Abstract Book 2010 - CIMT Annual Meeting

088 Schmid | Tumor biology & interaction with the immune system
Development of a novel transgenic mouse model for melanoma
Beate Schmid 1 , Danielle Arnold-Schild 1 , Mustafa Diken 2 , Christine Tertilt 1,3 , Markus Radsak
4 , Hansjörg Schild 1
1 Johannes Gutenberg University Medical Center, Dept. of Immunology,
Langenbeckstr. 1, 55131 Mainz, Germany
2 Johannes Gutenberg University Medical Center, III. Dept. Medicine, Hematology/Oncology,
Obere Zahlbacher Str. 63, 55131 Mainz, Germany
3 Johannes Gutenberg University Medical Center, Dept. of Pediatrics,
Langenbeckstr. 1, 55131 Mainz, Germany
4 Johannes Gutenberg University Medical Center, III. Dept. Medicine, Hematology/Oncology,
Langenbeckstr. 1, 55131 Mainz, Germany
Novel cancer therapeutics need to be evaluated
in animal models before application in humans.
Models using transplanted tumor cell lines may lead
to tumor growth in mice, but their characteristics
often substantially differ from autochthonously developing
tumors in vivo. This may be important for
the development of tumor tolerance and the establishment
of anti-tumor immunity. Therefore, new
animal models are needed where the endogenous
development of tumors can be controlled and manipulated.
To create an autochthonous tumor model
we generated BAC transgenic mice with inducible
expression of the melanoma oncogenes BrafV600E,
Cdk4R24C and Mitf under the control of the melanocyte
specific tyrosinase promoter. Furthermore
we introduced the gene for firefly luciferase for monitoring
of oncogene expression by bioluminescent
imaging. Transcription of these genes is controlled
by the tamoxifen inducible recombinase CreERT2
also expressed specifically in melanocytes. In vitro
studies of C22 cells transfected with the vector
pcDNA3.1 containing the oncogene-luciferase expression
construct indeed showed an increase in
Braf and Cdk4 expression by western blot as well
as luciferase activity indicating the functionality
of the construct. The pronucleus injection of the
final BAC construct resulted in three founders confirmed
by PCR and southern blot analysis. Analysis
of these mouse lines in vivo by bioluminescent
imaging showed some base line luciferase activity
in one mouse line indicating leakiness of the trans-
genic construct. However, tamoxifen treatment
greatly enhanced the luciferase activity indicating
that our construct is operating as intended. Further
analyses to characterize the tissue specific transgene
expression and kinetics of tumor development
are ongoing. After completion of these basic studies
this novel mouse model will be a valuable tool for
the preclinical assessment of novel cancer therapeutics.
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