ABSTRACT
Drug-resistant and metastatic cancer cells such as a small population of cancer stem cells (CSCs) play a crucial role in metastasis and relapse. Conventional small-molecule chemotherapeutics, however, are unable to eradicate drug-resistant CSCs owing to limited interface inhibitory effects. Herein, it is reported that enhanced interfacial inhibition leading to eradication of drug-resistant CSCs can be dramatically induced by self-insertion of bioactive graphene quantum dots (GQDs) into DNA major groove (MAG) sites in cancer cells. Since transcription factors regulate gene expression at the MAG site, MAG-targeted GQDs exert greatly enhanced interfacial inhibition, downregulating the expression of a collection of cancer stem genes such as ALDH1, Notch1, and Bmi1. Moreover, the nanoscale interface inhibition mechanism reverses cancer multidrug resistance (MDR) by inhibiting MDR1 gene expression when GQDs are used at a nontoxic concentration (1/4 × half-maximal inhibitory concentration (IC50)) as the MDR reverser. Given their high efficacy in interfacial inhibition, CSC-mediated migration, invasion, and metastasis of cancer cells can be substantially blocked by MAG-targeted GQDs, which can also be harnessed to sensitize clinical cytotoxic agents for improved efficacy in combination chemotherapy. These findings elucidate the inhibitory effects of the enhanced nano-bio interface at the MAG site on eradicating CSCs, thus preventing cancer metastasis and recurrence.
Subject(s)
Drug Resistance, Neoplasm , Graphite , Neoplastic Stem Cells , Quantum Dots , Humans , Graphite/chemistry , Graphite/pharmacology , Quantum Dots/chemistry , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/metabolism , Neoplastic Stem Cells/pathology , Drug Resistance, Neoplasm/drug effects , Cell Line, Tumor , Aldehyde Dehydrogenase 1 Family/metabolism , Cell Movement/drug effects , Retinal Dehydrogenase/metabolism , Neoplasm Metastasis , Receptor, Notch1/metabolism , Receptor, Notch1/genetics , Polycomb Repressive Complex 1/metabolism , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Drug Resistance, Multiple/drug effects , Gene Expression Regulation, Neoplastic/drug effects , AnimalsABSTRACT
Bridged PROTAC is a novel protein complex degrader strategy that exploits the target protein's binding partner to degrade undruggable proteins by inducing proximity to an E3 ubiquitin ligase. In this study, we discovered for the first time that cereblon (CRBN) can be employed for the bridged PROTAC approach and report the first-in-class CRBN-recruiting and EED-binding polycomb repressive complex 1 (PRC1) degrader, compound 1 (MS181). We show that 1 induces preferential degradation of PRC1 components, BMI1 and RING1B, in an EED-, CRBN-, and ubiquitin-proteosome system (UPS)-dependent manner. Compound 1 also has superior antiproliferative activity in multiple metastatic cancer cell lines over EED-binding PRC2 degraders and can be efficacious in VHL-defective cancer cells. Altogether, compound 1 is a valuable chemical biology tool to study the role of PRC1 in cancer. Importantly, we show that CRBN can be utilized to develop bridged PROTACs, expanding the bridged PROTAC technology for degrading undruggable proteins.
Subject(s)
Adaptor Proteins, Signal Transducing , Polycomb Repressive Complex 1 , Proteolysis , Ubiquitin-Protein Ligases , Humans , Ubiquitin-Protein Ligases/metabolism , Polycomb Repressive Complex 1/metabolism , Polycomb Repressive Complex 1/antagonists & inhibitors , Adaptor Proteins, Signal Transducing/metabolism , Cell Line, Tumor , Proteolysis/drug effects , Drug Discovery , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/chemical synthesis , Cell Proliferation/drug effects , Structure-Activity RelationshipABSTRACT
Differentiated thyroid carcinomas (DTCs), which have papillary and follicular types, are common endocrine malignancies worldwide. Cancer stem cells (CSCs) are a particular type of cancer cells within bulk tumors involved in cancer initiation, drug resistance, and metastasis. Cells with high intracellular aldehyde hydrogenase (ALDH) activity are a population of CSCs in DTCs. Disulfiram (DSF), an ALDH inhibitor used for the treatment of alcoholism, reportedly targets CSCs in various cancers when combined with copper. This study reported for the first time that DSF/copper can inhibit the proliferation of papillary and follicular DTC lines. DSF/copper suppressed thyrosphere formation, indicating the inhibition of CSC activity. Molecular mechanisms of DSF/copper involved downregulating the expression of B lymphoma Mo-MLV insertion region 1 homolog (BMI1) and cell cycle-related proteins, including cyclin B2, cyclin-dependent kinase (CDK) 2, and CDK4, in a dose-dependent manner. BMI1 overexpression diminished the inhibitory effect of DSF/copper in the thyrosphere formation of DTC cells. BMI1 knockdown by RNA interference in DTC cells also suppressed the self-renewal capability. DSF/copper could inhibit the nuclear localization and transcriptional activity of c-Myc and the binding of E2F1 to the BMI1 promoter. Overexpression of c-Myc or E2F1 further abolished the inhibitory effect of DSF/copper on BMI1 expression, suggesting that the suppression of c-Myc and E2F1 by DSF/copper was involved in the downregulation of BMI1 expression. In conclusion, DSF/copper targets CSCs in DTCs by inhibiting c-Myc- or E2F1-mediated BMI1 expression. Therefore, DSF is a potential therapeutic agent for future therapy in DTCs.
Subject(s)
Copper , Disulfiram , Neoplastic Stem Cells , Thyroid Neoplasms , Humans , Aldehyde Dehydrogenase/metabolism , Cell Line, Tumor , Copper/chemistry , Copper/pharmacology , Disulfiram/pharmacology , Disulfiram/chemistry , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/metabolism , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/metabolism , Thyroid Neoplasms/drug therapy , Thyroid Neoplasms/metabolismABSTRACT
BACKGROUND: Epigenetic changes play a key role in the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor. METHODS: We explore the therapeutic potential of BMI1 and MAPK/ERK inhibition in BMI1High;CHD7Low MB cells and in a preclinical xenograft model. RESULTS: We identify a synergistic vulnerability of BMI1High;CHD7Low MB cells to a combination treatment with BMI1 and MAPK/ERK inhibitors. Mechanistically, CHD7-dependent binding of BMI1 to MAPK-regulated genes underpins the CHD7-BMI1-MAPK regulatory axis responsible of the antitumour effect of the inhibitors in vitro and in a preclinical mouse model. Increased ERK1 and ERK2 phosphorylation activity is found in BMI1High;CHD7Low G4 MB patients, raising the possibility that they could be amenable to a similar therapy. CONCLUSIONS: The molecular dissection of the CHD7-BMI1-MAPK regulatory axis in BMI1High;CHD7Low MB identifies this signature as a proxy to predict MAPK functional activation, which can be effectively drugged in preclinical models, and paves the way for further exploration of combined BMI1 and MAPK targeting in G4 MB patients.
Subject(s)
Brain Neoplasms , Cerebellar Neoplasms , Medulloblastoma , Protein Kinase Inhibitors , Animals , Brain Neoplasms/genetics , Cell Line, Tumor , Cell Proliferation , Cerebellar Neoplasms/genetics , Humans , Medulloblastoma/genetics , Mice , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/genetics , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins/geneticsABSTRACT
Replication stress (RS) has a pivotal role in tumor initiation, progression, or therapeutic resistance. In this study, we depicted the mechanism of breast cancer stem cells' (bCSCs) response to RS and its clinical implication. We demonstrated that bCSCs present a limited level of RS compared with non-bCSCs in patient samples. We described for the first time that the spatial nuclear location of BMI1 protein triggers RS response in breast cancers. Hence, in bCSCs, BMI1 is rapidly located to stalled replication forks to recruit RAD51 and activate homologous-recombination machinery, whereas in non-bCSCs BMI1 is trapped on demethylated 1q12 megasatellites precluding effective RS response. We further demonstrated that BMI1/RAD51 axis activation is necessary to prevent cisplatin-induced DNA damage and that treatment of patient-derived xenografts with a RAD51 inhibitor sensitizes tumor-initiating cells to cisplatin. The comprehensive view of replicative-stress response in bCSC has profound implications for understanding and improving therapeutic resistance.
Subject(s)
Breast Neoplasms/pathology , Cell Nucleus/metabolism , Drug Resistance, Neoplasm/drug effects , Neoplastic Stem Cells/drug effects , Polycomb Repressive Complex 1/metabolism , Rad51 Recombinase/metabolism , Breast Neoplasms/genetics , Breast Neoplasms/metabolism , Cisplatin/pharmacology , DNA Damage/drug effects , DNA Replication/drug effects , Drug Resistance, Neoplasm/genetics , Female , Homologous Recombination , Humans , Neoplastic Stem Cells/metabolism , Neoplastic Stem Cells/pathology , Polycomb Repressive Complex 1/antagonists & inhibitors , Rad51 Recombinase/antagonists & inhibitorsABSTRACT
A good quality of life requires maintaining adequate skeletal muscle mass and strength, but therapeutic agents are lacking for this. We developed a bioassay-guided fractionation approach to identify molecules with hypertrophy-promoting effect in human skeletal muscle cells. We found that extracts from rosemary leaves induce muscle cell hypertrophy. By bioassay-guided purification we identified the phenolic diterpene carnosol as the compound responsible for the hypertrophy-promoting activity of rosemary leaf extracts. We then evaluated the impact of carnosol on the different signaling pathways involved in the control of muscle cell size. We found that activation of the NRF2 signaling pathway by carnosol is not sufficient to mediate its hypertrophy-promoting effect. Moreover, carnosol inhibits the expression of the ubiquitin ligase E3 Muscle RING Finger protein-1 that plays an important role in muscle remodeling, but has no effect on the protein synthesis pathway controlled by the protein kinase B/mechanistic target of rapamycin pathway. By measuring the chymotrypsin-like activity of the proteasome, we found that proteasome activity was significantly decreased by carnosol and Muscle RING Finger 1 inactivation. These results strongly suggest that carnosol can induce skeletal muscle hypertrophy by repressing the ubiquitin-proteasome system-dependent protein degradation pathway through inhibition of the E3 ubiquitin ligase Muscle RING Finger protein-1.
Subject(s)
Abietanes/pharmacology , Hypertrophy/chemically induced , Muscle Fibers, Skeletal/drug effects , Plant Extracts/chemistry , Rosmarinus/chemistry , Signal Transduction/drug effects , Abietanes/isolation & purification , Biological Assay , Chemical Fractionation , Humans , Muscle, Skeletal/cytology , Phenols/isolation & purification , Phenols/pharmacology , Polycomb Repressive Complex 1/antagonists & inhibitors , Proteasome Endopeptidase Complex/metabolism , Proteolysis/drug effects , Ubiquitin/metabolismABSTRACT
Diffuse large Bcell lymphoma (DLBCL) is the most common type of nonHodgkin lymphoma worldwide. Several studies have indicated that Homo sapiens (hsa)microRNA (miR)429 exerts a tumorsuppressive effect on a variety of malignant tumors. To the best of our knowledge, the molecular function and mechanism of action of hsamiR429 in DLBCL have not been evaluated to date. The present study demonstrated that the expression of hsamiR429 in DLBCL cells was significantly reduced. hsamiR429 inhibited the proliferation of the DLBCL cell lines, SUDHL4 and DB, and promoted apoptosis. A dual luciferase reporter assay was used to demonstrate that chromobox 8 (CBX8) was the target gene of hsamiR429. Overexpression of CBX8 promoted the proliferation of SUDHL4 and DB cells and inhibited apoptosis, thereby playing a cancerpromoting role. Transfection of hsamiR429 mimic into DB cells overexpressing CBX8 antagonized the effect of CBX8 on the proliferation of DB cells. Moreover, the apoptotic rate was increased in DB cells overexpressing CBX8 and transfected with hsamiR429 mimic, while the proportion of cells in the G2/M phase was significantly reduced. These results demonstrated the antagonistic effect of hsamiR429 on the oncogenic function of CBX8. Therefore, in DLBCL, the tumor suppressor effect of hsamiR429 may be achieved by targeted downregulation of CBX8, suggesting that hsamiR429 may be used as a diagnostic marker and a potential nucleic acid drug for DLBCL. CBX8 may also represent an effective therapeutic target for DLBCL.
Subject(s)
Apoptosis/genetics , Lymphoma, Large B-Cell, Diffuse/genetics , Lymphoma, Large B-Cell, Diffuse/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Polycomb Repressive Complex 1/metabolism , Aged , Cell Line , Cell Proliferation/genetics , Down-Regulation/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Male , Middle Aged , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/geneticsABSTRACT
BMI-1, a polycomb ring finger oncogene, is highly expressed in multiple cancer cells and is involved in cancer cell proliferation, invasion, and apoptosis. BMI-1 represents a cancer stemness marker that is associated with the regulation of stem cell self-renewal. In this study, pharmacological inhibition (PTC596) or knockdown (siRNA) of BMI-1 reduced cancer stem-like cells and enhanced cancer cell death. Mechanistically, the inhibition of BMI-1 induced the downregulation of Mcl-1 protein, but not Mcl-1 mRNA. PTC596 downregulated Mcl-1 protein expression at the post-translational level through the proteasome-ubiquitin system. PTC596 and BMI-1 siRNA induced downregulation of DUB3 deubiquitinase, which was strongly linked to Mcl-1 destabilization. Furthermore, overexpression of Mcl-1 or DUB3 inhibited apoptosis by PTC596. Taken together, our findings reveal that the inhibition of BMI-1 induces Mcl-1 destabilization through downregulation of DUB3, resulting in the induction of cancer cell death.
Subject(s)
Apoptosis , Benzimidazoles/pharmacology , Down-Regulation , Endopeptidases/metabolism , Gene Expression Regulation, Neoplastic , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Polycomb Repressive Complex 1/antagonists & inhibitors , Pyrazines/pharmacology , A549 Cells , Body Mass Index , Caspase 3/metabolism , Cell Death , Cell Line, Tumor , Cell Proliferation/drug effects , DNA Fragmentation , Enzyme Activation , HeLa Cells , Humans , Neoplastic Stem Cells/metabolism , RNA, Small Interfering/metabolism , Ubiquitin/chemistryABSTRACT
Methyllysine reader proteins bind to methylated lysine residues and alter gene transcription by changing either the compaction state of chromatin or by the recruitment of other multiprotein complexes. The polycomb paralog family of methyllysine readers bind to trimethylated lysine on the tail of histone 3 (H3) via a highly conserved aromatic cage located in their chromodomains. Each of the polycomb paralogs are implicated in several disease states. CBX6 and CBX8 are members of the polycomb paralog family with two structurally similar chromodomains. By exploring the structure-activity relationships of a previously reported CBX6 inhibitor we have discovered more potent and cell permeable analogs. Our current report includes potent, dual-selective inhibitors of CBX6 and CBX8. We have shown that the -2 position in our scaffold is an important residue for selectivity amongst the polycomb paralogs. Preliminary cell-based studies show that the new inhibitors impact cell proliferation in a rhabdoid tumor cell line.
Subject(s)
Antineoplastic Agents/pharmacology , Peptides/pharmacology , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb-Group Proteins/antagonists & inhibitors , Antineoplastic Agents/chemistry , Cell Line , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Humans , Ligands , Molecular Structure , Peptides/chemistry , Polycomb Repressive Complex 1/metabolism , Polycomb-Group Proteins/metabolism , Structure-Activity RelationshipABSTRACT
Cancer stem cells (CSCs) play a critical role in invasive growth and metastasis of human head and neck squamous cell carcinoma (HNSCC). Although significant progress has been made in understanding the self-renewal and pro-tumorigenic potentials of CSCs, a key challenge remains on how to eliminate CSCs and halt metastasis effectively. Here we show that super-enhancers (SEs) play a critical role in the transcription of cancer stemness genes as well as pro-metastatic genes, thereby controlling their tumorigenic potential and metastasis. Mechanistically, we find that bromodomain-containing protein 4 (BRD4) recruits Mediators and NF-κB p65 to form SEs at cancer stemness genes such as TP63, MET and FOSL1, in addition to oncogenic transcripts. In vivo lineage tracing reveals that disrupting SEs by BET inhibitors potently inhibited CSC self-renewal and eliminated CSCs in addition to elimination of proliferating non-stem tumor cells in a mouse model of HNSCC. Moreover, disrupting SEs also inhibits the invasive growth and lymph node metastasis of human CSCs isolated from human HNSCC. Taken together, our results suggest that targeting SEs may serve as an effective therapy for HNSCC by eliminating CSCs.
Subject(s)
Enhancer Elements, Genetic , Head and Neck Neoplasms/pathology , Neoplastic Stem Cells/drug effects , Squamous Cell Carcinoma of Head and Neck/pathology , Animals , Antineoplastic Agents/pharmacology , Azepines/pharmacology , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cell Line, Tumor , Gene Expression Regulation, Neoplastic , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/genetics , Humans , Lymphatic Metastasis/drug therapy , Lymphatic Metastasis/prevention & control , Mediator Complex Subunit 1/genetics , Mediator Complex Subunit 1/metabolism , Mice, Inbred C57BL , Mice, SCID , NF-kappa B/genetics , Neoplastic Stem Cells/pathology , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/metabolism , Squamous Cell Carcinoma of Head and Neck/drug therapy , Squamous Cell Carcinoma of Head and Neck/genetics , Transcription Factors/genetics , Transcription Factors/metabolism , Triazoles/pharmacology , Xenograft Model Antitumor AssaysABSTRACT
Polycomb repressive complex 1 (PRC1) is an essential chromatin-modifying complex that monoubiquitinates histone H2A and is involved in maintaining the repressed chromatin state. Emerging evidence suggests PRC1 activity in various cancers, rationalizing the need for small-molecule inhibitors with well-defined mechanisms of action. Here, we describe the development of compounds that directly bind to RING1B-BMI1, the heterodimeric complex constituting the E3 ligase activity of PRC1. These compounds block the association of RING1B-BMI1 with chromatin and inhibit H2A ubiquitination. Structural studies demonstrate that these inhibitors bind to RING1B by inducing the formation of a hydrophobic pocket in the RING domain. Our PRC1 inhibitor, RB-3, decreases the global level of H2A ubiquitination and induces differentiation in leukemia cell lines and primary acute myeloid leukemia (AML) samples. In summary, we demonstrate that targeting the PRC1 RING domain with small molecules is feasible, and RB-3 represents a valuable chemical tool to study PRC1 biology.
Subject(s)
Polycomb Repressive Complex 1/antagonists & inhibitors , Small Molecule Libraries/pharmacology , Cell Differentiation/drug effects , Dose-Response Relationship, Drug , Humans , K562 Cells , Models, Molecular , Molecular Structure , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/metabolism , Small Molecule Libraries/chemical synthesis , Small Molecule Libraries/chemistry , Ubiquitination/drug effectsABSTRACT
Polycomb group (PcG) proteins maintain cell identity by repressing gene expression during development. Surprisingly, emerging studies have recently reported that a number of PcG proteins directly activate gene expression during cell fate determination process. However, the mechanisms by which they direct gene activation in pluripotency remain poorly understood. Here, we show that Phc1, a subunit of canonical polycomb repressive complex 1 (cPRC1), can exert its function in pluripotency maintenance via a PRC1-independent activation of Nanog. Ablation of Phc1 reduces the expression of Nanog and overexpression of Nanog partially rescues impaired pluripotency caused by Phc1 depletion. We find that Phc1 interacts with Nanog and activates Nanog transcription by stabilizing the genome-wide chromatin interactions of the Nanog locus. This adds to the already known canonical function of PRC1 in pluripotency maintenance via a PRC1-dependent repression of differentiation genes. Overall, our study reveals a function of Phc1 to activate Nanog transcription through regulating chromatin architecture and proposes a paradigm for PcG proteins to maintain pluripotency.
Subject(s)
Chromatin/genetics , Induced Pluripotent Stem Cells/cytology , Induced Pluripotent Stem Cells/physiology , Nanog Homeobox Protein/genetics , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/physiology , Animals , Cells, Cultured , Gene Knockdown Techniques , Gene Knockout Techniques , Genome, Human , Human Embryonic Stem Cells/cytology , Human Embryonic Stem Cells/physiology , Humans , Mice , Mice, Inbred NOD , Mice, SCID , Models, Genetic , Mouse Embryonic Stem Cells/cytology , Mouse Embryonic Stem Cells/physiology , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/deficiencyABSTRACT
The BMI1 protein, a member of the PRC1 family, is a well recognised transcriptional suppressor and has the capability of maintaining the self-renewal and proliferation of tissue-specific stem cells. Numerous studies have established that BMI1 is highly expressed in a variety of malignant cancers and serves as a key regulator in the tumorigenesis process. However, our understanding of BMI1 in terminally differentiated organs, such as the heart, is relatively nascent. Importantly, emerging data support that, beyond the tumor, BMI1 is also expressed in the heart tissue and indeed exerts profound effects in various cardiac pathological conditions. This review gives a summary of the novel functions of BMI1 in the heart, including BMI1-positive cardiac stem cells and BMI1-mediated signaling pathways, which are involved in the response to various cardiac pathological stimuli. Besides, we summarize the recent progress of BMI1 in some novel and rapidly developing cardiovascular therapies. Furtherly, we highlight the properties of BMI1, a therapeutic target proved effective in cancer treatment, as a promising target to alleviate cardiovascular diseases.
Subject(s)
Myocardium/metabolism , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/metabolism , Animals , Biomarkers , Cardiovascular Diseases/drug therapy , Cardiovascular Diseases/etiology , Cardiovascular Diseases/metabolism , Cell Transformation, Neoplastic/genetics , Cell Transformation, Neoplastic/metabolism , Disease Susceptibility , Drug Discovery , Gene Expression Regulation , Humans , Molecular Targeted Therapy , Neoplasms/drug therapy , Neoplasms/etiology , Neoplasms/metabolism , Neoplasms/pathology , Organ Specificity , Polycomb Repressive Complex 1/antagonists & inhibitors , Signal Transduction , Stem Cells/metabolismABSTRACT
Diffuse intrinsic pontine glioma (DIPG) is an incurable brain tumor of childhood characterized by histone mutations at lysine 27, which results in epigenomic dysregulation. There has been a failure to develop effective treatment for this tumor. Using a combined RNAi and chemical screen targeting epigenomic regulators, we identify the polycomb repressive complex 1 (PRC1) component BMI1 as a critical factor for DIPG tumor maintenance in vivo. BMI1 chromatin occupancy is enriched at genes associated with differentiation and tumor suppressors in DIPG cells. Inhibition of BMI1 decreases cell self-renewal and attenuates tumor growth due to induction of senescence. Prolonged BMI1 inhibition induces a senescence-associated secretory phenotype, which promotes tumor recurrence. Clearance of senescent cells using BH3 protein mimetics co-operates with BMI1 inhibition to enhance tumor cell killing in vivo.
Subject(s)
Aging/genetics , Diffuse Intrinsic Pontine Glioma/genetics , Polycomb Repressive Complex 1/metabolism , Astrocytoma/genetics , Brain Stem Neoplasms/drug therapy , Brain Stem Neoplasms/genetics , Cell Differentiation/genetics , Cell Line, Tumor , Cell Proliferation/drug effects , Child , Child, Preschool , Chromatin/genetics , Diffuse Intrinsic Pontine Glioma/drug therapy , Diffuse Intrinsic Pontine Glioma/metabolism , Epigenomics , Female , Glioma/drug therapy , Glioma/genetics , Glioma/pathology , Histones/metabolism , Humans , Lysine/metabolism , Male , Mutation , Neoplasm Recurrence, Local/drug therapy , Neoplasm Recurrence, Local/genetics , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/geneticsABSTRACT
Epigenetic regulation is mainly mediated by enzymes that can modify the structure of chromatin by altering the structure of DNA or histones. Proteins involved in epigenetic processes have been identified to study the detailed molecular mechanisms involved in the regulation of specific mRNA expression. Evolutionarily well-conserved polycomb group (PcG) proteins can function as transcriptional repressors by the trimethylation of histone H3 at the lysine 27 residue (H3K27me3) and the monoubiquitination of histone H2A at the lysine 119 residue (H2AK119ub). PcG proteins form two functionally distinct protein complexes: polycomb repressor complex 1 (PRC1) and PRC2. In mammals, the structural heterogeneity of each PRC complex is dramatically increased by several paralogs of its subunit proteins. Genetic studies with transgenic mice along with RNA-seq and chromatin immunoprecipitation (ChIP)-seq analyses might be helpful for defining the cell-specific functions of paralogs of PcG proteins. Here, we summarize current knowledge about the immune regulatory role of PcG proteins related to the compositional diversity of each PRC complex and introduce therapeutic drugs that target PcG proteins in hematopoietic malignancy.
Subject(s)
Immunity , Mammals/immunology , Polycomb Repressive Complex 1/chemistry , Polycomb Repressive Complex 1/metabolism , Animals , Clinical Trials as Topic , Hematologic Neoplasms/pathology , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Humans , Polycomb Repressive Complex 1/antagonists & inhibitorsABSTRACT
Renal ischemia-reperfusion injury (I/R) usually occurs in renal transplantation and partial nephrectomy, which could lead to acute kidney injury. However, the effective treatment for renal I/R still remains limited. In the present study, we investigated whether inhibition of chromobox 7 (CBX7) could attenuate renal I/R injury in vivo and in vitro as well as the potential mechanisms. Adult male mice were subjected to right renal ischemia and reperfusion for different periods, both with and without the CBX7 inhibitor UNC3866. In addition, human kidney cells (HK-2) were subjected to a hypoxia/reoxygenation (H/R) process for different periods, both with or without the CBX7 inhibitor or siRNA for CBX7. The results showed that expression of CBX7, glucose regulator protein-78 (GRP78), phosphorylated eukaryotic translation initiation factor-2α (p-eIF2α), and C/EBP homologous protein (CHOP) were increased after extension of I/R and H/R periods. Moreover, overexpression of CBX7 could elevate the expression of CBX7, GRP78, p-eIF2α, and CHOP. However, CBX7 inhibition with either UNC3866 or genetic knockdown led to reduced expression of GRP78, p-eIF2α, and CHOP through nuclear factor-erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 activation in I/R and H/R injury. Furthermore, ML385, the Nrf2 inhibitor, could elevate endoplasmic reticulum stress levels, abrogating the protective effects of UNC3866 against renal I/R injury. In conclusion, our results demonstrated that CBX7 inhibition alleviated acute kidney injury by preventing endoplasmic reticulum stress via the Nrf2/HO-1 pathway, indicating that CBX7 inhibitor could be a potential therapeutic target for renal I/R injury.
Subject(s)
Acute Kidney Injury/prevention & control , Endoplasmic Reticulum Stress/drug effects , Heme Oxygenase-1/metabolism , Kidney/drug effects , Membrane Proteins/metabolism , NF-E2-Related Factor 2/metabolism , Oligopeptides/pharmacology , Polycomb Repressive Complex 1/antagonists & inhibitors , Reperfusion Injury/prevention & control , Acute Kidney Injury/enzymology , Acute Kidney Injury/genetics , Acute Kidney Injury/pathology , Animals , Cell Hypoxia , Cell Line , Endoplasmic Reticulum Chaperone BiP , Heme Oxygenase-1/genetics , Humans , Kidney/enzymology , Kidney/pathology , Male , Membrane Proteins/genetics , Mice , NF-E2-Related Factor 2/genetics , Polycomb Repressive Complex 1/genetics , Polycomb Repressive Complex 1/metabolism , Reperfusion Injury/enzymology , Reperfusion Injury/genetics , Reperfusion Injury/pathology , Signal TransductionABSTRACT
BMI1 is a core protein of the polycomb repressive complex 1 (PRC1) that is overexpressed in several cancer types, making it a promising target for cancer therapies. However, the underlying mechanisms and interactions associated with BMI1-induced tumorigenesis are often context-dependent and complex. Here, we performed a drug resistance screen on mutagenized human haploid HAP1 cells treated with BMI1 inhibitor PTC-318 to find new genetic and mechanistic features associated with BMI1-dependent cancer cell proliferation. Our screen identified NUMA1-mutations as the most significant inducer of PTC-318 cell death resistance. Independent validations on NUMA1-proficient HAP1 and non-small cell lung cancer cell lines exposed to BMI1 inhibition by PTC-318 or BMI1 knockdown resulted in cell death following mitotic arrest. Interestingly, cells with CRISPR-Cas9 derived NUMA1 knockout also showed a mitotic arrest phenotype following BMI1 inhibition but, contrary to cells with wildtype NUMA1, these cells were resistant to BMI1-dependent cell death. The current study brings new insights to BMI1 inhibition-induced mitotic lethality in cancer cells and presents a previously unknown role of NUMA1 in this process.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinogenesis/genetics , Cell Cycle Proteins/genetics , Drug Resistance, Neoplasm/genetics , Neoplasms/genetics , Polycomb Repressive Complex 1/metabolism , Antineoplastic Agents/therapeutic use , Apoptosis/drug effects , Apoptosis/genetics , CRISPR-Cas Systems/genetics , Carcinogenesis/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , Gene Knockdown Techniques , Gene Knockout Techniques , Humans , M Phase Cell Cycle Checkpoints/drug effects , Mutation , Neoplasms/drug therapy , Neoplasms/pathology , Polycomb Repressive Complex 1/antagonists & inhibitors , Polycomb Repressive Complex 1/genetics , RNA, Small Interfering/metabolismABSTRACT
Future progress in the treatment of multiple myeloma (MM) requires both the characterisation of key drivers of the disease and novel, innovative approaches to tackle these vulnerabilities. The present study focussed on the pre-clinical evaluation of a novel drug class, BMI-1 modulators, in MM. We demonstrate potent activity of PTC-028 and PTC596 in a comprehensive set of in vitro and in vivo models, including models of drug resistance and stromal support. Treatment of MM cells with PTC-028 and PTC596 downregulated BMI-1 protein levels, which was found to correlate with drug activity. Surprisingly, BMI-1 was dispensable for the activity of BMI-1 modulators and MM cell growth. Our data rather point to mitotic arrest accompanied by myeloid cell leukaemia-1 (MCL-1) loss as key anti-MM mechanisms and reveal impaired MYC and AKT signalling activity due to BMI-1 modulator treatment. Moreover, we observed a complete eradication of MM after PTC596 treatment in the 5TGM.1 in vivo model and define epigenetic compounds and B cell leukaemia/lymphoma 2 homology domain 3 (BH3) mimetics as promising combination partners. These results bring into question the postulated role of BMI-1 as an essential MM gene and confirm BMI-1 modulators as potent anti-mitotic agents with encouraging pre-clinical activity that supports their rapid translation into clinical trials.
Subject(s)
Antineoplastic Agents/pharmacology , Benzimidazoles/pharmacology , Mitosis/drug effects , Multiple Myeloma , Neoplasm Proteins/antagonists & inhibitors , Neoplasms, Experimental , Polycomb Repressive Complex 1/antagonists & inhibitors , Pyrazines/pharmacology , Animals , Female , Humans , Male , Mice , Multiple Myeloma/diet therapy , Multiple Myeloma/enzymology , Multiple Myeloma/pathology , Neoplasm Proteins/metabolism , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/enzymology , Neoplasms, Experimental/pathology , Polycomb Repressive Complex 1/metabolism , Xenograft Model Antitumor AssaysABSTRACT
The development of therapeutic approaches based on direct cardiac reprogramming of fibroblasts into induced-cardiomyocytes (iCM) has emerged as an attractive strategy to repair the injured myocardium. The identification of the mechanisms driving lineage conversion represents a crucial step toward the development of new and more efficient regenerative strategies. To this aim, here we show that pre-treatment with the Bmi1 inhibitor PTC-209 is sufficient to increase the efficiency of Chemical-induced Direct Cardiac Reprogramming both in mouse embryonic fibroblasts and adult cardiac fibroblasts. PTC-209 induces an overall increase of spontaneously beating iCM at end-stage of reprogramming, expressing high levels of late cardiac markers Troponin T and myosin muscle light chain-2v. The inhibition of Bmi1 expression occurring upon PTC-209 pre-treatment was maintained throughout the reprogramming protocol, contributing to a significant gene expression de-regulation. RNA profiling revealed that, upon Bmi1 inhibition a significant down-regulation of genes associated with immune and inflammatory signalling pathways occurred, with repression of different genes involved in interleukin, cytokine and chemokine pathways. Accordingly, we observed the down-regulation of both JAK/STAT3 and MAPK/ERK1-2 pathway activation, highlighting the crucial role of these pathways as a barrier for cardiac reprogramming. These findings have significant implications for the development of new cardiac regenerative therapies.
Subject(s)
Cellular Reprogramming/drug effects , Heterocyclic Compounds, 2-Ring/pharmacology , Myocytes, Cardiac/drug effects , Polycomb Repressive Complex 1/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Thiazoles/pharmacology , Animals , Biomarkers/metabolism , Cardiac Myosins/metabolism , Down-Regulation , Fibroblasts/drug effects , Mice , Myocytes, Cardiac/cytology , Myocytes, Cardiac/metabolism , Myosin Light Chains/metabolism , Polycomb Repressive Complex 1/metabolism , Proto-Oncogene Proteins/metabolism , Signal Transduction , Troponin T/metabolismABSTRACT
Chromobox homolog 2 (CBX2), a key member of the polycomb group (PcG) family, is essential for gonadal development in mammals. A functional deficiency or genetic mutation in cbx2 can lead to sex reversal in mice and humans. However, little is known about the function of cbx2 in gonadal development in fish. In this study, the cbx2 gene was identified in medaka, which is a model species for the study of gonadal development in fish. Transcription of cbx2 was abundant in the gonads, with testicular levels relatively higher than ovarian levels. In situ hybridization (ISH) revealed that cbx2 mRNA was predominately localized in spermatogonia and spermatocytes, and was also observed in oocytes at stages I, II, and III. Furthermore, cbx2 and vasa (a marker gene) were co-localized in germ cells by fluorescent in situ hybridization (FISH). After cbx2 knockdown in the gonads by RNA interference (RNAi), the sex-related genes, including sox9 and foxl2, were influenced. These results suggest that cbx2 not only plays a positive role in spermatogenesis and oogenesis but is also involved in gonadal differentiation through regulating the expression levels of sex-related genes in fish.