CBX2 Induces Glioma Cell Proliferation and Invasion Through the Akt/PI3K Pathway

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.

Cuproptosis-related ceRNA axis triggers cell proliferation and cell cycle through CBX2 in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) has high morbidity and mortality. Despite substantial advances in treatment, the prognosis of patients with LUAD remains unfavorable. The ceRNA axis has been reported to play an important role in the pathogenesis of LUAD. In addition, cuproptosis is considered an important factor in tumorigenesis. The expression of CBX2 has been associated with the development of multiple tumors, including LUAD. However, the precise molecular mechanisms through which the cuproptosis-related ceRNA network regulates CBX2 remain unclear.

METHODS

The DEGs between tumor and normal samples of LUAD were identified in TCGA database. The "ConsensusClusterPlus" R package was used to perform consensus clustering based on the mRNA expression matrix and cuproptosis-related gene expression profile. Then, LASSO-COX regression analysis was performed to identify potential prognostic biomarkers associated with cuproptosis, and the ceRNA network was constructed. Finally, the mechanisms of ceRNA in LUAD was studied by cell experiments.

RESULTS

In this study, the AC144450.1/miR-424-5p axis was found to promote the progression of LUAD by acting on CBX2. The expression of AC144450.1 and miR-424-5p can be altered to regulate CBX2 and is correlated with cell proliferation and cell cycle of LUAD. Mechanistically, AC144450.1 affects the expression of CBX2 by acting as the ceRNA of miR-424-5p. In addition, a cuproptosis-related model were constructed in this study to predict the prognosis of LUAD.

CONCLUSIONS

This study is the first to demonstrate that the AC144450.1/miR-424-5p/CBX2 axis is involved in LUAD progression and may serve as a novel target for its diagnosis and treatment.

Integrated bioinformatics analysis and experimental validation identified CDCA families as prognostic biomarkers and sensitive indicators for rapamycin treatment of glioma

The cell division cycle associated (CDCA) genes regulate the cell cycle; however, their relationship with prognosis in glioma has been poorly reported in the literature. The Cancer Genome Atlas (TCGA) was utilized to probe the CDCA family in relation to the adverse clinical features of glioma. Glioma single-cell atlas reveals specific expression of CDCA3, 4, 5, 8 in malignant cells and CDCA7 in neural progenitor cells (NPC)-like malignant cells. Glioma data from TCGA, the China Glioma Genome Atlas Project (CGGA) and the gene expression omnibus (GEO) database all demonstrated that CDCA2, 3, 4, 5, 7 and 8 are prognostic markers for glioma. Further analysis identified CDCA2, 5 and 8 as independent prognostic factors for glioma. Lasso regression-based risk models for CDCA families demonstrated that high-risk patients were characterized by high tumor mutational burden (TMB), low levels of microsatellite instability (MSI), and low tumor immune dysfunction and rejection (TIDE) scores. These pointed to immunotherapy for glioma as a potentially viable treatment option Further CDCA clustering suggested that the high CDCA subtype exhibited a high macrophage phenotype and was associated with a higher antigen presentation capacity and high levels of immune escape. In addition, hsa-mir-15b-5p was predicted to be common regulator of CDCA3 and CDCA4, which was validated in U87 and U251 cells. Importantly, we found that CDCAs may indicate response to drug treatment, especially rapamycin, in glioma. In summary, our results suggest that CDCAs have potential applications in clinical diagnosis and as drug sensitivity markers in glioma.

Novel chromobox 2 inhibitory peptide decreases tumor progression

BACKGROUND

The Polycomb Repressor Complex 1 (PRC1) is an epigenetic regulator of differentiation and development, consisting of multiple subunits including RING1, BMI1, and Chromobox. The composition of PRC1 dictates its function and aberrant expression of specific subunits contributes to several diseases including cancer. Specifically, the reader protein Chromobox2 (CBX2) recognizes the repressive modifications including histone H3 lysine 27 tri-methylation (H3K27me3) and H3 lysine 9 dimethylation (H3K9me2). CBX2 is overexpressed in several cancers compared to the non-transformed cell counterparts, it promotes both cancer progression and chemotherapy resistance. Thus, inhibiting the reader function of CBX2 is an attractive and unique anti-cancer approach.

RESEARCH DESIGN & METHODS

Compared with other CBX family members, CBX2 has a unique A/T-hook DNA binding domain that is juxtaposed to the chromodomain (CD). Using a computational approach, we constructed a homology model of CBX2 encompassing the CD and A/T hook domain. We used the model as a basis for peptide design and identified blocking peptides that are predicted to directly bind the CD and A/T-hook regions of CBX2. These peptides were tested in vitro and in vivo models.

CONCLUSION

The CBX2 blocking peptide significantly inhibited both 2D and 3D growth of ovarian cancer cells, downregulated a CBX2 target gene, and blunted tumor growth in vivo.

MiR-30a-5p inhibits cell behaviors in esophageal cancer via modulating CBX2

BACKGROUND

This investigation studied the impacts of the miR-30a-5p/CBX2 axis on esophageal cancer (EC).

METHODS

Research objects were ascertained using The Cancer Genome Atlas database. Followed by qRT-PCR, western blot, dual-luciferase reporter, MTT, Transwell, and wound healing approaches, we tested gene expression and varying cell behaviors RESULTS: Conspicuously miR-30 family members (miR-30a-5p, miR-30b-5p, miR-30c-5p, miR-30d-5p, miR-30e-5p) downregulation and CBX2 upregulation were discovered in EC cells. miR-30 family members target CBX2 and inhibited CBX2 expression. EC cell behaviors were inhibited by miR-30a-5p/CBX2 axis.

CONCLUSION

MiR-30a-5p draws a new inspiration for EC treatment.

Loss of CBX2 causes genomic instability and Wnt activation in high grade serous ovarian carcinoma cells

High grade serous ovarian carcinoma (HGSOC) is lethal with insidious onset, rapid progression, poor prognosis, and limited treatment options. Polycomb repressor complexes (PRC) 1 and 2 are intimately involved in progression of many types of cancer including HGSOC. Unlike the consistent constitution of PRC2, PRC1 consists of diverse components whose clinical significance in HGSOC are not entirely clear. Here, prognosis-associated PRC1 components were identified through data-mining. CBX2 promoted proliferation and reduced apoptosis of HGSOC cell lines OVCAR4, OVCAR3, and CAOV3. Complete loss of CBX2 by CRISPR-cas9 editing (CBX2^KO ) destabilized genome stability with increased spontaneous chromosomal breaks and tendency to polyploidy accompanied by disrupted cell cycle especially stalled G2/M transition and caused severe cell death. Wnt/β-catenin/LEF1/TCF7L1 was activated in surviving OVCAR4-CBX2^KO clones to bypass the crisis caused by loss of CBX2. The relieve of TCF7L1 core-promoter region occupied by CBX2 might be one of the possible explanations to TCF7L1 increase in OVCAR4-CBX2^KO clones. Subcutaneous tumor model further validated that depletion of CBX2 repressed HGSOC cell line derived tumor growth. High immunohistochemistry score of CBX2 in primary ovarian cancer tissue associated with advanced clinical stage (p = 0.033), poor overall survival (HR = 3.056, 95% CI: 1.024-9.123), and progression free survival (HR = 4.455, 95% CI: 1.513-13.118) in HGSOC. Overall, our results suggested that CBX2 was a promising prognostic factor and therapeutic target in HGSOC.

CBX2-mediated suppression of SIAH2 triggers WNK1 accumulations to promote glycolysis in hepatocellular carcinoma

Previous studies have highlighted the poor prognosis of liver cancer, and treatment effects are overall limited. We aimed to confirm the biological roles of SIAH2 in liver cancer and provide potential therapeutic targets. Differential analysis was conducted based on public datasets and found that SIAH2 expressed lowly in HCC samples relative to normal tissues, which was demonstrated in tumor samples via immunohistochemistry (IHC). Besides, SIAH2 overexpression could significantly suppress HCC proliferation. SIAH2 deficiency induced cell proliferation, migration and self-renewal abilities in vitro and in vivo. Mechanistically, SIAH2 could interact with WNK1, and trigger the ubiquitination and degradation of WNK1 proteins. In addition, low SIAH2 depended on elevated WNK1 proteins to drive HCC malignant features, including proliferation, migration and stemness. Meanwhile, we further found that CBX2 could regulate SIAH2 expressions. CBX2 cooperated with EZH2 to mediate the H3K27me3 enrichment on the promoter region of SIAH2 to suppress its transcriptional levels. High CBX2/EZH2 levels in HCC correlated with poor prognosis of patients. Gene set enrichment analysis (GSEA) further implicated that WNK1 correlates tightly with glycolytic process in HCC samples. WNK1 overexpression was found to notably enhance glycolytic activity, whereas WNK1 deficiency could significantly suppress the HCC glycolysis activity. Lastly, the subcutaneous tumor model further demonstrated that targeting WNK1 was effective to inhibit the in vivo tumor growth of SIAH2^low HCC. Collectively, down-regulated SIAH2 expressions induced by CBX2/EZH2 could drive progression and glycolysis via accumulating WNK1 proteins, indicating that CBX2/SIAH2/WNK1 axis is a potential prognostic biomarker and therapeutic vulnerability for human HCC.

Chromobox proteins in cancer: Multifaceted functions and strategies for modulation (Review)

Chromobox (CBX) proteins are important epigenetic regulatory proteins and are widely involved in biological processes, such as embryonic development, the maintenance of stem cell characteristics and the regulation of cell proliferation and apoptosis. Disorder and dysfunction of CBXs in cancer usually lead to the blockade or ectoptic activation of developmental pathways, promoting the occurrence, development and progression of cancer. In the present review, the characteristics and functions of CBXs were first introduced. Subsequently, the expression of CBXs in cancers and the relationship between CBXs and clinical characteristics (mainly cancer grade, stage, metastasis and relapse) and prognosis were discussed. Finally, it was described how CBXs regulate cell proliferation and self‑renewal, apoptosis and the acquisition of malignant phenotypes, such as invasion, migration and chemoresistance, through mechanisms involving epigenetic modification, nuclear translocation, noncoding RNA interactions, transcriptional regulation, posttranslational modifications, protein‑protein interactions, signal transduction and metabolic reprogramming. The study also focused on cancer therapies targeting CBXs. The present review provides new insight and a comprehensive basis for follow‑up research on CBXs and cancer.

MicroRNA-124-3p promotes apoptosis and autophagy of glioma cells by down-regulating CREBRF

OBJECTIVE

This research was performed to dissect the influence of microRNA (miR)-124-3p on the apoptosis and autophagy of glioma cells and clarify its specific mechanism.

METHODS

RT-PCR and western blot were utilized to determine miR-124-3p and CREBRF expression in U251 and T98 cells. After loss- and gain-of-function assays in U251 and T98 cells, glioma cell proliferation, autophagy, and apoptosis were measured by MTT assay, western blot, and flow cytometry, respectively. The relationship between miR-124-3p and CREBRF was examined by dual-luciferase reporter assay. The levels of AKT pathway-related proteins were detected by western blot.

RESULTS

MiR-124-3p was lowly expressed and CREBRF was highly expressed in U251 and T98 cells. Overexpression of miR-124-3p or knockdown of CREBRF enhanced apoptosis and autophagy and diminished proliferation of glioma cells. MiR-124-3p negatively targeted CREBRF. MiR-124-3p up-regulation repressed proliferation and facilitated apoptosis and autophagy of glioma cells by diminishing CREBRF expression and blocking the AKT pathway.

CONCLUSION

MiR-124-3p accelerates apoptosis and autophagy of glioma cells via CREBRF.

An intersectional analysis of LncRNAs and mRNAs reveals the potential therapeutic targets of Bi Zhong Xiao Decoction in collagen-induced arthritis rats

Background

Bi Zhong Xiao decoction (BZXD), a traditional Chinese herbal formula, has been used clinically for many years to treat rheumatoid arthritis (RA). Both clinical and experimental studies have revealed that BZXD is effective in treating RA, but the mechanism remains unclear. In this study, we aimed to explore the mechanism of efficacy of BZXD through transcriptomic analysis of lncRNA and mRNA.

Methods

The combination method of ultra-high performance liquid chromatography-mass spectrometry/mass spectrometry was used to assess the quality of BZXD. The efficacy of BZXD in treating collagen-induced arthritis (CIA) was evaluated by clinical assessment, weight changes, hematoxylin–eosin and safranin o-fast green staining, and Micro-CT. Arraystar rat lncRNA-mRNA chip technology was used to determine the lncRNA and mRNA expression profiles of the Control, CIA and BZXD groups, and to screen gene expression profiles related to the curative effect of BZXD. A lncRNA-mRNA co-expression network was constructed for the therapeutic efficacy genes. Through GO function and KEGG pathway enrichment analysis, the biological functions and signaling pathways of therapeutic efficacy genes were determined. Based on fold change and functional annotation, key differentially expressed lncRNAs and mRNAs were selected for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) validation. The functions of lncRNAs targeting mRNAs were verified in vitro.

Results

We demonstrated that BZXD could effectively reverse bone erosion. After BZXD treatment, up to 33 lncRNAs and 107 mRNAs differentially expressed genes were reversely regulated by BZXD. These differentially expressed lncRNAs are mainly involved in the biological process of the immune response and are closely related to the ECM-receptor interaction, MAPK signaling pathway, Focal adhesion, Ras signaling pathway, Antigen processing and presentation, and Chemokine signaling pathway. We identified four lncRNAs (uc.361−, ENSRNOT00000092834, ENSRNOT00000089244, ENSRNOT00000084631) and three mRNAs (Acvr2a, Cbx2, Morc4) as potential therapeutic targets for BZXD and their microarray data consistent with the RT-qPCR. In vitro experiments confirmed that silencing the lncRNAs ENSRNOT00000092834 and ENSRNOT00000084631 reversed the expression of target mRNAs.

Conclusions

This study elucidates the possible mechanism of BZXD reversing bone erosion in CIA rats from the perspective of lncRNA and mRNA. To provide a basis and direction for further exploration of the mechanism of BZXD in treating RA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00670-z.

The Epigenetic Regulatory Protein CBX2 Promotes mTORC1 Signalling and Inhibits DREAM Complex Activity to Drive Breast Cancer Cell Growth

Chromobox 2 (CBX2) is a chromatin-binding component of polycomb repressive complex 1, which causes gene silencing. CBX2 expression is elevated in triple-negative breast cancer (TNBC), for which there are few therapeutic options. Here, we aimed to investigate the functional role of CBX2 in TNBC. CBX2 knockdown in TNBC models reduced cell numbers, which was rescued by ectopic expression of wild-type CBX2 but not a chromatin binding-deficient mutant. Blocking CBX2 chromatin interactions using the inhibitor SW2_152F also reduced cell growth, suggesting CBX2 chromatin binding is crucial for TNBC progression. RNA sequencing and gene set enrichment analysis of CBX2-depleted cells identified downregulation of oncogenic signalling pathways, including mTORC1 and E2F signalling. Subsequent analysis identified that CBX2 represses the expression of mTORC1 inhibitors and the tumour suppressor RBL2. RBL2 repression, in turn, inhibits DREAM complex activity. The DREAM complex inhibits E2F signalling, causing cell senescence; therefore, inhibition of the DREAM complex via CBX2 may be a key oncogenic driver. We observed similar effects in oestrogen receptor-positive breast cancer, and analysis of patient datasets suggested CBX2 inhibits RBL2 activity in other cancer types. Therapeutic inhibition of CBX2 could therefore repress mTORC1 activation and promote DREAM complex-mediated senescence in TNBC and could have similar effects in other cancer types.

Comprehensive Molecular Analyses of a Macrophage-Related Gene Signature With Regard to Prognosis, Immune Features, and Biomarkers for Immunotherapy in Hepatocellular Carcinoma Based on WGCNA and the LASSO Algorithm

Macrophages have been reported to exert a crucial role in hepatocellular carcinoma (HCC). This study aimed to explore the macrophage-related genes and establish a macrophage-related signature (MRS) model to predict the overall survival (OS) of patients with HCC based on these genes’ expression. We screened the macrophage-related gene module by weighted gene coexpression network analysis (WGCNA), the least absolute shrinkage and selection operator (LASSO) Cox regression analysis was utilized for further selection, and the selected genes were entered into stepwise regression to develop the MRS model, which was further validated in the Gene Expression Omnibus (GEO) and International Cancer Genome Consortium (ICGC) datasets. We analyzed the biological phenotypes associated with macrophages in terms of functional enrichment, tumor immune signature, and tumor mutational signature. The patient’s response to immunotherapy was inferred by the tumor immune dysfunction and exclusion (TIDE) score, the immunophenotype score (IPS), and the IMvigor210 dataset. A novel MRS model was established based on the LASSO regression coefficients of the genes PON1, IL15RA, NEIL3, HILPDA, PFN2, HAVCR1, ANXA10, CDCA8, EPO, S100A9, TTK, KLRB1, SPP1, STC2, CYP26B1, GPC1, G6PD, and CBX2. In either dataset, MRS was identified as an independent risk factor for OS in HCC patients. Additionally, our research indicated that a high-risk score in the MRS model was significantly correlated with tumor staging, pathological grade, tumor–node–metastasis (TNM) stage, and survival. Several genes of the human leukocyte antigen (HLA) family and immune checkpoints were highly expressed in the high-risk group. In addition, the frequency of tumor mutations was also higher in the high-risk group. According to our analyses, a higher risk score in the MRS model may predict a better response to immunotherapy.