Histone-lysine N-methyltransferase 2D Research Articles

Histone-Lysine N-Methyltransferase 2D (KMT2D) Impending Therapeutic Target for the Management of Cancer: The Giant Rats Tail.

The histone-lysine N-methyltransferase 2D (KMT2D), tumor suppressor gene which is the major component of histone H3K4 mono-methyltransferase in mammals and has significant role in regulation of a gene which are frequently mutated that lead to many different types of cancers that include non-Hodgkin lymphoma, medulloblastoma, prostate carcinoma, renal carcinoma, bladder carcinoma and lung carcinoma. KMT2D gene epigenetic alterations in histone methylation play a significant role for the initiation and progression of cancers from pre-cancerous lesions, yet its complete function in oncogenesis remains unsolved. KMT2D deficiency - loss are thought of initial mediators of cancer development and cell migration such as B-cell lymphoma, medulloblastoma, melanoma, pancreas and lung cancer. The KMT2D loss has know to activate glycolytic genes that promote aggressive tumor progression. Therefore, the present review serves to underline the update on recent research pertaining to KMT2D gene, that could be a potential therapeutic target in downregulating glycolytic genes such as Pgk1, Ldha, Pgam1 and Gapdh; 2, epidermal growth factor receptor tyrosine kinase (EGFR-TK ) - ERBB2, RTK-RAS signaling, RAS activator genes Rgl1, Rasgrp1, Rasgrf1, Rasgrf 2 and Rapgef5 in suppressing the tumor progression that may represent novel targeted therapy for the management of cancer. This review will facilitate to understand the gene expression that inhibits cancer progression and which could serve as a potential molecular target in understanding cancer pathogenesis.

M2 Macrophage-Derived Exosomal circ_0088494 Inhibits Ferroptosis via Promoting H3K4me1 Modification of STEAP3 in Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) is a common type of cutaneous cancer globally. M2 macrophage-derived exosomes (M2 exosomes) facilitate the development of cancer. Ferroptosis, a newly uncovered form of cell death, is linked to cancer progression. The present research planned to study the function and potential mechanism of M2 exosomes on ferroptosis in cSCC. Patients with cSCC were recruited to gather adjacent noncancerous specimens and cSCC tissues. Mononuclear macrophage (THP-1) cells were differentiated into M2 macrophages before exosome extraction, and then the exosomes were added into cSCC cells (A431 and SCL-1). Erastin was applied to induce ferroptosis. Cell viability, mitochondrial superoxide, lipid-ROS, malondialdehyde (MDA), and iron level were detected to validate ferroptosis in cSCC cells. Proteins and RNAs were tested by applying western blot and RT-qPCR. The combination between molecules was validated by ChIP and RIP. Six-transmembrane epithelial antigen of the prostate 3 (STEAP3) was elevated in cSCC specimens, which correlated to reduced ferroptosis. cSCC tissues presented an increase in the number of M2 macrophages. Erastin-elicited ferroptosis was repressed by M2 macrophages, while exosome inhibitor GW4869 neutralized the outcome of M2 macrophages. Furthermore, M2 exosomes repressed ferroptosis of cSCC cells via circ_0088494, which might be related to the upregulation of STEAP3. M2 exosomes-derived circ_0088494 promoted histone 3 lysine 4 monomethylation (H3K4me1) modification of STEAP3 by recruiting histone-lysine N-methyltransferase 2D (KMT2D). The effect of circ_0088494-silenced M2 exosomes on ferroptosis was antagonized by STEAP3 overexpression. M2 exosomes-derived circ_0088494 recruited KMT2D to promote H3K4me1 modification of STEAP3, thereby inhibiting ferroptosis in cSCC. This study might provide a novel target for cSCC treatment.

Abstract PR07: SETD1B mutations confer apoptosis resistance and BCL2 independence in B-cell lymphoma

Abstract The translocation t(14;18) activates BCL2 and is considered the initiating genetic lesion in over ninety percent of follicular lymphomas (FL). Surprisingly, FL patients respond poorly to clinically approved inhibitor, venetoclax. The mechanisms underlying BCL2 independence in FL are poorly understood, and it has been speculated that epigenetic rewiring of cell death programs may play a role. We performed separate genome-wide CRISPR/Cas9 screens to explore the mechanisms of resistance to Venetoclax and an experimental MCL-1 inhibitor (S63845) and unveiled the histone lysine methyltransferase SETD1B (KMT2G) as an unexpected mechanism of resistance to both inhibitors in lymphoma. We show that mutations and deletions affecting SETD1B occur in 7% of FLs and 16% of diffuse large B cell lymphomas (DLBCL). In vivo, SETD1B acts as a tumor suppressor gene and cooperates with the related histone-lysine N-methyltransferase 2D (KMT2D) gene leading to a more aggressive disease presentation. This oncogenic cooperation is reflected in the genomes of human lymphoma, where SETD1B mutations typically co-occur with KMT2D mutations. Mechanistically, SETD1B is required to express pro-apoptotic BCL2 family proteins like BIM and BIK. Inhibitors of the KDM5 histone H3K4 de-methylase restore the expression of BIM and BIK, venetoclax sensitivity and lead to synergistic drug effects in SETD1B deficient lymphoma xenografts. Our results highlight a role for SETD1B in the epigenetic regulation of cell death proteins in B cell lymphomas, connecting the loss of SETD1B to lymphoma development and reduced sensitivity to venetoclax. Citation Format: Ana Portelinha, Shenqiu Wang, Sara Parsa, Man Jiang, Sagarajit Mohanty, Soumya Sharma, Neeraj Arya, Omid Tavana, Jiayu Wen, Jude Fitzgibbon, Ahmet Dogan, Ana Younes, Ari M. Melnick, Hans-Guido Wendel. SETD1B mutations confer apoptosis resistance and BCL2 independence in B-cell lymphoma [abstract]. In: Proceedings of the Fourth AACR International Meeting on Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2024 Jun 19-22; Philadelphia, PA. Philadelphia (PA): AACR; Blood Cancer Discov 2024;5(3_Suppl):Abstract nr PR07.

Somatic KMT2D loss-of-function mutations in lung squamous cell carcinoma: a single-center cohort study.

The significant progress has been made in targeted therapy for lung adenocarcinoma (LUAD) in the past decade. Only few targeted therapeutics have yet been approved for the treatment of lung squamous cell carcinoma (LUSC). Several higher frequency of gene alterations are identified as potentially actionable in LUSC. Our work aimed to explore the complex interplay of multiple genetic alterations and pathways contributing to the pathogenesis of LUSC, with a very low frequency of a single driver molecular alterations to develop more effective therapeutic strategies in the future. We retrospectively analyzed the targeted next-generation sequencing (NGS) data (approximately 600 genes) of 335 patients initially diagnosed with non-small cell lung cancer (NSCLC) at our institution between January 2019 and March 2023 and explored the somatic genome alteration difference between LUSC and LUAD. We analyzed that the presence of loss-of-function (LoF) mutations (nonsense, frameshift, and splice-site variants) in histone-lysine N-methyltransferase 2D (KMT2D) was much more prevalent in LUSC (11/53, 20.8%) than in LUAD (6/282, 2.1%). Moreover, our data indicated TP53 co-mutated with KMT2D LoF in 90.9% (10/11) LUSC and 33.3% (2/6) LUAD. Notably, the mutation allele fraction (MAF) of KMT2D was very similar to that of TP53 in the co-mutated cases. Genomic profiling of driver gene mutations of NSCLC showed that 81.8% (9/11) of the patients with LUSC with KMT2D LoF mutations had PIK3CA amplification and/or FGFR1 amplification. Our results prompted that somatic LoF mutations of KMT2D occur frequently in LUSC, but are less frequent in LUAD and therefore may potentially contribute to the pathogenesis of LUSC. Concurrent TP53 mutations, FGFR1 amplification, and PIK3CA amplification are very common in LUSC cases with KMT2D LoF mutations. It needs more deeper investigation on the interplay of the genes and pathways and uses larger cohorts in the future.

EBF2 Links KMT2D-Mediated H3K4me1 to Suppress Pancreatic Cancer Progression via Upregulating KLLN.

Mono-methylation of histone H3 on Lys 4 (H3K4me1), which is catalyzed by histone-lysine N-methyltransferase 2D (KMT2D), serves as an important epigenetic regulator in transcriptional control. In this study, the authors identify early B-cell factor 2 (EBF2) as a binding protein of H3K4me1. Combining analyses of RNA-seq and ChIP-seq data, the authorsfurther identify killin (KLLN) as a transcriptional target of KMT2D and EBF2 in pancreatic ductal adenocarcinoma (PDAC) cells. KMT2D-dependent H3K4me1 and EBF2 are predominantly over-lapped proximal to the transcription start site (TSS) of KLLN gene. Comprehensive functional assays show that KMT2D and EBF2 cooperatively inhibit PDAC cells proliferation, migration, and invasion through upregulating KLLN. Such inhibition on PDAC progression is also achieved through increasing H3K4me1 level by GSK-LSD1, a selective inhibitor of lysine-specific demethylase 1 (LSD1). Taken together, these findings reveal a new mechanism underlying PDAC progression and provide potential therapeutic targets for PDAC treatment.

Histone methyltransferase KMT2D mediated lipid metabolism via peroxisome proliferator-activated receptor gamma in prostate cancer.

BackgroundProstate cancer (PCa) is the most common type of cancer in men. Destruction of or blocking lipid metabolism impairs the growth, proliferation, and survival of tumor cells. Recent studies on hepatic steatosis suggest that kinase tethers histone-lysine N-methyltransferase 2D (KMT2D) to peroxisome proliferator-activated receptor gamma (PPARγ), transactivating its target genes. Here, to determine a therapeutic approach that may interfere with PCa lipid metabolism, the interaction mechanism of KMT2D and PPARγ was verified in PCa.MethodsMolecular techniques and bioinformatics analysis were used to explore the relationship between KMT2D and lipid metabolism pathways in PCa. Moreover, the changes of lipid droplets were detected by oil red O staining and BODIPY staining. Molecular techniques were used to investigate the effect of KMT2D on PPARγ signaling in PCa cells. Co-immunoprecipitation (Co-IP) and DNA pull-down verified the mechanism of interaction between KMT2D and PPARγ.ResultsKMT2D knockdown reduced the lipid droplet content in PC-3 and DU-145 cells and downregulated the expression of lipid metabolic genes. Low-dose rosiglitazone (ROSI) effectively activated the PPARγ pathway to promote lipid droplet synthesis and cell proliferation and migration. However, ROSI could not function effectively after KMT2D knockdown. Both co-IP and DNA pull-down analyses showed that KMT2D and PPARγ could be tethered to regulate the expression of PPARγ target genes.ConclusionsIn PCa, KMT2D interacted with PPARγ, which directly participated in the regulation of lipid metabolism-related genes and affected lipid synthesis. Therefore, inhibiting the interaction between KMT2D and PPARγ is a potential therapeutic strategy.

Tracking the evolution of untreated high-intermediate/high-risk diffuse large B-cell lymphoma by circulating tumour DNA.

Diffuse large B-cell lymphoma (DLBCL) is a highly heterogenous malignancy, early identification of patients for relapse remains challenging. The potential to non-invasively monitor tumour evolutionary dynamics of DLBCL needs to be further established. In the present study, 17 tumour biopsy and 38 plasma samples from 38 patients with high-intermediate/high-risk DLBCL were evaluated at baseline. Longitudinal blood samples were also collected during therapy. Circulating tumour DNA (ctDNA) was analysed using targeted sequencing based on a gene panel via a recently developed methodology, circulating single-molecule amplification and re-sequencing technology (cSMART). We found that the most frequently mutated genes were tumour protein p53 (TP53; 42·1%), histone-lysine N-methyltransferase 2D (KMT2D; 28·9%), caspase recruitment domain family member 11 (CARD11; 21·1%), cAMP response element-binding protein binding protein (CREBBP; 15·8%), β2 -microglobulin (B2M; 15·8%), and tumour necrosis factor alpha-induced protein 3 (TNFAIP3; 15·8%). The mutation profiles between ctDNA and matched tumour tissue showed good concordance; however, more mutation sites were detected in ctDNA samples. Either TP53 or B2M mutations before treatment predicted poor prognosis. Analysis of dynamic blood samples confirmed the utility of ctDNA for the real-time assessment of treatment response and revealed that the increases in ctDNA levels and changes in KMT2D mutation status could be useful predictors of disease progression. Our present results suggest that ctDNA is a promising method for the detection of mutation spectrum and serves as a biomarker for disease monitoring and predicting clinical recurrence.

Histone Methyltransferase KMT2D Regulates H3K4 Methylation and is Involved in the Pathogenesis of Ovarian Cancer

To investigate the function of histone-lysine N-methyltransferase 2D (KMT2D) on the methylation of H3 lysine 4 (H3K4) in the progression of Ovarian cancer (OV). KMT2D, ESR1 and H3K4me expressions in surgical resected tumors and tumor adjacent tissues of OV from 198 patients were determined using immunohistochemistry (IHC). Human OV cell lines including SKOV3, HO-8910 cells and normal ovarian epithelial cell line IOSE80 were employed for in vitro experiment, and BALB/C female nude mice were used for in vivo study. qRT-PCR and Western blotting were implemented for measuring the KMT2D, ESR1, PTGS2, STAT3, VEGFR2, H3K4me and ELF3 levels. Chromatin immunoprecipitation (ChIP) analysis was used for studying the binding between ESR1 and H3K4me. Edu staining assay was executed to determine cell viability, and colony formation and cell invasion assay. The immunofluorescence method was utilized for the visualization of protein expression and distribution in cells. In this study, KMT2D, ESR1 and H3K4me were found upregulated in OV progression. Mutated H3K4me could inhibit the proliferation, colony formation and invasion ability of OV cells. Mutated H3K4me could also hinder the ESR1 in SKOV3 expressions and HO-8910 cells, which would further mediate PTGS2/STAT3/VEGF pathway. In vivo studies also demonstrated that mutated H3K4me inhibited OV progression via targeting ESR1. All the ChIP-PCR analysis indicated the moderator effect of H3K4me on ESR1. Our findings indicated that ESR1 played an important role in the OV progression. Besides, H3K4me could promote cell proliferation and inhibit apoptosis of OV cells. Meanwhile, it could also targets the ESR1 production to enhance the migration and invasion of OV cells, which was through the activation of ESR1-ELF3-PTGS2-STAT3-VEGF cascade signaling pathway.

M256 UNMASKING KABUKI SYNDROME: A 7-YEAR-OLD GIRL WITH RECURRENT OTITIS MEDIA, HYPOGAMMAGLOBULINEMIA AND AUTOIMMUNE CYTOPENIAS

Kabuki syndrome (KS) is a rare disorder characterized by distinct facial features, growth deficiency, intellectual disability, skeletal and visceral abnormalities and immune dysregulation. It is caused by pathogenic variants in two known genes, KMT2D (histone-lysine N-methyltransferase 2D) and KDM6A (lysine-specific demethylase 6A).

Small molecule inhibitors of the prostate cancer target KMT2D

Histone lysine N-methyltransferase 2D (KMT2D), an important methyltransferase that is involved in the methylation of lysine 4 in histone H3 (H3K4) and related to the development of prostate cancer. Hypermethylation of H3K4 is shown in prostate cancer (PCa). However, KMT2D inhibitors have not yet been developed. This article aims to design small molecule inhibitors targeting KMT2D_SET to prevent PCa cell proliferation and migration. Twenty-four inhibitors were firstly designed according to a virtual screening of computers，and shown different degrees of binding to KMT2D_SET. Compounds 1 and 16 showed high binding affinities to KMT2D, with KD values of 147 ± 32.9 μM and 176 ± 37.9 μM, respectively. In addition, they exerted strong inhibitory activity against the PCa cell lines PC-3 and DU145, with IC50 values of 1.1 ± 0.06 μM, 1.5 ± 0.06 μM and 1.8 ± 0.1 μM, 2.3 ± 0.2 μM, respectively. Furthermore, these two compounds significantly suppressed the migration of PCa cells.

Abstract 1859: Elucidating the role of KMT2D as a novel therapeutic target for resistant HER2+ breast cancer

Abstract HER2 targeted agents have improved clinical outcomes for women with HER2+ breast cancer. However, drug resistance remains a critical challenge for curing HER2+ disease. Cancer stem cells (CSCs)-enriched during anti-HER2 therapy promote resistance and recurrence. Therefore, novel targets that drive survival of CSCs are needed. Recently, the histone-lysine N-methyltransferase 2D (KMT2D) has been shown to be a prognostic marker for poor recurrence free survival in women with HER2+ breast cancer. Preliminary data showed that KMT2D RNA was increased in HER2+ CSC-enriched mammospheres compared to bulk cells. Further, KMT2D protein is increased in resistant compared to sensitive cells. These data suggest that KMT2D is necessary for survival of CSCs and resistance to anti-HER2 therapy. To address this hypothesis, RNAi-mediated knockdown of KMT2D was performed in trastuzumab sensitive and resistant cells. KMT2D depletion in sensitive cells resulted in almost complete blockade of proliferation in 2-D culture and CSC survival in 3-D culture. In contrast, proliferation and CSC survival was only moderately inhibited by KMT2D depletion in resistant cells. ChIP studies confirmed that KMT2D is enriched on the MYC enhancer in sensitive cells but only moderately in resistant cells. Based on these data, KMT2D is necessary for growth of HER2+ breast cancer and is possibly inactivated during acquisition of resistance. To determine the mechanism, RNA sequencing was performed in both sensitive and resistance cells expressing or depleted for KMT2D. Several differentially expressed genes that were positively or negatively regulated by KMT2D were identified. Specifically, transcript levels of ITGB6 and CLIC3 were decreased upon KMT2D knockdown, while PGR and AR transcripts were increased. Initial results showed that ITGB6 depletion resulted in decreased bulk cell proliferation and survival of CSCs similar to KMT2D knockdown. These results suggest that ITGB6 could be a direct target gene of KMT2D and thus mediates the phenotypic effects of KMT2D. Overall, our results suggest that KMT2D is necessary for both proliferation and CSC survival in HER2+ breast cancer sensitive to anti-HER2 therapy and a combination approach of targeting both HER2 and KMT2D could prevent enrichment of CSCs and acquired resistance. Citation Format: EMILY MA, Andrei Zlobin, Debra Wyatt, Jeffrey Ng, Andrew Dingwall, Clodia Osipo. Elucidating the role of KMT2D as a novel therapeutic target for resistant HER2+ breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1859.

TMOD-03. SOMATIC MUTATIONS OF CHROMATIN REGULATOR Kmt2d IN CEREBELLAR PRECURSORS INFLUENCES SHH-MEDULLOBLASTOMA TUMORIGENESIS

Abstract Medulloblastoma (MB), the most common malignant pediatric brain tumor, is a classic example of dysregulation of developmental pathways leading to tumorogenesis. Despite advancements in multi-modal therapies, most patients suffer from long-term neurocognitive and neuroendocrine disabilities. The Sonic Hedgehog subgroup of MB (SHH-MB) accounts for ~30% of all cases and originates from ATOH1+ cerebellar granule cell precursors (GCPs). Experimental data in mice has shown that activating mutations in the SHH pathway induce tumors only in rare GCPs, suggesting that additional mutations and epigenetic changes are required to influence tumor progression. The KMT2D gene, encoding the histone-lysine N-methyltransferase 2D, is amongst the ten most frequently mutated genes in MB, with somatic mutations seen in ~15% of all SHH-MB patients. We developed sporadic mouse models of SHH-MB with a low penetrance to enable studies of secondary mutations (Tan, PNAS, 2018). Immunofluorescence staining for KMT2D on early-stage SHH-MB lesions, mid-stage and late-stage tumors revealed that a subset of lesions/tumors (16/98) do not express KMT2D and are negative for H3K4me3. Interestingly, P53 and KMT2D expression showed a positive correlation in ~94% of tumors/lesions and NeuN and KMT2D showed a positive correlation in ~92% of tumors/lesions. In order to determine the roles for KMT2D in GCP proliferation and differentiation, and uncover whether and how KMT2D promotes SHH-MB tumorigenesis, we are using genetic mouse-models whereby Kmt2d is heterozygously or homozygously deleted alone, or in conjunction with activation of the SHH pathway. Mice with SHH-MB tumors expressing SmoM2 and a loss of Kmt2d develop aggressive tumors at high penetrance, with metastatic leptomeningeal spread in the brain stem and spinal cord. Thus, loss of Kmt2d increases SHH-MB tumor progression and leads to malignancy. Ongoing studies are determining how the chromatin landscape and gene expression are changed when Kmt2d is deleted in GCPs.

KMT2D deficiency enhances the anti-cancer activity of L48H37 in pancreatic ductal adenocarcinoma.

BACKGROUNDNovel therapeutic strategies are urgently needed for patients with a delayed diagnosis of pancreatic ductal adenocarcinoma (PDAC) in order to improve their chances of survival. Recent studies have shown potent anti-neoplastic effects of curcumin and its analogues. In addition, the role of histone methyltransferases on cancer therapeutics has also been elucidated. However, the relationship between these two factors in the treatment of pancreatic cancer remains unknown. Our working hypothesis was that L48H37, a novel curcumin analog, has better efficacy in pancreatic cancer cell growth inhibition in the absence of histone-lysine N-methyltransferase 2D (KMT2D).AIMTo determine the anti-cancer effects of L48H37 in PDAC, and the role of KMT2D on its therapeutic efficacy.METHODSThe viability and proliferation of primary (PANC-1 and MIA PaCa-2) and metastatic (SW1990 and ASPC-1) PDAC cell lines treated with L48H37 was determined by CCK8 and colony formation assay. Apoptosis, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) levels, and cell cycle profile were determined by staining the cells with Annexin-V/7-AAD, JC-1, DCFH-DA, and PI respectively, as well as flow cytometric acquisition. In vitro migration was assessed by the wound healing assay. The protein and mRNA levels of relevant factors were analyzed using Western blotting, immunofluorescence and real time-quantitative PCR. The in situ expression of KMT2D in both human PDAC and paired adjacent normal tissues was determined by immunohistochemistry. In vivo tumor xenografts were established by injecting nude mice with PDAC cells. Bioinformatics analyses were also conducted using gene expression databases and TCGA.RESULTSL48H37 inhibited the proliferation and induced apoptosis in SW1990 and ASPC-1 cells in a dose- and time-dependent manner, while also reducing MMP, increasing ROS levels, arresting cell cycle at the G2/M stages and activating the endoplasmic reticulum (ER) stress-associated protein kinase RNA-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α/activating transcription factor 4 (ATF4)/CHOP signaling pathway. Knocking down ATF4 significantly upregulated KMT2D in PDAC cells, and also decreased L48H37-induced apoptosis. Furthermore, silencing KMT2D in L48H37-treated cells significantly augmented apoptosis and the ER stress pathway, indicating that KMT2D depletion is essential for the anti-neoplastic effects of L48H37. Administering L48H37 to mice bearing tumors derived from control or KMT2D-knockdown PDAC cells significantly decreased the tumor burden. We also identified several differentially expressed genes in PDAC cell lines expressing very low levels of KMT2D that were functionally categorized into the extrinsic apoptotic signaling pathway. The KMT2D high- and low-expressing PDAC patients from the TCGA database showed similar survival rates,but higher KMT2D expression was associated with poor tumor grade in clinical and pathological analyses.CONCLUSIONL48H37 exerts a potent anti-cancer effect in PDAC, which is augmented by KMT2D deficiency.

Analysis of the role of mutations in the KMT2D histone lysine methyltransferase in bladder cancer.

Histone lysine methyltransferases (HMT) comprise a subclass of epigenetic regulators; dysregulation of these enzymes affects gene expression, which may lead to tumorigenesis. Here, we performed an integrated analysis of 50 HMTs in bladder cancer and found intrinsic links between copy number alterations, mutations, gene expression levels, and clinical outcomes. Through integrative analysis, we identified six HMT genes (PRDM9,ASH1L,SETD3,SETD5,WHSC1L1, and KMT2D) that may play a key role in the development and progression of bladder cancer. Of these six HMTs, histone lysine N‐methyltransferase 2D (KMT2D) exhibited the highest mutation rate in bladder cancer. Our comparison of the mRNA and miRNA expression profiles of mutated and wild‐type KMT2D suggested that two signaling pathways (FOX1–miR‐1224‐5p–DLK1 and HIF/GATA5–miR‐133a‐3p–DRD5) may mediate the tumor suppressive effect of the KMT2D mutation. In summary, our findings indicate that mutations in HMT genes, especially KMT2D mutation, may play a role in the development of bladder cancer.

KMT2D Is a Haploinsufficient Tumor Suppressor in Acute Leukemia

Introduction: Epigenetic dysregulation plays a critical role in hematologic tumorigenesis and cancer progression. Histone-lysine N-methyltransferase 2D (KMT2D), also known as MLL4 (mixed-lineage leukemia 4), belongs to a family of mammalian histone H3 lysine 4 (H3K4) methyltransferases, which is amongst the most frequently mutated epigenetic genes in human cancers. It was reported that deletion of KMT2D inhibits MLL1-fusion-induced acute myeloid leukemia (Santos et al. 2014). However, in human cancers, the vast majority of the mutations in KMT2D is heterozygous deletion. Recent studies have revealed the role of KMT2D in lymphomagenesis, but the potential tumor suppressor function of KMT2D in leukemogenesis remains largely unclear. In addition, KMT2D was found to exist within a macromolecular complex named COMPASS (complex of proteins associated with Set1). KMT2C is another component of the complex, and was validated as another haploinsufficient tumor suppressor gene in acute myeloid leukemia (Chen et al. 2014). Mutations in KMT2D and KMT2C frequently co-occur in hematologic malignancies. Thus, we sought to first examine the role and molecular mechanism of KMT2D in acute leukemia, and then investigate whether co-mutated gene KMT2D and KMT2C have cooperative function in malignancies initiation and progression.Methods: Here we utilized RNAi approach to knockdown the expression of Kmt2d, and an approximate 50% reduction in gene dosage was validated by quantitative RT-PCR. We introduced two independent short-hairpin RNAs (shRNAs) targeting Kmt2d and a shRNA targeting Nf1 into p53 null hematopoietic stem and progenitor cells (hereafter referred to as shKmt2d;shNf1;p53-/- cells), and transplanted them into sublethally irradiated mice to model the impact of haploinsufficient tumor suppressors. The recipient mice were then monitored for the emergence of diseases by complete blood count as well as overall survival. Bone marrow was harvested and analyzed by flow cytometry after sacrifice. Histological analyses of blood smear, liver, spleen and bone marrow were conducted to accurately diagnose the disease. Besides, we established Kmt2d heterozygous and homozygous conditional knockout mouse models (Kmt2d fl/+; Mx1-Cre, Kmt2d fl/fl; Mx1-Cre) to further investigate the respective role of haploinsufficiency and deletion of KMT2D in acute leukemia. To study the cooperative function of KMT2D and KMT2C in leukemogenesis, two genes were co-suppressed by shRNAs in the same aforementioned genetic background (shNf1; p53-/-). Transplantation-based mouse modeling approach was used and the recipient mice were monitored for evidence of hematologic diseases.Results: A significant increase in peripheral white blood cell counts, anemia and thrombocytopenia were noticed in recipients of shKmt2d;shNf1;p53-/- cells over the same period after 4 weeks post-transplantation. Massive hepatomegaly and splenomegaly were displayed in those mice and a dramatic reduction in survival was observed (shKmt2d-1: median survival = 47 days, p = 0.0004 versus shRen; and shKmt2d-2: median survival = 74 days, p = 0.0127 versus shRen). Flow cytometry of cells from bone marrow of sacrificed mice showed a substantial enrichment of doule-positve cells (shRNAs targeting Kmt2d were linked to GFP and those targeting Nf1 were linked to mCherry) as compared to pre-injected, which were filled with leukemic cells that expressed myeloid/lymphoid lineage markers. Pathological analyses demonstrated the onset of acute myeloid/lymphoid leukemia. In Kmt2d and Kmt2c double-knockdown animal assay, the onset of acute myeloid leukemia was promoted compared with single-knockdown groups. (shKmt2d;shKmt2c: median survival = 48.5 days, p < 0.0001 versus shKmt2d; p = 0.0013 versus shKmt2c).Conclusions: KMT2D is a haploinsufficient tumor suppressor in acute leukemia. KMT2D deficiency cooperates with KMT2C to promote the development and progress of acute leukemia. Further understandings of the molecular mechanism of KMT2D as a haploinsufficient tumor suppressor in acute leukemia and the cooperative function of KMT2D and KMT2C in leukemogenesis are demanded, which can provide insights into developing novel therapeutic targets. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Systemic lupus erythematosus: A new autoimmune disorder in Kabuki syndrome

We report a case of a 17-year-old Caucasian girl with syndromic features of clinically unrecognized Kabuki syndrome (KS), who developed systemic lupus erythematosus (SLE). Diagnosis of KS was established after whole exome sequencing (WES) and detection of de novo frameshift 1bp deletion in histone-lysine N-methyltransferase 2D gene (KMT2D). The pathogenic variant in exon 34 (c.8626delC: 55 reads C, 56 reads delC), has not been described previously and is predicted to truncate the protein (p.Gln2876Serfs*34) resulting in KMT2D loss of function. Notwithstanding that patients with KS have a substantial susceptibility to various autoimmune diseases, to the best of our knowledge this is the first report of an SLE and KS association. The exact relationship between the two conditions in our patient is difficult to determine with certainty, as a number of clinical features, including positive antiphospholipid antibodies, persistent hypogammaglobulinemia and the episode of convulsions may occur in both conditions, suggesting potential overlap of KS and SLE. The combination of a high susceptibility towards infections and an autoimmune disorder present a great challenge when trying to achieve the optimum therapy which will enable the patient to stay on the thin line of remission. This case report emphasizes the value of WES as a powerful tool for the diagnosis of rare disorders and/or unusual disease presentations of possible genetic cause.

Expanding the Oro-Dental and Mutational Spectra of Kabuki Syndrome and Expression of KMT2D and KDM6A in Human Tooth Germs.

Kabuki syndrome is a rare genetic disorder characterized by distinct dysmorphic facial features, intellectual disability, and multiple developmental abnormalities. Despite more than 350 documented cases, the oro-dental spectrum associated with kabuki syndrome and expression of KMT2D (histone-lysine N-methyltransferase 2D) or KDM6A (lysine-specific demethylase 6A) genes in tooth development have not been well defined. Here, we report seven unrelated Thai patients with Kabuki syndrome having congenital absence of teeth, malocclusion, high-arched palate, micrognathia, and deviated tooth shape and size. Exome sequencing successfully identified that six patients were heterozygous for mutations in KMT2D, and one in KDM6A. Six were novel mutations, of which five were in KMT2D and one in KDM6A. They were truncating mutations including four frameshift deletions and two nonsense mutations. The predicted non-functional KMT2D and KDM6A proteins are expected to cause disease by haploinsufficiency. Our study expands oro-dental, medical, and mutational spectra associated with Kabuki syndrome. We also demonstrate for the first time that KMT2D and KDM6A are expressed in the dental epithelium of human tooth germs.

Epigenetic control of the immune system: a lesson from Kabuki syndrome

Kabuki syndrome (KS) is a rare multi-systemic disorder characterized by a distinct face, postnatal growth deficiency, mild-to-moderate intellectual disability, skeletal and visceral (mainly cardiovascular, renal, and skeletal) malformations, dermatoglyphic abnormalities. Its cause is related to mutations of two genes: KMT2D (histone-lysine N-methyltransferase 2D) and KDM6A (lysine-specific demethylase 6A), both functioning as epigenetic modulators through histone modifications in the course of embryogenesis and in several biological processes. Epigenetic regulation is defined as the complex of hereditable modifications to DNA and histone proteins that modulates gene expression in the absence of DNA nucleotide sequence changes. Different human disorders are caused by mutations of genes involved in the epigenetic regulation, and not surprisingly, all these share developmental defects, disturbed growth (in excess or defect), multiple congenital organ malformations, and also hematological and immunological defects. In particular, most KS patients show increased susceptibility to infections and have reduced serum immunoglobulin levels, while some suffer also from autoimmune manifestations, such as idiopathic thrombocytopenic purpura, hemolytic anemia, autoimmune thyroiditis, and vitiligo. Herein we review the immunological aspects of KS and propose a novel model to account for the immune dysfunction observed in this condition.