c-Fos over-expression promotes radioresistance and predicts poor prognosis in malignant glioma

C-FOS inhibition promotes pancreatic cancer cell ferroptosis by transcriptionally regulating the expression of SLC7A11

Cellular proto-oncogene C-Fos forms the AP-1 transcription factor by dimerizing with proto-oncogene c-Jun; this factor upregulates the transcription of genes associated with different malignancies. However, its functions in pancreatic adenocarcinoma (PAAD) remain poorly understood. In this study, the c-Fos was increased in PAAD cells and tissues through bioinformatic analysis, RT-PCR, and WB. In two PAAD cell lines, PANC-1 and BxPC-3, we performed c-Fos knockdown studies using short hairpin RNA (shRNA). Functional analysis indicated that c-Fos depletion in PAAD cells inhibits cell proliferation and promotes ferroptosis. Chromatin Immunoprecipitation (ChIP) and Dual-luciferase experiments showed that c-Fos coupled to the promoter region of SLC7A11 stimulated its transcription, providing mechanistic insight into the process. Moreover, SLC7A11 blocked the decline of proliferation and ferroptosis by c-Fos knockdown in PAAD cells. Furthermore, a xenograft nude mouse model was established to study the impact of c-Fos on tumorigenesis in vivo. Depletion of c-Fos could suppress PC tumor growth and the expressions of SLC7A11, ki-67, and 4HNE, but overexpression of SLC7A11 reversed this process. In summary, our investigation has shown that c-Fos acts as a transcriptional regulator of SLC7A11, which may enhance tumour growth in pancreatic cancer by inhibiting ferroptosis. These results indicate that c-Fos might be a promising target for treating ferroptosis in PAAD.

Role of c-Fos in DNA damage repair

c-Fos, a member of the immediate early gene, serves as a widely used marker of neuronal activation induced by various types of brain damage. In addition, c-Fos is believed to play a regulatory role in DNA damage repair. This paper reviews the literature on c-Fos' involvement in the regulation of DNA damage repair and indicates that genes of the Fos family can be induced by various forms of DNA damage. In addition, cells lacking c-Fos have difficulties in DNA repair. c-Fos is involved in tumorigenesis and progression as a proto-oncogene that maintains cancer cell survival, which may also be related to DNA repair. c-Fos may impact the repair of DNA damage by regulating the expression of downstream proteins, including ATR, ERCC1, XPF, and others. Nonetheless, the underlying mechanisms necessitate further exploration.

Nuclear miRNAs as transcriptional regulators in processes related to various cancers (Review)

MicroRNAs (miRNAs) are noncoding small nucleic acids that contain ~22 nucleotides and are considered to promote the degradation or inhibit the translation of mRNA by targeting its 3'‑untranslated region. However, growing evidence has revealed that nuclear miRNAs, combined with gene promoters or enhancers, are able to directly mediate gene transcription. These miRNAs exert a critical influence on cancer progression by affecting cell growth, migration and invasion. In this review, the direct regulation of gene expression by nuclear miRNAs at the transcriptional level was discussed and summarized, and their mechanisms of action in cancers were highlighted with reference to the various body systems.

Protein arginine methyltransferases (PRMTs): Orchestrators of cancer pathogenesis, immunotherapy dynamics, and drug resistance

Protein Arginine Methyltransferases (PRMTs) are a family of enzymes regulating protein arginine methylation, which is a post-translational modification crucial for various cellular processes. Recent studies have highlighted the mechanistic role of PRMTs in cancer pathogenesis, immunotherapy, and drug resistance. PRMTs are involved in diverse oncogenic processes, including cell proliferation, apoptosis, and metastasis. They exert their effects by methylation of histones, transcription factors, and other regulatory proteins, resulting in altered gene expression patterns. PRMT-mediated histone methylation can lead to aberrant chromatin remodeling and epigenetic changes that drive oncogenesis. Additionally, PRMTs can directly interact with key signaling pathways involved in cancer progression, such as the PI3K/Akt and MAPK pathways, thereby modulating cell survival and proliferation. In the context of cancer immunotherapy, PRMTs have emerged as critical regulators of immune responses. They modulate immune checkpoint molecules, including programmed cell death protein 1 (PD-1), through arginine methylation. Drug resistance is a significant challenge in cancer treatment, and PRMTs have been implicated in this phenomenon. PRMTs can contribute to drug resistance through multiple mechanisms, including the epigenetic regulation of drug efflux pumps, altered DNA damage repair, and modulation of cell survival pathways. In conclusion, PRMTs play critical roles in cancer pathogenesis, immunotherapy, and drug resistance. In this overview, we have endeavored to illuminate the mechanistic intricacies of PRMT-mediated processes. Shedding light on these aspects will offer valuable insights into the fundamental biology of cancer and establish PRMTs as promising therapeutic targets.

Expression data of FOS and JUN genes and FTIR spectra provide diagnosis of thyroid carcinoma

We explore the feasibility of using FOS and JUN gene expression and ATR-FTIR for diagnosis of thyroid cancer. For the study, 38 samples (6 non-neoplastic (NN), 10 papillary thyroid carcinoma (PTC), 7 follicular thyroid carcinoma (FTC), and 15 benign tumors (BT) were subjected to RNA extraction followed by quantitative real time PCR (qRT-PCR) and 30 samples (5 NN, 9 PTC, 5 FTC, and 11 BT) were used for Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) followed by multivariate analysis. Of the above, 20 samples were used for both gene expression and ATR-FTIR studies. We found FOS and JUN expression in malignant tumor samples to be significantly lower than NN and benign. ATR-FIR after multivariate analysis could identify the difficult to diagnose FTC with 93 % efficiency. Overall, results suggest the diagnostic potential of molecular biology techniques combined with ATR-FTIR spectroscopy in differentiated thyroid carcinomas (PTC and FTC) and BT.

FTO up-regulation induced by MYC suppresses tumour progression in Epstein-Barr virus-associated gastric cancer

BACKGROUND

Epstein-Barr virus-associated gastric cancer (EBVaGC) is regarded as a distinct molecular subtype of GC, accounting for approximately 9% of all GC cases. Clinically, EBVaGC patients are found to have a significantly lower frequency of lymph node metastasis and better prognosis than uninfected individuals. RNA N6-methyladenosine (m6A) modification has an indispensable role in modulating tumour progression in various cancer types. However, its impact on EBVaGC remains unclear.

METHODS

Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and m6A dot blot were conducted to compare the m6A modification levels between EBVaGC and EBV-negative GC (EBVnGC) cells. Western blot, real-time quantitative PCR (RT-qPCR) and immunohistochemistry were applied to explore the underlying mechanism of the reduced m6A modification in EBVaGC. The biological function of fat mass and obesity-associated protein (FTO) was determined in vivo and in vitro. The target genes of FTO were screened by MeRIP-seq, RT-qPCR and Western blot. The m6A binding proteins of target genes were verified by RNA pulldown and RNA immunoprecipitation assays. Chromatin immunoprecipitation and Luciferase report assays were performed to investigate the mechanism how EBV up-regulated FTO expression.

RESULTS

M6A demethylase FTO was notably increased in EBVaGC, leading to a reduction in m6A modification, and higher FTO expression was associated with better clinical outcomes. Furthermore, FTO depressed EBVaGC cell metastasis and aggressiveness by reducing the expression of target gene AP-1 transcription factor subunit (FOS). Methylated FOS mRNA was specifically recognized by the m6A 'reader' insulin-like growth factor 2 mRNA binding protein 1/2 (IGF2BP1/2), which enhanced its transcripts stability. Moreover, MYC activated by EBV in EBVaGC elevated FTO expression by binding to a specific region of the FTO promoter.

CONCLUSIONS

Mechanistically, our work uncovered a crucial suppressive role of FTO in EBVaGC metastasis and invasiveness via an m6A-FOS-IGF2BP1/2-dependent manner, suggesting a promising biomarker panel for GC metastatic prediction and therapy.

Physical interaction between STAT3 and AP1 in cervical carcinogenesis: Implications in HPV transcription control

The constitutive activation and aberrant expression of Signal Transducer and Activator of Transcription 3 (STAT3) plays a key role in initiation and progression of cervical cancer (CaCx). How STAT3 influences HPV transcription is poorly defined. In the present study, we probed direct and indirect interactions of STAT3 with HPV16/18 LCR. In silico assessment of cis-elements present on LCR revealed the presence of potential STAT3 binding motifs. However, experimental validation by ChIP-PCR could not confirm any specific STAT3 binding on HPV16 LCR. Protein-protein interaction (PPI) network analysis of STAT3 with other host transcription factors that bind LCR, highlighted the physical association of STAT3 with c-FOS and c-JUN. This was further confirmed in vitro by co-immunoprecipitation, where STAT3 co-immunoprecipitated with c-FOS and c-JUN in CaCx cells. The result was supported by immunocytochemical analysis and colocalization of STAT3 with c-FOS and c-JUN. Positive signals in proximity ligation assay validated physical interaction and colocalization of STAT3 with AP1. Colocalization of STAT3 with c-FOS and c-JUN increased upon IL-6 treatment and decreased post-Stattic treatment. Alteration of STAT3 expression affected the subcellular localization of c-FOS and c-JUN, along with the expression of viral oncoproteins (E6 and E7) in CaCx cells. High expression of c-JUN in tumor tissues correlated with poor prognosis in both HPV16 and HPV18 CaCx cohort whereas high expression of STAT3 correlated with poor prognosis in HPV18 CaCx lesions only. Overall, the data suggest an indirect interaction of STAT3 with HPV LCR via c-FOS and c-JUN and potentiate transcription of viral oncoproteins.

Protection of c-Fos from autophagic degradation by PRMT1-mediated methylation fosters gastric tumorigenesis

Both AP-1 and PRMT1 are vital molecules in variety of cellular progresssion, but the interaction between these proteins in the context of cellular functions is less clear. Gastric cancer (GC) is one of the pernicious diseases worldwide. An in-depth understanding of the molecular mode of action underlying gastric tumorigenesis is still elusive. In this study, we found that PRMT1 directly interacts with c-Fos and enhances AP-1 activation. PRMT1-mediated arginine methylation (mono- and dimethylation) of c-Fos synergistically enhances c-Fos-mediated AP-1 liveliness and consequently increases c-Fos protein stabilization. Consistent with this finding, PRMT1 knockdown decreases the protein level of c-Fos. We discovered that the c-Fos protein undergoes autophagic degradation and found that PRMT1-mediated methylation at R287 protects c-Fos from autophagosomal degradation and is linked to clinicopathologic variables as well as prognosis in stomach tumor. Together, our data demonstrate that PRMT1-mediated c-Fos protein stabilization promotes gastric tumorigenesis. We contend that targeting this modification could constitute a new therapeutic strategy in gastric cancer.

Ligand-Gated Ion Channels: Prognostic and Therapeutic Implications for Gliomas

Gliomas are common primary brain malignancies that remain difficult to treat due to their overall aggressiveness and heterogeneity. Although a variety of therapeutic strategies have been employed for the treatment of gliomas, there is increasing evidence that suggests ligand-gated ion channels (LGICs) can serve as a valuable biomarker and diagnostic tool in the pathogenesis of gliomas. Various LGICs, including P2X, SYT16, and PANX2, have the potential to become altered in the pathogenesis of glioma, which can disrupt the homeostatic activity of neurons, microglia, and astrocytes, further exacerbating the symptoms and progression of glioma. Consequently, LGICs, including purinoceptors, glutamate-gated receptors, and Cys-loop receptors, have been targeted in clinical trials for their potential therapeutic benefit in the diagnosis and treatment of gliomas. In this review, we discuss the role of LGICs in the pathogenesis of glioma, including genetic factors and the effect of altered LGIC activity on the biological functioning of neuronal cells. Additionally, we discuss current and emerging investigations regarding the use of LGICs as a clinical target and potential therapeutic for gliomas.

The Role of Hyperexcitability in Gliomagenesis

Glioblastoma is the most common malignant primary brain tumor. Recent studies have demonstrated that excitatory or activity-dependent signaling-both synaptic and non-synaptic-contribute to the progression of glioblastoma. Glutamatergic receptors may be stimulated via neuron-tumor synapses or release of glutamate by the tumor itself. Ion currents generated by these receptors directly alter the structure of membrane adhesion molecules and cytoskeletal proteins to promote migratory behavior. Additionally, the hyperexcitable milieu surrounding glioma increases the rate at which tumor cells proliferate and drive recurrent disease. Inhibition of excitatory signaling has shown to effectively reduce its pro-migratory and -proliferative effects.

NQO1 regulates cell cycle progression at the G2/M phase

Rationale: Overexpression of NAD(P)H:quinone oxidoreductase 1 (NQO1) is associated with tumor cell proliferation and growth in several human cancer types. However, the molecular mechanisms underlying the activity of NQO1 in cell cycle progression are currently unclear. Here, we report a novel function of NQO1 in modulation of the cell cycle regulator, cyclin-dependent kinase subunit-1 (CKS1), at the G2/M phase through effects on the stability of c‑Fos. Methods: The roles of the NQO1/c-Fos/CKS1 signaling pathway in cell cycle progression were analyzed in cancer cells using synchronization of the cell cycle and flow cytometry. The mechanisms underlying NQO1/c-Fos/CKS1-mediated regulation of cell cycle progression in cancer cells were studied using siRNA approaches, overexpression systems, reporter assays, co-immunoprecipitation, pull-down assays, microarray analysis, and CDK1 kinase assays. In addition, publicly available data sets and immunohistochemistry were used to investigate the correlation between NQO1 expression levels and clinicopathological features in cancer patients. Results: Our results suggest that NQO1 directly interacts with the unstructured DNA-binding domain of c-Fos, which has been implicated in cancer proliferation, differentiation, and development as well as patient survival, and inhibits its proteasome-mediated degradation, thereby inducing CKS1 expression and regulation of cell cycle progression at the G2/M phase. Notably, a NQO1 deficiency in human cancer cell lines led to suppression of c-Fos-mediated CKS1 expression and cell cycle progression. Consistent with this, high NQO1 expression was correlated with increased CKS1 and poor prognosis in cancer patients. Conclusions: Collectively, our results support a novel regulatory role of NQO1 in the mechanism of cell cycle progression at the G2/M phase in cancer through effects on c‑Fos/CKS1 signaling.

Diallyl Disulfide Induces Chemosensitization to Sorafenib, Autophagy, and Cell Cycle Arrest and Inhibits Invasion in Hepatocellular Carcinoma

Hepatocellular carcinoma is the seventh most common type of cancer in the world, with limited treatment options. A promising strategy to treat cancer is to associate chemotherapeutics and plant bioactive compounds. Here, we examined whether diallyl disulfide (DADS; 50-200 μM) and sorafenib (SORA; 8 μM), either alone or in combination, were toxic to hepatocellular carcinoma cells (HepG2) in vitro. We assessed whether DADS and/or SORA induced cell death (LIVE/DEAD assay and autophagy) and cell cycle changes (flow cytometry), altered expression of key genes and proteins (RT-qPCR and Western blot), and modulated tumorigenesis signatures, such as proliferation (clonogenic assay), migration (wound healing), and invasion (inserts). The DADS + SORA combination elicited autophagic cell death by upregulating LC3 and NRF2 expression and downregulating FOS and TNF expression; induced the accumulation of cells in the G1 phase which thereby upregulated the CHEK2 expression; and inhibited invasion by downregulating the MMP2 expression. Predictive analysis indicated the participation of the MAPK pathway in the reported results. The DADS + SORA combination suppressed both cell invasion and clonogenic survival, which indicated that it dampened tumor growth, proliferation, invasion, and metastatic potential. Therefore, the DADS + SORA combination is a promising therapy to develop new clinical protocols.

Expression and potential role of FOSB in glioma

Background

FOSB is reported to be an oncogene in a variety of tumors. However, the expression and role of FOSB in glioma remain obscure. In this study, we aimed to explore the expression of FOSB in glioma and its biological role in glioblastoma multiforme (GBM).

Methods

Western blot, immunohistochemical staining, and quantitative real-time polymerase chain reaction (RT-qPCR) were used to detect the expression of FOSB in clinical samples. FOSB was knocked down in cells to determine the effects of FOSB on the phenotypic changes of tumors by plate cloning, CCK-8 assay, and Transwell assay. Finally, subcutaneous tumorigenesis in nude mice was used to observe the tumorigenesis of glioma cell lines after the knockdown of the FOSB gene.

Results

FOSB expression was higher in glioma compared with normal brain tissue. After the downregulation of FOSB, the expression of cleaved caspase-3 increased. Plate cloning and CCK-8 experiments showed that the proliferation of glioma cell lines decreased. The Transwell assay demonstrated that the glioblastoma cell lines had lower migration ability after the knockdown of FOSB. Finally, the tumor volume of U87 glioma cells in group sh-FOSB was smaller than that in the control group. The TUNEL staining in vitro showed that the apoptosis of sh-FOSB glioma cells increased.

Conclusion

FOSB was highly expressed in glioma tissues. The viability of glioma cells decreased, and the ability of glioma cells to proliferate and migrate was reduced when FOSB was downregulated. Hence, FOSB may promote the development and migration of gliomas.

Biophysical insights into OR2T7: Investigation of a potential prognostic marker for glioblastoma

Glioblastoma multiforme (GBM) is the most aggressive and prevalent form of brain cancer, with an expected survival of 12-15 months following diagnosis. GBM affects the glial cells of the central nervous system, which impairs regular brain function including memory, hearing, and vision. GBM has virtually no long-term survival even with treatment, requiring novel strategies to understand disease progression. Here, we identified a somatic mutation in OR2T7, a G-protein-coupled receptor (GPCR), that correlates with reduced progression-free survival for glioblastoma (log rank p-value = 0.05), suggesting a possible role in tumor progression. The mutation, D125V, occurred in 10% of 396 glioblastoma samples in The Cancer Genome Atlas, but not in any of the 2504 DNA sequences in the 1000 Genomes Project, suggesting that the mutation may have a deleterious functional effect. In addition, transcriptome analysis showed that the p38α mitogen-activated protein kinase (MAPK), c-Fos, c-Jun, and JunB proto-oncogenes, and putative tumor suppressors RhoB and caspase-14 were underexpressed in glioblastoma samples with the D125V mutation (false discovery rate < 0.05). Molecular modeling and molecular dynamics simulations have provided preliminary structural insight and indicate a dynamic helical movement network that is influenced by the membrane-embedded, cytofacial-facing residue 125, demonstrating a possible obstruction of G-protein binding on the cytofacial exposed region. We show that the mutation impacts the "open" GPCR conformation, potentially affecting Gα-subunit binding and associated downstream activity. Overall, our findings suggest that the Val125 mutation in OR2T7 could affect glioblastoma progression by downregulating GPCR-p38 MAPK tumor-suppression pathways and impacting the biophysical characteristics of the structure that facilitates Gα-subunit binding. This study provides the theoretical basis for further experimental investigation required to confirm that the D125V mutation in OR2T7 is not a passenger mutation. With validation, the aforementioned mutation could represent an important prognostic marker and a potential therapeutic target for glioblastoma.

The DNA Double-Strand Break Repair in Glioma: Molecular Players and Therapeutic Strategies

Gliomas are the most frequent type of tumor in the central nervous system, which exhibit properties that make their treatment difficult, such as cellular infiltration, heterogeneity, and the presence of stem-like cells responsible for tumor recurrence. The response of this type of tumor to chemoradiotherapy is poor, possibly due to a higher repair activity of the genetic material, among other causes. The DNA double-strand breaks are an important type of lesion to the genetic material, which have the potential to trigger processes of cell death or cause gene aberrations that could promote tumorigenesis. This review describes how the different cellular elements regulate the formation of DNA double-strand breaks and their repair in gliomas, discussing the therapeutic potential of the induction of this type of lesion and the suppression of its repair as a control mechanism of brain tumorigenesis.

Kaempferol sensitizes cell proliferation inhibition in oxaliplatin-resistant colon cancer cells

Resolution to chemoresistance is a major challenge in patients with advanced-stage malignancies. Thus, identification of action points and elucidation of molecular mechanisms for chemoresist human cancer are necessary to overcome this challenge. In this study, we provide important evidence that kaempferol targeting RSKs might be a strategy to reduce the oxaliplatin-resistant colon cancer cells. We found that MAPK and PI3K-AKT signaling were increased in oxaliplatin (Ox)-resistant HCT116 (HCT116-Ox^R) cells compared to Ox-sensitive HCT116 (HCT116-Ox^S) cells. Comparison of cell sensitivities using SP600125 (JNK inhibitor), SB206580 (p38 kinase inhibitor), or MK-2206 (AKT inhibitor) revealed that cell proliferation inhibition was strongly observed in HT29 cells compared to that in HCT116 cells in both Ox^S and Ox^R cells. Interestingly, SP600125, SB206580, and MK-2206 treatment showed higher cell proliferation inhibition in Ox^S cells than that in Ox^R cells in both HCT116 and HT29 cells, except following treatments with 10 µM of SP600125, and 30 µM of SB206580. In comparison to magnolin and aschantin, kaempferol showed the strongest inhibitory effect on cell proliferation in both HCT116 and HT29 cells. Importantly, HCT116- and HT29-Ox^R cells showed higher sensitivities to cell proliferation inhibition than those of HCT116- and HT29-Ox^S cells, resulting in the accumulation of cells at the G₂/M-phases of the cell cycle. Finally, we showed that AP-1 transactivation activity was markedly decreased by kaempferol in HCT116- and HT29-Ox^R cells compared to the activity levels in HCT116- and HT29-Ox^S cells. Taken together, the results demonstrate that kaempferol-mediated AP-1 inhibition might be an important signaling mechanism to resolve the chemoresistance of Ox-resistant colon cancer cells.

MiR-744 Functions as an Oncogene Through Direct Binding to c-Fos Promoter and Facilitates Non-small Cell Lung Cancer Progression

Metastasis is the leading cause of death in non-small cell lung cancer (NSCLC) patients. Previously, we reported that miR-744 exerted proto-oncogenic function in nasopharyngeal carcinoma, but the role of miR-744 during NSCLC development has not been established. We focused on the function and molecular mechanism of miR-744 in NSCLC. The clinical cohort data from TCGA were analyzed for the correlation of miR-744 and outcomes in NSCLC patients. Gain- and loss-of-function experiment was performed by transfection with miR-744 agomir or antagomir in NSCLC cell lines. The expression of mRNA and protein were analyzed by qPCR assays and Western blotting respectively. Cellular proliferation, migration, and invasion were analyzed by CCK8 assays, wound healing, and transwell assays, respectively. Promoter activities and gene transcription were analyzed by luciferase reporter assays. Xenograft model was applied for in vivo study. High miR-744 expression correlated with lymph node metastasis and poor prognosis in NSCLC patient. MiR-744 aggravated the growth, invasion, and metastasis of NSCLC cells eventually induced the malignant phenotype and promotes radio/chemoresistance in vitro. The -1195 to -1227 and -298 to -323 bp upstream of c-FOS gene was observed to bind with miR-744. Lastly, miR-744 acted as a tumor promoter in lung cancer growth and metastasis in vivo. Taken together, our results indicated that miR-744 up-regulated c-Fos by binding with its promoter contributed to development of NSCLC cells malignant phenotype. Our findings highlight the potential value of miR-744, which may serve as a possible therapeutic target for NSCLC.

Network pharmacological mechanism of Cinobufotalin against glioma

OBJECTIVE

Cinobufotalin was extracted from the skin of Chinese giant salamander or black sable with good clinical effect against tumor. This study aims to explore the mechanism of Cinobufotalin components and predict the target of action of Cinobufotalin on glioma.

METHODS

The active components of Cinobufotalin were screened by the Chinese medicine pharmacology database and analysis platform (TCMSP), PubChem database, etc. The potential molecular components and targets were identified and enrichment analysis was conducted through the construction of related networks and analysis of their characteristics. Relevant targets of glioma were searched through TTD, DRUGBANK, and other databases, and the intersection was found and the key targets were found too.

RESULTS

A total of 21 active components and 184 target genes of Cinobufotalin were found. According to the enrichment analysis results, the pharmacological mechanism of Cinobufotalin mainly includes inhibition of the cell cycle, promotion of cell apoptosis, and regulation of immunity. On this basis, RAC1, FOS, and NOS3 can be preliminarily predicted as potential targets of Cinobufotalin in the treatment of glioma.

CONCLUSIONS

The screening of active ingredients and target prediction based on network pharmacology can provide a new research idea for the multi-target treatment of glioma with Cinobufotalin.

Exploring the Pharmacological Mechanism of Radix Salvia Miltiorrhizae in the Treatment of Radiation Pneumonia by Using Network Pharmacology

Background

Radiation pneumonia (RP) is the most common complication of radiotherapy to the thorax and seriously affects the survival rate and quality of life of patients. Radix Salviae Miltiorrhizae (RSM) is an ancient Chinese medicine, whose main pharmacological effect is to promote blood circulation and remove stasis. A growing number of studies have proved that RSM has a good effect on RP. However, the underlying mechanism is still unclear and needs to be fully elucidated.

Methods

The effective components and predictive targets of RSM were analyzed by Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, and the related targets of RP were predicted by GeneCards database. The common targets of the two targets mentioned above were analyzed by protein-protein interaction on the STRING website, GO and KEGG analysis on the DAVID website, visualization by CytoScape3.7.0, and screening for Hubber gene by cytoHubber plug-in.

Results

A search of the TCMSP database revealed that RSM contains 65 chemical constituents and 165 potential protein targets. A total of 2,162 protein targets were found to be associated with RP. The top 10 hub genes were obtained by MCC algorithm for 70 common genes, including TP53, CASP3, MAPK1, JUN, VEGFA, STAT3, PTGS2, IL6, AKT1, and FOS. By analyzing the Gene Ontology, The anti-radiation pneumonia effect of RSM is that it performs molecular functions (protein homodimerization activity) in the nucleus through three biological processes (positive regulation of transcription from RNA polymerase II promoter,Extrinsic apoptotic signaling pathway in absence of ligand and lipopolysaccharide-mediated signaling pathway). Through KEGG analysis, the mechanism of RSM treatment of radiation pneumonia may be through PI3K-Akt, HIF-1, TNF signaling pathways.

Conclusions

Through network pharmacology analysis, we found the possible target genes of RSM on RP and revealed the most likely signaling pathway, providing theoretical basis for further elucidating the potential mechanism of RSM on RP.

In Vitro Effects of Propofol on Cytotoxic, Apoptotic and PI3K-Akt Signaling Pathway Genes on Brain Cancer Cells

AIM

It was aimed to determine the cytotoxic and apoptotic effect of propofol on glioma cells.

BACKGROUND

Propofol [2,6-diisopropylphenol] is a commonly used intravenous anesthetic. Propofol is known to have a mechanism of action on the PI3K-AKT pathway.

OBJECTIVE

This study aimed to evaluate the effect of propofol on the proliferation and apoptosis of human glioma cells, as well as to investigate changes in expression levels of the PI3K-AKT signaling pathway genes.

MATERIALS-METHODS

The cytotoxic effect of propofol on the U-87 MG cell line was determined by WST-1 method. Annexin V-FITC and Mitoprobe JC-1 assay were used to measure apoptosis by flow cytometry. Expression levels of genes in the PI3K-AKT signaling pathway were investigated by qRT-PCR.

RESULTS

We have shown that propofol-induced apoptosis in U-87 MG cells by 17.1-fold compared to untreated control. Furthermore, significant differences were found in the expression levels of the PI3K-AKT signaling pathway genes.

CONCLUSION

As a result of our study, it was found that propofol caused differences in expression levels of PI3K-AKT signaling pathway genes, and it was suggested that these differences might be related to apoptosis induction.

Gammacoronavirus Avian Infectious Bronchitis Virus and Alphacoronavirus Porcine Epidemic Diarrhea Virus Exploit a Cell-Survival Strategy via Upregulation of cFOS to Promote Viral Replication

Coronaviruses have evolved a variety of strategies to optimize cellular microenvironment for efficient replication. In this study, we report the induction of AP-1 transcription factors by coronavirus infection based on genome-wide analyses of differentially expressed genes in cells infected with avian coronavirus infectious bronchitis virus (IBV). Most members of the AP-1 transcription factors were subsequently found to be upregulated during the course of IBV and porcine epidemic diarrhea virus (PEDV) infection of cultured cells as well as in IBV-infected chicken embryos. Further characterization of the induction kinetics and functional roles of cFOS in IBV replication demonstrated that upregulation of cFOS at early to intermediate phases of IBV replication cycles suppresses IBV-induced apoptosis and promotes viral replication. Blockage of nuclear translocation of cFOS by peptide inhibitor NLSP suppressed IBV replication and apoptosis, ruling out the involvement of the cytoplasmic functions of cFOS in the replication of IBV. Furthermore, knockdown of ERK1/2 and inhibition of JNK and p38 kinase activities reduced cFOS upregulation and IBV replication. This study reveals an important function of cFOS in the regulation of coronavirus-induced apoptosis, facilitating viral replication.IMPORTANCE The ongoing pandemic of coronavirus disease 2019 (COVID-19), caused by a newly emerged zoonotic coronavirus (SARS-CoV-2), highlights the importance of coronaviruses as human and animal pathogens and our knowledge gaps in understanding the cellular mechanisms, especially mechanisms shared among human and animal coronaviruses, exploited by coronaviruses for optimal replication and enhanced pathogenicity. This study reveals that upregulation of cFOS, along with other AP-1 transcription factors, as a cell-survival strategy is such a mechanism utilized by coronaviruses during their replication cycles. Through induction and regulation of apoptosis of the infected cells at early to intermediate phases of the replication cycles, subtle but appreciable differences in coronavirus replication efficiency were observed when the expression levels of cFOS were manipulated in the infected cells. As the AP-1 transcription factors are multi-functional, further studies of their regulatory roles in proinflammatory responses may provide new insights into the pathogenesis and virus-host interactions during coronavirus infection.

UBE2N Regulates Paclitaxel Sensitivity of Ovarian Cancer via Fos/P53 Axis

Background

Chemo-resistance is still considered one of the key factors in the mortality of ovarian cancer. In this work, we found that ubiquitin-conjugating enzyme E2 N (UBE2N) is downregulated in paclitaxel-resistant ovarian cancer cells. It suggests UBE2N to be critical in the regulation of paclitaxel sensitivity in ovarian cancer.

Materials and Methods

Ovarian cancer cells with stably overexpressed UBE2N were injected into nude mice to assess tumor growth and paclitaxel sensitivity in vivo. The MTT assay was applied to observe the effect of UBE2N expression on paclitaxel sensitivity. A real-time PCR array, specific for human cancer drug resistance, was used to examine the potential downstream target genes of UBE2N. The expression of UBE2N and potential downstream target genes was determined by Western blotting. The analysis of Gene Ontology and protein–protein interactions of these differentially expressed genes (DEGs) was performed using online tools. To evaluate the prognostic value of hub genes expression for ovarian cancer patients treated with paclitaxel, we applied the online survival analysis tool.

Results

Overexpressed UBE2N enhanced the paclitaxel sensitivity of ovarian cancer cells in vitro and in vivo. Thirteen upregulated DEGs and 11 downregulated DEGs were identified when we knockdown UBE2N. Meanwhile, 9 hub genes with a high degree of connectivity were selected. Only Fos proto-oncogene, AP-1 transcription factor subunit (Fos), was overexpressed upon decreasing UBE2N levels, indicating a poor outcome for patients treated with paclitaxel. Moreover, reduced UBE2N could increase Fos expression and reduce P53. Furthermore, reversed regulation of Fos and P53 based on UBE2N reduction could reverse paclitaxel sensitivity, respectively.

Conclusion

Our study suggests that UBE2N could be used as a therapeutic agent for paclitaxel-resistant ovarian cancer through Fos/P53 pathway. Further studies are needed to elucidate the specific mechanism.

Boswellic Acid Synergizes With Low-Level Ionizing Radiation to Modulate Bisphenol Induced-Lung Toxicity in Rats by Inhibiting JNK/ERK/c-Fos Pathway

Bisphenol A (BPA) is a low molecular weight chemical compound that has a deleterious effect on the endocrine system. It was used in plastics manufacturing with injurious effects on different body systems. Occupational exposure to low-level ionizing radiation (<1 Gy) is shown to attenuate an established inflammatory process and therefore enhance cell protection. Therefore, the objective of this study was to investigate the protective effect of boswellic acid (BA) accompanied by whole-body low-dose gamma radiation (γ-R) against BPA-induced lung toxicity in male albino rats. BPA intoxication induced with 500 mg/kg BW. Rats received 50 mg BA/kg BW by gastric gavage concomitant with 0.5 Gy γ-R over 4 weeks. The immunoblotting and biochemical results revealed that BA and/or γ-R inhibited BPA-induced lung toxicity by reducing oxidative damage biomolecules; (MDA and NADPH oxidase gene expression), inflammatory indices (MPO, TNF-α, IL-6, and gene expression of CXCR-4). Moreover, BA and or/γ-R ameliorated the lung inflammation via regulation of the JNK/ERK/c-Fos and Nrf2/ HO-1 signaling pathways. Interestingly, our data demonstrated that BA in synergistic interaction with γ-R is efficacious control against BPA-induced lung injury via anti-oxidant mediated anti-inflammatory activities.

PSMB8 inhibition decreases tumor angiogenesis in glioblastoma through vascular endothelial growth factor A reduction

Glioblastoma, also known as glioblastoma multiforme (GBM), is a fast‐growing tumor and the most aggressive brain malignancy. Proteasome subunit beta type‐8 (PSMB8) is one of the 17 essential subunits for the complete assembly of the 20S proteasome complex. The aim of the present study was to evaluate the role of PSMB8 expression in GBM progression and angiogenesis. PSMB8 expression in glioblastoma LN229 and U87MG was knocked down by siRNA or inducible shRNA both in vitro and in vivo. After PSMB8 reduction, cell survival, migration, invasion, angiogenesis, and the related signaling cascades were evaluated. An orthotopic mouse tumor model was also provided to examine the angiogenesis within tumors. A GEO profile analysis indicated that high expression of PSMB8 mRNA in GBM patients was correlated with a low survival rate. In immunohistochemistry analysis, PSMB8 expression was higher in high‐grade than in low‐grade brain tumors. The proliferation, migration, and angiogenesis of human GBM cells were decreased by PSMB8 knockdown in vitro. Furthermore, phosphorylated focal adhesion kinase (p‐FAK), p‐paxillin, MMP2, MMP9, and cathepsin B were significantly reduced in LN229 cells. Integrin β1 and β3 were reduced in HUVEC after incubation with LN229‐conditioned medium. In an orthotopic mouse tumor model, inducible knockdown of PSMB8 reduced the expression of vascular endothelial growth factor (VEGF), VEGF receptor, and CD31 as well as the progression of human glioblastoma. In this article, we demonstrated the role of PSMB8 in glioblastoma progression, especially neovascularization in vitro and in vivo. These results may provide a target for the anti–angiogenic effect of PSMB8 in glioblastoma therapy in the future.

Hypoxia-induced downregulation of B-cell translocation gene 3 confers resistance to radiation therapy of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is now a major human cancer, and B-cell translocation gene 3 (BTG3) has been reported as a tumor-suppressor in CRC, but its upstream regulator has not been identified.

METHODS

Endogenous expression levels of BTG3 were compared between normal colorectal cell line CCD-18Co and two CRC cell lines SW480 and HT29, as well as between CRC patient tumor and adjacent normal tissues. Analysis of BTG3 genomic region was performed which identified a putative hypoxia response element (HRE). Effects of hypoxia condition, BTG3 overexpression, and their combination on the radiation sensitivity of CRC cell lines were assessed.

RESULTS

BTG3 was downregulated in CRC cell lines and patient tumor samples, via the HRE in its promoter region. Hypoxia and BTG3 overexpression could both induce radiation resistance in CRC cells. Combining hypoxia with BTG3 overexpression effectively rendered the resistance of CRC cells to radiation to a level lower than hypoxia alone and higher than normoxia alone, indicating the essential role of BTG3 in hypoxia-induced radiation resistance of CRC cells.

CONCLUSION

We therefore propose a novel signaling cascade involving hypoxia/BTG3 to be a potential risk factor for CRC patients undergoing radiation therapy, which could possibly serve as therapeutic targets among CRC patients with acquired radiotherapy resistance.

Transregulation of microRNA miR-21 promoter by AP-1 transcription factor in cervical cancer cells

BACKGROUND

Gene expression profiles have demonstrated that miR-21 expression is altered in almost all types of cancers and it has been classified as an oncogenic microRNA. Persistent HPV infection is the main etiologic agent in cervical cancer and induces genetic instability, including disruption of microRNA gene expression. In the present study, we analyzed the underlying mechanism of how AP-1 transcription factor can active miR-21 gene expression in cervical cancer cells.

METHODS

To identify that c-Fos and c-Jun regulate the expression of miR-21 we performed RT-qPCR and western blot assays. We analyzed the interaction of AP-1 with miR-21 promoter by EMSA and ChIP assays and determined the mechanism of its regulation by reporter construct plasmids. We identified the nuclear translocation of c-Fos and c-Jun by immunofluorescence microscopy assays.

RESULTS

We demonstrated that c-Fos and c-Jun proteins are expressed and regulate the expression of miR-21 in cervical cancer cells. DNA sequence analysis revealed the presence of AP-1 DNA-binding sites in the human miR-21 promoter region. EMSA analyses confirmed the interactions of the miR-21 upstream transcription factor AP-1. ChIP assays further showed the binding of c-Fos to AP-1 sequences from the miR-21 core promoter in vivo. Functional analysis of AP-1 sequences of miR-21 in reporter plasmids demonstrated that these sequences increase the miR-21 promoter activation.

CONCLUSIONS

Our findings suggest a physical interaction and functional cooperation between AP-1 transcription factor in the miR-21 promoter and may explain the effect of AP-1 on miR-21 gene expression in cervical cancer cells.

Dihydrocapsaicin Inhibits Epithelial Cell Transformation through Targeting Amino Acid Signaling and c-Fos Expression

Chili peppers are one of the most widely consumed spices worldwide. However, research on the health benefits of chili peppers and some of its constituents has raised controversy as to whether chili pepper compounds possess cancer-promoting or cancer-preventive effects. While ample studies have been carried out to examine the effect of capsaicin in carcinogenesis, the chemopreventive effect of other major components in chili pepper, including dihydrocapsaicin, capsiate, and capsanthin, is relatively unclear. Herein, we investigated the inhibitory effect of chili pepper components on malignant cell transformation. Among the tested chili pepper compounds, dihydrocapsaicin displayed the strongest inhibitory activity against epidermal growth factor (EGF)-induced neoplastic transformation. Dihydrocapsaicin specifically suppressed EGF-induced phosphorylations of the p70S6K1-S6 pathway and the expression of c-Fos. A reduction in c-Fos levels by dihydrocapsaicin led to a concomitant downregulation of AP-1 activation. Further analysis of the molecular mechanism responsible for the dihydrocapsaicin-mediated decrease in phospho-p70S6K1, revealed that dihydrocapsaicin can block amino acid-dependent mechanistic targets of rapamycin complex 1 (mTORC1)-p70S6K1-S6 signal activation. Additionally, dihydrocapsaicin was able to selectively augment amino acid deprivation-induced cell death in mTORC1-hyperactive cells. Collectively, dihydrocapsaicin exerted chemopreventive effects through inhibiting amino acid signaling and c-Fos pathways and, thus, might be a promising cancer preventive natural agent.

NMDA Receptor Signaling Mediates cFos Expression via Top2β-Induced DSBs in Glioblastoma Cells

The activation of Ca2+-permeable N-methyl-D-aspartic acid (NMDA) receptor channels (NMDARs) is crucial for the development and survival of neurons, but many cancers use NMDAR-mediated signaling as well, enhancing the growth and invasiveness of tumors. Thus, NMDAR-dependent pathways emerge as a promising target in cancer therapy. Here, we use the LN229 and U-87MG glioblastoma multiforme (GBM) cells and immunofluorescence staining of 53BP1 to analyze NMDAR-induced DNA double-strand breaks (DSBs), which represent an important step in the NMDAR signaling pathway in neurons by facilitating the expression of early response genes. Our results show that NMDAR activation leads to the induction of DSBs in a subpopulation of glioma cells. In a further analogy to neurons, our results demonstrate that the induction of DSBs in LN229 cells is dependent on the activity of topoisomerase IIβ (Top2β). Western blot analysis revealed that the inhibition of NMDARs, cAMP-responsive element binding transcription factor (CREB) and Top2β decreased the expression of the proto-oncogene cFos. Knockdown of Top2β with siRNAs resulted in a downregulation of cFos and increased the radiosensitivity of LN229 cells in clonogenic survival. We also observed impaired cFos expression upon NMDAR and Top2β inhibition in a primary GBM cell line, suggesting that NMDAR signaling may be widely used by GBMs, demonstrating the potential of targeting NMDAR signaling proteins for GBM therapy.

OKN-007 Increases temozolomide (TMZ) Sensitivity and Suppresses TMZ-Resistant Glioblastoma (GBM) Tumor Growth

Treatment of glioblastoma (GBM) remains a challenge using conventional chemotherapy, such as temozolomide (TMZ), and is often ineffective as a result of drug resistance. We have assessed a novel nitrone-based agent, OKN-007, and found it to be effective in decreasing tumor volumes and increasing survival in orthotopic GBM xenografts by decreasing cell proliferation and angiogenesis and increasing apoptosis. In this study, we assessed combining OKN-007 with TMZ in vivo in a human G55 GBM orthotopic xenograft model and in vitro in TMZ-resistant and TMZ-sensitive human GBM cell lines. For the in vivo studies, magnetic resonance imaging was used to assess tumor growth and vascular alterations. Percent animal survival was also determined. For the in vitro studies, cell growth, IC50 values, RNA-seq, RT-PCR, and ELISA were used to assess growth inhibition, possible mechanism-of actions (MOAs) associated with combined OKN-007 + TMZ versus TMZ alone, and gene and protein expression levels, respectively. Microarray analysis of OKN-007-treated rat F98 glioma tumors was also carried out to determine possible MOAs of OKN-007 in glioma-bearing animals either treated or not treated with OKN-007. OKN-007 seems to elicit its effect on GBM tumors via inhibition of tumorigenic TGF-β1, which affects the extracellular matrix. When combined with TMZ, OKN-007 significantly increases percent survival, decreases tumor volumes, and normalizes tumor blood vasculature in vivo compared to untreated tumors and seems to affect TMZ-resistant GBM cells possibly via IDO-1, SUMO2, and PFN1 in vitro. Combined OKN-007 + TMZ may be a potentially potent treatment strategy for GBM patients.

Radioresistance of cancer cells, integrin αvβ3 and thyroid hormone

Radioresistance is a substantial barrier to success in cancer management. A number of molecular mechanisms support radioresistance. We have shown experimentally that the thyroid hormone analogue receptor on the extracellular domain of integrin αvβ3 may modulate the state of radiosensitivity of tumor cells. Specifically, tetraiodothyroacetic acid (tetrac), a derivative of L-thyroxine (T₄), can reduce radioresistance in cancer cells. In this review, we list a number of intrinsic signal transduction molecules and other host factors that have been reported to support/induce radioresistance in cancer cells and that are also subject to control by T₄ through actions primarily initiated at integrin αvβ3. Additional preclinical evidence is needed to support these radioresistance-relevant actions of thyroid hormone.

MiR-124-3p suppresses glioma aggressiveness via targeting of Fra-2

Malignant glioma is the most common and deadly primary brain tumor in adults. However, the mechanisms underlying the malignancy of glioma remain unclear. In the present study, we found that Fos-related antigen-2 (Fra-2) was overexpressed in most glioma cells, and knockdown of Fra-2 prevented cell proliferation, migration, and invasion. Mechanistically, Fra-2 silencing led to a significant reduction in cell-cycle drivers (Cyclin D1 and Cyclin E1), one invasion-associated gene (MMP9), the mesenchymal marker (Vimentin), and induction of the epithelial marker (E-cadherin). Further study confirmed that miR-124-3p decreased the expression of Fra-2 via directly targeting the 3'-UTR, and transfection with miR-124-3p in glioma cells inhibited expression of the above cell-cycle and EMT promoters. Phenotypic experiments also showed that overexpression of Fra-2 weakened the inhibitory effects of miR-124-3p on the proliferation, migration, and invasion of glioma cells. In addition, Fra-2 knockdown impaired the malignant phenotypes enhanced by miR-124-3p inhibition, which suggested a crucial role for the miR-124-3p/Fra-2 pathway in glioma development. Consistently, high expression of Fra-2 was closely associated with low miR-124-3p level and indicated a poor prognosis in patients with glioma. In conclusion, this study indicates the existence of an aberrant miR-124-3p/Fra-2 pathway that results in glioma aggressiveness, which suggests novel therapeutic opportunities for this fatal disease.

c-Fos/microRNA-18a feedback loop modulates the tumor growth via HMBOX1 in human gliomas

Glioma is one of the most aggressive and lethal human cancers in central nervous system (CNS). Recent studies have identified many dysregulated microRNAs (miRNA, miR) in human glioma, which are a class of small non-coding RNA molecules. Increasing data have shown that miR-18a plays significant roles in several tumors. However, its effects on glioma are unclear. In this study, we found the elevated expression of c-Fos and miR-18a in tissues of human glioma patients and glioma cells. Then the miR-18a inhibitor or c-Fos siRNA were transfected into glioma cells line H4 to determine their effects on H4 cells. MTT assay showed that both miR-18a inhibitor and si-c-Fos suppressed the H4 cell proliferation. Transwell assay showed the reduced cell migration by miR-18a inhibitor and si-c-Fos in H4 cells. The increased level of H4 cells apoptosis by miR-18a inhibitor and si-c-Fos was also determined. Moreover, knockout of c-Fos decreased the miR-18a level, while miR-18a inhibitor reduced the c-Fos level in H4 cells. Added with the results of ChIP assay, this report showed a positive feedback between c-Fos and miR-18a. Finally, luciferase assay showed that HMBOX1 was directly targeted by miR-18a in H4 cells, and the HMBOX1 siRNA reversed the effects of miR-18a inhibitor on cell proliferation, migration and apoptosis of H4 cells. In conclusion, our study determine that c-Fos/miR-18a feedback loop promotes the tumor growth of gliomas by HMBOX1, providing important clues for understanding the key roles of transcription factor mediated mRNA-miRNA functional network in the regulation of gliomas.

Small Molecule Modulation of Proteasome Assembly

The 20S proteasome is the main protease that directly targets intrinsically disordered proteins (IDPs) for proteolytic degradation. Mutations, oxidative stress, or aging can induce the buildup of IDPs resulting in incorrect signaling or aggregation, associated with the pathogenesis of many cancers and neurodegenerative diseases. Drugs that facilitate 20S-mediated proteolysis therefore have many potential therapeutic applications. We report herein the modulation of proteasome assembly by the small molecule TCH-165, resulting in an increase in 20S levels. The increase in the level of free 20S corresponds to enhanced proteolysis of IDPs, including α-synuclein, tau, ornithine decarboxylase, and c-Fos, but not structured proteins. Clearance of ubiquitinated protein was largely maintained by single capped proteasome complexes (19S-20S), but accumulation occurs when all 19S capped proteasome complexes are depleted. This study illustrates the first example of a small molecule capable of targeting disordered proteins for degradation by regulating the dynamic equilibrium between different proteasome complexes.

MIIP gene expression is associated with radiosensitivity in human nasopharyngeal carcinoma cells

The present study aims to investigate the radiosensitization effect of the migration and invasion inhibitory protein (MIIP) gene on nasopharyngeal carcinoma (NPC) cells. The MIIP gene was transfected into NPC 5-8F and CNE2 cells. The level of MIIP was analyzed by quantitative reverse transcription-polymerase chain reaction analysis and western blot. The changes in radiosensitivity of the cells were analyzed by colony formation assay. The changes in cell apoptosis and cycle distribution following irradiation were detected by flow cytometry. The expression of BCL2 associated X, apoptosis regulator/B-cell lymphoma 2 was evaluated using western blot. DNA damage was analyzed by counting γ-H2AX foci. The expression levels of γ-H2AX were evaluated by immunofluorescence and western blot. In a previous study by the authors, the results indicated that the expression of MIIP gene evidently increased in MIIP-transfected 5-8F (5-8F OE) and MIIP-transfected CNE2 (CNE2 OE) cells compared with the parental or negative control cells. In the present study, the survival rate of 5-8F OE and CNE2 OE cells markedly decreased following irradiation (0, 2, 4, 6 and 8 Gy) compared with the negative control (5-8F NC and CNE2 NC) and the untreated (5-8F and CNE2) groups. The expression of MIIP was able to increase apoptosis, which resulted in G2/M cell cycle arrest and DNA damage repair was attenuated in 5-8F and CNE2 cells following irradiation as measured by the accumulation of γ-H2AX. It was indicated that MIIP expression is associated with the radiosensitivity of NPC cells and has a significant role in regulating cell radiosensitivity.

c-Fos mediates α1, 2-fucosyltransferase 1 and Lewis y expression in response to TGF-β1 in ovarian cancer

FUT1 is a key rate-limiting enzyme in the synthesis of Lewis y, a membrane-associated carbohydrate antigen. The aberrant upregulation of FUT1 and Lewis y antigen is related to proliferation, invasion and prognosis in malignant epithelial tumors. A c-Fos/activator protein-1 (AP-1) binding site was found in the FUT1 promoter. However, the mechanisms of transcriptional regulation of FUT1 remain poorly understood. TGF-β1 is positively correlated to Lewis y. In the present study, we investigated the molecular mechanism of FUT1 gene expression in response to TGF-β1. We demonstrated that c-Fos was highly expressed in 77.50% of ovarian epithelial carcinoma cases and was significantly correlated with Lewis y. Using luciferase activity and chromatin immunoprecipitation (ChIP) assay, we further revealed that c-Fos interacted with the FUT1 promoter in ovarian cancer cells and transcriptional capacity of the heterodimer formed by c-Fos and c-Jun was stronger than that of the c-Fos or c-Jun homodimers. Then, we demonstrated that TGF-β1 induced dose-dependent c-Fos expression, which was involved in TGF-β1-induced ovarian cancer cell proliferation. In addition, inhibition of MAPK activation or TGF-β1 receptor by pharmacological agents prevented TGF-β1-induced c-Fos and Lewis y expression. Silencing of c-Fos prevented TGF-β1-induced Lewis y expression. Collectively, the results of these studies demonstrated that TGF-β1 regulated FUT1 and Lewis y expression by activating the MAPK/c-Fos pathway.

Musashi-2, a novel oncoprotein promoting cervical cancer cell growth and invasion, is negatively regulated by p53-induced miR-143 and miR-107 activation

Background

Although previous studies have shown promise for targeting Musashi RNA-binding protein 2 (MSI-2) in diverse tumors, the role and mechanism of MSI-2 for cervical cancer (CC) progression and the regulation of MSI-2 expression remains unclear.

Methods

Using gene expression and bioinformatic analysis, together with gain- and loss-of-function assays, we identified MSI-2 as a novel oncogenic driver and a poor prognostic marker in CC. We explored the regulation of c-FOS by MSI-2 via RNA-immunoprecipitation and luciferase assay, and confirmed a direct inhibition of MSI-2 by miR-143/miR-107 using luciferase assay. We assessed the effect of a natural antibiotic Mithramycin A on p53, miR-143/miR-107 and MSI-2 expression in CC cells.

Results

MSI-2 mRNA is highly expressed in CC tissues and its overexpression correlates with lower overall survival. MSI-2 promotes CC cell growth, invasiveness and sphere formation through directly binding to c-FOS mRNA and by increasing c-FOS protein expression. Furthermore, miR-143/miR-107 are two tumor suppressor miRNAs that directly bind and inhibit MSI-2 expression in CC cells, and downregulation of miR-143/miR-107 associates with poor patient prognosis. Importantly, we found that p53 decreases the expression of MSI-2 through elevating miR-143/miR-107 levels, and treatment with a natural antibiotic Mithramycin A increased p53 and miR-143/miR-107 expression and reduced MSI-2 expression, resulting in the inhibition of CC cell proliferation, invasion and sphere formation.

Conclusions

These results suggest that MSI-2 plays a crucial role in promoting the aggressive phenotypes of CC cells, and restoration of miR-143/miR-107 by Mithramycin A via activation of p53 may represent a novel therapeutic approach for CC.

Direct Downregulation of B-Cell Translocation Gene 3 by microRNA-93 Is Required for Desensitizing Esophageal Cancer to Radiotherapy

BACKGROUND

Esophageal squamous carcinoma (ESC) is one of the most fatal malignancies worldwide with increasing occurrences yet poor outcome. MicroRNAs were reported to play roles in ESC.

AIMS

We aimed to understand how miRNAs affect the radiotherapy resistance of ESC.

METHODS

MicroRNA assays, real-time PCR, and Western blot were performed for expression analysis of miR-93 and BTG3. Luciferase activity assay was conducted with mutated B-cell translocation gene 3 (BTG3) 3'-UTR sequence in the 3' end of luciferase sequence with miR-93 inhibitor. ESC cells were treated with irradiation (IR) and clonogenic assay was utilized to detect the cell viability. Human ESC xenograft mouse model was established and subjected to target IR treatment followed by tumor size analysis.

RESULTS

MiR-93 was decreased and BTG3 was increased in ESC cells, with negative correlation of their expression in ESC tissues. MiR-93 directly targeted BTG3 3'-UTR by luciferase activity assay. Either miR-93 inhibition or BTG3 overexpression decreased radiation resistance. Furthermore, miR-93 inhibition suppressed radiation resistance through BTG3.

CONCLUSIONS

Direct downregulation of BTG3 by miR-93 is able to render ESC resistant to radiotherapy, and both BTG3 and miR-93 may potentially serve as clinical markers for ESC and contribute to the treatment of ESC.

Involvement of c-Fos in cell proliferation, migration, and invasion in osteosarcoma cells accompanied by altered expression of Wnt2 and Fzd9

Osteosarcoma (OS) is an aggressive bone tumor, and proto-oncogene c-Fos is involved in this lethal disease. However, the role and molecular mechanism of c-Fos in the development and progression of OS remain enigmatic. As one of the Wnt family members, Wnt2 is closely associated with the development of several malignant tumors. In the present study, the expression of c-Fos, Wnt2, and its receptor Fzd9 in human OS tissues, MG63 OS cell line, and human osteoblast hFOB 1.19 cell line was detected by Western blot analysis, immunohistochemical staining, or reverse transcription-polymerase chain reaction. The role of c-Fos in the OS was clarified by treating MG63 cells with small interfering RNA to knockdown c-Fos. Then, cell migration and invasion were assayed by transwell assays and wound healing assay; cell proliferation was assayed by MTS method and 5-ethynyl-2'-deoxyuridine DNA proliferation in vitro detection; cell apoptosis was assayed by flow cytometric method. Co-immunoprecipitation kit was used to confirm the relationship between c-Fos and Wnt2/Fzd9. We found that the expression of c-Fos, Wnt2, and Fzd9 protein was distinctly higher in human OS tissues than that in the adjacent non-cancerous tissues, and their expression in the MG63 OS cell line was markedly increased compared with that in the human osteoblast hFOB 1.19 cell line. Knockdown of c-Fos inhibited the proliferation, migration, and invasion of MG63 cells, and promoted the apoptosis of MG63 cells. Moreover, knockdown of c-Fos inhibited the expression of Wnt2 and Fzd9 mRNA and protein. Our data enforced the evidence that knockdown of c-Fos inhibited cell proliferation, migration, and invasion, and promoted the apoptosis of OS cells accompanied by altered expression of Wnt2 and Fzd9. These findings offer new clues for OS development and progression, and c-Fos may be a potential therapeutic target for OS.