Specific genomic and transcriptomic aberrations in tumors induced by partial hepatectomy of a chronically inflamed murine liver
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Ezra Ella1, Denise Heim2, Evgeniy Stoyanov1, Rona Harari-Steinfeld1, Israel Steinfeld3, Orit Pappo4, Temima Schnitzer Perlman1, Natalie Nachmansson5, Ludmila Rivkin1, Devorah Olam1, Rinat Abramovitch1,5, Henning Wege2, Eithan Galun1 and Daniel Goldenberg1
1 The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
2 Department of Gastroenterology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
3 Computer Science Department, Technion-Israel Institute of Technology, Haifa, Israel
4 Department of Pathology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
5 Magnetic Resonance Imaging/Magnetic Resonance Spectroscopy Laboratory, Human Biology Research Center, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
Daniel Goldenberg, email:
Keywords: HCC, liver regeneration, chronic hepatitis, genomic instability, Crem
Received: August 24, 2014 Accepted: September 24, 2014 Published: September 25, 2014
Resection of hepatocellular carcinoma (HCC) tumors by partial hepatectomy (PHx) is associated with promoting hepatocarcinogenesis. We have previously reported that PHx promotes hepatocarcinogenesis in the Mdr2-knockout (Mdr2-KO) mouse, a model for inflammation-mediated HCC. Now, to explore the molecular mechanisms underlying the tumor-promoting effect of PHx, we compared genomic and transcriptomic profiles of HCC tumors developing in the Mdr2-KO mice either spontaneously or following PHx. PHx accelerated HCC development in these mice by four months. PHx-induced tumors had major chromosomal aberrations: all were amplifications affecting multiple chromosomes. Most of these amplifications were located near the acrocentric centromeres of murine chromosomes. Four different chromosomal regions were amplified each in at least three tumors. The human orthologs of these common amplified regions are known to be amplified in HCC. All tumors of untreated mice had chromosomal aberrations, including both deletions and amplifications. Amplifications in spontaneous tumors affected fewer chromosomes and were not located preferentially at the chromosomal edges. Comparison of gene expression profiles revealed a significantly enriched expression of oncogenes, chromosomal instability markers and E2F1 targets in the post-PHx compared to spontaneous tumors. Both tumor groups shared the same frequent amplification at chromosome 18. Here, we revealed that one of the regulatory genes encoded by this amplified region, Crem, was over-expressed in the nuclei of murine and human HCC cells in vivo, and that it stimulated proliferation of human HCC cells in vitro. Our results demonstrate that PHx of a chronically inflamed liver directed tumor development to a discrete pathway characterized by amplification of specific chromosomal regions and expression of specific tumor-promoting genes. Crem is a new candidate HCC oncogene frequently amplified in this model and frequently over-expressed in human HCC.
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