CBX4 deletion promotes tumorigenesis under KrasG12D background by inducing genomic instability

CBX4 regulation of senescence and associated diseases: molecular pathways and mechanisms

Polycomb repressive complex 1 (PRC1) is a multisubunit, evolutionarily conserved epigenetic regulator critical to numerous biological processes. Being a core component of the canonical PRC1 subunit within the Polycomb group protein complex, Chromobox4 (CBX4), a SUMO E3 ligase, can bind to H3K27me3 and recruit PRC1. This ligase regulates the SUMOylation of various proteins and permits their post-translational modification under different physiological conditions. CBX4 has been reported to regulate the development of senescence and various diseases in vivo. This review delves into the physiological functions and action mechanisms of CBX4 across different tissues and cells, particularly focusing on its primarily roles in migration, cellular senescence, metabolic dysregulation, inflammation development, and tumor proliferation. Targeting CBX4 offers a therapeutic potential for delaying cell senescence and suppressing tumor growth.

Genome-wide methylation analysis unveils genes and pathways with altered methylation profiles in pterygium

Pterygium is a highly prevalent ocular surface disease, particularly in equatorial regions, with no pharmaceutical intervention available and surgical excision remaining the only treatment option. Ultraviolet (UV) radiation from sunlight is widely recognized as the primary cause of pterygium. While chronic UV exposure induces epigenetic changes in the skin contributing to skin cancer, comprehensive studies on epigenetic alterations in pterygium remain unpublished, and causal relationships have yet to be established. This study aimed to investigate genome-wide methylation changes in pterygium using the Illumina Infinium Epic v2.0 Methylation array. We identified 1052 hypermethylated CpGs (499 genes) and 687 hypomethylated CpGs (340 genes) in pterygium tissue compared to control conjunctival tissue from patients undergoing cataract surgery (Δβ>|0.1|, P < 0.05). Hypomethylated genes were mainly associated with PI3K-Akt and MAPK pathways, while hypermethylated genes were enriched in pathways related to oxidative stress, autophagy, DNA repair, and Wnt signaling inhibition. Comparing these findings with transcriptomic datasets revealed 28 hypermethylated genes with downregulated transcripts and 74 hypomethylated genes with upregulated transcripts. qPCR validation confirmed upregulation of hypomethylated genes (MMP2, FBLN5, ZEB1) and downregulation of hypermethylated genes (SAMSN1, CBX4) at the transcript level. These findings suggest that dysregulated DNA methylation may contribute to pterygium pathogenesis by upregulating genes involved in cell proliferation, survival, angiogenesis, fibrosis, and extracellular matrix remodeling, while silencing genes associated with oxidative stress response, autophagy, and DNA damage repair. These insights into the global methylation landscape of pterygium open avenues for detailed functional analysis, potentially guiding targeted therapeutic strategies.

Epigenetic regulatory protein chromobox family regulates multiple signalling pathways and mechanisms in cancer

Signal transduction plays a pivotal role in modulating a myriad of critical processes, including the tumour microenvironment (TME), cell cycle arrest, proliferation and apoptosis of tumour cells, as well as their migration, invasion, and the epithelial-mesenchymal transition (EMT). Epigenetic mechanisms are instrumental in the genesis and progression of tumours. The Chromobox (CBX) family proteins, which serve as significant epigenetic regulators, exhibit tumour-specific expression patterns and biological functionalities. These proteins are influenced by a multitude of factors and could modulate the activation of diverse signalling pathways within tumour cells through alterations in epigenetic modifications, thereby acting as either oncogenic agents or tumour suppressors. This review aims to succinctly delineate the composition, structure, function, and expression of CBXs within tumour cells, with an emphasis on synthesizing and deliberating the CBXs-mediated activation of intracellular signalling pathways and the intricate mechanisms governing tumourigenesis and progression. Moreover, a plethora of contemporary studies have substantiated that CBXs might represent a promising target for the diagnosis and therapeutic intervention of tumour patients. We have also compiled and scrutinized the current research landscape concerning inhibitors targeting CBXs, aspiring to aid researchers in gaining a deeper comprehension of the biological roles and mechanisms of CBXs in the malignant evolution of tumours, and to furnish novel perspectives for the innovation of targeted tumour therapeutics.

Regulation of histone H3K27 methylation in inflammation and cancer

Inflammation is a multifaceted defense mechanism of the immune system against infection. Chronic inflammation is intricately linked to all stages of tumorigenesis and is therefore associated with an elevated risk of developing serious cancers. Epigenetic mechanisms have the capacity to trigger inflammation as well as facilitate tumor development and transformation within an inflammatory context. They achieve this by dynamically modulating the expression of both pro-inflammatory and anti-inflammatory cytokines, which in turn sustains chronic inflammation. The aberrant epigenetic landscape reconfigures the transcriptional programs of inflammatory and oncogenic genes. This reconfiguration is pivotal in dictating the biological functions of both tumor cells and immune cells. Aberrant histone H3 lysine 27 site (H3K27) methylation has been shown to be involved in biological behaviors such as inflammation development, tumor progression, and immune response. The establishment and maintenance of this repressive epigenetic mark is dependent on the involvement of the responsible histone modifying enzymes enhancer of zeste homologue 2 (EZH2), jumonji domain containing 3 (JMJD3) and ubiquitously transcribed tetratricopeptide repeat gene X (UTX) as well as multiple cofactors. In addition, specific pharmacological agents have been shown to modulate H3K27 methylation levels, thereby modulating inflammation and carcinogenesis. This review comprehensively summarises the current characteristics and clinical significance of epigenetic regulation of H3K27 methylation in the context of inflammatory response and tumor progression.

Liquid-liquid phase separation in viral infection: From the occurrence and function to treatment potentials

Liquid-liquid phase separation (LLPS) of biomacromolecules, as a widespread cellular functional mechanism, is closely related to life processes, and is also commonly present in the lifecycle of viruses. Viral infection often leads to the recombination and redistribution of intracellular components to form biomacromolecule condensates assembled from viral replication-related proteins and intracellular components, which plays an important role in the process of viral infection. In this review, the key and influencing factors of LLPS are generalized, which mainly depend on various molecular interactions and environmental conditions in solution. Meanwhile, some examples of viruses utilizing LLPS are summarized, which are conducive to further understanding the subtle and complex biological regulatory processes between phase condensation and viruses. Finally, some representative antiviral drugs targeting phase separation that have been discovered are also outlined. In conclusion, in-depth study of the role of LLPS in viral infection is helpful to understand the mechanisms of virus-related diseases from a new perspective, and also provide a new therapeutic strategy for future treatments.

FATS inhibits the Wnt pathway and induces apoptosis through degradation of MYH9 and enhances sensitivity to paclitaxel in breast cancer

Breast cancer is one of the most prevalent and diverse malignancies, and, with global cases increasing, the need for biomarkers to inform individual sensitivity to chemotherapeutics has never been greater. Our retrospective clinical analysis predicted that the expression of the fragile site-associated tumor suppressor (FATS) gene was associated with the sensitivity of breast cancer to neoadjuvant chemotherapy with paclitaxel. In vitro experiments subsequently demonstrated that FATS significantly increased the inhibitory effects of paclitaxel on breast cancer cells' migration, growth, and survival. An interaction screen revealed that FATS interacted with MYH9 and promoted its degradation via the ubiquitin-proteasome pathway, thereby downregulating Wnt signaling. By overexpressing FATS and MYH9, we demonstrated that FATS enhanced paclitaxel-induced apoptosis in breast cancer cells by degrading MYH9 to downregulate the Wnt pathway. We also demonstrated in a mouse xenograft model that FATS significantly increased the chemosensitivity of breast cancer cells to paclitaxel in vivo. This study presents a new mechanism by which FATS interacts with MYH9 to suppress the Wnt/β-catenin signaling pathway and induce apoptosis, thus enhancing the sensitivity of breast cancer cells to paclitaxel chemotherapy. The results also propose novel biomarkers for predicting breast cancer sensitivity to neoadjuvant chemotherapy with paclitaxel. Finally, we provide in vivo evidence that the combination of paclitaxel with IWR-1, a novel Wnt pathway inhibitor, synergistically suppresses breast cancer growth, laying the foundation for future trials with this drug combination. These results therefore provide a number of potential solutions for more precise treatment of patients with breast cancer in the future.

RNF2 promotes chondrosarcoma progression by regulating ubiquitination and degradation of CBX7

OBJECTIVE

Chondrosarcoma (CHS) is resistant to conventional chemotherapy and radiotherapy and currently lacks effective treatment options when in advanced stages. Accordingly, this research investigated the mechanism of RNF2/CBX7 in CHS to drive the development of molecularly targeted drugs for CHS.

METHODS

RNF2 and CBX7 levels were detected in CHS cells and tissues. RNF2 and CBX7 expression was modulated through cell transfection to examine their effects on cell proliferation, apoptosis, migration, and angiogenesis. The correlation between RNF2 and CBX7 levels was determined, and the ubiquitination level of CBX7 was tested. Protein synthesis was blocked in RNF2-knockdown/overexpressing cells with CHX to assess the effect of RNF2 on CBX7 stability. JJ012 cells transfected with LV-sh-RNF2 were subcutaneously injected into nu/nu nude mice to ascertain the action of RNF2 in the growth and metastasis of CHS.

RESULTS

RNF2 was highly expressed in CHS cells and tissues. RNF2 knockdown curbed CHS cell proliferation, migration, and angiogenesis while promoting apoptosis. RNF2 knockdown in JJ012 cells upregulated CBX7 protein levels and reduced CBX7 ubiquitination, whilst RNF2 had no effect on CBX7 mRNA expression. CBX7 knockdown partially nullified the repressing effects of RNF2 knockdown on CHS cell proliferation, migration, and angiogenesis, and CBX7 overexpression partially abolished the promotional effects of RNF2 overexpression. LV-sh-RNF2 prominently restricted tumor growth and weight and declined lung metastatic nodules and Ki-67-positive cells in mice.

CONCLUSION

RNF2 fosters CHS progression by elevating CBX7 degradation via the ubiquitination pathway.

The Hippo signalling pathway in bone homeostasis: Under the regulation of mechanics and aging

The Hippo signalling pathway is a conserved kinase cascade that orchestrates diverse cellular processes, such as proliferation, apoptosis, lineage commitment and stemness. With the onset of society ages, research on skeletal aging-mechanics-bone homeostasis has exploded. In recent years, aging and mechanical force in the skeletal system have gained groundbreaking research progress. Under the regulation of mechanics and aging, the Hippo signalling pathway has a crucial role in the development and homeostasis of bone. We synthesize the current knowledge on the role of the Hippo signalling pathway, particularly its downstream effectors yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), in bone homeostasis. We discuss the regulation of the lineage specification and function of different skeletal cell types by the Hippo signalling pathway. The interactions of the Hippo signalling pathway with other pathways, such as Wnt, transforming growth factor beta and nuclear factor kappa-B, are also mentioned because of their importance for modulating bone homeostasis. Furthermore, YAP/TAZ have been extensively studied as mechanotransducers. Due to space limitations, we focus on reviewing how mechanical forces and aging influence cell fate, communications and homeostasis through a dysregulated Hippo signalling pathway.

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.

Targeting metabolism to influence cellular senescence a promising anti-cancer therapeutic strategy

Metabolic disorders are considered the hallmarks of cancer and metabolic reprogramming is emerging as a new strategy for cancer treatment. Exogenous and endogenous stressors can induce cellular senescence; the interactions between cellular senescence and systemic metabolism are dynamic. Cellular senescence disrupts metabolic homeostasis in various tissues, which further promotes senescence, creating a vicious cycle facilitating tumor occurrence, recurrence, and altered outcomes of anticancer treatments. Therefore, the regulation of cellular senescence and related secretory phenotypes is considered a breakthrough in cancer therapy; moreover, proteins involved in the associated pathways are prospective therapeutic targets. Although studies on the association between cellular senescence and tumors have emerged in recent years, further elucidation of this complex correlation is required for comprehensive knowledge. In this paper, we review the research progress on the correlation between cell aging and metabolism, focusing on the strategies of targeting metabolism to modulate cellular senescence and the progress of relevant research in the context of anti-tumor therapy. Finally, we discuss the significance of improving the specificity and safety of anti-senescence drugs, which is a potential challenge in cancer therapy.

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.

MST1/2: Important regulators of Hippo pathway in immune system associated diseases

The Hippo signaling pathway is first found in Drosophila and is highly conserved in evolution. Previous studies on this pathway in mammals have revealed its key role in cell proliferation and differentiation, organ size control, and carcinogenesis. Apart from these, recent findings indicate that mammalian Ste20-like kinases 1 and 2 (MST1/2) have significant effects on immune regulation. In this review, we summarize the updated understanding of how MST1/2 affect the regulation of the immune system and the specific mechanism. The effect of MST1/2 on immune cells and its role in the tumor immune microenvironment can alter the body's response to tumor cells. The relationship between MST1/2 and the immune system suggests new directions in the manipulation of immune responses for clinical immunotherapy, especially for tumor treatment.