96. Jahrestagung der Deutschen Gesellschaft für Pathologie e. V ...

p42 and p27 have not yet been investigated in PCa. Therefore, we aimed
in this study at investigating the role of ETS-1 in PCa cell lines, and whether
the ETS-1 splice variants p42 and p27 are expressed in PCa cell lines.
Methods. We first examined the expression of all 27 ETS family members
using quantitative RT-PCR in androgen-sensitive and insensitive PCa
cell lines. As ETS-1 was found to be highly expressed in the androgeninsensitive
PCa cell lines PC3 and DU-145, we investigated the effect of
blocking ETS-1 in PC3 cells on genes involved in the metastatic cascade
using comprehensive gene expression microarrays, and correlated these
findings with PCa tissues. The expression of the ETS-1 splice variants p42
and p27 was assessed using an anti-ETS-1 antibody directed against the
DNA-binding domain (DBD), and RT-PCR.
Results. Assessment of ETS-1 blockade yielded many genes which are
known to be implicated in PCa. Correlating these genes with findings
from PCa tissues identified 16 genes that are up or down regulated in
healthy compared to tumorous PCa glands. Bioinformatical analysis revealed
that 13/16 of these genes have potential ETS-1 binding sites within
their promoter regions, and 4 were reported to be regulated by members
of the ETS family. Furthermore, our results show for the first time the
novel identification of the ETS-1 splice variants p42 and p27 in both the
androgen-dependent and the androgen-independent PCa cell lines.
Conclusions. Future studies will address the roles of the ETS-1 splice variants
in PCa cell lines and tissues. These findings provide in vitro and
in vivo evidence for the importance of ETS-1 in development and progression
of PCa
SO-063
Serum and prostate cancer tissue signatures of ERG rearrangement
derived from quantitative analysis of the PTEN conditional
knockout mouse proteome
N .J . Rupp1 , I . Cima2 , R . Schiess3 , P .J . Schüffler4 , T . Fuchs5 , N . Fankhauser2 , M .
Kälin6 , S . Gillessen6 , R . Aebersold3 , W . Krek2 , M .A . Rubin7 , H . Moch1 , P .J . Wild1 1University Hospital Zurich, Institute of Surgical Pathology, Zürich, Switzerland,
2ETH Zurich, Institute of Cell Biology, Zürich, Switzerland, 3ETH Zurich,
Institute of Molecular Systems Biology, Zürich, Switzerland, 4ETH Zurich,
Department of Computer Science, Zürich, Switzerland, 5California Institute
of Technology, Pasadena, CA, United States, 6Cantonal Hospital St . Gallen,
Department of Oncology, St . Gallen, Switzerland, 7Weill Cornell Medical
College, Department of Pathology and Laboratory Medicine, New York, NY,
United States
Aims. Applying a systems biology approach to assess serum and tissue
signatures of ERG rearrangement in patients with prostate cancer with
the goal of determining downstream molecular targets for gene fusion
cancers.
Methods. Prostate tissue from a conditional PTEN knockout mouse
model of prostate cancer was investigated, using selective enrichment of
N-glycopeptides and mass spectrometry-based label-free quantification.
Mouse tissue signatures were validated in sera and tissue of mice (n=12)
and humans (n=105) by selected reaction monitoring (SRM), ELISA, and
immunohistochemistry. ERG rearrangement status was assessed using
fluorescence in situ hybridization (FISH) on two independent tissue microarray
based prostatectomy cohorts (n=41, n=348). A Random forest
model was trained and validated to identify serum and tissue signatures
of ERG rearrangement.
Results. A comprehensive PTEN dependent protein catalogue representing
over 700 glycoproteins was established. TMPRSS2-ERG gene fusions
occurred in 41% (17/41) of analyzable prostate cancers of the training
cohort. ERG dependent serum signatures could be found. Predicted serum
signatures were systematically tested on two prostate cancer tissue
microarrays (training and test cohort) using immunohistochemistry for
15 candidate proteins and members of the PI3K/AKT/mTOR pathway.
Conclusions. This is the first study to demonstrate a proteomic signature
of ERG rearrangement prostate cancer. Given the challenges of directly
targeting ETS transcription factors, this study has potential clinical im-
plications providing important insights into future targetable downstream
pathways.
SO-064
Landscape of chromosome number changes during prostate
cancer progression
J . Stomper1 , M . Braun1 , W . Vogel1 , D . Böhm1 , V . Scheble2 , F . Fend3 , S . Perner1 1 2 University Hospital of Bonn, Institute of Pathology, Bonn, University
Hospital of Tübingen, Division of Oncology, Tübingen, 3University Hospital
of Tübingen, Institute of Pathology, Tübingen
Aims. Genetic instability resulting in both aneuploidy and polyploidy is
discussed to be involved in prostate cancer (PCa) development and progression.
However, a complete survey of numerical chromosomal changes
in PCa is lacking so far. The aim of this study was to comprehensively
characterize the ploidy level in PCa with regard to disease progression
via fluorescence in situ hybridization (FISH). Since aneuploidy and aggressive
disease are often associated with increased tumor cell proliferation,
we also assessed the expression of two common mitosis markers
within the same PCa cohort.
Methods. We studied a cohort comprising 186 localized PCa, 75 PCa with
125 corresponding lymph node metastases, and 42 hormone-refractory
distant metastases. Using dual-color FISH, we assessed the cohort for
losses and gains of all 24 chromosomes. Conducting immunohistochemistry
studies with the markers pHH3 and Ki67, we quantified the proliferation
rate within the same cohort.
Results. We observed a sharp and significant increase in aneuploidy with
advancing tumor stage (p