Einfluss der Glyoxalase 1 und ihres Inhibitors Curcumin auf Malignitätskriterien in ausgewählten Tumorentitäten

Trotz intensiver Forschung stellen bis heute maligne Tumorerkrankungen die zweithäufigste Todesursache in Industrienationen dar. Der Biochemiker Otto Warburg postulierte bereits vor 90 Jahren den nicht zu unterschätzenden Einfluss des Kohlenhydrat-Stoffwechsels in der malignen Entartung von Zellen. Als Nebenprodukt der Glykolyse entsteht das toxische Methylglyoxal, welches durch das nahezu ubiquitär vorkommende Glyoxalase-System neutralisiert werden kann. Speziell für die Glyoxalase 1 (Glo1) wird eine entscheidende Rolle in der Tumorgenese/-progression vermutet. In dieser Arbeit konnte basierend auf shRNA-vermittelten Glo1-knockdown Versuchen eine inhibitorische Rolle der Glo1 in der Ausbildung maligner Tumoreigenschaften wie Invasion, Migration und Proliferation in Astrozytomzellen gezeigt werden. Weiterhin wurde ein monoklonaler muriner Antikörper gegen die humane Isoform der Glo1 generiert und dessen Spezifität und Sensitivität bestätigt. Immunhistochemische Untersuchungen in primären Hirntumorgeweben offenbarten wiederum keine direkte Korrelation zwischen WHO-Stadium und Expressionsgrad bzw. subzellulärer Lokalisation der Glo1. Expressionsanalysen in malignen Tumorzelllinien unterschiedlicher Genese demonstrierten, dass besonders fortgeschrittene, therapieresistente Mamma- und Prostatakarzinomzellen niedrige Glo1-Level aufweisen. Basierend auf diesen Ergebnissen wurde ein zuvor identifizierter Inhibitor der Glo1 – das Phytotherapeutikum Curcumin – auf einen potentiellen Effekt in der Tumorprogression untersucht. Curcumin demonstrierte eine signifikante Reduktion der Proliferationsrate aller getesteter Tumorzelllinien. Darüber hinaus konnte ein in vivo -Tumormodell etabliert werden, mit welchem eine signifikante Tumorreduktion durch intraperitoneale und orale Applikation von Curcumin in Her-2/neu überexprimierenden Fibroblastenzellen erzielt wurde

Polyelectrolyte/Surfactant complexes (PESCs) – versatile self-assembled systems studied with respect to their structural, dynamical and rheological properties

Mixtures of oppositely charged polyelectrolyte and surfactant are very interesting systems, as they allow to control the structure and properties of the self-assembled complexes over a very wide range. In our investigations we concentrated on biopolymers such as chitosan, hyaluronic acid or cationically modified cellulose and their combination with biofriendly surfactants. We studied several such systems comprehensively by means of static and dynamic light scattering (SLS, DLS), small-angle neutron scattering (SANS), neutron spin-echo (NSE), and rheology, in order to deduce systematic relations between the composition of the systems (as mainly controlled by the mixing ratio surfactant/polyelectrolyte), the mesoscopic structure and the macroscopic flow behavior. For instance one can produce highly viscous complexes of locally rodlike structure already at concentrations below 1 wt% by having these mixed PESC structures highly interconnected [1]. An interesting observation here is that the local dynamics of the polyelectrolyte chains, as evidenced by NSE, is only little reduced despite an increase of viscosity by more than 4 orders of magnitude [2]. For example for chitosan in mixtures with anionic surfactants one finds a pronouncedly pH-dependent aggregation behavior [3]. An interesting SPEC structure are locally rod-like aggregates and densely packed micelles of alkylethoxy carboxylates in a chitosan matrix which can be present in globular or extended complexes, depending on the detailed composition of the system. This structural flexibility then was employed to use this system for selective separation of hydrophobic and hydrophilic organic compounds or sequestration of metal ions [4]. The local structure typically is determined by the surfactant self-assembly and for cases where the surfactant forms vesicles one can then have multilamellar vesicles (MLVs), where the number of lamellae is controlled by the amount of chitosan added (Fig. 1). Such MLVs are attractive for delivery purposes as they are fully composed of biocompatible components and their surface charge is controlled by the mixing ratio. Please click Additional Files below to see the full abstract

Ethyl pyruvate combats human leukemia cells but spares normal blood cells

Ethyl pyruvate, a known ROS scavenger and anti-inflammatory drug was found to combat leukemia cells. Tumor cell killing was achieved by concerted action of necrosis/apoptosis induction, ATP depletion, and inhibition of glycolytic and para-glycolytic enzymes. Ethyl lactate was less harmful to leukemia cells but was found to arrest cell cycle in the G0/G1 phase. Both, ethyl pyruvate and ethyl lactate were identified as new inhibitors of GSK-3β. Despite the strong effect of ethyl pyruvate on leukemia cells, human cognate blood cells were only marginally affected. The data were compiled by immune blotting, flow cytometry, enzyme activity assay and gene array analysis. Our results inform new mechanisms of ethyl pyruvate-induced cell death, offering thereby a new treatment regime with a high therapeutic window for leukemic tumors

GASZ Is Essential for Male Meiosis and Suppression of Retrotransposon Expression in the Male Germline

Nuage are amorphous ultrastructural granules in the cytoplasm of male germ cells as divergent as Drosophila, Xenopus, and Homo sapiens. Most nuage are cytoplasmic ribonucleoprotein structures implicated in diverse RNA metabolism including the regulation of PIWI-interacting RNA (piRNA) synthesis by the PIWI family (i.e., MILI, MIWI2, and MIWI). MILI is prominent in embryonic and early post-natal germ cells in nuage also called germinal granules that are often associated with mitochondria and called intermitochondrial cement. We find that GASZ (Germ cell protein with Ankyrin repeats, Sterile alpha motif, and leucine Zipper) co-localizes with MILI in intermitochondrial cement. Knockout of Gasz in mice results in a dramatic downregulation of MILI, and phenocopies the zygotene–pachytene spermatocyte block and male sterility defect observed in MILI null mice. In Gasz null testes, we observe increased hypomethylation and expression of retrotransposons similar to MILI null testes. We also find global shifts in the small RNAome, including down-regulation of repeat-associated, known, and novel piRNAs. These studies provide the first evidence for an essential structural role for GASZ in male fertility and epigenetic and post-transcriptional silencing of retrotransposons by stabilizing MILI in nuage

A molecular "screw-​clamp": accelerating click reactions in miniemulsions

The interface as a “screw clamp”: the copper-free 1,3-dipolar azide–alkyne cycloaddition at the interface of nanodroplets in miniemulsions was studied in detail by NMR spectroscopic methods. The reaction at the oil–water interface proved to exhibit higher rate constants, increased molecular weights and high regioregularity compared to the reaction in solutio

Methylthioadenosine Phosphorylase Genomic Loss in Advanced Gastrointestinal Cancers

BACKGROUND: One of the most common sporadic homozygous deletions in cancers is 9p21 loss, which includes the genes methylthioadenosine phosphorylase (MTAP), CDKN2A, and CDKN2B, and has been correlated with worsened outcomes and immunotherapy resistance. MTAP-loss is a developing drug target through synthetic lethality with MAT2A and PMRT5 inhibitors. The purpose of this study is to investigate the prevalence and genomic landscape of MTAP-loss in advanced gastrointestinal (GI) tumors and investigate its role as a prognostic biomarker. MATERIALS AND METHODS: We performed next-generation sequencing and comparative genomic and clinical analysis on an extensive cohort of 64 860 tumors comprising 5 GI cancers. We compared the clinical outcomes of patients with GI cancer harboring MTAP-loss and MTAP-intact tumors in a retrospective study. RESULTS: The prevalence of MTAP-loss in GI cancers is 8.30%. MTAP-loss was most prevalent in pancreatic ductal adenocarcinoma (PDAC) at 21.7% and least in colorectal carcinoma (CRC) at 1.1%. MTAP-loss tumors were more prevalent in East Asian patients with PDAC (4.4% vs 3.2%, P = .005) or intrahepatic cholangiocarcinoma (IHCC; 6.4% vs 4.3%, P = .036). Significant differences in the prevalence of potentially targetable genomic alterations (ATM, BRAF, BRCA2, ERBB2, IDH1, PIK3CA, and PTEN) were observed in MTAP-loss tumors and varied according to tumor type. MTAP-loss PDAC, IHCC, and CRC had a lower prevalence of microsatellite instability or elevated tumor mutational burden. Positive PD-L1 tumor cell expression was less frequent among MTAP-loss versus MTAP-intact IHCC tumors (23.2% vs 31.2%, P = .017). CONCLUSION: In GI cancers, MTAP-loss occurs as part of 9p21 loss and has an overall prevalence of 8%. MTAP-loss occurs in 22% of PDAC, 15% of IHCC, 8.7% of gastroesophageal adenocarcinoma, 2.4% of hepatocellular carcinoma, and 1.1% of CRC and is not mutually exclusive with other targetable mutations

Analysis of MicroRNA Expression in the Prepubertal Testis

Only thirteen microRNAs are conserved between D. melanogaster and the mouse; however, conditional loss of miRNA function through mutation of Dicer causes defects in proliferation of premeiotic germ cells in both species. This highlights the potentially important, but uncharacterized, role of miRNAs during early spermatogenesis. The goal of this study was to characterize on postnatal day 7, 10, and 14 the content and editing of murine testicular miRNAs, which predominantly arise from spermatogonia and spermatocytes, in contrast to prior descriptions of miRNAs in the adult mouse testis which largely reflects the content of spermatids. Previous studies have shown miRNAs to be abundant in the mouse testis by postnatal day 14; however, through Next Generation Sequencing of testes from a B6;129 background we found abundant earlier expression of miRNAs and describe shifts in the miRNA signature during this period. We detected robust expression of miRNAs encoded on the X chromosome in postnatal day 14 testes, consistent with prior studies showing their resistance to meiotic sex chromosome inactivation. Unexpectedly, we also found a similar positional enrichment for most miRNAs on chromosome 2 at postnatal day 14 and for those on chromosome 12 at postnatal day 7. We quantified in vivo developmental changes in three types of miRNA variation including 5′ heterogeneity, editing, and 3′ nucleotide addition. We identified eleven putative novel pubertal testis miRNAs whose developmental expression suggests a possible role in early male germ cell development. These studies provide a foundation for interpretation of miRNA changes associated with testicular pathology and identification of novel components of the miRNA editing machinery in the testis