FoxM1, a forkhead transcription factor is a master cell cycle regulator for mouse mature T cells but not double positive thymocytes

The role of FoxM1 in immune cells

Forkhead box M1 (FoxM1), a proliferation specific transcriptional modulator, plays a principal role in many physiological and pathological processes. FoxM1-mediated oncogenic processes have been well addressed. However, functions of FoxM1 in immune cells are less summarized. The literatures about the expression of FoxM1 and its regulation on immune cells were searched on PubMed and Google Scholar. In this review, we provide an overview on the roles of FoxM1 in regulating functions of immune cells, including T cells, B cells, monocytes, macrophages, and dendritic cells, and discuss their contributions to diseases.

Pyrimidine de novo synthesis inhibition selectively blocks effector but not memory T cell development

Blocking pyrimidine de novo synthesis by inhibiting dihydroorotate dehydrogenase is used to treat autoimmunity and prevent expansion of rapidly dividing cell populations including activated T cells. Here we show memory T cell precursors are resistant to pyrimidine starvation. Although the treatment effectively blocked effector T cells, the number, function and transcriptional profile of memory T cells and their precursors were unaffected. This effect occurred in a narrow time window in the early T cell expansion phase when developing effector, but not memory precursor, T cells are vulnerable to pyrimidine starvation. This vulnerability stems from a higher proliferative rate of early effector T cells as well as lower pyrimidine synthesis capacity when compared with memory precursors. This differential sensitivity is a drug-targetable checkpoint that efficiently diminishes effector T cells without affecting the memory compartment. This cell fate checkpoint might therefore lead to new methods to safely manipulate effector T cell responses.

LDHA as a regulator of T cell fate and its mechanisms in disease

T cells are the main force of anti-infection and antitumor and are also involved in autoimmune diseases. During the development of these diseases, T cells need to rapidly produce large amounts of energy to satisfy their activation, proliferation, and differentiation. In this review, we introduced lactate dehydrogenase A(LDHA), predominantly involved in glycolysis, which provides energy for T cells and plays a dual role in disease by mediating lactate production, non-classical enzyme activity, and oxidative stress. Mechanistically, the signaling molecule can interact with the LDHA promoter or regulate LDHA activity through post-translational modifications. These latest findings suggest that modulation of LDHA may have considerable therapeutic effects in diseases where T-cell activation is an important pathogenesis.

Transcription Regulation and Genome Rewiring Governing Sensitivity and Resistance to FOXM1 Inhibition in Breast Cancer

Forkhead box M1 (FOXM1), an oncogenic transcription factor associated with aggressiveness and highly expressed in many cancers, is an emerging therapeutic target. Using novel 1,1-diarylethylene-diammonium small molecule FOXM1 inhibitors, we undertook transcriptomic, protein, and functional analyses to identify mechanisms by which these compounds impact breast cancer growth and survival, and the changes that occur in estrogen receptor (ERα)-positive and triple negative breast cancer cells that acquire resistance upon long-term treatment with the inhibitors. In sensitive cells, these compounds regulated FOXM1 gene networks controlling cell cycle progression, DNA damage repair, and apoptosis. Resistant cells showed transcriptional alterations that reversed the expression of many genes in the FOXM1 network and rewiring that enhanced inflammatory signaling and upregulated HER2 or EGFR growth factor pathways. ERα-positive breast cancer cells that developed resistance showed greatly reduced ERα levels and responsiveness to fulvestrant and a 10-fold increased sensitivity to lapatinib, suggesting that targeting rewired processes in the resistant state may provide benefits and prolong anticancer effectiveness. Improved understanding of how FOXM1 inhibitors suppress breast cancer and how cancer cells can defeat their effectiveness and acquire resistance should be helpful in directing further studies to move these agents towards translation into the clinic.

PRMT7 targets of Foxm1 controls alveolar myofibroblast proliferation and differentiation during alveologenesis

Although aberrant alveolar myofibroblasts (AMYFs) proliferation and differentiation are often associated with abnormal lung development and diseases, such as bronchopulmonary dysplasia (BPD), chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF), epigenetic mechanisms regulating proliferation and differentiation of AMYFs remain poorly understood. Protein arginine methyltransferase 7 (PRMT7) is the only reported type III enzyme responsible for monomethylation of arginine residue on both histone and nonhistone substrates. Here we provide evidence for PRMT7's function in regulating AMYFs proliferation and differentiation during lung alveologenesis. In PRMT7-deficient mice, we found reduced AMYFs proliferation and differentiation, abnormal elastin deposition, and failure of alveolar septum formation. We further shown that oncogene forkhead box M1 (Foxm1) is a direct target of PRMT7 and that PRMT7-catalyzed monomethylation at histone H4 arginine 3 (H4R3me1) directly associate with chromatin of Foxm1 to activate its transcription, and thereby regulate of cell cycle-related genes to inhibit AMYFs proliferation and differentiation. Overexpression of Foxm1 in isolated myofibroblasts (MYFs) significantly rescued PRMT7-deficiency-induced cell proliferation and differentiation defects. Thus, our results reveal a novel epigenetic mechanism through which PRMT7-mediated histone arginine monomethylation activates Foxm1 transcriptional expression to regulate AMYFs proliferation and differentiation during lung alveologenesis and may represent a potential target for intervention in pulmonary diseases.

Co-regulation and function of FOXM1/RHNO1 bidirectional genes in cancer

The FOXM1 transcription factor is an oncoprotein and a top biomarker of poor prognosis in human cancer. Overexpression and activation of FOXM1 is frequent in high-grade serous carcinoma (HGSC), the most common and lethal form of human ovarian cancer, and is linked to copy number gains at chromosome 12p13.33. We show that FOXM1 is co-amplified and co-expressed with RHNO1, a gene involved in the ATR-Chk1 signaling pathway that functions in the DNA replication stress response. We demonstrate that FOXM1 and RHNO1 are head-to-head (i.e., bidirectional) genes (BDG) regulated by a bidirectional promoter (BDP) (named F/R-BDP). FOXM1 and RHNO1 each promote oncogenic phenotypes in HGSC cells, including clonogenic growth, DNA homologous recombination repair, and poly-ADP ribosylase inhibitor resistance. FOXM1 and RHNO1 are one of the first examples of oncogenic BDG, and therapeutic targeting of FOXM1/RHNO1 BDG is a potential therapeutic approach for ovarian and other cancers.

Sirtuin 6 deficiency induces endothelial cell senescence via downregulation of forkhead box M1 expression

Cellular senescence of endothelial cells causes vascular dysfunction, promotes atherosclerosis, and contributes to the development of age-related vascular diseases. Sirtuin 6 (SIRT6), a conserved NAD+-dependent protein deacetylase, has beneficial effects against aging, despite the fact that its functional mechanisms are largely uncharacterized. Here, we show that SIRT6 protects endothelial cells from senescence. SIRT6 expression is progressively decreased during both oxidative stress-induced senescence and replicative senescence. SIRT6 deficiency leads to endothelial dysfunction, growth arrest, and premature senescence. Using genetically engineered endothelial cell-specific SIRT6 knockout mice, we also show that down-regulation of SIRT6 expression in endothelial cells exacerbates vascular aging. Expression microarray analysis demonstrated that SIRT6 modulates the expression of multiple genes involved in cell cycle regulation. Specifically, SIRT6 appears to regulate the expression of forkhead box M1 (FOXM1), a critical transcription factor for cell cycle progression and senescence. Overexpression of FOXM1 ameliorates SIRT6 deficiency-induced endothelial cell senescence. In this work, we demonstrate the role of SIRT6 as an anti-aging factor in the vasculature. These data may provide the basis for future novel therapeutic approaches against age-related vascular disorders.

Genetic factors associated with cancer racial disparity - an integrative study across twenty-one cancer types

It is well known that different racial groups have significantly different incidence and mortality rates for certain cancers. It has been suggested that biological factors play a major role in these cancer racial disparities. Previous studies on the biological factors contributing to cancer racial disparity have generated a very large number of candidate factors, although there is modest agreement among the results of the different studies. Here, we performed an integrative analysis using genomic data of 21 cancer types from TCGA, GTEx, and the 1000 Genomes Project to identify biological factors contributing to racial disparity in cancer. We also built a companion website with additional results for cancer researchers to freely mine. Our study identified genes, gene families, and pathways displaying similar differential expression patterns between different racial groups across multiple cancer types. Among them, XKR9 gene expression was found to be significantly associated with overall survival for all cancers combined as well as for several individual cancers. Our results point to the interesting hypothesis that XKR9 could be a novel drug target for cancer immunotherapy. Bayesian network modeling showed that XKR9 is linked to important cancer-related genes, including FOXM1, cyclin B1, and RB1CC1 (RB1 regulator). In addition, metabolic pathways, neural signaling pathways, and several cancer-related gene families were found to be significantly associated with cancer racial disparities for multiple cancer types. Single nucleotide polymorphisms (SNPs) discovered through integrating data from the TCGA, GTEx, and 1000 Genomes databases provide biologists the opportunity to test highly promising, targeted hypotheses to gain a deeper understanding of the genetic drivers of cancer racial disparity and cancer biology in general.

Predicting FOXM1-Mediated Gene Regulation through the Analysis of Genome-Wide FOXM1 Binding Sites in MCF-7, K562, SK-N-SH, GM12878 and ECC-1 Cell Lines

Forkhead box protein M1 (FOXM1) is a key transcription factor (TF) that regulates a common set of genes related to the cell cycle in various cell types. However, the mechanism by which FOXM1 controls the common gene set in different cellular contexts is unclear. In this study, a comprehensive meta-analysis of genome-wide FOXM1 binding sites in ECC-1, GM12878, K562, MCF-7, and SK-N-SH cell lines was conducted to predict FOXM1-driven gene regulation. Consistent with previous studies, different TF binding motifs were identified at FOXM1 binding sites, while the NFY binding motif was found at 81% of common FOXM1 binding sites in promoters of cell cycle-related genes. The results indicated that FOXM1 might control the gene set through interaction with the NFY proteins, while cell type-specific genes were predicted to be regulated by enhancers with FOXM1 and cell type-specific TFs. We also found that the high expression level of FOXM1 was significantly associated with poor prognosis in nine types of cancer. Overall, these results suggest that FOXM1 is predicted to function as a master regulator of the cell cycle through the interaction of NFY-family proteins, and therefore the inhibition of FOXM1 could be an attractive strategy for cancer therapy.

Using Micro- and Macro-Level Network Metrics Unveils Top Communicative Gene Modules in Psoriasis

(1) Background: Psoriasis is a multifactorial chronic inflammatory disorder of the skin, with significant morbidity, characterized by hyperproliferation of the epidermis. Even though psoriasis’ etiology is not fully understood, it is believed to be multifactorial, with numerous key components. (2) Methods: In order to cast light on the complex molecular interactions in psoriasis vulgaris at both protein–protein interactions and transcriptomics levels, we studied a set of microarray gene expression analyses consisting of 170 paired lesional and non-lesional samples. Afterwards, a network analysis was conducted on the protein–protein interaction network of differentially expressed genes based on micro- and macro-level network metrics at a systemic level standpoint. (3) Results: We found 17 top communicative genes, all of which were experimentally proven to be pivotal in psoriasis, which were identified in two modules, namely the cell cycle and immune system. Intra- and inter-gene interaction subnetworks from the top communicative genes might provide further insight into the corresponding characteristic interactions. (4) Conclusions: Potential gene combinations for therapeutic/diagnostics purposes were identified. Moreover, our proposed workflow could be of interest to a broader range of future biological network analysis studies.

NPM-ALK Is a Key Regulator of the Oncoprotein FOXM1 in ALK-Positive Anaplastic Large Cell Lymphoma

Forkhead Box M1 (FOXM1) is an oncogenic transcription factor implicated in the pathogenesis of solid and hematologic cancers. In this study, we examined the significance of FOXM1 in NPM-ALK-positive anaplastic large cell lymphoma (NPM-ALK + ALCL), with a focus on how it interacts with NPM-ALK, which is a key oncogenic driver in these tumors. FOXM1 was expressed in NPM-ALK + ALCL cell lines (5/5), patient samples (21/21), and tumors arising in NPM-ALK transgenic mice (4/4). FOXM1 was localized in the nuclei and confirmed to be transcriptionally active. Inhibition of FOXM1 in two NPM-ALK + ALCL cells using shRNA and pharmalogic agent (thiostrepton) resulted in reductions in cell growth and soft-agar colony formation, which were associated with apoptosis and cell-cycle arrest. FOXM1 is functionally linked to NPM-ALK, as FOXM1 enhanced phosphorylation of the NPM-ALK/STAT3 axis. Conversely, DNA binding and transcriptional activity of FOXM1 was dependent on the expression of NPM-ALK. Further studies showed that this dependency hinges on the binding of FOXM1 to NPM1 that heterodimerizes with NPM-ALK, and the phosphorylation status of NPM-ALK. In conclusion, we identified FOXM1 as an important oncogenic protein in NPM-ALK+ ALCL. Our results exemplified that NPM-ALK exerts oncogenic effects in the nuclei and illustrated a novel role of NPM1 in NPM-ALK pathobiology.

ASGR1 but not FOXM1 expression decreases in the peripheral blood mononuclear cells of diabetic atherosclerotic patients

BACKGROUND

The ASGR1 was recently shown to play a key role in the development of coronary artery disease (CAD), but its exact mechanism of action in the CAD pathogenesis is not yet known. This study evaluates the possible association between the expression level of ASGR1 and its downstream transcription factor FOXM1 in the inflammatory cells of peripheral blood (PBMC) and the pathogenesis of CAD in the Diabetic condition.

METHODS

Blood samples were taken from the candidates who had visited the Tehran Heart Center and had underwent diagnostic tests with respect to diabetes and CAD. The peripheral blood cells were harvested, RNA was extracted, and cDNA was synthesized. The qRT-PCR was performed on 79 cDNA samples taken from 49 CAD⁺ patients and 30 CAD^- patients.

RESULTS

In this study, we observed a significant decrease of ASGR1 expression in the PBMC of CAD⁺ patients compared to the CAD^- patients. We did not identify any considerable differences in the expression of FOXM1 in patients' subgroups with respect to the diabetes and CAD.

CONCLUSION

The results of our study determine the association of ASGR1 expression and CAD pathogenesis. However, we do not know whether this result is the cause or the effect of CAD.

Inhibition of Wnt3a/FOXM1/β-Catenin Axis and Activation of GSK3β and Caspases are Critically Involved in Apoptotic Effect of Moracin D in Breast Cancers

Although Moracin D derived from Morus alba was known to have anti-inflammatory and antioxidant activities, the underlying antitumor mechanism of Moracin D has not been unveiled thus far. Thus, in the recent study, the apoptotic mechanism of Moracin D was elucidated in breast cancer cells. Herein, Moracin D exerted significant cytotoxicity in MDA-MB-231 and MCF-7 cells. Furthermore, Moracin D increased sub G1 population; cleaved poly (Adenosine diphosphate (ADP-ribose)) polymerase (PARP); activated cysteine aspartyl-specific protease 3 (caspase 3); and attenuated the expression of c-Myc, cyclin D1, B-cell lymphoma 2 (Bcl-2), and X-linked inhibitor of apoptosis protein (XIAP) in MDA-MB231 cells. Of note, Moracin D reduced expression of Forkhead box M1 (FOXM1), β-catenin, Wnt3a, and upregulated glycogen synthase kinase 3 beta (GSK3β) on Tyr216 along with disturbed binding of FOXM1 with β-catenin in MDA-MB-231 cells. Conversely, GSK3β inhibitor SB216763 reversed the apoptotic ability of Moracin D to reduce expression of FOXM1, β-catenin, pro-caspase3, and pro-PARP in MDA-MB-231 cells. Overall, these findings provide novel insight that Moracin D inhibits proliferation and induces apoptosis via suppression of Wnt3a/FOXM1/β-catenin signaling and activation of caspases and GSK3β.

FOXM1 is a critical driver of lung fibroblast activation and fibrogenesis

While the transcription factor forkhead box M1 (FOXM1) is well known as a proto-oncogene, its potential role in lung fibroblast activation has never been explored. Here, we show that FOXM1 is more highly expressed in fibrotic than in normal lung fibroblasts in humans and mice. FOXM1 was required not only for cell proliferation in response to mitogens, but also for myofibroblast differentiation and apoptosis resistance elicited by TGF-β. The lipid mediator PGE2, acting via cAMP signaling, was identified as an endogenous negative regulator of FOXM1. Finally, genetic deletion of FOXM1 in fibroblasts or administration of the FOXM1 inhibitor Siomycin A in a therapeutic protocol attenuated bleomycin-induced pulmonary fibrosis. Our results identify FOXM1 as a driver of lung fibroblast activation and underscore the therapeutic potential of targeting FOXM1 for pulmonary fibrosis.

Apoptotic effect of lambertianic acid through AMPK/FOXM1 signaling in MDA-MB231 breast cancer cells

Though lambertianic acid (LA) was known to exert antitumor effect in liver and prostate cancers, its underlying anticancer mechanism is never reported in breast cancers so far. Thus, in this study, apoptotic mechanism of LA was elucidated in MDA-MB-231 breast cancer cells. Here, LA increased cytotoxicity in MCF-7 and MDA-MB-231 cells; enhanced sub-G1 population, G2/M arrest, and cleaved poly(ADP-ribose) polymerase; activated phosphorylation of AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase pathway; and also suppressed phosphorylation of AKT and the expression of forkhead box M1 (FOXM1), X-linked inhibitor of apoptosis protein, B-cell lymphoma 2, and CyclinB1 in MDA-MB-231 cells. Furthermore, AMPK inhibitor compound C reversed the effect of LA on FOXM1, Cyclin B1, and cleaved poly(ADP-ribose) polymerase in MDA-MB-231 cells. Notably, immunoprecipitation revealed that LA disturbed the direct binding of AKT and FOXM1 in MDA-MB-231 cells. Overall, these findings suggest that LA-induced apoptosis is mediated via activation of AMPK and inhibition of AKT/FOXM1 signaling pathway.

ANLN functions as a key candidate gene in cervical cancer as determined by integrated bioinformatic analysis

Background

Cervical cancer, one of the leading causes of female deaths, remains a top cause of mortality in gynecologic oncology and tends to affect younger individuals. However, the pathogenesis of cervical cancer is still far from clear. Given the high incidence and mortality of cervical cancer, uncovering the causes and pathogenesis as well as identifying novel biomarkers are of great significance and are desperately needed.

Materials and methods

First, raw data were downloaded from the Gene Expression Omnibus database. The Robuse Multi-Array Average algorithm and combat function of the sva package were subsequently applied to preprocess and remove batch effects. Differentially expressed genes (DEGs) analyzed with the limma package were followed by gene ontology and pathway analysis, and a protein–protein interaction (PPI) network based on the STRING website and the Cytoscape software was constructed. Weighted Correlation Network Analysis (WGCNA) was utilized to build the coexpression network. Subsequently, UALCAN websites were employed to conduct survival analysis. Finally, the oncomine database was used to validate the expression of ANLN in other datasets.

Results

GSE29570 and GSE89657, including 49 cervical cancer tissues and 20 normal cervical tissues, were screened as the datasets. Three-hundred-twenty-four DEGs were identified and, among them, 123 were upregulated, while 201 were downregulated. The DEGs PPI network complex, contained 305 nodes and 4,962 edges, and 8 clusters were calculated according to k-core =2. Among them, cluster 1, which had 65 nodes and 1,780 edges, had the highest score in these clusters. In coexpression analysis, there were 86 hubgenes from the Brown modules that were chosen for further analysis. Sixty-one key genes were identified as the intersecting genes of the Brown module of WGCNA and DEGs. In survival analysis, only ANLN was a prognostic factor, and the survival was significantly better in the low-expression ANLN group.

Conclusion

Our study suggested that ANLN may be a potential tumor oncogene and could serve as a biomarker for predicting the prognosis of cervical cancer patients.

MELK: a potential novel therapeutic target for TNBC and other aggressive malignancies

INTRODUCTION

There is an unmet need in triple-negative breast cancer (TNBC) patients for targeted therapies. Maternal embryonic leucine zipper kinase (MELK) is a promising target for inhibition based on the abundance of correlative and functional data supporting its role in various cancer types. Areas covered: This review endeavors to outline the role of MELK in cancer. Studies covering a range of biological functions including proliferation, apoptosis, cancer stem cell phenotypes, epithelial-to-mesenchymal transition, metastasis, and therapy resistance are discussed here in order to understand the potential of MELK as a clinically significant target for TNBC patients. Expert opinion: Targeting MELK may offer a novel therapeutic opportunity in TNBC and other cancers. Despite the abundance of correlative data, there is still much we do not know. There are a lack of potent, specific inhibitors against MELK, as well as an insufficient understanding of MELK's downstream substrates. Addressing these issues is the first step toward identifying a patient population that could benefit from MELK inhibition in combination with other therapies.

The FOXM1 inhibitor RCM-1 suppresses goblet cell metaplasia and prevents IL-13 and STAT6 signaling in allergen-exposed mice

Goblet cell metaplasia and excessive mucus secretion associated with asthma, cystic fibrosis, and chronic obstructive pulmonary disease contribute to morbidity and mortality worldwide. We performed a high-throughput screen to identify small molecules targeting a transcriptional network critical for the differentiation of goblet cells in response to allergens. We identified RCM-1, a nontoxic small molecule that inhibited goblet cell metaplasia and excessive mucus production in mice after exposure to allergens. RCM-1 blocked the nuclear localization and increased the proteasomal degradation of Forkhead box M1 (FOXM1), a transcription factor critical for the differentiation of goblet cells from airway progenitor cells. RCM-1 reduced airway resistance, increased lung compliance, and decreased proinflammatory cytokine production in mice exposed to the house dust mite and interleukin-13 (IL-13), which triggers goblet cell metaplasia. In cultured airway epithelial cells and in mice, RCM-1 reduced IL-13 and STAT6 (signal transducer and activator of transcription 6) signaling and prevented the expression of the STAT6 target genes Spdef and Foxa3, which are key transcriptional regulators of goblet cell differentiation. These results suggest that RCM-1 is an inhibitor of goblet cell metaplasia and IL-13 signaling, providing a new therapeutic candidate to treat patients with asthma and other chronic airway diseases.

Lethal and nonlethal murine malarial infections differentially affect apoptosis, proliferation, and CD8 expression on thymic T cells

Although thymic atrophy and apoptosis of the double-positive (DP) T cells have been reported in murine malaria, comparative studies investigating the effect of lethal and nonlethal Plasmodium infections on the thymus are lacking. We assessed the effects of P. yoelii lethal (17XL) and nonlethal (17XNL) infections on thymic T cells. Both strains affected the thymus. 17XL infection induced DP T-cell apoptosis and a selective decrease in surface CD8 expression on developing thymocytes. By contrast, more severe but reversible effects were observed during 17XNL infection. DP T cells underwent apoptosis, and proliferation of both DN and DP cells was affected around peak parasitemia. A transient increase in surface CD8 expression on thymic T cells was also observed. Adult thymic organ culture revealed that soluble serum factors, but not IFN-γ or TNF-α, contributed to the observed effects. Thus, lethal and nonlethal malarial infections led to multiple disparate effects on thymus. These parasite-induced thymic changes are expected to impact the naïve T-cell repertoire and the subsequent control of the immune response against the parasite. Further investigations are required to elucidate the mechanism responsible for these disparate effects, especially the reversible involution of the thymus in case of nonlethal infection.

The Timing of T Cell Priming and Cycling

The proliferation of specific lymphocytes is the central tenet of the clonal selection paradigm. Antigen recognition by T cells triggers a series of events that produces expanded clones of differentiated effector cells. TCR signaling events are detectable within seconds and minutes and are likely to continue for hours and days in vivo. Here, I review the work done on the importance of TCR signals in the later part of the expansion phase of the primary T cell response, primarily regarding the regulation of the cell cycle in CD4(+) and CD8(+) cells. The results suggest a degree of programing by early signals for effector differentiation, particularly in the CD8(+) T cell compartment, with optimal expansion supported by persistent antigen presentation later on. Differences to CD4(+) T cell expansion and new avenues toward a molecular understanding of cell cycle regulation in lymphocytes are discussed.

The transcription factor Foxm1 is essential for the quiescence and maintenance of hematopoietic stem cells

Foxm1, a mammalian Forkhead Box M1 protein, is known as a typical proliferation-associated transcription factor. Here, we find that Foxm1 was essential for maintenance of hematopoietic stem cell (HSC) quiescence and self-renewal capacity in vivo in mice. Reducing expression of FOXM1 also decreased quiescence in human CD34⁺ HSCs and progenitor cells and its down-regulation was associated with a subset of myelodysplastic syndrome (MDS). Mechanistically, Foxm1 directly bound to the promoter region of Nurr1, inducing transcription while forced expression of Nurr1 reversed the loss of quiescence observed in Foxm1-deficient cells in vivo. Thus, our studies reveal a previously unrecognized role of Foxm1 as a critical regulator of HSC quiescence and self-renewal, mediated at least in part, by control of Nurr1 expression.

The Role of Il-12 and Type I Interferon in Governing the Magnitude of CD8 T Cell Responses

Antigen-specific CD8 T cells provide an important protective role in response to infection by viruses, intracellular bacteria, and parasites. Pathogen-specific CD8 T cells render this protection by undergoing robust expansion in numbers while gaining the ability to produce cytokines and cytolytic machinery. Creating optimal CD8 T cell responses to infection can be critical for raising sufficient armament to provide protection against invading intracellular pathogens. Although CD8 T cells have protective value, many vaccine strategies tend to focus on creating productive B cell antibody responses to promote immunological protection. Even though antibody responses can be highly protective, coupling optimal CD8 T cell responses with suboptimal B cell responses could provide higher orders of protection than either one on their own. Therefore, a deeper understanding of the pathways that ultimately guide the magnitude of CD8 T cell responses is required to explore this potential therapeutic benefit. The following chapter highlights our current understanding of how inflammatory cytokines regulate the magnitude of CD8 T cell responses.

Maternal embryonic leucine zipper kinase: key kinase for stem cell phenotype in glioma and other cancers

Maternal embryonic leucine zipper kinase (MELK) is a member of the snf1/AMPK family of protein serine/threonine kinases that has recently gained significant attention in the stem cell and cancer biology field. Recent studies suggest that activation of this kinase is tightly associated with extended survival and accelerated proliferation of cancer stem cells (CSC) in various organs. Overexpression of MELK has been noted in various cancers, including colon, breast, ovaries, pancreas, prostate, and brain, making the inhibition of MELK an attractive therapeutic strategy for a variety of cancers. In the experimental cancer models, depletion of MELK by RNA interference or small molecule inhibitors induces apoptotic cell death of CSCs derived from glioblastoma multiforme and breast cancer, both in vitro and in vivo. Mechanism of action of MELK includes, yet may not be restricted to, direct binding and activation of the oncogenic transcription factors c-JUN and FOXM1 in cancer cells but not in the normal counterparts. Following these preclinical studies, the phase I clinical trial for advanced cancers with OTSSP167 started in 2013, as the first-in-class MELK inhibitor. This review summarizes the current molecular understanding of MELK and the recent preclinical studies about MELK as a cancer therapeutic target.

Maternal embryonic leucine zipper kinase: key kinase for stem cell phenotype in glioma and other cancers

Maternal embryonic leucine zipper kinase (MELK) is a member of the snf1/AMPK family of protein serine/threonine kinases that has recently gained significant attention in the stem cell and cancer biology field. Recent studies suggest that activation of this kinase is tightly associated with extended survival and accelerated proliferation of cancer stem cells (CSC) in various organs. Overexpression of MELK has been noted in various cancers, including colon, breast, ovaries, pancreas, prostate, and brain, making the inhibition of MELK an attractive therapeutic strategy for a variety of cancers. In the experimental cancer models, depletion of MELK by RNA interference or small molecule inhibitors induces apoptotic cell death of CSCs derived from glioblastoma multiforme and breast cancer, both in vitro and in vivo. Mechanism of action of MELK includes, yet may not be restricted to, direct binding and activation of the oncogenic transcription factors c-JUN and FOXM1 in cancer cells but not in the normal counterparts. Following these preclinical studies, the phase I clinical trial for advanced cancers with OTSSP167 started in 2013, as the first-in-class MELK inhibitor. This review summarizes the current molecular understanding of MELK and the recent preclinical studies about MELK as a cancer therapeutic target.

A novel function for Foxm1 in interkinetic nuclear migration in the developing telencephalon and anxiety-related behavior

Interkinetic nuclear migration (INM) is a key feature of cortical neurogenesis. INM functions to maximize the output of the neuroepithelium, and more importantly, balance the self-renewal and differentiation of the progenitors. Although INM has been reported to be highly correlated with the cell cycle, little is known about the effects of cell cycle regulators on INM. In this study, by crossing Foxm1(fl/fl) mice with Emx1-Cre line, we report that a conditional disruption of forkhead transcription factor M1 (Foxm1) in dorsal telencephalon results in abnormal cell cycle progression, leading to impaired INM through the downregulation of Cyclin b1 and Cdc25b. The impairment of INM disturbs the synchronization of apical progenitors (APs) and promotes the transition from APs to basal progenitors (BPs) in a cell-autonomous fashion. Moreover, ablation of Foxm1 causes anxiety-related behaviors in adulthood. Thus, this study provides evidence of linkages among the cell cycle regulator Foxm1, INM, and adult behavior.

IL-12 and type I interferon prolong the division of activated CD8 T cells by maintaining high-affinity IL-2 signaling in vivo

The signal 3 cytokines interleukin-12 and type I interferon sustain CD8 T cell division by prolonging expression of CD25 in vivo.

TCR ligation and co-stimulation induce cellular division; however, optimal accumulation of effector CD8 T cells requires direct inflammatory signaling by signal 3 cytokines, such as IL-12 or type I IFNs. Although in vitro studies suggest that IL-12/type I IFN may enhance T cell survival or early proliferation, the mechanisms underlying optimal accumulation of CD8 T cells in vivo are unknown. In particular, it is unclear if disparate signal 3 cytokines optimize effector CD8 T cell accumulation by the same mechanism and how these inflammatory cytokines, which are transiently produced early after infection, affect T cell accumulation many days later at the peak of the immune response. Here, we show that transient exposure of CD8 T cells to IL-12 or type I IFN does not promote survival or confer an early proliferative advantage in vivo, but rather sustains surface expression of CD25, the high-affinity IL-2 receptor. This prolongs division of CD8 T cells in response to basal IL-2, through activation of the PI3K pathway and expression of FoxM1, a positive regulator of cell cycle progression genes. Thus, signal 3 cytokines use a common pathway to optimize effector CD8 T cell accumulation through a temporally orchestrated sequence of cytokine signals that sustain division rather than survival.

The transcription factor FOXM1 (Forkhead box M1): proliferation-specific expression, transcription factor function, target genes, mouse models, and normal biological roles

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor, which stimulates cell proliferation and exhibits a proliferation-specific expression pattern. Accordingly, both the expression and the transcriptional activity of FOXM1 are increased by proliferation signals, but decreased by antiproliferation signals, including the positive and negative regulation by protooncoproteins or tumor suppressors, respectively. FOXM1 stimulates cell cycle progression by promoting the entry into S-phase and M-phase. Moreover, FOXM1 is required for proper execution of mitosis. Accordingly, FOXM1 regulates the expression of genes, whose products control G1/S-transition, S-phase progression, G2/M-transition, and M-phase progression. Additionally, FOXM1 target genes encode proteins with functions in the execution of DNA replication and mitosis. FOXM1 is a transcriptional activator with a forkhead domain as DNA binding domain and with a very strong acidic transactivation domain. However, wild-type FOXM1 is (almost) inactive because the transactivation domain is repressed by three inhibitory domains. Inactive FOXM1 can be converted into a very potent transactivator by activating signals, which release the transactivation domain from its inhibition by the inhibitory domains. FOXM1 is essential for embryonic development and the foxm1 knockout is embryonically lethal. In adults, FOXM1 is important for tissue repair after injury. FOXM1 prevents premature senescence and interferes with contact inhibition. FOXM1 plays a role for maintenance of stem cell pluripotency and for self-renewal capacity of stem cells. The functions of FOXM1 in prevention of polyploidy and aneuploidy and in homologous recombination repair of DNA-double-strand breaks suggest an importance of FOXM1 for the maintenance of genomic stability and chromosomal integrity.

FoxO1 controls effector-to-memory transition and maintenance of functional CD8 T cell memory

During a T cell response, naive CD8 T cells differentiate into effector cells. Subsequently, a subset of effector cells termed memory precursor effector cells further differentiates into functionally mature memory CD8 T cells. The transcriptional network underlying this carefully scripted process is not well understood. In this study, we report that the transcription factor FoxO1 plays an integral role in facilitating effector-to-memory transition and functional maturation of memory CD4 and CD8 T cells. We find that FoxO1 is not required for differentiation of effector cells, but in the absence of FoxO1, memory CD8 T cells displayed features of senescence and progressive attrition in polyfunctionality, which in turn led to impaired recall responses and poor protective immunity. These data suggest that FoxO1 is essential for maintenance of functional CD8 T cell memory and protective immunity. Under competing conditions in bone marrow chimeric mice, FoxO1 deficiency did not perturb clonal expansion or effector differentiation. Instead, FoxO1-deficient memory precursor effector cells failed to survive and form memory CD8 T cells. Mechanistically, FoxO1 deficiency perturbed the memory CD8 T cell transcriptome, characterized by pronounced alterations in the expression of genes that encode transcription factors (including Tcf7), effector molecules, cell cycle regulators, and proteins that regulate fatty acid, purine, and pyramidine metabolism and mitochondrial functions. We propose that FoxO1 is a key regulator that reprograms and steers the differentiation of effector cells to functionally competent memory cells. These findings have provided fundamental insights into the mechanisms that regulate the quality of CD8 T cell memory to intracellular pathogens.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Postnatal ablation of Foxm1 from cardiomyocytes causes late onset cardiac hypertrophy and fibrosis without exacerbating pressure overload-induced cardiac remodeling

Heart disease remains a leading cause of morbidity and mortality in the industrialized world. Hypertrophic cardiomyopathy is the most common genetic cardiovascular disorder and the most common cause of sudden cardiac death. Foxm1 transcription factor (also known as HFH-11B, Trident, Win or MPP2) plays an important role in the pathogenesis of various cancers and is a critical mediator of post-injury repair in multiple organs. Foxm1 has been previously shown to be essential for heart development and proliferation of embryonic cardiomyocytes. However, the role of Foxm1 in postnatal heart development and in cardiac injury has not been evaluated. To delete Foxm1 in postnatal cardiomyocytes, αMHC-Cre/Foxm1(fl/fl) mice were generated. Surprisingly, αMHC-Cre/Foxm1(fl/fl) mice exhibited normal cardiomyocyte proliferation at postnatal day seven and had no defects in cardiac structure or function but developed cardiac hypertrophy and fibrosis late in life. The development of cardiomyocyte hypertrophy and cardiac fibrosis in aged Foxm1-deficient mice was associated with reduced expression of Hey2, an important regulator of cardiac homeostasis, and increased expression of genes critical for cardiac remodeling, including MMP9, αSMA, fibronectin and vimentin. We also found that following aortic constriction Foxm1 mRNA and protein were induced in cardiomyocytes. However, Foxm1 deletion did not exacerbate cardiac hypertrophy or fibrosis following chronic pressure overload. Our results demonstrate that Foxm1 regulates genes critical for age-induced cardiomyocyte hypertrophy and cardiac fibrosis.

Molecular definition of the identity and activation of natural killer cells

Using whole-genome microarray data sets of the Immunological Genome Project, we demonstrate a closer transcriptional relationship between NK cells and T cells than between any other leukocytes, distinguished by their shared expression of genes encoding molecules with similar signaling functions. Whereas resting NK cells are known to share expression of a few genes with cytotoxic CD8(+) T cells, our transcriptome-wide analysis demonstrates that the commonalities extend to hundreds of genes, many encoding molecules with unknown functions. Resting NK cells demonstrate a 'preprimed' state compared with naive T cells, which allows NK cells to respond more rapidly to viral infection. Collectively, our data provide a global context for known and previously unknown molecular aspects of NK cell identity and function by delineating the genome-wide repertoire of gene expression of NK cells in various states.

Foxm1 mediates cross talk between Kras/mitogen-activated protein kinase and canonical Wnt pathways during development of respiratory epithelium

While Kras/mitogen-activated protein kinase (MAPK) and canonical Wnt/β-catenin are critical for lung morphogenesis, mechanisms integrating these important signaling pathways during lung development are unknown. Herein, we demonstrate that the Foxm1 transcription factor is a key downstream target of activated Kras(G12D). Deletion of Foxm1 from respiratory epithelial cells during lung formation prevented structural abnormalities caused by activated Kras(G12D). Kras/Foxm1 signaling inhibited the activity of canonical Wnt signaling in the developing lung in vivo. Foxm1 decreased T-cell factor (TCF) transcriptional activity induced by activated β-catenin in vitro. Depletion of Foxm1 by short interfering RNA (siRNA) increased nuclear localization of β-catenin, increased expression of β-catenin target genes, and decreased mRNA and protein levels of the β-catenin inhibitor Axin2. Axin2 mRNA was reduced in distal lung epithelium of Foxm1-deficient mice. Foxm1 directly bound to and increased transcriptional activity of the Axin2 promoter region. Foxm1 is required for Kras signaling in distal lung epithelium and provides a mechanism integrating Kras and canonical Wnt/β-catenin signaling during lung development.

Expression of Foxm1 transcription factor in cardiomyocytes is required for myocardial development

Forkhead Box M1 (Foxm1) is a transcription factor essential for organ morphogenesis and development of various cancers. Although complete deletion of Foxm1 in Foxm1(-/-) mice caused embryonic lethality due to severe abnormalities in multiple organ systems, requirements for Foxm1 in cardiomyocytes remain to be determined. This study was designed to elucidate the cardiomyocyte-autonomous role of Foxm1 signaling in heart development. We generated a new mouse model in which Foxm1 was specifically deleted from cardiomyocytes (Nkx2.5-Cre/Foxm1(fl/f) mice). Deletion of Foxm1 from cardiomyocytes was sufficient to disrupt heart morphogenesis and induce embryonic lethality in late gestation. Nkx2.5-Cre/Foxm1(fl/fl) hearts were dilated with thinning of the ventricular walls and interventricular septum, as well as disorganization of the myocardium which culminated in cardiac fibrosis and decreased capillary density. Cardiomyocyte proliferation was diminished in Nkx2.5-Cre/Foxm1(fl/fl) hearts owing to altered expression of multiple cell cycle regulatory genes, such as Cdc25B, Cyclin B(1), Plk-1, nMyc and p21(cip1). In addition, Foxm1 deficient hearts displayed reduced expression of CaMKIIδ, Hey2 and myocardin, which are critical mediators of cardiac function and myocardial growth. Our results indicate that Foxm1 expression in cardiomyocytes is critical for proper heart development and required for cardiomyocyte proliferation and myocardial growth.

Multiple faces of FoxM1 transcription factor: lessons from transgenic mouse models

FoxM1 transcription factor (previously called HFH-11B, Trident, FoxM1b, Win, and MPP2) is expressed in actively dividing cells and critical for cell cycle progression. FoxM1 expression is induced in a variety of tissues during embryogenesis, and Foxm1 (-/-) mice exhibit embryonic lethal phenotype due to multiple abnormalities in the liver, heart, lung and blood vessels. FoxM1 levels are dramatically decreased in adult tissues, but FoxM1 expression is re-activated during organ injury and numerous cancers. In this review, we discussed the role of FoxM1 in different cell lineages using recent data from transgenic mouse models with conditional "gain-of-function" and "loss-of-function" of FoxM1, as well as tissue samples from human patients. In addition, we provided experimental data showing additional sites of FoxM1 expression in the mouse embryo. Novel cell-autonomous roles of FoxM1 in embryonic development, organ injury and cancer formation in vivo were analyzed. Potential application of these findings for the diagnosis and treatment of human diseases were discussed.