H3K4me1 facilitates promoter-enhancer interactions and gene activation during embryonic stem cell differentiation.

Histone H3 lysine 4 mono-methylation (H3K4me1) marks poised or active enhancers. KMT2C (MLL3) and KMT2D (MLL4) catalyze H3K4me1, but their histone methyltransferase activities are largely dispensable for transcription during early embryogenesis in mammals. To better understand the role of H3K4me1 in enhancer function, we analyze dynamic enhancer-promoter (E-P) interactions and gene expression during neural differentiation of the mouse embryonic stem cells. We found that KMT2C/D catalytic activities were only required for H3K4me1 and E-P contacts at a subset of candidate enhancers, induced upon neural differentiation. By contrast, a majority of enhancers retained H3K4me1 in KMT2C/D catalytic mutant cells. Surprisingly, H3K4me1 signals at these KMT2C/D-independent sites were reduced after acute depletion of KMT2B, resulting in aggravated transcriptional defects. Our observations therefore implicate KMT2B in the catalysis of H3K4me1 at enhancers and provide additional support for an active role of H3K4me1 in enhancer-promoter interactions and transcription in mammalian cells.

Pathogenic variants in KMT2C result in a neurodevelopmental disorder distinct from Kleefstra and Kabuki syndromes.

Trithorax-related H3K4 methyltransferases, KMT2C and KMT2D, are critical epigenetic modifiers. Haploinsufficiency of KMT2C was only recently recognized as a cause of neurodevelopmental disorder (NDD), so the clinical and molecular spectrums of the KMT2C-related NDD (now designated as Kleefstra syndrome 2) are largely unknown. We ascertained 98 individuals with rare KMT2C variants, including 75 with protein-truncating variants (PTVs). Notably, ∼15% of KMT2C PTVs were inherited. Although the most highly expressed KMT2C transcript consists of only the last four exons, pathogenic PTVs were found in almost all the exons of this large gene. KMT2C variant interpretation can be challenging due to segmental duplications and clonal hematopoesis-induced artifacts. Using samples from 27 affected individuals, divided into discovery and validation cohorts, we generated a moderate strength disorder-specific KMT2C DNA methylation (DNAm) signature and demonstrate its utility in classifying non-truncating variants. Based on 81 individuals with pathogenic/likely pathogenic variants, we demonstrate that the KMT2C-related NDD is characterized by developmental delay, intellectual disability, behavioral and psychiatric problems, hypotonia, seizures, short stature, and other comorbidities. The facial module of PhenoScore, applied to photographs of 34 affected individuals, reveals that the KMT2C-related facial gestalt is significantly different from the general NDD population. Finally, using PhenoScore and DNAm signatures, we demonstrate that the KMT2C-related NDD is clinically and epigenetically distinct from Kleefstra and Kabuki syndromes. Overall, we define the clinical features, molecular spectrum, and DNAm signature of the KMT2C-related NDD and demonstrate they are distinct from Kleefstra and Kabuki syndromes highlighting the need to rename this condition.

Mll3 and Mll4 Facilitate Enhancer RNA Synthesis and Transcription from Promoters Independently of H3K4 Monomethylation.

Monomethylation of histone H3 at lysine 4 (H3K4me1) and acetylation of histone H3 at lysine 27 (H3K27ac) are correlated with transcriptionally engaged enhancer elements, but the functional impact of these modifications on enhancer activity is not well understood. Here we used CRISPR/Cas9 genome editing to separate catalytic activity-dependent and independent functions of Mll3 (Kmt2c) and Mll4 (Kmt2d, Mll2), the major enhancer H3K4 monomethyltransferases. Loss of H3K4me1 from enhancers in Mll3/4 catalytically deficient cells causes partial reduction of H3K27ac, but has surprisingly minor effects on transcription from either enhancers or promoters. In contrast, loss of Mll3/4 proteins leads to strong depletion of enhancer Pol II occupancy and eRNA synthesis, concomitant with downregulation of target genes. Interestingly, downregulated genes exhibit reduced polymerase levels in gene bodies, but not at promoters, suggestive of pause-release defects. Altogether, our results suggest that enhancer H3K4me1 provides only a minor contribution to the long-range coactivator function of Mll3/4.

Loss of Kmt2c in vivo leads to EMT, mitochondrial dysfunction and improved response to lapatinib in breast cancer.

Deep sequencing of human tumours has uncovered a previously unappreciated role for epigenetic regulators in tumorigenesis. H3K4 methyltransferase KMT2C/MLL3 is mutated in several solid malignancies, including more than 10% of breast tumours. To study the tumour suppressor role of KMT2C in breast cancer, we generated mouse models of Erbb2/Neu, Myc or PIK3CA-driven tumorigenesis, in which the Kmt2c locus is knocked out specifically in the luminal lineage of mouse mammary glands using the Cre recombinase. Kmt2c knock out mice develop tumours earlier, irrespective of the oncogene, assigning a bona fide tumour suppressor role for KMT2C in mammary tumorigenesis. Loss of Kmt2c induces extensive epigenetic and transcriptional changes, which lead to increased ERK1/2 activity, extracellular matrix re-organization, epithelial-to-mesenchymal transition and mitochondrial dysfunction, the latter associated with increased reactive oxygen species production. Loss of Kmt2c renders the Erbb2/Neu-driven tumours more responsive to lapatinib. Publicly available clinical datasets revealed an association of low Kmt2c gene expression and better long-term outcome. Collectively, our findings solidify the role of KMT2C as a tumour suppressor in breast cancer and identify dependencies that could be therapeutically amenable.

Implication of KMT2C and TSC2 variants in the tumorigenesis of acquired cystic disease-associated renal cell carcinomas.

In 2020, acquired cystic disease-associated renal cell carcinomas (ACD-RCCs) were reported to harbor KMT2C and TSC2 variants: however, their carcinogenic implication has not yet been reported. This study aimed to explore the variant features of KMT2C and TSC2 in ACD-RCC and their implication in ACD-RCC tumorigenesis. Eleven ACD-RCCs, 10 ACD-RCC-like cysts, and 18 background kidneys were retrieved. The background kidneys consisted of atrophic thyroid follicle-like tubules. They included four with clustered cysts, two with eosinophilic changes, and one each with clear cell changes and sieve-like changes in the renal tubules. First, DNA-targeted sequencing of KMT2C and TSC2 whole exons was performed on eight ACD-RCC samples. Subsequently, a custom DNA panel was designed to include the recurrent KMT2C and TSC2 variants based on the sequencing results. Second, DNA-targeted sequencing was performed on the remaining samples using a custom panel targeting the recurrent variants. Additionally, immunohistochemistry was performed for KMTC, H3K4me1, H3K4me3, TSC2, and GPNMB on the ACD-RCCs. Six of the 11 ACD-RCC cases harbored KMT2C and TSC2 variants, including nine likely pathogenic variants. In contrast to ACD-RCC, 1 of the 9 ACD-RCC-like cysts harbored both variants. Immunohistochemical analysis did not support the loss of function in ACD-RCCs harboring KMT2C and TSC2 variants. KMT2C and TSC2 variant frequencies were higher in ACD-RCC than in other renal cell carcinomas. However, KMT2C and TSC2 are unlikely to be the primary drivers of ACD-RCC development.

Unveiling the Molecular Landscape of Pancreatic Ductal Adenocarcinoma: Insights into the Role of the COMPASS-like Complex.

Pancreatic ductal adenocarcinoma (PDAC) is poised to become the second leading cause of cancer-related death by 2030, necessitating innovative therapeutic strategies. Genetic and epigenetic alterations, including those involving the COMPASS-like complex genes, have emerged as critical drivers of PDAC progression. This review explores the genetic and epigenetic landscape of PDAC, focusing on the role of the COMPASS-like complex in regulating chromatin accessibility and gene expression. Specifically, we delve into the functions of key components such as KDM6A, KMT2D, KMT2C, KMT2A, and KMT2B, highlighting their significance as potential therapeutic targets. Furthermore, we discuss the implications of these findings for developing novel treatment modalities for PDAC.

A Pilot Study Based on the Correlation Between Whole Exome and Transcriptome Reveals Potent Variants in the Indian Population of Cervical Cancer.

Cervical malignancy (CC) is the 2nd most prevalent malignancy among females, leading to cancer mortality. Primary detection of CC tumors results in an improved prognosis. CC is a malignant gynecological tumor, with few treatment options. New diagnostic and therapeutic agents are required to expand patient survival and quality of life. If CC tumors can be found at an early stage, the prognosis is much brighter. New diagnostic and therapeutic agents are needed to increase patient survival and quality of life. In this work, we performed whole-exome sequencing utilizing V5 (Illumina platform) 10 samples, 5 control and 5 CC tumour tissue, and we compared the results with transcriptome studies. KMT2C variations were shown to be among the most vicious in this analysis. From an Indian viewpoint, we found a plethora of SNVs and mutations, including those with known, unknown, and possible effects on health. Based on our findings, we know that the KMT2C gene is on chr. Seven and in exon 8, all three recognized variants are missense, synonymous, coding synonymous, non-coding variants, and GnomAD MAF (- 0.05). The variation at position (7:152265091, T > A, SNV 62478356) in KMT2C is unique, potent, and pathogenic. The missense coding transcript CIQTNF maps to chromosome 7 and displays T > C SNV. In addition, we performed single strand conformational polymorphism analysis on 64 samples and further confirmed them using Sanger sequencing to understand and verify the mutations. KMT2C shows a log FC value of - 1.16. Understanding emerging harmful mutations from an Indian viewpoint is facilitated by our bioinformatics-based, extensive correlation studies of WES analysis. Potentially harmful and new mutations were found in our preliminary analysis; among these ten top mutated genes, KMT2C and CIQTNF were altered in ten cases of CC with an Indian phenotype.

Lpt, trr, and Hcf regulate histone mono- and dimethylation that are essential for Drosophila heart development.

Mammalian KMT2C, KMT2D, and HCFC1 are expressed during heart development and have been associated with congenital heart disease, but their roles in heart development remain elusive. We found that the Drosophila Lpt and trr genes encode the N-terminal and C-terminal homologs, respectively, of mammalian KMT2C or KMT2D. Lpt and trr mutant embryos showed reduced cardiac progenitor cells. Silencing of Lpt, trr, or both simultaneously in the heart led to similar abnormal cardiac morphology, tissue fibrosis, and cardiac functional defects. Like KMT2D, Lpt and trr were found to modulate histone H3K4 mono- and dimethylation, but not trimethylation. Investigation of downstream genes regulated by mouse KMT2D in the heart showed that their fly homologs are similarly regulated by Lpt or trr in the fly heart, suggesting that Lpt and trr regulate an evolutionarily conserved transcriptional network for heart development. Moreover, we showed that cardiac silencing of Hcf, the fly homolog of mammalian HCFC1, leads to heart defects similar to those observed in Lpt and trr silencing, as well as reduced H3K4 monomethylation. Our findings suggest that Lpt and trr function together to execute the conserved function of mammalian KMT2C and KMT2D in histone H3 lysine K4 mono- and dimethylation required for heart development. Possibly aided by Hcf, which we show plays a related role in H3K4 methylation during fly heart development.

Association of KMT2C/D loss-of-function variants with response to immune checkpoint blockades in colorectal cancer.

Immune checkpoint inhibitors (ICIs) have become important treatment strategies, yet responses vary among patients and predictive biomarkers are urgently needed. Mutations in KMT2C and KMT2D lead to increased levels of genomic instability. Therefore, we aimed to examine whether KMT2C/D mutations might be a predictor of immunotherapeutic efficacy. Here, we investigated the associations of KMT2C/D loss-of-function (LOF) variants with tumor mutation burden (TMB), MSI-H, PD-L1 expression, the levels of tumor-infiltrating leukocytes (TILs), and clinical response to ICIs. It was found that KMT2C/D LOF variants were associated with higher TMB. Compared with the non-LOF group, the proportion of patients with MSI-H tumors was larger in the LOF group. PD-L1 expression was higher in the LOF group only for colorectal cancer in both the Chinese and The Cancer Genome Atlas cohorts. Importantly, KMT2C/D LOF variants were associated with decreased regulatory T cells and increased levels of CD8+ T cells, activated NK cells, M1 macrophages, and M2 macrophages in colorectal cancer. However, there was no significant association between KMT2C/D LOF and TILs levels in other cancer types. Consistently, the results showed that KMT2C/D LOF variants were associated with prolonged overall survival only in colorectal cancer (p = 0.0485). We also presented that patients with KMT2C/D LOF mutations exhibited a better clinical response to anti-PD-1 therapy in a Chinese colorectal cancer cohort (p = 0.002). Taken together, these results suggested that KMT2C/D LOF variants could be a useful predictor for ICIs efficacy in colorectal cancer. In addition, the predictive value of KMT2C/D LOF variants was consistent with their association with TILs levels.

Circadian clock function does not require the histone methyltransferase MLL3.

The circadian clock controls the physiological function of tissues through the regulation of thousands of genes in a cell-type-specific manner. The core cellular circadian clock is a transcription-translation negative feedback loop, which can recruit epigenetic regulators to facilitate temporal control of gene expression. Histone methyltransferase, mixed lineage leukemia gene 3 (MLL3) was reported to be required for the maintenance of circadian oscillations in cultured cells. Here, we test the role of MLL3 in circadian organization in whole animals. Using mice expressing catalytically inactive MLL3, we show that MLL3 methyltransferase activity is in fact not required for circadian oscillations in vitro in a range of tissues, nor for the maintenance of circadian behavioral rhythms in vivo. In contrast to a previous report, loss of MLL3-dependent methylation did not affect the global levels of H3K4 methylation in liver, indicating substantial compensation from other methyltransferases. Furthermore, we found little evidence of genomic repositioning of H3K4me3 marks. We did, however, observe repositioning of H3K4me1 from intronic regions to intergenic regions and gene promoters; however, there were no changes in H3K4me1 mark abundance around core circadian clock genes. Output functions of the circadian clock, such as control of inflammation, were largely intact in MLL3-methyltransferase-deficient mice, although some gene-specific changes were observed, with sexually dimorphic loss of circadian regulation of specific cytokines. Taken together, these observations indicate that MLL3-directed histone methylation is not essential for core circadian clock function; however, it may influence the inflammatory response.

LncRNA LINC00205 stimulates osteoporosis and contributes to spinal fracture through the regulation of the miR-26b-5p/KMT2C axis.

BACKGROUND: Osteoporosis (OP) is a common bone disease marked by decreased bone strength. Increasing evidence suggests that long non-coding RNA (lncRNAs) play important roles in the occurrence and progression of OP. This study aimed to investigate the role and mechanism of LINC00205 in the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and OP. METHODS: Bone tissue samples were obtained from healthy controls and patients with osteoporosis with a spinal fracture (OP-Frx) or without a spinal fracture (OP-no-Frx). HMSCs were cultured and induced to undergo osteogenic differentiation. The expression of LINC00205, lysine (K)-specific methyltransferase 2C (KMT2C), and miR-26b-5p in bone tissues and cells was evaluated using western blotting and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The effects of LINC00205, miR-26b-5p, and KMT2C on calcium deposition, alkaline phosphatase (ALP) activity, and mRNA levels of the osteogenic differentiation marker genes [ALP, osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2)] were investigated using alizarin red S staining, an ALP activity assay, and qRT-PCR, respectively. Dual-luciferase reporter assay was performed to ascertain the binding relationship between miR-26b-5p and LINC00205/KMT2C. RESULTS: LINC00205 and KMT2C were upregulated in patients with OP-Frx and OP-no-Frx, whereas miR-26b-5p was downregulated. Furthermore, LINC00205 and KMT2C expression decreased, whereas that of miR-26b-5p increased over time from day 7 to 21 of the osteogenic differentiation of hMSCs. The knockdown of LINC00205 and KMT2C significantly increased ALP activity, calcium deposition, and the expression of RUNX2, ALP, and OCN. In contrast, the inhibition of miR-26b-5p yielded the opposite result. These data suggest that LINC00205 inhibits the osteogenic differentiation of hMSCs by modulating the miR-26b-5p/KMT2C signaling axis. CONCLUSION: LINC00205 promotes OP and is involved in spinal fractures. LINC00205 is also a potential negative regulator of the osteogenic differentiation of hMSCs.

KMT2C methyltransferase domain regulated INK4A expression suppresses prostate cancer metastasis.

BACKGROUND: Frequent truncation mutations of the histone lysine N-methyltransferase KMT2C have been detected by whole exome sequencing studies in various cancers, including malignancies of the prostate. However, the biological consequences of these alterations in prostate cancer have not yet been elucidated. METHODS: To investigate the functional effects of these mutations, we deleted the C-terminal catalytic core motif of Kmt2c specifically in mouse prostate epithelium. We analysed the effect of Kmt2c SET domain deletion in a Pten-deficient PCa mouse model in vivo and of truncation mutations of KMT2C in a large number of prostate cancer patients. RESULTS: We show here for the first time that impaired KMT2C methyltransferase activity drives proliferation and PIN formation and, when combined with loss of the tumour suppressor PTEN, triggers loss of senescence, metastatic dissemination and dramatically reduces life expectancy. In Kmt2c-mutated tumours we show enrichment of proliferative MYC gene signatures and loss of expression of the cell cycle repressor p16INK4A. In addition, we observe a striking reduction in disease-free survival of patients with KMT2C-mutated prostate cancer. CONCLUSIONS: We identified truncating events of KMT2C as drivers of proliferation and PIN formation. Loss of PTEN and KMT2C in prostate cancer results in loss of senescence, metastatic dissemination and reduced life expectancy. Our data demonstrate the prognostic significance of KMT2C mutation status in prostate cancer patients. Inhibition of the MYC signalling axis may be a viable treatment option for patients with KMT2C truncations and therefore poor prognosis.

KMT2C mutation in a Chinese man with primary multidrug-resistant metastatic adenocarcinoma of rete testis: a case report.

BACKGROUND: Adenocarcinoma of the rete testis (AORT) is an extremely rare malignant tumor with poor prognosis and limited responsiveness to traditional chemotherapy. Few previous studies have focused on the molecular mechanisms underlying therapy resistance in AORT and further scrutiny is required to enable searches for targeted drugs to guide treatment selection. CASE PRESENTATION: The current case concerns a 55-year-old man with AORT who presented with isolated bone metastasis at initial diagnosis and experienced rapid disease progression after multi-line platinum-based combination chemotherapy. Next-generation sequencing revealed a novel somatic lysine methyltransferase 2C (KMT2C) c.5605 T > C mutation in exon 36 with an abundance of 49.27%. The patient received antiangiogenic drug treatment for 2 months but this was discontinued due to unacceptable anorexia and nausea. He survived for 12 months after diagnosis. CONCLUSION: A potential correlation between AORT primary multi-drug resistance and KMT2C mutations is implied. Further studies are needed to determine the efficacy of PARP1/2 inhibitors for tumors with KMT2C mutations.

Histone Lysine Methylases and Demethylases in the Landscape of Human Developmental Disorders.

Histone lysine methyltransferases (KMTs) and demethylases (KDMs) underpin gene regulation. Here we demonstrate that variants causing haploinsufficiency of KMTs and KDMs are frequently encountered in individuals with developmental disorders. Using a combination of human variation databases and existing animal models, we determine 22 KMTs and KDMs as additional candidates for dominantly inherited developmental disorders. We show that KMTs and KDMs that are associated with, or are candidates for, dominant developmental disorders tend to have a higher level of transcription, longer canonical transcripts, more interactors, and a higher number and more types of post-translational modifications than other KMT and KDMs. We provide evidence to firmly associate KMT2C, ASH1L, and KMT5B haploinsufficiency with dominant developmental disorders. Whereas KMT2C or ASH1L haploinsufficiency results in a predominantly neurodevelopmental phenotype with occasional physical anomalies, KMT5B mutations cause an overgrowth syndrome with intellectual disability. We further expand the phenotypic spectrum of KMT2B-related disorders and show that some individuals can have severe developmental delay without dystonia at least until mid-childhood. Additionally, we describe a recessive histone lysine-methylation defect caused by homozygous or compound heterozygous KDM5B variants and resulting in a recognizable syndrome with developmental delay, facial dysmorphism, and camptodactyly. Collectively, these results emphasize the significance of histone lysine methylation in normal human development and the importance of this process in human developmental disorders. Our results demonstrate that systematic clinically oriented pathway-based analysis of genomic data can accelerate the discovery of rare genetic disorders.

KMT2C is a potential biomarker of prognosis and chemotherapy sensitivity in breast cancer.

PURPOSE: Epigenetic regulation plays critical roles in cancer progression, and high-frequency mutations or expression variations in epigenetic regulators have been frequently observed in tumorigenesis, serving as biomarkers and targets for cancer therapy. Here, we aimed to explore the function of epigenetic regulators in breast cancer. METHODS: The mutational landscape of epigenetic regulators in breast cancer samples was investigated based on datasets from the Cancer Genome Atlas. The Kaplan-Meier method was used for survival analysis. RNA sequencing (RNA-seq) in MCF-7 cells transfected with control siRNA or KMT2C siRNA was performed. Quantitative reverse transcription-PCR and chromatin immunoprecipitation were used to validate the RNA-seq results. RESULTS: Among the 450 epigenetic regulators, KMT2C was frequently mutated in breast cancer samples. The tumor mutational burden (TMB) was elevated in breast cancer samples with KMT2C mutations or low KMT2C mRNA levels compared to their counterparts with wild-type KMT2C or high KMT2C mRNA levels. Somatic mutation and low expression of KMT2C were independently correlated with the poor overall survival (OS) and disease-free survival (DFS) of the breast cancer samples, respectively. RNA-seq analysis combined with chromatin immunoprecipitation and qRT-PCR assays revealed that the depletion of KMT2C remarkably affected the expression of DNA damage repair-related genes. More importantly, the low expression of KMT2C was related to breast cancer cell sensitivity to chemotherapy and longer OS of breast cancer patients who underwent chemotherapy. CONCLUSION: We conclude that KMT2C could serve as a potential biomarker of prognosis and chemotherapy sensitivity by affecting the DNA damage repair-related genes of breast cancer.

The lysine-specific methyltransferase KMT2C/MLL3 regulates DNA repair components in cancer.

Genome-wide studies in tumor cells have indicated that chromatin-modifying proteins are commonly mutated in human cancers. The lysine-specific methyltransferase 2C (KMT2C/MLL3) is a putative tumor suppressor in several epithelia and in myeloid cells. Here, we show that downregulation of KMT2C in bladder cancer cells leads to extensive changes in the epigenetic status and the expression of DNA damage response and DNA repair genes. More specifically, cells with low KMT2C activity are deficient in homologous recombination-mediated double-strand break DNA repair. Consequently, these cells suffer from substantially higher endogenous DNA damage and genomic instability. Finally, these cells seem to rely heavily on PARP1/2 for DNA repair, and treatment with the PARP1/2 inhibitor olaparib leads to synthetic lethality, suggesting that cancer cells with low KMT2C expression are attractive targets for therapies with PARP1/2 inhibitors.

XIST lost induces ovarian cancer stem cells to acquire taxol resistance via a KMT2C-dependent way.

BACKGROUND/AIMS: The expression levels of long non-coding RNA XIST are significantly associated with paclitaxel (Pac) sensitivity in ovarian cancer, but the mechanism of action remains unclear. Therefore, this experimental design was based on lncRNA XIST analysis to regulate the effect of XIST on the tumor stem cell and paclitaxel sensitivity in ovarian cancer. METHODS: Sphere assay and fluorescence activated cell sorting (FACS) were used to determine the expression levels of XIST and sensitivity to paclitaxel treatment. The effect of the proliferation was detected by MTT assay. Target gene prediction and screening, luciferase reporter assays were used to validate downstream target genes for lncRNA XIS and KMT2C. The expression of KMT2C was detected by RT-qPCR and Western blotting. RT-qPCR was used to detect the expression of cancer stem cell-associated genes SOX2, OCT4 and Nanog. The tumor changes in mice were detected by in vivo experiments in nude mice. RESULTS: There was an inverse correlation between the expression of XIST and cancer stem cell (CD44 + /CD24-) population. XIST promoted methylation of histone H3 methylation at lysine 4 by enhancing the stability of lysine (K)-specific methyltransferase 2C (KMT2C) mRNA. XIST acted on the stability of KMT2C mRNA by directly targeting miR-93-5p. Overexpression of miR-93-5p can reverse the XIST overexpression-induced KMT2C decrease and sphere number increase. Overexpression of KMT2C inhibited XIST silencing-induced proliferation of cancer stem cells, and KMT2C was able to mediate paclitaxel resistance induced by XIST in ovarian cancer. The study found that XIST can affect the expression of KMT2C in the ovarian cancer via targeting miR-93-5p. CONCLUSION: XIST promoted the sensitivity of ovarian cancer stem cells to paclitaxel in a KMT2C-dependent manner.

Analysis of mutations of PARP1, RNF213, PAX8, KMT2C, MTRR in malignant mesothelioma of testicular tunica vaginalis testis.

Molecular next gene sequencing was used to evaluate mutations in 409 common mutated cancer-related genes in malignant mesothelioma of tunica vaginalis testis (MMTVT) of 81-year-old man. Multifocal papillary-solid areas contained necrosis among highly cellular fields with multiple mitoses. It was positive for WT1, CKAE1/AE3, calretinin, CK7 with negativity for CK5, PSA, TTF-1. Following mutations were revealed in PARP1 (NM_001618: c.2285TG, p.K135R), MTRR (NM_024010: c.147A>G, p.I49M) and two sorts of mutations in structure of KMT2C gene (NM_170606: c.2447_2448insA (c.2447dupA), p.Y816fs and NM_170606: c.1042G>A, p.D348N) for the first time in MMTVT.

A Novel and Cytogenetically Cryptic t(7;21)(q36.1;q22) Disrupting RUNX1 in Acute Myeloid Leukemia.

Translocations involving the RUNX1 transcription factor gene are frequently identified in leukemia patients, but the partner genes have been characterized in only about half of these cases. We report here a novel RUNX1 partner gene, KMT2C (MLL3), in a patient with de novo acute myeloid leukemia, having a novel and cytogenetically cryptic t(7;21)(q36.1;q22) leading to disruption of RUNX1 and KMT2C. This is the third cryptic RUNX1 rearrangement in myeloid and the fourth in hematologic malignancies.

MLL2/KMT2D and MLL3/KMT2C expression correlates with disease progression and response to imatinib mesylate in chronic myeloid leukemia.

BACKGROUND: Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm whose pathogenesis is linked to the Philadelphia chromosome presence that generates the BCR-ABL1 fusion oncogene. Tyrosine kinase inhibitors (TKI) such as imatinib mesylate (IM) dramatically improved the treatment efficiency and survival of CML patients by targeting BCR-ABL tyrosine kinase. The disease shows three distinct clinical-laboratory stages: chronic phase, accelerated phase and blast crisis. Although patients in the chronic phase respond well to treatment, patients in the accelerated phase or blast crisis usually show therapy resistance and CML relapse. It is crucial, therefore, to identify biomarkers to predict CML genetic evolution and resistance to TKI therapy, considering not only the effects of genetic aberrations but also the role of epigenetic alterations during the disease. Although dysregulations in epigenetic modulators such as histone methyltrasnferases have already been described for some hematologic malignancies, to date very limited data is available for CML, especially when considering the lysine methyltransferase MLL2/KMT2D and MLL3/KMT2C. METHODS: Here we investigated the expression profile of both genes in CML patients in different stages of the disease, in patients showing different responses to therapy with IM and in non-neoplastic control samples. Imatinib sensitive and resistant CML cell lines were also used to investigate whether treatment with other tyrosine kinase inhibitors interfered in their expression. RESULTS: In patients, both methyltransferases were either upregulated or with basal expression level during the chronic phase compared to controls. Interestingly, MLL3/KMT2C and specially MLL2/KMT2D levels decreased during disease progression correlating with distinct clinical stages. Furthermore, MLL2/KMT2D was decreased in patients resistant to IM treatment. A rescue in the expression of both MLL genes was observed in KCL22S, a CML cell line sensitive to IM, after treatment with dasatinib or nilotinib which was associated with a higher rate of apoptosis, an enhanced expression of p21 (CDKN1A) and a concomitant decrease in the expression of CDK2, CDK4 and Cyclin B1 (CCNB1) in comparison to untreated KCL22S control or IM resistant KCL22R cell line, which suggests involvement of p53 regulated pathway. CONCLUSION: Our results established a new association between MLL2/KMT2D and MLL3/KMT2C genes with CML and suggest that MLL2/KMT2D is associated with disease evolution and may be a potential marker to predict the development of therapy resistance.