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Project description:Background/aimThe entire mechanisms by which epigenetic modifiers contribute to the development of pancreatic cancer remain unknown. Although the histone methyltransferase G9a is a promising target in human cancers, its role in pancreatic carcinogenesis has been under-studied. The aim of the study was to examine the role of G9a in pancreatic carcinogenesis by a gene-targeting mouse model.Materials and methodsWe established pancreas-specific G9aflox/flox mice and crossed them with Ptf1aCre/; KrasG12D/+ (KC) mice, which spontaneously develop pancreatic cancer. The phenotypes of the resulting KC mice with G9a deletion were examined. We analyzed transcriptomic data by microarray and genome-wide chromatin accessibility by transposase-accessible chromatin using sequencing. We established pancreatic organoids from KC mice.ResultsG9a deficiency impaired the progression of pancreatic intraepithelial neoplasia (PanIN) and prolonged the survival of KC mice. The number of phosphorylated Erk-positive cells and Dclk1-positive cells, which are reported to be essential for the progression of PanIN, were decreased by G9a deletion. UNC0638, an inhibitor of G9a, suppressed the growth of organoids and increased global chromatin accessibility, especially around the regions including the protein phosphatase 2A genes.ConclusionThus, our study suggested the functional interaction of G9a, Dclk1 and Mapk pathway in the Kras-driven pancreatic carcinogenesis. The inhibition of G9a may suppress the initiation of oncogenic Kras-driven pancreatic carcinogenesis.
| S-EPMC7675651 | biostudies-literature
Project description:Histone methyltransferase G9a governs the mutant Kras-driven pancreatic carcinogenesis
| PRJNA635814 | ENA
Project description:we reported a high-content drug screening platform of a series of pancreas organoids which contain common mutations found in human pancreatic cancer, wide type (WT), KC (KRASG12D), KPC (KRASG12D; Tp53R172H), KSC (KRASG12D; SMAD4-/-) and KPSC (KRASG12D; Tp53R172H and SMAD4-/-). Based on this platform, we screened about 6000 compounds and identified Perhexiline, which can inhibit the growth of pancreas organoids with KRAS mutation in vitro and in vivo. Single cell RNA-seq data shows that the cholesterol synthesis pathway is activated specifically caused by KRAS in mutated organoid lines. The key cholesterol synthesis regulator of SREBP2 and its downstream genes are activated in KRAS mutated organoids compared with WT. Interestingly, Perhexiline can reverse the metabolism changes in pancreas organoids with KRAS through downregulating SREBP2 at transcription level. Finally, we further validated targeting SREBP2 can attenuate tumor growth significantly with chemical inhibitor and genetic perturbation. These findings boost further understanding of KRAS in PDAC and provide a valuable resource for targeting KRAS therapeutics development.
2023-11-16 | GSE207352 | GEO
Project description:To investigate the transcriptomic effects of iASPP deletion or p53 mutation in the KRASG12D background Pdx1-Cre was used to delete iASPP in oncogenic KRASG12D expressing (KC) background to generate KC;iASPPΔ8/Δ8 mice. KC and KC;iASPPΔ8/Δ8 mice were then crossed with mice containing a p53R172H allele (equivalent to human p53 hotspot mutation R175H) to generate KPC and KPC;iASPPΔ8/Δ8 cohorts. Primary cell cultures were then derived from pancreatic ductal adenocarcinoma tissue for RNA-seq.
2023-07-06 | GSE226595 | GEO
Project description:Inflammatory transcription networks have been linked with the development of pancreatic ductal adenocarcinoma (PDAC). Here, we demonstrate that NFATc1 is both necessary and sufficient to drive progression of KrasG12D-initiated PDAC, particularly in the context of inflammation. Significantly, nuclear NFATc1 accelerates PDAC development in KrasG12D mice, whereas conditional NFATc1 deletion or pharmacological inhibition attenuates inflammation-mediated carcinogenesis. Mechanistically, NFATc1 induces STAT3 expression, complex formation and signal integration in PDAC. Genome-wide ChIP-sequencing and expression analysis in cells derived from c.n.NFATc1;KrasG12D mice identified combinatorial NFATc1/STAT3 binding at chromatin enhancer sites and subsequent regulation of key molecules involved in oncogenic signaling, growth and inflammation. Together, this study supports the relevance of inflammatory transcription factor networks in pancreatic carcinogenesis and provides a theoretical platform for therapeutic targeting of NFATc1 nucleoprotein complexes in PDAC. NFATc1 ChIP followed by high throughput sequencing in primary murine pancreatic cancer cells (referred to as NKC cells) derived from transgenic mice with pancreas-specific constitutive activation of NFATc1 and KrasG12D mutation in the presence or absence of STAT3 shRNA; 2 ChIP samples (scramble DNA and shSTAT3 DNA) and 1 unenriched input control from the same chromatin pool.
2014-06-30 | E-GEOD-39969 | biostudies-arrayexpress
Project description:Hepatocellular carcinoma (HCC) is the third deadliest and sixth most common cancer in the world. Histone-lysine N-methyltransferase EHMT2 (also known as G9a) is a histone methyltransferase frequently overexpressed in many cancer types, including HCC. We showed that Myc-driven liver tumours have a unique H3K9 methylation pattern with corresponding G9a overexpression. This phenomenon of increased G9a was further observed in our c-Myc-positive HCC patient-derived xenografts. More importantly, we showed that HCC patients with higher c-Myc and G9a expression levels portend a poorer survival with lower median survival months. We demonstrated that c-Myc interacts with G9a in HCC and cooperates to regulate c-Myc-dependent gene repression. In addition, G9a stabilises c-Myc to promote cancer development, contributing to the growth and invasive capacity in HCC. Furthermore, combination therapy between G9a and synthetic-lethal target of c-Myc, CDK9, demonstrates strong efficacy in patient-derived avatars of Myc-driven HCC. Our work suggests that targeting G9a could prove to be a potential therapeutic avenue for Myc-driven liver cancer. This will increase our understanding of the underlying epigenetic mechanisms of aggressive tumour initiation and lead to improved therapeutic and diagnostic options for Myc-driven hepatic tumours.
| S-EPMC10620125 | biostudies-literature
Project description:Tumor suppression that is mediated by oncogene-induced senescence (OIS) is considered to function as a safeguard during development of pancreatic ductal adenocarcinoma (PDAC). However, the mechanisms that regulate OIS in PDAC are poorly understood. Here, we have determined that nuclear RelA reinforces OIS to inhibit carcinogenesis in the Kras mouse model of PDAC. Inactivation of RelA accelerated pancreatic lesion formation in Kras mice by abrogating the senescence-associated secretory phenotype (SASP) gene transcription signature. Using genetic and pharmacological tools, we determined that RelA activation promotes OIS via elevation of the SASP factor CXCL1 (also known as KC), which activates CXCR2, during pancreatic carcinogenesis. In Kras mice, pancreas-specific inactivation of CXCR2 prevented OIS and was correlated with increased tumor proliferation and decreased survival. Moreover, reductions in CXCR2 levels were associated with advanced neoplastic lesions in tissue from human pancreatic specimens. Genetically disabling OIS in Kras mice caused RelA to promote tumor proliferation, suggesting a dual role for RelA signaling in pancreatic carcinogenesis. Taken together, our data suggest a pivotal role for RelA in regulating OIS in preneoplastic lesions and implicate the RelA/CXCL1/CXCR2 axis as an essential mechanism of tumor surveillance in PDAC.
| S-EPMC4966329 | biostudies-literature
Project description:Macroautophagy is an evolutionarily conserved cellular process involved in the clearance of proteins and organelles. Although the cytoplasmic machinery that orchestrates autophagy induction during starvation, hypoxia, or receptor stimulation has been widely studied, the key epigenetic events that initiate and maintain the autophagy process remain unknown. Here we show that the methyltransferase G9a coordinates the transcriptional activation of key regulators of autophagosome formation by remodeling the chromatin landscape. Pharmacological inhibition or RNA interference (RNAi)-mediated suppression of G9a induces LC3B expression and lipidation that is dependent on RNA synthesis, protein translation, and the methyltransferase activity of G9a. Under normal conditions, G9a associates with the LC3B, WIPI1, and DOR gene promoters, epigenetically repressing them. However, G9a and G9a-repressive histone marks are removed during starvation and receptor-stimulated activation of naive T cells, two physiological inducers of macroautophagy. Moreover, we show that the c-Jun N-terminal kinase (JNK) pathway is involved in the regulation of autophagy gene expression during naive-T-cell activation. Together, these findings reveal that G9a directly represses genes known to participate in the autophagic process and that inhibition of G9a-mediated epigenetic repression represents an important regulatory mechanism during autophagy.
| S-EPMC3811684 | biostudies-literature
Project description:The discovery of Suv39h1, the first SET domain-containing histone lysine methyltransferase (HKMT), was reported in 2000. Since then, research on histone methylation has progressed rapidly. Among the identified HKMTs in mammals, G9a and GLP are the primary enzymes for mono- and dimethylation at Lys 9 of histone H3 (H3K9me1 and H3K9me2), and exist predominantly as a G9a-GLP heteromeric complex that appears to be a functional H3K9 methyltransferase in vivo. Recently, many important studies have reported that G9a and GLP play critical roles in various biological processes. The physiological relevance of G9a/GLP-mediated epigenetic gene regulation is discussed.
| S-EPMC3078703 | biostudies-literature
Project description:DNA CpG methylation and histone H3 lysine 9 (H3K9) methylation are two major repressive epigenetic modifications, and these methylations are positively correlated with one another in chromatin. Here we show that G9a or G9a-like protein (GLP) dimethylate the amino-terminal lysine 44 (K44) of mouse Dnmt3a (equivalent to K47 of human DNMT3A) in vitro and in cells overexpressing G9a or GLP. The chromodomain of MPP8 recognizes the dimethylated Dnmt3aK44me2. MPP8 also interacts with self-methylated GLP in a methylation-dependent manner. The MPP8 chromodomain forms a dimer in solution and in crystals, suggesting that a dimeric MPP8 molecule could bridge the methylated Dnmt3a and GLP, resulting in a silencing complex of Dnmt3a-MPP8-GLP/G9a on chromatin templates. Together, these findings provide a molecular explanation, at least in part, for the co-occurrence of DNA methylation and H3K9 methylation in chromatin.
| S-EPMC3286832 | biostudies-literature