TY  - JOUR
A1  - Haferkamp, Sebastian
A1  - Hesbacher, Sonja
A1  - Weyandt, Gerhard
A1  - Vetter-Kauczok, Claudia S.
A1  - Becker, Jürgen C.
A1  - Motschenbacher, Stephanie
A1  - Wobser, Marion
A1  - Maier, Melissa
A1  - Schmid, Corinna P.
A1  - Houben, Roland
T1  - p53 regulation by TRP2 is not pervasive in melanoma
N2  - p53 is a central tumor suppressor protein and its inhibition is believed to be a prerequisite for cancer development. In approximately 50% of all malignancies this is achieved by inactivating mutations in the p53 gene. However, in several cancer entities, including melanoma, p53 mutations are rare. It has been recently proposed that tyrosinase related protein 2 (TRP2), a protein involved in melanin synthesis, may act as suppressor of the p53 pathway in melanoma. To scrutinize this notion we analyzed p53 and TRP2 expression by immunohistochemistry in 172 melanoma tissues and did not find any correlation. Furthermore, we applied three different TRP2 shRNAs to five melanoma cell lines and could not observe a target specific effect of the TRP2 knockdown on either p53 expression nor p53 reporter gene activity. Likewise, ectopic expression of TRP2 in a TRP2 negative melanoma cell line had no impact on p53 expression. In conclusion our data suggest that p53 repression critically controlled by TRP2 is not a general event in melanoma.
KW  - melanomas
KW  - melanoma cell
KW  - cell staining
KW  - histology
KW  - reporter genes
KW  - apoptosis
KW  - immunohistochemistry techniques
KW  - tumor suppressor genes
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111396
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  -