Affymetrix SNP array data for a Diffuse Large B-cell Lymphoma case with a TERT promoter variant who later developed Chronic Myelomonocytic Leukemia
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ABSTRACT: TERT promoter variants are well known in solid tumors. However, less is known in hematological malignancies, thus we screened a large series of MDS and MDS/MPN.
Project description:Affymetrix SNP array data for a Diffuse Large B-cell Lymphoma case with a TERT promoter variant who later developed Chronic Myelomonocytic Leukemia
Project description:All cancer cells must adopt a telomere maintenance mechanism to achieve replicative immortality. Most human cancer cells utilize the enzyme telomerase to maintain telomeres. Alternative splicing of TERT regulates the amount and function of telomerase, however many alternative splicing isoforms of TERT have unknown functions. Single molecule long read RNA/cDNA sequencing of TERT revealed 45 TERT mRNA variants including 13 known and 32 novel variants. Among the variants, TERT Delta 2-4, which lacks exons 2-4 but retains the original open reading frame, was selected for further study. Induced pluripotent stem cells and cancer cells express higher levels of TERT Delta 2-4 compared to primary human bronchial epithelial cells. Overexpression of TERT Delta 2-4 enhanced clonogenicity and resistance to cisplatin- induced apoptosis. Knockdown of endogenous TERT Delta 2-4 in Calu-6 cells reduced clonogenicity and resistance to cisplatin. Our results suggest that TERT Delta 2-4 enhances cancer cells’ resistance to intrinsic apoptosis. RNA sequencing following knockdown of Delta 2-4 TERT indicates that translation is downregulated and that mitochondrial related proteins are upregulated compared to controls. Overall, our data indicate that TERT produces many isoforms that influence the function TERT and the abundance and activity of telomerase.
Project description:Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line, B16F10, we have previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression. To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here we report the identification of PITX1, whose restoration leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We showed that three and one binding sites, respectively, within the hTERT and mtert promoters that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity.
Project description:Analysis of TERT-regulated global gene expression changes. The hypothesis tested in the present study was that neuronal TERT influences the regulation of gene expressions. Results provide important information of the response of in vivo mouse neurons to physiological TERT induction.
Project description:Using microcell-mediated chromosome transfer (MMCT) into the mouse melanoma cell line, B16F10, we have previously found that human chromosome 5 carries a gene, or genes, that can negatively regulate TERT expression. To identify the gene responsible for the regulation of TERT transcription, we performed cDNA microarray analysis using parental B16F10 cells, telomerase negative B16F10 microcell hybrids with a human chromosome 5 (B16F10MH5), and its revertant clones (MH5R) with reactivated telomerase. Here we report the identification of PITX1, whose restoration leads to the downregulation of mouse tert (mtert) transcription, as a TERT suppressor gene. Additionally, both human TERT (hTERT) and mouse TERT (mtert) promoter activity can be suppressed by PITX1. We showed that three and one binding sites, respectively, within the hTERT and mtert promoters that express a unique conserved region are responsible for the transcriptional activation of TERT. Furthermore, we showed that PITX1 binds to the TERT promoter both in vitro and in vivo. Thus, PITX1 suppresses TERT transcription through direct binding to the TERT promoter, which ultimately regulates telomerase activity. We transferred intact human chromosome 5 into mouse melanoma B16F10 cells by microcell fusion. The microcell hybrids (MH5) exhibited suppression of telomerase, we also obtained revertant clones (MH5R) in which telomerase is reactivated. To identify the differentially expressed genes on human chromosome 5, we performed expression microarray analysis using these two clones and parental B16F10 cells.
Project description:All cancer cells must adopt a telomere maintenance mechanism to achieve replicative immortality. Most human cancer cells utilize the enzyme telomerase to maintain telomeres. Alternative splicing of TERT regulates the amount and function of telomerase, however many alternative splicing isoforms of TERT have unknown functions. Single molecule long read RNA/cDNA sequencing of TERT revealed 45 TERT mRNA variants including 13 known and 32 novel variants. Among the variants, TERT Delta 2-4, which lacks exons 2-4 but retains the original open reading frame, was selected for further study. Induced pluripotent stem cells and cancer cells express higher levels of TERT Delta 2-4 compared to primary human bronchial epithelial cells. Overexpression of TERT Delta 2-4 enhanced clonogenicity and resistance to cisplatin- induced apoptosis. Knockdown of endogenous TERT Delta 2-4 in Calu-6 cells reduced clonogenicity and resistance to cisplatin. Our results suggest that TERT Delta 2-4 enhances cancer cells’ resistance to intrinsic apoptosis. RNA sequencing following knockdown of Delta 2-4 TERT indicates that translation is downregulated and that mitochondrial related proteins are upregulated compared to controls. Overall, our data indicate that TERT produces many isoforms that influence the function TERT and the abundance and activity of telomerase.
Project description:Point mutations within the TERT promoter are the most common recurrent somatic non-coding mutation identified across different cancer types, including glioblastoma, melanoma, hepatocellular carcinoma and bladder cancer. They are most abundant at C146T and C124T and more rare at A57C, with the latter originally described as a familial case but subsequently shown also to occur somatically. All three mutations create de novo ETS (E-twenty-six specific) binding sites and result in the reactivation of the TERT gene, allowing cancer cells to achieve replicative immortality. Here, we employed a systematic proteomics screen to identify transcription factors preferentially binding to the C146T, C124T and A57C mutations. While we confirmed binding of multiple ETS factors to the mutant C146T and C124T sequences, we identified E4F1 a an A57C-specific binder and ZNF148 as a TERT WT binder that is excluded from the TERT promoter by the C124T allele. Both proteins are activating transcription factors that bind specifically to the A57C and wildtype (at position 124) TERT promoter sequence in corresponding cell lines and upregulate TERT transcription and telomerase activity.
Project description:Blocking telomerase is recognized as a key anti-cancer mechanism. Unlike in stem cells, levels of telomerase catalytic subunit TERT are limiting in reconstituting telomerase activity in somatic cells. However in some cancers, Tert is transcriptionally reactivated by mutations in its promoter. Given that Tert in stem cells is driven by WT Tert promoter, if we can selectively target Tert reactivation through mutant Tert promoters we can block telomerase activity specifically in cancer cells without toxicity in stem cells. Here we report the epigenetic regulation of Tert promoter comparing WT and mutant promoters. We showed that GABPA homodimerization through long-range interaction stabilizes Gabpa to drive Tert expression. Furthermore, BRD4 specifically activates the C250T mutant promoter via dual mechanism involving GABPA, thereby setting the stage for future therapeutics.
Project description:The goal of this study is to understand how the specific TERT inhibitor BIBR1532 preconditioning regulates transcriptional reprogramming in mouse neuronal cells. We use CUT-Tag approach to comprehensively map the genomic binding sites of TERT in primary neurons and determine the alteration of is binding profile after BIBR1532 preconditioning. By obtaining over 10 million reads per sample, we generated genome-wide TERT chromatin-binding maps of mouse primary neurons. Under normal conditions, we show that more than 50% of the TERT binding sites were located at the promoter regions, many of them are previously unknown genomic loci. Intriguingly, BIBR1532 preconditioning significantly alters TERT-chromatin binding profile. Out of the total promoter binding sites by TERT, 30.4% (2,837 peaks) and 31.7% (2,954 peaks) are respectively upregulated and downregulated in TERT-binding after BIBR1532 preconditioning. Interestingly, we find that BIBR1532-preconditioned neurons show significant upregulation of promoter binding of TERT to the mitochondrial antioxidant genes. Together, these results identify the previously unknown TERT-binding sites in the mouse primary neurons and demonstrate that BIBR1532 preconditioning confers neuronal ischemic tolerance through TERT-mediated transcriptional reprogramming.
Project description:We discovered a novel small-molecule TERT activating compound (TAC) that selectively enhances TERT transcription in human and mouse adult somatic cells. Our findings also provide the novel mechanism of TAC-mediated TERT up-regulation and elucidate the impact of TERT induction on regulatory factors governing aging.