Retinoblastoma binding protein 4 up-regulation is correlated with hepatic metastasis and poor prognosis in colon cancer patients

RBBP4: A novel diagnostic and prognostic biomarker for non-small-cell lung cancer correlated with autophagic cell death

BACKGROUND

Non-small-cell lung cancer (NSCLC) often presents at later stages, typically associated with poor prognosis. Autophagy genes play a role in the progression of tumors. This study investigated the clinical relevance, prognostic value, and biological significance of RBBP4 in NSCLC.

METHODS

We assessed RBBP4 expression using the GSE30219 and TCGA NSCLC datasets and NSCLC cells, exploring its links with clinical outcomes, tumor immunity, and autophagy genes through bioinformatics analysis after transcriptome sequencing of RBBP4-knockdown and control PC9 cells. We identified differentially expressed genes (DEGs) and conducted Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment, and protein-protein interaction network analyses. The significance of autophagy-related DEGs was evaluated for diagnosis and prognosis using the GSE30219 dataset. Experiments both in vivo and in vitro explored the biological mechanisms behind RBBP4-mediated autophagic cell death in NSCLC.

RESULTS

RBBP4 overexpression in NSCLC correlates with a poorer prognosis. Eighteen types of immune cell were significantly enriched in cultures that had low RBBP4 expression compared high expression. DEGs associated with RBBP4 are enriched in autophagy pathways. Transcriptomic profiling of the PC9 cell line identified autophagy-related DEGs associated with RBBP4 that exhibited differential expression in NSCLC, suggesting prognostic applications. In vitro experiments demonstrated that RBBP4 knockdown induced autophagy and apoptosis in PC9 cells, promoting cell death, which was inhibited by 3-MA. In vivo, targeted siRNA against RBBP4 significantly reduced tumor development in PC9 cell-injected nude mice, elevating autophagy-related protein levels and inducing apoptosis and necrosis in tumor tissues.

CONCLUSION

In NSCLC, RBBP4 upregulation correlates with poor prognosis and altered immunity. Its knockdown induces autophagic cell death in NSCLC cells. These results indicate RBBP4 as a potential NSCLC diagnostic marker and its autophagy modulation as a prospective therapeutic target.

RebL1 is required for macronuclear structure stability and gametogenesis in Tetrahymena thermophila

Histone modification and nucleosome assembly play important roles in chromatin-related processes. Histone chaperones form different complexes and coordinate histone transportation and assembly. Various histone chaperone complexes have been identified in different organisms. The ciliate protozoa (ciliates) have various chromatin structures and different nuclear morphology. However, histone chaperone components and functions of different subunits remain unclear in ciliates. Tetrahymema thermophila contains a transcriptionally active macronucleus (MAC) and a transcriptionally inactive micronucleus (MIC) which exhibit multiple replication and various chromatin remodeling progresses during vegetative growth and sexual developmental stages. Here, we found histone chaperone RebL1 not only localized evenly in the transcriptionally active MAC but also dynamically changed in the MIC during vegetative growth and sexual developmental stages. REBL1 knockdown inhibited cellular proliferation. The macronuclear morphology became bigger in growing mutants. The abnormal macronuclear structure also occurred in the starvation stage. Furthermore, micronuclear meiosis was disturbed during sexual development, leading to a failure to generate new gametic nuclei. RebL1 potentially interacted with various factors involved in histone-modifying complexes and chromatin remodeling complexes in different developmental stages. REBL1 knockdown affected expression levels of the genes involved in chromatin organization and transcription. Taken together, RebL1 plays a vital role in maintaining macronuclear structure stability and gametogenesis in T. thermophila.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-024-00219-z.

Expression and clinical significance of RBBP4 gene in lower-grade glioma: An integrative analysis

This study investigated the expression pattern of retinoblastoma binding protein 4 (RBBP4) gene in glioma and explored its associations with clinicopathologic characteristics and prognosis of patients. Data retrieved from the GEPIA, CGGA, HPA and TIMER databases were processed to analyze RBBP4 expression in glioma and investigate its relationship with clinicopathologic characteristics, tumor immune infiltration and prognosis in glioma patients. Immunohistochemistry was applied to determine the expression of RBBP4 protein in glioma tissue. Additionally, the Coexpedia database was visited to identify co-expressed genes for RBBP4 gene, while the Cytoscape software was run to visualize the enriched GO entries and KEGG pathways of these co-expressed genes. The expression levels of RBBP4 in lower-grade glioma (LGG) and glioblastoma (GBM) tissues were markedly elevated when compared to normal tissues (both p < 0.05). The up-regulation of RBBP4 expression was associated with an increase in WHO grade (II-IV), wild-type IDH, and 1p/19q non-codeletion (all p < 0.05). Multi-variate Cox regression analysis showed that both increased abundance of infiltrating macrophages and up-regulated RBBP4 expression independently predicted poor survival outcomes in LGG patients (both p < 0.05). Furthermore, RBBP4 expression exhibited significant positive correlations with the abundance of infiltrating B cell, CD8+ T cell, CD4+ T cell, macrophage, neutrophil, and dendritic cell in LGG (all p < 0.05). Functional enrichment analyses indicated that the co-expressed genes associated with RBBP4 were highly involved in pathways such as the p53 signaling pathway, cell cycle, DNA replication, glutathione metabolism, as well as biological processes including cell cycle process, DNA replication, and DNA repair. High levels of RBBP4 are predictive for the poor survival outcome of LGG patients. RBBP4 gene, therefore, is expected to be a potential biomarker for prognosis of LGG and a target for immunotherapy.

Effect and Prognosis Factors of Combining Laparoscopic Radical Resection of Colon Adenocarcinoma with Docetaxel Therapy in Treating Middle and Advanced Colon Adenocarcinoma

Objective. The aim of the study is to explore the clinical efficacy and prognosis factors of joint application of laparoscopic radical resection of colon adenocarcinoma (COAD) and docetaxel therapy in treating COAD of middle and advanced stages. Methods. The clinical data of 103 COAD patients of middle and advanced stages treated in our hospital from July 2016 to July 2018 were selected for the retrospective analysis, all patients received the treatment scheme of combining laparoscopic radical resection of COAD with docetaxel therapy for the observation of short-term efficacy, follow-up was conducted to record their 3-year survival, and relevant factors affecting patient prognosis were analyzed by the logistic regression model. Results. After treatment, the total remission rate of patients was 75.73% (78/103), the total incidence rate of adverse reactions was 16.50% (17/103); patients’ level values of various serum tumor markers after treatment were significantly lower than those before treatment ( $P<0.001$ ); according to the univariate analysis results, for COAD patients with different tumor diameters, differentiated degrees, TNM stages, perineural invasion degrees, pathological types, and depths of invasion, their modality rates were statistically different ( $P<0.05$ ); and the logistic regression analysis showed that tumor diameter ≥5 cm, poor differentiation, TNM stage IV, perineural invasion, pathologically signet-ring cell carcinoma, and T3-invasion were the independent risk factors affecting patient prognosis ( $P<0.05$ ). Conclusion. Combining laparoscopic radical resection of COAD with docetaxel therapy in treating COAD of middle and advanced stages achieves affirmed short-term efficacy, which can reduce patients’ level of serum tumor markers and ensure high safety and good survival prognosis. Tumor diameter, differentiated degree, TNM stage, perineural invasion, pathological type, and T3-invasion are the relevant factors affecting the prognosis of middle and advanced COAD.

RBBP4 plays a vital role in the malignant progression of triple-negative breast cancer by regulating epithelial-mesenchymal transition

BACKGROUND

Mounting findings have revealed the increasingly appreciated functional importance of Retinoblastoma binding protein (RBBP) family members in tumorigenesis. However, the biological function of RBBP4 in breast cancer, especially in the most malignant and aggressive subtype, i.e., triple-negative breast cancer (TNBC), remains to be elucidated.

OBJECTIVE

The present study was aimed at elucidating the role of RBBP4 in TNBC pathogenesis.

METHODS

The expression of RBBP4 in TNBC tissues and cell lines was examined and its oncogenic-related functions were verified by performing a series of in vitro and in vivo experiments.

RESULTS

At the cellular and tissue level, a marked increase in the RBBP4 expression was observed. Functionally, RBBP4 knockdown dramatically inhibited the proliferation, invasion, and migration of TNBC cells in vitro. Further, mechanistically, RBBP4 downregulation regulated the inactivation of epithelial-mesenchymal transition (EMT) of TNBC cells. In vivo xenograft model in nude mice also validated these results.

CONCLUSION

Collectively, our results showed that the inhibition of RBBP4 suppresses the malignant progression of TNBC cells by regulating EMT. Thus, RBBP4 could serve as a novel biomarker and target for TNBC diagnosis and treatment.

Photoaffinity labeling-based chemoproteomic strategy reveals RBBP4 as a cellular target of protopanaxadiol against colorectal cancer cells

ABSTRCT Protopanaxadiol (PPD), a main ginseng metabolite, exerts powerful anticancer effects against multiple types of cancer; however, its cellular targets remain elusive. Here, we synthesized a cell-permeable PPD probe via introducing a bifunctional alkyne-containing diazirine photo-crosslinker and performed a photoaffinity labeling-based chemoproteomic study. We identified retinoblastoma binding protein 4 (RBBP4), a chromatin remodeling factor, as an essential cellular target of PPD in HCT116 colorectal cancer cells. PPD significantly decreased RBBP4-dependent trimethylation at lysine 27 of histone H3 (H3K27me3), a crucial epigenetic marker that correlates with histologic signs of colorectal cancer aggressiveness, and PPD inhibition of proliferation and migration of HCT116 cells was antagonized by RBBP4 RNA silencing. Collectively, our study highlights a previously undisclosed anti-colorectal cancer cellular target of the ginseng metabolite and advances the fundamental understanding of RBBP4 functions via a chemical biology strategy.

Colorectal liver metastasis: molecular mechanism and interventional therapy

Colorectal cancer (CRC) is one of the most frequently occurring malignancy tumors with a high morbidity additionally, CRC patients may develop liver metastasis, which is the major cause of death. Despite significant advances in diagnostic and therapeutic techniques, the survival rate of colorectal liver metastasis (CRLM) patients remains very low. CRLM, as a complex cascade reaction process involving multiple factors and procedures, has complex and diverse molecular mechanisms. In this review, we summarize the mechanisms/pathophysiology, diagnosis, treatment of CRLM. We also focus on an overview of the recent advances in understanding the molecular basis of CRLM with a special emphasis on tumor microenvironment and promise of newer targeted therapies for CRLM, further improving the prognosis of CRLM patients.

Genome-Wide Transcriptional Changes of Rhodosporidium kratochvilovae at Low Temperature

Rhodosporidium kratochvilovae strain YM25235 is a cold-adapted oleaginous yeast strain that can grow at 15°C. It is capable of producing polyunsaturated fatty acids. Here, we used the Nanopore Platform to first assemble the R. kratochvilovae strain YM25235 genome into a 23.71 Mb size containing 46 scaffolds and 8,472 predicted genes. To explore the molecular mechanism behind the low temperature response of R. kratochvilovae strain YM25235, we analyzed the RNA transcriptomic data from low temperature (15°C) and normal temperature (30°C) groups using the next-generation deep sequencing technology (RNA-seq). We identified 1,300 differentially expressed genes (DEGs) by comparing the cultures grown at low temperature (15°C) and normal temperature (30°C) transcriptome libraries, including 553 significantly upregulated and 747 significantly downregulated DEGs. Gene ontology and pathway enrichment analysis revealed that DEGs were primarily related to metabolic processes, cellular processes, cellular organelles, and catalytic activity, whereas the overrepresented pathways included the MAPK signaling pathway, metabolic pathways, and amino sugar and nucleotide sugar metabolism. We validated the RNA-seq results by detecting the expression of 15 DEGs using qPCR. This study provides valuable information on the low temperature response of R. kratochvilovae strain YM25235 for further research and broadens our understanding for the response of R. kratochvilovae strain YM25235 to low temperature.

The ubiquitin ligase RNF5 determines acute myeloid leukemia growth and susceptibility to histone deacetylase inhibitors

Acute myeloid leukemia (AML) remains incurable, largely due to its resistance to conventional treatments. Here, we find that increased abundance of the ubiquitin ligase RNF5 contributes to AML development and survival. High RNF5 expression in AML patient specimens correlates with poor prognosis. RNF5 inhibition decreases AML cell growth in culture, in patient-derived xenograft (PDX) samples and in vivo, and delays development of MLL-AF9-driven leukemogenesis in mice, prolonging their survival. RNF5 inhibition causes transcriptional changes that overlap with those seen upon histone deacetylase (HDAC)1 inhibition. RNF5 induces the formation of K29 ubiquitin chains on the histone-binding protein RBBP4, promoting its recruitment to and subsequent epigenetic regulation of genes involved in AML maintenance. Correspondingly, RNF5 or RBBP4 knockdown enhances AML cell sensitivity to HDAC inhibitors. Notably, low expression of both RNF5 and HDAC coincides with a favorable prognosis. Our studies identify an ERAD-independent role for RNF5, demonstrating that its control of RBBP4 constitutes an epigenetic pathway that drives AML, and highlight RNF5/RBBP4 as markers useful to stratify patients for treatment with HDAC inhibitors.

Challenging, Accurate and Feasible: CAF-1 as a Tumour Proliferation Marker of Diagnostic and Prognostic Value

Simple Summary

There is an emerging need for new weapons in the battle against cancer; therefore, the discovery of new biomarkers with diagnostic, prognostic, and therapeutic value is a priority of current cancer research. An important task is to identify how quickly a tumour proliferates. A tumour’s proliferation rate is critical for grading and clinical decision-making; hence, there is an imperative need for accurate proliferation markers. Here, we review evidence demonstrating that chromatin assembly factor 1 (CAF-1) is a proliferation marker of clinical value. CAF-1 is selectively expressed in proliferating cells and its expression can be evaluated by immunohistochemistry in cytology smears and biopsies. CAF-1 expression is increased in almost all cancers and correlates strongly with the expression of Ki-67, the current routine proliferation marker. Overexpression of CAF-1 is associated with poor clinical outcome (advanced cancer stage, recurrence, metastasis, and decreased survival). CAF-1 is a robust, reproducible, and feasible proliferation marker of prognostic importance and may represent an attractive alternative or complementary to Ki-67 for cancer stratification and clinical guidance.

Abstract

The discovery of novel biomarkers of diagnostic, prognostic, and therapeutic value is a major challenge of current cancer research. The assessment of tumour cell proliferative capacity is pivotal for grading and clinical decision-making, highlighting the importance of proliferation markers as diagnostic and prognostic tools. Currently, the immunohistochemical analysis of Ki-67 expression levels is routinely used in clinical settings to assess tumour proliferation. Inasmuch as the function of Ki-67 is not fully understood and its evaluation lacks standardization, there is interest in chromatin regulator proteins as alternative proliferation markers of clinical value. Here, we review recent evidence demonstrating that chromatin assembly factor 1 (CAF-1), a histone chaperone selectively expressed in cycling cells, is a proliferation marker of clinical value. CAF-1 expression, when evaluated by immunocytochemistry in breast cancer cytology smears and immunohistochemistry in cancer biopsies from several tissues, strongly correlates with the expression of Ki-67 and other proliferation markers. Notably, CAF-1 expression is upregulated in almost all cancers, and CAF-1 overexpression is significantly associated, in most cancer types, with high histological tumour grade, advanced stage, recurrence, metastasis, and decreased patient survival. These findings suggest that CAF-1 is a robust, reproducible, and feasible proliferation marker of prognostic importance. CAF-1 may represent an attractive alternative or complementary to Ki-67 for cancer stratification and clinical guidance.

Structure Based Design of Bicyclic Peptide Inhibitors of RbAp48

The scaffolding protein RbAp48 is part of several epigenetic regulation complexes and is overexpressed in a variety of cancers. In order to develop tool compounds for the study of RbAp48 function, we have developed peptide inhibitors targeting the protein-protein interaction interface between RbAp48 and the scaffold protein MTA1. Based on a MTA1-derived linear peptide with low micromolar affinity and informed by crystallographic analysis, a bicyclic peptide was developed that inhibits the RbAp48/MTA1 interaction with a very low nanomolar KD value of 8.56 nM, and which showed appreciable stability against cellular proteases. Design included exchange of a polar amide cyclization strategy to hydrophobic aromatic linkers enabling mono- and bicyclization by means of cysteine alkylation, which improved affinity by direct interaction of the linkers with a hydrophobic residue on RbAp48. Our results demonstrate that stepwise evolution of a structure-based design is a suitable strategy for inhibitor development targeting PPIs.

LncRNA HOXA-AS2 promotes glioblastoma carcinogenesis by targeting miR-885-5p/RBBP4 axis

Background

LncRNA HOXA-AS2 has been found in the literature to deteriorate glioblastoma. However, its regulatory mechanism is yet to be fully investigated. Our study focused chiefly on the interaction and role of the HOXA-AS2/miR-885-5p/RBBP4 axis in the development of glioblastoma.

Methods

qRT-PCR analysis was performed to detect the expression of lncRNA, miRNA and mRNA in glioblastoma tissues and cells. Dual-luciferase assay, RIP assay and RNA pull-down assay were later carried out to reveal the interactions among HOXA-AS2, miR-885-5p and RBBP4. After that, CCK-8 assay, BrdU assay, nude mice xenografting assay, western blot assay, and flow cytometry were carried out to analyze the effect of the HOXA-AS2/miR-885-5p/RBBP4 axis on glioblastoma samples.

Results

HOXA-AS2 and RBBP4 were found to be overexpressed in glioblastoma. Experimental results showed that HOXA-AS2 and RBBP4 contributed to the tumorigenesis of glioblastoma cells. However, miR-885-5p was observed to be downregulated in glioblastoma. Findings also indicated that HOXA-AS2 could negatively regulate miR-885-5p, thereby enhancing RBBP4 expression.

Conclusion

Overall, HOXA-AS2 promoted the tumorigenesis of glioblastoma by targeting and regulating miR-885-5p to induce the expression of RBBP4.

RBBP4 promotes colon cancer malignant progression via regulating Wnt/β-catenin pathway

BACKGROUND

Our previous study demonstrated that RBBP4 was upregulated in colon cancer and correlated with poor prognosis of colon cancer and hepatic metastasis. However, the potential biological function of RBBP4 in colon cancer is still unknown.

AIM

To investigate the biological role and the potential mechanisms of RBBP4 in colon cancer progression.

METHODS

Real-time polymerase chain reaction and western blot analysis were used to detect the expression of RBBP4 in colon cancer cell lines. The cell proliferation and viability of SW620 and HCT116 cells with RBBP4 knockdown was detected by Cell Counting Kit-8 and 5-ethynyl-2’-deoxyuridine staining. The transwell assay was used to detect the invasion and migration capabilities of colon cancer cells with RBBP4 knockdown. Flow cytometry apoptosis assay was used to detect the apoptosis of colon cancer cells. Western blotting analysis was used to detect the expression of epithelial-mesenchymal transition and apoptosis related markers in colon cancer. The nuclear translocation of β-catenin was examined by Western blotting analysis in colon cancer cells with RBBP4 knockdown. The TOPFlash luciferase assay was used to detect the effect of RBBP4 on Wnt/β-catenin activation. The rescue experiments were performed in colon cancer cells treated with Wnt/β-catenin activator LiCl and RBBP4 knockdown.

RESULTS

We found that RBBP4 was highly expressed in colon cancer cell lines. The 5-ethynyl-2’-deoxyuridine assay showed that knockdown of RBBP4 significantly inhibited cell proliferation. RBBP4 inhibition reduced cell invasion and migration via regulating proteins related to epithelial-mesenchymal transition. Knockdown of RBBP4 significantly inhibited survivin-mediated apoptosis. Mechanistically, the TOPFlash assay showed that RBBP4 knockdown increased activity of the Wnt/β-catenin pathway. Meanwhile, RBBP4 knockdown suppressed nuclear translocation of β-catenin. With Wnt/β-catenin activator, rescue experiments suggested that the role of RBBP4 in colon cancer progression was dependent on Wnt/β-catenin pathway.

CONCLUSION

RBBP4 promotes colon cancer development via increasing activity of the Wnt/β-catenin pathway. RBBP4 may serve as a novel therapeutic target in colon cancer.

Tumour suppressor candidate 3 inhibits biological function and increases endoplasmic reticulum stress of melanoma cells WM451 by regulating AKT/GSK3-β/β-catenin pathway

Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. This study aims to evaluate the significance of TUSC3, an endoplasmic reticulum stress (ERS)-inducible gene and explore its relationship with AKT/GSK3-β/β-catenin signalling pathway in melanoma cell WM451. We investigated TUSC3 expression in melanoma cell by qRT-PCR, CCK-8 and clonal formation assays were utilized to evaluate cell proliferation. Wound healing and transwell experiments detected cell migration and invasion. Flow cytometry detected the level of apoptosis. Western blot analysed MMP2, MMP9, p-AKT, p-GSK3-β, β-catenin and AKT, GSK3-β, ERS-related proteins and apoptosis-related proteins in WM451 cells. The results revealed that TUSC3 was remarkably decreased in melanoma cell lines. Overexpression of TUSC3 significantly inhibits melanoma cell WM451 biological functions and promotes expression of ERS-related proteins in WM451 cells, increases ERS in WM451 cells by inhibiting AKT/GSK3-β/β-catenin pathway. These finding suggest that TUSC3 regulates biological functions of melanoma cells WM451 and increases ERS in melanoma cells WM451 via the inhibition of the AKT/GSK3-β/β-catenin signalling pathway. SIGNIFICANCE OF THE STUDY: Melanoma is a highly malignant and is a life-threatening disease with no effective treatment currently. Therefore, studying the molecular mechanism of melanoma occurrence and metastasis is essential for the treatment of melanoma. Meanwhile, mounting studies suggest that TUSC3 is considered to be closely associated with the development of various malignancies. TUSC3 regulates proliferation, migration and epithelial-to-mesenchymal transition, but the molecular mechanism of the tumour suppressor effects of TUSC3 on melanoma cells is not well understood. Our study demonstrates that TUSC3 inhibits biological function of melanoma cells and increases ERS in melanoma cells by inhibiting AKT/GSK3-β/β-catenin pathway. And this is expected to be a new target and method for the treatment of melanoma.