Murine Leukemia Virus Integration Site 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.

Human embryonic stem cell-derived mesenchymal stem cell secretome reverts silica-induced airway epithelial cell injury by regulating Bmi1 signaling.

Silicosis is an irreversible chronic pulmonary disease caused by long-term inhalation and deposition of silica particles, which is currently incurable. The exhaustion of airway epithelial stem cells plays a pathogenetic role in silicosis. In present study, we investigated therapeutic effects and potential mechanism of human embryonic stem cell (hESC)-derived MSC-likes immune and matrix regulatory cells (IMRCs) (hESC-MSC-IMRCs), a type of manufacturable MSCs for clinical application in silicosis mice. Our results showed that the transplantation of hESC-MSC-IMRCs led the alleviation of silica-induced silicosis in mice, accompanied by inhibiting epithelia-mesenchymal transition (EMT), activating B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) signaling and airway epithelial cell regeneration. In consistence, the secretome of hESC-MSC-IMRC exhibited abilities to restore the potency and plasticity of primary human bronchial epithelial cells (HBECs) proliferation and differentiation following the SiO2 -induced HBECs injury. Mechanistically, the secretome resolved the SiO2 -induced HBECs injury through the activation of BMI1 signaling and restoration of airway basal cell proliferation and differentiation. Moreover, the activation of BMI1 significantly enhanced the capacity of HBEC proliferation and differentiation to multiple airway epithelial cell types in organoids. Cytokine array revealed that DKK1, VEGF, uPAR, IL-8, Serpin E1, MCP-1 and Tsp-1 were the main factors in the hESC-MSC-IMRC secretome. These results demonstrated a potential therapeutic effect of hESC-MSC-IMRCs and their secretome for silicosis, in part through a mechanism by activating Bmi1 signaling to revert the exhaustion of airway epithelial stem cells, subsequentially enhance the potency and plasticity of lung epithelial stem cells.

Hairy gene homolog increases nasopharyngeal carcinoma cell stemness by upregulating Bmi-1

B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) is overexpressed in various cancer types. We found that Bmi-1 mRNA levels were elevated in nasopharyngeal carcinoma (NPC) cell lines. In immunohistochemical analyses, high Bmi-1 levels were observed in not only 5 of 38 non-cancerous nasopharyngeal squamous epithelial biopsies, but also in 66 of 98 NPC specimens (67.3%). High Bmi-1 levels were detected more frequently in T3-T4, N2-N3 and stage III-IV NPC biopsies than in T1-T2, N0-N1 and stage I-II NPC samples, indicating that Bmi-1 is upregulated in advanced NPC. In 5-8F and SUNE1 NPC cells, stable depletion of Bmi-1 using lentiviral RNA interference greatly suppressed cell proliferation, induced G1-phase cell cycle arrest, reduced cell stemness and suppressed cell migration and invasion. Likewise, knocking down Bmi-1 inhibited NPC cell growth in nude mice. Both chromatin immunoprecipitation and Western blotting assays demonstrated that Hairy gene homolog (HRY) upregulated Bmi-1 by binding to its promoter, thereby increasing the stemness of NPC cells. Immunohistochemistry and quantitative real-time PCR analyses revealed that HRY expression correlated positively with Bmi-1 expression in a cohort of NPC biopsies. These findings suggested that HRY promotes NPC cell stemness by upregulating Bmi-1, and that silencing Bmi-1 can suppress NPC progression.

A transverse colon lipoma complicated with an adenoma is successfully and safely resected en bloc by endoscopic mucosal resection during water immersion

The B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) is associated with the progression of gastric cancer (GC). However, its role in drug resistance of gastric cancer stem cell (GCSC) remains unclear. This study aimed to explore the biological function of BMI-1 in GC cells and its role in drug resistance of GCSCs.We assessed BMI-1 expression in the GEPIA database and in our collected samples from patients with GC. We silenced BMI-1 using siRNA to study the cell proliferation and migration of GC cells. We also used Hoechst 33342 staining to verify the effect of adriamycin (ADR) on side population (SP) cells, and measured the effects of BMI-1 on the expression of N-cadherin, E-cadherin, and drug-resistance-related proteins (multidrug resistance mutation 1 and lung resistance-related protein). Finally, we analyzed BMI-1-related proteins uing the STRING and GEPIA databases.BMI-1 mRNA was upregulated in GC tissues and cell lines, especially in MKN-45 and HGC-27 cells. Silencing BMI-1 reduced the proliferation and migration of GC cells. Knocking down BMI-1 significantly decreased epithelial-mesenchymal transition progression, expression levels of drug-resistant proteins, and the number of SP cells in ADR-treated GC cells. Bioinformatics analysis showed that EZH2, CBX8, CBX4, and SUZ12 were positively correlated with BMI-1 in GC tissues.Our study demonstrates that BMI-1 affects the cellular activity, proliferation, migration, and invasion of GC cells. Silencing the BMI-1 gene significantly reduces the number of SP cells and the expression of drug-resistant proteins in ADR-treated GC cells. We speculate that inhibition of BMI-1 increases the drug resistance of GC cells by affecting GCSCs, and that EZH2, CBX8, CBX4, and SUZ12 may participate in BMI-1-induced enhancement of GCSC-like phenotype and viability.

BMI1 fine-tunes gene repression and activation to safeguard undifferentiated spermatogonia fate.

Introduction: Spermatogenesis is sustained by the homeostasis of self-renewal and differentiation of undifferentiated spermatogonia throughout life, which is regulated by transcriptional and posttranscriptional mechanisms. B cell-specific Moloney murine leukemia virus integration site 1 (BMI1), one of spermatogonial stem cell markers, is a member of Polycomb repressive complex 1 (PRC1) and important to spermatogenesis. However, the mechanistic underpinnings of how BMI1 regulates spermatogonia fate remain elusive. Methods: We knocked down BMI1 by siRNA to investigate the role of BMI1 in undifferentiated spermatogonia. Differentially expressed genes were identified by RNA-seq and used for KEGG pathway analysis. We performed ChIP-seq analysis in wild type and BMI1 knockdown cells to explore the underlying molecular mechanisms exerted by BMI1. BMI1-associated alterations in repressive histone modifications were detected via Western blotting and ChIP-seq. Furthermore, we performed mass spectrometry and Co-immunoprecipitation assays to investigate BMI1 co-factors. Finally, we demonstrated the genomic regions occupied by both BMI1 and its co-factor. Results: BMI1 is required for undifferentiated spermatogonia maintenance by both repressing and activating target genes. BMI1 preserves PI3K-Akt signaling pathway for spermatogonia proliferation. Decrease of BMI1 affects the deposition of repressive histone modifications H2AK119ub1 and H3K27me3. BMI also positively regulates H3K27ac deposited genes which are associated with proliferation. Moreover, we demonstrate that BMI1 interacts with Sal-like 4 (SALL4), the transcription factor critical for spermatogonia function, to co-regulate gene expression. Discussion: Overall, our study reveals that BMI1 safeguards undifferentiated spermatogonia fate through multi-functional roles in regulating gene expression programs of undifferentiated spermatogonia.

B-cell-specific Moloney murine leukemia virus integration site 1 knockdown impairs adriamycin resistance of gastric cancer cells

Background and study aimsThe B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) is associated with the progression of gastric cancer (GC). However, its role in drug resistance of gastric cancer stem cell (GCSC) remains unclear. This study aimed to explore the biological function of BMI-1 in GC cells and its role in drug resistance of GCSCs. Patients and methodsWe assessed BMI-1 expression in the GEPIA database and in our collected samples from patients with GC. We silenced BMI-1 using siRNA to study the cell proliferation and migration of GC cells. We also used Hoechst 33342 staining to verify the effect of adriamycin (ADR) on side population (SP) cells, and measured the effects of BMI-1 on the expression of N-cadherin, E-cadherin, and drug-resistance-related proteins (multidrug resistance mutation 1 and lung resistance-related protein). Finally, we analyzed BMI-1-related proteins uing the STRING and GEPIA databases. ResultsBMI-1 mRNA was upregulated in GC tissues and cell lines, especially in MKN-45 and HGC-27 cells. Silencing BMI-1 reduced the proliferation and migration of GC cells. Knocking down BMI-1 significantly decreased epithelial-mesenchymal transition progression, expression levels of drug-resistant proteins, and the number of SP cells in ADR-treated GC cells. Bioinformatics analysis showed that EZH2, CBX8, CBX4, and SUZ12 were positively correlated with BMI-1 in GC tissues. ConclusionOur study demonstrates that BMI-1 affects the cellular activity, proliferation, migration, and invasion of GC cells. Silencing the BMI-1 gene significantly reduces the number of SP cells and the expression of drug-resistant proteins in ADR-treated GC cells. We speculate that inhibition of BMI-1 increases the drug resistance of GC cells by affecting GCSCs, and that EZH2, CBX8, CBX4, and SUZ12 may participate in BMI-1-induced enhancement of GCSC-like phenotype and viability.

Targeted Degradation of PRC1 Components, BMI1 and RING1B, via a Novel Protein Complex Degrader Strategy.

Polycomb repressive complex 1 (PRC1) is an essential epigenetic regulator that mainly controls histone H2A Lys119 mono-ubiquitination (H2AK119ub). B cell-specific Moloney murine leukemia virus Integration site 1 (BMI1) and really interesting new gene 1B (RING1B) are PRC1 core components and play critical roles in the development of various cancers. However, therapeutic agents targeting PRC1 are very limited. In this study, MS147, the first degrader of PRC1 core components, BMI1 and RING1B, is discovered via a novel protein complex degradation strategy that utilizes the target protein's interacting partner protein (embryonic ectoderm development (EED)). MS147, which comprises an EED small-molecule binder linked to a ligand of the E3 ligase von Hippel-Lindau (VHL), degrades BMI1/RING1B in an EED-, VHL-, ubiquitination-, and time-dependent manner. MS147 preferentially degrades BMI1/RING1B over polycomb repressive complex 2 (PRC2) core components. Consequently, MS147 effectively reduces H2AK119ub, but not histone H3 Lys27 tri-methylation (H3K27me3), which is catalyzed by PRC2. Furthermore, MS147 effectively inhibits the proliferation of cancer cell lines that are insensitive to PRC2 inhibitors/degraders. Overall, this study provides a novel BMI1/RING1B degrader, which is a useful chemical tool to further investigate the roles of PRC1 in cancer, and a novel protein complex degradation strategy, which can potentially expand the degradable human proteome.

Sonic Hedgehog and WNT Signaling Regulate a Positive Feedback Loop Between Intestinal Epithelial and Stromal Cells to Promote Epithelial Regeneration

Active intestinal stem cells are prone to injury by ionizing radiation. We previously showed that upon radiation-induced injury, normally quiescent reserve intestinal stem cells (rISCs) (marked by BMI1) are activated by Musashi-1 (MSI1) and exit from the quiescent state to regenerate the intestinal epithelium. This study aims to further establish the mechanism that regulates activation of Bmi1-CreER;Rosa26eYFP (Bmi1-CreER) rISCs following γ radiation-induced injury. Bmi1-CreER mice were treated with tamoxifen to initiate lineage tracing of BMI1 (eYFP+) cells and exposed to 12 Gy of total body γ irradiation or sham. Intestinal tissues were collected and analyzed by immunofluorescence, Western blot, reverse-transcription quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and chromatin immunoprecipitation real-time polymerase chain reaction. After irradiation, increased expression of Msi1 in eYFP+ cells was accompanied by increased expression of Axin2, a WNT marker. Promoter studies of the Msi1 gene indicated that Msi1 is a WNT target gene. Coculture of stromal cells isolated from irradiated mice stimulated Bmi1-CreER-derived organoid regeneration more effectively than those from sham mice. Expression of WNT ligands, including Wnt2b, Wnt4, Wnt5a, and Rspo3, was increased in irradiated stromal cells compared with sham-treated stromal cells. Moreover, expression of the Sonic hedgehog (SHH) effector Gli1 was increased in stromal cells from irradiated mice. This was correlated with an increased expression of SHH in epithelial cells postirradiation, indicating epithelial-stromal interaction. Finally, preinjury treatment with SHH inhibitor cyclopamine significantly reduced intestinal epithelial regeneration and Msi1 expression postirradiation. Upon ionizing radiation-induced injury, intestinal epithelial cells increase SHH secretion, stimulating stromal cells to secrete WNT ligands. WNT activators induce Msi1 expression in the Bmi1-CreER cells. This stromal-epithelial interaction leads to Bmi1-CreER rISCs induction and epithelial regeneration.

A novel association between Bmi-1 protein expression and the SUVmax obtained by 18F-FDG PET/CT in patients with gastric adenocarcinoma.

This study aimed to examine B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) in gastric adenocarcinoma (GAC) and its association with the maximal standard uptake value (SUVmax) of preoperative fluorine-18-fludeoosyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Clinicopathological data were retrospectively collected from 60 primary GAC patients. The Bmi-1 protein expression in GAC and adjacent noncancerous tissues was examined by immunohistochemistry and western blot analysis. Pearson's correlation analysis was conducted to assess the correlation between Bmi-1 expression and the SUVmax. The Bmi-1 protein levels were significantly greater in GAC versus noncancerous tissues, and higher Bmi-1 was significantly correlated with a lower degree of tumor differentiation, higher tumor stages, more lymph node metastasis, and depth of invasion. The SUVmax value was significantly correlated with the T stage, N stage, and clinical stage, but not with age, gender, tumor size, histological differentiation degree, or Lauren classification. Moreover, a significant positive correlation between Bmi-1 and SUVmax was observed in GAC tissues. In conclusion, our findings demonstrate a novel correlation between Bmi-1 and preoperative SUVmax in GAC patients who did not receive radiotherapy, chemotherapy, or targeted treatment before surgery, and both are positively correlated with unfavorable prognostic factors and a higher grade of malignancy.

MicroRNA-429 Regulates Invasion and Migration of Multiple Myeloma Cells via Bmi1/AKT Pathway

Background: miR-429-mediated progression of multiple myeloma (MM) was studied through mediating B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1)/protein kinase B (AKT) pathway. Methods: miRNA or siRNA was delivered into MM cell lines to alter cellular proliferation, apoptosis, invasion and migration. Measurements of miR-429 and Bmi1 levels were performed. AKT and p-AKT expression change was measured after regulating miR-429. The interaction between miR-429 and Bmi1 was analyzed. Results: miR-429 elevation disrupted proliferation, anti-apoptosis, migration and invasion properties of MM cells, and inactivated AKT pathway. Bmi1 was a targeting partner of miR-429, which was highly expressed in MM. Bmi1 knockdown phenotyped the effects of overexpressed miR-429 on MM cells. AKT agonist SC70 reversed miR-429-regulated inhibition of MM cell growth. Conclusion: miR-429 suppresses the activation of Bmi1/AKT pathway to down-regulate the malignant functions of MM cells.

BMI-1 promotes breast cancer proliferation and metastasis through different mechanisms in different subtypes.

Breast cancer is among the most common malignant cancers in women. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) is a transcriptional repressor that has been shown to be involved in tumorigenesis, the cell cycle, and stem cell maintenance. In our study, increased expression of BMI-1 was found in both human triple negative breast cancer and luminal A-type breast cancer tissues compared with adjacent tissues. We also found that knockdown of BMI-1 significantly suppressed cell proliferation and migration in vitro and in vivo. Further mechanistic research demonstrated that BMI-1 directly bound to the promoter region of CDKN2D/BRCA1 and inhibited its transcription in MCF-7/MDA-MB-231. More importantly, we discovered that knockdown of CDKN2D/BRCA1 could promote cell proliferation and migration after repression by PTC-209. Our results reveal that BMI-1 transcriptionally suppressed BRCA1 in TNBC cell lines whereas, in luminal A cell lines, CDKN2D was the target gene. This provides a reference for the precise treatment of different types of breast cancer in clinical practice.

Chlorogenic acid for cancer prevention and therapy: Current status on efficacy and mechanisms of action

Chlorogenic acid (CA), also known as 5-O-caffeoylquinic acid, is a dietary phenolic acid produced by various plant species. CA, is the most ubiquitous compound among the phenolic acid group, is also present in tea and green coffee extracts. Its consumption reduces the risk of numerous diseases as validated by preclinical and clinical studies. CA possesses a wide range of pharmacological properties, such as hepatoprotective, antimicrobial, immunomodulatory, antioxidant, antidiabetic, and anticancer activities. It has been extensively used in the food, chemical, medicine, and health care industries. Available reports revealed that CA can exert anticancer activity by inhibiting the cell cycle, triggering apoptosis, and suppressing the proliferation of cancer cells. It upregulates the expression of nuclear factor of activated T cells 2 (NFATC2) and NFATC3 genes involved in immune pathway and downregulates B cell-specific moloney murine leukemia virus integration site 1 protein and SRY-box transcription factor 2 gene expression to facilitate tumor cell destruction. It promotes intracellular DNA impairment and topoisomerase I- and topoisomerase-II-DNA complex formation that perform a key function in apoptosis. In addition, CA has been documented to be an effective natural anticancer drug and was approved by the China Food and Drug Administration. Several previously published reports have provided fragmented summary of various anticancer activities of CA. Therefore, this review aims to deliver up-to-date and comprehensive assessment about the natural sources of CA, its bioavailability, metabolism, and anticancer property with an emphasis on the molecular mechanisms associated with several signaling pathways in tumor cells.

EPCT-05. Phase Ib study of unesbulin (PTC596) in children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) and high-grade glioma (HGG): A report from the COllaborative Network for NEuro-Oncology Clinical Trials (CONNECT)

BACKGROUND: The B-cell-specific Moloney murine leukemia virus integration site-1 (BMI-1) protein, implicated in self-renewal and DNA-damage signaling, is highly expressed in DIPG and HGG. Preclinically, BMI-1 modulation by unesbulin (PTC596 [which mediates hyperphosphorylation and subsequent degradation of BMI-1]) leads to DIPG/HGG cell proliferation blockade, mitotic abnormalities, and tumor cell sensitization to radiation-induced DNA damage. METHODS: This phase Ib study sought to determine the maximally tolerated dose/ recommended phase 2 dose (RP2D) of unesbulin administered concurrently with radiotherapy and adjuvantly in children with newly diagnosed DIPG or HGG. Patients were enrolled according to a Rolling-6 design and received oral unesbulin twice weekly during radiotherapy and as maintenance therapy. RESULTS: Twenty-seven patients enrolled (median age: 8.5 years [range: 2-18]), including 18 patients with DIPG and nine patients with HGG. Unesbulin was administered in capsule formulation in the first nine patients, then tablet formulation for subsequent patients. Within the capsule formulation group, three dose-limiting toxicities (DLTs) were observed in two patients on dose level 2 (grade 4 neutropenia). Within the tablet formulation group, four DLTs were experienced by three patients on dose level 2 (grade 3 ALT elevation, grade 3 dehydration/vomiting, grade 3 decreased ejection fraction, grade 4 neutropenia). Dose level 1 was declared the RP2D, and six additional patients enrolled in the expansion cohort at this dose without DLTs. Most common drug-related grade 3/4 toxicities were neutropenia (48%), leucopenia (35%), and elevated ALT (26%). Similar pharmacokinetic profiles were observed for capsule and tablet formulations, consistent with adult data. Survival outcomes and genomics results will be shared at time of presentation. CONCLUSIONS: The RP2D of unesbulin in children newly diagnosed with DIPG or HGG is 200mg/m2 twice weekly, concurrent with and following radiotherapy. The recently opened surgical cohort will assess intratumoral pharmacokinetics and inhibition of tumor BMI-1 signaling, with results forthcoming.

BMI1 Silencing Induces Mitochondrial Dysfunction in Lung Epithelial Cells Exposed to Hyperoxia.

Acute Lung Injury (ALI), characterized by bilateral pulmonary infiltrates that restrict gas exchange, leads to respiratory failure. It is caused by an innate immune response with white blood cell infiltration of the lungs, release of cytokines, an increase in reactive oxygen species (ROS), oxidative stress, and changes in mitochondrial function. Mitochondrial alterations, changes in respiration, ATP production and the unbalancing fusion and fission processes are key events in ALI pathogenesis and increase mitophagy. Research indicates that BMI1 (B cell-specific Moloney murine leukemia virus integration site 1), a protein of the Polycomb repressive complex 1, is a cell cycle and survival regulator that plays a role in mitochondrial function. BMI1-silenced cultured lung epithelial cells were exposed to hyperoxia to determine the role of BMI1 in mitochondrial metabolism. Its expression significantly decreases in human lung epithelial cells (H441) following hyperoxic insult, as determined by western blot, Qrt-PCR, and functional analysis. This decrease correlates with an increase in mitophagy proteins, PINK1, Parkin, and DJ1; an increase in the expression of tumor suppressor PTEN; changes in the expression of mitochondrial biomarkers; and decreases in the oxygen consumption rate (OCR) and tricarboxylic acid enzyme activity. Our bioinformatics analysis suggested that the BMI1 multifunctionality is determined by its high level of intrinsic disorder that defines the ability of this protein to bind to numerous cellular partners. These results demonstrate a close relationship between BMI1 expression and mitochondrial health in hyperoxia-induced acute lung injury (HALI) and indicate that BMI1 is a potential therapeutic target to treat ALI and Acute Respiratory Distress Syndrome.

Bmi-1 directly upregulates glucose transporter 1 in human gastric adenocarcinoma.

This study aimed to investigate whether and how Moloney murine leukemia virus integration site 1 (Bmi-1) plays a role in the regulation of glucose transporter 1 (GLUT1) in gastric adenocarcinoma (GAC). GAC and matched noncancerous tissues were obtained from GAC patients who underwent surgical treatment at the China-Japan Union Hospital, Jilin University (Changchun, Jilin, China). The human GAC cell line AGS and the gastric epithelial cell line GES-1 were used for in vitro studies. BALB/c nude mice were used for in vivo studies. The Bmi-1 and GLUT1 protein levels were significantly greater in human tissues from GAC patients and AGS cells in comparison with controls. Silencing of Bmi-1 resulted in significant decrease in glucose uptake, lactate levels, and GLUT1 expression. In vivo 18F-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) imaging studies indicated that the nude mice bearing xenografts of AGS cells treated with Bmi-1-specific small interfering RNA (siRNA) had a significantly lower maximum standardized uptake value (SUVmax) in comparison with the control mice. Thus, Bmi-1 directly upregulates GLUT1 gene expression, through which it is involved in enhancing glucose uptake in GAC. The results also provide scientific evidence for 18F-FDG PET/CT imaging to evaluate Bmi-1 and glucose uptake in GAC.

Bmi1 signaling maintains the plasticity of airway epithelial progenitors in response to persistent silica exposures

Silicosis is caused by the continuous inhalation of environmental silica dust. The repetitive exposure of silica induces airway epithelial cell injury, leads proliferative exhaustion of epithelial stem cells, ultimately results in the lung remodeling and the development of silicosis. The B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) is a pivotal transcription factor in stem cell self-renewal and proliferation of many tissues including the lung, but its role in the airway basal cell proliferation and differentiation during the pathogenesis of silicosis in lung has yet been investigated. In this study, the function of Bmi1 in airway basal cell proliferation and differentiation in response to silica challenge was investigated in lungs of silicosis mice and primary human bronchial epithelia cells (HBECs) exposed to silica dioxide (SiO2). Results showed a decreased expression of Bmi1 protein, epithelial basal cell markers Krt14 and Krt5, club cell marker Clara cell secretory protein, and ciliated cell marker acetyl-α-tubulin in silicosis lungs, compared to healthy mice. In consistence, a persistent exposure of SiO2 reduced the capacity of cell proliferation and differentiation in HBECs, as ascertained by the reduction of differentiated epithelial cell markers and BMI1 expression, while an increased P21-positive senescent cell fraction. Moreover, an overexpression of BMI1 in HBECs reduced the SiO2-senescent cells, enhanced the potency of cell proliferation and differentiation, and increased capacity of airway epithelial regeneration in response to the persistent exposure of SiO2. These data suggest that Bmi1 is a key transcription factor engaging in maintaining the self-renewal, proliferation and differentiation of epithelial stem cells in lung during the development of silicosis disease.

Specific overexpression of SIRT1 in mesenchymal stem cells rescues hematopoiesis niche in BMI1 knockout mice through promoting CXCL12 expression.

Osteoblastic lineage cells (OBCs) are bone-building cells and essential component of hematopoietic niche, but mechanisms whereby bone-building and hematopoiesis-supportive activities of OBCs could be regulated simultaneously remain largely unknown. Here we found that B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) was involved in such a co-regulatory mechanism. In this study, we first found that, accompanied with marked decline of osteogenic activity, the hematopoietic niche in Bmi1 knockout (KO) mice was severely impaired and manifested as CXCL12 expression falls and LSK homing failure; however, intratibial injection with CXCL12 effectively facilitated LSK accumulation in bone marrow of Bmi1 KO mice. To try to rescue these defects in Bmi1 KO mice, we generated Bmi1KO/Sirt1Tg (KO-TG) double mutant mice with Sirt1 specific overexpression in mesenchymal progenitor cells (MPCs) in Bmi1 KO mice, and our data showed that KO-TG mice had significantly increased bone-building activity, elevated Cxcl12 expression by MPCs, increased LSK homing and expanded LSK pool in bone marrow compared to Bmi1 KO mice. Of note, similar improvements in KO-TG mice were observed in Bmi1 KO mice fed with dietary resveratrol, an established Sirt1 activator, comparing with KO control mice. Therefore, pharmacologic activation of Bmi1/Sirt1 signaling pathway could simultaneously promote bone-building and hematopoiesis-supportive activities of OBCs.

The combination phenotype of B-cell specific Moloney murine leukaemia virus integration site 1 (BMI1) and CD44+/CD24−/low associates with poor clinicopathological features in African patients with breast cancer

Cancer stem cell theory has revolutionalised breast cancer (BC) treatment and prognosis. The role of B cell specific Moloney murine leukaemia virus integration site 1 (BMI1) cancer stem cell marker in BC is not entirely understood. Herein, we have studied the association between BMI1, its combination phenotypes with other breast cancer stem cells and BC behaviour in a cohort of African patients.Tissue microarray of BC cohort (n = 222) from Ghanaian patients was immunohistochemically stained for BMI1. The associations between BMI1, clinicopathological features, other cancer stems cell markers and outcome were analysed using Pearson's chi-square, and Kaplan Meier's log rank-test.High expression of BMI1 was observed in 85% of cases. CD44+/CD24−/low/BMI1+ phenotype was associated with unfavourable clinicopathological features including higher tumour grade (p = 0.013), larger tumour size (p = 0.048), and high clinical prognostic stage (p = 0.018). However, the CD44+CD24−/lowBMI1− was the only phenotype that showed improved BCSS.BMI1 may contribute to the inherent tumour aggressiveness of African BC. Additional functional studies are warranted to identify the underlying mechanisms and the role of stem cell network in BC development and behaviour.

The inhibition of circular RNA circNOLC1 by propofol/STAT3 attenuates breast cancer stem cells function via miR-365a-3p/STAT3 signaling

BackgroundBreast cancer remains one of the most dreadful female malignancies globally, in which cancer stem cells (CSCs) play crucial functions. Circular RNAs have drawn great attention in cancer research area and propofol is a widely applied intravenous anesthetic agent. Methods: In the current study, we explored the function of circular RNA nucleolar and coiled-body phosphoprotein 1 (circNOLC1) in CSCs of breast cancer and the inhibitory impact of propofol on circNOLC1.ResultsThe expression of circNOLC1 was induced in breast cancer tissues compared with the non-tumor tissues. The silencing of circNOLC1 was able to repress the viability of breast cancer cells. Meanwhile, the numbers of colony formation were suppressed by circNOLC1 knockdown in breast cancer cells. The inhibition of circNOLC1 reduced the invasion and migration ability of breast cancer cells. The mRNA and protein levels of E-cadherin were enhanced but Vimentin levels were reduced by the silencing of circNOLC1. The repression of circNOLC1 decreased the side population (SP) ratio in breast cancer cells. Meanwhile, the sphere formation ability of breast cancer cells was attenuated by the silencing of circNOLC1. The levels of ATP-binding cassette (ABC) superfamily G member 2 (ABCG2), c-Myc, B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1), and SRY-box transcription factor 2 (Sox2) were repressed by the depletion of circNOLC1 in the cells. Regarding to the mechanism, circNOLC1 functioned as a competing endogenous RNAs (ceRNAs) for microRNA-365a-3p (miR-365a-3p) and the inhibition of miR-365a-3p rescued circNOLC1 depletion-repressed proliferation and cancer stem cell activity of breast cancer. MiR-365a-3p targeted signal transducer and activator of transcription 3 (STAT3) in breast cancer cells and circNOLC1 enhanced STAT3 expression by sponging miR-365a-3p. The overexpression of STAT3 could reverse miR-365a-3p or circNOLC1 depletion-inhibited proliferation and cancer stem cell properties of breast cancer. Interestingly, the expression of circNOLC1 and STAT3 was repressed by the treatment of propofol. The enrichment of STAT3 on circNOLC1 promoter was inhibited by propofol. The expression of circNOLC1 was suppressed by the silencing of STAT3 in the cells. The inhibition of circNOLC1 expression by propofol was rescued under the co-treatment of STAT3 overexpression. The overexpression of circNOLC1 rescued propofol-attenuated proliferation and cancer stem cell functions in vitro and in vivo.ConclusionsThus, we concluded that circNOLC1 contributes to CSCs properties and progression of breast cancer by targeting miR-365a-3p /STAT3 axis and propofol inhibited circNOLC1 by repressing STAT3 in a feedback mechanism.

Acute lymphoblastic leukemia in children and SALL4 and BMI-1 gene expression.

Sal-like protein 4 transcription factor (SALL4) and B cell-specific Moloney murine leukemia virus integration site 1 (BMI-1) gene were reported to cause treatment failure and relapse in several malignancies. We aimed to evaluate the prognostic value of SALL4 and BMI-1 in children with acute lymphoblastic leukemia (ALL). This prospective cohort study was carried out on 60 children with ALL as the patient group and 60 age- and sex-matched children as the control group. We evaluated the expression pattern of both SALL4 and BMI-1 genes in the peripheral blood using real-time reverse transcriptase-polymerase chain reaction in children with ALL at initial diagnosis before chemotherapy. We followed up with the patient group for 2 years for relapse or death. Both SALL4 and BMI-1 were overexpressed in ALL children compared to the control group. Moreover, the expression of SALL4 and BMI-1 in patients with relapse was significantly higher than those with complete remission. The best cut-off of SALL4 and BMI-1 to predict relapse were >2.21 and 0.55 yielding sensitivity of 92.3% and 84.6%, respectively. Patients with overexpression of SALL4 and BMI-1 had significantly shorter overall and disease-free survival. SALL4 and BMI-1 could be useful prognostic markers in children with ALLto predict relapse.