Search

Neuroglobin (Ngb), so named after its initial discovery in brain neurones, has received great attention as a result of its neuroprotective effects both in vitro and in vivo. Recently, we demonstrated that, in neurones, Ngb is a 17β-oestradiol (E2) inducible protein that is pivotal for hormone-induced anti-apoptotic effects against H2O2 toxicity. The involvement of Ngb in other brain cell populations, as well as in other neuroprotective effects of E2, is completely unknown at present. We demonstrate Ngb immunoreactivity in reactive astrocytes located in the proximity of a penetrating cortical injury in vivo and the involvement of Ngb in the E2-mediated anti-inflammatory effect in primary cortical astrocytes. Upon binding to oestrogen receptor ( ER)β, E2 enhances Ngb levels in a dose-dependent manner. Although with a lesser degree than E2, the pro-inflammatory stimulation with lipopolysaccharide ( LPS) also induces the increase of Ngb protein levels via nuclear factor-( NF)κB signal(s). Moreover, a negative cross-talk between ER subtypes and NFκB signal(s) has been demonstrated. In particular, ERα-activated signals prevent the NFκB-mediated Ngb increase, whereas LPS impairs the ERβ-induced up-regulation of Ngb. Therefore, the co-expression of both ERα and ERβ is pivotal for mediating E2-induced Ngb expression in the presence of NFκB-activated signals. Interestingly, Ngb silencing prevents the effect of E2 on the expression of inflammatory markers (i.e. interleukin 6 and interferon γ-inducible protein 10). Ngb can be regarded as a key mediator of the different protective effects of E2 in the brain, including protection against oxidative stress and the control of inflammation, both of which are at the root of several neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Aberrant response to physiological cell stress is part of the mechanisms underlying the development of diverse human diseases, including neuropathologies. Neuroglobin (NGB), an intracellular monomeric globin, has gained attention for its role in endogenous stress response pathways in neuroprotection. To date, evidence supports the concept of NGB as an inducible protein, triggered by physiological and pathological stimuli via transcriptional and/or post-transcriptional mechanisms, offering cell-autonomous neuroprotective functions under various cellular stresses. Notably, recent evidence suggests the extracellular occurrence of NGB. We aimed to explore whether NGB redistribution in the cell microenvironment may serve in transmitting resilience capability in a model with neuronal characteristics. Results obtained in SH-SY5Y demonstrated that intracellular NGB upregulation is associated with the promotion of the extracellular release of the globin. Additionally, cell secretome from NGB-overexpressing cells, characterized by globin accumulation, exhibits protective effects against oxidative stress and mitochondrial toxicity, as evidenced by reduced apoptosis and preserved mitochondrial structure. These findings shed light on the potential significance of extracellular NGB as part of a common cell response to physiological and stress conditions and as a factor promoting cell resilience. Furthermore, the potential for neuroprotection of extracellular NGB paves the way for future therapeutic opportunities., Competing Interests: The authors declare no conflict of interest.

Extensive research has focused on cellular cholesterol and its regulation, primarily due to its crucial physiological roles and its association with numerous diseases resulting from dysregulated homeostasis. Consequently, investigating cholesterol metabolism and the network of regulating proteins remains an ongoing challenge for biomedical research seeking new molecular targets to manage aberrant cholesterol levels in pathologic conditions. There is evidence that Sigma-2/TMEM97 receptor regulates cholesterol metabolism. However, the mechanisms remain incompletely understood to date. Therefore, this study aimed to employ a pharmacological approach based on selective Sigma-2/TMEM97 agonists, rimcazole and siramesine, to uncover the contribution of this receptor to cholesterol homeostasis. Our results indicate that Sigma-2/TMEM97 activation modulates cholesterol uptake by altering key proteins involved in, leading to free cholesterol and neutral lipids accumulation. This sheds light on potential mechanisms implied, contributing a new piece to the intricate puzzle of cholesterol metabolism homeostasis., (© 2024 Wiley Periodicals LLC.)

17β-estradiol is a hormone that plays a vital role in human physiology. It acts through estrogen receptors, specifically estrogen receptor α and estrogen receptor β, and its action is determined by the pulsatile secretion in the bloodstream. 17β-estradiol affects cell proliferation, and dysregulation of 17β-estradiol:estrogen receptor α signaling contribute to the development of breast cancer. Previous research on 17β-estradiol:estrogen receptor α signaling has primarily used two-dimensional cell cultures, which do not fully recapitulate the complexity of tumors that exist in a three-dimensional environment and do not consider the pulsatile nature of this hormone. To address these limitations, we studied 17β-estradiol:estrogen receptor α signaling in cell proliferation using both two-dimensional and three-dimensional breast cancer cell culture models under continuous and pulsatile stimulation conditions. Results revealed that breast cancer cells grown in an alginate-based three-dimensional matrix exhibited similar responsiveness to 17β-estradiol compared with cells grown in conventional two-dimensional culture plates. 17β-estradiol induced the expression of proteins containing estrogen response element in the three-dimensional model. The efficacy of the antiestrogen drugs fulvestrant (ICI182,280) and 4OH-tamoxifen was also demonstrated in the three-dimensional model. These results support the use of the three-dimensional culture model for studying tumor response to drugs and provide a more realistic microenvironment for such studies. Furthermore, the study revealed that a brief 5-min exposure to 17β-estradiol triggered a physiological response comparable with continuous hormone exposure, suggesting that the cellular response to 17β-estradiol is more important than the continuous presence of the hormone. In conclusion, the study demonstrates that the alginate-based three-dimensional culture model is suitable for studying the effects of 17β-estradiol and antiestrogen drugs on breast cancer cells, offering a more realistic representation of tumor-microenvironment interactions. The results also highlight the importance of considering the physiological importance of the temporal dynamics in studying 17β-estradiol signaling and cellular responses., (© 2024 Wiley Periodicals LLC.)

A promising therapeutic strategy to delay and/or prevent the onset of neurodegenerative diseases (NDs) could be to restore neuroprotective pathways physiologically triggered by neurons against stress injury. Recently, we identified the accumulation of neuroglobin (NGB) in neuronal cells, induced by the 17β-estradiol (E2)/estrogen receptor β (ERβ) axis, as a protective response that increases mitochondria functionality and prevents the activation of apoptosis, increasing neuron resilience against oxidative stress. Here, we would verify if resveratrol (Res), an ERβ ligand, could reactivate NGB accumulation and its protective effects against oxidative stress in neuronal-derived cells (i.e., SH-SY5Y cells). Our results demonstrate that ERβ/NGB is a novel pathway triggered by low Res concentrations that lead to rapid and persistent NGB accumulation in the cytosol and in mitochondria, where the protein contributes to reducing the apoptotic death induced by hydrogen peroxide (H 2 O 2 ). Intriguingly, Res conjugation with gold nanoparticles increases the stilbene efficacy in enhancing neuron resilience against oxidative stress. As a whole, ERβ/NGB axis regulation is a novel mechanism triggered by low concentration of Res to regulate, specifically, the neuronal cell resilience against oxidative stress reducing the triggering of the apoptotic cascade.

Breast cancer is the first leading tumor in women in terms of incidence worldwide. Seventy percent of cases are estrogen receptor (ER) α-positive. In these malignancies, 17β-estradiol (E2) via ERα increases the levels of neuroglobin (NGB), a compensatory protein that protects cancer cells from stress-induced apoptosis, including chemotherapeutic drug treatment. Our previous data indicate that resveratrol (RSV), a plant-derived polyphenol, prevents E2/ERα-induced NGB accumulation in this cellular context, making E2-dependent breast cancer cells more prone to apoptosis. Unfortunately, RSV is readily metabolized, thus preventing its effectiveness. Here, four different RSV analogs have been developed, and their effect on the ERα/NGB pathway has been compared with RSV conjugated with highly hydrophilic gold nanoparticles as prodrug to evaluate if RSV derivatives maintain the breast cancer cells' susceptibility to the chemotherapeutic drug paclitaxel as the original compound. Results demonstrate that RSV conjugation with gold nanoparticles increases RSV efficacy, with respect to RSV analogues, reducing NGB levels and enhancing the pro-apoptotic action of paclitaxel, even preventing the anti-apoptotic action exerted by E2 treatment on these cells. Overall, RSV conjugation with gold nanoparticles makes this complex a promising agent for medical application in breast cancer treatment.

Naringenin (Nar) is one of major citrus flavonoids predominantly found in grapefruit and orange. In vivo studies have demonstrated Nar potential as a normolipidemic agent capable to reduce circulating cholesterol in hypercholesterolemic rabbits, rats, and patients, suggesting a new role for this molecule in cardiovascular disease prevention. Although Nar cholesterol-lowering effects are known, the underlying mechanisms have not yet been elucidated. Interestingly, Nar binds to the estrogen receptors (ERs), modulating both transcriptional and membrane-initiating signals. Although estrogen and ERs are deeply involved in lipid metabolism, no data are available regarding a putative role of these nuclear receptors as mediators of the hypocholesterolemic effect exerted by Nar. Thus, the aim of this work was to study the involvement of ERs in Nar-induced modulation of cholesterol metabolism. Results obtained in HepG2 cell line demonstrate that Nar can modulate the molecular network of cholesterol homeostasis. However, these effects were only partially dependent on the activity of estrogen receptor α. As a whole, our data highlight new molecular mechanisms by which Nar influences cholesterol metabolism, opening a new scenery about dietary impact on human health.

Retinal neurodegeneration affects an increasing number of people worldwide causing vision impairments and blindness, reducing quality of life, and generating a great economic challenge. Due to the complexity of the tissue, and the diversity of retinal neurodegenerative diseases in terms of etiology and clinical presentation, so far, there are no cures and only a few early pathological markers have been identified. Increasing efforts have been made to identify and potentiate endogenous protective mechanisms or to abolish detrimental stress responses to preserve retinal structure and function. The discovering of the intracellular monomeric globin neuroglobin (NGB), found at high concentration in the retina, has opened new possibilities for the treatment of retinal disease. Indeed, the NGB capability to reversibly bind oxygen and its neuroprotective function against several types of insults including oxidative stress, ischemia, and neurodegenerative conditions have raised the interest in the possible role of the globin as oxygen supplier in the retina and as a target for retinal neurodegeneration. Here, we provide the undercurrent knowledge on NGB distribution in retinal layers and the evidence about the connection between NGB level modulation and the functional outcome in terms of retinal neuroprotection to provide a novel therapeutic/preventive target for visual pathway degenerative disease.

Phthalates comprise a group of synthetic chemicals present in the environment because of their wide use as plasticizers and as additives in products for personal care. Among others, diethyl phthalate (DEP) is largely used in products for infants, children, and adults, in which its exposure has been correlated with an increased risk of breast cancer. The adverse health outcomes deriving from phthalate exposure have been associated with their activity as endocrine disruptors (EDCs) of the steroid and thyroid hormone signaling by affecting developmental and reproductive health, and even carcinogenicity. However, the estrogen disruptor activities of DEP are still controversial, and the mechanism at the root of the estrogenic-disrupting action of DEP remains to be clarified. Here, we evaluated the DEP mechanism of action on the activation status of estrogen receptor α (ERα) by analyzing the receptor's phosphorylation as well as both nuclear and extra-nuclear pathways triggered by the receptor to modulate the proliferation of breast cancer cells. Although DEP does not bind to ERα, our results suggest that this phthalate ester exerts multiple parallel interactions with ERα signaling and emphasize the importance to determine an appropriate battery of in vitro methods that will include specific molecular mechanisms involved in the endocrine disruption.

The expression of the α-subtype of Estrogen Receptor (ERα) characterizes most breast cancers (more than 75%), for which endocrine therapy is the mainstay for their treatment. However, a high percentage of ERα+ breast cancers are de novo or acquired resistance to endocrine therapy, and the definition of new targets for improving therapeutic interventions and the prediction of treatment response is demanding. Our previous data identified the ERα/AKT/neuroglobin (NGB) pathway as a common pro-survival process activated in different ERα breast cancer cell lines. However, no in vivo association between the globin and the malignity of breast cancer has yet been done. Here, we evaluated the levels and localization of NGB in ERα+ breast ductal carcinoma tissue of different grades derived from pre-and post-menopausal patients. The results indicate a strong association between NGB accumulation, ERα, AKT activation, and the G3 grade, while no association with the menopausal state has been evidenced. Analyses of the data set (e.g., GOBO) strengthen the idea that NGB accumulation could be linked to tumor cell aggressiveness (high grade) and resistance to treatment. These data support the view that NGB accumulation, mainly related to ER expression and tumor grade, represents a compensatory process, which allows cancer cells to survive in an unfavorable environment.

Estradiol (E 2 ) and selective estrogen receptor modulators (SERMs) have broad-ranging cellular effects that include mitochondrial respiration and reactive oxygen species (ROS) metabolism. Many of these effects have been studied using cell culture models. Recent advances have revealed the extent to which cellular metabolism is affected by the culture environment. Cell culture media with metabolite composition similar to blood plasma [e.g., Plasmax, Human Plasma-Like Medium (HPLM)] alter cellular behaviors including responses to drugs. Similar effects have been observed with respect to O 2 levels in cell culture. Given these observations, we investigated whether the effects of E 2 and SERMs are also influenced by media composition and O 2 level during cell culture experiments. We analyzed mitochondrial network characteristics, cellular oxidative metabolism, and H 2 O 2 production in C2C12 myoblasts growing in physiological (5%) or standard cell culture (18%)O 2 and in physiological (Plasmax) or standard cell culture [Dulbecco's modified Eagle's medium (DMEM)] media. Although E 2 significantly lowered H 2 O 2 production from cells growing in 18% O 2 /DMEM (standard cell culture), it had no effect on cells growing in Plasmax. Moreover, culture conditions significantly altered the effects of E 2 and SERMs on mitochondrial abundance and network characteristics. These results indicate that the effects of E 2 and SERMs on various aspects of cell physiology strongly depends on growth conditions, which in turn emphasizes the need to consider this carefully in cell culture experiments.

Neuroglobin (NGB) is a myoglobin-like monomeric globin that is involved in several processes, displaying a pivotal redox-dependent protective role in neuronal and extra-neuronal cells. NGB remarkably exerts its function upon upregulation by NGB inducers, such as 17β-estradiol (E2) and H 2 O 2 . However, the molecular bases of NGB's functions remain undefined, mainly in non-neuronal cancer cells. Human MCF-7 breast cancer cells with a knocked-out (KO) NGB gene obtained using CRISPR/Cas9 technology were analyzed using shotgun label-free quantitative proteomics in comparison with control cells. The differential proteomics experiments were also performed after treatment with E2, H 2 O 2 , and E2 + H 2 O 2 . All the runs acquired using liquid chromatography-tandem mass spectrometry were elaborated within the same MaxQuant analysis, leading to the quantification of 1872 proteins in the global proteomic dataset. Then, a differentially regulated protein dataset was obtained for each specific treatment. After the proteomic study, multiple bioinformatics analyses were performed to highlight unbalanced pathways and processes. Here, we report the proteomic and bioinformatic investigations concerning the effects on cellular processes of NGB deficiency and cell treatments. Globally, the main processes that were affected were related to the response to stress, cytoskeleton dynamics, apoptosis, and mitochondria-driven pathways.

Dysfunctional mitochondria have severe consequences on cell functions including Reactive Oxygen Specie (ROS) generation, alteration of mitochondrial signaling, Ca 2+ buffering, and activation of apoptotic pathway. These dysfunctions are closely linked with degenerative diseases including neurodegeneration. The discovery of neuroglobin (NGB) as an endogenous neuroprotective protein, which effects seem to depend on its mitochondrial localization, could drive new therapeutic strategies against aged-related neurodegenerative diseases. Indeed, high levels of NGB are active against several brain injuries, including neurodegeneration, hypoxia, ischemia, toxicity, and nutrient deprivation opening a new scenario in the comprehension of the relationship between neural pathologies and mitochondrial homeostasis. In this review, we provide the current understanding of the role of mitochondria in neurodegeneration and discuss structural and functional connection between NGB and mitochondria with the purpose of defining a novel mitochondrial-based neuroprotective mechanism(s)., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Estrogen receptor α expressing breast cancers (BC) are classically treated with endocrine therapy. Prolonged endocrine therapy often results in a metastatic disease (MBC), for which a standardized effective therapy is still lacking. Thus, new drugs are required for primary and metastatic BC treatment. Here, we report that the Food and Drug Administration (FDA)-approved drugs, ouabain and digoxin, induce ERα degradation and prevent proliferation in cells modeling primary and metastatic BC. Ouabain and digoxin activate the cellular proteasome, instigating ERα degradation, which causes the inhibition of 17β-estradiol signaling, induces the cell cycle blockade in the G2 phase, and triggers apoptosis. Remarkably, these effects are independent of the inhibition of the Na/K pump. The antiproliferative effects of ouabain and digoxin occur also in diverse cancer models (i.e., tumor spheroids and xenografts). Additionally, gene profiling analysis reveals that these drugs downregulate the expression of genes related to endocrine therapy resistance. Therefore, ouabain and digoxin behave as 'anti-estrogen'-like drugs, and are appealing candidates for the treatment of primary and metastatic BCs.

Components of tumor microenvironment, including tumor and/or stromal cells-derived factors, exert a critical role in breast cancer (BC) progression. Here we evaluated the possible role of neuroglobin (NGB), a monomeric globin that acts as a compensatory protein against oxidative and apoptotic processes, as part of BC microenvironment. The extracellular NGB levels were evaluated by immunofluorescence of BC tissue sections and by Western blot of the culture media of BC cell lines. Moreover, reactive oxygen species (ROS) generation, cell apoptosis, and cell migration were evaluated in different BC cells and non-tumorigenic epithelial mammary cells treated with BC cells (i.e., Michigan Cancer Foundation-7, MCF-7) conditioned culture media and extracellular NGB. Results demonstrate that NGB is a component of BC microenvironment. NGB is released in tumor microenvironment by BC cells only under oxidative stress conditions where it can act as autocrine/paracrine factor able to communicate cell resilience against oxidative stress and chemotherapeutic treatment.

Aims: Nuclear factor (erythroid-derived 2)-like-2 factor (NRF-2) is a transcription factor well known to provide an advantage for cancer growth and survival regulating the cellular redox pathway. In breast cancer cells, we recently identified the monomeric heme-globin neuroglobin (NGB) as part of a new mechanism induced by the steroid hormone 17β-estradiol (E2) against oxidative stress. While there is mounting evidence suggesting a critical role of NGB as a sensor of oxidative stress, scarce information is available about its involvement in NRF-2 pathway activation in breast cancer cells. Results: Although NGB is not involved in the rapid E2-induced NRF-2 stability, E2 loses the capacity to regulate the expression of NRF-2-dependent genes in NGB-depleted MCF-7 cells. These data strongly sustain a role of NGB as a compensatory protein in the E2-activated intracellular pathway devoted to the increase of cancer cells tolerance to reactive oxygen species (ROS) generation in stressing conditions acting as key regulator of NRF-2 pathway activity in a time-dependent manner. Innovation: In this study, we identified a new role of NGB in the cell response to oxidative stress. Conclusion: Altogether, reported results open new insights on the NGB effect in regulating intracellular pathways related to cell adaptive response to stress and, as consequence, to cell survival, beyond its direct effect as ROS scavenger, opening new prospective in cancer therapeutic intervention.

Reactive oxygen species (ROS) result from intracellular aerobic metabolism and/or extracellular stimuli. Although endogenous antioxidant systems exquisitely balance ROS production, an excess of ROS production, commonly found in diverse human degenerative pathologies including cancer, gives rise to the oxidative stress. Increased oxidative stress in cancer is related to the sustained proliferation and metabolism of cancer cells. However, cancer cells show an intrinsic higher antioxidant capacity with respect to the normal counterpart as well as an ability to cope with oxidative stress-induced cell death by establishing mechanisms of adaptation, which define a selective advantage against the adverse oxidative stress environment. The identification of survival factors and adaptive pathways, set up by cancer cells against oxidative stress, provides multiple targets for the therapeutic intervention against cancer. Neuroglobin (NGB), a globin primarily described in neurons as an oxidative stress sensor and cytoprotective factor against redox imbalance, has been recently recognized as a novel tumor-associated protein. In this review, the involvement of NGB in the cancer cell adaptation and resistance to oxidative stress will be discussed highlighting the globin role in the regulation of both the stress-induced apoptotic pathway and antioxidant systems activated by cancer cells.

Neuroglobin (NGB), an antiapoptotic protein upregulated by 17β-estradiol (E2), is part of E2/estrogen receptor α (ERα) pathway pointed to preserve cancer cell survival in presence of microenvironmental stressors including chemotherapeutic drugs. Here, the possibility that resveratrol (Res), an anticancer plant polyphenol, could increase the susceptibility of breast cancer cells to paclitaxel (Pacl) by affecting E2/ERα/NGB pathway has been evaluated. In MCF-7 and T47D (ERα-positive), but not in MDA-MB 231 (ERα-negative) nor in SK-N-BE (ERα and ERβ positive), Res decreases NGB levels interfering with E2/ERα-induced NGB upregulation and with E2-induced ERα and protein kinase B phosphorylation. Although Res treatment does not reduce cell viability by itself, this compound potentiates Pacl proapoptotic effects. Notably, the increase of NGB levels by NGB expression vector transfection prevents Pacl or Res/Pacl effects. Taken together, these findings indicate a new Res-based mechanism that acts on tumor cells impairing the E2/ERα/NGB signaling pathways and increasing cancer cell susceptibility to chemotherapeutic agent., (© 2018 Wiley Periodicals, Inc.)

Neuroglobin (NGB) is a relatively recent discovered monomeric heme-protein, which behave in neurons as a sensor of injuring stimuli including oxidative stress, hypoxia, and neurotoxicity. In addition, the anti-apoptotic activity of overexpressed NGB has been reported both in neurons and in cancer cell lines. We recently demonstrated that, NGB functions as a compensatory protein of the steroid hormone 17β-estradiol (E2) protecting cancer cells against the apoptotic death induced by oxidative stress. However, the E2-induced signaling pathways at the root of NGB over-expression and mitochondrial re-localization in breast cancer cells is still elusive. By using a kinase screening library, here, we report that: i) There is a strong positive correlation between NGB and ERα expression and activity in breast cancer cells; ii) The E2-activated phosphatidyl-inositol 3 kinase (PI3K)/protein kinase B (AKT) and protein kinase C (PKC) pathways are necessary to modulate the NGB protein levels; iii) The E2-induced persistent activation of AKT drive NGB to mitochondria; iv) Reactive oxygen species (ROS)-inducing compounds activating rapidly and transiently AKT does not affect the NGB mitochondrial level; and v) High level of NGB into mitochondria are necessary for the pro-survival and anti-apoptotic effect of this globin in cancer cells. As a whole, these results underline the E2 triggered pathways in E2-responsive breast cancer cells that involve NGB as a compensatory protein devoted to cancer cell survival., (© 2017 Wiley Periodicals, Inc.)

Environmental factors or adverse growth conditions that may reduce cell function or viability are considered stress. The cell ability to sense and respond to environmental stresses determine its function and survival destiny. We recently defined Neuroglobin (NGB), a heme-protein, as a compensatory protein in the 17β-Estradiol (E2) anti-apoptotic activity and as a sensor of oxidative stress in both neurons and breast cancer cells. Here, the possibility that NGB levels could represent a pivotal regulator of integrated response of cancer cells to stress has been evaluated. Data obtained in neuroblastoma and in breast cancer cell lines evidence that nutrient deprivation significantly up-regulated NGB levels at different time points. However, the analysis of autophagy activation led to exclude any possible role of stress- or E2-induced NGB in the upstream regulation of general autophagy. However, the over-expression of Flag-NGB in ERα stable transfected HEK-293 cells completely affects nutrient deprivation-induced decrease in cell number. In addition, reported results indicate that modulation of the anti-apoptotic Bcl-2 level may play a key role in the protective NGB function against energetic stress. Overall, these data define a role of NGB as compensatory protein in the cell machinery activated in response to stress and as general stress adaptation marker of cancer cells susceptible to oxidative stress, oxygen and, as demonstrated here for the first time, even to nutrient willingness. Despite the lacking of any direct NGB role on autophagic flux activated by energetic stress, NGB upregulation appears functional in delaying stress-related cell death allowing an appropriate cell response and adaptation to the changing extracellular conditions.

The hormone 17β-estradiol (E2) contributes to body homeostasis maintenance by regulating many different physiological functions in both male and female organs. E2 actions in reproductive and non-reproductive tissues rely on a complex net of nuclear and extra-nuclear signal transduction pathways triggered by at least two estrogen receptor subtypes (ERα and ERβ). Consequently, the de-regulation of E2:ER signaling contributes to the pathogenesis of many diseases including cancer. Among other factors, the ERα/ERβ ratio is considered one of the pivotal mechanisms at the root of E2 action in cancer progression. Remarkably, several natural or synthetic exogenous chemicals, collectively called xenoestrogens, bind to ERs and interfere with their signals and intracellular functions. In this review, the molecular mechanism(s) through which xenoestrogens influence ERα and ERβ intracellular concentrations and the consequences of this influence on E2-related cancer will be discussed., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

In the year 2000, the third member of the globin family was discovered in human and mouse brain and named neuroglobin (Ngb). Neuroglobin overexpression significantly protects both heart and brain from hypoxic/ischemic and oxidative stress-related insults, whereas decreased Ngb levels lead to an exacerbation of tissue injuries. Moreover, Ngb overexpression protects neurons from mitochondrial dysfunctions and neurodegenerative disorders such as Alzheimer disease; however, it facilitates the survival of cancer cells. Neuroglobin, representing a switch point for cell death and survival, has been reported to recognize a number of proteins involved in several metabolic pathways including ionic homeostasis maintenance, energy metabolism, mitochondrial function, and cell signaling. Here, the recognition properties of Ngb are reviewed to highlight its roles in health and disease., (Copyright © 2017 John Wiley & Sons, Ltd.)

Among several mechanisms underlying the well-known trophic and protective effects of 17β-estradiol (E2) in the brain, we recently reported that E2 induces the up-regulation of two anti-apoptotic and neuroprotectant proteins: huntingtin (HTT) and neuroglobin (NGB). Here, we investigate the role of this up-regulation. The obtained results indicate that E2 promotes NGB-HTT association, induces the localization of the complex at the mitochondria, and protects SK-N-BE neuroblastoma cells and murine striatal cells, which express wild-type HTT (i.e., polyQ 7 ), against H 2 O 2 -induced apoptosis. All E2 effects were completely abolished in HTT-knocked out SK-N-BE cells and in striatal neurons expressing the mutated form of HTT (mHTT; i.e., polyQ 111 ) typical of Huntington's disease (HD). As a whole, these data provide a new function of wild-type HTT which drives E2-induced NGB in mitochondria modulating NGB anti-apoptotic activity. This new function is lost by HTT polyQ pathological expansion. These data evidence the existence of a novel E2/HTT/NGB neuroprotective axis that may play a relevant role in the development of HD therapeutics.

Androgens, the main male sex steroids, are the critical factors responsible for the development of the male phenotype during embryogenesis and for the achievement of sexual maturation and puberty. In adulthood, androgens remain essential for the maintenance of male reproductive function and behavior. Androgens, acting through the androgen receptor (AR), regulate male sexual differentiation during development, sperm production beginning from puberty, and maintenance of prostate homeostasis. Several substances present in the environment, now classified as endocrine disruptors (EDCs), strongly interfere with androgen actions in reproductive and non-reproductive tissues. EDCs are a heterogeneous group of xenobiotics which include synthetic chemicals used as industrial solvents/lubricants, plasticizers, additives, agrochemicals, pharmaceutical agents, and polyphenols of plant origin. These compounds are even present in the food as components (polyphenols) or food/water contaminants (pesticides, plasticizers used as food packaging) rendering the diet as the main route of exposure to EDCs for humans. Although huge amount of literature reports the (anti)estrogenic effects of different EDCs, relatively scarce information is available on the (anti)androgenic effects of EDCs. Here, the effects and mechanism of action of phytochemicals and pesticides and plasticizers as possible modulators of AR activities will be reviewed taking into account that insight derived from principles of endocrinology are required to estimate EDC consequences on endocrine deregulation and disease.

In 2000, the third member of the globin family was discovered in human and mouse brain and named neuroglobin (Ngb). Ngb is a monomeric 3/3 globin structurally similar to myoglobin and to the α- and β-chains of hemoglobin, however it displays a bis-histidyl six-coordinate heme-Fe atom. Therefore, ligand binding to the Ngb metal center is limited from the dissociation of the distal His(E7)64-Fe bond. From its discovery, more than 500 papers on Ngb structure, expression, reactivity, and localization have been published to highlight its biochemical properties and its role(s) in health and disease. In vivo experiments have shown that increased levels of Ngb significantly protect both heart and brain from hypoxic/ischemic and oxidative stress-related insults, whereas decreased Ngb levels lead to an exacerbation of tissue injuries. Although some contradictory data emerged, human Ngb overexpression has been hypothesized to protect neurons from mitochondrial dysfunctions and neurodegenerative disorders such as Alzheimer's disease, and to play a shielding role in cancer cells. Recently, the recognition of Ngb interactors and inducers enlarges the functions of this stress-inducible globin, opening new therapeutic approaches to prevent neuronal cell death. Here, structural and functional aspects of human Ngb are examined critically to highlight its roles in health and disease., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Although paclitaxel (Taxol) is an active chemotherapeutic agent for the treatment of breast cancer, not all breast tumors are sensitive to this drug. In particular, there is a wide agreement on the low sensitivity of estrogen receptor (ER) α-positive breast cancer to paclitaxel treatment. However, the ERα-based insensitivity to paclitaxel is still elusive. Here, the effect of the E2/ERα-dependent upregulation of neuroglobin (NGB), an antiapoptotic globin, on the reduced sensitivity of breast cancer cells to paclitaxel-induced apoptosis has been evaluated in ERα-containing MCF-7 cells. The E2 pretreatment enhances the ERα activity and significantly impairs paclitaxel-induced apoptosis as evaluated by Annexin V assay and PARP-1 cleavage. NGB displays a pivotal role in the E2/ERα-induced antiapoptotic pathway to abrogate paclitaxel-induced cell death in stable NGB-silenced MCF-7 cell clones. Moreover, in the absence of the active ERα, paclitaxel significantly reduces the NGB cell content. In conclusion, these results highlight the involvement of ERα activation and of E2/ERα-dependent NGB upregulation in the insensitivity of MCF-7 to paclitaxel. These novel findings could have important implications in the development of targeted therapeutics for overcoming paclitaxel insensitivity in ERα-positive human breast cancer. © 2016 IUBMB Life, 68(8):645-651, 2016., (© 2016 International Union of Biochemistry and Molecular Biology.)

The over-expression of human neuroglobin (NGB), a heme-protein preferentially expressed in the brain, displays anti-apoptotic effects against hypoxic/ischemic and oxidative stresses enhancing neuron survival. As hypoxic and oxidative stress injury frequently occurs in fast proliferating neoplastic tissues, here, the effect of these stressors on the level, localization, and anti-apoptotic function of NGB in wild type and NGB-stable-silenced MCF-7 breast cancer cells has been assessed. The well-known endogenous NGB inducer 17β-estradiol (E2) has been used as positive control. The median pO2 present in tumor microenvironment of breast cancer patients (i.e., 2% O2) does not affect the NGB level in breast cancer cells, whereas hydrogen peroxide and lead(IV) acetate, which increase intracellular reactive oxygen species (ROS) level, enhance the NGB levels outside the mitochondria and still activate apoptosis. However, E2-induced NGB up-regulation in mitochondria completely reverse lead(IV) acetate-induced PARP cleavage. These results indicate that the NGB level could represent a marker of oxidative-stress in MCF-7 breast cancer cells; however, the NGB ability to respond to injuring stimuli by preventing apoptosis requires its re-allocation into the mitochondria. As a whole, present data might lead to a new direction in understanding NGB function in cancer opening new avenues for the therapeutic intervention.

17β-Estradiol (E2) exerts neurotrophic and neuroprotective functions in the brain. Here, E2-induced increased levels of huntingtin (HTT), a protein involved in several crucial neuronal functions is reported. E2 physiological concentrations up-regulate HTT in hippocampus and striatum of rats as well as in human neuroblastoma cells. This effect requires both nuclear and extra-nuclear estrogen receptor (ER)α activities. Intriguingly, HTT silencing completely prevents E2 protective effects against oxidative stress injury. In conclusion, these data indicate for the first time that HTT is an E2-inducible protein involved in the first steps of E2-induced signaling pathways committed to neuronal protection against oxidative stress., (Copyright © 2015. Published by Elsevier Ireland Ltd.)

Microperoxidase-11 (MP11) is an undecapeptide derived from horse heart cytochrome c (cyt c) and characterized by a covalently-linked solvent-exposed heme group. Here, kinetics of the NO2(-)-mediated nitrosylation of ferrous MP11 (MP11-Fe(II)) is reported. Data were obtained between pH6.4 and 8.2, at 20.0°C. The NO2(-)-mediated conversion of MP11-Fe(II) to MP11-Fe(II)-NO requires one proton; accordingly, values of the apparent second-order rate constant (kon) decrease by about two orders of magnitude from (2.9±0.3)×10(1)M(-1)s(-1) to (5.0±0.6)×10(-1)M(-1)s(-1) upon increasing pH from 6.4 to pH8.2. The slope of the linear fitting of Logkon versus pH is -1.00±0.06. Values of kon for the NO2(-)-mediated nitrosylation of MP11-Fe(II) are similar to those of penta-coordinated cardiolipin-bound horse heart cyt c, exceeding by about two orders of magnitude those of wild-type horse heart cyt c. Present results highlight the role of heme distal residues in modulating horse heart cyt c reactivity., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Besides other mechanism(s) 17β-estradiol (E2) facilitates neuronal survival by increasing, via estrogen receptor β (ERβ), the levels of neuroglobin (NGB) an anti-apoptotic protein. In contrast, E2 could exert protective effects in cancer cells by activating apoptosis when the ERβ level prevails on that of ERα as in colon cancer cell lines. These apparently contrasting results raise the possibility that E2-induced NGB up-regulation could regulate the ERβ activities shunning this receptor subtype to trigger an apoptotic cascade in neurons but not in non-neuronal cells. Here, human colorectal adenocarcinoma cell line (DLD-1) that only expresses ERβ and HeLa cells transiently transfected with ERβ encoding vector has been used to verify this hypothesis. In addition, neuroblastoma SK-N-BE cells were used as positive control. Surprisingly, E2 also induced NGB up-regulation, in a dose- and time-dependent manner, in DLD-1 cells. The ERβ-mediated activation of p38/MAPK was necessary for this E2 effect. E2 induced NGB re-allocation in mitochondria where, subsequently to an oxidative stress injury (i.e., 100μM H2O2), NGB interacted with cytochrome c preventing its release into the cytosol and the activation of an apoptotic cascade. As a whole, these results demonstrate that E2-induced NGB up-regulation could act as an oxidative stress sensor, which does not oppose to the pro-apoptotic E2 effect in ERβ-containing colon cancer cells unless a rise of oxidative stress occurs. These results support the concept that oxidative stress plays a critical role in E2-induced carcinogenesis and further open an important scenario to develop novel therapeutic strategies that target NGB against E2-related cancers., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Caspase-3 displays a pivotal role as an executioner of apoptosis, hydrolyzing several proteins including the nuclear enzyme poly(ADP-ribose)polymerase (PARP). Ac-Asp-Glu-Val-Asp-H (K i° = 2.3 × 10(-10) M at pH 7.5 and 25.0 °C), designed on the basis of the cleavage site of PARP, has been reported as a highly specific human caspase-3 inhibitor. Here, di- and tri-peptidyl aldehydes 11-13 and 27-29 have been synthesized to overcome the susceptibility to proteolysis, the intrinsic instability, and the scarce membrane permeability of the current inhibitors. Compounds 11-13, 27-29 inhibit in vitro human caspase-3 competitively, values of K i° ranging between 6.5 (±0.82) × 10(-9) M and 1.1 (±0.04) × 10(-7) M (at pH 7.4 and 25.0 °C). Moreover, the most effective caspase-3 inhibitor 11 impairs apoptosis in human DLD-1 colon adenocarcinoma cells. Furthermore, the binding mode of 11-13 and 27-29 to human caspase-3 has been investigated in silico. The comparative analysis of human caspase-3 inhibitors indicates that (1) aldehyde 11 is the minimal highly effective inhibitor, (2) the tLeu-Asp sequence is pivotal for satisfactory enzyme inhibition, and (3) the occurrence of the tLeu residue at the inhibitor P2 position is fundamental for enzyme/inhibitor recognition. Moreover, calculations suggest that the tLeu residue reduces the conformational flexibility of the inhibitor that binds to the enzyme with a lower energetic penalty.

The balance between neuronal apoptosis and survival sculpts the developing brain and has an important role in neurodegenerative diseases. Thus, the individuation of signals that could modulate the cell death machinery as well as enhance survival in neurons promises to provide multiple points of therapeutic intervention in neurodegenerative diseases. Neuroglobin (NGB), the first nerve globin identified in neuronal tissues of humans, seems to possess a protective role in the brain only after up-regulation. Here, the NGB physiological role in the control of neuronal survival is reviewed. In vitro studies suggested that cytosolic NGB could react very rapidly with cytochrome c released from mitochondria, thus interfering with the intrinsic pathway of apoptosis. Although very suggestive, these data do not explain either the role of NGB up-regulation in neuroprotection or the recently reported NGB localization into mitochondria. Recently, we identified the steroid hormone 17β-estradiol (E2) as an endogenous modulator of NGB levels in neuroblastoma SK-N-BE cell line. Upon E2 stimulation, NGB reallocates mainly into mitochondria where the association with the mitochondrial cytochrome c occurs. Remarkably, E2 treatment before an apoptotic stimulus strongly enhances the NGB:cytochrome c association reducing cytochrome c release into the cytosol. As a consequence, a decrease of caspase-3 activation and, in turn, of the apoptotic cascade activation take place. Besides E2, other compounds have been reported to up-regulate the NGB expression highlighting the possibility to develop NGB-mediated therapeutic strategies against stroke damage and neurodegenerative diseases. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Besides its crucial role in many physiological events, 17β-estradiol (E2) exerts protective effects in the central nervous system. The E2 effects are not restricted to the brain areas related with the control of reproductive function, but rather are widespread throughout the developing and the adult brain. E2 actions are mediated through estrogen receptors (i.e., ERα and ERβ) belonging to the nuclear receptor super-family. As members of the ligand-regulated transcription factor family, classically, the actions of ERs in the brain were thought to mediate only the E2 long-term transcriptional effects. However, a growing body of evidence highlighted rapid, membrane initiated E2 effects in the brain that are independent of ER transcriptional activities and are involved in E2-induced neuroprotection. The aim of this review is to focus on the rapid effects of E2 in the brain highlighting the specific role of the signaling pathway(s) of the ERβ subtype in the neuroprotective actions of E2.