CBX7 gene expression plays a negative role in adipocyte cell growth and differentiation

LncRNA RNA ROR Aggravates Hypoxia/Reoxygenation-Induced Cardiomyocyte Ferroptosis by Targeting miR-769-5p/CBX7 Axis

Ferroptosis is a new way of cell death which is reported to participate in the pathology of myocardial ischemia-reperfusion (MI/R) injury, but it's mechanism remains unclear. The present investigation is to study the emerging role of long non-coding RNA (lncRNA) regulator of reprogramming (ROR) in cardiomyocyte ferroptosis after hypoxia/reoxygenation (H/R) administration. RT-qPCR and/or Western blot methods were performed to examine the gene/or protein levels, and CCK-8, ELISA, and DCFH-DA staining determined the cellular viability and ferroptosis. Dual-luciferase and RNA immunoprecipitation were applied to verify molecular interaction. LncRNA ROR and miR-769-5p were overexpressed and reduced in blood samples from MI patients and H/R-treated AC16 cells, respectively. Mechanistically, lncROR sponged to miR-769-5p, thus upregulating CBX7 expression. Functional experiments presented that lncRNA ROR silence mitigated H/R-stimulated inflammatory damage, oxidative stress, and ferroptosis in AC16 cells, whereas these roles could be reversed by co-downregulation of miR-769-5p or co-overexpression of CBX7. These data uncovered that lncRNA ROR prevented against H/R-induced cardiomyocyte ferroptosis by modulating miR-769-5p/CBX7 signaling, emphasizing the therapeutic value of lncRNA ROR in MI/R injury.

Decoding the interaction between miR-19a and CBX7 focusing on the implications for tumor suppression in cancer therapy

Cancer is a complex and multifaceted disease characterized by uncontrolled cell growth, genetic alterations, and disruption of normal cellular processes, leading to the formation of malignant tumors with potentially devastating consequences for patients. Molecular research is important in the diagnosis and treatment, one of the molecular mechanisms involved in various cancers is the fluctuation of gene expression. Non-coding RNAs, especially microRNAs, are involved in different stages of cancer. MicroRNAs are small RNA molecules that are naturally produced within cells and bind to the 3'-UTR of target mRNA, repressing gene expression by regulating translation. Overexpression of miR-19a has been reported in human malignancies. Upregulation of miR-19a as a member of the miR-17-92 cluster is key to tumor formation, cell proliferation, survival, invasion, metastasis, and drug resistance. Furthermore. bioinformatics and in vitro data reveal that the miR-19a-3p isoform binds to the 3'UTR of CBX7 and was identified as the miR-19a-3p target gene. CBX7 is known as a tumor suppressor. This review initially describes the regulation of mir-19a in multiple cancers. Accordingly, the roles of miR-19 in affecting its target gene expression CBX7 in carcinoma also be discussed.

Chromobox Family Proteins as Putative Biomarkers for Breast Cancer Management: A Preliminary Study Based on Bioinformatics Analysis and qRT-PCR Validation

Background

Epigenetic modification of chromatin is an important step in the regulation of gene expression. The chromobox family proteins (CBXs), as epigenetic modifier, may play a vital role in tumorigenesis and cancer progression. Herein we explored the correlation between CBXs and breast cancer (BC) via the bioinformatics approach and qRT-PCR validation.

Methods

Several databases, including GEPIA, TCGA, GEO, K-M plotter, STRING, DAVID, cBioPortal, CIBERSORT, and HPA were employed to analyze the expression levels of CBXs and the correlations between CBXs and prognosis (overall and recurrence-free survival) in BC. We analyzed molecular functions, genetic variations, transcription factors of CBXs, and immune cell infiltration status. ROC curve analysis was performed to determine the predictive value of CBXs. RNA extracted from 11 human BC and paired adjacent normal tissues were subjected to qRT-PCR.

Results

The mRNA expression level of CBX1-5 was significantly upregulated, while that of CBX7 was significantly downregulated in BC; no expression disparities were observed in CBX6/8 expression. Further, high mRNA expression of CBX1/2/3/4/8 correlated with advanced BC, whereas high mRNA expression of CBX6/7 correlated with early BC. High mRNA expressions of CBX1/2/3/5 predict poor OS and RFS, while higher mRNA expressions of CBX6/7 predict better OS and RFS in patients with BC. ROC curve analysis revealed that CBX3 showed excellent discriminatory ability. Gene ontology enrichment analysis showed that CBXs primarily participated in SUMOylation and post-/transcriptional regulation. Moreover, they presented varying degrees of amplification in BC tissues and were related to the infiltration of various immune cells.

Conclusion

CBXs can serve as putative biomarkers for BC. Further studies are warranted to determine the exact molecular mechanisms underlying the action of CBXs in BC, particularly CBX1/2/3/5/7.

CBX7 is Dualistic in Cancer Progression Based on its Function and Molecular Interactions

Chromobox protein homolog 7 (CBX7) is a member of the Chromobox protein family and participates in the formation of the polycomb repressive complex 1(PRC1). In cells, CBX7 often acts as an epigenetic regulator to regulate gene expression. However, pathologically, abnormal expression of CBX7 can lead to an imbalance of gene expression, which is closely related to the occurrence and progression of cancers. In cancers, CBX7 plays a dual role; On the one hand, it contributes to cancer progression in some cancers by inhibiting oncosuppressor genes. On the other hand, it suppresses cancer progression by interacting with different molecules to regulate the synthesis of cell cycle-related proteins. In addition, CBX7 protein may interact with different RNAs (microRNAs, long noncoding RNAs, circular RNAs) in different cancer environments to participate in a variety of pathways, affecting the development of cancers. Furthermore, CBX7 is involved in cancer-related immune response and DNA repair. In conclusion, CBX7 expression is a key factor in the occurrence and progression of cancers.

Comprehensive analysis of Transcription Factors identified novel prognostic biomarker in human bladder cancer

Background: Transcriptional factors (TFs) are responsible for regulating the transcription of pro-oncogenes and tumor suppressor genes in the process of tumor development. However, the role of these transcription factors in Bladder cancer (BCa) remains unclear. And the main purpose of this research is to explore the possibility of these TFs serving as biomarkers for BCa. Methods: We analyzed the differential expression of TFs in BCa from The Cancer Genome Atlas (TCGA) online database, identified 408 up-regulated TFs and 751down-regulated TFs. We obtained some hub genes via WGCNA model and detected the RNAs level in BCa cells and tissues. Then, the relationship between the expression and clinicopathological parameters was further investigated. Kaplan-Meier curves and the log-rank test were carried out to analyze the relationship between NFATC1, AKNA and five-TFs combination and overall survival (OS). And RT-PCR assay was conducted to further consolidate and verify these results. Results: There were significant differences in the expression of five TFs (CBX7, AKNA, HDAC4, EBF2 and NFATC1) between bladder cancer and normal bladder tissue. In BCa tissue and cell lines, the five TFs were frequently down-regulated, and closely related to poor prognosis. Moreover, the RT-PCR results of five TFs in bladder cancer and normal bladder tissue were consistent with the database results, and reduced TFs could significantly induce or restrain the transcription of many critical factors. The expression level of AKNA and NFATC1 could serve as independent biomarker to predict the overall survival (P<0.05). And the above five TFs combined detection of bladder cancer has higher sensitivity and specificity. Furthermore, differential neutrophils expression between high-risk and low-risk were found, which consolidated the role and function of the five TFs combination model in the progression of BCa. Conclusions: Our analysis effectively provides a newly TFs-associated prognostic model for bladder cancer. The combination of five identified-TFs is an independent prognostic biomarker, which could serve as a more effective therapeutic target for BCa patients.

Biological functions of chromobox (CBX) proteins in stem cell self-renewal, lineage-commitment, cancer and development

Epigenetic regulatory proteins support mammalian development, cancer, aging and tissue repair by controlling many cellular processes including stem cell self-renewal, lineage-commitment and senescence in both skeletal and non-skeletal tissues. We review here our knowledge of epigenetic regulatory protein complexes that support the formation of inaccessible heterochromatin and suppress expression of cell and tissue-type specific biomarkers during development. Maintenance and formation of heterochromatin critically depends on epigenetic regulators that recognize histone 3 lysine trimethylation at residues K9 and K27 (respectively, H3K9me3 and H3K27me3), which represent transcriptionally suppressive epigenetic marks. Three chromobox proteins (i.e., CBX1, CBX3 or CBX5) associated with the heterochromatin protein 1 (HP1) complex are methyl readers that interpret H3K9me3 marks which are mediated by H3K9 methyltransferases (i.e., SUV39H1 or SUV39H2). Other chromobox proteins (i.e., CBX2, CBX4, CBX6, CBX7 and CBX8) recognize H3K27me3, which is deposited by Polycomb Repressive Complex 2 (PRC2; a complex containing SUZ12, EED, RBAP46/48 and the methyl transferases EZH1 or EZH2). This second set of CBX proteins resides in PRC1, which has many subunits including other polycomb group factors (PCGF1, PCGF2, PCGF3, PCGF4, PCGF5, PCGF6), human polyhomeotic homologs (HPH1, HPH2, HPH3) and E3-ubiquitin ligases (RING1 or RING2). The latter enzymes catalyze the subsequent mono-ubiquitination of lysine 119 in H2A (H2AK119ub). We discuss biological, cellular and molecular functions of CBX proteins and their physiological and pathological activities in non-skeletal cells and tissues in anticipation of new discoveries on novel roles for CBX proteins in bone formation and skeletal development.

The gut microbiota regulates white adipose tissue inflammation and obesity via a family of microRNAs

The gut microbiota is a key environmental determinant of mammalian metabolism. Regulation of white adipose tissue (WAT) by the gut microbiota is a process critical to maintaining metabolic fitness, and gut dysbiosis can contribute to the development of obesity and insulin resistance (IR). However, how the gut microbiota regulates WAT function remains largely unknown. Here, we show that tryptophan-derived metabolites produced by the gut microbiota controlled the expression of the miR-181 family in white adipocytes in mice to regulate energy expenditure and insulin sensitivity. Moreover, dysregulation of the gut microbiota-miR-181 axis was required for the development of obesity, IR, and WAT inflammation in mice. Our results indicate that regulation of miR-181 in WAT by gut microbiota-derived metabolites is a central mechanism by which host metabolism is tuned in response to dietary and environmental changes. As we also found that MIR-181 expression in WAT and the plasma abundance of tryptophan-derived metabolites were dysregulated in a cohort of obese human children, the MIR-181 family may represent a potential therapeutic target to modulate WAT function in the context of obesity.

CBX7 binds the E-box to inhibit TWIST-1 function and inhibit tumorigenicity and metastatic potential

Deaths from ovarian cancer usually occur when patients succumb to overwhelmingly numerous and widespread micrometastasis. Whereas epithelial-mesenchymal transition is required for epithelial ovarian cancer cells to acquire metastatic potential, the cellular phenotype at secondary sites and the mechanisms required for the establishment of metastatic tumors are not fully determined. Using in vitro and in vivo models we show that secondary epithelial ovarian cancer cells (sEOC) do not fully reacquire the molecular signature of the primary epithelial ovarian cancer cells from which they are derived. Despite displaying an epithelial morphology, sEOC maintains a high expression of the mesenchymal effector, TWIST-1. TWIST-1 is however transcriptionally nonfunctional in these cells as it is precluded from binding its E-box by the PcG protein, CBX7. Deletion of CBX7 in sEOC was sufficient to reactivate TWIST-1-induced transcription, prompt mesenchymal transformation, and enhanced tumorigenicity in vivo. This regulation allows secondary tumors to achieve an epithelial morphology while conferring the advantage of prompt reversal to a mesenchymal phenotype upon perturbation of CBX7. We also describe a subclassification of ovarian tumors based on CBX7 and TWIST-1 expression, which predicts clinical outcomes and patient prognosis.

Vertebrate diapause preserves organisms long term through Polycomb complex members

Diapause is a state of suspended development that helps organisms survive extreme environments. How diapause protects living organisms is largely unknown. Using the African turquoise killifish (Nothobranchius furzeri), we show that diapause preserves complex organisms for extremely long periods of time without trade-offs for subsequent adult growth, fertility, and life span. Transcriptome analyses indicate that diapause is an active state, with dynamic regulation of metabolism and organ development genes. The most up-regulated genes in diapause include Polycomb complex members. The chromatin mark regulated by Polycomb, H3K27me3, is maintained at key developmental genes in diapause, and the Polycomb member CBX7 mediates repression of metabolism and muscle genes in diapause. CBX7 is functionally required for muscle preservation and diapause maintenance. Thus, vertebrate diapause is a state of suspended life that is actively maintained by specific chromatin regulators, and this has implications for long-term organism preservation.

Potential role of chromatin remodeling factor genes in atrophic gastritis/gastric cancer risk

BACKGROUND/AIMS

Atrophic gastritis (AG), intestinal metaplasia (IM), and Helicobacter pylori (HP) are the risk factors for the development of gastric cancer (GC). Chromatin remodeling is one of the epigenetic mechanisms involved in the carcinogenesis of GC. The purpose of this study was to investigate the expression profiles of defined chromatin remodeling genes in gastric mucosal samples and their values as gastric carcinogenesis biomarkers.

MATERIALS AND METHODS

In total, 95 patients were included in the study. Patients were divided into 3 groups as: GC group (n=34), AG group (n=36), and control group (n=25). AG group was further divided into subgroups based on the presence of HP and IM in gastric mucosa. Chromatin remodeling gene expressions were analyzed using real-time PCR (RT-PCR) array in all groups. Data were evaluated using the RT-qPCR primer assay data analysis software.

RESULTS

EED, CBX3, and MTA1 were more overexpressed, whereas ARID1A, ING5, and CBX7 were more underexpressed in the AG and GC groups compared with the controls. No significant differences were observed between the AG and GC groups concerning the expression of these 6 genes, although the fold change levels of these genes in the GC group were well above than in the AG group. EED, CBX3, and MTA1 were significantly more overexpressed in HP- and IM-positive AG subgroup compared with the HP- or IM-negative AG subgroup.

CONCLUSION

In conclusion, our results provide an evidence of epigenetic alterations in AG. Expressions of EED, CBX3, MTA1, ARID1A, ING5, and CBX7 may be considered as promising markers to be used in GC screening for patients with AG.

Epigenetic balance of gene expression by Polycomb and COMPASS families

Epigenetic regulation of gene expression in metazoans is central for establishing cellular diversity, and its deregulation can result in pathological conditions. Although transcription factors are essential for implementing gene expression programs, they do not function in isolation and require the recruitment of various chromatin-modifying and -remodeling machineries. A classic example of developmental chromatin regulation is the balanced activities of the Polycomb group (PcG) proteins within the PRC1 and PRC2 complexes, and the Trithorax group (TrxG) proteins within the COMPASS family, which are highly mutated in a large number of human diseases. In this review, we will discuss the latest findings regarding the properties of the PcG and COMPASS families and the insight they provide into the epigenetic control of transcription under physiological and pathological settings.

An integrative pan-cancer-wide analysis of epigenetic enzymes reveals universal patterns of epigenomic deregulation in cancer

Background

One of the most important recent findings in cancer genomics is the identification of novel driver mutations which often target genes that regulate genome-wide chromatin and DNA methylation marks. Little is known, however, as to whether these genes exhibit patterns of epigenomic deregulation that transcend cancer types.

Results

Here we conduct an integrative pan-cancer-wide analysis of matched RNA-Seq and DNA methylation data across ten different cancer types. We identify seven tumor suppressor and eleven oncogenic epigenetic enzymes which display patterns of deregulation and association with genome-wide cancer DNA methylation patterns, which are largely independent of cancer type. In doing so, we provide evidence that genome-wide cancer hyper- and hypo- DNA methylation patterns are independent processes, controlled by distinct sets of epigenetic enzyme genes. Using causal network modeling, we predict a number of candidate drivers of cancer DNA hypermethylation and hypomethylation. Finally, we show that the genomic loci whose DNA methylation levels associate most strongly with expression of these putative drivers are highly consistent across cancer types.

Conclusions

This study demonstrates that there exist universal patterns of epigenomic deregulation that transcend cancer types, and that intra-tumor levels of genome-wide DNA hypomethylation and hypermethylation are controlled by distinct processes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0699-9) contains supplementary material, which is available to authorized users.

Polycomb protein family member CBX7 plays a critical role in cancer progression

CBX7 is a polycomb protein that participates in the formation of polycomb repressive complex 1. Apart from few exceptions, CBX7 expression is lost in human malignant neoplasias and a clear correlation between its downregulated expression and a cancer aggressiveness and poor prognosis has been observed. These findings indicate a critical role of CBX7 in cancer progression. Consistently, CBX7 is able to differentially regulate crucial genes involved in cancer progression and in epithelial-mesenchymal transition, as osteopontin and E-cadherin. Recent evidences indicate a role of CBX7 also in the modulation of response to therapy. In conclusion, CBX7 represents an important prognostic factor, whose loss of expression in general indicates a bad prognosis and a progression towards a fully malignant phenotype.

Up-regulation of miR-9 target CBX7 to regulate invasion ability of bladder transitional cell carcinoma

BACKGROUND

Bladder urothelial carcinoma is the most common genitourinary system cancer in China. The objective of this study was to investigate whether the miR-9 can regulate the invasion ability of human bladder transitional cell carcinoma cells by down-regulation of CBX7.

MATERIAL/METHODS

The expression of miR-9 was detected by quantitative real-time PCR in bladder transitional cell carcinomas (TCC) and normal bladder transitional cell (NBTC) samples. Bioinformatics software was used to predict some potential target genes of miR-9. T24 cells were transfected with pre-miR-9, and the CBX7 protein expression was detected by Western blot. Luciferase activities assay was selected to verify that CBX7 was a direct and specific gene of miR-9. T24 cells were transfected with pcDNA-CBX7, and the expression of CBX7 gene was detected. Then, the transwell assay was used to detect the invasion ability of T24 cells with CBX7 over-expression.

RESULTS

The expression of miR-9 increased significantly in human TCC specimens compared to that in NBTC specimens. TargetScan and PicTar software programs predicted CBX7 gene was a target gene of miR-9. The pre-miR-9 could up-regulate the miR-9 expression and down-regulate CBX7 protein expression. The luciferase activities assay verified that CBX7 gene was a direct and specific target gene of miR-9. The pcDNA-CBX7 transfection could up-regulate the CBX7 protein expression, and the invasion ability of T24 cells with CBX7 over-expression decreased significantly.

CONCLUSIONS

Aberrantly expressed miR-9 contributes to T24 cells invasion, partly through directly down-regulating CBX7 protein expression in TCC. This miRNA signature offers a new potential therapeutic target for TCC.