scholarly journals Inhibition of EZH2 transactivation function sensitizes solid tumors to genotoxic stress

2022 ◽  
Vol 119 (3) ◽  
pp. e2105898119
Author(s):  
Yiji Liao ◽  
Chen-Hao Chen ◽  
Tengfei Xiao ◽  
Bárbara de la Peña Avalos ◽  
Eloise V. Dray ◽  
...  
Keyword(s):  
Gene Expression ◽  
Solid Tumors ◽  
Excision Repair ◽  
Genotoxic Stress ◽  
Inhibitory Effect ◽  
Cancer Therapies ◽  
Transactivation Domain ◽  
Castration Resistant Prostate Cancer ◽  
Public Data ◽  
Mechanistic Basis

Drugs that block the activity of the methyltransferase EZH2 are in clinical development for the treatment of non-Hodgkin lymphomas harboring EZH2 gain-of-function mutations that enhance its polycomb repressive function. We have previously reported that EZH2 can act as a transcriptional activator in castration-resistant prostate cancer (CRPC). Now we show that EZH2 inhibitors can also block the transactivation activity of EZH2 and inhibit the growth of CRPC cells. Gene expression and epigenomics profiling of cells treated with EZH2 inhibitors demonstrated that in addition to derepressing gene expression, these compounds also robustly down-regulate a set of DNA damage repair (DDR) genes, especially those involved in the base excision repair (BER) pathway. Methylation of the pioneer factor FOXA1 by EZH2 contributes to the activation of these genes, and interaction with the transcriptional coactivator P300 via the transactivation domain on EZH2 directly turns on the transcription. In addition, CRISPR-Cas9–mediated knockout screens in the presence of EZH2 inhibitors identified these BER genes as the determinants that underlie the growth-inhibitory effect of EZH2 inhibitors. Interrogation of public data from diverse types of solid tumors expressing wild-type EZH2 demonstrated that expression of DDR genes is significantly correlated with EZH2 dependency and cellular sensitivity to EZH2 inhibitors. Consistent with these findings, treatment of CRPC cells with EZH2 inhibitors dramatically enhances their sensitivity to genotoxic stress. These studies reveal a previously unappreciated mechanism of action of EZH2 inhibitors and provide a mechanistic basis for potential combination cancer therapies.

scholarly journals A non-canonical EZH2 function sensitizes solid tumors to genotoxic stress

2020 ◽  
Author(s):  
Yiji Liao ◽  
Chen-Hao Chen ◽  
Neel Shah ◽  
Tengfei Xiao ◽  
Avery Feit ◽  
...  
Keyword(s):  
Dna Repair ◽  
Genotoxic Stress ◽  
New Combination ◽  
Cancer Therapies ◽  
Dna Repair Genes ◽  
Castration Resistant Prostate Cancer ◽  
Loss Of Function ◽  
Inhibitory Function ◽  
Public Data ◽  
Repair Genes

SummaryDrugs that block the activity of the methyltransferase EZH2 are in clinical development for the treatment of non-Hodgkin lymphomas harboring gain-of-function EZH2 mutations that enhance its polycomb repressive function. In contrast, in castration-resistant prostate cancer (CRPC) we have previously reported that EZH2 plays a non-canonical role as a transcriptional activator. In this setting, we now show that EZH2 inhibitors can also block the non-canonical activity of EZH2 and inhibit the growth of CRPC cells. Gene expression and epigenomic profiling of cells treated with EZH2 inhibitors demonstrated that rather than de-repressing tumor suppressor genes silenced by PRC2, EZH2 inhibitors downregulate a set of DNA repair genes that are directly regulated by EZH2. In addition, genome-wide CRISPR/Cas9-mediated loss-of-function screens in the presence of EZH2 inhibitors identified these DNA repair genes to underlie the growth-inhibitory function of these compounds. Interrogation of public data from diverse solid tumor types expressing wild-type EZH2 showed that expression of DNA damage repair genes is significantly correlated with cellular sensitivity to EZH2 inhibitors. Consistent with these findings, treatment of CRPC cells with EZH2 inhibitors dramatically enhanced their sensitivity to genotoxic stress. These studies reveal a previously unappreciated mechanism of action of EZH2 inhibitors and provide a mechanistic basis for potential new combination cancer therapies.

scholarly journals SIRT1 gene expression upon genotoxic damage is regulated by APE1 through nCaRE-promoter elements

2014 ◽  
Vol 25 (4) ◽  
pp. 532-547 ◽  
Author(s):  
Giulia Antoniali ◽  
Lisa Lirussi ◽  
Chiara D'Ambrosio ◽  
Fabrizio Dal Piaz ◽  
Carlo Vascotto ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genome Stability ◽  
Gene Expression Regulation ◽  
Excision Repair ◽  
Genotoxic Stress ◽  
Early Response ◽  
Dna Lesions ◽  
Sirtuin 1 ◽  
Gene Promoters ◽  
Sirt1 Gene

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional protein contributing to genome stability via repair of DNA lesions via the base excision repair pathway. It also plays a role in gene expression regulation and RNA metabolism. Another, poorly characterized function is its ability to bind to negative calcium responsive elements (nCaRE) of some gene promoters. The presence of many functional nCaRE sequences regulating gene transcription can be envisioned, given their conservation within ALU repeats. To look for functional nCaRE sequences within the human genome, we performed bioinformatic analyses and identified 57 genes potentially regulated by APE1. We focused on sirtuin-1 (SIRT1) deacetylase due to its involvement in cell stress, including senescence, apoptosis, and tumorigenesis, and its role in the deacetylation of APE1 after genotoxic stress. The human SIRT1 promoter presents two nCaRE elements stably bound by APE1 through its N-terminus. We demonstrate that APE1 is part of a multiprotein complex including hOGG1, Ku70, and RNA Pol II, which is recruited on SIRT1 promoter to regulate SIRT1 gene functions during early response to oxidative stress. These findings provide new insights into the role of nCaRE sequences in the transcriptional regulation of mammalian genes.

389 Combining transcriptomic- and tissue-based immune biomarkers to evaluate GB1275, a CD11b modulator, as a single agent or with pembrolizumab in patients with advanced solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A414-A414
Author(s):  
Wells Messersmith ◽  
Drew Rasco ◽  
Johann De Bono ◽  
Andrea Wang-Gillam ◽  
Wungki Park ◽  
...  
Keyword(s):  
Gene Expression ◽  
Solid Tumors ◽  
Peripheral Blood ◽  
Post Treatment ◽  
Transcriptomic Analysis ◽  
Gene Set Enrichment Analysis ◽  
Cancer Center ◽  
Advanced Solid Tumors ◽  
Core Tissue ◽  
Dose Dependent

BackgroundGB1275 is a first-in-class CD11b modulator in development as monotherapy and in combination with pembrolizumab or chemotherapy for the treatment of advanced solid tumors. Nonclinical data show that GB1275 reduced influx of tumor-associated myeloid-derived suppressor cells (MDSCs) and macrophages (TAMs), and repolarized M2 immuno-suppressive TAMs towards an M1 phenotype. We hypothesize that GB1275 administration can alleviate myeloid cell-mediated immunosuppressive effects and improve cancer treatment outcomes. A phase 1 trial evaluating GB1275 as monotherapy and in combination with pembrolizumab in specified advanced tumors in ongoing (NCT04060342).MethodsBlood gene expression variations as well as core tissue biopsies pre- and post-treatment were assessed following GB1275 monotherapy and combination with pembrolizumab. After obtaining informed consent, peripheral blood for MDSCs was collected from 21 patients pre- and two weeks post-treatment; core tissue biopsies were collected from 13 patients pre- and post-treatment. The frequency of MDSCs in whole blood was measured using the Serametrix MDSC FACS Assay. Gene expression transcriptome profiles were generated using NovaSeq platform. CD8 staining was performed at Neogenomics, and tumor infiltrating lymphocyte (TIL) quantification was performed by an independent pathologist.ResultsPreliminary statistical analysis of MDSC immunophenotyping pre- and post- treatment is consistent with the proposed mechanism of GB1275, showing modulation of peripheral blood MDSCs in some patients. Preliminary gene expression analysis in the blood showed dose-dependent clusters following treatment with GB1275 alone. Moreover, the transcriptomic analysis revealed two unique expression patterns for patients treated with GB1275 monotherapy or in combination with pembrolizumab. Gene Set Enrichment Analysis showed that the CD11b pathway is downregulated in patients treated with GB1275. Analyses of TIL count revealed an increase in lymphocyte trafficking into the tumor after treatment with GB1275 alone or in combination with pembrolizumab. CD8 expression and transcriptomic analysis are underway and will be presented.ConclusionsGB1275 alone or in combination with pembrolizumab demonstrates biological activity, which may be dose dependent. The observed increase in TILs after treatment is supportive of the mechanism of action of GB1275. Further biomarker analyses in blood and tissues are ongoing and will be correlated with clinical activity in a larger number of patients.Ethics ApprovalThis ongoing study is being conducted in accordance with the the Declaration of Helsinki and Council for International Organizations of Medical Sciences (CIOMS) International Ethical Guidelines. The study was approved by the Ethics Boards of University of Colorado Hospital, Washington University School of Medicine - Siteman Cancer Center, Memorial Sloan Kettering Cancer Center, The Sarah Cannon Research Institute/Tennessee Oncology, South Texas Accelerated Research Therapeutics, and The Royal Marsden NHS Foundation Trust.

scholarly journals Targeting Post-Translational Modifications of the p73 Protein: A Promising Therapeutic Strategy for Tumors

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1916
Author(s):  
Ziad Omran ◽  
Mahmood H. Dalhat ◽  
Omeima Abdullah ◽  
Mohammed Kaleem ◽  
Salman Hosawi ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Protein A ◽  
P53 Gene ◽  
Cancer Therapies ◽  
Transactivation Domain ◽  
P53 Family ◽  
Post Translational Modifications ◽  
P53 Status ◽  
Apoptotic Effects ◽  
High Degree

The tumor suppressor p73 is a member of the p53 family and is expressed as different isoforms with opposing properties. The TAp73 isoforms act as tumor suppressors and have pro-apoptotic effects, whereas the ΔNp73 isoforms lack the N-terminus transactivation domain and behave as oncogenes. The TAp73 protein has a high degree of similarity with both p53 function and structure, and it induces the regulation of various genes involved in the cell cycle and apoptosis. Unlike those of the p53 gene, the mutations in the p73 gene are very rare in tumors. Cancer cells have developed several mechanisms to inhibit the activity and/or expression of p73, from the hypermethylation of its promoter to the modulation of the ratio between its pro- and anti-apoptotic isoforms. The p73 protein is also decorated by a panel of post-translational modifications, including phosphorylation, acetylation, ubiquitin proteasomal pathway modifications, and small ubiquitin-related modifier (SUMO)ylation, that regulate its transcriptional activity, subcellular localization, and stability. These modifications orchestrate the multiple anti-proliferative and pro-apoptotic functions of TAp73, thereby offering multiple promising candidates for targeted anti-cancer therapies. In this review, we summarize the current knowledge of the different pathways implicated in the regulation of TAp73 at the post-translational level. This review also highlights the growing importance of targeting the post-translational modifications of TAp73 as a promising antitumor strategy, regardless of p53 status.

scholarly journals Nonmonotonic Pathway Gene Expression Analysis Reveals Oncogenic Role of p27/Kip1 at Intermediate Dose

2017 ◽  
Vol 16 ◽  
pp. 117693511774013 ◽  
Author(s):  
Hien H Nguyen ◽  
Susan C Tilton ◽  
Christopher J Kemp ◽  
Mingzhou Song
Keyword(s):  
Gene Expression ◽  
Pathway Analysis ◽  
Dose Response ◽  
Response Analysis ◽  
Response Curves ◽  
Cancer Pathways ◽  
Pathway Gene ◽  
Mechanistic Basis ◽  
Functional Pathway ◽  
Squamous Cell Papilloma

The mechanistic basis by which the level of p27Kip1 expression influences tumor aggressiveness and patient mortality remains unclear. To elucidate the competing tumor-suppressing and oncogenic effects of p27Kip1 on gene expression in tumors, we analyzed the transcriptomes of squamous cell papilloma derived from Cdkn1b nullizygous, heterozygous, and wild-type mice. We developed a novel functional pathway analysis method capable of testing directional and nonmonotonic dose response. This analysis can reveal potential causal relationships that might have been missed by other nondirectional pathway analysis methods. Applying this method to capture dose-response curves in papilloma gene expression data, we show that several known cancer pathways are dominated by low-high-low gene expression responses to increasing p27 gene doses. The oncogene cyclin D1, whose expression is elevated at an intermediate p27 dose, is the most responsive gene shared by these cancer pathways. Therefore, intermediate levels of p27 may promote cellular processes favoring tumorigenesis—strikingly consistent with the dominance of heterozygous mutations in CDKN1B seen in human cancers. Our findings shed new light on regulatory mechanisms for both pro- and anti-tumorigenic roles of p27Kip1. Functional pathway dose-response analysis provides a unique opportunity to uncover nonmonotonic patterns in biological systems.

scholarly journals Dexamethasone administration attenuates the inhibitory effect of lipopolysaccharide on IGF-I and IGF-binding protein-3 in adult rats

2005 ◽  
Vol 185 (3) ◽  
pp. 467-476 ◽  
Author(s):  
Teresa Priego ◽  
Miriam Granado ◽  
Ana Isabel Martín ◽  
Asunción López-Calderón ◽  
María Angeles Villanúa
Keyword(s):  
Gene Expression ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Serum Concentrations ◽  
Gh Receptor ◽  
Its Gene ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

The aim of this study was to investigate whether glucocorticoid administration had a beneficial effect on serum concentrations of insulin-like growth factor I (IGF-I) and on IGF-binding protein 3 (IGFBP-3) in rats injected with lipopolysaccharide (LPS). Adult male rats were injected with LPS or saline and pretreated with dexamethasone or saline. Dexamethasone administration decreased growth hormone (GH) receptor and IGF-I mRNA levels in the liver of control rats. LPS decreased GH receptor and IGF-I gene expression in the liver of saline-treated rats but not in the liver of dexamethasone-pretreated rats. In the kidney, GH receptor mRNA levels were not modified by dexamethasone or LPS treatment. However, LPS decreased renal IGF-I gene expression and dexamethasone pretreatment prevented this decrease. Serum concentrations of IGF-I were decreased by LPS, and dexamethasone pretreatment attenuated this effect. The gene expression of IGFBP-3 in the liver and kidney and its circulating levels were decreased by LPS. In control rats dexamethasone increased circulating IGFBP-3 and its gene expression in the liver, and decreased the proteolysis of this protein. Dexamethasone pretreatment attenuated the LPS-induced decrease in IGFBP-3 gene expression in the liver and prevented the LPS-induced decrease in IGFBP-3 gene expression in the kidney. Moreover, dexamethasone pretreatment attenuated the LPS-induced decrease in serum concentrations of IGFBP-3 and decreased the LPS-induced IGFBP-3 proteolysis in serum. In conclusion, dexamethasone pretreatment partially attenuates the inhibitory effect of LPS on serum IGF-I by blocking the decrease of its gene expression in the kidney as well as by attenuating the decrease in serum concentrations of IGFBP-3.

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