Study on the Role of EPHB6 in Inhibiting the Malignant Progression of Cervical Cancer C33A Cells by Binding to CBX7.

Cervical cancer stands as the most frequently diagnosed malignancy affecting the female reproductive. The erythropoietin-producing hepatocyte (Eph) family tyrosine kinases play important roles in tumorigenesis and cancer aggression. However, the exact role of EPHB6 in cervical cancer remains unknown. The present study investigated the role of EPHB6 in the malignant process of cervical cancer. GEPIA, tnmplot and kmplot database was used to study the expression of EPHB6 in cervical cancer tissues. western blotting was used to detect the expression of EPHB6, CyclinD, CDK4, CDK6, CBX7, MMP2 and MMP9. CCK8 and EDU staining were used to detect cell proliferation. Wound healing and transwell were used to detect cell proliferation and migration. Flow cytometry was used to detect cell cycle level. The linkedomics database was used to predict the correlation of EPHB6 and CBX7 in cervical cancer. Subsequently, HDOCK server was used to predict the combination of EPHB6 and CBX7. Our current results suggested that the expression of EPHB6 is reduced in cervical cancer tissues and cell lines, and the lower the expression, the worse the prognosis. Moreover, overexpression of EPHB6 inhibits cell proliferation, invasion and migration and cycle acceleration of C33A cells. Furthermore, EPHB6 and CBX7 bind to each other in C33A cells, and EPHB6 inhibits cell proliferation, invasion, migration and cell cycle acceleration in cervical cancer by binding to CBX7. EPHB6 expression is reduced in cervical cancer tissues and cells. Its overexpression inhibits proliferation, invasion, migration, and cell cycle acceleration in C33A cells, exhibiting synergy when bound to CBX7.

Exploring the Role of CBX3 as a Potential Therapeutic Target in Lung Cancer.

Epigenetic changes regulate gene expression through histone modifications, chromatin remodeling, and protein translation of these modifications. The PRC1 and PRC2 complexes shape gene repression via histone modifications. Specifically, the CBX protein family aids PRC1 recruitment to chromatin, impacting the progressive multistep process driving chromatin silencing. Among family members, CBX3 is a complex protein involved in aberrant epigenetic mechanisms that drive lung cancer progression. CBX3 promotes lung tumorigenesis by interacting with key pathways such as PI3K/AKT, Ras/KRAS, Wnt/ß-catenin, MAPK, Notch, and p53, leading to increased proliferation, inhibition of apoptosis, and enhanced resistance to therapy. Given our current lack of knowledge, additional research is required to uncover the intricate mechanisms underlying CBX3 activity, as well as its involvement in molecular pathways and its potential biomarker evaluation. Specifically, the dissimilar roles of CBX3 could be reexamined to gain a greater insight into lung cancer pathogenesis. This review aims to provide a clear overview of the context-related molecular profile of CBX3, which could be useful for addressing clinical challenges and developing novel targeted therapies based on personalized medicine.

CBX4 counteracts cellular senescence to desensitize gastric cancer cells to chemotherapy by inducing YAP1 SUMOylation.

AIMS: As our comprehension of the intricate relationship between cellular senescence and tumor biology continues to evolve, the therapeutic potential of cellular senescence is gaining increasing recognition. Here, we identify chromobox 4 (CBX4), a Small Ubiquitin-related Modifier (SUMO) E3 ligase, as an antagonist of cellular senescence and elucidate a novel mechanism by which CBX4 promotes drug resistance and malignant progression of gastric cancer (GC). METHODS: In vitro and in vivo models were conducted to investigate the manifestation and impact of CBX4 on cellular senescence and chemoresistance. High-throughput sequencing, chromatin immunoprecipitation, and co-immunoprecipitation techniques were utilized to identify the upstream regulators and downstream effectors associated with CBX4, revealing its intricate regulatory network. RESULTS: CBX4 diminishes the sensitivity of GC cells to cellular senescence, facilitating chemoresistance and GC development by deactivating the senescence-related Hippo pathway. Mechanistically, low-dose cisplatin transcriptionally downregulates CBX4 through CEBPB. In addition, CBX4 preserves the stability and cytoplasm-nuclear transport of YAP1, the key player of Hippo pathway, by inducing SUMO1 modification at K97 and K280, which competitively inhibits YAP1-S127 phosphorylation. CONCLUSIONS: Our study highlights the anti-senescence role of CBX4 and suggests that CBX4 inhibition in combination with low-dose cisplatin has the potential to overcome chemoresistance and effectively restrict GC progression.

CBX2 enhances the progression and TMZ chemoresistance of glioma via EZH2-mediated epigenetic silencing of PTEN expression.

Chromobox (CBX) 2, a member of the CBX protein family and a crucial component of the polycomb repressive complex (PRC), exerts significant influence on the epigenetic regulation of tumorigenesis, including glioma. However, the precise role of CBX2 in glioma has remained elusive. In our study, we observed a substantial upregulation of CBX2 expression in glioma, which displayed a strong correlation with pathological grade, chemoresistance, and unfavorable prognosis. Through a series of in vivo and in vitro experiments, we established that heightened CBX2 expression facilitated glioma cell proliferation and bolstered resistance to chemotherapy. Conversely, CBX2 knockdown led to a significant inhibition of glioma cell growth and a reduction in chemoresistance. Notably, our investigation uncovered the underlying mechanism by which CBX2 operates, primarily by inhibiting PTEN transcription and activating the AKT/mTOR signalling pathway. Conversely, silencing CBX2 curtailed cell proliferation and attenuated chemoresistance by impeding the activation of the PTEN/AKT/mTOR signalling pathway. Delving deeper into the molecular intricacies, we discovered that CBX2 can recruit EZH2 and modulate the trimethylation of histone H3 lysine 27 (H3K27me3) levels on the PTEN promoter, effectively suppressing PTEN transcription. Our research unveils a comprehensive understanding of how CBX2 impacts the tumorigenesis, progression, chemoresistance, and prognosis of glioma. Furthermore, it presents CBX2 as a promising therapeutic target for drug development and clinical management of glioma.

The Role of the MiR-181 Family in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the fourth-leading cause of cancer-related death worldwide. Due to the high mortality rate in HCC patients, discovering and developing novel systemic treatment options for HCC is a vital unmet medical need. Among the numerous molecular alterations in HCCs, microRNAs (miRNAs) have been increasingly recognised to play critical roles in hepatocarcinogenesis. We and others have recently revealed that members of the microRNA-181 (miR-181) family were up-regulated in some, though not all, human cirrhotic and HCC tissues-this up-regulation induced epithelial-mesenchymal transition (EMT) in hepatocytes and tumour cells, promoting HCC progression. MiR-181s play crucial roles in governing the fate and function of various cells, such as endothelial cells, immune cells, and tumour cells. Previous reviews have extensively covered these aspects in detail. This review aims to give some insights into miR-181s, their targets and roles in modulating signal transduction pathways, factors regulating miR-181 expression and function, and their roles in HCC.

CBX4/miR-190 regulatory loop inhibits lung cancer metastasis.

BACKGROUND: Lung cancer is one of the major threats to human life worldwide. MiR-190 has been found to perform essential roles in multiple cancer progression; however, there have been no studies focused on its function and underlying regulatory mechanism in lung cancer. METHOD: The miR-190 expression was detected by real-time quantitative polymerase chain reaction (RT-qPCR). The cell functional experiments, including cell counting kit-8 (CCK-8), colony formation and transwell assay were conducted in vitro, as well as animal experiments performed in vivo. The regulation and potential binding sites of CBX4 on miR-190 were predicted by TCGA data set and JASPAR website and verified by ChIP assay and dual-luciferase reporter assay. The prospects binding site of miR-190-3p on CBX4 3'UTR region was predicted by StarBase and verified by dual-luciferase reporter assay. RESULTS: MiR-190 was decreased in lung cancer cells. The overexpression of miR-190 had no effects on cell proliferation, but significantly inhibited cancer metastasis both in vitro and in vivo. Moreover, miR-190 expression could be transcriptionally inhibited by CBX4, and CBX4 was the direct target of miR-190-3p. CONCLUSION: MiR-190 served as a cancer metastasis inhibitor in lung cancer and formed a regulatory loop with CBX4. These findings provided emerging insights into therapeutic targets and strategies for metastatic lung cancer.

Bioinformatics analysis reveals that CBX2 promotes enzalutamide resistance in prostate cancer.

Enzalutamide (Enz) is commonly utilized as the initial treatment strategy for advanced prostate cancer (PCa). However, a notable subset of patients may experience resistance to Enz, resulting in reduced effectiveness. Utilizing Gene Expression Omnibus (GEO) databases, we identified CBX2 as a crucial factor in mediating resistance to Enz, primarily due to its inhibitory effect on the P53 signaling pathway. Silencing of CBX2 using small interfering RNA (siRNA) led to elevated levels of P53 expression in LNCaP cells. This indicates that CBX2 may have a critical effect on PCa Enz resistance and could serve as a promising therapeutic target for individuals with Enz resistance.

CBX7 promotes choroidal neovascularization by activating the HIF-1α/VEGF pathway in choroidal vascular endothelial cells.

Vascular endothelial growth factor (VEGF) signaling is crucial for choroidal neovascularization (CNV), a major pathological feature of neovascular age-related macular degeneration (nAMD). Gene transcription of VEGF is mainly regulated by hypoxia-inducible factor 1-alpha (HIF-1α). The chromobox (CBX) family polycomb protein (Pc) subgroup includes CBX2, CBX4, CBX6, CBX7, and CBX8. CBX4 enhances hypoxia-induced VEGF expression and angiogenesis in hepatocellular carcinoma (HCC) cells by increasing HIF-1α's transcriptional activity. The objective of the study was to examine the functions of members of the CBX family Pc subgroup in choroidal vascular endothelial cells (CVECs) during CNV. CBX4 and CBX7 expression was up-regulated in hypoxic human choroidal vascular endothelial cells (HCVECs). In HCVECs, CBX7 facilitated HIF-1α transcription and expression, while CBX4 did not. In HCVECs, CBX7 stimulated HIF-1α's nuclear translocation and transcriptional activity, which in turn stimulated VEGF transcription and expression. The CBX7/HIF-1α/VEGF pathway promoted the migration, proliferation, and tube formation of HCVECs. The CBX7/HIF-1α/VEGF pathway was up-regulated in CVECs and in the mouse model with laser-induced CNV. Mouse CNV was lessened by the blockade of CBX7 through the down-regulation of HIF-1α/VEGF. In conclusion, CBX7 enhanced pro-angiogenic behaviors of hypoxic CVECs by up-regulating the HIF-1α/VEGF pathway, which contributing to the formation of mouse laser-induced CNV.

Integrated Lactylome Characterization Reveals the Molecular Dynamics of Protein Regulation in Gastrointestinal Cancers.

Lysine lactylation (Kla) plays a vital role in several physiological processes. However, the cancer-specific modulation of Kla in gastrointestinal (GI) tumors requires systematic elucidation. Here, global lactylome profiling of cancerous and adjacent tissues is conducted from 40 patients with GI cancer and identified 11698 Kla sites. Lactylome integration revealed that Kla affects proteins involved in hallmark cancer processes, including epigenetic rewiring, metabolic perturbations, and genome instability. Moreover, the study revealed pan-cancer patterns of Kla alterations, among which 37 Kla sites are consistently upregulated in all four GI cancers and are involved in gene regulation. It is further verified that lactylation of CBX3 at K10 mediates its interaction of CBX3 with the epigenetic marker H3K9me3 and facilitates GI cancer progression. Overall, this study provides an invaluable resource for understanding the lactylome landscape in GI cancers, which may provide new paths for drug discovery for these devastating diseases.

A novel nanoplatform-based circCSNK1G3 affects CBX7 protein and promotes glioma cell growth.

Bioenvironmental and biological factors have the potential to contribute to the development of glioma, a type of brain tumor. Recent studies have suggested that a unique circular RNA called circCSNK1G3 could play a role in promoting the growth of glioma cells. It does this by stabilizing a specific microRNA called miR-181 and reducing the expression of a tumor-suppressor gene known as chromobox protein homolog 7 (CBX7). To further investigate circCSNK1G3 and its effects on glioma, we utilized a nanoplatform called adeno-associated virus (AAV)-RNAi.To explore the functional implications of circCSNK1G3, we employed siRNA to silence its expression. Along with these effects, the silencing of circCSNK1G3 led to a depletion of miR-181d and an upregulation of CBX7. When we introduced miR-181d mimics, which artificially increase the levels of miR-181d, the anti-glioma cell activity induced by circCSNK1G3 siRNA was almost completely reversed. Conversely, inhibiting miR-181d mimicked the effects of circCSNK1G3 silencing. Moreover, when we overexpressed circCSNK1G3 in glioma cells, we observed an elevation of miR-181d and a depletion of CBX7. We found that the growth of A172 xenografts (tumors) carrying circCSNK1G3 shRNA was significantly inhibited. In these xenograft tissues, we detected a depletion of circCSNK1G3 and miR-181d, as well as an upregulation of CBX7.

CBX4 suppresses CD8+ T cell antitumor immunity by reprogramming glycolytic metabolism.

Rationale: CD8+ T cells undergo a series of metabolic reprogramming processes during their activation and proliferation, including increased glycolysis, decreased aerobic oxidation of sugars, increased amino acid metabolism and increased protein synthesis. However, it is still unclear what factors regulate these metabolic reprogramming processes in CD8+ T cells in the tumor immune microenvironment. Methods: T cell chromobox protein 4 (CBX4) knock-out mice models were used to determine the role of CBX4 in CD8+ T cells on the tumor immune microenvironment and tumor progression. Flow cytometry, Cut-Tag qPCR, Chip-seq, immunoprecipitation, metabolite detection, lentivirus infection and adoptive T cells transfer were performed to explore the underlying mechanisms of CBX4 knock-out in promoting CD8+ T cell activation and inhibiting tumor growth. Results: We found that CBX4 expression was induced in tumor-infiltrating CD8+ T cells and inhibited CD8+ T cell function by regulating glucose metabolism in tumor tissue. Mechanistically, CBX4 increases the expression of the metabolism-associated molecule aldolase B (Aldob) through sumoylation of trans-acting transcription factor 1 (SP1) and Krüppel-like factor 3 (KLF3). In addition, Aldob inhibits glycolysis and ATP synthesis in T cells by reducing the phosphorylation of the serine/threonine protein kinase (Akt) and ultimately suppresses CD8+ T cell function. Significantly, knocking out CBX4 may improve the efficacy of anti-PD-1 therapy by enhancing the function of CD8+ T cells in the tumor microenvironment. Conclusion: CBX4 is involved in CD8+ T cell metabolic reprogramming and functional persistence in tumor tissues, and serves as an inhibitor in CD8+ T cells' glycolysis and effector function.

Uncovering the mechanism of Clostridium butyricum CBX 2021 to improve pig health based on in vivo and in vitro studies.

Introduction: As a symbiotic probiotic for the host, Clostridium butyricum (CB) has the potential to strengthen the body's immune system and improve intestinal health. However, the probiotic mechanism of CB is not completely understood. The Clostridium butyricum CBX 2021 strain isolated by our team from a health pig independently exhibits strong butyric acid production ability and stress resistance. Therefore, this study comprehensively investigated the efficacy of CBX 2021 in pigs and its mechanism of improving pig health. Methods: In this study, we systematically revealed the probiotic effect and potential mechanism of the strain by using various methods such as microbiome, metabolites and transcriptome through animal experiments in vivo and cell experiments in vitro. Results: Our in vivo study showed that CBX 2021 improved growth indicators such as daily weight gain in weaned piglets and also reduced diarrhea rates. Meanwhile, CBX 2021 significantly increased immunoglobulin levels in piglets, reduced contents of inflammatory factors and improved the intestinal barrier. Subsequently, 16S rRNA sequencing showed that CBX 2021 treatment implanted more butyric acid-producing bacteria (such as Faecalibacterium) in piglets and reduced the number of potentially pathogenic bacteria (like Rikenellaceae RC9_gut_group). With significant changes in the microbial community, CBX 2021 improved tryptophan metabolism and several alkaloids synthesis in piglets. Further in vitro experiments showed that CBX 2021 adhesion directly promoted the proliferation of a porcine intestinal epithelial cell line (IPEC-J2). Moreover, transcriptome analysis revealed that bacterial adhesion increased the expression of intracellular G protein-coupled receptors, inhibited the Notch signaling pathway, and led to a decrease in intracellular pro-inflammatory molecules. Discussion: These results suggest that CBX 2021 may accelerate piglet growth by optimizing the intestinal microbiota, improving metabolic function and enhancing intestinal health.

Fluorescent Reporter Systems to Investigate Chromatin Effector Proteins in Living Cells.

Epigenetic research faces the challenge of the high complexity and tight regulation in chromatin modification networks. Although many isolated mechanisms of chromatin-mediated gene regulation have been described, solid approaches for the comprehensive analysis of specific processes as parts of the bigger epigenome network are missing. In order to expand the toolbox of methods by a system that will help to capture and describe the complexity of transcriptional regulation, we describe here a robust protocol for the generation of stable reporter systems for transcriptional activity and summarize their applications. The system allows for the induced recruitment of a chromatin regulator to a fluorescent reporter gene, followed by the detection of transcriptional changes using flow cytometry. The reporter gene is integrated into an endogenous chromatin environment, thus enabling the detection of regulatory dependencies of the investigated chromatin regulator on endogenous cofactors. The system allows for an easy and dynamic readout at the single-cell level and the ability to compensate for cell-to-cell variances of transcription. The modular design of the system enables the simple adjustment of the method for the investigation of different chromatin regulators in a broad panel of cell lines. We also summarize applications of this technology to characterize the silencing velocity of different chromatin effectors, removal of activating histone modifications, analysis of stability and reversibility of epigenome modifications, the investigation of the effects of small molecule on chromatin effectors and of functional effector-coregulator relationships. The presented method allows to investigate the complexity of transcriptional regulation by epigenetic effector proteins in living cells.

Ziyuglycoside II, a triterpene glycoside compound in Sanguisorbae officinalis l. extract, suppresses metastasis in osteosarcoma via CBX4-mediated Wnt/ß-catenin signal pathway.

BACKGROUND: Osteosarcoma (OS), the most prevalent primary bone malignancy, exhibits rapid growth and a high tendency for lung metastasis, posing significant treatment challenges. Ziyuglycoside II (ZGS II), a main active compound derived from Sanguisorba officinalis l., has shown potential in cancer treatment. However, the effects of ZGS II and its potential mechanism in OS remain elusive. PURPOSE: This study aims to explore the anti-metastatic potential of ZGS II in OS, offering a novel therapeutic strategy for improved patient outcomes. METHODS: Cell viability and proliferation was detected by cell counting kit-8 (CCK-8) and clone formation assay, respectively. Transwell and wound-healing assay were applied to evaluate the potential metastatic abilities of OS cells in vitro. More critically, the chromobox protein homolog 4 (CBX4) and Wnt/ß-catenin signaling pathway was investigated utilizing Western blotting, immunohistochemistry, shRNA knockdown and immunofluorescence. An orthotopic metastasis mouse model was utilized to evaluate the efficacy of ZGS II in suppressing OS metastasis in vivo, with molecular docking studies conducted to elucidate the interaction between ZGS II and the CBX4 protein. RESULTS: Our study demonstrated the potent inhibitory effects of ZGS II on OS cell proliferation and induced apoptosis in vitro, as evidenced by decreased cell viability, enhanced caspase-3 activation, and mitochondrial dysfunction. Furthermore, using an orthotopic metastasis mouse model, we illustrated that ZGS II effectively suppressed tumor growth and lung metastasis in vivo. Notably, our investigation revealed that the antitumor action of ZGS II is dependent on the reduction of CBX4 levels, leading to the attenuation of the Wnt/ß-catenin signaling pathway activation. Molecular docking analyses supported this pathway's suppression, showing that ZGS II has the capability to directly bind and disrupt CBX4 function. To further confirm this mechanism, we utilized shRNA to silence CBX4 in OS cells, which significantly enhanced the inhibitory impact of ZGS II on cell migration. CONCLUSION: Our study findings reveal that ZGS II efficiently suppresses both metastasis and tumor growth in OS by a novel mechanism that entails the inhibition of the CBX4-regulated Wnt/ß-catenin pathway. These outcomes highlight the promising potential of ZGS II as a therapeutic agent for managing metastatic OS, thus justifying the need for additional clinical investigations.

FABP4, GINS2 and CBX7 Expression in Cancer Cervix Tissues: Clinical, Pathological and Prognostic Implications.

Background & Objective: Cervical cancer spreads to the pelvic lymph nodes, leading to a high incidence of cancer recurrence and unfavorable survival rates. Therefore, there is an urgent need to detect new predictive biomarkers for the early assessment of pelvic lymph node status in patients with cervical cancer. The current study aimed to assess the expression of FABP4, GINS2, and CBX7 in cervical cancer tissue to detect their prognostic and predictive roles in developing lymph node metastases in patients with that cancer type. Methods: We collected the tissues from patients with cervical cancer and evaluated the expression of FABP4, GINS2, and CBX7 using immunohistochemistry. We evaluated the association between their expression and clinicopathological and prognostic parameters. Results: A high expression of FABP4 and GINS2 and a low expression of CBX7 were found to be positively associated with the old age group, large tumor size, high grade and lymphovascular involvement, para-uterine organ infiltration, advanced FIGO stage, chemotherapeutic resistance, and tumor recurrence. Conclusion: We demonstrated the oncogenic roles of FABP4 and GISN2 in addition to the on-co-suppressive roles of CBX7 in cervical cancer and their association with poor clinicopathological criteria and poor survival. Our results may indicate that FABP4, GISN2, and CBX7 could be considered predictive biomarkers of the occurrence of lymph node metastases in the cancer of the cervix preoperatively, which could be beneficial in the accurate preoperative design therapy.

Small-Molecule Inhibition of CBX4/7 Hypersensitises Homologous Recombination-Impaired Cancer to Radiation by Compromising CtIP-Mediated DNA End Resection.

The therapeutic targeting of DNA repair pathways is an emerging concept in cancer treatment. Compounds that target specific DNA repair processes, such as those mending DNA double-strand breaks (DSBs), are therefore of therapeutic interest. UNC3866 is a small molecule that targets CBX4, a chromobox protein, and a SUMO E3 ligase. As a key modulator of DNA end resection-a prerequisite for DSB repair by homologous recombination (HR)-CBX4 promotes the functions of the DNA resection factor CtIP. Here, we show that treatment with UNC3866 markedly sensitises HR-deficient, NHEJ-hyperactive cancer cells to ionising radiation (IR), while it is non-toxic in selected HR-proficient cells. Consistent with UNC3866 targeting CtIP functions, it inhibits end-resection-dependent DNA repair including HR, alternative end joining (alt-EJ), and single-strand annealing (SSA). These findings raise the possibility that the UNC3866-mediated inhibition of end resection processes we define highlights a distinct vulnerability for the selective killing of HR-ineffective cancers.

In Silico Analysis of Functional SNPs in Genes of Complete Androgen Insensitivity Syndrome (CAIS): A Retrospective, Case-Control Study.

Background: Complete androgen insensitivity syndrome (CAIS) is one of the categories of androgen insensitivity syndrome (AIS) described as complete failure of the cell to react to androgens with external genitalia of a normal female. People with AIS condition are genetically male, with XY karyotype in each cell, but their bodies are unable to respond to male sex hormones (called androgens). It is associated with infertility as well as developing cancerous conditions. The genetic association of CAIS involves polymorphism of genes such as NR5A1, SOX9, SRD5A2, CBX2, GATA4, and SRY. Their mutation and participation in genetics of CAIS can be studied by Single Nucleotide polymorphism (SNP) analysis which is a way to detect genetic variations. SNP in coding region leads to synonymous and non-synonymous mutations. Hence, this study highlights analysis of SNPs associated with CAIS. Our aim is to study SNP analysis of NR5A1, SOX9, SRD5A2, CBX2, GATA4, SRY genes in Complete Androgen Insensitivity Syndrome. Methods: SIFT and Polyphen analysis was performed for all the genes and samples were subjected for PCR-SSCP technique. Results: SNPs were analyzed for the genes associated with CAIS. Benign and damaging SNPs were identified. DNA Samples were amplified using PCR technique and they will be analyzed using Single-strand conformation polymorphism (SSCP). Conclusions: As SNPs have decreased stability, damaging and benign character, they can be used as candidate hallmarks in study of Complete Androgen Insensitivity Syndrome.

CBX7 silencing promoted liver regeneration by interacting with BMI1 and activating the Nrf2/ARE signaling pathway.

Multiple studies have shown knockdown of chromobox 7 (CBX7) promotes the regenerative capacity of various cells or tissues. We examined the effect of CBX7 on hepatocyte proliferation and liver regeneration after 2/3 hepatectomy in a mouse model. For in vitro experiments, NCTC 1469 and BNL CL.2 hepatocytes were co-transfected with siRNA-CBX7-1 (si-CBX7-1), siRNA-CBX7-2 (si-CBX7-2), pcDNA-CBX7, si-BMI1-1, si-BMI1-2, pcDNA-BMI1, or their negative control. For in vivo experiments, mice were injected intraperitoneally with lentivirus-packaged shRNA and shRNA CBX7 before hepatectomy. Our results showed that CBX7 was rapidly induced in the early stage of liver regeneration. CBX7 regulated hepatocyte proliferation, cell cycle, and apoptosis of NCTC 1469 and BNL CL.2 hepatocytes. CBX7 interacted with BMI1 and inhibited BMI1 expression in hepatocytes. Silencing BMI1 aggregated the inhibitory effect of CBX7 overexpression on hepatocyte viability and the promotion of apoptosis. Furthermore, silencing BMI1 enhanced the regulatory effect of CBX7 on Nrf2/ARE signaling in HGF-induced hepatocytes. In vivo, CBX7 silencing enhanced liver/body weight ratio in PH mice. CBX7 silencing promoted the Ki67-positive cell count and decreased the Tunel-positive cell count after hepatectomy, and also increased the expression of nuclear Nrf2, HO-1, and NQO-1. Our results suggest that CBX7 silencing may increase survival following hepatectomy by promoting liver regeneration.

CBX3 antagonizes IFNγ/STAT1/PD-L1 axis to modulate colon inflammation and CRC chemosensitivity.

As an important immune stimulator and modulator, IFNγ is crucial for gut homeostasis and its dysregulation links to diverse colon pathologies, such as colitis and colorectal cancer (CRC). Here, we demonstrated that the epigenetic regulator, CBX3 (also known as HP1γ) antagonizes IFNγ signaling in the colon epithelium by transcriptionally repressing two critical IFNγ-responsive genes: STAT1 and CD274 (encoding Programmed death-ligand 1, PD-L1). Accordingly, CBX3 deletion resulted in chronic mouse colon inflammation, accompanied by upregulated STAT1 and CD274 expressions. Chromatin immunoprecipitation indicated that CBX3 tethers to STAT1 and CD274 promoters to inhibit their expression. Reversely, IFNγ significantly reduces CBX3 binding to these promoters and primes gene expression. This antagonist effect between CBX3 and IFNγ on STAT1/PD-L1 expression was also observed in CRC. Strikingly, CBX3 deletion heightened CRC cells sensitivity to IFNγ, which ultimately enhanced their chemosensitivity under IFNγ stimulation in vitro with CRC cells and in vivo with a syngeneic mouse tumor model. Overall, this work reveals that by negatively tuning IFNγ-stimulated immune genes' transcription, CBX3 participates in modulating colon inflammatory response and CRC chemo-resistance.