Gilles Tremblay

EM-652 (SCH 57068), a third generation SERM acting as pure antiestrogen in the mammary gland and endometrium

Breast cancer is the most frequent cancer in women while it is the second cause of cancer death. Estrogens are well recognized to play the predominant role in breast cancer development and growth and much efforts have been devoted to the blockade of estrogen formation and action. The most widely used therapy of breast cancer which has shown benefits at all stages of the disease is the use of the antiestrogen Tamoxifen. This compound, however, possesses mixed agonist and antagonist activity and major efforts have been devoted to the development of compounds having pure antiestrogenic activity in the mammary gland and endometrium. Such a compound would avoid the problem of stimulation of the endometrium and the risk of endometrial carcinoma. We have thus synthesized an orally active non-steroidal antiestrogen, EM-652 (SCH 57068) and the prodrug EM-800 (SCH57050) which are the most potent of the known antiestrogens. EM-652 is the compound having the highest affinity for the estrogen receptor, including estradiol. It has higher affinity for the ER than ICI 182780, hydroxytamoxifen, raloxifene, droloxifene and hydroxytoremifene. EM-652 has the most potent inhibitory activity on both ER alpha and ER beta compared to any of the other antiestrogens tested. An important aspect of EM-652 is that it inhibits both the AF1 and AF2 functions of both ER alpha and ER beta while the inhibitory action of hydroxytamoxifen is limited to AF2, the ligand-dependent function of the estrogen receptors. AF1 activity is constitutive, ligand-independent and is responsible for mediation of the activity of growth factors and of the ras oncogene and MAP-kinase pathway. EM-652 inhibits Ras-induced transcriptional activity of ER alpha and ER beta and blocks SRC-1-stimulated activity of the two receptors. EM-652 was also found to block the recruitment of SRC-1 at AF1 of ER beta, this ligand-independent activation of AF1 being closely related to phosphorylation of the steroid receptors by protein kinase. Most importantly, the antiestrogen hydroxytamoxifen has no inhibitory effect on the SRC-1-induced ER beta activity while the pure antiestrogen EM-652 completely abolishes this effect, thus strengthening the need to use pure antiestrogens in breast cancer therapy in order to control all known aspects of ER-regulated gene expression. In fact, the absence of blockade of AF2 by hydroxytamoxifen could explain why the benefits of tamoxifen observed up to 5 years become negative at longer time intervals and why resistance develops to tamoxifen. EM-800, the prodrug of EM-652, has been shown to prevent the development of dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in the rat, a well-recognized model of human breast cancer. It is of interest that the addition of dehydroepiandrosterone, a precursor of androgens, to EM-800, led to complete inhibition of tumor development in this model. Not only the development, but also the growth of established DMBA-induced mammary carcinoma was inhibited by treatment with EM-800. An inhibitory effect was also observed when medroxyprogesterone was added to treatment with EM-800. Uterine size was reduced to castration levels in the groups of animals treated with EM-800. An almost complete disappearance of estrogen receptors was observed in the uterus, vaginum and tumors in nude mice treated with EM-800. EM-652 was the most potent antiestrogen to inhibit the growth of human breast cancer ZR-75-1, MCF-7 and T-47D cells in vitro when compared with ICI 182780, ICI 164384, hydroxytamoxifen, and droloxifene. Moreover, EM-652 and EM-800 have no stimulatory effect on the basal levels of cell proliferation in the absence of E2 while hydroxytamoxifen and droloxifene had a stimulatory effect on the basal growth of T-47D and ZR-75-1 cells. EM-652 was also the most potent inhibitor of the percentage of cycling cancer cells. (ABSTRACT TRUNCATED)

4-Hydroxytamoxifen Is an Isoform-Specific Inhibitor of Orphan Estrogen-Receptor-Related (ERR) Nuclear Receptors β and γ

Selective estrogen receptor modulators (SERMs) are synthetic molecules that exhibit tissue-specific activities. 4-hydroxytamoxifen (OHT) is a first generation SERM that functions as an antagonist in breast cancer cells but displays estrogen-like activities in the uterus and bone. The estrogen-receptor-related receptors (ERR) α, β and γ are orphan members of the superfamily of nuclear receptors. While the ERRs do not respond to natural estrogens, these receptors recognize the estrogen response element and have been shown to activate and repress gene expression in the absence of exogenously added ligand. Here we show that OHT disrupts the interaction between the orphan estrogen-receptor-related (ERR) receptors β and γ and a coregulator protein and abolishs the constitutive transcriptional activity of these receptors in transient transfection assays. In contrast, OHT has no effect on coregulator/ERRα interaction or its transcriptional activity. These results demonstrate the existence of a novel nuclear recep...

EM-800, A NOVEL ANTIESTROGEN, ACTS AS A PURE ANTAGONIST OF THE TRANSCRIPTIONAL FUNCTIONS OF ESTROGEN RECEPTORS ALPHA AND BETA

Estrogens act as potent mitogens in a large number of breast cancers, and the use of estrogen receptor (ER) antagonists is, therefore, considered the endocrine therapy of choice in the management of this disease. We describe the molecular properties of EM-652, the active metabolite of EM-800, a novel nonsteroidal antiestrogen compound, on the transcriptional functions of ERα and ERβ. Using RT-PCR, we show that ERα and ERβ are expressed in mouse mammary glands, suggesting that both receptors should be considered putative targets for antiestrogen action in the breast. In cotransfection assays using a synthetic estrogen-responsive promoter, EM-652 shows no agonistic activity on ERα and ERβ transcriptional function and blocks the estradiol (E2)-mediated activation of both ERα and ERβ. EM-652 is also very effective in abrogating E2-stimulated ERα and ERβ trans-activation of the pS2 promoter in HeLa cells. EM-652 does not alter binding of ERα and ERβ to DNA. The Ras-mediated induction of ERα and ERβ transcripti...

Estrogen Receptor β: Re-evaluation of Estrogen and Antiestrogen Signaling

Abstract Estrogen is of vital importance for the development and control of reproductive functions. Until recently, estrogen was believed to regulate complex programs of gene expression by binding to an unique nuclear receptor belonging to the superfamily of ligand-dependent transcription factors. However, the identification of a second estrogen receptor, referred to as ERβ, is leading to a re-evaluation of estrogen signaling and physiology.

Soybean Tocopherol Concentrations Are Affected by Crop Management

Soybeans are an important source of tocopherols, which have health-beneficial properties. Previous studies have demonstrated that environmental factors may affect soybean tocopherol concentrations; the impact of specific crop management strategies, however, remains poorly understood. Experiments were conducted for 2 years at three sites in Quebec to determine the impact on soybean tocopherol concentrations of seeding rate, row spacing, seeding date, cultivar, and P and K fertilization. Total and alpha-, gamma-, and delta-tocopherol concentrations were determined by high-performance liquid chromatography. Overall, alpha-tocopherol was the most responsive to the factors evaluated; the response of other tocopherols was often lower or inconsistent across environments. The seeding rate affected alpha-tocopherol concentrations in three out of five environments; seeding at a rate of 40 seeds m(-2) resulted in 4% higher concentrations than seeding at a higher rate. Wide row spacing (more than 36 cm) resulted in two out of five environments in 6% higher alpha-tocopherol concentrations as compared to narrower row spacing. The seeding date had a greater impact; mid- to late-May seeding across four environments resulted in 45% greater alpha-tocopherol concentrations than seeding at later dates. Phosphorus and K fertilization had a negligible impact on tocopherol concentrations. Across experiments, large differences were observed between environments; plants grown in northern environments consistently had lower concentrations of alpha- and gamma-tocopherols but higher concentrations of delta-tocopherol. Differences between cultivars were also consistent, ranging between 10 and 30%, depending on the tocopherol. Results demonstrate that soybean tocopherol concentrations are affected by crop management and thus suggest that specific recommended agronomic practices may need to be established for the production of soybeans for the functional food market.

Mechanism and function of monoclonal antibodies targeting siglec-15 for therapeutic inhibition of osteoclastic bone resorption.

Background: Bone-resorbing osteoclasts express the Siglec-15 receptor on their plasma membrane. Results: Siglec-15 antibodies inhibit osteoclast differentiation and induce receptor endocytosis and degradation. Conclusion: These results establish that Siglec-15 antibodies target osteoclasts in vivo and reveal a likely mechanism of action. Significance: Siglec-15 could serve as a target of novel therapeutics for osteoporosis and cancer-associated bone loss. The use of monoclonal antibodies to target functionally important cell-surface proteins on bone-resorbing osteoclasts represents a promising approach for treatment of cancer-associated bone loss and other skeletal pathologies. Previously, we identified Siglec-15, a little studied sialic acid-binding receptor, as a candidate target that is highly up-regulated during osteoclast differentiation induced by the cytokine receptor activator of NF-κB ligand (RANKL). In this report, we confirm that Siglec-15 is localized to the plasma membrane where it can be targeted by monoclonal antibodies to inhibit differentiation of functional osteoclasts in vitro. Furthermore, we found that treatment of mice with these antibodies led to a marked increase in bone mineral density, consistent with inhibition of osteoclast activity. Interestingly, osteoblast numbers were maintained despite the anti-resorptive activity. At the molecular level, Siglec-15 interacts with the adapter protein DAP12 and can induce Akt activation when clustered on the osteoclast cell surface, which likely represents its normal signaling function. Importantly, we discovered that monoclonal antibodies induce rapid internalization, lysosomal targeting, and degradation of Siglec-15 by inducing receptor dimerization. This study defines a key regulatory node that controls osteoclast differentiation and activity downstream of RANKL and supports further development of Siglec-15 antibodies as a novel class of bone loss therapeutics.

Men's health promotion in Canada: Current context and future direction

The issue of ‘men’s health’, and how best to promote it, has been gaining increasing attention in both academic and media arenas across the globe. Whilst commentaries on the state of health promotion for men have been provided in countries including Australia and the United Kingdom, no corresponding Canadian-specific insights have yet been published. This article provides such an overview, focusing on research, policy and practice and suggesting what future direction men’s health promotion in Canada might take.

Identity and Disruptiveness in Boys: Longitudinal Perspectives

After more than 30 years of research on identity, the links between identity and disruptive behaviors are not clear. This study compared the identity formation of boys with stable disruptive behaviors from age 6 to age 15 (n = 16), with the identity formation of boys that were never disruptive during the same period (n = 25). All boys came from low socio-economic status families. At age 9 and 11, identity was assessed with the The Self-Perception Profile for Children (Harter, 1985). At age 15, identity was assessed with the Extended Objective Measure of Ego Identity Status (Adams, Bennion, & Huh, 1989) and two scales of the Offer Self-Image Questionnaire (Offer, Ostrov, & Howard, 1981). Differences between disruptive and non-disruptive boys were found only for behavior in childhood and identity in ideological domains at age 15. Explanations for the weakness of the link between identity and disruptiveness are discussed.

“Do it All by Myself” A Salutogenic Approach of Masculine Health Practice Among Farming Men Coping With Stress

Farming is often considered one of the most stressful occupations. At the same time, farming men symbolically represent a strong, traditional, or hegemonic form of masculinity based on stoicism, resourcefulness, and resilience to adversity. A contrast is observed between this social representation and their health status, marked by higher levels of stress, social isolation, psychological distress, and suicide than many other subgroups of men. A salutogenic approach was taken in this study to enable the investigation of the social contexts in which farming men positively engage in health-promoting behaviors that may prevent or ameliorate mental health problems. A focus was placed on how farming men cope with stress on their own, and the relationship of this to their popular image of being resourceful and resilient. Thirty-two individual in-depth interviews with farming men and a focus group with five key informants working in rural areas within the Province of Quebec, Canada, were carried out. Self-distraction and cognitive strategies emerged as the most relevant for participants. Notably, taking work breaks conflicted with the discourse of the “relentless worker” that farmers are expected to be. Pathways to positive coping and recovery implied an ambivalence between contemplation of strategies aligned with negative aspects of traditional masculinity norms in North America and strategies aligned with more positive, progressive aspects of these norms based on the importance of family and work life balance. Health promotion and future research should investigate how various positive masculine practices can be aligned with farmers’ health and well-being and that of their family.

Crop Management, Genotypes, and Environmental Factors Affect Soyasaponin B Concentration in Soybean

Soybean [Glycine max (L.) Merr.] seeds contain soyasaponin B, which has putative health benefits. Studies were conducted in multiple environments in Quebec, Canada to determine the effects of genotypes, environments, and seeding dates on soyasaponin B concentration in mature seeds. A growth chamber study was also conducted to determine the impact of high air temperature imposed at specific growth development stages on soyasaponin B in soybeans. Concentrations of individual and total soyasaponin B were determined using high-performance liquid chromatography. Genotype and environment main effects were the main determinants of soyasaponin B concentration in soybean, genotype × environment interactions accounting for less than 5% of the variation for all soyasaponin. Ranking of 20 early maturing soybean genotypes was thus relatively consistent across four environments, total concentration varying between 2.31 and 6.59 μmol g(-1). Seeding date consistently impacted soyasaponin B concentrations, early seeding date resulting in the highest concentrations. There was an 11% difference in total soyasaponin B concentration of soybeans seeded in mid-May compared to that in late-June. The response to high air temperature was complex and cultivar specific. High temperature stress restricted to the seed filling stages increased total soyasaponin B concentration in one cultivar by 28% when compared to that in control nonstressed plants; however, in another cultivar high temperature applied during all growth stages reduced total concentration by 27%. Results from the present study thus demonstrate that environmental factors and crop management both impact soyasaponin B concentration in soybeans.