibit mRNA transcription, but that 24 h after treatment an induction is observed. This is especially marked in the danazol-treated cells.

Hormonal sex manipulation and evidence for female homogamety in channel catfish.

The mechanism of sex determination in channel catfish Ictalurus punctatus was evaluated by hormonal and genetic methods. Aromatizable and nonaromatizable androgens, as well as an estrogen, caused feminization in fish fed steroids for 21 days after yolk-sac absorption. The effectiveness of 60 micrograms of ethynyltestosterone/g food decreased markedly when the experimental feeding period was shortened and was ineffective when the treatment lasted less than 12 days. Females from all-female populations produced by treatment with sex hormones were mated with normal males resulting in nine spawns with a sex ratio different from 1:1. The sex ratios were statistically similar to 3 male: 1 female in five spawns, both 2:1 and 3:1 in two spawns, and 2:1 in two spawns. These data are consistent with a model for female homogametic sex determination in channel catfish and suggest that the YY equivalent genotype is viable.

Influence of steroid hormones on protein-platelet interaction at the blood-polymer interface.

To develop artificial materials for prolonged use in the vascular system, the complicated process of surface-induced thrombosis needs to be better understood. Steroidal hormones have a profound role in thrombosis and haemostasis, although adequate studies are not available to demonstrate their part in the thromboembolic phenomena that occur at the blood-foreign material interface. We studied the interfacial phenomena of five steroid hormonal drugs, Sustanon, Menstrogen, Mixogen, Durabolin and Ovral and their interaction with proteins and platelets toward an artificial surface using contact angle, polyacrylamide gel electrophoresis, trace labelling methods, etc. This study demonstrates the effect of these hormones to modulate platelet-surface attachment in the presence of platelet inducers. The addition of steroid hormones to the polymer-protein system can inhibit the level of surface-bound albumin where the fibrinogen binding to an artificial surface has been enhanced or unaltered. Steroids also increase platelet-surface attachment to variable degrees. Prolonged use of steroids or the oestrogen-containing oral contraceptive agents may not be advisable for patients having an artificial implant in contact with blood.

The inhibitory effects of danazol, danazol metabolites, gestrinone, and testosterone on the growth of human endometrial cells in vitro.

Danazol and gestrinone are effective drugs in the treatment of endometriosis. Their mechanism of action remains uncertain, but may be related to their androgenic activity. The authors examined the effect of danazol on human endometrial cells cultured in vitro, its two major metabolites, ethisterone and 2 hydroxymethyl ethisterone, gestrinone, and testosterone (T) at 1X and 10X expected plasma concentrations. Danazol and T suppressed growth by 20.8 and 25.0% (P less than 0.01), respectively, at the lower dose, and by 26.9 and 35.5% (P less than 0.01), respectively, at the 10-fold higher dose. No significant suppression of growth occurred with gestrinone, ethisterone, or 2 hydroxymethyl ethisterone. The results provide further evidence that danazol and T (but not gestrinone) may act by a direct effect on endometrial tissue.

[Pharmacological activity of progesterone derivatives]. / Farmakologicheskaia aktivnost' nekotorykh proizvodnykh progesterona.

Tests conducted on rabbits demonstrated that the progesterone derivatives--megestol-acetate, mepregnol-diacetate, melengestrol-acetate, megestro-capronate--display a higher progestagenic action than do progesterone and pregnene. Tests with rats revealed the contraceptive action to be highest with a long-term administration of low doses of mestranol and melengestrol-acetate (ratio of 1:50), or with introduction of mestranol and megpregno-diacetate (ratio of 1:20). When used together with mestranol megestrol-capronate manifests a greater ability of prolonged action and a higher effectiveness in the pre-implantation period as compared to a combination of megestrol-acetate and mestranol.