miR-4792 inhibits epithelial-mesenchymal transition and invasion in nasopharyngeal carcinoma by targeting FOXC1

Research progress on the regulatory mechanisms of FOXC1 expression in cancers and its role in drug resistance

The Forkhead box C1 (FOXC1) transcription factor is an important member of the FOX family. After initially being identified in triple-negative breast cancer (TNBC) with significant oncogenic function, FOXC1 was subsequently demonstrated to be involved in the development of more than 16 types of cancers. In recent years, increasing studies have focused on the deregulatory mechanisms of FOXC1 expression and revealed that FOXC1 expression was regulated at multiple levels including transcriptional regulation, post-transcription regulation and post-translational modification. Moreover, dysregulation of FOXC1 is also implicated in drug resistance in various types of cancer, especially in breast cancer, which further emphasizes the translational and clinical significance of FOXC1 as a therapeutic target in cancer treatment. This review summarizes recent findings on mechanisms of FOXC1 dysregulation in cancers and its role in chemoresistance, which will help to better understand the oncogenic role of FOXC1, overcome FOXC1-mediated drug resistance and develop targeted therapy for FOXC1 in cancers.

Exosome-Mediated miR-4792 Transfer Promotes Bladder Cancer Cell Proliferation via Enhanced FOXC1/c-Myc Signaling and Warburg Effect

Bladder cancer is the second-most common malignancy in the urogenital system and the most common in men. However, our understanding of the driving mechanisms of bladder cancer remains incomplete. The forkhead box (FOX) family of transcription factors is implicated in urogenital development and bladder malignancies. Many exosomal microRNAs have been identified as regulators and mediators of the expression of FOX, including the expression of FOXC1. miR-4792 has been known as a tumor miRNA suppressor. However, the function of miR-4792/FOXC1 signaling in bladder cancer development remains unknown. Here, we studied the role of miR-4792/FOXC1 signaling in bladder cancer by using multiple bladder cancer cell lines and bladder cancer mouse models through in vitro and in vivo approaches. We showed that FOXC1 is highly expressed in multiple bladder cancer cell lines and bladder tumor tissues. The knockdown of FOXC1 expression in bladder cancer cell lines decreases c-Myc expression levels, retards cell growth, and reduces aerobic glycolysis (also known as the Warburg effect) and lactic acid content. By contrast, the overexpression of FOXC1 elicits the opposite effects. FOXC1-downregulated bladder cancer cells form significantly smaller tumors in vivo. The inhibition of c-Myc reverses the effects of FOXC1 overexpression and leads to reduced cell proliferation, aerobic glycolysis, and lactic acid content. miR-4792 expression is downregulated in bladder tumor tissues. miR-4792 exposure to bladder cancer cells reduces the expression levels of FOXC1 and c-Myc, slows down cell growth, and decreases aerobic glycolysis and lactic acid content. However, the enhanced miR-4792 expression elicits opposite effects. These findings provided the first evidence that the exosome-mediated delivery of miR-4792 could play an important role in bladder cancer development through the downregulation of FOXC1 and c-Myc, which further inhibited aerobic glycolysis and lactic acid content.

Therapeutically Targeting Cancers That Overexpress FOXC1: A Transcriptional Driver of Cell Plasticity, Partial EMT, and Cancer Metastasis

Metastasis accounts for more than 90% of cancer related mortality, thus the most pressing need in the field of oncology today is the ability to accurately predict future onset of metastatic disease, ideally at the time of initial diagnosis. As opposed to current practice, what would be desirable is that prognostic, biomarker-based detection of metastatic propensity and heightened risk of cancer recurrence be performed long before overt metastasis has set in. Without such timely information it will be impossible to formulate a rational therapeutic treatment plan to favorably alter the trajectory of disease progression. In order to help inform rational selection of targeted therapeutics, any recurrence/metastasis risk prediction strategy must occur with the paired identification of novel prognostic biomarkers and their underlying molecular regulatory mechanisms that help drive cancer recurrence/metastasis (i.e. recurrence biomarkers). Traditional clinical factors alone (such as TNM staging criteria) are no longer adequately prognostic for this purpose in the current molecular era. FOXC1 is a pivotal transcription factor that has been functionally implicated to drive cancer metastasis and has been demonstrated to be an independent predictor of heightened metastatic risk, at the time of initial diagnosis. In this review, we present our viewpoints on the master regulatory role that FOXC1 plays in mediating cancer stem cell traits that include cellular plasticity, partial EMT, treatment resistance, cancer invasion and cancer migration during cancer progression and metastasis. We also highlight potential therapeutic strategies to target cancers that are, or have evolved to become, “transcriptionally addicted” to FOXC1. The potential role of FOXC1 expression status in predicting the efficacy of these identified therapeutic approaches merits evaluation in clinical trials.

Impact of Zika Virus Infection on Human Neural Stem Cell MicroRNA Signatures

Zika virus (ZIKV) is a mosquito-borne virus, which can cause brain abnormalities in newborns, including microcephaly. MicroRNAs (miRNAs) are small non-coding RNAs, which post- transcriptionally regulate gene expression. They are involved in various processes including neurological development and host responses to viral infection, but their potential role in ZIKV pathogenesis remains poorly understood. MiRNAs can be incorporated into extracellular vesicles (EVs) and mediate cell-to-cell communication. While it is well known that in viral infections EVs carrying miRNAs can play a crucial role in disease pathogenesis, ZIKV effects on EV-delivered miRNAs and their contribution to ZIKV pathogenesis have not been elucidated. In the present study, we profiled intracellular and EV-derived miRNAs by next generation sequencing and analyzed the host mRNA transcriptome of neural stem cells during infection with ZIKV Uganda and French Polynesia strains. We identified numerous miRNAs, including miR-4792, which were dysregulated at the intracellular level and had altered levels in EVs during ZIKV infection. Integrated analyses of differentially expressed genes and miRNAs showed that ZIKV infection had an impact on processes associated with neurodevelopment and oxidative stress. Our results provide insights into the roles of intracellular and EV-associated host miRNAs in ZIKV pathogenesis.

The first report on circulating microRNAs at Pre- and Post-metamorphic stages of axolotls

MicroRNAs (miRNAs) are endogenously coded small RNAs, implicated in post-transcriptional gene regulation by targeting messenger RNAs (mRNAs). Circulating miRNAs are cell-free molecules, found in body fluids, such as blood and saliva, and emerged recently as potential diagnostic biomarkers. Functions of circulating miRNAs and their roles in target tissues have been extensively investigated in mammals, and the reports on circulating miRNAs in non-mammalian clades are largely missing. Salamanders display remarkable regenerative potential, and the Mexican axolotl (Ambystoma mexicanum), a critically endangered aquatic salamander, has emerged as a powerful model organism in regeneration and developmental studies. This study aimed to explore the circulating miRNA signature in axolotl blood plasma. Small RNA sequencing on plasma samples revealed 16 differentially expressed (DE) circulating miRNAs between neotenic and metamorphic stages out of identified 164 conserved miRNAs. Bioinformatics predictions provided functional annotation of detected miRNAs for both stages and enrichment of DE miRNAs in cancer-related and developmental pathways was notable. Comparison with previous reports on axolotl miRNAs unraveled common and unique members of the axolotl circulating miRNome. Overall, this work provides novel insights into non-mammalian aspects of circulating miRNA biology and expands the multi-omics toolkit for this versatile model organism.

miR-4792 Inhibits Acute Myeloid Leukemia Cell Proliferation and Invasion and Promotes Cell Apoptosis by Targeting Kindlin-3

It has been reported that kindlin-3 expression is closely associated with progression of many cancers and microRNA (miRNA) processing. However, the effects and precise mechanisms of kindlin-3 in acute myeloid leukemia (AML) have not been well clarified. Our study aimed to explore the interaction between kindlin-3 and miR-4792 in AML. In our study, we found that the expression of kindlin-3 was dramatically increased in AML samples and cell lines, and the miR-4792 level was significantly downregulated. Interestingly, the low miR-4792 level was closely associated with upregulated kindlin-3 expression in AML samples. Moreover, introduction of miR-4792 dramatically suppressed proliferation and invasion and induced apoptosis of AML cells. We demonstrated that miR-4792 could directly target kindlin-3 by using both bioinformatics analysis and luciferase reporter assay. In addition, kindlin-3 silencing had similar effects with miR-4792 overexpression on AML cells. Overexpression of kindlin-3 in AML cells partially reversed the inhibitory effects of miR-4792 mimic. miR-4792 inhibited cell proliferation and invasion and induced apoptosis of AML cells by directly downregulating kindlin-3 expression, and miR-4792 targeting kindlin-3 was responsible for the regulation of the proliferation, invasion, and apoptosis of AML cells.

Amyloid β precursor protein silencing attenuates epithelial‑mesenchymal transition of nasopharyngeal carcinoma cells via inhibition of the MAPK pathway

Advances in the treatment of nasopharyngeal carcinoma (NPC) have significantly improved the local control rate; however, distant metastasis remains a principal cause of mortality. Previous studies have demonstrated that the expression levels of amyloid β precursor protein (APP) are increased in NPC. The present study aimed to investigate the association between APP and the development of NPC. In order to knockdown APP expression, an APP-small interfering RNA vector was synthesized and transfected into SUNE-1 cells. Cell Counting Kit-8 assay was performed to assess cell viability. The migratory and invasive abilities of SUNE-1 cells were examined by wound healing and Transwell assays, respectively. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to measure the mRNA and protein expression levels of APP, and additional factors involved in epithelial-mesenchymal transition (EMT) and in the mitogen-activated protein kinase (MAPK) signaling pathway. APP silencing significantly suppressed cell viability, migration and invasion. In addition, APP interference downregulated the expression levels of metastasis-associated 1, matrix metalloproteinase (MMP)-2 and MMP-9; however, knockdown of APP led to upregulation of tissue inhibitor of metalloproteinases 2 and inhibited EMT. The phosphorylation levels of p38, extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinases 1/2 were decreased following downregulation of APP. The present results suggested that APP knockdown may significantly inhibit the development of NPC by suppressing cell viability, migration and invasion, and by inhibiting the EMT process via downregulation of the MAPK signaling pathway. Therefore, APP may facilitate the development of a novel gene therapy for the treatment of NPC.

Bioinformatic analysis of miR-4792 regulates Radix Tetrastigma hemsleyani flavone to inhibit proliferation, invasion, and induce apoptosis of A549 cells

BACKGROUND

Radix Tetrastigma hemsleyani, a kind of Chinese medicinal herb, contains multiple medicinal ingredients and can exert a variety of pharmacological activities. Our previous study revealed that miR-4792 was significantly upregulated in Radix Tetrastigma hemsleyani flavone (RTHF)-treated A549 cells; however, the regulatory mechanism of RTHF-treated A549 cells remains unclear.

MATERIALS AND METHODS

In this study, we investigated the antitumor mechanism and regulatory pathway of miR-4792 in RTHF-treated A549 cells, and the target genes were predicted and pathway enrichment of miR-4792 was performed using bioinformatic analysis.

RESULTS

Our results confirmed that the upregulated expression of miR-4792 could inhibit cell proliferation and invasion, provoke cell cycle arrest, and induce apoptosis in A549 cells. Gene Ontology analysis showed that target genes of miR-4792 were enriched in protein binding, cytosol, cytoplasm, plasma membrane, and metal ion binding. Kyoto Encyclopedia of Genes and Genomes analysis showed that target genes of miR-4792 were enriched in aminoacyltRNA biosynthesis, AGE-RAGE signaling pathway in diabetic complications, sphingolipid signaling pathway, neuroactive ligand-receptor interaction, glycosaminoglycan degradation, and regulation of lipolysis in adipocytes. Additionally, FOXC1 was identified as an important target gene of miR-4792 in RTHF-treated A549 cells, and miR-4792 may be the target of some apoptotic-related proteins involved in induction of apoptosis in A549 cells by RTHF. Moreover, the intracellular Ca2+ levels of A549 cells were increased after RTHF treatment, which may be involved in the anticancer regulatory process of miR-4792 in RTHF-treated A549 cells.

CONCLUSION

These findings suggest a novel therapeutic approach for lung cancer that will be investigated in future studies.

Analysis of change in microRNA expression profiles of lung cancer A549 cells treated with Radix tetrastigma hemsleyani flavonoids

Background

The aim of this study was to determine the inhibition effects of Radix tetrastigma hemsleyani (RTH) flavonoids on human lung adenocarcinoma A549 cells and the underlying molecular mechanism. RTH is an important Chinese traditional herb that has been widely used in cancer therapy. As an important type of active substance, RTH flavones (RTHF) have been shown to have good antiproliferative effects on various cancer cells. MicroRNAs (miRNAs) are small, noncoding RNA molecules that play important roles in cancer progression and prevention. However, the miRNA profile of RTHF-treated A549 cells has not yet been studied.

Materials and methods

The miRNA expression profile changes of A549 cell treated with RTHF were determined using the miRNA-seq analysis. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of differentially expressed miRNAs' (DE-miRNAs) target genes were carried out.

Results

In this study, we identified 162 miRNAs that displayed expression changes >1.2-fold in RTHF-treated A549 cells. GO analysis results showed that target genes of DE-miRNAs were significantly enriched in protein binding, binding, cell, cell part, intracellular, cellular process, single-organism process, and single-organism cellular process. Pathway analysis illustrated that target genes of DE-miRNAs are mainly involved in endocytosis, axon guidance, lysosome, melanogenesis, and acute myeloid leukemia pathway.

Conclusion

These results may assist in the better understanding of the anticancer effects of RTHF in A549 cells.

Small non-coding RNA profiling in human biofluids and surrogate tissues from healthy individuals: description of the diverse and most represented species

The role of non-coding RNAs in different biological processes and diseases is continuously expanding. Next-generation sequencing together with the parallel improvement of bioinformatics analyses allows the accurate detection and quantification of an increasing number of RNA species. With the aim of exploring new potential biomarkers for disease classification, a clear overview of the expression levels of common/unique small RNA species among different biospecimens is necessary. However, except for miRNAs in plasma, there are no substantial indications about the pattern of expression of various small RNAs in multiple specimens among healthy humans. By analysing small RNA-sequencing data from 243 samples, we have identified and compared the most abundantly and uniformly expressed miRNAs and non-miRNA species of comparable size with the library preparation in four different specimens (plasma exosomes, stool, urine, and cervical scrapes). Eleven miRNAs were commonly detected among all different specimens while 231 miRNAs were globally unique across them. Classification analysis using these miRNAs provided an accuracy of 99.6% to recognize the sample types. piRNAs and tRNAs were the most represented non-miRNA small RNAs detected in all specimen types that were analysed, particularly in urine samples. With the present data, the most uniformly expressed small RNAs in each sample type were also identified. A signature of small RNAs for each specimen could represent a reference gene set in validation studies by RT-qPCR. Overall, the data reported hereby provide an insight of the constitution of the human miRNome and of other small non-coding RNAs in various specimens of healthy individuals.

FOXC1 in cancer development and therapy: deciphering its emerging and divergent roles

Forkhead box C1 (FOXC1) is an essential member of the forkhead box transcription factors and has been highlighted as an important transcriptional regulator of crucial proteins associated with a wide variety of carcinomas. FOXC1 regulates tumor-associated genes and is regulated by multiple pathways that control its mRNA expression and protein activity. Aberrant FOXC1 expression is involved in diverse tumorigenic processes, such as abnormal cell proliferation, cancer stem cell maintenance, cancer migration, and angiogenesis. Herein, we review the correlation between the expression of FOXC1 and tumor behaviors. We also summarize the mechanisms of the regulation of FOXC1 expression and activity in physiological and pathological conditions. In particular, we focus on the pathological processes of cancer targeted by FOXC1 and discuss whether FOXC1 is good or detrimental during tumor progression. Moreover, FOXC1 is highlighted as a clinical biomarker for diagnosis or prognosis in various human cancers. The information reviewed here should assist in experimental designs and emphasize the potential of FOXC1 as a therapeutic target for cancer.

MicroRNA-374c-5p regulates the invasion and migration of cervical cancer by acting on the Foxc1/snail pathway

Some microRNAs (miRNAs) have been implicated in cervical cancer development and progression. However, the roles and mechanisms of several miRNAs in epithelial-mesenchymal transition (EMT) in cervical cancer remain poorly understood. Here, we conducted a microarray analysis and found that miR-374c-5p was most down-regulated miRNA in TGFβ1-treated cervical cancer cells compared to the expression in parental cell lines. Ectopic overexpression of miR-374c-5p inhibited cervical cancerl invasion and migration in TGFβ1- treated cervical cancer cells. Conversely, miR-374c-5p knockdown increased the migration and invasion abilities of parental cell lines. Moreover, miR-374c-5p exerted its function by directly targeting the FOXC1 3^/-UTR and repressing FOXC1 expression, thus leading to suppression of snail. In clinical cervical cancer samples, lower miR-374c-5p expression predicted poor patient survival and highe lymph node metastasis in cervical cancers. miR-374c-5p was negatively correlated with FOXC1, which was upregulated in cervical cancers with lymph node metastasis. Taken together, our findings highlight the important role of miR-374c-5p in regulating cervical cancers metastasis by targeting FOXC1, suggesting that miR-374c-5p may represent a novel potential therapeutic target and prognostic marker in cervical cancers.

Forkhead box C1 is targeted by microRNA-133b and promotes cell proliferation and migration in osteosarcoma

Forkhead box C1 (FOXC1) has been demonstrated to act as an oncogene in a number of malignant tumors, though its underlying mechanism of action in osteosarcoma (OS) remains unknown. The present study evaluated the expression and regulatory role of FOXC1 in OS. Reverse transcription-quantitative polymerase chain reaction and western blot data indicated that FOXC1 was significantly upregulated in OS tissues and cell lines when compared with adjacent non-tumor tissues (P<0.001) and normal human osteoblast cells (P<0.01), respectively. Moreover, levels of FOXC1 expression were significantly higher in OS at advanced clinical stage (III–IV) when compared with that at low clinical stage (I–II; P<0.001). Knockdown of FOXC1 expression caused a significant decrease in the proliferation and migration of OS U2OS cells (P<0.01), while overexpression of FOXC1 significantly promoted U2OS cell proliferation and migration (P<0.01), relative to control U2OS cells. Furthermore, FOXC1 was identified as a direct target of microRNA (miR)-133b, a reported tumor-suppressive miR in OS. The protein expression of FOXC1 was negatively regulated by miR-133b in U2OS cells (P<0.01), and miR-133b expression was inversely correlated with FOXC1 expression in OS. In conclusion, the present study demonstrated that FOXC1, targeted by miR-133b, may promote cell proliferation and migration in OS. Thus, FOXC1 may be a potential therapeutic target in the treatment of OS.

Foxj2 overexpression is associated with poor prognosis, progression, and metastasis in nasopharyngeal carcinoma

Foxj2, a novel member of Forkhead box family, has been reported to play an important role in tumorigenesis, progression, and metastasis of certain cancers. However, the expression status and effects of Foxj2 on nasopharyngeal carcinoma (NPC) progression and metastasis remain debated. In this study, we first examined the expression of Foxj2 in NPC by immunohistochemistry and Western blotting analysis. We confirmed significantly elevated expression of Foxj2 in NPC tissues and cell lines. Next, the relationships between Foxj2 expression levels and the clinicopathological factors were investigated. Its expression level correlated with T-classification (P=0.026), distant metastasis (P=0.004), and clinical stage (P=0.029). In addition, high expression of Foxj2 was associated with poor prognosis in NPC patients. The effects of Foxj2 on cell proliferation and migration were explored by RNA interference (RNAi) with CCK-8 assay, cell cycle analyses, wound healing, and transwell assay. In conclusion, our data indicate that Foxj2 upregulation promotes the progression and migration of NPC. It makes Foxj2 serve as a potential therapeutic target for the treatment of NPC.

MiR-130a-3p inhibits the viability, proliferation, invasion, and cell cycle, and promotes apoptosis of nasopharyngeal carcinoma cells by suppressing BACH2 expression

The aim of the present study was to explore the mechanism through which miR-130a-3p affects the viability, proliferation, migration, and invasion of nasopharyngeal carcinoma (NPC). Tissue samples were collected from the hospital department. NPC cell lines were purchased to conduct the in vitro and in vivo assays. A series of biological assays including MTT, Transwell, and wound healing assays were conducted to investigate the effects of miR-130a-3p and BACH2 on NPC cells. MiR-130a-3p was down-regulated in both NPC tissues and cell lines, whereas BACH2 was up-regulated in both tissues and cell lines. MiR-130a-3p overexpression inhibited NPC cell viability, proliferation, migration, and invasion but promoted cell apoptosis. The converse was true of BACH2, the down-regulation of which could inhibit the corresponding cell abilities and promote apoptosis of NPC cells. The target relationship between miR-130a-3p and BACH2 was confirmed. The epithelial-mesenchymal transition (EMT) pathway was also influenced by miR-130a-3p down-regulation. In conclusion, miR-130a-3p could bind to BACH2, inhibit NPC cell abilities, and promote cell apoptosis.

Oxygen tension regulates the miRNA profile and bioactivity of exosomes released from extravillous trophoblast cells - Liquid biopsies for monitoring complications of pregnancy

Our understanding of how cells communicate has undergone a paradigm shift since the recent recognition of the role of exosomes in intercellular signaling. In this study, we investigated whether oxygen tension alters the exosome release and miRNA profile from extravillous trophoblast (EVT) cells, modifying their bioactivity on endothelial cells (EC). Furthermore, we have established the exosomal miRNA profile at early gestation in women who develop pre-eclampsia (PE) and spontaneous preterm birth (SPTB). HTR-8/SVneo cells were used as an EVT model. The effect of oxygen tension (i.e. 8% and 1% oxygen) on exosome release was quantified using nanocrystals (Qdot®) coupled to CD63 by fluorescence NTA. A real-time, live-cell imaging system (Incucyte™) was used to establish the effect of exosomes on EC. Plasma samples were obtained at early gestation (<18 weeks) and classified according to pregnancy outcomes. An Illumina TrueSeq Small RNA kit was used to construct a small RNA library from exosomal RNA obtained from EVT and plasma samples. The number of exosomes was significantly higher in EVT cultured under 1% compared to 8% oxygen. In total, 741 miRNA were identified in exosomes from EVT. Bioinformatic analysis revealed that these miRNA were associated with cell migration and cytokine production. Interestingly, exosomes isolated from EVT cultured at 8% oxygen increased EC migration, whilst exosomes cultured at 1% oxygen decreased EC migration. These changes were inversely proportional to TNF-α released from EC. Finally, we have identified a set of unique miRNAs in exosomes from EVT cultured at 1% oxygen and exosomes isolated from the circulation of mothers at early gestation, who later developed PE and SPTB. We suggest that aberrant exosomal signalling by placental cells is a common aetiological factor in pregnancy complications characterised by incomplete SpA remodeling and is therefore a clinically relevant biomarker of pregnancy complications.