Fra-1/AP-1 induces EMT in mammary epithelial cells by modulating Zeb1/2 and TGFβ expression

Umbelliprenin attenuates comorbid behavioral disorders in acetic acid-induced colitis in mice: mechanistic insights into hippocampal oxidative stress and neuroinflammation

Inflammatory bowel disease (IBD) is often accompanied by psychiatric disorders. Emerging evidence suggests that neuroinflammation and oxidative stress contribute to the psychiatric symptoms associated with IBD. Umbelliprenin (UMB) possesses several pharmacological properties, including anti-inflammatory and antioxidant effects. This study aimed to investigate the protective effects of UMB on comorbid behavioral disorders in a mouse model of experimental colitis, focusing on its potential anti-neuroinflammatory and antioxidant activities. After inducing colitis with acetic acid, male NMRI mice were treated for 7 consecutive days with UMB, saline, or dexamethasone. Behavioral assessments included the forced swimming test (FST), splash test, open field test (OFT), and elevated plus maze (EPM). Histopathological changes in the colon were evaluated, and total antioxidant capacity (TAC), malondialdehyde (MDA) levels, and the expression of inflammatory genes (TNFα, IL1β, and TLR4) were measured in the hippocampus. Colitis was associated with increased immobility time in the FST, reduced entries and time spent in the open arms of the EPM, decreased grooming behavior in the splash test, and reduced time spent in the central zone of the OFT. Colitis also resulted in a reduction in TAC and an increase in MDA levels and inflammatory gene expression in the hippocampus. UMB treatment mitigated the behavioral disorders associated with colitis, reduced neuroinflammation and oxidative stress in the hippocampus, and alleviated histopathological alterations in the colon. In conclusion, UMB may reduce behavioral disorders induced by colitis by decreasing oxidative stress and neuroinflammation in the hippocampus.

ZEB1 Promotes Epithelial-Mesenchymal Transition of Endometrial Epithelial Cells and Plays a Critical Role in Embryo Implantation in Mice

Zinc finger E-box binding homeobox 1 (ZEB1) promotes epithelial-mesenchymal transition (EMT) in carcinogenesis, but its role in embryo implantation has not yet been well studied. In the present study we evaluated the hypothesis that ZEB1-induced EMT is essential for embryo implantation in vivo. Endometrial epithelium from female Kunming mice (non-pregnant, and pregnant from day 2.5 to 6.5) were collected for assessment of mRNA/protein expression of ZEB1, and EMT markers E-cadherin and vimentin, by employment of real-time quantitative reverse transcription PCR, Western blot, and immunohistochemical staining. To test if knockdown of ZEB1 affects embryo implantation in vivo, mice received intrauterine injection of shZEB1 before the number of embryos implanted was counted. The results showed that, ZEB1 was highly expressed at both mRNA and protein levels in the mouse endometrium on day 4.5 of pregnancy, paralleled with down-regulated E-cadherin and up-regulated vimentin expression (P < 0.05). Intrauterine injection of shZEB1 markedly suppressed embryo implantation in mice (P < 0.01). Conclusively, the present work demonstrated that ZEB1 is essential for embryo implantation under in vivo condition, and is possibly due to its effect on modulation of endometrial receptivity through EMT.

Neuroimmune response and oxidative stress in the prefrontal cortex mediate seizure susceptibility in experimental colitis in male mice

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder. Oxidative stress and inflammatory responses have a vital role in the pathophysiology of IBD as well as seizure. IBD is associated with extraintestinal manifestations. This study aimed to explore the relationship between colitis and susceptibility to seizures, with a focus on the roles of neuroinflammation and oxidative stress in acetic acid-induced colitis in mice. Forty male Naval Medical Research Institute mice were divided into four groups: control, colitis, pentylenetetrazole (PTZ), and colitis + PTZ. Colitis was induced by intrarectal administration of acetic acid, and seizures were induced by intravenous injection of PTZ 7 days postcolitis induction. Following the measurement of latency to seizure, the mice were killed, and their colons and prefrontal cortex (PFC) were dissected. Gene expression of inflammatory markers including interleukin-1β, tumor necrosis factor-alpha, NOD-like receptor protein 3, and toll-like receptor 4, as well as total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrite levels were measured in the colon and PFC. Histopathological evaluations were performed on the colon samples. Data were analyzed by t-test or one-way variance analysis. Colitis decreased latency to seizure, increased gene expression of inflammatory markers, and altered levels of MDA, nitrite, and TAC in both the colon and PFC. Simultaneous induction of colitis and seizure exacerbated the neuroimmune response and oxidative stress in the PFC and colon. Results concluded that neuroinflammation and oxidative stress in the PFC at least partially mediate the comorbid decrease in seizure latency in mice with colitis.

Machine learning identifies activation of RUNX/AP-1 as drivers of mesenchymal and fibrotic regulatory programs in gastric cancer

Gastric cancer (GC) is the fifth most common cancer worldwide and is a heterogeneous disease. Among GC subtypes, the mesenchymal phenotype (Mes-like) is more invasive than the epithelial phenotype (Epi-like). Although gene expression of the epithelial-to-mesenchymal transition (EMT) has been studied, the regulatory landscape shaping this process is not fully understood. Here we use ATAC-seq and RNA-seq data from a compendium of GC cell lines and primary tumors to detect drivers of regulatory state changes and their transcriptional responses. Using the ATAC-seq data, we developed a machine learning approach to determine the transcription factors (TFs) regulating the subtypes of GC. We identified TFs driving the mesenchymal (RUNX2, ZEB1, SNAI2, AP-1 dimer) and the epithelial (GATA4, GATA6, KLF5, HNF4A, FOXA2, GRHL2) states in GC. We identified DNA copy number alterations associated with dysregulation of these TFs, specifically deletion of GATA4 and amplification of MAPK9 Comparisons with bulk and single-cell RNA-seq data sets identified activation toward fibroblast-like epigenomic and expression signatures in Mes-like GC. The activation of this mesenchymal fibrotic program is associated with differentially accessible DNA cis-regulatory elements flanking upregulated mesenchymal genes. These findings establish a map of TF activity in GC and highlight the role of copy number driven alterations in shaping epigenomic regulatory programs as potential drivers of GC heterogeneity and progression.

Epigenomic signatures of sarcomatoid differentiation to guide the treatment of renal cell carcinoma

Renal cell carcinoma with sarcomatoid differentiation (sRCC) is associated with poor survival and a heightened response to immune checkpoint inhibitors (ICIs). Two major barriers to improving outcomes for sRCC are the limited understanding of its gene regulatory programs and the low diagnostic yield of tumor biopsies due to spatial heterogeneity. Herein, we characterized the epigenomic landscape of sRCC by profiling 107 epigenomic libraries from tissue and plasma samples from 50 patients with RCC and healthy volunteers. By profiling histone modifications and DNA methylation, we identified highly recurrent epigenomic reprogramming enriched in sRCC. Furthermore, CRISPRa experiments implicated the transcription factor FOSL1 in activating sRCC-associated gene regulatory programs, and FOSL1 expression was associated with the response to ICIs in RCC in two randomized clinical trials. Finally, we established a blood-based diagnostic approach using detectable sRCC epigenomic signatures in patient plasma, providing a framework for discovering epigenomic correlates of tumor histology via liquid biopsy.

The IL-33-ST2 axis plays a vital role in endometriosis via promoting epithelial-mesenchymal transition by phosphorylating β-catenin

OBJECTIVES

Interleukin 33 (IL-33) is a crucial inflammatory factor that functions as an alarm signal in endometriosis (EMs). Epithelial-mesenchymal transition (EMT), a process related to inflammatory signals, intracellular reactive oxygen species (ROS) production, and lipid peroxidation, have been proposed as potential mechanisms that contribute to the development and progression of EMs. IL-33 is highly upregulated in the ectopic milieu. Moreover, ectopic endometrial cells constitutively express interleukin-33 receptor ST2 (IL-33R). However, the role of IL-33/ST2 in the EMT of EMs remains largely unknown. In this study, we aimed to mechanistically determine the role of IL-33/ST2 in EMs-associated fibrosis.

MATERIALS AND METHODS

We established a non-lethal oxidative stress model to explore the conditions that trigger IL-33 induction. We performed α-smooth muscle actin (α-SMA) protein detection, cell counting kit-8 (CCK-8) assays, and scratch assays to analyze the impact of IL-33 on primary endometrial stromal cells (ESCs) proliferation and invasion. Clinical samples from patients with or without EMs were subjected to immunohistochemical (IHC) and and immunofluorescence(IF) staining to assess the clinical relevance of IL-33 receptor ST2 and EMT-related proteins. Furthermore, we used the ectopic human endometrial epithelial cell line 12Z and normal human epithelial cell line EEC to evaluate the effects of IL-33 on Wnt/β-catenin signaling. The effect of IL-33 on EMT-associated fibrosis was validated in vivo by intraperitoneal injections of IL-33 and antiST2.

RESULTS

We observed that ectopic milieu, characterized by ROS, TGF-β1, and high level of estrogen, triggers the secretion of IL-33 from ectopic ESCs. Ectopic endometrial lesions exhibited higher level of fibrotic characteristics and ST2 expression than that in the normal endometrium. Exogenous recombinant human (rhIL-33) enhanced ESC migration and survival. Similarly, 12Z cells displayed a higher degree of EMT characteristics with elevated expression of CCN4 and Fra-1, downstream target genes of the WNT/β-catenin pathway, than that observed in EECs. Conversely, blocking IL-33 with neutralizing antibodies, knocking down ST2 or β-catenin with siRNA, and β-catenin dephosphorylation abolished its effects on EMT promotion. In vivo validation demonstrated that IL-33 significantly promotes EMs-related fibrosis through the activation of Wnt/β-catenin signaling.

CONCLUSION

Our data strongly support the vital role of the IL-33/ST2 pathway in EMs-associated fibrosis and emphasize the importance of the EMT in the pathophysiology of fibrosis. Targeting the IL-33/ST2/Wnt/β-catenin axis may hold promise as a feasible therapeutic approach for controlling fibrosis in EMs.

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.

IKBKE promotes the ZEB2-mediated EMT process by phosphorylating HMGA1a in glioblastoma

IKBKE (Inhibitor of Nuclear Factor Kappa-B Kinase Subunit Epsilon) is an important oncogenic protein in a variety of tumors, which can promote tumor growth, proliferation, invasion and drug resistance, and plays a critical regulatory role in the occurrence and progression of malignant tumors. HMGA1a (High Mobility Group AT-hook 1a) functions as a cofactor for proper transcriptional regulation and is highly expressed in multiple types of tumors. ZEB2 (Zinc finger E-box Binding homeobox 2) exerts active functions in epithelial mesenchymal transformation (EMT). In our current study, we confirmed that IKBKE can increase the proliferation, invasion and migration of glioblastoma cells. We then found that IKBKE can phosphorylate HMGA1a at Ser 36 and/or Ser 44 sites and inhibit the degradation process of HMGA1a, and regulate the nuclear translocation of HMGA1a. Crucially, we observed that HMGA1a can regulate ZEB2 gene expression by interacting with ZEB2 promoter region. Hence, HMGA1a was found to promote the ZEB2-related metastasis. Consequently, we demonstrated that IKBKE can exert its oncogenic functions via the IKBKE/HMGA1a/ZEB2 signalling axis, and IKBKE may be a prominent biomarker for the treatment of glioblastoma in the future.

Jun/Fos promotes migration and invasion of hepatocellular carcinoma cells by enhancing BORIS promoter activity

The Brother of the Regulator of Imprinted Sites (BORIS), as a specific indicator of hepatocellular carcinoma, exhibits a significant increase in expression. However, its upstream regulatory network remains enigmatic. Previous research has indicated a strong correlation between the Hippo pathway and the progression of hepatocellular carcinoma. It is well established that the Activator Protein-1 (AP-1) frequently engages in interactions with the Hippo pathway. Thus, we attempt to prove whether Jun and Fos, a major member of the AP-1 family, are involved in the regulation of BORIS expression. Bioinformatics analysis revealed the existence of binding sites for Jun and Fos within the BORIS promoter. Through a series of overexpression and knockdown experiments, we corroborated that Jun and Fos have the capacity to augment BORIS expression, thereby fostering the migration and invasion of hepatocellular carcinoma cells. Moreover, Methylation-Specific PCR and Bisulfite Sequencing PCR assays revealed that Jun and Fos do not have a significant impact on the demethylation of the BORIS promoter. However, luciferase reporter and chromatin immunoprecipitation experiments substantiated that Jun and Fos could directly bind to the BORIS promoter, thereby enhancing its transcription. In conclusion, these results suggest that Jun and Fos can promote the development of hepatocellular carcinoma by directly regulating the expression of BORIS. These findings may provide experimental evidence positioning BORIS as a novel target for the clinical intervention of hepatocellular carcinoma.

Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner

The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; BrafCA; Ptenlox/+ melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2.

The role of ERp29/FOS/EMT pathway in excessive apoptosis of placental trophoblast cells in intrahepatic cholestasis of pregnancy

BACKGROUND

Abnormal bile acid metabolism leading to changes in placental function during pregnancy. To determine whether endoplasmic reticulum protein 29 (ERp29) can mediate the pregnancy effects of cholestasis by altering the level of trophoblast cell apoptosis.

METHODS

ERp29 in serum of 66 intrahepatic cholestasis of pregnancy (ICP) pregnant women and 74 healthy were detected by ELISA. Subcutaneous injection of ethinyl estradiol (E2) was used to induce ICP in pregnant rats. Taurocholic acid (TCA) was used to simulate the ICP environment, and TGF-β1 was added to induce the epithelial mesenchymal transformation (EMT) process. The scratch, migration, and invasion test were used to detect the EMT process. ERp29 overexpression/knockdown vector were constructed and transfected to verify the role of ERp29 in the EMT process. Downstream gene was obtained through RNA-seq.

RESULTS

Compared with the healthy pregnant women, the expression levels of ERp29 in serum of ICP pregnancy women were significantly increased (P < 0.001). ERp29 in the placenta tissue of the ICP pregnant rats increased significantly, and the level of apoptosis increased. The placental tissues of the ICP had high expression of E-cadherin and low expression of N-cadherin, snail1, vimentin. After HTR-8/SVneo cells were induced by TCA, EMT was inhibited, while the ERp29 increased. Cell and animal experiments showed that, knockdown of ERp29 reduced the inhibition of EMT, the ICP progress was alleviated. Overexpression of FOS salvaged the inhibitory effects of ERp29 on cell EMT.

DISCUSSION

The high level of ERp29 in placental trophoblast cells reduced FOS mRNA levels, inhibited the EMT process and aggravated the occurrence and development of ICP.

MET exon 14 skipping mutation drives cancer progression and recurrence via activation of SMAD2 signalling

BACKGROUND

c-Met encoded by the proto-oncogene MET, also known as hepatocyte growth factor (HGF) receptor, plays a crucial role in cellular processes. MET exon 14 skipping alteration (METΔ14EX) is a newly discovered MET mutation. SMAD2 is an important downstream transcription factor in TGF-β pathway. Unfortunately, the mechanisms by which METΔ14EX leads to oncogenic transformation are scarcely understood. The relationship between METΔ14EX and SMAD2 has not been studied yet.

METHODS

We generate METΔ14EX models by CRISPR-Cas9. In vitro transwell, wound-healing, soft-agar assay, in vivo metastasis and subcutaneous recurrence assay were used to study the role of METΔ14EX in tumour progression. RNA-seq, Western blotting, co-immunoprecipitation (CO-IP) and immunofluorescent were performed to explore the interaction between c-Met and SMAD2.

RESULTS

Our results demonstrated that METΔ14EX, independent of HGF, can prolong the constitutive activation of c-Met downstream signalling pathways by impeding c-Met degradation and facilitating tumour metastasis and recurrence. Meanwhile, METΔ14EX strengthens the interaction between c-Met and SMAD2, promoting SMAD2 phosphorylation. Therapeutically, MET inhibitor crizotinib impedes METΔ14EX-mediated tumour metastasis by decreasing SMAD2 phosphorylation.

CONCLUSIONS

These data elucidated the previously unrecognised role of METΔ14EX in cancer progression via activation of SMAD2 independent of TGF-β, which helps to develop more effective therapies for such patients. METΔ14EX alteration significantly triggers tumour progression via activation of SMAD2 signalling that are involved in activating tumour invasion, metastasis and recurrence. On the left, in the MET wild-type (METWT), the juxtamembrane (JM) domain is involved in the regulation of tyrosine kinase activity, receptor degradation, and caspase cleavage. On the right, the METΔ14EX mutation leads to the loss of the juxtamembrane domain, resulting in an abnormal MET protein lacking a CBL-binding site. This causes the accumulation of truncated MET receptors followed by constitutive activation of the MET signalling pathway. Thus, the METΔ14EX-mutated protein has strong binding and phosphorylation to SMAD2, which results in the phosphorylation of a large number of SMAD2/3 proteins that combine with SMAD4 to form a complex in the nucleus, activating downstream signalling pathways, such as EMT and ECM remodelling, resulting in tumour progression and recurrence. TF transcription factor.

The human adenovirus E1B-55K oncoprotein coordinates cell transformation through regulation of DNA-bound host transcription factors

The multifunctional adenovirus E1B-55K oncoprotein can induce cell transformation in conjunction with adenovirus E1A gene products. Previous data from transient expression studies and in vitro experiments suggest that these growth-promoting activities correlate with E1B-55K-mediated transcriptional repression of p53-targeted genes. Here, we analyzed genome-wide occupancies and transcriptional consequences of species C5 and A12 E1B-55Ks in transformed mammalian cells by combinatory ChIP and RNA-seq analyses. E1B-55K-mediated repression correlates with tethering of the viral oncoprotein to p53-dependent promoters via DNA-bound p53. Moreover, we found that E1B-55K also interacts with and represses transcription of numerous p53-independent genes through interactions with transcription factors that play central roles in cancer and stress signaling. Our results demonstrate that E1B-55K oncoproteins function as promiscuous transcriptional repressors of both p53-dependent and -independent genes and further support the model that manipulation of cellular transcription is central to adenovirus-induced cell transformation and oncogenesis.

Integrative analysis reveals early epigenetic alterations in high-grade serous ovarian carcinomas

High-grade serous ovarian carcinoma (HGSOC) is the most lethal gynecological malignancy. To date, the profiles of gene mutations and copy number alterations in HGSOC have been well characterized. However, the patterns of epigenetic alterations and transcription factor dysregulation in HGSOC have not yet been fully elucidated. In this study, we performed integrative omics analyses of a series of stepwise HGSOC model cells originating from human fallopian tube secretory epithelial cells (HFTSECs) to investigate early epigenetic alterations in HGSOC tumorigenesis. Assay for transposase-accessible chromatin using sequencing (ATAC-seq), chromatin immunoprecipitation sequencing (ChIP-seq), and RNA sequencing (RNA-seq) methods were used to analyze HGSOC samples. Additionally, protein expression changes in target genes were confirmed using normal HFTSECs, serous tubal intraepithelial carcinomas (STICs), and HGSOC tissues. Transcription factor motif analysis revealed that the DNA-binding activity of the AP-1 complex and GATA family proteins was dysregulated during early tumorigenesis. The protein expression levels of JUN and FOSL2 were increased, and those of GATA6 and DAB2 were decreased in STIC lesions, which were associated with epithelial-mesenchymal transition (EMT) and proteasome downregulation. The genomic region around the FRA16D site, containing a cadherin cluster region, was epigenetically suppressed by oncogenic signaling. Proteasome inhibition caused the upregulation of chemokine genes, which may facilitate immune evasion during HGSOC tumorigenesis. Importantly, MEK inhibitor treatment reversed these oncogenic alterations, indicating its clinical effectiveness in a subgroup of patients with HGSOC. This result suggests that MEK inhibitor therapy may be an effective treatment option for chemotherapy-resistant HGSOC.

Overexpression of FRA1 (FOSL1) Leads to Global Transcriptional Perturbations, Reduced Cellular Adhesion and Altered Cell Cycle Progression

FRA1 (FOSL1) is a transcription factor and a member of the activator protein-1 superfamily. FRA1 is expressed in most tissues at low levels, and its expression is robustly induced in response to extracellular signals, leading to downstream cellular processes. However, abnormal FRA1 overexpression has been reported in various pathological states, including tumor progression and inflammation. To date, the molecular effects of FRA1 overexpression are still not understood. Therefore, the aim of this study was to investigate the transcriptional and functional effects of FRA1 overexpression using the CGL1 human hybrid cell line. FRA1-overexpressing CGL1 cells were generated using stably integrated CRISPR-mediated transcriptional activation, resulting in a 2-3 fold increase in FRA1 mRNA and protein levels. RNA-sequencing identified 298 differentially expressed genes with FRA1 overexpression. Gene ontology analysis showed numerous molecular networks enriched with FRA1 overexpression, including transcription-factor binding, regulation of the extracellular matrix and adhesion, and a variety of signaling processes, including protein kinase activity and chemokine signaling. In addition, cell functional assays demonstrated reduced cell adherence to fibronectin and collagen with FRA1 overexpression and altered cell cycle progression. Taken together, this study unravels the transcriptional response mediated by FRA1 overexpression and establishes the role of FRA1 in adhesion and cell cycle progression.

Epithelial-Mesenchymal Plasticity and Endothelial-Mesenchymal Transition in Cutaneous Wound Healing

Epithelial and endothelial cells possess the inherent plasticity to undergo morphological, cellular, and molecular changes leading to their resemblance of mesenchymal cells. A prevailing notion has been that cutaneous wound reepithelialization involves partial epithelial-to-mesenchymal transition (EMT) of wound-edge epidermal cells to enable their transition from a stationary state to a migratory state. In this review, we reflect on past findings that led to this notion and discuss recent studies that suggest a refined view, focusing predominantly on in vivo results using mammalian excisional wound models. We highlight the concept of epithelial-mesenchymal plasticity (EMP), which emphasizes a reversible conversion of epithelial cells across multiple intermediate states within the epithelial-mesenchymal spectrum, and discuss the critical importance of restricting EMT for effective wound reepithelialization. We also outline the current state of knowledge on EMP in pathological wound healing, and on endothelial-to-mesenchymal transition (EndMT), a process similar to EMT, as a possible mechanism contributing to wound fibrosis and scar formation. Harnessing epithelial/endothelial-mesenchymal plasticity may unravel opportunities for developing new therapeutics to treat human wound healing pathologies.

Multiple Fra-1-bound enhancers showing different molecular and functional features can cooperate to repress gene transcription

BACKGROUND

How transcription factors (TFs) down-regulate gene expression remains ill-understood, especially when they bind to multiple enhancers contacting the same gene promoter. In particular, it is not known whether they exert similar or significantly different molecular effects at these enhancers.

RESULTS

To address this issue, we used a particularly well-suited study model consisting of the down-regulation of the TGFB2 gene by the TF Fra-1 in Fra-1-overexpressing cancer cells, as Fra-1 binds to multiple enhancers interacting with the TGFB2 promoter. We show that Fra-1 does not repress TGFB2 transcription via reducing RNA Pol II recruitment at the gene promoter but by decreasing the formation of its transcription-initiating form. This is associated with complex long-range chromatin interactions implicating multiple molecularly and functionally heterogeneous Fra-1-bound transcriptional enhancers distal to the TGFB2 transcriptional start site. In particular, the latter display differential requirements upon the presence and the activity of the lysine acetyltransferase p300/CBP. Furthermore, the final transcriptional output of the TGFB2 gene seems to depend on a balance between the positive and negative effects of Fra-1 at these enhancers.

CONCLUSION

Our work unveils complex molecular mechanisms underlying the repressive actions of Fra-1 on TGFB2 gene expression. This has consequences for our general understanding of the functioning of the ubiquitous transcriptional complex AP-1, of which Fra-1 is the most documented component for prooncogenic activities. In addition, it raises the general question of the heterogeneity of the molecular functions of TFs binding to different enhancers regulating the same gene.

Antibody-drug conjugates (ADCs) targeting TROP-2 in lung cancer

INTRODUCTION

The advent of antibody-drug conjugates (ADCs) represents a renewed strategy in the era of precision oncology. Several epithelial tumors harbor overexpression of the trophoblast cell-surface antigen 2 (TROP-2), which represents a predictor of poor prognosis and a promising target for anticancer therapy.

AREAS COVERED

In this review, we aim to collect the available preclinical and clinical data regarding anti-TROP-2 ADCs in lung cancer obtained through extensive literature research and screening of the available abstract/posters presented at recent meetings.

EXPERT OPINION

Anti-TROP-2 ADCs represent an innovative upcoming weapon against both non-small cell lung cancer and small cell lung cancer subtypes, pending the results of several ongoing trials. The proper combination and placement of this agent throughout the lung cancer treatment pathway, the identification of potentially predictive biomarkers of benefit, as well as the optimal management and impact of peculiar toxicity (i.e. interstitial lung disease) are the next questions to be answered.

Recent Advances in Transcription Factors Biomarkers and Targeted Therapies Focusing on Epithelial-Mesenchymal Transition

Transcription factors involve many proteins in the process of transactivating or transcribing (none-) encoded DNA to initiate and regulate downstream signals, such as RNA polymerase. Their unique characteristic is that they possess specific domains that bind to specific DNA element sequences called enhancer or promoter sequences. Epithelial-mesenchymal transition (EMT) is involved in cancer progression. Many dysregulated transcription factors-such as Myc, SNAIs, Twists, and ZEBs-are key drivers of tumor metastasis through EMT regulation. This review summarizes currently available evidence related to the oncogenic role of classified transcription factors in EMT editing and epigenetic regulation, clarifying the roles of the classified conserved transcription factor family involved in the EMT and how these factors could be used as therapeutic targets in future investigations.

The role of infected epithelial cells in Chlamydia-associated fibrosis

Ocular, genital, and anogenital infection by the obligate intracellular pathogen Chlamydia trachomatis have been consistently associated with scar-forming sequelae. In cases of chronic or repeated infection of the female genital tract, infection-associated fibrosis of the fallopian tubes can result in ectopic pregnancy or infertility. In light of this urgent concern to public health, the underlying mechanism of C. trachomatis-associated scarring is a topic of ongoing study. Fibrosis is understood to be an outcome of persistent injury and/or dysregulated wound healing, in which an aberrantly activated myofibroblast population mediates hypertrophic remodeling of the basement membrane via deposition of collagens and other components of the extracellular matrix, as well as induction of epithelial cell proliferation via growth factor signaling. Initial study of infection-associated immune cell recruitment and pro-inflammatory signaling have suggested the cellular paradigm of chlamydial pathogenesis, wherein inflammation-associated tissue damage and fibrosis are the indirect result of an immune response to the pathogen initiated by host epithelial cells. However, recent work has revealed more direct routes by which C. trachomatis may induce scarring, such as infection-associated induction of growth factor signaling and pro-fibrotic remodeling of the extracellular matrix. Additionally, C. trachomatis infection has been shown to induce an epithelial-to-mesenchymal transition in host epithelial cells, prompting transdifferentiation into a myofibroblast-like phenotype. In this review, we summarize the field's current understanding of Chlamydia-associated fibrosis, reviewing key new findings and identifying opportunities for further research.

FRA-1 as a Regulator of EMT and Metastasis in Breast Cancer

Among FOS-related components of the dimeric AP-1 transcription factor, the oncoprotein FRA-1 (encoded by FOSL1) is a key regulator of invasion and metastasis. The well-established FRA-1 pro-invasive activity in breast cancer, in which FOSL1 is overexpressed in the TNBC (Triple Negative Breast Cancer)/basal subtypes, correlates with the FRA-1-dependent transcriptional regulation of EMT (Epithelial-to-Mesenchymal Transition). After summarizing the major findings on FRA-1 in breast cancer invasiveness, we discuss the FRA-1 mechanistic links with EMT and cancer cell stemness, mediated by transcriptional and posttranscriptional interactions between FOSL1/FRA-1 and EMT-regulating transcription factors, miRNAs, RNA binding proteins and cytokines, along with other target genes involved in EMT. In addition to the FRA-1/AP-1 effects on the architecture of target promoters, we discuss the diagnostic and prognostic significance of the EMT-related FRA-1 transcriptome, along with therapeutic implications. Finally, we consider several novel perspectives regarding the less explored roles of FRA-1 in the tumor microenvironment and in control of the recently characterized hybrid EMT correlated with cancer cell plasticity, stemness, and metastatic potential. We will also examine the application of emerging technologies, such as single-cell analyses, along with animal models of TNBC and tumor-derived CTCs and PDXs (Circulating Tumor Cells and Patient-Derived Xenografts) for studying the FRA-1-mediated mechanisms in in vivo systems of EMT and metastasis.

The transcription factor Fosl1 preserves Klotho expression and protects from acute kidney injury

Increased expression of AP-1 transcription factor components has been reported in acute kidney injury (AKI). However, the role of specific components, such as Fosl1, in tubular cells or AKI is unknown. Upstream regulator analysis of murine nephrotoxic AKI transcriptomics identified AP-1 as highly upregulated. Among AP-1 canonical components, Fosl1 was found to be upregulated in two transcriptomics datasets from nephrotoxic murine AKI induced by folic acid or cisplatin and from proximal tubular cells exposed to TWEAK, a cytokine mediator of AKI. Fosl1 was minimally expressed in the kidneys of control uninjured mice. Increased Fosl1 protein was localized to proximal tubular cell nuclei in AKI. In human AKI, FOSL1 was found present in proximal tubular cells in kidney sections and in urine along with increased urinary FOSL1 mRNA. Selective Fosl1 deficiency in proximal tubular cells (Fosl1Δtub) increased the severity of murine cisplatin- or folate-induced AKI as characterized by lower kidney function, more severe kidney inflammation and Klotho downregulation. Indeed, elevated AP-1 activity was observed after cisplatin-induced AKI in Fosl1Δtub mice compared to wild-type mice. More severe Klotho downregulation preceded more severe kidney dysfunction. The Klotho promoter was enriched in Fosl1 binding sites and Fosl1 bound to the Klotho promoter in cisplatin-AKI. In cultured proximal tubular cells, Fosl1 targeting increased the proinflammatory response and downregulated Klotho. In vivo, recombinant Klotho administration protected Fosl1Δtub mice from cisplatin-AKI. Thus, increased proximal tubular Fosl1 expression during AKI is an adaptive response, preserves Klotho, and limits the severity of tubular cell injury and AKI.

Combating pancreatic cancer with ovarian cancer cells

With overall five-year survival rate less than 10%, pancreatic cancer (PC) represents the most lethal one in all human cancers. Given that the incidence of PC is still increasing and current cancer treatment strategies are often inefficacious, its therapy is still a huge challenge. Here, we first revealed ovarian serous carcinoma is mostly anti-correlated with pancreatic cancer in gene expression signatures. Based on this observation, we proposed that ovarian cancer cells could defend PC. To confirm this strategy, we first showed that ovarian cancer cell SKOV3 can significantly inhibit the proliferation of pancreatic cancer cell SW1990 when they were co-cultured. We further validated this strategy by an animal model of pancreatic cancer xenografts. The result showed that the injection of SKOV3 significantly inhibits pancreatic cancer xenografts. Moreover, we found that SKOV3 with transgenic African elephant TP53 gene further enhances the therapeutic effect. RNA-sequencing analysis revealed that the ovarian cancer cell treatment strikingly induced changes of genes being involved in pancreas function and phenotype (e.g. enhancing pancreas function, pancreas regeneration, and cell adhesion) but not immune and inflammation-related functions, suggesting that the proposed strategy is different from immunotherapy and could be a novel strategy for cancer treatment.

ABCA1-Mediated EMT Promotes Papillary Thyroid Cancer Malignancy through the ERK/Fra-1/ZEB1 Pathway

Papillary thyroid cancer (PTC) is the most prevalent histological type of thyroid cancer (TC) worldwide. Although tumor metastasis occurs in regional lymph nodes, distant metastasis (DM) may also occur. Radioactive iodine (RAI) therapy is an effective treatment for TC; however, resistance to RAI occurs in patients with DM. Therefore, in this study, we investigated the efficacy of DM-related biomarkers as therapeutic targets for PTC therapy. ABCA1 expression was higher in aggressive BCPAP cells than in other PTC cells in terms of migration and invasion capacity. The knockdown of ABCA1 substantially decreased the expression of the epithelial-mesenchymal transition (EMT) marker, N-cadherin, and EMT regulator (ZEB1), resulting in suppressed migration and invasion of BCPAP cells. ABCA1 knockdown also reduced ERK activity and Fra-1 expression, which correlated with the effects of an ERK inhibitor or siRNA-mediated inhibition of ERK or Fra-1 expression. Furthermore, ABCA1-knocked-down BCPAP cells suppressed cell migration and invasion by reducing Fra-1 recruitment to Zeb1 promoter; lung metastasis was not observed in mice injected with ABCA1-knocked-down cells. Overall, our findings suggest that ABCA1 regulates lung metastasis in TC cells.

IL11 signaling mediates piR-2158 suppression of cell stemness and angiogenesis in breast cancer

Emerging evidence has indicated the aberrant expression of PIWI-interacting RNAs (piRNAs) in human cancer cells to regulate tumor development and progression by governing cancer cell stemness. Herein, we identified downregulation of piR-2158 in human breast cancer tumors, especially in ALDH+ breast cancer stem cells (BCSCs) from patients and cell lines, which was further validated in two types of genetically engineered mouse models of breast cancer (MMTV-Wnt and MMTV-PyMT). Enforced overexpression of piR-2158 in basal-like or luminal subtypes of breast cancer cells suppressed cell proliferation, migration, epithelial-mesenchymal transition (EMT) and stemness in vitro. Administration of a dual mammary tumor-targeting piRNA delivery system in mice reduced tumor growth in vivo. RNA-seq, ChIP-seq and luciferase reporter assays demonstrated piR-2158 as a transcriptional repressor of IL11 by competing with AP-1 transcription factor subunit FOSL1 to bind the promoter of IL11. STAT3 signaling mediated piR-2158-IL11 regulation of cancer cell stemness and tumor growth. Moreover, by co-culturing of MDA-MB-231 and HUVECs in vitro and CD31 staining of tumor endothelial cells in vivo, we demonstrated inhibition of angiogenesis by piR-2158-IL11 in breast cancer. In conclusion, the current study not only reveals a novel mechanism through which piR-2158 inhibits mammary gland tumorigenesis via regulating cancer stem cells and tumor angiogenesis, but also provides a novel therapeutic strategy in treatment of breast cancer.

Post-Translational Modification of ZEB Family Members in Cancer Progression

Post-translational modification (PTM), the essential regulatory mechanisms of proteins, play essential roles in physiological and pathological processes. In addition, PTM functions in tumour development and progression. Zinc finger E-box binding homeobox (ZEB) family homeodomain transcription factors, such as ZEB1 and ZEB2, play a pivotal role in tumour progression and metastasis by induction epithelial-mesenchymal transition (EMT), with activation of stem cell traits, immune evasion and epigenetic reprogramming. However, the relationship between ZEB family members' post-translational modification (PTM) and tumourigenesis remains largely unknown. Therefore, we focussed on the PTM of ZEBs and potential therapeutic approaches in cancer progression. This review provides an overview of the diverse functions of ZEBs in cancer and the mechanisms and therapeutic implications that target ZEB family members' PTMs.

Epithelial-Mesenchymal Plasticity Induced by Discontinuous Exposure to TGFβ1 Promotes Tumour Growth

Simple Summary

In this manuscript, we used a non-genetically manipulated EMT/MET cell line model to demonstrate that epithelial mesenchymal plasticity occurring in normal cells generates co-existing phenotypically and functionally divergent cell subpopulations which result in fast growing tumours in vivo.

Abstract

Transitions between epithelial and mesenchymal cellular states (EMT/MET) contribute to cancer progression. We hypothesize that EMT followed by MET promotes cell population heterogeneity, favouring tumour growth. We developed an EMT model by on and off exposure of epithelial EpH4 cells (E-cells) to TGFβ1 that mimics phenotypic EMT (M-cells) and MET. We aimed at understanding whether phenotypic MET is accompanied by molecular and functional reversion back to epithelia by using RNA sequencing, immunofluorescence (IF), proliferation, wound healing, focus formation and mamosphere formation assays as well as cell xenografts in nude mice. Phenotypic reverted epithelial cells (RE-cells) obtained after MET induction presented epithelial morphologies and proliferation rates resembling E cells. However, the RE transcriptomic profile and IF staining of epithelial and mesenchymal markers revealed a uniquely heterogeneous mixture of cell subpopulations with a high self-renewal ability. RE cell heterogeneity was stably maintained for long periods after TGFβ1 removal both in vitro and in large tumours derived from the nude mice. Overall, we show that phenotypic reverted epithelial cells (RE cells) do not return to the molecular and functional epithelial state and present mesenchymal features related to aggressiveness and cellular heterogeneity that favour tumour growth in vivo. This work strengthens epithelial cell reprogramming and cellular heterogeneity fostered by inflammatory cues as a tumour growth-promoting factor in vivo.

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.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

Distinct cytosine modification profiles define epithelial-to-mesenchymal cell-state transitions

Background: Epithelial-to-mesenchymal transition (EMT) is an early step in the invasion-metastasis cascade, involving progression through intermediate cell states. Due to challenges with isolating intermediate cell states, genome-wide cytosine modifications that define transition are not completely understood. Methods: The authors measured multiple DNA cytosine modification marks and chromatin accessibility across clonal populations residing in specific EMT states. Results: Clones exhibiting more intermediate EMT phenotypes demonstrated increased 5-hydroxymethylcytosine and decreased 5-methylcytosine. Open chromatin regions containing increased 5-hydroxymethylcytosine CpG loci were enriched in EMT transcription factor motifs and were associated with Rho GTPases. Conclusion: The results indicate the importance of both distinct and shared epigenetic profiles associated with EMT processes that may be targeted to prevent EMT progression.

The role of epigenetic modifications in Colorectal Cancer Metastasis

Distant metastasis is the major contributor to the high mortality rate of colorectal cancer (CRC). To overcome the poor prognosis caused by distant metastasis, the mechanisms of CRC metastasis should be further explored. Epigenetic events are the main mediators of gene regulation and further affect tumor progression. Recent studies have found that some epigenetic enzymes are often dysregulated or mutated in multiple tumor types, which prompted us to study the roles of these enzymes in CRC metastasis. In this review, we summarized the alteration of enzymes related to various modifications, including histone modification, nonhistone modification, DNA methylation, and RNA methylation, and their epigenetic mechanisms during the progression of CRC metastasis. Existing data suggest that targeting epigenetic enzymes is a promising strategy for the treatment of CRC metastasis.

Chlamydia pneumoniae Infection Induces Vascular Smooth Muscle Cell Migration and Atherosclerosis Through Mitochondrial Reactive Oxygen Species-Mediated JunB-Fra-1 Activation

Infection is closely related to atherosclerosis, which is a major pathological basis for cardiovascular diseases. Vascular smooth muscle cell (VSMC) migration is an important trigger in development of atherosclerosis that is associated with Chlamydia pneumoniae (C. pneumoniae) infection. However, the mechanism of VSMC migration remains unclear, and whether antioxidant could be a therapeutic target for C. pneumoniae infection-induced atherosclerosis also remains unknown. The results showed that C. pneumoniae infection mainly impaired mitochondrial function and increased the level of mitochondrial reactive oxygen species (mtROS). The expressions of protein JunB, Fra-1 and Matrix metalloproteinase 2 (MMP) evidently increased after C. pneumoniae infection, and the interaction between JunB and Fra-1 was also enhanced. After scavenging mtROS by antioxidant Mito-TEMPO, the increasing expressions of JunB, Fra-1, MMP2 and the capacity of VSMC migration induced by C. pneumoniae infection were all inhibited. In comparison with infected ApoE^-/- mice, the level of ROS in atherosclerotic lesion in ApoE^-/-TLR2^-/- mice with C. pneumoniae infection decreased. Knocking out TLR2 suppressed the expressions of JunB, Fra-1 and MMP2 in VSMCs and the formation of atherosclerotic lesion after C. pneumoniae infection. Furthermore, after using small interfering RNA to inhibit the expression of TLR2, the level of mtROS and the expressions of JunB, Fra-1 and MMP2 apparently decreased. Taken together, C. pneumoniae infection may promote VSMC migration and atherosclerosis development by increasing the level of mtROS through TLR2 to activate the JunB-Fra-1/MMP2 signaling pathway. The data provide the first evidence that antioxidant could reduce C. pneumoniae infection-induced VSMC migration and atherosclerosis.

Epigenetic alterations at distal enhancers are linked to proliferation in human breast cancer

Aberrant DNA methylation is an early event in breast carcinogenesis and plays a critical role in regulating gene expression. Here, we perform genome-wide expression-methylation Quantitative Trait Loci (emQTL) analysis through the integration of DNA methylation and gene expression to identify disease-driving pathways under epigenetic control. By grouping the emQTLs using biclustering we identify associations representing important biological processes associated with breast cancer pathogenesis including regulation of proliferation and tumor-infiltrating fibroblasts. We report genome-wide loss of enhancer methylation at binding sites of proliferation-driving transcription factors including CEBP-β, FOSL1, and FOSL2 with concomitant high expression of proliferation-related genes in aggressive breast tumors as we confirm with scRNA-seq. The identified emQTL-CpGs and genes were found connected through chromatin loops, indicating that proliferation in breast tumors is under epigenetic regulation by DNA methylation. Interestingly, the associations between enhancer methylation and proliferation-related gene expression were also observed within known subtypes of breast cancer, suggesting a common role of epigenetic regulation of proliferation. Taken together, we show that proliferation in breast cancer is linked to loss of methylation at specific enhancers and transcription factor binding and gene activation through chromatin looping.

Melatonin Inhibits EMT and PD-L1 Expression through the ERK1/2/FOSL1 Pathway and Regulates Anti-Tumor Immunity in HNSCC

Melatonin is an endogenous hormone with various biological functions and possesses anti-tumor properties in multiple malignancies. Immune evasion is one of the most important hallmarks of head and neck squamous cell carcinoma (HNSCC) and is closely related to tumor progression. However, as an immune modulator under physiological conditions, the roles of melatonin in tumor immunity in HNSCC remains unclear. In this study, we found that the endogenous melatonin levels in HNSCC patients were lower than those in patients with benign tumors in head and neck. Importantly, lower melatonin levels were related to lymph node metastasis among HNSCC patients. Moreover, melatonin significantly suppressed programmed death-ligand 1 (PD-L1) expression and inhibited epithelial-mesenchymal transition (EMT) of HNSCC through the ERK1/2/FOSL1 pathway in vitro and vivo. In SCC7/C3H syngeneic mouse models, anti-programmed death-1 (PD-1) antibody combined with melatonin significantly inhibited tumor growth and modulated anti-tumor immunity by increasing CD8⁺ T cell infiltration and decreasing regulatory T cell (Treg) proportion in tumor microenvironment. Taken together, melatonin inhibited EMT and downregulated PD-L1 expression in HNSCC through the ERK1/2/FOSL1 pathway and exerted synergistic effects with anti-PD-1 antibody in vivo, which could provide promising strategies for HNSCC treatment.

The Fra-1/AP-1 Oncoprotein: From the "Undruggable" Transcription Factor to Therapeutic Targeting

The genetic and epigenetic changes affecting transcription factors, coactivators, and chromatin modifiers are key determinants of the hallmarks of cancer. The acquired dependence on oncogenic transcriptional regulators, representing a major determinant of cancer cell vulnerability, points to transcription factors as ideal therapeutic targets. However, given the unavailability of catalytic activities or binding pockets for small-molecule inhibitors, transcription factors are generally regarded as undruggable proteins. Among components of the AP-1 complex, the FOS-family transcription factor Fra-1, encoded by FOSL1, has emerged as a prominent therapeutic target. Fra-1 is overexpressed in most solid tumors, in response to the BRAF-MAPK, Wnt-beta-catenin, Hippo-YAP, IL-6-Stat3, and other major oncogenic pathways. In vitro functional analyses, validated in onco-mouse models and corroborated by prognostic correlations, show that Fra-1-containing dimers control tumor growth and disease progression. Fra-1 participates in key mechanisms of cancer cell invasion, Epithelial-to-Mesenchymal Transition, and metastatic spreading, by driving the expression of EMT-inducing transcription factors, cytokines, and microRNAs. Here we survey various strategies aimed at inhibiting tumor growth, metastatic dissemination, and drug resistance by interfering with Fra-1 expression, stability, and transcriptional activity. We summarize several tools aimed at the design and tumor-specific delivery of Fra-1/AP-1-specific drugs. Along with RNA-based therapeutics targeting the FOSL1 gene, its mRNA, or cognate regulatory circRNAs, we will examine the exploitation of blocking peptides, small molecule inhibitors, and innovative Fra-1 protein degraders. We also consider the possible caveats concerning Fra-1 inhibition in specific therapeutic contexts. Finally, we discuss a recent suicide gene therapy-based approach, aimed at selectively killing the Fra-1-overexpressing neoplastic cells.

Long non-coding RNA FAM83A antisense RNA 1 (lncRNA FAM83A-AS1) targets microRNA-141-3p to regulate lung adenocarcinoma cell proliferation, migration, invasion, and epithelial-mesenchymal transition progression

The current paper investigates how long non-coding RNA (lncRNA) FAM83A antisense RNA 1 (lncRNA FAM83A-AS1) affected the epithelial-mesenchymal transformation (EMT), growth, invasion and migration of lung adenocarcinoma (LUAD) via targeting miRNA-141-3p. The GEPIA and ENCORI databases were used to analyze differences in lncRNA FAM83A-AS1 levels within LUAD samples. FAM83A-AS1 and miR-141-3p levels were assessed using qRT-PCR among 30 LUAD samples and surrounding normal tissues. In addition, we analyzed how FAM83A-AS1 affected proliferation, invasion, migration, and EMT processes of LUAD cells by targeting miR-141-3p through EdU, CCK-8 assay, scratch assay, transwell migration and invasion assay, immunofluorescence (IF) staining and WB assay. MicroRNAs targeting FAM83A-AS1 were screened using AnnoLnc2 and identified by RT-qPCR. Dual-luciferase assays were utilized to evaluate the connection between FAM83A-AS1 and miR-141-3p. FAM83A-AS1 expression was remarkably raised in lung cancer cells and tissue samples; however, miR-141-3p level markedly reduced relative to healthy samples. FAM83A-AS1 silencing suppressed EMT, growth, invasion and migration of LUAD cells. MiR-141-3p was the possible FAM83A-AS1 binding target negatively associated with FAM83A-AS1. The miR-141-3p inhibitor partly abolished the FAM83A-AS1 knockdown-induced inhibition on EMT, cell growth, invasion and migration in LUAD cells. In addition, miR-141-3p down-regulation abolished the inhibition of E-box-bound zinc finger protein 1 and 2 protein production following FAM83A-AS1 knockdown. According to our results, FAM83A-AS1/miR-141-3p axis plays an important role in LUAD occurrence and development. FAM83A-AS1 sponged miR-141-3p to down-regulate the level of the latter within LUAD and thereby encouraging LUAD development and suggesting a possible novel therapeutic approach for LUAD.

NRG1 regulates Fra-1 transcription and metastasis of triple-negative breast cancer cells via the c-Myc ubiquitination as manipulated by ERK1/2-mediated Fbxw7 phosphorylation

Neuregulin 1 (NRG1), an EGF family member, is expressed in most breast cancers. It promotes breast cancer growth and metastasis in HER2 receptor expressing breast cancer. However, its role in triple-negative breast cancer (TNBC) has not been extensively investigated. In this study, we observed that NRG1 knockdown resulted in the suppression of TNBC cells (MDA-MB-231 cell and MDA-MB-468 cell) metastasis and downregulation of Fra-1 (FOS-like 1, AP-1 transcription factor subunit, which is an overexpressed transcription factor in TNBC and acts as a coordinator of metastasis). In addition, the transcriptional regulation of Fra-1 by NRG1 was mediated by ERK1/2-induced recruitment of c-Myc (MYC proto-oncogene, transcription factor) to the promoter of Fra-1. Furthermore, c-Myc was targeted by an E3 ligase Fbxw7 and its ubiquitination and degradation by Fbxw7 was regulated by NRG1 expression and ERK1/2-mediated Fbxw7 phosphorylation that results in the dissociation and nuclear import of c-Myc. Taken together, the results of our study demonstrated that NRG1 regulates the Fra-1 expression to coordinate the TNBC metastasis via the novel ERK1/2-Fbxw7-c-Myc pathway and targeting NRG1 expression could be a potential therapeutic strategy for TNBC.

Role of the Transcription Factor FOSL1 in Organ Development and Tumorigenesis

The transcription factor FOSL1 plays an important role in cell differentiation and tumorigenesis. Primarily, FOSL1 is crucial for the differentiation of several cell lineages, namely adipocytes, chondrocytes, and osteoblasts. In solid tumors, FOSL1 controls the progression of tumor cells through the epithelial-mesenchymal transformation. In this review, we summarize the available data on FOSL1 expression, stabilization, and degradation in the cell. We discuss how FOSL1 is integrated into the intracellular signaling mechanisms and provide a comprehensive analysis of FOSL1 influence on gene expression. We also analyze the pathological changes caused by altered Fosl1 expression in genetically modified mice. In addition, we dedicated a separate section of the review to the role of FOSL1 in human cancer. Primarily, we focus on the FOSL1 expression pattern in solid tumors, FOSL1 importance as a prognostic factor, and FOSL1 perspectives as a molecular target for anticancer therapy.

A dual role of human tRNA methyltransferase hTrmt13 in regulating translation and transcription

Since numerous RNAs and RBPs prevalently localize to active chromatin regions, many RNA-binding proteins (RBPs) may be potential transcriptional regulators. RBPs are generally thought to regulate transcription via noncoding RNAs. Here, we describe a distinct, dual mechanism of transcriptional regulation by the previously uncharacterized tRNA-modifying enzyme, hTrmt13. On one hand, hTrmt13 acts in the cytoplasm to catalyze 2'-O-methylation of tRNAs, thus regulating translation in a manner depending on its tRNA-modification activity. On the other hand, nucleus-localized hTrmt13 directly binds DNA as a transcriptional co-activator of key epithelial-mesenchymal transition factors, thereby promoting cell migration independent of tRNA-modification activity. These dual functions of hTrmt13 are mutually exclusive, as it can bind either DNA or tRNA through its CHHC zinc finger domain. Finally, we find that hTrmt13 expression is tightly associated with poor prognosis and survival in diverse cancer patients. Our discovery of the noncatalytic roles of an RNA-modifying enzyme provides a new perspective for understanding epitranscriptomic regulation.

Epithelial Mesenchymal Transition and its transcription factors

Epithelial–mesenchymal transition or EMT is an extremely dynamic process involved in conversion of epithelial cells into mesenchymal cells, stimulated by an ensemble of signaling pathways, leading to change in cellular morphology, suppression of epithelial characters and acquisition of properties such as enhanced cell motility and invasiveness, reduced cell death by apoptosis, resistance to chemotherapeutic drugs etc. Significantly, EMT has been found to play a crucial role during embryonic development, tissue fibrosis and would healing, as well as during cancer metastasis. Over the years, work from various laboratories have identified a rather large number of transcription factors (TFs) including the master regulators of EMT, with the ability to regulate the EMT process directly. In this review, we put together these EMT TFs and discussed their role in the process. We have also tried to focus on their mechanism of action, their interdependency, and the large regulatory network they form. Subsequently, it has become clear that the composition and structure of the transcriptional regulatory network behind EMT probably varies based upon various physiological and pathological contexts, or even in a cell/tissue type-dependent manner.

Recent advances in trophoblast cell-surface antigen 2 targeted therapy for solid tumors

Trophoblast cell-surface antigen 2 (Trop 2) is a transmembrane glycoprotein that is highly expressed in various cancer types with relatively low or no baseline expression in most normal tissues. Its overexpression is associated with tumor growth and poor prognosis; Trop 2 is, therefore, an ideal therapeutic target for epithelial cancers. Several Trop 2 targeted therapeutics have recently been developed for the treatment of cancers, such as anti-Trop 2 antibodies and antibody-drug conjugates (ADCs), as well as Trop 2-specific cell therapy. In particular, the safety and clinical benefit of Trop 2-based ADCs have been demonstrated in clinical trials across multiple tumor types, including those with limited treatment options, such as triple-negative breast cancer, platinum-resistant urothelial cancer, and heavily pretreated non-small cell lung cancer. In this review, we elaborate on recent advances in Trop 2 targeted modalities and provide an overview of novel insights for future developments in this field.

NF1 regulates mesenchymal glioblastoma plasticity and aggressiveness through the AP-1 transcription factor FOSL1

The molecular basis underlying glioblastoma (GBM) heterogeneity and plasticity is not fully understood. Using transcriptomic data of human patient-derived brain tumor stem cell lines (BTSCs), classified based on GBM-intrinsic signatures, we identify the AP-1 transcription factor FOSL1 as a key regulator of the mesenchymal (MES) subtype. We provide a mechanistic basis to the role of the neurofibromatosis type 1 gene (NF1), a negative regulator of the RAS/MAPK pathway, in GBM mesenchymal transformation through the modulation of FOSL1 expression. Depletion of FOSL1 in NF1-mutant human BTSCs and Kras-mutant mouse neural stem cells results in loss of the mesenchymal gene signature and reduction in stem cell properties and in vivo tumorigenic potential. Our data demonstrate that FOSL1 controls GBM plasticity and aggressiveness in response to NF1 alterations.

ZEB2, the Mowat-Wilson Syndrome Transcription Factor: Confirmations, Novel Functions, and Continuing Surprises

After its publication in 1999 as a DNA-binding and SMAD-binding transcription factor (TF) that co-determines cell fate in amphibian embryos, ZEB2 was from 2003 studied by embryologists mainly by documenting the consequences of conditional, cell-type specific Zeb2 knockout (cKO) in mice. In between, it was further identified as causal gene causing Mowat-Wilson Syndrome (MOWS) and novel regulator of epithelial-mesenchymal transition (EMT). ZEB2's functions and action mechanisms in mouse embryos were first addressed in its main sites of expression, with focus on those that helped to explain neurodevelopmental and neural crest defects seen in MOWS patients. By doing so, ZEB2 was identified in the forebrain as the first TF that determined timing of neuro-/gliogenesis, and thereby also the extent of different layers of the cortex, in a cell non-autonomous fashion, i.e., by its cell-intrinsic control within neurons of neuron-to-progenitor paracrine signaling. Transcriptomics-based phenotyping of Zeb2 mutant mouse cells have identified large sets of intact-ZEB2 dependent genes, and the cKO approaches also moved to post-natal brain development and diverse other systems in adult mice, including hematopoiesis and various cell types of the immune system. These new studies start to highlight the important adult roles of ZEB2 in cell-cell communication, including after challenge, e.g., in the infarcted heart and fibrotic liver. Such studies may further evolve towards those documenting the roles of ZEB2 in cell-based repair of injured tissue and organs, downstream of actions of diverse growth factors, which recapitulate developmental signaling principles in the injured sites. Evident questions are about ZEB2's direct target genes, its various partners, and ZEB2 as a candidate modifier gene, e.g., in other (neuro)developmental disorders, but also the accurate transcriptional and epigenetic regulation of its mRNA expression sites and levels. Other questions start to address ZEB2's function as a niche-controlling regulatory TF of also other cell types, in part by its modulation of growth factor responses (e.g., TGFβ/BMP, Wnt, Notch). Furthermore, growing numbers of mapped missense as well as protein non-coding mutations in MOWS patients are becoming available and inspire the design of new animal model and pluripotent stem cell-based systems. This review attempts to summarize in detail, albeit without discussing ZEB2's role in cancer, hematopoiesis, and its emerging roles in the immune system, how intense ZEB2 research has arrived at this exciting intersection.

Constitutive activation of MEK5 promotes a mesenchymal and migratory cell phenotype in triple negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited targeted therapeutic options. A defining feature of TNBC is the propensity to metastasize and acquire resistance to cytotoxic agents. Mitogen activated protein kinase (MAPK) and extracellular regulated kinase (ERK) signaling pathways have integral roles in cancer development and progression. While MEK5/ERK5 signaling drives mesenchymal and migratory cell phenotypes in breast cancer, the specific mechanisms underlying these actions remain under-characterized. To elucidate the mechanisms through which MEK5 regulates the mesenchymal and migratory phenotype, we generated stably transfected constitutively active MEK5 (MEK5-ca) TNBC cells. Downstream signaling pathways and candidate targets of MEK5-ca cells were based on RNA sequencing and confirmed using qPCR and Western blot analyses. MEK5 activation drove a mesenchymal cell phenotype independent of cell proliferation effects. Transwell migration assays demonstrated MEK5 activation significantly increased breast cancer cell migration. In this study, we provide supporting evidence that MEK5 functions through FRA-1 to regulate the mesenchymal and migratory phenotype in TNBC.

Identification of EMT signaling cross-talk and gene regulatory networks by single-cell RNA sequencing

The epithelial-to-mesenchymal transition (EMT) plays a critical role during normal development and in cancer progression. EMT is induced by various signaling pathways, including TGF-β, BMP, Wnt-β-catenin, NOTCH, Shh, and receptor tyrosine kinases. In this study, we performed single-cell RNA sequencing on MCF10A cells undergoing EMT by TGF-β1 stimulation. Our comprehensive analysis revealed that cells progress through EMT at different paces. Using pseudotime clustering reconstruction of gene-expression profiles during EMT, we found sequential and parallel activation of EMT signaling pathways. We also observed various transitional cellular states during EMT. We identified regulatory signaling nodes that drive EMT with the expression of important microRNAs and transcription factors. Using a random circuit perturbation methodology, we demonstrate that the NOTCH signaling pathway acts as a key driver of TGF-β-induced EMT. Furthermore, we demonstrate that the gene signatures of pseudotime clusters corresponding to the intermediate hybrid EMT state are associated with poor patient outcome. Overall, this study provides insight into context-specific drivers of cancer progression and highlights the complexities of the EMT process.

Genome-wide Screens Implicate Loss of Cullin Ring Ligase 3 in Persistent Proliferation and Genome Instability in TP53-Deficient Cells

TP53 deficiency is the most common alteration in cancer; however, this alone is typically insufficient to drive tumorigenesis. To identify genes promoting tumorigenesis in combination with TP53 deficiency, we perform genome-wide CRISPR-Cas9 knockout screens coupled with proliferation and transformation assays in isogenic cell lines. Loss of several known tumor suppressors enhances cellular proliferation and transformation. Loss of neddylation pathway genes promotes uncontrolled proliferation exclusively in TP53-deficient cells. Combined loss of CUL3 and TP53 activates an oncogenic transcriptional program governed by the nuclear factor κB (NF-κB), AP-1, and transforming growth factor β (TGF-β) pathways. This program maintains persistent cellular proliferation, induces partial epithelial to mesenchymal transition, and increases DNA damage, genomic instability, and chromosomal rearrangements. Our findings reveal CUL3 loss as a key event stimulating persistent proliferation in TP53-deficient cells. These findings may be clinically relevant, since TP53-CUL3-deficient cells are highly sensitive to ataxia telangiectasia mutated (ATM) inhibition, exposing a vulnerability that could be exploited for cancer treatment.

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Mixed-effect models with MEMcrispR applied to CRISPR screen analyses

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Knockout of neddylation genes increases persistent proliferation in TP53^−/− cells

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TP53^−/−,CUL3^−/− cells exhibit persistent proliferation and partial EMT phenotype

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TP53^−/−,CUL3^−/− cells show increased DNA damage and display sensitivity to ATM inhibition

So alike yet so different. Differential expression of the long non-coding RNAs NORAD and HCG11 in breast cancer subtypes

Breast cancer (BC) is a heterogeneous disease, and it is the leading cause of death among women. NORAD and HCG11 are highly similar lncRNAs that present binding sites for PUMILIO proteins. PUMILIO acts on hundreds of mRNA targets, contributing to the modulation of gene expression. We analyzed the expression levels of NORAD and HCG11 in the BC subtypes luminal A (LA) and basal-like (BL), and the regulatory networks associated with these lncRNAs. In the analysis of TCGA cohort (n=329) and Brazilian BC samples (n=44), NORAD was up-regulated in LA while HCG11 was up-regulated in BL subtype. An increased expression of NORAD is associated with reduced disease-free survival in basal-like patients (p = 0.002), which suggests that its prognostic value could be different in specific subtypes. The biological pathways observed for the HCG11 network are linked to the epithelial-to-mesenchymal transition; while NORAD associated pathways appear to be related to luminal epithelial cell transformation. NORAD and HCG11 regulons respectively present 36% and 21.5% of PUMILIO targets, which suggests that these lncRNAs act as a decoy for PUMILIO. These lncRNAs seem to work as players in the differentiation process that drives breast cells to acquire distinct phenotypes related to a specific BC subtype.

Fra-1 regulates its target genes via binding to remote enhancers without exerting major control on chromatin architecture in triple negative breast cancers

The ubiquitous family of dimeric transcription factors AP-1 is made up of Fos and Jun family proteins. It has long been thought to operate principally at gene promoters and how it controls transcription is still ill-understood. The Fos family protein Fra-1 is overexpressed in triple negative breast cancers (TNBCs) where it contributes to tumor aggressiveness. To address its transcriptional actions in TNBCs, we combined transcriptomics, ChIP-seqs, machine learning and NG Capture-C. Additionally, we studied its Fos family kin Fra-2 also expressed in TNBCs, albeit much less. Consistently with their pleiotropic effects, Fra-1 and Fra-2 up- and downregulate individually, together or redundantly many genes associated with a wide range of biological processes. Target gene regulation is principally due to binding of Fra-1 and Fra-2 at regulatory elements located distantly from cognate promoters where Fra-1 modulates the recruitment of the transcriptional co-regulator p300/CBP and where differences in AP-1 variant motif recognition can underlie preferential Fra-1- or Fra-2 bindings. Our work also shows no major role for Fra-1 in chromatin architecture control at target gene loci, but suggests collaboration between Fra-1-bound and -unbound enhancers within chromatin hubs sometimes including promoters for other Fra-1-regulated genes. Our work impacts our view of AP-1.