Gender Influence on XOR Activities and Related Pathologies: A Narrative Review

Taking into account the patient's gender is the first step towards more precise and egalitarian medicine. The gender-related divergences observed in purine catabolism and their pathological consequences are good examples of gender medicine differences. Uric acid is produced by the activity of xanthine oxidoreductase (XOR). The serum levels of both XOR activity and uric acid differ physiologically between the genders, being higher in men than in women. Their higher levels have been associated with gout and hypertension, as well as with vascular, cardiac, renal, and metabolic diseases. The present review analyzes the gender-related differences in these pathological conditions in relation to increases in the serum levels of XOR and/or uric acid and the opportunity for gender-driven pharmacological treatment.

Heterophyllin: A New Adenia Toxic Lectin with Peculiar Biological Properties

Ribosome-inactivating proteins (RIPs) are plant toxins that were identified for their ability to irreversibly damage ribosomes, thereby causing arrest of protein synthesis and induction of cell death. The RIPs purified from Adenia plants are the most potent ones. Here, we describe a novel toxic lectin from Adenia heterophylla caudex, which has been named heterophyllin. Heterophyllin shows the enzymatic and lectin properties of type 2 RIPs. Interestingly, in immunoreactivity experiments, heterophyllin poorly cross-reacts with sera against all other tested RIPs. The cytotoxic effects and death pathways triggered by heterophyllin were investigated in three human-derived cell lines: NB100, T24, and MCF7, and compared to ricin, the most known and studied type 2 RIP. Heterophyllin was able to completely abolish cell viability at nM concentration. A strong induction of apoptosis, but not necrosis, and the involvement of oxidative stress and necroptosis were observed in all the tested cell lines. Therefore, the enzymatic, immunological, and biological activities of heterophyllin make it an interesting molecule, worthy of further in-depth analysis to verify its possible pharmacological application.

Design and optimization of a high-energy optical parametric amplifier for broadband, spectrally incoherent pulses

Spectrally incoherent laser pulses with sufficiently large fractional bandwidth are in demand for the mitigation of laser-plasma instabilities occurring in high-energy laser-target interactions. Here, we modeled, implemented, and optimized a dual-stage high-energy optical parametric amplifier for broadband, spectrally incoherent pulses in the near-infrared. The amplifier delivers close to 400 mJ of signal energy through noncollinear parametric interaction of 100-nJ-scale broadband, spectrally incoherent seed pulses near 1053 nm with a narrowband high-energy pump operating at 526.5 nm. Mitigation strategies for high-frequency spatial modulations in the amplified signal caused by index inhomogeneities in the Nd:YLF rods of the pump laser are explored and discussed in detail.

New Insights on Saporin Resistance to Chemical Derivatization with Heterobifunctional Reagents

Saporin is a type 1 ribosome-inactivating protein widely used as toxic payload in the construction of targeted toxins, chimeric molecules formed by a toxic portion linked to a carrier moiety. Among the most used carriers, there are large molecules (mainly antibodies) and small molecules (such as neurotransmitters, growth factors and peptides). Some saporin-containing targeted toxins have been used for the experimental treatment of several diseases, giving very promising results. In this context, one of the reasons for the successful use of saporin lies in its resistance to proteolytic enzymes and to conjugation procedures. In this paper, we evaluated the influence of derivatization on saporin using three heterobifunctional reagents, namely 2-iminothiolane (2-IT), N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP) and 4-succinimidyloxycarbonyl-α-methyl-α-[2-pyridyldithio]toluene (SMPT). In order to obtain the highest number of inserted -SH groups with the lowest reduction of saporin biological activities, we assessed the residual ability of saporin to inhibit protein synthesis, to depurinate DNA and to induce cytotoxicity after derivatization. Our results demonstrate that saporin maintains an excellent resistance to derivatization processes, especially with SPDP, and permit us to define reaction conditions, in which saporin biological properties may not be altered. Therefore, these findings provide useful information for the construction of saporin-based targeted toxins, especially with small carriers.

Structure and Biological Properties of Ribosome-Inactivating Proteins and Lectins from Elder (Sambucus nigra L.) Leaves

Ribosome-inactivating proteins (RIPs) are a group of proteins with rRNA N-glycosylase activity that catalyze the removal of a specific adenine located in the sarcin–ricin loop of the large ribosomal RNA, which leads to the irreversible inhibition of protein synthesis and, consequently, cell death. The case of elderberry (Sambucus nigra L.) is unique, since more than 20 RIPs and related lectins have been isolated and characterized from the flowers, seeds, fruits, and bark of this plant. However, these kinds of proteins have never been isolated from elderberry leaves. In this work, we have purified RIPs and lectins from the leaves of this shrub, studying their main physicochemical characteristics, sequences, and biological properties. In elderberry leaves, we found one type 2 RIP and two related lectins that are specific for galactose, four type 2 RIPs that fail to agglutinate erythrocytes, and one type 1 RIP. Several of these proteins are homologous to others found elsewhere in the plant. The diversity of RIPs and lectins in the different elderberry tissues, and the different biological activities of these proteins, which have a high degree of homology with each other, constitute an excellent source of proteins that are of great interest in diagnostics, experimental therapy, and agriculture.

Chronic kidney disease: Which role for xanthine oxidoreductase activity and products?

The present review explores the role of xanthine oxidoreductase (XOR) in the development and progression of chronic kidney disease (CKD). Human XOR is a multi-level regulated enzyme, which has many physiological functions, but that is also implicated in several pathological processes. The main XOR activities are the purine catabolism, which generates uric acid, and the regulation of cell redox state and cell signaling, through the production of reactive oxygen species. XOR dysregulation may lead to hyperuricemia and oxidative stress, which could have a pathogenic role in the initial phases of CKD, by promoting cell injury, hypertension, chronic inflammation and metabolic derangements. Hypertension is common in CKD patients and many mechanisms inducing it (upregulation of renin-angiotensin-aldosterone system, endothelial dysfunction and atherosclerosis) may be influenced by XOR products. High XOR activity and hyperuricemia are also risk factors for obesity, insulin resistance, type 2 diabetes and metabolic syndrome that are frequent CKD causes. Moreover, CKD is common in patients with gout, which is characterized by hyperuricemia, and in patients with cardiovascular diseases, which are associated with hypertension, endothelial dysfunction and atherosclerosis. Although hyperuricemia is undoubtedly related to CKD, controversial findings have been hitherto reported in patients treated with urate-lowering therapies.

Anti-PD-L1 immunoconjugates for cancer therapy: Are available antibodies good carriers for toxic payload delivering?

Immune checkpoint mechanisms are important molecular cell systems that maintain tolerance toward autoantigens in order to prevent immunity-mediated accidental damage. It is well known that cancer cells may exploit these molecular and cellular mechanisms to escape recognition and elimination by immune cells. Programmed cell death protein-1 (PD-1) and its natural ligand programmed cell death ligand-1 (PD-L1) form the PD-L1/PD-1 axis, a well-known immune checkpoint mechanism, which is considered an interesting target in cancer immunotherapy. In fact, the expression of PD-L1 was found in various solid malignancies and the overactivation of PD-L1/PD-1 axis results in a poor patient survival rate. Breaking PD-L1/PD-1 axis, by blocking either the cancer side or the immune side of the axis, is currently used as anti-cancer strategy to re-establish a tumor-specific immune response. For this purpose, several blocking antibodies are now available. To date, three anti-PD-L1 antibodies have been approved by the FDA, namely atezolizumab, durvalumab and avelumab. The main advantages of anti-PD-L1 antibodies arise from the overexpression of PD-L1 antigen by a high number of tumor cells, also deriving from different tissues; this makes anti-PD-L1 antibodies potential pan-specific anti-cancer molecules. Despite the good results reported in clinical trials with anti-PD-L1 antibodies, there is a significant number of patients that do not respond to the therapy. In fact, it should be considered that, in some neoplastic patients, reduced or absent infiltration of cytotoxic T cells and natural killer cells in the tumor microenvironment or presence of other immunosuppressive molecules make immunotherapy with anti-PD-L1 blocking antibodies less effective. A strategy to improve the efficacy of antibodies is to use them as carriers for toxic payloads (toxins, drugs, enzymes, radionuclides, etc.) to form immunoconjugates. Several immunoconjugates have been already approved by FDA for treatment of malignancies. In this review, we focused on PD-L1 targeting antibodies utilized as carrier to construct immunoconjugates for the potential elimination of neoplastic cells, expressing PD-L1. A complete examination of the literature regarding anti-PD-L1 immunoconjugates is here reported, describing the results obtained in vitro and in vivo. The real potential of anti-PD-L1 antibodies as carriers for toxic payload delivery is considered and extensively discussed.

Sequence, Structure, and Binding Site Analysis of Kirkiin in Comparison with Ricin and Other Type 2 RIPs

Kirkiin is a new type 2 ribosome-inactivating protein (RIP) purified from the caudex of Adenia kirkii with a cytotoxicity compared to that of stenodactylin. The high toxicity of RIPs from Adenia genus plants makes them interesting tools for biotechnology and therapeutic applications, particularly in cancer therapy. The complete amino acid sequence and 3D structure prediction of kirkiin are here reported. Gene sequence analysis revealed that kirkiin is encoded by a 1572 bp open reading frame, corresponding to 524 amino acid residues, without introns. The amino acid sequence analysis showed a high degree of identity with other Adenia RIPs. The 3D structure of kirkiin preserves the overall folding of type 2 RIPs. The key amino acids of the active site, described for ricin and other RIPs, are also conserved in the kirkiin A chain. Sugar affinity studies and docking experiments revealed that both the 1α and 2γ sites of the kirkiin B chain exhibit binding activity toward lactose and D-galactose, being lower than ricin. The replacement of His246 in the kirkiin 2γ site instead of Tyr248 in ricin causes a different structure arrangement that could explain the lower sugar affinity of kirkiin with respect to ricin.

Xanthine oxidoreductase: A leading actor in cardiovascular disease drama

Cardiovascular diseases (CVD) are the leading cause of global mortality and their pathogenesis lies mainly in the atherosclerotic process. There are close connections linking oxidative stress and inflammation to endothelial dysfunction, atherosclerosis and, consequently, to CVD. This review focuses on the role of xanthine oxidoreductase (XOR) and its products on the development of chronic inflammation and oxidative stress, responsible for atheromatous plaque formation. Evidence is reported that an excessive level of XOR products favors inflammatory response and plaque development, thereby promoting major cardiovascular risk factors. Also, the relationship between hyperuricemia and hypertension as well as between XOR activity and CVD is confirmed. In spite of the increasing number of clinical studies investigating the output of cardiovascular patients treated with urate-lowering therapies (including uricosuric drugs, XOR inhibitors and recombinant uricase) the results are still uncertain. The inhibition of XOR activity appears more promising than just the control of uricemia level in preventing cardiovascular events, possibly because it also reduces the intracellular accumulation of urate, as well as the production of reactive oxygen species. However, XOR inhibition also reduces the availability of the multifaced mediator nitric oxide and, at present, can be recommended only in hyperuricemic patients.

Xanthine oxidoreductase: One enzyme for multiple physiological tasks

Human xanthine oxidoreductase (XOR) is a multiple-level regulated enzyme, resulting from a complicated evolutionary process that assigned it many physiological roles. The main XOR activities are: (i) xanthine dehydrogenase (XDH) activity that performs the last two steps of purine catabolism, from hypoxanthine to uric acid; (ii) xanthine oxidase (XO) activity that, besides purine catabolism, produces reactive oxygen species (ROS); (iii) nitrite reductase activity that generates nitric oxide, contributing to vasodilation and regulation of blood pressure; (iv) NADH oxidase activity that produces ROS. All these XOR activities contribute also to metabolize various endogenous and exogenous compounds, including some drugs. About XOR products, it should be considered that (i) uric acid is not only a proinflammatory agent, but also a fundamental antioxidant molecule in serum and (ii) XOR-derived ROS are essential to the inflammatory defensive response. Although XOR has been the object of a large number of studies, most of them were focused on the pathological consequences of its activity and there is not a clear and schematic picture of XOR physiological roles. In this review, we try to fill this gap, reporting and graphically schematizing the main roles of XOR and its products.

Kirkiin: A New Toxic Type 2 Ribosome-Inactivating Protein from the Caudex of Adenia kirkii

Ribosome-inactivating proteins (RIPs) are plant toxins that irreversibly damage ribosomes and other substrates, thus causing cell death. RIPs are classified in type 1 RIPs, single-chain enzymatic proteins, and type 2 RIPs, consisting of active A chains, similar to type 1 RIPs, linked to lectin B chains, which enable the rapid internalization of the toxin into the cell. For this reason, many type 2 RIPs are very cytotoxic, ricin, volkensin and stenodactylin being the most toxic ones. From the caudex of Adenia kirkii (Mast.) Engl., a new type 2 RIP, named kirkiin, was purified by affinity chromatography on acid-treated Sepharose CL-6B and gel filtration. The lectin, with molecular weight of about 58 kDa, agglutinated erythrocytes and inhibited protein synthesis in a cell-free system at very low concentrations. Moreover, kirkiin was able to depurinate mammalian and yeast ribosomes, but it showed little or no activity on other nucleotide substrates. In neuroblastoma cells, kirkiin inhibited protein synthesis and induced apoptosis at doses in the pM range. The biological characteristics of kirkiin make this protein a potential candidate for several experimental pharmacological applications both alone for local treatments and as component of immunoconjugates for systemic targeting in neurodegenerative studies and cancer therapy.

Primary Sequence and 3D Structure Prediction of the Plant Toxin Stenodactylin

Stenodactylin is one of the most potent type 2 ribosome-inactivating proteins (RIPs); its high toxicity has been demonstrated in several models both in vitro and in vivo. Due to its peculiarities, stenodactylin could have several medical and biotechnological applications in neuroscience and cancer treatment. In this work, we report the complete amino acid sequence of stenodactylin and 3D structure prediction. The comparison between the primary sequence of stenodactylin and other RIPs allowed us to identify homologies/differences and the amino acids involved in RIP toxic activity. Stenodactylin RNA was isolated from plant caudex, reverse transcribed through PCR and the cDNA was amplificated and cloned into a plasmid vector and further analyzed by sequencing. Nucleotide sequence analysis showed that stenodactylin A and B chains contain 251 and 258 amino acids, respectively. The key amino acids of the active site described for ricin and most other RIPs are also conserved in the stenodactylin A chain. Stenodactylin amino acid sequence shows a high identity degree with volkensin (81.7% for A chain, 90.3% for B chain), whilst when compared with other type 2 RIPs the identity degree ranges from 27.7 to 33.0% for the A chain and from 42.1 to 47.7% for the B chain.

Early Response to the Plant Toxin Stenodactylin in Acute Myeloid Leukemia Cells Involves Inflammatory and Apoptotic Signaling

Stenodactylin, a highly toxic type 2 ribosome-inactivating protein purified from the caudex of Adenia stenodactyla Harms, is a potential anticancer drug candidate. Previous studies demonstrated that stenodactylin induces apoptosis and necroptosis in treated cells, involving the production of reactive oxygen species. We analyzed the effect of stenodactylin on Raji and Ramos (Human Burkitt’s lymphoma cells) and MOLM-13 (acute myeloid leukemia cells). Moreover, we focused on the early events in MOLM-13 cells that characterize the cellular response to the toxin by whole-genome microarray analysis of gene expression. Treatment with stenodactylin induced the depurination of 28S rRNA within 4 h and increased the phosphorylation of p38 and JNK. A time-dependent activation of caspase 1, 2, 8, 9, 3/7 was also observed. Genome-wide gene expression microarray analysis revealed early changes in the expression of genes involved in the regulation of cell death, inflammation and stress response. After 4 h, a significant increase of transcript level was detectable for ATF3, BTG2, DUSP1, EGR1, and JUN. Increased upstream JUN signaling was also confirmed at protein level. The early response to stenodactylin treatment involves inflammatory and apoptotic signaling compatible with the activation of multiple cell death pathways. Because of the above described properties toward acute myeloid leukemia cells, stenodactylin may be a promising candidate for the design of new immunoconjugates for experimental cancer treatment.

Insights into penicillin-induced Chlamydia trachomatis persistence

Chlamydia persistence is a viable, but non-cultivable, growth stage, resulting in a long-term relationship with the infected host cell. In vitro, this condition can be induced by different stressor agents, including beta-lactam antibiotics, as penicillin. The aim of this study was to get new insights into the interactions between Chlamydia trachomatis (serovars D and L2) and the epithelial host cells (HeLa) during persistence condition. In particular, we evaluated the following aspects, by comparing the normal chlamydial development cycle with penicillin-induced persistence: (i) cell survival/death, (ii) externalization of phosphatidylserine, (iii) caspase 1 and caspase 3/7 activation, and (iv) reactive oxygen species (ROS) production by the infected cells. At 72 h post-infection, the cytotoxic effect displayed by CT was completely abolished for both serovars and for all levels of multiplicity of infection only in the cells with aberrant CT inclusions. At the same time, CT was able to switch off the exposure of the lipid phosphatidylserine on the surface of epithelial cells and to strongly inhibit the activation of caspase 1 and caspase 3/7 only in penicillin-treated cells. Forty-eight hours post-infection, CT elicited a significant ROS expression both in case of a normal cycle and in case of persistence. However, serovar L and penicillin-free infection activated a higher ROS production compared to serovar D and to penicillin-induced persistence, respectively. In conclusion, we added knowledge to the cellular dynamics taking place during chlamydial persistence, demonstrating that CT creates a suitable niche to survive, switching off signals able to activate phagocytes/leukocytes recruitment. Nevertheless, persistent CT elicits ROS production by the infected cells, potentially contributing to the onset of chronic inflammation and tissue damages.

Survival and death of intestinal cells infected by Chlamydia trachomatis

The sexually transmitted pathogen Chlamydia trachomatis (CT) is able to replicate and survive in human intestinal epithelial cells, being the gastro-intestinal tract a suitable site of residence for this microorganism. In this context, no detailed information about the mechanisms of cell death in intestinal cell lines after a chlamydial infection is available. The aim of this study was to compare the effect of two different CT serovars (D and L2) on the survival/death of different intestinal cell lines (Caco-2 and COLO-205), using endocervical cells (HeLa) as a reference model of genital infection. Seventy two hours after chlamydial infection at different multiplicity of infection (MOI) levels, the viability of HeLa, Caco-2 and COLO 205 cells was evaluated through dose-response experiments by means of a MTS-based assay. To get deeper insights in the mechanisms of cell death induced by CT, cell viability was assessed in presence of different inhibitors (i.e. pan-caspase inhibitor Z-VAD, necroptosis inhibitor Necrostatin-1, hydrogen peroxide scavenger catalase, caspase-1 inhibitor Ac-YVAD-cmk). Moreover, the activation of effector caspases and the presence of cellular apoptotic/necrotic changes were evaluated at different time points after CT infection. Our results demonstrated that, for both chlamydial serovars, intestinal cell lines are more resistant to CT-induced cell death compared to HeLa, thus representing a suitable ‘niche’ for chlamydial residence and replication. In literature, apoptosis has been widely described to be the main cell death mechanism elicited by chlamydia infection. However, our data demonstrate that necroptosis plays a relevant role, proceeding in parallel with apoptosis. The protective effect of catalase suggests the involvement of oxidative stress in triggering both cell death pathways. Moreover, we demonstrated that caspase-1 is involved in CT-induced cell death, potentially contributing to host inflammatory response and tissue damage. Cells infected by L2 serovar displayed a higher activation of effector caspases compared to cells infected with serovar D, suggesting a serovar-specific activation of apoptotic pathways and potentially explaining the greater virulence of L serovars. Finally, we found that Chlamydia elicits the early externalization of phosphatidylserine on the external leaflet of plasma membrane independently of caspase activation.

Hexadecenoic Fatty Acid Positional Isomers and De Novo PUFA Synthesis in Colon Cancer Cells

Palmitic acid metabolism involves delta-9 and delta-6 desaturase enzymes forming palmitoleic acid (9cis-16:1; n-7 series) and sapienic acid (6cis-16:1; n-10 series), respectively. The corresponding biological consequences and lipidomic research on these positional monounsaturated fatty acid (MUFA) isomers are under development. Furthermore, sapienic acid can bring to the de novo synthesis of the n-10 polyunsaturated fatty acid (PUFA) sebaleic acid (5cis,8cis-18:2), but such transformations in cancer cells are not known. The model of Caco-2 cell line was used to monitor sapienic acid supplementation (150 and 300 μM) and provide evidence of the formation of n-10 fatty acids as well as their incorporation at levels of membrane phospholipids and triglycerides. Comparison with palmitoleic and palmitic acids evidenced that lipid remodelling was influenced by the type of fatty acid and positional isomer, with an increase of 8cis-18:1, n-10 PUFA and a decrease of saturated fats in case of sapienic acid. Cholesteryl esters were formed only in cases with sapienic acid. Sapienic acid was the less toxic among the tested fatty acids, showing the highest EC₅₀s and inducing death only in 75% of cells at the highest concentration tested. Two-photon fluorescent microscopy with Laurdan as a fluorescent dye provided information on membrane fluidity, highlighting that sapienic acid increases the distribution of fluid regions, probably connected with the formation of 8cis-18:1 and the n-10 PUFA in cell lipidome. Our results bring evidence for MUFA positional isomers and de novo PUFA synthesis for developing lipidomic analysis and cancer research.

Metabolic syndrome and cancer risk: The role of xanthine oxidoreductase

Obesity and related pathologies such as diabetes and metabolic syndrome are associated with chronic inflammation and cancer. The serum level of xanthine oxidoreductase (XOR) is correlated to obesity-associated metabolic disorders. XOR can play a role in the pathogenesis of both metabolic syndrome and cancer through the inflammatory response and the oxidative stress elicited by the products of its activity. The reactive oxygen and nitrogen species and the uric acid derived from XOR concur to the development of hypertension, dyslipidemia and insulin resistance and participate in both cell transformation and proliferation, as well as in the progression and metastasis process. Despite the availability of different drugs to inhibit in vivo XOR activity, the complexity of XOR inhibition effects should be carefully considered before clinical application, save in the case of symptomatic hyperuricemia.

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Metabolic syndrome (MS) increases the risk of cancer development.

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Xanthine oxidoreductase (XOR) plays a role in both MS and cancer.

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Uric acid, ROS and RNS produced by XOR cause inflammation and oxidative stress.

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Inflammation and oxidative stress contribute to the pathogenesis of MS and cancer.

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XOR activity can be pharmacologically controlled.

[Cu(TPMA)(Phen)](ClO4)2: Metallodrug Nanocontainer Delivery and Membrane Lipidomics of a Neuroblastoma Cell Line Coupled with a Liposome Biomimetic Model Focusing on Fatty Acid Reactivity

The use of copper complexes for redox and oxidative-based mechanisms in therapeutic strategies is an important field of multidisciplinary research. Here, a novel Cu(II) complex [Cu(TPMA)(Phen)](ClO4)2 (Cu-TPMA-Phen, where TPMA = tris-(2-pyridylmethyl)amine and Phen = 1,10-phenanthroline) was studied using both the free and encapsulated forms. A hollow pH-sensitive drug-delivery system was synthesized, characterized, and used to encapsulate and release the copper complex, thus allowing for the comparison with the free drug. The human neuroblastoma-derived cell line NB100 was treated with 5 μM Cu-PMA-Phen for 24 h, pointing to the consequences on mono- and polyunsaturated fatty acids (MUFA and PUFA) present in the membrane lipidome, coupled with cell viability and death pathways (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium viability assay, flow cytometry, microscopy, caspase activation). In parallel, the Cu-TPMA-Phen reactivity with the fatty acid moieties of phospholipids was studied using the liposome model to work in a biomimetic environment. The main results concerned: (i) the membrane lipidome in treated cells, involving remodeling with a specific increase of saturated fatty acids (SFAs) and a decrease of MUFA, but not PUFA; (ii) cytotoxic events and lipidome changes did not occur for the encapsulated Cu-TPMA-Phen, showing the influence of such nanocarriers on drug activity; and (iii) the liposome behavior confirmed that MUFA and PUFA fatty acid moieties in membranes are not affected by oxidative and isomerization reactions, proving the different reactivities of thiyl radicals generated from amphiphilic and hydrophilic thiols and Cu-TPMA-Phen. This study gives preliminary but important elements of copper(II) complex reactivity in cellular and biomimetic models, pointing mainly to the effects on membrane reactivity and remodeling based on the balance between SFA and MUFA in cell membranes that are subjects of strong interest for chemotherapeutic activities as well as connected to nutritional strategies.

Bouganin, an Attractive Weapon for Immunotoxins

Bougainvillea (Bougainvillea spectabilis Willd.) is a plant widely used in folk medicine and many extracts from different tissues of this plant have been employed against several pathologies. The observation that leaf extracts of Bougainvillea possess antiviral properties led to the purification and characterization of a protein, named bouganin, which exhibits typical characteristics of type 1 ribosome-inactivating proteins (RIPs). Beyond that, bouganin has some peculiarities, such as a higher activity on DNA with respect to ribosomal RNA, low systemic toxicity, and immunological properties quite different than other RIPs. The sequencing of bouganin and the knowledge of its three-dimensional structure allowed to obtain a not immunogenic mutant of bouganin. These features make bouganin a very attractive tool as a component of immunotoxins (ITs), chimeric proteins obtained by linking a toxin to a carrier molecule. Bouganin-containing ITs showed very promising results in the experimental treatment of both hematological and solid tumors, and one bouganin-containing IT has entered Phase I clinical trial. In this review, we summarize the milestones of the research on bouganin such as bouganin chemico-physical characteristics, the structural properties and de-immunization studies. In addition, the in vitro and in vivo results obtained with bouganin-containing ITs are summarized.

The role of xanthine oxidoreductase and uric acid in metabolic syndrome

Xanthine oxidoreductase (XOR) could contribute to the pathogenesis of metabolic syndrome through the oxidative stress and the inflammatory response induced by XOR-derived reactive oxygen species and uric acid. Hyperuricemia is strongly linked to hypertension, insulin resistance, obesity and hypertriglyceridemia. The serum level of XOR is correlated to triglyceride/high density lipoprotein cholesterol ratio, fasting glycemia, fasting insulinemia and insulin resistance index. Increased activity of endothelium-linked XOR may promote hypertension. In addition, XOR is implicated in pre-adipocyte differentiation and adipogenesis. XOR and uric acid play a role in cell transformation and proliferation as well as in the progression and metastatic process. Collected evidences confirm the contribution of XOR and uric acid in metabolic syndrome. However, in some circumstances XOR and uric acid may have anti-oxidant protective outcomes. The dual-face role of both XOR and uric acid explains the contradictory results obtained with XOR inhibitors and suggests caution in their therapeutic use.

Neoadjuvant CMV Chemotherapy plus Radical Cystectomy in Locally Advanced Bladder Cancer: The Impact of Pathologic Response on Long-Term Results

Aims and Background

Neoadjuvant systemic chemotherapy in infiltrating transitional cell carcinoma of the bladder has proved to be effective and to provide a pathologic complete response in about 30% of patients. No survival benefit has yet been proved.

Methods

We analyzed the outcome of 75 patients with advanced bladder cancer (stages T2-T4 N+/N0 M0) treated from 1985 to 1993 at two institutions in the same geographic area with 2 or 3 cycles of neoadjuvant CMV (cisplatin, methotrexate and vinblastine) chemotherapy plus cystectomy. Transurethral resection of the tumor was expressly avoided in order to keep the tumor intact as a marker lesion to evaluate response to chemotherapy.

Results

At the time of analysis, the median follow-up of 67 assessable patients was 51.5±3.9 (SE) months. Forty-six patients (69%) had clinical evidence of extravesical spread of the bladder tumor and 6 of lymph node metastases at presentation. After cystectomy, a pathologic complete response (pT0, pN0) was achieved in only 6 cases (9%) and a pathologic partial response in 32 patients (48%). The overall 5-year survival rate of all patients was 61 ±6%. Those patients who had a major response to chemotherapy (pCR + pPR) had a 5-year disease-free survival rate of 74%, which was statistically higher (P=0.0021) than the 44% for the remaining nonresponding patients (pNR). Overall, 43% of the patients with stage T2-T3a disease achieved tumor downstaging (CR, 5%; PR, 38%) compared with 63% of the patients with T3b-T4 (CR, 11%; PR, 52%), although there was no significant difference in 5-year survival curves between the two groups.

Conclusions

A pathologic complete response was achieved in less than 10% of the cases without a preoperative tumor resection. Unfortunately, most of the responses were only partial. Even though the study appears to suggest a survival advantage for those patients who achieved a downstaging, CMV chemotherapy had a limited curative potential in most of the patients. It seems unlikely that determinant proof will be obtained that neoadjuvant chemotherapy may improve survival over a nontreatment control arm. The intrinsic chemoresistance or the suboptimal response to chemotherapy of bladder cancer remains the most adverse prognostic factor.

Quality Control by Portal Film Analysis in Radiotherapy for Prostate Cancer: A Comparison between Two Different Institutions and Treatment Techniques

AIMS AND BACKGROUND

Accuracy and reproducibility of patient setup during radiotherapy for prostate cancer were investigated in two different Institutions (A and B), within their Quality Assurance programs. The purpose of the study was to evaluate and compare setup accuracy and reproducibility in Institutions A and B, which adopt different patient positioning and treatment techniques for prostate irradiation.

MATERIALS AND METHODS

A retrospective analysis of portal localization films taken during the treatment course was performed: 30 and 21 patients in Institutes A and B, respectively, entered the study. In Institute A, patients were treated in a prone position, utilizing an individualized immobilization cast (either an alpha cradle or a heat and vacuum-formed cellulose acetate cast) with an open table top and individual abdominal wall compressor to minimize small bowel irradiation; a 5-field conformal technique was used. In Institute B, patients were treated in a supine position without any immobilization device; a 6-field BEV-based technique (conformal only for patients treated with a radical aim) was adopted. A total of 598 portal films (420 from Institute A and 178 from Institute B) were analyzed. The mean number of films per patient was 12 (range, 4-29). Systematic and random setup errors were estimated utilizing the statistical method suggested by Bijhold et al. (1992).

RESULTS

When patients with a mean (systematic) error larger than 5, 8 and 10 mm in craniocaudal, lateral and posterior-anterior directions, respectively, were compared, no statistically significant difference between the two groups was observed. Similarly, when comparing portal films, a significant difference (P <0.01) appeared only in the craniocaudal direction (errors > 5 mm: Institute A = 24%; Institute B = 11%). In both Institutes, the SD of random and systematic error distribution ranged from 1.8 to 4.2 mm, with a small prevalence of systematic errors. Only for craniocaudal shifts in Institute A was the random error larger than the systematic error, and it was significantly worse than in Institute B (1 SD, 4.2 mm in Institute A vs 1.8 mm in Institute B).

CONCLUSIONS

Setup errors observed in Institutes A and B were similar and in accord with data reported in the literature. In Institute B, satisfactory geometrical treatment quality was achieved without patient immobilization. In Institute A, the goal of minimizing small bowel irradiation and prostate motion through the aforementioned technique, which makes patient position less comfortable, did not seem to considerably increase daily setup uncertainty.

Immunoconjugates for Osteosarcoma Therapy: Preclinical Experiences and Future Perspectives

Osteosarcoma (OS) is an aggressive osteoid-producing tumor of mesenchymal origin, which represents the most common primary bone malignancy. It is characterized by a complex and frequently uncertain etiology. The current standard care for high-grade OS treatment is neoadjuvant chemotherapy, followed by surgery and post-operative chemotherapy. In order to ameliorate survival rates of patients, new therapeutic approaches have been evaluated, mainly immunotherapy with antibody-drug conjugates or immunoconjugates. These molecules consist of a carrier (frequently an antibody) joined by a linker to a toxic moiety (drug, radionuclide, or toxin). Although several clinical trials with immunoconjugates have been conducted, mainly in hematological tumors, their potential as therapeutic agents is relatively under-explored in many types of cancer. In this review, we report the immunoconjugates directed against OS surface antigens, considering the in vitro and in vivo studies. To date, several attempts have been made in preclinical settings, reporting encouraging results and demonstrating the validity of the idea. The clinical experience with glembatumumab vedotin may provide new insights into the real efficacy of antibody-drug conjugates for OS therapy, possibly giving more information about patient selection. Moreover, new opportunities could arise from the ongoing clinical trials in OS patients with unconjugated antibodies that could represent future candidates as carrier moieties of immunoconjugates.

Xanthine Oxidoreductase in Drug Metabolism: Beyond a Role as a Detoxifying Enzyme

The enzyme xanthine oxidoreductase (XOR) catalyzes the last two steps of purine catabolism in the highest uricotelic primates. XOR is an enzyme with dehydrogenase activity that, in mammals, may be converted into oxidase activity under a variety of pathophysiologic conditions. XOR activity is highly regulated at the transcriptional and post-translational levels and may generate reactive oxygen and nitrogen species, which trigger different consequences, ranging from cytotoxicity to inflammation. The low specificity for substrates allows XOR to metabolize a number of endogenous metabolites and a variety of exogenous compounds, including drugs.

The present review focuses on the role of XOR as a drug-metabolizing enzyme, specifically for drugs with anticancer, antimicrobial, antiviral, immunosuppressive or vasodilator activities, as well as drugs acting on metabolism or inducing XOR expression.

XOR has an activating role that is essential to the pharmacological action of quinone drugs, cyadox, antiviral nucleoside analogues, allopurinol, nitrate and nitrite. XOR activity has a degradation function toward thiopurine nucleotides, pyrazinoic acid, methylxanthines and tolbutamide, whose half-life may be prolonged by the use of XOR inhibitors.

In conclusion, to avoid potential drug interaction risks, such as a toxic excess of drug bioavailability or a loss of drug efficacy, caution is suggested in the use of XOR inhibitors, as in the case of hyperuricemic patients affected by gout or tumor lysis syndrome, when it is necessary to simultaneously administer therapeutic substances that are activated or degraded by the drug-metabolizing activity of XOR.

Hyperuricaemia, Xanthine Oxidoreductase and Ribosome-Inactivating Proteins from Plants: The Contributions of Fiorenzo Stirpe to Frontline Research

The enzymes called ribosome-inactivating proteins (RIPs) that are able to depurinate nucleic acids and arrest vital cellular functions, including protein synthesis, are still a frontline research field, mostly because of their promising medical applications. The contributions of Stirpe to the development of these studies has been one of the most relevant. After a short biographical introduction, an overview is offered of the main results obtained by his investigations during last 55 years on his main research lines: hyperuricaemia, xanthine oxidoreductase and RIPs.

Ribosome-Inactivating Proteins from Plants: A Historical Overview

This review provides a historical overview of the research on plant ribosome-inactivating proteins (RIPs), starting from the first studies at the end of eighteenth century involving the purification of abrin and ricin, as well as the immunological experiments of Paul Erlich. Interest in these plant toxins was revived in 1970 by the observation of their anticancer activity, which has given rise to a large amount of research contributing to the development of various scientific fields. Biochemistry analyses succeeded in identifying the enzymatic activity of RIPs and allowed for a better understanding of the ribosomal machinery. Studies on RIP/cell interactions were able to detail the endocytosis and intracellular routing of ricin, thus increasing our knowledge of how cells handle exogenous proteins. The identification of new RIPs and the finding that most RIPs are single-chain polypeptides, together with their genetic sequencing, has aided in the development of new phylogenetic theories. Overall, the biological properties of these proteins, including their abortifacient, anticancer, antiviral and neurotoxic activities, suggest that RIPs could be utilized in agriculture and in many biomedical fields, including clinical drug development.

Xanthine oxidoreductase in cancer: more than a differentiation marker

Human xanthine oxidoreductase (XOR) catalyzes the last two steps of purine catabolism and is present in two interconvertible forms, which may utilize O2 or NAD(+) as electron acceptors. In addition to uric acid, XOR products may comprise reactive oxygen and nitrogen species that have many biologic effects, including inflammation, endothelial dysfunction, and cytotoxicity, as well as mutagenesis and induction of proliferation. XOR is strictly modulated at the transcriptional and post-translational levels, and its expression and activity are highly variable in cancer. Xanthine oxidoreductase (XOR) expression has been negatively associated with a high malignity grade and a worse prognosis in neoplasms of the breast, liver, gastrointestinal tract, and kidney, which normally express a high level of XOR protein. However, the level of XOR expression may be associated with a worse outcome in cancer of low XOR-expressing cells, in relation to the inflammatory response elicited through the tissue damage induced by tumor growth. Xanthine oxidoreductase (XOR) has been implicated in the process of oncogenesis either directly because it is able to catalyze the metabolic activation of carcinogenic substances or indirectly through the action of XOR-derived reactive oxygen and nitrogen species. The role of uric acid is characterized by both oxidant and antioxidant action; thus, it is still debatable whether control of uricemia may be helpful to improve the outcomes of tumor illness.

Apoptosis and necroptosis induced by stenodactylin in neuroblastoma cells can be completely prevented through caspase inhibition plus catalase or necrostatin-1

BACKGROUND

Stenodactylin is a highly toxic plant lectin purified from the caudex of Adenia stenodactyla, with molecular structure, intracellular routing and enzyme activity similar to those of ricin, a well-known type 2 ribosome-inactivating protein. However, in contrast with ricin, stenodactylin is retrogradely transported not only in peripheral nerves but also in the central nervous system.

PURPOSE

Stenodactylin properties make it a potential candidate for application in neurobiology and in experimental therapies against cancer. Thus, it is necessary to better clarify the toxic activity of this compound.

STUDY DESIGN

We investigated the mechanism of stenodactylin-induced cell death in the neuroblastoma-derived cell line, NB100, evaluating the implications of different death pathways and the involvement of oxidative stress.

METHODS

Stenodactylin cytotoxicity was determined by evaluating protein synthesis and other viability parameters. Cell death pathways and oxidative stress were analysed through flow cytometry and microscopy. Inhibitors of apoptosis, oxidative stress and necroptosis were tested to evaluate their protective effect against stenodactylin cytotoxicity.

RESULTS

Stenodactylin efficiently blocked protein synthesis and reduced the viability of neuroblastoma cells at an extremely low concentration and over a short time (1 pM, 24 h). Stenodactylin induced the strong and rapid activation of apoptosis and the production of free radicals. Here, for the first time, a complete and long lasting protection from the lethal effect induced by a toxic type 2 ribosome-inactivating protein has been obtained by combining the caspase inhibitor Z-VAD-fmk, to either the hydrogen peroxide scavenger catalase or the necroptotic inhibitor necrostatin-1.

CONCLUSION

In respect to stenodactylin cytotoxicity, our results: (i) confirm the high toxicity to nervous cells, (ii) indicate that multiple cell death pathways can be induced, (iii) show that apoptosis is the main death pathway, (iv) demonstrate the involvement of necroptosis and (v) oxidative stress.

Protein synthesis inhibition activity by strawberry tissue protein extracts during plant life cycle and under biotic and abiotic stresses

Ribosome-inactivating proteins (RIPs), enzymes that are widely distributed in the plant kingdom, inhibit protein synthesis by depurinating rRNA and many other polynucleotidic substrates. Although RIPs show antiviral, antifungal, and insecticidal activities, their biological and physiological roles are not completely understood. Additionally, it has been described that RIP expression is augmented under stressful conditions. In this study, we evaluated protein synthesis inhibition activity in partially purified basic proteins (hereafter referred to as RIP activity) from tissue extracts of Fragaria × ananassa (strawberry) cultivars with low (Dora) and high (Record) tolerance to root pathogens and fructification stress. Association between the presence of RIP activity and the crop management (organic or integrated soil), growth stage (quiescence, flowering, and fructification), and exogenous stress (drought) were investigated. RIP activity was found in every tissue tested (roots, rhizomes, leaves, buds, flowers, and fruits) and under each tested condition. However, significant differences in RIP distribution were observed depending on the soil and growth stage, and an increase in RIP activity was found in the leaves of drought-stressed plants. These results suggest that RIP expression and activity could represent a response mechanism against biotic and abiotic stresses and could be a useful tool in selecting stress-resistant strawberry genotypes.

The role of settling velocity formulation in the determination of gully pot trapping efficiency: comparison between analytical and experimental data

Roadside gully pots are the connecting points between surface runoff and the underground drainage network; therefore they can be considered as the most superficial component of urban drainage systems. Gully pots are supposed to trap particulate matter washed off the catchment surface, but also to collect and convey stormwater into the network. The continuous accumulation of particulate matter results in a progressive loss of the gully pot hydraulic conveyance, thereby increasing the probability of urban flooding during rainstorm events. This study has therefore the objective to determine which variables influence the gully pot capability of retaining solids (efficiency), both experimentally and analytically. Several laboratory tests have been performed on a simple plastic gully pot, with different inflow rates and using both mono and hetero-disperse particle samples. Particular attention has been given to the influence exerted by the way particle settling velocity is expressed: efficiency has been analytically determined by means of multiple settling velocity formulas proposed by various authors and eventually compared to experimental data. Results deriving from the adoption of each single settling velocity formula have been extensively analysed, showing fairly different outcomes.

Endocytosis and intracellular localisation of type 1 ribosome-inactivating protein saporin-s6

Saporin-S6 is a single-chain ribosome-inactivating protein (RIP) that has low toxicity in cells and animals. When the protein is bound to a carrier that facilitates cellular uptake, the protein becomes highly and selectively toxic to the cellular target of the carrier. Thus, saporin-S6 is one of the most widely used RIPs in the preparation of immunoconjugates for anti-cancer therapy. The endocytosis of saporin-S6 by the neoplastic HeLa cells and the subsequent intracellular trafficking were investigated by confocal microscopy that utilises indirect immunofluorescence analysis and transmission electron microscopy that utilises a direct assay with gold-conjugated saporin-S6 and an indirect immunoelectron microscopy assay. Our results indicate that saporin-S6 was taken up by cells mainly through receptor-independent endocytosis. Confocal microscopy analysis showed around 30% co-localisation of saporin-S6 with the endosomal compartment and less than 10% co-localisation with the Golgi apparatus. The pathway identified by the immunofluorescence assay and transmission electron microscopy displayed a progressive accumulation of saporin-S6 in perinuclear vesicular structures. The main findings of this work are the following: i) the nuclear localisation of saporin-S6 and ii) the presence of DNA gaps resulting from abasic sites in HeLa nuclei after intoxication with saporin-S6.

Combined treatment of non-small cell lung cancer with synchronous brain metastases: a single center experience

AIM

The aim of this study was to analyze our experience with combined treatment of non-small cell lung cancer with synchronous brain metastases.

METHODS

Between 1992 and 2008, 31 patients were treated by performing neurosurgery (or stereotactic radiosurgery) and lung surgery. Patients were divided into two groups according to their preoperative mediastinal work-up: group A (CT scan) and group B (FDG-PET scan).

RESULTS

Twenty-six patients had one brain metastasis and five had two. Neurosurgery was performed in 10 patients, stereotactic radiosurgery in 20 and both approaches in 1. Seven patients underwent chemotherapy after cerebral procedure. Pulmonary resection was complete in 27 cases and incomplete in 4. Histological findings showed: adenocarcinoma in 19 cases, squamous cell carcinoma in 8 and large cell carcinoma in 4. All patients underwent adjuvant chemotherapy. Overall 1, 2 and 5-year survival rates were 83%, 47% and 21%, respectively. The median survival was 22 months. Univariate analysis showed a better prognosis for complete resection (P=0.008), adenocarcinomas (P=0.015), N0 disease (P=0.038), and Group B (P=0.045). Multivariate analysis showed that only the radicality of the resection (P=0.027) and Group B (P=0.047) were independent prognostic factors.

CONCLUSION

Our experience confirms that selected patients with non-small cell lung cancer and synchronous brain metastases may be effectively treated by combined therapy. Complete resection, adenocarcinoma histology and N0 disease were prognostic factors. The incorporation of FDG-PET scan into the preoperative work-up may translate into a survival benefit.

Immunotoxins and other conjugates containing saporin-s6 for cancer therapy

Ribosome-inactivating proteins (RIPs) are a family of plant toxins that permanently damage ribosomes and possibly other cellular substrates, thus causing cell death. RIPs are mostly divided in two types: Type 1 RIPs that are single-chain enzymatic proteins, and type 2 RIPs that consist of an active A chain (similar to a type 1 RIP) linked to a B chain with lectin properties. RIP-containing conjugates have been used in many experimental strategies against cancer cells, often showing great efficacy in clinical trials. Saporin-S6, a type 1 RIP extracted from Saponaria officinalis L. seeds, has been extensively utilized to construct anti-cancer conjugates because of its high enzymatic activity, stability and resistance to conjugation procedures, resulting in the efficient killing of target cells. This review summarizes saporin-S6-containing conjugates and their application in cancer therapy, considering in-vitro and in-vivo studies both in animal models and in clinical trials. The review is structured on the basis of the targeting of hematological versus solid tumors and on the antigen recognized on the cell surface.

Chiral Polyalkylthiophenes for Organic Light Emitting Diodes

Chiral polyalkylthiophenes are noncentrosymmetric organic materials which can be used both in second harmonic-generation devices and in polarized light emitting diodes. In this work we present the synthesis and the characterization of a polyalkylthiophene with a chiral center very close to the conjugated backbone: poly(3-[(S)-2-methylbutyl]thiophene) (PMBT). Circular dichroism (CD) measurements have been carried out to ascertain the chirality of these materials. The CD spectra show intense signals both in mixed solvents and in the solid state. The strong Cotton effect can be associated to a highly ordered aggregated phase whose nature is still under investigation. We also present the photo and electroluminescence characterization of single layer light emitting diode (LED) with the following configuration: ITO (Tin Indium Oxide)/PMBT/Al.

Increased serum level of xanthine oxidoreductase in liver transplanted patients

Xanthine oxidoreductase (XOR) leakage into serum has been observed in various types of liver pathology as well as after liver transplantation (LT). We determined the amount of XOR associated with LT to investigate the changes in serum enzyme level during the LT procedure and the post-operative period. Additionally, we examined whether there was any correlation between XOR levels and the surgical technique. XOR levels were measured by a competitive ELISA. In a first group of patients, the portal vein was flushed before the liver and systemic reperfusions, which occurred simultaneously. In the second group, the graft was flushed with blood from the portal vein before the systemic reperfusion. XOR showed a marked elevation in the caval effluent collected during LT and was higher compared to control serum levels at all time points that were examined after LT. The XOR levels during LT were also higher than samples taken pre-LT or from the portal blood flush before reperfusion. The XOR level was higher in Group 2 than in Group 1. Enhancement of the XOR serum level during LT was not derived from enterocytes, and it should be attributed to enzyme leakage from graft liver cells. We report the elevation of serum XOR during the three weeks following LT for the first time, as well as the influence of the graft reperfusion technique on XOR serum levels.

Toxicity and pollutant impact analysis in an urban river due to combined sewer overflows loads

The Navile Channel (Bologna, Italy) is an ancient artificial water course derived from the Reno river. It is the main receiving water body for the urban catchment of Bologna sewer systems and also for the Waste Water Treatment Plant (WWTP) main outlet. The aim of this work is to evaluate the Combined Sewer Overflows (CSOs) impact on Navile Channel's water quality. In order to collect Navile flow and water quality data in both dry and wet weather conditions, two measuring and sampling stations were installed, right upstream and downstream the WWTP outflow. The study shows that even in case of low intensity rain events, CSOs have a significant effect on both water quantity and quality, spilling a considerable amount of pollutants into the Navile Channel and presenting also acute toxicity effects. The collected data shown a good correlations between the concentrations of TSS and of chemical compounds analyzed, suggesting that the most part of such substances is attached to suspended solids. Resulting toxicity values are fairly high in both measuring points and seem to confirm synergistic interactions between heavy metals.