studies

1176A AASLD ABSTRACTS HEPATOLOGY, October, 2015
The following authors have nothing to disclose: Takehisa Watanabe, Satomi
Fujie, Youko Yoshimaru, Katsuya Nagaoka, Hiroko Setoyama, Kotaro Fukubayashi,
Masakuni Tateyama, Hideaki Naoe, Jiro Fujimoto, Motohiko Tanaka
1988
DDB2 loss protects mice from H-ras12V-driven HCCs
Dragana Kopanja, Akshay Pandey, Shuo Huang, Damiano Fantini,
Pradip Raychaudhuri; Biochemistry and Molecular Genetics,
University of Illinois at Chicago, Chicago, IL
DDB2 (Damaged DNA-binding protein (DDB)-2,) is a protein
encoded by the nucleotide excision repair (NER) gene xeroderma
pigmentosum group E (XPE). DDB2 is involved in early
steps of NER and in DNA damage-induced apoptosis. Interestingly,
DDB2 also acts as transcriptional repressor and regulates
expression of antioxidant genes MnSOD and Catalase. Furthermore,
DDB2 represses transcription of EMT-inducing factors
Snail, VEGF and ZEB1, and its loss in high grade colon cancers
promotes metastasis by promoting EMT. Moreover, DDB2
-/- mice develop spontaneous tumors at higher frequency than
wt mice, suggesting that it can act as a tumor suppressor. In
this study, we investigated role of DDB2 in liver cancer. Since
Ras-signaling pathway is found to be ubiquitously activated
in human hepatocellular carcinoma (HCC) through epigenetic
silencing of the Ras-regulators, we used mice that express
H-ras12V under control of albumin promoter. Male mice of
this strain develop liver tumors at age of 8-9 months with penetrance
of almost 100%. We crossed H-ras12V mice with DDB2
knockout mice (DDB2 -/-). Surprisingly, in that model of HCCs,
DDB2 deletion protects mice from liver tumor development. We
observed lower number of liver tumor nodules in DDB2 knockout
H-ras12V mice compared to the DDB2 +/+ H-ras12V mice.
Moreover, unlike in colon cancer, DDB2 loss does not induce
metastasis of H-ras12V driven liver cancer. To understand why
DDB2 -/- H-ras12V mice develop lower number of tumor nodules
compared to DDB2 +/+ H-ras12V, we harvested livers
from 5 months old male mice of both genotypes. We found
that DDB2 null livers have increased expression of MnSOD
and decreased accumulation of ROS. Therefore, an impairment
of oxidative damage could explain observed reduction in the
number of H-ras12V-driven HCC nodules in DDB2 -/- mice.
Since DDB2 is considered to act as a tumor suppressor, our
finding that DDB2 loss protects mice from H-ras12V-driven liver
tumor development is interesting and surprising, and it demonstrates
that depending of the context of tumor development
DDB2 can either inhibit or promote tumorigenesis.
Disclosures:
The following authors have nothing to disclose: Dragana Kopanja, Akshay Pandey,
Shuo Huang, Damiano Fantini, Pradip Raychaudhuri
1989
Inflammation contributes to hepatocarcinogenesis
through an acceleration of transcription-coupled mutagenesis
Tomonori Matsumoto, Norihiro Nishijima, Tsutomu Chiba, Hiroyuki
Marusawa; Department of Gastroenterology and Hepatology,
Graduate School of Medicine, Kyoto University, Kyoto, Japan
Chronic inflammation plays important roles in cancer development
in association with various intrinsic mediators including
cytokines and growth factors, however, accumulation of
genetic alterations in tumor-related genes is a critical step
required for malignant transformation. Activation-induced cytidine
deaminase (AID), an intrinsic DNA mutator enzyme, has
been demonstrated to be aberrantly elicited in epithelial cells
by inflammatory stimulation, and to contribute to tumorigenesis
by inducing genetic aberrations. To gain further insight into the
inflammation-mediated genotoxic events required for carcinogenesis,
we examined the role of chronic inflammation in the
emergence of genetic aberrations in the liver with constitutive
AID expression. Treatment with thioacetamide (TAA) at lowdose
concentrations caused minimal hepatic inflammation in
both wild-type and AID transgenic (Tg) mice. Surprisingly, all
the TAA-treated AID Tg mice developed multiple liver cancers in
6 months, while wild-type mice with TAA or AID Tg mice without
TAA rarely develop tumors during the same periods. Whole
exome sequencing demonstrated the enhanced accumulation
of somatic mutations in various genes in the liver of TAA-treated
AID Tg mice. Microarray analyses showed the transcriptional
upregulation of several putative tumor suppressor genes under
hepatic inflammatory conditions induced by TAA treatment.
Additional quantitative reverse transcription-polymerase chain
reaction analyses and deep-sequencing analyses revealed
the transcriptional upregulation and enhanced mutagenesis
of putative tumor suppressor genes, including dual specificity
phosphatase 6 (Dusp6), early growth response 1 (Egr1) and
inhibitor of DNA binding 2 (Id2), in AID-expressing liver with
TAA-mediated hepatic inflammation. Together, these findings
suggest that inflammation-mediated transcriptional upregulation
of target genes, including putative tumor suppressor genes,
enhances the opportunity for inflamed cells to acquire somatic
mutations and contributes to the acceleration of tumorigenesis
in the inflamed liver tissues.
Disclosures:
The following authors have nothing to disclose: Tomonori Matsumoto, Norihiro
Nishijima, Tsutomu Chiba, Hiroyuki Marusawa
1990
Regulator of G-protein signaling 5 enhances portal vein
invasion in hepatocellular carcinoma
Yumi Umeno 1 , Sachiko Ogasawara 1 , Jun Akiba 1 , Hironori
Kusano 1 , Osamu Nakashima 2 , Hironori Koga 3 , Takuji Torimura 3 ,
Hirohisa Yano 1 ; 1 Department of Pathology, Kurume University
School of Medicine, Kurume, Japan; 2 Clinical Laboratory Medicine,
Kurume University Hospital, Kurume, Japan; 3 Department of
Medicine, Division of Gastroenterology, Kurume University School
of Medicine, Kurume, Japan
Aim: Hepatocellular carcinoma (HCC) is one of the most
common cancers in the world and a leading cause of cancer
death. Portal vein invasion (PVI) is one of the major prognostic
factors in patients with HCC. The aim of this study is to identify
molecules to regulate PVI. Materials and Methods: We
selectively collected tissues from each part of cancerous area,
paired noncancerous area and PVI area by using laser microdissection
(LMD) and frozen sections obtained from 3 HCC
patients. Subsequently, cDNA microarray was conducted. Five
upregulated or downregulated molecules in plural cases were
identified and subjected to the following examinations. In order
to evaluate the expression and the relationship to clinicopathologic
factors, quantitative RT-PCR (qRT-PCR) and immunohistochemical
stain were performed in 32 HCCs and in 60 HCCs,
respectively. Results: We focused on 3 upregulated molecules,
i.e., integrin beta 3 (ITGB3), osteopontin (OPN) and regulator
of G-protein signaling 5 (RGS5) and 2 downregulated molecules,
i.e., metallothionein 1G (MT1G) and metallothionein 1H
(MT1H) in PVI tissue compared with cancerous tissue by cDNA
microarray analysis. In qRT-PCR, RGS5 was significantly overexpressed
in cancerous tissue compared with noncancerous
tissue (p = 0.02). However, there was no significant difference
in ITGB3 and OPN expression (respectively: p = 0.13 and p
= 0.12). The expression of MT1G and MT1H was significantly