Mutational landscape of a chemically induced mouse model of liver cancer
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ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Margus Lukk
PROVIDER: S-BSMS4 | bioimages |
REPOSITORIES: bioimages
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Project description:BACKGROUND & AIMS:Carcinogen-induced mouse models of liver cancer are used extensively to study the pathogenesis of the disease and are critical for validating candidate therapeutics. These models can recapitulate molecular and histological features of human disease. However, it is not known if the genomic alterations driving these mouse tumour genomes are comparable to those found in human tumours. Herein, we provide a detailed genomic characterisation of tumours from a commonly used mouse model of hepatocellular carcinoma (HCC). METHODS:We analysed whole exome sequences of liver tumours arising in mice exposed to diethylnitrosamine (DEN). Mutational signatures were compared between liver tumours from DEN-treated and untreated mice, and human HCCs. RESULTS:DEN-initiated tumours had a high, uniform number of somatic single nucleotide variants (SNVs), with few insertions, deletions or copy number alterations, consistent with the known genotoxic action of DEN. Exposure of hepatocytes to DEN left a reproducible mutational imprint in resulting tumour exomes which we could computationally reconstruct using six known COSMIC mutational signatures. The tumours carried a high diversity of low-incidence, non-synonymous point mutations in many oncogenes and tumour suppressors, reflecting the stochastic introduction of SNVs into the hepatocyte genome by the carcinogen. We identified four recurrently mutated genes that were putative oncogenic drivers of HCC in this model. Every neoplasm carried activating hotspot mutations either in codon 61 of Hras, in codon 584 of Braf or in codon 254 of Egfr. Truncating mutations of Apc occurred in 21% of neoplasms, which were exclusively carcinomas supporting a role for deregulation of Wnt/?-catenin signalling in cancer progression. CONCLUSIONS:Our study provides detailed insight into the mutational landscape of tumours arising in a commonly used carcinogen model of HCC, facilitating the future use of this model to better understand the human disease. LAY SUMMARY:Mouse models are widely used to study the biology of cancer and to test potential therapies. Herein, we have described the mutational landscape of tumours arising in a carcinogen-induced mouse model of liver cancer. Since cancer is a disease caused by genomic alterations, information about the patterns and types of mutations in the tumours in this mouse model should facilitate its use to study human liver cancer.
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Project description:The objective of this study was to evaluate the efficacy of nicotinamide in a N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced urinary bladder cancer model in mice, and to identify through gene expression profiling the molecular signatures of cancer prevention by nicotinamide. We used 20 mice for microarray experiments: five mice with normal bladders (group I), five with nicotinamide-treated bladders (group II), five with BBN-induced mouse bladder tumors (group III), and five with non-tumorigenic bladders treated with BBN and nicotinamide (group IV). Keywords: Gene expression, Mouse bladder cancer, Cancer prevention Total RNA was isolated using TRIzol reagent (Life Technologies, NY), according to the manufacturer's protocol. The quality and integrity of the RNA were confirmed by agarose gel electrophoresis and ethidium bromide staining, followed by visual examination under ultraviolet light. Five-hundred nanograms of total RNA were used for labeling hybridization according to the manufacturerM-bM-^@M-^Ys protocols (Illumina Mouse-6 BeadChips, version 1.0). Arrays were scanned with an Illumina Bead Array Reader confocal scanner (BeadStation 500GXDW; Illumina, Inc., San Diego, CA) according to the manufacturer's instructions. After scanning, the microarray data were normalized using quantile normalization. Measured gene expression values were log2 transformed and median-centered across genes and samples.
2011-12-12 | E-GEOD-21636 | biostudies-arrayexpress
Project description:4-Aminobiphenyl (ABP) is a trace component of cigarette smoke and hair dyes, a suspected human carcinogen and a potent rodent liver carcinogen. Postnatal exposure of mice to ABP results in a higher incidence of liver tumors in males than in females, paralleling the sex difference in human liver cancer incidence. A traditional model of ABP tumorigenesis involves initial CYP1A2-mediated N-hydroxylation, which eventually leads to production of mutagenic ABP-DNA adducts that initiate tumor growth. However, several studies have found no correlation between sex or CYP1A2 function and the DNA-damaging, mutagenic, or tumorigenic effects of ABP. Oxidative stress may be an important etiological factor for liver cancer, and it has also been linked to ABP exposure. The goals of this study were to identify novel enzyme(s) that contribute to ABP N-oxidation, and to investigate a potential role for oxidative stress in ABP liver tumorigenicity. Isozyme-selective inhibition experiments using liver microsomes from wild-type and genetically modified mice identified CYP2E1 as a major ABP N-hydroxylating enzyme. The N-hydroxylation of ABP by transiently expressed CYP2E1 produced oxidative stress in cultured mouse hepatoma cells. In vivo postnatal exposure of mice to a tumorigenic dose of ABP also produced oxidative stress in male wild-type mice, but not in male Cyp2e1(-/-) mice or in female mice. However, a stronger NRF2-associated antioxidant response was observed in females. Our results identify CYP2E1 as a novel ABP-N-oxidizing enzyme, and suggest that sex differences in CYP2E1-dependent oxidative stress and antioxidant responses to ABP may contribute to the observed sex difference in tumor incidence.
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Project description:Emerging evidence has implicated microRNAs in regulating the production of multiple inflammatory mediators including cytokines and chemokines. We previously elucidated the dynamic activation of key signals that link colitis to colorectal cancer. In this study, we observed a sharp increase in the levels of matrix metalloproteinases (Mmps) that provided a basis for the inflammation-cancer link, and we questioned whether this was a consequence of the dysregulation of Mmp-specific microRNAs, at least partly. We assayed a panel of murine microRNAs that were predicted to target Mmps and found they were downregulated in the inflammation-cancer link. Furthermore, we demonstrated that three murine microRNAs, namely miR-128, -134, and -330, can target the three Mmps Mmp3, Mmp10, and Mmp13, respectively. We also found that the level of the microRNA-processing enzyme Dicer1 was decreased in the inflammation-cancer link. These microRNAs functioned as tumor suppressors in colon cancer cells, attenuating the proliferation, migration, and invasion potential of murine colon cancer cells as well as angiogenesis and the growth of tumors derived from these cells. Our results suggest that microRNAs modulate the production of key inflammatory mediators and that microRNA dysfunction may contribute to the non-resolving inflammation associated with cancer.
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Project description:The objective of this study was to evaluate the efficacy of nicotinamide in a N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced urinary bladder cancer model in mice, and to identify through gene expression profiling the molecular signatures of cancer prevention by nicotinamide. We used 20 mice for microarray experiments: five mice with normal bladders (group I), five with nicotinamide-treated bladders (group II), five with BBN-induced mouse bladder tumors (group III), and five with non-tumorigenic bladders treated with BBN and nicotinamide (group IV). Keywords: Gene expression, Mouse bladder cancer, Cancer prevention
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Project description:Ulcerative colitis (UC) is a chronic inflammatory disease that targets the colon and has seen an increasing prevalence worldwide. In our pursuit of new diagnostic and therapeutic approaches for UC, we undertook a sequencing of colons from UC mouse models. We focused on analyzing their differentially expressed genes (DEGs), enriching pathways, and constructing protein-protein interaction (PPI) and Competing Endogenous RNA (ceRNA) networks. Our analysis highlighted novel DEGs such as Tppp3, Saa3, Cemip, Pappa, and Nr1d1. These DEGs predominantly play roles in pathways like cytokine-mediated signaling, extracellular matrix organization, extracellular structure organization, and external encapsulating structure organization. This suggests that the UC pathogenesis is intricately linked to the interactions between immune and non-immune cells with the extracellular matrix (ECM). To corroborate our findings, we also verified certain DEGs through quantitative real-time PCR. Within the PPI network, nodes like Stat3, Il1b, Mmp3, and Lgals3 emerged as significant and were identified to be involved in the crucial cytokine-mediated signaling pathway, which is central to inflammation. Our ceRNA network analysis further brought to light the role of the Smad7 Long non-coding RNA (lncRNA). Key MicroRNA (miRNAs) in the ceRNA network were pinpointed as mmu-miR-17-5p, mmu-miR-93-5p, mmu-miR-20b-5p, mmu-miR-16-5p, and mmu-miR-106a-5p, while central mRNAs included Egln3, Plagl2, Sema7a, Arrdc3, and Stat3. These insights imply that ceRNA networks are influential in UC progression and could provide further clarity on its pathogenesis. In conclusion, this research deepens our understanding of UC pathogenesis and paves the way for potential new diagnostic and therapeutic methods. Nevertheless, to solidify our findings, additional experiments are essential to confirm the roles and molecular interplay of the identified DEGs in UC.
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Project description:Because of similarities in histopathology and tumor progression stages between mouse and human lung adenocarcinomas, the mouse lung tumor model with lung adenomas as the endpoint has been used extensively to evaluate the efficacy of putative lung cancer chemopreventive agents. In this study, a competitive cDNA library screening (CCLS) was employed to determine changes in the expression of mRNA in chemically induced lung adenomas compared with paired normal lung tissues. A total of 2555 clones having altered expression in tumors were observed following competitive hybridization between normal lung and lung adenomas after primary screening of over 160,000 clones from a mouse lung cDNA library. Among the 755 clones confirmed by dot blot hybridization, 240 clones were underexpressed, whereas 515 clones were overexpressed in tumors. Sixty-five clones with the most frequently altered expression in six individual tumors were confirmed by semiquantitative RT-PCR. When examining the 58 known genes, 39 clones had increased expression and 19 had decreased expression, whereas the 7 novel genes showed overexpression. A high percentage (>60%) of overexpressed or underexpressed genes was observed in at least two or three of the lesions. Reproducibly overexpressed genes included ERK-1, JAK-1, surfactant proteins A, B, and C, NFAT1, alpha-1 protease inhibitor, helix-loop-helix ubiquitous kinase (CHUK), alpha-adaptin, alpha-1 PI2, thioether S-methyltransferase, and CYP2C40. Reproducibly underexpressed genes included paroxanase, ALDH II, CC10, von Ebner salivary gland protein, and alpha- and beta-globin. In addition, CCLS identified several novel genes or genes not previously associated with lung carcinogenesis, including a hypothetical protein (FLJ11240) and a guanine nucleotide exchange factor homologue. This study shows the efficacy of this methodology for identifying genes with altered expression. These genes may prove to be helpful in our understanding of the genetic basis of lung carcinogenesis and in developing biomarkers for lung cancer chemoprevention studies in mice.
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