Biological effects of bergamot and its potential therapeutic use as an anti-inflammatory, antioxidant, and anticancer agent.

Context: Bergamot, mainly produced in the Ionian coastal areas of Southern Italy (Calabria), has been used since 1700 for its balsamic and medicinal properties. Phytochemical profiling has confirmed that bergamot juices are rich in flavonoids, including flavone and flavanone glycosides which are responsible for its beneficial effects.Objective: Recently, it was shown that the combination of natural compounds with conventional treatments improves the efficacy of anticancer therapies. Natural compounds with anticancer properties attack cancerous cells without being toxic to healthy cells. Bergamot can induce cytotoxic and apoptotic effects and prevent cell proliferation in various cancer cells.Methods: In this review, the antiproliferative, pro-apoptotic, anti-inflammatory, and antioxidant effects of bergamot are described. Information was compiled from databases such as PubMed, Web of Science, and Google Scholar using the key words 'bergamot' accompanied by 'inflammation' and, 'cancer' for data published from 2015-2021.Results: In vitro and in vivo studies provided evidence that different forms of bergamot (extract, juice, essential oil, and polyphenolic fraction) can affect several mechanisms that lead to anti-proliferative and pro-apoptotic effects that decrease cell growth, as well as anti-inflammatory and antioxidant effects.Conclusions: Considering the effects of bergamot and its new formulations, we affirm the importance of its rational use in humans and illustrate how bergamot can be utilized in clinical applications. Numerous studies evaluated the effect of new bergamot formulations that can affect the absorption and, therefore, the final effects by altering the therapeutic profile of bergamot and enhancing the scientific knowledge of bergamot.

Exemplifying complexity of immune suppression by a "canonical" speech: A glimpse into TNFRSF-activated signaling pathways in Treg cells.

Regulatory T (Treg) cells are crucial mediators of immune tolerance suppressing self-reactive T cells and preventing autoimmune diseases. Besides activation of the T cell receptor (TCR), empowerment of Treg cell functions requires co-accessory signals, such as those released by the TNF receptor superfamily (TNFRSF) that, however, can also promote immunostimulatory responses when engaged by effector T cells. In this issue of European Journal of Immunology, Lubrano di Ricco et al. [Eur. J. Immunol. 2020. 50: 972-985] have taken a closer look at the important question of the functional meaning of TNFRSF-activated signaling pathways in Treg cells. They have demonstrated that costimulation by TNFR2, 4-1BB, GITR, DR3, but not OX40 in mouse Foxp3+ Treg cells activates the same and unique signaling pathway, i.e., canonical NF-κB, which in turn leads to Foxp3 gene upregulation, cell expansion in vitro and in vivo, and suppressive activity in an experimental model of colitis. Moreover, induction of markers of T helper 2 (Th2) and Th17 as well as of genes encoding proteins involved in noncanonical NF-κΒ was also observed. We here discussed how these findings further highlight the emerging concept of Treg cell plasticity in immune tolerance.

Role of Endogenous Glucocorticoids in Cancer in the Elderly.

Although not a disease itself, aging represents a risk factor for many aging-related illnesses, including cancer. Numerous causes underlie the increased incidence of malignancies in the elderly, for example, genomic instability and epigenetic alterations that occur at cellular level, which also involve the immune cells. The progressive decline of the immune system functions that occurs in aging defines immunosenescence, and includes both innate and adaptive immunity; the latter undergoes major alterations. Aging and chronic stress share the abnormal hypothalamic⁻pituitary⁻adrenal axis activation, where altered peripheral glucocorticoids (GC) levels and chronic stress have been associated with accelerated cellular aging, premature immunosenescence, and aging-related diseases. Consequently, changes in GC levels and sensitivity contribute to the signs of immunosenescence, namely fewer naïve T cells, poor immune response to new antigens, decreased cell-mediated immunity, and thymic involution. GC signaling alterations also involve epigenetic alterations in DNA methylation, with transcription modifications that may contribute to immunosenescence. Immune cell aging leads to decreased levels of immunosurveillance, thereby providing tumor cells one more route for immune system escape. Here, the contribution of GC secretion and signaling dysregulation to the increased incidence of tumorigenesis in the elderly is reviewed.

SUMO proteins: Guardians of immune system.

Small ubiquitin-like modifier (SUMO) proteins belong to the ubiquitin-like family and act to change the function of target proteins through post-translational modifications. Through their interactions with innate immune pathways, SUMOs promote an efficient immune response to pathogenic challenge avoiding, at the same time, an excess of immune response that could lead to the development of autoimmune diseases. This report discusses the general functions of SUMO proteins; highlights SUMO involvement in the innate immune response through their role in NF-κB and interferon pathways; the involvement of SUMO proteins in autoimmune diseases; and reviews bacterial, viral, and parasitic interactions with SUMO pathways. In conclusion, we speculate that targeting SUMOs could represent a new therapeutic strategy against infections and autoimmunity.

Targeting glucocorticoid side effects: selective glucocorticoid receptor modulator or glucocorticoid-induced leucine zipper? A perspective.

Glucocorticoids (GCs) are steroid hormones that are necessary for life and important in health and disease. They regulate crucial homeostatic functions, including metabolism, cell growth, and development. Although GCs are regulated by circadian rhythm, increased production is associated with stress. Synthetic GCs are a valuable resource for anti-inflammatory and immunosuppressive therapy. Natural and synthetic GCs transduce signals mainly through GC receptor (GR) activation. Extensive research has explored the downstream targets of the GR, and optimization of GC therapy has required collaborative efforts. One highly promising approach involves new dissociative GR modulators. Because transrepression and transactivation of GR genes induce beneficial and adverse effects, respectively, this approach favors transrepression. Another approach involves the use of GC-dependent genes to generate proteins to mediate therapeutic GC effects. In a third approach, drug discovery is used to identify agents that selectively target GR isoforms to obtain differential gene transcription and effects. In this review, we focus on mechanisms of GR function compatible with the use of dissociative drugs. We highlight GC-induced leucine zipper (GILZ), a gene cloned in our laboratory, as a mediator of GC anti-inflammatory and immunosuppressive effects, to outline our perspective on the future of GC therapy.

Pharmacological modulation of caspase-8 in thymus-related medical conditions.

The thymus is a lymphoid organ that governs the development of a diverse T-cell repertoire capable of defending against nonself-antigens and avoiding autoimmunity. However, the thymus can also succumb to different diseases. Hypertrophic diseases, such as thymomas, are typically associated with impairment of negative selection, which leads to autoimmune disease, or disruption of positive selection, which results in immunodeficiency. Hypotrophic diseases of the thymus can manifest during acute infections, cancer, allogeneic bone marrow transplantation, or with aging. This condition leads to decreased immune function and can be treated by either replacing lost thymic tissue or by preventing thymic tissue death. Studies have demonstrated the critical role of caspase-8 in regulating apoptosis in the thymus. In this review, we discuss how pharmacological activation and inhibition of caspase-8 can be used to treat hypertrophic and hypotrophic diseases of the thymus, respectively, to improve its function.

Reverse signaling through GITR ligand enables dexamethasone to activate IDO in allergy.

Glucocorticoid-induced tumor necrosis factor receptor (GITR) on T cells and its natural ligand, GITRL, on accessory cells contribute to the control of immune homeostasis. Here we show that reverse signaling through GITRL after engagement by soluble GITR initiates the immunoregulatory pathway of tryptophan catabolism in mouse plasmacytoid dendritic cells, by means of noncanonical NF-kappaB-dependent induction of indoleamine 2,3-dioxygenase (IDO). The synthetic glucocorticoid dexamethasone administered in vivo activated IDO through the symmetric induction of GITR in CD4(+) T cells and GITRL in plasmacytoid dendritic cells. The drug exerted IDO-dependent protection in a model of allergic airway inflammation. Modulation of tryptophan catabolism via the GITR-GITRL coreceptor system might represent an effective therapeutic target in immune regulation. Induction of IDO could be an important mechanism underlying the anti-inflammatory action of corticosteroids.

Cocaine Addiction Treatment and Home Remedies: Use of the Scopolamine Transdermal Patch.

Recently, there has been an enormous increase in the number of people seeking treatment for cocaine addiction. Fifteen male cocaine users aged 20-30 years who requested hair analysis from our forensic toxicology laboratory (Perugia, Italy) from March to June 2012, reported using scopolamine without medical supervision to reduce the anxiety associated with cocaine withdrawal. Self-reports were verified with the results obtained from the hair analysis. We discuss whether the use of scopolamine in cocaine abusers could be supported by a neurobiological and pharmacological point of view.

Mechanisms of the anti-inflammatory effects of glucocorticoids: genomic and nongenomic interference with MAPK signaling pathways.

Glucocorticoids (GCs) are steroid hormones produced by the adrenal gland and regulated by the hypothalamus-pituitary-adrenal axis. GCs mediate effects that mostly result in transcriptional regulation of glucocorticoid receptor target genes. Mitogen-activated protein kinases (MAPKs) comprise a family of signaling proteins that convert extracellular stimuli into the activation of intracellular transduction pathways via phosphorylation of a cascade of substrates. They modulate a variety of physiological cell processes, such as proliferation, apoptosis, and development. However, when MAPKs are improperly activated by proinflammatory and/or extracellular stress stimuli, they contribute to the regulation of proinflammatory transcription factors, thus perpetuating activation of the inflammatory cascade. One of the mechanisms by which GCs exert their anti-inflammatory effects is negative interference with MAPK signaling pathways. Several functional interactions between GCs and MAPK signaling have been discovered and studied. Some of these interactions involve the GC-mediated up-regulation of proteins that in turn interfere with the activation of MAPK, such as glucocorticoid-induced-leucine zipper, MAPK phosphatase-1, and annexin-1. Other mechanisms include activated GR directly interacting with components of the MAPK pathway and negatively regulating their activation. The multiple interactions between GCs and MAPK pathways and their potential biological relevance in mediating the anti-inflammatory effects of GCs are reviewed.

Cyclooxygenase-2 Upregulated by Temozolomide in Glioblastoma Cells Is Shuttled In Extracellular Vesicles Modifying Recipient Cell Phenotype.

Temozolomide (TMZ) resistance is frequent in patients with glioblastoma (GBM), a tumor characterized by a marked inflammatory microenvironment. Recently, we reported that cyclooxygenase-2 (COX-2) is upregulated in TMZ-resistant GBM cells treated with high TMZ concentrations. Moreover, COX-2 activity inhibition significantly counteracted TMZ-resistance of GBM cells. Extracellular vesicles (EV) are considered crucial mediators in orchestrating GBM drug resistance by modulating the tumor microenvironment (TME) and affecting the surrounding recipient cell phenotype and behavior. This work aimed to verify whether TMZ, at low and clinically relevant doses (5-20 µM), could induce COX-2 overexpression in GBM cells (T98G and U87MG) and explore if secreted EV shuttled COX-2 to recipient cells. The effect of COX-2 inhibitors (COXIB), Celecoxib (CXB), or NS398, alone or TMZ-combined, was also investigated. Our results indicated that TMZ at clinically relevant doses upregulated COX-2 in GBM cells. COXIB treatment significantly counteracted TMZ-induced COX-2 expression, confirming the crucial role of the COX-2/PGE2 system in TMZ-resistance. The COXIB specificity was verified on U251MG, COX-2 null GBM cells. Western blotting of GBM-EV cells showed the COX-2 presence, with the same intracellular trend, increasing in EV derived from TMZ-treated cells and decreasing in those derived from COXIB+TMZ-treated cells. We then evaluated the effect of EV secreted by TMZ-treated cells on U937 and U251MG, used as recipient cells. In human macrophage cell line U937, the internalization of EV derived by TMZ-T98G cells led to a shift versus a pro-tumor M2-like phenotype. On the other hand, EV from TMZ-T98G induced a significant decrease in TMZ sensitivity in U251MG cells. Overall, our results, in confirming the crucial role played by COX-2 in TMZ-resistance, provide the first evidence of the presence and effective functional transfer of this enzyme through EV derived from GBM cells, with multiple potential consequences at the level of TME.

Glucocorticoids and natural killer cells: A suppressive relationship.

Glucocorticoids exert their pharmacological actions by mimicking and amplifying the function of the endogenous glucocorticoid system's canonical physiological stress response. They affect the immune system at the levels of inflammation and adaptive and innate immunity. These effects are the basis for therapeutic use of glucocorticoids. Innate immunity is the body's first line of defense against disease conditions. It is relatively nonspecific and, among its mediators, natural killer (NK) cells link innate and acquired immunity. NK cell numbers are altered in patients with auto immune diseases, and research suggests that interactions between glucocorticoids and natural killer cells are critical for successful glucocorticoid therapy. The aim of this review is to summarize these interactions while highlighting the latest and most important developments in this field. Production and release in the blood of endogenous glucocorticoids are strictly regulated by the hypothalamus-pituitary adrenal axis. A self-regulatory mechanism prevents excessive plasma levels of these hormones. However, exogenous stimuli such as stress, inflammation, infections, cancer, and autoimmune disease can trigger the hypothalamus-pituitary-adrenal axis response and lead to excessive systemic release of glucocorticoids. Thus, stress stimuli, such as sleep deprivation, intense exercise, depression, viral infections, and cancer, can result in release of glucocorticoids and associated immunosuppressant effects. Among these effects are decreases in the numbers and activities of NK cells in inflammatory and autoimmune diseases (e.g., giant cell arteritis, polymyalgia rheumatica, and familial hypogammaglobulinemia).

Effect of dietary saturated fatty acids on HNF-4α DNA binding activity and ApoCIII mRNA in sedentary rat liver.

Hind limb-suspended rats represent a sedentary-hyperinsulinemic model with a liver dyslipidemia mainly related to changes in sterol regulatory element-binding protein 1 (SREBP-1) and peroxisome proliferator-activated receptor-α (PPARα) expression and activity. To assess the effects of dietary fatty acids on hepatic lipid homeostasis, the hepatic expression and activity of PPARα, SREBP-1, and hepatocyte nuclear factor-4α (HNF-4α) were investigated in this animal model. In control and sedentary rats, diets enriched with saturated, monounsaturated, and polyunsaturated fatty acids (PUFA) enhanced the expression of the PPARα target genes carnitine palmitoyltransferase 1 and acyl-CoA oxidase, the highest effect being exerted by ω-3. The same diets reduced SREBP-1 mRNA and target lipogenic gene expression, as indicated by the reduction in fatty acid synthase and acetyl-CoA carboxylase mRNA content. Effects were greater in sedentary rat liver than in controls on the same diet. Only the ω-3 enriched diet decreased liver triglyceride content as well as plasma cholesterol and triglyceride levels in sedentary rats. This effect may be mainly related to the enhanced mitochondrial and peroxisomal ß-oxidation genes expression. On the other hand, saturated fatty acid-enriched diet induced an increase in liver triglyceride content and enhanced plasma cholesterol and triglyceride levels, both in control and immobilized rats. This detrimental effect may be ascribed to the induced HNF-4α binding activity on ApoCIII promoter and to the enhanced ApoCIII mRNA levels both in control and in sedentary rat livers. In conclusion, we can speculate that dietary saturated fats, acting at apolipoprotein transcriptional level, may impact on the close relationship existing among high ApoCIII plasma level, dyslipidemia, and atherosclerosis.

Glucocorticoid and PD-1 Cross-Talk: Does the Immune System Become Confused?

Programmed cell death protein 1 (PD-1) and its ligands, PD-L1/2, control T cell activation and tolerance. While PD-1 expression is induced upon T cell receptor (TCR) activation or cytokine signaling, PD-L1 is expressed on B cells, antigen presenting cells, and on non-immune tissues, including cancer cells. Importantly, PD-L1 binding inhibits T cell activation. Therefore, the modulation of PD-1/PD-L1 expression on immune cells, both circulating or in a tumor microenvironment and/or on the tumor cell surface, is one mechanism of cancer immune evasion. Therapies that target PD-1/PD-L1, blocking the T cell-cancer cell interaction, have been successful in patients with various types of cancer. Glucocorticoids (GCs) are often administered to manage the side effects of chemo- or immuno-therapy, exerting a wide range of immunosuppressive and anti-inflammatory effects. However, GCs may also have tumor-promoting effects, interfering with therapy. In this review, we examine GC signaling and how it intersects with PD-1/PD-L1 pathways, including a discussion on the potential for GC- and PD-1/PD-L1-targeted therapies to "confuse" the immune system, leading to a cancer cell advantage that counteracts anti-cancer immunotherapy. Therefore, combination therapies should be utilized with an awareness of the potential for opposing effects on the immune system.

GILZ mediates the antiproliferative activity of glucocorticoids by negative regulation of Ras signaling.

Tsc22d3 coding for glucocorticoid-induced leucine zipper (GILZ) was initially identified as a dexamethasone-responsive gene involved in the control of T lymphocyte activation and apoptosis. However, the physiological role of this molecule and its function in the biological activity of glucocorticoids (GCs) has not been clarified. Here, we demonstrate that GILZ interacts directly with Ras in vitro and in vivo as shown by GILZ and Ras coimmunoprecipitation and colocalization upon PMA activation in primary mouse spleen T lymphocytes and thymus cells. The analysis of GILZ mutants showed that they bound Ras through the tuberous sclerosis complex box (TSC) and, depending on the Ras activation level, formed a trimeric complex with Ras and Raf, which we previously identified as a GILZ binder. As a consequence of these interactions, GILZ diminished the activation of Ras and Raf downstream targets including ERK1/2, AKT/PKB serine/threonine kinase, and retinoblastoma (Rb) phosphorylation and cyclin D1 expression, leading to inhibition of Ras- and Raf-dependent cell proliferation and Ras-induced NIH-3T3 transformation. GILZ silencing resulted in an increase in concanavalin A-induced T cell proliferation and, most notably, inhibition of dexamethasone antiproliferative effects. Together, these findings indicate that GILZ serves as a negative regulator of Ras- and Raf-induced proliferation and is an important mediator of the antiproliferative effect of GCs.

Glucocorticoid-induced leucine zipper (GILZ): a new important mediator of glucocorticoid action.

Glucocorticoids (GCs) represent the mainstay of current anti-inflammatory and immunosuppressive strategies, mediating effects that mostly result in transcriptional regulation of glucocorticoid receptor target genes. A variety of actions are tied together in the response to GC treatment. Dissecting the beneficial from the detrimental actions in GC therapy is a major challenge in basic research, raising the critical issue of whether a single target gene or gene family might eventually be linked to a specific GC function. Glucocorticoid-induced leucine zipper (GILZ) was originally discovered in studies aimed at characterizing genes targeted by dexamethasone. The first suggestion that GILZ plays an important role in GC immunomodulation came from observations of GILZ up-regulation by GCs, mainly in lymphoid organs, and inhibition of anti-CD3-induced activation and apoptosis. The identification of GILZ interaction with and inhibition of NF-kappaB provided a first molecular mechanistic basis for explaining GILZ effects on T cells. Subsequently, other GILZ targets have been identified, including AP-1, Raf-1, and Ras, all involved in GC effects. The finding that GILZ silencing abrogates the antiproliferative activity of dexamethasone and reduces GC inhibition of cytokine-induced COX-2 expression clearly gained GILZ a distinguished reputation within the critical mediators of GC effects. The multiple functions of GILZ and their potential biological relevance are here reviewed.

A Glance at the Use of Glucocorticoids in Rare Inflammatory and Autoimmune Diseases: Still an Indispensable Pharmacological Tool?

Since their discovery, glucocorticoids (GCs) have been used to treat almost all autoimmune and chronic inflammatory diseases, as well as allergies and some forms of malignancies, because of their immunosuppressive and anti-inflammatory effects. Although GCs provide only symptomatic relief and do not eliminate the cause of the pathology, in the majority of treatments, GCs frequently cannot be replaced by other classes of drugs. Consequently, long-term treatments cause adverse effects that may, in turn, lead to new pathologies that sometimes require the withdrawal of GC therapy. Therefore, thus far, researchers have focused their efforts on molecules that have the same efficacy as that of GCs but cause fewer adverse effects. To this end, some GC-induced proteins, such as glucocorticoid-induced leucine zipper (GILZ), have been used as drugs in mouse models of inflammatory pathologies. In this review, we focus on some important but rare autoimmune and chronic inflammatory diseases for which the biomedical research investment in new therapies is less likely. Additionally, we critically evaluate the possibility of treating such diseases with other drugs, either GC-related or unrelated.

L-GILZ binds and inhibits nuclear factor κB nuclear translocation in undifferentiated thyroid cancer cells.

Proto-oncogene mutations and abnormal activation of mitogen-activated protein kinase (MAPK) signalling are recurrently found in thyroid cancers. Some thyroid neoplasms respond to drugs that inhibit MAPK pathway activation. Previously, we showed that pharmacological inhibition of MAPK in thyroid cancer cells inhibits cell proliferation and upregulates L-GILZ (long glucocorticoid-induced leucine zipper), a protein with anti-oncogenic and antiproliferative activity, and that L-GILZ is partially responsible for the antiproliferative activity of MAPK inhibitors. Here, we demonstrate that pharmacological inhibition of MAPK in the anaplastic thyroid cancer cell line CAL-62 upregulated L-GILZ, which bound nuclear factor κB (NF-κB) and inhibited its nuclear translocation. These data demonstrate a unique L-GILZ-mediated molecular mechanism that, by trapping NF-κB in the cytoplasm, contributes to the inhibition of proliferation induced by drugs targeting the MAPK transduction cascade. Enhanced knowledge of the mechanism of action of MAPK pathway-inhibiting drugs may improve their clinical use.

Bcl-xL overexpression decreases GILZ levels and inhibits glucocorticoid-induced activation of caspase-8 and caspase-3 in mouse thymocytes.

Glucocorticoids promote thymocyte apoptosis and modulate transcription of numerous regulators of thymic apoptosis. Among these, glucocorticoid-induced leucine zipper (GILZ) is strongly upregulated in the thymus. We have previously demonstrated that GILZ decreases Bcl-xL expression, activates caspase-8 and caspase-3, and augments apoptosis in mice thymocytes. To better understand the causal links between glucocorticoids, GILZ, Bcl-xL, caspase-8, and caspase-3, we analyzed the thymocytes of Bcl-xL-overexpressing transgenic mice with or without glucocorticoid stimulation in vitro. Overexpression of Bcl-xL inhibited the glucocorticoid-induced up-regulation of GILZ in murine thymocytes as well as the glucocorticoid-dependent activation of caspase-8 and caspase-3. By contrast, no appreciable change in caspase-9 activation was observed upon Bcl-xL overexpression. Thus, these experiments highlighted a novel thymocyte apoptotic pathway in which Bcl-xL overexpression inhibited the glucocorticoid-induced activation of caspase-8 and caspase-3, but not caspase-9, as well as the accumulation of GILZ protein. These findings, together with our previous results showing that caspase-8 protects GILZ from proteasomal degradation, suggest the presence of a glucocorticoid-induced apoptosis self-amplification loop in which GILZ decreases Bcl-xL expression with a subsequent activation of caspase-8 and caspase-3; caspase-8 activation then enhances the stability and accumulation of GILZ and ensures the unimpeded and irreversible progression of apoptosis. By contrast, inappropriate increases in Bcl-xL levels could have catastrophic effects on thymic apoptosis as it would shut down caspase-8/3 activation, diminish the expression of GILZ, and impair the fine control necessary for thymic generation of a healthy immune repertoire.

Implicating the Role of GILZ in Glucocorticoid Modulation of T-Cell Activation.

Glucocorticoid-induced leucine zipper (GILZ) is a protein with multiple biological roles that is upregulated by glucocorticoids (GCs) in both immune and non-immune cells. Importantly, GCs are immunosuppressive primarily due to their regulation of cell signaling pathways that are crucial for immune system activity. GILZ, which is transcriptionally induced by the glucocorticoid receptor (GR), mediates part of these immunosuppressive, and anti-inflammatory effects, thereby controlling immune cell proliferation, survival, and differentiation. The primary immune cells targeted by the immunosuppressive activity of GCs are T cells. Importantly, the effects of GCs on T cells are partially mediated by GILZ. In fact, GILZ regulates T-cell activation, and differentiation by binding and inhibiting factors essential for T-cell function. For example, GILZ associates with nuclear factor-κB (NF-κB), c-Fos, and c-Jun and inhibits NF-κB-, and AP-1-dependent transcription. GILZ also binds Raf and Ras, inhibits activation of Ras/Raf downstream targets, including mitogen-activated protein kinase 1 (MAPK1). In addition GILZ inhibits forkhead box O3 (FoxO3) without physical interaction. GILZ also promotes the activity of regulatory T cells (Tregs) by activating transforming growth factor-ß (TGF-ß) signaling. Ultimately, these actions inhibit T-cell activation and modulate the differentiation of T helper (Th)-1, Th-2, Th-17 cells, thereby mediating the immunosuppressive effects of GCs on T cells. In this mini-review, we discuss how GILZ mediates GC activity on T cells, focusing mainly on the therapeutic potential of this protein as a more targeted anti-inflammatory/immunosuppressive GC therapy.

Fusarubin and Anhydrofusarubin Isolated from A Cladosporium Species Inhibit Cell Growth in Human Cancer Cell Lines.

Cladosporium species are endophytic fungi that grow on organic matter and are considered food contaminants. The anti-microbial and anti-tumor naphthoquinones fusarubin (FUS) and anhydrofusarubin (AFU) were isolated using column chromatography from a Cladosporium species residing inside Rauwolfia leaves. The impact of FUS and AFU on cell growth was assessed in acute myeloid leukemia (OCI-AML3) and other hematologic tumor cell lines (HL-60, U937, and Jurkat). Treatment with FUS or AFU reduced the number of OCI-AML3 cells as evaluated by a hemocytometer. Flow cytometry analyses showed that this effect was accompanied by diverse impairments in cell cycle progression. Specifically, FUS (20 or 10 µg/mL significantly decreased the percentage of cells in S phase and increased the percentage of cells in G2/M phase, whereas AFU increased the percentage of cells in G0/G1 phase (50 and 25 µg/mL) and decreased the percentage of cells in S (50 µg/mL) and G2/M (50 and 25 µg/mL) phases. Both substances significantly increased apoptosis at higher concentrations. The effects of FUS were more potent than those of AFU, with FUS up-regulating p21 expression in a p53-dependent manner, as detected by Western blot analyses, likely the consequence of decreased ERK phosphorylation and increased p38 expression (both of which increase p21 stability). FUS also decreased Akt phosphorylation and resulted in increased Fas ligand production and caspase-8/3-dependent apoptosis. These results suggest that FUS and AFU inhibit proliferation and increase apoptosis in cell lines derived from hematological cancers.