Downregulation of RKIP promotes radioresistance of nasopharyngeal carcinoma by activating NRF2/NQO1 axis via downregulating miR-450b-5p

The interplay between microRNAs and Nrf2 signaling in human cancers

MicroRNAs (miRNAs), as a class of nonprotein-coding RNAs, post-transcriptionally regulate the expression of target genes by base pairing to 3'-untranslated regions (3'-UTRs). Nuclear factor E2-related factor 2 (Nrf2) has been identified as a critical component of the antioxidant defense mechanism. Dysregulation is associated with chemoresistance and radioresistance in cancerous cells. MiRNA-mediated regulation of the Nrf2 signaling pathway has been shown to have important implications for the development of various cancers. In this article, we review the roles of miRNAs as regulators of the Nrf2 pathway in different human cancers. Ras-associated binding (Rab) proteins have an essential role regulation of vesicle transport, as well as oncogenic functions in preventing chemotherapy efficacy and cancer development. More importantly, increased evidence indicated that the interaction between miRNAs and Rabs has been determined to play critical roles in cancer therapy. However, the significant limitations in using miRNAs for therapeutic applications include cross-targeting and instability of miRNAs. The detailed aspect of the interaction of miRNAs and Rabs is not clearly understood. In the current review, we highlighted the involvement of these molecules as regulators of the Nrf2 pathway in cancer pathogenesis. Potential methods and several obstacles in developing miRNAs as an anticancer therapy are also mentioned.

Upregulation and functional roles of miR-450b in canine oral melanoma

Canine oral melanoma (COM) is a common and highly aggressive disease with the potential to model human melanomas. Dysregulated microRNAs represent an interesting line of research for COM because they are implicated in tumor progression. One example is miR-450b, which has been investigated for its molecular mechanisms and biological functions in multiple human cancers, but not human or canine melanoma. Here, we aimed to investigate miR-450b as a potential diagnostic biomarker of COM and its functional roles in metastatic and non-metastatic forms of the disease. We investigated the expression of miR-450b and its target mRNA genes in clinical (tumor tissue and plasma) samples and metastatic and primary-tumor cell lines. Knockdown and overexpression experiments were performed to determine the influence of miR-450b on cell proliferation, migration, colony formation, and apoptosis. miR-450b was significantly upregulated in COM and differentiated between metastatic and non-metastatic tumors, and its potential as a biomarker of metastatic and non-metastatic COM was further confirmed in ROC analysis. miR-450b knockdown promoted cell proliferation, migration, and clonogenicity and inhibited apoptosis, whereas its overexpression yielded the reverse pattern. miR-450b directly binds 3' UTR of PAX9 mRNA and modulates its function leading to BMP4 downregulation and MMP9 upregulation at the transcript level. Furthermore, we surmised that miR-450b activates the Wnt signaling pathway based on gene ontology and enrichment analyses. We concluded that miR-450b has the potential as a diagnostic biomarker and could be a target candidate for COM treatment.

miR-450b promotes cell migration and invasion by inhibiting SERPINB2 in oral squamous cell carcinoma

OBJECTIVE

microRNA-450b (miR-450b) plays an important role in cancer progression; however, its function in oral squamous cell carcinoma (OSCC) remains largely unknown. This study aimed to investigate the action mechanisms of miR-450b in OSCC.

MATERIALS AND METHODS

OSCC animal model was established via continuous induction with single-drug 7, 12-dimethylbenzo[a]anthracene (DMBA). Animal tissue samples were pathologically typed using haematoxylin-eosin (HE) staining. The Cancer Genome Atlas (TCGA) database was used to predict miR-450b and SERPINB2 expression in head and neck squamous cell carcinoma (HNSCC). qRT-PCR and Western blotting were used to detect gene and protein expression in OSCC tissue and cells, respectively. OSCC cell proliferation, growth, migration and invasion were detected using CCK-8, colony formation, transwell migration and matrigel invasion assays, respectively. Bioinformatic tools were used to predict miR-450b target genes. Dual-luciferase reporter assay was used to verify targeting between miR-450b and SERPINB2. Finally, small interfering RNA (siRNA) was used to reduce SERPINB2 expression to detect its effect on tumourigenesis.

RESULTS

Four stages of OSCC carcinogenesis (normal oral epithelium, simple epithelial hyperplasia, dysplasia and OSCC) were identified. miR-450b was found to be overexpressed in OSCC animal samples, HNSCC samples and human OSCC cells. Upregulation of miR-450b significantly promoted OSCC cell proliferation, colony formation, migration and invasion, while its downregulation had the opposite effect. SERPINB2 was found to be a miR-450b target gene, and its expression was negatively correlated with miR-450b expression. Altering SERPINB2 expression effectively inhibited OSCC cell invasion, metastasis and epithelial-mesenchymal transition (EMT).

CONCLUSIONS

miR-450b plays a key role in OSCC tumourigenesis by regulating OSCC cell migration, invasion and EMT via SERPINB2.

Clinical Significance of Frequently Down-Regulated Phosphatidylethanolamine-Binding Protein-1 in Gallbladder Cancer

BACKGROUND

Promoter hypermethylation of tumor suppressor genes has been demonstrated to be one of the major mechanisms of their epigenetic regulation in various reports. We have studied the promoter methylation status of PEBP1 and evaluated its correlation with gallbladder carcinogenesis.

AIMS

PEBP1, an endogenous inhibitor of Raf/MEK/ERK signaling pathway, is a tumor suppressor gene. We aimed to study the expression profile of PEBP1 and understand the mechanism and significance of its deregulation in gallbladder cancer.

METHODS

PEBP1 expression analysis and its promoter methylation status were investigated in 77 gallbladder carcinoma (GBC) and tissue biopsies from 28 patients of gallstone disease by RT-PCR and MS-PCR, respectively.

RESULTS

Our results of the mRNA expression profiling demonstrate that PEBP1 is down-regulated in 62.3% (48/77), while 31.2% (24/77) of the gallbladder cancer biopsies show no significant change and 6.5% (5/77) show up-regulated expression compared to tissue samples of gallstone diseases. In GBC, 48.1% (N = 37) GBC biopsy samples exhibited significantly heterozygous promoter hypermethylation compared to tissue samples from gallstone diseases which show promoter hypermethylation in 3 (10.7%) samples only. In gallbladder cancer, the PEBP1 methylation is significantly associated with lymph node metastasis and shorter period of survival.

CONCLUSION

PEBP1 is frequently down-regulated and hypermethylated in gallbladder cancer and its promoter hypermethylation is a frequent and early inactivating mechanism in GBC.

Targeting the RAS/RAF/MAPK pathway for cancer therapy: from mechanism to clinical studies

Metastatic dissemination of solid tumors, a leading cause of cancer-related mortality, underscores the urgent need for enhanced insights into the molecular and cellular mechanisms underlying metastasis, chemoresistance, and the mechanistic backgrounds of individuals whose cancers are prone to migration. The most prevalent signaling cascade governed by multi-kinase inhibitors is the mitogen-activated protein kinase (MAPK) pathway, encompassing the RAS-RAF-MAPK kinase (MEK)-extracellular signal-related kinase (ERK) pathway. RAF kinase is a primary mediator of the MAPK pathway, responsible for the sequential activation of downstream targets, such as MEK and the transcription factor ERK, which control numerous cellular and physiological processes, including organism development, cell cycle control, cell proliferation and differentiation, cell survival, and death. Defects in this signaling cascade are associated with diseases such as cancer. RAF inhibitors (RAFi) combined with MEK blockers represent an FDA-approved therapeutic strategy for numerous RAF-mutant cancers, including melanoma, non-small cell lung carcinoma, and thyroid cancer. However, the development of therapy resistance by cancer cells remains an important barrier. Autophagy, an intracellular lysosome-dependent catabolic recycling process, plays a critical role in the development of RAFi resistance in cancer. Thus, targeting RAF and autophagy could be novel treatment strategies for RAF-mutant cancers. In this review, we delve deeper into the mechanistic insights surrounding RAF kinase signaling in tumorigenesis and RAFi-resistance. Furthermore, we explore and discuss the ongoing development of next-generation RAF inhibitors with enhanced therapeutic profiles. Additionally, this review sheds light on the functional interplay between RAF-targeted therapies and autophagy in cancer.

Epigenetic modulation of ferroptosis in cancer: Identifying epigenetic targets for novel anticancer therapy

Ferroptosis is a newly recognized form of oxidative-regulated cell death resulting from iron-mediated lipid peroxidation accumulation. Radical-trapping antioxidant systems can eliminate these oxidized lipids and prevent disrupting the integrity of cell membranes. Epigenetic modifications can regulate ferroptosis by altering gene expression or cell phenotype without permanent sequence changes. These mechanisms include DNA methylation, histone modifications, RNA modifications, and noncoding RNAs. Epigenetic alterations in cancer can control the expression of ferroptosis regulators or related pathways, leading to changes in cell sensitivity to ferroptosis inducers or cancer progression. Epigenetic alterations in cancer are influenced by a wide range of cancer hallmarks, contributing to therapeutic resistance. Targeting epigenetic alterations is a promising approach to overcoming cancer resilience. However, the exact mechanisms involved in different types of cancer remain unresolved. Discovering more ferroptosis-associated epigenetic targets and interventions can help overcome current barriers in anticancer therapy. Many papers on epigenetic modifications of ferroptosis have been continuously published, making it essential to summarize the current state-of-the-art in the epigenetic regulation of ferroptosis in human cancer.

Wogonin Diminishes Radioresistance of Breast Cancer via Inhibition of the Nrf2/HIF-1[Formula: see text] Pathway

Radiotherapy plays a crucial role in the multimodal treatment of breast cancer. However, radioresistance poses a significant challenge to its effectiveness, hindering successful cancer therapy. Emerging evidence indicates that Nrf2 and HIF-1[Formula: see text] are critical regulators of cellular anti-oxidant responses and that their overexpression significantly promotes radioresistance. Wogonin (WG), the primary component isolated from Scutellaria baicalensis, exhibits potential antitumor and reversal of multidrug resistance activities. Nevertheless, the role of WG in radioresistance remains unclear. This study aims to explore the effects of WG on the radioresistance of breast cancer. Our results indicate that Nrf2 and HIF-1[Formula: see text] overexpression was observed in breast cancer tissues and was correlated with the histological grading of the disease. Radiation further increased the levels of Nrf2 and HIF-1[Formula: see text] in breast cancer cells. However, WG demonstrated the ability to induce cell apoptosis and reverse radioresistance by inhibiting the Nrf2/HIF-1[Formula: see text] pathway. These effects were also confirmed in xenograft mice models. Mechanistically, WG enhanced the level of the Nrf2 inhibitor Keap1 through reducing CpG methylation in the promoter region of the Keap1 gene. Consequently, the Nrf2/HIF-1[Formula: see text] pathway, along with the Nrf2- and HIF-1[Formula: see text]-dependent protective responses, were suppressed. Taken together, our findings demonstrate that WG can epigenetically regulate the Keap1 gene, inhibit the Nrf2/HIF-1[Formula: see text] pathway, induce apoptosis in breast cancer cells, and diminish acquired radioresistance. This study offers potential strategies to overcome the limitations of current radiotherapy for breast cancer.

Ferroptosis in tumors and its relationship to other programmed cell death: role of non-coding RNAs

Programmed cell death (PCD) plays an important role in many aspects of individual development, maintenance of body homeostasis and pathological processes. Ferroptosis is a novel form of PCD characterized by the accumulation of iron-dependent lipid peroxides resulting in lethal cell damage. It contributes to tumor progression in an apoptosis-independent manner. In recent years, an increasing number of non-coding RNAs (ncRNAs) have been demonstrated to mediate the biological process of ferroptosis, hence impacting carcinogenesis, progression, drug resistance, and prognosis. However, the clear regulatory mechanism for this phenomenon remains poorly understood. Moreover, ferroptosis does not usually exist independently. Its interaction with PCD, like apoptosis, necroptosis, autophagy, pyroptosis, and cuproptosis, to destroy cells appears to exist. Furthermore, ncRNA seems to be involved. Here, we review the mechanisms by which ferroptosis occurs, dissect its relationship with other forms of death, summarize the key regulatory roles played by ncRNAs, raise relevant questions and predict possible barriers to its application in the clinic, offering new ideas for targeted tumour therapy.

Study of Three Potential Diagnostic Biomarkers in Nasopharyngeal Carcinoma Samples from Guilan, North of Iran

Introduction  Finding biomarkers for highly lethal cancers is a priority. Objective  The current study was designed to understand the clinical significance of vascular endothelial growth factor (VEGF), latent membrane protein 1 (LMP1), and tumor necrosis factor-α (TNF-α) expression as the biomarkers, and evaluate their correlation with each other, in nasopharyngeal carcinoma (NPC) in the province of Guilan, North of Iran. Methods  Gene expression was evaluated in 25 formalin-fixed paraffin-embedded (FFPE) blocks from cases of confirmed NPC and 20 FFPE samples of non-NPC by quantifying messenger ribonucleic acid (mRNA) and protein levels, using real-time polymerase chain reaction (PCR) and immunohistochemistry (IHC) methods, respectively. Furthermore, the correlations among the protein levels of different genes, along with the patients' demographic characteristics were assessed. Results  Our findings on mRNA and protein levels demonstrated that the expression of the LMP1 gene in the NPC group was significantly elevated compared with that of the non-NPC group. In addition, the protein levels in the NPC group indicated a positive and significant correlation between LMP1 and VEGF expression. It was noted that both protein and mRNA levels showed no significant differences in the expression of TNF-α and VEGF genes between the NPC and control groups. Furthermore, there was no significant relationship between the expression of these proteins and the demographic characteristics of NPC patients. Conclusion  Overall, a significant increase in LMP1 expression was observed in NPC patients, which may serve as a diagnostic biomarker for NPC. Also, LMP1 might be involved in NPC progression by inducing VEGF gene expression.

Prognostic Value of Serum Transferrin Level before Radiotherapy on Radio-Sensitivity and Survival in Patients with Nasopharyngeal Carcinoma

Purpose: To investigate the prognostic value of serum transferrin (TRF) level before intensity-modulated radiation therapy (IMRT) on radio-sensitivity and overall survival (OS) in patients with nasopharyngeal carcinoma (NPC). Methods: From October 2012 to October 2016, a total of 348 patients with NPC in the First Affiliated Hospital of Fujian Medical University were retrospectively analyzed in our study. The concentration of serum TRF was detected by the method of enzyme-linked immunosorbent assay (ELISA). In the whole group, 46 patients received IMRT, and 302 patients received IMRT plus chemotherapy. The radio-sensitive tumor was defined when the local tumor lesions disappeared completely in the nasopharyngeal MRI scan and no tumor residues were found under the electronic nasopharyngoscope one month after the end of radiotherapy. Results: The serum TRF level before IMRT was (1.34–3.89) g/L, with a median of 2.16 g/L and a mean of (2.20 ± 0.42) g/L. In the whole group, 242 cases (69.5%) were radiosensitive, and 106 cases (30.5%) were insensitive. The number of radiosensitive patients in the group of HTRF (transferrin > 2.16 g/L) and LTRF (transferrin ≤ 2.16 g/L) before radiotherapy was 129 (74.6%) and 113 (64.6%), respectively. The difference in radio-sensitivity between the two groups was statistically significant (χ2 = 4.103, p = 0.043). Logistic regression analysis showed that the level of TRF before radiotherapy (OR = 1.702; 95% CI 1.044~2.775; p = 0.033) was an independent factor for radio-sensitivity. The log-rank test showed that patients in the LTRF group achieved a significantly worse OS (χ2 = 5.388, p = 0.02) than those in the HTRF group. Cox regression analysis showed that baseline TRF level (HR = 1.706; 95% CI 1.065~2.731; p = 0.026) was an independent prognostic factor for overall survival. Conclusions: The low level of TRF before IMRT is a risk factor for radio-sensitivity and a prognostic factor for poor OS in NPC patients. It may be a promising marker to predict radio-sensitivity and OS in NPC patients who accept IMRT.

Profiling of Tumor Cell-Delivered Exosome by Surface Enhanced Raman Spectroscopy-Based Biosensor for Evaluation of Nasopharyngeal Cancer Radioresistance

Although the advancement of radiotherapy significantly improves the survival of nasopharyngeal cancer (NPC), radioresistance associated with recurrence and poor outcomes still remains a daunting challenge in the clinical scenario. Currently, effective biomarkers and convenient detection methods for predicting radioresistance have not been well established. Here, the surface-enhanced Raman spectroscopy combined with proteomics is used to firstly profile the characteristic spectral patterns of exosomes secreted from self-established NPC radioresistance cells, and reveals specific variations of proteins expression during radioresistance formation, including collagen alpha-2 (I) chain (COL1A2) that is associated with a favorable prognosis in NPC and is negatively associated with DNA repair scores and DNA repair-related genes via bioinformatic analysis. Furthermore, deep learning model-based diagnostic model is generated to accurately identify the exosomes from radioresistance group. This work demonstrates the promising potential of exosomes as a novel biomarker for predicting the radioresistance and develops a rapid and sensitive liquid biopsy method that will provide a personalized and precise strategy for clinical NPC treatment.

LncRNA CASC19 Enhances the Radioresistance of Nasopharyngeal Carcinoma by Regulating the miR-340-3p/FKBP5 Axis

Radioresistance remains a serious obstacle encountered in the radiotherapy of nasopharyngeal carcinoma (NPC). Both mRNAs and non-coding RNAs (ncRNAs), including long ncRNA (lncRNA) and microRNA (miRNA), play essential roles in radiosensitivity. However, the comprehensive expression profiles and competing endogenous RNA (ceRNA) regulatory networks among lncRNAs, miRNAs, and mRNAs in NPC radioresistance are still bewildering. In this study, we performed an RNA-sequencing (RNA-seq) assay in the radioresistant NPC cells CNE2R and its parental cells CNE2 to identify the differentially expressed lncRNAs, miRNAs, and mRNAs. The ceRNA networks containing lncRNAs, miRNAs, and mRNAs were predicted on the basis of the Pearson correlation coefficients and authoritative miRanda databases. In accordance with bioinformatic analysis of the data of the tandem mass tag (TMT) assay of CNE2R and CNE2 cells and the gene chip assay of radioresistant NPC samples in pre- and post-radiotherapy, the radioresistance-related signaling network of lncRNA CASC19, miR-340-3p, and FKBP5 was screened and further verified using an RT-qPCR assay. CASC19 was positively associated with FKBP5 expression while negatively correlated with miR-340-3p, and the target binding sites of CASC19/miR-340-3p and miR-340-3p/FKBP5 were confirmed using a dual-luciferase reporter assay. Moreover, using an mRFP-GFP-LC3 maker, it was found that autophagy contributed to the radioresistance of NPC. MiR-340-3p inhibition or FKBP5 overexpression could rescue the suppression of autophagy and radioresistance induced by CASC19 knockdown in CNE2R cells. In conclusion, the CASC19/miR-340-3p/FKBP5 network may be instrumental in regulating NPC radioresistance by enhancing autophagy, which provides potential new therapeutic targets for NPC.

Chrysophanol prevents IL-1β-Induced inflammation and ECM degradation in osteoarthritis via the Sirt6/NF-κB and Nrf2/NF-κB axis

Osteoarthritis (OA) is a common joint illness that negatively impacts people's lives. The main active ingredient of cassia seed or rhubarb is chrysophanol. It has various pharmacological effects including anticancer, anti-diabetes and blood lipid regulation. Previous evidence suggests that chrysophanol has anti-inflammatory properties in various diseases, but its effect on OA has not been investigated yet. In this study, chrysophanol inhibited IL-1β -induced expression of ADAMTS-4, MMP13, COX-2 and iNOS. Meanwhile, it can inhibit aggrecan and collagen degradation in osteoarthritic chondrocytes induced by IL-1β.Further studies depicted that SIRT6 silencing eliminated the chrysophanol effect on IL-1β. The results demonstrated that chrysophanol could stimulate SIRT6 activation and, more importantly, increase SIRT6 levels. We also discovered that chrysophanol might impede the NF-κB pathway of OA mice's chondrocytes induced by IL-1β, which could be because it depends on SIRT6 activation to some extent. It had also been previously covered that chrysophanol could produce a marked effect on Nrf2/NF-κB axis [1]. Therefore, we can infer that chrysophanol may benefit chondrocytes by regulating the SIRT6/NF-κB and Nrf2/NF-κB signaling axis.We examined the anti-inflammatory mechanism and the impact of chrysophanol on mice in vitro and in vivo. In summary, we declare that chrysophanol diminishes the inflammatory reaction of OA in mice in vitro by regulating SIRT6/NF-κB and Nrf2/NF-κB signaling pathway and protects articular cartilage from degradation in vivo. We can infer that chrysophanol could be an efficient therapy for OA.

Silencing lncRNA HCG18 regulates GPX4-inhibited ferroptosis by adsorbing miR-450b-5p to avert sorafenib resistance in hepatocellular carcinoma

Ferroptosis is potential to relieve drug resistance in hepatocellular carcinoma (HCC). Glutathione peroxidase 4 (GPX4) is a critical modulator of ferroptosis. This study discussed the mechanism of GPX4-inhibited ferroptosis in sorafenib resistance in HCC. HCG18 in HCC cells was detected. Sorafenib resistant (SR) cell line Huh7-SR cells were treated with sorafenib (0, 2.5, 5, 7.5, 10 μM). After silencing HCG18 in Huh7-SR cells, cell activity, proliferation and apoptosis were detected. The levels of iron, the concentration of MDA, GSH and lipid reactive oxygen species (ROS) were measured to evaluate the ferroptosis. The downstream mechanism of HCG18 was predicted and verified. Huh7-SR cells were infected with lentivirus sh-HCG18 to establish xenograft tumor model. HCG18 was elevated in HCC cells and associated with sorafenib resistance. Silencing HCG18 inhibited cell proliferation, promoted apoptosis, and impaired sorafenib resistance. Ferroptosis was inhibited in Huh7-SR cells, while silencing HCG18 inhibited sorafenib resistance by promoting ferroptosis. GPX4 overexpression averted the promotion of sh-HCG18 on ferroptosis, thereby reducing sorafenib resistance. HCG18 sponged miR-450b-5p to regulate GPX4. Collectively, Silencing HCG18 inhibits GPX4 by binding to miR-450b-5p, promotes GPX4-inhibited ferroptosis, and averts sorafenib resistance in HCC.

Relationship between miRNA and ferroptosis in tumors

Malignant tumor is a major killer that seriously endangers human health. At present, the methods of treating tumors include surgical resection, chemotherapy, radiotherapy and immunotherapy. However, the survival rate of patients is still very low due to the complicated mechanism of tumor occurrence and development and high recurrence rate. Individualized treatment will be the main direction of tumor treatment in the future. Because only by understanding the molecular mechanism of tumor development and differentially expressed genes can we carry out accurate treatment and improve the therapeutic effect. MicroRNA (miRNA) is a kind of small non coding RNA, which regulates gene expression at mRNA level and plays a key role in tumor regulation. Ferroptosis is a kind of programmed death caused by iron dependent lipid peroxidation, which is different from apoptosis, necrosis and other cell death modes. Now it has been found that ferroptosis plays an important role in the occurrence and development of tumors and drug resistance. More and more studies have found that miRNAs can regulate tumor development and drug resistance through ferroptosis. Therefore, in this review, the mechanism of ferroptosis is briefly outlined, and the relationship between miRNAs and ferroptosis in tumors is reviewed.

Wnt Signaling Modulator DKK4 Inhibits Colorectal Cancer Metastasis through an AKT/Wnt/β-catenin Negative Feedback Pathway

Aberrant activation of the Wnt/β-catenin signaling pathway is implicated in most malignant cancers, especially in the initiation and progression of colorectal cancer (CRC). DKK4 is a classical inhibitory molecule of the Wnt/β-catenin pathway, but its role in CRC is ambiguous, and the molecular mechanism remains unclear. Here, we determined DKK4 expression was significantly upregulated in 23 CRC cell lines and 229 CRC tissues when analyzed by quantitative PCR and immunohistochemistry, respectively. Our analysis of tissue samples indicated the survival time of CRC patients with high DKK4 expression was longer than that of patients with medium-low DKK4 expression. We examined the effects of DKK4 on cell proliferation and metastasis by cell counting kit-8 assays, Transwell assays, and subcutaneous and metastatic mouse tumor models, and we discovered that DKK4 silencing promoted the metastasis of CRC cells both in vitro and in vivo. Our RNA-seq analysis revealed that AKT2, FZD6, and JUN, which play important roles in AKT and Wnt signaling, were significantly increased after DKK4 knockdown. DKK4 represses Wnt/β-catenin signaling by repressing FZD6 and AKT2/s552 β-catenin in CRC. Further experiments revealed recombinant Wnt3a and LiCl could induce DKK4 expression. Moreover, our bioinformatics analysis and luciferase reporter assays identified posttranscriptional regulators of DKK4 in CRC cells. In summary, DKK4 is elevated in CRC and inhibits cell metastasis by a novel negative feedback mechanism of the Wnt3a/DKK4/AKT/s552 β-catenin regulatory axis to restrict overactivation of Wnt activity in CRC. Therefore, DKK4 restoration may be applied as a potential CRC therapeutic strategy.

Protective effect of fluoxetine against oxidative stress induced by renal ischemia-reperfusion injury via the regulation of miR-450b-5p/Nrf2 axis

The present study was performed to assess the protective effect of fluoxetine (FLX) on renal ischemia-reperfusion injury (IRI) via the regulation of miR-450b-5p/Nrf2 axis in male rats. In vivo, these male rats were randomly divided into different treatment groups. The rats were administered with FLX (20 mg/kg, intraperitoneally) once daily for 3 days before operation. The pathomorphological changes of renal tissues were assessed by histological examination and Masson staining. In vitro, HK-2 cells were used to detect the activity by CCK-8 assay in Hypoxia/Reoxygenation (H/R) group and Hypoxia/Reoxygenation+Fluoxetine (H/R+FLX) group. In addition, the oxidative stress biomarkers were evaluated. Subsequently, Nrf2, NF-κB, and Nrf2-dependent antioxidant enzymes, were detected by Western blot assay. In vivo, the pathological changes and serological renal function were significantly relieved in the rats with the pre-treatment of FLX, compared to IRI group. After FLX stimulation, the expression levels of oxidative stress indices significantly decreased, while tissue antioxidant indices significantly increased, compared to IRI group. The differently expressed miRNAs on renal IRI in male rats were screened out by miRNA microarray, especially showing that miR-450b-5p was selected as the target miRNA. Following miR-450b-5p agomir injection, the pathological changes and oxidative stress biomarkers significantly aggravated, whether in IRI group or IRI+FLX group. Bioinformatics analysis and double-luciferase reporter assay demonstrated that miR-450b-5p directly targeted Nrf2. The expression level of NF-κB significantly increased, while the expression levels of Nrf2 and Nrf2-dependent antioxidant enzymes significantly decreased after miR-450b-5p agomir injection. Furthermore, the expression levels of Nrf2 and it-dependent antioxidant enzymes were apparently increased in ischemic kidney after the transfection of miR-450b-5p mimic+recombination protein Nrf2, as well as the decreased expression levels of intracellular ROS and iNOS. In vitro, FLX significantly increased HK-2 cell viability, and relieved H/R HK-2 cell oxidative injury via down-regulating ROS and iNOS. In addition, H/R-induced oxidative damage was recovered with miR-450b-5p mimic and recombination protein Nrf2. Consequently, FLX played an important protective role in renal IRI-induced oxidative damage by promoting antioxidation via targeting miR-450b-5p/Nrf2 axis.

An Axis between the Long Non-Coding RNA HOXA11-AS and NQOs Enhances Metastatic Ability in Oral Squamous Cell Carcinoma

Long non-coding RNAs (lncRNAs) play critical roles in human cancers. HOXA11 anti-sense RNA (HOXA11-AS) is an lncRNA belonging to the homeobox (HOX) gene cluster that promotes liver metastasis in human colon cancer. However, its role and mechanism of action in human oral squamous cell carcinoma (OSCC) are unclear. In this study, we investigated HOXA11-AS expression and function in human OSCC tissues and cell lines, as well as a mouse model of OSCC. Our analyses showed that HOXA11-AS expression in human OSCC cases correlates with lymph node metastasis, nicotinamide adenine dinucleotide (NAD)(P)H: quinone oxidoreductase 1 (NQO1) upregulation, and dihydronicotinamide riboside (NRH): quinone oxidoreductase 2 (NQO2) downregulation. Using the human OSCC cell lines HSC3 and HSC4, we demonstrate that HOXA11-AS promotes NQO1 expression by sponging microRNA-494. In contrast, HOXA11-AS recruits zeste homolog 2 (EZH2) to the NQO2 promoter to suppress its expression via the trimethylation of H3K27. The upregulation of NQO1 enzymatic activity by HOXA11-AS results in the consumption of flavin adenine dinucleotide (FAD), which reduces FAD-requiring glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity and suppresses glycolysis. However, our analyses show that lactic acid fermentation levels are preserved by glutaminolysis due to increased malic enzyme-1 expression, promoting enhanced proliferation, invasion, survival, and drug resistance. In contrast, suppression of NQO2 expression reduces the consumption of NRH via NQO2 enzymatic activity and increases NAD levels, which promotes enhanced stemness and metastatic potential. In mouse tumor models, knockdown of HOXA11-AS markedly suppressed tumor growth and lung metastasis. From these findings, targeting HOXA11-AS may strongly suppress high-grade OSCC by regulating both NQO1 and NQO2.

Circular RNA circPOLR2A promotes clear cell renal cell carcinoma progression by facilitating the UBE3C-induced ubiquitination of PEBP1 and, thereby, activating the ERK signaling pathway

Background

Increasing evidence has demonstrated that circular RNAs (circRNAs) are implicated in cancer progression. However, the aberrant expression and biological functions of circRNAs in clear cell renal cell carcinoma (cRCC) remain largely elusive.

Method

Differentially expressed circRNAs in cRCC were filtered via bioinformatics analysis. Aberrant circPOLR2A expression was validated in cRCC tissues and cell lines via qRT-PCR. Sanger sequencing was used to identify the backsplicing site of circPOLR2A. In vitro and in vivo functional experiments were performed to evaluate the role of circPOLR2A in cRCC malignancy. RNA pull-down, mass spectrometry, RIP, FISH and immunofluorescence assays were used to identify and validate the circPOLR2A-interacting proteins. Ubiquitination modification and interaction between proteins were detected via Co-IP and western blotting. The m6A modification in circPOLR2A was validated by the meRIP assay.

Results

Bioinformatics analysis revealed that circPOLR2A was highly expressed in cRCC tissues and metastatic cRCC tissues. CircPOLR2A expression was associated with tumor size and TNM stage in cRCC patients. In vitro and in vivo functional assays revealed that circPOLR2A accelerated cRCC cell proliferation, migration, invasion and angiogenesis, while inhibiting apoptosis. Further mechanistic research suggested that circPOLR2A could interact with UBE3C and PEBP1 proteins, and that UBE3C could act as a specific ubiquitin E3 ligase for the PEBP1 protein. The UBE3C/circPOLR2A/PEBP1 protein-RNA ternary complex enhanced the UBE3C-mediated ubiquitination and degradation of the PEBP1 protein which could inactivate the ERK signaling pathway. Rescue experiments revealed that the PEBP1 protein was the functional downstream target of circPOLR2A. Furthermore, m6A modification in circPOLR2A was confirmed, and the m6A reader YTHDF2 could regulate circPOLR2A expression.

Conclusion

Our study demonstrated that circPOLR2A modulated the UBE3C-mediated ubiquitination and degradation of the PEBP1 protein, and further activated the ERK pathway during cRCC progression and metastasis. The m6A reader, YTHDF2, regulated circPOLR2A expression in cRCC. Hence, circPOLR2A could be a potential target for the diagnosis and treatment of cRCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01607-8.

Long Intergenic Noncoding RNA 00641 Promotes Growth and Invasion of Colorectal Cancer through Regulating miR-450b-5p/GOLPH3 Axis

Background

Long noncoding RNAs (lncRNAs) have a vital function in tumor onset and progress. For instance, long intergenic noncoding RNA 00641 (LINC00641) has been linked to cancer modulation. Nonetheless, the precise biological roles of LINC00641 in colorectal cancer (CRC) remain elusive.

Methods

The expression levels of LINC00641 as well as the docking sites for LINC00641 and miR-450b-5p were analyzed using public data resources and web-based analytic tools. The putative downstream targets of miR-450b-5p were also predicted. Next, we evaluated the biological functions and the contents of LINC00641 in CRC both in vivo and in vitro. We next explored the influence of LINC00641 on the growth, migration, and infiltration of CRC cells via cell proliferation, migration, and invasion experiments. Besides, qRT-PCR, western blotting, flow cytometry, luciferase enzyme reporter assay, and in vivo tumorigenicity assays were conducted.

Results

Our results confirmed that LINC00641 was markedly upmodulated in CRC tissues and CRC cell lines, and the upmodulation was linked to poor survival. Notably, the proliferative and migratory abilities of HCT-116 and SW480 cells were significantly inhibited by the knockdown of LINC00641 both in vitro and in vivo, illustrating that LINC00641 exerted a tumor-promotion role in CRC. Mechanistically, LINC00641 could competitively bind miR-450b-5p, thereby expunging its inhibitory effect on GOLPH3 expression. Moreover, miR-450-5p and GOLPH3 were able to reverse LINC00641-mediated cellular processes.

Conclusions

Overall, the findings of this study suggest that LINC00641 promotes the proliferative and migratory abilities of CRC through sponging the miR-450b-5p/GOLPH3 axis.

Radiotherapy resistance: identifying universal biomarkers for various human cancers

Radiotherapy (RT) is considered as a standard in the treatment of most solid cancers, including glioblastoma, lung, breast, rectal, prostate, colorectal, cervical, esophageal, and head and neck cancers. The main challenge in RT is tumor cell radioresistance associated with a high risk of locoregional relapse and distant metastasis. Despite significant progress in understanding mechanisms of radioresistance, its prediction and overcoming remain unresolved. This review presents the state-of-the-art for the potential universal biomarkers correlated to the radioresistance and poor outcome in different cancers. We describe radioresistance biomarkers functionally attributed to DNA repair, signal transduction, hypoxia, and angiogenesis. We also focus on high throughput genetic and proteomic studies, which revealed a set of molecular biomarkers related to radioresistance. In conclusion, we discuss biomarkers which are overlapped in most several cancers.

CDKN2B-AS1 promotes the proliferation, clone formation, and invasion of nasopharyngeal carcinoma cells by regulating miR-98-5p/E2F2 axis

OBJECTIVE

To explore the effect of CDKN2B antisense RNA 1 (CDKN2B-AS1) on the proliferation, clone formation, and invasion of nasopharyngeal carcinoma (NPC) cells by regulating miR-98-5p/E2F transcription factor 2 (E2F2) axis.

METHODS

The expressions of CDKN2B-AS1, miR-98-5p, and E2F2 in NPC tissues and cell lines (SUNE-1, 5-8F, 6-10B, and HK-1) as well as in peritumoral normal tissues and cell line NP69 were determined by qRT-PCR. Subcellular localization of CDKN2B-AS1 was detected using the fluorescence in situ hybridization assay. The targeting relationships between CDKN2B-AS1 and miR-98-5p as well as between miR-98-5p and E2F2 were analyzed by the dual-luciferase reporter assay and RNA binding protein immunoprecipitation assay. The proliferation, clone formation and invasion of 5-8F cells were measured using the CCK-8 assay, Clone formation assay, and transwell assay, respectively.

RESULTS

CDKN2B-AS1 was highly expressed in NPC tissues and cells, whereas the expression of miR-98-5p decreased in the NPC tissues and cells. Silencing of CDKN2B-AS1 inhibited the proliferation, clone formation, and invasion of NPC cells (all P<0.05). CDKN2B-AS1 acted asceRNA of miR-98-5p, and miR-98-5p inhibitor could partially reverse the inhibitory effect of silencing CDKN2B-AS1 on NPC cells (all P<0.05). CDKN2B-AS1 upregulated E2F2 by inhibiting miR-98-5p, and the upregulation of E2F2 partially reversed the inhibitory effect of miR-98-5p overexpression on the NPC cells (all P<0.05).

CONCLUSION

CDKN2B-AS1, as a lncRNA, can regulate E2F2 by sponging miR-98-5p to promote the proliferation, clone formation, and invasion of NPC cells.

Cross-link between ferroptosis and nasopharyngeal carcinoma: New approach to radiotherapy sensitization

Ferroptosis is a recently discovered special type of regulated cell death that is strongly associated with both homeostasis maintenance and cancer development. Previous studies have indicated that a number of small-molecular agents inducing ferroptosis have great potential in the treatment of different types of cancer, including breast, pancreatic, prostate and head and neck cancer. However, the role of ferroptosis in nasopharyngeal carcinoma (NPC) has remained to be fully determined. To the best of our knowledge, no review of the currently available studies on this subject has been published to date. The metabolism and expression of specific genes that regulate ferroptosis may represent a promising radiosensitization target in cancer treatment. The aim of the present review was to describe the cross-link between ferroptosis and NPC and to discuss the potential value of regulators and the possible mechanism underlying the role of ferroptosis in the radiosensitization of NPC, in the hope that linking the mechanism of ferroptosis with the development of NPC will accelerate the development of novel ferroptosis-based targets and radiotherapy strategies in NPC.

Properties and gene expression profiling of acquired radioresistance in mouse breast cancer cells

Background

Acquired radioresistant cells exhibit many characteristic changes which may influence cancer progression and further treatment options. The purpose of this study is to investigate the changes of radioresistant human epidermal growth factor receptor 2 (HER2)-positive breast cancer cells on both phenotypic and molecular levels.

Methods

We established an acquired radioresistant cell line from its parental NF639 cell line (HER2-positive) by fractionated radiation and assessed changes in cellular morphology, proliferation, migration, anti-apoptosis activity, basal reactive oxygen species (ROS) level and energy metabolism. RNA-sequencing (RNA-seq) was also used to reveal the potential regulating genes and molecular mechanisms associated with the acquired changed phenotypes. Real-time PCR was used to validate the results of RNA-seq.

Results

The NF639R cells exhibited increased radioresistance and enhanced activity of proliferation, migration and anti-apoptosis, but decreased basal ROS. Two main energy metabolism pathways, mitochondrial respiration and glycolytic, were also upregulated. Furthermore, 490 differentially expressed genes were identified by RNA-seq. Enrichment analysis based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes showed many differently expressed genes were significantly enriched in cell morphology, proliferation, migration, anti-apoptosis, antioxidation, tumor stem cells and energy metabolism and the signaling cascades such as the transforming growth factor-β, Wnt, Hedgehog, vascular endothelial growth factor, retinoic acid-inducible gene I (RIG-I)-like receptor, Toll-like receptor and nucleotide oligomerization domain (NOD)-like receptor were significantly altered in NF639R cells.

Conclusions

In clinical radiotherapy, repeat radiotherapy for short-term recurrence of breast cancer may result in enhanced radioresistance and promote malignant progression. Our research provided hints to understand the tumor resistance to radiotherapy de novo and recurrence with a worse prognosis following radiotherapy.

Flotillin-2 promotes cell proliferation via activating the c-Myc/BCAT1 axis by suppressing miR-33b-5p in nasopharyngeal carcinoma

Previously, we elucidated the function of flotilin-2 (FLOT2) and branched-chain amino acid transaminase 1(BCAT1) in nasopharyngeal carcinoma (NPC). However, the relationship between FLOT2 and BCAT1 in promoting NPC progression remains unknown. Here, we observed that FLOT2 upregulated BCAT1 expression in NPC cells. Ectopic expression of BCAT1 significantly antagonized the inhibitory effects on NPC cell proliferation induced by FLOT2 depletion. Consequently, BCAT1 knockdown markedly inhibited the pro-proliferative effects of FLOT2 overexpression in NPC cells. FLOT2 expression was positively correlated with BCAT1 expression in NPC tissues and was inversely correlated with the prognosis of NPC patients. Mechanistically, FLOT2 maintains the expression level of c-Myc, a positive transcription factor of BCAT1, and subsequently promote BCAT1 transcription. FLOT2 inhibited miR-33b-5p in NPC cells and attenuated its inhibitory effects on c-Myc. Further, experimental validation of the function of the FLOT2/miR-33b-5p/c-Myc/BCAT1 axis in regulating NPC cell proliferation was performed. Our results revealed that FLOT2 promotes NPC cell proliferation by suppressing miR-33b-5p, to maintain proper levels of c-Myc, and upregulate BCAT1trancription. Therefore, the FLOT2/miR-33b-5p/c-Myc/BCAT1 axis is a potential therapeutic target for NPC.

miR‑182‑5p contributes to radioresistance in nasopharyngeal carcinoma by regulating BNIP3 expression

Radioresistance is the primary roadblock limiting the success of treatment of nasopharyngeal carcinoma (NPC). microRNA (miRNA/miR)-182-5p has been reported to affect the sensitivity of cancer cells to irradiation; however, the role of miR-182-5p in NPC has not been assessed. The aim of the present study was to investigate the contribution of miR-182-5p to the radioresistance of NPC cells. The key mRNA and miRNA involved in NPC radioresistance were identified using bioinformatics analysis. The two cell lines used in the present study were 5–8F cells (radio-sensitive) and 5–8F-R cells (radioresistant). A dual-luciferase reporter assay system was used to validate the binding between BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) mRNA and miR-182-5p. Reverse transcription-quantitative PCR and western blotting were used to determine the RNA and protein expression levels. To obtain a deeper insight into the effects of the BNIP3/miR-182-5p axis on NPC radioresistance, Cell Counting Kit-8, wound healing, Transwell invasion and colony formation assays, as well as flow cytometry analysis were performed. The results showed that miR-182-5p and BNIP3 were up and downregulated, respectively, in 5–8F-R cells. BNIP3 was also confirmed to be the target of miR-182-5p, and miR-182-5p reversed the inhibitory effect of BNIP3 in 5–8F-R cells. The cellular experiments showed that upregulation of BNIP3 not only inhibited cell proliferation, viability, invasion and migration, but also promoted the apoptosis of 5–8F-R cells. However, the effects of BNIP3 were attenuated by the simultaneous upregulation of miR-182-5p. Thus, through downregulation of BNIP3, miR-182-5p contributed to radiation resistance of NPC cells.