MBD2 Expression Research Articles

Melatonin-induced suppression of DNA methylation promotes odontogenic differentiation in human dental pulp cells

ABSTRACT Differentiation potency of human dental pulp cells (hDPCs) is essential for dentin regeneration. DNA methylation is one of the major epigenetic mechanisms and is suggested to involve in differentiation of hDPCs, the machinery of which includes DNA methyltransferase enzymes (DNMTs) and methyl-CpG-binding domain proteins (MBDs). Our previous study has found that melatonin (MT) promoted hDPC differentiation, but its mechanism remains elusive. We aimed to investigate the role of DNA methylation in the promotion of MT to differentiation of hDPCs in vitro. hDPCs were cultured in basal growth medium (CO) or odontogenic medium (OM) exposed to MT at different concentrations (0, 10−12, 10−10, 10−8, 10−6, 10−4 M). The cell growth was analyzed using Cell Counting Kit-8 assay, and mineralized tissue formation was measured using Alizarin red staining. The expression of the 10 genes (DNMT1, DNMT3A, DNMT3B, MBD1-6, MeCP2) was determined using real-time qPCR and western blotting. The abundance of MeCP2 in the nuclei was evaluated using immunofluorescence analysis. Global methylation level was tested using ELISA. We found that mineralized tissue formation significantly increased in OM with MT at 10−4 M, while the levels of MeCP2 and global DNA methylation level declined. The expression of MBD1, MBD3, and MBD4 significantly increased in OM alone, and the expession of DNMT1 and MBD2 was decreased. These results indicate that MT promotes odontogenic differentiation of hDPCs in vitro by regulating the levels of DNMT1, MeCP2, and global DNA methylation, suggesting that MT-induced DNA methylation machinery may play an important role in tooth regeneration.

Assessment of Immuno-Histochemical Expression of MBD1 in Colorectal Adenocarcinoma and Its Correlations with Prognostic Factors.

BACKGROUND MBD1, the largest member of methyl binding domain family, has the most downregulated mRNA expression and upregulated methylation levels in advanced colorectal cancer (CRC). In this study, we evaluated the immune-histochemical expression of MBD1 in CRC and assessed its correlation with clinicopathological features to study its prognostic value in CRC. METHODS A total of 60 samples of CRC, from patients who underwent surgical gastroenterology operations, were randomly selected. The samples included one tumor-rich section per case and one adjacent tumor-free section as a normal control for that case. Then, immunohistochemistry (ICH) was performed for MBD1 protein on all samples and the expression of MBD1 was analyzed in cancerous and normal samples. In the next step, the correlation between MBD1 and clinicopathological features including age, sex, location of the tumor, grade, and stage were evaluated. RESULTS The expression of MBD1 protein had a significant downregulation in cancerous samples compared with normal control samples. This downregulation increased corresponding to both grade and stage of cancer. However, no correlation was seen between the expression of MBD1 and sex, age and location of the tumor. CONCLUSION MBD1 protein may be considered as a protein marker in the detection of CRC and its progression.

Avermectin inhibits neutrophil extracellular traps release by activating PTEN demethylation to negatively regulate the PI3K-ERK pathway and reducing respiratory burst in carp

Excessive residual avermectin (AVM) in the environment can have toxic effects on non-target organisms. AVM can exert immunotoxicity by inducing genomic demethylation, but its effect on neutrophil extracellular traps (NETs) release in carp is unclear. In this study, carp neutrophils were pretreated with 5 μg/L AVM or 4 μM DNA demethylation inhibitor (aurintricarboxylic acid, ATA), alone or in combination, and then treated with 4 μM phorbol 12-myristate 13-acetate (PMA) to stimulate NETs release. The results showed that exposure of carp neutrophils to AVM significantly suppressed NETs release and MPO expression, increased ROS production, and dramatically reduced PMA-induced cellular respiratory burst. In addition, AVM could bind to the MBD2 molecule, markedly upregulate MBD2 expression to cause demethylation, and clearly activate PTEN expression, thereby inhibiting the expression of PI3K, AKT, Raf, MEK, and ERK. However, these effects were alleviated by ATA. In conclusion, our study showed that AVM could inhibit NETs release in carp by inducing demethylation of PTEN to negatively regulate NETs synthesis pathways and reducing respiratory burst level. Our findings clarify the mechanism of AVM immunotoxicity to fish and are of great significance for efforts to protect the ecological environment and human health.

MBD1 promotes the malignant behavior of gallbladder cancer cells and induces chemotherapeutic resistance to gemcitabine

BackgroundMethyl-CpG binding domain protein 1 (MBD1), which couples DNA methylation to transcriptional repression, has been implicated in transcriptional regulation, heterochromatin formation, genomic stability, cell cycle progression and development. It has also been proven that MBD1 is involved in tumor development and progression. However, whether MBD1 is involved in tumorigenesis, especially in gallbladder cancer, is totally unknown.MethodsHuman GBC-SD and SGC996 cells were used to perform experiments. Invasion, wound healing and colony formation assays were performed to evaluate cell viability. A CCK-8 assay was performed to assess gallbladder cancer cell viability after gemcitabine treatment. Western blot analysis was used to evaluate changes in protein expression. Human gallbladder cancer tissues and adjacent nontumor tissues were subjected to immunohistochemical staining to detect protein expression.ResultsWe found that MBD1 expression was significantly upregulated in gallbladder cancer tissues compared with that in surrounding normal tissues according to immunohistochemical analysis of 84 surgically resected gallbladder cancer specimens. These data also indicated that higher MBD1 expression was correlated with lymph node metastasis and poor survival in gallbladder cancer patients. Overexpression and deletion in vitro validated MBD1 as a potent oncogene promoting malignant behaviors in gallbladder cancer cells, including invasion, proliferation and migration, as well as epithelial–mesenchymal transition. Studies have demonstrated that epithelial–mesenchymal transition is common in gallbladder cancer, and it is well known that drug resistance and epithelial–mesenchymal transition are very closely correlated. Herein, our data show that targeting MBD1 restored gallbladder cancer cell sensitivity to gemcitabine chemotherapy.ConclusionsTaken together, the results of our study revealed a novel function of MBD1 in gallbladder cancer tumor development and progression through participation in the gallbladder cancer epithelial–mesenchymal transition program, which is involved in resistance to gemcitabine chemotherapy. Thus, MBD1 may be a potential therapeutic target for gallbladder cancer.

The Expression of MBD6 Is Associated with Tumor Size in Uterine Leiomyomas.

Background: Uterine leiomyoma (UL) is the most common benign smooth muscle tumor of the uterus in reproductive women. Prior studies indicated that methyl-CpG-binding domain proteins (MBDs) may be involved in the pathogenesis of UL. Materials and Methods: In this study, UL tissues and paired adjacent myometrium were collected from a total of 51 patients. The expression of MBD mRNAs and their cognate proteins were analyzed via quantitative polymerase chain reaction assays and western blotting, respectively. The relationships between the MBD expression levels and the patients' clinicopathologic variables were assessed using Student's t test, nonparametric tests, or Pearson χ2 methods. Results: Our results show that both the mRNA and protein levels of MBD2 were significantly decreased in ULs compared to the adjacent myometrium. In addition, MBD6 protein expression was also decreased significantly in UL samples when compared to the adjacent myometrium. There was, however, no significant difference on the mRNA expression of MBD6 between these two groups. Neither the mRNA nor the protein levels of the other MBD members (MBD1, MBD3, MBD4, MBD5, and MeCP2) showed any significant differences between ULs and the adjacent myometria. The decreased expression of the MBD6 protein was correlated with the tumor size of ULs. Conclusions: These results suggest that the dysregulated expression of MBD2 and MBD6 in ULs may play a role in their development; however, a larger sample size together with cellular functional assays should be carried out to further elucidate the precise role of MBD6 in ULs.

Resveratrol up-regulates ATP2A3 gene expression in breast cancer cell lines through epigenetic mechanisms.

Resveratrol (RSV) is a phytoestrogen which has been related to chemoprevention of several types of cancer. In this work, we show up to a 6-fold increased expression of ATP2A3 gene induced by RSV that triggers apoptosis and changes of intracellular Ca2+ management in MCF-7 and MDA-MB-231 breast cancer cell lines. We explored epigenetic mechanisms for that RSV-induced ATP2A3 up-regulation. The results indicate that RSV-induced ATP2A3 up-regulation correlates with about 50% of reduced HDAC activity and reduced nuclear HDAC2 expression and occupancy on ATP2A3 promoter, increasing the global acetylation of histone H3 and the enrichment of histone mark H3K27Ac on the proximal promoter of the ATP2A3 gene in MDA-MB-231 cells. We also quantified HAT activity, finding that it can be boosted with RSV treatment; however, pharmacological inhibition of p300, one of the main HATs, did not have significant effects in RSV-mediated ATP2A3 gene expression. Additionally, DNMT activity was also reduced in cells treated with RSV, as well as the expression of Methyl-DNA binding proteins MeCP2 and MBD2. However, analysis of the methylation pattern of ATP2A3 gene promoter showed un-methylated promoter in both cell lines. Taken together, the results of this work help to explain, at the molecular level, how ATP2A3 gene is regulated in breast cancer cells, and the benefits of RSV intake observed in epidemiological data, studies with animals, and in vitro models.

Fusaric acid-induced promoter methylation of DNA methyltransferases triggers DNA hypomethylation in human hepatocellular carcinoma (HepG2) cells

ABSTRACTFusaric acid (FA), a mycotoxin contaminant of maize, displays toxicity in plants and animals; however, its epigenetic mechanism is unknown. DNA methylation, an epigenetic modification that regulates gene expression, is mediated by DNA methyltransferases (DNMTs; DNMT1, DNMT3A, and DNMT3B) and demethylases (MBD2). The expression of DNMTs and demethylases are regulated by promoter methylation, microRNAs (miR-29b) and post-translational modifications (ubiquitination). Alterations in these DNA methylation modifying enzymes affect DNA methylation patterns and offer novel mechanisms of FA toxicity. We determined the effect of FA on global DNA methylation as well as a mechanism of FA-induced changes in DNA methylation by transcriptional (promoter methylation), post-transcriptional (miR-29b) and post-translational (ubiquitination) regulation of DNMTs and MBD2 in the human hepatocellular carcinoma (HepG2) cell line. FA induced global DNA hypomethylation (p < 0.0001) in HepG2 cells. FA decreased the mRNA and protein expression of DNMT1 (p < 0.0001), DNMT3A (p < 0.0001), and DNMT3B (p < 0.0001) by upregulating miR-29b (p < 0.0001) and inducing promoter hypermethylation of DNMT1 (p < 0.0001) and DNMT3B (p < 0.0001). FA decreased the ubiquitination of DNMT1 (p = 0.0753), DNMT3A (p = 0.0008), and DNMT3B (p < 0.0001) by decreasing UHRF1 (p < 0.0001) and USP7 (p < 0.0001). FA also induced MBD2 promoter hypomethylation (p < 0.0001) and increased MBD2 expression (p < 0.0001). Together these results indicate that FA induces global DNA hypomethylation by altering DNMT promoter methylation, upregulating miR-29b, and increasing MBD2 in HepG2 cells.

Upregulated exosomal miR-221/222 promotes cervical cancer via repressing methyl-CpG-binding domain protein 2.

Methyl-CpG-binding domain protein 2, a target gene of miR-221and miR-222, plays a crucial role in a large body of human cancers. In this study, we aim to explore the mechanism by which miR-221/222 promotes cervical cancer. We have analyzed mRNA expression of MeCP2 and MBD2 in cervical cancer tissues by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) and examined the expression of miR-221/222 in C33A, HeLa, and CaSki cells by Western blot. We found that the expression levels of MBD2 and MeCP2 were significantly reduced in cervical cancer samples as detected by the analysis of MeCP2 in matched tumor-normal samples of patients with cervical cancer, indicating a reduction in a significant percentage of patients. At the same time, we found that miR-221 and miR-222, which targeted MBD2, were upregulated in cervical cancer samples. To further elucidate the relation between miR-221/222 and MBD2, we used a lot of cell lines such as C33A, HeLa, and CaSki. Surprisingly, we found that the expression levels of MBD2 and MeCP2 were significantly lower in HeLa and CaSki than in C33A, as detected by qRT-PCR. Western blot analysis of MeCP2 of HeLa and CaSki was significantly lower than in C33A. MiR-221/222 was significantly higher in HeLa and CaSki than in C33A by qRT-PCR. The knockdown of miR-221/222 in HeLa and CaSki resulted in the downregulation of miR-221/222 levels, which rescued the expression levels of MBD2 and MeCP2 in HeLa and CaSki. However, transfection of miR-221/222 on C33A could upregulate the expression levels of miR-221/222 and decrease the expression levels of MBD2 and MeCP2. Our results demonstrate that the upregulated miR-221/222 promotes cervical cancer by repressing MBD2 and MeCP2.

Disruption of the MBD2-NuRD complex but not MBD3-NuRD induces high level HbF expression in human adult erythroid cells.

As high fetal hemoglobin levels ameliorate the underlying pathophysiological defects in sickle cell anemia and beta (β)-thalassemia, understanding the mechanisms that enforce silencing of fetal hemoglobin postnatally offers the promise of effective molecular therapy. Depletion of the Nucleosome Remodeling and Deacetylase complex member MBD2 causes a 10-20-fold increase in γ-globin gene expression in adult β-globin locus yeast artificial chromosome transgenic mice. To determine the effect of MBD2 depletion in human erythroid cells, genome editing technology was utilized to knockout MBD2 in Human Umbilical cord Derived Erythroid Progenitor-2 cells resulting in γ/γ+β mRNA levels of approximately 50% and approximately 40% fetal hemoglobin by high performance liquid chromatography. In contrast, MBD3 knockout had no appreciable effect on γ-globin expression. Knockdown of MBD2 in primary adult erythroid cells consistently increased γ/γ+β mRNA ratios by approximately 10-fold resulting in approximately 30-40% γ/γ+β mRNA levels and a corresponding increase in γ-globin protein. MBD2 exerts its repressive effects through recruitment of the chromatin remodeler CHD4 via a coiled-coil domain, and the histone deacetylase core complex via an intrinsically disordered region. Enforced expression of wild-type MBD2 in MBD2 knockout cells caused a 5-fold decrease in γ-globin mRNA while neither the coiled-coil mutant nor the intrinsically disordered region mutant MBD2 proteins had an inhibitory effect. Co-immunoprecipitation assays showed that the coiled-coil and intrinsically disorder region mutations disrupt complex formation by dissociating the CHD4 and the histone deacetylase core complex components, respectively. These results establish the MBD2 Nucleosome Remodeling and Deacetylase complex as a major silencer of fetal hemoglobin in human erythroid cells and point to the coiled-coil and intrinsically disordered region of MBD2 as potential therapeutic targets.

Differential expression of tescalcin by modification of promoter methylation controls cell survival in gastric cancer cells.

The EF‑hand calcium binding protein tescalcin (TESC) is highly expressed in various human and mouse cancer tissues and is therefore considered a potential oncogene. However, the underlying mechanism that governs TESC expression remains unclear. Emerging evidence suggests that TESC expression is under epigenetic regulation. In the present study, the relationship between the epigenetic modification and gene expression of TESC in gastric cancer was investigated. To evaluate the relationship between the methylation and expression of TESC in gastric cancer, the methylation status of CpG sites in the TESC promoter was analyzed using microarray with the Illumina Human Methylation27 BeadChip (HumanMethylation27_270596_v.1.2), gene profiles from the NCBI Dataset that revealed demethylated status were acquired, and real‑time methylation‑specific PCR (MSP) in gastric cancer cells was conducted. In the present study, it was demonstrated that the hypermethylation of TESC led to the downregulation of TESC mRNA/protein expression. In addition, 5‑aza‑2c‑deoxycytidine (5'‑aza‑dC) restored TESC expression in the tested gastric cancer cells except for SNU‑620 cells. ChIP assay further revealed that the methylation of the TESC promoter was associated with methyl‑CpG binding domain protein (MBD)1, histone deacetylase (HDAC)2, and Oct‑1 and that treatment with 5'‑aza‑dC facilitated the dissociation of MBD1, HDAC2, and Oct‑1 from the promoter of TESC. Moreover, silencing of TESC increased MBD1 expression and decreased the H3K4me2/3 level, thereby causing transcriptional repression and suppression of cell survival in NCI‑N87 cells; conversely, overexpression of TESC downregulated MBD1 expression and upregulated the H3K4me2 level associated with active transcription in SNU‑638 cells. These results indicated that the differential expression of TESC via the modification status of the promoter and histone methylation controled cell survival in gastric cancer cells. Overall, the present study provided a novel therapeutic strategy for gastric cancer.

Silencing of a novel lncRNA LOC105369748 suppresses the progression of hepatocellular carcinoma by sponging miR-5095 from MBD2.

A growing number of studies have suggested that long noncoding RNAs (lncRNAs) play critical roles in human malignant cancers, including hepatocellular carcinoma (HCC). However, the functions of most lncRNAs have not been elucidated in HCC. In the present study, we explored the potential functions of a novel lncRNA LOC105369748 in the HCC progression. We identified that LOC105369748 expression was significantly elevated in HCC tissues compared with normal tissues based on bioinformatics analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis and in situ hybridization (ISH) examination. Moreover, we found that the LOC105369748 overexpression was associated with poor prognosis in patients with HCC. Then we measured the effects of LOC105369748 on HCC cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT). And our results demonstrated that LOC105369748 exerted oncogenic roles. In terms of mechanism, LOC105369748 was shown to promote MBD2 expression through competitively binding to microRNA(miR)-5095 in HCC. In conclusion, our findings elucidate that the LOC105369748/miR-5095/MBD2 signaling axis regulates the HCC progression and may be a novel therapeutic avenue.

Age-related Changes in the Global DNA Methylation Profile of Oligodendrocyte Progenitor Cells Derived from Rat Spinal Cords.

Demyelination of axons plays an important role in the pathology of many spinal cord diseases and injuries. Remyelination in demyelinated lesions is primarily performed by oligodendrocyte progenitor cells (OPCs), which generate oligodendrocytes in the developing and mature central nervous system. The efficiency of remyelination decreases with age. Many reports suggest that this decline in remyelination results from impaired OPC recruitment and differentiation during aging. Of the various molecular mechanisms involved in aging, changes in epigenetic modifications have received particular attention. Global DNA methylation is a major epigenetic modification that plays important roles in cellular senescence and organismal aging. Thus, we aimed to evaluate the dynamic changes in the global DNA methylation profiles of OPCs derived from rat spinal cords during the aging process. We separated and cultured OPCs from the spinal cords of neonatal, 4-month-old, and 16-month-old rats and investigated the age-related alterations of genomic DNA methylation levels by using quantitative colorimetric analysis. To determine the potential cause of dynamic changes in global DNA methylation, we further analyzed the activity of DNA methyltransferases (DNMTs) and the expression of DNMT1, DNMT3a, DNMT3b, TET1, TET2, TET3, MBD2, and MeCP2 in the OPCs from each group. Our results showed the genomic DNA methylation level and the activity of DNMTs from OPCs derived from rat spinal cords decreased gradually during aging, and OPCs from 16-month-old rats were characterized by global hypomethylation. During OPC aging, the mRNA and protein expression levels of DNMT3a, DNMT3b, and MeCP2 were significantly elevated; those of DNMT1 were significantly down-regulated; and no significant changes were observed in those for TET1, TET2, TET3, or MBD2. Our results indicated that global DNA hypomethylation in aged OPCs is correlated with DNMT1 downregulation. Together, these data provide important evidence for partly elucidating the mechanism of age-related impaired OPC recruitment and differentiation and assist in the development of new treatments for promoting efficient remyelination.

UTX and MBD3 Epistasis Regulates Rac Gtpase Activation and Sensitizes Human Acute Myeloid Leukemia Cells to Dock Inhibition

Transcriptional plasticity is an evolving phenomenon in cancer biology. Mutational profiling alone may not suffice to dissect transcriptional dependency and underlying epigenetic vulnerabilities in tumorigenesis. Histone 3 lysine 27 (H3K27) demethylases (UTX, UTY and JMJD3) critically regulate transcriptional architecture. Recently it has been demonstrated that Utx (Kdm6a) plays tumor suppressor role in myeloid leukemogenesis through noncatalytic activity (Gozdecka M, et al., Nat Genet, 2018). Conditional (Mx1-Cre) deletion of Utx caused development of acute myeloid leukemia (AML) in ~ 60% of the mice; wherein, only Utx-/-, but not Utx+/-, aged (22 months) mice presented with AML. Paradoxically, previous report suggested that Utx conditional (Vav1-Cre) knock out male/female mice did not develop leukemia over 18 months (Tian, L., et al., Blood, 2015). In our recent report we have identified that expression of UTX is significantly increased in human primary AML, and pharmacological inhibition of H3K27 demethylase catalytic activity attenuated survival of AML cells (Boila L.D. et al,. Exp Hematol, 2017). Therefore the contribution of UTX in AML pathogenesis remains context dependent, and probably contentious, and warrants further investigations.ATP-dependent chromatin remodelers have been implicated in AML pathobiology (Chatterjee S.S., et al., Mol Cancer Res, 2018). We reported that loss of MBD3, a scaffold of NuRD chromatin remodeler, in human primary AML cells associates with nucleation of leukemic NuRD (Biswas M et al., Blood, 2017). Loss of Mbd3(Vav1-Cre) has been shown to disrupt NuRD complex integrity and causes T-cell lymphoma, suggesting tissue-specific function of NuRD (Loughran, S.J., et al., J Exp Med, 2017). Interestingly, in our present study we have identified for the first time that endogenous UTX, but not JMJD3, reversibly co-immunoprecipitates with NuRD in AML cells. These findings led us to test the hypothesis whether UTX would participate with NuRD in AML. ChIP-seq analysis in AML blasts using antibodies against UTX and CHD4 (intact ATPase component of leukemic NuRD) along with H3K27ac identified the co-localized genes. ChIP-qPCR, transcriptome, pathway analysis (P<0.001) performed in paired AML, and MBD3loss of function experiments suggested an enrichment of Dedicator of Cytokinesis (DOCK) transcripts as bona fide effectors of UTX and NuRD in AML.DOCK proteins are conserved atypical guanine nucleotide exchange factors (GEFs) for Rho GTPase activation, regulating cell motility and invasion. Earlier we had shown that small GTPases regulate myeloid leukemia cell engraftment, survival in vivo (Sengupta A et al., Blood, 2010). DOCK1 upregulation is associated with a poor prognosis in AML (Hwei, L.S., Blood, 2016). TCGA cross-cancer analysis showed that UTX is maximally expressed, whereas MBD3 is downregulated in AML among all cancer types. Consistent with this observation, DOCK expression was significantly (P<0.001) increased in MBD3loUTXhi AML cohort compared to MBD3hiUTXlo AML. Importantly, MBD3loUTXhi patients have relatively poor survival compared to MBD3hiUTXhi individuals, indicating that a combination of high UTX and low MBD3 expression could be a marker of poor prognosis in AML.Mechanistically, MBD3 deficiency caused loss of HDAC1 occupancy with a corresponding increase in UTX, CBP and H3K27ac on target DOCK loci leading to de-repression of gene expression. In agreement with this finding, loss of MBD3 resulted in ~ 2-fold increase in active Rac GTP and promoted AML cell migration to CXCL12. Interestingly, UTX silencing opposed DOCK expression, Rac activation and reversed hyper-migratory phenotype of MBD3-deficient AML cells. Together, these data account for UTX and MBD3 epistasis in regulating DOCK-Rac signalling in AML. Finally, treatment with DOCK inhibitor CPYPP dramatically inhibited survival of AML cells while having minimal effect on the survival of normal CD34+ cells. In unison, our findings highlight UTX as a putative oncogene in conjunction with leukemic NuRDand posit DOCK proteins as an important target of UTX-NuRD axis in human AML cells.To conclude, we provide evidence for MBD3-deficient NuRD in leukemia pathobiology, and inform a novel epistasis between UTX and NuRD towards maintenance of oncogenic gene expression in AML, and rationalize DOCK inhibition as a novel therapeutic modality for precision medicine in AML. DisclosuresNo relevant conflicts of interest to declare.

Abstract C47: Obesity enhances tumor colonization and promotes expression of the spliced variant MBD2_v2 and splicing factor SRSF2 in triple-negative breast cancer

Abstract Introduction: Triple-negative breast cancer (TNBC) is a molecular subtype that accounts for approximately 15-20% of invasive breast cancer diagnoses in the United States. TNBC occurs more prevalently in premenopausal African American women (AAW), and obesity coupled with chronic inflammation is a risk factor for both incidence and recurrence. TNBC is lacking therapeutic options and persons diagnosed with TNBC have the lowest 5-year survival rates among all breast cancer patients, with AAW disproportionally bearing this burden. In order to improve TNBC patient outcomes, etiologic factors driving disparities in disease progression need to be better understood. We previously showed in TNBC cell cultures that intrinsic oncogenic redox signaling promotes self-renewal capacity of cancer stem-like cells (CSC) by maintaining expression of an epigenetic reader protein and mRNA spliced variant, methyl binding domain protein 2 variant 2 (MBD2_v2). We hypothesized that obesity-induced chronic inflammation in vivo could promote a similar cancer phenotype. Methods: To study this potential phenomenon, we developed and characterized a diet-induced obesity mouse tumor xenograft (MTX) model of TNBC in C57BL/6J Rag1 (-/-) mice, a strain that maintains a functional innate immune system, to recapitulate the proinflammatory environment induced by increased adiposity. TNBC cell lines MDA-MB-468 and MDA-MB-231 were used to generate ectopic tumor xenografts in this model. Tumor colonization and growth were measured over 150 days. RT-PCR and microarray based assays were used to detect transcriptional changes in TNBC MTXs. Results: At 5 weeks post-diet consumption, mice fed a high-fat diet displayed a 5-10% increase in body weight and increased blood glucose concentration. By the end of the study high-fat fed mice displayed a 33-43% increase in body weight and appeared to have greater central adiposity post-mortem. In overweight mice relative to healthy weight controls, TNBC cell line tumor colonization rate and MBD2_v2 expression were significantly higher. Furthermore, staining for CSC marker EpCam was greater in overweight versus control MTXs, indicating that CSC self-renewal capacity could have been enhanced. Upon global gene expression analysis of overweight MTXs, we observed a significant upregulation of stem-related factors based on fold-change expression, as well as functional enrichment for RNA splicing, including SRSF2, a splicing factor that has been shown to drive MBD2_v2 expression in pluripotent stem cells. Knockdown of SRSF2 led to decreased expression of MBD2_v2 in MDA-MB-468 cells, and decreased CSC self-renewal capacity in vitro. Conclusions: Altogether these data support MBD2_v2 regulation by redox signaling, which may be driven by a proinflammatory environment in the presence of increased adiposity. Future studies will be conducted to confirm MBD2_v2's importance in obesity-related tumor colonization in in vivo overexpression and knockdown studies, and to determine its transcriptional regulatory functions in TNBC. Citation Format: Emily A. Girsch, Gregory Dyson, Cristina Mitrea, Bin Bao, Lisa Polin, Aliccia Bollig-Fischer. Obesity enhances tumor colonization and promotes expression of the spliced variant MBD2_v2 and splicing factor SRSF2 in triple-negative breast cancer [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr C47.

MBD2 Ablation Impairs Lymphopoiesis and Impedes Progression and Maintenance of T-ALL.

Aberrant DNA methylation patterns in leukemia might be exploited for therapeutic targeting. In this study, we employed a genetically deficient mouse model to explore the role of the methylated DNA binding protein MBD2 in normal and malignant hematopoiesis. MBD2 ablation led to diminished lymphocytes. Functional defects of the lymphoid compartment were also observed after in vivo reconstitution of MBD2-deficient hematopoietic stem cells (HSC). In an established model of Notch1-driven T-cell acute lymphoblastic leukemia (T-ALL), MBD2 ablation impeded malignant progression and maintenance by attenuating the Wnt signaling pathway. In clinical specimens of human T-ALL, Wnt signaling pathway signatures were significantly enhanced and positively correlated with the expression and function of MBD2. Furthermore, a number of typical Wnt signaling inhibitory genes were abnormally hypermethylated in primary human T-ALL. Abnormal activation of Wnt signaling in T-ALL was switched off by MBD2 deletion, partially by reactivating epigenetically silenced Wnt signaling inhibitors. Taken together, our results define essential roles for MBD2 in lymphopoiesis and T-ALL and suggest MBD2 as a candidate therapeutic target in T-ALL.Significance: This study highlights a methylated DNA binding protein as a candidate therapeutic target to improve the treatment of T-cell acute lymphoblastic leukemias, as a new starting point for developing epigenetic therapy in this and other lymphoid malignancies. Cancer Res; 78(7); 1632-42. ©2018 AACR.

Mbd2-CP2c loop drives adult-type globin gene expression and definitive erythropoiesis.

During hematopoiesis, red blood cells originate from the hematopoietic stem cell reservoir. Although the regulation of erythropoiesis and globin expression has been intensively investigated, the underlining mechanisms are not fully understood, including the interplay between transcription factors and epigenetic factors. Here, we uncover that the Mbd2-free NuRD chromatin remodeling complex potentiates erythroid differentiation of proerythroblasts via managing functions of the CP2c complexes. We found that both Mbd2 and Mbd3 expression is downregulated during differentiation of MEL cells in vitro and in normal erythropoiesis in mouse bone marrow, and Mbd2 downregulation is crucial for erythropoiesis. In uninduced MEL cells, the Mbd2-NuRD complex is recruited to the promoter via Gata1/Fog1, and, via direct binding through p66α, it acts as a transcriptional inhibitor of the CP2c complexes, preventing their DNA binding and promoting degradation of the CP2c family proteins to suppress globin gene expression. Conversely, during erythropoiesis in vitro and in vivo, the Mbd2-free NuRD does not dissociate from the chromatin and acts as a transcriptional coactivator aiding the recruitment of the CP2c complexes to chromatin, and thereby leading to the induction of the active hemoglobin synthesis and erythroid differentiation. Our study highlights the regulation of erythroid differentiation by the Mbd2-CP2c loop.

Induction of CD4+CD25+Foxp3+ regulatory T cells by mesenchymal stem cells is associated with RUNX complex factors.

Among the particular immunomodulation properties of mesenchymal stem cells (MSCs), one relies on their capacity to regulatory T cell (Treg) induction from effector T cells. Stable expression of Foxp3 has a dominant role in suppressive phenotype and stability of induced regulatory T cells (iTregs). How MSCs induce stable Foxp3 expression in iTregs remains unknown. We previously showed MSCs could enhance demethylation of Treg-specific demethylated region (TSDR) in iTregs in cell-cell contact manner (unpublished data). Here, we evaluated the possible effect of MSCs on the mRNA expression of Runx complex genes (Runx1, Runx3, and CBFB) that perch on TSDR in iTregs and play the main role in suppressive properties of Tregs, a regulatory pathway that has not yet been explored by MSCs. Also, we investigated the mRNA expression of MBD2 that promotes TSDR demethylation in Tregs. We first showed that in vitro MSC-iTreg induction was associated with strong mRNA modifications of genes involved in Runx complex. We next injected high doses of MSCs in a murine model of C57BL/6 into Balb/C allogeneic skin transplantation to prolong allograft survival. When splenocytes of grafted mice were analyzed, we realized that the Foxp3 expression was increased at day 5 and 10 post-graft merely in MSC-treated mice. Furthermore, Foxp3 mRNA expression was associated with modified Runx complex mRNA expression comparable to what was shown in in vitro studies. Hence, our data identify a possible mechanism in which MSCs convert conventional T cells to iTreg through strong modifications of mRNA of genes that are involved in Runx complex of Foxp3.

Human β-defensin-3 induces IL-8 release and apoptosis in airway smooth muscle cells.

Human airway smooth muscle cells (ASMCs) may have a pro-inflammatory role through the release of inflammatory mediators. Increasing evidence indicates that human β-defensins (HBDs) are related to pathogenesis of asthma. To examine the plasma level of HBD-1, HBD-2 and HBD-3 in asthmatic patients and the expression of their mouse orthologues in the lung tissue of a mouse model of chronic severe asthma. Further to investigate the effect of HBD-3 on the release of the pro-inflammatory cytokine IL-8 and to explore the mechanisms. The plasma levels of HBD-1, HBD-2 and HBD-3 from 34 healthy controls and 25 asthmatic patients were determined by ELISA. The expression of mouse β-defensins MBD-1, MBD-3 and MBD-14 in the lung tissue of asthmatic mice was detected by Western blot. The ASMCs were cultured with HBD-3 for 24hour, and then the supernatant level of IL-8 was evaluated by ELISA and the cell viability was examined by WST-1 assay. The signalling pathway was investigated with blocking antibodies or pharmacological inhibitors. The plasma levels of HBD-1 and HBD-3 were elevated in asthmatic patients, and the expression of MBD-14, the mouse orthologue for HBD-3, was increased in asthmatic mice. HBD-3-induced IL-8 production in a CCR6 receptor-specific manner and was dependent on multiple signalling pathways. Moreover, HBD-3-induced cell apoptosis concurrently, which was dependent on the ERK1/2 MAPK pathway. Mitochondrial ROS regulated both HBD-3-induced IL-8 production and cell apoptosis. These observations provide clear evidence of an important new mechanism for the promotion of airway inflammation and tissue remodelling with potential relevance for the treatment of asthma.

Screening of Tumor Suppressor Genes in Metastatic Colorectal Cancer.

Most tumor suppressor genes are commonly inactivated in the development of colorectal cancer (CRC). The activation of tumor suppressor genes may be beneficial to suppress the development and metastasis of CRC. This study analyzed genes expression and methylation levels in different stages of CRC. Genes with downregulated mRNA expression and upregulated methylation level in advanced CRC were screened as the potential tumor suppressor genes. After comparing the methylation level of screened genes, we found that MBD1 gene had downregulated mRNA expression and upregulated methylation levels in advanced CRC and continuously upregulated methylation level in the progression of CRC. Enrichment analysis revealed that genes expression in accordance with the elevated expression of MBD1 mainly located on chromosomes 17p13 and 17p12 and 8 tumor suppressor genes located on chromosome 17p13. Further enrichment analysis of transcription factor binding site identified that SP1 binding site had higher enrichment and could bind with MBD1. In conclusion, MBD1 may be a tumor suppressor gene in advanced CRC and affect the development and metastasis of CRC by regulating 8 tumor suppressor genes through binding with SP1.

Interleukin-17A (IL-17A) and IL-17F Are Critical for Antimicrobial Peptide Production and Clearance of Staphylococcus aureus Nasal Colonization.

Approximately 20% of the population is persistently colonized by Staphylococcus aureus in the nares. Th17-like immune responses mediated by the interleukin-17 (IL-17) family of cytokines and neutrophils are becoming recognized as relevant host defense mechanisms for resolution of S. aureus mucocutaneous infections. Since antimicrobial peptides are regulated by the IL-17 cytokines, we sought to determine the role of IL-17 cytokines in production of antimicrobial peptides in a murine model of S. aureus nasal carriage. We discovered that nasal tissue supernatants have antistaphylococcal activity, and mice deficient in both IL-17A and IL-17F lost the ability to clear S. aureus nasal colonization. IL-17A was found to be sufficient for nasal mBD-3 production ex vivo and was required for CRAMP, mBD-3, and mBD-14 expression in response to S. aureus colonization in vivo These data were confirmed in a clinical study of nasal secretions in which elevated levels of the human forms of these antimicrobial peptides were found in nasal secretions from healthy human subjects when they were colonized with S. aureus but not in secretions from noncolonized subjects. Together, these data provide evidence for the importance of IL-17A regulation of antimicrobial peptides and IL-17F in the clearance of S. aureus nasal carriage.