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  - 
TY  - JOUR
A1  - Djuzenova, Cholpon S.
A1  - Elsner, Ines
A1  - Katzer, Astrid
A1  - Worschech, Eike
A1  - Distel, Luitpold V.
A1  - Flentje, Michael
A1  - Polat, Bülent
T1  - Radiosensitivity in breast cancer assessed by the histone γ-H2AX and 53BP1 foci
JF  - Radiation Oncology
N2  - Background

High expression of constitutive histone γ-H2AX, a sensitive marker of DNA damage, might be indicative of defective DNA repair pathway or genomic instability. 53BP1 (p53-binding protein 1) is a conserved checkpoint protein with properties of a DNA double-strand breaks sensor. This study explores the relationship between the clinical radiosensitivity of tumor patients and the expression/induction of γ-H2AX and 53BP1 in vitro.

Methods

Using immunostaining, we assessed spontaneous and radiation-induced foci of γ-H2AX and 53 BP1 in peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=57) undergoing radiotherapy (RT). Cells from apparently healthy donors (n=12) served as references.

Results

Non-irradiated cells from controls and unselected BC patients exhibited similar baseline levels of DNA damage assessed by γ-H2AX and 53BP1 foci. At the same time, the γ-H2AX assay of in vitro irradiated cells revealed significant differences between the control group and the group of unselected BC patients with respect to the initial (0.5 Gy, 30 min) and residual (2 Gy, 24 h post-radiation) DNA damage. The numbers of 53BP1 foci analyzed in 35 BC patients were significantly higher than in controls only in case of residual DNA damage. A weak correlation was found between residual foci of both proteins tested. In addition, cells from cancer patients with an adverse acute skin reaction (grade 3) to RT showed significantly increased radiation-induced γ-H2AX foci and their protracted disappearance compared to the group of BC patients with normal skin reaction (grade 0–1). The mean number of γ-H2AX foci after 5 clinical fractions was significantly higher than that before RT, especially in clinically radiosensitive patients.

Conclusions

The γ-H2AX assay may have potential for screening individual radiosensitivity of breast cancer patients.
KW  - DNA damage
KW  - DNA repair
KW  - Peripheral blood lymphocytes
KW  - Radiosensitivity
KW  - DNS-Schädigung
KW  - DNS-Reparatur
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96110
UR  - http://www.ro-journal.com/content/8/1/98
ER  -