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Transient telomere dysfunction induces chromosomal instability and promotes carcinogenesis in telomerase-proficient mice

ABSTRACT: 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.

ORGANISM(S): Mus musculus

PROVIDER: GSE36813 | GEO | 2012/03/31

SECONDARY ACCESSION(S): PRJNA157343

REPOSITORIES: GEO

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Transient telomere dysfunction induces chromosomal instability and promotes carcinogenesis in telomerase-proficient mice

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.

2012-03-30 | E-GEOD-36813 | biostudies-arrayexpress

Mus musculus

Project description:Transient telomere dysfunction induces chromosomal instability and promotes carcinogenesis in telomerase-proficient mice

| PRJNA157343 | ENA

Mammalian telomeres reforged with non-telomeric sequences

Project description:Telomere is a highly refined system for maintaining the stability of linear chromosomes. Most telomeres rely on simple repetitive sequences and telomerase enzymes, but in some species or telomerase-defective situations, alternative telomere lengthening (ALT) mechanism is utilized to protect chromosomal ends. Telomere loss can induce telomere recombination by which specific sequences can be recruited into telomeres. However, canonical telomeric repeat-based telomeres have been found in mammals. Here, we show that mammalian telomeres can also be completely reconstituted using a non-telomeric unique sequence. We found that a specific subtelomeric element, named as mouse template for ALT (mTALT), is utilized for repairing telomeric DNA damage and composing new telomeric sequences in mouse embryonic stem cells. We found a high-level of non-coding mTALT transcript despite the heterochromatic nature of mTALT-based telomere. After ALT activation, the increased HMGN1, a non-histone chromosomal protein, contributed to maintaining telomere stability by regulating telomeric transcriptions. Our findings reveal novel molecular features of potential telomeric sequences which can reconstitute telomeres during cancer formation and evolution.

2020-07-17 | MSV000085772 | MassIVE

Expression data between WT and G3/4 Terc KO mouse ESCs during differentiation

Project description:Mammalian telomeres are formed by tandem repeats of the TTAGGG sequence, and shorten with each round of cell division in the absence of telomerase. Telomere shortening and dysfunction has been implicated in the pathology of several age-related diseases and premature ageing syndromes. Telomerase is important for telomere length maintenance. Telomerase RNA component, also known as TERC, is a component of telomerase. Terc knockout leads to telomerase deficiency and telomere shortening. Heterozygous telomerase-deficient (Terc+/-) mice were housed and bred for homozygous generation. ESC lines were generated with high efficiency from wild-type (WT, Terc+/+), heterozygous (Het, Terc+/-) and early- to late-generation (G1, G3 and G4) Terc-/- mouse blastocysts. Telomeres were shorter in Terc+/- ES cells than in WT ES cells, and further shortened from G1 to G4 Terc-/- ES cells. We took advantage of ES cell lines with various telomere lengths to investigate roles of telomere length on differentiation capacity of ES cells. We found that telomere length, but not telomerase activity, is required for differentiation of ES cells into epidermis. We performed microarray analysis to investigate differential gene expression profile at genome-wide levels between WT and G3/G4 Terc-/- (KO) mouse ES cells and during differentiation in vitro of WT and G4 Terc-/- mouse ES cells.

2016-01-29 | GSE77362 | GEO

Telomeric Chromosomal Instability Fosters Paracrine Mediated Cell Competition to Initiate Intestinal Cancer (WGS)

Project description:Telomere dysfunction drives chromosomal instability (CIN) during the transition from benign adenoma to malignant adenocarcinoma. While CIN provides a mutator mechanism for cancer- relevant genomic events, its role in shaping tumor biology during carcinogenesis is not well understood. Here, we explored the molecular and biological impact of telomere dysfunction and associated CIN in vivo in a faithful model of CRC. In vivo lineage tracing revealed that CIN increased the rate of neoplastic cell clonal expansion through accelerated differentiation of neighboring stem cells, resulting in increased number of adenomas and decreased survival in CIN-high Apcmin mice. Mechanistically, CIN represses EZH2 leading to upregulation of secreted Wnt antagonists, which resulted in a growth advantage to CIN-high neoplastic cells. Correspondingly, pharmacological activation of intrinsic WNT signaling enhanced intestinal stem cells fitness, leading to reduced neoplastic cell clonal expansion and adenoma burden. Thus, the CIN-EZH2-WNT axis enhances intestinal cancer initiation in the nascent tumor microenvironment, providing a preventive strategy for patients harboring germline APC mutations.

2024-03-05 | GSE229828 | GEO

Telomeric Chromosomal Instability Fosters Paracrine Mediated Cell Competition to Initiate Intestinal Cancer [bulk RNA-seq]

2024-03-01 | GSE234032 | GEO

Telomeric Chromosomal Instability Fosters Paracrine Mediated Cell Competition to Initiate Intestinal Cancer [scRNA-seq]

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Telomeric Chromosomal Instability Fosters Paracrine Mediated Cell Competition to Initiate Intestinal Cancer [CUT&RUN]

2024-03-01 | GSE234030 | GEO

ZNF365 promotes stability of fragile sites and telomeres

Project description:Critically short telomeres activate cellular senescence or apoptosis, as mediated by the tumor suppressor p53, but in the absence of this checkpoint response, telomere dysfunction engenders chromosomal aberrations and cancer. Here, analysis of p53-regulated genes activated in the setting of telomere dysfunction identified Zfp365 (ZNF365 in humans) as a direct p53 target that promotes genome stability. Germline polymorphisms in the ZNF365 locus are associated with increased cancer risk, including those associated with telomere dysfunction. On the mechanistic level, ZNF365 suppresses expression of a subset of common fragile sites (CFS) including telomeres. In the absence of ZNF365, defective telomeres engage in aberrant recombination of telomere ends, leading to increased telomere sister chromatid exchange (T-SCE) and formation of anaphase DNA bridges, including ultra-fine DNA bridges (UFB), and ultimately increased cytokinesis failure and aneuploidy. Thus, the p53-ZNF365 axis contributes to genomic stability in the setting of telomere dysfunction. We expressed an inducible p53 allele encoding a p53-estrogen receptor fusion protein (p53ER) that becomes functional upon addition of 4-hydroxytamoxifen (4-OHT) in TKO cells. We chose a time point of 4 hours post-4-OHT induction to catalog potential direct targets.

2013-08-01 | E-GEOD-44599 | biostudies-arrayexpress

Gene Expression Analysis of Melanoma Cells Treated with 6-Thio-dG In Vitro

Project description:Telomerase promoter mutations are highly prevalent in human tumors including melanoma. Telomere transcriptional signatures are enriched in a subset of therapy-naïve melanomas associated with worse overall survival, in BRAF-mutant intrinsically resistant melanoma cells that evade MAPK inhibitors (MAPKi), as well as in a subset of post-treatment tumor biopsies derived from patients who have disease progression on MAPKi or the immune checkpoint inhibitors, anti-CTLA-4 or anti-PD1. We demonstrate the efficacy of a telomerase-directed nucleoside, 6-thio-2'-deoxyguanosine (6-thio-dG) that results in telomere dysfunction and cell death in various models of therapy-resistant cells. Furthermore, 6-thio-dG significantly inhibits tumor growth of primary tumor biopsy cultures derived from patients who had disease progression on multiple therapies including anti-CTLA-4 or anti-PD1.

2017-06-02 | GSE99552 | GEO

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