Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited syndrome. MEN1 is characterized by the presence of functioning and nonfunctioning tumors or hyperplasia of the pituitary gland, parathyroid glands, and pancreatic islet cells. In addition, MEN1 carriers can have adrenal or thyroid tumors and non-endocrine tumors, such as lipomas, angiofibromas, and leiomyomas. Although leiomyoma is not a major component of MEN1, it is thought to occur more frequently than expected. However, there has been no report of a case of MEN1 with leiomyoma in Korea so far. This report describes a patient with multiple leiomyomas in MEN1. A 50-year-old woman was referred for further evaluation of elevated calcium levels and osteoporosis. Biochemical abnormalities included hypercalcemia with elevated parathyroid hormone. There was hyperprolactinemia with pituitary microadenoma in sella MRI. An abdominal MRI demonstrated adrenal nodules and leiomyomas in the bladder and uterus. Endoscopic ultrasonography demonstrated esophageal leiomyoma and pancreatic islet cell tumor. A subtotal parathyroidectomy with thymectomy was performed. Sequencing of the MEN1 gene in this patient revealed a novel missense mutation (D350V, exon 7). This is the first case of MEN1 accompanied with multiple leiomyomas, parathyroid adenoma, pituitary adenoma, pancreatic tumor, and adrenal tumor.
Base Sequence ; Female ; Humans ; Leiomyomatosis/genetics/*metabolism/*pathology/radiography ; Magnetic Resonance Imaging ; Middle Aged ; Multiple Endocrine Neoplasia Type 1/genetics/*metabolism ; Mutation/genetics

Multiple endocrine neoplasia type 1 (MEN1) is a dominantly inherited tumor syndrome characterized by development of various combinations of tumors in multiple endocrine glands, including the pituitary, parathyroid or pancreas. MEN1 results from mutations in tumor suppressor gene Men1, which encodes nuclear protein menin. Menin has been shown to preferentially repress cell proliferation in endocrine tissues including pancreatic beta cells. Herein, the present study was to explore the potential mechanisms underlying menin in repressing cell proliferation in mice MEN1 insulinoma. In the Gene Set Enrichment Analysis (GSEA), Ccnb2 (encoding cyclin B2) was up-regulated in pancreatic islets of Men1-excised mice after 14-day tamoxifen-feeding. Immunofluorescence with antibody against cyclin B2 revealed that the expression of cyclin B2 was greatly increased in MEN1 insulinoma. In Men1(-/-) cells, Men1 ablation leaded to an increase in cyclin B2 expression. Immunofluorescent staining by phospho-H3S10 antibody revealed the increasing number of Men1(-/-) cells in mitosis. Cells were seeded at a density of 5 × 10(4), then counted on day 2, 4 and 6, and the cell growth curve revealed Men1 ablation increased the cell proliferation. In contrast, knockdown of cyclin B2 by shRNA diminished the number of cells in mitosis and reduced cell proliferation. Further, chromatin immunoprecipitation (ChIP) assay indicated that menin affected the histone modification of the promoter of Ccnb2 by reducing the level of histone H3 lysine 4 tri-methylation (H3K4me3) and histone H3 acetylation but not affecting the level of histone H3 lysine 9 tri-methylation (H3K9me3) or histone H3 lysine 27 tri-methylation (H3K27me3). Our results suggest that menin may inhibit MEN1 insulinoma by suppressing cyclin B2 expression via histone modification.
Animals ; Cell Proliferation ; Cyclin B2 ; genetics ; metabolism ; Histones ; metabolism ; Insulinoma ; metabolism ; pathology ; Mice ; Mice, Knockout ; Multiple Endocrine Neoplasia Type 1 ; genetics ; Mutation ; Pancreatic Neoplasms ; metabolism ; pathology ; Proto-Oncogene Proteins ; genetics

BACKGROUNDMenin is a ubiquitously expressed protein encoded by the multiple endocrine neoplasia type 1 (MEN1) gene. Besides its importance in endocrine organs, menin has been shown to interact with the mixed lineage leukemia (MLL) protein, a histone H3 lysine 4 methyltransferase, and plays a critical role in hematopoiesis and leukemogenesis. Previous studies have shown that menin promotes transforming growth factor beta (TGF-β) signaling in endocrine cells. However, little is known regarding the impact of TGF-β pathway on menin in hematopoietic system. Here, with leukemia cell lines generated from conditional MEN1 or TGF-β receptor (TβRII) knockout mouse models, we investigated the possible cross-talk of these two pathways in leukemia cells.

METHODSMEN1 or TβRII conditional knockout mice were bred and the bone marrow cells were transduced with retroviruses expressing oncogeneic MLL-AF9 (a mixed lineage leukemia fusion protein) to generate two leukemia cell lines. Cell proliferation assays were performed to investigate the effect of TGF-β treatment on MLL-AF9 transformed leukemia cells with/without MEN1 or TβRII excision. Menin protein was detected with Western blotting and mRNA levels of cell proliferation-related genes Cyclin A(2) and Cyclin E(2) were examined with real-time RT-PCR for each treated sample. In vivo effect of TGF-β signal on menin expression was also investigated in mouse liver tissue after TβRII excision.

RESULTSTGF-β not only inhibited the proliferation of wild type MLL-AF9 transformed mouse bone marrow cells, but also up-regulated menin expression in these cells. Moreover, TGF-β failed to further inhibit the proliferation of Men1-null cells as compared to Men1-expressing control cells. Furthermore, excision of TβRII, a vital component in TGF-β signaling pathway, down-regulated menin expression in MLL-AF9 transformed mouse bone marrow cells. In vivo data also confirmed that menin expression was decreased in liver samples of conditional TβRII knockout mice after TβRII excision.

CONCLUSIONThese results provided the first piece of evidence of cross-talk between menin and TGF-β signaling pathways in regulating proliferation of leukemia cells, suggesting that manipulating the cross-talk of the two pathways may lead to a novel therapy for leukemia.

Animals ; Blotting, Western ; Cells, Cultured ; Humans ; Leukemia ; metabolism ; Mice ; Mice, Knockout ; Multiple Endocrine Neoplasia Type 1 ; genetics ; metabolism ; Oncogene Proteins, Fusion ; genetics ; metabolism ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction ; Receptors, Transforming Growth Factor beta ; genetics ; metabolism ; Transforming Growth Factor beta ; genetics ; metabolism

TCR signaling leading to thymocyte apoptosis is mediated through the expression of the Nur77 family of orphan nuclear receptors. It has been shown that the Nur77 promoter is activated by at least two signaling pathways, one mediated by calcium and the other by protein kinase C (PKC). MEF2D has been known to regulate Nur77 expression in a calcium- dependent manner. The mechanism by which calcium regulates MEF2D is through dissociation of calcium-sensitive MEF2 corepressors (Cabin1/ HDACs, HDAC4/5) and the association with calcineurin-activated transcription factor NF-AT and the coactivator p300. However, little is known about how PKC activates the Nur77 promoter. Herein, we report that PKC theta targets AP-1 like response element in the Nur77 promoter where JunD constitutively binds. PKC theta triggers mitogen-activated protein kinase- inediated phosphorylation of JunD, and increases transcriptional activity of JunD, cooperatively with p300. Menin is identified as the transcriptional corepressor for JunD via recruitment of mSin3-istone deacetylases. In fact, Menin represses PKC theta/ p300-mediated transcriptional activity of JunD in T cell. Its dynamic regulation of histone modifiers with JunD is responsible for PKCq-synergistic effect on Nur77 expression in T cell.
Cell Line, Tumor ; DNA-Binding Proteins/*genetics ; Enzyme Activation ; *Gene Expression Regulation ; Humans ; Isoenzymes/*metabolism ; Mitogen-Activated Protein Kinases/metabolism ; *Multiple Endocrine Neoplasia Type 1 ; Promoter Regions (Genetics)/genetics ; Protein Kinase C/*metabolism ; Proto-Oncogene Proteins/genetics/*metabolism ; Proto-Oncogene Proteins c-jun/*antagonists & inhibitors/metabolism ; Receptors, Cytoplasmic and Nuclear/*genetics ; Receptors, Steroid/*genetics ; Research Support, Non-U.S. Gov't ; Response Elements ; Transcription Factors/*genetics ; Transcription, Genetic/*genetics