Donald Poirier

Chemopreventive and adjuvant therapeutic potential of pomegranate (Punica granatum) for human breast cancer

Fresh organically grown pomegranates (Punica granatum L.) of the Wonderful cultivar were processed into three components: fermented juice, aqueous pericarp extract and cold-pressed or supercritical CO2-extracted seed oil. Exposure to additional solvents yielded polyphenol-rich fractions (‘polyphenols’) from each of the three components. Their actions, and of the crude whole oil and crude fermented and unfermented juice concentrate, were assessed in vitro for possible chemopreventive or adjuvant therapeutic potential in human breast cancer. The ability to effect a blockade of endogenous active estrogen biosynthesis was shown by polyphenols from fermented juice, pericarp, and oil, which inhibited aromatase activity by 60–80%. Fermented juice and pericarp polyphenols, and whole seed oil, inhibited 17-β-hydroxysteroid dehydrogenase Type 1 from 34 to 79%, at concentrations ranging from 100 to 1,000 μg/ml according to seed oil ≫ fermented juice polyphenols > pericarp polyphenols. In a yeast estrogen screen (YES) lyophilized fresh pomegranate juice effected a 55% inhibition of the estrogenic activity of 17-β-estradiol; whereas the lyophilized juice by itself displayed only minimal estrogenic action. Inhibition of cell lines by fermented juice and pericarp polyphenols was according to estrogen-dependent (MCF-7) ≫ estrogen- independent (MB-MDA-231) > normal human breast epithelial cells (MCF-10A). In both MCF-7 and MB-MDA-231 cells, fermented pomegranate juice polyphenols consistently showed about twice the anti-proliferative effect as fresh pomegranate juice polyphenols. Pomegranate seed oil effected 90% inhibition of proliferation of MCF-7 at 100 μg/ml medium, 75% inhibition of invasion of MCF-7 across a Matrigel membrane at 10 μg/ml, and 54% apoptosis in MDA-MB-435 estrogen receptor negative metastatic human breast cancer cells at 50 μg/ml. In a %% murine mammary gland organ culture, fermented juice polyphenols effected 47% inhibition of cancerous lesion formation induced by the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The findings suggest that clinical trials to further assess chemopreventive and adjuvant therapeutic applications of pomegranate in human breast cancer may be warranted.

Metal-based biologically active agents: synthesis, characterization, antibacterial and antileukemia activity evaluation of Cu(II), V(IV) and Ni(II) complexes with antipyrine-derived compounds.

The paper presents the synthesis of complex combinations of Cu(II), V(IV) and Ni(II) with Schiff bases obtained through the condensation of 4-amino-1,5-dimethyl-2-phenyl-1H-3-pyrazol-3(2H)-one (antipyrine) with 2-hydroxybenzaldehyde, 4-hydroxy-5-methoxyisophthalaldehyde and 4,5-dihydroxyisophalaldehyde respectively. The characterization of newly formed complexes was done by (1)H NMR, (13)C NMR, UV-VIS, IR, EPR spectroscopies and molar electric conductibility studies. The effect of these complexes on proliferation of human leukemia cells (HL-60) and their antibacterial activity against Staphylococcus aureus var. Oxford 6538, Escherichia coli ATCC 10536 and Candida albicans ATCC 10231strains were studied and compared with those of free ligands.

Antiestrogenic properties of keoxifene,trans-4-hydroxytamoxifen, and ICI 164384, a new steroidal antiestrogen, in ZR-75-1 human breast cancer cells

The agonistic/antagonistic properties of two non-steroidal antiestrogens, namelytrans-4-monohydroxy-tamoxifen (OH-TAM) and keoxifene (LY156758), and the new steroidal antiestrogen ICI164384, a 7β-alkylamide derivative of estradiol (E2), were assessed by measuring their effect on the proliferation of ZR·75-1 cells, an estrogen-responsive human breast cancer cell line. While subnanomolar concentrations of both OH-TAM and LY156758 had significant estrogenic stimulatory activity on cell growth in the absence of estrogens and higher concentrations were inhibitory, ICI164384 behaved exclusively as a growth inhibitor and more potently so than the two other compounds. The three antiestrogens had similar potency to inhibit the mitogenic effect of E2 and at 300 nM, all antiproliferative effects were completely reversible by the estrogen. ICI164384 was a weaker competitor of3H-labeled E2 or R2858 (moxestrol) uptake in intact ZR-75-1 cells in a 1-hour assay, partly because of a slower intracellular access to estrogen specific binding sites. Moreover, ICI164384 interacted in a rapidly (~ 6 h) reversible manner with estrogen-specific binding sites, while the non-steroidal antiestrogens induced a longer-acting (> 24 h) down-regulation of specific [3H]R2858 uptake. The present data indicate that, among the antiestrogens studied, ICI164384 is the only compound acting as a pure antiestrogen in ZR-75-1 breast cancer cells, while LY156758 and OH-TAM behave as antiestrogens endowed with partial agonistic activity in this system.

Androgen and glucocorticoid receptor-mediated inhibition of cell proliferation by medroxyprogesterone acetate in ZR-75-1 human breast cancer cells

Medroxyprogesterone acetate (MPA) is a synthetic progestin, currently used in the adjuvant treatment of advanced breast cancer, which induces remission rates (30–40%) comparable to those obtained with other types of endocrine therapies. Since, in addition to its progestin-like action, MPA exhibits androgen- and glucocorticoid-like activities in other tissues, the present study was designed to assess the relative contribution of the different steroid receptor systems in the direct action of MPA on breast cancer cell growth, using the ZR-75-1 human mammary carcinoma cell line as anin vitro model.Unlike pure progestins, MPA potently inhibited the proliferation of ZR-75-1 cells in a concentrationdependent manner either in the presence or in the absence of estrogens, and the addition of insulin had only marginal effects on its growth-inhibitory activity. On the other hand, both hydroxyflutamide (OHF, a non-steroidal monospecific antiandrogen) and RU486 (a potent antiglucocorticoid and antiprogestin also endowed with antiandrogenic activity) competitively reversed MPA antiproliferative effects. MPA further decreased the growth of ZR-75-1 cells co-incubated with maximally inhibitory concentrations of either 5α-dihydrotestosterone (DHT) or dexamethasone (DEX), although at about 300-fold higher MPA concentrations with DHT-treated than with DEX-treated ZR-75-1 cells, thus demonstrating a highly predominant androgenic effect. However, MPA had no effect on the growth of ZR-75-1 cells co-incubated with DHT and DEX simultaneously, thus supporting the predominant role of androgen and glucocorticoid receptors in MPA action. A 12-day preincubation of ZR-75-1 cells with increasing concentrations of MPA (10−12 to 3 × 10−6M) decreased the specific uptake of [3H]estradiol (E2) by intact cell monolayers to the same extent as 10 nM DHT, an effect which was competitively blocked by the addition of OHF (3 µM). MPA action on ZR-75-1 cell growth also significantly differed from that of progestins in being additive to the inhibition of E2-stimulated growth by the steroidal antiestrogen ICI164384.The present data indicate that the main action of MPA on ZR-75-1 human breast cancer cell growth is due to its androgen receptor-mediated inhibitory action, while its glucocorticoid-like activity could play an additional role at high concentrations.

A concerted, rational design of type 1 17beta-hydroxysteroid dehydrogenase inhibitors: estradiol-adenosine hybrids with high affinity

Human estrogenic 17β‐hydroxysteroid dehydrogenase (17β‐HSD type 1) catalyzes the final step in the synthesis of active estrogens that stimulate the proliferation of breast cancer cells. Based on the initial premise to make use of the binding energies of both the substrate and cofactor sites, and molecular modeling starting from the enzyme structure, several estradiol‐adenosine hybrids were designed and synthesized. Among these hybrids, EM‐1745 with a linker of 8‐CH2 groups is proved to be the best competitive inhibitor with a Ki of 3.0 ± 0.8 nM. The crystal structure of the EM‐1745 enzyme complex at 1.6 Å provides evidence at atomic resolution of strong interactions between both the steroid and cofactor moieties and the enzyme molecule, as illustrated by a σAweighted 2Fo‐Fc electron density map contoured at 3.0 σ. The substrate entry loop is further stabilized in this complex compared with previous complexes of the enzyme. These results confirm our initial strategy of combining studies of structural biology and enzyme mechanism in the inhibitor design, which may be applied to other steroidogenic enzymes involved in human diseases.

Molecular therapy of breast cancer: progress and future directions

Breast cancer is a major cause of death in Western women, with a 10% lifetime risk of the disease. Most breast cancers are estrogen-dependent. Molecular therapies for breast cancer have developed rapidly in the past few decades and future treatment strategies are being investigated. The selective estrogen receptor (ER) modulator tamoxifen, which until now has served as a standard therapy, functions not only as an estrogen antagonist but also as an estrogen agonist in terms of bone maintenance. Aromatase inhibitors have performed well in international trials and have become a new standard therapy for estrogen-dependent breast cancer. The systematic study of estrogen activation pathways suggests that the enzymes steroid sulfatase and 17β-hydroxysteroid dehydrogenase type 1, which both have pivotal roles in estrogen biosynthesis, are promising targets; the results of a phase I trial of steroid sulfatase inhibitors are encouraging. The activity of the human epidermal growth factor receptor (HER) pathway correlates negatively with that of the ER. HER2 is overexpressed in 22% of all breast cancers. In the decade since HER2 began being targeted, the monoclonal antibody trastuzumab has been used as well as pertuzumab and HER2 vaccines. Among the estrogen-independent breast cancers, the basal-like subtype has low survival, and therapeutic improvement is a priority. Crosstalk between ER and HER2 signaling pathways means that combinatory therapies may hold the key to enhancement of treatment responses. Other molecular therapies involving functional genomics and RNA interference studies also hold promise.

Overview of a rational approach to design type I 17β-hydroxysteroid dehydrogenase inhibitors without estrogenic activity : Chemical synthesis and biological evaluation

Hormone-sensitive diseases such as breast cancer are health problems of major importance in North America and Europe. Endocrine therapies using antiestrogens for the treatment and the prevention of breast cancer are presently under clinical trials. Antiestrogens are drugs that compete with estrogens for the estrogen receptor without activating the transcription of estrogen-sensitive genes. However, an optimal blockade of estrogen action could ideally be achieved by a dual-action compound that would antagonize the estrogen receptor and inhibit the biosynthesis of estradiol. Type I 17beta-hydroxysteroid dehydrogenase (17beta-HSD) was chosen as a key steroidogenic target enzyme to inhibit the formation of estradiol, which is the most potent estrogen. This article describes a rational approach that could lead to the development of compounds that exhibit both actions. The chemical syntheses of estradiol derivatives bearing a bromoalkyl and a bromoalkylamide side chain at the 16alpha-position are summarized. Two parameters were studied for biological evaluation of our synthetic inhibitors: (1) the inhibition of estrone reduction into estradiol by type I 17beta-HSD, and (2) the proliferative/antiproliferative cell assays performed on the estrogen-sensitive ZR-75-1 breast tumor cell line. First, the substitution of the 16alpha-position of estradiol by bromoalkyl side chain led to potent inhibitors of type I 17beta-HSD, but the estrogenic activity remained. Secondly, an alkylamide functionality at the 16alpha- or 7alpha-position of estradiol cannot abolish the estrogenic activity without affecting considerably the inhibitory potency on type I 17beta-HSD. In conclusion, the best dual-action inhibitor synthesized showed an IC50 of 13 +/- 1 microM for type I 17beta-HSD, while displaying antiestrogenic activity at 1.0 microM. Despite the fact that we did not obtain an ideal dual-action blocker, we have optimized several structural parameters providing important structure-activity relationship.

Steroid sulfatase inhibitors

Steroid sulfatase catalyses the hydrolysis of sulfated steroids to their corresponding hydroxylated forms. Since oestrogens and androgens can be synthesised intracellularly from the abundant circulating sulfated steroids, steroid sulfatase inhibitors should prove to be valuable therapeutic agents for the treatment of hormono-dependent diseases. Furthermore, steroid sulfatase inhibitors have been reported to control brain concentrations of sulfated neurosteroids and also to improve memory. Such therapeutic potential stimulated research and development of steroid sulfatase inhibitors and important progress has been achieved during the last ten years. This review focuses on patented steroid sulfatase inhibitors, but discussion of unpatented inhibitors published in the literature has been included to complement the information presented.

Estrogen receptor-α mediates an intraovarian negative feedback loop on thecal cell steroidogenesis via modulation of Cyp17a1 (cytochrome P450, steroid 17α-hydroxylase/17,20 lyase) expression

Excess androgen synthesis by thecal cells is invariably detrimental to preovulatory follicles in the ovary and is considered a fundamental characteristic of polycystic ovary syndrome in women. Investigators have long postulated that granulosa cell‐derived estrogens modulate thecal cell steroidogenesis via a short negative‐feedback loop within the follicle. To test this hypothesis, we assessed the steroidogenic capacity of individual wild‐type (WT) and estrogen receptor‐ (ERα)‐null follicles when cultured in vitro under comparable conditions. Late‐stage ERα‐null follicles exhibited markedly increased expression of the thecal cell enzyme CYP17A1 and secreted much greater amounts of its end product, androstenedione. This phenotype was reproduced in WT follicles when exposed to an aromatase inhibitor or ER‐antagonist, and prevented when the former treatment was supplemented with an ERα‐specific agonist. ERα‐null follicles also exhibited increased testosterone synthesis due to ectopic expression of hydroxysteroid (17ß) dehydrogenase type 3 (HSD17B3), a testis‐specific androgenic enzyme. These data indicate that ER17α functions within thecal cells to negatively modulate the capacity for androgen synthesis by repressing Cyp17a1 expression, and the biological activity of androgens produced by inhibiting Hsd17b3 expression. Hence, these findings provide novel evidence of an intraovarian ERα function that may be critical to the latter stages of folliculogenesis and overall ovarian function.—Taniguchi, F., Couse, J. F., Rodriguez, K. F., Emmen, J. M. A., Poirier. D., Korach, K. S. Estrogen receptor‐17α mediates an intraovarian negative feedback loop on thecal cell steroidogenesis via modulation of CYP17A1 (cytochrome P450, steroid 17α‐hydroxylase/17,20 μlyase) expression FASEB J. 21, 586 −595 (2007)

17β-Hydroxysteroid dehydrogenase inhibitors: a patent review

Importance of the field: 17β-Hydroxysteroid dehydrogenases (17β-HSDs) mainly catalyze the reduction of C17-ketosteroids to their corresponding hydroxylated forms as well as the reverse reaction (oxidation). Able to convert inactive or less active steroid hormones into more potent ones and vice versa, certain 17β-HSDs play a key role, especially in the regulation of estrogen and androgen levels. The therapeutic potential of this enzyme family, especially for the treatment of breast cancer, prostate cancer, acne and osteoporosis, then stimulated the development of inhibitors of 17β-HSDs and important progress was achieved over the last years. Areas covered in this review: This review article reports all patent applications related to the inhibitors of 17β-HSDs, including some articles needed to complement the information presented. What the reader will gain: Readers will be informed about the role and function of 17β-HSDs in the first section and about the history of inhibitor development in the second section. Furthermore, in the third and main section, the readers will learn about the structures of patented inhibitors originating from different companies and academic groups. Take home message: The increase in the number of 17β-HSD inhibitors reported in the last years augurs well for the future. The challenge is now to translate these results into clinical studies to allow determination of the therapeutic usefulness of 17β-HSD inhibitors.