Andrea Antonosante

Glioblastoma Stem Cells Microenvironment: The Paracrine Roles of the Niche in Drug and Radioresistance

Among all solid tumors, the high-grade glioma appears to be the most vascularized one. In fact, “microvascular hyperplasia” is a hallmark of GBM. An altered vascular network determines irregular blood flow, so that tumor cells spread rapidly beyond the diffusion distance of oxygen in the tissue, with the consequent formation of hypoxic or anoxic areas, where the bulk of glioblastoma stem cells (GSCs) reside. The response to this event is the induction of angiogenesis, a process mediated by hypoxia inducible factors. However, this new capillary network is not efficient in maintaining a proper oxygen supply to the tumor mass, thereby causing an oxygen gradient within the neoplastic zone. This microenvironment helps GSCs to remain in a “quiescent” state preserving their potential to proliferate and differentiate, thus protecting them by the effects of chemo- and radiotherapy. Recent evidences suggest that responses of glioblastoma to standard therapies are determined by the microenvironment of the niche, where the GSCs reside, allowing a variety of mechanisms that contribute to the chemo- and radioresistance, by preserving GSCs. It is, therefore, crucial to investigate the components/factors of the niche in order to formulate new adjuvant therapies rendering more efficiently the gold standard therapies for this neoplasm.

Involvement of peroxisome proliferator-activated receptor β/δ (PPAR β/δ) in BDNF signaling during aging and in Alzheimer disease: Possible role of 4-hydroxynonenal (4-HNE)

Aging and many neurological disorders, such as AD, are linked to oxidative stress, which is considered the common effector of the cascade of degenerative events. In this phenomenon, reactive oxygen species play a fundamental role in the oxidative decomposition of polyunsaturated fatty acids, resulting in the formation of a complex mixture of aldehydic end products, such as malondialdehyde, 4-hydroxynonenal, and other alkenals. Interestingly, 4-HNE has been indicated as an intracellular agonist of peroxisome proliferator-activated receptor β/δ. In this study, we examined, at early and advanced AD stages (3, 9, and 18 months), the pattern of 4-HNE and its catabolic enzyme glutathione S-transferase P1 in relation to the expression of PPARβ/δ, BDNF signaling, as mRNA and protein, as well as on their pathological forms (i.e., precursors or truncated forms). The data obtained indicate a novel detrimental age-dependent role of PPAR β/δ in AD by increasing pro-BDNF and decreasing BDNF/TrkB survival pathways, thus pointing toward the possibility that a specific PPARβ/δ antagonist may be used to counteract the disease progression.

Nucleolin antagonist triggers autophagic cell death in human glioblastoma primary cells and decreased in vivo tumor growth in orthotopic brain tumor model

Nucleolin (NCL) is highly expressed in several types of cancer and represents an interesting therapeutic target. It is expressed at the plasma membrane of tumor cells, a property which is being used as a marker for several human cancer including glioblastoma. In this study we investigated targeting NCL as a new therapeutic strategy for the treatment of this pathology. To explore this possibility, we studied the effect of an antagonist of NCL, the multivalent pseudopeptide N6L using primary culture of human glioblastoma cells. In this system, N6L inhibits cell growth with different sensitivity depending to NCL localization. Cell cycle analysis indicated that N6L-induced growth reduction was due to a block of the G1/S transition with down-regulation of the expression of cyclin D1 and B2. By monitoring autophagy markers such as p62 and LC3II, we demonstrate that autophagy is enhanced after N6L treatment. In addition, N6L-treatment of mice bearing tumor decreased in vivo tumor growth in orthotopic brain tumor model and increase mice survival. The results obtained indicated an anti-proliferative and pro-autophagic effect of N6L and point towards its possible use as adjuvant agent to the standard therapeutic protocols presently utilized for glioblastoma.

Gastroprotective Effects of L-Lysine Salification of Ketoprofen in Ethanol-Injured Gastric Mucosa

Ketoprofen L‐lysine salt (KLS), a NSAID, is widely used for its analgesic efficacy and tolerability. L‐lysine salification was reported to increase the solubility and the gastric absorption and tolerance of ketoprofen. Since the management of NSAIDs gastrotoxicity still represents a major limitation in prolonged therapies, mainly when gastric lesions are present, this study investigated the gastro‐protective activity of L‐lysine by using a well‐established model of gastric mucosa injury, the ethanol‐gastric injury model. Several evidences show that the damaging action of ethanol could be attributed to the increase of ROS, which plays a key role in the increase of lipid peroxidation products, including malonyldialdehyde and 4‐hydroxy‐2‐nonenal. With the aim to unravel the mechanism of L‐lysine gastroprotection, cellular MDA levels and 4‐HNE protein adducts as markers of lipid peroxidation and a panel of key endogenous gastro‐protective proteins were assayed. The data obtained indicate a gastroprotective effect of L‐lysine on gastric mucosa integrity. J. Cell. Physiol. 230: 813–820, 2015.

Peroxisome Proliferator-Activated Receptors in Female Reproduction and Fertility

Reproductive functions may be altered by the exposure to a multitude of endogenous and exogenous agents, drug or environmental pollutants, which are known to affect gene transcription through the peroxisome proliferator-activated receptors (PPARs) activation. PPARs act as ligand activated transcription factors and regulate metabolic processes such as lipid and glucose metabolism, energy homeostasis, inflammation, and cell proliferation and differentiation. All PPARs isotypes are expressed along the hypothalamic-pituitary-gonadal axis and are strictly involved in reproductive functions. Since female fertility and energy metabolism are tightly interconnected, the research on female infertility points towards the exploration of potential PPARs activating/antagonizing compounds, mainly belonging to the class of thiazolidinediones (TZDs) and fibrates, as useful agents for the maintenance of metabolic homeostasis in women with ovarian dysfunctions. In the present review, we discuss the recent evidence about PPARs expression in the hypothalamic-pituitary-gonadal axis and their involvement in female reproduction. Finally, the therapeutic potential of their manipulation through several drugs is also discussed.

Roles of PPAR transcription factors in the energetic metabolic switch occurring during adult neurogenesis

ABSTRACT PPARs are a class of ligand-activated transcription factors belonging to the superfamily of receptors for steroid and thyroid hormones, retinoids and vitamin D that control the expression of a large number of genes involved in lipid and carbohydrate metabolism and in the regulation of cell proliferation, differentiation and death. The role of PPARs in the CNS has been primarily associated with lipid and glucose metabolism; however, these receptors are also implicated in neural cell differentiation and death, as well as neuronal maturation. Although it has been demonstrated that PPARs play important roles in determining NSCs fate, less is known about their function in regulating NSCs metabolism during differentiation. In order to identify the metabolic events, controlled by PPARs, occurring during neuronal precursor differentiation, the glucose and lipid metabolism was followed in a recognized model of neuronal differentiation in vitro, the SH-SY5Y neuroblastoma cell line. Moreover, PPARs distribution were also followed in situ in adult mouse brains. The concept of adult neurogenesis becomes relevant especially in view of those disorders in which a loss of neurons is described, such as Alzheimer disease, Parkinson disease, brain injuries and other neurological disorders. Elucidating the crucial steps in energetic metabolism and the involvement of PPARγ in NSC neuronal fate (lineage) may be useful for the future design of preventive and/or therapeutic interventions.

Flavopiridol: An Old Drug With New Perspectives? Implication for Development of New Drugs.

Glioblastoma, the most common brain tumor, is characterized by high proliferation rate, invasion, angiogenesis, and chemo‐ and radio‐resistance. One of most remarkable feature of glioblastoma is the switch toward a glycolytic energetic metabolism that leads to high glucose uptake and consumption and a strong production of lactate. Activation of several oncogene pathways like Akt, c‐myc, and ras induces glycolysis and angiogenesis and acts to assure glycolysis prosecution, tumor proliferation, and resistance to therapy. Therefore, the high glycolytic flux depends on the overexpression of glycolysis‐related genes resulting in an overproduction of pyruvate and lactate. Metabolism of glioblastoma thus represents a key issue for cancer research. Flavopiridol is a synthetic flavonoid that inhibits a wide range of Cyclin‐dependent kinase, that has been demonstrate to inactivate glycogen phosphorylase, decreasing glucose availability for glycolysis. In this work the study of glucose metabolism upon flavopiridol treatment in the two different glioblastoma cell lines. The results obtained point towards an effect of flavopiridol in glycolytic cells, thus suggesting a possible new use of this compound or flavopiridol‐derived formulations in combination with anti‐proliferative agents in glioblastoma patients. J. Cell. Physiol. 232: 312–322, 2017.

PPARβ/δ and γ in a Rat Model of Parkinson's Disease: Possible Involvement in PD Symptoms

Parkinsons disease is one of the most common neurologic disorder, affecting about 1–4% of persons older than 60 years. Among the proposed mechanisms of PD generation, free radical damage is believed to play a pivotal role in the development and/or progression of the disease. Recently, PPARs, a class of transcription factors involved in several pathways both in physiological and pathological conditions, have been linked by us and others to neurodegeneration. Particularly, PPARγ and its ligands have been indicated as potential therapeutic targets for the treatment of several pathological conditions associated with neuroinflammation within the CNS. The anti‐inflammatory function of PPARγ has attracted attention since agonists exert a broad spectrum of protective effects in several animal models of neurological diseases, including psychiatric diseases. On the other hand a detrimental role for PPARβ/δ has been proposed in Alzheimer, being closely related to the decrease of BDNF and Trkfl. On these bases, in this work we used a 6‐OHDA hemi‐lesioned rat model, inducing loss of dopaminergic neurons, to study the effects of the lesion at three time points from the lesion (1, 2, and 3 weeks), in relevant areas of PD motor symptoms, such as substantia nigra and globus pallidus and in the area of reward and mood control, the nucleus accumbens. In particular, it was studied: (i) the expression of BDNF and its downstream signals; (ii) the modulation of PPARs levels. The results obtained indicate the possible use of a dual PPARβ/δ antagonist/PPARγ agonist to counteract primary and secondary signs of PD neurodegeneration. J. Cell. Biochem. 116: 844–855, 2015.

PPARα Antagonist AA452 Triggers Metabolic Reprogramming and Increases Sensitivity to Radiation Therapy in Human Glioblastoma Primary Cells

Glioblastoma (GB) is the most common cancer in the brain and with an increasing incidence. Despite major advances in the field, there is no curative therapy for GB to date. Many solid tumors, including GB, experienced metabolic reprogramming in order to sustain uncontrolled proliferation, hypoxic conditions, and angiogenesis. PPARs, member of the steroid hormone receptor superfamily, are particularly involved in the control of energetic metabolism, particularly lipid metabolism, which has been reported deregulated in gliomas. PPARα was previously indicated by us as a potential therapeutic target for this neoplasm, due to the malignancy grade dependency of its expression, being particularly abundant in GB. In this work, we used a new PPARα antagonist on patient‐derived GB primary cells, with particular focus on the effects on lipid metabolism and response to radiotherapy. The results obtained demonstrated that blocking PPARα results in cell death induction, increase of radiosensitivity, and decrease of migration. Therefore, AA452 is proposed as a new adjuvant for the gold standard therapies for GB, opening the possibility for preclinical and clinical trials for this class of compounds. J. Cell. Physiol. 232: 1458–1466, 2017.

PDZ Domain in the Engineering and Production of a Saporin Chimeric Toxin as a Tool for targeting Cancer Cells.

In this paper we have studied a PDZ protein domain as a possible tool for cellular targeting of the ribosome inactivating protein Saporin, exploiting the ability of PDZ domains to recognize and bind short peptide sequences located at the C‐terminus of a cognate protein. We have focused our attention on the PDZ domain from hCASK (Human calcium/calmodulin‐dependent serine protein kinase) that binds extracellular CD98 in epithelial cells, being this antigen recognized as a marker for several human tumors and particularly considered a negative prognostic marker for human glioblastoma. We produced recombinant fusions of one or two hCASK‐PDZ domains with the ribosome inactivating protein Saporin and assayed them on two human glioblastoma cell lines (GL15 and U87). These constructs proved to be toxic, with increasing activity as a function of the number of PDZ domains, and induce cell death by apoptotic mechanisms in a dose‐dependent and/or time dependent manner. J. Cell. Biochem. 116: 1256–1266, 2015.