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Destruction of cells by irradiation-induced radical formation is one of the most frequent interventions in cancer therapy. An alternative to irradiation-induced radical formation is in principle drug-induced formation of radicals, and the formation of toxic metabolites by enzyme catalyzed reactions. Thus, combination therapy targeting polyamine metabolism could represent a promising strategy to fight hyper-proliferative disease. The aim of this work is to discuss and evaluate whether the presence of a DNA damage provoked by enzymatic ROS overproduction may act as an additive or adaptive response upon radiation and combination of hyperthermia with lysosomotropic compounds may improve the cytocidal effect of polyamines oxidation metabolites. Low level of X-irradiations delivers challenging dose of damage and an additive or adaptive response with the chronic damage induced by spermine oxidase overexpression depending on the deficiency of the DNA repair mechanisms. Since reactive oxygen species lead to membrane destabilization and cell death, we discuss the effects of BSAO and spermine association in multidrug resistant cells that resulted more sensitive to spermine metabolites than their wild-type counterparts, due to an increased mitochondrial activity. Since mammal spermine oxidase is differentially activated in a tissue specific manner, and cancer cells can differ in term of DNA repair capability, it could be of interest to open a scientific debate to use combinatory treatments to alter spermine metabolism and deliver differential response. © 2013 Springer-Verlag.

International audience; The most frequent interventions in cancer therapy are currently the destruction of cells by irradiation or administration of drugs both able to induce radical formation and toxic metabolites by enzyme-catalyzed reactions. The aim of this study was to determine the cell viability of cells undergoing a DNA damage threshold accomplished by ROS overproduction via both ectopic expression of murine spermine oxidase (mSMOX) and bovine serum amine oxidase (BSAO) enzymes. Low dose of X-irradiation delivers a challenging dose of damage as evaluated in proficient Chinese hamster AA8 cell line and both deficient transcription-coupled nucleotide excision repair (NER) UV61 cells and deficient base excision repair (BER) EM9 cells, at 6 and 24 h after exposure. The priming dose of ROS overexposure by mSMOX provokes an adaptive response in N18TG2, AA8 and EM9 cell lines at 24 h. Interestingly, in the UV61 cells, ROS overexposure by mSMOX delivers an earlier adaptive response to radiation. The enzymatic formation of toxic metabolites has mainly been investigated on wild-type (WT) and multidrug-resistant (MDR) cancer cell lines, using and spermine as substrate of the BSAO enzyme. MDR cells are more sensitive to the toxic polyamine metabolites than WT cells, thus indicating a new therapeutic strategy to overcome MDR tumors. Since SMOX in mammals is differentially activated in a tissue-specific manner and cancer cells can differ in terms of DNA repair and MDR capabilities, it could be of interest to simultaneously treat with very low dose of X-rays and/or to alter SMOX metabolism to generate a differential response in healthy and cancer tissues.

Background Meloidae (blister beetles) are known to synthetize cantharidin (CA), a toxic and defensive terpene mainly stored in male accessory glands (MAG) and emitted outward through reflex-bleeding. Recent progresses in understanding CA biosynthesis and production organ(s) in Meloidae have been made, but the way in which self-protection is achieved from the hazardous accumulation and release of CA in blister beetles has been experimentally neglected. To provide hints on this pending question, a comparative de novo assembly transcriptomic approach was performed by targeting two tissues where CA is largely accumulated and regularly circulates in Meloidae: the male reproductive tract (MRT) and the haemolymph. Differential gene expression profiles in these tissues were examined in two blister beetle species, Lydus trimaculatus (Fabricius, 1775) (tribe Lyttini) and Mylabris variabilis (Pallas, 1781) (tribe Mylabrini). Upregulated transcripts were compared between the two species to identify conserved genes possibly involved in CA detoxification and transport. Results Based on our results, we hypothesize that, to avoid auto-intoxication, ABC, MFS or other solute transporters might sequester purported glycosylated CA precursors into MAG, and lipocalins could bind CA and mitigate its reactivity when released into the haemolymph during the autohaemorrhaging response. We also found an over-representation in haemolymph of protein-domains related to coagulation and integument repairing mechanisms that likely reflects the need to limit fluid loss during reflex-bleeding. Conclusions The de novo assembled transcriptomes of L. trimaculatus and M. variabilis here provided represent valuable genetic resources to further explore the mechanisms employed to cope with toxicity of CA in blister beetle tissues. These, if revealed, might help conceiving safe and effective drug-delivery approaches to enhance the use of CA in medicine.

Blister beetles owe their name to their ability to release cantharidin, a blistering terpene, the highest concentration of which is retained in male accessory glands. The anatomy and ultrastructure of the three pairs of male reproductive accessory glands and the glandular region of the two vasa deferentia of Meloe proscarabaeus were investigated using light, electron and ion beam microscopy. All of the mesodermal glands here analysed share a common structural organization with an outer muscular layer and an inner glandular epithelium facing a broad lumen in which the secretory products are released. Developed rough endoplasmic reticulum, Golgi systems, abundant mitochondria, numerous secretory vesicles and a microvillated apical membrane are commonly found in the cells of different glandular epithelia, suggesting that all accessory gland pairs as well as the vasa deferentia are involved in an active synthesis. Nevertheless, each pair of glands appears specialized in the production of a specific set of substances, as suggested by the peculiarities in cellular ultrastructure and by the different aspect of the secretions stored in their glandular lumen. The above cited features of male accessory glands of M. proscarabaeus are compared with those of other beetles and some hints on their potential role in producing and/or concentrating cantharidin are provided.

Several studies have demonstrated high polyamine levels in brain diseases such as epilepsy. Epilepsy is the fourth most common neurological disorder and affects people of all ages. Excitotoxic stress has been associated with epilepsy and it is considered one of the main causes of neuronal degeneration and death. The transgenic mouse line Dach-SMOX, with CD1 background, specifically overexpressing spermine oxidase in brain cortex, has been proven to be highly susceptible to epileptic seizures and excitotoxic stress induced by kainic acid. In this study, we analysed the effect of spermine oxidase over-expression in a different epileptic model, pentylenetetrazole. Behavioural evaluations of transgenic mice compared to controls showed a higher susceptibility towards pentylentetrazole. High-performance liquid chromatography analysis of transgenic brain from treated mice revealed altered polyamine content. Immunoistochemical analysis indicated a rise of 8-oxo-7,8-dihydro-2′-deoxyguanosine, demonstrating an increase in oxidative damage, and an augmentation of system xc− as a defence mechanism. This cascade of events can be initially linked to an increase in protein kinase C alpha, as shown by Western blot. This research points out the role of spermine oxidase, as a hydrogen peroxide producer, in the oxidative stress during epilepsy. Moreover, Dach-SMOX susceptibility demonstrated by two different epileptic models strongly indicates this transgenic mouse line as a potential animal model to study epilepsy.

Neuroblastoma (NB) is a heterogeneous extra‑cranial childhood type of cancer, responsible for approximately15% of all paediatric cancer‑related deaths. Although several critical genetic aberrations have been related to NB, only a few established molecular markers have been associated with prognosis [V‑myc avian myelocytomatosis viral oncogene(MYCN) locus amplification, deletions of part of chromosome1p, 11q23 and gain of 17q]. Regrettably, direct evidence of NB‑related tumour suppressors or oncogenes has not been currently identified at these chromosomal regions. MYCN locus amplification is present in approximately 20‑30% of cases and is associated with a poor clinical outcome, representing the most important genetic prognostic marker. The functional guidelines for the prognosis of NB identify high‑risk patients (

Background Polyamine metabolism has a critical role in cell death and proliferation representing a potential target for intervention in breast cancer (BC). This study investigates the expression of spermine oxidase (SMO) and its prognostic significance in BC. Biochemical analysis of Spm analogues BENSpm and CPENSpm, utilized in anticancer therapy, was also carried out to test their property in silico and in vitro on the recombinant SMO enzyme. Methods BC tissue samples were analyzed for SMO transcript level and SMO activity. Student's t test was applied to evaluate the significance of the differences in value observed in T and NT samples. The structure modeling analysis of BENSpm and CPENSpm complexes formed with the SMO enzyme and their inhibitory activity, assayed by in vitro experiments, were examined. Results Both the expression level of SMO mRNA and SMO enzyme activity were significantly lower in BC samples compared to NT samples. The modeling of BENSpm and CPENSpm complexes formed with SMO and their inhibition properties showed that both were good inhibitors. Conclusions This study shows that underexpression of SMO is a negative marker in BC. The SMO induction is a remarkable chemotherapeutical target. The BENSpm and CPENSpm are efficient SMO inhibitors. The inhibition properties shown by these analogues could explain their poor positive outcomes in Phases I and II of clinical trials.

The natural polyamines (PA), putrescine (PUT), spermidine (SPD) and spermine (SPM) are ubiquitous constituents of eukaryotic cells. The increase of PA in malignant and proliferating cells attracted the interest of scientists during last decades, addressing PA depletion as a new strategy to inhibit cell growth. Selective enzyme inhibitors were developed for decreasing PA metabolism and to act as chemotherapeutic anticancer agents. Indeed, the complexity of the PA homoeostasis overcomes the PA perturbation by a single enzyme to take effect therapeutically. Recently, an increasing interest has been posed on spermine-oxidase (SMO), the only catabolic enzyme able to specifically oxidise SPM. Interestingly, the absence of SPM is compatible with life, but its accumulation and degradation is lethal. Augmented SMO activity provokes an oxidative stress rendering cells prone to die, and appears to be important in the cell differentiation pathway. Extra-cellular SPM is cytotoxic, but its analogues are capable of inhibiting cell growth at low concentrations, most likely by intracellular SPM depletion. These pivotal roles seem to evoke the biological processes of stress response, wherein balance is mandatory to live or to die. Thus, altering SPM metabolism could allow a multi-tasking therapeutic strategy, addressed not only to inhibit PA metabolism. Several tetramines are presently in early phases (I and II) of clinical trials, and it will be a matter of a few more years to understand whether SPM-related therapeutic approaches would be of benefit for composite treatment protocols of cancer.

Spermine oxidase (SMO) is a FAD-containing enzyme involved in animal cell polyamines (PA) homeostasis, selectively active on spermine and producing H2O2, spermidine, and the 3-aminopropanal. In the present study, we have examined the SMO gene expression during the mouse myoblast C2C12 cell differentiation induced with two different stimuli by RT-PCR analysis, polysome-mRNP distribution and enzyme activity. SMO transcript accumulation and enzymatic activity increases during C2C12 cell differentiation and correlates with the decrease of spermine content. Many proteins are highly regulated during the phenotypic conversion of rapidly dividing C2C12 myoblasts into fully differentiated post-mitotic myotubes. The SMO gene induction represents a novel and additional marker of C2C12 cell differentiation. The sub-cellular localization of the SMOα and SMOμ splice variants is not involved in the differentiation processes. Nuclear localization of only the SMOμ protein was confirmed.