UDP-glucose, cereblon-dependent proinsulin degrader.

Insulin secretion is regulated in multiple steps, and one of the main steps is in the endoplasmic reticulum (ER). Here, we show that UDP-glucose induces proinsulin ubiquitination by cereblon, and uridine binds and competes for proinsulin degradation and behaves as sustainable insulin secretagogue. Using insulin mutagenesis of neonatal diabetes variant-C43G and maturity-onset diabetes of the young 10 (MODY10) variant-R46Q, UDP-glucose:glycoprotein glucosyltransferase 1 (UGGT1) protects cereblon-dependent proinsulin ubiquitination in the ER. Cereblon is a ligand-inducible E3 ubiquitin ligase, and we found that UDP-glucose is the first identified endogenous proinsulin protein degrader. Uridine-containing compounds, such as uridine, UMP, UTP, and UDP-galactose, inhibit cereblon-dependent proinsulin degradation and stimulate insulin secretion from 3 to 24 h after administration in ß-cell lines as well as mice. This late and long-term insulin secretion stimulation is designated a day sustainable insulin secretion stimulation. Uridine-containing compounds are designated as proinsulin degradation regulators.

UDP-Glucose: A Cereblon-Dependent Glucokinase Protein Degrader.

We previously reported that glucokinase is ubiquitinated and degraded by cereblon with an unknown endogenous glucokinase protein degrader. Here, we show that UDP-glucose is a glucokinase protein degrader. We identified that both glucose and UDP-glucose bind to glucokinase and that both uridine and UDP-glucose bind to cereblon in a similar way to thalidomide. From these results, UDP-glucose was identified as a molecular glue between cereblon and glucokinase. Glucokinase produces glucose-6-phosphate in the pancreas and liver. Especially in ß-cells, glucokinase is the main target of glucose for glucose-induced insulin secretion. UDP-glucose administration ubiquitinated and degraded glucokinase, lowered glucose-6-phosphate production, and then reduced insulin secretion in ß-cell lines and mice. Maturity-onset diabetes of the young type 2 (MODY2) glucokinaseE256K mutant protein was resistant to UDP-glucose induced ubiquitination and degradation. Taken together, glucokinase ubiquitination and degradation signaling might be impaired in MODY2 patients.

Decidualization Differentially Regulates microRNA Expression in Eutopic and Ectopic Endometrial Stromal Cells.

Decidualization of the endometrium and endometriosis involves the morphological and biochemical reprogramming of the estrogen-primed proliferative stromal compartment under the continuing influence of progesterone. Here, we evaluated the involvement of microRNA in the decidualization processes of normal endometrial stromal cells (NESCs) and endometriotic cyst stromal cells (ECSCs). In vitro decidualization of NESCs and ECSCs was induced by long-term culture with a combination of 0.5 mmol/L of dibutyryl cyclic adenosine monophosphate and 100 nmol/L of dienogest. We investigated the effect of in vitro decidualization on the microRNA and messenger RNA (mRNA) expression profiles of the NESCs and ECSCs using global microarray techniques and an Ingenuity Pathways Analysis. Decidualization differentially enhanced the miR-30a-5p expression in the NESCs and the miR-210 expression in the ECSCs. The enhanced miR-30a-5p expression in the NESCs correlated with the increased mRNA expression of Krüppel-like factor 9 and period circadian clock 3 as well as the decreased mRNA expression of tolloid-like 1, tolloid-like 2, and paired-like homeodomain 1. The enhanced expression of miR-210 in the ECSCs correlated with the decreased mRNA expression of growth hormone receptor and thymidine kinase 1. Although there is no direct evidence, we speculate that the loss of miR-30a-5p-mediated mechanisms of decidualization and the acquisition of miR-210-mediated mechanisms of decidualization may be involved in the progesterone resistance in endometriosis. Further investigations are necessary to test this speculation.

miR-503, a microRNA epigenetically repressed in endometriosis, induces apoptosis and cell-cycle arrest and inhibits cell proliferation, angiogenesis, and contractility of human ovarian endometriotic stromal cells.

STUDY QUESTION: Is the micro-RNA (miRNA) miR-503, downregulated in endometriotic cyst stromal cells (ECSCs) and does this affect the cell cycle, cell proliferation, angiogenesis and contractility of these cells? SUMMARY ANSWER: miR-503 expression is downregulated in ECSCs by DNA hypermethylation and this contributes to their proliferation, resistance to apoptosis, extracellular matrix (ECM) contractility and angiogenesis through effects on cyclin D1, B-cell lymphoma/leukemia (Bcl)-2, Ras homology A  and vascular endothelial growth factor A (VEGF-A). WHAT IS KNOWN ALREADY: A variety of miRNAs are demonstrated to involve in the pathogenesis of endometriosis. miR-503 is a miRNA with tumor-suppressor functions, whose expression is suppressed in ECSCs. STUDY DESIGN, SIZE, DURATION: We isolated ECSCs and normal endometrial stromal cells (NESCs) from ovarian endometriotic tissues (n = 32) and eutopic endometrial tissues without endometriosis (n = 8), respectively. PARTICIPANTS/MATERIALS, SETTING, METHODS: We investigated the functions of miR-503 by using miR-503-transfected ECSCs and the DNA methylation status of miR-503 gene in ECSCs and NESCs by combined bisulfite restriction analysis. MAIN RESULTS AND THE ROLE OF CHANCE: In ECSCs, miR-503 is downregulated by the DNA hypermethylation of its gene. The transfection of miR-503 into ECSCs resulted in the inhibition of cell proliferation and induction of cell-cycle arrest at G0/G1 phase through the suppression of cyclin D1, the induction of apoptosis through Bcl-2 suppression, the inhibition of VEGF-A production and the attenuation of ECM contractility via the suppression of Rho/Rho-associated coiled-coil-forming protein kinase-pathways. LARGE SCALE DATA: NA. LIMITATIONS, REASONS FOR CAUTION: The present experiments were carried out only with the stromal component of endometriosis and eutopic endometrium. The experiments with the eutopic endometrial stromal cells from women with endometriosis are not performed. WIDER IMPLICATIONS OF THE FINDINGS: Our findings indicate that epigenetically repressed miR-503 in ECSCs is involved in the acquisition of endometriosis-specific cellular functions. STUDY FUNDING/COMPETING INTERESTS: This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (no. 13237327 to K.N., no. 26861335 to K.K. and no. 23592407 to H.N.) and the Kanzawa Medical Research Foundation (to K.K.). There are no conflicts of interest to declare.

Aberrant histone modification in endometriosis.

Accumulating evidence suggests that epigenetic aberrations play definite roles in the pathogenesis of endometriosis. These include aberrations in genomic DNA methylation, microRNA expression, and histone modification. The aberrant histone modification status and the aberrant expression of histone deacetylases, which regulate histone acetylation, in endometriosis are the focus of this review. Herein, we summarize the recent studies in the following areas: (i) hyperacetylation of histones located in the promoter lesions of G-protein-coupled estrogen receptor 1, steroidogenic factor-1, and hypoxia-inducible factor-1 alpha genes and (ii) hypoacetylation of histones located in the promoter lesions of estrogen receptor alpha, homeobox A10, CCAAT/enhancer-binding protein alpha, p16(INK4a), p21(Waf1/Cip1), p27(Kip1), checkpoint kinase 2, death receptor 6, and E-cadherin genes. Further research from the viewpoint of epigenetics may lead to the identification of the candidate molecules that are aberrantly expressed in endometriosis and may help elucidate the pathogenesis of this disease. In addition, epigenetic drugs (including histone deacetylase inhibitors) show promise for the treatment of endometriosis by amending the expression of these epigenetically dysregulated genes.

Death receptor 6 is epigenetically silenced by histone deacetylation in endometriosis and promotes the pathogenesis of endometriosis.

PROBLEM: The purpose of this study is to evaluate the involvement of death receptor (DR) 6 in the pathogenesis of endometriosis. METHODS OF STUDY: Endometriotic cyst stromal cells (ECSCs) and normal endometrial stromal cells (NESCs) were isolated from ovarian endometriotic tissues and the eutopic endometrial tissues, respectively. The effect of valproic acid (VPA) on the DR6 expression in ECSCs was examined. The roles of DR6 in NESC proliferation and apoptosis were investigated with DR6 siRNA transfection. The distribution of DR6 protein in ovarian endometriotic tissues and normal proliferative-phase endometrium was examined by immunohistochemistry. The expression of DR6 mRNA and protein in ECSCs and NESCs was also examined. RESULTS: Death receptor 6 expression was attenuated in ECSCs and in endometriotic tissues, and its expression was upregulated by VPA stimulation. VPA treatment resulted in an accumulation of acetylated histone H4 in the promoter region of the DR6 gene. DR6 knockdown directed the stimulation of cell proliferation and the resistance to apoptosis in NESCs. CONCLUSION: The present findings suggested that DR6 is involved in the pathogenesis of endometriosis by creating the proliferative and anti-apoptotic characteristics of endometriosis. The results also suggest that histone deacetylase inhibitors are promising agents for the treatment of endometriosis.

CCAAT/enhancer-binding protein α is epigenetically silenced by histone deacetylation in endometriosis and promotes the pathogenesis of endometriosis.

CONTEXT: Accumulating evidence suggests that various epigenetic aberrations play definite roles in the pathogenesis of endometriosis. OBJECTIVE: The objective of the study was to determine the epigenetically silenced genes by histone deacetylation in endometriosis. DESIGN: Histone deacetylase-1 target mRNAs that were up-regulated by valproic acid (VPA) treatment in endometriotic cyst stromal cells (ECSCs) were identified by a global mRNA microarray technique. RESULTS: We identified 5 candidate genes and chose CCAAT/enhancer-binding protein α (C/EBPα) for further functional experiments. C/EBPα mRNA and protein expression is attenuated in ECSCs, and the expression was up-regulated by VPA stimulation. Immunohistochemical stainings also confirmed the decreased staining for C/EBPα protein in endometriotic tissues. VPA treatment resulted in an accumulation of acetylated histones H3 and H4 in the promoter region of the C/EBPα gene in ECSCs. The compulsory expression of C/EBPα in ECSCs directed the inhibition of cell proliferation and the induction of apoptosis. C/EBPα knockdown by small interfering RNA directed the stimulation of cell proliferation and the resistance to apoptosis in normal eutopic endometrial stromal cells. The expressions of peroxisome proliferator-activated receptor-γ (PPARγ), period homolog 2 (PER2), p53, apoptosis-inducing factor, mitochondrion-associated 1 (AIFM1), Bax, caspase-8, caspase-10, p16(INK4a), p21(Waf1/Cip1), cyclin-dependent kinase (cdk) 2, and cdk4 were down-regulated by C/EBPα knockdown. CONCLUSIONS: Our findings suggest that an epigenetically suppressed tumor suppressor gene is involved in the pathogenesis of endometriosis by creating the proliferative, antiapoptotic, and other disease-specific characteristics of endometriosis. The results also suggest that histone deacetylase inhibitors are promising agents for the treatment of endometriosis.

miR-196b targets c-myc and Bcl-2 expression, inhibits proliferation and induces apoptosis in endometriotic stromal cells.

STUDY QUESTION: What is the global expression pattern of microRNAs (miRNAs) in endometriotic stromal cells and is miR-196b involved in the pathogenesis of endometriosis? SUMMARY ANSWER: Several miRNAs are aberrantly expressed in endometriotic cyst stromal cells (ECSCs), including miR-196b whose expression is repressed in endometriotic stromal cells. WHAT IS KNOWN ALREADY: Although, histologically, endometriotic tissues and normal proliferative endometrium are similar, a number of distinct molecular differences have been reported to date. The anti-apoptotic and excessive proliferative properties of endometriotic cells are considered to be involved in the development and progression of endometriosis. STUDY DESIGN AND SIZE DURATION: ECSCs and normal endometrial stromal cells (NESCs) were isolated from ovarian endometriotic tissues and eutopic endometrial tissues, respectively and compared. PARTICIPANTS/MATERIALS, SETTING AND METHODS: Aberrantly expressed miRNAs in ECSCs were identified by a global miRNA microarray technique. The roles of miR-196b in ECSC proliferation, apoptosis, and c-myc and B-cell lymphoma/leukemia (Bcl)-2 mRNA expression were investigated with precursor hsa-miR-196b transfection. The methylation status of the miR-196b gene in ECSCs and the effect of a DNA demethylating agent on miR-196b expression were also examined. MAIN RESULTS AND THE ROLE OF CHANCE: miRNA microarray analysis identified eight down-regulated miRNAs (including miR-196b) and four up-regulated miRNAs in ECSCs. Compulsory expression of miR-196b directed the inhibition of proliferation and the induction of apoptosis in ECSCs. miR-196b was found to suppress c-myc and Bcl-2 mRNA expression in ECSCs, and there was a significant correlation between miR-196b and HOXA10 expression in ECSCs and NESCs. The miR-196b gene was hypermethylated in ECSCs when compared with NESCs, and the treatment with a DNA demethylating agent restored the expression of miR-196b in ECSCs. LIMITATIONS AND REASONS FOR CAUTION: miRNA expression profiles were investigated only in the stromal component of ectopic and eutopic endometrium samples. In addition to miR-196b, the roles of other miRNAs aberrantly expressed in ECSCs should be examined. WIDER IMPLICATIONS OF THE FINDINGS: The present findings suggest that aberrant miRNA expression plays an important role in the pathogenesis of endometriosis as a part of epigenetic mechanisms, that expression of miR-196b in ECSCs is repressed by DNA hypermethylation of the miR-196b gene and this repression may be involved in the development of proliferative and anti-apoptotic characteristics of endometriosis. STUDY FUNDING: This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (no. 20591920 to K.N. and no. 23592407 to H.N.) and The Uehara Memorial Foundation (to K.N.).

Fasudil inhibits the proliferation and contractility and induces cell cycle arrest and apoptosis of human endometriotic stromal cells: a promising agent for the treatment of endometriosis.

CONTEXT: During the development of endometriotic lesions, excess fibrosis may lead to scarring and to the alterations of tissue function that are the characteristic features of this disease. Enhanced extracellular matrix contractility of endometriotic stromal cells (ECSC) mediated by the mevalonate-Ras homology (Rho)/Rho-associated coiled-coil-forming protein kinase (ROCK) pathway has been shown to contribute to the pathogenesis of endometriosis. DESIGN: To assess the use of fasudil, a selective ROCK inhibitor, for the medical treatment of endometriosis-associated fibrosis, the effects of this agent on the cell proliferation, apoptosis, cell cycle, morphology, cell density, and contractility of ECSC were investigated. The effects of fasudil on the expression of contractility-related, apoptosis-related, and cell cycle-related molecules in ECSC were also evaluated. RESULTS: Fasudil significantly inhibited the proliferation and contractility of ECSC and induced the cell cycle arrest in the G2/M phase and apoptosis of these cells. Morphological observation revealed the suppression of ECSC attachment to collagen fibers and decrease of cell density by fasudil. The expression of α-smooth muscle actin, RhoA, ROCK-I, and ROCK-II proteins was inhibited by fasudil administration. The expression of the antiapoptotic factors, Bcl-2 and Bcl-X(L), in two-dimensional cultured ECSC were down-regulated by the addition of fasudil, whereas, the expression of p16(INK4a) and p21(Waf1/Cip1) was up-regulated by the addition of fasudil. CONCLUSIONS: The present findings suggest that fasudil is a promising agent for the treatment of endometriosis. The inhibition of cell proliferation, contractility, and myofibroblastic differentiation, the attenuation of attachment to collagen fibers, the decrease of cell density, and the induction of cell cycle arrest and apoptosis of ECSC are involved in the active mechanisms of fasudil.

Application of the histone deacetylase inhibitors for the treatment of endometriosis: histone modifications as pathogenesis and novel therapeutic target.

BACKGROUND: Accumulating evidence suggests that various epigenetic aberrations play definite roles in the pathogenesis of endometriosis. We investigated the histone acetylation status in endometriosis and the application of the histone deacetylase inhibitors (HDACIs) for the treatment of endometriosis. METHODS: The levels of acetylated histones in the endometriotic cyst stromal cells (ECSCs) and normal endometrial stromal cells (NESCs) were evaluated. The effects of the HDACIs on cell proliferation, the cell cycle, apoptosis of ECSCs and NESCs, and the expression of genes related to these cellular events were investigated. The effects of HDACIs on histone acetylation in chromatin of the promoter region of the cell cycle regulatory genes in ECSCs were also investigated. RESULTS: The acetylated histone levels were significantly lower in ECSCs than in NESCs (P < 0.025). HDACIs inhibited cell proliferation and induced cell cycle arrest and apoptosis of ECSCs. The effects of HDACIs on NESCs were marginal or weak. These HDACIs induced an accumulation of acetylated histones in total cellular chromatin and in the promoter regions of the p16(INK4a), p21(Waf1/Cip1), p27(Kip1) and cycle checkpoint kinase 2 genes in ECSCs. HDACIs induced the protein expression of these cell cycle regulators and suppressed the protein expression of Bcl-2 and Bcl-X(L) in ECSCs. CONCLUSIONS: The present findings demonstrated that aberrant histone modifications are present in endometriosis and that HDACIs reactivated epigenetically silenced genes, resulting in the suppression of cell proliferation, induction of cell cycle arrest and apoptosis of ECSCs. HDACIs are therefore promising agents for the treatment of endometriosis.

Aberrant DNA methylation status of endometriosis: epigenetics as the pathogenesis, biomarker and therapeutic target.

Endometriosis, a common, benign, estrogen-dependent disease affecting 3-10% of women of reproductive age, is characterized by the ectopic growth of endometrial tissue that is found primarily in the peritoneum, ovaries and rectovaginal septum. Recently, endometriosis has been alternatively described as an immune disease, a genetic disease and a disease caused by exposure to environmental factors, in addition to its usual description as a hormonal disease. In addition, accumulating evidence suggests that various epigenetic aberrations play definite roles in the pathogenesis of endometriosis. Epigenetic alterations reported to date in endometriosis include the genomic DNA methylation of progesterone receptor-B, E-cadherin, homeobox A10, estrogen receptor-ß, steroidogenic factor-1 and aromatase. Aberrant expression of DNA methyltransferases, which attach a methyl group to the 5-carbon position of cytosine bases in the CpG island of the promoter region and silence the corresponding gene expression, has also been demonstrated in endometriosis. This review summarizes the recent studies on the aberrant DNA methylation status and aberrant expression of DNA methyltransferases, which regulate DNA methylation, in endometriosis. We also discuss the recent information on the diagnostic and therapeutic implications of epigenetic alterations occurring in endometriosis.

Aberrant expression of apoptosis-related molecules in endometriosis: a possible mechanism underlying the pathogenesis of endometriosis.

Endometriosis, a disease affecting 3% to 10% of women of reproductive age, is characterized by the ectopic growth of endometrial tissue under the influence of estrogen. It is also becoming recognized as a condition in which ectopic endometrial cells exhibit abnormal proliferative and apoptotic regulation in response to appropriate stimuli. Apoptosis plays a critical role in maintaining tissue homeostasis and represents a normal function to eliminate excess or dysfunctional cells. Accumulated evidence suggests that, in healthy women, endometrial cells expelled during menstruation do not survive in ectopic locations because of programmed cell death, while decreased apoptosis may lead to the ectopic survival and implantation of these cells, resulting in the development of endometriosis. Both the inability of endometrial cells to transmit a "death" signal and the ability of endometrial cells to avoid cell death have been associated with increased expression of antiapoptotic factors and decreased expression of preapoptotic factors. Further investigations may elucidate the role of apoptosis-associated molecules in the pathogenesis of endometriosis. Medical treatment with apoptosis-inducing agents may be novel and promising therapeutic strategy for endometriosis.

Cadmium chloride induces the expression of metallothionein mRNA by endometrial stromal cells and amnion-derived (WISH) cells.

BACKGROUND: Metallothionein (MT) is known to bind to metals with high affinity. The potential for MT-1 mRNA expression in endometrial stromal cells (ESC) and amniotic cells in response to cytokines and cadmium chloride (CdCl(2)) was evaluated. METHODS: Human ESC were cultured and treated with interleukin-1α, 12-O-tetradecanoylphobol 13-acetate (TPA), forskolin, transforming growth factor-ß, and CdCl(2). Amnion-derived (WISH) cells were also cultured and treated with the same reagents. The levels of MT mRNA were evaluated by Northern blot analysis in ESC and WISH cells. RESULTS: In response to treatment with CdCl(2) (0.01-10 µM), the expression of MT mRNA markedly increased in ESC and WISH cells in a dose-dependent manner. On the other hand, the expression of MT mRNA did not increase after treatment with interleukin-1α (1 nM), TPA (10 nM), forskolin (1 µM) or transforming growth factor-ß (1 nM) in these cells. CONCLUSION: These findings indicate that MT expression in ESC and WISH cells is sensitive to the CdCl(2) concentration, which is known to be evaluated in cigarette smokers. The present results suggest that increased levels of MT may affect metal metabolism at the feto-maternal interface.

Impact of positron emission tomography/computed tomography in the management of patients with epithelial ovarian carcinoma after treatment.

PURPOSE: The aims of this study were to compare the usefulness and reliability of integrated whole-body positron emission tomography/computed tomography (PET/CT) using (18)F-fluorodeoxyglucose (FDG) with those of contrast-enhanced multidetector CT during regular follow-up in patients after initial treatment of ovarian cancer, to assess the impact of FDG-PET/CT on the confirmation of recurrence, restaging, and clinical management of patients, and to determine the incremental information provided by PET/CT. METHODS: A retrospective review was performed on 19 ovarian cancer patients who underwent a total of 30 FDG-PET/CT and contrast-enhanced multidetector CT scans. The following information was obtained: the clinical information of the patients; the results of FDG-PET/CT and contrast-enhanced multidetector CT, particularly with regard to the impact on the diagnosis of recurrence; information on the localization and number of diseases; and the impact on subsequent clinical management. RESULTS: Both FDG-PET/CT and contrast-enhanced multidetector CT had very high sensitivity and specificity for the detection of recurrent ovarian cancer. Contrast-enhanced multidetector CT was considered the more accurate imaging modality for detecting recurrence, whereas FDG-PET/CT was proven more effective for detecting large numbers of small lesions. When comparing the impact on the choice of a management plan, both FDG-PET/CT and contrast-enhanced multidetector CT were found to be significantly effective at predicting the locations of recurrence. CONCLUSIONS: Both integrated FDG-PET/CT and contrast-enhanced multidetector CT are sensitive surveillance modalities for the detection of recurrent ovarian cancer; the use of both modalities aids decisions on treatment plans and may ultimately have a favorable impact on prognosis. However, contrast-enhanced multidetector CT is recommended for the regular follow-up for ovarian cancer patients after initial treatment.