fThe generation of new antileishmanial drugs has become a priority. Selenium and its derivatives stand out as having promising leishmanicidal activity. In fact, some parasites express selenoproteins and metabolize selenium. Recently, selenium derivatives have shown the potential to reduce parasitemia, clinical manifestations, and mortality in parasite-infected mice. In this paper, after selecting four candidates according to drug similarity parameters, we observed that two of them, called compounds 2b [methyl-N,N=-di(thien-2-ylcarbonyl)-imidoselenocarbamate] and 4b [methyl-N,N=-di(5-nitrothien-3-ylcarbonyl)-imidoselenocarbamate], exhibit low 50% inhibitory concentrations (IC 50 s) (<3 M) and good selectivity indexes (SIs) (>5) in Leishmania major promastigotes and lack toxicity on macrophages. In addition, in analysis of their therapeutic potential against L. major in vitro infection, both compounds display a dramatic reduction of amastigote burden (ϳ80%) with sublethal concentrations. Furthermore, in macrophages, these selenocompounds induce nitric oxide production, which has been described to be critical for defense against intracellular pathogens. Compounds 2b and 4b were demonstrated to cause cell cycle arrest in G 1 . Interestingly, evaluation of expression of genes related to proliferation (PCNA), treatment resistance (ABC transporter and alpha-tubulin), and virulence (quinonoid dihydropteridine reductase [QDPR]) showed several alterations in gene expression profiling. All these results prompt us to propose both compounds as candidates to treat leishmanial infections.

Medulloblastoma is one of the most frequent and aggressive tumors of childhood. The Sonic hedgehog (Shh) pathway, related to human development, is altered in most medulloblastomas: genes like Ptch, Smo, or Sufu suffer mutations in 15% to 25% of these tumors. We tested Shh inhibition in the Daoy medulloblastoma cell line by two methods: a molecular one (direct Gli1 siRNA inhibition); and a pharmacological inhibition of Smo, upstream of Gli1, by cyclopamine. Afterwards, a comparison of cellular and molecular responses was done. We proved that MTT cell viability, and cell migration assessed by the scratching assay decreased after Shh inhibition. Furthermore, colony formation assay in culture decreased by 70%, and colony formation assay in soft agar decreased up to 90% when Shh inhibition was applied. As a whole, Shh inhibition conferred a less in vitro tumorigenic status to Daoy cells. Moreover, we assessed the expression of different Gli1 target genes and other genes, before and after Shh inhibition, and found that Shh shows a crosstalk with oncogenes and tumor suppressor genes that have been described in numerous tumors. Therefore, we found downregulation of Ptch1, Cyclin D2, Plakoglobin, Nkx2.2, Bmi1, Smo and N-myc after Shh inhibition. Sufu and Gli3 showed parallel results, where Gli1 siRNA did neither decrease nor increase expression of both genes, whereas cyclopamine reduced them in 15-25%. Pax6 mRNA levels were upregulated by either Gli1 siRNA or cyclopamine. Finally, Notch1 was upregulated after inhibition of Shh, while Notch2 showed contrasting results, as siRNA inhibition decreased its expression, while cyclopamine increased it. All these experiments give an overview of the Shh pathway in medulloblastoma, its relationship with other genes, and the demonstration of the efficacy of cyclopamine and Gli 1 siRNA Shh inhibition in vitro. Citation Format: R Garcia-Lopez, B Vera-Cano, A Vacas-Oleas, J de la Rosa, G Gallo-Oller, M H. Shahi, X Fan, M M. Alonso, J A. Rey, Javier S. Castresana. Sonic hedgehog inhibition reduces in vitro tumorigenesis and alters expression of GLI1-target genes in a desmoplastic medulloblastoma cell line. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5053. doi:10.1158/1538-7445.AM2013-5053

Leishmaniasis is a neglected tropical disease caused by Leishmania spp. The improvement of existing treatments and the discovery of new drugs remain ones of the major goals in control and eradication of this disease. From the parasite genome, we have identified the homologue of the human oncogene PES1 in Leishmania major (LmjPES). It has been demonstrated that PES1 is involved in several processes such as ribosome biogenesis, cell proliferation and genetic transcription. Our phylogenetic studies showed that LmjPES encodes a highly conserved protein containing three main domains: PES N-terminus (shared with proteins involved in ribosomal biogenesis), BRCT (found in proteins related to DNA repair processes) and MAEBL-type domain (C-terminus, related to erythrocyte invasion in apicomplexan). This gene showed its highest expression level in metacyclic promastigotes, the infective forms; by fluorescence microscopy assay, we demonstrated the nuclear localization of LmjPES protein. After generating mutant parasites overexpressing LmjPES, we observed that these clones displayed a dramatic increase in the ratio of cell infection within macrophages. Furthermore, BALB/c mice infected with these transgenic parasites exhibited higher footpad inflammation compared to those inoculated with non-overexpressing parasites.

A novel serine/threonine protein kinase, LmjF.22.0810, was recently described in Leishmania major. After generating an L. major cell line overexpressing LmjF.22.0810 (named LmJ3OE), the ability of this novel protein to modulate the Th2-type immune response was analyzed. Our results suggest that the protein kinase LmjF.22.0810 might be involved in leishmaniasis outcomes. Indeed, our study outlined the LmJ3OE parasites infectivity in vitro and in vivo. Transgenic parasites displayed lower phagocytosis rates in vitro, and their promastigote forms exhibited lower expression levels of virulence factors compared to their counterparts in control parasites. In addition, LmJ3OE parasites developed significantly smaller footpad swelling in susceptible BALB/c mice. Hematoxylin–eosin staining allowed the observation of a lower inflammatory infiltrate in the footpad from LmJ3OE-infected mice compared to animals inoculated with control parasites. Gene expression of Th2-associated cytokines and effectors revealed a dramatically lower induction in interleukin (IL)-4, IL-10, and arginase 1 (ARG1) mRNA levels at the beginning of the swelling; no expression change was found in Th1-associated cytokines except for IL-12. Accordingly, such results were validated by immunohistochemistry studies, illustrating a weaker expression of ARG1 and a similar induction for inducible NO synthase (iNOS) in footpads from LmJ3OE-infected mice compared to control L. major infected animals. Furthermore, the parasite burden was lower in footpads from LmJ3OE-infected mice. Our analysis indicated that such significant smaller footpad swellings might be due to an impairment of the Th2 immune response that subsequently benefits Th1 prevalence. Altogether, these studies depict LmjF.22.0810 as a potential modulator of host immune responses to Leishmania. Finally, this promising target might be involved in the modulation of infection outcome.

The identification and clarification of the mechanisms of action of drugs used against leishmaniasis may improve their administration regimens and prevent the development of resistant strains. Herein, for the first time, we describe the structure of the putatively essential Ser/Thr kinase LmjF.22.0810 from Leishmania major. Molecular dynamics simulations were performed to assess the stability of the kinase model. The analysis of its sequence and structure revealed two druggable sites on the protein. Furthermore, in silico docking of small molecules showed that aminoglycosides preferentially bind to the phosphorylation site of the protein. Given that transgenic LmjF.22.0810-overexpressing parasites displayed less sensitivity to aminoglycosides such as paromomycin, our predicted models support the idea that the mechanism of drug resistance observed in those transgenic parasites is the tight binding of such compounds to LmjF.22.0810 associated with its overexpression. These results may be helpful to understand the complex machinery of drug response in Leishmania.

The cancer stem cells (CSC) hypothesis is currently the most widely accepted theory regarding tumor formation and self-renewal ability. The need to find pharmacological compounds or biological agents capable of eliminating CSC makes the search for methods of recognition and isolation of these cells a matter of great urgency. The aim of the study was to separate CD133+ and CD133-cell subpopulations from the U87MG glioblastoma cell line by magnetic activated cell sorting (MACS), and to analyze the tumorigenic and stem cell differences among four sets of cells: the cell line grown in serum (monolayer group), the neurospheres of the same cell line, and the CD133+ and CD133-sorted cell fractions from the neurospheres.

Leishmania is the causative agent of leishmaniasis, a neglected tropical disease that affects more than 12 million people around the world. Current treatments are toxic and poorly effective due to the acquisition of resistance within Leishmania populations. Thus, the pursuit for new antileishmanial drugs is a priority. The available methods for drug screening based on colorimetric assays using vital dyes are time-consuming. Currently, the use of fluorescent reporter proteins is replacing the use of viability indicator dyes. We have constructed two plasmids expressing the red fluorescent protein mCherry with multiple cloning sites (MCS), adequate for N- and C-terminal fusion protein constructs. Our results also show that the improved pXG-mCherry plasmid can be employed for drug screening in vitro. The use of the red fluorescent protein, mCherry, is an easier tool for numerous assays, not only to test pharmacological compounds, but also to determine the subcellular localization of proteins.

The cancer stem cells (CSC) hypothesis is nowadays the most widely accepted theory regarding tumor formation and self-renewal capacity. It states that one of the different tumorigenic phenotypes inside a tumor mass is capable of generating new tumors if transplanted onto a host and it is able to self-generate and regenerate the rest of the tumor cells. The necessity to find pharmacological compounds or biological agents capable of eliminating CSC makes the search for methods of recognition and isolation of these cells a matter of great urgency. Our working hypothesis is that the selection of cancer cells with the CD133 marker and their subsequent isolation and characterization will allow us to assess the capacity of the different CD133 subpopulations as CSC. The aim of the study was to separate CD133+ and CD133- cell subpopulations from the U87MG glioblastoma cell line by magnetic activated cell sorting (MACS), and to analyze the tumorigenic and stem cell differences among four sets of cells: the cell line grown in serum (monolayer group), the neurospheres of the same cell line, and the CD133+ and CD133- sorted cell fractions from the neurospheres. Our results showed that the neurospheres and the CD133+ cells overexpressed stem cell marker genes like SOX2, Nestin, Musashi1 and CD133, and formed more colonies in soft agar than the cell groups with less CD133 expression (monolayer and CD133- group). On the other hand the CD133- and the monolayer groups had similar expression levels of CD133, while the CD133- cells expressed higher levels of Nestin, SOX2 and Musashi1 than the monolayer cells. Besides, cell migration assessed by the scratching test showed that the CD133- and the monolayer cells migrated more than the neurospheres and the CD133+ cells. Moreover, the CD133- cells had a higher proliferation rate than the CD133+ cells and the neurospheres, being all these three groups cultured in the medium for neurospheres. In conclusion, we might point to the presence of CSC in the CD133- group, as previously suggested by others. Then, CD133+ cells are not necessarily equivalent to CSC. Maybe CD133+ cells present a higher probability of including CSC than CD133- do. Therefore, further functional and genetic analyses must be performed to reach an optimal isolation of CSC. Citation Format: A Vacas-Oleas, J de la Rosa, R Garcia-Lopez, B Vera-Cano, G Gallo-Oller, M Alfaro, M H. Shahi, X Fan, I J. Encio, J A. Rey, Javier S. Castresana. In vitro tumorigenicity and stemness characterization of the U87MG glioblastoma cell line: Monolayer cultures, neurospheres, and CD133+ and CD133- sorted fractions. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 257. doi:10.1158/1538-7445.AM2013-257