@article{WittbrodtLammersMalitscheketal.1992,
  author    = {Wittbrodt, Joachim and Lammers, Reiner and Malitschek, Barbara and Ullrich, Axel and Schartl, Manfred},
  title     = {Xmrk receptor tyrosine kinase is activated in Xiphophorus malignant melanoma},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61699},
  year      = {1992},
  abstract  = {Xmrk encodes a putative transmembrane glycoprotein of the tyrosine kinase family and is a melanoma-inducing gene in Xiphophorus. We attempted to investigate the biological function of the putative Xmrk receptor by characterizing its signalling properties. Since a potential Iigand for Xmrk has not yet been identified, it has been difficult to analyse the biochemical properlies and biological function of this cell surface protein. In an approach towards such analyses, the Xmrk extracellular domain was replaced by the closely related Iigand-binding domain sequences of the human epidennal growth factor receptor (HER) and the ligand-induced activity of the chimeric HER-Xmrk proteinwas examined. We show that the Xmrk protein is a functional receptor tyrosine kinase, is highly active in malignant melanoma and displays a constitutive autophosphorylation activity possibly due to an activating mutation in its extracellular or transmembrane domain. In the focus formation assay the HER-Xmrk chimera is a potent transfonning protein equivalent to other tyrosine kinase oncoproteins.},
  subject      = {Physiologische Chemie},
  language  = {en}
}
@article{WendlingerWohlfarthKreftetal.2022,
  author    = {Wendlinger, Simone and Wohlfarth, Jonas and Kreft, Sophia and Siedel, Claudia and Kilian, Teresa and Dischinger, Ulrich and Heppt, Markus V. and Wistuba-Hamprecht, Kilian and Meier, Friedegund and Goebeler, Matthias and Schadendorf, Dirk and Gesierich, Anja and Kosnopfel, Corinna and Schilling, Bastian},
  title     = {Blood eosinophils are associated with efficacy of targeted therapy in patients with advanced melanoma},
  series = {Cancers},
  volume    = {14},
  journal   = {Cancers},
  number    = {9},
  issn      = {2072-6694},
  doi       = {10.3390/cancers14092294},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-275137},
  year      = {2022},
  abstract  = {Background: Eosinophils appear to contribute to the efficacy of immunotherapy and their frequency was suggested as a predictive biomarker. Whether this observation could be transferred to patients treated with targeted therapy remains unknown. Methods: Blood and serum samples of healthy controls and 216 patients with advanced melanoma were prospectively and retrospectively collected. Freshly isolated eosinophils were phenotypically characterized by flow cytometry and co-cultured in vitro with melanoma cells to assess cytotoxicity. Soluble serum markers and peripheral blood counts were used for correlative studies. Results: Eosinophil-mediated cytotoxicity towards melanoma cells, as well as phenotypic characteristics, were similar when comparing healthy donors and patients. However, high relative pre-treatment eosinophil counts were significantly associated with response to MAPKi (p = 0.013). Eosinophil-mediated cytotoxicity towards melanoma cells is dose-dependent and requires proximity of eosinophils and their target in vitro. Treatment with targeted therapy in the presence of eosinophils results in an additive tumoricidal effect. Additionally, melanoma cells affected eosinophil phenotype upon co-culture. Conclusion: High pre-treatment eosinophil counts in advanced melanoma patients were associated with a significantly improved response to MAPKi. Functionally, eosinophils show potent cytotoxicity towards melanoma cells, which can be reinforced by MAPKi. Further studies are needed to unravel the molecular mechanisms of our observations.},
  language  = {en}
}
@article{TomeiAdamsUccellinietal.2012,
  author    = {Tomei, Sara and Adams, Sharon and Uccellini, Lorenzo and Bedognetti, Davide and De Giorgi, Valeria and Erdenebileg, Narnygerel and Libera Ascierto, Maria and Reinboth, Jennifer and Liu, Qiuzhen and Bevilacqua, Generoso and Wang, Ena and Mazzanti, Chiara and Marincola, Francesco M.},
  title     = {Association between HRAS rs12628 and rs112587690 polymorphisms with the risk of melanoma in the North American population},
  series = {Medical Oncology},
  volume    = {29},
  journal   = {Medical Oncology},
  number    = {5},
  doi       = {dx.doi.org/10.1007/s12032-012-0255-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126834},
  pages     = {3456-3461},
  year      = {2012},
  abstract  = {HRAS belongs to the RAS genes superfamily. RAS genes are important players in several human tumors and the single-nucleotide polymorphism rs12628 has been shown to contribute to the risk of bladder, colon, gastrointestinal, oral, and thyroid carcinoma. We hypothesized that this SNP may affect the risk of cutaneous melanoma as well. HRAS gene contains a polymorphic region (rs112587690), a repeated hexanucleotide -GGGCCT- located in intron 1. Three alleles of this region, P1, P2, and P3, have been identified that contain two, three, and four repeats of the hexanucleotide, respectively. We investigated the clinical impact of these polymorphisms in a case-control study. A total of 141 melanoma patients and 118 healthy donors from the North America Caucasian population were screened for rs12628 and rs112587690 polymorphisms. Genotypes were assessed by capillary sequencing or fragment analysis, respectively, and rs12628 CC and rs112587690 P1P1 genotypes significantly associated with increased melanoma risk (OR = 3.83, p = 0.003; OR = 11.3, p = 0.033, respectively), while rs112587690 P1P3 frequency resulted significantly higher in the control group (OR = 0.5, p = 0.017). These results suggest that rs12628 C homozygosis may be considered a potential risk factor for melanoma development in the North American population possibly through the linkage to rs112587690.},
  language  = {en}
}
@phdthesis{Teutschbein2008,
  author    = {Teutschbein, Janka},
  title     = {Identifizierung und Charakterisierung von Genen und Proteinen in der Xmrk-induzierten Entwicklung von Melanomen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-27516},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Melanome stellen die gef{\"a}hrlichste Form von Hautkrebs mit der h{\"o}chsten Mortalit{\"a}tsrate dar. Der Transformation normaler Melanozyten zu malignen Melanomen liegen komplexe molekulare und biochemische Ver{\"a}nderungen zu Grunde. Im Xiphophorus-Melanom-Modell ist die onkogene Rezeptortyrosinkinase "Xiphophorus melanoma receptor kinase" (Xmrk) der alleinige Ausl{\"o}ser der Melanominitiation und -progression. Die Aufkl{\"a}rung der Xmrk-vermittelten Signaltransduktion kann zum besseren Verst{\"a}ndnis von Ereignissen, die auch bei der humanen Melanomentwicklung eine Rolle spielen, beitragen. In der vorliegenden Arbeit wurde mit Hilfe der Microarray-Technologie die Regulation der Genexpression durch Xmrk analysiert. Zu den nach Rezeptoraktivierung am st{\"a}rksten herabregulierten Genen geh{\"o}rten "son of sevenless homolog 1" (Sos1) und "ubiquitin-conjugating enzyme E2I" (Ube2i); stark hochreguliert waren "early growth response 1" (Egr1), "cysteine-rich protein 61" (Cyr61), "dual-specificity phosphatase 4" (Dusp4), "fos-like antigen 1" (Fosl1), "epithelial membrane protein" (Emp1), Osteopontin (Opn), "insulin-like growth factor binding protein 3" (Igfbp3) und "tumor-associated antigen L6" (Taal6). Die f{\"u}r die Regulation dieser Gene verantwortlichen Signalwege wurden durch die Anwendung von niedermolekularen Inhibitoren und siRNA identifiziert, wobei f{\"u}r die SRC-Kinase FYN eine zentrale Bedeutung bei der Xmrk-abh{\"a}ngigen Regulation der Genexpression festgestellt wurde. Dar{\"u}ber hinaus wurde die Expression der Gene in humanen Melanomzelllinien im Vergleich zu normalen humanen Melanozyten untersucht. Als besonders vielversprechende Kandidaten stellten sich dabei DUSP4 und TAAL6 heraus, deren Rolle in der humanen Melanominduktion und -progression Gegenstand zuk{\"u}nftiger Studien sein wird. In einem anderen Ansatz zur Aufkl{\"a}rung des Signalnetzwerkes sollten Zielproteine von Xmrk durch Protein-Protein-Interaktionsstudien mit Hilfe des Split-Ubiquitin-Systems ermittelt werden. Aufgrund ung{\"u}nstiger Expressions- oder Faltungseigenschaften von Xmrk in diesem System war es aber nicht m{\"o}glich, den Rezeptor als K{\"o}derprotein einzusetzen. Das f{\"u}r die Xmrk-vermittelte Melanomentstehung zentrale Protein FYN konnte jedoch als K{\"o}der etabliert und seine Wechselwirkung mit der Tyrosinkinase FAK analysiert werden. Es wurde gezeigt, dass der phosphorylierte Tyrosinrest an Position 397 von FAK f{\"u}r die Interaktion einer N-terminal trunkierten FAK-Variante mit FYN notwendig ist und dass diese Phosphorylierung in Hefe gew{\"a}hrleistet zu sein scheint. Die Suche nach neuen Interaktionspartnern von FYN mittels der Split-Ubiquitin-Technologie k{\"o}nnte Einblicke in weitere FYN-abh{\"a}ngige Ereignisse bieten, die zur Aufkl{\"a}rung seiner zentralen Rolle bei der Tumorentstehung dienen k{\"o}nnte.},
  subject      = {Melanom},
  language  = {de}
}
@article{SchummerSchilling2022,
  author    = {Schummer, Patrick and Schilling, Bastian},
  title     = {How representative are data from global trials on programmed death-1 blockade in melanoma?},
  series = {The British Journal of Dermatology},
  volume    = {187},
  journal   = {The British Journal of Dermatology},
  number    = {3},
  doi       = {10.1111/bjd.21621},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318406},
  pages     = {283 -- 284},
  year      = {2022},
  language  = {en}
}
@article{SchramaUgurelSuckeretal.2014,
  author    = {Schrama, David and Ugurel, Selma and Sucker, Antje and Ritter, Cathrin and Zapatka, Marc and Schadendorf, Dirk and Becker, J{\"u}rgen Christian},
  title     = {STAT3 Single Nucleotide Polymorphism rs4796793 SNP Does Not Correlate with Response to Adjuvant IFNα Therapy in Stage III Melanoma Patients},
  series = {Frontiers in Medicine},
  volume    = {1},
  journal   = {Frontiers in Medicine},
  number    = {47},
  issn      = {2296-858X},
  doi       = {10.3389/fmed.2014.00047},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120602},
  year      = {2014},
  abstract  = {Interferon alpha (IFNα) is approved for adjuvant treatment of stage III melanoma in Europe and the US. Its clinical efficacy, however, is restricted to a subpopulation of patients while side effects occur in most of treated patients. Thus, the identification of predictive biomarkers would be highly beneficial to improve the benefit to risk ratio. In this regard, STAT3 is important for signaling of the IFNα receptor. Moreover, the STAT3 single-nucleotide polymorphism (SNP) rs4796793 has recently been reported to be associated with IFNα sensitivity in metastatic renal cell carcinoma. To translate this notion to melanoma, we scrutinized the impact of rs4796793 functionally and clinically in this cancer. Interestingly, melanoma cells carrying the minor allele of rs4796793 were the most sensitive to IFNα in vitro. However, we did not detect a correlation between SNP genotype and STAT3 mRNA expression for either melanoma cells or for peripheral blood lymphocytes. Next, we analyzed the impact of rs4796793 on the clinical outcome of 259 stage III melanoma patients of which one-third had received adjuvant IFNα treatment. These analyses did not reveal a significant association between the STAT3 rs4796793 SNP and patients' progression free or overall survival when IFNα treated and untreated patients were compared. In conclusion, STAT3 rs4796793 SNP is no predictive marker for the efficacy of adjuvant IFNα treatment in melanoma patients.},
  language  = {en}
}
@phdthesis{Schrama2004,
  author    = {Schrama, David},
  title     = {T-Zell-priming außerhalb sekund{\"a}rer lymphatischer Gewebe},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-15060},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {T-Zellimmunantworten werden normalerweise durch folgenden Weg initiiert: unreife dendritische Zellen nehmen Antigen in der Peripherie auf, wandern in die sekund{\"a}ren lymphatischen Organe, wobei sie auf ihrem Weg sowohl reifen als auch das Antigen prozessieren. In den sekund{\"a}ren lymphatischen Organen angekommen, pr{\"a}sentieren sie als reife dendritische Zellen den T-Zellen die Antigene in Form von Peptiden zusammen mit kostimulierenden Molek{\"u}len. Dadurch rufen sie eine spezifische T-Zellantwort hervor. In der vorliegenden Arbeit wurde untersucht, ob nicht Situationen herbeigef{\"u}hrt werden k{\"o}nnen, die ein T-Zell priming außerhalb der sekund{\"a}ren lymphatischen Organe erlauben. Dazu wurden ein murines Modell, bei dem das Zytokin Lymphotoxin-alpha spezifisch am Tumor angereichert wurde, und ein humanes Modell, bei dem reife, antigenbeladene DC intradermal appliziert wurden, untersucht. Im murinen Modell zeigte sich, dass die gerichtete Anreicherung von Lymphotoxin-alpha am Tumor zu dessen Zerst{\"o}rung f{\"u}hrte, welche durch T-Zellen vermittelt wurde, und mit der Induktion eines terti{\"a}ren lymphatischen Gewebes am Tumor assoziiert war. Dieses terti{\"a}re lymphatische Gewebe war durch die Kompartimentalisierung von T- und B-Zellen und der Pr{\"a}senz von high endothelial venules charakterisiert und besaß zudem mit dendritischen Zellen und na{\"i}ven T-Zellen alle Voraussetzungen f{\"u}r ein in loco priming. Dementsprechend konnte in der Folge der gerichteten Lymphotoxin-alpa Therapie im Tumor ein Anstieg am T-Zellinfiltrat, welches sich oligoklonal zusammensetzte, beobachtet werden. In vitro Experimente verdeutlichte die Tumorspezifit{\"a}t der Therapie-induzierten T-Zellantwort, da die T-Zellen auf ein Tumorantigen mit der Aussch{\"u}ttung von Interferon gamma reagierten und die Tumorzellen lysierten. Im humanen Modell wurden Hautbiopsien von Melanompatienten untersucht, denen im Rahmen einer klinischen Studie autologe, in vitro generierte und antigenbeladene DC intradermal appliziert wurden. Die Patienten erlaubten die Entnahme von Hautbiopsien aus den Injektionsstellen f{\"u}r wissenschaftliche Untersuchungen. Eine Induktion bzw. Verst{\"a}rkung einer spezifischen T-Zellantwort durch die Vakzinierung mit antigenbeladenen dendritischen Zellen konnte bereits in zahlreichen Arbeiten und auch in dem in dieser Arbeit untersuchten Patientenkollektiv gezeigt werden. Bei der Analyse der Injektionsstellen zeigt sich, dass ein großer Teil der injizierten dendritischen Zellen in der Vakzinierungsstelle verharren und dass diese unabh{\"a}ngig von einer Beladung mit Antigen zu einer Induktion von high endothelial venules Charakteristika f{\"u}hrte. Waren die dendritischen Zellen mit Antigen beladen, so f{\"u}hrte dies zu einem st{\"a}rkeren T-Zellinfiltrat in den Injektionsstellen, wobei sowohl na{\"i}ve als auch central memory T-Zellen nachgewiesen wurde. Diese Zellen wurden vermutlich durch die {\"U}berexpression der DC CK1 und SDF1 Chemokinen in den Injektionsstellen, die chemotaktisch auf T-Zellen wirken, angezogen. Das Infiltrat in den Injektionsstellen war oligoklonal und wies tumorspezifische T-Zellen auf. Nachdem diese T-Zellklone im Blut der Patienten vor der Vakzinierung nicht nachweisbar waren, m{\"u}ssen sie zumindest in den Injektionsstellen expandiert sein. Interessanterweise konnte einer dieser Klone in Metastasen nachgewiesen werden, die nach der Vakzinierung dem Patienten entfernt wurden. In beiden Modellen wurde also durch die Manipulation des Mikromilieus, d.h. Lymphotoxin-alpa Anreicherung am Tumor bzw. Injektion von reifen dendritischen Zellen in die Haut, Strukturen wie z.B. high endothelial venules induziert, die ein in loco priming erm{\"o}glichen sollten. Dementsprechend riefen diese Ver{\"a}nderungen ein Tumorantigen-spezifisches Infiltrat hervor. Diese Ergebnisse deuten darauf hin, dass T-Zell priming auch außerhalb sekund{\"a}rer lymphatischer Organe erfolgen kann. Prinzipiell scheint also nur der Kontakt von reifen, antigenbeladenen dendritischen Zellen mit den entsprechenden antigenspezifischen, na{\"i}ven T-Zellen entscheiden zu sein. Die M{\"o}glichkeit des in vitro primings bekr{\"a}ftigt diese These. In vivo erfolgt dieses Aufeinandertreffen normalerweise in den sekund{\"a}ren lymphatischen Organen, doch konnte in der vorliegenden Arbeit gezeigt werden, dass Ver{\"a}nderungen des Mikromilieus diesen Kontakt auch in anderen Geweben erm{\"o}glicht.},
  subject      = {T-Lymphozyt},
  language  = {de}
}
@phdthesis{Schmitt2015,
  author    = {Schmitt, Alexandra},
  title     = {Role of Peroxiredoxin 6 in human melanoma},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111465},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Peroxiredoxin 6 (PRDX6) is a bifunctional enzyme comprising a peroxidase and a Ca2+-independent phospholipase (iPLA2) activity. This renders the enzyme capable of detoxifying reactive oxygen species (ROS) and of catalyzing the liberation of arachidonic acid (AA) from cellular membranes. Released AA can be further metabolized to bioactive lipids including eicosanoids, which are involved in inflammation, cell growth, differentiation, invasion and proliferation. Human melanoma cells are often characterized by imbalances in both ROS and lipid levels, which can be generated by oncogenic signaling, altered metabolism or UV irradiation. In previous studies, a comparative proteome analysis of the Xiphophorus fish melanoma model revealed a strong upregulation of Prdx6 in benign and malignant lesions compared to healthy skin. As the Xiphophorus melanoma model displays in many respects molecular characteristics that are similar to human melanoma, I investigated the functional role of PRDX6 in human melanoma cells. The first part of the study deals with the regulation of PRDX6 in melanocytes and human melanoma cells. I could demonstrate that the protein level of PRDX6 was strongly enhanced by the induction of the EGFR orthologue Xmrk from the Xiphophorus fish as well as the human EGFR. The upregulation of PRDX6 was further shown to be mediated in a PI3K-dependent and ROS-independent manner. The main part of the thesis comprises the investigation of the functional role of PRDX6 in human melanoma cells as well as the analysis of the underlying mechanism. I could show that knockdown of PRDX6 enhanced the oxidative stress response and led to decreased proliferation of melanoma cells. This cell growth effect was mainly mediated by the iPLA2 activity of PRDX6. Under conditions of strongly enhanced oxidative stress, the peroxidase activity became also important for cellular proliferation. Furthermore, the anti-proliferative effect in cells with lowered PRDX6 levels was the result of reduced cellular AA content and the decrease in the activation of SRC family proteins. Similarly, supplementation with AA led to regeneration of SRC family kinase activity and to an improvement in the reduced proliferation after knockdown of PRDX6. Since AA can be further processed into the prostaglandin PGE2, which has a pro-tumorigenic function in some cancer types, I further examined whether this eicosanoid is involved in the proliferative function of PRDX6. In contrast to AA, PGE2 was not consistently required for melanoma proliferation. In summary, I could demonstrate that PRDX6 plays a major role in AA-dependent lipid signaling in melanoma cells and thereby regulates proliferation. Interestingly, the proliferation relevant iPLA2 activity can be pharmacologically targeted, and melanoma cell growth was clearly blocked by the inhibitor BEL. Thus, I could identify the phospholipase activity of PRDX6 as a new therapeutically interesting target for melanoma treatment.},
  subject      = {Melanom},
  language  = {en}
}
@article{SchmidSchmidtHazuretal.2020,
  author    = {Schmid, Rafael and Schmidt, Sonja K. and Hazur, Jonas and Detsch, Rainer and Maurer, Evelyn and Boccaccini, Aldo R. and Hauptstein, Julia and Teßmar, J{\"o}rg and Blunk, Torsten and Schr{\"u}fer, Stefan and Schubert, Dirk W. and Horch, Raymund E. and Bosserhoff, Anja K. and Arkudas, Andreas and Kengelbach-Weigand, Annika},
  title     = {Comparison of hydrogels for the development of well-defined 3D cancer models of breast cancer and melanoma},
  series = {Cancers},
  volume    = {12},
  journal   = {Cancers},
  number    = {8},
  issn      = {2072-6694},
  doi       = {10.3390/cancers12082320},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211195},
  year      = {2020},
  abstract  = {Bioprinting offers the opportunity to fabricate precise 3D tumor models to study tumor pathophysiology and progression. However, the choice of the bioink used is important. In this study, cell behavior was studied in three mechanically and biologically different hydrogels (alginate, alginate dialdehyde crosslinked with gelatin (ADA-GEL), and thiol-modified hyaluronan (HA-SH crosslinked with PEGDA)) with cells from breast cancer (MDA-MB-231 and MCF-7) and melanoma (Mel Im and MV3), by analyzing survival, growth, and the amount of metabolically active, living cells via WST-8 labeling. Material characteristics were analyzed by dynamic mechanical analysis. Cell lines revealed significantly increased cell numbers in low-percentage alginate and HA-SH from day 1 to 14, while only Mel Im also revealed an increase in ADA-GEL. MCF-7 showed a preference for 1\% alginate. Melanoma cells tended to proliferate better in ADA-GEL and HA-SH than mammary carcinoma cells. In 1\% alginate, breast cancer cells showed equally good proliferation compared to melanoma cell lines. A smaller area was colonized in high-percentage alginate-based hydrogels. Moreover, 3\% alginate was the stiffest material, and 2.5\% ADA-GEL was the softest material. The other hydrogels were in the same range in between. Therefore, cellular responses were not only stiffness-dependent. With 1\% alginate and HA-SH, we identified matrices that enable proliferation of all tested tumor cell lines while maintaining expected tumor heterogeneity. By adapting hydrogels, differences could be accentuated. This opens up the possibility of understanding and analyzing tumor heterogeneity by biofabrication.},
  language  = {en}
}
@article{RotheBrandenburgHaunetal.2017,
  author    = {Rothe, Hansj{\"o}rg and Brandenburg, Vincent and Haun, Margot and Kollerits, Barbara and Kronenberg, Florian and Ketteler, Markus and Wanner, Christoph},
  title     = {Ecto-5 ' -Nucleotidase CD73 (NT5E), vitamin D receptor and FGF23 gene polymorphisms may play a role in the development of calcific uremic arteriolopathy in dialysis patients - Data from the German Calciphylaxis Registry},
  series = {PLoS One},
  volume    = {12},
  journal   = {PLoS One},
  number    = {2},
  doi       = {10.1371/journal.pone.0172407},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171817},
  year      = {2017},
  abstract  = {Introduction: Calciphylaxis/calcific uremic arteriolopathy affects mainly end-stage kidney disease patients but is also associated with malignant disorders such as myeloma, melanoma and breast cancer. Genetic risk factors of calciphylaxis have never been studied before. Methods: We investigated 10 target genes using a tagging SNP approach: the genes encoding CD73/ ecto-5'-nucleotidase (purinergic pathway), Matrix Gla protein, Fetuin A, Bone Gla protein, VKORC1 (all related to intrinsic calcification inhibition), calcium-sensing receptor, FGF23, Klotho, vitamin D receptor, stanniocalcin 1 (all related to CKD-MBD). 144 dialysis patients from the German calciphylaxis registry were compared with 370 dialysis patients without history of CUA. Genotyping was performed using iPLEX Gold MassARRAY(Sequenom, San Diego, USA), KASP genotyping chemistry (LGC, Teddington, Middlesex, UK) or sequencing. Statistical analysis comprised logistic regression analysis with adjustment for age and sex. Results: 165 SNPs were finally analyzed and 6 SNPs were associated with higher probability for calciphylaxis (OR>1) in our cohort. Nine SNPs of three genes (CD73, FGF23 and Vitamin D receptor) reached nominal significance (p< 0.05), but did not reach statistical significance after correction for multiple testing. Of the CD73 gene, rs4431401 (OR = 1.71, 95\%CI 1.08-2.17, p = 0.023) and rs9444348 (OR = 1.48, 95\% CI 1.11-1.97, p = 0.008) were associated with a higher probability for CUA. Of the FGF23 and VDR genes, rs7310492, rs11063118, rs13312747 and rs17882106 were associated with a higher probability for CUA. Conclusion: Polymorphisms in the genes encoding CD73, vitamin D receptor and FGF23 may play a role in calciphylaxis development. Although our study is the largest genetic study on calciphylaxis, it is limited by the low sample sizes. It therefore requires replication in other cohorts if available.},
  language  = {en}
}
@phdthesis{Robubi2007,
  author    = {Robubi, Armin},
  title     = {RAF Kinases: Pathway, Modulation and Modeling},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26953},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2007},
  abstract  = {The Ras/RAF/MEK/ERK cascade is a central cellular signal transduction pathway involved in cell proliferation, differentiation, and survival where RAF kinases are pivotal kinases implicated in cancer. The development of specific irreversible kinase inhibitors is a rewarding but difficult aim. CI-1033 was developed to irreversibly inhibit erbB receptor tyrosine kinases by reacting to the Cys113 residue (p38alpha MAP kinase numbering) of the kinase domain. In this study we tried a similar approach to target the RAF oncoproteins which posses a similar cysteine at position 108 in the hinge region between the small n-lobe and the large c-lobe of the kinase domain. A novel synthetic approach including a lyophilization step allowed us the synthesis of a diphenyl urea compound with an epoxide moiety (compound 1). Compound 1 possessed inhibitory activity in vitro. However our time kinetics experiments and mass spectroscopic studies clearly indicate that compound 1 does not react covalently with the cysteine residue in the hinge region. Moreover, in cell culture experiments, a strong activation of the RAF signaling pathway was observed, an effect which is known from several other RAF kinase inhibitors and is here reported for the first time for a diphenyl urea compound, to which the clinically used unspecific kinase inhibitor BAY 43-9006 (Sorafinib, Nexavar) belongs. Although activation was apparently independent on B- and C-RAF hetero-oligomerization in vitro, in vivo experiments support such a mechanism as the activation did not occur in starved knockout cells lacking either B-RAF or C-RAF. Furthermore, we developed a mathematical model of the Ras/RAF/MEK/ERK cascade demonstrating how stimuli induce different signal patterns and thereby different cellular responses, depending on cell type and the ratio between B-RAF and C-RAF. Based on biochemical data for activation and dephosphorylation, we set up differential equations for a dynamical model of the Ras/RAF/MEK/ERK cascade. We find a different signaling pattern and response result for B-RAF (strong activation, sustained signal) and C-RAF (steep activation, transient signal). We further support the significance of such differential modulatory signaling by showing different RAF isoform expression in various cell lines and experimental testing of the predicted kinase activities in B-RAF, C-RAF as well as mutated versions. Additionally the effect of the tumor suppressor DiRas3 (also known as Noey2 or ARHI) on RAF signaling was studied. I could show that DiRas3 down-regulates the mitogenic pathway by inhibition of MEK, a basis for a refined model of the Ras/RAF/MEK/ERK cascade.},
  subject      = {Systembiologie},
  language  = {en}
}
@phdthesis{Regneri2013,
  author    = {Regneri, Janine},
  title     = {Transcriptional regulation of cancer genes in the Xiphophorus melanoma system},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-82319},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {The Xiphophorus melanoma system is a useful animal model for the study of the genetic basis of tumor formation. The development of hereditary melanomas in interspecific hybrids of Xiphophorus is connected to pigment cell specific overexpression of the mutationally activated receptor tyrosine kinase Xmrk. In purebred fish the oncogenic function of xmrk is suppressed by the molecularly still unidentified locus R. The xmrk oncogene was generated by a gene duplication event from the Xiphophorus egfrb gene and thereby has acquired a new 5' regulatory sequence, which has probably altered the transcriptional control of the oncogene. So far, the xmrk promoter region was still poorly characterized and the molecular mechanism by which R controls xmrk-induced melanoma formation in Xiphophorus still remained to be elucidated. To test the hypothesis that R controls melanoma development in Xiphophorus on the transcriptional level, the first aim of the thesis was to gain a deeper insight into the transcriptional regulation of the xmrk oncogene. To this end, a quantitative analysis of xmrk transcript levels in different Xiphophorus genotypes carrying either the highly tumorigenic xmrkB or the non-tumorigenic xmrkA allele was performed. I was able to demonstrate that expression of the tumorigenic xmrkB allele is strongly increased in malignant melanomas of R-free backcross hybrids compared to benign lesions, macromelanophore spots, and healthy skin. The expression level of the non-tumorigenic xmrkA allele, in contrast, is not influenced by the presence or absence of R. These findings strongly indicate that differential transcriptional regulation of the xmrk promoter triggers the tumorigenic potential of these xmrk alleles. To functionally characterize the xmrk promoter region, I established a luciferase assay using BAC clones containing the genomic regions where xmrk and egfrb are located for generation of reporter constructs. This approach showed for the first time a melanoma cell specific transcriptional activation of xmrkB by its flanking regions, thereby providing the first functional evidence that the xmrk oncogene is controlled by a pigment cell specific promoter region. Subsequent analysis of different deletion constructs of the xmrkB BAC reporter construct strongly indicated that the regulatory elements responsible for the tumor-inducing overexpression of xmrkB in melanoma cells are located within 67 kb upstream of the xmrk oncogene. Taken together, these data indicate that melanoma formation in Xiphophorus is regulated by a tight transcriptional control of the xmrk oncogene and that the R locus acts through this mechanism. As the identification of the R-encoded gene(s) is necessary to fully understand how melanoma formation in Xiphophorus is regulated, I furthermore searched for alternative R candidate genes in this study. To this end, three genes, which are located in the genomic region where R has been mapped, were evaluated for their potential to be a crucial constituent of the regulator locus R. Among these genes, I identified pdcd4a, the ortholog of the human tumor suppressor gene PDCD4, as promising new candidate, because this gene showed the expression pattern expected from the crucial tumor suppressor gene encoded at the R locus.},
  subject      = {Melanom},
  language  = {en}
}
@article{MeinertJessenHufnageletal.2024,
  author    = {Meinert, Madlen and Jessen, Christina and Hufnagel, Anita and Kreß, Julia Katharina Charlotte and Burnworth, Mychal and D{\"a}ubler, Theo and Gallasch, Till and Da Xavier Silva, Thamara Nishida and Dos Santos, Anc{\´e}ly Ferreira and Ade, Carsten Patrick and Schmitz, Werner and Kneitz, Susanne and Friedmann Angeli, Jos{\´e} Pedro and Meierjohann, Svenja},
  title     = {Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner},
  series = {Redox Biology},
  volume    = {70},
  journal   = {Redox Biology},
  doi       = {10.1016/j.redox.2023.103011},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350328},
  year      = {2024},
  abstract  = {The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; Braf\(^{CA}\); Pten\(^{lox/+}\) melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2.},
  language  = {en}
}
@article{Meierjohann2015,
  author    = {Meierjohann, Svenja},
  title     = {Hypoxia independent drivers of melanoma angiogenesis},
  series = {Frontiers in Oncology},
  volume    = {5},
  journal   = {Frontiers in Oncology},
  number    = {120},
  doi       = {10.3389/fonc.2015.00102},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125586},
  year      = {2015},
  abstract  = {Tumor angiogenesis is a process which is traditionally regarded as the tumor's response to low nutrient supply occurring under hypoxic conditions. However, hypoxia is not a pre-requisite for angiogenesis. The fact that even single tumor cells or small tumor cell aggregates are capable of attracting blood vessels reveals the early metastatic capability of tumor cells. This review sheds light on the hypoxia-independent mechanisms of tumor angiogenesis in melanoma.},
  language  = {en}
}
@article{LoddeForschnerHasseletal.2021,
  author    = {Lodde, Georg and Forschner, Andrea and Hassel, Jessica and Wulfken, Lena M. and Meier, Friedegund and Mohr, Peter and K{\"a}hler, Katharina and Schilling, Bastian and Loquai, Carmen and Berking, Carola and H{\"u}ning, Svea and Schatton, Kerstin and Gebhardt, Christoffer and Eckardt, Julia and Gutzmer, Ralf and Reinhardt, Lydia and Glutsch, Valerie and Nikfarjam, Ulrike and Erdmann, Michael and Stang, Andreas and Kowall, Bernd and Roesch, Alexander and Ugurel, Selma and Zimmer, Lisa and Schadendorf, Dirk and Livingstone, Elisabeth},
  title     = {Factors influencing the adjuvant therapy decision: results of a real-world multicenter data analysis of 904 melanoma patients},
  series = {Cancers},
  volume    = {13},
  journal   = {Cancers},
  number    = {10},
  issn      = {2072-6694},
  doi       = {10.3390/cancers13102319},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239583},
  year      = {2021},
  abstract  = {Adjuvant treatment of melanoma patients with immune-checkpoint inhibition (ICI) and targeted therapy (TT) significantly improved recurrence-free survival. This study investigates the real-world situation of 904 patients from 13 German skin cancer centers with an indication for adjuvant treatment since the approval of adjuvant ICI and TT. From adjusted log-binomial regression models, we estimated relative risks for associations between various influence factors and treatment decisions (adjuvant therapy yes/no, TT vs. ICI in BRAF mutant patients). Of these patients, 76.9\% (95\% CI 74-80) opted for a systemic adjuvant treatment. The probability of starting an adjuvant treatment was 26\% lower in patients >65 years (RR 0.74, 95\% CI 68-80). The most common reasons against adjuvant treatment given by patients were age (29.4\%, 95\% CI 24-38), and fear of adverse events (21.1\%, 95\% CI 16-28) and impaired quality of life (11.9\%, 95\% CI 7-16). Of all BRAF-mutated patients who opted for adjuvant treatment, 52.9\% (95\% CI 47-59) decided for ICI. Treatment decision for TT or ICI was barely associated with age, gender and tumor stage, but with comorbidities and affiliated center. Shortly after their approval, adjuvant treatments have been well accepted by physicians and patients. Age plays a decisive role in the decision for adjuvant treatment, while pre-existing autoimmune disease and regional differences influence the choice between TT or ICI.},
  language  = {en}
}
@article{LivingstoneZarembaHornetal.2020,
  author    = {Livingstone, E. and Zaremba, A. and Horn, S. and Ugurel, S. and Casalini, B. and Schlaak, M. and Hassel, J.C. and Herbst, R. and Utikal, J.S. and Weide, B. and Gutzmer, R. and Meier, F. and Koelsche, C. and Hadaschik, E. and Sucker, A. and Reis, H. and Merkelbach-Bruse, S. and Siewert, M. and Sahm, F. and von Deimling, A. and Cosgarea, I. and Zimmer, L. and Schadendorf, D. and Schilling, B. and Griewank, K.G.},
  title     = {GNAQ and GNA11 mutant nonuveal melanoma: a subtype distinct from both cutaneous and uveal melanoma},
  series = {British Journal of Dermatology},
  volume    = {183},
  journal   = {British Journal of Dermatology},
  number    = {5},
  doi       = {10.1111/bjd.18947},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215434},
  pages     = {928 -- 939},
  year      = {2020},
  abstract  = {Background GNAQ and GNA11 mutant nonuveal melanoma represent a poorly characterized rare subgroup of melanoma with a gene mutation profile similar to uveal melanoma. Objectives To characterize these tumours in terms of clinical behaviour and genetic characteristics. Methods Patients with nonuveal GNAQ/11 mutated melanoma were identified from the prospective multicentre tumour tissue registry ADOREG, Tissue Registry in Melanoma (TRIM) and additional cooperating skin cancer centres. Extensive data on patient, tumour and treatment characteristics were collected retrospectively. Targeted sequencing was used to determine tumour mutational burden. Immunohistochemistry staining was performed for programmed death-ligand 1 and BRCA1-associated protein (BAP)1. Existing whole-exome cutaneous and uveal melanoma data were analysed for mutation type and burden. Results We identified 18 patients with metastatic GNAQ/11 mutant nonuveal melanoma. Tumours had a lower tumour mutational burden and fewer ultraviolet signature mutations than cutaneous melanomas. In addition to GNAQ and GNA11 mutations (nine each), six splicing factor 3b subunit 1 (SF3B1), three eukaryotic translation initiation factor 1A X-linked (EIF1AX) and four BAP1 mutations were detected. In contrast to uveal melanoma, GNAQ/11 mutant nonuveal melanomas frequently metastasized lymphatically and concurrent EIF1AX, SF3B1 and BAP1 mutations showed no apparent association with patient prognosis. Objective response to immunotherapy was poor with only one partial response observed in 10 treated patients (10\%). Conclusions Our findings suggest that GNAQ/11 mutant nonuveal melanomas are a subtype of melanoma that is both clinically and genetically distinct from cutaneous and uveal melanoma. As they respond poorly to available treatment regimens, novel effective therapeutic approaches for affected patients are urgently needed. What is already known about this topic? The rare occurrence of GNAQ/11 mutations in nonuveal melanoma has been documented. GNAQ/11 mutant nonuveal melanomas also harbour genetic alterations in EIF1AX, SF3B1 and BAP1 that are of prognostic relevance in uveal melanoma. What does this study add? GNAQ/11 mutant nonuveal melanomas show metastatic spread reminiscent of cutaneous melanoma, but not uveal melanoma. GNAQ/11 mutant nonuveal melanomas have a low tumour mutational burden that is higher than uveal melanoma, but lower than cutaneous melanoma. What is the translational message? Primary GNAQ/11 mutant nonuveal melanomas are a subtype of melanoma that is clinically and genetically distinct from both cutaneous and uveal melanoma. As metastatic GNAQ/11 mutant nonuveal melanomas respond poorly to available systemic therapies, including immune checkpoint inhibition, novel therapeutic approaches for these tumours are urgently needed.},
  language  = {en}
}
@phdthesis{Leikam2012,
  author    = {Leikam, Claudia},
  title     = {Oncogene-induced senescence in melanocytes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-79316},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Melanoma is the most aggressive skin cancer with very limited treatment options. Upon appearance of metastases chemotherapeutics are used to either kill or slow down the growth of cancer cells by inducing apoptosis or senescence, respectively. With melanomas originating from melanocytes, it is vital to elucidate the mechanisms that distinguish senescence induction from proliferation and tumourigenicity. Xmrk (Xiphophorus melanoma receptor kinase), the fish orthologue of the human epidermal growth factor receptor (EGFR), causes highly aggressive melanoma in fish. Using an inducible variant, HERmrk, I showed that high receptor levels result in melanocyte senescence, whereas low and medium expression allows for cell proliferation and tumourigenicity. Mechanistically, HERmrk leads to increased reactive oxygen species (ROS) levels, which trigger a DNA damage response. Consequently, multinucleated, senescent cells develop by both endomitosis and fusion. Furthermore, oncogenic N-RAS (N--RAS61K) induces a similar multinucleated phenotype in melanocytes. In addition, I found that both overexpression of C-MYC and the knockdown of miz­-1 (Myc­-interacting zinc finger protein 1) diminished HERmrk-induced senescence entry. C-MYC prevent ROS induction, DNA damage and senescence, while acting synergistically with HERmrk in conveying tumourigenic features to melanocytes. Further analyses identified cystathionase (CTH) as a novel target gene of Myc and Miz-­1 crucial for senescence prevention. CTH encodes an enzyme involved in the synthesis of cysteine from methionine, thereby allowing for increased ROS detoxification. Even though senescence was thought to be irreversible and hence tumour protective, I demonstrated that prolonged expression of the melanoma oncogene N­-RAS61K in pigment cells overcomes initial OIS by triggering the emergence of tumour-initiating, mononucleated stem-like cells from multinucleated senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis­-resistant and induces fast­-growing, metastatic tumours upon transplantation into nude mice. Our data demonstrate that induction of OIS is not only a cellular failsafe mechanism, but also carries the potential to provide a source for highly aggressive, tumour­-initiating cells.},
  subject      = {Melanom},
  language  = {en}
}
@phdthesis{Laisney2010,
  author    = {Laisney, Juliette Agn{\`e}s Genevi{\`e}ve Claire},
  title     = {Characterisation and regulation of the Egfr/Egfr ligand system in fish models for melanoma},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51369},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Fish of the genus Xiphophorus belong to the oldest animal models in cancer research. The oncogene responsible for the generation of spontaneous aggressive melanoma encodes for a mutated epidermal growth factor receptor (Egfr) and is called xmrk for Xiphophorus melanoma receptor kinase. Xmrk constitutive activation mechanisms and subsequent signaling pathways have already been investigated and charaterized but it is still unknown if Egfr ligands may also play a role in Xmrk-driven melanoma formation. To investigate the potential role of Egfr ligands in Xmrk-driven melanoma, I firstly analyzed the evolution of teleost and tetrapod Egfr/Egfr ligand systems. I especially focused on the analysis on the medaka fish, a closely related species to Xiphophorus, for which the whole genome has been sequenced. I could identify all seven Egfr ligands in medaka and could show that the two teleost-specific Egfr copies of medaka display dissimilar expression patterns in adult tissues together with differential expression of Egfr ligand subsets, arguing for subfunctionalization of receptor functions in this fish. Our phylogenetic and synteny analyses supported the hypothesis that only one gene in the chordate ancestor gave rise to the diversity of Egfr ligands found in vertebrate genomes today. I also could show that the Egfr extracellular subdomains implicated in ligand binding are not evolutionary conserved between tetrapods and teleosts, making the use of heterologous ligands in experiments with fish cells debatable. Despite its well understood and straight-forward process, Xmrk-driven melanomagenesis in Xiphophorus is problematic to further investigate in vivo. Our laboratory recently established a new melanoma animal model by generating transgenic mitf::xmrk medaka fishes, a Xiphophorus closely related species offering many more advantages. These fishes express xmrk under the control of the pigment-cell specific Mitf promoter. During my PhD thesis, I participated in the molecular analysis of the stably transgenic medaka and could show that the Xmrk-induced signaling pathways are similar when comparing Xiphophorus with transgenic mitf::xmrk medaka. These data together with additional RNA expression, protein, and histology analyses showed that Xmrk expression under the control of a pigment cell-specific promoter is sufficient to induce melanoma in the transgenic medaka, which develop very stereotyped tumors, including uveal and extracutaneous melanoma, with early onset during larval stages. To further investigate the potential role of Egfr ligands in Xmrk-driven melanoma, I made use of two model systems. One of them was the above mentioned mitf::xmrk medaka, the other was an in-vitro cell culture system, where the EGF-inducible Xmrk chimera HERmrk is stably expressed in murine melanocytes. Here I could show that HERmrk activation strongly induced expression of amphiregulin (Areg) and heparin-binding EGF-like growth factor (Hbegf) in melanocytes. This regulation was dependent on the MAPK and SRC signaling pathways. Moreover, upregulation of Adam10 and Adam17, the two major sheddases of Egfr ligands, was observed. I also could demonstrate the functionality of the growth factors by invitro analyses. Using the mitf::xmrk medaka model I could also show the upregulation of a subset of ligand genes, namely egf, areg, betacellulin (btc) and epigen (epgn) as well as upregulation of medaka egfrb in tumors from fish with metastatic melanoma. All these results converge to support an Xmrk-induced autocrine Egfr ligand loop. Interestingly, my in-vitro experiments with conditioned supernatant from medaka Egf- and Hbegf-producing cells revealed that not only Xiphophorus Egfrb, but also the pre-activated Xmrk could be further stimulated by the ligands. Altogether, I could show with in-vitro and in-vivo experiments that Xmrk is capable of inducing a functional autocrine Egfr ligand loop. These data confirm the importance of autocrine loops in receptor tyrosine kinase (RTK)-dependent cancer development and show the possibility for a constitutively active RTK to strengthen its oncogenic signaling by ligand binding.},
  subject      = {Schwertk{\"a}rpfling},
  language  = {en}
}
@phdthesis{Koestlin2006,
  author    = {K{\"o}stlin, Sebastian Michael Cosmann},
  title     = {Die Sekretion angiogenetischer Zytokine durch menschliche Melanomzellen unter Hypoxie},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-21305},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {Das maligne Melanom ist ein Tumor der Hautpigmentzellen mit weltweit steigender Inzidenz. Aufgrund seiner fr{\"u}hzeitigen lymphogenen und h{\"a}matogenen Metastasierung z{\"a}hlt das maligne Melanom zu den prognostisch sehr ung{\"u}nstigen Tumorerkrankungen. Nach erfolgter Metastasierung werden mit den derzeitig etablierten Therapieschemata noch keine ausreichenden Prognoseverbesserungen erzielt. Einen m{\"o}glichen neuen Therapieansatz stellt die Blockade der Tumorangiogenese dar. Besondere Bedeutung wird dabei der zyto- bzw. chemokinvermittelten Angiogenese zugemessen. In den letzten Jahren zeigten verschiedene diesbez{\"u}gliche Studien richtungsweisende und erfolgversprechende Ergebnisse. Trotzdem besteht weiterhin hoher Bedarf an Verbesserung des Verst{\"a}ndnisses der zugrundeliegenden Regulationsmechanismen. Ziel der vorliegenden Arbeit war, die Sekretion acht angiogenetisch wirksamer Zyto- und Chemokine in vitro durch hoch- und niedrigmaligne Melanomzellen unter normalen Kulturbedingungen sowie unter Hypoxie, Serum- und Glukosemangel zu erfassen. Diese Stressbedingungen dienten als vereinfachtes in vitro-Modell der Mangelbedingungen, die in schnell wachsenden bzw. Nekrosezonen angrenzenden Tumorarealen vorherrschen. Mittels ELISA wurden die abgegeben Mengen der Zytokine VEGF, b-FGF, Angiogenin, PDGF und TGF-ß sowie der Chemokine IL-8, Gro-\&\#945; und GM-CSF in den Zell{\"u}berst{\"a}nden bestimmt. Dabei zeigten die verschiedenen Melanomzelllinien f{\"u}r alle getesteten Zyto- bzw. Chemokine außer GM-CSF charakteristische Sekretionsverhalten unter bestimmten Kulturbedingungen. Insbesondere unter Hypoxie und nach Reoxigenierung ließen sich signifikante Ver{\"a}nderungen im Sekretionsverhalten der verschiedenen Melanomzelllinien feststellen. Eine signifikante Steigerung in der Freisetzung der Zyto- bzw. Chemokine durch Melanomzellen unter Hypoxie ließ sich nur f{\"u}r VEGF, b-FGF, Angiogenin und IL-8 feststellen. Zudem unterschieden sich hochmaligne Melanomzelllinien signifikant von niedrigmalignen Zelllinien in ihrer Sekretion von VEGF, Angiogenin, PDGF, IL-8 und Gro-\&\#945; unter normalen Kulturbedingungen und unter Hypoxie (Angiogenin, PDGF, IL-8 und Gro-\&\#945;). In weiterf{\"u}hrenden Experimenten wurde das Sekretionsverhalten von normalen Melanozyten, Endothelzellen und Fibroblasten untersucht. Dabei wiesen differenzierte Melanozyten im Vergleich zu den Melanomzellen signifikante Unterschiede in den abgegebenen Zyto-/ Chemokinmengen f{\"u}r VEGF, Angiogenin, PDGF, IL-8 und Gro-\&\#945; unter normalen bzw. hypoxischen Kulturbedingungen auf. Differenzierte Melanozyten unterschieden sich also von Melanomzellen in ihrer Sekretion bei den selben Zyto- bzw. Chemokinen wie niedrigmaligne von hochmalignen Melanomzelllinien (VEGF, Angiogenin, PDGF, IL-8 und Gro-\&\#945;). Im Sekretionsverhalten f{\"u}r VEGF, Angiogenin, IL-8 und Gro-\&\#945; {\"a}hnelten Fibroblasten und Endothelzellen (bzgl. VEGF nur HMEC-1) den Melanomzellen. Der Einfluss dieser vier Zyto- und Chemokine und b-FGF auf das in-vitro-Wachstumsverhalten von Endothelzellen wurde mit einem BrD-U-Proliferationsassay untersucht. Sowohl mikrovaskul{\"a}re (HMEC-1) als auch makrovaskul{\"a}re (HUVEC) Endothelzellen steigerten ihre Proliferation unter dem Einfluss von VEGF, b-FGF, Angiogenin, IL-8 und Gro-\&\#945; signifikant. HMEC-1 reagierten dabei mit einem tendenziell st{\"a}rkeren Ansprechen auf die Stimulation als HUVEC. In weiteren Versuchen zeigten HUVEC eine erh{\"o}hte Sensibilit{\"a}t f{\"u}r Zytokine (insbesondere f{\"u}r b-FGF) unter Serummangelbedingungen, nicht jedoch f{\"u}r Chemokine (IL-8 und Gro-\&\#945;). Am deutlichsten fiel die Proliferationssteigerung unter dem Einfluss der einzelnen Zyto- und Chemokine aus, wenn HUVEC in nonadh{\"a}rentem Zustand stimuliert wurden. Mit den Ergebnissen dieser Arbeit konnte erstmalig bzw. zeitgleich mit anderen Publikationen gezeigt werden, dass Melanomzellen unter Hypoxie nicht nur VEGF, sondern auch Angiogenin und IL-8 deutlich vermehrt sezernieren, dass diese Sekretionssteigerung nach Reoxigenierung weiter anh{\"a}lt und Melanomzellen signifikant von differenzierten Melanozyten unterscheidet. Jedes dieser Zyto- und Chemokine stimulierte die Endothelzellproliferation in vitro. Dabei erh{\"o}hten Serummangel und vor allem initial fehlende Zell-Zellkontakte die Zyto- bzw. Chemokinwirkung. Im Gegensatz zu dem bisher intensiver untersuchten VEGF sezernierten hochmaligne Melanomzellen unter Hypoxie signifikant mehr Angiogenin und IL-8 als niedrigmaligne Melanomzellen. Nur f{\"u}r Angiogenin zeigte sich dar{\"u}ber hinaus eine gegens{\"a}tzliche Sekretionsregulation unter Hypoxie aller Melanomzellen im Vergleich zu normalen Melanozyten. Dies k{\"o}nnte f{\"u}r IL-8 und im Besonderen f{\"u}r Angiogenin auf eine m{\"o}gliche Schl{\"u}sselfunktion in der Melanom-induzierten Angiogenese hindeuten. Inwieweit R{\"u}ckschl{\"u}sse auf die in vivo-Verh{\"a}ltnisse und eine klinische Relevanz zul{\"a}ssig sind, werden weitere Untersuchungen und ggf. Therapiestudien zeigen m{\"u}ssen.},
  language  = {de}
}
@article{KressJessenHufnageletal.2023,
  author    = {Kreß, Julia Katharina Charlotte and Jessen, Christina and Hufnagel, Anita and Schmitz, Werner and Da Xavier Silva, Thamara Nishida and Ferreira Dos Santos, Anc{\´e}ly and Mosteo, Laura and Goding, Colin R. and Friedmann Angeli, Jos{\´e} Pedro and Meierjohann, Svenja},
  title     = {The integrated stress response effector ATF4 is an obligatory metabolic activator of NRF2},
  series = {Cell Reports},
  volume    = {42},
  journal   = {Cell Reports},
  number    = {7},
  doi       = {10.1016/j.celrep.2023.112724},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350312},
  year      = {2023},
  abstract  = {Highlights • The integrated stress response leads to a general ATF4-dependent activation of NRF2 • ATF4 causes a CHAC1-dependent GSH depletion, resulting in NRF2 stabilization • An elevation of NRF2 transcript levels fosters this effect • NRF2 supports the ISR/ATF4 pathway by improving cystine and antioxidant supply Summary The redox regulator NRF2 becomes activated upon oxidative and electrophilic stress and orchestrates a response program associated with redox regulation, metabolism, tumor therapy resistance, and immune suppression. Here, we describe an unrecognized link between the integrated stress response (ISR) and NRF2 mediated by the ISR effector ATF4. The ISR is commonly activated after starvation or ER stress and plays a central role in tissue homeostasis and cancer plasticity. ATF4 increases NRF2 transcription and induces the glutathione-degrading enzyme CHAC1, which we now show to be critically important for maintaining NRF2 activation. In-depth analyses reveal that NRF2 supports ATF4-induced cells by increasing cystine uptake via the glutamate-cystine antiporter xCT. In addition, NRF2 upregulates genes mediating thioredoxin usage and regeneration, thus balancing the glutathione decrease. In conclusion, we demonstrate that the NRF2 response serves as second layer of the ISR, an observation highly relevant for the understanding of cellular resilience in health and disease.},
  language  = {en}
}