ZFHX4 interacts with the NuRD core member CHD4 and regulates the glioblastoma tumor-initiating cell state

Loss of function of the zinc finger homeobox 4 gene, ZFHX4, underlies a neurodevelopmental disorder

8q21.11 microdeletions involving ZFHX4 have previously been associated with a syndromic form of intellectual disability, hypotonia, unstable gait, and hearing loss. We report on 63 individuals-57 probands and 6 affected family members-with protein-truncating variants (n = 41), (micro)deletions (n = 21), or an inversion (n = 1) affecting ZFHX4. Probands display variable developmental delay and intellectual disability, distinctive facial characteristics, morphological abnormalities of the central nervous system, behavioral alterations, short stature, hypotonia, and occasionally cleft palate and anterior segment dysgenesis. The phenotypes associated with 8q21.11 microdeletions and ZFHX4 intragenic loss-of-function (LoF) variants largely overlap, although leukocyte-derived DNA shows a mild common methylation profile for (micro)deletions. ZFHX4 shows increased expression during human brain development and neuronal differentiation. Furthermore, ZFHX4-interacting factors identified via immunoprecipitation followed by mass spectrometry (IP-MS) suggest an important role for ZFHX4 in cellular pathways, especially during histone modifications, protein trafficking, signal transduction, cytosolic transport, and development. Additionally, using CUT&RUN, we observed that ZFHX4 binds the promoter of genes with crucial roles in embryonic, neuronal, and axonal development. Moreover, we investigated whether the disruption of zfhx4 causes craniofacial abnormalities in zebrafish. First-generation (F0) zfhx4 crispant zebrafish, a (mosaic) mutant for zfhx4 LoF variants, have significantly shorter Meckel's cartilage and smaller ethmoid plates compared to control zebrafish. Behavioral assays showed a decreased movement frequency in the zfhx4 crispant zebrafish in comparison with controls. Furthermore, structural abnormalities were found in the zebrafish hindbrain. In conclusion, our findings delineate a ZFHX4-associated neurodevelopmental disorder and suggest a role for zfhx4 in facial skeleton patterning, palatal development, and behavior.

Role of ZFHX4 in orofacial clefting based on human genetic data and zebrafish models

Orofacial clefting (OFC) is a frequent congenital anomaly and can occur either in the context of underlying syndromes or in isolation (nonsyndromic). The two common OFC phenotypes are cleft lip with/without cleft palate (CL/P) and cleft palate only (CPO). In this study, we searched for penetrant CL/P genes, by evaluating de novo copy number variants (CNV) from an exome sequencing dataset of 50 nonsyndromic patient-parent trios. We detected a heterozygous 86 kb de novo deletion affecting exons 4-11 of ZFHX4, a gene previously associated with OFC. Genetic and phenotypic data from our in-house and the AGORA cohort (710 and 229 individuals with nonsyndromic CL/P) together with literature and database reviews demonstrate that ZFHX4 variants can lead to both nonsyndromic and syndromic forms not only of CL/P but also CPO. Expression analysis in published single-cell RNA-sequencing data (mouse embryo, zebrafish larva) at relevant time-points support an important role of Zfhx4/zfhx4 in craniofacial development. To characterize the role of zfhx4 in zebrafish craniofacial development, we knocked out/down the zebrafish orthologue. Cartilage staining of the zfhx4 CRISPR F0 knockout and morpholino knockdown at 4 days post-fertilization showed an underdeveloped and abnormally shaped ethmoid plate and cartilaginous jaw (resembling micrognathia). While there is evidence for the dominant inheritance of ZFHX4 variants in OFC, we here present a patient with a possible recessive inheritance. In conclusion, ZFHX4 has a highly heterogeneous phenotypic spectrum and variable mode of inheritance. Our data highlight that ZFHX4 should be considered in genetic testing in patients with nonsyndromic clefting.

Predictive value of ZFHX4 mutation for the efficacy of immune checkpoint inhibitors in non-small cell lung cancer and melanoma

Studies have shown that the Zinc finger homeobox 4 (ZFHX4) might be a factor in the prognosis of malignancies. However, little is known about the association between the ZFHX4 mutation and the effectiveness of immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) and melanoma. Three public ICIs-treated NSCLC cohorts were divided into discovery cohort (n=75) and validation cohort (n=62), which were used to evaluate the relationship between ZFHX4 mutation and ICIs effectiveness in NSCLC. Seven ICIs-treated melanoma cohorts (n = 418) were used to analyze the relationship between ZFHX4 mutation and immunotherapy efficacy in melanoma. NSCLC and skin cutaneous melanoma (SKCM) cohorts from The Cancer Genome Atlas (TCGA) were used to investigate underlying mechanism. Patients with ZFHX4 mutant-type (ZFHX4-Mut) showed a superior objective response rate (ORR) (P < 0.01) and longer progression-free survival (PFS) (P < 0.05) than patients with ZFHX4 wild-type (ZFHX4-WT) in NSCLC cohorts. In the melanoma cohorts, patients carrying ZFHX4-Mut had a higher ORR (P = 0.042) and longer overall survival (OS) (P = 0.011). Besides, patients with NSCLC and melanoma harboring ZFHX4-Mut had a higher tumor mutation burden (TMB) (P<0.001) and tumor neoantigen burden (TNB) (P<0.001) than those harboring ZFHX4-WT. ZFHX4 mutation was associated with higher levels of plasma B cells, activated CD4+ memory T cells, and CD8+ T cells. Seven DNA damage repair pathways were significantly enriched in the ZFHX4-Mut group. ZFHX4 mutation could serve as a predicter for the efficacy of ICIs therapy in NSCLC and melanoma.

How does CHD4 slide nucleosomes?

Chromatin remodelling enzymes reposition nucleosomes throughout the genome to regulate the rate of transcription and other processes. These enzymes have been studied intensively since the 1990s, and yet the mechanism by which they operate has only very recently come into focus, following advances in cryoelectron microscopy and single-molecule biophysics. CHD4 is an essential and ubiquitous chromatin remodelling enzyme that until recently has received less attention than remodellers such as Snf2 and CHD1. Here we review what recent work in the field has taught us about how CHD4 reshapes the genome. Cryoelectron microscopy and single-molecule studies demonstrate that CHD4 shares a central remodelling mechanism with most other chromatin remodellers. At the same time, differences between CHD4 and other chromatin remodellers result from the actions of auxiliary domains that regulate remodeller activity by for example: (1) making differential interactions with nucleosomal epitopes such as the acidic patch and the N-terminal tail of histone H4, and (2) inducing the formation of distinct multi-protein remodelling complexes (e.g. NuRD vs ChAHP). Thus, although we have learned much about remodeller activity, there is still clearly much more waiting to be revealed.

NuRD chromatin remodeling is required to repair exogenous DSBs in the Caenorhabditis elegans germline

Organisms rely on coordinated networks of DNA repair pathways to protect genomes against toxic double-strand breaks (DSBs), particularly in germ cells. All repair mechanisms must successfully negotiate the local chromatin environment in order to access DNA. For example, nucleosomes can be repositioned by the highly conserved Nucleosome Remodeling and Deacetylase (NuRD) complex. In Caenorhabditis elegans, NuRD functions in the germline to repair DSBs - the loss of NuRD's ATPase subunit, LET-418/CHD4, prevents DSB resolution and therefore reduces fertility. In this study, we challenge germlines with exogenous DNA damage to better understand NuRD's role in repairing DSBs. We find that let-418 mutants are hypersensitive to cisplatin and hydroxyurea: exposure to either mutagen impedes DSB repair, generates aneuploid oocytes, and severely reduces fertility and embryonic survival. These defects resemble those seen when the Fanconi anemia (FA) DNA repair pathway is compromised, and we find that LET-418's activity is epistatic to that of the FA component FCD-2/FANCD2. We propose a model in which NuRD is recruited to the site of DNA lesions to remodel chromatin and allow access for FA pathway components. Together, these results implicate NuRD in the repair of both endogenous DSBs and exogenous DNA lesions to preserve genome integrity in developing germ cells.

Exploring single-cell RNA sequencing as a decision-making tool in the clinical management of Fuchs' endothelial corneal dystrophy

Single-cell RNA sequencing (scRNA-seq) has enabled the identification of novel gene signatures and cell heterogeneity in numerous tissues and diseases. Here we review the use of this technology for Fuchs' Endothelial Corneal Dystrophy (FECD). FECD is the most common indication for corneal endothelial transplantation worldwide. FECD is challenging to manage because it is genetically heterogenous, can be autosomal dominant or sporadic, and progress at different rates. Single-cell RNA sequencing has enabled the discovery of several FECD subtypes, each with associated gene signatures, and cell heterogeneity. Current FECD treatments are mainly surgical, with various Rho kinase (ROCK) inhibitors used to promote endothelial cell metabolism and proliferation following surgery. A range of emerging therapies for FECD including cell therapies, gene therapies, tissue engineered scaffolds, and pharmaceuticals are in preclinical and clinical trials. Unlike conventional disease management methods based on clinical presentations and family history, targeting FECD using scRNA-seq based precision-medicine has the potential to pinpoint the disease subtypes, mechanisms, stages, severities, and help clinicians in making the best decision for surgeries and the applications of therapeutics. In this review, we first discuss the feasibility and potential of using scRNA-seq in clinical diagnostics for FECD, highlight advances from the latest clinical treatments and emerging therapies for FECD, integrate scRNA-seq results and clinical notes from our FECD patients and discuss the potential of applying alternative therapies to manage these cases clinically.

Identification of Rocaglate Acyl Sulfamides as Selective Inhibitors of Glioblastoma Stem Cells

Glioblastoma (GBM) is the most aggressive and frequently occurring type of malignant brain tumor in adults. The initiation, progression, and recurrence of malignant tumors are known to be driven by a small subpopulation of cells known as tumor-initiating cells or cancer stem cells (CSCs). GBM CSCs play a pivotal role in orchestrating drug resistance and tumor relapse. As a prospective avenue for GBM intervention, the targeted suppression of GBM CSCs holds considerable promise. In this study, we found that rocaglates, compounds which are known to inhibit translation via targeting of the DEAD-box helicase eIF4A, exert a robust, dose-dependent cytotoxic impact on GBM CSCs with minimal killing of nonstem GBM cells. Subsequent optimization identified novel rocaglate derivatives (rocaglate acyl sulfamides or Roc ASFs) that selectively inhibit GBM CSCs with nanomolar EC50 values. Furthermore, comparative evaluation of a lead CSC-optimized Roc ASF across diverse mechanistic and target profiling assays revealed suppressed translation inhibition relative to that of other CSC-selective rocaglates, with enhanced targeting of the DEAD-box helicase DDX3X, a recently identified secondary target of rocaglates. Overall, these findings suggest a promising therapeutic strategy for targeting GBM CSCs.

Loss-of-function of the Zinc Finger Homeobox 4 (ZFHX4) gene underlies a neurodevelopmental disorder

8q21.11 microdeletions encompassing the gene encoding transcription factor ZFHX4, have previously been associated by us with a syndromic form of intellectual disability, hypotonia, decreased balance and hearing loss. Here, we report on 57 individuals, 52 probands and 5 affected family members, with protein truncating variants (n=36), (micro)deletions (n=20) or an inversion (n=1) affecting ZFHX4 with variable developmental delay and intellectual disability, distinctive facial characteristics, morphological abnormalities of the central nervous system, behavioral alterations, short stature, hypotonia, and occasionally cleft palate and anterior segment dysgenesis. The phenotypes associated with 8q21.11 microdeletions and ZFHX4 intragenic loss-of-function variants largely overlap, identifying ZFHX4 as the main driver for the microdeletion syndrome, although leukocyte-derived DNA shows a mild common methylation profile for (micro)deletions only. We identify ZFHX4 as a transcription factor that is increasingly expressed during human brain development and neuronal differentiation. Furthermore, ZFHX4 interacting factors identified via IP-MS in neural progenitor cells, suggest an important role for ZFHX4 in cellular and developmental pathways, especially during histone modifications, cytosolic transport and development. Additionally, using CUT&RUN, we observed that ZFHX4 binds with the promoter regions of genes with crucial roles in embryonic, neuron and axon development. Since loss-of-function variants in ZFHX4 are found with consistent dysmorphic facial features, we investigated whether the disruption of zfhx4 causes craniofacial abnormalities in zebrafish. First-generation (F0) zfhx4 crispant zebrafish, (mosaic) mutant for zfhx4 loss-of-function variants, have significantly shorter Meckel's cartilages and smaller ethmoid plates compared to control zebrafish. Furthermore, behavioral assays show a decreased movement frequency in the zfhx4 crispant zebrafish in comparison with control zebrafish larvae. Although further research is needed, our in vivo work suggests a role for zfhx4 in facial skeleton patterning, palatal development and behavior.

A hypoxia-glycolysis-lactate-related gene signature for prognosis prediction in hepatocellular carcinoma

BACKGROUND

Liver cancer ranks sixth in incidence and third in mortality globally and hepatocellular carcinoma (HCC) accounts for 90% of it. Hypoxia, glycolysis, and lactate metabolism have been found to regulate the progression of HCC separately. However, there is a lack of studies linking the above three to predict the prognosis of HCC. The present study aimed to identify a hypoxia-glycolysis-lactate-related gene signature for assessing the prognosis of HCC.

METHODS

This study collected 510 hypoxia-glycolysis-lactate genes from Molecular Signatures Database (MSigDB) and then classified HCC patients from TCGA-LIHC by analyzing their hypoxia-glycolysis-lactate genes expression. Differentially expressed genes (DEGs) were screened out to construct a gene signature by LASSO-Cox analysis. Univariate and multivariate regression analyses were used to evaluate the independent prognostic value of the gene signature. Analyses of immune infiltration, somatic cell mutations, and correlation heatmap were conducted by "GSVA" R package. Single-cell analysis conducted by "SingleR", "celldex", "Seurat", and "CellCha" R packages revealed how signature genes participated in hypoxia/glycolysis/lactate metabolism and PPI network identified hub genes.

RESULTS

We classified HCC patients from TCGA-LIHC into two clusters and screened out DEGs. An 18-genes prognostic signature including CDCA8, CBX2, PDE6A, MED8, DYNC1LI1, PSMD1, EIF5B, GNL2, SEPHS1, CCNJL, SOCS2, LDHA, G6PD, YBX1, RTN3, ADAMTS5, CLEC3B, and UCK2 was built to stratify the risk of HCC. The risk score of the hypoxia-glycolysis-lactate gene signature was further identified as a valuable independent factor for estimating the prognosis of HCC. Then we found that the features of clinical characteristics, immune infiltration, somatic cell mutations, and correlation analysis differed between the high-risk and low-risk groups. Furthermore, single-cell analysis indicated that the signature genes could interact with the ligand-receptors of hepatocytes/fibroblasts/plasma cells to participate in hypoxia/glycolysis/lactate metabolism and PPI network identified potential hub genes in this process: CDCA8, LDHA, YBX1.

CONCLUSION

The hypoxia-glycolysis-lactate-related gene signature we built could provide prognostic value for HCC and suggest several hub genes for future HCC studies.

CHD4 acts as a prognostic factor and drives radioresistance in HPV negative HNSCC

Despite great efforts in improving existing therapies, the outcome of patients with advanced radioresistant HPV-negative head and neck squamous cell carcinoma (HNSCC) remains poor. The chromatin remodeler Chromodomain helicase DNA binding protein 4 (CHD4) is involved in different DNA-repair mechanisms, but the role and potential in HNSCC has not been explored yet. In the present study, we evaluated the prognostic significance of CHD4 expression using in silico analysis of the pan-cancer dataset. Furthermore, we established a monoclonal HNSCC CHD4 knockdown cell clone utilizing the CRISPR/Cas9 system. Effects of lower CHD4 expression on radiosensitivity after increasing doses of ionizing radiation were characterized using clonogenic assays and cell numbers. The in silico analysis revealed that high CHD4 expression is associated with significant poorer overall survival of HPV-negative HNSCC patients. Additionally, the knockdown of CHD4 significantly increased the radiosensitivity of HNSCC cells. Therefore, CHD4 might be involved in promoting radioresistance in hard-to-treat HPV-negative HNSCC entities. We conclude that CHD4 could serve as a prognostic factor in HPV-negative HNSCC tumors and is a potential target protein overcoming radioresistance in HNSCC. Our results and the newly established cell clone laid the foundation to further characterize the underlying mechanisms and ultimately use CHD4 in HNSCC therapies.

Computational tools for inferring transcription factor activity

Transcription factors (TFs) are essential players in orchestrating the regulatory landscape in cells. Still, their exact modes of action and dependencies on other regulatory aspects remain elusive. Since TFs act cell type-specific and each TF has its own characteristics, untangling their regulatory interactions from an experimental point of view is laborious and convoluted. Thus, there is an ongoing development of computational tools that estimate transcription factor activity (TFA) from a variety of data modalities, either based on a mapping of TFs to their putative target genes or in a genome-wide, gene-unspecific fashion. These tools can help to gain insights into TF regulation and to prioritize candidates for experimental validation. We want to give an overview of available computational tools that estimate TFA, illustrate examples of their application, debate common result validation strategies, and discuss assumptions and concomitant limitations.

Fusing WGCNA and Machine Learning for Immune-Related Gene Prognostic Index in Lung Adenocarcinoma: Precision Prognosis, Tumor Microenvironment Profiling, and Biomarker Discovery

Background

The objective is to create an IRGPI (Immune-related genes prognostic index), which could predict the survival and effectiveness of immune checkpoint inhibitor (ICI) treatment for lung adenocarcinoma (LUAD).

Methods

By applying weighted gene co-expression network analysis (WGCNA), we ascertained 13 genes associated with immune functions. An IRGPI was constructed using four genes through multicox regression, and its validity was assessed in the GEO dataset. Next, we explored the immunological and molecular attributes and advantages of ICI treatment in subcategories delineated by IRGPI. The model genes were also validated by the random forest tree, and functional experiments were conducted to validate it.

Results

The IRGPI relied on the genes CD79A, IL11, CTLA-4, and CD27. Individuals categorized as low-risk exhibited significantly improved overall survival in comparison to those classified as high-risk. Extensive findings indicated that the low-risk category exhibited associations with immune pathways, significant infiltration of CD8 T cells, M1 macrophages, and CD4 T cells, a reduced rate of gene mutations, and improved sensitivity to ICI therapy. Conversely, the higher-risk group displayed metabolic signals, elevated frequencies of TP53, KRAS, and KEAP1 mutations, escalated levels of NK cells, M0, and M2 macrophage infiltration, and a diminished response to ICI therapy. Additionally, our study unveiled that the downregulation of IL11 effectively impedes the proliferation and migration of lung carcinoma cells, while also inducing cell cycle arrest.

Conclusion

IRGPI is a biomarker with significant potential for predicting the effectiveness of ICI treatment in LUAD patients and is closely related to the microenvironment and clinicopathological characteristics.

Integration of single-cell regulon atlas and multi-omics data for prognostic stratification and personalized treatment prediction in human lung adenocarcinoma

Transcriptional programs are often dysregulated in cancers. A comprehensive investigation of potential regulons is critical to the understanding of tumorigeneses. We first constructed the regulatory networks from single-cell RNA sequencing data in human lung adenocarcinoma (LUAD). We next introduce LPRI (Lung Cancer Prognostic Regulon Index), a precision oncology framework to identify new biomarkers associated with prognosis by leveraging the single cell regulon atlas and bulk RNA sequencing or microarray datasets. We confirmed that LPRI could be a robust biomarker to guide prognosis stratification across lung adenocarcinoma cohorts. Finally, a multi-omics data analysis to characterize molecular alterations associated with LPRI was performed from The Cancer Genome Atlas (TCGA) dataset. Our study provides a comprehensive chart of regulons in LUAD. Additionally, LPRI will be used to help prognostic prediction and developing personalized treatment for future studies.

In vivo loss of tumorigenicity in a patient-derived orthotopic xenograft mouse model of ependymoma

Introduction

Ependymomas (EPN) are the third most common malignant brain cancer in children. Treatment strategies for pediatric EPN have remained unchanged over recent decades, with 10-year survival rates stagnating at just 67% for children aged 0-14 years. Moreover, a proportion of patients who survive treatment often suffer long-term neurological side effects as a result of therapy. It is evident that there is a need for safer, more effective treatments for pediatric EPN patients. There are ten distinct subgroups of EPN, each with their own molecular and prognostic features. To identify and facilitate the testing of new treatments for EPN, in vivo laboratory models representative of the diverse molecular subtypes are required. Here, we describe the establishment of a patient-derived orthotopic xenograft (PDOX) model of posterior fossa A (PFA) EPN, derived from a metastatic cranial lesion.

Methods

Patient and PDOX tumors were analyzed using immunohistochemistry, DNA methylation profiling, whole genome sequencing (WGS) and RNA sequencing.

Results

Both patient and PDOX tumors classified as PFA EPN by methylation profiling, and shared similar histological features consistent with this molecular subgroup. RNA sequencing revealed that gene expression patterns were maintained across the primary and metastatic tumors, as well as the PDOX. Copy number profiling revealed gains of chromosomes 7, 8 and 19, and loss of chromosomes 2q and 6q in the PDOX and matched patient tumor. No clinically significant single nucleotide variants were identified, consistent with the low mutation rates observed in PFA EPN. Overexpression of EZHIP RNA and protein, a common feature of PFA EPN, was also observed. Despite the aggressive nature of the tumor in the patient, this PDOX was unable to be maintained past two passages in vivo.

Discussion

Others who have successfully developed PDOX models report some of the lowest success rates for EPN compared to other pediatric brain cancer types attempted, with loss of tumorigenicity not uncommon, highlighting the challenges of propagating these tumors in the laboratory. Here, we discuss our collective experiences with PFA EPN PDOX model generation and propose potential approaches to improve future success in establishing preclinical EPN models.

Epigenetic regulation of plastin 3 expression by the macrosatellite DXZ4 and the transcriptional regulator CHD4

Dysregulated Plastin 3 (PLS3) levels associate with a wide range of skeletal and neuromuscular disorders and the most common types of solid and hematopoietic cancer. Most importantly, PLS3 overexpression protects against spinal muscular atrophy. Despite its crucial role in F-actin dynamics in healthy cells and its involvement in many diseases, the mechanisms that regulate PLS3 expression are unknown. Interestingly, PLS3 is an X-linked gene and all asymptomatic SMN1-deleted individuals in SMA-discordant families who exhibit PLS3 upregulation are female, suggesting that PLS3 may escape X chromosome inactivation. To elucidate mechanisms contributing to PLS3 regulation, we performed a multi-omics analysis in two SMA-discordant families using lymphoblastoid cell lines and iPSC-derived spinal motor neurons originated from fibroblasts. We show that PLS3 tissue-specifically escapes X-inactivation. PLS3 is located ∼500 kb proximal to the DXZ4 macrosatellite, which is essential for X chromosome inactivation. By applying molecular combing in a total of 25 lymphoblastoid cell lines (asymptomatic individuals, individuals with SMA, control subjects) with variable PLS3 expression, we found a significant correlation between the copy number of DXZ4 monomers and PLS3 levels. Additionally, we identified chromodomain helicase DNA binding protein 4 (CHD4) as an epigenetic transcriptional regulator of PLS3 and validated co-regulation of the two genes by siRNA-mediated knock-down and overexpression of CHD4. We show that CHD4 binds the PLS3 promoter by performing chromatin immunoprecipitation and that CHD4/NuRD activates the transcription of PLS3 by dual-luciferase promoter assays. Thus, we provide evidence for a multilevel epigenetic regulation of PLS3 that may help to understand the protective or disease-associated PLS3 dysregulation.

The epigenetic factor CHD4 contributes to metastasis by regulating the EZH2/β-catenin axis and acts as a therapeutic target in ovarian cancer

BACKGROUND

The overall survival rate of patients with advanced ovarian cancer (OC) has remained static for several decades. Advanced ovarian cancer is known for its poor prognosis due to extensive metastasis. Epigenetic alterations contribute to tumour progression and therefore are of interest for potential therapeutic strategies.

METHODS

Following our previous study, we identified that CHD4, a chromatin remodelling factor, plays a strong role in ovarian cancer cell metastasis. We investigated the clinical significance of CHD4 through TCGA and GEO database analyses and explored the effect of CHD4 expression modulation and romidepsin treatment on the biological behaviour of ovarian cancer through CCK-8 and transwell assays. Bioluminescence imaging of tumours in xenografted mice was applied to determine the therapeutic effect of romidepsin. GSEA and western blotting were used to screen the regulatory mechanism of CHD4.

RESULTS

In ovarian cancer patient specimens, high CHD4 expression was associated with a poor prognosis. Loss of function of CHD4 in ovarian cancer cells induced suppression of migration and invasion. Mechanistically, CHD4 knockdown suppressed the expression of EZH2 and the nuclear accumulation of β-catenin. CHD4 also suppressed the metastasis of ovarian cancer cells and prevented disease progression in a mouse model. To inhibit the functions of CHD4 that are mediated by histone deacetylase, we evaluated the effect of the HDAC1/2 selective inhibitor romidepsin. Our findings indicated that treatment with romidepsin suppressed the progression of metastases in vitro and in vivo.

CONCLUSIONS

Collectively, our results uncovered an oncogenic function of CHD4 in ovarian cancer and provide a rationale for clinical trials of romidepsin in ovarian cancer patients.

CHD4 mediates SOX2 transcription through TRPS1 in luminal breast cancer

Chromodomain helicase DNA binding protein 4 (CHD4), as a core component of the nucleosome remodeling and deactetylase (NuRD) complex, participated in the inititation and development of myriad cancers. However, little is known about the linkage between CHD4 and breast cancer stemness. Here, we found that CHD4 repress the expression of SOX2, a key regulator of cancer stem cells (CSCs), to suppress cancer stemness in breast cancer. Mechanistically, CHD4 binds to the promoter of SOX2 depend on TRPS1. And CHD4 transcriptional activation of SOX2 was abolished by TRPS1. These findings identify CHD4 as a regulator of SOX2 linked to breast cancer stemness and provide detailed mechanistic of CHD4 in CSC functions.

A bioinformatics analysis: ZFHX4 is associated with metastasis and poor survival in ovarian cancer

Background

Metastasis was the major cause of the high mortality in ovarian cancer. Although some mechanisms of metastasis in ovarian cancer were proposed, few have been targeted in the clinical practice. In the study, we aimed to identify novel genes contributing to metastasis and poor clinical outcome in ovarian cancer from bioinformatics databases.

Methods

Studies collecting matched primary tumors and metastases from ovarian cancer patients were searched in the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened by software R language. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis for the DEGs were implemented by Metascape. Venn diagram was plotted to present overlapping DEGs. The associations between the overlapping DEGs and prognosis were tested by Cox proportional hazard regression model using a cohort of ovarian cancer patients from the TCGA database. Genes affecting patients’ outcomes significantly were served as hub genes. The mechanisms of the hub genes in promoting ovarian cancer metastasis were then predicted by R software.

Results

Two gene expression profiles (GSE30587 and GSE73168) met the inclusion criteria and were finally analyzed. A total of 259 genes were significantly differentially expressed in GSE30587, whereas 712 genes were in GSE73168. In GSE30587, DEGs were mainly involved in extracellular matrix (ECM) organization; For GSE73168, most of DEGs showed ion trans-membrane transport activity. There were 9 overlapping genes between the two datasets (RUNX2, FABP4, CLDN20, SVEP1, FAM169A, PGM5, ZFHX4, DCN and TAS2R50). ZFHX4 was proved to be an independent adverse prognostic factor for ovarian cancer patients (HR = 1.44, 95%CI: 1.13–1.83, p = 0.003). Mechanistically, ZFHX4 was positively significantly correlated with epithelial-mesenchymal transition (EMT) markers (r = 0.54, p = 2.59 × 10⁻²⁹) and ECM-related genes (r = 0.52, p = 2.86 × 10⁻²⁷).

Conclusions

ZFHX4 might promote metastasis in ovarian cancer by regulating EMT and reprogramming ECM. For clinical applications, ZFHX4 was expected to be a prognostic biomarker for ovarian cancer metastasis.

Comprehensive Analysis of Genomic and Expression Data Identified Potential Markers for Predicting Prognosis and Immune Response in CRC

Colorectal cancer (CRC) is the most prevalent type of malignant tumor of the gastrointestinal tract. In the current study, we characterized the landscape of genomic alterations in CRC patients. Based on the results of whole-exome sequencing (WES), we identified 31 significantly mutated genes. Among them, several genes including TP53, KRAS, APC, PI3KCA, and BRAF were reported as significantly mutated genes in previous studies. In the current study, the most frequently mutated gene was TP53, which encodes tumor suppressor p53, affecting approximately 60% of CRC patients. In addition, we performed the expression profiles of significantly mutated genes between the normal group and tumor groups and identified 20 differentially expressed genes (DEGs); among them, CSMD3, DCHS2, LRP2, RYR2, and ZFHX4 were significantly negatively correlated with PFS. Moreover, consensus clustering analysis for CRC based on the expression of significantly somatic mutated genes was performed. In total, three subtypes of CRC were identified in CRC, including cluster1 (n = 453), cluster2 (n = 158), and cluster 3 (n = 9), based on expression level of significantly somatic mutated genes. Clinicopathological features analysis showed subtype C1 had the longest progression-free survival (PFS) with median time of 8.2 years, while subtypes C2 and C3 had 4.1 and 2.7 years of PFS, respectively. Moreover, we found three subtypes related to tumor infiltration depth, lymph node metastasis, and distant metastasis. Immune infiltration analysis showed the tumor infiltration levels of B cell native, T cell CD8+, T cell CD4+ memory activated, T cell gamma delta, NK cell resting, macrophage M0, macrophage M2, myeloid dendritic cell activated, mast cell activated, and mast cell resting significantly changed among the three groups, demonstrating the three subgroups classified by 22 somatically significantly mutated genes had a high capacity to differentiate patients with different immune statuses, which is helpful for the prediction of immunotherapy response of CRC patients. Our findings could provide novel potential predictive indicators for CRC prognosis and therapy targets for CRC immunotherapy.

CHD4 is recruited by GATA4 and NKX2-5 to repress noncardiac gene programs in the developing heart

The nucleosome remodeling and deacetylase (NuRD) complex is one of the central chromatin remodeling complexes that mediates gene repression. NuRD is essential for numerous developmental events, including heart development. Clinical and genetic studies have provided direct evidence for the role of chromodomain helicase DNA-binding protein 4 (CHD4), the catalytic component of NuRD, in congenital heart disease (CHD), including atrial and ventricular septal defects. Furthermore, it has been demonstrated that CHD4 is essential for mammalian cardiomyocyte formation and function. A key unresolved question is how CHD4/NuRD is localized to specific cardiac target genes, as neither CHD4 nor NuRD can directly bind DNA. Here, we coupled a bioinformatics-based approach with mass spectrometry analyses to demonstrate that CHD4 interacts with the core cardiac transcription factors GATA4, NKX2-5, and TBX5 during embryonic heart development. Using transcriptomics and genome-wide occupancy data, we characterized the genomic landscape of GATA4, NKX2-5, and TBX5 repression and defined the direct cardiac gene targets of the GATA4-CHD4, NKX2-5-CHD4, and TBX5-CHD4 complexes. These data were used to identify putative cis-regulatory elements controlled by these complexes. We genetically interrogated two of these silencers in vivo: Acta1 and Myh11 We show that deletion of these silencers leads to inappropriate skeletal and smooth muscle gene misexpression, respectively, in the embryonic heart. These results delineate how CHD4/NuRD is localized to specific cardiac loci and explicates how mutations in the broadly expressed CHD4 protein lead to cardiac-specific disease states.

Molecular Signature of Tumor-Associated High Endothelial Venules That Can Predict Breast Cancer Survival

High endothelial venules (HEV) are specialized post-capillary venules that recruit naïve lymphocytes to lymph nodes. HEVs are essential for the development of adaptive immunity. HEVs can also develop in tumors where they are thought to be important for recruiting naïve T cells and B cells into the tumors and locally enhancing antitumor immunity by supporting the formation of tertiary lymphoid structures. Herein, we used comparative transcriptome analysis of human breast cancer to investigate genes differentially expressed between tumor-associated HEVs and the rest of the tumor vasculature. Tumor vessels highly expressing HEV-upregulated genes, such as the homeobox gene MEOX2 and the tetraspanin gene TSPAN7, were associated with extensive infiltration of T and B cells and the occurrence of tertiary lymphoid structures, which is known to predict therapeutic responses to immune-checkpoint inhibitors. Moreover, high transcript counts of these genes in clinical tumor specimens were associated with a significant survival benefit in advanced breast cancer. The molecular signature of HEVs identified herein may be useful for guiding immunotherapies and provides a new direction for investigating tumor-associated HEVs and their clinical significance. See related Spotlight by Gallimore, p. 371.

Purine Synthesis Inhibitor L-Alanosine Impairs Mitochondrial Function and Stemness of Brain Tumor Initiating Cells

Glioblastoma (GBM) is a lethal brain cancer exhibiting high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work shows that homozygous MTAP deletion, a genetic alteration occurring in about half of all GBMs, promotes stemness in GBM cells. Exploiting MTAP loss-conferred deficiency in purine salvage, we demonstrate that purine blockade via treatment with L-Alanosine (ALA), an inhibitor of de novo purine synthesis, attenuates stemness of MTAP-deficient GBM cells. This ALA-induced reduction in stemness is mediated in part by compromised mitochondrial function, highlighted by ALA-induced elimination of mitochondrial spare respiratory capacity. Notably, these effects of ALA are apparent even when the treatment was transient and with a low dose. Finally, in agreement with diminished stemness and compromised mitochondrial function, we show that ALA sensitizes GBM cells to temozolomide (TMZ) in vitro and in an orthotopic GBM model. Collectively, these results identify purine supply as an essential component in maintaining mitochondrial function in GBM cells and highlight a critical role of mitochondrial function in sustaining GBM stemness. We propose that purine synthesis inhibition can be beneficial in combination with the standard of care for MTAP-deficient GBMs, and that it may be feasible to achieve this benefit without inflicting major toxicity.

Identification and characterization of novel proteins associated with CHD4

The CHD (chromodomain helicase DNA binding protein) family consists of nine chromatin remodeling factors that alter chromatin structure in an ATP-dependent manner. CHD4 contributes to the regulation of various cellular activities and processes including development through interaction with multiple proteins including formation of the NuRD (nucleosome remodeling and deacetylase activity) complex. Functions of CHD4 that appear not to be mediated by the NuRD complex or other known interactors have also been identified, however, suggesting the existence of unrecognized proteins that also associate with CHD4. We here generated HeLa-S3 and HEK293T cells with a knock-in allele for FLAG epitope-tagged CHD4 and used these cells to identify proteins that bind to CHD4 with the use of immunoprecipitation followed by liquid chromatography and tandem mass spectrometry. LCORL (ligand-dependent nuclear receptor corepressor like) and NOL4L (nucleolar protein 4 like) were reproducibly identified as novel CHD4 interactors. Furthermore, RNA-sequencing analysis of HEK293T cells depleted of CHD4, LCORL, or NOL4L revealed consistent up-regulation of genes related to the Notch signaling pathway. Our results thus suggest that both LCORL and NOL4L may cooperate with CHD4 to suppress the Notch pathway in mammalian cells.

ATRX proximal protein associations boast roles beyond histone deposition

The ATRX ATP-dependent chromatin remodelling/helicase protein associates with the DAXX histone chaperone to deposit histone H3.3 over repetitive DNA regions. Because ATRX-protein interactions impart functions, such as histone deposition, we used proximity-dependent biotinylation (BioID) to identify proximal associations for ATRX. The proteomic screen captured known interactors, such as DAXX, NBS1, and PML, but also identified a range of new associating proteins. To gauge the scope of their roles, we examined three novel ATRX-associating proteins that likely differed in function, and for which little data were available. We found CCDC71 to associate with ATRX, but also HP1 and NAP1, suggesting a role in chromatin maintenance. Contrastingly, FAM207A associated with proteins involved in ribosome biosynthesis and localized to the nucleolus. ATRX proximal associations with the SLF2 DNA damage response factor help inhibit telomere exchanges. We further screened for the proteomic changes at telomeres when ATRX, SLF2, or both proteins were deleted. The loss caused important changes in the abundance of chromatin remodelling, DNA replication, and DNA repair factors at telomeres. Interestingly, several of these have previously been implicated in alternative lengthening of telomeres. Altogether, this study expands the repertoire of ATRX-associating proteins and functions.

ATRX is a protein that is needed to keep repetitive DNA regions organized. It does so in part by binding the DAXX histone chaperone to deposit histone proteins on DNA and assemble structures known as nucleosomes. While important, ATRX has additional functions that remain understudied. To better understand its various biological roles, we first identified the other proteins that are found in its proximity. ATRX-associating proteins were implicated in a range of functions, in addition to histone deposition. Our results suggest that ATRX-associating proteins likely help compact DNA after it is assembled into nucleosomes, and also promote its stability.

We then examined the effect of ATRX on telomeres (repetitive DNA regions at the end of chromosomes). ATRX and at least one of its associating proteins suppressed spurious DNA exchanges at telomeres. To understand why, we then identified proteomic changes that occur at telomeres when ATRX was deleted. Loss of ATRX altered the enrichment of a surprising number of proteins at telomeres, including several DNA damage response and chromatin remodelling proteins.

Zfhx4 regulates endochondral ossification as the transcriptional platform of Osterix in mice

Endochondral ossification is regulated by transcription factors that include SRY-box transcription factor 9, runt-related protein 2 (Runx2), and Osterix. However, the sequential and harmonious regulation of the multiple steps of endochondral ossification is unclear. This study identified zinc finger homeodomain 4 (Zfhx4) as a crucial transcriptional partner of Osterix. We found that Zfhx4 was highly expressed in cartilage and that Zfhx4 deficient mice had reduced expression of matrix metallopeptidase 13 and inhibited calcification of cartilage matrices. These phenotypes were very similar to impaired chondrogenesis in Osterix deficient mice. Coimmunoprecipitation and immunofluorescence indicated a physical interaction between Zfhx4 and Osterix. Notably, Zfhx4 and Osterix double mutant mice showed more severe phenotype than Zfhx4 deficient mice. Additionally, Zfhx4 interacted with Runx2 that functions upstream of Osterix. Our findings suggest that Zfhx4 coordinates the transcriptional network of Osterix and, consequently, endochondral ossification.

Sentinels of chromatin: chromodomain helicase DNA-binding proteins in development and disease

Chromatin is highly dynamic, undergoing continuous global changes in its structure and type of histone and DNA modifications governed by processes such as transcription, repair, replication, and recombination. Members of the chromodomain helicase DNA-binding (CHD) family of enzymes are ATP-dependent chromatin remodelers that are intimately involved in the regulation of chromatin dynamics, altering nucleosomal structure and DNA accessibility. Genetic studies in yeast, fruit flies, zebrafish, and mice underscore essential roles of CHD enzymes in regulating cellular fate and identity, as well as proper embryonic development. With the advent of next-generation sequencing, evidence is emerging that these enzymes are subjected to frequent DNA copy number alterations or mutations and show aberrant expression in malignancies and other human diseases. As such, they might prove to be valuable biomarkers or targets for therapeutic intervention.

jSRC: a flexible and accurate joint learning algorithm for clustering of single-cell RNA-sequencing data

Single-cell RNA-sequencing (scRNA-seq) explores the transcriptome of genes at cell level, which sheds light on revealing the heterogeneity and dynamics of cell populations. Advances in biotechnologies make it possible to generate scRNA-seq profiles for large-scale cells, requiring effective and efficient clustering algorithms to identify cell types and informative genes. Although great efforts have been devoted to clustering of scRNA-seq, the accuracy, scalability and interpretability of available algorithms are not desirable. In this study, we solve these problems by developing a joint learning algorithm [a.k.a. joints sparse representation and clustering (jSRC)], where the dimension reduction (DR) and clustering are integrated. Specifically, DR is employed for the scalability and joint learning improves accuracy. To increase the interpretability of patterns, we assume that cells within the same type have similar expression patterns, where the sparse representation is imposed on features. We transform clustering of scRNA-seq into an optimization problem and then derive the update rules to optimize the objective of jSRC. Fifteen scRNA-seq datasets from various tissues and organisms are adopted to validate the performance of jSRC, where the number of single cells varies from 49 to 110 824. The experimental results demonstrate that jSRC significantly outperforms 12 state-of-the-art methods in terms of various measurements (on average 20.29% by improvement) with fewer running time. Furthermore, jSRC is efficient and robust across different scRNA-seq datasets from various tissues. Finally, jSRC also accurately identifies dynamic cell types associated with progression of COVID-19. The proposed model and methods provide an effective strategy to analyze scRNA-seq data (the software is coded using MATLAB and is free for academic purposes; https://github.com/xkmaxidian/jSRC).

A ZFHX4 mutation associated with a recognizable neuropsychological and facial phenotype

Several patients with chromosomal deletions including ZFHX4 gene have been described, whereas point mutations are very rare. This gene encodes for a transcription factor involved in the development of several embryonal processes, including brain differentiation. Patients with 8q21.11 deletions usually show intellectual disability, short stature, peculiar facial features, and severe eye abnormalities. We describe a female patient with mild intellectual disability, autism spectrum disorder, strabismus, ptosis, low-set and prominent ears, high-arched palate, microretrognathia. Clinical Exome Sequencing revealed the presence of a de novo heterozygous variant in ZFHX4. Therefore, we further investigate the different phenotypes of ZFHX4 mutations and 8q21.11 deletions.

Genetic differences between lung metastases and liver metastases from left-sided microsatellite stable colorectal cancer: next generation sequencing and clinical implications

BACKGROUND

Data regarding the clinical characteristics and outcomes of lung metastases (LuM) from colorectal cancer (CRC) are different from those of liver metastases (LiM) from CRC. However, little is known about the genetic features of LuM. This study aimed to identify the different genetic characteristics of LuM and LiM from left-sided microsatellite stable CRC.

METHODS

Tissue samples of the primary tumors and paired metastases from 18 CRC patients with isolated LuM (LuM cohort), 18 patients with isolated LiM (LiM cohort), and 10 locally advanced CRC patients without metastases (control cohort) were selected for next-generation sequencing. Patients in the LiM cohort had matched clinicopathological characteristics with the LuM cohort. The single-nucleotide variations (SNVs), copy number variations (CNVs), pathway alterations, and tumor mutation burdens (TMBs) were also calculated and analyzed.

RESULTS

The CNV results showed that ZFHX4, GATA2, and FAM131B amplifications were more common in the metastatic cohorts than in the control cohort, while RECQL4 and FLCN amplifications were common in the controls. The LuM cohort had significantly higher proportions of HNF4A, BRD4, and U2AF1 amplification. The LuM, LiM, and control cohorts were successfully separated using pathway alteration analysis. The LuM cohort had more frequent alterations in the RTK/RAS pathway, HIPPO pathway, KRAS, and MET than the LiM group. The LuM cohort also had relatively higher TMBs than the LiM cohort.

CONCLUSIONS

CNVs in primary tumors could identify patients with LuM. Targeting the HIPPO pathway or MET and immune checkpoint inhibitors (ICIs) combined with other agents might be novel therapies for LuM.

Zfh-2 facilitates Notch-induced apoptosis in the CNS and appendages of Drosophila melanogaster

Apoptosis is a fundamental remodeling process for most tissues during development. In this manuscript we examine a pro-apoptotic function for the Drosophila DNA binding protein Zfh-2 during development of the central nervous system (CNS) and appendages. In the CNS we find that a loss-of-function zfh-2 allele gives an overall reduction of apoptotic cells in the CNS, and an altered pattern of expression for the axonal markers 22C10 and FasII. This same loss-of-function zfh-2 allele causes specific cells in the NB7-3 lineage of the CNS that would normally undergo apoptosis to be inappropriately maintained, whereas a gain-of-function zfh-2 allele has the opposite effect, resulting in a loss of normal NB 7-3 progeny. We also demonstrate that Zfh-2 and Hunchback reciprocally repress each other's gene expression which limits apoptosis to later born progeny of the NB7-3 lineage. Apoptosis is also required for proper segmentation of the fly appendages. We find that Zfh-2 co-localizes with apoptotic cells in the folds of the imaginal discs and presumptive cuticular joints. A reduction of Zfh-2 levels with RNAi inhibits expression of the pro-apoptotic gene reaper, and produces abnormal joints in the leg, antenna and haltere. Apoptosis has previously been shown to be activated by Notch signaling in both the NB7-3 CNS lineage and the appendage joints. Our results indicate that Zfh-2 facilitates Notch-induced apoptosis in these structures.

Replication Gaps Underlie BRCA Deficiency and Therapy Response

Defects in DNA repair and the protection of stalled DNA replication forks are thought to underlie the chemosensitivity of tumors deficient in the hereditary breast cancer genes BRCA1 and BRCA2 (BRCA). Challenging this assumption are recent findings that indicate chemotherapies, such as cisplatin used to treat BRCA-deficient tumors, do not initially cause DNA double-strand breaks (DSB). Here, we show that ssDNA replication gaps underlie the hypersensitivity of BRCA-deficient cancer and that defects in homologous recombination (HR) or fork protection (FP) do not. In BRCA-deficient cells, ssDNA gaps developed because replication was not effectively restrained in response to stress. Gap suppression by either restoration of fork restraint or gap filling conferred therapy resistance in tissue culture and BRCA patient tumors. In contrast, restored FP and HR could be uncoupled from therapy resistance when gaps were present. Moreover, DSBs were not detected after therapy when apoptosis was inhibited, supporting a framework in which DSBs are not directly induced by genotoxic agents, but rather are induced from cell death nucleases and are not fundamental to the mechanism of action of genotoxic agents. Together, these data indicate that ssDNA replication gaps underlie the BRCA cancer phenotype, "BRCAness," and we propose they are fundamental to the mechanism of action of genotoxic chemotherapies. SIGNIFICANCE: This study suggests that ssDNA replication gaps are fundamental to the toxicity of genotoxic agents and underlie the BRCA-cancer phenotype "BRCAness," yielding promising biomarkers, targets, and opportunities to resensitize refractory disease.See related commentary by Canman, p. 1214.

Defining phenotypic and functional heterogeneity of glioblastoma stem cells by mass cytometry

Most patients with glioblastoma (GBM) die within 2 years. A major therapeutic goal is to target GBM stem cells (GSCs), a subpopulation of cells that contribute to treatment resistance and recurrence. Since their discovery in 2003, GSCs have been isolated using single-surface markers, such as CD15, CD44, CD133, and α6 integrin. It remains unknown how these single-surface marker-defined GSC populations compare with each other in terms of signaling and function and whether expression of different combinations of these markers is associated with different functional capacity. Using mass cytometry and fresh operating room specimens, we found 15 distinct GSC subpopulations in patients, and they differed in their MEK/ERK, WNT, and AKT pathway activation status. Once in culture, some subpopulations were lost and previously undetectable ones materialized. GSCs that highly expressed all 4 surface markers had the greatest self-renewal capacity, WNT inhibitor sensitivity, and in vivo tumorigenicity. This work highlights the potential signaling and phenotypic diversity of GSCs. Larger patient sample sizes and antibody panels are required to confirm these findings.

Ablation of Zfhx4 results in early postnatal lethality by disrupting the respiratory center in mice

Breathing is an integrated motor behavior that is driven and controlled by a network of brainstem neurons. Zfhx4 is a zinc finger transcription factor and our results showed that it was specifically expressed in several regions of the mouse brainstem. Mice lacking Zfhx4 died shortly after birth from an apparent inability to initiate respiration. We also found that the electrical rhythm of brainstem‒spinal cord preparations was significantly depressed in Zfhx4-null mice compared to wild-type mice. Immunofluorescence staining revealed that Zfhx4 was coexpressed with Phox2b and Math1 in the brainstem and that Zfhx4 ablation greatly decreased the expression of these proteins, especially in the retrotrapezoid nucleus. Combined ChIP‒seq and mRNA expression microarray analysis identified Phox2b as the direct downstream target gene of Zfhx4, and this finding was validated by ChIP‒qPCR. Previous studies have reported that both Phox2b and Math1 play key roles in the development of the respiratory center, and Phox2b and Math1 knockout mice are neonatal lethal due to severe central apnea. On top of this, our study revealed that Zfhx4 is a critical regulator of Phox2b expression and essential for perinatal breathing.

CHD4 Predicts Aggressiveness in PTC Patients and Promotes Cancer Stemness and EMT in PTC Cells

Chromodomain-helicase-DNA-binding protein 4 (CHD4), a core subunit of the nucleosome remodeling and deacetylation (NuRD) complex is highly expressed in several cancers. However, its role in the pathogenesis and progression of papillary thyroid carcinoma (PTC) has not been investigated. We investigated the prognostic significance of CHD4 in a large cohort of Middle Eastern PTC patients and explored the functional role of CHD4 in regulating cancer stemness and EMT in PTC cells. CHD4 overexpression was observed in 45.3% (650/1436) of PTCs, and was associated with aggressive clinico-pathological parameters and worse outcome. Functional analysis using PTC cell lines showed that forced expression of CHD4 promoted cell proliferation, spheroid growth, migration, invasion and progression of epithelial to mesenchymal transition (EMT) in PTC cells whereas its knockdown reversed the effect. Methylation of E-cadherin was associated with loss of expression in CHD4 expressing cells, while CHD4 depletion reactivated E-cadherin expression. Most importantly, knockdown of mesenchymal transcriptional factors, Snail1 or Zeb1, attenuated the spheroid growth in CHD4 expressing PTC cells, showing a potential link between EMT activation and stemness maintenance in PTC. These findings suggest that CHD4 might be a promising therapeutic target in the treatment of patients with an aggressive subtype of PTC.

A Rare CD4-CD8+ Adult T-Cell Leukemia/Lymphoma with Unique Molecular Mutations: A Case Report with Literature Review

Adult T-cell leukemia/lymphoma (ATLL) is a mature T-cell neoplasm caused by infection of the human T-cell lymphotropic virus type 1 (HTLV-1). Most ATLL cases are CD4-positive and CD8-negative. Though rare, there are a few dual negative (CD4-CD8-), dual positive (CD4+CD8+), and CD4-CD8+ cases reported in literature. ATLL is associated with HTLV-1 infection, but HTLV-1 alone cannot cause the malignant transformation of infected T cells. Additional genetic and/or epigenetic events are required for the development of the disease. Here, we report an unusual CD4-CD8+ATLL in a 76-year-old male with a unique molecular genetic profile. Molecular studies revealed alterations in 10 genes. Three of them are predicted to be pathogenic by the computational models, including the frameshift change in ZFHX4 and missense mutations in RHOA and POT1. The specific mutations of POT1 (c.281A > G; p.Q94R), RHOA (c.47G > A; p.C16Y), and ZFHX4 (c.2871delC; p.F958Sfs ∗ 31) have never been previously reported in ATLL to the best of our knowledge. The clinical significance of other genetic alterations is unknown. Further research is warranted to correlate this patient's molecular findings with other ATLL cases. Correlation specifically with other cases of CD8+ ATLL could prove to be useful in understanding the pathogenesis of this rare variant of an already rare form of leukemia/lymphoma.

NuRD subunit CHD4 regulates super-enhancer accessibility in rhabdomyosarcoma and represents a general tumor dependency

The NuRD complex subunit CHD4 is essential for fusion-positive rhabdomyosarcoma (FP-RMS) survival, but the mechanisms underlying this dependency are not understood. Here, a NuRD-specific CRISPR screen demonstrates that FP-RMS is particularly sensitive to CHD4 amongst the NuRD members. Mechanistically, NuRD complex containing CHD4 localizes to super-enhancers where CHD4 generates a chromatin architecture permissive for the binding of the tumor driver and fusion protein PAX3-FOXO1, allowing downstream transcription of its oncogenic program. Moreover, CHD4 depletion removes HDAC2 from the chromatin, leading to an increase and spread of histone acetylation, and prevents the positioning of RNA Polymerase 2 at promoters impeding transcription initiation. Strikingly, analysis of genome-wide cancer dependency databases identifies CHD4 as a general cancer vulnerability. Our findings describe CHD4, a classically defined repressor, as positive regulator of transcription and super-enhancer accessibility as well as establish this remodeler as an unexpected broad tumor susceptibility and promising drug target for cancer therapy.

Identification of candidate mediators of chemoresponse in breast cancer through therapy-driven selection of somatic variants

Purpose

More than a third of primary breast cancer patients are treated with cytotoxic chemotherapy, typically without guidance from predictive markers. Increased use of neoadjuvant chemotherapy provides opportunities for identification of molecules associated with treatment response, by comparing matched tumour samples before and after therapy. Our hypothesis was that somatic variants of increased prevalence after therapy promote resistance, while variants with reduced prevalence cause sensitivity.

Methods

We performed systematic analyses of matched pairs of cancer exomes from primary oestrogen receptor-positive/HER2-negative breast cancers (n = 6) treated with neoadjuvant epirubicin/cyclophosphamide. We identified candidate genes as mediators of chemotherapy response by consistent subclonal changes in somatic variant prevalence through therapy, predicted variant impact on gene function, and enrichment of specific functional pathways. Influence of candidate genes on breast cancer outcome was tested using publicly available breast cancer expression data (n = 1903).

Results

We identified 14 genes as the strongest candidate mediators of chemoresponse: TCHH, MUC17, ARAP2, FLG2, ABL1, CENPF, COL6A3, DMBT1, ITGA7, PLXNA1, S100PBP, SYNE1, ZFHX4, and CACNA1C. Genes contained somatic variants showing prevalence changes in up to 4 patients, with up to 3 being predicted as damaging. Genes coding for extra-cellular matrix components or related signalling pathways were significantly over-represented among variants showing prevalence changes. Expression of 5 genes (TCHH, ABL1, CENPF, S100PBP, and ZFHX4) was significantly associated with patient survival.

Conclusions

Genomic analysis of paired pre- and post-therapy samples resulting from neoadjuvant therapy provides a powerful method for identification of mediators of response. Genes we identified should be assessed as predictive markers or targets in chemo-sensitization.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05836-7) contains supplementary material, which is available to authorized users.

Prognostic Role of Zinc Finger Homeobox 4 in Ovarian Serous Cystadenocarcinoma

Introduction: The zinc finger homeobox 4 (ZFHX4) protein is a crucial molecular regulator of tumor-initiating stem cell-like functions. Objective: This study aimed to determine the role of ZFHX4 in the progression of ovarian serous cystadenocarcinoma (OSC). Methods: Differential gene expression ZFHX4 among low-stage (stages I and II), high-stage (stages III and IV), low-grade (grades I and II), and high-grade (grades III and IV) OSC patients was identified using four independent cohorts from the Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO). We compared ZFHX4 expression as a prognostic factor using Kaplan-Meier survival curves, multivariate analysis, the time-dependent area under the curve (AUC) of Uno's C-index, and the AUC of the receiver operating characteristics at 4 years post diagnosis. Results: ZFHX4 gene expression in high-stage tumors is significantly higher than in low-stage tumors (TCGA, p = 0.007; GSE9891, p = 0.001). A Kaplan-Meier analysis revealed that elevated expression of ZFHX4 was associated with a poor prognosis in OSC patients for all cohorts, regardless of stage and grade (TCGA, p = 1e-04; GSE9891, p = 0.0044; GSE13876, p = 0.00078; GSE26712, p = 0.039). Analysis of C-indices and the area under the receiver operating characteristic curve further supported this result (C-index: TCGA, 0.599; GSE9891, 0.642; GSE13876, 0.585; GSE26712, 0.597). Moreover, univariate and multivariate Cox hazards analyses confirmed the prognostic significance of ZFHX4 levels. Conclusion: Collectively, these findings suggest that ZFHX4 is a prognostic factor for OSC.

Off-target effect of the BMI1 inhibitor PTC596 drives epithelial-mesenchymal transition in glioblastoma multiforme

Glioblastoma multiforme (GBM) is an incurable primary brain tumor containing a sub-population of cancer stem cells (CSCs). Polycomb Repressive Complex (PRC) proteins BMI1 and EZH2 are enriched in CSCs, promoting clonogenic growth and resistance to genotoxic therapies. We report here that when used at appropriate concentrations, pharmaceutical inhibitors of BMI1 could efficiently prevent GBM colony growth and CSC self-renewal in vitro and significantly extend lifespan in terminally ill tumor-bearing mice. Notably, molecular analyses revealed that the commonly used PTC596 molecule targeted both BMI1 and EZH2, possibly providing beneficial therapeutic effects in some contexts. On the other hand, treatment with PTC596 resulted in instant reactivation of EZH2 target genes and induction of a molecular program of epithelial–mesenchymal transition (EMT), possibly explaining the modified phenotype of some PTC596-treated tumors. Treatment with a related but more specific BMI1 inhibitor resulted in tumor regression and maintenance of cell identity. We conclude that inhibition of BMI1 alone is efficient at inducing GBM regression, and that dual inhibition of BMI1 and EZH2 using PTC596 may be also beneficial but only in specific contexts.

The TWIST1-centered competing endogenous RNA network promotes proliferation, invasion, and migration of lung adenocarcinoma

The proposed competing endogenous RNA (ceRNA) mechanism suggested that diverse RNA species, including protein-coding messenger RNAs and non-coding RNAs such as long non-coding RNAs, pseudogenes and circular RNAs could communicate with each other by competing for binding to shared microRNAs. The ceRNA network (ceRNET) is involved in tumor progression and has become a hot research topic in recent years. To date, more attention has been paid to the role of non-coding RNAs in ceRNA crosstalk. However, coding transcripts are more abundant and powerful than non-coding RNAs and make up the majority of miRNA targets. In this study, we constructed a mRNA-mRNA related ceRNET of lung adenocarcinoma (LUAD) and identified the highlighted TWIST1-centered ceRNET, which recruits SLC12A5 and ZFHX4 as its ceRNAs. We found that TWIST1/SLC12A5/ZFHX4 are all upregulated in LUAD and are associated with poorer prognosis. SLC12A5 and ZFHX4 facilitated proliferation, migration, and invasion in vivo and in vitro, and their effects were reversed by miR-194–3p and miR-514a-3p, respectively. We further verified that SLC12A5 and ZFHX4 affected the function of TWIST1 by acting as ceRNAs. In summary, we constructed a mRNA-mRNA related ceRNET for LUAD and highlighted the well-known oncogene TWIST1. Then we verified that SLC12A5 and ZFHX4 exert their oncogenic function by regulating TWIST1 expression through a ceRNA mechanism.

Reconstruction of the Global Neural Crest Gene Regulatory Network In Vivo

Precise control of developmental processes is encoded in the genome in the form of gene regulatory networks (GRNs). Such multi-factorial systems are difficult to decode in vertebrates owing to their complex gene hierarchies and dynamic molecular interactions. Here we present a genome-wide in vivo reconstruction of the GRN underlying development of the multipotent neural crest (NC) embryonic cell population. By coupling NC-specific epigenomic and transcriptional profiling at population and single-cell levels with genome/epigenome engineering in vivo, we identify multiple regulatory layers governing NC ontogeny, including NC-specific enhancers and super-enhancers, novel trans-factors, and cis-signatures allowing reverse engineering of the NC-GRN at unprecedented resolution. Furthermore, identification and dissection of divergent upstream combinatorial regulatory codes has afforded new insights into opposing gene circuits that define canonical and neural NC fates early during NC ontogeny. Our integrated approach, allowing dissection of cell-type-specific regulatory circuits in vivo, has broad implications for GRN discovery and investigation.

CHD4 as a Potential Biomarker in Differentiating Between Cellular Schwannoma and Malignant Peripheral Nerve Sheath Tumor

Cellular schwannoma is an uncommon variant of benign peripheral nerve sheath tumors, but is commonly misdiagnosed as malignant peripheral sheath tumor (MPNST). Conventional methods that are used to distinguish cellular schwannoma from MPNST include immunohistochemistry (IHC) staining. However, most markers cannot precisely differentiate these 2 tumor types, and thus identification of a better marker is needed to improve the accuracy of diagnosis. Here, we evaluate the use of chromodomain helicase DNA-binding protein 4 (CHD4) as a specific marker for cellular schwannoma by comparing CHD4 and S-100 IHC staining in 14 cellular schwannoma and 17 MPNST tissue samples. Our results indicated that nuclear CHD4 stains were in moderate-to-high in 94% MPNST (16 cases) and 93% cellular schwannoma (13 cases). However, cytoplasmic CHD4 stains were moderate-to-high in 93% cellular schwannoma (13 cases) but negative-to-weak in 100% MPNST (17 cases). In contrast, the S-100 stains were moderate-to-high in 86% of the cellular schwannoma (12 cases) and in 35% of the MPNST (6 cases). Taken together, the results indicated that different location of CHD4 staining is a potential biomarker to differentiate cellular schwannoma from MPNST.

Tumour-specific Causal Inference Discovers Distinct Disease Mechanisms Underlying Cancer Subtypes

Cancer is a disease mainly caused by somatic genome alterations (SGAs) that perturb cellular signalling systems. Furthermore, the combination of pathway aberrations in a tumour defines its disease mechanism, and distinct disease mechanisms underlie the inter-tumour heterogeneity in terms of disease progression and responses to therapies. Discovering common disease mechanisms shared by tumours would provide guidance for precision oncology but remains a challenge. Here, we present a novel computational framework for revealing distinct combinations of aberrant signalling pathways in tumours. Specifically, we applied the tumour-specific causal inference algorithm (TCI) to identify causal relationships between SGAs and differentially expressed genes (DEGs) within tumours from the Cancer Genome Atlas (TCGA) study. Based on these causal inferences, we adopted a network-based method to identify modules of DEGs, such that the member DEGs within a module tend to be co-regulated by a common pathway. Using the expression status of genes in a module as a surrogate measure of the activation status of the corresponding pathways, we divided breast cancers (BRCAs) into five subgroups and glioblastoma multiformes (GBMs) into six subgroups with distinct combinations of pathway aberrations. The patient groups exhibited significantly different survival patterns, indicating that our approach can identify clinically relevant disease subtypes.

MAP: model-based analysis of proteomic data to detect proteins with significant abundance changes

Isotope-labeling-based mass spectrometry (MS) is widely used in quantitative proteomic studies. With this technique, the relative abundance of thousands of proteins can be efficiently profiled in parallel, greatly facilitating the detection of proteins differentially expressed across samples. However, this task remains computationally challenging. Here we present a new approach, termed Model-based Analysis of Proteomic data (MAP), for this task. Unlike many existing methods, MAP does not require technical replicates to model technical and systematic errors, and instead utilizes a novel step-by-step regression analysis to directly assess the significance of observed protein abundance changes. We applied MAP to compare the proteomic profiles of undifferentiated and differentiated mouse embryonic stem cells (mESCs), and found it has superior performance compared with existing tools in detecting proteins differentially expressed during mESC differentiation. A web-based application of MAP is provided for online data processing at http://bioinfo.sibs.ac.cn/shaolab/MAP.

Artificial intelligence in drug combination therapy

Currently, the development of medicines for complex diseases requires the development of combination drug therapies. It is necessary because in many cases, one drug cannot target all necessary points of intervention. For example, in cancer therapy, a physician often meets a patient having a genomic profile including more than five molecular aberrations. Drug combination therapy has been an area of interest for a while, for example the classical work of Loewe devoted to the synergism of drugs was published in 1928-and it is still used in calculations for optimal drug combinations. More recently, over the past several years, there has been an explosion in the available information related to the properties of drugs and the biomedical parameters of patients. For the drugs, hundreds of 2D and 3D molecular descriptors for medicines are now available, while for patients, large data sets related to genetic/proteomic and metabolomics profiles of the patients are now available, as well as the more traditional data relating to the histology, history of treatments, pretreatment state of the organism, etc. Moreover, during disease progression, the genetic profile can change. Thus, the ability to optimize drug combinations for each patient is rapidly moving beyond the comprehension and capabilities of an individual physician. This is the reason, that biomedical informatics methods have been developed and one of the more promising directions in this field is the application of artificial intelligence (AI). In this review, we discuss several AI methods that have been successfully implemented in several instances of combination drug therapy from HIV, hypertension, infectious diseases to cancer. The data clearly show that the combination of rule-based expert systems with machine learning algorithms may be promising direction in this field.

Systematic discovery of the functional impact of somatic genome alterations in individual tumors through tumor-specific causal inference

Cancer is mainly caused by somatic genome alterations (SGAs). Precision oncology involves identifying and targeting tumor-specific aberrations resulting from causative SGAs. We developed a novel tumor-specific computational framework that finds the likely causative SGAs in an individual tumor and estimates their impact on oncogenic processes, which suggests the disease mechanisms that are acting in that tumor. This information can be used to guide precision oncology. We report a tumor-specific causal inference (TCI) framework, which estimates causative SGAs by modeling causal relationships between SGAs and molecular phenotypes (e.g., transcriptomic, proteomic, or metabolomic changes) within an individual tumor. We applied the TCI algorithm to tumors from The Cancer Genome Atlas (TCGA) and estimated for each tumor the SGAs that causally regulate the differentially expressed genes (DEGs) in that tumor. Overall, TCI identified 634 SGAs that are predicted to cause cancer-related DEGs in a significant number of tumors, including most of the previously known drivers and many novel candidate cancer drivers. The inferred causal relationships are statistically robust and biologically sensible, and multiple lines of experimental evidence support the predicted functional impact of both the well-known and the novel candidate drivers that are predicted by TCI. TCI provides a unified framework that integrates multiple types of SGAs and molecular phenotypes to estimate which genome perturbations are causally influencing one or more molecular/cellular phenotypes in an individual tumor. By identifying major candidate drivers and revealing their functional impact in an individual tumor, TCI sheds light on the disease mechanisms of that tumor, which can serve to advance our basic knowledge of cancer biology and to support precision oncology that provides tailored treatment of individual tumors.

Dangerous liaisons: interplay between SWI/SNF, NuRD, and Polycomb in chromatin regulation and cancer

In this review, Bracken et al. discuss the functional organization and biochemical activities of remodelers and Polycomb and explore how they work together to control cell differentiation and the maintenance of cell identity. They also discuss how mutations in the genes encoding these various chromatin regulators contribute to oncogenesis by disrupting the chromatin equilibrium.

Changes in chromatin structure mediated by ATP-dependent nucleosome remodelers and histone modifying enzymes are integral to the process of gene regulation. Here, we review the roles of the SWI/SNF (switch/sucrose nonfermenting) and NuRD (nucleosome remodeling and deacetylase) and the Polycomb system in chromatin regulation and cancer. First, we discuss the basic molecular mechanism of nucleosome remodeling, and how this controls gene transcription. Next, we provide an overview of the functional organization and biochemical activities of SWI/SNF, NuRD, and Polycomb complexes. We describe how, in metazoans, the balance of these activities is central to the proper regulation of gene expression and cellular identity during development. Whereas SWI/SNF counteracts Polycomb, NuRD facilitates Polycomb repression on chromatin. Finally, we discuss how disruptions of this regulatory equilibrium contribute to oncogenesis, and how new insights into the biological functions of remodelers and Polycombs are opening avenues for therapeutic interventions on a broad range of cancer types.

CHD4 regulates the DNA damage response and RAD51 expression in glioblastoma

Glioblastoma (GBM) is a lethal brain tumour. Despite therapy with surgery, radiation, and alkylating chemotherapy, most people have recurrence within 6 months and die within 2 years. A major reason for recurrence is resistance to DNA damage. Here, we demonstrate that CHD4, an ATPase and member of the nucleosome remodelling and deactetylase (NuRD) complex, drives a component of this resistance. CHD4 is overexpressed in GBM specimens and cell lines. Based on The Cancer Genome Atlas and Rembrandt datasets, CHD4 expression is associated with poor prognosis in patients. While it has been known in other cancers that CHD4 goes to sites of DNA damage, we found CHD4 also regulates expression of RAD51, an essential component of the homologous recombination machinery, which repairs DNA damage. Correspondingly, CHD4 suppression results in defective DNA damage response in GBM cells. These findings demonstrate a mechanism by which CHD4 promotes GBM cell survival after DNA damaging treatments. Additionally, we found that CHD4 suppression, even in the absence of extrinsic treatment, cumulatively increases DNA damage. Lastly, we found that CHD4 is dispensable for normal human astrocyte survival. Since standard GBM treatments like radiation and temozolomide chemotherapy create DNA damage, these findings suggest an important resistance mechanism that has therapeutic implications.

Elucidating synergistic dependencies in lung adenocarcinoma by proteome-wide signaling-network analysis

To understand drug combination effect, it is necessary to decipher the interactions between drug targets-many of which are signaling molecules. Previously, such signaling pathway models are largely based on the compilation of literature data from heterogeneous cellular contexts. Indeed, de novo reconstruction of signaling interactions from large-scale molecular profiling is still lagging, compared to similar efforts in transcriptional and protein-protein interaction networks. To address this challenge, we introduce a novel algorithm for the systematic inference of protein kinase pathways, and applied it to published mass spectrometry-based phosphotyrosine profile data from 250 lung adenocarcinoma (LUAD) samples. The resulting network includes 43 TKs and 415 inferred, LUAD-specific substrates, which were validated at >60% accuracy by SILAC assays, including "novel' substrates of the EGFR and c-MET TKs, which play a critical oncogenic role in lung cancer. This systematic, data-driven model supported drug response prediction on an individual sample basis, including accurate prediction and validation of synergistic EGFR and c-MET inhibitor activity in cells lacking mutations in either gene, thus contributing to current precision oncology efforts.