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High-risk neuroblastoma (HR-NB) still remains the most dangerous tumor in early childhood. For this reason, the identification of new therapeutic approaches is of fundamental importance. Recently, we combined the conventional pharmacological approach to NB, represented by cisplatin, with fendiline hydrochloride, an inhibitor of several transporters involved in multidrug resistance of cancer cells, which demonstrated an enhancement of the ability of cisplatin to induce apoptosis. In this work, we co-administrated acetazolamide, a carbonic anhydrase isoform IX (CAIX) inhibitor which was reported to increase chemotherapy efficacy in various cancer types, to the cisplatin/fendiline approach in SKNBE2 xenografts in NOD-SCID mice with the aim of identifying a novel and more effective treatment. We observed that the combination of the three drugs increases more than twelvefold the differences in the cytotoxic activity of cisplatin alone, leading to a remarkable decrease of the expression of malignancy markers. Our conclusion is that this approach, based on three FDA-approved drugs, may constitute an appropriate improvement of the pharmacological approach to HR-NB.

Volume regulated anion channels (VRACs) are ubiquitously expressed in all vertebrate cells. Despite many years of research, the fundamental mechanisms underlying VRAC activation are not understood. The recent molecular identification of the LRRC8 genes underlying VRAC revealed that VRACs are formed by a hexameric assembly of members of the LRRC8 gene family. Knowing the genes underlying VRACs allowed the discovery of novel VRAC functions into cell volume regulation, and first structure function studies revealed important insight in channel activation mechanisms. The determination of cryo-EM structures of homomeric LRRC8A and LRRC8D complexes provide a framework for a rational approach to investigate biophysical mechanisms. We discuss several recent advances within the structural framework, and we critically review the literature on the main mechanisms proposed to be involved in VRAC activation, including low intracellular ionic strength, membrane unfolding, oxidation, phosphorylation and G-protein coupling.

Tumor microenvironments are often characterized by an increase in oxidative stress levels. We studied the response to oxidative stimulation in human primary (IGR39) or metastatic (IGR37) cell lines obtained from the same patient, performing patch-clamp recordings, intracellular calcium ([Ca2+]i) imaging, and RT-qPCR gene expression analysis. In IGR39 cells, chloramine-T (Chl-T) activated large K+ currents (KROS) that were partially sensitive to tetraethylammonium (TEA). A large fraction of KROS was inhibited by paxilline—a specific inhibitor of large-conductance Ca2+-activated BK channels. The TEA-insensitive component was inhibited by senicapoc—a specific inhibitor of the Ca2+-activated KCa3.1 channel. Both BK and KCa3.1 activation were mediated by an increase in [Ca2+]i induced by Chl-T. Both KROS and [Ca2+]i increase were inhibited by ACA and clotrimazole—two different inhibitors of the calcium-permeable TRPM2 channel. Surprisingly, IGR37 cells did not exhibit current increase upon the application of Chl-T. Expression analysis confirmed that the genes encoding BK, KCa3.1, and TRPM2 are much more expressed in IGR39 than in IGR37. The potassium currents and [Ca2+]i increase observed in response to the oxidizing agent strongly suggest that these three molecular entities play a major role in the progression of melanoma. Pharmacological targeting of either of these ion channels could be a new strategy to reduce the metastatic potential of melanoma cells, and could complement classical radio- or chemotherapeutic treatments.

Despite significant improvement of neuroblastoma (NB) patients&rsquo, survival due to recent treatment advancements in recent years, NB is still associated with high mortality rate. In search of novel strategies to increase NB&rsquo, s susceptibility to pharmacological treatments, we investigated the in vitro and in vivo effects of fendiline hydrochloride as an enhancer of cisplatin antitumor activity. To assess the modulation of fendiline treatment on cisplatin responses, we used in vitro (evaluating NB cell proliferation by XCELLigence technology and colony formation, and gene expression by RT-PCR) and in vivo (NB cell grafts in NOD-SCID mice) models of NB. NB cell treatment with fendiline induced the expression of the ncRNA NDM29, leading to cell differentiation and to the reduction of the expression of MDRs/ABC transporters linked to multidrug resistance. These events were correlated to higher NB cell susceptibility to cisplatin and, consequently, increased its cytotoxic potency. In vivo, this drug interaction causes an enhanced ability of cisplatin to induce apoptosis in NB masses, resulting in tumor growth reduction and prolonged animal survival rate. Thus, the administration of fendiline might be a possible novel therapeutic approach to increase cisplatin efficacy in aggressive and poorly responsive NB cases.

To overcome the lack of effective pharmacological treatments for high-risk neuroblastoma (HR-NB), the development of novel in vitro and in vivo models that better recapitulate the disease is required. Here, we used an in vitro multiclonal cell model encompassing NB cell differentiation stages, to identify potential novel pharmacological targets. This model allowed us to identify, by low-density RT-PCR arrays, two gene sets, one over-expressed during NB cell differentiation, and the other up-regulated in more malignant cells. Challenging two HR-NB gene expression datasets, we found that these two gene sets are related to high and low survival, respectively. Using mouse NB cisplatin-treated xenografts, we identified two genes within the list associated to the malignant stage (MCM2 and carbonic anhydrase 9), whose expression is positively correlated with tumor growth. Thus, we tested their pharmacological targeting as potential therapeutic strategy. We measured mice survival and tumor growth rate after xenografts of human NB treated with cisplatin in the presence of MCM2/carbonic anhydrase 9 inhibitors (ciprofloxacin and acetazolamide). MCM2 or carbonic anhydrase 9 inhibition significantly increased cisplatin activity, supporting their possible testing for NB therapy.

The sodium channel β1 subunit is non-covalently associated with the pore-forming α-subunits, and has been proposed to act as a modulator of channel activity, regulator of channel cell surface expression and cell adhesion molecule. Its importance is evident since mutations of the β1 subunit cause neurologic and cardiovascular disorders. The first described β1 subunit mutation is the C121W, that is related to generalized epilepsy with febrile seizures plus (GEFS+), a childhood genetic epilepsy syndrome. This mutation changed a conserved cysteine residue in position 121 into a tryptophan, putatively disrupting a disulfide bridge that should normally maintain the β1 extracellular immunoglobulin-like fold. Using the 2-D-diagonal-SDS–PAGE technique, we demonstrated the existence of this putative disulfide bridge in the Ig-like extracellular domain of the β1 subunit and its disruption in the epileptogenic C121W mutant.

The P2X(7) receptor (P2X(7)R) is an ATP-gated cation channel whose biophysical properties remain to be unravelled unequivocally. Its activity is modulated by divalent cations and organic messengers such as arachidonic acid (AA). In this study, we analysed the differential modulation of magnesium (Mg(2+)) and AA on P2X(7)R by measuring whole-cell currents and intracellular Ca(2+) ([Ca(2+)](i)) and Na(+) ([Na(+)](i)) dynamics in HEK293 cells stably expressing full-length P2X(7)R and in cells endowed with the P2X(7)R variant lacking the entire C-terminus tail (trP2X(7)R), which is thought to control the pore activation. AA induced a robust potentiation of the P2X(7)R- and trP2X(7)R-mediated [Ca(2+)](i) rise but did not affect the ionic currents in both conditions. Extracellular Mg(2+) reduced the P2X7R- and trP2X(7)R-mediated [Ca(2+)](i) rise in a dose-dependent manner through a competitive mechanism. The modulation of the magnitude of the P2X(7)R-mediated ionic current and [Na(+)](i) rise were strongly dependent on Mg(2+) concentration but occurred in a non-competitive manner. In contrast, in cells expressing the trP2X(7)R, the small ionic currents and [Na(+)](i) signals were totally insensitive to Mg(2+). Collectively, these results support the tenet of a functional structure of P2X(7)R possessing at least two distinct conductive pathways one for Ca(2+) and another for monovalent ions, with the latter which depends on the presence of the receptor C-terminus.

The presynaptic P2X7 receptor (P2X7R) plays an important role in the modulation of transmitter release. We recently demonstrated that, in nerve terminals of the adult rat cerebral cortex, P2X7R activation induced Ca2+-dependent vesicular glutamate release and significant Ca2+-independent glutamate efflux through the P2X7R itself. In the present study, we investigated the effect of the new selective P2X7R competitive antagonist 3-(5-(2,3-dichlorophenyl)-1H-tetrazol-1-yl)methyl pyridine (A-438079) on cerebrocortical terminal intracellular calcium (intrasynaptosomal calcium concentration;[Ca2+]i signals and glutamate release, and evaluated whether P2X7R immunoreactivity was consistent with these functional tests. A-438079 inhibited functional responses. P2X7R immunoreactivity was found in about 45% of cerebrocortical terminals, including glutamatergic and non-glutamatergic terminals. This percentage was similar to that of synaptosomes showing P2X7R-mediated [Ca2+]i signals. These findings provide compelling evidence of functional presynaptic P2X7R in cortical nerve terminals.

Summary Activation of the oxidative burst and failure of CD4+CD25+ cell regulation have been implicated in idiopathic nephrotic syndrome (iNS). The intimate mechanism is, however, unknown and requires specifically focused studies. We investigated reactive oxygen species (ROS) generation [di-chlorofluorescein-diacetate (DCFDA)] fluorescence assay and the regulatory adenosine 5′-triphosphate (ATP) pathways in the blood of 41 children with iNS, utilizing several agonists and antagonists of nucleotide/nucleoside receptors, including the addition of soluble apyrase. The CD4+CD25+CD39+/CD73+ expression was determined in vivo in parallel during disease activity. Overall, we found that the percentage of CD39+CD4+CD25+ was reduced markedly in iNS by 80% (3·43 ± 0·04% versus 13·14 ± 0·07% of total lymphocytes, P

In this article we show that the cytidine analog 5-azacytidine is able to induce differentiation of the human leukemia K-562 cell line. Erythroid induction is associated with (a) an increase of the overall globin synthesis and globin mRNA accumulation, (b) a relative increase of fetal with respect to embryonic globins, and (c) a decrease of the proliferative capacity of hemoglobin-containing cells. In addition, we have analysed the DNA methylation pattern at the cleavage sites of MspI and HpaII restriction enzymes, which are known to cleave differently CCGG DNA sequences when 5-methylcytosine is present. These experiments indicate that in K-562 cells treated with 5-azacytidine, DNA becomes hypomethylated, suggesting that genetic programmes leading to an erythroid phenotype may be activated by a reduction of DNA methylation.