Abstract 2050: Tumor stage-dependent transcriptomic signatures of endothelial cells reveal an intense paracrine crosstalk in liver capillarization
Authors: Thomann Stefan , Weiler Sofia , Dittmer Martin , Kazdal Daniel , Marquard Simone , Roessler Stephanie , Sticht Carsten , Gretz Norbert , Mogler Carolin , Ball Claudia , Glimm Hanno , Ryschich Eduard , Schirmacher Peter , Breuhahn Kai 
Published: August 2018

Abstract
Introduction:
The liver blood vessel network, consisting of liver sinusoidal endothelial cells (LSECs) and capillary endothelial cells (CECs), undergoes distinct modifications in the process of liver cancer development. The selective expansion of the CEC compartment is thereby the most prominent modification leading to a change of the predominant endothelial phenotype. An in depth molecular analysis of the dynamic vascular modifications in hepatocellular carcinoma (HCC) is however still missing.
Methods:
An inducible mouse model with hepatocyte-specific expression of constitutively active yes-associated protein (YAPS127A) was used for stage dependent purification of endothelial cells. Cell sorting allowed the subtyping of liver endothelial cells into LSECs (CD31+, CD146+, Lyve-1+) and CECs (CD31+, CD146+, Lyve-1-) followed by their consecutive transcriptomic analysis. Predicted paracrine interactions were functionally tested in the endothelial cell line SVEC4-10. Gene expression data of 242 HCC patients were used to confirm the findings in human HCC (Roessler et al. 2010).
Results
Immunofluorescence revealed a progressive replacement of LSECs by CECs in livers, hyperplastic lesions, and HCC derived from YAPS127A mice. FACS analysis confirmed the selective expansion of CECs from 4±2% in healthy livers to 37±16% in hepatomegaly to 61±30% in tumor-bearing livers. Expression profiling of CECs and LSECs revealed dynamic CEC-selective changes in early and late phases of hepatocarcinogenesis including an enrichment of migration specific pathways. Phylogenetic tree analysis of the gene set “cytokine –cytokine receptor interaction” displayed endothelial cell (EC)- and stage-specific secretion patterns suggesting a dynamic crosstalk between the EC populations. The promigratory role of the identified HGF/c-Met axis was confirmed in vitro by single cell tracking and spheroid sprouting. In vivo the inhibition through the c-Met inhibitor Cabozantinib led to a 67% reduction of CEC sprouting, in line with with decreased tumor cell proliferation. Human HCC gene expression data from 242 HCC patients confirmed the prognostic relevance of an identified 19 gene capillarization signature.
Conclusions
Our results illustrate a dynamic crosstalk between the two major EC populations in the process of liver tumor development, already detectable in early phases of capillarization. The identified HGF/c-Met axis represents an essential signal pathway in the process of arterial branch elongation and its inhibition through clinically relevant c-Met inhibitors may represent a promising approach to perturbate disease-associated capillarization.
References
Weiler SME, et al., Gastroenterology, 2017. 152(8): p. 2037-2051 e22
Roessler S, et al., Cancer Res. 2010 Dec 15;70(24):10202-12
Citation Format: Stefan Thomann, Sofia Weiler, Martin Dittmer, Daniel Kazdal, Simone Marquard, Stephanie Roessler, Carsten Sticht, Norbert Gretz, Carolin Mogler, Claudia Ball, Hanno Glimm, Eduard Ryschich, Peter Schirmacher, Kai Breuhahn. Tumor stage-dependent transcriptomic signatures of endothelial cells reveal an intense paracrine crosstalk in liver capillarization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2050.