Cell-specific Moloney Murine Leukemia Research Articles

Abstract 17416: Epigenetic Regulation of Fibroblast Fate Transition in Cardiac Wound Healing

Background: Fibroblast transitioning between physiological and pathological states can define cardiac wound healing ability of the heart in response to stress. Preventing fibroblast activation and differentiation into myofibroblast formation can attenuate cardiac fibrosis and adverse cardiac remodeling. Changes in chromatin structure and accessibility are one of the essential drivers of gene expression/repression involved in myocardial injury. One such driver of chromatin remodeling is the group of polycomb proteins that alter expression of genes involved in cardiac wound healing including B cell specific Moloney murine leukemia virus integration site 1 (Bmi1), a component of the polycomb repressive complex 1 (PRC1). Bmi1 have been linked to self-renewal, proliferation, quiescence, and lineage commitment in many organs however, how Bmi1 can mediate fibroblasts states and mediate wound healing after cardiac injury is not understood. Hypothesis: Bmi1 mediates myofibroblast activation and transition, scar maturation, stability, and fibrotic responses by regulating histone marks after injury. Methods and Results: To establish the role of Bmi1 in cardiac wound healing, we developed an inducible knock out mouse model for Bmi1, which showed decrease in cardiac structure and function with maladaptive remodeling following myocardial injury. Bmi1 knockout (KO) mice showed significant decrease in ejection fraction and fractional shortening measured by echocardiography after cardiac injury. Concurrently, this significant decrease in heart function was associated with increased fibrosis and DNA damage analyzed using immunohistochemistry. Additionally, we found that the adult cardiac fibroblasts, isolated from the Bmi1 KO mice have increased expression of fibrotic genes including TGFβ, Acta2, and collagen using RTPCR analysis. Using single cell sequencing RNA and ATAC sequencing and cellular staining assays, we found significant changes in fibrotic signaling pathways of TGFβ. We found SMAD3 chromatin accessibility was increased with the loss of Bmi1 with the decrease in H2AK119Ub. Conclusion: Bmi1 mediates wound healing ability by regulating cardiac fibroblast transition after cardiac injury.

Aflatoxin B1 induced multiple epigenetic modulators in human epithelial cell lines

The compulsive and insidious secondary metabolite aflatoxin B1, produced by the opportunistic fungi Aspergillus flavus, upholds a distinguished place in midst of the toxicants causing fatal hazards to humans. Aflatoxins alter the function of host cells by inducing multiple effects through genetic and non-genetic pathways. Epigenetic mechanisms drag major attention towards finding novel and new mechanisms involved in this process. Our present work intends to study the functional expression profile of multiple epigenetic regulators. AFB1 modulates multiple epigenetic regulators like DNA methyltransferases (DMNTs), histones modifying enzymes and polycomb proteins. AFB1 upregulates the expression of DNMTs at gene and protein level in a dose dependent manner. It reduced the histone acetyl transferase (HAT) activity significantly with a remarkable increase in histone deacetylase (HDAC) activity along with an induction in expression of HDACs gene and protein in a dose dependent manner. The gene and protein expression of polycomb repressor proteins B cell specific moloney murine leukemia virus integration site 1 (BMI-1) and enhancer of zeste homolog 2 (EZH2) was significantly over expressed with enhanced trimethylation of H3K27 and ubiquitination of H2AK119. In summary, our results show impact of aflatoxin B1 on multiple epigenetic modulations known to be pivotal in oncogenic processes.

Changes and significance of B cell specific monoclonal murine leukemia virus integration site-1 and helper T cell-related cytokine in children with immune thrombocytopenia

Objective To analyze the functional changes and the clinical significance of B cell specific monoclonal murine leukemia virus integration site-1(Bmi-1 ) and Th1/Th2 cells in children with newly diagnosed immune thrombocytopenia(ITP) by testing the mRNA expressions of Bmi-1, helper T cell-related cytokine interferon(IFN)-γ and interleukin(IL)-4 in children with newly diagnosed ITP. Methods Thirty-six cases of patients with newly diagnosed ITP in the experimental group came from the inpatient and outpatient children admitted to the Department of Pediatrics of the First Affiliated Hospital of Xinxiang Medical University from April to December 2013.In the control group, 26 cases of children requiring selective operation were admitted to the Department of Pediatric Surgery during the same period.The mRNA expressions of Bmi-1, IFN-γ and IL-4 in the peripheral blood lymphocytes were detected by means of the reverse transcription-polymerase chain reaction(RT-PCR) method, and were analyzed and compared by t test and linear correlation analysis. Results (1) The mRNA expressions of Bmi-1, IFN-γ and IL-4 in peripheral blood lymphocytes in the experimental group were 2.63±0.54, 3.84±0.43 and 1.44±0.39, respectively; while the mRNA expressions of Bmi-1, IFN-γ and IL-4 in the peripheral blood lymphocytes in the control group were 3.91±0.92, 2.88±0.57 and 1.87±0.34, respectively.The levels of IFN-γ of the experimental group were significantly higher than those of the control group (P 0.05). Conclusions Bmi-1 may be involved in the pathogenesis of ITP by regulating Th cell, and Th cell dysfunction may occur in the children with ITP, and the disproportion between Th1 and Th2 may be due to the advantages of Th1. Key words: B cell specific moloney murine leukemia virus integration site-1; Helper T cells; Immune thrombocytopenia; Child

Foxl1-expressing mesenchymal cells constitute the intestinal stem cell niche.

Background & AimsIntestinal epithelial stem cells that express leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5) and/or B cell specific Moloney murine leukemia virus integration site 1 (Bmi1) continuously replicate and generate differentiated cells throughout life. Previously, Paneth cells were suggested to constitute an epithelium-intrinsic niche that regulates the behavior of these stem cells. However, ablating Paneth cells has no effect on the maintenance of functional stem cells. Here, we show definitively that a small subset of mesenchymal subepithelial cells expressing the winged-helix transcription factor forkhead box l1 (Foxl1) are a critical component of the intestinal stem cell niche.MethodsWe genetically ablated Foxl1+ mesenchymal cells in adult mice using 2 separate models by expressing either the human or simian diphtheria toxin receptor under Foxl1 promoter control.ConclusionsKilling Foxl1+ cells by diphtheria toxin administration led to an abrupt cessation of proliferation of both epithelial stem- and transit-amplifying progenitor cell populations that was associated with a loss of active Wnt signaling to the intestinal epithelium. Therefore, Foxl1-expressing mesenchymal cells constitute the fundamental niche for intestinal stem cells.

Clinical Significance of Basal-like Breast Cancer in Chinese Women in Heilongjiang Province

Our objective was to clarify the clinical and biological characteristics of basal-like breast cancer (BLBC) and non-basal-like breast cancer (TN3BKE) in Heilongjiang. We examined, by immunohistochemistry, expression of biological markers cytokeratin (CK) 5/6 and epidermal growth factor receptor (EGFR) and B cell specific moloney murine leukemia virus integration site 1( Bmi-1) in triple-negative breast cancer (TNBC). We studied the correlation between BLBC and several factors related to tumor progression, along with its prognostic value. In the 229 cases of operable TNBC, BLBC was detected in 178 (77.7%) and TN3BKE- in 51 (22.2%). There was no significant difference in clinicopathological factors between them, However, BLBC was significantly associated with Bmi-1 expression (P=0.000) and shorter disease-free survival (DFS) (P = 0.045) and overall survival (OS) (P=0.041). Compared with the non-basal group, patients with BLBC have a high expression of Bmi-1 and a poor prognosis.

Abstract 5325: Role of MUC13 in colon cancer progression

Abstract Colon cancer is the third most commonly diagnosed and second leading cause of cancer related deaths in the United States. Mucin 13 (MUC13), a high molecular weight glycoprotein, is a recently identified transmembrane mucin. While MUC13 is known to be over expressed in gastric and ovarian cancers, limited information about MUC13 is available in colon cancer progression. Therefore, our aim is to investigate the expression profile, potential role and possible regulatory pathways of MUC13 in colon cancer progression. We performed immunohistochemical analysis using MUC13 monoclonal antibody (ppz0020) to determine expression profile and aberrant localization of MUC13 in colon cancer cells. Our results indicate that MUC13 is over expressed in colon cancer predominantly at the apical surface. MUC13 is also aberrantly localized (cytoplasmic and nuclear) in metastasized colon cancer and in liver metastasis. We also correlated MUC13 expression levels with clinico-pathological parameters of patients. Increased MUC13 expression correlated with increased tumor size and poorly differentiated colon cancer. To determine the functional roles of MUC13 we generated stable MUC13 over expressing and MUC13 knock down cells and performed functional assays. Our results demonstrate that MUC13 increased cell proliferation, colony formation, cell migration and cell invasion characteristics of colon cancer cells. In order to investigate proteins that are affected by MUC13, we performed immunoblot assays. Immunoblot analysis revealed that MUC13 increased expression of several proteins that are associated with colon cancer progression and metastasis such as Bmi-1(B cell specific lymphoma moloney murine leukemia integration site-1), TERT (telomerase reverse transcriptase), Shh (sonic hedgehog) and GATA1 (GATA binding protein 1). We also examined potential signaling pathways that may be associated with MUC13 colon carcinogenesis. We found that MUC13 increased expression of mitogen activated kinase (MAPK) pathway members such as ERK-1 and phospho ERK-1. In order to determine potential transcriptions factors that may regulate MUC13 expression, we screened expression of various transcription factors by real time PCR. Significantly high expression of STAT5B (signal transducers and activators of transcription factor 5B) was detected in cell lines expressing endogenously high levels of MUC13. In order to confirm transcription factor STAT5B binding sites in the MUC13 promotor, we performed chromatin immunoprecipitation (CHIP). CHIP analysis revealed that STAT5B binds to the promoter of MUC13. In summary, our study revealed that MUC13 is over expressed in colon cancer and aberrantly localized in metastasis. Over expression of MUC13 increases cell proliferation, colony formation, cell migration, cell invasion and expression of metastasis associated proteins partly via MAPK pathway. MUC13 expression may be regulated through binding of STAT5B to the MUC13 promoter. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5325. doi:1538-7445.AM2012-5325