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Project description:Precise dynamic control of activating H3K4me3 and repressive H3K27me3 histone modifications at bivalent gene promoters is essential for normal development and frequently corrupted in cancer. Using whole genome CRISPR/Cas9 screens we identify specific roles for MTF2-PRC2.1 and PCGF1-PRC1.1 polycomb complexes, and MLL1/2-COMPASS-like complex components in maintaining bivalency. Contrary to expectations, loss of Menin or inhibition of the Menin-MLL1/2 interaction, induces activation of bivalent genes via loss of polycomb-mediated repression and defines distinct roles for MLL1/2 and Menin in gene regulation. Whilst Menin and MLL1/2 contribute to maintenance H3K4me3 at active genes, a separate Menin-independent function of MLL1/2 opposes polycomb mediated repression at bivalent genes. MLL1/2 are essential for basal transcription and, although dispensable for transcription factor driven activation, facilitate transcriptional consistency during dynamic changes in gene expression. This functional partitioning of COMPASS complex components reveals therapeutic opportunities to target oncogenic and immunosuppressive functions of PRC2 through pharmacological inhibition of Menin.
2023-01-13 | GSE181818 | GEO
Project description:Precise control of activating H3K4me3 and repressive H3K27me3 histone modifications at bivalent promoters is essential for normal development and is frequently corrupted in cancer. By coupling a cell surface readout of bivalent MHC class I gene expression with whole genome CRISPR/Cas9 screens, we identify specific roles for MTF2-PRC2.1, PCGF1-PRC1.1 and Menin- KMT2A/B complexes in maintaining bivalency. Unexpectedly, genetic loss or pharmacological inhibition of Menin phenocopies the effects of polycomb disruption, resulting in derepression of bivalent genes in both cancer cells and pluripotent stem cells. Whilst Menin and KMT2A/B contribute to H3K4me3 at active genes, a separate Menin-independent function of KMT2A/B maintains H3K4me3 and opposes polycomb-mediated repression at bivalent genes. Release of KMT2A from active genes following Menin targeting alters the balance of polycomb and KMT2A at bivalent genes, facilitating gene activation. This functional partitioning of Menin-KMT2A/B complex components reveals novel therapeutic opportunities that can be leveraged through inhibition of Menin.
2023-01-13 | GSE222516 | GEO
Project description:Precise dynamic control of activating H3K4me3 and repressive H3K27me3 histone modifications at bivalent gene promoters is essential for normal development and frequently corrupted in cancer. Using whole genome CRISPR/Cas9 screens we identify specific roles for MTF2-PRC2.1 and PCGF1-PRC1.1 polycomb complexes, and MLL1/2-COMPASS-like complex components in maintaining bivalency. Contrary to expectations, loss of Menin or inhibition of the Menin-MLL1/2 interaction, induces activation of bivalent genes via loss of polycomb-mediated repression and defines distinct roles for MLL1/2 and Menin in gene regulation. Whilst Menin and MLL1/2 contribute to maintenance H3K4me3 at active genes, a separate Menin-independent function of MLL1/2 opposes polycomb mediated repression at bivalent genes. MLL1/2 are essential for basal transcription and, although dispensable for transcription factor driven activation, facilitate transcriptional consistency during dynamic changes in gene expression. This functional partitioning of COMPASS complex components reveals therapeutic opportunities to target oncogenic and immunosuppressive functions of PRC2 through pharmacological inhibition of Menin.
2023-01-13 | GSE181828 | GEO
Project description:Precise dynamic control of activating H3K4me3 and repressive H3K27me3 histone modifications at bivalent gene promoters is essential for normal development and frequently corrupted in cancer. Using whole genome CRISPR/Cas9 screens we identify specific roles for MTF2-PRC2.1 and PCGF1-PRC1.1 polycomb complexes, and MLL1/2-COMPASS-like complex components in maintaining bivalency. Contrary to expectations, loss of Menin or inhibition of the Menin-MLL1/2 interaction, induces activation of bivalent genes via loss of polycomb-mediated repression and defines distinct roles for MLL1/2 and Menin in gene regulation. Whilst Menin and MLL1/2 contribute to maintenance H3K4me3 at active genes, a separate Menin-independent function of MLL1/2 opposes polycomb mediated repression at bivalent genes. MLL1/2 are essential for basal transcription and, although dispensable for transcription factor driven activation, facilitate transcriptional consistency during dynamic changes in gene expression. This functional partitioning of COMPASS complex components reveals therapeutic opportunities to target oncogenic and immunosuppressive functions of PRC2 through pharmacological inhibition of Menin.
2023-01-13 | GSE181823 | GEO
Project description:The reported incidence of pancreatic neuroendocrine tumors (PanNETs) has increased, due in large part to improvements in detection and awareness. However, therapeutic options are limited and a critical need exists for understanding a more thorough characterization of the molecular pathology underlying this disease. The Men1 knockout mouse model recapitulates the early stage of human PanNET development and can serve as a foundation for the development of advanced mouse models that are necessary for preclinical testing. Menin, the product of the MEN1 gene, has been shown to physically interact with the KMT2A and KMT2B histone methyltransferases. Both the KMT2A and MEN1 genes are located on chromosome 11q, which frequently undergoes loss of heterozygosity (LOH) in PanNETs. We report herein that inactivation of Kmt2a in Men1-deficient mice accelerated pancreatic islet tumorigenesis and shortened the average life span. Increases in cell proliferation were observed in mouse pancreatic islet tumors upon inactivation of both Kmt2a and Men1. The Kmt2a/Men1 double knockout mouse model can be used as a mouse model to study advanced PanNETs.
| S-EPMC5199165 | biostudies-literature
Project description:The protein MENIN is the product of the multiple endocrine neoplasia type I (MEN1) gene. Altered MENIN expression is one of the few events that are clearly associated with foregut neuroendocrine tumours (NETs), classical oncogenes or tumour suppressors being not involved. One of the current challenges is to understand how alteration of MENIN expression contributes to the development of these tumours. We hypothesised that MENIN might regulate factors maintaining endocrine-differentiated functions. We chose the insulinoma model, a paradigmatic example of well-differentiated pancreatic NETs, to study whether MENIN interferes with the expression of v-MAF musculoaponeurotic fibrosarcoma oncogene homologue A (MAFA), a master glucose-dependent transcription factor in differentiated ?-cells. Immunohistochemical analysis of a series of human insulinomas revealed a correlated decrease in both MENIN and MAFA. Decreased MAFA expression resulting from targeted Men1 ablation was also consistently observed in mouse insulinomas. In vitro analyses using insulinoma cell lines showed that MENIN regulated MAFA protein and mRNA levels, and bound to Mafa promoter sequences. MENIN knockdown concomitantly decreased mRNA expression of both Mafa and ?-cell differentiation markers (Ins1/2, Gck, Slc2a2 and Pdx1) and, in parallel, increased the proliferation rate of tumours as measured by bromodeoxyuridine incorporation. Interestingly, MAFA knockdown alone also increased proliferation rate but did not affect the expression of candidate proliferation genes regulated by MENIN. Finally, MENIN variants with missense mutations detected in patients with MEN1 lost the WT MENIN properties to regulate MAFA. Together, our findings unveil a previously unsuspected MENIN/MAFA connection regarding control of the ?-cell differentiation/proliferation balance, which could contribute to tumorigenesis.
| S-EPMC3841063 | biostudies-literature
Project description:In colon tumors, the transcription of many genes becomes deregulated by poorly defined epigenetic mechanisms that have been studied mainly in established cell lines. In this study, we used frozen human colon tissues to analyze patterns of histone modification and DNA cytosine methylation in cancer and matched normal mucosa specimens. DNA methylation is strongly targeted to bivalent H3K4me3- and H3K27me3-associated promoters, which lose both histone marks and acquire DNA methylation. However, we found that loss of the Polycomb mark H3K27me3 from bivalent promoters was accompanied often by activation of genes associated with cancer progression, including numerous stem cell regulators, oncogenes, and proliferation-associated genes. Indeed, we found many of these same genes were also activated in patients with ulcerative colitis where chronic inflammation predisposes them to colon cancer. Based on our findings, we propose that a loss of Polycomb repression at bivalent genes combined with an ensuing selection for tumor-driving events plays a major role in cancer progression.
| S-EPMC4079738 | biostudies-literature
Project description:Menin functions as a critical oncogenic cofactor of mixed lineage leukemia (MLL) fusion proteins in the development of acute leukemias, and inhibition of the menin interaction with MLL fusion proteins represents a very promising strategy to reverse their oncogenic activity. MLL interacts with menin in a bivalent mode involving 2 N-terminal fragments of MLL. In the present study, we reveal the first high-resolution crystal structure of human menin in complex with a small-molecule inhibitor of the menin-MLL interaction, MI-2. The structure shows that the compound binds to the MLL pocket in menin and mimics the key interactions of MLL with menin. Based on the menin-MI-2 structure, we developed MI-2-2, a compound that binds to menin with low nanomolar affinity (K(d) = 22nM) and very effectively disrupts the bivalent protein-protein interaction between menin and MLL. MI-2-2 demonstrated specific and very pronounced activity in MLL leukemia cells, including inhibition of cell proliferation, down-regulation of Hoxa9 expression, and differentiation. Our results provide the rational and essential structural basis to design next generation of inhibitors for effective targeting of the menin-MLL interaction in leukemia and demonstrate a proof of concept that inhibition of complex multivalent protein-protein interactions can be achieved by a small-molecule inhibitor.
| S-EPMC3512226 | biostudies-literature
Project description:Melanoma is an aggressive cutaneous malignancy, illuminating the exact mechanisms and finding novel therapeutic targets are urgently needed. In this study, we identified KMT2A as a potential target, which promoted the growth of human melanoma cells. KMT2A knockdown significantly inhibited cell viability and cell migration and induced apoptosis, whereas KMT2A overexpression effectively promoted cell proliferation in various melanoma cell lines. Further study showed that KMT2A regulated melanoma cell growth by targeting the hTERT-dependent signal pathway. Knockdown of KMT2A markedly inhibited the promoter activity and expression of hTERT, and hTERT overexpression rescued the viability inhibition caused by KMT2A knockdown. Moreover, KMT2A knockdown suppressed tumorsphere formation and the expression of cancer stem cell markers, which was also reversed by hTERT overexpression. In addition, the results from a xenograft mouse model confirmed that KMT2A promoted melanoma growth via hTERT signaling. Finally, analyses of clinical samples demonstrated that the expression of KMT2A and hTERT were positively correlated in melanoma tumor tissues, and KMT2A high expression predicted poor prognosis in melanoma patients. Collectively, our results indicate that KMT2A promotes melanoma growth by activating the hTERT signaling, suggesting that the KMT2A/hTERT signaling pathway may be a potential therapeutic target for melanoma.
| S-EPMC5550845 | biostudies-other
Project description:Cervical cancer is an aggressive cutaneous malignancy, illuminating the molecular mechanisms of tumorigenesis and discovering novel therapeutic targets are urgently needed. KMT2A is a transcriptional co-activator regulating gene expression during early development and hematopoiesis, but the role of KMT2A in cervical cancer remains unknown. Here, we demonstrated that KMT2A regulated cervical cancer growth via targeting VADC1. Knockdown of KMT2A significantly suppressed cell proliferation and migration and induced apoptosis in cervical cancer cells, accompanying with activation of PARP/caspase pathway and inhibition of VADC1. Overexpression of VDAC1 reversed the KMT2A knockdown-mediated regulation of cell proliferation, migration and apoptosis. The in vivo results from a cervical cancer xenograft mouse model also validated that KMT2A knockdown suppressed tumor growth by inhibiting VDAC1, whereas KMT2A overexpression promoted cervical cancer growth. Moreover, analyses of Biewenga cervix database and clinical samples showed that both KMT2A and VDAC1 were upregulated in cervix squamous cell carcinoma compared with cervix uteri tissues, and their expression was negatively correlated with the differentiation grade of cervical cancer. Our results therefore indicated that the KMT2A/VDAC1 signaling axis may be a potential new mechanism of cervical carcinogenesis.
| S-EPMC7288919 | biostudies-literature