Zalypsis: A novel marine-derived compound with potent antimyeloma activity
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE13662 | GEO | 2008/11/30
SECONDARY ACCESSION(S): PRJNA110213
REPOSITORIES: GEO
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Project description:Multiple Myeloma (MM) remains incurable, and new drugs with novel mechanisms of action are still needed. In this report, we have analyzed the action of Zalypsis, an alkaloid analogous to certain natural marine compounds, in MM. Zalypsis turned out to be the most potent antimyeloma agent we have tested so far, with IC50s from picomolar to low nanomolar ranges. It also showed remarkable ex vivo potency in plasma cells from patients and in MM cells in vivo xenografted in mice. Besides the induction of apoptosis and cell cycle arrest, Zalypsis provoked DNA double-strand-breaks (DSB), evidenced by an increase in phospho-Histone-H2AX and phospho-CHK2, followed by a striking overexpression of p53 in p53-wild type cell lines. In addition, in those cell lines in which p53 was mutated, Zalypsis also provoked DSB and induced cell death, although higher concentrations were required. Immunohistochemical studies in tumours also demonstrated Histone-H2AX phosphorylation and p53 overexpression. Gene expression profile studies were concordant with these results, revealing an important deregulation of genes involved in DNA-damage response. The potent in vitro and in vivo antimyeloma activity of Zalypsis uncovers the high sensitivity of tumour plasma cells to DSB, and strongly supports the use of this compound in MM patients. Experiment Overall Design: MM cells treated in vitro with Zalypsis (5 nM) were harvested at the beginning of induction of cell death (15-20% cell death as assessed by Annexin V-FITC staining). Total RNA was extracted using Trizol reagent (Life Technologies, MD, USA) and purified with RNAeasy Mini Kit (Qiagen, CA, USA). RNA integrity was verified with the Agilent 2100 Bioanalyzer (Agilent, CA, USA). Double-stranded cDNA and biotinylated cRNA were synthesized with T7-polyT primer and the BioArray RNA labeling kit (Enzo, NY, USA), respectively. The labelled RNA was then fragmented and hybridized to HG-U133 Plus 2.0 oligonucleotide arrays (Affymetrix, CA, USA), which were scanned in a Gene Array Scanner and analyzed using the DNA-Chip Analyzer software (DChip). Changes in gene expression greater than two-fold were considered significant.
2009-01-13 | E-GEOD-13662 | biostudies-arrayexpress
Project description:In Saccharomyces cerevisiae, a single double-strand break (DSB) triggers extensive phosphorylation of histone H2A (known as gammaH2AX) over 50 kb on either side of the DSB. This modification is carried out by either of yeastM-^Rs checkpoint kinases, the ATM homolog, Tel1, or the ATR homolog, Mec1. In G1-arrested cells, where there is very little 5M-^R to 3M-^R processing of DSB ends, only Tel1 promotes this modification. We have recently described a second modification gammaH2B - the phosphorylation of the C terminal T129 locus of histone H2B which is also carried out by both Mec1 and Tel1 kinases. To understand in detail how gamma-H2AX and gamma-H2B spread along the chromosome from a DSB we have undertaken a high-density analysis of their occupancy where there is a DSB on three different chromosomes. gamma-H2AX and gamma-H2B modifications are similar, but there is a marked absence of gamma-H2B near telomeres. We find that there is reduced gamma-H2AX and gamma-H2B modification over strongly transcribed regions, even taking into account the reduced histone occupancy of these genes. When transcription of the galactose-regulated genes GAL1, GAL10, GAL7 are turned off by the addition of glucose, gamma-H2AX is restored within 5 min; when these genes are again induced, gamma-H2AX is rapidly lost. Regions more distal to the GAL genes have markedly reduced gamma-H2AX levels that rise rapidly when transcription is repressed, suggesting that transcription acts as a barrier to the propagation of gamma-H2AX away from the DSB. The restoration of gamma-H2AX in transcribed regions can be carried out by either Mec1 or Tel1, even 7 h after break induction, suggesting that Tel1 remains associated with damaged chromosomes for an extended time. In addition, we show that gamma-H2AX can be transferred in trans, to regions unlinked to the DSB that lie in close proximity the DSB. Specifically, if a DSB is generated 14 kb from CEN2, gamma-H2AX is transferred to regions around all the other centromeres, in keeping with observed close proximity of all centromere-adjacent chromosome arms. This transfer can be observed even in the absence of formaldehyde crosslinking of the samples.
2013-12-15 | E-MTAB-1409 | biostudies-arrayexpress
Project description:Recent observations show that the single-cell response of p53 to ionizing radiation (IR) is “digital” in that it is the number of oscillations rather than the amplitude of p53 that shows dependence on the radiation dose. We present a model of this phenomenon. In our model, double-strand break (DSB) sites induced by IR interact with a limiting pool of DNA repair proteins, forming DSB–protein complexes at DNA damage foci. The persisting complexes are sensed by ataxia telangiectasia mutated (ATM), a protein kinase that activates p53 once it is phosphorylated by DNA damage. The ATM-sensing module switches on or off the downstream p53 oscillator, consisting of a feedback loop formed by p53 and its negative regulator, Mdm2. In agreement with experiments, our simulations show that by assuming stochasticity in the initial number of DSBs and the DNA repair process, p53 and Mdm2 exhibit a coordinated oscillatory dynamics upon IR stimulation in single cells, with a stochastic number of oscillations whose mean increases with IR dose. The damped oscillations previously observed in cell populations can be explained as the aggregate behavior of single cell
2020-05-13 | MODEL2005130001 | BioModels
Project description:The structure of broken DNA ends is a critical determinant of the pathway used for DNA double strand break (DSB) repair. Here, we develop an approach, hairpin capture of DNA end structures (HCoDES), which elucidates chromosomal DNA end structures at single nucleotide resolution. HCoDES defines structures of physiologic DSBs generated by the RAG endonuclease, as well as those generated by nucleases widely used for genome editing. Analysis of G1-phase cells deficient in H2AX or 53BP1 reveals DNA ends that are frequently resected to form long single-stranded overhangs that can be repaired by mutagenic pathways. In addition to 3’ overhangs, many of these DNA ends unexpectedly form long 5’ single-stranded overhangs. The divergence in DNA end structures resolved by HCoDES suggests that H2AX and 53BP1 may have distinct activities in end protection. Thus, the high-resolution end structures obtained by HCoDES identify new features of DNA end processing during DSB repair. Single stranded DNA ligation of genomic DNA isolated from G1 arrested LigaseIV-/-, LigaseIV-/- 53BP1-/- and LigaseIV-/- H2AX-/- Abelson pre-B cells harboring site specific DSBs generated by the RAG recombinase, Cas9 endonuclease or Zinc Finger Endonuclease.
2014-12-03 | E-GEOD-62534 | biostudies-arrayexpress
Project description:Phosphorylation of the histone variant H2AX forms M-NM-3-H2AX that marks DNA double-strand break (DSB). Here we generated the sequencing-based maps of H2AX and M-NM-3-H2AX positioning in resting and proliferating cells before and after ionizing irradiation. Genome-wide locations of possible endogenous and exogenous DSBs were identified based on M-NM-3-H2AX distribution in dividing cancer cells without irradiation and that in resting cells upon irradiation, respectively. M-NM-3-H2AX-enriched regions of endogenous origin in replicating cells included telomeres and active transcription start sites, apparently reflecting replication- and transcription-mediated stress during rapid cell division. Surprisingly, H2AX itself, prior to phosphorylation, was specifically located at these endogenous hotspots. This phenomenon was only observed in dividing cancer cells but not in resting cells. Endogenous H2AX was concentrated on the transcription start site of actively transcribed genes but was irrelevant to pausing of RNA polymerase II (pol II), which precisely coincided with M-NM-3-H2AX of endogenous origin. M-NM-3-H2AX enrichment upon irradiation also coincided with actively transcribed regions, but unlike endogenous M-NM-3-H2AX, it extended into the gene body and was not specifically concentrated on the pausing site of pol II. Subtelomeres were not responsive to external DNA damage. Our findings provide insight into DNA repair programs of cancer and may have implications for cancer therapy. Profiles of H2AX and gamma-H2AX in normal resting and cancer T cells with and without ionizing irradiation.
2012-04-03 | E-GEOD-25577 | biostudies-arrayexpress
Project description:Phosphorylation of the histone variant H2AX forms γ-H2AX that marks DNA double-strand break (DSB). Here we generated the sequencing-based maps of H2AX and γ-H2AX positioning in resting and proliferating cells before and after ionizing irradiation. Genome-wide locations of possible endogenous and exogenous DSBs were identified based on γ-H2AX distribution in dividing cancer cells without irradiation and that in resting cells upon irradiation, respectively. γ-H2AX-enriched regions of endogenous origin in replicating cells included telomeres and active transcription start sites, apparently reflecting replication- and transcription-mediated stress during rapid cell division. Surprisingly, H2AX itself, prior to phosphorylation, was specifically located at these endogenous hotspots. This phenomenon was only observed in dividing cancer cells but not in resting cells. Endogenous H2AX was concentrated on the transcription start site of actively transcribed genes but was irrelevant to pausing of RNA polymerase II (pol II), which precisely coincided with γ-H2AX of endogenous origin. γ-H2AX enrichment upon irradiation also coincided with actively transcribed regions, but unlike endogenous γ-H2AX, it extended into the gene body and was not specifically concentrated on the pausing site of pol II. Subtelomeres were not responsive to external DNA damage. Our findings provide insight into DNA repair programs of cancer and may have implications for cancer therapy.
2012-04-04 | GSE25577 | GEO
Project description:The purpose of this research is to study the mechanism of the synergistic effect combining EZH2 inhibition and PI3K inhibition. In this study, we observed that the PIK3CA-mutant or amplified lung cancer cells were more sensitive to EZH2 inhibition. PIK3CA E545K, the most common mutation in lung cancer, harbored a modest transformation capacity along with p53 loss in lung epithelial cells, and developed adenocarcinoma autochthonously. EZH2 inhibitor synergized with PI3K inhibitor in human cancer cells in vitro and worked together efficiently in vivo. Mechanistically, EZH2 inhibition cooperated with PI3K inhibition to produce a more potent suppression of phospho-AKT downstream of PI3K.
2021-10-12 | GSE183818 | GEO
Project description:Purpose: Severe late normal tissue damage limits radiotherapy treatment regimens. This study aims to validate γ-H2AX foci decay ratios and induced expression levels of DNA double strand break (DSB) repair genes, found in a retrospective study, as possible predictors for late radiation toxicity. Methods and Materials: Prospectively, decay ratios (initial/residual γ-H2AX foci numbers) and genome-wide expression profiles were examined in ex vivo irradiated lymphocytes of 198 prostate cancer patients. All patients were followed ≥2 years after radiotherapy, clinical characteristics were assembled and toxicity was recorded using the Common Terminology Criteria (CTCAE) v4.0. Results: No clinical factors were correlated with late radiation toxicity. Analysis of γ-H2AX foci uncovered a negative correlation between the foci decay ratio and toxicity grade. Significantly smaller decay ratios were found in grade≥3 compared to grade 0 patients (p=0.02), indicating less efficient DNA-DSB repair in radio-sensitive patients. Moreover, utilizing a foci decay ratio threshold determined in our previous retrospective study correctly classified 23 of the 28 grade≥3 patients (sensitivity, 82%) and 9 of the 14 grade 0 patients (specificity, 64%). Grade of toxicity also correlated with a reduced induction of the homologous recombination (HR) repair gene-set. The difference in average fold induction of the HR gene-set was most pronounced between grade 0 and grade≥3 patients (p=0.008). Conclusions: Reduced responsiveness of HR repair genes to irradiation and inefficient DSB repair correlate with an increased risk of late radiation toxicity. Using a decay ratio classifier, we could correctly classify 82% of the patients with grade≥3 toxicity. Additional studies are required to further optimize and validate the foci decay assay and to assess its predictive value for late radiation toxicity in patients prostate cancer
2017-01-30 | GSE85570 | GEO
Project description:H2AX phosphorylation at Ser139 (gH2AX) is an early key event of the DNA damage response (DDR) following DNA double strand breaks (DSB) induction. Although gH2AX distribution has been extensively used as a damage marker, genome-wide investigation of the subsequent DNA repair has been poorly addressed. Here we present ChIP-Seq-based distributions of Histone H3, H2AX and gH2AX under physiological conditions in HeLa cells. Additionally the same histones were studied after a single exposure to 10 Gy X-ray at 0.5, 3 and 24 hours post irradiation
2017-04-17 | GSE60526 | GEO
Project description:p53 is a potent tumor suppressor and commonly mutated in human cancers. Recently, we demonstrated that p53 genes act to restrict retrotransposons in germ line tissues of flies and fish but whether this activity is conserved in somatic human cells is not known. Here we show that p53 constitutively restrains human LINE1s by cooperatively engaging sites in the 5’UTR and stimulating local deposition of repressive histone marks at these transposons. Consistent with this, the elimination of p53 or the removal of corresponding binding sites in LINE1s, prompted these retroelements to become hyperactive. Concurrently, p53 loss instigated chromosomal rearrangements linked to LINE sequences and also provoked inflammatory programs that were dependent on reverse transcriptase produced from LINE1s. Taken together, our observations establish that p53 continuously operates at the LINE1 promoter to restrict autonomous copies of these mobile elements in human cells. Our results further suggest that constitutive restriction of these retroelements may help to explain tumor suppression encoded by p53, since erupting LINE1s produced acute oncogenic threats when p53 was absent.
2020-12-01 | GSE159134 | GEO