Transcriptional factor six2 promotes the competitive endogenous RNA network between CYP4Z1 and pseudogene CYP4Z2P responsible for maintaining the stemness of breast cancer cells

The fatty acid omega hydroxylase genes (CYP4 family) in the progression of metabolic dysfunction-associated steatotic liver disease (MASLD): An RNA sequence database analysis and review

Fatty acid omega hydroxylase P450s consist of enzymes that hydroxylate various chain-length saturated and unsaturated fatty acids (FAs) and bioactive eicosanoid lipids. The human cytochrome P450 gene 4 family (CYP4) consists of 12 members that are associated with several human diseases. However, their role in the progression of metabolic dysfunction-associated fatty liver disease (MASLD) remains largely unknown. It has long been thought that the induction of CYP4 family P450 during fasting and starvation prevents FA-related lipotoxicity through FA metabolism to dicarboxylic acids that are chain-shortened in peroxisomes and then transported to the mitochondria for complete oxidation. Several studies have revealed that peroxisome succinate transported to the mitochondria is used for gluconeogenesis during fasting and starvation, and recent evidence suggests that peroxisome acetate can be utilized for lipogenesis and lipid droplet formation as well as epigenetic modification of gene transcription. In addition, omega hydroxylation of the bioactive eicosanoid arachidonic acid to 20-Hydroxyeicosatetraenoic acid (20-HETE) is essential for activating the GPR75 receptor, leading to vasoconstriction and cell proliferation. Several mouse models of diet-induced MASLD have revealed the induction of selective CYP4A members and the suppression of CYP4F during steatosis and steatohepatitis, suggesting a critical metabolic role in the progression of fatty liver disease. Thus, to further investigate the functional roles of CYP4 genes, we analyzed the differential gene expression of 12 members of CYP4 gene family in datasets from the Gene Expression Omnibus (GEO) from patients with steatosis, steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. We also observed the differential expression of various CYP4 genes in the progression of MASLD, indicating that different CYP4 members may have unique functional roles in the metabolism of specific FAs and eicosanoids at various stages of fatty liver disease. These results suggest that targeting selective members of the CYP4A family is a viable therapeutic approach for treating and managing MASLD.

The SIX2/PFN2 feedback loop promotes the stemness of gastric cancer cells

BACKGROUND

The roles of the transcriptional factor SIX2 have been identified in several tumors. However, its roles in gastric cancer (GC) progression have not yet been revealed. Our objective is to explore the impact and underlying mechanisms of SIX2 on the stemness of GC cells.

METHODS

Lentivirus infection was employed to establish stable expression SIX2 or PFN2 in GC cells. Gain- and loss-of-function experiments were conducted to detect changes of stemness markers, flow cytometry profiles, tumor spheroid formation, and tumor-initiating ability. ChIP, RNA-sequencing, tissue microarray, and bioinformatics analysis were performed to reveal the correlation between SIX2 and PFN2. The mechanisms underlying the SIX2/PFN2 loop-mediated effects were elucidated through tissue microarray analysis, RNA stability assay, IP-MS, Co-Immunoprecipitation, and inhibition of the JNK signaling pathway.

RESULTS

The stemness of GC cells was enhanced by SIX2. Mechanistically, SIX2 directly bound to PFN2's promoter and promoted PFN2 activity. PFN2, in turn, promoted the mRNA stability of SIX2 by recruiting RNA binding protein YBX-1, subsequently activating the downstream MAPK/JNK pathway.

CONCLUSION

This study unveils the roles of SIX2 in governing GC cell stemness, defining a novel SIX2/PFN2 regulatory loop responsible for this regulation. This suggests the potential of targeting the SIX2/PFN2 loop for GC treatment (Graphical Abstracts).

Lipid metabolism dynamics in cancer stem cells: potential targets for cancers

Cancer stem cells (CSCs) represent a small subset of heterogeneous cells within tumors that possess the ability to self-renew and initiate tumorigenesis. They serve as potential drivers for tumor initiation, metastasis, recurrence, and drug resistance. Recent research has demonstrated that the stemness preservation of CSCs is heavily reliant on their unique lipid metabolism alterations, enabling them to maintain their own environmental homeostasis through various mechanisms. The primary objectives involve augmenting intracellular fatty acid (FA) content to bolster energy supply, promoting β-oxidation of FA to optimize energy utilization, and elevating the mevalonate (MVA) pathway for efficient cholesterol synthesis. Additionally, lipid droplets (LDs) can serve as alternative energy sources in the presence of glycolysis blockade in CSCs, thereby safeguarding FA from peroxidation. Furthermore, the interplay between autophagy and lipid metabolism facilitates rapid adaptation of CSCs to the harsh microenvironment induced by chemotherapy. In this review, we comprehensively review recent studies pertaining to lipid metabolism in CSCs and provide a concise overview of the indispensable role played by LDs, FA, cholesterol metabolism, and autophagy in maintaining the stemness of CSCs.

Microglial SIX2 suppresses lipopolysaccharide (LPS)-induced neuroinflammation by up-regulating FXYD2 expression

Parkinson's disease (PD) is a severe neurodegenerative disease associated with the loss of dopaminergic (DA) neurons in the substantia nigra (SN). Although its pathogenesis remains unclear, microglia-mediated neuroinflammation significantly contributes to the development of PD. Here we showed that the sine oculis homeobox (SIX) homologue family transcription factors SIX2 exerted significant effects on neuroinflammation. The SIX2 protein, which is silenced during development, was reactivated in lipopolysaccharide (LPS)-treated microglia. The reactivated SIX2 in microglia mitigated the LPS induced inflammatory effects, and then reduced the toxic effect of conditioned media (CM) of microglia on co-cultured MES23.5 DA cells. Using the LPS-stimulated Cx3cr1-CreERT2 mouse model, we also demonstrated that the highly-expressed SIX2 in microglia obviously attenuated neuroinflammation and protected the DA neurons in SN. Further RNA-Seq analysis on the inflammatory activated microglia revealed that the SIX2 exerted these effects via up-regulating the FXYD domain containing ion transport regulator 2 (FXYD2). Taken together, our study demonstrated that SIX2 was an endogenous anti-inflammatory factor in microglia, and it exerted anti-neuroinflammatory effects by regulating the expression of FXYD2, which provides new ideas for anti-neuroinflammation in PD.

Butyrate attenuates the stemness of lung cancer cells through lysosome Fe2+- and SLC7A11-mediated ferroptosis

Cancer stem cells (CSCs) are considered key contributors to tumor progression, and ferroptosis has been identified as a potential target for CSCs. We have previously shown that butyrate enhances the ferroptosis induced by erastin in lung cancer cell, this study aimed to investigate the impact of butyrate on the progression of lung CSCs. To investigate these effects, we constructed a series of in vitro experiments, including 3D non-adherent sphere-formation, cytometry analysis, assessment of CSC marker expression, cell migration assay, and in vivo tumorigenesis analyses. Additionally, the influence of butyrate on chemotherapeutic sensitivity were determined through both in vitro and in vivo experiments. Mechanistically, immunofluorescence analysis was employed to examine the localization of biotin-conjugated butyrate. We identified that butyrate predominantly localized in the lysosome and concurrently recruited Fe2+ in lysosome. Moreover, butyrate reduced the stability of SLC7A11 protein stability in lung cancer cells through ubiquitination and proteasome degradation. Importantly, the effects of butyrate on lung CSCs were found to be dependent on lysosome Fe2+- and SLC7A11-mediated ferroptosis. In summary, our results demonstrate that butyrate could induce the ferroptosis in lung CSCs by recruiting Fe2+ in lysosome and promoting the ubiquitination-lysosome degradation of SLC7A11 protein.

1-Benzylimidazole attenuates the stemness of breast cancer cells through partially targeting CYP4Z1

Cytochrome P450 (CYP) 4Z1 (CYP4Z1) has recently garnered much interest as its expression predicts a poor prognosis and as a oncogene in breast cancer, and overexpressed in other many cancers. We previously showed that CYP4Z1 acts as a promoter of cancer stem cells (CSCs) to facilitate the occurrence and development of breast cancer. Here, RNA sequencing found that 1-benzylimidazole (1-Benzy) held a preferable correlation with breast cancer and suppressed the expression of CSC makers. Further functional experiments, including mammary spheroid formation, wound-healing, transwell-invasion, detection of tumor initiation, and metastatic ability, showed that 1-Benzy suppressed the stemness and metastasis of breast cancer cells. Additionally, we further demonstrated that CYP4Z1 is necessary for 1-Benzy-mediated suppression on breast cancer stemness and 1-Benzy exerted a weaker effect in breast cancer cells with CYP4Z1 knockdown. Taken together, our data suggest that 1-Benzy might be a potential drug suppressing breast cancer stemness via targeting CYP4Z1.

miR-125 in Breast Cancer Etiopathogenesis: An Emerging Role as a Biomarker in Differential Diagnosis, Regenerative Medicine, and the Challenges of Personalized Medicine

Breast Cancer (BC) is one of the most common cancer types worldwide, and it is characterized by a complex etiopathogenesis, resulting in an equally complex classification of subtypes. MicroRNA (miRNA or miR) are small non-coding RNA molecules that have an essential role in gene expression and are significantly linked to tumor development and angiogenesis in different types of cancer. Recently, complex interactions among coding and non-coding RNA have been elucidated, further shedding light on the complexity of the roles these molecules fulfill in cancer formation. In this context, knowledge about the role of miR in BC has significantly improved, highlighting the deregulation of these molecules as additional factors influencing BC occurrence, development and classification. A considerable number of papers has been published over the past few years regarding the role of miR-125 in human pathology in general and in several types of cancer formation in particular. Interestingly, miR-125 family members have been recently linked to BC formation as well, and complex interactions (competing endogenous RNA networks, or ceRNET) between this molecule and target mRNA have been described. In this review, we summarize the state-of-the-art about research on this topic.

NIK-mediated reactivation of SIX2 enhanced the CSC-like traits of hepatocellular carcinoma cells through suppressing ubiquitin-proteasome system

The critical roles of NF-κB Inducing Kinase (NIK) in tumor progression have been elucidated in various tumors; however, its effects on hepatocellular carcinoma (HCC) progression are still confusing. Here, we found that NIK level was upregulated in HCC tissues compared to that of normal tissues, and positively correlated with the levels of cancer stem cell (CSC) markers. Then we established HCC cells with NIK-stable knockdown and found that NIK knockdown suppressed the CSC-like traits of HCC cells through in vivo and in vitro experiments. Mechanistically, we revealed that SIX2 protein level, but not its mRNA level, was significantly reduced in HCC cells with NIK knockdown, which was rescued by MG132 treatment. Furthermore, NIK knockdown promoted the ubiquitination level of SIX2 and decreased its protein stability. Moreover, Six2 overexpression partially reversed the inhibition of NIK knockdown on the CSC-like traits of HCC cells. This study identified a novel NIK/SIX2 axis conferring HCC stemness.

Targeting Cytochrome P450 Enzymes in Ovarian Cancers: New Approaches to Tumor-Selective Intervention

Over the past decade, there have been significant developments in treatment for ovarian cancer, yet the lack of targeted therapy with few side effects still represents a major issue. The cytochrome P450 (CYP) enzyme family plays a vital role in the tumorigenesis process and metabolism of drugs and has a negative impact on therapy outcomes. Gaining more insight into CYP expression is crucial to understanding the pathophysiology of ovarian cancer since many isoforms are essential to the metabolism of xenobiotics and steroid hormones, which drive the disease's development. To the best of our knowledge, no review articles have documented the intratumoral expression of CYPs and their implications in ovarian cancer. Therefore, the purpose of this review is to provide a clear understanding of differential CYP expression in ovarian cancer and its implications for the prognosis of ovarian cancer patients, together with the effects of CYP polymorphisms on chemotherapy metabolism. Finally, we discuss opportunities to exploit metabolic CYP expression for the development of novel therapeutic methods to treat ovarian cancer.

AZGP1P2/UBA1/RBM15 Cascade Mediates the Fate Determinations of Prostate Cancer Stem Cells and Promotes Therapeutic Effect of Docetaxel in Castration-Resistant Prostate Cancer via TPM1 m6A Modification

Prostate cancer (PCa) is a common malignant tumor with high morbidity and mortality worldwide. The prostate cancer stem cell (PCSC) model provides novel insights into the pathogenesis of PCa and its therapeutic response. However, the roles and molecular mechanisms of specific genes in mediating fate decisions of PCSCs and carcinogenesis of PCa remain to be elusive. In this study, we have explored the expression, function, and mechanism of AZGP1P2, a pseudogene of AZGP1, in regulating the stemness and apoptosis of PCSCs and treatment resistance of docetaxel in castration-resistant prostate cancer (CRPC). We revealed that AZGP1P2 was downregulated in CRPC cell lines and PCSCs, while it was positively associated with progression-free interval. Upregulation of the AZGP1P2 enhanced the sensitivity of docetaxel treatment in CRPCs via inhibiting their stemness. RNA pull-down associated with mass spectrometry analysis, co-immunoprecipitation assay, and RNA immunoprecipitation assay demonstrated that AZGP1P2 could bind to UBA1 and RBM15 as a "writer" of methyltransferase to form a compound. UBA1, an E1 ubiquitin-activating enzyme, contributed to RBM15 protein degradation via ubiquitination modification. Methylated RNA immunoprecipitation assay displayed that RBM15 controlled the mRNA decay of TPM1 in m6A methylation. Furthermore, a xenograft mouse model and patient-derived organoids showed that the therapeutic effect of docetaxel in CRPC was increased by AZGP1P2 in vivo. Collectively, these results imply that AZGP1P2 mediates the stemness and apoptosis of PCSCs and promotes docetaxel therapeutic effect by suppressing tumor growth and metastasis via UBA1/RBM15-mediated TPM1 mRNA decay in CRPC.

A positive TGF-β/miR-9 regulatory loop promotes the expansion and activity of tumour-initiating cells in breast cancer

BACKGROUND AND PURPOSE

MicroRNA-9 (miR-9) has previously been described as a dual-functional RNA during breast cancer progression and its roles need to be clarified thoroughly.

EXPERIMENTAL APPROACH

A miR-9 knockout mode of mouse breast cancer, the MMTV-PyMT model (PyMT-miR-9-/- ), combined with different human breast cancer cell lines were used to evaluate the effects of miR-9 on breast cancer initiation, progression and metastasis. Lin-NECs (Neoplastic mammary epithelial cells) and pNECs (Pre-neoplastic mammary epithelial cells) were isolated and subjected to tumour-initiation assay. Whole-mount staining of mammary gland and histology was performed to determine mammary gland growth. Tumour-initiating analysis combining a series of in vitro experiments were carried out to evaluate miR-9 roles in tumour-initiating ability. RNA-sequencing of human breast cancer cells, and mammary glands at hyperplastic stages and established tumours in PyMT and PyMT-miR-9-/- mice, ChIP and luciferase report assays were conducted to reveal the underlying mechanisms.

KEY RESULTS

MiR-9 is ectopically expressed in breast cancer and its level is negatively correlated with the prognosis, especially in basal-like breast cancer patients. Additionally, miR-9 is essential for breast cancer progression by promoting the expansion and activity of tumour-initiating cells (TICs) in preneoplastic glands, established tumours and xenograft modes. Mechanistically, the activity of TICs hinges on a positive TGF-β/miR-9 regulatory loop mediated by the STARD13/YAP axis.

CONCLUSIONS AND IMPLICATIONS

These findings demonstrate that miR-9 is an oncogenic miRNA rather than a tumour-suppressor in breast cancer, calling for rectification of the model for this conserved and highly abundant miRNA.

Dephosphorylation of Six2Y129 protects tyrosine hydroxylase-positive cells in SNpc by regulating TEA domain 1 expression

Parkinson's disease (PD) is a neurodegenerative disease characterized by selective loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). We recently reported that Six2 could reverse the degeneration of DA neurons in a dephosphorylation state. Here we further identified that Eya1 was the phosphatase of Six2 that could dephosphorylate the tyrosine 129 (Y129) site by forming a complex with Six2 in damaged DA cells. Dephosphorylated Six2 then translocates from the cytoplasm to the nucleus. Using ChIP-qPCR and dual luciferase assay, we found that dephosphorylated Six2 down-regulates TEA domain1 (Tead1) expression, thus inhibiting 6-hydroxydopamine (6-OHDA)-induced apoptosis in DA cells. Furthermore, we showed Six2Y129F/Tead1 signaling could protect against the loss of SNpc tyrosine hydroxylase-positive (TH+) cells and improve motor function in PD model rats. Our results demonstrate a dephosphorylation-dependent mechanism of Six2 that restores the degeneration of DA neurons, which could represent a potential therapeutic target for PD.

Exploring human CYP4 enzymes: Physiological roles, function in diseases and focus on inhibitors

The cytochrome P450 (CYP)4 family of enzymes are monooxygenases responsible for the ω-oxidation of endogenous fatty acids and eicosanoids and play a crucial part in regulating numerous eicosanoid signaling pathways. Recently, CYP4 gained attention as a potential therapeutic target for several human diseases, including cancer, cardiovascular diseases and inflammation. Small-molecule inhibitors of CYP4 could provide promising treatments for these diseases. The aim of the present review is to highlight the advances in the field of CYP4, discussing the physiology and pathology of the CYP4 family and compiling CYP4 inhibitors into groups based on their chemical classes to provide clues for the future discovery of drug candidates targeting CYP4.

ncRNA-mediated ceRNA regulatory network: Transcriptomic insights into breast cancer progression and treatment strategies

With the rapid development of next-generation sequencing technology, several studies have shown that ncRNAs can act as competitive endogenous RNAs (ceRNAs) and are involved in various biological processes, such as proliferation, differentiation, apoptosis, and migration of breast cancer (BC) cells, and plays an important role in BC progression as a molecular target for its diagnosis, treatment, prognosis, and differentiation of subtypes and age groups of BC patients. Based on the description of ceRNA-related biological functions, this study screened and sorted the sequencing analysis and experimental verification conclusions of BC-related ceRNAs and found that the ncRNAs mediated ceRNA networks can promote the development of BC by promoting the expression of genes related to BC proliferation, drug resistance, and apoptosis, inducing the production of epithelial-mesenchymal transition (EMT) to promote metastasis and activating cancer-related signaling pathways.

Long non-coding RNA TDRG1 aggravates lung cancer stemness by binding to Sox2 mRNA

The roles of long non-coding RNA TDRG1 have been revealed in several tumors, especially its roles in CSC progression have been recently elucidated; However, its effects in lung CSC progression have not been revealed. In the present study, we collected 3D non-adherent spheres as the CSC model to measure lncRNA TDRG1 level in lung CSC and the parental lung cancer cells, and found that TDRG1 level was significantly upregulated in lung CSCs compared to that of parental lung cancer cells. Then we constructed the lung CSCs with or without TDRG1 stable knockdown and lung cancer cells with or without TDRG1 stable overexpression. It was found that TDRG1 positively regulated lung cancer stemness. Mechanistically, we identified that TDRG1 directly bound to Sox2 mRNA, which is a critical stemness regulator, enhanced its mRNA stability, and thus increased Sox2 expression. Indeed, we demonstrated that TDRG1 aggravated lung cancer stemness dependent on Sox2 expression. Thus, this study suggests that TDRG1 is a critical stemness promoter of lung cancer cells by acting as a stabilizer for Sox2 mRNA.

PLAGL2 promotes the stemness and is upregulated by transcription factor E2F1 in human lung cancer

This study mainly focuses on revealing the role of PLAGL2 in lung cancer stemness. In vitro and in vivo experiments were performed to evaluate the effects of PLAGL2 on lung cancer cell stemness. Mechanistic analysis using luciferase reporter and ChIP assays were implemented to reveal the underlying mechanisms. The transcriptional factor E2F1 transcriptionally activated PLAGL2 expression via directly binding to PLAGL2 promoter in lung cancer cells. Moreover, PLAGL2 promoted the stemness of lung cancer cells dependent on E2F1-mediated transcriptional activation. This study provides a potential target for lung cancer progression.

Identification of a Novel Potent CYP4Z1 Inhibitor Attenuating the Stemness of Breast Cancer Cells through Lead Optimization

Pharmacological targeting cancer stem cells are emerging as a novel therapeutic modality for cancer treatment and prevention. Human cytochrome P450 enzyme CYP4Z1 represents a promising target for its potential role in attenuating the stemness of breast cancer cells. In order to develop potent and selective CYP4Z1 inhibitors, a series of novel N-hydroxyphenylformamidines were rationally designed and synthesized from a pan-CYP inhibitor HET0016. CYP4Z1 inhibitory activities of the newly synthesized derivatives were evaluated, and the structure-activity relationships (SARs) were summarized. Among them, compound 7c exhibited the best inhibitory activity with an IC50 value of 41.8 nM. Furthermore, it was found that 7c decreased the expression of stemness markers, spheroid formation, and metastatic ability as well as tumor-initiation capability in a concentration-dependent manner in vitro and in vivo. Altogether, compound 7c might be a potential lead compound to develop CYP4Z1 inhibitor with more favorable druggability for clinical application to treat breast cancer.

Acetylation of Checkpoint suppressor 1 enhances its stability and promotes the progression of triple-negative breast cancer

Checkpoint suppressor 1 (CHES1), a transcriptional regulator, had been dysregulated in many types of malignancies including breast cancer, and its expression level is strongly associated with progression and prognosis of patients. However, the underlying regulatory mechanisms of CHES1 expression in the breast cancer and the effects of post-translational modifications (PTMs) on its functional performance remain to be fully investigated. Herein, we found that CHES1 had a high abundance in triple-negative breast cancer (TNBC) and its expression was tightly associated with malignant phenotype and poor outcomes of patients. Furthermore, we confirmed that CHES1 was an acetylated protein and its dynamic modification was mediated by p300 and HDAC1, and CHES1 acetylation enhanced its stability via decreasing its ubiquitination and degradation, which resulted in the high abundance of CHES1 in TNBC. RNA-seq and functional study revealed that CHES1 facilitated the activation of oncogenic genes and pathways leading to proliferation and metastasis of TNBC. Taken together, this research established a novel regulatory role of acetylation on the stability and activity of CHES1. The results demonstrate the significance of CHES1 acetylation and underlying mechanisms in the progression of TNBC, offering new potential candidate for molecular-targeted therapy in breast cancer.

Long non-coding RNA TDRG1 aggravates colorectal cancer stemness by binding with miR-873-5p to upregulate PRKAR2

The effects of long non-coding RNA TDRG1 have been established in several tumors; however, its roles in colorectal cancer (CRC) progression are never been found. Here, we found that TDRG1 level was upregulated in CRC cells compared to that in normal colon epithelial cells. Additionally, TDRG1 level was remarkably upregulated in 3D non-adherent spheres derived from the parental CRC cells. Further in vitro and in vivo revealed that TDRG1 knockdown suppressed the stemness of CRC cells. What's more, combined with bioinformatics analysis, luciferase reporter and RNA pull down experiments showed that TDRG1 could bind to miR-873-5p, downregulated its level and thus increase the expression of PRKAR2. Finally, it was shown that TDRG1 functioned through the miR-873-5p/PRKAR2 axis. This study demonstrated a novel TDRG1/miR-873-5p/PRKAR2 signaling in CRC progression.

Cytochrome 4Z1 Expression Connotes Unfavorable Prognosis in Ovarian Cancers

Background and Objective: Ovarian cancer is a leading cause of death in females. Since its treatment is challenging and causes severe side effects, novel therapies are urgently needed. One of the potential enzymes implicated in the progression of cancers is Cytochrome 4Z1 (CYP4Z1). Its expression in ovarian cancer remains unknown. Therefore, the current study aims to assess CYP4Z1 expression in different subtypes of ovarian cancers. Materials and Methods: Immunohistochemistry was used to characterize CYP4Z1 expression in 192 cases of ovarian cancers along with eight normal ovarian tissues. The enzyme’s association with various clinicopathological characteristics and survival was determined. Results: CYP4Z1 was strongly expressed in 79% of ovarian cancers, compared to negative expression in normal ovarian samples. Importantly, significantly high CYP4Z1 expres-sion was determined in patients with advanced-stage cancer and a high depth of invasion (p < 0.05). Surprisingly, CYP4Z1 expression was significantly associated with a low patient survival rate. Univariate analysis revealed that patient survival was strongly associated with CYP4Z1 expression, tumor stage, depth of invasion, and lymph node metastasis (p < 0.05). Multivariate analysis showed that only CYP4Z1 expression was significantly associated with patient survival (p < 0.05). Conclusions: CYP4Z1 expression is correlated with shorter patient survival and has been identified as an independent indicator of a poor prognosis for ovarian cancer patients.

EHD1 promotes the cancer stem cell (CSC)-like traits of glioma cells via interacting with CD44 and suppressing CD44 degradation

Plenty of evidence has shown that endocytosis plays a key role in cancer progression; however, its effects in the progression of cancer stem cells (CSCs) are still fragmentary. In the present study, we firstly identified that mammalian Eps15 homology domain protein 1 (EHD1), an endocytic and metastasis-associated gene, was upregulated in the 3D non-adherent spheres derived from glioma cells compared to that in the corresponding parental cells. Further functional experiments revealed that EHD1 knockdown reduced the CSC-like traits of glioma cells, which were evident by the decrease of sphere-formation ability, ALDH1 activity, and CSC markers' expression. Additionally, EHD1 knockdown attenuated the tumor-initiating ability of glioma cells in vivo. Furthermore, it was shown that EHD1 bound to CD44, enhanced CD44 stability, and prevented its total ubiquitination. Indeed, overexpression of CD44 rescued the inhibitory effects of EHD1 knockdown on the CSC-like traits of glioma cells. Finally, through the online dataset analysis, we found that EHD1 indeed exhibited a higher level in glioma tissues relative to that in normal tissues, and a positive correlation with CSC markers' expression in glioma tissues. Notably, EHD1 expression was negatively correlated with the overall survival and relapse-free survival of glioma patients. Thus, this work indicates that EHD1 might be a potent target for glioma progression, especially through breaking the EHD1-CD44 interaction.

ISG15 enhances glioma cell stemness by promoting Oct4 protein stability

The effects of ISG15 or ISGylation on tumor progression have been widely revealed; however, its roles in glioma progression are largely unknown. This study aims to explore the roles and underlying mechanisms of ISG15 in glioma progression. Here, ISG15 level was found to be upregulated in glioma tissues compared to the paired/unpaired normal tissues, and positively correlated with the level of stemness markers in glioma tissues. Loss of functional experiments indicated that ISG15 positively regulated glioma cell stemness, as evident by the increase of sphere formation ability, ALDH activity, stemness marker expression, and tumor-initiating ability. Further mechanistic studies revealed that ISG15 directly interacted with Oct4 protein, a critical stemness promoter, induced the ISGylation of Oct4 protein, and thus enhanced Oct4 protein stability. Additionally, it was found that Oct4 was ISGylated at lysine 284 (K284), which has been confirmed to be the ubiquitination site of Oct4 protein, and ISG15 knockdown did not degrade K284R mutant Oct4. Furthermore, ISG15 knockdown-induced downregulation of glioma cell stemness was rescued by Oct4 overexpression, but not by K284R mutant Oct4. Altogether, we suggest that ISG15-induced ISGylation of Oct4 protein is essential for glioma cell stemness.

MicroRNA-18 facilitates the stemness of gastric cancer by downregulating HMGB3 though targeting Meis2

The recurrence and metastasis of gastric cancer are related to the stemness of gastric cancer cells. Researches have shown that miR-18 level is negatively correlated to the occurrence and development of certain cancer types. However, the effects of miR-18 on the stemness of gastric cancer remain uncertain. In this research, gastric cancer cell lines with stable overexpression of miR-18 were constructed through lentivirus infection. CCK-8 assay, RT-qPCR, Western blot, flow cytometry, and in vivo tumorigenesis assays were performed to evaluate the effects of miR-18 on the stemness of gastric cancer cells. Moreover, luciferase reporter assays found that Meis2 was the target of miR-18. Furthermore, we also found that the low-expressed oncogene HMGB3 is involved in this miR-18/Meis2 axis to further promote the stemness of gastric cancer cells. These findings suggest that the miR-18/Meis2/HMGB3 axis may be potential prognostic indicators for patients with gastric cancer.

Metabolic dysregulation and emerging therapeutical targets for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive human cancer with increasing incidence worldwide. Multiple efforts have been made to explore pharmaceutical therapies to treat HCC, such as targeted tyrosine kinase inhibitors, immune based therapies and combination of chemotherapy. However, limitations exist in current strategies including chemoresistance for instance. Tumor initiation and progression is driven by reprogramming of metabolism, in particular during HCC development. Recently, metabolic associated fatty liver disease (MAFLD), a reappraisal of new nomenclature for non-alcoholic fatty liver disease (NAFLD), indicates growing appreciation of metabolism in the pathogenesis of liver disease, including HCC, thereby suggesting new strategies by targeting abnormal metabolism for HCC treatment. In this review, we introduce directions by highlighting the metabolic targets in glucose, fatty acid, amino acid and glutamine metabolism, which are suitable for HCC pharmaceutical intervention. We also summarize and discuss current pharmaceutical agents and studies targeting deregulated metabolism during HCC treatment. Furthermore, opportunities and challenges in the discovery and development of HCC therapy targeting metabolism are discussed.

Tanshinone IIA attenuates the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis

BACKGROUND

Tanshinone II A is an effective component extracted from Salvia miltiorrhiza and the roles of Tanshinone IIA in regulating the stemness of tumor cells remain unclear. This work aims to explore the roles and underlying mechanisms of Tanshinone IIA in breast cancer stemness.

METHODS

In vitro mammary spheroid formation, flow cytometry assay on CD24^-/CD44⁺ sub-population, ALDH activity detection, cell viability assay and western blot analysis, and in vivo tumor-initiating analysis were performed to examine the effects of Tanshinone IIA on the stemness of breast cancer cells. MiRNAs-based transcriptome sequencing and data analysis, online dataset analysis, luciferase reporter assay combined with rescuing experiments were constructed to explore the underlying mechanisms.

RESULTS

Tanshinone IIA attenuated the stemness of breast cancer cells, evident by downregulating the expression of stemness markers, hindering the capacity of spheroid formation, decreasing the CD24^-/CD44⁺ sub-population in a concentration-dependent manner and reducing the tumor-initiating ability of breast cancer cells. Additionally, Tanshinone IIA enhanced adriamycin sensitivity and attenuated adriamycin resistance of breast cancer cells. Combined with miRNAs-based transcriptome sequencing assay, it was found that Tanshinone IIA downregulated miR-125b level and upregulated its target gene STARD13 (StAR-related lipid transfer protein 13) level, thus inactivating the miR-125b/STARD13 axis, which had been previously confirmed to promote breast cancer progression. Notably, miR-125b overexpression enhanced the stemness of breast cancer cells, and miR-125b overexpression or STARD13 knockdown impaired the inhibitory effects of Tanshinone IIA on the stemness of breast cancer cells.

CONCLUSIONS

Tanshinone IIA could attenuate the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis.

The World of Pseudogenes: New Diagnostic and Therapeutic Targets in Cancers or Still Mystery Molecules?

Pseudogenes were once considered as “junk DNA”, due to loss of their functions as a result of the accumulation of mutations, such as frameshift and presence of premature stop-codons and relocation of genes to inactive heterochromatin regions of the genome. Pseudogenes are divided into two large groups, processed and unprocessed, according to their primary structure and origin. Only 10% of all pseudogenes are transcribed into RNAs and participate in the regulation of parental gene expression at both transcriptional and translational levels through senseRNA (sRNA) and antisense RNA (asRNA). In this review, about 150 pseudogenes in the different types of cancers were analyzed. Part of these pseudogenes seem to be useful in molecular diagnostics and can be detected in various types of biological material including tissue as well as biological fluids (liquid biopsy) using different detection methods. The number of pseudogenes, as well as their function in the human genome, is still unknown. However, thanks to the development of various technologies and bioinformatic tools, it was revealed so far that pseudogenes are involved in the development and progression of certain diseases, especially in cancer.

Faciogenital dysplasia 5 confers the cancer stem cell-like traits of gastric cancer cells through enhancing Sox2 protein stability

The promoting roles of faciogenital dysplasia 5 (FGD5) in tumor progression have been identified in various tumors, however, its roles in gastric cancer progression are still confusing. Currently, it was found that FGD5 was highly expressed in gastric cancer tissues and negatively correlated with different types of survival of gastric cancer patients via online dataset analysis. In vitro analysis of different types of gastric cancer cell lines and normal gastric epithelial cells obtained a consistent result. Then FGD5 was knocked down in gastric cancer cell lines through two independent siRNAs against FGD5 and it was identified that FGD5 knockdown suppressed the cancer stem cell (CSC)-like traits of gastric cancer cells through analyzing the expression of CSC markers, ALDH1 activity and spheroid-formation ability. Further mechanistic studies revealed that FGD5 interacted with Sox2 protein, a critical regulator of CSC progression, enhanced Sox2 protein stability and decreased its ubquitination. Additionally, FGD5 supported the CSC-like traits dependent on Sox2 expression. Taken together, this work identified a novel FGD5/Sox2 axis responsible for the CSC-like traits of gastric cancer cells.

Cytochrome 4Z1 Expression is Associated with Poor Prognosis in Colon Cancer Patients

Purpose

Colon cancer is a leading cause of mortality worldwide. It has a relatively poor prognosis; therefore, new therapies are needed. One of the tumour-related enzymes that has gained considerable interest is CYP4Z1. This enzyme has been expressed in many tumours and has been hypothesized as a potential biomarker or target for novel anticancer therapies.

Patients and Methods

CYP4Z1 overexpression was immunohistochemically examined in a large panel of colon tissue types including normal, benign, primary and metastatic ones, and the enzyme’s relation to histopathological features and patient survival was evaluated.

Results

A high CYP4Z1 expression was observed in benign, primary and metastatic colon tissues compared to a weak or lack of expression in normal tissues. Importantly, there was a significant differential in CYP4Z1 expression where it was stronger in metastatic, primary and benign, respectively (p < 0.05). A significantly high rate of CYP4Z1 expression was found in high histological grades and late stages of the disease, where its expression was more evident in patients with metastasis in the lymph nodes (p < 0.05). Interestingly, CYP4Z1 expression was identified an independent prognostic predictor of poor overall survival of colon cancer patients (p = 0.003).

Conclusion

CYP4Z1 was distinctly overexpressed in benign, primary and metastatic colon tissues compared to corresponding normal tissues. This differential in CYP4Z1 expression across different types of colon tissues strongly supports CYP4Z1 as potential biomarker and target for novel anticancer therapy development.

Cytochrome 4Z1 Expression is Associated with Unfavorable Survival in Triple-Negative Breast Cancers

Purpose

Triple-negative breast cancer (TNBC) is characterized by high mortality rate, and its clinical management is difficult and complex. Therefore, there is a need for extensive efforts aimed at accelerating the discovery of novel therapies for TNBC. CYP4Z1 has been implicated in the development of breast cancer. The current study aimed at characterizing the expression of CYP4Z1 on TNBC.

Materials and Methods

Using immunohistochemistry, CYP4Z1 expression was evaluated on 122 TNBC samples, four samples of breast cancers expressing ER, PR, and HER-2, and four samples of normal breast tissues. The association between the enzyme and various histopathological features and survival of patients were determined.

Results

CYP4Z1 was strongly expressed in 83.3% of various histopathological subtypes of TNBC, when compared to negative expression in normal breast tissues. Interestingly, there were marked variations in CYP4Z1 expression with respect to histopathology subtype, histological grade, histological stage and tumor diameter. There was a high incidence of CYP4Z1 expression in patients with advanced grades, late stages and larger tumor sizes. Importantly, CYP4Z1 expression was correlated with the survival of TNBC patients, but it was an independent determinant of the poor prognosis of TNBC (p< 0.05).

Conclusion

CYP4ZI may be a potential biomarker or target for evolving new CYP4Z1-targeted treatments.

Cytochrome 4Z1 Expression Is Correlated with Poor Prognosis in Patients with Cervical Cancer

Background: cervical cancer is one of the most common malignancies in women worldwide and its management remains challenging and complex. As Cytochrome4Z1 (CYP4Z1) is overexpressed in many tumours, its expression in cervical cancer is unknown. Therefore, the present study aimed to evaluate CYP4Z1 expression in cervical cancers. Methods: CYP4Z1 expression was immunohistochemically assessed in 100 cases of cervical cancers along with ten normal cervix tissues, and the enzyme’s relationship to several clinicopathological features and survival was explored. Results: CYP4Z1 was strongly expressed in 55% of cervical cancer patients. Normal cervix samples were negative for CYP4Z1 expression. Importantly, this expression was significantly found in patients with the late stage of the disease, lymph node metastasis, and high tumour invasion (p < 0.05). Interestingly, CYP4Z1 expression was significantly correlated with shorter survival times of cervical cancer patients. Univariate analysis showed that CYP4Z1 expression, tumour stage, lymph node metastasis, and tumour invasion were significantly correlated with patient survival (p < 0.05). The multivariate analysis revealed that only CYP4Z1 expression and tumour stage were significantly correlated with patient survival (p < 0.05). Conclusions: CYP4Z1 expression is associated with cervical cancer patients’ survival and may serve as an independent predictor of poor prognosis in cervical cancer patients.

Transmembrane protein TMEM119 facilitates the stemness of breast cancer cells by activating Wnt/β-catenin pathway

The effects of transmembrane protein 119 (TMEM119) on breast cancer progression have not been elucidated. This study aims to investigate the roles of TMEM119 in breast cancer progression. Clinical samples and online datasets were used to determine TMEM119 expression and its correlation between patients’ survival. Wound healing, transwell invasion, mammary spheroid formation, and ALDH activity were performed to detect the effects of TMEM119. RNA-sequencing, Luciferase report analysis, Co-IP, and ChIP analysis were constructed to reveal the underlying mechanisms. We found that TMEM119 was highly expressed in breast cancer tissues and cells compared to that in normal tissues and cells. Additionally, TMEM119 expression was negatively correlated with the survival of breast cancer patients. TMEM119 knockdown reduced the expression of stemness markers, mammary spheroid-formation ability and ALDH activity. RNA-sequencing analysis indicated that Wnt/β-catenin signaling was enriched in cells with TMEM119 overexpression. Further co-IP experiments indicated that TMEM119 interacted with β-catenin and maintained its protein stability. Conversely, β-catenin directly bound to TMEM119 gene promoter and thus increased TMEM119 transcriptional activity and its expression. Finally, we demonstrated that TMEM119-mediated effects depended on Wnt/β-catenin signaling. Thus, this work reveals a novel TMEM119-β-catenin positive feedback loop essential for breast cancer cell stemness.

HET0016 attenuates the stemness of breast cancer cells through targeting CYP4Z1

Ours and other previous studies have shown that CYP4Z1 is specifically and highly expressed in breast cancer, and acts as a promoter for the stemness of breast cancer cells. Here, we explored whether targeting CYP4Z1 could attenuate the stemness of breast cancer cells using HET0016, which has been confirmed to be an inhibitor of CYP4Z1 by us and others. Using the transcriptome-sequencing analysis, we found that HET0016 suppressed the expression of cancer stem cell (CSC) markers and stem cell functions. Additionally, HET0016 indeed reduced the stemness of breast cancer cells, as evident by the decrease of stemness marker expression, CD44+ /CD24- subpopulation with stemness, mammary-spheroid formation, and tumor-initiating ability. Moreover, HET0016 suppressed the metastatic capability through in vitro and in vivo experiments. Furthermore, we confirmed that HET0016 suppressed CYP4Z1 activity, and HET0016-induced inhibition on the stemness and metastasis of breast cancer cells was rescued by CYP4Z1 overexpression. Thus, our results demonstrate that HET0016 can attenuate the stemness of breast cancer cells through targeting CYP4Z1.

Identification of key pseudogenes in nasopharyngeal carcinoma based on RNA-Seq analysis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a malignant head and neck tumor, and more than 70% of new cases are in East and Southeast Asia. However, association between NPC and pseudogenes playing important roles in genesis of multiple tumor types is still not clear and needs to be investigated.

METHODS

Using RNA-Sequencing (RNA-seq) technology, we analyzed pseudogene expression in 13 primary NPC and 6 recurrent NPC samples as well as their paracancerous counterparts. Quantitative PCR was used to validate the differentially expressed pseudogenes.

RESULTS

We found 251 differentially expressed pseudogenes including 73 up-regulated and 178 down-regulated ones between primary NPC and paracancerous tissues. Enrichment analysis of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were conducted to filter out the key pseudogenes. We reported that pseudogenes from cytochrome P450 (CYP) family, such as CYP2F2P, CYP2G1P, CYP4F24P, CYP2B7P and CYP2G2P were significantly down-regulated in NPC compared to paracancerous tissues, while IGHV1OR15-2, IGHV3-11, FCGR1CP and IGHV3-69-1 belonging to Fc gamma receptors were significantly up-regulated. CYP2B7P, CYP2F2P and CYP4F26P were enriched in arachidonic acid metabolism pathway. The qRT-PCR analysis validated the lower expression of pseudogenes CYP2F2P and CYP2B7P in NPC tissues and cell lines compared to paracancerous tissues and normal human nasopharyngeal epithelial cell line. CYP2B7P overexpression weakened migratory and invasive capacity of NPC cell line. Moreover, the expression pattern of those pseudogenes in recurrent NPC tissues was different from the primary NPC.

CONCLUSION

This study suggested the role of pseudogenes in tumorigenesis and progression, potentially functioning as therapeutic targets to NPC.

Assessment of Phenylboronic Acid Nitrogen Mustards as Potent and Selective Drug Candidates for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) has limited treatment options and the worst prognosis among all types of breast cancer. We describe two prodrugs, namely, CWB-20145 (1) and its methyl analogue FAN-NM-CH3 (2) that reduced the size of TNBC-derived tumors. The DNA cross-linking of nitrogen mustard prodrugs 1 and 2 was superior to that of chlorambucil and melphalan once activated in the presence of H2O2. The cellular toxicity of 1 and 2 was demonstrated in seven human cancer cell lines. The TNBC cell line MDA-MB-468 was particularly sensitive toward 1 and 2. Compound 2 was 10 times more cytotoxic than chlorambucil and 16 times more active than melphalan. An evaluation of the gene expression demonstrated an upregulation of the tumor suppressor genes p53 and p21 supporting a transcriptional mechanism of a reduced tumor growth. Pharmacokinetic studies with 1 showed a rapid conversion of the prodrug. The introduction of a methyl group generated 2 with an increased half-life. An in vivo toxicity study in mice demonstrated that both prodrugs were less toxic than chlorambucil. Compounds 1 and 2 reduced tumor growth with an inhibition rate of more than 90% in athymic nude mice xenografted with MDA-MB-468 cells. Together, the in vivo investigations demonstrated that treatment with 1 and 2 suppressed tumor growth without affecting normal tissues in mice. These phenylboronic acid nitrogen mustard prodrugs represent promising drug candidates for the treatment of TNBC. However, the mechanisms underlying their superior in vivo activity and selectivity as well as the correlation between H2O2 level and in vivo efficacy are not yet fully understood.

Acylglycerol kinase promotes the stemness of nasopharyngeal carcinoma cells by promoting β-catenin translocation to the nucleus through activating PI3K/Akt pathway

Recent evidences show that acylglycerol kinase (AGK) expression is related to the occurrence and development of various human cancers. However, its roles in nasopharyngeal carcinoma (NPC) progression are still unclear. This work aims to explore the roles of AGK in NPC cell stemness. It was shown that AGK expression was higher in NPC tissues compared to the adjacent tissues. Online dataset analysis revealed that AGK expression was negatively correlated with the overall survival of NPC patients. Gain and loss of functional experiments demonstrated that AGK positively regulated the stemness of NPC cells, as evident by the change of the tumor sphere-formation ability, ALDH1 activity and expression of stemness critical regulators. KEGG analysis were performed to determine the potential pathways of AGK involved in NPC cell stemness and showed that the PI3K/Akt pathway exhibited the most correlation with AGK expression. Further mechanistic studies confirmed that AGK promoted the stemness of NPC cells through activating the PI3K/Akt pathway, and thus enhancing β-catenin accumulation in nucleus. This study demonstrates a novel AGK/PI3K/Akt/β-catenin axis involving in NPC cell stemness.

MiR-375 inhibits the stemness of breast cancer cells by blocking the JAK2/STAT3 signaling

The relapse of breast cancer could be due to the existence of breast cancer stem cells (BCSCs). Other and our researches have indicated the suppressive roles of miR-375 in various tumors, however, its roles in breast cancer stemness remain confusing. Here, we constructed breast cancer cells with miR-375 stable overexpression via lentivirus infection. Flow cytometry, Western blot, mammosphere formation, cell colony formation and CCK8 as well as in vivo assays were performed to identify the role of miR-375 in the stemness of breast cancer cells. Luciferase reporter, RNA-Fluorescence in situ hybridization (RNA-FISH) and RNA-binding protein immunoprecipitation (RIP) assays were utilized to elucidate the mechanism whereby miR-375 exerts its effects. It was found that miR-375 not only reduced the stemness, but also decreased adriamycin resistance of breast cancer cells. These results were characterized by the decrease of BCSC rate, mammosphere-forming and tumor-initiating ability, and IC50 value of adriamycin, and weakened by JAK2 re-expression. This work indicates that miR-375 suppresses the stemness of breast cancer cells through targeting JAK2.

Screening of cytochrome 4Z1 expression in human non-neoplastic, pre-neoplastic and neoplastic tissues

Background:

Cytochromes P450 (CYPs) constitute an enzyme family involved in the oxidative metabolism of a wide variety of endogenous and exogenous compounds, including anti-cancer drugs and carcinogens. Unlike other human CYPs, CYP4Z1 is highly expressed in human breast carcinoma and is associated with poor prognosis. As a result, CYP4Z1 was hypothesised to be a potential biomarker or drug target for the discovery and development of promising anti-cancer therapies.

Materials and methods:

CYP4Z1 expression was immunohistochemically studied in a set of 100 different human tissues, including normal, benign, malignant and metastatic tissues, which originated from 27 anatomical sites. As a tumour model for CYP4Z1 expression, a panel of different breast cancers was evaluated for CYP4Z1 expression and its relation to histopathological features and prognostic immunohistochemical markers.

Results:

The immunohistochemical results revealed that CYP4Z1 was expressed in only one (4.3%) of the normal tissues from the mammary glands, while the expression of the enzyme was positive in 1 (11%), 12 (19%) and 2 (40%) of the benign, malignant and metastatic tissues, respectively. Interestingly, several tumour entities showed prominent expressions of CYP4Z1, including carcinomas of adrenal cortex, squamous cells of oesophagus, lung and cervix, as well as seminoma, astrocytoma, melanoma and lastly endometrial adenocarcinoma. In breast cancers, CYP4Z1 was expressed in 82% of the cases. Its expression was significantly associated with the pathology of tumour, histological grade and status of lymph node metastasis. Importantly, it was also significantly associated with the expressions of Her2, P53 and Ki-67.

Conclusion:

These findings greatly support future plans for the use of CYP4Z1 as a biomarker or target for anti-cancer drugs. However, large-scale validation studies are needed to better delineate the potential use of CYP4Z1 for therapeutic purposes.

Transcriptional Factor Yin Yang 1 Promotes the Stemness of Breast Cancer Cells by Suppressing miR-873-5p Transcriptional Activity

Transcription factor Yin Yang 1 (YY1) is upregulated in multiple tumors and plays essential roles in tumor proliferation and metastasis. However, the function of YY1 in breast cancer stemness remains unclear. Herein, we found that YY1 expression was negatively correlated with the overall survival and relapse-free survival of breast cancer patients and positively correlated with the expression of stemness markers in breast cancer. Overexpression of YY1 increased the expression of stemness markers, elevated CD44+CD24- cell sub-population, and enhanced the capacity of cell spheroid formation and tumor-initiation. In contrast, YY1 knockdown exhibited the opposite effects. Mechanistically, YY1 decreased microRNA-873-5p (miR-873-5p) level by recruiting histone deacetylase 4 (HDAC4) and HDAC9 to miR-873-5p promoter and thus increasing the deacetylation level of miR-873-5p promoter. Sequentially, YY1 activated the downstream PI3K/AKT and ERK1/2 pathways, which have been confirmed to be suppressed by miR-873-5p in our recent work. Moreover, the suppressed effect of YY1/miR-873-5p axis on the stemness of breast cancer cells was partially dependent on PI3K/AKT and ERK1/2 pathways. Finally, it was found that the YY1/miR-873-5p axis is involved in the chemoresistance of breast cancer cells. Our study defines a novel YY1/miR-873-5p axis responsible for the stemness of breast cancer cells.

Long noncoding RNA MACC1-AS1 promotes the stemness of nonsmall cell lung cancer cells through promoting UPF1-mediated destabilization of LATS1/2

The roles of long noncoding RNA (lncRNA) MACC1-AS1 have been revealed in various tumors. This work aims to explore the roles of lncRNA MACC1-AS1 in the stemness of nonsmall cell lung cancer (NSCLC) cells and the underlying mechanism. We showed that overexpression of MACC1-AS1 enhanced the stemness of NSCLC cells, which is evident as the increased expression of cancer stem cell transcription factors, ALDH1 activity, and sphere-formation capacity, while knockdown of MACC1-AS1 decreased it. RNA-sequencing analysis revealed that the Hippo pathway was mostly enriched in NSCLC cell with MACC1-AS1 overexpression. Further mRNA and western blot analysis showed that ectopic expression of MACC1-AS1 regulated the expression LATS1/2, the critical regulator of Hippo pathway. Additionally, it was found that MACC1-AS1 interacted with up-frameshift 1 (UPF1) to modulate mRNA decay of LATS1/2. Overexpression of LAST1/2 attenuated the promoting effects of MACC1-AS1 overexpression on the stemness of NSCLC cells. Therefore, our results demonstrate the effects of the novel MACC1-AS1/UPF1/LATS1/2 axis in NSCLC cell stemness.

Long noncoding RNAs AC026904.1 is essential for TGF-β-induced migration and epithelial-mesenchymal transition through functioning as an enhancer of Slug in lung cancer cells

Long noncoding RNA (lncRNA) AC026904.1 has been confirmed to be necessary for breast cancer metastasis. This work aims to investigate the effects of lncRNA AC026904.1 on lung cancer metastasis. We found that lncRNA AC026904.1 displayed a higher level in metastatic lung cancer tissues than adjacent tissues and nonmetastatic lung cancer tissues, and lung cancer cells treated with TGF-β. The expression of AC026904.1 was increased by the non-canonical TGF-β signaling. Additionally, AC026904.1 acts as an enhancer of the key metastatic factor Slug in the nucleus. This AC026904.1/Slug axis is necessary for TGF-β-mediated migration and epithelial-mesenchymal transition in lung cancer cells. This work firstly uncovers that AC026904.1 increases Slug expression at transcriptional level and subsequently plays critical effects in lung cancer metastasis, providing novel evidences that AC026904.1 holds great potential to be used as a marker for metastatic lung cancer.

The F-box protein FBXO11 restrains hepatocellular carcinoma stemness via promotion of ubiquitin-mediated degradation of Snail

Expression of the F‐box protein FBXO11 has been shown to be down‐regulated in various tumors, but its role in hepatocellular carcinoma (HCC) progression remains unclear. Here, we examined the role of FBXO11 in HCC cell stemness. We report that FBXO11 expression is significantly decreased in HCC cells, and overexpression of FBXO11 decreased the expression of HCC stemness markers, ALDH1 activity and sphere‐forming ability. In addition, overexpression of FBXO11 reduced the migration ability and epithelial‐mesenchymal transition of HCC cells. Mechanistically, overexpression of FBXO11 decreased the protein level, but not mRNA level, of Snail by directly interacting with Snail and promoting Snail degradation through the ubiquitin‐proteasome system. Overexpression of Snail rescued the inhibitory effect of FBXO11 overexpression on HCC cell stemness. This study reveals the existence of a novel FBXO11/Snail regulatory axis that is necessary for HCC cell stemness.

Targeting SLC7A11 specifically suppresses the progression of colorectal cancer stem cells via inducing ferroptosis

Recent studies have revealed the critical roles of ferroptosis in different physiological and pathological processes, however, its effects on the progression of colorectal cancer stem cells (CSCs) are still unclear. Here, we found that colorectal CSCs exhibited a remarkably lower level of reactive oxygen species (ROS), a higher level of cysteine, glutathione and SLC7A11 compared to colorectal cancer cells. Knockout of SLC7A11 increased the ROS level and reduced the levels of cysteine and glutathione, subsequently attenuating the viability of colorectal CSCs. Erastin, an inhibitor of SLC7A11, was found to hold a remarkably stronger cytotoxic effect on colorectal CSCs via in vitro and in vivo experiments. Finally, it was found that Erastin attenuated the chemoresistance of colorectal CSCs. This work indicates that colorectal CSCs are more sensitive to ferroptosis, which could be targeted to attenuate colorectal cancer progression and chemoresistance.

TRIB3 confers glioma cell stemness via interacting with β-catenin

Here, we aim to explore whether tribbles pseudokinase 3 (TRIB3) enhances glioma cell stemness. TRIB3 was overexpressed in glioma tissues and cell-formed spheres, positively correlated with the size and grade. Additionally, TRIB3 expression displayed a negative correlation with the overall survival rate of glioma patients. Moreover, TRIB3 knockdown reduced the stemness of nonadherent spheres, evident by the decreased sphere-forming ability, stemness master expression, and ALDH1 activity, while TRIB3 overexpression enhanced the stemness of adherent cells, which was rescued by β-catenin knockdown. Mechanistically, TRIB3 activated β-catenin signaling via physically interacting with β-catenin. This study suggests that the TRIB3-β-catenin interaction is responsible for glioma cell stemness.

Ginsenoside Rg3 attenuates the osimertinib resistance by reducing the stemness of non-small cell lung cancer cells

In the present study, we found that Ginsenoside Rg3 attenuated the stemness of non-small cell lung cancer (NSCLC) cells, evident by decreasing spheroid formation ability, ALDH1 activity and stemness marker expression. Furthermore, osimertinib-resistant NSCLC cells displayed a stronger stemness than the parental cells. Ginsenoside Rg3 reduced the stemness and osimertinib resistance of osimertinib-resistant cells. RNA-sequencing revealed that Hippo signaling was shown on the top of the most upregulated pathways regulated by Ginsenoside Rg3 in NSCLC cells, and YAP/TAZ expression was suppressed by Ginsenoside Rg3. Notably, the inhibitor of Hippo signaling attenuated the effects of Ginsenoside Rg3 on the stemness of NSCLC cells. Therefore, Ginsenoside Rg3 attenuates the osimertinib resistance of NSCLC cells via suppressing the stemness, which is dependent on Hippo pathway.

Pseudogene-Derived lncRNAs and Their miRNA Sponging Mechanism in Human Cancer

Pseudogenes, abundant in the human genome, are traditionally considered as non-functional “junk genes.” However, recent studies have revealed that pseudogenes act as key regulators at DNA, RNA or protein level in diverse human disorders (including cancer), among which pseudogene-derived long non-coding RNA (lncRNA) transcripts are extensively investigated and has been reported to be frequently dysregulated in various types of human cancer. Growing evidence demonstrates that pseudogene-derived lncRNAs play important roles in cancer initiation and progression by serving as competing endogenous RNAs (ceRNAs) through competitively binding to shared microRNAs (miRNAs), thus affecting both their cognate genes and unrelated genes. Herein, we retrospect those current findings about expression, functions and potential ceRNA mechanisms of pseudogene-derived lncRNAs in human cancer, which may provide us with some crucial clues in developing potential targets for cancer therapy in the future.

Napabucasin Attenuates Resistance of Breast Cancer Cells to Tamoxifen by Reducing Stem Cell-Like Properties

BACKGROUND Tamoxifen (TAM) is the first-line drug for estrogen receptor-positive (ER+) breast cancer (BC) treatment. However, its resistance is a main obstacle in clinical practice. Thus, new therapeutic agents are urgently needed to fight TAM resistance. MATERIAL AND METHODS Here, we constructed TAM-resistant ER+BC cells with TAM resistance, named MCF-7-R. Western blot, quantitative real-time PCR (qRT-PCR), ALDH1 activity analysis, and spheroid-forming detection were used to detect the stemness of cells and the effects of napabucasin (NP) on BC cell stemness. Cell counting kit-8 (CCK8) assay was used to evaluate the effects of NP on cell viability. RESULTS MCF-7-R cells exhibited higher stemness compared with the parental MCF-7 cells, which was evident by the increased spheroid formation ability at diluted concentration, aldehyde dehydrogenase (ALDH) activity, and expression of stemness critical biomarkers (Oct4, Nanog, and Sox2). Additionally, it was found that napabucasin (NP) specifically killed MCF-7-T cells, characterized by remarkably decreased IC₅₀ value. Notably, NP reduced MCF-7-R cell stemness, which was evident as the decreased stemness marker expression, spheroid-forming capacity, and ALDH1 activity. Importantly, NP attenuated TAM resistance of MCF-7-R cells and enhanced sensitivity of MCF-7 cells to TAM. Mechanistic study showed that NP inhibited STAT3 activation, and overexpression of STAT3 rescued NP-mediated inhibition of the stemness-like characteristics of MCF-7-R cells. CONCLUSIONS NP might be used as an adjuvant therapy for ER+ BC patients with TAM resistance.

Targeting Frizzled-7 Decreases Stemness and Chemotherapeutic Resistance in Gastric Cancer Cells by Suppressing Myc Expression

BACKGROUND Although the promoting roles of Frizzled-7 (Fzd7) have been shown before, its effects in gastric cancer (GC) cell stemness are still unclear. The present study assessed the effects of Fzd7 on GC cell stemness and chemoresistance. MATERIAL AND METHODS Clinical samples were used to detect Fzd7 expression and online datasets were used to analyze the correlation between Fzd7 expression and GC patient prognosis. Quantitative real-time PCR (qPCR), Western blot, and spheroid formation were used to detect the stemness of cells and Fzd7-mediated effects on GC cell stemness. Cell viability was assessed to evaluate the role of Fzd7 in chemoresistance of GC cells. RESULTS We found that the expression of Frizzled-7 (Fzd7), a Wnt receptor, was increased in gastric cancer (GC) cells and tissues. Additionally, Fzd7 expression was correlated with shorter overall survival of GC patients. Knockdown of Fzd7 or using inhibitors of Wnt/Fzd (OMP-18R5/Vantictumad) decreased GC cell stemness, characterized as a decrease of spheroid formation ability and expression of stemness regulators. Notably, Fzd7 knockdown or inhibitors of Wnt/Fzd attenuated the chemoresistance of GC cells. Furthermore, elevation of Myc expression rescued the effects of Fzd7 inhibition on GC cell stemness and chemoresistance. CONCLUSIONS Our results suggest that inhibition of Fzd7 decreases the stemness and chemotherapeutic resistance of GC cells.

Correction to: Transcriptional factor six2 promotes the competitive endogenous RNA network between CYP4Z1 and pseudogene CYP4Z2P responsible for maintaining the stemness of breast cancer cells

The original article [1] contained an error in Fig. 7c whereby the same flow image was accidentally misused for the second and fourth group.

TRIB3 promotes lung cancer progression by activating β-catenin signaling

TRIB3 roles in tumor progression have been revealed with similar or opposite results. Here, we found that TRIB3 expression was highly expressed in lung cancer tissues and correlated with tumor grades and metastasis. Functional experiments showed that TRIB3 knockdown (KD) inhibited lung cancer cell migration, invasion, EMT (epithelial-mesenchymal transition) process and stemness. Mechanistic studies demonstrated that TRIB3 physically interacted with β-catenin and increased the recruitment of β-catenin to the promoter region of genes regulated by Wnt. Re-activation of β-catenin attenuated the inhibition of TRIB3 KD on lung cancer progression. These results suggest that TRIB3 interacts with β-catenin and thus activates β-catenin signaling, which is responsible for lung cancer progression, and blocking TRIB3 activity might be developed to treat lung cancer.