Lysine Methyltransferase 2D Research Articles

The low-complexity domains of the KMT2D protein regulate histone monomethylation transcription to facilitate pancreatic cancer progression

BackgroundLiquid–liquid phase separation (LLPS) within the nucleus is directly linked to driving gene expression through transcriptional complexes. Histone lysine methyltransferase 2D (KMT2D) is widely present in many cancers. It is known to epigenetically stimulate the expression of genes associated with tumorigenesis and metastasis. Our analyses show that KMT2D possesses two distinct low-complexity domains (LCDs) capable of driving the assembly of membrane-less condensates. The dependence of the mechanisms underlying monomethylation of H3K4 on the LLPS microenvironment derived from KMT2D LCDs is unclear in tumor.MethodsKMT2D LCD-depletion cells were used to investigate tumor cell proliferation, apoptosis, and migration. We identified some core proteins, including WDR5, RBBP5, and ASH2L, which are involved in the KMT2D-associated catalytic complex in KMT2D LCD-deficient cells to further elucidate the mechanism that decreases monomethylation of H3K4. We also evaluated the viability of KMT2D LCD-deficient cells in vivo. Finally, using 1,6-hexanediol (HD), an inhibitor of LLPS, we determined cell activities associated with KMT2D function in wild-type PANC-1 cells.ResultsWithout the LLPS microenvironment in KMT2D LCD-deficient cells or wild-type PANC-1 cells treated with HD, the WDR5 protein was significantly less stable and the protein–protein interactions between the components of the KMT2D–enzyme complex were attenuated, impairing the formation of the complex. Moreover, with the decrease in H3K4me1 level at enhancers, transcription factors such as LIFR and KLF4 were markedly downregulated, effectively inhibiting tumor progression. In xenograft tumor models, PANC-1 cells lacking the KMT2D LCDs showed effectively suppressed tumor growth compared to normal cells.ConclusionsOur data indicate that the two low-complexity domains of the KMT2D protein could form a stable LLPS microenvironment, promoting the KMT2D catalysis of H3K4 monomethylation through stabilization of the WDR5 protein and KMT2D–enzyme complex. Therefore, finding ways to regulate the LLPS microenvironment will be benefitial for new cancer treatment strategies.

Lysine methyltransferase 2D regulates muscle fiber size and muscle cell differentiation.

Kabuki syndrome (KS) is a rare genetic disorder caused primarily by mutations in the histone modifier genes KMT2D and KDM6A. The genes have broad temporal and spatial expression in many organs, resulting in complex phenotypes observed in KS patients. Hypotonia is one of the clinical presentations associated with KS, yet detailed examination of skeletal muscle samples from KS patients has not been reported. We studied the consequences of loss of KMT2D function in both mouse and human muscles. In mice, heterozygous loss of Kmt2d resulted in reduced neuromuscular junction (NMJ) perimeter, decreased muscle cell differentiation in vitro and impaired myofiber regeneration in vivo. Muscle samples from KS patients of different ages showed presence of increased fibrotic tissue interspersed between myofiber fascicles, which was not seen in mouse muscles. Importantly, when Kmt2d‐deficient muscle stem cells were transplanted in vivo in a physiologic non‐Kabuki environment, their differentiation potential is restored to levels undistinguishable from control cells. Thus, the epigenetic changes due to loss of function of KMT2D appear reversible through a change in milieu, opening a potential therapeutic avenue.

995P A pan-cancer analysis of KMT2D as a potential biomarker for immune checkpoint therapy

Lysine methyltransferase 2D (KMT2D), which encodes a histone H3 lysine 4 methyltransferase, is one of the most frequently mutated genes in cancer patients. Previous studies showed that KMT2D-mutant tumor cell lines exhibited increasing immune infiltration and KMT2D mutation was correlated with higher tumor mutation burden (TMB) in multiple types of human cancers in TCGA datasets, suggesting that KMT2D-deficient tumors might be more sensitive to immune checkpoint inhibitors (ICIs), but the correlation of KMT2D mutation status with immune response in clinical remains unknown.

Genetic alternations and immune characteristics in patients with small cell lung cancer

Genetic alternations and immune characteristics in patients with small cell lung cancer

Genomic Sequencing of Cancer-related Genes in Sinonasal Squamous Cell Carcinoma and Coexisting Inverted Papilloma.

The genetic basis of sinonasal inverted papilloma (SNIP)-derived squamous cell carcinoma (SCC) has not yet been well characterized. To characterize the genetic abnormalities of SNIP and SNIP-derived SCC and to uncover their differences. Mutations of 409 genes were analyzed using amplicon targeted sequencing in a total of six papilloma/carcinoma samples from four patients with SNIP-derived SCC. The genes that were mutated in multiple cases were epidermal growth factor receptor (EGFR) (3/6), cyclin-dependent kinase inhibitor 2A (CDKN2A) (3/6), lysine methyltransferase 2D (KMT2D) (3/6), tumor protein p53 (TP53) (3/6), neurofibromin 1 (NF1) (3/6), phosphodiesterase 4D interacting protein (PDE4DIP) (3/6), cytochrome P450 family 2 subfamily D member 6 (CYP2D6) (2/6), fms-related receptor tyrosine kinase 4 (FLT4) (2/6) and myosin heavy chain 9 (MYH9) (2/6). Of the two cases analyzed in the papilloma-oncology carcinoma pair, one did not have any common mutations; the other showed a staged functional deletion of TP53 during the process of malignant transformation from SNIP to SCC. CDKN2A, KMT2D, NF1, PDE4DIP, CYP2D6, FLT4, and MYH9 were identified as candidate novel SNIP-derived SCC-related genes.

Update of the genotype and phenotype of KMT2D and KDM6A by genetic screening of 100 patients with clinically suspected Kabuki syndrome.

Kabuki syndrome is characterized by a variable degree of intellectual disability, characteristic facial features, and complications in various organs. Many variants have been identified in two causative genes, that is, lysine methyltransferase 2D (KMT2D) and lysine demethylase 6A (KDM6A). In this study, we present the results of genetic screening of 100 patients with a suspected diagnosis of Kabuki syndrome in our center from July 2010 to June 2018. We identified 76 variants (43 novel) in KMT2D and 4 variants (3 novel) in KDM6A as pathogenic or likely pathogenic. Rare variants included a deep splicing variant (c.14000-8C>G) confirmed by RNA sequencing and an 18% mosaicism level for a KMT2D mutation. We also characterized a case with a blended phenotype consisting of Kabuki syndrome, osteogenesis imperfecta, and 16p13.11 microdeletion. We summarized the clinical phenotypes of 44 patients including a patient who developed cervical cancer of unknown origin at 16 years of age. This study presents important details of patients with Kabuki syndrome including rare clinical cases and expands our genetic understanding of this syndrome, which will help clinicians and researchers better manage and understand patients with Kabuki syndrome they may encounter.

Association analysis of KMT2D copy number variation as a positional candidate for growth traits.

Copy number variations (CNVs) are an important source of genetic variation, which can affect a wide range of economic traits by diverse mechanisms. KMT2D (Lysine methyltransferase 2D) is an important positional candidate for growth traits. Quantitative trait loci (QTLs) with large effects on economically important traits cover the KMT2D gene. The KMT2D gene overlays a CNV within its exons, hence it was chosen as a crucial candidate gene to study the association between CNV and growth traits. Further, KMT2D, a major mammalian histone H3K4 mono-methyltransferase, plays a critical role in regulating development, differentiation, metabolism, and tumor suppression. Therefore, we proposed the hypothesis that KMT2D CNV may have phenotypic effects on sheep growth traits. In our study, KMT2D CNVs in three Chinese sheep breeds were detected by quantitative polymerase chain reaction (qPCR), and the loss copy was found to be the dominant genotype. Association analysis between growth traits and KMT2D CNV was also performed, which revealed that individuals with the median copy showed better performance than those with the loss copy in all three breeds. This research suggested that KMT2D CNV can be used as a promising marker for sheep molecular breeding.

Abnormal Peyer patch development and B-cell gut homing drive IgA deficiency in Kabuki syndrome

Kabuki syndrome (KS) is commonly caused by mutations in the histone-modifying enzyme lysine methyltransferase 2D (KMT2D). Immune dysfunction is frequently observed in individuals with KS, but the role of KMT2D in immune system function has not been identified. We sought to understand the mechanisms driving KS-associated immune deficiency (hypogammaglobulinemia [low IgA], splenomegaly, and diminished immunization responses). We performed a comprehensive evaluation of humoral immunity and secondary lymphoid tissues in an established KS (Kmt2d+/βGeo) mouse model and validated select findings in a patient with KS. Compared with wild-type littermates, Kmt2d+/βGeo mice demonstrated deficiencies in multiple B-cell lineages and reduced serum IgA and elevated IgM levels across multiple ages. The bone marrow, spleen, and intestine of Kmt2d+/βGeo mice contained diminished numbers of IgA-secreting cells, while elevated germinal center B cells were found in the mesenteric lymph node and Peyer patches. Kmt2d+/βGeo mice have decreased size and numbers of Peyer patches, a finding confirmed in human samples. We identified deficiency of Itgb7 RNA and protein expression, a gene encoding an adhesion protein that mediates intestinal homing, and we demonstrated KMT2D-dependent control of ITGB7 expression in a human cell line. Kmt2d haploinsufficiency has broad deleterious effects on B-cell differentiation, specifically hampering gut lymphocyte homing and IgA+ plasma cell differentiation. Intestinal lymphoid defects caused by ITGB7 deficiency have not previously been recognized in KS, and these results provide new mechanistic insights into the pathogenesis of KS-associated immune deficiency.

Abstract 4168: Identify the predisposition genes to endometrial cancer

Abstract Endometrial carcinoma is the most dominant gynecological tumor worldwide. Familial risk of endometrial cancer has been reported but little is known about the predisposition genes. Here we focused on a family with high incidence of cancer, aiming to identify potential markers with low allele frequency and high disease-causing probability. Whole-genome sequencing was performed with available DNA from 4 family members: one healthy control and 3 endometrial cancer patients. We analyzed the non-synonymous variations in the coding region expressed in 3 of the patients but not in the healthy control. The variations with high allele frequencies in Taiwanese population were excluded. Five potential candidates, KMT2D, PCDHA8, COG5, RAPGEF3 and PFDN1, were identified as heterozygous mutations predisposed to endometrial cancer. In addition, we demonstrated that PCDHA8 and COG5 genes play crucial roles in cell proliferation in endometrial cancer cells. Notably, KMT2D (lysine methyltransferase 2D) is highly mutated in the tumors of endometrial cancer. An interaction between mutated KMT2D and other candidate genes may explain the high risk of cancer formation in this family. These results validate the potential markers of endometrial cancer and create opportunities for therapeutic applications and personalized prevention. Citation Format: Yu-Cheh Chiang, Ting-Fang Lee, Yung-Feng Lin, Hui-Ying Weng, Shih-Feng Tsai, Cheng-Wen Wu. Identify the predisposition genes to endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4168.

Neonatal Kabuki syndrome: a report of two cases

This paper reported the diagnosis and treatment of two neonates with Kabuki syndrome (KS). Neither of them had typical facial features of KS during the neonatal period, but poor response, abnormal appearance and multiple organ dysplasia were observed in both. Case 1 was lost to follow up after discharge, while typical KS facial features were gradually appeared in Case 2 including eversion of lower lateral eyelids, arched eyebrows, sparse eyebrow arch, flattened nasal tip, prominent ears, during a three-month follow-up after birth. Next-generation sequencing revealed that both neonates were KS caused by lysine methyltransferase 2D (KMT2D) gene mutation, of which case 1 had a heterozygous deletion mutation of c.13895delC (p.P4632HfsTer8) in KMT2D gene, while case 2 had a heterozygous repeat mutation of c.12809dupA (p.T4271Dfs*63) in KMT2D gene. Both cases were defined as de novo mutations and the one carried by case 2 was a newly discovered pathogenic mutation. Key words: Abnormalities, multiple; Face; Hematologic diseases; Vestibular diseases; DNA-binding proteins; Neoplasm proteins; Infant, newborn

Mutation of chromatin regulators and focal hotspot alterations characterize human papillomavirus-positive oropharyngeal squamous cell carcinoma.

Human papillomavirus (HPV)-associated oropharyngeal cancer is a disease clinically and biologically distinct from smoking-related head and neck squamous cell carcinoma (HNSCC). Despite its rapidly increasing incidence, the mutational landscape of HPV+ oropharyngeal squamous cell carcinoma (OPSCC) remains understudied. This article presents the first mutational analysis of the 46 HPV+ OPSCC tumors within the newly expanded cohort of 530 HNSCC tumors from The Cancer Genome Atlas. A separate exome sequencing analysis was also performed for 46 HPV+ OPSCCs matched to their normal lymphocyte controls from the Johns Hopkins University cohort. There was a strikingly high 33% frequency of mutations within genes associated with chromatin regulation, including mutations in lysine methyltransferase 2C (KMT2C), lysine methyltransferase 2D (KMT2D), nuclear receptor binding SET domain protein 1 (NSD1), CREB binding protein (CREBBP), E1A-associated protein p300 (EP300), and CCCTC-binding factor (CTCF). In addition, the commonly altered genes phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA) and fibroblast growth factor receptor 3 (FGFR3) showed distinct domain-specific hotspot mutations in comparison with their HPV- counterparts. PIK3CA showed a uniquely high rate of mutations within the helicase domain, and FGFR3 contained a predominance of hotspot S249C alterations that were not found in HPV- HNSCC. This analysis represents one of the largest studies to date of HPV+ OPSCC and lends novel insight into the genetic landscape of this biologically distinct disease, including a high rate of mutations in histone- and chromatin-modifying genes, which may offer novel therapeutic targets.

Lysine methyltransferase 2D regulates pancreatic carcinogenesis through metabolic reprogramming

ObjectiveDespite advances in the identification of epigenetic alterations in pancreatic cancer, their biological roles in the pathobiology of this dismal neoplasm remain elusive. Here, we aimed to characterise the functional...

Downregulation of KMT2D suppresses proliferation and induces apoptosis of gastric cancer

PurposeHistone lysine methyltransferase 2D (KMT2D/MLL2) is a known cancer-related protein; however, its function in gastric cancer (GC) remains uncharacterized. The present study sought to investigate the expression pattern and the role of KMT2D in GC. MethodsThe expression of KMT2D were evaluated at mRNA and protein levels, while its clinico-pathological value were further explored. GC cells were transfected with KMT2D knockdown siRNAs or lentiviruses, and then detected by cell counting kit-8, plate clone formation, cell apoptosis, cycle, migration, invasion, and tumorigenesis assays. ResultsOverexpression of KMT2D was observed in GC samples, and was strongly associated with poor survival. Depletion of KMT2D suppressed cell proliferation and induced apoptosis. ConclusionOur study demonstrated the upregulation of KMT2D in GC tissue, and KMT2D modulates proliferation and apoptosis in GC. Therefore, KMT2D might represent a novel oncogene for prognosis and optimal treatment of GC patients.

Abstract 5845: Roles for MLL2/ KMT2D or MLL3/ KMT2C in HER+ breast cancer stem cells

Abstract A major clinical challenge for the treatment of breast cancer (BC) is drug resistance. Cancer stem cells (CSCs) may contribute to drug resistance despite therapy. The HER2-positive subtype of BC contains a gene amplification for the ERBB2 proto-oncogene and these tumors are treated with anti-HER2 therapy. Anti-HER2 therapy, such as trastuzumab or lapatinib, increases Notch signaling and is required for HER2+ breast tumor resistance and tumor recurrence. Notch promotes survival of BC CSCs cells. MLL2/KMT2D (Lysine Methyltransferase 2D) and MLL3/KMT2C (Lysine Methyltransferase 2C) are histone methyltransferases that directly control gene enhancer activity through methylation of histone3 lysine4 within enhancer nucleosomes. These complexes collaborate with transcription factors, such as Notch, to drive gene expression by helping to shape the epigenetic landscape of a cell. Recently, it was shown that lapatinib or a PI3K inhibitor increases MLL2 activity and this increase in MLL2 contributes to resistance. Both MLL2 and MLL3 were found to be required for CSCs differentiation, while MLL2 was required for upregulation of c-Myc in HER2+ cells. Recent breast cancer xeno-engraftment studies found that clonal selection and expansion of primary and metastatic breast tumors was associated with amplification of MLL3 in 80% of breast cancer xenografts, suggesting that increased MLL3 expression may contribute to the survival of CSCs in breast tumors. High expression of MLL2 and/or MLL3 predict poor outcome for women with HER2+ breast cancer from cBio portal and Kaplan-Meier Plotter datasets. We measured the expression levels of MLL2 and MLL3 transcripts in both bulk HER2+ breast cancer cells that are trastuzumab sensitive, cells that have acquired resistance to trastuzumab, and cancer stem-enriched mammospheres. Results from PCR analysis showed that MLL2 and MLL3 transcripts were increased in mammospheres compared to bulk cells. Mammosphere forming efficiency of trastuzumab sensitive cells was decreased when MLL2 or MLL3 was knocked down using RNAi. Mammosphere forming efficiency of anti-HER2 therapy resistant (BT474 TR) cells was significantly decreased upon MLL3 knockdown, while HCC1954 mammospheres were inhibited by either MLL2 or MLL3 knockdown. We next measured transcript levels of Notch genes and other stem, mesenchymal, and luminal genes to determine whether MLL2 or MLL3 is necessary for the proper expression of cell fate genes. We found that Notch3 transcripts were decreased in both BT474 and HCC1954 cells upon MLL2 knockdown. SNAIL and Notch1 transcripts were also decreased, suggesting that MLL2 is required for the expression of genes involved in regulating cancer stem cell fates. These results suggest that MLL2/KMT2D and its paralog MLL3/KMT2C are increased in CSCs-derived from HER2+ breast cancer and may regulate CSC genes such Notch1 and Notch3 to promote resistance to anti-HER2 based therapy. Citation Format: Andrei Zlobin, Debra Wyatt, Mary Varsanik, Andrew Dingwall, Clodia Osipo.. Roles for MLL2/ KMT2D or MLL3/ KMT2C in HER+ breast cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5845.

Histiocytic sarcoma: New insights into FNA cytomorphology and molecular characteristics.

Histiocytic sarcoma (HS) is a rare malignant neoplasm showing morphologic and immunophenotypic features of histiocytes. Molecular characteristics of HS and fine-needle aspiration (FNA) criteria for its diagnosis have not been established. A case series of HS in 8 FNA samples from 6 patients was reviewed along with histopathologic and clinical data. Immunohistochemistry was performed on cell blocks (3 cases), core biopsies (5 cases), and surgical specimens (4 cases). Targeted-exome next-generation sequencing (NGS) was performed on surgical resection specimens in 4 cases. Four patients had a known history of hematolymphoid malignancy. Cytomorphologic features included variably cellular smears composed of large epithelioid cells with reniform nuclei and abundant vacuolated cytoplasm, in an inflammatory background, with occasional cytophagocytosis and lymphoglandular bodies. Marked pleomorphism, multinucleated monster cells, and binucleated histiocytoid cells with partially overlapping, eccentrically placed nuclei resembling Pac-Man were common. Most cases expressed histiocytic markers CD68 (6 of 7 cases), CD163 (5 of 5 cases), and PU.1 (3 of 4 cases). In 3 cases, NGS analysis revealed alterations in lysine methyltransferase 2D (KMT2D)/mixed-lineage leukemia 2 (MLL2), a gene involved in chromatin regulation and previously implicated in the pathogenesis of follicular lymphoma. Although diagnosing HS with FNA alone is extremely challenging, the presence of pleomorphic and epithelioid large cells with binucleation and/or multinucleation in an inflammatory background should prompt the diagnosis of HS with judicious use of confirmatory histiocytic lineage markers. The detection of recurrent KMT2D/MLL2 alterations implicates epigenetic regulation in the pathogenesis of HS and supports the notion of transdifferentiation from a genetically similar but phenotypically distinct tumor of a different lineage. Cancer Cytopathol 2017;125:604-14. © 2017 American Cancer Society.

Small Cell Lung Cancer Exhibits Frequent Inactivating Mutations in the Histone Methyltransferase KMT2D/MLL2: CALGB 151111 (Alliance)

IntroductionSCLC is a lethal neuroendocrine tumor type that is highly prone to metastasis. There is an urgency to understand the mutated genes that promote SCLC, as there are no approved targeted therapies yet available. SCLC is rarely resected, limiting the number of samples available for genomic analyses of somatic mutations. MethodsTo identify potential driver mutations in human SCLC we sequenced the whole exomes of 18 primary SCLCs and seven cell lines along with matched normal controls. We extended these data by resequencing a panel of genes across 40 primary SCLCs and 48 cell lines. ResultsWe report frequent mutations in the lysine methyltransferase 2D gene (KMT2D) (also known as MLL2), a key regulator of transcriptional enhancer function. KMT2D exhibited truncating nonsense/frameshift/splice site mutations in 8% of SCLC tumors and 17% of SCLC cell lines. We found that KMT2D mutation in human SCLC cell lines was associated with reduced lysine methyltransferase 2D protein levels and reduced monomethylation of histone H3 lysine 4, a mark associated with transcriptional enhancers. We also found mutations in other genes associated with transcriptional enhancer control, including CREB binding protein gene (CREBBP), E1A binding protein p300 gene (EP300), and chromodomain helicase DNA binding protein 7 gene (CHD7), and we report mutations in additional chromatin remodeling genes such as polybromo 1 gene (PBRM1). ConclusionsThese data indicate that KMT2D is one of the major mutated genes in SCLC, and they point to perturbation of transcriptional enhancer control as potentially contributing to SCLC.

Differential mutation frequencies in metastatic cutaneous squamous cell carcinomas versus primary tumors.

Exome and targeted sequencing studies have identified potential driver mutations for a variety of tumor types. Cutaneous squamous cell carcinoma (cSCC) is one of the most highly mutated cancers but typically is associated with low rates of metastasis and high survival rates. Nevertheless, metastatic cSCC is a significant health threat; up to 8800 individuals die each year of this disease. Because it is difficult to predict which cSCCs are more likely to metastasize, and because to the best of the authors' knowledge there are no targeted therapies specifically designated for patients with metastatic cSCC, exome and/or targeted sequencing of 18 metastatic and 10 primary cSCCs was performed to identify mutations that were more frequent in metastatic tumors and might be targeted for therapeutic benefit. The authors compared their results with published sequencing results of an additional 223 primary tumors and 68 metastatic cSCCs. The authors identified genes demonstrating higher mutation frequencies in metastatic cSCC compared with primary tumors, including the chromatin remodeling gene lysine methyltransferase 2D (KMT2D) and the classic skin tumor suppressor tumor protein p53 (TP53), which was found to be mutated in 54% of primary tumors compared with 85% of metastatic tumors (P<.0001). These studies appear to uncover potential pathways that are important in metastatic cSCC and that broaden understanding of the biology contributing to aggressive tumor behavior. These results may lead to new therapeutic strategies. Cancer 2017;123:1184-1193. © 2016 American Cancer Society.

Clinical and genetic determinants of ovarian metastases from colorectal cancer.

Ovarian metastases from colorectal cancer (OM-CRC) often are unresponsive to chemotherapy and are associated with poor survival. To the authors' knowledge, the clinicopathologic and genomic predictors of OM-CRC are poorly characterized and optimal clinical management remains unclear. Women with a histopathological diagnosis of OM-CRC who were treated at Memorial Sloan Kettering Cancer Center from 1999 to 2015 were identified. Next-generation somatic mutation profiling (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets [MSK-IMPACT]) was performed on 38 OM-CRC cases, including 21 matched tumor pairs/trios. Regression models were used to analyze variables associated with progression-free survival and overall survival (OS). Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), SMAD family member 4 (SMAD4), and neurotrophic receptor tyrosine kinase 1 (NTRK1) mutations were more frequent in cases of OM-CRC than in instances of CRC occurring without OM. SMAD4 and lysine methyltransferase 2D (KMT2D) mutations were associated with reduced OS. Matched multisite tumor sequencing did not identify OM-specific genomic alterations. Of the 195 patients who underwent oophorectomy for OM-CRC (median age, 49 years with a progression-free survival of 9.4 months and an OS of 23 months from oophorectomy), 76% had extraovarian metastasis (EOM). In multivariable analysis, residual disease after surgery (R2 resection) was associated with worse survival. Patients with EOM were less likely to achieve R0/R1 surgical resection status (complete macroscopic resection without clinical/radiological evidence of disease) (48% vs 94%). However, if R0/R1 resection status was achieved, both patients with (35.9 months vs 12 months) and without (43.2 months vs 14.5 months) EOM were found to have better OS. Among 114 patients with R0/R1 resection status, 23 (20%) had no disease recurrence, including 10 patients (9%) with > 3 years of follow-up. Loss-of-function alterations in SMAD4 are frequent and predictive of worse survival in patients with OM-CRC. Similar to oligometastatic CRC to the lung or liver, surgical resection of OM-CRC is associated with a better outcome only if all macroscopic metastatic disease is resected. Cancer 2017;123:1134-1143. © 2016 American Cancer Society.

Defects of B-cell terminal differentiation in patients with type-1 Kabuki syndrome

Kabuki syndrome (KS) is a complex multisystem developmental disorder associated with mutation of genes encoding histone-modifying proteins. In addition to craniofacial, intellectual, and cardiac defects, KS is also characterized by humoral immune deficiency and autoimmune disease, yet no detailed molecular characterization of the KS-associated immune phenotype has been reported. We sought to characterize the humoral immune defects found in patients with KS with lysine methyltransferase 2D (KMT2D) mutations. We comprehensively characterized B-cell function in a cohort (n=13) of patients with KS (age, 4months to 27years). Three quarters (77%) of the cohort had a detectable heterozygous KMT2D mutation (50% nonsense, 20% splice site, and 30% missense mutations), and 70% of the reported mutations are novel. Among the patients with KMT2D mutations (KMT2D(Mut/+)), hypogammaglobulinemia was detected in all but 1 patient, with IgA deficiency affecting 90% of patients and a deficiency in at least 1 other isoform seen in 40% of patients. Numbers of total memory (CD27(+)) and class-switched memory B cells (IgM(-)) were significantly reduced in patients with KMT2D(Mut/+) mutations compared with numbers in control subjects (P<.001). Patients with KMT2D(Mut/+) mutations also had significantly reduced rates of somatic hypermutation in IgG (P=.003) but not IgA or IgM heavy chain sequences. Impaired terminal differentiation was noted in primary B cells from patients with KMT2D(Mut/+) mutations. Autoimmune pathology was observed in patients with missense mutations affecting the SET domain and its adjacent domains. In patients with KS, autosomal dominant KMT2D mutations are associated with dysregulation of terminal B-cell differentiation, leading to humoral immune deficiency and, in some cases, autoimmunity. All patients with KS should undergo serial clinical immune evaluations.