Epigenetic Based Enrichment of Cancer Stem Cells: Mechanistic and Clinical Implications for Liver Cancer
ABSTRACT: Global transcriptiome changes between SP and NSP cells of liver cancer cell lines w and w/o Zebularine treatment Huh7,WRL68, KMCH FACS sorted in SP and NSP w and w/o Zebularine and subjected to illumina microarray analysis.
Project description:Global transcriptiome changes between SP and NSP cells of liver cancer cell lines w and w/o Zebularine treatment Overall design: Huh7,WRL68, KMCH FACS sorted in SP and NSP w and w/o Zebularine and subjected to illumina microarray analysis.
Project description:Transcriptomic changes in human liver cancer cell lines caused by the demethylating drug zebularine. Epigenomic changes such as aberrant hypermethylation and subsequent atypical gene silencing are characteristic features of human cancer. Here, we report a comprehensive characterization of epigenomic modulation caused by zebularine, an effective DNA methylation inhibitor, in human liver cancer. Using transcriptomic and epigenomic profiling, we identified a zebularine signature that classified liver cancer cell lines into two major subtypes with different drug-responses. In drug-sensitive cell lines, zebularine caused inhibition of proliferation coupled with increased apoptosis, whereas drug-resistant cell lines were associated with upregulation of oncogenic networks (e.g. E2F1, MYC, and TNF) driving liver cancer growth in vitro and in mice. Assessment of zebularine-based therapy in xenograft mouse models demonstrated potent therapeutic effects against tumors established from zebularine-sensitive but not zebularine-resistant liver cancer cells leading to increased survival and decreased pulmonary metastasis. Integration of zebularine gene expression and demethylation response signatures differentiated patients with HCC according to their survival and disease recurrence and identified a subclass of patients within the poor survivors likely to benefit from therapeutic agents that target the cancer epigenome. Each cell line was mock treated or treated with 100uM and 200uM zebularine for 7 days, respectively *** This Series represents the gene expression component of the study.
Project description:Reversal of DNA hypermethylation and associated gene silencing is an emerging cancer therapy approach. In this context we have addressed the impact of epigenetic alterations and local microenvironment on the functional and transcriptional reprogramming of hepatic cancer stem cells. (CSCs) using the DNMT1 inhibitor Zebularine (ZEB). We show for the first time that cellular context is a critical determinant in the response to DNMT1 inhibition resulting in either a long term epigenetically driven malignant reprogramming or an effective antitumor therapeutic reprogramming. Furthermore, permanent reduction of DNMT1 protein level renders the HCC cell lines insensitive to both DNMT1 inhibition and cellular context. These results emphasize the importance of decoding the mechanisms involved in therapeutic application of DNA demethylating agents. Huh7 and PLC treated with ZEB, and Huh7 depleted for DNMT1
Project description:Development of targeted therapeutics for hepatocellular carcinoma (HCC) remains a major challenge. We have previously demonstrated that constitutively photomorphogenic 1 (COP1), which regulates p53 activity by ubiquitination, is frequently overexpressed in human HCC. Here we examined whether molecular targeting of COP1 by small interfering (si) RNA can affect the course of HCC progression. COP1-1 was selected as the most effective target siRNAs in terms of growth inhibition and apoptotic induction in several HCC cell lines. Interestingly, the growth inhibition occurred both in HCC cells that retain wild-type p53 or express mutant p53 (Y220C or R249S). Next we have determined to investigate the molecular mechanisms underlying the phenotypic changes. Given the recent findings that COP1 functions as a negative regulator of p53, we addressed whether the phenotypic changes caused by COP1 silencing were due to alterations in p53 and/or p21 status. Indeed, in COP1-depleted HepG2 cells expressing wild type p53, induction of apoptosis was associated with restoration of p53 function as judged by a marked increase in the levels of p53 and its target p21, suggesting that cell death was p53-dependent. However, the COP1 silencing in Huh7 cells, which carry Y220C mutation, caused a strong induction of apoptosis without changing p53 levels. To further address this issue, we next looked for the global transcriptional changes underlying the antitumor effects of COP1 silencing in HCC cells [with different p53 status]. For this purpose, Huh7 and HepG2 were treated with NCsiRNA and COP1-1siRNA for 48 hours and subjected to illumina microarray analysis. We found that the number of differentially expressed genes which displayed more than a 2-fold change (P < 0.01 by Bootstrap t-test) was 462 (167 up- and 295 down-regulated genes) and 522 (179 up- and 343 down-regulated genes) in COP1siRNA-treated Huh7 and HepG2 cells, respectively. As expected, the expression levels of RFWD2 (COP1) mRNA were significantly reduced in both treated HCC cell lines. Consistent with phenotypic changes, COP1-depleted Huh7 cells also displayed changes in p53-associated group of genes functionally involved in regulation of apoptosis, growth and differentiation including CASP6, GLIPR1, FHL2, GADD45A, HMOX1 BCL6, FOXO3, GDF15, and SCNN1A genes. Finally, we generated the common COP1 knockdown gene signature which included 78 genes. The Ingenuity Pathway Analysis analysis revealed that the 5 top putative networks with high score (>19) were strongly associated with NF-κB, HNF4α, TNF, and p53 pathways, suggesting that a common subset of molecular alterations in the diverse oncogenic pathways may cooperatively result in growth inhibition of HCC cells with wild type and mutant p53. Analysis of COP1 knockdown gene expression signatures by microarray revealed that the anti-proliferative effect was driven by a common subset of molecular alterations including p53-associated functional network. Systemic delivery of a modified COP1siRNA by stable-nucleic-acid-lipid-particles (SNALP) significantly suppressed neoplastic growth in liver, without unwanted immune response in an orthotopic xenograft model. These findings provide the first proof of principle that COP1 is a promising target for systemic therapy of HCC. Microarray was performed on human Ref-8v3 microarrays (illumina) as recommended by the manufacture. In detail, total RNAs were isolated 48 h after the transfection of NCsiRNA or COP1-1siRNA to Huh7, HepG2 or Hep3B cells. Biotin-labeled cRNA was linearly amplified according to manufacturer’s specification (AMIL1791; Ambion, Austin, TX). As input, 200 ng total RNA from tumor was used for the in vitro transcription (IVT) reactions which were incubated for 16 h at 37 ºC. The efficiency of this single round amplification was measured by NanoDrop (ND1000, Thermo Scientific). Hybridization, washing, detection (Cy3-streptavidin, Amersham Biosciences, GE Healthcare) and scanning were performed on an Illumina iScan system (Illumina) using reagents and following protocols supplied by the manufacturer. Briefly, the biotinylated cRNA (750 ng/sample) was hybridized on Sentrix whole genome beadchips human Ref-8v3 for 18 h at 58ºC while rocking (5 rpm). The beadchip covers ~ 24,000 RefSeq transcripts. Image analysis and data extraction were performed automatically using Illumina GenomeScan Software. To explore the functional relationships among the genes with altered expression in the HCC cells treated with COP1-1siRNA, a pathway analysis was carried out with the Ingenuity Pathway Analysis tool (Ingenuity Systems). Using the approach, we examined functional associations among genes and generated the gene networks with high significance on the basis that they had more of the interconnected genes present than would be expected by chance. The significance of each network was estimated by scoring system provided by Ingenuity. The scores are determined by the number of differentially expressed genes within each of the networks and the strength of the associations among network members. Once over-represented genes that are functionally relevant in gene networks are identified, we validated their functional association by using the independent pathway analysis tool PathwayStudio (Ariadne Genomics).
Project description:The experimental design demonstrates that zebularine, a DNA methyltransferase inhibitor, promotes regeneration in the mouse and that retinoic acid and zebularine synergistically accelerate this process.
Project description:PN2 male and female rat pups were treated with vehicle or zebularine. POA RNA was extracted and sequenced to deterime the effects of DNMT inhibition in POA gene expression. Males and Females were treated with either vehicle (0.1% DNMSO in saline) or Zebularine
Project description:Hepatocellular carcinoma is one of the most common cancers in world wide. During tumorigenesis, tumor suppressor and cancer-related genes are commonly silenced by aberrant DNA methylation in their promoter regions. Zebularine [1-(β-ᴅ-ribofuranosyl)-1,2-dihydropyrimidin-2-one] acts as an inhibitor of DNA methylation and exhibits chemical stability and minimal cytotoxicity both in vitro and in vivo. In this study, we explore the effect and possible mechanism of action of zebularine on hepatocellular carcinoma cell line HepG2. Here, we demonstrated that zebularine exhibited antitumor activity on HepG2 cells by inhibiting cell proliferation and inducing apoptosis. Zebularine treatment down-regulated CDK2 and phosphorylation of retinoblastoma protein (RB), and up-regulated p21WAF/CIP1 and p53. We also found that zebularine treatment up-regulated phosphorylation of p44/42 MAPK. These results suggest that p44/42 MAPK pathway play a role in zebularine induced cell cycle arrest by regulating activity of p21WAF/CIP1 and Rb. Furthermore, we found that zebularine induced apoptosis. Although proapoptotic protein Bax levels were not affected, antiapoptotic protein Bcl-2 level was down-regulated with zebularine treatment. The data in the present study suggest that the action of the double-stranded RNA-dependent protein kinase (PKR) is involved in inducing apoptosis with zebularine. These results provide a novel mechanism of zebularine-induced cell growth arrest and apoptosis in hepatocellular carcinoma. Three each independent batches of zebuluarine-treated and control HepG2 cells were subjected to illumina Human methylation 450K Beadchip analysis.
Project description:Cultures of DU-145 cells and of LNCaP cells were treated for 216 hours with 100µM zebularine (SIGMA) in three independent biological experiments. Zebularine acts as a DNA methyltransferase (DNMT) inhibitor thereby upregulating genes that are inactivated by e.g. promotor hypermethylation. The experiment aimed to search for upregulated transcripts to provide new targets for biomarker development and therapeutic use. Total RNA of untreated and treated (100µM zebularine) DU-145 cells (experiment HK_21_DU_145-HK_26_DU_145), and of untreated and treated (100µM zebularine) LNCaP cells (experiment HK_27_LNCaP-HK_32_LNCaP), were subjected to Affymetrix array analysis to detail the overall expression changes after treatment with a DNMT inhibitor. Treated cells showed no obvious signs of zebularine-induced cytotoxicity as revealed by XTT assays.
Project description:Recent studies suggested that embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) may represent different pluripotent states as defined by gene expression profiles and differentiation potential. Here we addressed a contribution of a lineage stage-specific donor cell memory in modulating the functional properties of iPSCs. iPSCs were generated from hepatic lineage cells at an early (hepatoblast-derived, HB-iPSCs) and end stage (adult hepatocyte, AH-iPSCs) of hepatocyte differentiation as well as from mouse fetal fibroblasts (MEF-iPSCs) using a lentiviral vector encoding four pluripotency-inducing factors Oct4, Sox2, Klf4, and c-Myc. All resulting iPS cell lines acquired iPSCs phenotype as judged by the accepted criteria including morphology, expression of pluripotency markers, silencing of transducing factors, capacity of multilineage differentiation in teratoma assay and normal diploid karyotype. However, hepatoblasts were more susceptible to reprogramming than either AH or MEF, and HB-iPSCs were more efficient in directed differentiation towards hepatocytic lineage as compared to AH-iPSCs, MEF-iPSCs or mESCs. Extensive comparative transcriptome analyses of the early passage iPSCs, donor cells and mESCs revealed that despite global similarities in gene expression patterns between generated iPSCs and mESCs, HB-iPSCs retained a transcriptional memory (7 up- and 20 down-regulated genes) typical of the original cells. Continuous passaging of HB-iPSCs abolished most of these differences including a superior capacity of hepatic re-differentiation. These results suggest that retention of lineage stage-specific donor memory in iPSCs may facilitate differentiation into donor cell type. The identified gene set may be helpful to improve hepatic differentiation for therapeutic application in liver disease modeling. A total of 200 ng RNA from four independent biological replicates of MACS-sorted mESC and iPSC were linearly amplified according to manufactures’ specification (Ambion, Austin, Tx,). For in vitro transcription (IVT), reactions were incubated for 16 h at 37ºC. The efficiency of the single round amplification was measured by NanoDrop (ND1000, Thermo Scientific). Hybridization, washing, detection (Cy3-streptavidin, Amersham Biosciences, GE Healthcare), and scanning were performed on an illumina iScan system (Illumina) using reagents and following protocols supplied by the manufacturer. The biotinylated cRNA (750 ng/sample) was hybridized on Sentrix beadchips human Ref-8v3 for 18 h at 58ºC while rocking (5 rpm).
Project description:Cultures of A-498 cells were treated for 120hours with 1000µM zebularine (SIGMA) in three independent biological experiments. Zebularine acts as a DNA methyltransferase (DNMT) inhibitor thereby upregulating genes that are inactivated by e.g. promotor hypermethylation. The experiment aimed to search for upregulated transcripts to provide new targets for biomarker development and therapeutic use. 308 candidates were upregulated more than 1.5-fold. Members of the metallothionein group (MT1G, MT1H, and MT2A) were validated in 49 clinical samples of renal cell carcinomas. Total RNA of treated (1000µM zebularine) and untreated A-498 cells (experiment A05-A07) was subjected to Affymetrix array analysis to detail the overall expression changes after treatment with a DNMT inhibitor. Treated cells showed no obvious signs of zebularine-induced cytotoxicity as revealed by XTT assays. Cell were split twice during the 120hour treatment period.