TY - JOUR A1 - Fischer, Thomas A1 - Hartmann, Oliver A1 - Reissland, Michaela A1 - Prieto-Garcia, Cristian A1 - Klann, Kevin A1 - Pahor, Nikolett A1 - Schülein-Völk, Christina A1 - Baluapuri, Apoorva A1 - Polat, Bülent A1 - Abazari, Arya A1 - Gerhard-Hartmann, Elena A1 - Kopp, Hans-Georg A1 - Essmann, Frank A1 - Rosenfeldt, Mathias A1 - Münch, Christian A1 - Flentje, Michael A1 - Diefenbacher, Markus E. T1 - PTEN mutant non-small cell lung cancer require ATM to suppress pro-apoptotic signalling and evade radiotherapy JF - Cell & Bioscience N2 - Background Despite advances in treatment of patients with non-small cell lung cancer, carriers of certain genetic alterations are prone to failure. One such factor frequently mutated, is the tumor suppressor PTEN. These tumors are supposed to be more resistant to radiation, chemo- and immunotherapy. Results We demonstrate that loss of PTEN led to altered expression of transcriptional programs which directly regulate therapy resistance, resulting in establishment of radiation resistance. While PTEN-deficient tumor cells were not dependent on DNA-PK for IR resistance nor activated ATR during IR, they showed a significant dependence for the DNA damage kinase ATM. Pharmacologic inhibition of ATM, via KU-60019 and AZD1390 at non-toxic doses, restored and even synergized with IR in PTEN-deficient human and murine NSCLC cells as well in a multicellular organotypic ex vivo tumor model. Conclusion PTEN tumors are addicted to ATM to detect and repair radiation induced DNA damage. This creates an exploitable bottleneck. At least in cellulo and ex vivo we show that low concentration of ATM inhibitor is able to synergise with IR to treat PTEN-deficient tumors in genetically well-defined IR resistant lung cancer models. KW - PTEN KW - ATM KW - IR KW - NSCLC KW - radiotherapy KW - cancer KW - DNA-PK KW - PI3K Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-299865 SN - 2045-3701 VL - 12 ER - TY - JOUR A1 - Kreß, Julia Katharina Charlotte A1 - Jessen, Christina A1 - Marquardt, André A1 - Hufnagel, Anita A1 - Meierjohann, Svenja T1 - NRF2 enables EGFR signaling in melanoma cells JF - International Journal of Molecular Sciences N2 - Receptor tyrosine kinases (RTK) are rarely mutated in cutaneous melanoma, but the expression and activation of several RTK family members are associated with a proinvasive phenotype and therapy resistance. Epidermal growth factor receptor (EGFR) is a member of the RTK family and is only expressed in a subgroup of melanomas with poor prognosis. The insight into regulators of EGFR expression and activation is important for the understanding of the development of this malignant melanoma phenotype. Here, we describe that the transcription factor NRF2, the master regulator of the oxidative and electrophilic stress response, mediates the expression and activation of EGFR in melanoma by elevating the levels of EGFR as well as its ligands EGF and TGFα. ChIP sequencing data show that NRF2 directly binds to the promoter of EGF, which contains a canonical antioxidant response element. Accordingly, EGF is induced by oxidative stress and is also increased in lung adenocarcinoma and head and neck carcinoma with mutationally activated NRF2. In contrast, regulation of EGFR and TGFA occurs by an indirect mechanism, which is enabled by the ability of NRF2 to block the activity of the melanocytic lineage factor MITF in melanoma. MITF effectively suppresses EGFR and TGFA expression and therefore serves as link between NRF2 and EGFR. As EGFR was previously described to stimulate NRF2 activity, the mutual activation of NRF2 and EGFR pathways was investigated. The presence of NRF2 was necessary for full EGFR pathway activation, as NRF2-knockout cells showed reduced AKT activation in response to EGF stimulation compared to controls. Conversely, EGF led to the nuclear localization and activation of NRF2, thereby demonstrating that NRF2 and EGFR are connected in a positive feedback loop in melanoma. In summary, our data show that the EGFR-positive melanoma phenotype is strongly supported by NRF2, thus revealing a novel maintenance mechanism for this clinically challenging melanoma subpopulation. KW - EGFR KW - NRF2 KW - NFE2L2 KW - KEAP1 KW - MITF-low KW - TGF-alpha KW - EGF KW - NSCLC KW - HNSC Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-260222 SN - 1422-0067 VL - 22 IS - 8 ER - TY - JOUR A1 - Roesch, J. A1 - Panje, C. A1 - Sterzing, F. A1 - Mantel, F. A1 - Nestle, U. A1 - Andratschke, N. A1 - Guckenberger, M. T1 - SBRT for centrally localized NSCLC - What is too central? JF - Radiation Oncology N2 - Purpose Current guidelines recommend stereotactic body radiotherapy (SBRT) for stage I non-small-cell lung cancer (NSCLC) in medically inoperable patients. There are excellent outcome and toxicity data for SBRT of peripheral lung tumors. However, the discussion on SBRT for centrally located tumors is controversial. This study evaluated current clinical practice regarding SBRT of centrally located lung tumors, to identify common fractionation schedules and commonly accepted contraindications for SBRT. Methods A questionnaire consisting of two parts was introduced at the annual meeting of the DEGRO working group on stereotactic radiotherapy, representing centers in Germany and Switzerland. The first part of the questionnaire covered general information about the centers, whereas the second part specifically addressed SBRT of centrally located lung tumors, using case examples of nine primary NSCLC patients. Reconstructions of a contrast enhanced CT, as well as PET-Imaging for each case were demonstrated to the participants. Results Twenty-six centers participated in the meeting. The majority was academic (73%), participated in interdisciplinary thoracic oncology tumorboards (88%) and offered SBRT for lung tumors (96%). Two centers questioned the indication of SBRT for central lung tumors because of lack of evidence. The majority of centers had experience in SBRT for central lung tumors (88%) and half of the centers reported more than ten cases treated during a median period of five years. Most fractionation schedules used PTV encompassing doses of 48–60 Gy in eight fractions with maximum doses of 125–150%. A clear indication for SBRT treatment was seen by more than 85% of centers in three of the nine patients in whom tumors were small and not closer than 2 cm to the main bronchus. Prior pneumonectomy or immediate adjacency to hilar/mediastinal structures were not considered as contraindications for SBRT. In cases where the tumor exceeded 4 cm in diameter or was located closer than 4 cm to the carina 50–80% of centers saw an indication for SBRT. One case, with a 7 cm tumor reaching to the carina would have been treated with SBRT only by one center. Conclusion Within DEGRO working group on stereotactic radiotherapy, SBRT for small (<4 cm) early stage NSCLC is a common indication, if the minimal distance to the main bronchi is at least 2 cm. The controversy on the treatment of larger and more central tumors will hopefully be solved by ongoing prospective clinical trials. KW - SBRT KW - SABR KW - NSCLC KW - central lung KW - pulmonary toxicity Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167459 VL - 11 IS - 157 ER - TY - JOUR A1 - Mantel, Frederick A1 - Flentje, Michael A1 - Guckenberger, Matthias T1 - Stereotactic body radiation therapy in the re-irradiation situation – a review JF - Radiation Oncology N2 - Although locoregional relapse is frequent after definitive radiotherapy (RT) or multimodal treatments, re-irradiation is only performed in few patients even in palliative settings like e.g. vertebral metastasis. This is most due to concern about potentially severe complications, especially when large volumes are exposed to re-irradiation. With technological advancements in treatment planning the interest in re-irradiation as a local treatment approach has been reinforced. Recently, several studies reported re-irradiation for spinal metastases using SBRT with promising local and symptom control rates and simultaneously low rates of toxicity. These early data consistently indicate that SBRT is a safe and effective treatment modality in this clinical situation, where other treatment alternatives are rare. Similarly, good results have been shown for SBRT in the re-irradiation of head and neck tumors. Despite severe late adverse effects were reported in several studies, especially after single fraction doses >10 Gy, they appear less frequently compared to conventional radiotherapy. Few studies with small patient numbers have been published on SBRT re-irradiation for non-small cell lung cancer (NSCLC). Overall survival (OS) is limited by systemic progression and seems to depend particularly on patient selection. SBRT re-irradiation after primary SBRT should not be practiced in centrally located tumors due to high risk of severe toxicity. Only limited data is available for SBRT re-irradiation of pelvic tumors: feasibility and acceptable toxicity has been described, suggesting SBRT as a complementary treatment modality for local symptom control. KW - Stereotactic body radiotherapy KW - Radiosurgery KW - Re-irradiation KW - Locoregional recurrence KW - Normal tissue tolerance KW - Spinal metastases KW - NSCLC KW - Head and neck cancer KW - Pelvic tumors Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96346 UR - http://www.ro-journal.com/content/8/1/7 ER - TY - THES A1 - Lütkenhaus, Katharina T1 - Tumour development in Raf-driven cancer mouse models T1 - Tumor-Entwicklung in Raf-transgenen Mausmodellen N2 - Metastasis is the cause of death in 90% of cancer-related deaths in men. Melanoma and Non-Small-Cell Lung Cancer (NSCLC) are both tumour types with poor prognosis, lacking appropriate therapeutic possibilities, not least because of their high rate of metastasis. Thus understanding the process of metastasis might unravel therapeutic targets for developing further therapeutic strategies. The generation of a transgenic mouse model expressing B-RafV600E in melanocytes, a mutation that is found in about 60% of all melanoma, would result in an ideal tool to study melanoma progression and metastasis. In this work, a doxycycline-inducible system was constructed for expression of B-RafV600E and transgenic animals were generated, but the expression system has to be improved, since this strategy didn’t give rise to any viable, transgene carrying mice. Furthermore, since it was shown in the work of others that the metastatic behavior of tumour cell lines could be reversed by an embryonic microenvironment and the influence of a tumourigenic microenvironment on melanocytes lead to the acquisition of tumour cell-like characteristics, the question arose, whether B-Raf is as important in melanocyte development as it is in melanoma progression. In this work, the embryonal melanocyte development in B-Raf-deficient and wildtype mouse embryos was examined and there were no differences observed in the localization and number of neural crest stem cells as well as in the localization of the dopachrome-tautomerase positive melanoblasts in the embryos and in cultured neural tube explants. The expression of oncogenic C-Raf in lung epithelial cells has yielded a model for NSCLC giving rise to adenomas lacking spontaneous progression or metastasis. The co-expression of c-Myc in the same cells accelerates the tumour development and gives rise to liver and lymphnode metastases. The expression of c-Myc alone in lung epithelial cells leads to late tumour development with incomplete penetrance. A mutation screen in this work resulted in the observation that a secondary mutation in KRas or LKB1 is necessary for tumour formation in the c-Myc single transgenic animals and suggested metastasis as an early event, since the corresponding metastases of the mutation-prone primary lung tumours were negative for the observed mutations. Furthermore, in this work it was shown that the expression of chicken c-Myc in a non-metastatic NSCLC cell line leads to metastatic clones, showing that c-Myc is sufficient to induce metastasis. Additionally a panel of metastasis markers was identified, that might serve as diagnostic markers in the future. N2 - In 90% der Todesfälle aufgrund von Krebserkrankungen sind Metastasen für den Tod des Patienten verantwortlich. Sowohl Melanom, als auch nicht-kleinzelliges Lungenkarzinom (Non-Small Cell Lung Cancer, NSCLC) sind beides Tumortypen, die eine schlechte Prognose haben und für die sich wenige Therapiemöglichkeiten bieten, nicht zuletzt aufgrund ihrer häufigen Metastasierung. Somit würde ein besseres Verständnis des Metastasierungsprozesses neue therapeutische Angriffspunkte aufdecken und damit die Möglichkeit zur Entwicklung neuer Therapieansätze bieten. Die Entwicklung eines transgenen Mausmodells, in dem B-RafV600E, eine Mutation die man in 60% der Melanompatienten findet, melanocyten-spezifisch exprimiert wird, würde ein geeignetes Werkzeug ergeben, um die Entstehung und die Metastasierung von Melanom zu untersuchen. Im Rahmen dieser Arbeit wurde ein Konstrukt zur Doxycyclin-abhängingen Expression von B-RafV600E erzeugt und mit diesem wurden transgene Tiere generiert. Da dieser Ansatz nicht zu lebensfähigen, das Transgen tragenden Linien führte, muss das Expressionssystem weiter verbessert werden. Da in der Arbeit von anderen gezeigt wurde, dass das metastasierende Verhalten von Tumor-Zelllinien durch eine embryonale Mikroumgebung aufgehoben werden konnte, und dass der Einfluss einer tumorähnlichen Mikroumgebung in Melanocyten zur Erlangung von Tumorzell-Charakteristika führte, kam die Frage auf, ob B-Raf eine ähnlich wichtige Rolle in der Entwicklung von Melanocyten wie in der Entstehung von Melanomen spielt. Im Rahmen dieser Arbeit wurde die embryonale Melanocytenentwicklung in B-Raf-defizienten sowie in wildtypischen Mausembryonen untersucht. Es konnten keine Unterschiede in der Lokalisation und Anzahl von Stammzellen des Neuralrohres und in der Lokalisation von Dopachrome-tautomerase positiven Melanoblasten in den Embryonen und in kultivierten Explantaten des Neuralrohres festgestellt werden. Die Expression von oncogenem C-Raf in Lungenepithelzellen von Mäusen ist ein Modell für NSCLC und führt zur Ausbildung von Adenomen ohne spontane Weiterentwicklung oder Metastasen. Die Koexpression von C-Raf mit c-Myc in denselben Zellen beschleunigt die Entwicklung von Tumoren und führt zu Metastasen in Leber und Lymphknoten. Die Expression von c-Myc alleine in Lungenepithelzellen führt zu einer verspäteten Entwicklung von Tumoren mit nicht vollständiger Penetranz. Ein Screening für Mutation im Rahmen dieser Arbeit führte zu der Beobachtung, dass Sekundärmutationen in KRas oder LKB1 für die Tumorentwicklung in den c-Myc transgenen Tieren notwendig sind und dass die Metastasierung ein frühes Ereignis zu seien scheint, da die zugehörigen Metastasen in Leber und Lymphknoten im Gegensatz zum Primärtumor in der Lunge keine Mutationen in diesen Genen trugen. Desweiteren wurde in dieser Arbeit gezeigt, dass die Expression von avianem c-Myc in einer nicht-metastasierenden NSCLC Zelllinie zu metastasierenden Klonen führte, was zeigt, dass c-Myc ausreichend ist um Metastasierung auszulösen. Zusätzlich wurde eine Reihe von Markern für Metastasen identifiziert, die in Zukunft als diagnostische Marker Verwendung finden könnten. KW - Raf KW - Melanom KW - Metastase KW - Lungenkrebs KW - Raf KW - Myc KW - NSCLC KW - metastasis KW - Raf KW - Myc Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48332 ER -