ABSTRACT: The effect of TMPyP4, the well established anticancer telomerase inhibitor on genome wide expression of genes, analyzed across different cell-lines, was investigated Keywords: Comparative gene-expression profiling Overall design: Cells were treated with TMPyP4 for 48 hours before RNA isolation. Untreated cells were taken as controls and the TMPyP4 treated cells as treatments. Experiments in each cell-line (A549 and HeLa S3) were replicated four times.
Project description:The effect of TMPyP4, the well established anticancer telomerase inhibitor on genome wide expression of genes, analyzed across different cell-lines, was investigated Keywords: Comparative gene-expression profiling Cells were treated with TMPyP4 for 48 hours before RNA isolation. Untreated cells were taken as controls and the TMPyP4 treated cells as treatments. Experiments in each cell-line (A549 and HeLa S3) were replicated four times.
Project description:The effect of TMPyP4, the well established anticancer telomerase inhibitor on genome wide expression of genes was investigated Keywords: Time course Cells were treated with TMPyP4 for either 24 or 48 hours before RNA isolation.Untreated cells were taken as controls and the TMPyP4 treated cells as treatments. Experiments at each time point were replicated four times.
Project description:The effect of TMPyP4, the well established anticancer telomerase inhibitor on genome wide expression of genes was investigated Keywords: Time course Overall design: Cells were treated with TMPyP4 for either 24 or 48 hours before RNA isolation.Untreated cells were taken as controls and the TMPyP4 treated cells as treatments. Experiments at each time point were replicated four times.
Project description:Chromatin immunoprecipitation sequencing (ChIP-seq) was performed to analyze the effect of telomerase inhibition on TNFα-induced genome-wide p65 binding in HeLa cells. By obtaining over 40 million uniquely mappable reads per sample from ChIP-seq, maps for TNFα-induced p65 binding in absence and presence of an hTERT inhibitor, MST-312, were generated. As expected, TNFα treatment significantly increased genome-wide p65 occupancy. Interestingly, when cells were treated with MST-312 prior to TNFα stimulation, the number of p65 binding sites was reduced. In addition, some binding sites, including important p65 targets like IL6 and TNF, showed a reduced p65 occupancy with a minimum fold change of 1.5, after MST-312 exposure. Taken together, our ChIP-seq data indicate that telomerase is required for optimal p65 binding at a small proportion of p65 target sites upon inflammatory stimuli. Examination of p65 binding in HeLa cells in absence and presence of TNFα and MST-312.
Project description:GRN163L is a potent and specific telomerase inhibitor and in clinical trials for cancer treatment. To identify the biomarker that might predict response to telomease based therapy, gene expression analysis of the cancer cell lines after treatiment with telomerase inhibitor Imetelstat (GRN163L) was performed. Overall design: HCT116, Colo205, OVCAR5 cells were either vehicle treated or Imetelstat treated for 2 weeks and then total RNA was preppared, which was then used to analyze for gene expression using Illumina expression array.
Project description:With the increase of atmospheric oxygen 2.3 billion years ago, mechanisms evolved to mitigate the toxic effects of oxygen radicals. Telomeres appear particularly susceptible to oxidative damage, which leads to cellular and organismal aging, cancer, cardiac failure and other diseases. Specific mechanisms of telomere protection from oxidative damage and the molecular consequences of the damage have not been described. Here, we identify the antioxidant enzyme peroxiredoxin 1 (PRDX1) enriched in telomeric chromatin in S and G2 phases of the cell cycle during which telomeres become replicated. PRDX1 depletion leads to oxidative damage of telomeric DNA without affecting the bulk of genomic DNA. The oxidized nucleotide 8-oxo-2’deoxyguanosine-5’-triphosphate (8oxodGTP) can be incorporated by telomerase into telomeric repeats but it mediates premature chain termination when incorporated as first G in the telomeric 5’-TTAGGG-3’ sequence. In dependency of the alignment position within the telomerase RNA template, terminus 8oxoG containing DNA substrates also completely block extension by telomerase. We propose two major mechanisms by which PRDX1 counteracts telomere damage and aging. In safeguarding telomeres from oxygen radicals, PRDX1 prevents DNA damage, telomere replication defects and mutations that will perturb recognition of telomeric DNA by shelterin components. In preventing modification of the telomeric DNA substrate and the dNTP pool, PRDX1 preserves telomeres for elongation by telomerase.
Project description:Mutant template human telomerase RNAs (MT-hTers) have been shown to induce apoptosis in various cancer cells with high telomerase activity. However, the mechanism by which MT-hTers inhibit growth of cancer cells and their effects on normal cells remain unknown. To determine the effects of MT-hTers on normal cells, MT-hTer-47A and -AU5 were introduced into IMR90 lung fibroblasts that have low telomerase levels. Growth of IMR90 cells following MT-hTers infection was not significantly impaired; however, similar treatments in telomerase-overexpressing IMR90 (IMR90 WThTERT) cells inhibited cell proliferation and induced apoptosis. Confocal microscopy showed that MT-hTers induced DNA damage foci i.e. 53BP1 and γ-H2AX in IMR90 WThTERT cells. Microarray analysis revealed that GADD45γ was significantly elevated in MT-hTers treated IMR90 WThTERT cells. MT-hTers also induced ATM phosphorylation at Ser 1981 in IMR90 WThTERT cells, and Western blot analysis revealed high levels of phosphorylated p53 following down-regulation of cellular TRF2 expression in MT-hTers treated IMR90 WThTERT cells. Taken together, we have elucidated that MT-hTers induce double-stranded DNA breaks (DSBs)-like damages in telomerase-positive IMR90 WThTERT cells following phosphorylation of ATM and p53 via suppression of TRF2 which eventually may have led to apoptosis via elevation of GADD45γ. Overall design: MT-hTer-47A and -AU5 were introduced into IMR90 primary lung fibroblasts and immortalized IMR90 WT-hTERT cells. Through microarray analysis, gene expression of MT-hTer-infected IMR90 WT-hTERT cells were compared against MT-hTer-infected IMR90 control cells.
Project description:Background and Aims: Telomere dysfunction can increase tumor initiation by induction of chromosomal instability, but initiated tumor cells need to reactivate telomerase for genome stabilization and tumor progression. However, this concept has not been proven in vivo since appropriate mouse models were lacking. Here, we analyzed hepatocarcinogenesis (i) in a novel mouse model of inducible telomere dysfunction on a telomerase-proficient background, (ii) in telomerase knockout mice with chronic telomere dysfunction (G3 mTerc-/-), and (iii) in wild-type mice with functional telomeres and telomerase. Transient or chronic telomere dysfunction enhanced the rates of chromosomal aberrations during hepatocarcinogenesis, but only telomerase-proficient mice exhibited significantly increased rates of macroscopic tumor formation and cancer cell proliferation in response to telomere dysfunction. In contrast, telomere dysfunction resulted in pronounced accumulation of DNA damage, cell cycle arrest and apoptosis in telomerase-deficient liver tumors. Together, these data provide the first in vivo evidence that transient telomere dysfunction during early and late stages of tumorigenesis can promote chromosomal instability and carcinogenesis in telomerase-proficient mice in the absence of additional genetic checkpoint defects at germline level. RNA from liver tumors derived from from DEN treated TTD+ mice TTD- mice and RNA from normal liver 48h-72h after doxycycline induced transient telomere dysfunction in TTD+ and TTD- liver were isolated and RNA was extracted. Agilent Mouse 4x44K v2 arrays were used. DNA from liver tumors and corrresponding kidney as control derived from from DEN treated TTD+ mice, TTD- mice and mTERC-/- G3 mice was isolated and extracted using Phenol/Chloroform. Agilent Mouse 4x44K and Mouse 1x244K arrays were used.
Project description:Critically short telomeres activate p53-mediated apoptosis, resulting in organ failure and causing malignant transformation. Mutations in genes responsible for telomere maintenance are linked to a number of specific human diseases. We derived induced pluripotent stem cells (iPSCs) from patients with mutations in the TERT and TERC telomerase genes. Telomerase-mutant iPSCs elongated telomeres, but at a lower rate than healthy iPSCs, and the magnitude of the elongation deficit correlated with the specific mutation’s impact on telomerase activity. However, elongation significantly varied among iPSC clones harboring the same mutation, and was affected by genetic and environmental factors. iPSCs cultured in hypoxia showed increased telomere length. Potential influence of residual expression of reprogramming factors on telomerase regulation and telomere length was ruled out by excising the transgenes after successful reprogramming. Evidence for telomerase-independent telomere elongation was not observed in these cells. We demonstrate that telomerase is required for telomere elongation in iPSCs and uncover heterogeneity in telomere maintenance even between clones derived from individual patients or siblings with the same mutation, indicating that telomere phenotype may be influenced by acquired and environmental agents. Our data underscore the necessity of studying multiple clones when using iPSCs to model disease. The exon array were done to validate the pluripotent phenotype of the derived normal and telomerase mutant iPSC and to potentially identify differentially expressed genes in mutant iPSC. Objective: confirming pluripotency by comparing telomerase mutated-, control-iPSC to human ESC and to their parental somatic cells (fibroblast used for iPSC derivation) 20 samples total, 5 different fibroblast cells, 13 iPSC lines, 1 ES line (H1) from different passages