@article{LeikamHufnagelOttoetal.2015,
  author    = {Leikam, C and Hufnagel, AL and Otto, C and Murphy, DJ and M{\"u}hling, B and Kneitz, S and Nanda, I and Schmid, M and Wagner, TU and Haferkamp, S and Br{\"o}cker, E-B and Schartl, M and Meierjohann, S},
  title     = {In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells},
  series = {Cell Death and Disease},
  volume    = {6},
  journal   = {Cell Death and Disease},
  number    = {e1711},
  doi       = {10.1038/cddis.2015.71},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148718},
  year      = {2015},
  abstract  = {Oncogenic signaling in melanocytes results in oncogene-induced senescence (OIS), a stable cell-cycle arrest frequently characterized by a bi-or multinuclear phenotype that is considered as a barrier to cancer progression. However, the long-sustained conviction that senescence is a truly irreversible process has recently been challenged. Still, it is not known whether cells driven into OIS can progress to cancer and thereby pose a potential threat. Here, we show that prolonged expression of the melanoma oncogene N-RAS\(^{61K}\) in pigment cells overcomes OIS by triggering the emergence of tumor-initiating mononucleated stem-like cells from senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis-resistant and induces fast growing, metastatic tumors. Our data describe that differentiated cells, which are driven into senescence by an oncogene, use this senescence state as trigger for tumor transformation, giving rise to highly aggressive tumor-initiating cells. These observations provide the first experimental in vitro evidence for the evasion of OIS on the cellular level and ensuing transformation.},
  language  = {en}
}
@article{HohenauerBerkingSchmidtetal.2013,
  author    = {Hohenauer, Tobias and Berking, Carola and Schmidt, Andreas and Haferkamp, Sebastian and Senft, Daniela and Kammerbauer, Claudia and Fraschka, Sabine and Graf, Saskia Anna and Irmler, Martin and Beckers, Johannes and Flaig, Michael and Aigner, Achim and H{\"o}bel, Sabrina and Hoffmann, Franziska and Hermeking, Heiko and Rothenfusser, Simon and Endres, Stefan and Ruzicka, Thomas and Besch, Robert},
  title     = {The neural crest transcription factor Brn3a is expressed in melanoma and required for cell cycle progression and survival},
  series = {EMBO Molecular Medicine},
  volume    = {5},
  journal   = {EMBO Molecular Medicine},
  issn      = {1757-4676},
  doi       = {10.1002/emmm.201201862},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122193},
  pages     = {919-934},
  year      = {2013},
  abstract  = {Pigment cells and neuronal cells both are derived from the neural crest. Here, we describe the Pit-Oct-Unc (POU) domain transcription factor Brn3a, normally involved in neuronal development, to be frequently expressed in melanoma, but not in melanocytes and nevi. RNAi-mediated silencing of Brn3a strongly reduced the viability of melanoma cell lines and decreased tumour growth in vivo. In melanoma cell lines, inhibition of Brn3a caused DNA double-strand breaks as evidenced by Mre11/Rad50-containing nuclear foci. Activated DNA damage signalling caused stabilization of the tumour suppressor p53, which resulted in cell cycle arrest and apoptosis. When Brn3a was ectopically expressed in primary melanocytes and fibroblasts, anchorage-independent growth was increased. In tumourigenic melanocytes and fibroblasts, Brn3a accelerated tumour growth in vivo. Furthermore, Brn3a cooperated with proliferation pathways such as oncogenic BRAF, by reducing oncogene-induced senescence in non-malignant melanocytes. Together, these results identify Brn3a as a new factor in melanoma that is essential for melanoma cell survival and that promotes melanocytic transformation and tumourigenesis.},
  language  = {en}
}