Prognostic impact of transcription factor Fra-1 in ER-positive breast cancer: contribution to a metastatic phenotype through modulation of tumor cell adhesive properties

FOSL1's Oncogene Roles in Glioma/Glioma Stem Cells and Tumorigenesis: A Comprehensive Review

This review specifically examines the important function of the oncoprotein FOSL1 in the dimeric AP-1 transcription factor, which consists of FOS-related components. FOSL1 is identified as a crucial controller of invasion and metastatic dissemination, making it a potential target for therapeutic treatment in cancer patients. The review offers a thorough examination of the regulatory systems that govern the influence exerted on FOSL1. These include a range of changes that occur throughout the process of transcription and after the translation of proteins. We have discovered that several non-coding RNAs, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play a significant role in regulating FOSL1 expression by directly interacting with its mRNA transcripts. Moreover, an investigation into the functional aspects of FOSL1 reveals its involvement in apoptosis, proliferation, and migration. This work involves a comprehensive analysis of the complex signaling pathways that support these diverse activities. Furthermore, particular importance is given to the function of FOSL1 in coordinating the activation of several cytokines, such as TGF-beta, and the commencement of IL-6 and VEGF production in tumor-associated macrophages (TAMs) that migrate into the tumor microenvironment. There is a specific emphasis on evaluating the predictive consequences linked to FOSL1. Insights are now emerging on the developing roles of FOSL1 in relation to the processes that drive resistance and reliance on specific treatment methods. Targeting FOSL1 has a strong inhibitory effect on the formation and spread of specific types of cancers. Despite extensive endeavors, no drugs targeting AP-1 or FOSL1 for cancer treatment have been approved for clinical use. Hence, it is imperative to implement innovative approaches and conduct additional verifications.

FRA-1: A key factor regulating signal transduction of tumor cells and a potential target molecule for tumor therapy

Fos-related antigen-1 (FRA-1) is a member of activator protein-1 (AP-1) transcription factor superfamily, and FRA-1 is highly expressed in colon cancer, breast cancer, gastric cancer, lung cancer, bladder cancer, and other tumors. The expression level of FRA-1 is closely related to the processes of tumor cell proliferation, apoptosis, transformation, migration, and invasion, which is a potential therapeutic target and prognostic factor for many tumors. Clarifying the detailed mechanism of action of FRA-1 could provide the theoretical basis for tumor diagnosis, treatment, and prognosis, and is of great significance for the study of tumor etiology and pathogenesis. In this paper, the expression levels and influencing factors of FRA-1 in various tumor tissues and cells are summarized, as well as the effect of FRA-1 expression level on the biological behavior of tumor cells and the signal transduction mechanism. At the same time, the signal transduction mechanism of FRA-1 in inflammation was expounded. In addition, the related metabolites, drugs and non-coding RNA that affect the expression and function of FRA-1 were summarized. Finally, it illustrates that FRA-1 may be taken as a key factor for tumor prognosis and a potential therapeutic target. This review provides a theoretical basis for the systematic understanding of the relationship between FRA-1 and tumors, its function, and possible mechanism.

Fra-2 overexpression upregulates pro-metastatic cell-adhesion molecules, promotes pulmonary metastasis, and reduces survival in a spontaneous xenograft model of human breast cancer

Purpose

The transcription factor Fra-2 affects the invasive potential of breast cancer cells by dysregulating adhesion molecules in vitro. Previous results suggested that it upregulates the expression of E- and P-selectin ligands. Such selectin ligands are important members of the leukocyte adhesion cascade, which govern the adhesion and transmigration of cancer cells into the stroma of the host organ of metastasis. As so far, no in vivo data are available, this study was designed to elucidate the role of Fra-2 expression in a spontaneous breast cancer metastasis xenograft model.

Methods

The effect of Fra-2 overexpression in two stable Fra-2 overexpressing clones of the human breast cancer cell line MDA MB231 on survival and metastatic load was studied after subcutaneous injection into scid and E- and P-selectin-deficient scid mice.

Results

Fra-2 overexpression leads to a significantly shorter overall survival and a higher amount of spontaneous lung metastases not only in scid mice, but also in E- and P-deficient mice, indicating that it regulates not only selectin ligands, but also selectin-independent adhesion processes.

Conclusion

Thus, Fra-2 expression influences the metastatic potential of breast cancer cells by changing the expression of adhesion molecules, resulting in increased adherence to endothelial cells in a breast cancer xenograft model.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03812-2.

Fra-1 Inhibits Cell Growth and the Warburg Effect in Cervical Cancer Cells via STAT1 Regulation of the p53 Signaling Pathway

The oncogenesis of cervical cancer is a multi-factor and multi-step process, and major risk factors include oncogene activation with tumor suppressor gene inactivation, viral factors, and immune factors. For example, the human papillomavirus (HPV) has been linked to the occurrence of cervical cancer. At present, the pathogenesis of cervical cancer remains unclear. Fra-1 (Fos-related antigen 1, also known as FOSL1) is a member of the Fos family and an important nuclear transcription factor that regulates normal cell growth, differentiation, and apoptosis. In the present study, we found that Fra-1 inhibited the proliferation of cervical cancer cells while also promoting apoptosis and affecting cell cycle distribution. Moreover, Fra-1 up-regulated STAT1 expression and modulated p53 signal pathway activity in cervical cancer cells. Overexpression of Fra-1 inhibited cell senescence by altering sirtuin 1 (SIRT1) expression in HeLa cells, and Fra-1 overexpression restored mitochondrial disorder and suppressed metabolic reprogramming in HeLa cells. Silencing of STAT1 impaired the inhibitory effect of Fra-1 on cervical cancer cell growth, while knock-down of STAT1 reversed the effect on cell senescence and mitochondrial dysfunction caused by Fra-1 in HeLa cells. Silencing of STAT1 also recovered metabolic reprogramming in cervical cancer cells. In summary, our results show that Fra-1 inhibited cervical cancer cell growth and the Warburg effect via STAT1-mediated regulation of the p53 signaling pathway.

Tubulin Tyrosine Ligase Like 4 (TTLL4) overexpression in breast cancer cells is associated with brain metastasis and alters exosome biogenesis

BACKGROUND

The survival rate is poor in breast cancer patients with brain metastases. Thus, new concepts for therapeutic approaches are required. During metastasis, the cytoskeleton of cancer cells is highly dynamic and therefore cytoskeleton-associated proteins are interesting targets for tumour therapy.

METHODS

Screening for genes showing a significant correlation with brain metastasis formation was performed based on microarray data from breast cancer patients with long-term follow up information. Validation of the most interesting target was performed by MTT-, Scratch- and Transwell-assay. In addition, intracellular trafficking was analyzed by live-cell imaging for secretory vesicles, early endosomes and multiple vesicular bodies (MVB) generating extracellular vesicles (EVs). EVs were characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), Western blotting, mass spectrometry, and ingenuity pathway analysis (IPA). Effect of EVs on the blood-brain-barrier (BBB) was examined by incubating endothelial cells of the BBB (hCMEC/D3) with EVs, and permeability as well as adhesion of breast cancer cells were analyzed. Clinical data of a breast cancer cohort was evaluated by χ2-tests, Kaplan-Meier-Analysis, and log-rank tests while for experimental data Student's T-test was performed.

RESULTS

Among those genes exhibiting a significant association with cerebral metastasis development, the only gene coding for a cytoskeleton-associated protein was Tubulin Tyrosine Ligase Like 4 (TTLL4). Overexpression of TTLL4 (TTLL4plus) in MDA-MB231 and MDA-MB468 breast cancer cells (TTLL4plus cells) significantly increased polyglutamylation of β-tubulin. Moreover, trafficking of secretory vesicles and MVBs was increased in TTLL4plus cells. EVs derived from TTLL4plus cells promote adhesion of MDA-MB231 and MDA-MB468 cells to hCMEC/D3 cells and increase permeability of hCMEC/D3 cell layer.

CONCLUSIONS

These data suggest that TTLL4-mediated microtubule polyglutamylation alters exosome homeostasis by regulating trafficking of MVBs. The TTLL4plus-derived EVs may provide a pre-metastatic niche for breast cancer cells by manipulating endothelial cells of the BBB.

Expression and function of FRA1 protein in tumors

AP-1 is a dimeric complex that is composed of JUN, FOS, ATF and MAF protein families. FOS-related antigen 1 (FRA1) which encoded by FOSL1 gene, belongs to the FOS protein family, and mainly forms an AP-1 complex with the protein of the JUN family to exert an effect. Regulation of FRA1 occurs at levels of transcription and post-translational modification, and phosphorylation is the major post-translational modification. FRA1 is mainly regulated by the mitogen-activated protein kinases signaling pathway and is degraded by ubiquitin-independent proteasomes. FRA1 can affect biological functions, such as tumor proliferation, differentiation, invasion and apoptosis. Studies have demonstrated that FRA1 is abnormally expressed in many tumors and plays a relevant role, but the specific condition varies from the target organs. FRA1 is overexpressed in breast cancer, lung cancer, colorectal cancer, prostate cancer, nasopharyngeal cancer, thyroid cancer and other tumors. However, the expression of FRA1 is decreased in cervical cancer, and the expression of FRA1 in ovarian cancer and oral squamous cell carcinoma is still controversial. In this review, we present a detailed description of the regulatory factors and functions of FRA1, also, the expression of FRA1 in various tumors and its function in relative tumor.

[Expression of the Fra-1 gene in the peripheral blood of children with Wilms tumor]

OBJECTIVE

To study the expression of the Fra-1 gene in the peripheral blood of children with Wilms tumor and its clinical significance.

METHODS

Fifty children pathologically diagnosed with Wilms tumor between December 2012 and January 2018 were enrolled as the case group, and 40 healthy children for physical examination were selected as the control group. Among the 45 children with Wilms tumor who were followed up, the children with continuous remission were included in the ideal efficacy group (n=33), and those with recurrence, metastasis or death were included in the poor efficacy group (n=12). Peripheral blood samples were collected from all subjects. Quantitative real-time PCR was used to measure the mRNA expression of Fra-1.

RESULTS

The case group had significantly higher mRNA expression of Fra-1 in peripheral blood than the control group (P<0.05). In the case group, Fra-1 mRNA expression was significantly different between the individuals with and without distant metastasis and those with different TNM stages (P<0.05), but was not significantly different between the individuals with different sexes, ages, tumor diabetes, tumor locations and alpha-fetoprotein levels (P>0.05). The mRNA expression of Fra-1 was significantly lower in the ideal efficacy group than in the poor efficacy group (P<0.05).

CONCLUSIONS

Fra-1 may be involved in the development of Wilms tumor and plays a certain role in its development, invasion and metastasis, but the mechanism remains to be further studied.

HER2 in stemness and epithelial-mesenchymal plasticity of breast cancer

Breast cancer had been the first non-hematologic malignancy where sub-types based on molecular characterization had entered clinical practice. HER2 over-expression, due to either gene amplification or protein up-regulation, defines one of these sub-types and is clinically exploited by addition of HER2-targeted treatments to the regimens of treatment. Nevertheless, in many occasions HER2-positive cancers are resistant or become refractory to these therapies. Several mechanisms, such as activation of alternative pathways or loss of expression of the receptor in cancer cells, have been proposed as the cause of these therapeutic failures. Cancer stem cells (CSCs, alternatively called tumor-initiating cells) comprise a small percentage of the tumor cells, but are capable of reconstituting and propagating tumors due to their superior intrinsic capacity for regeneration, survival and resistance to therapies. CSCs possess circuits enabling epigenetic plasticity which endow them with the ability to alternate between epithelial and mesenchymal states. This paper will discuss the expression and regulation of HER2 in CSCs of the different sub-types of breast cancer and relationships of the receptor with both the circuits of stemness and epithelial-mesenchymal plasticity. Therapeutic repercussions of the relationship of HER2-initiated signaling with stemness networks will also be proposed.

Integrin-uPAR signaling leads to FRA-1 phosphorylation and enhanced breast cancer invasion

Background

The Fos-related antigen 1 (FRA-1) transcription factor promotes tumor cell growth, invasion and metastasis. Phosphorylation of FRA-1 increases protein stability and function. We identify a novel signaling axis that leads to increased phosphorylation of FRA-1, increased extracellular matrix (ECM)-induced breast cancer cell invasion and is prognostic of poor outcome in patients with breast cancer.

Methods

While characterizing five breast cancer cell lines derived from primary human breast tumors, we identified BRC-31 as a novel basal-like cell model that expresses elevated FRA-1 levels. We interrogated the functional contribution of FRA-1 and an upstream signaling axis in breast cancer cell invasion. We extended this analysis to determine the prognostic significance of this signaling axis in samples derived from patients with breast cancer.

Results

BRC-31 cells display elevated focal adhesion kinase (FAK), SRC and extracellular signal-regulated (ERK2) phosphorylation relative to luminal breast cancer models. Inhibition of this signaling axis, with pharmacological inhibitors, reduces the phosphorylation and stabilization of FRA-1. Elevated integrin α_Vβ₃ and uPAR expression in these cells suggested that integrin receptors might activate this FAK-SRC-ERK2 signaling. Transient knockdown of urokinase/plasminogen activator urokinase receptor (uPAR) in basal-like breast cancer cells grown on vitronectin reduces FRA-1 phosphorylation and stabilization; and uPAR and FRA-1 are required for vitronectin-induced cell invasion. In clinical samples, a molecular component signature consisting of vitronectin-uPAR-uPA-FRA-1 predicts poor overall survival in patients with breast cancer and correlates with an FRA-1 transcriptional signature.

Conclusions

We have identified a novel signaling axis that leads to phosphorylation and enhanced activity of FRA-1, a transcription factor that is emerging as an important modulator of breast cancer progression and metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0936-8) contains supplementary material, which is available to authorized users.

[Spleen tyrosine kinase inhibits proliferation and promotes apoptosis of colorectal cancer cells in vitro via regulating Fra-1]

OBJECTIVE

To investigate the effects of spleen tyrosine kinase (SYK) overexpression on proliferation and apoptosis of colorectal cancer cells and explore the possible mechanism.

METHODS

The mRNA expressions of SYK and Fra?1 in 10 clinical specimens of colorectal cancer and 10 adjacent tissues were measured with qRT?PCR, and their protein expressions were detected with Western blotting. The recombinant plasmid pcDNA.3.1?SYK was constructed and transfected into colorectal cancer cells to induce SYK overexpression, and the cell viability and proliferation were assessed using by MTT assay and BrdU assay, respectively; caspase?3 activity in the cells was evaluated with a commercial kit and the cell apoptosis was analyzed with Annexin?V FITC/PI assay.

RESULTS

The expressions of SYK were significantly decreased in colorectal cancer tissues and colorectal cancer cell lines. Transfection of pcDNA.3.1?SYK into the colorectal cancer cells induced obviously upregulated mRNA and protein expressions of SYK, which caused a significant suppression of the cell viability and proliferation and enhancement of the cell apoptosis along with a significant inhibition of Fra?1 expression.

CONCLUSION

s SYK overexpression inhibits the proliferation and promotes apoptosis of colorectal cancer cells, and these effects are possibly mediated by the regulation of Fra?1 expression by SYK.

Prognostic value from integrative analysis of transcription factors c-Jun and Fra-1 in oral squamous cell carcinoma: a multicenter cohort study

Transcription factors c-Jun and Fra-1 have been reported to play a role during the initiation and progression in oral squamous cell carcinoma (OSCC). However, cohort studies are rarely reported. Here is an integrative analysis of their prognostic value in OSCC through a multicenter cohort study.313 OSCC patients were included in this study and received regular follow-up. The survival rate and hazard ratios(HR) were generated by survival analysis. The concordance probability and receiver operating characteristic curve area were chosen to measure the model discrimination. High expressions of c-Jun or Fra-1 were associated with poor prognosis, meanwhile the high expression of Fra-1 meant worse prognosis of patients than the high expression of c-Jun. Besides, the interaction effect of c-Jun and Fra-1 was antagonism, when the expression of c-Jun and Fra-1 was both high, the HR was lower than the hazard ratio when only the Fra-1 was at high expression. c-Jun and Fra-1 were both proved to be high risky predictors of death in OSCC, the antagonistic effect suggested that these biomarkers’ activities could be influenced by each other. It may provide a new sight for the studies of OSCC prognosis and treatment.

Expression of Fra-1 in human hepatocellular carcinoma and its prognostic significance

This study aimed to explore the clinical significance and prognostic value of Fra-1 in hepatocellular carcinoma patients after curative resection. Fra-1 expression was investigated using a combination of techniques: immunohistochemistry for 66 samples of hepatocellular carcinoma and quantitative real-time polymerase chain reaction and western blotting assays for 19 matched hepatocellular carcinoma specimens. Fra-1 was present in 38 of 66 (57.6%) tumor tissues, with intense staining in the nuclei. There was also positive staining in 14 of 66 (21.2%) adjacent peritumoral tissues, with weak staining in the cytoplasm. Quantitative real-time polymerase chain reaction and western blotting assays confirmed higher expression of Fra-1 messenger RNA and Fra-1 protein in tumor tissues than adjacent non-tumor tissues for 19 hepatocellular carcinoma samples (p < 0.001). Positive expression of Fra-1 was significantly related to vascular invasion and serum alpha-fetoprotein. Kaplan-Meier survival analysis found that overexpressed Fra-1 was correlated with poor overall survival and disease-free survival. Multivariate analysis identified Fra-1 as an independent prognostic factor. Fra-1 may be involved in the progress of hepatocellular carcinoma and could be a promising molecular candidate in the diagnosis and treatment of hepatocellular carcinoma.

Fra-1 is upregulated in lung cancer tissues and inhibits the apoptosis of lung cancer cells by the P53 signaling pathway

Fos-related antigen-1 (Fra-1) is a member of the activator protein-1 transcription factor superfamily. It plays important roles in oncogenesis in various types of malignancies. Herein, we investigated the expression of Fra-1 in lung cancer tissues by qPCR, immunohistochemistry, and western blot technologies. The results showed that Fra-1 was overexpressed in the lung cancer tissues when compared with the level in the adjacent non-cancerous tissues. To explore the possible mechanism of Fra-1 in lung cancer, we elucidated the effect of Fra-1 on the apoptosis of lung cancer H460 cells, and found that the rate of cell apoptosis was decreased in the H460/Fra-1 cells compared with the H460 or H460/vector cells. Cell apoptosis is closely related with a reduction in mitochondrial membrane potential (ΔΨm) and an increase in intracellular reactive oxygen species (ROS) and calcium ion (Ca2+) concentrations. Our results showed that overexpression of Fra-1 in the lung cancer H460 cells, led to an increase in ΔΨm and and a decrease in intracellular ROS and Ca2+ concentrations. Furthermore, we found that Fra-1 was correlated with dysregulation of the P53 signaling pathway in lung cancer tissues in vitro. At the same time, we found that Fra-1 overexpression affected the expression of MDM2 and P53 in vivo. In summary, our results suggest that Fra-1 is upregulated in lung cancer tissues and functions by affecting the P53 signaling pathway in lung cancer.

Fra-1 is upregulated in gastric cancer tissues and affects the PI3K/Akt and p53 signaling pathway in gastric cancer

Gastric cancer is an aggressive disease that continues to have a daunting impact on global health. Fra-1 (FOSL1) plays important roles in oncogenesis in various malignancies. We investigated the expression of Fra-1 in gastric cancer (GC) tissues by qPCR, immunohistochemistry (IHC) and western blot technologies. The results showed that Fra-1 was overexpressed in gastric cancer tissues compared with the adjacent non‑cancerous tissues. To explore the possible mechanism of Fra-1 in GC, we elucidated the effect of Fra-1 in the apoptosis and cell cycle of gastric cancer cells, AGS, and found that a considerable decrease in apoptotic cells and increase of S phase rate were observed for AGS cells with Fra-1 overexpession. We identified and confirmed that Fra-1 affected the expression level of CTTN and EZR in vitro through LC-MS/MS analyses and western blot technology. Furthermore, we found that Fra-1 was correlated with dysregulation PI3K/Akt and p53 signaling pathway in gastric cancer tissues in vitro. Moreover, we found that Fra-1 overexpression affected the expression of PI3K, Akt, MDM2 and p53 in vivo. In summary, our results suggest that Fra-1 is upregulated in gastric cancer tissues and plays its function by affecting the PI3K/Akt and p53 signaling pathway in gastric cancer.