Development of gemcitabine-modified miRNA mimics as cancer therapeutics for pancreatic ductal adenocarcinoma.

Despite the recent advancement in diagnosis and therapy, pancreatic ductal adenocarcinoma (PDAC), the most common type of pancreatic cancer, is still the most lethal cancer with a low five-year survival rate. There is an urgent need to develop new therapies to address this issue. In this study, we developed a treatment strategy by modifying tumor suppressor miRNAs, miR-15a and miR-194, with the chemotherapeutic gemcitabine (Gem) to create Gem-modified mimics, Gem-miR-15a and Gem-miR-194, respectively. In a panel of PDAC cell lines, we found that Gem-miR-15a and Gem-miR-194 induce cell-cycle arrest and apoptosis, and these mimics are potent inhibitors with IC50 values up to several hundred fold less than their native counterparts or Gem alone. Furthermore, we found that Gem-miR-15a and Gem-miR-194 retained miRNA function by downregulating the expression of several key targets including WEE1, CHK1, BMI1, and YAP1 for Gem-miR-15a, and FOXA1 for Gem-miR-194. We also found that our Gem-modified miRNA mimics exhibit an enhanced efficacy compared to Gem in patient-derived PDAC organoids. Furthermore, we observed that Gem-miR-15a significantly inhibits PDAC tumor growth in vivo without observing any noticeable signs of toxicity. Overall, our results demonstrate the therapeutic potential of Gem-modified miRNAs as a treatment strategy for PDAC.

Chk2 Modulates Bmi1-Deficiency-Induced Renal Aging and Fibrosis via Oxidative Stress, DNA Damage, and p53/TGFß1-Induced Epithelial-Mesenchymal Transition.

Renal aging may lead to fibrosis and dysfunction, yet underlying mechanisms remain unclear. We explored whether deficiency of the Polycomb protein Bmi1 causes renal aging via DNA damage response (DDR) activation, inducing renal tubular epithelial cell (RTEC) senescence and epithelial-mesenchymal transition (EMT). Bmi1 knockout mice exhibited oxidative stress, DDR activation, RTEC senescence, senescence-associated secretory phenotype (SASP), and age-related fibrosis in kidneys. Bmi1 deficiency impaired renal structure and function, increasing serum creatinine/urea, reducing creatinine clearance, and decreasing cortical thickness and glomerular number. However, knockout of the serine-threonine kinase Chk2 alleviated these aging phenotypes. Transcriptomics identified transforming growth factor beta 1 (TGFß1) upregulation in Bmi1-deficient RTECs, but TGFß1 was downregulated upon Chk2 knockout. The tumor suppressor protein p53 transcriptionally activated TGFß1, promoting EMT in RTECs. Bmi1 knockout or oxidative stress (induced with H2O2) increased TGFß1 expression, and EMT in RTECs and was partly reversed by p53 inhibition. Together, Bmi1 deficiency causes oxidative stress and DDR-mediated RTEC senescence/SASP, thus activating p53 and TGFß1 to induce EMT and age-related fibrosis. However, blocking DDR (via Chk2 knockout) or p53 ameliorates these changes. Our study reveals mechanisms whereby Bmi1 preserves renal structure and function during aging by suppressing DDR and p53/TGFß1-mediated EMT. These pathways represent potential targets for detecting and attenuating age-related renal decline.

TGF-ß1-triggered BMI1 and SMAD2 cooperatively regulate miR-191 to modulate bone formation.

Transforming growth factor ß 1 (TGF-ß1), as the most abundant signaling molecule in bone matrix, is essential for bone homeostasis. However, the signaling transduction of TGF-ß1 in the bone-forming microenvironment remains unknown. Here, we showed that microRNA-191 (miR-191) was downregulated during osteogenesis and further decreased by osteo-favoring TGF-ß1 in bone marrow mesenchymal stem cells (BMSCs). MiR-191 was lower in bone tissues from children than in those from middle-aged individuals and it was negatively correlated with collagen type I alpha 1 chain (COL1A1). MiR-191 depletion significantly increased osteogenesis and bone formation in vivo. Hydrogels embedded with miR-191-low BMSCs displayed a powerful bone repair effect. Mechanistically, transcription factors BMI1 and SMAD2 coordinately controlled miR-191 level. In detail, BMI1 and pSMAD2 were both upregulated by TGF-ß1 under osteogenic condition. SMAD2 activated miR-191 transcription, while BMI1 competed with SMAD2 for binding to miR-191 promoter region, thus disturbing the activation of SMAD2 on miR-191 and reducing miR-191 level. Altogether, our findings reveal that miR-191 regulated by TGF-ß1-induced BMI1 and SMAD2 negatively modulated bone formation and regeneration, and inhibition of miR-191 might be therapeutically useful to enhance bone repair in clinic.

MicroRNA-128 acts as a suppressor in the progression of gastrointestinal stromal tumor by targeting B-lymphoma Mo-MLV insertion region 1

Introduction The critical role of microRNA-128 (miR-128) in gastrointestinal-related diseases has been documented. In the current study, we tried to clarify the specific role miR-128 in gastrointestinal stromal tumor (GIST) and the underlying mechanism. Methods Differentially expressed genes in GIST were identified following bioinformatics analysis. Then, expression patterns of miR-128 and B-lymphoma Mo-MLV insertion region 1 (BMI-1) in clinical tissue samples and cell lines were characterized, followed by validation of their correlation. GIST-T1 cells were selected and transfected with different mimic, inhibitor, or siRNA plasmids, after which the biological functions were assayed. Results We identified low miR-128 and high BMI-1 expression in GIST tissues of 78 patients and 4 GIST cell lines. Ectopic expression of miR-128 or silencing of BMI-1 suppressed the malignant potentials of GIST-T1 cells. As a target of miR-128, BMI-1 re-expression could partly counteract the suppressive effect of miR-128 on the malignancy of GIST-T1 cells. Conclusion Our study provided evidence that miR-128-mediated silencing of BMI-1 could prevent malignant progression of GIST, highlighting a promising anti-tumor target for combating GIST (AU)

Melatonin-Loaded Nanoparticles Augment Mitophagy to Retard Parkinson's Disease.

The molecular pathways that melatonin follows as a Parkinson's disease (PD) antagonist remain poorly elucidated, despite it being a safe and a potential neurotherapeutic drug with a few limitations such as less bioavailability, premature oxidation, brain delivery, etc. Here, we used a biocompatible protein (HSA) nanocarrier for the delivery of melatonin to the brain. This nanomelatonin showed better antioxidative and neuroprotective properties, and it not only improves mitophagy to remove unhealthy mitochondria but also improves mitochondrial biogenesis to counteract rotenone-induced toxicity in an in vitro PD model. We also showed BMI1, a member of the PRC1 complex that regulates mitophagy, whose protein expression was enhanced after nanomelatonin dosage. These effects were translated to a rodent model, where nanomelatonin improves the TH+ve neuron population in SNPC and protects against rotenone-mediated toxicity. Our findings highlight the significantly better in vitro and in vivo neuroprotective effect of nanomelatonin as well as the molecular/cellular dynamics it influences to regulate mitophagy as a measure of the potential therapeutic candidate for PD.

B-cell specific Moloney murine leukemia virus insertion site 1 contributes to invasion, metastasis, and poor prognosis in salivary adenoid cystic carcinoma.

Background/purpose: Upregulation of B-cell specific Moloney murine leukemia virus insertion site 1 (BMI-1) has been involved in the invasion, metastasis, and poor prognosis of many cancers. The aim of this study was to evaluate the levels and clinical significance of BMI-1 in saliva of patients with salivary adenoid cystic carcinoma (SACC), and to analyze biological function and mechanism of BMI-1 in the invasion and metastasis of SACC. Materials and methods: The levels of BMI-1 in saliva and tumor tissues of SACC patients were determined. The correlation of salivary BMI-1 levels with clinicopathological parameters and clinical outcomes in patients with SACC was analyzed. Additionally, the effects of BMI-1 on wound-healing, transwell invasion, and epithelial-mesenchymal transition (EMT)-related protein expression in vitro as well as on tumorigenicity and experimental lung metastasis in vivo were investigated through exogenous overexpression and silencing of BMI-1 in SACC cells. Results: BMI-1 levels increased in saliva and tumor tissues in SACC patients with invasion or metastasis. High salivary BMI-1 levels were correlated with poor TNM stage, poor overall survival, and disease-free survival. Exogenous expression of BMI-1 in SACC-83 promoted its migration and invasion, while silencing BMI-1 in SACC-LM inhibited its migration and invasion in vitro and suppressed tumorigenesis and lung metastasis in vivo. Furthermore, BMI-1 regulated the expression of EMT-related proteins in SACC. Conclusion: Our study shows that BMI-1 can serve as a valuable biomarker to identify tumor invasion and metastasis in SACC, predict its prognosis, and act as a promising therapeutic target for SACC.

Cancer-associated fibroblast-derived extracellular vesicles promote lymph node metastases in oral cavity squamous cell carcinoma by encapsulating ITGB1 and BMI1.

BACKGROUND: Extracellular vesicles (EVs) have been revealed to facilitate the development of oral squamous cavity cell carcinoma (OCSCC), while its supporting role in lymph node metastases is under continuous investigation. This study aimed to examine the function of cancer-associated fibroblasts (CAF)-derived EVs (CAF-EVs) during lymph node metastasis in OCSCC and the mechanisms. METHODS: CAF were isolated from OCSCC tissues of patients, and CAF-EVs were extracted and identified. EdU, colony formation, wound healing, and Transwell assays were performed. The OCSCC cells before and after CAF-EVs treatment were injected into mice to probe the effects of CAF-EVs on tumor growth and lymph node metastasis, respectively. The effect of CAF-EVs treatment on transcriptome changes in OCSCC cells was analyzed. Clinical data of patients with OCSCC were analyzed to determine the prognostic significance of the selected genes. Finally, loss-of-function assays were conducted to corroborate the involvement of polycomb complex protein BMI-1 (BMI1) and integrin beta1 (ITGB1). RESULTS: CAF-EVs promoted the malignant behavior of OCSCC cells and accelerated tumor growth and lymph node metastasis in mice. CAF-EVs significantly increased the expression of BMI1 and ITGB1, and the expression of BMI1 and ITGB1 was negatively correlated with the overall survival and relapse-free survival of OCSCC patients. Knockdown of BMI1 or ITGB1 in OCSCC cells abated the promoting effects of CAF-EVs in vitro and in vivo. CONCLUSION: CAF-EVs elicited the metastasis-promoting properties in OCSCC by elevating BMI1 and ITGB1, suggesting that BMI1 and ITGB1 could be potential biomarkers and therapeutic targets for OCSCC.

Genome-wide association study identifies a novel BMI1A QTL allele that confers FLC expression diversity in Arabidopsis thaliana.

Identification and understanding of the genetic basis of natural variations in plants are essential for comprehending their phenotypic adaptation. Here, we report a genome-wide association study (GWAS) of FLOWERING LOCUS C (FLC) expression in 727 Arabidopsis accessions. We identified B LYMPHOMA MOLONEY MURINE LEUKEMIA VIRUS INSERTION REGION 1 HOMOLOG 1A (BMI1A) as a causal gene for one of the FLC expression quantitative trait loci (QTLs). Loss of function in BMI1A increases FLC expression and delays flowering time at 16 °C significantly compared with the wild type (Col-0). BMI1A activity is required for histone H3 lysine 27 trimethylation (H3K27me3) accumulation at the FLC, MADS AFFECTING FLOWERING 4 (MAF4), and MAF5 loci at low ambient temperature. We further uncovered two BMI1A haplotypes associated with the natural variation in FLC expression and flowering time at 16 °C, and demonstrated that polymorphisms in the BMI1A promoter region are the main contributor. Different BMI1A haplotypes are strongly associated with geographical distribution, and the low ambient temperature-sensitive BMI1A variants are associated with a lower mean temperature of the driest quarter of their collection sites compared with the temperature-non-responsive variants, indicating that the natural variations in BMI1A have adaptive functions in FLC expression and flowering time regulation. Therefore, our results provide new insights into the natural variations in FLC expression and flowering time diversity in plants.

Peptidase inhibitor 16 promotes inflammatory arthritis by suppressing Foxp3 expression via regulating K48-linked ubiquitin degradation Bmi-1 in regulatory T cells.

Abnormalities of regulatory T cells (Tregs) has been suggested in rheumatoid arthritis (RA), and Forkhead box P3 (Foxp3) is the key transcriptional factor of Tregs expression. However, the underlying molecular mechanism remains unclear. Here, we demonstrated peptidase inhibitor 16 (PI16) was significantly increased in the peripheral blood, synovial fluid, and synovial tissue from RA patients. PI16 transgenic mice (PI16Tg) aggravated arthritis severity partly through suppressing Foxp3 expression. Mechanistically, PI16 could interact with and stabilize Bmi-1 in Tregs via inhibiting K48-linked polyubiquitin of Bmi-1, which promotes the enrichment of repressive histone mark in Foxp3 promoter. Furthermore, Bmi-1 specific inhibitor PTC209 could restore Foxp3 expression and alleviate arthritis progression in PI16Tg mice, accompanied by increased recruitment of active histone mark in the promoter of Tregs. Our results suggest that PI16-Bmi-1 axis plays an important role in RA and other autoimmune diseases by suppressing Foxp3 expression in Tregs via Bmi-1-mediated histone modification.

A dynamic Boolean network reveals that the BMI1 and MALAT1 axis is associated with drug resistance by limiting miR-145-5p in non-small cell lung cancer.

Patients with non-small cell lung cancer (NSCLC) are often treated with chemotherapy. Poor clinical response and the onset of chemoresistance limit the anti-tumor benefits of drugs such as cisplatin. According to recent research, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA related to cisplatin resistance in NSCLC. Furthermore, MALAT1 targets microRNA-145-5p (miR-145), which activates Krüppel-like factor 4 (KLF4) in associated cell lines. B lymphoma Mo-MLV insertion region 1 homolog (BMI1), on the other hand, inhibits miR-145 expression, which stimulates Specificity protein 1 (Sp1) to trigger the epithelial-mesenchymal transition (EMT) process in pemetrexed-resistant NSCLC cells. The interplay between these molecules in drug resistance is still unclear. Therefore, we propose a dynamic Boolean network that can encapsulate the complexity of these drug-resistant molecules. Using published clinical data for gain or loss-of-function perturbations, our network demonstrates reasonable agreement with experimental observations. We identify four new positive circuits: miR-145/Sp1/MALAT1, BMI1/miR-145/Myc, KLF4/p53/miR-145, and miR-145/Wip1/p38MAPK/p53. Notably, miR-145 emerges as a central player in these regulatory circuits, underscoring its pivotal role in NSCLC drug resistance. Our circuit perturbation analysis further emphasizes the critical involvement of these new circuits in drug resistance for NSCLC. In conclusion, targeting MALAT1 and BMI1 holds promise for overcoming drug resistance, while activating miR-145 represents a potential strategy to significantly reduce drug resistance in NSCLC.

PP2A inhibitor SET promotes mTORC1 and Bmi1 signaling through Akt activation and maintains the colony-formation ability of cancer cells.

Protein phosphatase 2A (PP2A) is an essential tumor suppressor, with its activity often hindered in cancer cells by endogenous PP2A inhibitory proteins like SE translocation (SET). SET/PP2A axis plays a pivotal role in the colony-formation ability of cancer cells and the stabilization of c-Myc and E2F1 proteins implicated in this process. However, in osteosarcoma cell line HOS, SET knock-down (KD) suppresses the colony-formation ability without affecting c-Myc and E2F1. This study aimed to unravel the molecular mechanism through which SET enhances the colony-formation ability of HOS cells and determine if it is generalized to other cancer cells. Transcriptome analysis unveiled that SET KD suppressed mTORC1 signaling. SET KD inhibited Akt phosphorylation, an upstream kinase for mTORC1. PP2A inhibitor blocked SET KD-mediated decrease in phosphorylation of Akt and a mTORC1 substrate p70S6K. A constitutively active Akt restored decreased colony-formation ability by SET KD, indicating the SET/PP2A/Akt/mTORC1 axis. Additionally, enrichment analysis highlighted that Bmi-1, a polycomb group protein, is affected by SET KD. SET KD decreased Bmi-1 protein by Akt inhibition but not by mTORC1 inhibition, and exogenous Bmi-1 expression rescued the reduced colony formation by SET KD. Four out of eight cancer cell lines exhibited decreased Bmi-1 by SET KD. Further analysis of these cell lines revealed that Myc activity plays a role in SET KD-mediated Bmi-1 degradation. These findings provide new insights into the molecular mechanism of SET-regulated colony-formation ability, which involved Akt-mediated activation of mTORC1/p70S6K and Bmi-1 signaling.

MicroRNA-128 acts as a suppressor in the progression of gastrointestinal stromal tumor by targeting B-lymphoma Mo-MLV insertion region 1.

INTRODUCTION: The critical role of microRNA-128 (miR-128) in gastrointestinal-related diseases has been documented. In the current study, we tried to clarify the specific role miR-128 in gastrointestinal stromal tumor (GIST) and the underlying mechanism. METHODS: Differentially expressed genes in GIST were identified following bioinformatics analysis. Then, expression patterns of miR-128 and B-lymphoma Mo-MLV insertion region 1 (BMI-1) in clinical tissue samples and cell lines were characterized, followed by validation of their correlation. GIST-T1 cells were selected and transfected with different mimic, inhibitor, or siRNA plasmids, after which the biological functions were assayed. RESULTS: We identified low miR-128 and high BMI-1 expression in GIST tissues of 78 patients and 4 GIST cell lines. Ectopic expression of miR-128 or silencing of BMI-1 suppressed the malignant potentials of GIST-T1 cells. As a target of miR-128, BMI-1 re-expression could partly counteract the suppressive effect of miR-128 on the malignancy of GIST-T1 cells. CONCLUSION: Our study provided evidence that miR-128-mediated silencing of BMI-1 could prevent malignant progression of GIST, highlighting a promising anti-tumor target for combating GIST.

Application of mPEG-CS-cRGD/Bmi-1RNAi-PTX nanoparticles in suppression of laryngeal cancer by targeting cancer stem cells.

Although surgery-based comprehensive therapy is becoming the main approach to treat laryngeal cancer, recurrence, metastasis, radiotherapy resistance and chemotherapy tolerance are still the main causes of death in patients. Targeted inhibition of laryngeal cancer stem cells has been considered as the consensus to cure laryngeal cancer. Our previous study has confirmed proto-oncogene Bmi-1 as a key regulator for self-renewal of laryngeal cancer stem cells. Targeted knockdown of Bmi-1 gene effectively inhibited the self-renewal and differentiation of laryngeal cancer stem cells, leading to the promoted sensitivity to chemotherapy including paclitaxel. However, due to off-target effects and quick degradation of the naked Bmi-1-RNAi small RNA oligo by nuclease in body fluids, it is urgently needed to develop a tumor-targeted delivery system with a protective shell. In this study, we designed and synthesized cRGD peptide-modified chitosan-polyethylene glycol slow-release nanoparticles (mPEG-CS-cRGD/Bmi-1RNAi-PTX) containing Bmi-1RNAi siRNA oligo and paclitaxel, which showed spherical in shape, 200 nm diameter in size, low cytotoxicity, strong DNA wrapping, resistance to nuclease degradation and high transfection efficiency to cells. Functional analysis indicated significant suppression of cell proliferation and migration and induction of apoptosis by the nanocomplex in laryngeal cancer cells in vitro. By application to the mouse model with laryngeal cancer, the nanocomplex inhibited tumor growth significantly in vivo. In addition, cRGD peptide, paclitaxel and Bmi-1 siRNA in the nanoparticles showed synergistic effects to suppress laryngeal cancer stem cells. In conclusion, this study not only developed a laryngeal tumor-targeted chemotherapeutic system, but also demonstrated a Bmi-1 RNAi-based chemotherapeutic strategy to inhibit cancer stem cells, having strong potential to treat laryngeal cancer patients suffering therapy resistance and/or tumor recurrence.

Molecular biomarkers NOTCH1, CD44, BMI1, and TP53 in oral squamous cell carcinoma.

It is of interest to evaluate NOTCH1, CD44, BMI1, and TP53 genes in the epiglottis, tongue, and hard palate of oral malignancies (OM) with healthy controls. This was a prospective and cross-sectional study of 60 individuals with oral malignancies (OM) (20 each of tongue, epiglottis, and hard palate) studied at Malla Reddy Medical College and tertiary care hospitals in Hyderabad. Adults aged ≥ 18 years and diagnosed with oral cancer were included in the study. Those who had cancer in more than one area were excluded from the study. Blood samples of individuals with tongue or epiglottis or hard palate were taken for testing the expression of NOTCH1, CD44, TP53, and BMI1 genes. They were analysed by the genomic sequencing method. One-way ANOVA with Bonferroni's t-test was used for statistical analysis. Expression of NOTCH1, CD44, BMI1, and TP53 genes were significantly higher in epiglottis, tongue, and hard palate compared to healthy control samples (p < 0.001). All four genes were expressed in all three areas of OM. However, they were not significant between them. Further analysis revealed that NOTCH1, CD44, TP53, and BMI1 genes did not show any difference in HPV-positive and HPV-negative samples. Comparing the T stages of cancer Notch1, gene expression was significantly higher in stages 1 and 2 compared to 3 and 4. The CD44, TP53, and BMI1 did not show any differences in the T stage. However, the difference in HPV in all T stages was very minimal. Data showed that irrespective of the areas of cancer (epiglottis, tongue, and hard palate) NOTCH1, CD44, TP53, and BMI1 genes were expressed equally. The expression was not very much dependent on HPV positive (+ve) or negative (-ve). However the T-stage was showing higher expression compared to control group. Since the expression of these genes was very high in all the three malignancies, they may be used as early biomarkers to detect cancer of epiglottis, tongue, and hard palate.

Targeting BMI-1 to deplete antibody-secreting cells in autoimmunity.

Objectives: B cells drive the production of autoreactive antibody-secreting cells (ASCs) in autoimmune diseases such as Systemic Lupus Erythematosus (SLE) and Sjögren's syndrome, causing long-term organ damage. Current treatments for antibody-mediated autoimmune diseases target B cells or broadly suppress the immune system. However, pre-existing long-lived ASCs are often refractory to treatment, leaving a reservoir of autoreactive cells that continue to produce antibodies. Therefore, the development of novel treatment methods targeting ASCs is vital to improve patient outcomes. Our objective was to test whether targeting the epigenetic regulator BMI-1 could deplete ASCs in autoimmune conditions in vivo and in vitro. Methods: Use of a BMI-1 inhibitor in both mouse and human autoimmune settings was investigated. Lyn -/- mice, a model of SLE, were treated with the BMI-1 small molecule inhibitor PTC-028, before assessment of ASCs, serum antibody and immune complexes. To examine human ASC survival, a novel human fibroblast-based assay was established, and the impact of PTC-028 on ASCs derived from Sjögren's syndrome patients was evaluated. Results: BMI-1 inhibition significantly decreased splenic and bone marrow ASCs in Lyn -/- mice. The decline in ASCs was linked to aberrant cell cycle gene expression and led to a significant decrease in serum IgG3, immune complexes and anti-DNA IgG. PTC-028 was also efficacious in reducing ex vivo plasma cell survival from both Sjögren's syndrome patients and age-matched healthy donors. Conclusion: These data provide evidence that inhibiting BMI-1 can deplete ASC in a variety of contexts and thus BMI-1 is a viable therapeutic target for antibody-mediated autoimmune diseases.

The lncRNA DLX6-AS1/miR-16-5p axis regulates autophagy and apoptosis in non-small cell lung cancer: A Boolean model of cell death.

Long non-coding RNA (lncRNA) distal-less homeobox 6 antisense RNA 1 (DLX6-AS1) is elevated in a variety of cancers, including non-small cell lung cancer (NSCLC) and cervical cancer. Although it was found that the microRNA-16-5p (miR-16), which is known to regulate autophagy and apoptosis, had been downregulated in similar cancers. Recent research has shown that in tumors with similar characteristics, DLX6-AS1 acts as a sponge for miR-16 expression. However, the cell death-related molecular mechanism of the DLX6-AS1/miR-16 axis has yet to be investigated. Therefore, we propose a dynamic Boolean model to investigate gene regulation in cell death processes via the DLX6-AS1/miR-16 axis. We found the finest concordance when we compared our model to many experimental investigations including gain-of-function genes in NSCLC and cervical cancer. A unique positive circuit involving BMI1/ATM/miR-16 is also something we predict. Our results suggest that this circuit is essential for regulating autophagy and apoptosis under stress signals. Thus, our Boolean network enables an evident cell-death process coupled with NSCLC and cervical cancer. Therefore, our results suggest that DLX6-AS1 targeting may boost miR-16 activity and thereby restrict tumor growth in these cancers by triggering autophagy and apoptosis.

Specific downregulation of microRNA-186 induces neural stem cell self-renewal by upregulating Bmi-1/FoxG1 expression.

Self-renewal and differentiation in neural stem cells (NSCs) are modulated by microRNAs (miRNAs). However, the recent evidence available is not enough to elucidate the role of miRNA in the self-renewal and differentiation of NSCs from developing brain. In this study, we isolated primary NSCs from the forebrain of fetal rat for in vitro analysis. Downregulation of miRNA-186 in response to a specific miRNA inhibitor resulted in upregulation of Bmi-1 and FoxG1, while maintaining NCS self-renewal. Bmi-1 overexpression restored the maintenance of NSCs in vitro. FoxG1 was found to promote the methylation of Foxo3 promoter and inhibited Foxo3 expression. miR-186 upregulation increased the expression of Foxo3 and inhibited NSC self-renewal in the absence of Foxo3. Therefore, we propose that downregulation of miR-186 maintained NSC self-renewal in the postnatal brain by upregulating the Bmi1/FoxG1 expression via FoxO3 elevation.

Mechanism of E2F1 in the proliferation, migration, and invasion of endometrial carcinoma cells via the regulation of BMI1 transcription.

BACKGROUND: Endometrial carcinoma (EC) is the most prevalent gynecological cancer. Transcription factor (TF) regulates a large number of downstream target genes and is a key determinant of all physiological activities, including cell proliferation, differentiation, apoptosis, and cell cycle. The transcription factor E2F1 shows prominent roles in EC. BMI1 is a member of Polycomb suppressor Complex 1 (PRC1) and has been shown to be associated with EC invasiveness. It is currently unclear whether E2F1 can participate in the proliferation, migration, and invasion processes of EC cells by regulating BMI1 transcription. OBJECTIVE: We investigated whether E2F1 could participate in the proliferation, migration, and invasion processes of EC cells by regulating BMI1 transcription, in order to further clarify the pathogenesis and etiology of EC, and provide reference for identifying potential therapeutic targets and developing effective prevention and treatment strategies for this disease. METHODS: Human endometrial epithelial cells (hEECs) and human EC cell lines were selected. E2F1 expression was assessed by Western blot. E2F1 was silenced in AN3CA or overexpressed in HEC-1 by transfections, or E2F1 was silenced and BMI1 was overexpressed in AN3CA by cotransfection. Cell proliferation, migration, and invasion were detected by MTT, wound healing, and Transwell assays. The binding sites between E2F1 and BMI1 promoters were predicted through JASPAR website, and the targeted binding was verified by dual-luciferase report and ChIP assays. RESULTS: E2F1 was up-regulated in human EC cell lines, with its expression highest in AN3CA, and lowest in HEC-1. AN3CA invasion, migration, and proliferation were repressed by E2F1 knockdown, while those of HEC-1 cells were promoted by E2F1 overexpression. E2F1 overexpression increased the activity of wild type BMI1 reporter vector promoter, while this promotion was weakened after mutation of the predicted binding site in the BMI1 promoter. In the precipitated E2F1, BMI1 promoter site level was higher than that of IgG immunoprecipitant. BMI1 silencing suppressed AN3CA cell growth. BMI1 overexpression partially abrogated E2F1 silencing-inhibited EC cell growth. CONCLUSION: E2F1 promoted EC cell proliferation, invasion, and migration by promoting the transcription of BMI1.

BMI-1 activates hepatic stellate cells to promote the epithelial-mesenchymal transition of colorectal cancer cells.

BACKGROUND: Activated hepatic stellate cells (aHSCs) are the major source of cancer-associated fibroblasts in the liver. Although the crosstalk between aHSCs and colorectal cancer (CRC) cells supports liver metastasis (LM), the mechanisms are largely unknown. AIM: To explore the role of BMI-1, a polycomb group protein family member, which is highly expressed in LM, and the interaction between aHSCs and CRC cells in promoting CRC liver metastasis (CRLM). METHODS: Immunohistochemistry was carried out to examine BMI-1 expression in LM and matched liver specimens of CRC. The expression levels of BMI-1 in mouse liver during CRLM (0, 7, 14, 21, and 28 d) were detected by Western blotting (WB) and the quantitative polymerase chain reaction (qPCR) assay. We overexpressed BMI-1 in HSCs (LX2) by lentivirus infection and tested the molecular markers of aHSCs by WB, qPCR, and the immunofluorescence assay. CRC cells (HCT116 and DLD1) were cultured in HSC-conditioned medium (LX2 NC CM or LX2 BMI-1 CM). CM-induced CRC cell proliferation, migration, epithelial-mesenchymal transition (EMT) phenotype, and transforming growth factor beta (TGF-ß)/SMAD pathway changes were investigated in vitro. A mouse subcutaneous xenotransplantation tumor model was established by co-implantation of HSCs (LX2 NC or LX2 BMI-1) and CRC cells to investigate the effects of HSCs on tumor growth and the EMT phenotype in vivo. RESULTS: Positive of BMI-1 expression in the liver of CRLM patients was 77.8%. The expression level of BMI-1 continued to increase during CRLM in mouse liver cells. LX2 overexpressed BMI-1 was activated, accompanied by increased expression level of alpha smooth muscle actin, fibronectin, TGF-ß1, matrix metalloproteinases, and interleukin 6. CRC cells cultured in BMI-1 CM exhibited enhanced proliferation and migration ability, EMT phenotype and activation of the TGF-ß/SMAD pathway. In addition, the TGF-ßR inhibitor SB-505124 diminished the effect of BMI-1 CM on SMAD2/3 phosphorylation in CRC cells. Furthermore, BMI-1 overexpressed LX2 HSCs promoted tumor growth and the EMT phenotype in vivo. CONCLUSION: High expression of BMI-1 in liver cells is associated with CRLM progression. BMI-1 activates HSCs to secrete factors to form a prometastatic environment in the liver, and aHSCs promote proliferation, migration, and the EMT in CRC cells partially through the TGF-ß/SMAD pathway.

ING1 inhibits Twist1 expression to block EMT and is antagonized by the HDAC inhibitor vorinostat.

ING1 is a chromatin targeting subunit of the Sin3a histone deacetylase (HDAC) complex that alters chromatin structure to subsequently regulate gene expression. We find that ING1 knockdown increases expression of Twist1, Zeb 1&2, Snai1, Bmi1 and TSHZ1 drivers of EMT, promoting EMT and cell motility. ING1 expression had the opposite effect, promoting epithelial cell morphology and inhibiting basal and TGF-ß-induced motility in 3D organoid cultures. ING1 binds the Twist1 promoter and Twist1 was largely responsible for the ability of ING1 to reduce cell migration. Consistent with ING1 inhibiting Twist1 expression in vivo, an inverse relationship between ING1 and Twist1 levels was seen in breast cancer samples from The Cancer Genome Atlas (TCGA). The HDAC inhibitor vorinostat is approved for treatment of multiple myeloma and cutaneous T cell lymphoma and is in clinical trials for solid tumours as adjuvant therapy. One molecular target of vorinostat is INhibitor of Growth 2 (ING2), that together with ING1 serve as targeting subunits of the Sin3a HDAC complex. Treatment with sublethal (LD25-LD50) levels of vorinostat promoted breast cancer cell migration several-fold, which increased further upon ING1 knockout. These observations indicate that correct targeting of the Sin3a HDAC complex, and HDAC activity in general decreases luminal and basal breast cancer cell motility, suggesting that use of HDAC inhibitors as adjuvant therapies in breast cancers that are prone to metastasize may not be optimal and requires further investigation.