Article

Multiple adaptive mechanisms to chronic liver disease revealed at early stages of liver carcinogenesis in the Mdr2-knockout mice

Department of Pharmacology, Hebrew University of Jerusalem, Yerushalayim, Jerusalem, Israel
Cancer Research (Impact Factor: 9.28). 05/2006; 66(8):4001-10. DOI: 10.1158/0008-5472.CAN-05-2937
Source: PubMed

ABSTRACT Molecular events preceding the development of hepatocellular carcinoma were studied in the Mdr2-knockout (Mdr2-KO) mice. These mice lack the liver-specific P-glycoprotein responsible for phosphatidylcholine transport across the canalicular membrane. Portal inflammation ensues at an early age followed by hepatocellular carcinoma development after the age of 1 year. Liver tissue samples of Mdr2-KO mice in the early and late precancerous stages of liver disease were subjected to histologic, biochemical, and gene expression profiling analysis. In an early stage, multiple protective mechanisms were found, including induction of many anti-inflammatory and antioxidant genes and increase of total antioxidant capacity of liver tissue. Despite stimulation of hepatocyte DNA replication, their mitotic activity was blocked at this stage. In the late stage of the disease, although the total antioxidant capacity of liver tissue of Mdr2-KO mice was normal, and inflammation was less prominent, many protective genes remained overexpressed. Increased mitotic activity of hepatocytes resulted in multiple dysplastic nodules, some of them being steatotic. Expression of many genes regulating lipid and phospholipid metabolism was distorted, including up-regulation of choline kinase A, a known oncogene. Many other oncogenes, including cyclin D1, Jun, and some Ras homologues, were up-regulated in Mdr2-KO mice at both stages of liver disease. However, we found no increase of Ras activation. Our data suggest that some of the adaptive mechanisms induced in the early stages of hepatic disease, which protect the liver from injury, could have an effect in hepatocarcinogenesis at later stages of the disease in this hepatocellular carcinoma model.

Download full-text

Full-text

Available from: Daniel Goldenberg, Aug 23, 2015
0 Followers
 · 
98 Views
  • Article: Fxr
    [Show abstract] [Hide abstract]
    ABSTRACT: Great progress has been made in the understanding of the physiological roles of the nuclear receptor farnesoid X receptor (FXR) during the last several years. Roles for FXR were initially identified in the regulation of bile acid, cholesterol, triglyceride, and glucose metabolism. More recently, additional functions of FXR are identified in enteroprotection, liver regeneration, cancer and aging. These exciting findings suggest that FXR has a broader role than previously thought, and also highlight potential opportunities for using FXR as a drug target for different diseases.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: According to the cancer immunoediting concept, inflammatory mediators play not only a critical role in promoting host protection against cancer but also contribute to cancer cell growth and survival. TNF-alpha is a critical factor in this network. However, the mechanisms underlying the tumor-promoting effect of TNF-alpha have not been fully elucidated yet. We previously reported that in vitro culture of Lewis lung carcinoma 3LL cells with TNF-alpha-producing macrophages resulted in enhanced resistance toward TNF-alpha-mediated lysis and increased malignancy of the 3LL cells. In this study, we analyzed the effects of endogenous TNF-alpha on TNF-alpha resistance and malignant behavior in vivo of low-malignant/TNF-alpha-sensitive 3LL-S cells and cancer cells derived from 3LL-S tumors that developed in wild-type or TNF-alpha(-/-) mice. Interestingly, 3LL-S cells acquired a malignant phenotype in vivo depending on the presence of host TNF-alpha, whereas acquisition of TNF-alpha resistance was TNF-alpha-independent. This result suggested that malignancy-promoting characteristics of 3LL-S cells other than TNF-alpha resistance are influenced in vivo by TNF-alpha. We previously identified the malignancy-promoting genes, secretory leukocyte protease inhibitor (SLPI) and S100A4, as being up-regulated in 3LL-S cells upon their s.c. growth in wild-type mice. In this study, we show that SLPI, but not S100A4, was induced in 3LL-S cells both in vitro and in vivo by TNF-alpha, and that silencing of in vivo induced 3LL-S SLPI expression using RNA interference abrogated in vivo progression but did not influence TNF-alpha resistance. These data indicate that SLPI induction may be one mechanism whereby TNF-alpha acts as an endogenous tumor promoter.
    The Journal of Immunology 01/2007; 177(11):8046-52. DOI:10.4049/jimmunol.177.11.8046 · 5.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mutations and epigenetic aberrant signaling of growth factors pathways contribute to carcinogenesis. Recent studies reveal that non-coding RNAs are controllers of gene expression. H19 is an imprinted gene that demonstrates maternal monoallelic expression without a protein product; although its expression is shut off in most tissues postnatally, it is re-activated during adult tissue regeneration and tumorigenesis. Moreover, H19 is highly expressed in liver metastasis derived from a range of carcinomas. The objective of this study is to explore the role of H19 in carcinogenesis, and to determine its identification as an anti-tumor target. By controlling oxygen pressure during tumor cell growth and H19 expression levels, we investigated the role of H19 expression in vitro and in vivo in hepatocellular (HCC) and bladder carcinoma. Hypoxia upregulates the level of H19 RNA. Ablations of tumorigenicity of HCC and bladder carcinomas in vivo are seen by H19 knockdown which also significantly abrogates anchorage-independent growth after hypoxia recovery, while ectopic H19 expression enhances tumorigenic potential of carcinoma cells in vivo. Knocking-down H19 message in hypoxic stress severely diminishes p57(kip2) induction. We identified a number of potential downstream targets of H19 RNA, including angiogenin and FGF18. H19 RNA harbors pro-tumorigenic properties, thus the H19 gene behaves as an oncogene and may serve as a potential new target for anti-tumor therapy.
    PLoS ONE 02/2007; 2(9):e845. DOI:10.1371/journal.pone.0000845 · 3.53 Impact Factor
Show more