Factor Forkhead Box Protein M1 Research Articles

Identification of signalling downstream of the transcription factor forkhead box protein M1 that protects against endoplasmic reticulum stress in a diabetic foot ulcer model.

Diabetic foot ulcer (DFU) has a significant impact on the quality of life of diabetic mellitus (DM) patients. Here, we aimed to explore the molecules with aberrant expression and their regulatory mechanisms in DFU. The expression of gene and protein was examined using quantitative polymerase chain reaction (qPCR) and western blot. Pearson's correlation analysis was used to analyse interactions among FOXM1, GAS5 and SDF4. Immunofluorescence was used to detect PDI and GRP78 expression. Flow cytometry was used to assess cell apoptosis. Tube formation assay was used to determine angiogenic capacity. Fluorescence in situ hybridization (FISH) assay was employed to determine the cellular localization of GAS5 and SDF4 in human umbilical vein endothelial cells (HUVECs). The interactions among FOXM1, GAS5 and SDF4 were validated by chromatin immunoprecipitation (ChIP), luciferase, RNA pull-down and RNA immunoprecipitation (RIP) assays. FOXM1, GAS5 and SDF4 were decreased in the skin tissues of DFU patients. High glucose (HG) stimulation induced endoplasmic reticulum (ER) stress and cell apoptosis but suppressed angiogenesis in HUVECs, which were abolished by FOXM1 overexpression. FOXM1 promoted GAS5 transcriptional activity, resulting in increased GAS5 expression, and GAS5 knockdown reversed the effects of FOXM1 overexpression in HG-treated HUVECs. Moreover, GAS5 recruited TAF15 to promote SDF4 expression in HUVECs. GAS5 overexpression inhibited ER stress, cell apoptosis and induced angiogenesis in HG-treated HUVECs which could be reversed by silencing SDF4. Our results revealed that FOXM1 suppressed ER stress, cell apoptosis and promoted angiogenesis in HG-induced HUVECs via mediating GAS5/TAF15/SDF4 axis, providing a novel therapeutic molecule mechanism for DFU.

The role of branched-chain aminotransferase 1 in driving glioblastoma cell proliferation and invasion varies with tumor subtype.

Branched-chain aminotransferase 1 (BCAT1) has been proposed to drive proliferation and invasion of isocitrate dehydrogenase (IDH) wild-type glioblastoma cells. However, the Cancer Genome Atlas (TCGA) dataset shows considerable variation in the expression of this enzyme in glioblastoma. The aim of this study was to determine the role of BCAT1 in driving the proliferation and invasion of glioblastoma cells and xenografts that have widely differing levels of BCAT1 expression and the mechanism responsible. The activity of BCAT1 was modulated in IDH wild-type patient-derived glioblastoma cell lines, and in orthotopically implanted tumors derived from these cells, to examine the effects of BCAT1 expression on tumor phenotype. In cells with constitutively high BCAT1 expression and a glycolytic metabolic phenotype, inducible shRNA knockdown of the enzyme resulted in reduced proliferation and invasion by increasing the concentration of α-ketoglutarate, leading to reduced DNA methylation, HIF-1α destabilization, and reduced expression of the transcription factor Forkhead box protein M1 (FOXM1). Conversely, overexpression of the enzyme increased HIF-1α expression and promoted proliferation and invasion. However, in cells with an oxidative phenotype and very low constitutive expression of BCAT1 increased expression of the enzyme had no effect on invasion and reduced cell proliferation. This occurred despite an increase in HIF-1α levels and could be explained by decreased TCA cycle flux. There is a wide variation in BCAT1 expression in glioblastoma and its role in proliferation and invasion is dependent on tumor subtype.

Glucose-Dependent FOXM1 Promotes Epithelial-to-Mesenchymal Transition Via Cellular Metabolism and Targeting Snail in Human Pancreatic Cancer.

Transcription factor Forkhead box protein M1 (FOXM1) plays critical roles in the progression of cancer including epithelial-to-mesenchymal transition (EMT). The aim of this study is to characterize the regulatory mechanisms of FOXM1 in EMT via pancreatic cancer metabolism. We investigated the regulation of EMT via mitochondrial respiration by FOXM1 using pancreatic cancer cell lines HPAC and PANC-1 and normal human pancreatic duct epithelial cells. Forkhead box protein M1 and Snail were strongly expressed in HPAC and PANC-1. Epithelial-to-mesenchymal transition-modulated claudin-1 level was lower in PANC-1 than in HPAC. In both cell lines in low-glucose medium, FOXM1 and Snail were decreased and claudin-1 was increased. Knockdown of FOXM1 increased claudin-1 and decreased Snail in both cell lines. Low-glucose medium and downregulation of FOXM1 inhibited the cell migration in both cell lines. In both cell lines, mitochondrial respiration was at higher levels in low-glucose medium than in high-glucose medium. Downregulation of FOXM1 induced mitochondrial respiration in high-glucose medium. In normal human pancreatic duct epithelial cells, FOXM1 and Snail were low and claudin-1 was highly expressed, whereas overexpression of FOXM1 decreased claudin-1. Glucose-dependent FOXM1 promoted EMT via Snail and pancreatic cancer metabolism.

HDAC inhibitors and cardioprotection: Homing in on a mechanism of action.

HDAC inhibitors and cardioprotection: Homing in on a mechanism of action.

FOXM1 promotes proliferation in human hepatocellular carcinoma cells by transcriptional activation of CCNB1

The transcription factor Forkhead box protein M1 (FOXM1) plays critical roles in cancer development and progression, including human hepatocellular carcinoma (HCC). However, the regulatory role and underlying mechanisms of FOXM1 is still limited. Here, we found that the high level expression of FOXM1 and CCNB1 is closely associated with poor prognosis in HCC patients. And FOXM1 and CCNB1 were overexpressed concomitantly in liver tumor tissues. Knockdown of FOXM1 significantly inhibited the expression levels of CCNB1 in HCC cell lines at both the mRNA and protein levels. Mechanistic studies revealed that FOXM1 binds directly to the promoter region of CCNB1 and regulates the expression levels of the CCNB1 gene in the transcriptional level. Furthermore, the loss of functional and rescue experiments showed that CCNB1 is essential for FOXM1-driven proliferation in HCC cells. In the present study, our results partially explained the dysregulated expression of FOXM1 play an important role in proliferation of human hepatocellular carcinoma cells via transcriptional activation of CCNB1 expression. And it also highlights a FOXM1/CCNB1 axis could be a potential target for the treatment of HCCs.

Proteasome inhibitor bortezomib enhances the effect of standard chemotherapy in small cell lung cancer.

Small cell lung cancer (SCLC) is an aggressive cancer showing a very poor prognosis because of metastasis formation at an early stage and acquisition of chemoresistance. One key driver of chemoresistance is the transcription factor Forkhead box protein M1 (FOXM1) that regulates cell cycle proliferation, maintenance of genomic stability, DNA damage response, and cell differentiation in numerous tumor entities. In this study we investigated the role of FOXM1 in SCLC progression and analyzed the effect of FOXM1 inhibition using two proteasome inhibitors, bortezomib and siomycin A. FOXM1 was strongly expressed in patient-derived SCLC samples (n=123) and its nuclear localization was associated with the proliferation marker Ki-67. Both proteasome inhibitors successfully inhibited FOXM1 expression leading to a significantly reduced proliferation and a decreased mitotic rate along with cell cycle arrest and apoptosis induction. These effects were further enhanced by addition of bortezomib to standard chemotherapy. Treatment of mice bearing chemoresistant SCLC xenografts with bortezomib reduced the mean bioluminescence signal of tumors by 54%. Similarly, treatment with cisplatin as a standard chemotherapy reduced the mean bioluminescence signal of tumors by 58%. However, in combination with standard chemotherapy bortezomib further reduced the mean bioluminescence signal by 93% (p=0.0258). In conclusion, we demonstrate the effect of bortezomib in inhibiting FOXM1 expression and thus in sensitizing resistant SCLC cells to standard chemotherapy. Thus, addition of bortezomib to standard chemotherapy might potently improve SCLC therapy, particularly in an extensive cancer stage.

FOXM1 confers resistance to gefitinib in lung adenocarcinoma via a MET/AKT-dependent positive feedback loop.

Gefitinib resistance remains a major problem in the treatment of lung adenocarcinoma. However, the molecular mechanisms of gefitinib resistance are not fully understood. In this study, we characterized the critical role of transcription factor Forkhead box protein M1 (FOXM1) in gefitinib resistance of lung adenocarcinoma cells. In vitro drug sensitivity assays demonstrated that FOXM1 inhibition sensitized PC9/GR and HCC827/GR cells to gefitinib, whereas FOXM1 overexpression enhanced PC9 and HCC827 cell resistance to gefitinib. Increased FOXM1 resulted in the upregulation of hepatocyte growth factor receptor (MET), which led to activation of the protein kinase B (AKT) pathway, whereas knockdown of FOXM1 did the opposite. FOXM1 bound directly to the MET promoter regions and regulated the promoter activities and the expression of MET at the transcriptional level. Moreover, MET/AKT pathway upregulated the expression of FOXM1 in lung adenocarcinoma cells. Inhibition of pAKT by LY294002 or inhibition of pMET by PHA-665752 significantly inhibited the expression of FOXM1 in lung adenocarcinoma cells. Importantly, we further demonstrated that the expression levels of FOXM1, pAKT and MET were significantly increased in lung adenocarcinoma tissues relative to normal lung tissues, and these three biomarkers were concomitantly overexpressed in lung adenocarcinoma tissues. Taken together, our results indicate that FOXM1 promotes acquired resistance to gefitinib of lung adenocarcinoma cells, and FOXM1 crosstalks with MET/AKT signaling to form a positive feedback loop to promote lung adenocarcinoma development.

Abstract 1563: Interplay between perlecan/HSPG2 and matrilysin/MMP-7 in the prostate cancer tumor microenvironment directs metastatic programming through focal adhesion kinase and FoxM1

Abstract Prostate cancer (PCa) cells interact with the stroma and extracellular matrix (ECM) during tumor expansion and invasion during metastasis. Dissecting the complex matrix-cancer interplay is essential to halting tumor progression. A vital component of the ECM is perlecan/heparan sulfate proteoglycan 2 (HSPG2). As a large extracellular proteoglycan, perlecan helps orchestrate tumor angiogenesis, proliferation, differentiation and invasion. Actively metastasizing cancer cells must proteolytically degrade several tissue borders which perlecan patrols, including the basement membrane, vasculature, reactive stromal matrix and bone marrow. We have demonstrated that perlecan, even fully decorated with glycosaminoglycan chains and in the context of the basement membrane, is cleaved efficiently by the protease matrilysin/matrix metalloproteinase 7 (MMP-7). MMP-7 levels increase, especially in relation to its endogenous inhibitor, during metastatic programming in several cancers including PCa. Recent analysis of a tissue microarray of 157 prostatectomy patients showed perlecan and MMP-7 are increased in tandem, with perlecan disappearing at the sites where MMP-7 is high, indicative of a protease-substrate relationship in tissue. This idea is supported by the finding that perlecan fragments are present in serum of PCa patients, with a majority from domain IV. Additionally, higher perlecan staining in cancer related stroma positively correlated with higher grade cancer. Investigating the effects of perlecan on metastatic PCa cells showed full length perlecan and specifically domain IV of perlecan triggers clustering of PCa cells. Perlecan proteolysis by MMP-7 reverses this, favoring cell dispersion and tumor dyscohesion. To discover the molecular signaling events associated with perlecan binding to PCa cells, a reverse phase protein array was analyzed for protein interactions that were plotted in Cytoscape. Network analysis revealed, and western blotting confirmed, perlecan and MMP-7 mediated proteolysis altered focal adhesion kinase (FAK) signaling, with intact perlecan and domain IV suppressing FAK activity during clustering, and MMP-7 cleaved perlecan activating FAK, consistent with the induction of dispersion. Further work showed that cleavage of perlecan increased the pro-cancer transcription factor forkhead box protein M1 (FOXM1). This work reveals that degradation of perlecan by MMP-7 in the tumor microenvironment can unlock stable epithelial contacts and reprogram PCa cells for invasion and metastasis through processes involving FAK and FoxM1. Citation Format: Brian J. Grindel, Jerahme Martinez, Hamim Zafar, Luay K. Nakhleh, Leland W.K. Chung, Mary C. Farach-Carson. Interplay between perlecan/HSPG2 and matrilysin/MMP-7 in the prostate cancer tumor microenvironment directs metastatic programming through focal adhesion kinase and FoxM1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1563.

FOXM1 promotes reprogramming of glucose metabolism in epithelial ovarian cancer cells via activation of GLUT1 and HK2 transcription.

Cancer cells exhibit the reprogrammed metabolism mainly via aerobic glycolysis, a phenomenon known historically as the Warburg effect; however, the underlying mechanisms remain largely unknown. In this study, we characterized the critical role of transcription factor Forkhead box protein M1 (FOXM1) in aerobic glycolysis of human epithelial ovarian cancer (EOC) and its molecular mechanisms. Our data showed that aberrant expression of FOXM1 significantly contributed to the reprogramming of glucose metabolism in EOC cells. Aerobic glycolysis and cell proliferation were down-regulated in EOC cells when FOXM1 gene expression was suppressed by RNA interference. Moreover, knockdown of FOXM1 in EOC cells significantly reduced glucose transporter 1 (GLUT1) and hexokinase 2 (HK2) expression. FOXM1 bound directly to the GLUT1 and HK2 promoter regions and regulated the promoter activities and the expression of the genes at the transcriptional level. This reveals a novel mechanism by which glucose metabolism is regulated by FOXM1. Importantly, we further demonstrated that the expression levels of FOXM1, GLUT1 and HK2 were significantly increased in human EOC tissues relative to normal ovarian tissues, and that FOXM1 expression was positively correlated with GLUT1 and HK2 expression. Taken together, our results show that FOXM1 promotes reprogramming of glucose metabolism in EOC cells via activation of GLUT1 and HK2 transcription, suggesting that FOXM1 may be an important target in aerobic glycolysis pathway for developing novel anticancer agents.

SUMO-specific protease 6 promotes gastric cancer cell growth via deSUMOylation of FoxM1.

SUMOylation is a post-translational modification exerted various effects on the target proteins. SUMOylation is a highly dynamic and reversible process, which has been shown to play an important role in tumorigenesis. However, the roles of sentrin/SUMO-specific proteases (SENPs), which mediate the reverse process of SUMOylation, in tumorigenesis remains largely unexplored. Here, we uncover a critical role of SENP6 in promoting gastric cancer cells growth via regulating the deSUMOylation of a transcription factor forkhead box protein M1 (FoxM1). We demonstrated that the mRNA and protein levels were elevated in gastric cancer tissues. Overexpression of SENP6 promoted, while RNA interference depletion of endogenous SENP6 inhibited gastric cancer cells growth and the ability of colony formation. By using biochemical assays, we identified FoxM1 as a novel substrate of SENP6 in gastric cancer cells. Thus, our data suggest that SENP6, which is highly expressed in gastric cancer cells, regulates the transcriptional activity and stability of FoxM1 through deSUMOylation.

SUMOylation of FOXM1B alters its transcriptional activity on regulation of MiR-200 family and JNK1 in MCF7 human breast cancer cells.

Transcription factor Forkhead Box Protein M1 (FOXM1) is a well-known master regulator in controlling cell-cycle pathways essential for DNA replication and mitosis, as well as cell proliferation. Among the three major isoforms of FOXM1, FOXM1B is highly associated with tumor growth and metastasis. The activities of FOXM1B are modulated by post-translational modifications (PTMs), such as phosphorylation, but whether it is modified by small ubiquitin-related modifier (SUMO) remains unknown. The aim of the current study was to determine whether FOXM1B is post-translationally modified by SUMO proteins and also to identify SUMOylation of FOXM1B on its target gene transcription activity. Here we report that FOXM1B is clearly defined as a SUMO target protein at the cellular levels. Moreover, a SUMOylation protease, SENP2, significantly decreased SUMOylation of FOXM1B. Notably, FOXM1B is selectively SUMOylated at lysine residue 463. While SUMOylation of FOXM1B is required for full repression of its target genes MiR-200b/c and p21, SUMOylation of FOXM1B is essential for full activation of JNK1 gene. Overall, we provide evidence that FOXM1B is post-translationally modified by SUMO and SUMOylation of FOXM1B plays a functional role in regulation of its target gene activities.

FOXM1 Promotes the Warburg Effect and Pancreatic Cancer Progression via Transactivation of LDHA Expression

The transcription factor Forkhead box protein M1 (FOXM1) plays critical roles in cancer development and progression. However, the regulatory role and underlying mechanisms of FOXM1 in cancer metabolism are unknown. In this study, we characterized the regulation of aerobic glycolysis by FOXM1 and its impact on pancreatic cancer metabolism. The effect of altered expression of FOXM1 on expression of glycolytic enzymes and tumor development and progression was examined using animal models of pancreatic cancer. Also, the underlying mechanisms of altered pancreatic cancer glycolysis were analyzed using in vitro molecular biology. The clinical relevance of aberrant metabolism caused by dysregulated FOXM1 signaling was determined using pancreatic tumor and normal pancreatic tissue specimens. We found that FOXM1 did not markedly change the expression of most glycolytic enzymes except for phosphoglycerate kinase 1 (PGK-1) and lactate dehydrogenase A (LDHA). FOXM1 and LDHA were overexpressed concomitantly in pancreatic tumors and cancer cell lines. Increased expression of FOXM1 upregulated the expression of LDHA at both the mRNA and protein level and elevated LDH activity, lactate production, and glucose utilization, whereas reduced expression of FOXM1 did the opposite. Further studies demonstrated that FOXM1 bound directly to the LDHA promoter region and regulated the expression of the LDHA gene at the transcriptional level. Also, elevated FOXM1-LDHA signaling increased the pancreatic cancer cell growth and metastasis. Dysregulated expression and activation of FOXM1 play important roles in aerobic glycolysis and tumorigenesis in patients with pancreatic cancer via transcriptional regulation of LDHA expression.

FOXM1 mediates resistance to docetaxel in gastric cancer via up‐regulating Stathmin

Docetaxel is commonly used as an effective chemotherapeutic drug for gastric cancer patients recently. With the increasing emergence of docetaxel resistance nowadays, identification of suitable biomarkers for predicting chemosensitivity to docetaxel may be a key role for improving therapeutic effects for gastric cancer patients. In this study, we investigated the correlation between the expression of transcription factor forkhead box protein M1 (FOXM1) and chemotherapy response to docetaxel in gastric cancer, the possible mechanism for which was further explored. As a result, FOXM1 overexpression was shown to mediate resistance to docetaxel in gastric cancers. It altered microtubule dynamics to protect tumour cells from docetaxel-induced apoptosis. Mechanistic investigations revealed that tubulin-destabilizing protein Stathmin, which mediated docetaxel resistance in FOXM1-silenced gastric cancer cells, is a direct down-stream target of FOXM1, whereas another microtubule dynamics protein mitotic centromere–associated kinesin (MCAK), shown to be related to docetaxel resistance in gastric cancer cells, is not associated with FOXM1 expression significantly. These results were further provided by immunohistochemical analysis, indicating that FOXM1 and Stathmin expression levels were correlated in 103 post-operational gastric cancer specimens. Moreover, when we attenuated FOXM1 expression with FOXM1 inhibitor thiostrepton, docetaxel resistance in gastric cancers was found to be reversed, simultaneously with the down-regulation of FOXM1 and Stathmin. Therefore, FOXM1 can be a useful marker for predicting and monitoring docetaxel response. Through the inhibition of FOXM1, docetaxel resistance can be reversed, and thus FOXM1 could be a new therapeutic target in docetaxel-resistant gastric cancer.

Casticin induces breast cancer cell apoptosis by inhibiting the expression of forkhead box protein M1.

Casticin is an active ingredient derived from Fructus Viticis, a traditional Chinese medicine. This study aimed to investigate the role of forkhead box O3 (FOXO3a) in breast cancer cells and examine the regulatory mechanisms of FOXO3a in response to casticin treatment of the cells by ELISA, flow cytometry, small interfering RNA (siRNA) transfection and western blot analysis. Casticin treatment induced apoptosis and reduced the expression of the transcription factor forkhead box protein M1 (FOXM1). In addition, FOXM1 repression induced by casticin treatment was associated with the activation of FOXO3a via increased dephosphorylation. Notably, silencing FOXO3a expression by siRNA-mediated gene knockdown attenuated casticin-mediated apoptosis. Collectively, these findings suggest that FOXO3a is a critical mediator of the inhibitory effects of casticin on apoptosis in breast cancer cells.

The roles of FOXM1 in pancreatic stem cells and carcinogenesis

Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognoses among all cancers. Over the past several decades, investigators have made great advances in the research of PDAC pathogenesis. Importantly, identification of pancreatic cancer stem cells (PCSCs) in pancreatic cancer cases has increased our understanding of PDAC biology and therapy. PCSCs are responsible for pancreatic tumorigenesis and tumor progression via a number of mechanisms, including extensive proliferation, self-renewal, high tumorigenic ability, high propensity for invasiveness and metastasis, and resistance to conventional treatment. Furthermore, emerging evidence suggests that PCSCs are involved in the malignant transformation of pancreatic intraepithelial neoplasia. The molecular mechanisms that control PCSCs are related to alterations of various signaling pathways, for instance, Hedgehog, Notch, Wnt, B-cell-specific Moloney murine leukemia virus insertion site 1, phosphoinositide 3-kinase/AKT, and Nodal/Activin. Also, authors have reported that the proliferation-specific transcriptional factor Forkhead box protein M1 is involved in PCSC self-renewal and proliferation. In this review, we describe the current knowledge about the signaling pathways related to PCSCs and the early stages of PDAC development, highlighting the pivotal roles of Forkhead box protein M1 in PCSCs and their impacts on the development and progression of pancreatic intraepithelial neoplasia.

Clinical significance and positive correlation of FoxM1 and Her-2 expression in gastric cancer

The transcription factor forkhead box protein M1 (FoxM1) and tyrosine kinase receptor Her-2, aberrantly expressing in various kinds of human malignancies, are closely related to the development of cancer. However, the correlation of them is still little explored, especially in gastric cancer. In current study, we examined FoxM1 and Her-2 levels in gastric cancers, and the clinical significance and association of them were further explored. As a result, FoxM1 and Her-2 expression were significantly higher in gastric cancer compared with para-cancer tissues and gastric cell lines (P < 0.01), while a positive association was found between the two genes at both RNA and protein levels (P = 0.007, P = 0.025). No significant association was observed between FoxM1 expression and clinic-pathological parameters (P > 0.1), whereas the positive frequency of Her-2 correlated with TNM stage significantly (P = 0.045). In addition, multivariate analysis showed Her-2 was not a prognostic predictor in gastric cancer (P = 0.625), while FoxM1 was independently associated with prognosis (P = 0.001), which especially affected the survival in patients with advanced stage (P < 0.01). These results suggest that FoxM1 and Her-2 are important diagnostic markers for gastric cancer, and FoxM1 is a favorable prognostic indicator in gastric cancer. FoxM1 may be a potential cellular target for therapeutic intervention, especially in Her2-targeted therapy-resistant cancers.

Signaling of MiRNAs-FOXM1 in Cancer and Potential Targeted Therapy

The transcription factor Forkhead box protein M1 (FOXM1) is overexpressed in the majority of cancer patients. This overexpression is implicated to play a role in the pathogenesis, progression, and metastasis of cancer. This important role of FOXM1 demonstrates its significance to cancer therapy. MicroRNAs (miRNAs) are small noncoding, endogenous, single-stranded RNAs that are pivotal posttranscriptional gene expression regulators. MiRNAs aberrantly expressed in cancer cells have important roles in tumorigenesis and progression. Currently, miRNAs are being studied as diagnostic and prognostic biomarkers and therapeutic tools for cancer. The rapid discovery of many target miRNAs and their relevant pathways has contributed to the development of miRNA-based therapeutics for cancer. In this review, we summarize the latest and most significant findings on FOXM1 and miRNA involvement in cancer development and describe the role/roles of miRNA/FOXM1 signaling pathways in cancer initiation and progression. Targeting FOXM1 via regulation of miRNA expression may have a role in cancer treatment, although the miRNA delivery method remains the key challenge to the establishment of this novel therapy.