Tribbles Pseudokinase 3 Contributes to Cancer Stemness of Endometrial Cancer Cells by Regulating β-Catenin Expression

The Lyn/RUVBL1 Complex Promotes Colorectal Cancer Liver Metastasis by Regulating Arachidonic Acid Metabolism Through Chromatin Remodeling

Liver metastasis is a common cause of death in colorectal cancer (CRC) patients, but epigenetic remodeling and metabolic reprogramming for CRC liver metastasis remain unclear. The study revealed that the Lyn/RUVBL1 complex is highly expressed in CRC and is closely correlated with liver metastasis. On the one hand, ATAC-seq and HiCut suggested that Lyn/RUVBL1 regulates the expression of TRIB3 through the POL II-mediated chromatin conformation of TRIB3 and thus the expression of β-catenin. This promotes the proliferation and migration of CRC through β-catenin-mediated upregulation of MMP9 and VEGF. On the other hand, metabolomics revealed that Lyn/RUVBL1 regulates the expression of PGE2 through the enzyme COX2, thereby promoting arachidonic acid (AA) metabolism. CUT-Tag showed that Lyn/RUVBL1 silencing reduces the H3K27ac level in the COX2 promoter. Then, it is found that COX2 is regulated by the transcription factor FOXA1. Lyn/RUVBL1 modulates AA metabolism by regulating the chromatin accessibility of FOXA1. AA metabolism promotes the metastasis of CRC by affecting β-catenin nuclear translocation and upregulating MMP9 and VEGF. These findings suggest that the Lyn/RUVBL1 complex mediates epigenetic remodeling to regulate the metabolic reprogramming of AA, highlighting its role in promoting the metastasis of CRC.

Ovatodiolide inhibits endometrial cancer stemness via reactive oxygen species-mediated DNA damage and cell cycle arrest

Endometrial cancer (EC) is a common gynecological cancer worldwide, often associated with a poor prognosis after recurrence or metastasis. Ovatodiolide (OVA) is a macrocyclic diterpenoid derived from Anisomeles indica that shows anticancer effects in various malignancies. This study aimed to evaluate the cytotoxic effects of OVA on EC cell proliferation and cancer stem cell (CSC) activity and explore its underlying molecular mechanisms. OVA treatment dose-dependently reduced the viability and colony formation of three EC cell lines (AN3CA, HEC-1A, and EMC6). It induced G2/M phase cell cycle arrest, associated with decreased cell division cycle 25C (CDC25C) expression and reduced activation of cyclin-dependent kinases 1 (CDK1) and 2 (CDK2). OVA also increased reactive oxygen species (ROS) production and DNA damage, activating the DNA damage-sensitive cell cycle checkpoint kinases 1 (CHK1) and 2 (CHK2) and upregulating the DNA damage marker γ-H2A.X variant histone (H2AX). It also suppressed the activation of mechanistic target of rapamycin kinase (mTOR) and nuclear factor kappa B (NF-κB) and downregulated glutathione peroxidase 1 (GPX1), an antioxidant enzyme counteracting oxidative stress. Moreover, OVA reduced the self-renewal capacity of CSCs, reducing the expression of key stemness proteins Nanog homeobox (NANOG) and octamer-binding transcription factor 4 (OCT4). The ROS inhibitor N-acetylcysteine attenuated the anti-proliferative and anti-CSC effects of OVA. Our findings suggest that OVA acts via ROS generation, leading to oxidative stress and DNA damage, culminating in cell cycle arrest and the suppression of CSC activity in EC. Therefore, OVA is a promising therapeutic agent for EC, either as a standalone treatment or an adjunct to existing therapies.

Diverse functions of Tribbles homolog 3 in cancers and its potential as a therapeutic target

Currently, cancer is the second leading cause of death worldwide, and potential targeted drugs and molecular pathways for cancer development and progression have been a hot research topic worldwide. In recent years, the importance of the kinase superfamily in diseases has been well demonstrated by studies on various molecular mechanisms of kinases and the successful application of their inhibitors in diseases. Pseudokinases are members of the kinase superfamily, which have been increasingly documented to play a crucial role in cancers year after year. As a member of pseudokinases, tribbles homolog 3 (TRIB3) also exerts diverse functions in different cancers through different interacting proteins and molecular pathways, especially in tumor immunity, stemness, drug resistance, metabolism, and autophagy. In addition, peptide drugs targeting TRIB3 have high specificity in preclinical studies, which shows great promise for TRIB3 application in diseases including cancers. In this review, we dissect diverse functions played by TRIB3 in different cancers, describing the underlying mechanisms in detail. Notably, inhibitors and agonists currently available for TRIB3 are discussed, indicating the potential for TRIB3 as a therapeutic target.

Licochalcone A induces endoplasmic reticulum stress-mediated apoptosis of endometrial cancer cells via upregulation of GRP78 expression

Licochalcone A (LicA), a natural compound extracted from licorice root, has been shown to exert a variety of anticancer activities. Whether LicA has such effects on endometrial cancer (EMC) is unclear. This study aims to investigate the antitumor effects of LicA on EMC. Our results show that LicA significantly reduced the viability and induced apoptosis of EMC cells and EMC-7 cells from EMC patients. LicA was also found to induce endoplasmic reticulum (ER) stress, leading to increased expression of ER-related proteins (GRP78/PERK/IRE1α/CHOP) in EMC cell lines. Suppression of GRP78 expression in human EMC cells treated with LicA significantly attenuated the effects of LicA, resulting in reduced ER-stress mediated cell apoptosis and decreased expression of ER- and apoptosis-related proteins. Our findings demonstrate that LicA induces apoptosis in EMC cells through the GRP78-mediated ER-stress pathway, emphasizing the potential of LicA as an anticancer therapy for EMC.

Identification of the role of endoplasmic reticulum stress genes in endometrial cancer and their association with tumor immunity

BACKGROUND

Endometrial cancer (EC) is one of the worldwide gynecological malignancies. Endoplasmic reticulum (ER) stress is the cellular homeostasis disturbance that participates in cancer progression. However, the mechanisms of ER Stress on EC have not been fully elucidated.

METHOD

The ER Stress-related genes were obtained from Gene Set Enrichment Analysis (GSEA) and GeneCards, and the RNA-seq and clinical data were downloaded from The Cancer Genome Atlas (TCGA). The risk signature was constructed by the Cox regression and the least absolute shrinkage and selection operator (LASSO) analysis. The significance of the risk signature and clinical factors were tested by time-dependent receiver operating characteristic (ROC) curves, and the selected were to build a nomogram. The immunity correlation was particularly analyzed, including the related immune cells, pathways, and immune checkpoints. Functional enrichment, potential chemotherapies, and in vitro validation were also conducted.

RESULT

An ER Stress-based risk signature, consisting of TRIB3, CREB3L3, XBP1, and PPP1R15A was established. Patients were randomly divided into training and testing groups with 1:1 ratio for subsequent calculation and validation. Based on risk scores, high- and low-risk subgroups were classified, and low-risk subgroup demonstrated better prognosis. The Area Under Curve (AUC) demonstrated a reliable predictive capability of the risk signature. The majority of significantly different immune cells and pathways were enriched more in low-risk subgroup. Similarly, several typical immune checkpoints, expressed higher in low-risk subgroup. Patients of the two subgroups responded differently to chemotherapies.

CONCLUSION

We established an ER Stress-based risk signature that could effectively predict EC patients' prognosis and their immune correlation.

Comprehensive analysis of E47‑like factors and verification of ELF4 in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most prominent subtype of renal cancer and E47-like factors (ELFs) are important in tumorigenesis; however, the specific role of key ELFs in ccRCC remains unclear. The present study comprehensively analyzed RNA sequencing and clinical data from multiple databases, and identified differentially expressed ELFs (ELF3-5) in ccRCC. The DNA promoter methylation, genetic variation and clinical significance of ELF3-5 in ccRCC were analyzed using the cBioPortal and UALCAN databases. The association between ELF3-5 and multiple immune cell infiltration was analyzed using Tumor Immune Estimation Resource. Subsequently, ELF4 was selected and its association with biological functions was assessed. Cell counting kit-8 (CCK-8), colony formation, Transwell, macrophage chemotaxis and polarization assays were conducted to validate the functions of ELF4. Notably, the mRNA expression levels of ELF4 were significantly upregulated in ccRCC, whereas ELF3 and ELF5 mRNA expression levels were significantly downregulated. Clinical significance analysis revealed that ELF4 showed a high clinical significance with tumor grade, clear cell type A and B subtypes, and incidence rates of amplification in genetic variation. Further analyses indicated that ELF4 may be involved in multiple immune cell differentiation. Additionally, cell experiments revealed that ELF4 inhibition downregulated 769-P and 786-O proliferation, migration and invasion. Knockdown of ELF4 in cancer cells also inhibited M2 macrophage polarization and chemotaxis towards 769-P and 786-O cells. Conclusively, the present findings indicated the clinical significance of ELF4 in ccRCC, and verified its key role in driving cell proliferation, migration and invasion, and promoting M2 macrophage polarization and chemotaxis in ccRCC.

Pseudokinases, Tribbles Proteins and Cancer

The human kinome comprises 518 protein kinases, of which approximately 10% lack one or more of the conserved amino acids necessary for catalytic activity [...].

Novel insights into tumorigenesis and prognosis of endometrial cancer through systematic investigation and validation on mitophagy-related signature

In-depth studies on the pathogenesis of endometrial cancer (EC) are critical because of the increasing global incidence of EC. Mitophagy, a mitochondrial quality control process, plays an important role in carcinogenesis and tumor progression. This study aimed to develop a novel mitophagy-based signature to predict the tumorigenesis and prognosis of EC. Data was downloaded from The Cancer Genome Atlas and Gene Expression Omnibus databases, and 29 mitophagy-related genes were downloaded from the Pathway Unification Database. EC patients were classified into two risk groups based on the two-key- gene signature, TOMM40 and MFN1, which were constructed using Cox regression analysis. A better prognosis was noted in the low-risk group. The model was validated for four aspects: clinical features, mutation status, clinical therapeutic response, and immune cell infiltration status. Moreover, according to the contribution to the risk model, TOMM40 was selected for further in vitro experiments. The silencing of TOMM40 inhibited mitochondrial degradation; suppressed cell proliferation; induced cell apoptosis and G1 phase cell cycle arrest; inhibited migration, invasion, and epithelial-mesenchymal transition; and suppressed cell stemness. In conclusion, the mitophagy-related risk score provides a novel perspective for survival and drug selection during the individual treatment of EC patients. TOMM40 serves as an oncogene in EC and promotes tumor progression via a mitophagy-related pathway. Thus, TOMM40 is a potential therapeutic target in EC.

FGF19-mediated ELF4 overexpression promotes colorectal cancer metastasis through transactivating FGFR4 and SRC

Background: Metastasis accounts for the high lethality of colorectal cancer (CRC) patients. Unfortunately, the molecular mechanism manipulating metastasis in CRC is still elusive. Here, we investigated the function of E74-like factor 4 (ELF4), an ETS family member, in facilitating CRC progression. Methods: The expression of ELF4 in human CRC samples and CRC cell lines was determined by quantitative real-time PCR, immunohistochemistry and immunoblotting. The migratory and invasive phenotypes of CRC cells were evaluated by in vitro transwell assays and in vivo metastatic models. The RNA sequencing was used to explore the downstream targets of ELF4. The luciferase reporter assays and chromatin immunoprecipitation assays were used to ascertain the transcriptional regulation related to ELF4. Results: We found elevated ELF4 was positively correlated with distant metastasis, advanced AJCC stages, and dismal outcomes in CRC patients. ELF4 expression was also an independent predictor of poor prognosis. Overexpression of ELF4 boosted CRC metastasis via transactivating its downstream target genes, fibroblast growth factor receptor 4 (FGFR4) and SRC proto-oncogene, non-receptor tyrosine kinase, SRC. Fibroblast growth factor 19 (FGF19) upregulated ELF4 expression through the ERK1/2/SP1 axis. Clinically, ELF4 expression had a positive correlation with FGF19, FGFR4 and SRC, and CRC patients who positively coexpressed FGF19/ELF4, ELF4/FGFR4, or ELF4/SRC exhibited the worst clinical outcomes. Furthermore, the combination of the FGFR4 inhibitor BLU-554 and the SRC inhibitor KX2-391 dramatically suppressed ELF4-mediated CRC metastasis. Conclusions: We demonstrated the essentiality of ELF4 in the metastatic process of CRC, and targeting the ELF4-relevant positive feedback circuit might represent a novel therapeutic strategy.

Disulfiram/Copper Suppresses Cancer Stem Cell Activity in Differentiated Thyroid Cancer Cells by Inhibiting BMI1 Expression

Differentiated thyroid carcinomas (DTCs), which have papillary and follicular types, are common endocrine malignancies worldwide. Cancer stem cells (CSCs) are a particular type of cancer cells within bulk tumors involved in cancer initiation, drug resistance, and metastasis. Cells with high intracellular aldehyde hydrogenase (ALDH) activity are a population of CSCs in DTCs. Disulfiram (DSF), an ALDH inhibitor used for the treatment of alcoholism, reportedly targets CSCs in various cancers when combined with copper. This study reported for the first time that DSF/copper can inhibit the proliferation of papillary and follicular DTC lines. DSF/copper suppressed thyrosphere formation, indicating the inhibition of CSC activity. Molecular mechanisms of DSF/copper involved downregulating the expression of B lymphoma Mo-MLV insertion region 1 homolog (BMI1) and cell cycle-related proteins, including cyclin B2, cyclin-dependent kinase (CDK) 2, and CDK4, in a dose-dependent manner. BMI1 overexpression diminished the inhibitory effect of DSF/copper in the thyrosphere formation of DTC cells. BMI1 knockdown by RNA interference in DTC cells also suppressed the self-renewal capability. DSF/copper could inhibit the nuclear localization and transcriptional activity of c-Myc and the binding of E2F1 to the BMI1 promoter. Overexpression of c-Myc or E2F1 further abolished the inhibitory effect of DSF/copper on BMI1 expression, suggesting that the suppression of c-Myc and E2F1 by DSF/copper was involved in the downregulation of BMI1 expression. In conclusion, DSF/copper targets CSCs in DTCs by inhibiting c-Myc- or E2F1-mediated BMI1 expression. Therefore, DSF is a potential therapeutic agent for future therapy in DTCs.

Sorafenib targets and inhibits the oncogenic properties of endometrial cancer stem cells via the RAF/ERK pathway

Background

Distinct subsets of cancer stem cells (CSCs) drive the initiation and progression of malignant tumors via enhanced self-renewal and development of treatment/apoptosis resistance. Endometrial CSC-selective drugs have not been successfully developed because most endometrial cell lines do not contain a sufficient proportion of stable CSCs. Here, we aimed to identify endometrial CSC-containing cell lines and to search for endometrial CSC-selective drugs.

Methods

We first assessed the presence of CSCs by identifying side populations (SPs) in several endometrial cancer cell lines. We then characterized cell viability, colony-formation, transwell invasion and xenotransplantion capability using the isolated SP cells. We also conducted real-time RT-PCR, immunoblot and immunofluorescence analyses of the cells’ expression of CSC-associated markers. Focusing on 14 putative CSC-selective drugs, we characterized their effects on the proliferation and apoptosis of endometrial cancer cell lines, examining cell viability and annexin V staining. We further examined the inhibitory effects of the selected drugs, focusing on proliferation, invasion, expression of CSC-associated markers and tumor formation.

Results

We focused on HHUA cells, an endometrial cancer cell line derived from a well-differentiated endometrial adenocarcinoma. HHUA cells contained a sufficient proportion of stable CSCs with an SP phenotype (HHUA-SP). HHUA-SP showed greater proliferation, colony-formation, and invasive capabilities compared with the main population of HHUA cells (HHUA-MP). HHUA-SP generated larger tumors with higher expression of proliferation-related markers, Ki67, c-MYC and phosphorylated ERK compared with HHUA-MP when transplanted into immunodeficient mice. Among the 14 candidate drugs, sorafenib, an inhibitor of RAF pathways and multiple kinase receptors, inhibited cell proliferation and invasion in both HHUA-SP and -MP, but more profoundly in HHUA-SP. In vivo treatment with sorafenib for 4 weeks reduced the weights of HHUA-SP-derived tumors and decreased the expression of Ki67, ZEB1, and RAF1.

Conclusions

Our results suggest that HHUA is a useful cell line for discovery and identification of endometrial CSC-selective drugs, and that sorafenib may be an effective anti-endometrial cancer drug targeting endometrial CSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02888-y.