Using 4-vinylcyclohexene diepoxide as a model of menopause for cardiovascular disease.

There is a sharp rise in cardiovascular disease (CVD) risk and progression with the onset of menopause. The 4-vinylcyclohexene diepoxide (VCD) model of menopause recapitulates the natural, physiological transition through perimenopause to menopause. We hypothesized that menopausal female mice were more susceptible to CVD than pre- or perimenopausal females. Female mice were treated with VCD or vehicle for 20 consecutive days. Premenopausal, perimenopausal, and menopausal mice were administered angiotensin II (ANG II) or subjected to ischemia-reperfusion (I/R). Menopausal females were more susceptible to pathological ANG II-induced cardiac remodeling and cardiac injury from a myocardial infarction (MI), while perimenopausal, like premenopausal, females remained protected. Specifically, ANG II significantly elevated diastolic (130.9 ± 6.0 vs. 114.7 ± 6.2 mmHg) and systolic (156.9 ± 4.8 vs. 141.7 ± 5.0 mmHg) blood pressure and normalized cardiac mass (15.9 ± 1.0 vs. 7.7 ± 1.5%) to a greater extent in menopausal females compared with controls, whereas perimenopausal females demonstrated a similar elevation of diastolic (93.7 ± 2.9 vs. 100.5 ± 4.1 mmHg) and systolic (155.9 ± 7.3 vs. 152.3 ± 6.5 mmHg) blood pressure and normalized cardiac mass (8.3 ± 2.1 vs. 7.5 ± 1.4%) compared with controls. Similarly, menopausal females demonstrated a threefold increase in fibrosis measured by Picrosirus red staining. Finally, hearts of menopausal females (41 ± 5%) showed larger infarct sizes following I/R injury than perimenopausal (18.0 ± 5.6%) and premenopausal (16.2 ± 3.3, 20.1 ± 4.8%) groups. Using the VCD model of menopause, we provide evidence that menopausal females were more susceptible to pathological cardiac remodeling. We suggest that the VCD model of menopause may be critical to better elucidate cellular and molecular mechanisms underlying the transition to CVD susceptibility in menopausal women.NEW & NOTEWORTHY Before menopause, women are protected against cardiovascular disease (CVD) compared with age-matched men; this protection is gradually lost after menopause. We present the first evidence that demonstrates menopausal females are more susceptible to pathological cardiac remodeling while perimenopausal and cycling females are not. The VCD model permits appropriate examination of how increased susceptibility to the pathological process of cardiac remodeling accelerates from pre- to perimenopause to menopause.

Sex dimorphisms of crossbridge cycling kinetics in transgenic hypertrophic cardiomyopathy mice.

Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertrophic, dilated, restrictive, and/or arrhythmogenic cardiomyopathy, congestive heart failure, or sudden cardiac death. We hypothesized that hearts from transgenic HCM mice harboring a mutant myosin heavy chain increase the energetic cost of contraction in a sex-specific manner. To do this, we assessed Ca(2+) sensitivity of tension and crossbridge kinetics in demembranated cardiac trabeculas from male and female wild-type (WT) and HCM hearts at an early time point (2 mo of age). We found a significant effect of sex on Ca(2+) sensitivity such that male, but not female, HCM mice displayed a decrease in Ca(2+) sensitivity compared with WT counterparts. The HCM transgene and sex significantly impacted the rate of force redevelopment by a rapid release-restretch protocol and tension cost by the ATPase-tension relationship. In each of these measures, HCM male trabeculas displayed a gain-of-function when compared with WT counterparts. In addition, cardiac remodeling measured by echocardiography, histology, morphometry, and posttranslational modifications demonstrated sex- and HCM-specific effects. In conclusion, female and male HCM mice display sex dimorphic crossbridge kinetics accompanied by sex- and HCM-dependent cardiac remodeling at the morphometric, histological, and cellular level.

Liver Kinase B1 complex acts as a novel modifier of myofilament function and localizes to the Z-disk in cardiac myocytes.

Contractile perturbations downstream of Ca(2+) binding to troponin C, the so-called sarcomere-controlled mechanisms, represent the earliest indicators of energy remodeling in the diseased heart [1]. Central to cellular energy "sensing" is the adenosine monophosphate-activated kinase (AMPK) pathway, which is known to directly target myofilament proteins and alter contractility [2-6]. We previously showed that the upstream AMPK kinase, LKB1/MO25/STRAD, impacts myofilament function independently of AMPK [5]. Therefore, we hypothesized that the LKB1 complex associated with myofilament proteins and that alterations in energy signaling modulated targeting or localization of the LKB1 complex to the myofilament. Using an integrated strategy of myofilament mechanics, immunoblot analysis, co-immunoprecipitation, mass spectroscopy, and immunofluorescence, we showed that 1) LKB1 and MO25 associated with myofibrillar proteins, 2) cellular energy stress re-distributed AMPK/LKB1 complex proteins within the sarcomere, and 3) the LKB1 complex localized to the Z-Disk and interacted with cytoskeletal and energy-regulating proteins, including vinculin and ATP Synthase (Complex V). These data represent a novel role for LKB1 complex proteins in myofilament function and myocellular "energy" sensing in the heart.

Canine Mammary Cancer: State of the Art and Future Perspectives.

Mammary cancer is the most frequently diagnosed neoplasia in women and non-spayed female dogs and is one of the leading causes of death in both species. Canines develop spontaneous mammary tumors that share a significant number of biological, clinical, pathological and molecular characteristics with human breast cancers. This review provides a detailed description of the histological, molecular and clinical aspects of mammary cancer in canines; it discusses risk factors and currently available diagnostic and treatment options, as well as remaining challenges and unanswered questions. The incidence of mammary tumors is highly variable and is impacted by biological, pathological, cultural and socioeconomic factors, including hormonal status, breed, advanced age, obesity and diet. Diagnosis is mainly based on histopathology, although several efforts have been made to establish a molecular classification of canine mammary tumors to widen the spectrum of treatment options, which today rely heavily on surgical removal of tumors. Lastly, standardization of clinical study protocols, development of canine-specific biological tools, establishment of adequate dog-specific disease biomarkers and identification of targets for the development of new therapies that could improve survival and have less adverse effects than chemotherapy are among the remaining challenges.

Propolis: Antineoplastic Activity, Constituents, and Mechanisms of Action.

Propolis is a beehive product with great pharmacological potential, including antineoplastic activity. OBJECTIVES: The aim of this study is to provide an actual understanding of the existent scientific information regarding the antiproliferative effect of propolis, proposed mechanisms of action, and challenges to meet. METHODS: An assessment of the scientific literature was attained using the PubMed and SciFinder platforms. Research papers, clinical trials, and reviews published between the years 2000 - 2021, were considered. The words "anticancer", "antitumor", "antiproliferative" and "propolis" were used in the search criteria. CONCLUSION: A summary of several antiproliferative activities of different types of propolis is exposed. The potential health benefits of propolis are discussed. The variable plant origin of propolis partially accounts for its anti-cancer activities. Even when some mechanisms of action of propolis have been proposed, much of the genesis of how this effect is produced is yet to be answered, including several molecular mechanisms in different biological systems.

The clinical impact of estrogen loss on cardiovascular disease in menopausal females.

According to the CDC (2017), more women than men have died from heart disease over the last 20-25 years. On the contrary, premenopausal women are protected against heart and cardiovascular disease (CVD) compared to men. Following menopause, there is sharp rise in CVD mortality and morbidity in women compared to men indicating that women lose protection against CVD during menopause. This loss of CVD protection in women drives the CDC statistics. Life expectance of women has now reached 82 (almost 35 years longer than at the turn of the 20th century). Yet, women typically undergo menopause at 50-60 years of age, which means that women spend over 40% of their life in menopause. Therefore, menopausal women, and associated CVD risk, must be considered as distinct from an aging or senescent woman. Despite longstanding knowledge that premenopausal women are protected from CVD, our fundamental understanding regarding the shift in CVD risk with menopause remains inadequate and impedes our ability to develop sex-specific therapeutic strategies to combat menopausal susceptibility to CVD. This review provides a critical overview of clinical trials attempting to address CVD susceptibility postmenopausal using hormone replacement therapy. Next, we outline key deficiencies in pre-clinical menopause models and introduce an alternative to overcome these deficiencies. Finally, we discuss a novel connection between AMPK and estrogen-dependent pathways that may serve as a potential solution to increased CVD susceptibility in menopausal women.

The complex nature of oestrogen signalling in breast cancer: enemy or ally?

The pleiotropic nature of oestradiol, the main oestrogen found in women, has been well described in the literature. Oestradiol is positioned to play a unique role since it can respond to environmental, genetic and non-genetic cues to affect genetic expression and cellular signalling. In breast cancer, oestradiol signalling has a dual effect, promoting or inhibiting cancer growth. The potential impact of oestradiol on tumorigenesis depends on the molecular and cellular characteristics of the breast cancer cell. In this review, we provide a broad survey discussing the cellular and molecular consequences of oestrogen signalling in breast cancer. First, we review the structure of the classical oestrogen receptors and resultant transcriptional (genomic) and non-transcriptional (non-genomic) signalling. We then discuss the nature of oestradiol signalling in breast cancer including the specific receptors that initiate these signalling cascades as well as potential outcomes, such as cancer growth, proliferation and angiogenesis. Finally, we examine cellular and molecular mechanisms underlying the dimorphic effect of oestrogen signalling in breast cancer.

AMP-Activated Protein Kinase Signalling in Cancer and Cardiac Hypertrophy.

The AMP-protein kinase (AMPK) pathway is very versatile as it regulates cellular energetic homeostasis in many different tissue types. An appreciation for the importance of AMPK signalling and regulation in cardiovascular and tumor biology is increasing. Recently, a link has been established between anti-cancer therapy and susceptibility to cardiac disease. It has been shown that some anti-cancer drugs lead to an increased risk of cardiac disease, underlined by de-regulation of AMPK signalling. This review explores the AMPK signalling axis in both cardiac and tumor metabolism. We then examine off-target AMPK inhibition by cancer drugs and how this may translate into increased risk of cardiovascular disease. Finally, we discuss the implication of deregulated AMPK signalling during different stages of cardiac hypertrophy. Better understanding of the molecular pathways behind pathological processes will lead to the development of more effective therapeutics for cancer and cardiovascular diseases.

Oestrogen receptors interact with the α-catalytic subunit of AMP-activated protein kinase.

Normal and pathological stressors engage the AMP-activated protein kinase (AMPK) signalling axis to protect the cell from energetic pressures. Sex steroid hormones also play a critical role in energy metabolism and significantly modify pathological progression of cardiac disease, diabetes/obesity and cancer. AMPK is targeted by 17ß-oestradiol (E2), the main circulating oestrogen, but the mechanism by which E2 activates AMPK is currently unknown. Using an oestrogen receptor α/ß (ERα/ß) positive (T47D) breast cancer cell line, we validated E2-dependent activation of AMPK that was mediated through ERα (not ERß) by using three experimental strategies. A series of co-immunoprecipitation experiments showed that both ERs associated with AMPK in cancer and striated (skeletal and cardiac) muscle cells. We further demonstrated direct binding of ERs to the α-catalytic subunit of AMPK within the ßγ-subunit-binding domain. Finally, both ERs interacted with the upstream liver kinase B 1 (LKB1) kinase complex, which is required for E2-dependent activation of AMPK. We conclude that E2 activates AMPK through ERα by direct interaction with the ßγ-binding domain of AMPKα.