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Das CUP-Syndrom („cancer of unknown primary origin“) wird definiert als eine heterogene Gruppe von Karzinomerkrankungen. Die Diagnose metastasiertes Karzinom bei unbekanntem Primarius ist im onkologischen Alltag mit Unsicherheiten sowohl diagnostischer als auch therapeutischer Natur assoziiert. Auf der Grundlage von Literaturrecherchen sowie klinischer Expertise wurden die Moglichkeiten einer Strahlenbehandlung bei CUP beschrieben. Fur die Planung der Strahlentherapie sind Histologie, Lokalisation und Ausdehnung der Tumormanifestationen entscheidend. Unerlasslich fur eine zielgerichtete und effektive Strahlentherapie sind moderne bildgebende Verfahren zum pratherapeutischen Staging und zur Zielvolumendefinition. Die Strahlentherapie eroffnet in Verbindung mit operativen und medikamentosen Ansatzen therapeutische Moglichkeiten zum organerhaltenden und kurativen Vorgehen bei axillarem und zervikalen CUP. In palliativer Situation bietet die Strahlentherapie Optionen zur Pravention und Behandlung krankheitsassoziierter Komplikationen und zur Aufrechterhaltung der Lebensqualitat (z. B. ossare und zerebrale Metastasen). Die Behandlung von Patienten mit CUP-Syndrom stellt eine interdisziplinare Herausforderung dar. Strahlentherapie bietet kurative Therapieansatze bei lokalisiertem CUP. Sie ist wirksam bei symptomatischen Metastasen.

Single ribonucleoside monophosphates (rNMPs) are transiently present in eukaryotic genomes. The RNase H2-dependent ribonucleotide excision repair (RER) pathway ensures error-free genomic rNMP removal. In pathological conditions, genomic rNMP levels can rise and persist. If these rNMPs hydrolyse in, or prior to, S phase, toxic single-ended double-strand breaks (seDSBs) can occur upon an encounter with replication forks. How such rNMP-derived seDSB lesions are repaired is unclear. We employed a cell cycle phase restricted allele of RNase H2 as a genetic tool to induce nicks at rNMPs specifically in S phase to generate such lesions and study their repair. Here, we introduce a network of genes that maintain DNA integrity when rNMP-derived nick lesions arise during DNA replication. We use genetic methods to characterise the molecular requirements of a Top1-independent, rNMP-derived nick lesion repair (NLR). In NLR, the RAD52 epistasis group becomes essential for homology-directed repair (HDR). Moreover, the previously described Rtt101Mms1-Mms22 dependent ubiquitylation of histone H3 is essential for NLR in cells with high rNMP load, and loss of Rtt101Mms1-Mms22 combined with RNase H2 dysfunction leads to compromised cellular fitness. We discuss the genetic NLR network in the context of human disease, where cancer therapies may be able to exploit these synthetic lethalities.

Das Analkarzinom ist ein seltener gastrointestinaler Tumor mit stetig steigenden Inzidenzzahlen. Die Entstehung des Analkarzinoms ist eng mit dem humanen Papillomavirus verbunden. Das Karzinom wird haufiger bei Frauen diagnostiziert. Die simultane Radiochemotherapie stellt die Standardtherapie dar und ist meist mit einem Sphinktererhalt verbunden. Die intensitatsmodulierte Radiotherapie reduziert die Nebenwirkungen signifikant. Bei persistierendem Tumor nach Radiochemotherapie oder lokalem Rezidiv kann mit einer abdominoperinealen Rektumexstirpation prinzipiell eine Heilung erzielt werden. Um die Indikation zur chirurgischen Intervention fruhzeitig erkennen zu konnen, sollten regelmasige Nachsorgeuntersuchungen gewahrleistet sein. Neuere Substanzen und/oder das Hinzufugen einer Induktions- oder Erhaltungschemotherapie konnten die Ergebnisse bisher nicht verbessern. Die Suche nach neuen Substanzen ist aber vielversprechend. Eine Kooperation aller beteiligten Disziplinen ist unabdingbar.

The human ribosomal DNA (rDNA) locus encodes a variety of long non-coding RNAs (lncRNAs). Among them, the canonical ribosomal RNAs that are the catalytic components of the ribosomes, as well as regulatory lncRNAs including promoter-associated RNAs (pRNA), stress-induced promoter and pre-rRNA antisense RNAs (PAPAS), and different intergenic spacer derived lncRNA species (IGSRNA). In addition, externally encoded lncRNAs are imported into the nucleolus, which orchestrate the complex regulation of the nucleolar state in normal and stress conditions via a plethora of molecular mechanisms. This review focuses on the triplex and R-loop formation aspects of lncRNAs at the rDNA locus in yeast and human cells. We discuss the protein players that regulate R-loops at rDNA and how their misregulation contributes to DNA damage and disease. Furthermore, we speculate how DNA lesions such as rNMPs or 8-oxo-dG might affect RNA-DNA hybrid formation. The transcription of lncRNA from rDNA has been observed in yeast, plants, flies, worms, mouse and human cells. This evolutionary conservation highlights the importance of lncRNAs in rDNA function and maintenance.

Strahlentherapie verfugt uber einen starken und schnellen tumoriziden Effekt, der einen wirksamen Einsatz in onkologischen Notfallsituationen ermoglicht. Die Applikation ionisierender Strahlung kann schnell und prazise erfolgen. Auf der Grundlage von Literaturrecherchen und eigener Expertise werden die aktuellen Aspekte zur Radiotherapie in onkologischen Notfallsituationen zusammengestellt. Strahlentherapie kommt zum Einsatz im Rahmen der interdisziplinaren Tumortherapie bei oberer Einflussstauung, spinalem Kompressionssyndrom und Hirndrucksteigerung bei Hirnmetastasen. Sie ist sehr effektiv beim Stillen von tumorbedingten Blutungen sowie bei allen bedrohlichen tumorbedingten Kompressionssyndromen. In 50–90 % der Falle kann eine Reduktion der Symptomatik erreicht werden. In etwa 30 % der Falle ist sie von Dauer. Die Ergebnisse der Strahlentherapie bei onkologischen Notfallen legen nahe, dieses Behandlungsverfahren bei gegebener Indikation rechtzeitig einzusetzen.

The conserved Mre11-Rad50 complex is crucial for the detection, signaling, end tethering and processing of DNA double-strand breaks. While it is known that Mre11-Rad50 foci formation at DNA lesions accompanies repair, the underlying molecular assembly mechanisms and functional implications remained unclear. Combining pathway reconstitution in electron microscopy, biochemical assays and genetic studies, we show that S. cerevisiae Mre11-Rad50 with or without Xrs2 forms higher-order assemblies in solution and on DNA. Rad50 mediates such oligomerization, and mutations in a conserved Rad50 beta-sheet enhance or disrupt oligomerization. We demonstrate that Mre11-Rad50-Xrs2 oligomerization facilitates foci formation, DNA damage signaling, repair, and telomere maintenance in vivo. Mre11-Rad50 oligomerization does not affect its exonuclease activity but drives endonucleolytic cleavage at multiple sites on the 5'-DNA strand near double-strand breaks. Interestingly, mutations in the human RAD50 beta-sheet are linked to hereditary cancer predisposition and our findings might provide insights into their potential role in chemoresistance.

Heart development relies on PTMs that control cardiomyocyte proliferation, differentiation and cardiac morphogenesis. We generated a map of phosphorylation sites during the early stages of cardiac postnatal development in mice; we quantified over 10,000 phosphorylation sites and 5000 proteins that were assigned to different pathways. Analysis of mitochondrial proteins led to the identification of PGC-1- and ERR-induced regulator in muscle 1 (PERM1), which is specifically expressed in skeletal muscle and heart tissue and associates with the outer mitochondrial membrane. We demonstrate PERM1 is subject to rapid changes mediated by the UPS through phosphorylation of its PEST motif by casein kinase 2. Ablation of Perm1 in mice results in reduced protein expression of lipin-1 accompanied by accumulation of specific phospholipid species. Isolation of Perm1-deficient mitochondria revealed significant downregulation of mitochondrial transport proteins for amino acids and carnitines, including SLC25A12/13/29/34 and CPT2. Consistently, we observed altered levels of various lipid species, amino acids, and acylcarnitines in Perm1(-/-) mitochondria. We conclude that the outer mitochondrial membrane protein PERM1 regulates homeostasis of lipid and amino acid metabolites in mitochondria.

Summary: Protein aggregates and cytoplasmic vacuolization are major hallmarks of multisystem proteinopathies (MSPs) that lead to muscle weakness. Here, we identify METTL21C as a skeletal muscle-specific lysine methyltransferase. Insertion of a β-galactosidase cassette into the Mettl21c mouse locus revealed that METTL21C is specifically expressed in MYH7-positive skeletal muscle fibers. Ablation of the Mettl21c gene reduced endurance capacity and led to age-dependent accumulation of autophagic vacuoles in skeletal muscle. Denervation-induced muscle atrophy highlighted further impairments of autophagy-related proteins, including LC3, p62, and cathepsins, in Mettl21c−/− muscles. In addition, we demonstrate that METTL21C interacts with the ATPase p97 (VCP), which is mutated in various human MSP conditions. We reveal that METTL21C trimethylates p97 on the Lys315 residue and found that loss of this modification reduced p97 hexamer formation and ATPase activity in vivo. We conclude that the methyltransferase METTL21C is an important modulator of protein degradation in skeletal muscle under both normal and enhanced protein breakdown conditions. : Wiederstein et al. describe the skeletal muscle methyltransferase Mettl21c. They found that ablation of Mettl21c in mice results in muscle weakness and disturbance of the protein degradation machinery. Those changes are hallmarks of multisystem proteinopathies. They demonstrate that Mettl21c modulates p97 activity, which is frequently mutated in human patients with muscle weakness. Keywords: methyltransferases, skeletal muscle, p97, atrophy, autophagy

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) are closely related members of the interleukin-6 (IL-6) cytokine family. Both cytokines share a common origin and structure, and both interact through a specific region, termed binding site III, to activate a dimeric receptor complex formed by glycoprotein 130 (gp130) and LIF receptor (LIFR) in humans. However, only OSM activates the OSM receptor (OSMR)–gp130 complex. The molecular features that enable OSM to specifically activate the OSMR are currently unknown. To define specific sequence motifs within OSM that are critical for initiating signaling via OSMR, here we generated chimeric OSM–LIF cytokines and performed alanine-scanning experiments. Replacement of the OSM AB loop within OSM's binding site III with that of LIF abrogated OSMR activation, measured as STAT3 phosphorylation at Tyr-705, but did not compromise LIFR activation. Correspondingly, substitution of the AB loop and D-helix in LIF with their OSM counterparts was sufficient for OSMR activation. The alanine-scanning experiments revealed that residues Tyr-34, Gln-38, Gly-39, and Leu-45 (in the AB loop) and Pro-153 (in the D-helix) had specific roles in activating OSMR but not LIFR signaling, whereas Leu-40 and Cys-49 (in the AB loop), and Phe-160 and Lys-163 (in the D-helix) were required for activation of both receptors. Because most of the key amino acid residues identified here are conserved between LIF and OSM, we concluded that comparatively minor differences in a few amino acid residues within binding site III account for the differential biological effects of OSM and LIF.

Recurrent mutations in MYD88 have been identified in >90% of lymphoplasmacytic lymphoma (LPL). Recently, WHIM (warts, hypogammaglobulinaemia, infections, myelokathexis) syndrome-like mutations in CXCR4 have been described in 28% of LPL cases, and seem to impact clinical presentation and response to therapy. We investigated the presence of the MYD88 L265P mutation in 90 decalcified, formalin-fixed, paraffin-embedded (FFPE) bone marrow (BM) biopsies, including 51 cases of LPL, 14 cases of B-cell chronic lymphocytic leukaemia (CLL), 13 cases of marginal zone lymphoma (MZL) and 12 normal controls. In addition, the C-terminal domain of CXCR4 was sequenced in LPL cases. MYD88 L265P was found in 49/51 (96%) LPL cases and in 1/13 (7·6%) MZL (splenic type), whereas all CLL samples remained negative. The two MYD88 wild type LPL cases were associated with cold agglutinin disease. Mutations in CXCR4 were detected in 17/47 (36·2%) LPL cases, which showed a higher extent of BM infiltration and lower leucocyte counts (P = 0·02), haemoglobin (P = 0·05) and platelet counts (P = 0·01). In conclusion the detection of MYD88 L265P mutation in FFPE samples is reliable and useful for subtyping small B-cell lymphomas in BM biopsies. In addition, the presence of CXCR4 mutations identifies a subgroup of LPL patients with higher disease activity.