DNA Methyltransferase 1 Protein Levels Research Articles

Preclinical and Clinical Use of AB1, a DNMT1 Protein Depleter, to Upregulate Fetal Hemoglobin in Townes Sickle Cell Disease (SCD) Mice and Patients with SCD

Background: Sickle Cell Disease (SCD) is an inherited hematologic disorder characterized by lifelong hemolysis, vaso-occlusion and severe complications including pain, acute chest syndrome and stroke among others. Its complex pathophysiology is driven by polymerization of mutated sickle hemoglobin (HbS) in red blood cells. Fetal hemoglobin (HbF) has been well documented to interfere with HbS polymerization, however, γ-globin gene transcription is silenced after birth through the action of a repressor complex including DNA methyltransferase 1 (DNMT1) during hemoglobin switching. We previously demonstrated the ability of AB1, a potent non-cytotoxic agent which depletes DNMT1 protein, to induce HbF in sickle erythroid progenitors. To expand these findings, we aimed to 1) perform preclinical studies in the Townes SCD mouse model to determine the ability of AB1 to induce HbF and deplete DNMT1 protein; and 2) evaluate the safety of oral AB1 in patients with SCD through an open-label, dose escalating phase 1/2 study (NCT05261711). Methods: Preclinical. Townes SCD mice, 4 months old (6 mice per group) were treated by intraperitoneal injections of escalating AB1 doses of 0.5, 1.5 and 3.0 mg/dose, hydroxyurea (HU; 100 mg/kg/dose) alone or HU combined with AB1 (0.5mg/dose) and water control, 5 days/week for 6 weeks. Every 2 weeks, complete blood counts with differentials were performed along with flow cytometry for HbF positive cells (F-cells) and reticulocytes; RT-qPCR for γ- and β-globin mRNA levels was completed and the spleen was harvested for weights and DNMT1 protein levels by Western blot. Clinical Trial. After informed consent, patients with confirmed HbSS or HbSb 0 thalassemia, on stable HU doses (if on treatment), and no recent/chronic transfusions or pain crisis were approached for the study. Patients were enrolled at Duke and Augusta University, starting on 2 mg of AB1 with 4 additional cohorts (4mg, 8mg, 16mg, and 32mg) to be recruited. Doses were taken daily by mouth for 8 weeks. Safety and tolerability (primary outcomes), as well as pharmacokinetics, pharmacodynamics and HbF response (secondary outcomes) were assessed. The F-cells and mean fluorescence intensity were measured by flow cytometry and HbF% by HPLC. Results: Preclinical. In general, SCD mice treated with AB1 showed good weight gain without toxicity. Three deaths occurred in the HU and combination treatment groups along with a significant decrease in platelets, granulocytes, and monocytes; by contrast, one death occurred in the 3mg/kg AB1 group, but the blood or reticulocyte counts were not affected. By week 6, HU increased F-cells by 2.1-fold (p=0.02) compared to a 2.2-fold (p=0.006) and 1.5-fold (p=0.03) increase by AB1 1.5mg/kg and 3.0 mg/kg respectively. Likewise, γ-globin mRNA increased, and β-globin mRNA decreased at the highest dose. Spleen analysis showed decreased weights and an 80% decrease in reactive oxygen species by AB1. Finally, DNMT1 protein levels were depleted by AB1 in spleen tissue. Clinical Trial. The clinical trial opened for enrollment in the winter of 2022. Two patients completed cohort 1 and two patients have enrolled and started cohort 2. Both cohort 1 patients had HbSS with a median age of 29.5 years (range 28-31). No change in total hemoglobin or reticulocyte counts was observed in either subject treated with 2mg AB1 daily. During the treatment period two adverse events occurred (rash-drug related and elevated liver enzymes-unrelated), however there were no serious adverse events. AB1 increased F-cell levels in subject 1 by 5.7-fold (2.9% to 16.4%). Expanded analysis of subject 2 showed an increase in F-cells 3-fold (4.8% to 14.4%) and 3-fold increase in F-reticulocytes. At the lowest 2mg dose, by HPLC analysis both patients had an increase in HbF% from a mean of 6.3% to 7% supporting protein induction by AB1. Discussion: The goal of this project is to develop an oral-active HbF inducer for the treatment of individuals with SCD. Data generated in the SCD mouse showed a significant increase in F-cells and γ-globin gene transcription, along with DNMT1 protein depletion. Subsequent oral AB1 treatment of patients with HbSS confirmed increased F-cells and HbF protein levels without clinical toxicities. These findings support continuing the ongoing phase 1/2 study, which will provide further insights into the ability of AB1 to increase HbF without hematologic side effects in patients with SCD.

GCM2 Silencing in Parathyroid Adenoma Is Associated With Promoter Hypermethylation and Gain of Methylation on Histone 3.

Glial cells missing 2 (GCM2), a zinc finger-transcription factor, is essentially required for the development of the parathyroid glands. We sought to identify whether the epigenetic alterations in GCM2 transcription are involved in the pathogenesis of sporadic parathyroid adenoma. In addition, we examined the association between promoter methylation and histone modifications with disease indices. Messenger RNA (mRNA) and protein expression of GCM2 were analyzed by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry in 33 adenomatous and 10 control parathyroid tissues. DNA methylation and histone methylation/acetylation of the GCM2 promoter were measured by bisulfite sequencing and chromatin immunoprecipitation-qPCR. Additionally, we investigated the role of epigenetic modifications on GCM2 and DNA methyltransferase 1 (DNMT1) expression in parathyroid (PTH)-C1 cells by treating with 5-aza-2'-deoxycytidine (DAC) and BRD4770 and assessed for GCM2 mRNA and DNMT1 protein levels. mRNA and protein expression of GCM2 were lower in sporadic adenomatous than in control parathyroid tissues. This reduction correlated with hypermethylation (P < .001) and higher H3K9me3 levels in the GCM2 promoter (P < .04) in adenomas. In PTH-C1 cells, DAC treatment resulted in increased GCM2 transcription and decreased DNMT1 protein expression, while cells treated with the BRD4770 showed reduced H3K9me3 levels but a nonsignificant change in GCM2 transcription. These findings suggest the concurrent association of promoter hypermethylation and higher H3K9me3 with the repression of GCM2 expression in parathyroid adenomas. Treatment with DAC restored GCM2 expression in PTH-C1 cells. Our results showed a possible epigenetic landscape in the tumorigenesis of parathyroid adenoma and also that DAC may be a promising avenue of research for parathyroid adenoma therapeutics.

Prenatal bisphenol-A exposure altered exploratory and anxiety-like behaviour and induced non-monotonic, sex-specific changes in the cortical expression of CYP19A1, BDNF and intracellular signaling proteins in F1 rats

Bisphenol-A (BPA) is one of the extensively studied estrogenic endocrine disrupting chemicals (EDC) with ubiquitous exposure among humans and wildlife. While there are literature reporting the association of dysregulated Brain-derived neurotrophic factor (BDNF) expression levels with altered cognitive and emotional behaviour such as anxiety-like and stress behaviour in animal models, there are no studies in BPA that investigate these altered neurobehavioural outcomes in parallel with the expression of intracellular proteins involved in BDNF signaling pathway. In this study, pregnant Wistar rats were exposed to BPA through water (25 μg/L, 250 μg/L, and 2.5 mg/L) during gestation day (GD) 9–21. Prenatal BPA exposure, increased anxiety-like behaviour in males and decreased exploratory behaviour in both male and female offspring. Downregulation of both BDNF and CYP19A1 genes were observed in male BPA-exposed offspring, whereas in females, the expression was upregulated. The expression of p-AKT, p-MEK and p-ERK proteins were increased in males, while in females, it decreased. Both the male and the female BPA-exposed offspring exhibited elevated levels of DNMT1 protein. The sex-specific alteration in the expression of CYP19A1 and DNA methyltransferase 1 (DNMT1) suggests that both hormonal and epigenetic dysregulation could underlie the long-term BPA-induced effect on anxiety-like behaviour in the offspring.

A pilot clinical trial of p53/p16-independent epigenetic therapy for pancreatic ductal adenocarcinoma (PDA).

699 Background: PDA treatment is limited to cytotoxic drugs. A key factor limiting their efficacy is TP53 mutations, omnipresent in PDA, which counter apoptosis-mediated cell kill. We evaluated a novel epigenetic approach using decitabine (Dec) to inhibit DNA methyltransferase 1 (DNMT1) and effect cancer cell cycle exits by epithelial-differentiation, combined with tetrahydrouridine (THU) to inhibit cytidine deaminase (CDA) and thereby permit oral bioavailability and solid-tissue distribution of Dec. Methods: Open-label single-arm, IRB-approved clinical trial at Cleveland Clinic and University Hospitals for patients with metastatic PDA that had progressed on prior chemotherapy, ECOG PS of 0-2. Treatment was oral, weight-based, with Dec 10-20 mg, and THU 500-1000 mg daily, 5 days/week. Primary endpoint was DNMT1 protein levels at 16-week vs baseline biopsies. Results: From Apr to Aug 2017, we enrolled 13 patients. Median age was 65 (range 44-74) years; 7 (54%) males; 11 (85%) Caucasians. Median time from diagnosis was 13 (3.9-53.5) months, with a median of 2 (1-3) prior lines of therapy. Baseline ECOG PS was 0/1 in 12 (92%) patients. All patients started study drugs; median time on treatment was 35 (4-63) days, and on study 72 (25-105) days. The most frequent adverse events attributable to the study drugs were anemia (n=5), and anorexia, dehydration, nausea, fatigue, febrile neutropenia and decreased lymphocyte count, in 3 patients each; no deaths. Eight (62%) patients underwent evaluation scans at 8 weeks, showing stable disease in 1 patient and progression in 7. Common reasons for coming off of study drugs were progression (n=6), physician discretion (n=3), and adverse events (n=2). Overall, 6 patients died; median survival was 3.1 months, and patients did not reach the 16-week biopsy. Shifts in blood counts, a sensitive indicator of Dec systemic activity, were unexpectedly mild, and plasma CDA enzyme activity was increased versus other cancer and normal controls. Conclusions: This first-of-its-kind study demonstrated feasibility and safety of the novel oral epigenetic therapy. Systemically elevated CDA in these patients requires higher doses of THU; a trial accordingly refined is planned. Clinical trial information: NCT02847000.

Intestinal PPARα Protects Against Colon Carcinogenesis via Regulation of Methyltransferases DNMT1 and PRMT6

Many genetic and environmental factors, including family history, dietary fat, and inflammation, increase risk for colon cancer development. Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear receptor that regulates systemic lipid homeostasis. We explored the role of intestinal PPARα in colon carcinogenesis. Colon cancer was induced in mice with intestine-specific disruption of Ppara (PparaΔIE), Pparafl/fl (control), and mice with disruption of Ppara that express human PPARA (human PPARA transgenic mice), by administration of azoxymethane with or without dextran sulfate sodium (DSS). Colons were collected from mice and analyzed by immunoblots, quantitative polymerase chain reaction, and histopathology. Liquid chromatography coupled with mass spectrometry-based metabolomic analyses were performed on urine and colons. We used molecular biology and biochemical approaches to study mechanisms in mouse colons, primary intestinal epithelial cells, and colon cancer cell lines. Gene expression data and clinical features of patients with colorectal tumors were obtained from Oncomine, and human colorectal-tumor specimens and adjacent normal tissues were collected and analyzed by immunohistochemistry. Levels of Ppara messenger RNA were reduced in colon tumors from mice. PparaΔIE mice developed more and larger colon tumors than control mice following administration of azoxymethane, with or without DSS. Metabolomic analyses revealed increases in methylation-related metabolites in urine and colons from PparaΔIE mice, compared with control mice, following administration of azoxymethane, with or without DSS. Levels of DNA methyltransferase 1 (DNMT1) and protein arginine methyltransferase 6 (PRMT6) were increased in colon tumors from PparaΔIE mice, compared with colon tumors from control mice. Depletion of PPARα reduced the expression of retinoblastoma protein, resulting in increased expression of DNMT1 and PRMT6. DNMT1 and PRMT6 decreased expression of the tumor suppressor genes Cdkn1a (P21) and Cdkn1b (p27) via DNA methylation and histone H3R2 dimethylation-mediated repression of transcription, respectively. Fenofibrate protected human PPARA transgenic mice from azoxymethane and DSS-induced colon cancer. Human colon adenocarcinoma specimens had lower levels of PPARA and retinoblastoma protein and higher levels of DNMT1 and PRMT6 than normal colon tissues. Loss of PPARα from the intestine promotes colon carcinogenesis by increasing DNMT1-mediated methylation of P21 and PRMT6-mediated methylation of p27 in mice. Human colorectal tumors have lower levels of PPARA messenger RNA and protein than nontumor tissues. Agents that activate PPARα might be developed for chemoprevention or treatment of colon cancer.

High expression of DNA methyltransferase 1 in Kazakh esophageal epithelial cells may promote malignant transformation induced by N-methyl-N'-nitro-N-nitrosoguanidine.

We examined the role of DNA methyltransferase 1 (DNMT1) in N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced malignant transformation of Kazakh esophageal epithelial (EE) cells to better understand the pathogenesis of esophageal cancer (EC). The 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide method and colony formation assays were performed to determine the MNNG dose for malignant transformation. Colony formation assays showed the effects of different frequencies of MNNG exposure and different cell passages on malignant transformation. A nude mouse tumor experiment indicated the malignancy of Kazakh EE cells expressing high DNMT1 levels and of transformed cells. The result shows that when the dose, frequency, and time of MNNG exposure increased, cell morphology became irregular, cell-contact suppression disappeared, and cell tolerance and growth rate increased. Colony formation occurred in the Kazakh-DNMT1 group after 14 transfections and 27 passages. Significant differences in DNMT1 mRNA and protein levels were observed in different types of cells and tumor tissues (F = 140.644, p < 0.001; F = 105.545, p < 0.001). Our study demonstrated that DNMT1 could promote MNNG to induce malignant transformation of EE cells, and this study will help understand EC better in order to develop appropriate treatment strategies.

P118 TARGETING ENDOPLASMIC RETICULUM STRESS FOR THE TREATMENT OF FIBROSIS IN CROHN’S DISEASE

Progressive tissue remodeling characterized by extensive collagen production and excess extracellular matrix deposition leads to intestinal fibrosis and stricture formation in patients with fibrostenotic Crohn’s disease. Currently medical therapies can delay but not prevent the development of critical fibrostenosis necessitating surgery. Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are associated with intestinal epithelial cells damage and apoptosis in Crohn’s disease. However, the role of ER stress and UPR signaling in subepithelial myofibroblasts (SEMF) during the development of intestinal fibrosis awaits further clarification. Previously, we reported that increase in ER stress and UPR signaling in SEMF isolated from strictured ileum contributes to activation of TGF-β1 and fibrosis. Increased interaction between GRP78 and latent TGF-β complex on the cell membrane leads to αVβ3 integrin-mediated activation of latent TGF-β. The ER stress response was augmented in SEMF by silencing of inhibitory miR-199a-5p by DNA methyltransferase-1 (DNMT1). In current study we investigated the effects of selective targeting of activated ER stress sensors on intestinal fibrosis in vitro. SEMF were prepared from cells isolated from affected ileum and from normal ileum in the same patient undergoing resection for Crohn’s disease. SEMF were transfected with siRNA to the ER stress proteins: Grp78, ATF6, XBP1 and IRE1α, and to DNMT1 to knockdown these proteins and compared to scramble sense siRNA treatment. Some cells were co-transfected with a Smad-binding element (SBE) luciferase reporter and TGFB1 transcriptional activity measured. The protein levels of GRP78, DNMT1 and collagen I were measured by immunoblot and normalized to β-actin. Active and total TGF-β1 was measured by ELISA. Our results showed that knockdown of DNMT1 decreased GRP78 protein production, diminished activation of TGF-β1, and blocked ER stress-induced TGF-β1-dependent collagen production. Knockdown of Grp78, Atf6α, Xbp1, and Ire1α in normal SEMF decreased ER stress-induced TGFB1 transcriptional activity by 30 ± 2%, 33 ± 1.5%, 35 ± 1.8%, and 23 ± 1.2%, respectively. In 3D culture of normal SEMF with Grp78 knocked down, tunicamycin failed to induce ER stress, increase activation of TGF-β1 or increase collagen production. Taken together, our results indicate that ER stress in part mediates development of intestinal fibrosis in Crohn’s disease by where DNMT1-induced silencing of miR-199a-5p allows a heighted ER Stress response that results in greater TGF-β1 activation and collagen production in the SEMF.

The Curcumin Analog CH-5 Exerts Anticancer Effects in Human Osteosarcoma Cells via Modulation of Transcription Factors p53/Sp1.

Curcumin is a potential anticancer drug with poor bioavailability, which limits its clinical use as a therapeutic agent. The aim of this study was a preliminary evaluation of the curcumin analogue CH-5 as a cytotoxic agent in human osteosarcoma cell lines U2OS, MG-63, and Saos-2. CH-5 inhibited cell viability at lower concentrations than curcumin, leading to the induction of apoptosis. The cellular levels of the transcription factors p53 and Sp1 affect the expression of cellular pathways that lead to apoptosis. CH-5 increased p53 protein levels in U2OS cells and reduced Sp1 levels, with a consequent effect on the expression of their target genes DNA methyltransferase 1 (DNMT1) and growth arrest and DNA damage-inducible 45 alpha gene (Gadd45a). CH-5 repressed DNMT1 and increased Gadd45a mRNA expression, which was dependent on p53, as this effect was only observed in the colorectal cancer cell line HCT116 with active p53, but not in the isogenic p53-deficient HCT116 cells. CH-5 also reduced the protein levels of DNMT1, which led to the upregulation of Gadd45a. These results suggest that CH-5 has potentially higher anticancer activity than curcumin, which is associated with the expression of apoptosis-associated genes regulated by the transcription factors Sp1 and p53. Future work on CH-5 will define the therapeutic potential of this compound in vivo.

Effects of Folic Acid on DNMT1, GAP43, and VEGFR1 in Intrauterine Growth Restriction Filial Rats.

To investigate the effect of a folic acid intervention on the outcome of intrauterine growth restriction (IUGR) filial rats and changes in DNA methyltransferase 1 (DNMT1), growth-associated protein 43 (GAP43), and vascular endothelial growth factor receptor 1 (VEGFR1). The IUGR animal model was established using a starvation method in pregnant rats. The animals were randomly divided into 4 groups: normal controls, IUGR rats, IUGR rats given folic acid, and IUGR rats given normal saline. After the rats were weighed, the brain tissue was removed and the messenger RNA and protein levels of DNMT1, GAP43, and VEGFR1 were validated by reverse transcription-polymerase chain reaction and western blot. Birth weight was significantly increased after intervention with folic acid compared with the IUGR group, although it remained about 16% lower compared with the normal controls. The expressions of DNMT1 and GAP43, which were significantly upregulated in the IUGR group compared with the normal controls, were decreased with the folic acid intervention. However, there were no significant differences in VEGFR1 expression across groups. Brain damage in IUGR rats mainly manifests as delayed myelination or synaptic maturation and rarely as pathological proliferation of blood vessels. Our results strongly support the idea that the application of folic acid during pregnancy might represent a new epigenetic therapy for IUGR.

Reciprocal Regulation Between miR-148a/152 and DNA Methyltransferase 1 Is Associated with Hyperhomocysteinemia-Accelerated Atherosclerosis

DNA methyltransferase 1 (DNMT1) and miRNAs are both important regulators of gene expression that have been implicated in the pathogenesis of atherosclerosis. This study was designed to elucidate the potential interaction between DNMT1 and miRNAs in the context of hyperhomocysteinemia (HHcy)-related atherosclerosis. In the aorta of ApoE-/- mice fed a high methionine diet, increased expression of miR-148a/152, with decreased DNMT1 mRNA and protein levels, was detected. Similar changes were observed in cultured foam cells stimulated with homocysteine. When miR-148a/152 was overexpressed using viral vectors, DNMT1 expression was suppressed, whereas the expression of adipose differentiation-related protein (ADRP) was enhanced, and the contents of total cholesterol (TC) and cholesteryl ester (CE) were increased in cultured foam cells. Conversely, downregulation of miR-148a/152 led to elevated DNMT1 expression, reduced ADRP expression, and lowered contents of TC and CE. The luciferase reporter assay verified that DNMT1 is a target gene for miR-148a/152 and overexpression of DNMT1 can partially reverse the miR-148a/152-induced lipid accumulation in foam cells. Meanwhile, we observed that DNMT1 overexpression enhanced DNA methylation and reduced miR-148a/152 expression. Our data showed reciprocal regulation between miR-148a/152 and DNMT1 in foam cells, which likely plays a critical role in HHcy-related atherosclerosis.

Inhibition of EZH2 via activation of SAPK/JNK and reduction of p65 and DNMT1 as a novel mechanism in inhibition of human lung cancer cells by polyphyllin I

BackgroundPolyphyllin I (PPI), a bioactive phytochemical extracted from the Rhizoma of Paris polyphylla, has been reported to exhibit anti-cancer activity. However, the detailed mechanism underlying this remains to be elucidated.MethodsCell viability and cell cycle distribution were measured using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometry assays, respectively. The expression of enhancer of zeste homolog 2 (EZH2) mRNA was measured by quantitative real time PCR (qRT-PCR). Western blot analysis was performed to examine the phosphorylation and protein expression of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), p65, DNA methyltransferase 1 (DNMT1) and EZH2. Exogenous expression of p65, DNMT1, and EZH2 were carried out by transient transfection assays. Promoter activity of EZH2 gene was determined using Secrete-Pair Dual Luminescence Assay Kit. A xenografted tumor model in nude mice and bioluminescent imaging system were used to further test the effect of PPI in vivo.ResultsWe showed that PPI significantly inhibited growth and induced cell cycle arrest of non-small cell lung cancer (NSCLC) cells in a dose-dependent manner. Mechanistically, we found that PPI increased the phosphorylation of SAPK/JNK, reduced protein expression of p65 and DNMT1. The inhibitor of SAPK/JNK (SP600125) blocked the PPI-inhibited p65 and DNMT1 protein expression. Interestingly, exogenously expressed p65 overcame PPI-inhibited protein expression of DNMT1. Moreover, PPI reduced EZH2 protein, mRNA, and promoter activity; overexpression of EZH2 resisted the PPI-inhibited cell growth, and intriguingly, negative feedback regulation of SAPK/JNK signaling. Finally, exogenous expression of DNMT1 antagonized the PPI-suppressed EZH2 protein expression. Consistent with this, PPI inhibited tumor growth, protein expression levels of p65, DNMT1 and EZH2, and increased phosphorylation of SAPK/JNK in vivo.ConclusionOur results show that PPI inhibits growth of NSCLC cells through SAPK/JNK-mediated inhibition of p65 and DNMT1 protein levels, subsequently; this results in the reduction of EZH2 gene expression. The interactions among p65, DNMT1 and EZH2, and feedback regulation of SAPK/JNK by EZH2 converge on the overall responses of PPI. This study reveals a novel mechanism for regulating EZH2 gene in response to PPI and suggests a new strategy for NSCLC associated therapy.

The correlation between DNMT1 and ERα expression and the methylation status of ERα, and its clinical significance in breast cancer.

The correlation between the expression of DNA methyltransferase-1 (DNMT1) and estrogen receptor α (ERα), as well as the methylation status of ERα, was analyzed to investigate the clinical significance of DNMT1 and ERα in breast cancer. Substance P immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR) were utilized to detect the protein and mRNA expression levels of DNMT1 and ERα in 112 breast cancer and 20 normal breast specimens. Methylation specific PCR was utilized to detect the methylation status of ERα in ERα-positive and -negative breast cancer specimens and 20 normal breast specimens. The results of the present study revealed that DNMT1 protein and mRNA levels were low in normal breast specimens (10.00 and 46.05%, respectively) and ERα-positive breast cancer specimens (15.00 and 48.68%, respectively), compared with increased levels in ERα-negative breast cancer specimens (81.11 and 88.89%, respectively; P<0.05). The methylation rate of ERα was highest in ERα-negative breast cancer specimens (86.11%) compared with normal breast specimens and ERα-positive breast cancer specimens (10.00 and 36.84%, respectively; P<0.05). Positive expression of ERα protein was observed to be associated with progesterone receptor expression (P<0.05), however, no such association was observed for age, menopause state, tumor size, number of positive nodes, Tumor-Node-Metastasis stage or tumor type (P>0.05). The protein and mRNA expression levels of DNMT1 were negatively correlated with ERα expression (P<0.05). DNMT1 expression was positively correlated with methylation of ERα (P<0.05), and was positively correlated with the methylation of CpG islands of ERα, indicating that the detection of DNMT1 expression may be significant for the diagnosis and typing of breast cancer.

Structural optimization of non-nucleoside DNA methyltransferase inhibitor as anti-cancer agent.

Inhibition of DNA methyltransferase 1 (DNMT1) can reverse the malignant behavior of cancer cells by restoring expression of aberrantly silenced genes that are required for differentiation, senescence, and apoptosis. Clinically used DNMT1 inhibitors decitabine and azacitidine inhibit their target by covalent trapping after incorporation into DNA as azacytidine analogs. These nucleoside compounds are prone to rapid enzymatic inactivation in blood, posing challenges to the development of purely epigenetic dosing schedules. Non-nucleoside compounds that suppress expression or function of DNMT1 may overcome this problem. Using a high-throughput PCR-based site specific chromatin condensation assay, we identified a compound that reactivated Cyclin-Dependent Kinase Inhibitor 2A (CDKN2A) in myeloma cells and suppressed expression of DNMT1 from a library of 5120 chemically diverse small molecules. Lead optimization was performed to generate 26 new analogs with lung cancer proliferation and DNMT1 expression as activity readout. Two of the new derivatives showed 2 fold improvement of growth inhibiting potency and also decreased DNMT1 protein levels in lung cancer cells.

Decreased Expression of Anti-DNMT1 Tumor-Suppressor microRNAs in Azacitidine (AZA)-Resistant Cells Independently Predicts Survival in Patients Treated with AZA for Higher Risk Myelodysplastic Syndrome (HRMDS) and Oligoblastic Acute Myeloid Leukemia (AML)

Background: AZA is the standard of care for patients with either HRMDS or AML with 20-30% blasts (Oligoblastic AML). The response rate is ~50% with a median response duration of 12-15 months. The mechanisms underlying primary and secondary resistance are poorly understood and it remains difficult to accurately predict which patients will respond and in responders, to predict secondary resistance. The main factors demonstrated or suggested to interfere with response to AZA and/or survival include marrow blast percentage, performance status, IPSS cytogenetic risk, presence of peripheral blasts, transfusion dependency, IPSS-R risk, mutations of TET2, P53, IDH1/2, and DNMT3A, elevated expression of BCL2L10, Fas, or PI-PLCbeta1. Deregulation of microRNAs is a hallmark of MDS, yet its consequences on AZA efficacy have not been specifically addressed in HRMDS.Methods: We measured the expression of 754 miRNAs in SKM1 MDS cells resistant or sensitive to AZA. miRNAs of interest were ectopically expressed or specifically inhibited in HEK293T cells which were assayed for AZA sensitivity (MTT). Seven miRNAs were quantified in bone marrow mononuclear cells deriving from 75 patients with HRMDS (n= 50) or oligoblastic AML treated with AZA [median age 74, 24 females, median cycle number 6, (1-39)].Results: Seven miRNAs (miR-125a-5p, miR-99b-5p, miR-126, miR-126*, hsa-let-7c, miR-34b-3p, and miR-10b*) that include 6 tumor-suppressor miRNAs, were found differentially expressed between AZA-sensitive versus -resistant cells; all being transcriptionally repressed in resistant cells. In silico, 5 of these miRNAs were found to target the 3' UTR of DNA methyltransferase 1 (DNMT1) while Zhao et al. [Arthritis & rheumatism, 2011; 63(5)] have shown that miR-126 directly inhibits DNMT1 translation. DNMT1 is one of the main AZA molecular target, the higher the level of DNMT1 expression, the lower the AZA sensitivity [Li et al., Cancer biology & therapy, 2010; 9(4)]. Microarray and western blotting showed that levels of DNMT1 protein, but not mRNA, were significantly higher in AZA-resistant cells. In HEK293T cells, specific endogenous miR-126/126* inhibition significantly augmented DNMT1 protein expression and triggered AZA-resistance, as measured through MTT proliferation assay. In the same cells, ectopic expression of miR-126/126* decreased DNMT1 protein expression in a concentration-dependent manner. In the 75 patients treated with AZA, a decreased expression level of all but miR-10* was associated with decreased response rate (IWG 2006 criteria) and poor outcome; miR-126/126* having the strongest prognostic impact. When compared with miR-126*High MDS, miR-126*Low MDS had significantly lower overall response rate (37% versus 60%, p=0.04), higher relapse rate (100% versus 71%, p=0.034), shorter progression-free (PFS) (8±8% versus 49±12% at 3 years, p=0.004, log rank test), and overall survival (OS) (16±6% versus 46±9%, p=0.004). Baseline patient characteristics of the 2 groups were similar. Multivariate analyses were performed using the Cox proportional hazards model. Table 1 shows that age, miR-126* expression, and IPSS-R risk independently predicted PFS and OS. miRNAs expression was analyzed over time in 15 patients. The mean expression level of 5/7 miRNAs increased over time in the 10 responders without statistically significant difference (DNS) between the first and latest values. In contrast, the expression of 7/7 miRNAs decreased over time in the 5 patients with treatment failure, the difference being statistically significant for 2 miRNAs (p²0.043, Wilcoxon test). Secondary resistance occurred in 7/10 responders and was found associated with a decreased expression of 6/7 miRNAs (p²0.044 for 4 miRNAs) versus 2/7 (DNS) in the 3 long-term responders.Conclusion: Our results suggest that in HRMDS and oligoblastic AML, i. primary or secondary resistance to AZA is associated with the decreased expression of anti-DNMT1 tumor-suppressor microRNAs that trigger AZA resistance in vitro; ii. measuring miRNAs expression before and under treatment might help to predict primary or secondary AZA resistance and thereby to rapidly offer alternative treatment; iii. increasing AZA exposure might help to circumvent AZA resistance in case of either low or decreased anti-DNMT1 miRNA concentration while using anti-DNMT1 microRNAs as a therapeutic tool might increase or restore AZA sensitivity. [Display omitted] DisclosuresFenaux:Janssen: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Wattel:AMGEN: Consultancy, Research Funding; PIERRE FABRE MEDICAMENTS: Research Funding; CELGENE: Research Funding, Speakers Bureau; NOVARTIS: Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Research Funding.

Coordination of AUF1 and miR-148a destabilizes DNA methyltransferase 1 mRNA under hypoxia in endometriosis.

DNA methylation is regulated by hypoxia in endometriosis. Hypoxia causes global hypomethylation through AU-rich element binding factor 1 (AUF1)/microRNA-148a (miR-148a)-mediated destabilization of DNA methyltransferase 1 (DNMT1) mRNA. Eutopic endometrial and ectopic endometriotic stromal cells have the same genetic background, but differ in several cellular and molecular responses. Both hypoxia and DNA methylation regulate several genes involved in the development of endometriosis. This laboratory study included 15 patients of reproductive age with endometriosis or normal menstrual cycles. Paired endometrial and endometriotic tissues were collected for assaying the levels of DNMT1, 3a and 3b using quantitative RT-PCR, western blot and immunohistochemical (IHC) staining. Primary cultured endometrial stromal cells maintained in normoxia/hypoxia (1% O2) or treated with hypoxia-mimetic compounds were also assayed. The levels of DNA 5-methylcytosine were assayed by using IHC in clinical specimens and murine tissues, and by ELISA in cultured stromal cells. The 3'-untranslated region reporter assay was used to evaluate the effect of hypoxia, microRNAs (miRNAs) and human antigen R (HuR)/AUF1 on DNMT1 mRNA stability. RNA immunoprecipitation was used to assess the interaction of HuR/AUF1 and miR-148a/DNMT1 mRNA under hypoxia. Finally, a transplant-induced mouse model of endometriosis using 20 mice was used to elucidate the alteration of Dnmt1 levels and DNA methylation in the endometriotic tissues. Levels of DNMT1 mRNA and protein and 5-methylcytosine were lower in the ectopic stromal cells (P < 0.05) than in the eutopic cells. Treatment with hypoxia and its mimetic compounds recapitulated the reduced levels of DNMT1 and 5-methylcytosine levels (P < 0.05 versus control). Hypoxia treatment destabilized DNMT1 mRNA through recruitment of miR-148a and AUF1. Mutations introduced to the miR-148a targeting site or AU-rich element (ARE) restored the hypoxia-suppressed DNMT1 3'-untranslated region (3'-UTR) reporter activity (P < 0.05 versus control). Levels of proteins of three hypermethylated genes in endometrial stroma cells, GATA6, HOXA3 and SLC16A5, were elevated after 72 h of hypoxia treatment (P < 0.05 versus control). Finally, a transplant-induced model of endometriosis demonstrated the down-regulation of DNMT1 and a decrease in 5-methylcytosine in the endometriotic tissues (P < 0.05, eutopic versus ectopic). Primary human cell cultures and a murine model were used in this study, and thus the results may not fully represent the situation in vivo. This is the first study to elucidate how microenvironmental hypoxia links to the epigenetic effects of DNA methylation in the endometriosis, and to delineate the molecular mechanism of hypoxia-coordinated AUF1/miR-148a interaction and recruitment to DNMT1 mRNA during the pathogenesis of endometriosis. The development of future therapeutics in endometriosis may aim at disrupting this specific interaction and eventually restore the epigenetic regulation. This work was supported by the National Science Council of Taiwan (NSC101-2320-B-006-030-MY3). The author declares that there are no conflicts of interest.

Downregulation of DNA methyltransferase 1 in zona-free cloned buffalo (Bubalus bubalis) embryos by small interefering RNA improves in vitro development but does not alter DNA methylation level.

Aberrant epigenetic reprogramming, especially genomic hypermethylation, is implicated as the primary reason behind the failure of the cloning process during somatic cell nuclear transfer (SCNT). We transfected one-cell-stage zona-free buffalo embryos produced by handmade cloning with 50 nM DNMT1 small interfering RNA (siRNA), using lipofectamine, to knockdown the DNA methyltransferase 1 (DNMT1) gene. siRNA treatment decreased (p<0.001) the expression level of DNMT1 mRNA and DNMT1 protein in the one-cell-stage embryos and increased (p<0.05) the blastocyst rate (52.3 ± 1.3% vs. 45.3 ± 2.5%) compared to that in the controls, but did not reduce the DNA methylation level similar to the in vitro-fertilized (IVF) embryos. It also increased (p<0.05) the relative mRNA abundance of P53 and CASPASE 3, but not that of HDAC1, DNMT1, and DNMT3a, in the blastocysts of the siRNA group compared to the controls. The global level of H3K18ac was higher (p<0.05) in the blastocysts of the siRNA group than in the controls, whereas that of H3K9ac and H3K27me3 was not significantly different between the two groups. In conclusion, lipofection can be successfully used for transfection of DNMT1 siRNA into one-cell-stage zona-free cloned buffalo embryos. It results in a concomitant decrease in the DNMT1 mRNA and protein levels in the one-cell-stage embryos. siRNA-mediated knockdown increases the blastocyst rate but does not alter the DNA methylation level.

Perinatal nicotine exposure suppresses PPARγ epigenetically in lung alveolar interstitial fibroblasts.

Due to the active inhibition of the adipogenic programming, the default destiny of the developing lung mesenchyme is to acquire a myogenic phenotype. We have previously shown that perinatal nicotine exposure, by down-regulating PPARγ expression, accentuates this property, culminating in myogenic pulmonary phenotype, though the underlying mechanisms remained incompletely understood. We hypothesized that nicotine-induced PPARγ down-regulation is mediated by PPARγ promoter methylation, controlled by DNA methyltransferase 1 (DNMT1) and methyl CpG binding protein 2 (MeCP2), two known key regulators of DNA methylation. Using cultured alveolar interstitial fibroblasts and an in vivo perinatal nicotine exposure rat model, we found that PPARγ promoter methylation is strongly correlated with inhibition of PPARγ expression in the presence of nicotine. Methylation inhibitor 5-aza-2'-deoxycytidine restored the nicotine-induced down-regulation of PPARγ expression and the activation of its downstream myogenic marker fibronectin. With nicotine exposure, a specific region of PPARγ promoter was significantly enriched with antibodies against chromatin repressive markers H3K9me3 and H3K27me3, dose-dependently. Similar data were observed with antibodies against DNA methylation regulatory factors DNMT1 and MeCP2. The knock down of DNMT1 and MeCP2 abolished nicotine-mediated increases in DNMT1 and MeCP2 protein levels, and PPARγ promoter methylation, restoring nicotine-induced down regulation of PPARγ and upregulation of the myogenic protein, fibronectin. The nicotine-induced alterations in DNA methylation modulators DNMT1 and MeCP2, PPARγ promoter methylation, and its down-stream targets, were also validated in perinatally nicotine exposed rat lung tissue. These data provide novel mechanistic insights into nicotine-induced epigenetic silencing of PPARγ that could be exploited to design novel targeted molecular interventions against the smoke exposed lung injury in general and perinatal nicotine exposure induced lung damage in particular.

A simple and efficient method to transfect small interference RNA into bovine SCNT embryos

RNA interference is an important tool to study the gene function. Microinjection and electroporation are usually used to transfer DNA, small interference RNA (siRNA), morpholinos, and protein into oocytes or embryos. This study used a simple and effective method to transfect siRNA into bovine somatic cell nuclear transfer (SCNT) embryos. In this method, siRNA transfection and electrofusion of SCNT were combined. A pair of platinum microelectrodes was used during SCNT to complete electrofusion. A CY3-labeled siRNA-targeted DNA methyltransferase-1 (DNMT1) was chosen to verify the siRNA transfection efficiency of this approach. First, a suitable concentration of siRNA was mixed with Zimmermann's fusion medium. Reconstructed embryos were then added into the microdrops of the mixed fusion medium to simultaneously transfect the siRNA and electrofuse the SCNT embryos. Our results showed that transfecting DNMT1 siRNA via the proposed method caused obvious CY3 fluorescence and significant downregulation of DNMT1 messenger RNA, DNMT1 protein, and global DNA methylation levels in the SCNT embryos. Meanwhile, the survival rate after electrofusion (90.4% vs. 89.4% vs. 89.1%, P > 0.05) and developmental rates of the SCNT embryos (72.8% vs. 74.9% vs. 72.4%, P > 0.05; 29.7% vs. 31.7% vs. 29.7%, P > 0.05) were not significantly affected. In summary, siRNAs were effectively transfected into the SCNT embryos via the proposed method and exert their functions, and the normal development of preimplantation SCNT embryos was not affected by the method used.

Folate Deficiency and Aberrant Expression of DNA Methyltransferase 1 were Associated with Cervical Cancerization

DNA methyltransferase 1 (DNMT1) plays a significant role in maintaining DNA methylation. Aberrant DNA methylation is a recognized feature of human cancers and folate is directly involved in DNA methylation via one-carbon metabolism. Previous reports also have suggested that folate deficiency was associated with many cancers. The aim of the present study was to evaluate the effect of folate deficiency and aberrant expression of DNA methyltransferase 1 (DNMT1) on cervical cancerization. The expression of DNMT1 protein and mRNA and levels of serum folate were detected in 238 women with a diagnosis of normal cervix (NC，n = 53), cervical intraepithelial neoplasia (CIN I, n = 52; CIN II/III, n = 53), and squamous cell carcinoma of the cervix (SCC; n = 80). In addition, the expression of DNMT1 protein and mRNA was measured in cervical cancer cells (Caski and C33A) treated by different concentration of folate. Serum folate levels decreased and expression levels of DNMT1 protein and mRNA increased gradually with progressive severity of the cervix lesions (P<0.001). It was found that folate was able to reduce the viability of Caski or C33A cell (r=0.978, P=0.002; r=0.984, P<0.001) and regulated aberrant expression of DNMT1 protein (r=-0.859, P=0.01; r=-0.914, P<0.001) and mRNA (r=-0.297, P=0.159; r=0.433, P=0.034) in vitro. Our findings indicated that the low-level of serum folate and high-expression of DNMT1 protein or mRNA was significantly associated with cervical carcinogenesis. Folate deficiency and aberrant expression of DNA methyltransferase 1 had additive effect on cervical cancerization. Folate supplement and recovery of aberrant DNA methylation status may offer a new strategy for prevention and therapy of cancers.

Significance of aberrant expression of DNA methyltransferase 1 in cervical cancerization tissue and cervical cancer cell lines

Objective To explore the effects of aberrant expression of DNA methyltransferase 1 (DNMT1) in cervical cancerization tissue and cervical cancer cells.Methods Cervical tissues were collected from 80 cases with a diagnosis of invasive cervix squamous cell carcinoma (SCC),53 cases with high-grade cervical intraepithelial neoplasia (CIN Ⅱ/Ⅲ),52 cases with low-grade cervical intraepithelial neoplasia (CIN Ⅰ)and 53 cases with normal cervix (NC).Meanwhile,Caski (HPV16-positive) and C33A (HPV-negative) cells selected from cervical cancer cell lines were cultured routinely in vitro.The expression of DNMT1 protein and mRNA were examined by Western blot analysis and real-time PCR (qRT-PCR) in the tissues and cells,respectively.Results The levels of DNMT1 protein were 1.33,1.84 and 2.28,and the Ct-ratios (DNMT1/β-actin) of DNMT1 mRNA were 1.27,1.27 and 1.26 in CIN Ⅰ,CIN Ⅱ/Ⅲand SCC group,respectively.Comparing with NC group,the expression of DNMT1 protein or mRNA was elevated in deficient cervical groups,with statistical significance (F =110.57,P ＜ 0.001,F =2.68,P =0.048).The expression levels of DNMT1 protein were increased steadily according to severity of the cervix lesions (x2tend =50.80,P ＜ 0.001),however,the expression of DNMT1 mRNA was not observed the same tendency (x2tend =3.63,P ＞ 0.05).The results from experiment in vitro showed that the levels of DNMT1 protein or mRNA were both higher in Caski cell than in C33A cell,especially for DNMT1 mRNA with significantly difference (t =7.134,P =0.002).Conclusion Aberrant expression of DNMT1 protein or mRNA could link with the risk of cervical cancerization by both transcriptional and posttranscriptional mechanisms.There would be a synergistic effect between overexpression of DNMT1 and HPV16 infection in the progression of cervix carcinogenesis. Key words: DNA methyltransferase 1; Aberrant expression; Cervical cancerization; Cervical cancer cells