@article{HaferkampHesbacherWeyandtetal.2014, author = {Haferkamp, Sebastian and Hesbacher, Sonja and Weyandt, Gerhard and Vetter-Kauczok, Claudia S. and Becker, J{\"u}rgen C. and Motschenbacher, Stephanie and Wobser, Marion and Maier, Melissa and Schmid, Corinna P. and Houben, Roland}, title = {p53 regulation by TRP2 is not pervasive in melanoma}, doi = {10.1371/journal.pone.0087440}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111396}, year = {2014}, abstract = {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.}, 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} }