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

and desmoplastic reaction are different. SNAIT revealed more cohesiveness
and lower vascular spreading than CRAIT. CXDX2 and CK20
expressions are identically. CK7 and Synaptophysin demonstrated no reliable
differences, even though SNAIT are more often positive as CRAIT.
Mutations analyses exhibited for 30 SNAIT negative results for EGFR.
One case (1/30) only was positive for K-RAS Mutation (Mut g/g 12 Asp.)
and only one case for b-rafV600E, whereas about 60% of cases revealed a
p53 expression mostly in Exon 5, thrice in Exon 8/9.
Conclusions. Subtile studies detect dissimilarities of CRAIT and SNAIT.
However, if in a given case the discrimination is problematic, the molecular
status can be helpful. Molecular results reflect the different pathway
of these similar tumors. Hence it follows, that a morphologic mimicry
does not imply biologic relatedness!
SA-P-044
The G protein coupled-receptor GPR81 is upregulated in colorectal
carcinomas with KRAS wild type genotype
A .-K . Wenke1 , K . Balschun1 , C . Röcken1 1Christian-Albrechts-University Kiel, Department of Pathology, Kiel
Aims. The KRAS genotype is essential for the response to a targeted therapy
in advanced colorectal carcinoma (CRC). Several studies revealed
that only patients with wild type KRAS (KRASwt) benefit from a therapy
with monoclonal antibodies like cetuximab (Erbitux®) and panitumumab
(Vectibix®) which block the intracellular cascade following
activation of the epidermal-growth-factor-receptor (EGFR). Therefore,
the identification of new therapeutic targets is very important. G protein
coupled-receptors (GPCRs) are interesting candidates, since they
are known to transactivate the EGFR signaling pathway. The aim of this
study was the identification and functional analysis of GPCRs which are
differentially expressed in colorectal carcinoma dependent on KRAS genotype.
Methods. mRNA expression of KRASwt tumor and non-tumor tissue of
eight patients was compared to eight cases with KRASmut tumor and
non-tumor tissue using Affymetrix GeneChip® Human Gene 1.1 ST Arrays.
Differential gene expression of interesting candidate genes was validated
by quantitative RT-PCR and immunohistochemical staining of a
validation series of 46 colorectal carcinomas (28 KRASwt, 18 KRASmut
tumors).
Results. We found 32 differentially regulated GPCRs comparing gene
expression of normal and tumor colon tissue. An increased expression
of GPR81, NIACR1, NIACR2, GPR143, HTR1D and LGR5 in carcinoma
tissue could be confirmed. However, GPR81 is the only receptor being
significantly differentially regulated according to the KRAS genotype of
the tumor.
Conclusions. Our expression analyses demonstrate a correlation of
GPR81 expression with the KRAS genotype in CRC. The functional role
of GPR81 in colorectal carcinogenesis has to be analyzed in further studies.
Additionally, a comprehensive expression analysis on an enlarged
patient series of 2000 cases will show if GPR81 could serve as a proper
therapeutic target or a potential prognostic marker for colorectal carcinoma.
SA-P-045
Polysomy and amplification status of EGFR in primary colorectal
cancer and in matched metastases
C . Giedl1 , A . Kiesl1 , F . Hofstädter1 , W . Dietmaier1 1University of Regensburg, Institute of Pathology, Regensburg
Aims. There is a need for predictive biomarkers that identify patients
most likely to respond to targeted treatment. EGFR is an important target
for therapies using monoclonal antibodies and tyrosine kinase inhibitors
(TKIs). We analyzed the polysomy and amplification status of
EGFR in primary colorectal cancers, matched metastases, and looked if
differences in the polysomy and amplification status exist which could
influence targeted therapies.
Methods. 54 primary colorectal cancers and 94 metastases of primary
colorectal cancers were analyzed. The EGFR gene copy number was evaluated
by fluorescence in situ hybridization (FISH). Specimens that have
>40% of cells displaying ≥4 copies of the EGFR signal and specimens that
showed an EGFR to CEP7 ratio ≥2 over all scored nuclei were counted
as EGFR FISH-positive. Also specimens with gene clusters (≥4 spots) in
≥10% of tumor cells and specimens with at least 15 copies of the EGFR
signals in ≥10% of tumor cells were counted as EGFR FISH-positive.
Results. A high EGFR polysomy was found in 18 of the 54 primary colorectal
cancers (33.3%) and in 30 of the 94 evaluated syn-or metachronous
metastases in lymph nodes, liver, lung, ovary, peritoneum, skin, brain,
urinary bladder and bone (31.9%). In contrast no real gene clusters and
real EGFR amplifications were found. 18 of 22 matched metastases from
EGFR FISH-positive primary colorectal cancers were also EGFR FISHpositive
(81.8%) showing a high accordance but no complete congruence.
In addition, 1 case showed an EGFR FISH-negative primary colorectal
cancer and a EGFR FISH-positive metastasis.
Conclusions. The discrepancy of EGFR polysomy and amplification
status found in primary colorectal cancers and matched metastases demonstrate
a tumor-metastases diversity, which should be considered in
patients’ treatment regime.
SA-P-046
Detection of KRAS and BRAF mutation in Chinese colorectal carcinoma
patients by pyrosequencing
M . Ye1 , J . Chen1 , M . Lai1 1Zhejiang University, School of Medicine, Hangzhou, China
Aims. KRAS and BRAF mutation status were reported to be a possible
biomarker which response to EGFR antibody chemotherapy in colorectal
carcinoma. Recently, pyrosequencing is proved as a powerful and
convenient method for KRAS and BRAF mutation detection by a lot of
groups in the U. S. and Europe. In China, there are rare labs or groups
to setting up pyrosequencing method for molecular clinical diagnosis.
Methods. 180 FFPE CRC tissue samples were microdissected to obtain
the tumor cells and remove the stroma contents, then the genomic DNA
was extracted from these samples by routine method. A pyrosequencing
assay based on PCR was designed to characterize KRAS codon 12, 13 and
BRAF codon 600 mutation status by Pyromark Q24. The SW620 and
HT29 CRC cell lines were used as controls in pyrosequencing.
Results. Mutation status of KRAS codon 12 was identified in 65/180
(36.11%) samples, among them,1 sample was 34G>A mutation(0.56%), 2
samples were 34G>C mutation(1.11%) , 2 samples were 34G>T mutation
(1.11%), 29 samples were 35G>A mutation (16.11%), 1 was 35G>C mutation
(0.56%) and 30 were 35G>T mutation (16.67%). 20 samples were mutant
for KRAS codon 13 (11.11%)with the nucleotide change 38G>A for 19 samples
(10.56%) and 1 for 38G>A (0.56%). 16/180 tumors harbored a mutation
of 1799T>A in BRAF codon 600 mutation (8.89%).
Conclusions. The KRAS and BRAF mutant frequencies of the 180 FFPE
tissue samples are generally consistent with those recently reported. Although
the amount of samples was limited, more CRC patients are needed
to be detected in the year future.
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