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BioRxiv : the Preprint Server For... Feb 2024The stress-associated molecular chaperone system is an actionable target in cancer therapies. It is ubiquitously upregulated in cancer tissues and enables tumorigenicity...
The stress-associated molecular chaperone system is an actionable target in cancer therapies. It is ubiquitously upregulated in cancer tissues and enables tumorigenicity by stabilizing hundreds of oncoproteins and disturbing the stoichiometry of protein complexes. Most inhibitors target the key component heat-shock protein 90 (HSP90). However, although classical HSP90 inhibitors are highly tumor-selective, they fail in phase 3 clinical oncology trials. These failures are at least partly due to an interference with a negative feedback loop by HSP90 inhibition, known as heat-shock response (HSR): in response to HSP90 inhibition there is compensatory synthesis of stress-inducible chaperones, mediated by the transcription factor heat-shock factor 1 (HSF1). We recently identified that wildtype p53 (p53) actively reduces the HSR by repressing HSF1 via a p21-CDK4/6-MAPK-HSF1 axis. Here we test the hypothesis that in HSP90-based therapies simultaneous p53 activation or direct cell cycle inhibition interrupts the deleterious HSF1-HSR axis and improves the efficiency of HSP90 inhibitors. Indeed, we find that the clinically relevant p53 activator Idasanutlin suppresses the HSF1-HSR activity in HSP90 inhibitor-based therapies. This combination synergistically reduces cell viability and accelerates cell death in p53-proficient colorectal cancer (CRC) cells, murine tumor-derived organoids and patient-derived organoids (PDOs). Mechanistically, upon combination therapy human CRC cells strongly upregulate p53-associated pathways, apoptosis, and inflammatory immune pathways. Likewise, in the chemical AOM/DSS CRC model in mice, dual HSF1-HSP90 inhibition strongly represses tumor growth and remodels immune cell composition, yet displays only minor toxicities in mice and normal mucosa-derived organoids. Importantly, inhibition of the cyclin dependent kinases 4 and 6 (CDK4/6) under HSP90 inhibition phenocopies synergistic repression of the HSR in p53-proficient CRC cells. Even more important, in p53-deficient (mutp53-harboring) CRC cells, an HSP90 inhibition in combination with CDK4/6 inhibitors similarly suppresses the HSF1-HSR system and reduces cancer growth. Likewise, p53-mutated PDOs strongly respond to dual HSF1-HSP90 pathway inhibition and thus, providing a strategy to target CRC independent of the p53 status. In sum, activating p53 (in p53-proficient cancer cells) or inhibiting CDK4/6 (independent of the p53 status) provide new options to improve the clinical outcome of HSP90-based therapies and to enhance colorectal cancer therapy.
PubMed: 38464125
DOI: 10.1101/2024.02.22.581507 -
BioRxiv : the Preprint Server For... Mar 2024Early defects at the neuromuscular junction (NMJ) are among the first hallmarks of the progressive neurodegenerative disease amyotrophic lateral sclerosis (ALS)....
Early defects at the neuromuscular junction (NMJ) are among the first hallmarks of the progressive neurodegenerative disease amyotrophic lateral sclerosis (ALS). According to the "dying back" hypothesis, disruption of the NMJ not only precedes, but is also a trigger for the subsequent degeneration of the motoneuron in both sporadic and familial ALS, including ALS caused by the severe pathogenic variant P525L. However, the mechanisms linking genetic and environmental factors to NMJ defects remain elusive. By taking advantage of co-cultures of motoneurons and skeletal muscle derived from human induced pluripotent stem cells (iPSCs), we show that the neural RNA binding protein HuD (ELAVL4) may underlie NMJ defects and apoptosis in FUS-ALS. HuD overexpression in motoneurons phenocopies the severe FUS mutation, while HuD knockdown in FUS co-cultures produces phenotypic rescue. We validated these findings in a FUS-ALS model. Neuronal-restricted overexpression of the HuD-related gene, , produces a motor phenotype, while neuronal-restricted knockdown significantly rescues motor dysfunction caused by FUS. Finally, we show that HuD levels increase upon oxidative stress in human motoneurons and in sporadic ALS patients with an oxidative stress signature. On these bases, we propose HuD as an important player downstream of FUS mutation in familial ALS, with potential implications for sporadic ALS related to oxidative stress.
PubMed: 38464028
DOI: 10.1101/2023.08.22.554258 -
Molecular Oncology Mar 2024Acute myeloid leukaemia (AML) is a clonal haematological malignancy affecting the myeloid lineage, with generally poor patient outcomes owing to the lack of targeted...
Acute myeloid leukaemia (AML) is a clonal haematological malignancy affecting the myeloid lineage, with generally poor patient outcomes owing to the lack of targeted therapies. The histone lysine demethylase 4A (KDM4A) has been established as a novel therapeutic target in AML, due to its selective oncogenic role within leukaemic cells. We identify that the transcription factor nuclear factor of activated T cells 2 (NFATC2) is a novel binding and transcriptional target of KDM4A in the human AML THP-1 cell line. Furthermore, cytogenetically diverse AML cell lines, including THP-1, were dependent on NFATC2 for colony formation in vitro, highlighting a putative novel mechanism of AML oncogenesis. Our study demonstrates that NFATC2 maintenance of cell cycle progression in human AML cells was driven primarily by CCND1. Through RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq), NFATc2 was shown to bind to the promoter region of genes involved in oxidative phosphorylation and subsequently regulate their gene expression in THP-1 cells. Furthermore, our data show that NFATC2 shares transcriptional targets with the transcription factor c-MYC, with MYC knockdown phenocopying NFATC2 knockdown. These data suggest a newly identified co-ordinated role for NFATC2 and MYC in the maintenance of THP-1 cell function, indicative of a potential means of therapeutic targeting in human AML.
PubMed: 38459421
DOI: 10.1002/1878-0261.13630 -
Cancer Cell Apr 2024SMARCA4 encodes one of two mutually exclusive ATPase subunits in the BRG/BRM associated factor (BAF) complex that is recruited by transcription factors (TFs) to drive...
SMARCA4 encodes one of two mutually exclusive ATPase subunits in the BRG/BRM associated factor (BAF) complex that is recruited by transcription factors (TFs) to drive chromatin accessibility and transcriptional activation. SMARCA4 is among the most recurrently mutated genes in human cancer, including ∼30% of germinal center (GC)-derived Burkitt lymphomas. In mice, GC-specific Smarca4 haploinsufficiency cooperated with MYC over-expression to drive lymphomagenesis. Furthermore, monoallelic Smarca4 deletion drove GC hyperplasia with centroblast polarization via significantly increased rates of centrocyte recycling to the dark zone. Mechanistically, Smarca4 loss reduced the activity of TFs that are activated in centrocytes to drive GC-exit, including SPI1 (PU.1), IRF family, and NF-κB. Loss of activity for these factors phenocopied aberrant BCL6 activity within murine centrocytes and human Burkitt lymphoma cells. SMARCA4 therefore facilitates chromatin accessibility for TFs that shape centrocyte trajectories, and loss of fine-control of these programs biases toward centroblast cell-fate, GC hyperplasia and lymphoma.
Topics: Animals; Humans; Mice; Chromatin; DNA Helicases; Haploinsufficiency; Hyperplasia; Lymphoma, B-Cell; Nuclear Proteins; Transcription Factors
PubMed: 38458188
DOI: 10.1016/j.ccell.2024.02.011 -
Cancer Research Communications Mar 2024Epithelial-mesenchymal transition (EMT) in cancer promotes metastasis and chemotherapy resistance. A subset of triple-negative breast cancer (TNBC) exhibits a...
UNLABELLED
Epithelial-mesenchymal transition (EMT) in cancer promotes metastasis and chemotherapy resistance. A subset of triple-negative breast cancer (TNBC) exhibits a mesenchymal gene signature that is associated with poor patient outcomes. We previously identified PTK6 tyrosine kinase as an oncogenic driver of EMT in a subset of TNBC. PTK6 induces EMT by stabilizing SNAIL, a key EMT-initiating transcriptional factor. Inhibition of PTK6 activity reverses mesenchymal features of TNBC cells and suppresses their metastases by promoting SNAIL degradation via a novel mechanism. In the current study, we identify membrane-associated RING-CH2 (MARCH2) as a novel PTK6-regulated E3 ligase that promotes the ubiquitination and degradation of SNAIL protein. The MARCH2 RING domain is critical for SNAIL ubiquitination and subsequent degradation. PTK6 inhibition promotes the interaction of MARCH2 with SNAIL. Overexpression of MARCH2 exhibits tumor suppressive properties and phenocopies the effects of SNAIL downregulation and PTK6 inhibition in TNBC cells, such as inhibition of migration, anoikis resistance, and metastasis. Consistent with this, higher levels of MARCH2 expression in breast and other cancers are associated with better prognosis. We have identified MARCH2 as a novel SNAIL E3 ligase that regulates EMT and metastases of mesenchymal TNBC.
SIGNIFICANCE
EMT is a process directly linked to drug resistance and metastasis of cancer cells. We identified MARCH2 as a novel regulator of SNAIL, a key EMT driver, that promotes SNAIL ubiquitination and degradation in TNBC cells. MARCH2 is oncogene regulated and inhibits growth and metastasis of TNBC. These insights could contribute to novel strategies to therapeutically target TNBC.
Topics: Humans; Gene Expression Regulation; Oncogenes; Triple Negative Breast Neoplasms; Ubiquitin-Protein Ligases; Ubiquitination; Membrane Proteins
PubMed: 38457262
DOI: 10.1158/2767-9764.CRC-23-0090 -
EMBO Reports Apr 2024Teratozoospermia is a significant cause of male infertility, but the pathogenic mechanism of acephalic spermatozoa syndrome (ASS), one of the most severe...
Teratozoospermia is a significant cause of male infertility, but the pathogenic mechanism of acephalic spermatozoa syndrome (ASS), one of the most severe teratozoospermia, remains elusive. We previously reported Spermatogenesis Associated 6 (SPATA6) as the component of the sperm head-tail coupling apparatus (HTCA) required for normal assembly of the sperm head-tail conjunction, but the underlying molecular mechanism has not been explored. Here, we find that the co-chaperone protein BAG5, expressed in step 9-16 spermatids, is essential for sperm HTCA assembly. BAG5-deficient male mice show abnormal assembly of HTCA, leading to ASS and male infertility, phenocopying SPATA6-deficient mice. In vivo and in vitro experiments demonstrate that SPATA6, cargo transport-related myosin proteins (MYO5A and MYL6) and dynein proteins (DYNLT1, DCTN1, and DNAL1) are misfolded upon BAG5 depletion. Mechanistically, we find that BAG5 forms a complex with HSPA8 and promotes the folding of SPATA6 by enhancing HSPA8's affinity for substrate proteins. Collectively, our findings reveal a novel protein-regulated network in sperm formation in which BAG5 governs the assembly of the HTCA by activating the protein-folding function of HSPA8.
Topics: Animals; Humans; Male; Mice; Adaptor Proteins, Signal Transducing; Cytoskeletal Proteins; Dyneins; HSC70 Heat-Shock Proteins; Infertility, Male; Molecular Chaperones; Protein Folding; Semen; Sperm Head; Spermatogenesis; Spermatozoa; Teratozoospermia; Thiazoles
PubMed: 38454159
DOI: 10.1038/s44319-024-00112-x -
Nature Communications Mar 2024Recent studies have identified a previously uncharacterized protein C11orf53 (now named POU2AF2/OCA-T1), which functions as a robust co-activator of POU2F3, the master...
Recent studies have identified a previously uncharacterized protein C11orf53 (now named POU2AF2/OCA-T1), which functions as a robust co-activator of POU2F3, the master transcription factor which is critical for both normal and neoplastic tuft cell identity and viability. Here, we demonstrate that POU2AF2 dictates opposing transcriptional regulation at distal enhance elements. Loss of POU2AF2 leads to an inhibition of active enhancer nearby genes, such as tuft cell identity genes, and a derepression of Polycomb-dependent poised enhancer nearby genes, which are critical for cell viability and differentiation. Mechanistically, depletion of POU2AF2 results in a global redistribution of the chromatin occupancy of the SWI/SNF complex, leading to a significant 3D genome structure change and a subsequent transcriptional reprogramming. Our genome-wide CRISPR screen further demonstrates that POU2AF2 depletion or SWI/SNF inhibition leads to a PTEN-dependent cell growth defect, highlighting a potential role of POU2AF2-SWI/SNF axis in small cell lung cancer (SCLC) pathogenesis. Additionally, pharmacological inhibition of SWI/SNF phenocopies POU2AF2 depletion in terms of gene expression alteration and cell viability decrease in SCLC-P subtype cells. Therefore, impeding POU2AF2-mediated transcriptional regulation represents a potential therapeutic approach for human SCLC therapy.
Topics: Humans; Gene Expression Regulation; Transcription Factors; Lung Neoplasms; Cell Differentiation; Regulatory Sequences, Nucleic Acid; Small Cell Lung Carcinoma
PubMed: 38453939
DOI: 10.1038/s41467-024-46492-5 -
Biology Open Mar 2024Loss of Cdx2 in vivo leads to stunted development of the allantois, an extraembryonic mesoderm-derived structure critical for nutrient delivery and waste removal in the...
Loss of Cdx2 in vivo leads to stunted development of the allantois, an extraembryonic mesoderm-derived structure critical for nutrient delivery and waste removal in the early embryo. Here, we investigate how CDX2 dose-dependently influences the gene regulatory network underlying extraembryonic mesoderm development. By engineering human induced pluripotent stem cells (hiPSCs) consisting of wild-type (WT), heterozygous (CDX2-Het), and homozygous null CDX2 (CDX2-KO) genotypes, differentiating these cells in a 2D gastruloid model, and subjecting these cells to single-nucleus RNA and ATAC sequencing, we identify several pathways that are dose-dependently regulated by CDX2 including VEGF and non-canonical WNT. snATAC-seq reveals that CDX2-Het cells retain a WT-like chromatin accessibility profile, suggesting accessibility alone is not sufficient to drive this variability in gene expression. Because the loss of CDX2 or TBXT phenocopy one another in vivo, we compared differentially expressed genes in our CDX2-KO to those from TBXT-KO hiPSCs differentiated in an analogous experiment. This comparison identifies several communally misregulated genes that are critical for cytoskeletal integrity and tissue permeability. Together, these results clarify how CDX2 dose-dependently regulates gene expression in the extraembryonic mesoderm and reveal pathways that may underlie the defects in vascular development and allantoic elongation seen in vivo.
Topics: Humans; CDX2 Transcription Factor; Cell Differentiation; Embryo, Mammalian; Gene Regulatory Networks; Induced Pluripotent Stem Cells; Mesoderm; Gene Dosage
PubMed: 38451093
DOI: 10.1242/bio.060323 -
The Canadian Journal of Cardiology May 2024Hypertrophic cardiomyopathy (HCM) is a common myocardial disease defined by increased left ventricular wall thickness unexplained by loading conditions. HCM frequently... (Review)
Review
Hypertrophic cardiomyopathy (HCM) is a common myocardial disease defined by increased left ventricular wall thickness unexplained by loading conditions. HCM frequently is caused by pathogenic variants in sarcomeric protein genes, but several other syndromic, metabolic, infiltrative, and neuromuscular diseases can result in HCM phenocopies. This review summarizes the current understanding of these HCM mimics, highlighting their importance across the life course. The central role of a comprehensive, multiparametric diagnostic approach and the potential of precision medicine in tailoring treatment strategies are emphasized.
Topics: Humans; Cardiomyopathy, Hypertrophic; Diagnosis, Differential; Phenotype
PubMed: 38447917
DOI: 10.1016/j.cjca.2024.02.025 -
MBio Apr 2024Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including and , the ESAT-6...
Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including and , the ESAT-6 system 1 (ESX-1) secretion is crucial for host interaction. Secretion of protein substrates by the ESX-1 secretion system disrupts phagosomes, allowing mycobacteria cytoplasmic access during macrophage infections. Deletion or mutation of the ESX-1 system attenuates mycobacterial pathogens. Pathogenic mycobacteria respond to the presence or absence of the ESX-1 system in the cytoplasmic membrane by altering transcription. Under laboratory conditions, the EspM repressor and WhiB6 activator control transcription of specific ESX-1-responsive genes, including the ESX-1 substrate genes. However, deleting the or gene does not phenocopy the deletion of the ESX-1 substrate genes during macrophage infection by . In this study, we identified EspN, a critical transcription factor whose activity is masked by the EspM repressor under laboratory conditions. In the absence of EspM, EspN activates transcription of and ESX-1 genes during both laboratory growth and macrophage infection. EspN is also independently required for growth within and cytolysis of macrophages, similar to the ESX-1 genes, and for disease burden in a zebrafish larval model of infection. These findings suggest that EspN and EspM coordinate to counterbalance the regulation of the ESX-1 system and support mycobacterial pathogenesis.IMPORTANCEPathogenic mycobacteria, which are responsible for tuberculosis and other long-term diseases, use the ESX-1 system to transport proteins that control the host response to infection and promote bacterial survival. In this study, we identify an undescribed transcription factor that controls the expression of ESX-1 genes and is required for both macrophage and animal infection. However, this transcription factor is not the primary regulator of ESX-1 genes under standard laboratory conditions. These findings identify a critical transcription factor that likely controls expression of a major virulence pathway during infection, but whose effect is not detectable with standard laboratory strains and growth conditions.
Topics: Animals; Transcription Factors; Bacterial Proteins; Type VII Secretion Systems; Zebrafish; Tuberculosis; Mycobacterium tuberculosis; Mycobacterium marinum
PubMed: 38445877
DOI: 10.1128/mbio.03357-23