TY  - JOUR
A1  - Leikam, C
A1  - Hufnagel, AL
A1  - Otto, C
A1  - Murphy, DJ
A1  - Mühling, B
A1  - Kneitz, S
A1  - Nanda, I
A1  - Schmid, M
A1  - Wagner, TU
A1  - Haferkamp, S
A1  - Bröcker, E-B
A1  - Schartl, M
A1  - Meierjohann, S
T1  - In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells
JF  - Cell Death and Disease
N2  - 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.
KW  - reactive oxygen
KW  - human melanoma
KW  - MITF
KW  - cancer
KW  - skin
KW  - DNA damage
KW  - kappa-B
KW  - oncogene-induced senescence
KW  - cellular senescence
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148718
VL  - 6
IS  - e1711
ER  - 
TY  - JOUR
A1  - Hohenauer, Tobias
A1  - Berking, Carola
A1  - Schmidt, Andreas
A1  - Haferkamp, Sebastian
A1  - Senft, Daniela
A1  - Kammerbauer, Claudia
A1  - Fraschka, Sabine
A1  - Graf, Saskia Anna
A1  - Irmler, Martin
A1  - Beckers, Johannes
A1  - Flaig, Michael
A1  - Aigner, Achim
A1  - Höbel, Sabrina
A1  - Hoffmann, Franziska
A1  - Hermeking, Heiko
A1  - Rothenfusser, Simon
A1  - Endres, Stefan
A1  - Ruzicka, Thomas
A1  - Besch, Robert
T1  - The neural crest transcription factor Brn3a is expressed in melanoma and required for cell cycle progression and survival
JF  - EMBO Molecular Medicine
N2  - 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.
KW  - oncogene-induced senescence
KW  - BRN-3A
KW  - DNA
KW  - DNA damage
KW  - tumourigenesis
KW  - P53
KW  - in-vitro
KW  - neural crest factors
KW  - family
KW  - apoptosis
KW  - melanoma
KW  - BRAF mutations
KW  - domain
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122193
SN  - 1757-4676
VL  - 5
ER  -