C/EBPβ regulates homeostatic and oncogenic gastric cell proliferation

Single-cell analysis uncovers high-proliferative tumour cell subtypes and their interactions in the microenvironment of gastric cancer

Gastric cancer (GC) remains a prominent malignancy that poses a significant threat to human well-being worldwide. Despite advancements in chemotherapy and immunotherapy, which have effectively augmented patient survival rates, the mortality rate associated with GC remains distressingly high. This can be attributed to the elevated proliferation and invasive nature exhibited by GC. Our current understanding of the drivers behind GC cell proliferation remains limited. Hence, in order to reveal the molecular biological mechanism behind the swift advancement of GC, we employed single-cell RNA-sequencing (scRNA-seq) to characterize the tumour microenvironment in this study. The scRNA-seq data of 27 patients were acquired from the Gene Expression Omnibus database. Differential gene analysis, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and Gene Set Enrichment Analysis were employed to investigate 38 samples. The copy number variation level exhibited by GC cells was determined using InferCNV. The CytoTRACE, Monocle and Slingshot analysis were used to discern the cellular stemness and developmental trajectory of GC cells. The CellChat package was utilized for the analysis of intercellular communication crosstalk. Moreover, the findings of the data analysis were validated through cellular functional tests conducted on the AGS cell line and SGC-7901 cell line. Finally, this study constructed a risk scoring model to evaluate the differences of different risk scores in clinical characteristics, immune infiltration, immune checkpoints, functional enrichment, tumour mutation burden and drug sensitivity. Within the microenvironment of GC, we identified the presence of 8 cell subsets, encompassing NK_T cells, B_Plasma cells, epithelial cells, myeloid cells, endothelial cells, mast cells, fibroblasts, pericytes. By delving deeper into the characterization of GC cells, we identified 6 specific tumour cell subtypes: C0 PSCA+ tumour cells, C1 CLDN7+ tumour cells, C2 UBE2C+ tumour cells, C3 MUC6+ tumour cells, C4 CHGA+ tumour cells and C5 MUC2+ tumour cells. Notably, the C2 UBE2C+ tumour cells demonstrated a close association with cell mitosis and the cell cycle, exhibiting robust proliferative capabilities. Our findings were fortified through enrichment analysis, pseudotime analysis and cell communication analysis. Meanwhile, knockdown of the transcription factor CREB3, which is highly active in UBE2C+ tumour cells, significantly impedes the proliferation, migration and invasion of GC cells. And the prognostic score model constructed with CREB3-related genes showcased commendable clinical predictive capacity, thus providing valuable guidance for patients' prognosis and clinical treatment decisions. We have identified a highly proliferative cellular subgroup C2 UBE2C+ tumour cells in GC for the first time. The employment of a risk score model, which is based on genes associated with UBE2C expression, exhibits remarkable proficiency in predicting the prognosis of GC patients. In our investigation, we observed that the knockdown of the transcription factor CREB3 led to a marked reduction in cellular proliferation, migration and invasion in GC cell line models. Implementing a stratified treatment approach guided by this model represents a judicious and promising methodology.

Role of Oxidative Stress-Dependent C/EBPβ Expression on CAF Transformation Inducing HCT116 Colorectal Cancer Cell Progression; Migration and Invasion

OBJECTIVE

To investigate oxidative stress-related CAF transformation through C/EBPβ, which affects CRC progression and may have a potential implication for CRC treatment.

METHODS

The conditioned media (CM) from HCT116, CRC cells, was used to activate CCD-18Co, colon fibroblasts, then the ability of activated FBs to induce HCT116 growth and progression was assessed using MTT assay, transwell migration, and matrix invasion assay. Alteration of the cytokine profile and oxidative stress of the activated FBs were studied with cytokine arrays and DCFH-DA assay, respectively. The protein expressions of the CAF markers (α-SMA and FAP) and C/EBPβ were investigated with immunofluorescence and western blotting.

RESULT

It was found that CM from HCT116 cells induced oxidative stress, change of cytokine profile, CAF markers, and the C/EBPβ expression of activated FBs. Furthermore, when the oxidative stress of the activated FBs was suppressed, FAP and C/EBPβ expression were downregulated, correlating with the disabling of their capability to support the cancer progression. The C/EBPβ and prognosis for CRC patients were accessed using the GEPIA dataset, in which high C/EBPβ expression was associated with a poor prognosis.

CONCLUSION

These findings suggest that C/EBPβ expression has a role in CAF transformation in an oxidative stress-related manner and might be used as a target to improve aggressive CRC treatment outcomes.

Integrated analysis of single-cell and bulk RNA-sequencing reveals the poor prognostic value of ABCA1 in gastric adenocarcinoma

PURPOSE

ATP-binding cassette A1 (ABCA1) is a potential prognostic marker for various tumor types. However, the biological effects and prognostic value of ABCA1 in gastric adenocarcinoma (GAC) remain unknown.

METHODS

GAC-associated single-cell RNA and bulk RNA-sequencing (bulk-seq) data were obtained from the Gene Expression Omnibus and The Cancer Genome Atlas databases, respectively. The differential expression of ABCA1 between GAC and normal gastric tissues was analyzed based on the bulk-seq data. Additionally, the relationship between ABCA1 expression and various clinicopathological features was explored. Furthermore, Kaplan-Meier survival and Cox regression analyses were performed to establish the prognostic value of ABCA1. The relationships between ABCA1 expression and anti-tumor drug sensitivity and immune checkpoints were also explored. Finally, the biological functions of ABCA1 were evaluated at the single-cell level, and in vitro studies were performed to assess the effects of ABCA1 on GAC cell proliferation and invasion.

RESULTS

ABCA1 expression is significantly elevated in GAC samples compared with that in normal gastric tissues. Clinical features and survival analysis revealed that high ABCA1 expression is associated with poor clinical phenotypes and prognosis, whereas Cox analysis identified ABCA1 as an independent risk factor for patients with GAC. Furthermore, high ABCA1 expression suppresses sensitivity to various chemotherapeutic drugs, including cisplatin and mitomycin, while upregulating immune checkpoints. ABCA1-overexpressing macrophages are associated with adverse clinical phenotypes in GAC and express unique ligand-receptor pairs that drive GAC progression. In vitro, ABCA1-knockdown GAC cells exhibit significantly inhibited proliferative and invasive properties.

CONCLUSION

High ABCA1 expression promotes an adverse immune microenvironment and low survival rates in patients with GAC. Furthermore, ABCA1 and ABCA1-producing macrophages may serve as novel molecular targets in GAC treatment.

Predicting response to immunotherapy in gastric cancer via assessing perineural invasion-mediated inflammation in tumor microenvironment

BACKGROUND

The perineural invasion (PNI)-mediated inflammation of the tumor microenvironment (TME) varies among gastric cancer (GC) patients and exhibits a close relationship with prognosis and immunotherapy. Assessing the neuroinflammation of TME is important in predicting the response to immunotherapy in GC patients.

METHODS

Fifteen independent cohorts were enrolled in this study. An inflammatory score was developed and validated in GC. Based on PNI-related prognostic inflammatory signatures, patients were divided into Clusters A and B using unsupervised clustering. The characteristics of clusters and the potential regulatory mechanism of key genes were verified by RT-PCR, western-blot, immunohistochemistry and immunofluorescence in cell and tumor tissue samples.The neuroinflammation infiltration (NII) scoring system was developed based on principal component analysis (PCA) and visualized in a nomogram together with other clinical characteristics.

RESULTS

Inflammatory scores were higher in GC patients with PNI compared with those without PNI (P < 0.001). NII.clusterB patients with PNI had abundant immune cell infiltration in the TME but worse prognosis compared with patients in the NII.clusterA patients with PNI and non-PNI subgroups. Higher immune checkpoint expression was noted in NII.clusterB-PNI. VCAM1 is a specific signature of NII.clusterB-PNI, which regulates PD-L1 expression by affecting the phosphorylation of STAT3 in GC cells. Patients with PNI and high NII scores may benefit from immunotherapy. Patients with low nomogram scores had a better prognosis than those with high nomogram scores.

CONCLUSIONS

Inflammation mediated by PNI is one of the results of tumor-nerve crosstalk, but its impact on the tumor immune microenvironment is complex. Assessing the inflammation features of PNI is a potential method in predicting the response of immunotherapy effectively.

Compound Kushen Injection inhibits epithelial-mesenchymal transition of gastric carcinoma by regulating VCAM1 induced by the TNF signaling pathway

BACKGROUND

Gastric carcinoma (GC) treatment needs to be developed rapidly. Compound Kushen Injection (CKI), a formula from traditional Chinese medicine, has been used clinically in combination with chemotherapy to treat GC with satisfactory results. However, the molecular mechanism by which CKI acts to cure GC is still unclear.

METHODS

In the present study, in vivo and in vitro experiments were used to assess the efficacy of CKI. Using ceRNA microarray and TMT technologies, the molecular mechanism of CKI was further investigated at the transcriptional and protein levels, and a bioinformatics approach was employed to investigate and functionally validate key CKI targets in GC.

RESULTS

When combined with cisplatin (DDP), CKI significantly increased its efficacy in preventing the proliferation and metastasis of GC cells and malignant-looking tumors in mice. High-throughput sequencing data and bioinformatics analysis showed that CKI regulated the TNF signaling pathway, epithelial-mesenchymal transition (EMT), with VCAM1 as a key target. The transcription factors CEBPB, JUN, RELA, NFKB1, the EMT mesenchymal-like cell markers N-cadherin and vimentin, as well as the expression of VCAM1 and its upstream signaling driver TNF, were all downregulated by CKI. In contrast, the expression of the EMT epithelial-like cell marker E-cadherin was upregulated.

CONCLUSION

CKI can effectively inhibit GC growth and metastasis, improve body's immunity, and protect normal tissues from damage. The molecular mechanism by which CKI inhibits metastasis of GC is by regulating VCAM1 induced by the TNF signaling pathway to inhibit EMT of GC. Our results provide an important clue to clarify precisely the multi-scale molecular mechanism of CKI in the treatment of GC.

Single-cell transcriptomics uncovers EGFR signaling-mediated gastric progenitor cell differentiation in stomach homeostasis

Defects in gastric progenitor cell differentiation are associated with various gastric disorders, including atrophic gastritis, intestinal metaplasia, and gastric cancer. However, the mechanisms underlying the multilineage differentiation of gastric progenitor cells during healthy homeostasis remain poorly understood. Here, using a single-cell RNA sequencing method, Quartz-Seq2, we analyzed the gene expression dynamics of progenitor cell differentiation toward pit cell, neck cell, and parietal cell lineages in healthy adult mouse corpus tissues. Enrichment analysis of pseudotime-dependent genes and a gastric organoid assay revealed that EGFR-ERK signaling promotes pit cell differentiation, whereas NF-κB signaling maintains gastric progenitor cells in an undifferentiated state. In addition, pharmacological inhibition of EGFR in vivo resulted in a decreased number of pit cells. Although activation of EGFR signaling in gastric progenitor cells has been suggested as one of the major inducers of gastric cancers, our findings unexpectedly identified that EGFR signaling exerts a differentiation-promoting function, not a mitogenic function, in normal gastric homeostasis.

IL-1β, an important cytokine affecting Helicobacter pylori-mediated gastric carcinogenesis

Infection with Helicobacter pylori (H. pylori) is prevalent around the world and responsible for gastric cancer (GC). The development of GC from gastritis is closely associated with the bacterial virulence and the body's immune response ability. In this process, interleukin-1β (IL-1β) plays an important role. Under H. pylori infection, IL-1β is highly expressed that result in gastric acid inhibition, GC-related gene methylations and disfunctions, angiogenesis. Nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome mediates IL-1β maturation in cells such as macrophages, neutrophils and dendritic cells. But how does IL-1β get released across the cell membrane still unclear. In this review, we focus on the secretion mechanism of IL-1β across the membrane, and to explore the role of IL-1β in the progression of GC.

Landscape of Druggable Molecular Pathways Downstream of Genomic CDH1/Cadherin-1 Alterations in Gastric Cancer

Loss of CDH1/Cadherin-1 is a common step towards the acquisition of an abnormal epithelial phenotype. In gastric cancer (GC), mutation and/or downregulation of CDH1/Cadherin-1 is recurrent in sporadic and hereditary diffuse GC type. To approach the molecular events downstream of CDH1/Cadherin-1 alterations and their relevance in gastric carcinogenesis, we queried public databases for genetic and DNA methylation data in search of molecular signatures with a still-uncertain role in the pathological mechanism of GC. In all GC subtypes, modulated genes correlating with CDH1/Cadherin-1 aberrations are associated with stem cell and epithelial-to-mesenchymal transition pathways. A higher level of genes upregulated in CDH1-mutated GC cases is associated with reduced overall survival. In the diffuse GC (DGC) subtype, genes downregulated in CDH1-mutated compared to cases with wild type CDH1/Cadherin-1 resulted in being strongly intertwined with the DREAM complex. The inverse correlation between hypermethylated CpGs and CDH1/Cadherin-1 transcription in diverse subtypes implies a common epigenetic program. We identified nonredundant protein-encoding isoforms of 22 genes among those differentially expressed in GC compared to normal stomach. These unique proteins represent potential agents involved in cell transformation and candidate therapeutic targets. Meanwhile, drug-induced and CDH1/Cadherin-1 mutation-related gene expression comparison predicts FIT, GR-127935 hydrochloride, amiodarone hydrochloride in GC and BRD-K55722623, BRD-K13169950, and AY 9944 in DGC as the most effective treatments, providing cues for the design of combined pharmacological treatments. By integrating genetic and epigenetic aspects with their expected functional outcome, we unveiled promising targets for combinatorial pharmacological treatments of GC.

IFNγ-dependent silencing of TFF1 during Helicobacter pylori infection

Chronic Helicobacter pylori infection is the leading cause of intestinal-type adenocarcinoma, as prolonged Helicobacter colonization triggers chronic active gastritis, which may evolve into adenocarcinoma of the intestinal type. In this environment, cytokines play a significant role in determining the evolution of the infection. In combination with other factors (genetic, environmental and nutritional), the pro-inflammatory response may trigger pro-oncogenic mechanisms that lead to the silencing of tumour-suppressor genes, such as trefoil factor 1 (TFF1). The latter is known to play a protective role by maintaining the gastric mucosa integrity and retaining H. pylori in the mucus layer, preventing the progression of infection and, consequently, the development of gastric cancer (GC). Since TFF1 expression is reduced during chronic Helicobacter infection with a loss of gastric mucosa protection, we investigated the molecular pathways involved in this reduction. Specifically, we evaluated the effect of some pro-inflammatory cytokines on TFF1 regulation in GC and primary gastric cells by RT-qPCR and luciferase reporter assay analyses and the repressor role of the transcription factor C/EBPβ, overexpressed in gastric-intestinal cancer. Our results show that, among several cytokines, IFNγ stimulates C/EBPβ expression, which acts as a negative regulator of TFF1 by binding its promoter at three different sites.

A DCS-related lncRNA signature predicts the prognosis and chemotherapeutic response of patients with gastric cancer

The combination of docetaxel, cisplatin, and S-1 (DCS) is a common chemotherapy regimen for patients with gastric cancer (GC). However, studies on long noncoding RNAs (lncRNAs) associated with the chemotherapeutic response to and prognosis after DCS remain lacking. The aim of the present study was to identify DCS mRNAs-lncRNAs associated with chemotherapy response and prognosis in GC patients. In the present study, we identified 548 lncRNAs associated with these 16 mRNAs in the TCGA and GSE31811 datasets. Eleven lncRNAs were used to construct a prognostic signature by least absolute shrinkage and selection operator (LASSO) regression. A model including the 11 lncRNAs (LINC02532, AC007277.1, AC005324.4, AL512506.1, AC068790.7, AC022509.2, AC113139.1, LINC00106, AC005165.1, MIR100HG, and UBE2R2-AS1) associated with the prognosis of GC was constructed. The signature was validated in the TCGA database, model comparison, and qRT-PCR experiments. The results showed that the risk signature was a more effective prognostic factor for GC patients. Furthermore, the results showed that this model can well predicting chemotherapy drug response and immune infiltration of GC patients. In addition, our experimental results indicated that lower expression levels of LINC00106 and UBE2R2-AS1 predicted worse drug resistance in AGS/DDP cells. The experimental results agreed with the predictions. Furthermore, knockdown of LINC00106 or UBE2R2-AS1 can significantly enhanced the proliferation and migration of GC AGS cells in vitro. In conclusion, a novel DCS therapy-related lncRNA signature may become a new strategy to predict chemotherapy response and prognosis in GC patients. LINC00106 and UBE2R2-AS1 may exhibit a tumor suppressive function in GC.

RUNX1T1 function in cell fate

RUNX1T1 (Runt-related transcription factor 1, translocated to 1), a myeloid translocation gene (MTG) family member, is usually investigated as part of the fusion protein RUNX1-RUNX1T1 for its role in acute myeloid leukemia. In the main, by recruiting histone deacetylases, RUNX1T1 negatively influences transcription, enabling it to regulate the proliferation and differentiation of hematopoietic progenitors. Moreover, the formation of blood vessels, neuronal differentiation, microglial activation following injury, and intestinal development all relate closely to the expression of RUNX1T1. Furthermore, through alternative splicing of RUNX1T1, short and long isoforms have been noted to mediate adipogenesis by balancing the differentiation and proliferation of adipocytes. In addition, RUNX1T1 plays wide-ranging and diverse roles in carcinoma as a biomarker, suppressor, or positive regulator of carcinogenesis, closely correlated to specific organs and dominant signaling pathways. The aim of this work was to investigate the structure of RUNX1T1, which contains four conserved nervy homolog domains, and to demonstrate crosstalk with the Notch signaling pathway. Moreover, we endeavored to illustrate the effects of RUNX1T1 on cell fate from multiple aspects, including its influence on hematopoiesis, neuronal differentiation, microglial activation, intestinal development, adipogenesis, angiogenesis, and carcinogenesis.

MiR-210-3p accelerates tumor-relevant cell functions of endometrial carcinoma by repressing RUNX1T1

BACKGROUND

Biological mechanism of miR-210-3p in endometrial carcinoma (EC) remains unclear. Here, our purpose is to study effects of miR-210-3p on malignant progression of EC.

METHODS

Bioinformatics analysis showed miRNA and mRNA are abnormally expressed in EC tissues. Quantitative real-time fluorescence polymerase chain reaction (qRT-PCR) was utilized to compare miR-210-3p mRNA level in EC cells and tissues. qRT-PCR and western blot were used to measure RUNX1T1 and NCAM1 at mRNA and protein levels, and western blot for p-AKT and AKT proteins related to PI3K/AKT signaling pathway. Furthermore, EC cell behaviors were assayed via Cell Counting Kit-8, cell colony formation assay, wound healing, transwell and flow cytometry experiments. Interaction between RUNX1T1 and miR-210-3p was verified through dual-luciferase assay. Immunohistochemistry was used to analyze RUNX1T1 expression in clinical samples RESULTS: MiR-210-3p was considerably upregulated and RUNX1T1 was significantly under-expressed in EC. Overexpression of miR-210-3p stimulated cell proliferation, migration, invasion, and restrained cell apoptosis in EC. Dual-luciferase assay proved that RUNX1T1 was a target gene of miR-210-3p. The level of RUNX1T1 in EC was downregulated after overexpressing miR-210-3p. Rescue assay showed that overexpression of RUNX1T1 had an inhibitory impact on tumor-relevant cell behaviors, whereas overexpression of miR-210-3p rescued such inhibition. Overexpression of RUNX1T1 reduced p-AKT expression, which was restored with concomitantly overexpressed miR-210-3p.

CONCLUSION

In general, miR-210-3p behaves as an oncogene in EC by down-regulating the expression of RUNX1T1. This study elucidates a new functional mechanism in EC, and indicates miR-210-3p an underlying target.

Molecular Mechanisms and Potential Rationale of Immunotherapy in Peritoneal Metastasis of Advanced Gastric Cancer

Peritoneal metastasis (PM) is one of the most frequent metastasis patterns of gastric cancer (GC), and the prognosis of patients with PM is very dismal. According to Paget’s theory, disseminated free cancer cells are seeded and survive in the abdominal cavity, adhere to the peritoneum, invade the subperitoneal tissue, and proliferate through angiogenesis. In these sequential processes, several key molecules are involved. From a therapeutic point of view, immunotherapy with chemotherapy combination has become the standard of care for advanced GC. Several clinical trials of newer immunotherapy agents are ongoing. Understanding of the molecular process of PM and the potential rationale of immunotherapy for PM treatment is necessary. Beyond understanding of the molecular aspect of PM, many studies have been conducted on the modality of treatment of PM. Notably, intraperitoneal approaches, including chemotherapy or immunotherapy, have been conducted, because systemic treatment of PM has limitations. In this study, we reviewed the molecular mechanisms and immunologic aspects of PM, and intraperitoneal approaches under investigation for treating PM.

Stress-induced epinephrine promotes epithelial-to-mesenchymal transition and stemness of CRC through the CEBPB/TRIM2/P53 axis

Background

Previous studies have indicated that chronic emotional stressors likely participate in the occurrence of cancers. However, direct evidence connecting stress and colorectal cancer development remains almost completely unexplored.

Methods

Chronic stress mouse model was used to investigate the influence of stress on tumorigenesis. Several major agonists and antagonists of adrenergic receptors were applied to investigate the effects of β-adrenergic signaling on the development of CRC. Chromatin immunoprecipitation assays (CHIP) were used to investigate the binding of p53 and CEBPB to TRIM2 promoter. Mammosphere cultures, Cell Counting Kit-8 (CCK-8) assay, colony-formation assay, scratch wound healing assays, qPCR, immunofluorescence, coimmunoprecipitation and western blotting were used to explore the effect of stress-induced epinephrine on the CEBPB/TRIM2/P53 axis and the progress of CRC cells.

Results

In this study, we found that stress-induced epinephrine (EPI) promotes the proliferation, metastasis and CSC generation of CRC primarily through the β2-adrenergic receptor. Furthermore, our studies also confirmed that chronic stress decreased the stability of p53 protein by promoting p53 ubiquitination. Results of transcriptome sequencing indicated that TRIM2 was overexpressed in cells treated with EPI. Further studies indicated that TRIM2 could regulate the stability of p53 protein by promoting p53 ubiquitination. Finally, we further proved that CEBPB was regulated by EPI and acts as the upstream transcription factor of TRIM2.

Conclusions

Our studies proved that stress-induced EPI promotes the development and stemness of CRC through the CEBPB/TRIM2/P53 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03467-8.

Natural Products with Antitumor Potential Targeting the MYB-C/EBPβ-p300 Transcription Module

The transcription factor MYB is expressed predominantly in hematopoietic progenitor cells, where it plays an essential role in the development of most lineages of the hematopoietic system. In the myeloid lineage, MYB is known to cooperate with members of the CCAAT box/enhancer binding protein (C/EBP) family of transcription factors. MYB and C/EBPs interact with the co-activator p300 or its paralog CREB-binding protein (CBP), to form a transcriptional module involved in myeloid-specific gene expression. Recent work has demonstrated that MYB is involved in the development of human leukemia, especially in acute T-cell leukemia (T-ALL) and acute myeloid leukemia (AML). Chemical entities that inhibit the transcriptional activity of the MYB-C/EBPβ-p300 transcription module may therefore be of use as potential anti-tumour drugs. In searching for small molecule inhibitors, studies from our group over the last 10 years have identified natural products belonging to different structural classes, including various sesquiterpene lactones, a steroid lactone, quinone methide triterpenes and naphthoquinones that interfere with the activity of this transcriptional module in different ways. This review gives a comprehensive overview on the various classes of inhibitors and the inhibitory mechanisms by which they affect the MYB-C/EBPβ-p300 transcriptional module as a potential anti-tumor target. We also focus on the current knowledge on structure-activity relationships underlying these biological effects and on the potential of these compounds for further development.

Clinical potential of long non-coding RNA LINC01133 as a promising biomarker and therapeutic target in cancers

Recently, long intergenic non-protein coding RNA 01133 (LINC01133) was identified as a novel transcript in cancers. It modulates various hallmarks of cancers and acts as oncogenic in some cancers while tumor-suppressive in others. Furthermore, the expression of LINC01133 correlates with tumor size, advanced tumor node metastasis stage and lymphatic node metastasis, Ki-67 levels and overall survival of patients. Herein, the authors provide an in-depth analysis describing how LINC01133 modulates the multiple cancer-associated signaling pathways and the pathogenesis of various malignancies and treatment regimens. Based on the role played by LINC01133, the authors propose LINC01133 as both a potential biomarker and a therapeutic target in cancer.

Metformin inhibits human non-small cell lung cancer by regulating AMPK-CEBPB-PDL1 signaling pathway

Metformin has been found to have inhibitory effects on a variety of tumors. However, its effects on non-small cell lung cancer (NSCLC) remain unclear. We demonstrated that metformin could inhibit the proliferation of A549 and H1299 cells. RNA transcriptome sequencing revealed that PDL1 was significantly downregulated in both cell types following treatment with metformin (P < 0.001). Jaspar analysis and chromatin immunoprecipitation showed that CEBPB could directly bind the promoter region of PDL1. Western blotting showed that protein expression of the isoforms CEBPB-LAP*, CEBPB-LAP, and CEBPB-LIP was significantly upregulated and the LIP/LAP ratio was increased. Gene chip analysis showed that PDL1 was significantly upregulated in A549-CEBPB-LAP cells and significantly downregulated in A549-CEBPB-LIP cells (P < 0.05) compared with CEBPB-NC cells. Dual-luciferase reporter gene assay showed that CEBPB-LAP overexpression could promote transcription of PDL1 and CEBPB-LIP overexpression could inhibit the process. Functional assays showed that the changes in CEBPB isoforms affected the function of NSCLC cells. Western blotting showed that metformin could regulate the function of NSCLC cells via AMPK-CEBPB-PDL1 signaling. Animal experiments showed that tumor growth was significantly inhibited by metformin, and atezolizumab and metformin had a synergistic effect on tumor growth. A total of 1247 patients were retrospectively analyzed, including 166 and 1081 patients in metformin and control groups, respectively. The positive rate of PDL1 was lower than that of the control group (HR = 0.338, 95% CI = 0.235-0.487; P < 0.001). In conclusion, metformin inhibited the proliferation of NSCLC cells and played an anti-tumor role in an AMPK-CEBPB-PDL1 signaling-dependent manner.

Non-classical role of Galectin-3 in cancer progression: translocation to nucleus by carbohydrate-recognition independent manner

Galectin-3 is a carbohydrate-binding protein and regulates diverse functions, including cell proliferation and differentiation, mRNA splicing, apoptosis induction, immune surveillance and inflammation, cell adhesion, angiogenesis, and cancer-cell metastasis. Galectin-3 is also recommended as a diagnostic or prognostic biomarker of various diseases, including heart disease, kidney disease, and cancer. Galectin-3 exists as a cytosol, is secreted in extracellular spaces on cells, and is also detected in nuclei. It has been found that galectin-3 has different functions in cellular localization: (i) Extracellular galectin-3 mediates cell attachment and detachment. (ii) cytosolic galectin-3 regulates cell survival by blocking the intrinsic apoptotic pathway, and (iii) nuclear galectin-3 supports the ability of the transcriptional factor for target gene expression. In this review, we focused on the role of galectin-3 on translocation from cytosol to nucleus, because it happens in a way independent of carbohydrate recognition and accelerates cancer progression. We also suggested here that intracellular galecin-3 could be a potent therapeutic target in cancer therapy. [BMB Reports 2020; 53(4): 173-180].

Odyssey of trefoil factors in cancer: Diagnostic and therapeutic implications

Trefoil factors 1, 2, and 3 (TFFs) are a family of small secretory molecules involved in the protection and repair of the gastrointestinal tract (GI). TFFs maintain and restore epithelial structural integrity via transducing key signaling pathways for epithelial cell migration, proliferation, and invasion. In recent years, TFFs have emerged as key players in the pathogenesis of multiple diseases, especially cancer. Initially recognized as tumor suppressors, emerging evidence demonstrates their key role in tumor progression and metastasis, extending their actions beyond protection. However, to date, a comprehensive understanding of TFFs' mechanism of action in tumor initiation, progression and metastasis remains obscure. The present review discusses the structural, functional and mechanistic implications of all three TFF family members in tumor progression and metastasis. Also, we have garnered information from studies on their structure and expression status in different organs, along with lessons from their specific knockout in mouse models. In addition, we highlight the emerging potential of using TFFs as a biomarker to stratify tumors for better therapeutic intervention.

Galectin-3 Interacts with C/EBPβ and Upregulates Hyaluronan-Mediated Motility Receptor Expression in Gastric Cancer

The hyaluronan-mediated motility receptor (HMMR) is overexpressed in gastric cancer; however, the apparent role of HMMR has not been well defined owing to lack of detailed studies on gastric tumorigenesis. Therefore, we elucidated the functional and regulatory mechanisms of HMMR in gastric cancer. Using publicly available data, we confirmed HMMR overexpression in patients with gastric cancer. HMMR silencing decreased proliferation, migration, and invasion of gastric cancer cells, whereas HMMR overexpression reversed these effects. A gastric cancer xenograft mouse model showed statistically significant inhibition of tumor growth upon HMMR depletion. Previous data from cDNA microarray showed reduced HMMR expression upon inhibition of galectin-3. However, overexpression of galectin-3 increased HMMR expression, cell proliferation, and motility in gastric cancer cells, whereas HMMR silencing blocked these effects. Interestingly, galectin-3 interacted directly with C/EBPβ and bound to HMMR promoter to drive its transcription, and gastric cancer cell proliferation and motility. Altogether, high expression of HMMR promoted gastric cancer cell proliferation and motility and could be a prognostic factor in gastric cancer. In addition, HMMR expression was regulated by the interaction between C/EBPβ and galectin-3. Therefore, targeting HMMR along with galectin-3 and C/EBPβ complex could be a potential treatment strategy for inhibiting gastric cancer progression and metastasis. IMPLICATIONS: This study provides evidence that galectin-3 interacts with C/EBPβ in gastric cancer, and galectin-3 and C/EBPβ complex promotes gastric cancer cell progression and motility through upregulating HMMR expression.

TNIP1 Inhibits Proliferation And Promotes Apoptosis In Clear Cell Renal Carcinoma Through Targeting C/Ebpβ

Background/Purpose

TNF-α-induced protein 3-interacting protein 1 (TNIP1) is active in various cancers, but its expression and function in renal cell carcinoma (RCC) have not been described. This study investigated the role of TNIP1 in clear cell renal cell carcinomas (ccRCC), which accounts for 75–80% of RCC and has a poor prognosis.

Methods

The expression of TNIP1 in human ccRCC tissues and cells was detected by real-time quantitative reverse transcription–polymerase chain reaction (qRT-PCR), Western blot (WB), and immunohistochemical (IHC) staining. Cell proliferation was assayed by a cell counting kit (CCK)-8 assay; cell cycle analysis and apoptosis assay were done by flow cytometry.

Results

TNIP1 is downregulated in both ccRCC human tissues and cells. Besides, TNIP1 downregulation promoted cell proliferation with more cell cycle entry, and inhibited apoptosis. TNIP1 downregulation was associated with increased of expression of the Bcl-2 anti-apoptosis gene and decreased expression of the Bax apoptosis-promoting gene and cleaved-caspase-3 by negatively regulating C/EBPβ expression.

Conclusion

TNIP1 acted as a tumor-inhibitor in ccRCC by targeting C/EBPβ. The results warrant study of TNIP1 as a potential diagnostic marker and therapeutic target of ccRCC.

C/EBPβ Is a Transcriptional Regulator of Wee1 at the G₂/M Phase of the Cell Cycle

The CCAAT/enhancer-binding protein β (C/EBPβ) is a transcription factor that regulates cellular proliferation, differentiation, apoptosis and tumorigenesis. Although the pro-oncogenic roles of C/EBPβ have been implicated in various human cancers, how it contributes to tumorigenesis or tumor progression has not been determined. Immunohistochemistry with human non-small cell lung cancer (NSCLC) tissues revealed that higher levels of C/EBPβ protein were expressed compared to normal lung tissues. Knockdown of C/EBPβ by siRNA reduced the proliferative capacity of NSCLC cells by delaying the G₂/M transition in the cell cycle. In C/EBPβ-knockdown cells, a prolonged increase in phosphorylation of cyclin dependent kinase 1 at tyrosine 15 (Y15-pCDK1) was displayed with simultaneously increased Wee1 and decreased Cdc25B expression. Chromatin immunoprecipitation (ChIP) analysis showed that C/EBPβ bound to distal promoter regions of WEE1 and repressed WEE1 transcription through its interaction with histone deacetylase 2. Treatment of C/EBPβ-knockdown cells with a Wee1 inhibitor induced a decrease in Y15-pCDK1 and recovered cells from G₂/M arrest. In the xenograft tumors, the depletion of C/EBPβ significantly reduced tumor growth. Taken together, these results indicate that Wee1 is a novel transcription target of C/EBPβ that is required for the G₂/M phase of cell cycle progression, ultimately regulating proliferation of NSCLC cells.

A novel cell-based screening assay for small-molecule MYB inhibitors identifies podophyllotoxins teniposide and etoposide as inhibitors of MYB activity

The transcription factor MYB plays key roles in hematopoietic cells and has been implicated the development of leukemia. MYB has therefore emerged as an attractive target for drug development. Recent work has suggested that targeting MYB by small-molecule inhibitors is feasible and that inhibition of MYB has potential as a therapeutic approach against acute myeloid leukemia. To facilitate the identification of small-molecule MYB inhibitors we have re-designed and improved a previously established cell-based screening assay and have employed it to screen a natural product library for potential inhibitors. Our work shows that teniposide and etoposide, chemotherapeutic agents causing DNA-damage by inhibiting topoisomerase II, potently inhibit MYB activity and induce degradation of MYB in AML cell lines. MYB inhibition is suppressed by caffeine, suggesting that MYB is inhibited indirectly via DNA-damage signalling. Importantly, ectopic expression of an activated version of MYB in pro-myelocytic NB4 cells diminished the anti-proliferative effects of teniposide, suggesting that podophyllotoxins disrupt the proliferation of leukemia cells not simply by inducing general DNA-damage but that their anti-proliferative effects are boosted by inhibition of MYB. Teniposide and etoposide therefore act like double-edged swords that might be particularly effective to inhibit tumor cells with deregulated MYB.

The natural anti-tumor compound Celastrol targets a Myb-C/EBPβ-p300 transcriptional module implicated in myeloid gene expression

Myb is a key regulator of hematopoietic progenitor cell proliferation and differentiation and has emerged as a potential target for the treatment of acute leukemia. Using a myeloid cell line with a stably integrated Myb-inducible reporter gene as a screening tool we have previously identified Celastrol, a natural compound with anti-tumor activity, as a potent Myb inhibitor that disrupts the interaction of Myb with the co-activator p300. We showed that Celastrol inhibits the proliferation of acute myeloid leukemia (AML) cells and prolongs the survival of mice in an in vivo model of AML, demonstrating that targeting Myb with a small-molecule inhibitor is feasible and might have potential as a therapeutic approach against AML. Recently we became aware that the reporter system used for Myb inhibitor screening also responds to inhibition of C/EBPβ, a transcription factor known to cooperate with Myb in myeloid cells. By re-investigating the inhibitory potential of Celastrol we have found that Celastrol also strongly inhibits the activity of C/EBPβ by disrupting its interaction with the Taz2 domain of p300. Together with previous studies our work reveals that Celastrol independently targets Myb and C/EBPβ by disrupting the interaction of both transcription factors with p300. Myb, C/EBPβ and p300 cooperate in myeloid-specific gene expression and, as shown recently, are associated with so-called super-enhancers in AML cells that have been implicated in the maintenance of the leukemia. We hypothesize that the ability of Celastrol to disrupt the activity of a transcriptional Myb-C/EBPβ-p300 module might explain its promising anti-leukemic activity.