FOXC2 Often Overexpressed in Glioblastoma Enhances Proliferation and Invasion in Glioblastoma Cells

ADAM12 Silencing Mediated by FOXC2 Represses Meningioma Progression Through Inactivating the JAK1/STAT3/VEGFA Pathway

Meningioma is a prevalently intracranial tumor, and the malignant type is aggressive with high recurrence. A Disintegrin and Metalloprotease 12 (ADAM12) is a common oncogene and differentially expressed in meningioma. However, its roles and mechanisms in meningioma development remain obscure. The differentially expressed genes in meningioma were analyzed by GEO (GSE77259 and GSE43290) datasets and weighted gene co-expression network analysis (WGCNA) based on GSE16581. ADAM12 expression was measured via qRT-PCR and western blot. The correlation between ADAM12 and FOXC2 was predicted through JASPER tool and identified via luciferase reporter analysis. Cell proliferation, migration and invasion were investigated using CCK-8, EdU, transwell assays. The JAK1/STAT3/VEGFA signaling was activated by IL-6, and analyzed via western blot. The differentially expressed ADAM12 in meningioma was screened by WGCNA and GEO analyses. ADAM12 silencing repressed meningioma cell proliferation, and decreased migration and invasion. The transcription factor FOXC2 expression was enhanced in meningioma based on GSE77259 and GSE43290 datasets, and positively induced ADAM12 transcription. The JAK1/STAT3/VEGFA signaling was inactivated due to ADAM12 silencing and activated via IL-6. Upregulation of FOXC2 promoted cell proliferation, migration and invasion, and these effects were reversed by silencing ADAM12. ADAM12 knockdown mediated via FOXC2 silencing restrained proliferation, migration and invasion of meningioma cells through inactivating the JAK1/STAT3/VEGFA pathway.

The contribution of silencer variants to human diseases

BACKGROUND

Although disease-causal genetic variants have been found within silencer sequences, we still lack a comprehensive analysis of the association of silencers with diseases. Here, we profiled GWAS variants in 2.8 million candidate silencers across 97 human samples derived from a diverse panel of tissues and developmental time points, using deep learning models.

RESULTS

We show that candidate silencers exhibit strong enrichment in disease-associated variants, and several diseases display a much stronger association with silencer variants than enhancer variants. Close to 52% of candidate silencers cluster, forming silencer-rich loci, and, in the loci of Parkinson's-disease-hallmark genes TRIM31 and MAL, the associated SNPs densely populate clustered candidate silencers rather than enhancers displaying an overall twofold enrichment in silencers versus enhancers. The disruption of apoptosis in neuronal cells is associated with both schizophrenia and bipolar disorder and can largely be attributed to variants within candidate silencers. Our model permits a mechanistic explanation of causative SNP effects by identifying altered binding of tissue-specific repressors and activators, validated with a 70% of directional concordance using SNP-SELEX. Narrowing the focus of the analysis to individual silencer variants, experimental data confirms the role of the rs62055708 SNP in Parkinson's disease, rs2535629 in schizophrenia, and rs6207121 in type 1 diabetes.

CONCLUSIONS

In summary, our results indicate that advances in deep learning models for the discovery of disease-causal variants within candidate silencers effectively "double" the number of functionally characterized GWAS variants. This provides a basis for explaining mechanisms of action and designing novel diagnostics and therapeutics.

Cross-species comparative hippocampal transcriptomics in Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial pathology, with most cases having a sporadic origin. Recently, knock-in (KI) mouse models, such as the novel humanized amyloid-β (hAβ)-KI, have been developed to better resemble sporadic human AD.

METHODS

Here, we compared hippocampal publicly available transcriptomic profiles of transgenic (5xFAD and APP/PS1) and KI (hAβ-KI) mouse models with early- (EOAD) and late- (LOAD) onset AD patients.

RESULTS

The three mouse models presented more Gene Ontology biological processes terms and enriched signaling pathways in common with LOAD than with EOAD individuals. Experimental validation of consistently dysregulated genes revealed five altered in mice (SLC11A1, S100A6, CD14, CD33, and C1QB) and three in humans (S100A6, SLC11A1, and KCNK). Finally, we identified 17 transcription factors potentially acting as master regulators of AD.

CONCLUSION

Our cross-species analyses revealed that the three mouse models presented a remarkable similarity to LOAD, with the hAβ-KI being the more specific one.

Oncogenic functions of the FOXC2 transcription factor: a hallmarks of cancer perspective

Epigenetic regulation of gene expression is a fundamental determinant of molecular and cellular function, and epigenetic reprogramming in the context of cancer has emerged as one of the key enabling characteristics associated with acquisition of the core hallmarks of this disease. As such, there has been renewed interest in studying the role of transcription factors as epigenetic regulators of gene expression in cancer. In this review, we discuss the current state of knowledge surrounding the oncogenic functions of FOXC2, a transcription factor that frequently becomes dysregulated in a variety of cancer types. In addition to highlighting the clinical impact of aberrant FOXC2 activity in cancer, we discuss mechanisms by which this transcription factor becomes dysregulated in both tumor and tumor-associated cells, placing particular emphasis on the ways in which FOXC2 promotes key hallmarks of cancer progression. Finally, we bring attention to important issues related to the oncogenic dysregulation of FOXC2 that must be addressed going forward in order to improve our understanding of FOXC2-mediated cancer progression and to guide prognostic and therapeutic applications of this knowledge in clinical settings.

FOXC2 as a prognostic marker and a potential molecular target in patients with human solid tumors

BACKGROUND

Forkhead Box Protein C2 (FOXC2) belongs to the Forkhead/Wing-helix family. The regulatory role of this transcription factor in physiological function and carcinogenic activity has been proven in subsequent investigations. However, there is still scarcity of evidence on the relationship between FOXC2 expression and prognosis in human solid tumors. We conducted this meta-analysis to evaluate the role of FOXC2 as a prognosis factor and a possible target marker in human solid tumors.

METHODS

PubMed, Web of Science, Embase, and the Cochrane library database were all searched methodically. Eligible publications on FOXC2 in human solid tumors were gathered and reviewed. The effect sizes were calculated using pooled hazard ratios (HRs) or odds ratios (ORs) with the corresponding 95% confidence interval (CI). Statistical analysis was conducted with Stata SE12.0.

RESULTS

This meta-analysis comprised 3,267 patients from 20 studies covering a variety of solid tumors. Increased FOXC2 expression was related to shorter overall survival (OS) (HR = 2.05, 95% CI: 1.73-2.42). High expression of FOXC2 is associated with lymph node metastases (OR = 3.33, 95% CI: 2.65-4.19), TNM stage (OR = 3.09, 95% CI: 2.00-4.78), and age (OR = 1.26, 95% CI: 1.06-1.50), according to the pooled ORs. However, no significant association was observed between the high expression of FOXC2 and sex, tumor size or tumor differentiation.

CONCLUSION

Increased expression of FOXC2 is associated with unfavored OS, lymph node metastases, TNM stage, and age. FOXC2 is a promising prognostic marker and a novel target marker in human solid tumors.

FOXC2 Promotes Vasculogenic Mimicry in Ovarian Cancer

FOXC2 is a forkhead family transcription factor that plays a critical role in specifying mesenchymal cell fate during embryogenesis. FOXC2 expression is associated with increased metastasis and poor survival in various solid malignancies. Using in vitro and in vivo assays in mouse ovarian cancer cell lines, we confirmed the previously reported mechanisms by which FOXC2 could promote cancer growth, metastasis, and drug resistance, including epithelial-mesenchymal transition, stem cell-like differentiation, and resistance to anoikis. In addition, we showed that FOXC2 expression is associated with vasculogenic mimicry in mouse and human ovarian cancers. FOXC2 overexpression increased the ability of human ovarian cancer cells to form vascular-like structures in vitro, while inhibition of FOXC2 had the opposite effect. Thus, we present a novel mechanism by which FOXC2 might contribute to cancer aggressiveness and poor patient survival.

Novel Brain-Stiffness-Mimicking Matrix Gel Enables Comprehensive Invasion Analysis of 3D Cultured GBM Cells

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults, which is fast growing and tends to invade surrounding normal brain tissues. Uncovering the molecular and cellular mechanisms of GBM high invasion potential is of great importance for the treatment and prognostic prediction. However, the commonly used two-dimensional (2D) cell culture and analysis system suffers from lack of the heterogeneity and in vivo property of brain tissues. Here, we established a three-dimensional (3D) cell culture-based analysis system that could better recapitulate the heterogeneity of GBM and mimic the in vivo conditions in the brain. The GBM cell lines, DBTRG and U251, were cultured by hanging drop culture into the GBM multicellular spheroids, which were embedded in the optimized 3D brain-stiffness-mimicking matrix gel (0.5 mg/ml Collagen Ⅰ + 3 mg/ml Matrigel+ 3.3 mg/ml Hyaluronic Acid (HA)). The biochemical composition of the optimized matrix gel is similar to that of the brain microenvironment, and the elastic modulus is close to that of the brain tissue. The dynamics of the GBM spheroids was examined using high-content imaging for 60 h, and four metrics including invasion distance, invasion area, single-cell invasion velocity, and directionality were employed to quantify the invasion capacity. The result showed that DBTRG cells possess higher invasion capacity than U251 cells, which was consistent with the results of the classic transwell test. Transcriptome analysis of both cell lines was performed to explore the underlying molecular mechanisms. Our novel brain-stiffness-mimicking matrix gel enables comprehensive invasion analysis of the 3D cultured GBM cells and provides a model basis for in-depth exploration of the mechanisms regulating GBM invasion including the interaction between GBM cells and brain stroma.

Comprehensive analysis reveals common DNA methylation patterns of tobacco-associated cancers: A pan-cancer analysis

The role of tobacco in carcinogenesis has received increasing attention across a number of disciplines in recent years. Accumulating evidences reveal that tobacco consumption affects various epigenetic modifications, especially DNA methylation. However, the genetic modifications of methylation patterns involved in tobacco-attributable cancers remain poorly understood. In this manuscript, aberrant DNA methylation patterns were investigated in 9 tobacco-attributable cancers. Differential methylated probes (DMPs) were identified in each cancer type and a total of 2,392 hyper- and 736 hypomethylated pan-cancer DMPs (PDMPs) were screened out for further analysis. PDMP-associated genes were mostly enriched in metabolism-associated pathways, suggesting the potential roles of methylation alternation in reprogramming cancer cell metabolism. Hypomethylated PDMPs cg12422154, cg02772121 and cg06051311 constituted an enhancer region, significantly downregulating TRIM15, TRIM26 and RPP21, which serve as epigenetically therapeutic biomarkers. Forty-three hypermethylated and 13 hypomethylated transcription factor motifs were clustered into 6 groups, and exhibited various biological functions. Forty-nine PDMPs were reported to be associated with prognosis, providing effective tools to predict clinical outcomes. In summary, our studies revealed the characteristics, influences and potential mechanisms of DNA methylation patterns of tobacco-attributable cancer.

FOXC2/ADAM12-dependent radiosensitivity of head and neck squamous cell carcinoma cells

BACKGROUND

Radiotherapy greatly benefits patients with tumors, but not all patients show favorable treatment response. This study investigated the impact of forkhead box protein C2 (FOXC2)-mediated a disintegrin and metalloprotease 12 (ADAM12) on the radiosensitivity of head and neck squamous cell carcinoma (HNSCC).

METHODS

After transfection and ionizing radiation, the biological activities of HNSCC cells were assessed. The relationship between ADAM12 and FOXC2 was verified. A xenograft model was used to evaluate the effect of FOXC2 knockdown on HNSCC growth in the context of radiation therapy.

RESULTS

FOXC2 and ADAM12 were upregulated in irradiated CAL-27 and HN4 cells. Knockdown of FOXC2 suppressed the malignant behaviors of CAL-27 and HN4 cells and inhibited the growth of transplanted tumors in nude mice. FOXC2 could bind ADAM12 promoter. Overexpression of ADAM12 reversed the promotion of FOXC2 silencing on the radiosensitivity of HNSCC cells.

CONCLUSIONS

FOXC2 regulates the radiosensitivity of HNSCC by targeting ADAM12.

Circular RNA circNRIP1 plays oncogenic roles in the progression of osteosarcoma

Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. Increasing evidence suggests that aberrant expression of circRNAs is associated with the occurrence and progression of many cancers. Here, we investigated the role of circNRIP1 in osteosarcoma and explored its possible underlying mechanisms. Three pairs of osteosarcoma tissues and adjacent normal tissues were applied to the detection of altered expression of circRNAs through circRNAs microarray. And the level of circNRIP1 expression was elevated in osteosarcoma tissues. Compared with that in adjacent normal tissue, circNRIP1 expression level was obviously elevated in 100 osteosarcoma tissues. Besides, circNRIP1 knockdown inhibited proliferation and migration, promoted apoptosis of osteosarcoma cells. Bioinformatic analysis demonstrated circNRIP1 contributed to FOXC2 expression by sponging miR-199a. Furthermore, METTL3 elevated circNRIP1 expression level via m6A modification. In short, METTL3-induced circNRIP1 exerted an oncogenic role in osteosarcoma by sponging miR-199a, which may provide new ideas for the treatment of osteosarcoma.

Super-enhancer Acquisition Drives FOXC2 Expression in Middle Ear Cholesteatoma

Distinct histone modifications regulate gene expression in certain diseases, but little is known about histone epigenetics in middle ear cholesteatoma. It is known that histone acetylation destabilizes the nucleosome and chromatin structure and induces gene activation. The association of histone acetylation with chronic inflammatory diseases has been indicated in recent studies. In this study, we examined the localization of variously modified histone H3 acetylation at lysine 9, 14, 18, 23, and 27 in paraffin-embedded sections of human middle ear cholesteatoma (cholesteatoma) tissues and the temporal bones of an animal model of cholesteatoma immunohistochemically. As a result, we found that there was a significant increase of the expression levels of H3K27ac both in human cholesteatoma tissues and the animal model. In genetics, super-enhancers are clusters of enhancers that drive the transcription of genes involved in cell identity. Super-enhancers were originally defined using the H3K27ac signal, and then we used H3K27ac chromatin immunoprecipitation followed by sequencing to map the active cis-regulatory landscape in human cholesteatoma. Based on the results, we identified increased H3K27ac signals as super-enhancers of the FOXC2 loci, as well as increased protein of FOXC2 in cholesteatoma. Recent studies have indicated that menin-MLL inhibitor could suppress tumor growth through the control of histone H3 modification. In this study, we demonstrated that the expression of FOXC2 was inhibited by menin-MLL inhibitor in vivo. These findings indicate that FOXC2 expression under histone modifications promoted the pathogenesis of cholesteatoma and suggest that it may be a therapeutic target of cholesteatoma.

FOXC2 regulates the G2/M transition of stem cell-rich breast cancer cells and sensitizes them to PLK1 inhibition

Cancer cells with stem cell properties (CSCs) underpin the chemotherapy resistance and high therapeutic failure of triple-negative breast cancers (TNBCs). Even though CSCs are known to proliferate more slowly, they are sensitive to inhibitors of G2/M kinases such as polo-like kinase 1 (PLK1). Understanding the cell cycle regulatory mechanisms of CSCs will help target these cells more efficiently. Herein, we identify a novel role for the transcription factor FOXC2, which is mostly expressed in CSCs, in the regulation of cell cycle of CSC-enriched breast cancer cells. We demonstrate that FOXC2 expression is regulated in a cell cycle-dependent manner, with FOXC2 protein levels accumulating in G2, and rapidly decreasing during mitosis. Knockdown of FOXC2 in CSC-enriched TNBC cells delays mitotic entry without significantly affecting the overall proliferation rate of these cells. Moreover, PLK1 activity is important for FOXC2 protein stability, since PLK1 inhibition reduces FOXC2 protein levels. Indeed, FOXC2 expressing CSC-enriched TNBC cells are sensitive to PLK1 inhibition. Collectively, our findings demonstrate a novel role for FOXC2 as a regulator of the G2/M transition and elucidate the reason for the observed sensitivity of CSC-enriched breast cancer cells to PLK1 inhibitor.

Discovering key regulatory mechanisms from single-factor and multi-factor regulations in glioblastoma utilizing multi-dimensional data

Glioblastoma (GBM) is the most common malignant brain cancer in adults. Investigating the regulatory mechanisms underlying GBM is effective for the in-depth study of GBM. The Cancer Genome Atlas (TCGA) project is producing large-scale data and makes the comprehensive study of the diverse regulatory mechanisms underlying GBM possible. Although there have been research studies on GBM with large-scale data, distinguishing different regulatory mechanisms and identifying the key regulation types remain challenging. In this study, we integrated multi-dimensional data of differentially expressed genes in GBM: copy number variation (CNV), gene expression, miRNA expression and methylation, by performing partial correlation analysis with the Lasso technique. Our results showed that there were single-factor and multi-factor regulatory mechanisms in GBM. In further analysis of the regulation subtypes, we discovered that single-factor and multi-factor regulations are potentially distinct in functionality. Moreover, multi-factor regulations especially the key regulation subtypes may be more relevant to GBM and affect many GBM-related genes such as ERBB2 and MAPK1. This study not only verifies the utility of multi-dimensional data integration into GBM research but also distinguishes the key multi-factor regulatory subtypes that may drive pathogenesis of GBM from various regulatory mechanisms.

FOXC2 expression is associated with tumor proliferation and invasion potential in oral tongue squamous cell carcinoma

Forkhead box protein C2 (FOXC2) is a gene encoding a transcription factor that controls the generation of mesodermal tissue including vascular and lymphatic tissues. FOXC2 has previously been associated with EMT and tumor angiogenesis in various cancers. Moreover, a relationship between the expression of FOXC2 and poor prognosis has been reported in various cancers. We herein examined the clinicopathological significance of FOXC2 in oral tongue squamous cell carcinoma (OTSCC) and attempted to clarify the function of FOXC2 in OTSCC cell lines in vitro. The overexpression of FOXC2 was more frequent in cancers with higher grades according to the pattern of invasion (grade 4 vs. 1-3; p < 0.05). A correlation was observed between the expression of FOXC2 and that of VEGF-A and -C (VEGF-A; p < 0.05, VEGF-C; p < 0.001). The high-FOXC2 expression group had a significantly poorer prognosis than that of the low-expression group (p < 0.001). Multivariate analysis indicated that the overexpression of FOXC2 may also be an independent prognostic factor, similar to N classification (N0 vs 1/2; p < 0.05), stage classification (stage I/II vs III/IV; p < 0.05), pattern of invasion (grade 1-3vs 4; p < 0.05), local recurrence (local recurrence (+) vs (-); p < 0.01), and the overexpression of FOXC2 (FOXC2 overexpression (-) vs.(+); p < 0.05). In the OTSCC cell line analysis, the expression of FOXC2 was also associated with proliferation and invasion potential. These results strongly suggest that the overexpression of FOXC2 may be a potent predictor of survival in OTSCC patients.