Project description:Reactivation of the telomerase reverse transcriptase subunit, TERT, is linked to tumourigenesis due to well-documented telomere-dependent and independent functions. The aim of this study was to investigate the effect of the telomerase inhibitor, MST-312, on TERT functions, focusing in particular, on its effects on MYC stabilty and MYC-regulated pathways, in order to assess its potential as a therapeutic agent. We demonstrate that MST-312 reduces MYC levels in cancer cells, leading to reduced MYC levels on chromatin, and subsequently affecting the MYC-regulated transcriptional program. As a result, MST-312 treatment increases the survival of lymphoma-bearing mice. Mechanistically, MST-312 affects the conformation of TERT, leading to TERT/Terc dissociation, and the subsequent loss of both its telomere-dependent and independent functions. Based on the presented data, we conclude that MST-312 treatment is a promising therapeutic strategy, in particular, in MYC-driven tumorus.
Project description:Reactivation of the telomerase reverse transcriptase subunit, TERT, is linked to tumourigenesis due to well-documented telomere-dependent and independent functions. The aim of this study was to investigate the effect of the telomerase inhibitor, MST-312, on TERT functions, focusing in particular, on its effects on MYC stabilty and MYC-regulated pathways, in order to assess its potential as a therapeutic agent. We demonstrate that MST-312 reduces MYC levels in cancer cells, leading to reduced MYC levels on chromatin, and subsequently affecting the MYC-regulated transcriptional program. As a result, MST-312 treatment increases the survival of lymphoma-bearing mice. Mechanistically, MST-312 affects the conformation of TERT, leading to TERT/Terc dissociation, and the subsequent loss of both its telomere-dependent and independent functions. Based on the presented data, we conclude that MST-312 treatment is a promising therapeutic strategy, in particular, in MYC-driven tumorus.
Project description:Chromatin immunoprecipitation sequencing (ChIP-seq) was performed to analyze the effect of telomerase inhibition on TNFM-NM-1-induced genome-wide p65 binding in HeLa cells. By obtaining over 40 million uniquely mappable reads per sample from ChIP-seq, maps for TNFM-NM-1-induced p65 binding in absence and presence of an hTERT inhibitor, MST-312, were generated. As expected, TNFM-NM-1 treatment significantly increased genome-wide p65 occupancy. Interestingly, when cells were treated with MST-312 prior to TNFM-NM-1 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 TNFM-NM-1 and MST-312.
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.
Project description:Gene expression changes of UC-model organoids derive from human colon indcued by telomere enlongation was assessed by Madecassoside treatemt (telomerase activator). Gene expression changes of human colon organoids induced by telomere shortening was assessd by MST-312 treatment (telomerase inhibitor).
Project description:In a fluorescence polarization screen for MYC-MAX interaction, we have identified a novel small molecule inhibitor of MYC, KJ-Pyr-9, from a Kröhnke pyridine library. The Kd of KJ-Pyr-9 for MYC in vitro is 6.5 ± 1.0 nM as determined by backscattering interferometry; KJ-Pyr-9 also interferes with MYC-MAX complex formation in the cell as shown in a protein fragment complementation assay. KJ-Pyr-9 specifically inhibits MYC-induced oncogenic transformation in cell culture; it has no or only weak effects on the oncogenic activity of several unrelated oncoproteins. KJ-Pyr-9 preferentially interferes with the proliferation of MYC-overexpressing human and avian cells and specifically reduces the MYC-driven transcriptional signature. In vivo, KJ-Pyr-9 effectively blocks the growth of a xenotransplant of MYC-overexpressing human cancer cells. 4 treatment groups analyzed in triplicate: no treatment(control), 20uM KJ-Pyr-9, 0.1ug/mL doxycycline and KJ-Pyr-9 in combination with doxycycline
Project description:MYC genes have both essential roles during normal development and exert oncogenic functions during tumorigenesis. Expression of a dominant-negative allele of MYC, termed OmoMYC, can induce rapid tumor regression in mouse models with little toxicity for normal tissues. How OmoMYC discriminates between physiological and oncogenic functions of MYC is unclear. We have solved the crystal structure of OmoMYC and show that it forms a stable homodimer and as such recognizes DNA in the same manner as the MYC/MAX heterodimer. OmoMYC attenuates both MYC-dependent activation and repression by competing with MYC/MAX for binding to chromatin, effectively lowering MYC/MAX occupancy at its cognate binding sites. OmoMYC causes the largest decreases in promoter occupancy and changes in expression on genes that are invaded by oncogenic MYC levels. A signature of OmoMYC-regulated genes defines subgroups with high MYC levels in multiple tumor entities and identifies novel targets for the eradication of MYC-driven tumors.
Project description:Constitutively active MYC and reactivated telomerase often co-exist in cancers. While the reactivation of telomerase is thought to be essential for replicative immortality, MYC, in conjunction with co-factors, confers several growth advantages to cancer cells. However, it is unclear which co-factors sustain elevated MYC activity in tumours . Here, we identify TERT, the catalytic subunit of telomerase, as a novel regulator of MYC stability in cancers. Binding of TERT to MYC stabilizes its levels on chromatin, contributing to either activation or repression of its target genes. Mechanistically, TERT regulates MYC ubiquitination and stability, and this effect of TERT is independent of its role on telomeres. Genetic inhibition and knocking out of TERT phenocopied the loss of MYC, resulting in reduced disease burden of early- and late-stage MYC-driven murine lymphomas. Conversly, the ectopic expression of TERT could substitute for reduced MYC in these functions. Finally we show that TERT null mice, unlike Terc null mice, show delayed onset of MYC induced lymphomagenesis. Accordingly, inhibiting TERT function in primary human leukemia cells blocked the expression of MYC targets, while Terc depletion had no effects . Based on our data, we conclude that the re-expression of TERT, a direct MYC target in tumors, provides a feed-forward mechanism to potentiate MYC-dependent oncogenesis. ChIP was performed using anti-MYC (sc-764) in primary lymphoma cells from Eµ-Myc;Tert -/- mice, Eµ-Myc;Tert +/+ mice, or in P493 cells treated with shTert, P493 shTerc and shControl.