Comprehensive Analysis of the Expression and Prognosis of chromobox Family Members in Breast Cancer

Integrated bioinformatics investigation and experimental validation reveals the clinical and biological significance of chromobox family in breast cancer

Chromobox (CBX) proteins are essential components of the Polycomb group and play pivotal roles in tumor onset, progression, and metastasis. However, the prognostic significance and functions of CBXs in the advancement of breast cancer (BC) have not been sufficiently investigated. A comprehensive analysis of the expression and prognostic relevance of CBX1-8 in BC was conducted comprehensively using The Cancer Genome Atlas (TCGA) and multiple databases. High mRNA expression of CBX2, CBX3, and CBX5 in BC patients was significantly associated with reduced overall survival (OS). Results from univariate and multivariate Cox regression analysis revealed that the mRNA expression level of CBX2 in BC patients served as an independent prognostic factor. In Luminal A and Luminal B BC subtypes, high expression of CBX2 correlated with unfavorable prognosis. Subsequent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated a strong association between CBX2 and the cell cycle as well as DNA replication processes. CCK-8 and EdU assays demonstrated that silencing CBX2 inhibited the proliferation of T47D and MCF7 cell lines. Moreover, the cell cycle assay indicated that CBX2 silencing led to cell cycle arrest, accompanied by a significant decrease in the levels of CDK4 and CyclinD1. Elevated CBX2 expression significantly correlated with the infiltration of T cells, B cells, macrophages, and dendritic cells in BC. Our findings could provide new perspectives for identifying potential prognostic markers within the CBX family in BC. Targeting CBX2 may present a promising approach to address endocrine resistance in BC therapy.

Identification of Eight Histone Methylation Modification Regulators Associated With Breast Cancer Prognosis

Histone methylation is an important epigenetic modification process coordinated by histone methyltransferases, histone demethylases and histone methylation reader proteins and plays a key role in the occurrence and development of cancer. This study constructed a risk scoring model around histone methylation modification regulators and conducted a multidimensional comprehensive analysis to reveal its potential role in breast cancer prognosis and drug sensitivity. First, 144 histone methylation modification regulators (HMMRs) were subjected to differential analysis and univariate Cox regression analysis, and nine differentially expressed HMMRs associated with survival were screened out. Next, a risk scoring model consisting of eight HMMRs was constructed using the LASSO regression algorithm, exhibiting independent predictive values in training and validation cohorts. Then, immune analysis shows that patients in the high-risk group divided by the risk scoring model has weakened the immune response. In addition, through functional analysis of differentially expressed genes (DEGs) between high-risk and low-risk groups, we confirmed that the DEGs mainly affected the nucleoplasm and tumour microenvironment. Finally, drug sensitivity analysis demonstrated that our model could be useful for drug screening and identify potential drugs for treating BRCA patients. In conclusion, these eight HMMRs may be key factors in the prognosis and drug sensitivity of BRCA patients.

Identification of Cbx6 as a potential biomarker in renal ischemia/reperfusion injury

BACKGROUND

Renal ischemia/reperfusion injury (RIRI) is an inevitable consequence of kidney transplantation and has a negative impact on both short-term and long-term graft survival. The identification of key markers in RIRI to improve the prognosis of patients would be highly advantageous.

METHODS

Gene expression profile data of GSE27274 were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were analyzed using the Limma package. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment of DEGs were performed. Support vector machine-recursive feature elimination and least absolute shrinkage and selection operator regression modeling were both performed to identify potential biomarkers. The GSE148420 dataset, quantitative reverse transcriptase-PCR, and western blotting results of kidney tissue samples were used to validate the bioinformatic analysis. Lastly, exploring differences between different groups through gene set enrichment analysis and using DsigDB database to identify potential therapeutic drugs targeting hub genes.

RESULTS

A total of 160 upregulated and 180 downregulated DEGs were identified. Functional enrichment analysis identified significant enrichment in processes involving peroxisomes. As a subunit of Polycomb Repressive Complex 1(PRC1), chromobox 6(Cbx6) was identified as a potential biomarker with an area under the receiver operating characteristic curve of 0.875 (95% confidence interval 0.624-1.000) in the validation cohort, and it was highly expressed in the RIRI group (p < 0.05). In the high expression group Cbx6 was more enriched in the toll-like receptor signaling pathway. We predicted 15 potential drugs targeting hub genes of RIRI.

CONCLUSIONS

We identified Cbx6 as a potential biomarker for RIRI and 15 potential drugs for the treatment of RIRI, which might shed a light on the treatment of RIRI.

The predictive significance of chromobox family members in prostate cancer in humans

PURPOSE

The Chromobox (CBX) family proteins are crucial elements of the epigenetic regulatory machinery and play a significant role in the development and advancement of cancer. Nevertheless, there is limited understanding regarding the role of CBXs in development or progression of prostate cancer (PCa). Our objective is to develop a unique prognostic model associated with CBXs to improve the accuracy of predicting outcomes of patients with PCa.

METHODS

Data from TCGA and GEO databases were analyzed to assess differential expression, prognostic value, gene pathway enrichment, and immune cell infiltration. COX regression analysis was utilized to identify the independent prognostic factors that impact disease-free survival (DFS). The expression of CBX2 and FOXP3+ cells infiltration was verified by immunohistochemical staining of clinical tissue sections. In vitro proliferation, migration and invasion assay were conducted to examine the function of CBX2. RNA-seq was employed to examine the CBX2 related pathway enrichment.

RESULTS

CBX2, CBX3, CBX4, and CBX8 were upregulated, while CBX6 and CBX7 were downregulated in PCa tissues. CBXs expression varied by stage and grade. Elevated expression of CBX1, CBX2, CBX3, CBX4 and CBX8 is correlated with poor outcome. CBX2 expression, T stage, and Gleason score were independent prognostic factors. The expression level of CBX2 in PCa tissues was significantly higher than that in adjacent normal tissues. More Treg infiltration was observed in the group with high CBX2 expression. CBX2 expression affected PCa cell growth, migration, and invasion.

CONCLUSIONS

CBX2 is involved in the development and advancement of PCa, suggesting its potential as a reliable prognostic indicator for PCa patients.