Project description:To explore the target genes of Men1 and Kmt2a in lung of mice, we isolated the lung tissues from WT and Men1 knockout and Kmt2a mouse and performed gene expression profiling analysis by RNA-seq.
Project description:In this study, we used a targeted CRISPR/Cas9 screen to identify genes that determine growth of A549 cells in vivo and in vitro. Functional genomic screens in 2D cell culture are of limited use for identifying therapeutic targets that modulate tumor cell-microenvironment cell interactions. By comparing targeted CRISPR-Cas9 screens in 2D culture of A549 lung cancer cells versus xenografts derived from the same cell line, we identified MEN1 as the top hit that confers differential effects in vitro and in vivo. Knockout of MEN1 in multiple solid cancer types does not impact cell proliferation in vitro, but significantly promotes or inhibits tumor growth in immunodeficient or immunocompetent mice, respectively. Mechanistically, knockout of MEN1 leads to increased chromatin interaction of its interaction partner MLL1 (KMT2A), a histone methyltransferase, to repetitive genomic regions, where it activates expression of double-stranded RNA. This results in MARV and cGAS-STING dependent activation of viral mimicry response, which induces infiltration of neutrophils and CD8+ T cells in immunodeficient and immunocompetent mice respectively. Consistently, multiple immune cell infiltrations are negatively correlated with MEN1 abundance and positively correlated with that of MLL1 in patient tumors of a broad range of cancer types. Pharmacological inhibition of MEN1-MLL interaction reduces tumor growth in CD8+ T cell dependent manner, with enhanced activity in combination with anti-PD-1 treatment. These findings reveal tumor microenvironment dependent oncogenic and tumor suppressive functions of MEN1 and provide rationale for therapeutic targeting of MEN1 alone or in combination with immunotherapy in multiple solid cancer types.
Project description:Functional genomic screen in 2D cell culture is limited in identifying therapeutic targets that modulates tumor-microenvironment interaction. Through comparison of targeted CRISPR-Cas9 screens in 2D cell culture and cell line derived xenografts of lung cancer A549, we identified MEN1 as the top hit that confers differential essentialities in vitro and in vivo. Knockout of MEN1 in multiple solid cancer types does not impact cell proliferation in vitro, but significantly promotes and inhibits tumor growth in immunodeficient and immunocompetent mice, respectively. Mechanistically, knockout of MEN1 leads to redistribution of its interaction partner MLL1, a histone methyltransferase, to repetitive genomic regions that produce double stranded RNA. This resulted in MARV and cGAS-STING dependent activation of viral mimicry response, which induces tumor promoting neutrophil and tumor suppressing CD8+ T cell infiltrations in immunodeficient and immunocompetent mice, respectively. Consistently, multiple immune cell infiltrations are negatively correlated with MEN1 abundance and positively correlated with that of MLL1 in patient tumors of a broad range of cancer types. Pharmacological inhibition of MEN1-MLL1 interaction reduces tumor growth in CD8+ T cell dependent manner, and synergizes with anti-PD-L1 treatment. These findings reveal tumor microenvironment dependent oncogenic and tumor suppressive function of MEN1 and provide rationale for therapeutic targeting of MEN1 alone or in combination with immunotherapy in multiple solid cancer types.
Project description:Menin inhibitors have entered clinical trials for KMT2A-rearranged and NPM1 mutant acute leukemias and are demonstrating promising activity. CRISPR-Cas9 base editor screening previously predicted several MEN1 mutations that have arisen in patients receiving SNDX-5613 and confer menin inhibitor resistance. The extent to which MEN1 mutations will impact each menin inhibitor is currently unknown. We leveraged advances in CRISPR-Cas9 base editing technology to predict the MEN1 mutation profile that will impact five different menin inhibitors in clinical trials. We found key similarities (M327) and differences (C334, E368, V372) in the profile of MEN1 mutations that affect each compound. The co-crystal structure of menin bound to each compound suggests resistance mechanisms related to how each menin inhibitor binds in the KMT2A binding pocket of menin. Our in vitro and in vivo validation suggests that the MEN1 mutations identified and validated with this approach are likely to arise and impact all menin inhibitors.
Project description:Menin inhibitors have entered clinical trials for KMT2A-rearranged and NPM1 mutant acute leukemias and are demonstrating promising activity. CRISPR-Cas9 base editor screening previously predicted several MEN1 mutations that have arisen in patients receiving SNDX-5613 and confer menin inhibitor resistance. The extent to which MEN1 mutations will impact each menin inhibitor is currently unknown. We leveraged advances in CRISPR-Cas9 base editing technology to predict the MEN1 mutation profile that will impact five different menin inhibitors in clinical trials. We found key similarities (M327) and differences (C334, E368, V372) in the profile of MEN1 mutations that affect each compound. The co-crystal structure of menin bound to each compound suggests resistance mechanisms related to how each menin inhibitor binds in the KMT2A binding pocket of menin. Our in vitro and in vivo validation suggests that the MEN1 mutations identified and validated with this approach are likely to arise and impact all menin inhibitors.
Project description:To explore the target genes of Men1 in macrophage, we isolated the peritoneal cavity macrophage from WT and Men1 knockout mouse and performed gene expression profiling analysis by RNA-seq.
Project description:Multiple endocrine neoplasia type 1 (MEN1) syndrome is the result of mutations in the MEN1 gene and results in tumor formation via mechanisms that are not well understood. Using a novel genome-wide methylation analysis, we studied tissues from patients with MEN1-parathyroid tumors, tissues from Men1 knockout (KO) mouse models, and mouse Men1 null mouse embryonic fibroblast (MEF) cell lines. Tissues from KO mice were used to confirm and assess the findings from the MEN1 clinical samples and further explore the molecular mechanisms of global epigenetic changes following the inactivation of menin. We demonstrated that the inactivation of menin results in enhanced activity of DNA (cytosine-5)-methyltransferase 1 (DNMT1) by retinoblastoma-binding protein 5 (Rbbp5) activation in MEN1 tumor tissues. The increased activity of DNMT1 mediated global DNA hypermethylation, which in turn resulted in aberrant activation of the Wnt/β-catenin signaling pathway through inactivation of Sox regulatory genes. Our study provides important insights into the possible regulatory role of menin in DNA methylation and its impact on the pathogenesis of MEN1 tumor development. Global DNA methylation in tissues from patients with MEN1-parathyroid tumors. Thirty-eight human parathyroid specimens were used: 13 sporadic (non-MEN1) parathyroid adenomas, 12 MEN1-parathyroid tumors, 4 parathyroid carcinomas, and 9 normal parathyroids.
Project description:Loss-of-function mutations of the multiple endocrine neoplasia type 1 (MEN1) gene are causal to the MEN1 tumor syndrome, but they are also commonly found in sporadic pancreatic neuroendocrine tumors and other types of cancers. The MEN1 gene product, menin, is involved in transcriptional and chromatin regulation, most prominently as an integral component of KMT2A/MLL1 and KMT2B/MLL2 containing COMPASS-like histone H3K4 methyltransferase complexes. In a mutually exclusive fashion, menin also interacts with the JunD subunit of the AP-1 and ATF/CREB transcription factors. After in silico screening of 253 disease-related MEN1 missense mutations, we selected a set of nine menin mutations in surface-exposed residues. The protein interactomes of these mutants were assessed by quantitative mass spectrometry, which indicated that seven of the nine mutants disrupt interactions with both MLL1/2 and JunD complexes in the nucleus. We identified three missense mutations, R52G, E255K and E359K, which display predominant reduction in interaction with MLL1 compared to JunD. This observation was supported by a pronounced loss of binding of the R52G, E255K and E359K mutant proteins at unique MLL1 genomic binding sites with less effect on unique JunD sites. These findings support the general importance of the menin-MLL1 and menin-JunD interactions in MEN1 gene-associated pathogenic conditions.
Project description:Pharmacologic targeting of epigenetic protein complexes has shown significant in vitro responses in acute myeloid leukemia (AML). Early clinical trials in KMT2A-rearranged leukemia indicate rather transient responses and development of resistance. In an effort to define functional dependencies of KMT2A-fusions in AML, we identify the catalytic immunoproteasome subunit PSMB8 as a KMT2A-complex-specific vulnerability. Genetic and pharmacologic inactivation of PSMB8 results in impaired proliferation of murine and human leukemic cells while normal hematopoietic cells remain unaffected. Disruption of immunoproteasome function results in cellular enrichment of transcription factor BASP1, and consecutive repression of KMT2A-target genes. Pharmacologic targeting of PSMB8 improves efficacy of Menin-inhibitors, eradicates leukemia in primary human xenografts and shows preserved activity against Menin-inhibitor resistance mutations. This identifies and validates a cell-intrinsic mechanism whereby selective disruption of proteostasis results in altered transcription factor abundance and repression of oncogene-specific transcriptional networks. Therapeutic targeting of PSMB8-dependent transcription in combination with Menin-inhibition could thus eradicate KMT2A-complex driven AML.