Project description:To-date, most proteomic studies aimed at discovering tissue-based cancer biomarkers have compared the quantity of selected proteins between case and control groups. However, proteins generally function in association with other proteins to form modules localized in particular subcellular compartments in specialized cell types and tissues. Sub-cellular mislocalization of proteins has in fact been detected as a key feature in a variety of cancer cells. Here, we describe a strategy for tissue-biomarker detection based on a mitochondrial fold enrichment (mtFE) score, which is sensitive to protein abundance changes as well as changes in subcellular distribution between mitochondria and cytosol. The mtFE score integrates protein abundance data from total cellular lysates and mitochondria-enriched fractions, and provides novel information for the classification of cancer samples that is not necessarily apparent from conventional abundance measurements alone. We apply this new strategy to a panel of wild-type and mutant mice with a liver-specific gene deletion of Liver receptor homolog 1 (Lrh-1hep-/-), with both lines containing control individuals as well as individuals with liver cancer induced by diethylnitrosamine (DEN). Lrh-1 gene deletion attenuates cancer cell metabolism in hepatocytes through mitochondrial glutamine processing. We show that proteome changes based on mtFE scores outperform protein abundance measurements in discriminating DEN-induced liver cancer from healthy liver tissue, and are uniquely robust against genetic perturbation. We validate the capacity of selected proteins with informative mtFE scores to indicate hepatic malignant changes in two independent mouse models of hepatocellular carcinoma (HCC), thus demonstrating the robustness of this new approach to biomarker research.
Project description:Autotaxin (ATX, Enpp2) is a secreted lysophospholipase D catalyzing the production of lysophosphatidic acid (LPA), a pleiotropic growth factor-like phospholipid. Upregulated ATX expression has been detected in various chronic inflammatory disorders and different types of cancer; among them increased ATX mRNA or immunohistochemical staining has been suggested in Hepatocellular carcinoma (HCC) patients. Conditional deletion of ATX/Enpp2 specifically from hepatocytes, in AlbEnpp2-/- mice, attenuated the DEN/CCl4-mediated HCC development in mice. To obtain mechanistic insights into the mode of action of the ATX/LPA axis in HCC development, we performed whole liver, genome wide expression profiling of DEN/CCl4-induced HCC upon the genetic deletion of Autotaxin (ATX) in AlbEnpp2-/- mice in comparison with DEN/CCl4-treated and untreated wt littermate mice.
Project description:To date, most proteomic analyses towards cancer biomarker discovery have been based on protein quantification. However, proteins function in association with other proteins to form modules that are localized in specific subcellular compartments. Cellular mislocalization of proteins has in fact been detected as a key feature in a variety of cancer cells1,2. Here, we describe a strategy for biomarker detection based on a mitochrondrial enrichment score (mtES), which is sensitive to protein abundance as well as protein translocation between mitochondria and cytosol. The mtES score integrates protein expression data from total cellular lysates and enriched mitochondrial fractions and provides important information for the classification of cancer samples, which is not apparent from conventional quantitative protein measurements. We apply the new strategy to a panel of wild-type and mutant mice that are either healthy or present liver cancer. We show that proteome changes based on mtES scores outperform protein abundance measurements in discriminating liver cancer from healthy liver tissue and that they are uniquely robust against strong genetic perturbation. Overall, our method provides a more sensitive approach to cancer biomarker discovery that takes into account contextual information of tested proteins.
Project description:Hepatocellular carcinoma is the third leading cause of cancer death worldwide, and it is necessary to elucidate the mechanism of hepatocarcinogenesis. Hepatocellular carcinoma (HCC) has a high mortality rate and develops based on the chronic inflammatory hepatic disease. Therefore, novel prophylactic or therapeutic strategies are required to improve outcome. In this study, influence of diethylnitrosamine (DEN) and retinoic acid (ATRA) on hepatocarcinogenesis was investigated in mouse. These results suggest that the control of NF-M-NM-:B signaling during the early stage of HCC development is important for the prevention of malignant transformation in hepatocytes. Genes induced by the following treatments in mice liver were investigated at 2 days or 7 days after treatment; DEN: diethylnitrosamine (treatment of DEN (drinking water 80 mg/L)) ATRA: retinoic acid (treatment of ATRA (drinking water 30 mg/L)) G0s2 siRNA : G0s2 knockdown mouse liver (treatment of G0s2 siRNA) Control siRNA: treatment of scramble siRNA (negative control)
Project description:The LXCXE peptide motif facilitates interaction between the RB tumor suppressor and a large number of cellular proteins that are expected to impinge on diverse biological processes. In vitro and in vivo analyses demonstrated that LXCXE-binding function is dispensable for RB promoter association and control of basal gene expression. Dependence on this function of RB is unmasked after DNA damage, wherein LXCXE-binding is essential for exerting control over E2F3 and suppressing cell cycle progression in the presence of genotoxic stress. Gene expression profiling revealed that the transcriptional program coordinated by this specific aspect of RB is associated with progression of human hepatocellular carcinoma and poor disease outcome. Consistent with these findings, biological challenge revealed a requirement for LXCXE-binding in suppression of genotoxin-initiated hepatocellular carcinoma in vivo. Together, these studies establish an essential role of the LXCXE-binding motif for RB-mediated transcriptional control, response to genotoxic insult, and tumor suppression. Mice transgenic for Cre-recombinase under the albumin promoter contain indicated combinations of loxP sites flanking exon 19 of Rb1 (f), N750F mutation (NF) or wild-type (plus) genotypes. For gene expression microarray analysis, mice were aged to 14 days and treated for 24 hours with diethylnitrosamine (DEN) or saline as an M-bM-^@M-^\untreatedM-bM-^@M-^] control. Liver tissue was obtained from DEN treated livers and compared to normal liver tissue of saline treated littermates.
Project description:The retinoblastoma (RB) and p53 tumor suppressors are critical regulators of the cell cycle with profound impact on both normal cell biology and disease etiology. In the context of human cancers, compound inactivation of RB and p53 is a frequent occurrence; however, the cooperation of these tumor suppressors in driving tumorigenesis has proven to be intricate and dependent on both the tissue and type of cancer. Hepatocellular carcinoma (HCC) is a highly complex disease characterized by numerous molecular abnormalities (e.g. p53, RB, TGFβ) and chromosomal aberrations associated with environmental factors (e.g. Hepatitis B/C Virus, Aflatoxin B1). Despite extensive research, how each of these facets of disease development cooperates in promoting tumorigenesis is ultimately unknown. In the current study, we present a mouse model of liver tumorigenesis, in which the impact of RB and p53 loss is modified by the tissue environment. While loss of RB and p53 promotes deregulation of transcriptional programs associated with advanced disease, these changes are not sufficient to drive spontaneous tumorigenesis in the liver. However, in response to carcinogen-induced damage, distinct and cooperative roles of RB and p53 are revealed, which critically impact cell cycle control, checkpoint response, genome stability, and ultimately tumor development. Mice that are transgenic for Cre recombinase under the albumin promoter and harboring loxP sites within the Rb and/or p53 genes. For gene expression microarray analysis, mice were aged to 14 days, and treated for 24 hours with diethylnitrosamine (DEN) or saline as a control. For CGH analysis, mice were aged to 6 months post-DEN treatment. Liver tissue was obtained from dissected tumors and compared to normal liver tissue of 6-month old, saline-treated littermates. CGH analysis includes 5 individual tumor samples and 2 control samples (each consisting of a pool of 3 normal mouse liver DNA).
Project description:Gene-expression profiles of liver and hepatocellular carcinoma induced by diethylnitrosamine (DEN) in KLF6 +/- and wild type KLF6 mice. Inactivation of the KLF6 tumor suppressor is common in HCC due to hepatitis C virus (HCV), consistent with its anti-proliferative activity in HCC-derived cell lines and in hepatocytes of transgenic mice. We have evaluated the impact of KLF6 depletion on human HCC and experimental hepatocarcinogenesis. In patients with surgically resected HCC, those with significantly reduced tumor expression of KLF6 had a significantly decreased survival. We modeled this event in KLF6 +/- mice, which displayed significantly more tumorigenicity than KLF6 +/+ animals in response to the hepatic carcinogen DEN, associated with recapitulation of gene signatures in both surrounding tissue and tumors that are associated with aggressive human HCCs. In DNA microarrays, mdm2 mRNA expression was increased in tumors from KLF6 +/- compared to KLF6 +/+ mice, which was validated by realtime qPCR and Western blot in both human HCC and DEN-induced murine tumors. Moreover, chromosomal immunoprecipitation and co-transfection assays established the P2 intronic promoter of mdm2 as a bona fide transcriptional target repressed by KLF6. Whereas KLF6 over-expression in HCC cell lines led to reduced MDM2 levels and increased p53 protein and transcriptional activity, reduction in KLF6 by siRNA led to increased MDM2 and reduced p53. Our findings indicate that KLF6 deficiency contributes significantly to the carcinogenic milieu in human and murine HCC, and uncover a novel tumor suppressor activity of KLF6 in HCC, by linking its transcriptional repression of MDM2 to stabilization of p53. Keywords: Liver, Hepatocellular carcinoma, Expression array, Exon array, Affymetrix KLF6 +/- mice were previously generated by homologous recombination in which exon 2 was targeted using an 11-kb targeting construct, and replaced with neomycin/lacZ cassette. After selection with neomycin, the ES clones were injected into C57BL/6 mouse blastocysts and implanted into pseudo pregnant females; two lines of KLF6 +/- mice were generated from the resulting chimeric animals (Blood 107;1357, Oncogene 26;4428). Whereas KLF6 -/- mice are embryonic lethal, KLF6 +/- animals had no demonstrable abnormalities in the absence of any stressor. Male KLF6 +/- mice were bred with wild type C57BL/6 to generate mixed litters of KLF6 +/- and KLF6 +/+ animals. Progeny were genotyped using PCR-amplified tail DNA, using primers as previously described (Oncogene 26;4428). Amplified fragments were separated on a 2.5% agarose gel, revealing bands of ~200 bp (wild type KLF6) and ~100 bp (Neo), as expected. At 2 weeks of age, KLF6 +/+ and KLF6 +/- mice were injected intraperitoneally with either a single dose of diethyl nitrosamine (DEN), 5 µg/g body weight in 100 µl of saline, or vehicle alone. Vehicle and DEN-treated mice were maintained on standard chow, and then sacrificed 3, 6 or 9 months later. At the time of sacrifice the animals were weighed, and blood and liver samples were harvested for analysis and tumor quantification.
Project description:The retinoblastoma (RB) and p53 tumor suppressors are critical regulators of the cell cycle with profound impact on both normal cell biology and disease etiology. In the context of human cancers, compound inactivation of RB and p53 is a frequent occurrence; however, the cooperation of these tumor suppressors in driving tumorigenesis has proven to be intricate and dependent on both the tissue and type of cancer. Hepatocellular carcinoma (HCC) is a highly complex disease characterized by numerous molecular abnormalities (e.g. p53, RB, TGFβ) and chromosomal aberrations associated with environmental factors (e.g. Hepatitis B/C Virus, Aflatoxin B1). Despite extensive research, how each of these facets of disease development cooperates in promoting tumorigenesis is ultimately unknown. In the current study, we present a mouse model of liver tumorigenesis, in which the impact of RB and p53 loss is modified by the tissue environment. While loss of RB and p53 promotes deregulation of transcriptional programs associated with advanced disease, these changes are not sufficient to drive spontaneous tumorigenesis in the liver. However, in response to carcinogen-induced damage, distinct and cooperative roles of RB and p53 are revealed, which critically impact cell cycle control, checkpoint response, genome stability, and ultimately tumor development. Mice that are transgenic for Cre recombinase under the albumin promoter and harboring loxP sites within the Rb and/or p53 genes. For gene expression microarray analysis, mice were aged to 14 days, and treated for 24 hours with diethylnitrosamine (DEN) or saline as a control. For CGH analysis, mice were aged to 6 months post-DEN treatment. Liver tissue was obtained from dissected tumors and compared to normal liver tissue of 6-month old, saline-treated littermates. CGH analysis includes 5 individual tumor samples and 2 control samples (each consisting of a pool of 3 normal mouse liver DNA).
Project description:Smyd3 is a histone methyltransferase implicated in tumorigenesis. Here we show that Smyd3 expression in mice is required but not sufficient for chemically induced liver and colon cancer formation. In these organs Smyd3 is functioning in the nucleus as a direct transcriptional activator of several key genes involved in cell proliferation, epithelial-mesenchymal transition, JAK/Stat3 oncogenic pathways, as well as of the c-myc and b-catenin oncogenes. Smyd3 specifically interacts with H3K4Me3-modified histone tails and is recruited to the core promoter regions of many but not all active genes. Smyd3 binding density on target genes positively correlates with increased RNA Pol-II density and transcriptional outputs. The results suggest that Smyd3 is an essential transcriptional potentiator of a multitude of cancer-related genes. Standard Smyd3-deficient (Smyd3-KO) mice were generated using gene-trap ES cell clones (AS0527 from International Gene Trap Consortium), in which a selection cassette, containing the splice acceptor site from mouse EN2 exon 2 followed by the beta-galactosidase and neomycin resistance gene fusion gene and the SV40 polyadenylation sequence was inserted into the 5th intron of the Smyd3 gene. The resulting mice were devoid of Smyd3 mRNA and protein in all tissues, including liver and colon. For the generation of Smyd3-Tg mice the open reading frame of the mouse Smyd3 cDNA, which contained 3 Flag epitopes at the 3â end was inserted into the StuI site of the pTTR1-ExV3 plasmid (Yan et al, 1990). The 6.8 kb HindIII fragment containing the mouse transthyretin enhancer/promoter, intron 1, Smyd3 cDNA, three Flag epitopes and SV40 poly-A site was used to microinject C57Bl/6 fertilized oocytes. Founder animals were identified by Southern blotting and crossed with F1 mice to generate lines. Specific overexpression in the liver was tested by RT-PCR analysis in different tissues.
Project description:The effect of Tlr4P712H mutation (rendering TLR4 non-functional), or gut-sterilization by antbiotics, on the induction of tumorgenesis by CCl4 and diethylnitrosamine (DEN) was characterized. Affymetrix Mouse 430 2.0 gene expression measurements were used to characterize the transcriptomic basis of the effects of the above treatments and genotypes on tumorgenesis. Gene expression of mouse livers of A. Normal liver from WT C3H/HeOuJ mice, B. HCC from WT C3H/HeOuJ mice treated with CCl4 and DEN, C.HCC from TLR4-mutant C3H/HeJ mice (Tlr4P712H) treated with CCl4 and DEN and D.HCC from WT C3H/HeOuJ mice treated with antibiotics (a combination of ampicillin (1 g/l), neomycin [1 g/l], metronidazole[1 g/l] and vancomycin [500 mg/l] in drinking water) and CCl4 and DEN were characterized.