Z Gastroenterol 2018; 56(01): E2-E89
DOI: 10.1055/s-0037-1612773
Poster Visit Session IV Tumors, Liver Surgery and Transplantation – Saturday, January 27, 2018, 8:30am – 9:15am, Foyer area West Wing
Georg Thieme Verlag KG Stuttgart · New York

The role of mutations in NOTCH signaling pathway components in liver carcinogenesis

S Luiken
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
,
M Bieg
2   German Cancer Research Center, Division of Applied Bioinformatics, Heidelberg
,
B Goeppert
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
,
B Brors
2   German Cancer Research Center, Division of Applied Bioinformatics, Heidelberg
,
S Pusch
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
3   Clinical Cooperation Unit Neuropathology, German Cancer Research Center, Heidelberg
,
T Longerich
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
,
P Schirmacher
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
,
S Roessler
1   Heidelberg University Hospital, Institute of Pathology, Heidelberg
› Author Affiliations
Further Information

Publication History

Publication Date:
03 January 2018 (online)

 

Background:

The Notch pathway is an evolutionary conserved signaling pathway that is known to play a pivotal role in appropriate liver development and regeneration. Thereby, the Notch pathway controls cell fate decisions of bipotential liver progenitor cells promoting a biliary lineage commitment rather than hepatic differentiation. Furthermore, aberrant Notch signaling is also a potential driver of liver inflammation, formation and progression of hepatocellular (HCC) as well as cholangiocellular carcinoma (CCA). Previous studies mainly focused on the expression level of the Notch receptors (NOTCH1 – 4) and their ligands (DLL1/3/4, JAG1/2). However, little is known regarding mutational effects within components of the Notch pathway and their relevance in liver cancer.

Results:

In a whole exome sequencing approach of 57 human HCC samples, we discovered 19 amino acid-altering mutations in 15 different Notch pathway genes which were confirmed by Sanger sequencing to be somatic. In summary, 24.6% of patients (14 of 57) presented at least one mutation in one of the included Notch pathway components (NOTCH1/3/4, DLL1, DTX1/3/4, HES5, DVL2, LFNG, NUMB, NCSTN, DMXL2, GXYLT2). Consistently, 30% of HCC patients contain a tumor-associated hyper-activated Notch pathway. Using multiple online tools to predict the effect of the mutations on protein function and tumor relevance, we observed that HES5-Arg31Gly mutation ranked highest. In order to test, whether HES5 is activated by Notch in HCC cells, we generated cell lines with inducible expression of NOTCH1 or NOTCH3 intracellular domain and found that HES5 but not HES1 is strongly activated in several HCC cell lines. Furthermore, induction of HES5 in an inducible cell line resulted in increased expression of WNT11, VIM, NOTCH3 and endogenous HES5. Interestingly, HES5-Arg31Gly failed to induce the expression of the here tested target genes. We also observed that HES5 negatively regulated HES1 expression and that HES5-Arg31Gly had no effect on HES1 mRNA levels. Our preliminary mouse experiments indicate that hydrodynamic transduction of transposons expressing MYC and HES5 leads to increased tumor formation compared to MYC alone. Moreover, Zhu et al. showed that HES5 is upregulated in human HCC and high HES5 expression correlates with worse patient outcome. In current experiments, we aim to elucidate the oncogenic role of wildtype and mutant HES5 in HCC cell lines and mouse models.

Conclusion:

Here, we identified somatic mutations in Notch pathway genes in 24.6% of HCC patients. Our analyses suggest that HES5 has oncogenic properties and that HES5-Arg31Gly fails to regulate HES5 target genes.