Page 116 - ebook HCC

PROGRAMME
114 PROGRAMME AND ABSTRACTSAND ABSTRACTS GENEVA, SWITZERLAND EASL HCC SUMMIT 115
114
FEBRUARY 13 - 16, 2014

Poster Board Number B15

FUNCTIONAL CONSEQUENCES OF EPIGENETIC NOTES
REGULATED TUMOUR SUPPRESSOR MIRNA-
449-FAMILY IN HEPATOCELLULAR CARCINOMA

Maria Sandbothe , Reena Buurman , Mareike Bütepage ,
1
1
1
Brigitte Schlegelberger , Britta Skawran 1
1
1 Institute for Cell and Molecular Pathology, Hannover Medical School,
30623 Hannover, Germany
Corresponding author’s e-mail: skawran.britta@mh-hannover.de
Introduction: Chromatin remodeling is a common hallmark in human tumor cells and this
process strongly alters the transcription of many genes and microRNAs (miRNAs). We
could show that histone deacetylases (HDAC1-3) are consistently up-regulated in primary
hepatocellular carcinoma (HCC). Selected miRNAs have been shown to play important
roles in carcinogenesis. Until now, it is largely unknown which miRNA genes are altered
due to histone deacetylation in HCC.
Aims: We hypothesized that the altered expression of miRNAs due to chromatin
remodeling may play a fundamental role in hepatocarcinogenesis.
BASIC POSTER ABSTRACTS A (TSA) and by siRNA silencing of HDAC1-3, respectively, to identify deregulated miRNAs BASIC POSTER ABSTRACTS
Methodology: Therefore, we induced histone acetylation by HDAC inhibitors trichostatin
and their target genes in four HCC cell lines (HepG2, HLE, HLF, and Huh7) and two
immortalized liver cell lines (THLE-2 and THLE-3). Differentially expressed mRNAs and
miRs were identified by expression profiling.

Results: Upon histone acetylation, the tumor suppressor miRNA-449a was reactivated
and its target gene c-MET downregulated, which induced strong effects on proliferation
and survival in HCC. MiR-449a together with miR-449b and miR-449c belongs to the
relatively unknown miR-449 family which is coded in the second intron of the CDC20B
gene. So far, only a few direct targets of miR-449a have been validated. MiR-449b
and miR-449c have not yet been analyzed in depth. The miR-449 family shares seed
sequences and target genes with the p53-inducible miR-34 family. Using qPCR we also
found that miR-449b and miR-449c are significantly up-regulated after HDAC inhibition,
in contrast to the p53-inducible miR-34 family. Interestingly, our first results indicate that
miR-449b and miR-449c reduce proliferation and strongly promotes apoptosis in HCC cell
lines after HDAC inhibition.
Recently, we could show transfection of miR-449a, b and c into the cell lines HLE led to
a significantly reduced expression of BCL9-2 in RNA. BCL9-2 increases the expression
of a subset of canonical Wnt target genes but also regulates genes that are required for
initiation of colon cancer.

Conclusions: In particular we expect that histone deacetylation and many putative target
genes of epigenetically deregulated tumor suppressor miR-449 family can be targeted by
new therapeutic agents.