FOXK transcription factors: Regulation and critical role in cancer

FOXK1 promotes hormonally responsive breast carcinogenesis by suppressing apoptosis

BACKGROUND

Globally, breast cancer constitutes the predominant malignancy in women. Abnormal regulation of epigenetic factors plays a key role in the development of tumors. Anti-apoptosis is a characteristic of tumor cells. Therefore, exploring and identifying relevant epigenetic factors that regulate the apoptosis of tumor cells is the foundation for clarifying the pathogenesis of tumors and achieving precision antitumor therapy.

METHOD

This study focused on exploring the epigenetic mechanism of FOXK1 in the development of estrogen receptor-positive (ER+) breast cancer. We used overexpressing FLAG-FOXK1 MCF-7 cells to perform silver staining mass spectrometry analysis and conducted Co-IP experiments to verify the interactions. ChIP-seq was conducted on MCF-7 cells to examine FOXK1's binding across the genome and its transcriptional target sites. To validate the ChIP-seq results, qChIP, western blotting, and quantitative polymerase chain reaction (qPCR) were performed. Through TUNEL assay, cell counting assay, colony formation assay, and the mouse xenograft models, the effect of FOXK1 on breast cancer progression was detected. Finally, by analyzing online databases, the correlation between FOXK1 and the survival of breast cancer patients was examined.

RESULTS

FOXK1 interacts with the REST/CoREST transcriptional corepression complex to transcriptionally inhibit target genes representing the apoptotic pathway. Abnormally high expression of FOXK1 prevents the apoptosis of ER+ breast cancer cells in vitro and promotes ER+ breast tumor progression in vivo. Furthermore, the expression of FOXK1 is negatively correlated with the survival of ER+ breast cancer patients.

CONCLUSION

FOXK1 promotes ER+ breast carcinogenesis through anti-apoptosis and acts as a potential target for ER+ breast cancer treatment.

Foxk1 and Foxk2 promote cardiomyocyte proliferation and heart regeneration

Promoting endogenous cardiomyocyte proliferation is a promising strategy for cardiac repair. Identifying key factors that regulate cardiomyocyte proliferation can advance the development of novel therapies for heart regeneration. Here, we identify Foxk1 and Foxk2 as key regulators of cardiomyocyte proliferation, whose expression declines during postnatal heart development. Cardiomyocyte-specific knockout of Foxk1 or Foxk2 impairs neonatal heart regeneration after myocardial infarction (MI) injury. AAV9-mediated Foxk1 or Foxk2 overexpression extends the postnatal cardiomyocyte proliferative window and enhances cardiac repair in adult mice after MI. Mechanistically, Foxk1 and Foxk2 drive cardiomyocyte cell cycle progression by directly activating CCNB1 and CDK1 expression, forming the CCNB1/CDK1 complex that facilitates G2/M transition. Moreover, Foxk1 and Foxk2 promote cardiomyocyte proliferation by upregulating HIF1α expression, which enhances glycolysis and the pentose phosphate pathway (PPP), which further favors cardiomyocyte proliferation. These findings establish Foxk1 and Foxk2 as promising therapeutic targets for cardiac injury.

The LncRNA lnc-POTEM-4:14 promotes HCC progression by interacting with FOXK1

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours of the digestive tract and poses a serious threat to human life. This study first analysed two GEO datasets (GSE166705 and GSE115018) to screen for differentially expressed lncRNAs between HCC and adjacent tissues. The lncRNA lnc-POTEM-4:14 was determined via a series of methods to be closely related to liver cancer. Further research was subsequently performed to investigate the role of the lncRNA lnc-POTEM-4:14 in the progression of HCC. The lncRNA lnc-POTEM-4:14 is localized primarily within the nucleus and is highly expressed in liver cancer tissues. We established lnc-POTEM-4:14 knockdown and overexpression cell lines to analyse the role of lnc-POTEM-4:14 in liver cancer through functional experiments such as qPCR and WB. We identified FOXK1 as an RNA-binding protein (RBP) of lnc-POTEM-4:14 that participates in MAPK signal activation and cell cycle progression by regulating the activation or expression levels of the downstream target protein TAB1 as a transcription factor. The restoration of FOXK1 can rescue the limited proliferation and increased apoptosis caused by lnc-POTEM-4:14 knockdown. Finally, we validated our hypothesis in a nude mouse tumour-bearing model. In conclusion, lnc-POTEM-4:14 affects the progression of HCC through the FOXK1/TAB1/NLK axis, suggesting that lnc-POTEM-4:14 has potential as a therapeutic target for treating this aggressive malignancy.

C15orf39, a downstream effector of PI3K/AKT signaling, promotes gastric carcinogenesis and correlates with patient outcomes

The phosphatidylinositol-3-kinases (PI3K) signaling pathway is highly complex and well-known to exert oncogenic roles in multiple cancer types. Exploring new factors involved in this pathway may offer the potential for improving the early diagnosis and treatment strategies for cancers. Here we used gastric cancer (GC) as a model to identify co-regulated effectors downstream of three catalytic subunits of PI3K through high-throughput sequencing in PIK3CA, PIK3CB, and PIK3CD knockdown GC cells. C15orf39, a new uncharacterized gene, was selected due to the most significant expression change. qRT-PCR and immunohistochemistry analyses revealed that C15orf39 was frequently upregulated in GC tissues and strongly correlated with poor clinical outcomes in GC patients. Gain- and loss-of-function studies demonstrated that C15orf39 promoted GC cell proliferation, migration, and drug resistance. Mechanistically, C15orf39 promoted GC progression possibly via modulating cell mitosis and cell cycle. FOXK2, a transcription factor activated by PI3K/AKT signaling, could bind to the promoter of C15orf39 and positively regulate C15orf39 expression. These findings unveiled a new PI3K/AKT/FOXK2/C15orf39 signaling axis that promotes GC development and progression. C15orf39 may become a potential biomarker for early diagnosis and personalized treatment to improve the prognosis of GC patients.

Systematic and comprehensive insights into HIF-1 stabilization under normoxic conditions: implications for cellular adaptation and therapeutic strategies in cancer

Hypoxia-inducible factors (HIFs) are essential transcription factors that orchestrate cellular responses to oxygen deprivation. HIF-1α, as an unstable subunit of HIF-1, is usually hydroxylated by prolyl hydroxylase domain enzymes under normoxic conditions, leading to ubiquitination and proteasomal degradation, thereby keeping low levels. Instead of hypoxia, sometimes even in normoxia, HIF-1α translocates into the nucleus, dimerizes with HIF-1β to generate HIF-1, and then activates genes involved in adaptive responses such as angiogenesis, metabolic reprogramming, and cellular survival, which presents new challenges and insights into its role in cellular processes. Thus, the review delves into the mechanisms by which HIF-1 maintains its stability under normoxia including but not limited to giving insights into transcriptional, translational, as well as posttranslational regulation to underscore the pivotal role of HIF-1 in cellular adaptation and malignancy. Moreover, HIF-1 is extensively involved in cancer and cardiovascular diseases and potentially serves as a bridge between them. An overview of HIF-1-related drugs that are approved or in clinical trials is summarized, highlighting their potential capacity for targeting HIF-1 in cancer and cardiovascular toxicity related to cancer treatment. The review provides a comprehensive insight into HIF-1's regulatory mechanism and paves the way for future research and therapeutic development.

FoxK1 and FoxK2 cooperate with ORF45 to promote late lytic replication of Kaposi's sarcoma-associated herpesvirus

Lytic replication is essential for persistent infection of Kaposi's sarcoma-associated herpesvirus (KSHV) and the pathogenesis of related diseases, and many cellular pathways are hijacked by KSHV proteins to initiate and control the lytic replication of this virus. However, the mechanism involved in KSHV lytic replication from the early to the late phases remains largely undetermined. We previously revealed that KSHV open reading frame 45 (ORF45) plays important roles in late transcription and translation. In the present study, we revealed that the Forkhead box proteins FoxK1 and FoxK2 are ORF45-binding proteins and are essential for KSHV lytic gene expression and virion production, and that depletion of FoxK1 or FoxK2 significantly suppresses the expression of many late viral genes. FoxK1 and FoxK2 directly bind to the promoters of several late viral genes, ORF45 augments the promoter binding and transcriptional activity of FoxK1 and FoxK2, and then FoxK1 or FoxK2 cooperates with ORF45 to promote late viral gene expression. Our findings suggest that ORF45 interacts with FoxK1 and FoxK2 and promotes their occupancy on a cluster of late viral promoters and their subsequent transcriptional activity; consequently, FoxK1 and FoxK2 promote late viral gene expression to facilitate KSHV lytic replication.IMPORTANCEThe forkhead box proteins FoxK1 and FoxK2 can act as transcriptional inhibitors or activators to regulate several important processes, including aerobic glycolysis, metabolism, autophagy, and antiviral responses. However, the subversion and functions of FoxK1 and FoxK2 during KSHV infection and the pathogenesis of related diseases remain unknown. Here, we revealed that ORF45 binds to FoxK1 and FoxK2 and increases their transcriptional activity during KSHV lytic replication; consequently, FoxK1 and FoxK2 bind to late viral promoters and cooperate with ORF45 to promote late lytic gene expression. Our findings reveal two new ORF45 partners and a new function of ORF45 in which it utilizes FoxK1 and FoxK2 to promote transcription during late KSHV lytic replication.

Foxk1 promotes bone formation through inducing aerobic glycolysis

Transcription factor Foxk1 can regulate cell proliferation, differentiation, metabolism, and promote skeletal muscle regeneration and cardiogenesis. However, the roles of Foxk1 in bone formation is unknown. Here, we found that Foxk1 expression decreased in the bone tissue of aged mice and osteoporosis patients. Knockdown of Foxk1 in primary murine calvarial osteoblasts suppressed osteoblast differentiation and proliferation. Conditional knockout of Foxk1 in preosteoblasts and mature osteoblasts in mice exhibited decreased bone mass and mechanical strength due to reduced bone formation. Mechanistically, we identified Foxk1 targeted the promoter region of many genes of glycolytic enzyme by CUT&Tag analysis. Lacking of Foxk1 in primary murine calvarial osteoblasts resulted in reducing aerobic glycolysis. Inhibition of glycolysis by 2DG hindered osteoblast differentiation and proliferation induced by Foxk1 overexpression. Finally, specific overexpression of Foxk1 in preosteoblasts, driven by a preosteoblast specific osterix promoter, increased bone mass and bone mechanical strength of aged mice, which could be suppressed by inhibiting glycolysis. In summary, these findings reveal that Foxk1 plays a vital role in the osteoblast metabolism regulation and bone formation stimulation, offering a promising approach for preventing age-related bone loss.

Forkhead Box Protein K1 Promotes Chronic Kidney Disease by Driving Glycolysis in Tubular Epithelial Cells

Renal tubular epithelial cells (TECs) undergo an energy-related metabolic shift from fatty acid oxidation to glycolysis during chronic kidney disease (CKD) progression. However, the mechanisms underlying this burst of glycolysis remain unclear. Herein, a new critical glycolysis regulator, the transcription factor forkhead box protein K1 (FOXK1) that is expressed in TECs during renal fibrosis and exhibits fibrogenic and metabolism-rewiring capacities is reported. Genetic modification of the Foxk1 locus in TECs alters glycolytic metabolism and fibrotic lesions. A surge in the expression of a set of glycolysis-related genes following FOXK1 protein activation contributes to the energy-related metabolic shift. Nuclear-translocated FOXK1 forms condensate through liquid-liquid phase separation (LLPS) to drive the transcription of target genes. Core intrinsically disordered regions within FOXK1 protein are mapped and validated. A therapeutic strategy is explored by targeting the Foxk1 locus in a murine model of CKD by the renal subcapsular injection of a recombinant adeno-associated virus 9 vector encoding Foxk1-short hairpin RNA. In summary, the mechanism of a FOXK1-mediated glycolytic burst in TECs, which involves the LLPS to enhance FOXK1 transcriptional activity is elucidated.

FOXK2 targeting by the SCF-E3 ligase subunit FBXO24 for ubiquitin mediated degradation modulates mitochondrial respiration

FOXK2 is a crucial transcription factor implicated in a wide array of biological activities and yet understanding of its molecular regulation at the level of protein turnover is limited. Here, we identify that FOXK2 undergoes degradation in lung epithelia in the presence of the virulent pathogens Pseudomonas aeruginosa and Klebsiella pneumoniae through ubiquitin-proteasomal processing. FOXK2 through its carboxyl terminus (aa 428-478) binds the Skp-Cullin-F-box ubiquitin E3 ligase subunit FBXO24 that mediates multisite polyubiquitylation of the transcription factor resulting in its nuclear degradation. FOXK2 was detected within the mitochondria and targeted depletion of the transcription factor or cellular expression of FOXK2 mutants devoid of key carboxy terminal domains significantly impaired mitochondrial function. In experimental bacterial pneumonia, Fbxo24 heterozygous mice exhibited preserved mitochondrial function and Foxk2 protein levels compared to WT littermates. The results suggest a new mode of regulatory control of mitochondrial energetics through modulation of FOXK2 cellular abundance.

Targeting O-GlcNAcylation in cancer therapeutic resistance: The sugar Saga continues

O-linked-N-acetylglucosaminylation (O-GlcNAcylation), a dynamic post-translational modification (PTM), holds profound implications in controlling various cellular processes such as cell signaling, metabolism, and epigenetic regulation that influence cancer progression and therapeutic resistance. From the therapeutic perspective, O-GlcNAc modulates drug efflux, targeting and metabolism. By integrating signals from glucose, lipid, amino acid, and nucleotide metabolic pathways, O-GlcNAc acts as a nutrient sensor and transmits signals to exerts its function on genome stability, epithelial-mesenchymal transition (EMT), cell stemness, cell apoptosis, autophagy, cell cycle. O-GlcNAc also attends to tumor microenvironment (TME) and the immune response. At present, several strategies aiming at targeting O-GlcNAcylation are under mostly preclinical evaluation, where the newly developed O-GlcNAcylation inhibitors markedly enhance therapeutic efficacy. Here we systematically outline the mechanisms through which O-GlcNAcylation influences therapy resistance and deliberate on the prospects and challenges associated with targeting O-GlcNAcylation in future cancer treatments.

Single-cell RNA sequencing reveals pro-invasive cancer-associated fibroblasts in hypopharyngeal squamous cell carcinoma

BACKGROUND

Hypopharyngeal squamous cell carcinoma (HPSCC) has the worst prognosis among all head-and-neck cancers, and treatment options are limited. Tumor microenvironment (TME) analysis can help identify new therapeutic targets and combined treatment strategies.

METHODS

Six primary HPSCC tissues and two adjacent normal mucosae from six treatment-naïve patients with HPSCC were analyzed using scRNA-seq. Cell types were curated in detail, ecosystemic landscapes were mapped, and cell-cell interactions were inferred. Key results were validated with The Cancer Genome Atlas and cell biology experiments.

RESULTS

Malignant HPSCC epithelial cells showed significant intratumor heterogeneity. Different subtypes exhibited distinct histological features, biological behaviors, and spatial localization, all affecting treatment selection and prognosis. Extracellular matrix cancer-associated fibroblasts (mCAFs) expressing fibroblast activation protein were the dominant CAFs in HPSCC tumors. mCAFs, constituting an aggressive CAF subset, promoted tumor cell invasion, activated endothelial cells to trigger angiogenesis, and synergized with SPP1+ tumor associated macrophages to induce tumor progression, ultimately decreasing the overall survival of patients with HPSCC. Moreover, the LAMP3+ dendritic cell subset was identified in HPSCC and formed an immunosuppressive TME by recruiting Tregs and suppressing CD8+ T cell function.

CONCLUSIONS

mCAFs, acting as the communication center of the HPSCC TME, enhance the invasion ability of HPSCC cells, mobilizing surrounding cells to construct a tumor-favorable microenvironment. Inhibiting mCAF activation offers a new anti-HPSCC therapeutic strategy. Video Abstract.

MicroRNAs as the Critical Regulators of Forkhead Box Protein Family in Pancreatic, Thyroid, and Liver Cancers

The metabolism of human body is mainly regulated by the pancreas, liver, and thyroid using the hormones or exocrine secretions that affect the metabolic processes from food digestion to intracellular metabolism. Therefore, metabolic organ disorders have wide clinical symptoms that severely affect the quality of patient's life. The pancreatic, liver, and thyroid cancers as the main malignancies of the metabolic system have always been considered as one of the serious health challenges worldwide. Despite the novel therapeutic modalities, there are still significant high mortality and recurrence rates, especially in liver and pancreatic cancer patients which are mainly related to the late diagnosis. Therefore, it is required to assess the molecular bases of tumor progressions to introduce novel early detection and therapeutic markers in these malignancies. Forkhead box (FOX) protein family is a group of transcription factors that have pivotal roles in regulation of cell proliferation, migration, and apoptosis. They function as oncogene or tumor suppressor during tumor progression. MicroRNAs (miRNAs) are also involved in regulation of cellular processes. Therefore, in the present review, we discussed the role of miRNAs during pancreatic, thyroid, and liver tumor progressions through FOX regulation. It has been shown that miRNAs were mainly involved in tumor progression via FOXM and FOXO targeting. This review paves the way for the introduction of miR/FOX axis as an efficient early detection marker and therapeutic target in pancreatic, thyroid, and liver tumors.

MicroRNAs as the critical regulators of Forkhead box protein family during gynecological and breast tumor progression and metastasis

Gynecological and breast tumors are one of the main causes of cancer-related mortalities among women. Despite recent advances in diagnostic and therapeutic methods, tumor relapse is observed in a high percentage of these patients due to the treatment failure. Late diagnosis in advanced tumor stages is one of the main reasons for the treatment failure and recurrence in these tumors. Therefore, it is necessary to assess the molecular mechanisms involved in progression of these tumors to introduce the efficient early diagnostic markers. Fokhead Box (FOX) is a family of transcription factors with a key role in regulation of a wide variety of cellular mechanisms. Deregulation of FOX proteins has been observed in different cancers. MicroRNAs (miRNAs) as a group of non-coding RNAs have important roles in post-transcriptional regulation of the genes involved in cellular mechanisms. They are also the non-invasive diagnostic markers due to their high stability in body fluids. Considering the importance of FOX proteins in the progression of breast and gynecological tumors, we investigated the role of miRNAs in regulation of the FOX proteins in these tumors. MicroRNAs were mainly involved in progression of these tumors through FOXM, FOXP, and FOXO. The present review paves the way to suggest a non-invasive diagnostic panel marker based on the miRNAs/FOX axis in breast and gynecological cancers.

FOXN Transcription Factors: Regulation and Significant Role in Cancer

A growing number of studies have demonstrated that cancer development is closely linked to abnormal gene expression, including alterations in the transcriptional activity of transcription factors. The Forkhead box class N (FOXN) proteins FOXN1-6 form a highly conserved class of transcription factors, which have been shown in recent years to be involved in the regulation of malignant progression in a variety of cancers. FOXNs mediate cell proliferation, cell-cycle progression, cell differentiation, metabolic homeostasis, embryonic development, DNA damage repair, tumor angiogenesis, and other critical biological processes. Therefore, transcriptional dysregulation of FOXNs can directly affect cellular physiology and promote cancer development. Numerous studies have demonstrated that the transcriptional activity of FOXNs is regulated by protein-protein interactions, microRNAs (miRNA), and posttranslational modifications (PTM). However, the mechanisms underlying the molecular regulation of FOXNs in cancer development are unclear. Here, we reviewed the molecular regulatory mechanisms of FOXNs expression and activity, their role in the malignant progression of tumors, and their value for clinical applications in cancer therapy. This review may help design experimental studies involving FOXN transcription factors, and enhance their therapeutic potential as antitumor targets.

CangFu Daotan decoction improves polycystic ovarian syndrome by downregulating FOXK1

Objective: Polycystic ovarian syndrome (PCOS) is a prevalent gynecologic disorder, often associated with abnormal follicular development. Cangfu Daotan decoction (CFD) is a traditional Chinese medicine formula that is effective in alleviating PCOS clinically, but the specific mechanism remains unclear. Forkhead box K1 (FOXK1) is associated with cellular function. This study aimed to explore the effects of CFD and FOXK1 on PCOS.Methods: High-fat diet and letrozole were combined to establish PCOS rat models. Next, primary GCs were extracted from those PCOS rats. Then, GC cells were transfected with si-FOXK1 or oe-FOXK1. CFD-contain serum was prepared, and experiments were conducted to investigate the regulation of FOXK1 by CFD.Results: FOXK1 was highly expressed in GCs of PCOS rats. Further investigation revealed that FOXK1 overexpression resulted in inhibition of proliferation and DNA synthesis, along with promotion of apoptosis and autophagy in GCs. Additionally, it was found that FOXK1 promoted the expressions of the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway-related proteins. Interestingly, treatment with CFD reversed all the effects of FOXK1 overexpression in GCs. Conclusion: This study demonstrated that CFD exerted a protective role in PCOS by inhibiting FOXK1, which provided a research basis for the application of CFD in PCOS, and suggested that FOXK1 is a novel therapeutic target in PCOS treatment.

FOXK1 regulates Wnt signalling to promote cardiogenesis

AIMS

Congenital heart disease (CHD) is the most common genetic birth defect, which has considerable morbidity and mortality. We focused on deciphering key regulators that govern cardiac progenitors and cardiogenesis. FOXK1 is a forkhead/winged helix transcription factor known to regulate cell cycle kinetics and is restricted to mesodermal progenitors, somites, and heart. In the present study, we define an essential role for FOXK1 during cardiovascular development.

METHODS AND RESULTS

We used the mouse embryoid body system to differentiate control and Foxk1 KO embryonic stem cells into mesodermal, cardiac progenitor cells and mature cardiac cells. Using flow cytometry, immunohistochemistry, cardiac beating, transcriptional and chromatin immunoprecipitation quantitative polymerase chain reaction assays, bulk RNA sequencing (RNAseq) and assay for transposase-accessible chromatin using sequencing (ATACseq) analyses, FOXK1 was observed to be an important regulator of cardiogenesis. Flow cytometry analyses revealed perturbed cardiogenesis in Foxk1 KO embryoid bodies (EBs). Bulk RNAseq analysis at two developmental stages showed a significant reduction of the cardiac molecular program in Foxk1 KO EBs compared to the control EBs. ATACseq analysis during EB differentiation demonstrated that the chromatin landscape nearby known important regulators of cardiogenesis was significantly relaxed in control EBs compared to Foxk1 KO EBs. Furthermore, we demonstrated that in the absence of FOXK1, cardiac differentiation was markedly impaired by assaying for cardiac Troponin T expression and cardiac contractility. We demonstrate that FOXK1 is an important regulator of cardiogenesis by repressing the Wnt/β-catenin signalling pathway and thereby promoting differentiation.

CONCLUSION

These results identify FOXK1 as an essential transcriptional and epigenetic regulator of cardiovascular development. Mechanistically, FOXK1 represses Wnt signalling to promote the development of cardiac progenitor cells.

The Role of Polo-Like Kinase 1 in Regulating the Forkhead Box Family Transcription Factors

Polo-like kinase 1 (PLK1) is a serine/threonine kinase with more than 600 phosphorylation substrates through which it regulates many biological processes, including mitosis, apoptosis, metabolism, RNA processing, vesicle transport, and G₂ DNA-damage checkpoint recovery, among others. Among the many PLK1 targets are members of the FOX family of transcription factors (FOX TFs), including FOXM1, FOXO1, FOXO3, and FOXK1. FOXM1 and FOXK1 have critical oncogenic roles in cancer through their antagonism of apoptotic signals and their promotion of cell proliferation, metastasis, angiogenesis, and therapeutic resistance. In contrast, FOXO1 and FOXO3 have been identified to have broad functions in maintaining cellular homeostasis. In this review, we discuss PLK1-mediated regulation of FOX TFs, highlighting the effects of PLK1 on the activity and stability of these proteins. In addition, we review the prognostic and clinical significance of these proteins in human cancers and, more importantly, the different approaches that have been used to disrupt PLK1 and FOX TF-mediated signaling networks. Furthermore, we discuss the therapeutic potential of targeting PLK1-regulated FOX TFs in human cancers.

The Crosstalk and Clinical Implications of CircRNAs and Glucose Metabolism in Gastrointestinal Cancers

The majority of glucose in tumor cells is converted to lactate despite the presence of sufficient oxygen and functional mitochondria, a phenomenon known as the "Warburg effect" or "aerobic glycolysis". Aerobic glycolysis supplies large amounts of ATP, raw material for macromolecule synthesis, and also lactate, thereby contributing to cancer progression and immunosuppression. Increased aerobic glycolysis has been identified as a key hallmark of cancer. Circular RNAs (circRNAs) are a type of endogenous single-stranded RNAs characterized by covalently circular structures. Accumulating evidence suggests that circRNAs influence the glycolytic phenotype of various cancers. In gastrointestinal (GI) cancers, circRNAs are related to glucose metabolism by regulating specific glycolysis-associated enzymes and transporters as well as some pivotal signaling pathways. Here, we provide a comprehensive review of glucose-metabolism-associated circRNAs in GI cancers. Furthermore, we also discuss the potential clinical prospects of glycolysis-associated circRNAs as diagnostic and prognostic biomarkers and therapeutic targets in GI cancers.

FOXK2 affects cancer cell response to chemotherapy by promoting nucleotide de novo synthesis

AIMS

Nucleotide de novo synthesis is essential to cell growth and survival, and its dysregulation leads to cancers and drug resistance. However, how this pathway is dysregulated in cancer has not been well clarified. This study aimed to identify the regulatory mechanisms of nucleotide de novo synthesis and drug resistance.

METHODS

By combining the ChIP-Seq data from the Cistrome Data Browser, RNA sequencing (RNA-Seq) and a luciferase-based promoter assay, we identified transcription factor FOXK2 as a regulator of nucleotide de novo synthesis. To explore the biological functions and mechanisms of FOXK2 in cancers, we conducted biochemical and cell biology assays in vitro and in vivo. Finally, we assessed the clinical significance of FOXK2 in hepatocellular carcinoma.

RESULTS

FOXK2 directly regulates the expression of nucleotide synthetic genes, promoting tumor growth and cancer cell resistance to chemotherapy. FOXK2 is SUMOylated by PIAS4, which elicits FOXK2 nuclear translocation, binding to the promoter regions and transcription of nucleotide synthetic genes. FOXK2 SUMOylation is repressed by DNA damage, and elevated FOXK2 SUMOylation promotes nucleotide de novo synthesis which causes resistance to 5-FU in hepatocellular carcinoma. Clinically, elevated expression of FOXK2 in hepatocellular carcinoma patients was associated with increased nucleotide synthetic gene expression and correlated with poor prognoses for patients.

CONCLUSION

Our findings establish FOXK2 as a novel regulator of nucleotide de novo synthesis, with potentially important implications for cancer etiology and drug resistance.

FADD as a key molecular player in cancer progression

Cancer is a leading disease-related cause of death worldwide. Despite advances in therapeutic interventions, cancer remains a major global public health problem. Cancer pathogenesis is extremely intricate and largely unknown. Fas-associated protein with death domain (FADD) was initially identified as an adaptor protein for death receptor-mediated extrinsic apoptosis. Recent evidence suggests that FADD plays a vital role in non-apoptotic cellular processes, such as proliferation, autophagy, and necroptosis. FADD expression and activity of are modulated by a complicated network of processes, such as DNA methylation, non-coding RNA, and post-translational modification. FADD dysregulation has been shown to be closely associated with the pathogenesis of numerous types of cancer. However, the detailed mechanisms of FADD dysregulation involved in cancer progression are still not fully understood. This review mainly summarizes recent findings on the structure, functions, and regulatory mechanisms of FADD and focuses on its role in cancer progression. The clinical implications of FADD as a biomarker and therapeutic target for cancer patients are also discussed. The information reviewed herein may expand researchers’ understanding of FADD and contribute to the development of FADD-based therapeutic strategies for cancer patients.

Underlying mechanisms of epithelial splicing regulatory proteins in cancer progression

Cancer is the second-leading disease-related cause of global mortality after cardiovascular disease. Despite significant advances in cancer therapeutic strategies, cancer remains one of the major obstacles to human life extension. Cancer pathogenesis is extremely complicated and not fully understood. Epithelial splicing regulatory proteins (ESRPs), including ESRP1 and ESRP2, belong to the heterogeneous nuclear ribonucleoprotein family of RNA-binding proteins and are crucial regulators of the alternative splicing of messenger RNAs (mRNAs). The expression and activity of ESRPs are modulated by various mechanisms, including post-translational modifications and non-coding RNAs. Although a growing body of evidence suggests that ESRP dysregulation is closely associated with cancer progression, the detailed mechanisms remain inconclusive. In this review, we summarize recent findings on the structures, functions, and regulatory mechanisms of ESRPs and focus on their underlying mechanisms in cancer progression. We also highlight the clinical implications of ESRPs as prognostic biomarkers and therapeutic targets in cancer treatment. The information reviewed herein could be extremely beneficial to the development of individualized therapeutic strategies for cancer patients.

Emerging Role of Non-Coding RNAs in Aortic Dissection

Aortic dissection (AD) is a fatal cardiovascular acute disease with high incidence and mortality, and it seriously threatens patients’ lives and health. The pathogenesis of AD mainly includes vascular inflammation, extracellular matrix degradation, and phenotypic conversion as well as apoptosis of vascular smooth muscle cells (VSMCs); however, its detailed mechanisms are still not fully elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are an emerging class of RNA molecules without protein-coding ability, and they play crucial roles in the progression of many diseases, including AD. A growing number of studies have shown that the dysregulation of ncRNAs contributes to the occurrence and development of AD by modulating the expression of specific target genes or the activity of related proteins. In addition, some ncRNAs exhibit great potential as promising biomarkers and therapeutic targets in AD treatment. In this review, we systematically summarize the recent findings on the underlying mechanism of ncRNA involved in AD regulation and highlight their clinical application as biomarkers and therapeutic targets in AD treatment. The information reviewed here will be of great benefit to the development of ncRNA-based therapeutic strategies for AD patients.

Non-coding RNA in cancer drug resistance: Underlying mechanisms and clinical applications

Cancer is one of the most frequently diagnosed malignant diseases worldwide, posing a serious, long-term threat to patients’ health and life. Systemic chemotherapy remains the first-line therapeutic approach for recurrent or metastatic cancer patients after surgery, with the potential to effectively extend patient survival. However, the development of drug resistance seriously limits the clinical efficiency of chemotherapy and ultimately results in treatment failure and patient death. A large number of studies have shown that non-coding RNAs (ncRNAs), particularly microRNAs, long non-coding RNAs, and circular RNAs, are widely involved in the regulation of cancer drug resistance. Their dysregulation contributes to the development of cancer drug resistance by modulating the expression of specific target genes involved in cellular apoptosis, autophagy, drug efflux, epithelial-to-mesenchymal transition (EMT), and cancer stem cells (CSCs). Moreover, some ncRNAs also possess great potential as efficient, specific biomarkers in diagnosis and prognosis as well as therapeutic targets in cancer patients. In this review, we summarize the recent findings on the emerging role and underlying mechanisms of ncRNAs involved in cancer drug resistance and focus on their clinical applications as biomarkers and therapeutic targets in cancer treatment. This information will be of great benefit to early diagnosis and prognostic assessments of cancer as well as the development of ncRNA-based therapeutic strategies for cancer patients.

CircSV2b participates in oxidative stress regulation through miR-5107-5p-Foxk1-Akt1 axis in Parkinson's disease

As a novel type of non-coding RNAs, covalently closed circular RNAs (circRNAs) are ubiquitously expressed in eukaryotes. Emerging studies have indicated that dysregulation of circRNAs was related to neurological diseases. However, the biogenesis, regulation, function, and mechanism of circRNAs in Parkinson's disease (PD) remain largely unclear. In this study, thirty-three differentially expressed circRNAs (DECs) were detected by RNA-sequencing between the MPTP-induced PD mice model and the wild-type mice. Quantitative real-time PCR was used to determine the RNA level of DECs in the striatum (STR), substantia nigra pars compacta (SNpc), and serum exosomes, and it was found that circSV2b was downregulated in PD mice. Then, functional experiments in vivo were employed to explore the effect of circSV2b in PD. For the mechanism study, dual-luciferase reporter, fluorescence in situ hybridization (FISH), RNA immunoprecipitation (RIP), RNA pull-down, gene editing, and CUT & Tag were performed in vitro to confirm that circSV2b directly sponged miR-5107-5p and alleviated the suppression of the expression of the target gene Foxk1, and then positively regulated Akt1 transcription. In vivo, the mechanistic analysis demonstrated that circSV2b overexpression resisted oxidative stress damage through the ceRNA-Akt1 axis in PD models. Taken together, these findings suggested that the miR-5107-5p-Foxk1-Akt1 axis might serve as a key target of circSV2b overexpression in PD treatment, and highlighted the significant change of circSV2b in serum exosomes. Therefore, circSV2b might be a novel biomarker for the diagnosis and treatment of PD.

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CircSV2b in serum exosomes can be used as a biomarker for the diagnosis of PD.

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CircSV2b participates in the progress of PD through the ceRNA-Akt1 axis.

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CircSV2b overexpression is neuroprotective by resisting oxidative stress injury.

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Foxk1 can regulate Akt1 transcription.

The Function of FoxK Transcription Factors in Diseases

Forkhead box (FOX) transcription factors play a crucial role in the regulation of many diseases, being an evolutionarily conserved superfamily of transcription factors. In recent years, FoxK1/2, members of its family, has been the subject of research. Even though FoxK1 and FoxK2 have some functional overlap, increasing evidence indicates that the regulatory functions of FoxK1 and FoxK2 are not the same in various physiological and disease states. It is important to understand the biological function and mechanism of FoxK1/2 for better understanding pathogenesis of diseases, predicting prognosis, and finding new therapeutic targets. There is, however, a lack of comprehensive and systematic analysis of the similarities and differences of FoxK1/2 roles in disease, prompting us to perform a literature review.

A comprehensive study of arthropod and onychophoran Fox gene expression patterns

Fox genes represent an evolutionary old class of transcription factor encoding genes that evolved in the last common ancestor of fungi and animals. They represent key-components of multiple gene regulatory networks (GRNs) that are essential for embryonic development. Most of our knowledge about the function of Fox genes comes from vertebrate research, and for arthropods the only comprehensive gene expression analysis is that of the fly Drosophila melanogaster. For other arthropods, only selected Fox genes have been investigated. In this study, we provide the first comprehensive gene expression analysis of arthropod Fox genes including representative species of all main groups of arthropods, Pancrustacea, Myriapoda and Chelicerata. We also provide the first comprehensive analysis of Fox gene expression in an onychophoran species. Our data show that many of the Fox genes likely retained their function during panarthropod evolution highlighting their importance in development. Comparison with published data from other groups of animals shows that this high degree of evolutionary conservation often dates back beyond the last common ancestor of Panarthropoda.

The FOXO family of transcription factors: key molecular players in gastric cancer

Gastric cancer (GC) is the fifth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death with an oncological origin. Despite its decline in incidence and mortality in recent years, GC remains a global public problem that seriously threatens patients' health and lives. The forkhead box O proteins (FOXOs) are a family of evolutionarily conserved transcription factors (TFs) with crucial roles in cell fate decisions. In mammals, the FOXO family consists of four members FOXO1, 3a, 4, and 6. FOXOs play crucial roles in a variety of biological processes, such as development, metabolism, and stem cell maintenance, by regulating the expression of their target genes in space and time. An accumulating amount of evidence has shown that the dysregulation of FOXOs is involved in GC progression by affecting multiple cellular processes, including proliferation, apoptosis, invasion, metastasis, cell cycle progression, carcinogenesis, and resistance to chemotherapeutic drugs. In this review, we systematically summarize the recent findings on the regulatory mechanisms of FOXO family expression and activity and elucidate its roles in GC progression. Moreover, we also highlight the clinical implications of FOXOs in GC treatment.

Combining Recombinase-Mediated Cassette Exchange Strategy with Quantitative Proteomic and Phosphoproteomic Analyses to Inspect Intracellular Functions of the Tumor Suppressor Galectin-4 in Colorectal Cancer Cells

Galectin-4 (Gal4) has been suggested to function as a tumor suppressor in colorectal cancer (CRC). In order to systematically explore its function in CRC, we established a CRC cell line where Gal4 expression can be regulated via the doxycycline (dox)-inducible expression of a single copy wildtype LGALS4 transgene generated by recombinase-mediated cassette exchange (RMCE). Using this model and applying in-depth proteomic and phosphoproteomic analyses, we systematically screened for intracellular changes induced by Gal4 expression. Overall, 3083 cellular proteins and 2071 phosphosites were identified and quantified, of which 1603 could be matched and normalized to their protein expression levels. A bioinformatic analysis revealed that most of the regulated proteins and phosphosites can be localized in the nucleus and are categorized as nucleic acid-binding proteins. The top candidates whose expression was modulated by Gal4 are PURB, MAPKAPK3, BTF3 and BCAR1, while the prime candidates with altered phosphorylation included ZBTB7A, FOXK1, PURB and CK2beta. In order to validate the (phospho)proteomic data, we confirmed these candidates by a radiometric metabolic-labelling and immunoprecipitation strategy. All candidates exert functions in the transcriptional or translational control, indicating that Gal4 might be involved in these processes by affecting the expression or activity of these proteins.

Tissue-Based Markers as a Tool to Assess Response to Neoadjuvant Radiotherapy in Rectal Cancer-Systematic Review

According to current guidelines, the current treatment for locally advanced rectal cancer is neoadjuvant therapy, followed by a total mesorectal excision. However, radiosensitivity tends to differ among patients due to tumor heterogeneity, making it difficult to predict the possible outcomes of the neoadjuvant therapy. This review aims to investigate different types of tissue-based biomarkers and their capability of predicting tumor response to neoadjuvant therapy in patients with locally advanced rectal cancer. We identified 169 abstracts in NCBI PubMed, selected 48 reports considered to meet inclusion criteria and performed this systematic review. Multiple classes of molecular biomarkers, such as proteins, DNA, micro-RNA or tumor immune microenvironment, were studied as potential predictors for rectal cancer response; nonetheless, no literature to date has provided enough sufficient evidence for any of them to be introduced into clinical practice.

FoxK1 is Required for Ectodermal Cell Differentiation During Planarian Regeneration

Forkhead box (Fox) genes belong to the “winged helix” transcription factor superfamily. The function of some Fox genes is well known, such as the role of foxO in controlling metabolism and longevity and foxA in controlling differentiation of endodermal tissues. However, the role of some Fox factors is not yet well characterized. Such is the case of FoxK genes, which are mainly studied in mammals and have been implicated in diverse processes including cell proliferation, tissue differentiation and carcinogenesis. Planarians are free-living flatworms, whose importance in biomedical research lies in their regeneration capacity. Planarians possess a wide population of pluripotent adult stem cells, called neoblasts, which allow them to regenerate any body part after injury. In a recent study, we identified three foxK paralogs in the genome of Schmidtea mediterranea. In this study, we demonstrate that foxK1 inhibition prevents regeneration of the ectodermal tissues, including the nervous system and the epidermis. These results correlate with foxK1 expression in neoblasts and in neural progenitors. Although the triggering of wound genes expression, polarity reestablishment and proliferation was not affected after foxK1 silencing, the apoptotic response was decreased. Altogether, these results suggest that foxK1 would be required for differentiation and maintenance of ectodermal tissues.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

MicroRNAs and Corresponding Targets in Esophageal Cancer as Shown In Vitro and In Vivo in Preclinical Models

Squamous cell carcinoma of the esophagus is associated with a dismal prognosis. Therefore, identification of new targets and implementation of new treatment modalities are issues of paramount importance. Based on a survey of the literature, we identified microRNAs conferring antitumoral activity in preclinical in vivo experiments. In the category of miRs targeting secreted factors and transmembrane receptors, four miRs were up-regulated and 10 were down-regulated compared with five out of nine in the category transcription factors, and six miRs were down-regulated in the category enzymes, including metabolic enzymes. The down-regulated miRs have targets which can be inhibited by small molecules or antibody-related entities, or re-expressed by reconstitution therapy. Up-regulated miRs have targets which can be reconstituted with small molecules or inhibited with antagomirs.

Long Non-Coding RNA in Gastric Cancer: Mechanisms and Clinical Implications for Drug Resistance

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide, with high recurrence and mortality rate. Chemotherapy, including 5-fluorouracil (5-FU), adriamycin (ADR), vincristine (VCR), paclitaxel (PTX), and platinum drugs, remains one of the fundamental methods of GC treatment and has efficiently improved patients’ prognosis. However, most patients eventually develop resistance to chemotherapeutic agents, leading to the failure of clinical treatment and patients’ death. Recent studies suggest that long non-coding RNAs (lncRNAs) are involved in the drug resistance of GC by modulating the expression of drug resistance-related genes via sponging microRNAs (miRNAs). Moreover, lncRNAs also play crucial roles in GC drug resistance via a variety of mechanisms, such as the regulation of the oncogenic signaling pathways, inhibition of apoptosis, induction of autophagy, modulation of cancer stem cells (CSCs), and promotion of the epithelial-to-mesenchymal transition (EMT) process. Some of lncRNAs exhibit great potential as diagnostic and prognostic biomarkers, as well as therapeutic targets for GC patients. Therefore, understanding the role of lncRNAs and their mechanisms in GC drug resistance may provide us with novel insights for developing strategies for individual diagnosis and therapy. In this review, we summarize the recent findings on the mechanisms underlying GC drug resistance regulated by lncRNAs. We also discuss the potential clinical applications of lncRNAs as biomarkers and therapeutic targets in GC.

The regulation of PBXs and their emerging role in cancer

Pre‐B‐cell leukaemia transcription factor (PBX) proteins are a subfamily of evolutionarily conserved, atypical homeodomain transcription factors that belong to the superfamily of three amino acid loop extension (TALE) homeodomain proteins. Members of the PBX family play crucial roles in regulating multiple pathophysiological processes, such as the development of organs, congenital cardiac defects and carcinogenesis. The dysregulation of PBXs has been shown to be closely associated with many diseases, particularly cancer. However, the detailed mechanisms of PBX dysregulation in cancer progression are still inconclusive. In this review, we summarize the recent advances in the structures, functions and regulatory mechanisms of PBXs, and discuss their underlying mechanisms in cancer progression. We also highlight the great potential of PBXs as biomarkers for the early diagnosis and prognostic evaluation of cancer as well as their therapeutic applications. The information reviewed here may expand researchers’ understanding of PBXs and could strengthen the clinical implication of PBXs in cancer treatment.

Long non-coding RNAs: Biogenesis, functions, and clinical significance in gastric cancer

Gastric cancer (GC) is one of the most prevalent malignant tumor types and the third leading cause of cancer-related death worldwide. Its morbidity and mortality are very high due to a lack of understanding about its pathogenesis and the slow development of novel therapeutic strategies. Long non-coding RNAs (lncRNAs) are a class of non-coding RNAs with a length of more than 200 nt. They play crucial roles in a wide spectrum of physiological and pathological processes by regulating the expression of genes involved in proliferation, differentiation, apoptosis, cell cycle, invasion, metastasis, DNA damage, and carcinogenesis. The aberrant expression of lncRNAs has been found in various cancer types. A growing amount of evidence demonstrates that lncRNAs are involved in many aspects of GC pathogenesis, including its occurrence, metastasis, and recurrence, indicating their potential role as novel biomarkers in the diagnosis, prognosis, and therapeutic targets of GC. This review systematically summarizes the biogenesis, biological properties, and functions of lncRNAs and highlights their critical role and clinical significance in GC. This information may contribute to the development of better diagnostics and treatments for GC.

Mechanisms of Action And Clinical Implications of MicroRNAs in the Drug Resistance of Gastric Cancer

Gastric cancer (GC) is one of the most common malignant tumors of digestive systems worldwide, with high recurrence and mortality. Chemotherapy is still the standard treatment option for GC and can effectively improve the survival and life quality of GC patients. However, with the emergence of drug resistance, the clinical application of chemotherapeutic agents has been seriously restricted in GC patients. Although the mechanisms of drug resistance have been broadly investigated, they are still largely unknown. MicroRNAs (miRNAs) are a large group of small non-coding RNAs (ncRNAs) widely involved in the occurrence and progression of many cancer types, including GC. An increasing amount of evidence suggests that miRNAs may play crucial roles in the development of drug resistance by regulating some drug resistance-related proteins as well as gene expression. Some also exhibit great potential as novel biomarkers for predicting drug response to chemotherapy and therapeutic targets for GC patients. In this review, we systematically summarize recent advances in miRNAs and focus on their molecular mechanisms in the development of drug resistance in GC progression. We also highlight the potential of drug resistance-related miRNAs as biomarkers and therapeutic targets for GC patients.

MYCN and MAX alterations in Wilms tumor and identification of novel N-MYC interaction partners as biomarker candidates

BACKGROUND

Wilms tumor (WT) is the most common renal tumor in childhood. Among others, MYCN copy number gain and MYCN P44L and MAX R60Q mutations have been identified in WT. MYCN encodes a transcription factor that requires dimerization with MAX to activate transcription of numerous target genes. MYCN gain has been associated with adverse prognosis in different childhood tumors including WT. The MYCN P44L and MAX R60Q mutations, located in either the transactivating or basic helix-loop-helix domain, respectively, are predicted to be damaging by different pathogenicity prediction tools, but the functional consequences remain to be characterized.

METHODS

We screened a large cohort of unselected WTs for MYCN and MAX alterations. Wild-type and mutant protein function were characterized biochemically, and we analyzed the N-MYC protein interactome by mass spectrometric analysis of N-MYC containing protein complexes.

RESULTS

Mutation screening revealed mutation frequencies of 3% for MYCN P44L and 0.9% for MAX R60Q that are associated with a higher risk of relapse. Biochemical characterization identified a reduced transcriptional activation potential for MAX R60Q, while the MYCN P44L mutation did not change activation potential or protein stability. The protein interactome of N-MYC-P44L was likewise not altered as shown by mass spectrometric analyses of purified N-MYC complexes. Nevertheless, we could identify a number of novel N-MYC partner proteins, e.g. PEG10, YEATS2, FOXK1, CBLL1 and MCRS1, whose expression is correlated with MYCN in WT samples and several of these are known for their own oncogenic potential.

CONCLUSIONS

The strongly elevated risk of relapse associated with mutant MYCN and MAX or elevated MYCN expression corroborates their role in WT oncogenesis. Together with the newly identified co-expressed interactors they expand the range of potential biomarkers for WT stratification and targeting, especially for high-risk WT.

FOXK2 transcriptionally activating VEGFA induces apatinib resistance in anaplastic thyroid cancer through VEGFA/VEGFR1 pathway

Anaplastic thyroid carcinoma (ATC) is a rare and extremely aggressive type of thyroid cancer, and the potential mechanisms involved in ATC progression remains unclarified. In this study, we found that forkhead box K2 (FOXK2) was upregulated in ATC tissues, and the expression of FOXK2 was associated with tumor size. Evidenced by RNA-seq and Chromatin immunoprecipitation (ChIP)-seq assays, FOXK2 positively regulated VEGF and VEGFR signaling network, among which only VEGFA could be noticed in both RNA-seq and ChIP-seq results. ChIP, dual-luciferase reporter system and functional experiments further confirmed that FOXK2 promoted angiogenesis by inducing the transcription of VEGFA. On VEGFR2 blockage by specific targeting agent, such as Apatinib, FOXK2 could rapidly trigger therapeutic resistance. Mechanical analyses revealed that VEGFA transcriptionally induced by FOXK2 could bind to VEGFR1 as a compensation for VEGFR2 blockage, which promoted angiogenesis by activating ERK, PI3K/AKT and P38/MAPK signaling in human umbilical vein endothelial cells (HUVECs). Synergic effect on anti-angiogenesis could be observed when VEGFR1 suppressor AF321 was included in VEGFR2 inhibition system, which clarified the pivot role of FOXK2 in VEGFR2 targeting therapy resistance. More importantly, the binding of VEGFA to VEGFR1 could further promoter FOXK2-mediated VEGFA transcription, which consequently constituted a positive feedback loop. Therefore, the novel loop VEGFA/VEGFR1/FOXK2 functioned importantly in resistance to VEGFR2 targeting therapy in FOXK2+ ATCs. Altogether, FOXK2 plays critical roles in ATC angiogenesis and VEGFR2 blockage resistance by inducing VEGFA transcription. FOXK2 represents a potentially new therapeutic strategy and biomarker for anti-angiogenic therapy against ATC.

Oscillating waves of Fox, Cyclin and CDK gene expression indicate unique spatiotemporal control of cell cycling during nervous system development in onychophorans

Forkhead box (Fox) genes code for a class of transcription factors with many different fundamental functions in animal development including cell cycle control. Other important factors of cell cycle control are Cyclins and Cyclin-dependent kinases (CDKs). Here we report on the oscillating expression of three Fox genes, FoxM, FoxN14 (jumeaux) and FoxN23 (Checkpoint suppressor like-1), Cyclins and CDKs in an onychophoran, a representative of a relatively small group of animals that are closely related to the arthropods. Expression of these genes is in the form of several waves that start as dot-like domains in the center of each segment and then transform into concentric rings that run towards the periphery of the segments. This oscillating gene expression, however, occurs exclusively along the anterior-posterior body axis in the tissue ventral to the base of the appendages, a region where the central nervous system and the enigmatic ventral and preventral organs of the onychophoran develop. We suggest that the oscillating gene expression and the resulting waves of expression we report are likely correlated with cell cycle control during the development of the onychophoran nervous system. This intriguing patterning appears to be unique for onychophorans as it is not found in any of the arthropods we also investigated in this study, and is likely correlated with the slow embryonic development of onychophorans compared to arthropods.

Transcription factor forkhead box K1 regulates miR-32 expression and enhances cell proliferation in colorectal cancer

Increased microRNA (miR)-32 expression in colorectal cancer (CRC) tissues enhances CRC cell proliferation, migration, invasion and attenuates CRC cell apoptosis by repressing the expression of phosphatase and tensin homolog (PTEN). Forkhead box K1 (FOXK1) was identified as a potential interacting transcription factor using DNA pull-down assays and mass spectrometry. The present study aimed to elucidate the role of FOXK1 in regulating miR-32 expression in CRC. The expressions of FOXK1, miR-32, transmembrane protein 245 gene (TMEM245) and PTEN were compared between CRC and normal colonic tissues. Levels of miR-32, TMEM245, PTEN and the proliferation and apoptosis of CRC cells were studied using FOXK1-overexpression or knockdown, or by simultaneously interfering with FOXK1 and miR-32 expression. Direct FOXK1 binding to the miR-32 promoter was verified using chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays. The results showed elevated FOXK1, miR-32 and TMEM245 expression, and significantly decreased PTEN expression in CRC, compared with normal colonic tissues. Correlations between the expressions of TMEM245 and miR-32, FOXK1 and miR-32, and FOXK1 and TMEM245 were positive and significant. FOXK1-knockdown led to decreased miR-32 and TMEM245 expression and increased PTEN expression, whereas FOXK1-overexpression had the opposite effect. Overexpressed FOXK1 promoted the malignancy of CRC cells in vitro by stimulating proliferation and reducing apoptosis; whereas FOXK1-depletion suppressed such malignancy and a miR-32 inhibitor partially reversed the effects of FOXK1. The results of ChIP and dual-luciferase reporter assays indicated that FOXK1 directly binds to the promoter of TMEM245/miR-32. Thus, the FOXK1-miR-32-PTEN signaling axis may play a crucial role in the pathogenesis and development of CRC.

Targets and regulation of microRNA-652-3p in homoeostasis and disease

microRNA are small non-coding RNA molecules which inhibit gene expression by binding mRNA, preventing its translation. As important regulators of gene expression, there is increasing interest in microRNAs as potential diagnostic biomarkers and therapeutic targets. Studies investigating the role of one of the miRNA-miR-652-3p-detail diverse roles for this miRNA in normal cell homoeostasis and disease states, including cancers, cardiovascular disease, mental health, and central nervous system diseases. Here, we review recent literature surrounding miR-652-3p, discussing its known target genes and their relevance to disease progression. These studies demonstrate that miR-652-3p targets LLGL1 and ZEB1 to modulate cell polarity mechanisms, with impacts on cancer metastasis and asymmetric cell division. Inhibition of the NOTCH ligand JAG1 by miR-652-3p can have diverse effects on angiogenesis and immune cell regulation. Investigation of miR-652-3p and other dysregulated miRNAs identified a number of pathways potentially regulated by miR-652-3p. This review demonstrates that miR-652-3p has great promise as a diagnostic or therapeutic target due to its activity across multiple cellular systems.

TIMELESS inhibits breast cancer cell invasion and metastasis by down-regulating the expression of MMP9

Breast cancer is the first killer leading to female death, and tumor metastasis is one of the important factors leading to the death of patients, but the specific mechanism of breast cancer metastasis is not very clear at present. Our study showed that overexpression of TIMELESS could significantly inhibit the invasion and metastasis of breast cancer cells ZR-75-30 and the assembly of F-actin protein. On the contrary, knockdown of TIMELESS promoted the invasion and metastasis of breast cancer cells. Further study revealed that TIMELESS overexpression decreased the mRNA and protein levels of MMP9. Furthermore, TIMELESS could interact with p65, leading to repress the association of p65 and its acetyltransferase CBP and down-regulating the acetylation level of p65, which inhibited the activation of NF-κB signal pathway. In conclusion, our research showed that TIMELESS may repress the invasion and metastasis of breast cancer cells via inhibiting the acetylation of p65, inhibiting the activation of NF-κB, thus down-regulating the expression of MMP9, and then inhibiting the invasion and metastasis of breast cancer cells.

PR-DUB maintains the expression of critical genes through FOXK1/2- and ASXL1/2/3-dependent recruitment to chromatin and H2AK119ub1 deubiquitination

Polycomb group proteins are important for maintaining gene expression patterns and cell identity in metazoans. The mammalian Polycomb repressive deubiquitinase (PR-DUB) complexes catalyze removal of monoubiquitination on lysine 119 of histone H2A (H2AK119ub1) through a multiprotein core comprised of BAP1, HCFC1, FOXK1/2, and OGT in combination with either of ASXL1, 2, or 3. Mutations in PR-DUB components are frequent in cancer. However, mechanistic understanding of PR-DUB function in gene regulation is limited. Here, we show that BAP1 is dependent on the ASXL proteins and FOXK1/2 in facilitating gene activation across the genome. Although PR-DUB was previously shown to cooperate with PRC2, we observed minimal overlap and functional interaction between BAP1 and PRC2 in embryonic stem cells. Collectively, these results demonstrate that PR-DUB, by counteracting accumulation of H2AK119ub1, maintains chromatin in an optimal configuration ensuring expression of genes important for general functions such as cell metabolism and homeostasis.

Targeting phosphatidylserine for Cancer therapy: prospects and challenges

Cancer is a leading cause of mortality and morbidity worldwide. Despite major improvements in current therapeutic methods, ideal therapeutic strategies for improved tumor elimination are still lacking. Recently, immunotherapy has attracted much attention, and many immune-active agents have been approved for clinical use alone or in combination with other cancer drugs. However, some patients have a poor response to these agents. New agents and strategies are needed to overcome such deficiencies. Phosphatidylserine (PS) is an essential component of bilayer cell membranes and is normally present in the inner leaflet. In the physiological state, PS exposure on the external leaflet not only acts as an engulfment signal for phagocytosis in apoptotic cells but also participates in blood coagulation, myoblast fusion and immune regulation in nonapoptotic cells. In the tumor microenvironment, PS exposure is significantly increased on the surface of tumor cells or tumor cell-derived microvesicles, which have innate immunosuppressive properties and facilitate tumor growth and metastasis. To date, agents targeting PS have been developed, some of which are under investigation in clinical trials as combination drugs for various cancers. However, controversial results are emerging in laboratory research as well as in clinical trials, and the efficiency of PS-targeting agents remains uncertain. In this review, we summarize recent progress in our understanding of the physiological and pathological roles of PS, with a focus on immune suppressive features. In addition, we discuss current drug developments that are based on PS-targeting strategies in both experimental and clinical studies. We hope to provide a future research direction for the development of new agents for cancer therapy.

Long non-coding RNA HUMT hypomethylation promotes lymphangiogenesis and metastasis via activating FOXK1 transcription in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer with highly invasive ability and metastatic nature to the lymph nodes. Long non-coding RNAs (lncRNAs) have been widely explored in cancer tumorigenesis and progression. However, their roles in TNBC lymph node metastasis remains rarely studied.

METHODS

The expression of lncRNA highly upregulated in metastatic TNBC (HUMT) in cell lines and tissues was detected by quantitative real-time PCR (qRT-PCR) and in situ hybridization (ISH). RNA immunoprecipitation (RIP) and RNA pulldown were used to verify the interaction between lncRNA and protein. Chromatin immunoprecipitation (CHIP) and dCas9-gRNA-guided chromatin immunoprecipitation (dCas9-CHIP) were conducted to identify the specific binding site of HUMT-YBX1 complex. Western blot was used to detect the downstream of HUMT.

RESULTS

HUMT was significantly upregulated in lymph node invasive cells and predicted poorer clinical prognosis. Functional study indicated that HUMT promoted lymphangiogenesis and lymph node metastasis. Bioinformatic analysis and qRT-PCR showed that the high expression of HUMT was correlated with the hypomethylation status of its promoter region. Further, HUMT recruited Y-box binding protein 1 (YBX1) to form a novel transcription complex and activated the expression of forkhead box k1 (FOXK1), thus enhancing the expression of vascular endothelial growth factor C (VEGFC). The therapeutic value was further validated in patient-derived xenograft (PDX) models, and a combined marker panel exhibited a better prognostic value for TNBC in receiver operating characteristic (ROC) analysis.

CONCLUSIONS

Our study identified a novel TNBC lymph node metastasis-associated lncRNA, which promoted TNBC progression and indicated a novel biomarker and potential therapeutic target for TNBC lymph node metastasis.