Forkhead box M1B is a determinant of rat susceptibility to hepatocarcinogenesis and sustains ERK activity in human HCC

Research progress of the Otubains subfamily in hepatocellular carcinoma

In cancer research, oncogenesis can be affected by modulating the deubiquitination pathway. Ubiquitination regulates proteins post-translationally in variety of physiological processes. The Otubain Subfamily includes OTUB1 (ovarian tumor-associated proteinase B1) and OTUB2(ovarian tumor-associated proteinase B2). They are deubiquitinating enzymes, which are research hotspots in tumor immunotherapy, with their implications extending across the spectrum of tumor development. Understanding their important role in tumorigenesis, includ-ing hepatocellular carcinoma (HCC) is crucial. HCC has alarming global incidence rates and mortality statistics, ranking among the top five prevalent cancers in Malaysia1. Numerous studies have consistently indicated significant expression of OTUB1 and OTUB2 in HCC cells. In addition, OTUB1 has important biological functions in cancer, suggesting its important role in tumorigenesis. However, the mechanism underlying the action of OTUB1 and OTUB2 in liver cancer remains inadequately explored. Therefore, Otubain Subfamily, as potential molecular target, holds promise for advancing HCC treatments. However, further clinical studies are required to verify its efficacy and application prospects.

Invasive FoxM1 phosphorylated by PLK1 induces the polarization of tumor-associated macrophages to promote immune escape and metastasis, amplified by IFITM1

BACKGROUND

Understanding the mechanism behind immune cell plasticity in cancer metastasis is crucial for identifying key regulators. Previously we found that mitotic factors regulate epithelial-mesenchymal transition, but how these factors convert to metastatic players in the tumor microenvironment (TME) is not fully understood.

METHODS

The clinical importance of mitotic factors was analyzed by heatmap analysis, a KM plot, and immunohistochemistry in lung adenocarcinoma (LUAD) patients. Immunoprecipitation, LC-MS/MS, kinase assay, and site-directed mutagenesis were performed for the interaction and phosphorylation. A tail-vein injection mouse model, Transwell-based 3D culture, microarray analysis, coculture with monocytes, and chromatin immunoprecipitation assays were used to elucidate the function of phosphorylated FoxM1 in metastasis of TME.

RESULTS

The phosphorylated FoxM1 at Ser25 by PLK1 acquires the reprogramming ability to stimulate the invasive traits in cancer and influence immune cell plasticity. This invasive form of p-FoxM1 upregulates the expression of IL1A/1B, VEGFA, and IL6 by direct activation, recruiting monocytes and promoting the polarization of M2d-like tumor-associated macrophages (TAMs). Upregulation of PD-L1 in LUAD having phosphomimetic FoxM1 facilitates immune evasion. In invasive LUAD with phosphomimetic FoxM1, IFITM1 is the most highly expressed through the activation of the STING-TBK1-IRF3 signaling, which enhances FoxM1-mediated signaling. Clinically, higher expression of FOXM1, PLK1, and IFITM1 is inversely correlated with the survival rate of advanced LUAD patients, providing a promising therapeutic strategy for the treatment of LUAD.

CONCLUSION

FoxM1-based therapy would be a potential therapeutic strategy for LUAD to reduce TAM polarization, immune escape, and metastasis, since FoxM1 functions as a genetic reprogramming factor reinforcing LUAD malignancy in the TME.

Crosstalk of RNA methylation writers defines tumor microenvironment and alisertib resistance in breast cancer

Background

The five major RNA methylation modifications (m6A, m1A, m6Am, m5C, and m7G) exert biological roles in tumorigenicity and immune response, mediated mainly by "writer" enzymes. Here, the prognostic values of the "writer" enzymes and the TCP1 role in drug resistance in breast cancer (BC) were explored for further therapeutic strategies.

Methods

We comprehensively characterized clinical, molecular, and genetic features of subtypes by consensus clustering. RNA methylation modification "Writers" and related genes_risk (RMW_risk) model for BC was constructed via a machine learning approach. Moreover, we performed a systematical analysis for characteristics of the tumor microenvironment (TME), alisertib sensitivity, and immunotherapy response. A series of experiments in vitro were carried out to assess the association of TCP1 with drug resistance.

Results

One "writer" (RBM15B) and two related genes (TCP1 and ANKRD36) were identified for prognostic model construction, validated by GSE1456, GSE7390, and GSE20685 cohorts and our follow-up data. Based on the patterns of the genes related to prognosis, patients were classified into RMW_risk-high and RMW_risk-low subtypes. Lower RMW_Score was associated with better overall survival and the infiltration of immune cells such as memory B cells. Further analysis revealed that RMW_Score presented potential values in predicting drug sensitivity and response for chemo- and immunotherapy. In addition, TCP1 was confirmed to promote BC alisertib-resistant cell proliferation and migration in vitro.

Conclusion

RMW_Score could function as a robust biomarker for predicting BC patient survival and therapeutic benefits. This research revealed a potential TCP1 role regarding alisertib resistance in BC, providing new sights into more effective therapeutic plans.

An in silico toxicogenomic approach in constructing the aflatoxin B1-mediated regulatory network of hub genes in hepatocellular carcinoma

Aflatoxin B1 (AFB1) can cause hepatocellular carcinoma (HCC) through a mutagenic mode of action but can also lead to global changes in gene expression; however, the AFB1 network of molecular pathways involved in HCC is not known. Here, we used toxicogenomic data from human liver cells exposed to AFB1 to infer the network of AFB1-responsive molecular pathways involved in HCC. The following computational tools: STRING, MCODE, cytoHubba, iRegulon, kinase enrichment tool KEA3, and DAVID were used to identify protein-protein interaction network, hub genes, transcription factors (TFs), upstream kinases, and biological processes (BPs). Predicted molecular events were validated with an external dataset, whereas the hub genes in HCC were validated using the UALCAN database. The results revealed an association between AFB1 and the hub genes involved in the cell cycle. We identified TFs that regulate the hub genes and linked them with upstream kinases including cyclin-dependent kinases, mitogen-activated protein kinase 1, and AKT. This approach enabled the construction of the AFB1-mediated regulatory network consisting of upstream kinases, TFs, hub genes, and BPs, thus revealing the signaling hierarchy and information flow that may contribute to AFB1-induced HCC. This could be a useful tool in predicting the molecular mechanisms involved in chemical-induced diseases when available toxicogenomic data exist.

Genetic Predisposition to Hepatocellular Carcinoma

Liver preneoplastic and neoplastic lesions of the genetically susceptible F344 and resistant BN rats cluster, respectively, with human HCC with better (HCCB) and poorer prognosis (HCCP); therefore, they represent a valid model to study the molecular alterations determining the genetic predisposition to HCC and the response to therapy. The ubiquitin-mediated proteolysis of ERK-inhibitor DUSP1, which characterizes HCC progression, favors the unrestrained ERK activity. DUSP1 represents a valuable prognostic marker, and ERK, CKS1, or SKP2 are potential therapeutic targets for human HCC. In DN (dysplastic nodule) and HCC of F344 rats and human HCCP, DUSP1 downregulation and ERK1/2 overexpression sustain SKP2-CKS1 activity through FOXM1, the expression of which is associated with a susceptible phenotype. SAM-methyl-transferase reactions and SAM/SAH ratio are regulated by GNMT. In addition, GNMT binds to CYP1A, PARP1, and NFKB and PREX2 gene promoters. MYBL2 upregulation deregulates cell cycle and induces the progression of premalignant and malignant liver. During HCC progression, the MYBL2 transcription factor positively correlates with cells proliferation and microvessel density, while it is negatively correlated to apoptosis. Hierarchical supervised analysis, regarding 6132 genes common to human and rat liver, showed a gene expression pattern common to normal liver of both strains and BN nodules, and a second pattern is observed in F344 nodules and HCC of both strains. Comparative genetics studies showed that DNs of BN rats cluster with human HCCB, while F344 DNs and HCCs cluster with HCCP.

Effects of thiostrepton alone or in combination with selumetinib on triple-negative breast cancer metastasis

OBJECTIVE

FoxM1 transcription factor contributes to tumor metastasis and poor prognosis in many cancers including triple-negative breast cancer (TNBC). In this study, we examined the effects of FoxM1 inhibitor Thiostrepton (THIO) alone or in combination with MEK inhibitor Selumetinib (SEL) on metastatic parameters in vitro and in vivo.

METHODS

Cell viability was determined by MTT assay. Immunoblotting and immunohistochemistry was used to assess metastasis-related protein expressions in 4T1 cells and its allograft tumor model in BALB/c mice. In vivo uPA activity was determined by enzymatic methods.

RESULTS

Both inhibitors were effective on the expressions of FoxM1, ERK, p-ERK, Twist, E-cadherin, and Vimentin alone or in combination in vitro. THIO significantly decreased 4T1 cell migration and changed the cell morphology from mesenchymal-like to epithelial-like structure. THIO was more effective than in combination with SEL in terms of metastatic protein expressions in vivo. THIO alone significantly inhibited mean tumor growth, decreased lung metastasis rate and tumor foci, however, no significant changes in these parameters were observed in the combined group. Immunohistochemically, FoxM1 expression intensity was decreased with THIO and its combination with SEL in the tumors.

CONCLUSIONS

This study suggests that inhibiting FoxM1 as a single target is more effective than combined treatment with MEK in theTNBC allograft model. The therapeutic efficacy of THIO should be investigated with further studies on appropriate drug delivery systems.

FOXM1-induced TYMS upregulation promotes the progression of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the major causes of cancer-related death. Thymidylate synthase (TYMS) catalyzes the methylation of deoxy guanosine to deoxy thymidylate, which is a crucial gene for DNA repair and replication. Thus, TYMS was reported to be closely associated with developing a variety of tumors, but it has been poorly studied in HCC.

Materials and methods

We used the cell counting kit-8 (CCK-8), BrdU, and CFSE assay to measure cell proliferation. The flow cytometry assay and the TUNEL assay were used for assessing cell apoptosis. The flow cytometry assay was used to analyze the cell cycle. The Transwell invasion assay and the wound healing assay were conducted to determine the invasive ability of the cells. RT-qPCR and Western blot analyses were performed to evaluate the mRNA and protein expression levels of specific genes, respectively.

Results

TYMS was found to be upregulated in both HCC cells and patient samples. High expression of TYMS was associated with an unfavorable prognosis in HCC patients based on the TCGA-LIHC dataset. Cell proliferation, apoptosis, and invasion assays revealed that TYMS promoted the proliferation and invasion of HCC cells as well as inhibited apoptosis. In addition, TYMS is a downstream target of FOXM1. TYMS knockdown reversed the 5-FU resistance caused by FOXM1 overexpression and re-sensitized HCC cells to 5-FU treatment.

Conclusion

This study suggested that TYMS serves as an oncogene in HCC, and targeting the FOXM1-TYMS axis may help improve the survival of HCC patients as well as provide new insights for treating advanced HCC patients.

S-Adenosylmethionine: From the Discovery of Its Inhibition of Tumorigenesis to Its Use as a Therapeutic Agent

Alterations of methionine cycle in steatohepatitis, cirrhosis, and hepatocellular carcinoma induce MAT1A decrease and MAT2A increase expressions with the consequent decrease of S-adenosyl-L-methionine (SAM). This causes non-alcoholic fatty liver disease (NAFLD). SAM administration antagonizes pathological conditions, including galactosamine, acetaminophen, and ethanol intoxications, characterized by decreased intracellular SAM. Positive therapeutic effects of SAM/vitamin E or SAM/ursodeoxycholic acid in animal models with NAFLD and intrahepatic cholestasis were not confirmed in humans. In in vitro experiments, SAM and betaine potentiate PegIFN-alpha-2a/2b plus ribavirin antiviral effects. SAM plus betaine improves early viral kinetics and increases interferon-stimulated gene expression in patients with viral hepatitis non-responders to pegIFNα/ribavirin. SAM prevents hepatic cirrhosis, induced by CCl4, inhibits experimental tumors growth and is proapoptotic for hepatocellular carcinoma and MCF-7 breast cancer cells. SAM plus Decitabine arrest cancer growth and potentiate doxorubicin effects on breast, head, and neck cancers. Furthermore, SAM enhances the antitumor effect of gemcitabine against pancreatic cancer cells, inhibits growth of human prostate cancer PC-3, colorectal cancer, and osteosarcoma LM-7 and MG-63 cell lines; increases genomic stability of SW480 cells. SAM reduces colorectal cancer progression and inhibits the proliferation of preneoplastic rat liver cells in vivo. The discrepancy between positive results of SAM treatment of experimental tumors and modest effects against human disease may depend on more advanced human disease stage at moment of diagnosis.

HELLS Is Negatively Regulated by Wild-Type P53 in Liver Cancer by a Mechanism Involving P21 and FOXM1

Simple Summary

The tumor suppressor protein P53 is a major player in preventing liver cancer development and progression. In this study we could show that P53 negatively regulates the expression of Helicase, lymphoid specific (HELLS), previously described as an important pro-tumorigenic epigenetic regulator in hepatocarcinogenesis. The regulatory mechanism included induction of the P53 target gene P21 (CDKN1A) resulting in repression of HELLS via downregulation of the transcription factor Forkhead Box Protein M1 (FOXM1). Our in vitro and in vivo findings indicate an important additional aspect of the tumor suppressive function of P53 in liver cancer linked to epigenetic regulation.

Abstract

The major tumor suppressor P53 (TP53) acts primarily as a transcription factor by activating or repressing subsets of its numerous target genes, resulting in different cellular outcomes (e.g., cell cycle arrest, apoptosis and senescence). P53-dependent gene regulation is linked to several aspects of chromatin remodeling; however, regulation of chromatin-modifying enzymes by P53 is poorly understood in hepatocarcinogenesis. Herein, we identified Helicase, lymphoid specific (HELLS), a major epigenetic regulator in liver cancer, as a strong and selective P53 repression target within the SNF2-like helicase family. The underlying regulatory mechanism involved P53-dependent induction of P21 (CDKN1A), leading to repression of Forkhead Box Protein M1 (FOXM1) that in turn resulted in downregulation of HELLS expression. Supporting our in vitro data, we found higher expression of HELLS in murine HCCs arising in a Trp53−/− background compared to Trp53+/+ HCCs as well as a strong and highly significant correlation between HELLS and FOXM1 expression in different HCC patient cohorts. Our data suggest that functional or mutational inactivation of P53 substantially contributes to overexpression of HELLS in HCC patients and indicates a previously unstudied aspect of P53′s ability to suppress liver cancer formation.

Efficacy and Safety of Weekly Paclitaxel With or Without Oral Alisertib in Patients With Metastatic Breast Cancer: A Randomized Clinical Trial

IMPORTANCE

Elevated expression of AURKA adversely affects prognosis in estrogen receptor (ER)-positive and ERBB2 (formerly HER2)-negative and triple-negative breast cancer and is associated with resistance to taxanes.

OBJECTIVE

To compare paclitaxel alone vs paclitaxel plus alisertib in patients with ER-positive and ERBB2-negative or triple-negative metastatic breast cancer (MBC).

DESIGN, SETTING, AND PARTICIPANTS

In this randomized clinical trial conducted with the US Oncology Network, participants were randomized to intravenous (IV) paclitaxel 90 mg/m2 on days 1, 8, and 15 on a 28-day cycle or IV paclitaxel 60 mg/m2 on days 1, 8, and 15 plus oral alisertib 40 mg twice daily on days 1 to 3, 8 to 10, and 15 to 17 on a 28-day cycle. Stratification was by prior neo or adjuvant taxane and by line of metastatic therapy. Eligible patients were those who had undergone endocrine therapy, 0 or 1 prior chemotherapy regimens for MBC, more than 12 months treatment-free interval from neo or adjuvant taxane therapy, and with measurable or evaluable lytic bone-disease. Data were analyzed from March 2019 through May 2019.

MAIN OUTCOMES AND MEASURES

The main outcome was progression-free survival (PFS) with secondary end points of overall survival (OS), overall response rate, clinical benefit rate, safety, and analysis of archival breast cancer tissues for molecular markers associated with benefit from alisertib.

RESULTS

A total of 174 patients were randomized, including with 86 randomized to paclitaxel and 88 patients randomized to paclitaxel plus alisertib, and 169 patients received study treatment. The final cohort included 139 patients with a median (interquartile range [IQR]) age of 62 (27-84) years with ER-positive and ERBB2-negative MBC, with 70 randomized to paclitaxel and 69 randomized to paclitaxel plus alisertib. The TNBC cohort closed with only 35 patients enrolled due to slow accrual and were not included in efficacy analyses. The median (IQR) follow-up was 22 (10.6-25.1) months, and median (IQR) PFS was 10.2 (3.8-15.7) months with paclitaxel plus alisertib vs 7.1 (3.8-10.6) months with paclitaxel alone (HR, 0.56; 95% CI, 0.37-0.84; P = .005). Median (IQR) OS was 26.3 (12.4-37.2) months for patients who received paclitaxel plus alisertib vs 25.1 (11.0-31.4) months for paclitaxel alone (HR, 0.89; 95% CI, 0.58-1.38; P = .61). Grade 3 or 4 adverse events occurred in 56 patients (84.8%) receiving paclitaxel plus alisertib vs 34 patients (48.6%) receiving paclitaxel alone. The main grade 3 or 4 adverse events with paclitaxel plus alisertib vs paclitaxel alone were neutropenia (50 patients [59.5%] vs 14 patients [16.4%]), anemia (8 patients [9.5%] vs 1 patient [1.2%]), diarrhea (9 patients [10.7%] vs 0 patients), and stomatitis or oral mucositis (13 patients [15.5%] vs 0 patients). One patient receiving paclitaxel plus alisertib died of sepsis.

CONCLUSIONS AND RELEVANCE

This randomized clinical trial found that the addition of oral alisertib to a reduced dose of weekly paclitaxel significantly improved PFS compared with paclitaxel alone, and toxic effects with paclitaxel plus alisertib were manageable with alisertib dose reduction. These data support further evaluation of alisertib in patients with ER-positive, ERBB2-negative MBC.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02187991.

Autophagic protein ULK1 regulates FOXM1 signalling in human hepatoma cells

Hepatocellular cancer (HCC) is one of the leading causes of mortality worldwide. Unfortunately, a limited choice of anti-cancer drugs is available for treatment, owing to their minimal efficacy and development of acquired resistance. Autophagy, a cellular survival pathway, often exhibits a pleiotropic role in HCC progression. Studies show increased autophagy in established HCC, promoting the survival of HCC cells in the tumour microenvironment. Therefore, novel anti-autophagy drugs hold promise for preventing HCC progression. Here, using a non-biased transcriptomics analysis in HepG2 cells we demonstrate the existence of an autophagy-FOXM1 nexus regulating growth in HepG2 cells. Additionally, we show that suppression of autophagy by an Unc-51 Like Autophagy Activating Kinase 1(ULK1) inhibitor not only attenuates the expression of FOXM1 and its transcriptional targets, but also has a synergistic effect on the inhibition of HepG2 growth when combined with FOXM1 inhibitors. Thus, the autophagic protein, ULK1, is a promising candidate for preventing HCC progression. Collectively, our results provide new insight into the role of autophagy in HCC growth and are a proof-of concept for combinatorial therapy using ULK1 and FOXM1 inhibitors.

FOX transcription factor family in hepatocellular carcinoma

The pathogenesis of hepatocellular carcinoma (HCC) is a multistep process, involving the progressive accumulation of molecular alterations and transcriptomic alterations. The Forkhead-box (FOX) transcription factor family is characterized by its unique DNA binding domain (FKH or winged-helix domain). Human FOX family consists of about 17 subfamilies, at least 43 members. Some of them are liver-enriched transcription factors, suggesting that they may play a crucial role in the development or/and functions of the liver. Dysregulation of FOX transcription factors may contribute to the pathogenesis of HCC because they can activate or suppress the expression of various tumor-related molecules, and pinpoint different molecular and cellular events. Here we summarized, analyzed and discussed the status and the functions of the human FOX family of transcription factors in HCC, aiming to help the further development of them as potential therapeutic targets or/and diagnostic/prognostic markers for HCC.

Experimental Models to Define the Genetic Predisposition to Liver Cancer

Hepatocellular carcinoma (HCC) is a frequent human cancer and the most frequent liver tumor. The study of genetic mechanisms of the inherited predisposition to HCC, implicating gene-gene and gene-environment interaction, led to the discovery of multiple gene loci regulating the growth and multiplicity of liver preneoplastic and neoplastic lesions, thus uncovering the action of multiple genes and epistatic interactions in the regulation of the individual susceptibility to HCC. The comparative evaluation of the molecular pathways involved in HCC development in mouse and rat strains differently predisposed to HCC indicates that the genes responsible for HCC susceptibility control the amplification and/or overexpression of c-Myc, the expression of cell cycle regulatory genes, and the activity of Ras/Erk, AKT/mTOR, and of the pro-apoptotic Rassf1A/Nore1A and Dab2IP/Ask1 pathways, the methionine cycle, and DNA repair pathways in mice and rats. Comparative functional genetic studies, in rats and mice differently susceptible to HCC, showed that preneoplastic and neoplastic lesions of resistant mouse and rat strains cluster with human HCC with better prognosis, while the lesions of susceptible mouse and rats cluster with HCC with poorer prognosis, confirming the validity of the studies on the influence of the genetic predisposition to hepatocarinogenesis on HCC prognosis in mouse and rat models. Recently, the hydrodynamic gene transfection in mice provided new opportunities for the recognition of genes implicated in the molecular mechanisms involved in HCC pathogenesis and prognosis. This method appears to be highly promising to further study the genetic background of the predisposition to this cancer.

Alterations of Methionine Metabolism as Potential Targets for the Prevention and Therapy of Hepatocellular Carcinoma

Several researchers have analyzed the alterations of the methionine cycle associated with liver disease to clarify the pathogenesis of human hepatocellular carcinoma (HCC) and improve the preventive and the therapeutic approaches to this tumor. Different alterations of the methionine cycle leading to a decrease of S-adenosylmethionine (SAM) occur in hepatitis, liver steatosis, liver cirrhosis, and HCC. The reproduction of these changes in MAT1A-KO mice, prone to develop hepatitis and HCC, demonstrates the pathogenetic role of MAT1A gene under-regulation associated with up-regulation of the MAT2A gene (MAT1A:MAT2A switch), encoding the SAM synthesizing enzymes, methyladenosyltransferase I/III (MATI/III) and methyladenosyltransferase II (MATII), respectively. This leads to a rise of MATII, inhibited by the reaction product, with a consequent decrease of SAM synthesis. Attempts to increase the SAM pool by injecting exogenous SAM have beneficial effects in experimental alcoholic and non-alcoholic steatohepatitis and hepatocarcinogenesis. Mechanisms involved in hepatocarcinogenesis inhibition by SAM include: (1) antioxidative effects due to inhibition of nitric oxide (NO•) production, a rise in reduced glutathione (GSH) synthesis, stabilization of the DNA repair protein Apurinic/Apyrimidinic Endonuclease 1 (APEX1); (2) inhibition of c-myc, H-ras, and K-ras expression, prevention of NF-kB activation, and induction of overexpression of the oncosuppressor PP2A gene; (3) an increase in expression of the ERK inhibitor DUSP1; (4) inhibition of PI3K/AKT expression and down-regulation of C/EBPα and UCA1 gene transcripts; (5) blocking LKB1/AMPK activation; (6) DNA and protein methylation. Different clinical trials have documented curative effects of SAM in alcoholic liver disease. Furthermore, SAM enhances the IFN-α antiviral activity and protects against hepatic ischemia-reperfusion injury during hepatectomy in HCC patients with chronic hepatitis B virus (HBV) infection. However, although SAM prevents experimental tumors, it is not curative against already established experimental and human HCCs. The recent observation that the inhibition of MAT2A and MAT2B expression by miRNAs leads to a rise of endogenous SAM and strong inhibition of cancer cell growth could open new perspectives to the treatment of HCC.

microRNA 193a-5p Regulates Levels of Nucleolar- and Spindle-Associated Protein 1 to Suppress Hepatocarcinogenesis

BACKGROUND & AIMS

We performed an integrated analysis to identify microRNAs (miRNAs) and messenger RNAs (mRNAs) with altered expression in liver tumors from 3 mouse models of hepatocellular carcinoma (HCC) and human tumor tissues.

METHODS

We analyzed miRNA and mRNA expression profiles of liver tissues from mice with diethylnitrosamine-induced hepatocarcinogenesis, conditional expression of lymphotoxin alpha and lymphotoxin beta, or inducible expression of a Myc transgene (Tet-O-Myc mice), as well as male C57BL/6 mice (controls). miRNA mimics were expressed and miRNAs and mRNAs were knocked down in human (Huh7, Hep3B, JHH2) hepatoma cell lines; cells were analyzed for viability, proliferation, apoptosis, migration, and invasion. Cells were grown as xenograft tumors in nude mice and analyzed. We combined in silico target gene prediction with mRNA profiles from all 3 mouse models. We quantified miRNA levels in 146 fresh-frozen tissues from patients (125 HCCs, 17 matched nontumor tissues, and 4 liver samples from patients without cancer) and published human data sets and tested correlations with patient survival times using Kaplan-Meier curves and the log-rank test. Levels of NUSAP1 mRNA were quantified in 237 HCCs and 5 nontumor liver samples using the TaqMan assay.

RESULTS

Levels of the miRNA 193a-5p (MIR193A-5p) were reduced in liver tumors from all 3 mouse tumor models and in human HCC samples, compared with nontumor liver tissues. Expression of a MIR193A-5p mimic in hepatoma cells reduced proliferation, survival, migration, and invasion and their growth as xenograft tumors in nude mice. We found nucleolar and spindle-associated protein 1 (NUSAP1) to be a target of MIR193A-5p; HCC cells and tissues with low levels of MIR193A-5p had increased expression of NUSAP1. Increased levels of NUSAP1 in HCC samples correlated with shorter survival times of patients. Knockdown of NUSAP1 in Huh7 cells reduced proliferation, survival, migration, and growth as xenograft tumors in nude mice. Hydrodynamic tail-vein injections of a small hairpin RNA against NUSAP1 reduced growth of Akt1-Myc-induced tumors in mice.

CONCLUSIONS

MIR193A-5p appears to prevent liver tumorigenesis by reducing levels of NUSAP1. Levels of MIR193A-5p are reduced in mouse and human HCC cells and tissues, leading to increased levels of NUSAP1, associated with shorter survival times of patients. Integrated analyses of miRNAs and mRNAs in tumors from mouse models can lead to identification of therapeutic targets in humans. The currently reported miRNA and mRNA profiling data have been submitted to the Gene Expression Omnibus (super-series accession number GSE102418).

Upregulation of FOXM1 leads to diminished drug sensitivity in myeloma

BACKGROUND

Following up on previous work demonstrating the involvement of the transcription factor forkhead box M1 (FOXM1) in the biology and outcome of a high-risk subset of newly diagnosed multiple myeloma (nMM), this study evaluated whether FOXM1 gene expression may be further upregulated upon tumor recurrence in patients with relapsed multiple myeloma (rMM). Also assessed was the hypothesis that increased levels of FOXM1 diminish the sensitivity of myeloma cells to commonly used myeloma drugs, such as the proteasome inhibitor bortezomib (Bz) and the DNA intercalator doxorubicin (Dox).

METHODS

FOXM1 message was evaluated in 88 paired myeloma samples from patients with nMM and rMM, using gene expression microarrays as measurement tool. Sources of differential gene expression were identified and outlier analyses were performed using statistical methods. Two independent human myeloma cell lines (HMCLs) containing normal levels of FOXM1 (FOXM1N) or elevated levels of lentivirus-encoded FOXM1 (FOXM1Hi) were employed to determine FOXM1-dependent changes in cell proliferation, survival, efflux-pump activity, and drug sensitivity. Levels of retinoblastoma (Rb) protein were determined with the assistance of Western blotting.

RESULTS

Upregulation of FOXM1 occurred in 61 of 88 (69%) patients with rMM, including 4 patients that exhibited > 20-fold elevated expression peaks. Increased FOXM1 levels in FOXM1Hi myeloma cells caused partial resistance to Bz (1.9-5.6 fold) and Dox (1.5-2.9 fold) in vitro, using FOXM1N myeloma as control. Reduced sensitivity of FOXM1Hi cells to Bz was confirmed in vivo using myeloma-in-mouse xenografts. FOXM1-dependent regulation of total and phosphorylated Rb agreed with a working model of myeloma suggesting that FOXM1 governs both chromosomal instability (CIN) and E2F-dependent proliferation, using a mechanism that involves interaction with NIMA related kinase 2 (NEK2) and cyclin dependent kinase 6 (CDK6), respectively.

CONCLUSIONS

These findings enhanced our understanding of the emerging FOXM1 genetic network in myeloma and provided preclinical support for the therapeutic targeting of the FOXM1-NEK2 and CDK4/6-Rb-E2F pathways using small-drug CDK and NEK2 inhibitors. Clinical research is warranted to assess whether this approach may overcome drug resistance in FOXM1Hi myeloma and, thereby, improve the outcome of patients in which the transcription factor is expressed at high levels.

NEK2 Promotes Hepatoma Metastasis and Serves as Biomarker for High Recurrence Risk after Hepatic Resection

INTRODUCTION AND AIM

Developing reliable biomarkers for hepatocellular carcinoma (HCC) patients who are at a high risk of recurrence after curative hepatic resection is very important for determining subsequent therapeutic strategies. We investigated the role of the cell cycle factor NIMA-related kinase 2 (NEK2) in HCC progression in hepatoma cells and post-surgery patients.

MATERIAL AND METHODS

The effects of NEK2 on proliferation, invasion and migration of hepatoma HuH7 and SK-Hep1 cells were evaluated. In a post-surgery HCC cohort (N = 97), the Nek2 induction levels in the tumors were examined with real-time RT-PCR analysis, and the results were analyzed for their correlations with recurrence.

RESULTS

NEK2 promoted G1 to S phase cell cycle progression by causing increases in cyclin D1 and AKT phosphorylation and decreases in the cyclin-dependent kinase inhibitor p27, indicating that NEK2 plays an important role during interphase in addition to its previously identified role in M phase. NEK2 also enhanced the proliferation, migration and invasion of hepatoma cells and regulated the expression of E-cadherin and MMP9. The Nek2 mRNA levels in the tumors were highly correlated with recurrence rates in the post-surgery HCC patients. Combined evaluation of the tumor AJCC stage and the Nek2 level can serve as a reliable method for predicting the relative risk of HCC recurrence in these patients.

CONCLUSIONS

NEK2 plays a significant role in cell cycle progression in the inter- and M-phases. NEK2 enhances HCC metastasis and is correlated with recurrence and thus can potentially serve a promising high-risk biomarker for HCC.

Deregulation of methionine metabolism as determinant of progression and prognosis of hepatocellular carcinoma

The under-regulation of liver-specific MAT1A gene codifying for S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and the up-regulation of widely expressed MAT2A, MATII isozyme occurs in hepatocellular carcinoma (HCC). MATα1:MATα2 switch strongly contributes to the fall in SAM liver content both in rodent and human liver carcinogenesis. SAM administration to carcinogen-treated animals inhibits hepatocarcinogenesis. The opposite occurs in Mat1a-KO mice, in which chronic SAM deficiency is followed by HCC development. This review focuses upon the changes, induced by the MATα1:MATα2 switch, involved in HCC development. In association with MATα1:MATα2 switch there occurs, in HCC, global DNA hypomethylation, decline of DNA repair, genomic instability, and deregulation of different signaling pathways such as overexpression of c-MYC (avian myelocytomatosis viral oncogene homolog), increase of polyamine (PA) synthesis and RAS/ERK (Harvey murine sarcoma virus oncogene homolog/extracellular signal-regulated kinase), IKK/NF-kB (I-k kinase beta/nuclear factor kB), PI3K/AKT, and LKB1/AMPK axes. Furthermore, a decrease in MATα1 expression and SAM level induces HCC cell proliferation and survival. SAM treatment in vivo and enforced MATα1 overexpression or MATα2 inhibition, in cultured HCC cells, prevent these changes. A negative correlation of MATα1:MATα2 and MATI/III:MATII ratios with cell proliferation and genomic instability and a positive correlation with apoptosis and global DNA methylation are present in human HCC. Altogether, these data suggest that the decrease of SAM level and the deregulation of MATs are potential therapeutic targets for HCC.

Targeting the mevalonate pathway is a novel therapeutic approach to inhibit oncogenic FoxM1 transcription factor in human hepatocellular carcinoma

Dysregulation of cell metabolism is a hallmark of cancer. The mevalonate pathway in lipid metabolism has been implicated as a potential target of cancer therapy for hepatocellular carcinoma (HCC). The role of the Forkhead Box M1 (FoxM1) transcription factor in HCC development has been well documented, however, its involvement in cancer metabolism of HCC has not been fully determined. Here, we hypothesized that FoxM1 is involved in the mevalonate pathway of cholesterol biosynthesis in HCC. Inhibition of the mevalonate pathway by statins, inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR), resulted in reduced expression of FoxM1 and increased cell death in human hepatoma cells. Re-exposure of mevalonate, a product of HMGCR, restored these effects. Likewise, knockdown of HMGCR reduced FoxM1 expression, indicating that FoxM1 expression was regulated by the mevalonate pathway in HCC. Mechanistically, protein geranylgeranylation was found to be responsible for FoxM1 expression and geranylgeranylated proteins, including RhoA, Rac1 or Cdc42, were shown to be involved in this process. In surgically resected human HCC tissues, the gene expression of FoxM1 had a positive correlation with that of the mevalonate pathway-related genes, such as HMGCR or sterol regulatory element-binding protein 2 (SREBP2). Furthermore, the gene expression of FoxM1 along with that of HMGCR or SREBP2 defined prognosis of HCC patients, suggesting the clinical significance of the mevalonate-FoxM1 pathway in human HCC. Our data indicate that FoxM1 links the mevalonate pathway to oncogenic signals in HCC. Thus, we propose a novel therapeutic approach to inhibit FoxM1 by targeting the mevalonate pathway for HCC.

Overexpression of FOXM1 as a target for malignant progression of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common types of malignancies globally. Forkhead box M1 (FOXM1) has important functions in cancer progression. However, the function of FOXM1 signaling in ESCC remains unknown. The aim of the present study was to evaluate the expression level and function of FOXM1 in human ESCC. The present study first detected the FOXM1 expression level in 78 cases of primary ESCC tissues and matched normal tissue samples by immunohistochemistry, western blot analysis and reverse transcription-quantitative polymerase chain reaction. Subsequently, the present study investigated the impact of FOXM1 knockdown on the ability of cell proliferation and migration of ESCC cells by MTT, clonogenic and Transwell assays. The results revealed that the mRNA and protein expression levels of FOXM1 were upregulated in a series of ESCC tissue samples. Silencing of FOXM1 inhibited the proliferation and migration of ESCC cells. In conclusion, FOXM1 was significantly increased in cancerous tissue samples of patients with ESCC. It may serve as a selective target for the treatment of ESCC.

A novel microRNA, hsa-miR-6852 differentially regulated by Interleukin-27 induces necrosis in cervical cancer cells by downregulating the FoxM1 expression

We have previously demonstrated that Interleukin-27 differentially regulates the expression of seven novel microRNAs. Here we elucidate the functional significance of these novel microRNAs. Of the seven microRNAs, over expression of miRNA-6852 (miR-SX4) mimic induces cell cycle arrest at G2/M phase and induces necrosis in HEK293 and panel of cervical cancer cells (Human Papilloma Virus (HPV) infected cell lines; HeLa, CaSki and SiHa cells). To define the mechanism of the miR-SX4-mediated G2/M arrest, a microarray gene chip array and western blot analysis were performed. FoxM1, a transcription factor is identified as a key protein down-regulated by miR-SX4, even though the miR-SX4 does not target 3’UTR of FoxM1. Knock down of FoxM1 using si-RNA demonstrate that FoxM1 silenced cell induces G2/M cell cycle arrest and necrosis. Our data demonstrated for the first time that miR-SX4 could be a potent anti-cancer microRNA.

FOXM1 regulates expression of eukaryotic elongation factor 2 kinase and promotes proliferation, invasion and tumorgenesis of human triple negative breast cancer cells

Eukaryotic elongation factor 2 kinase (eEF2K), an emerging molecular target for cancer therapy, contributes to cancer proliferation, cell survival, tumorigenesis, and invasion, disease progression and drug resistance. Although eEF2K is highly up-regulated in various cancers, the mechanism of gene regulation has not been elucidated. In this study, we examined the role of Forkhead Box M1 (FOXM1) proto-oncogenic transcription factor in triple negative breast cancer (TNBC) cells and the regulation of eEF2K. We found that FOXM1 is highly upregulated in TNBC and its knockdown by RNA interference (siRNA) significantly inhibited eEF2K expression and suppressed cell proliferation, colony formation, migration, invasion and induced apoptotic cell death, recapitulating the effects of eEF2K inhibition. Knockdown of FOXM1 inhibited regulators of cell cycle, migration/invasion and survival, including cyclin D1, Src and MAPK-ERK signaling pathways, respectively. We also demonstrated that FOXM1 (1B and 1C isoforms) directly binds to and transcriptionally regulates eEF2K gene expression by chromatin immunoprecipitation (ChIP) and luciferase gene reporter assays. Furthermore, in vivo inhibition of FOXM1 by liposomal siRNA-nanoparticles suppressed growth of MDA-MB-231 TNBC tumor xenografts in orthotopic models. In conclusion, our study provides the first evidence about the transcriptional regulation of eEF2K in TNBC and the role of FOXM1 in mediating breast cancer cell proliferation, survival, migration/invasion, progression and tumorgenesis and highlighting the potential of FOXM1/eEF2K axis as a molecular target in breast and other cancers.

Metadherin/Astrocyte elevated gene-1 positively regulates the stability and function of forkhead box M1 during tumorigenesis

Background

Forkhead box M1 (FOXM1) is overexpressed and activates numerous oncoproteins in tumors. However, the mechanism by which the FOXM1 protein aberrantly accumulates in human cancer remains uncertain. This study was designed to clarify the upstream signaling pathway(s) that regulate FOXM1 protein stability and transcriptional activity.

Methods

Mass spectrometry and immunoprecipitation were performed to identify the FOXM-metadherin (MTDH) interaction. In vivo and in vitro ubiquitination assays were conducted to test the effect of MTDH on FOXM1 stability. Chromatin immunoprecipitation assays were used to determine the involvement of MTDH in FOXM1 transcriptional activity. Cell invasion assays, tube formation assays, and in vivo tumor formation assays were performed to evaluate the cooperative activities of FOXM1 and MTDH during tumorigenesis.

Results

MTDH directly interacts with FOXM1 via the N-terminal inhibitory domain of MTDH, and this interaction disrupted the binding of cadherin-1 to FOXM1, thus protecting FOXM1 from subsequent proteasomal degradation. Deleting the MTDH-binding sites of FOXM1 abolished the MTDH overexpression-mediated stabilization of FOXM1. MTDH also bound to FOXM1 target gene promoters and enhanced FOXM1 transcriptional activity. MTDH knockdown destabilized FOXM1 and attenuated its transcriptional activity, consequently inhibiting cell cycle progression, angiogenesis, and cancer cell invasion in vitro and in vivo; these effects were abolished via forced overexpression of a stabilized mutant form of FOXM1. Thus, MTDH stabilized FOXM1 and supported the sustained activation of FOXM1 target genes.

Conclusion

These findings highlight a novel MTDH-regulated mechanism of FOXM1 stabilization and provide profound insight into the tumorigenic events simultaneously mediated by FOXM1 and MTDH.

FOXM1 is a therapeutic target for high-risk multiple myeloma

The transcription factor forkhead box M1 (FOXM1) is a validated oncoprotein in solid cancers, but its role in malignant plasma cell tumors such as multiple myeloma (MM) is unknown. We analyzed publicly available MM data sets and found that overexpression of FOXM1 prognosticates inferior outcome in a subset (~15%) of newly diagnosed cases, particularly patients with high-risk disease based on global gene expression changes. Follow-up studies using human myeloma cell lines (HMCLs) as the principal experimental model system demonstrated that enforced expression of FOXM1 increased growth, survival and clonogenicity of myeloma cells, whereas knockdown of FOXM1 abolished these features. In agreement with that, constitutive upregulation of FOXM1 promoted HMCL xenografts in laboratory mice, whereas inducible knockdown of FOXM1 led to growth inhibition. Expression of cyclin-dependent kinase 6 (CDK6) and NIMA-related kinase 2 (NEK2) was coregulated with FOXM1 in both HMCLs and myeloma patient samples, suggesting interaction of these three genes in a genetic network that may lend itself to targeting with small-drug inhibitors for new approaches to myeloma therapy and prevention. These results establish FOXM1 as high-risk myeloma gene and provide support for the design and testing of FOXM1-targeted therapies specifically for the FOXM1(High) subset of myeloma.

Overexpressed transcription factor FOXM1 contributes to the progression of colorectal cancer

Forkhead box M1 (FOXM1) is a characteristic proliferation‑associated transcription factor, which is overexpressed in various types of human cancer. The aim of the present study was to determine the expression of FOXM1 in a large collection of colorectal cancer (CRC) samples. Between March 2012 and January 2014, 96 patients with histologically diagnosed CRC were recruited into the current study. Using immunohistochemistry, reverse transcription‑quantitative polymerase chain reaction and western blotting, mRNA and protein expression levels of FOXM1 in CRC tissue samples were determined. The function of FOXM1 in the CRC cells was evaluated by small interfering RNA‑mediated depletion of FOXM1, followed by analyses of cell proliferation and invasion. High levels of staining for FOXM1 were observed in significantly more CRC tissue samples: 85.42% (82/96) of CRC tissue samples compared with 18.75% (18/96) of adjacent normal mucosa tissue samples. Silencing FOXM1 inhibited the proliferation of LoVo cells, which express a relatively high level of FOXM1, and the invasion and migration of LoVo cells were also markedly suppressed. The data from the present study suggested that the pathogenesis of human CRC may be mediated by FOXM1, and that FOXM1 inhibition may provide a promising therapeutic strategy for CRC.

Peroxiredoxin II promotes hepatic tumorigenesis through cooperation with Ras/Forkhead box M1 signaling pathway

The current study was carried out to define the involvement of Peroxiredoxin (Prx) II in progression of hepatocellular carcinoma (HCC) and the underlying molecular mechanism(s). Expression and function of Prx II in HCC was determined using H-ras(G12V)-transformed HCC cells (H-ras(G12V)-HCC cells) and the tumor livers from H-ras(G12V)-transgenic (Tg) mice and HCC patients. Prx II was upregulated in H-ras(G12V)-HCC cells and H-ras(G12V)-Tg mouse tumor livers, the expression pattern of which highly similar to that of forkhead Box M1 (FoxM1). Moreover, either knockdown of FoxM1 or site-directed mutagenesis of FoxM1-binding site of Prx II promoter significantly reduced Prx II levels in H-ras(G12V)-HCC cells, indicating FoxM1 as a direct transcription factor of Prx II in HCC. Interestingly, the null mutation of Prx II markedly decreased the number and size of tumors in H-ras(G12V)-Tg livers. Consistent with this, knockdown of Prx II in H-ras(G12V)-HCC cells reduced the expression of cyclin D1, cell proliferation, anchorage-independent growth and tumor formation in athymic nude mice, whereas overexpression of Prx II increased or aggravated the tumor phenotypes. Importantly, the expression of Prx II was correlated with that of FoxM1 in HCC patients. The activation of extracellular signal-related kinase (ERK) pathway and the expression of FoxM1 and cyclin D1 were highly dependent on Prx II in H-ras(G12V)-HCC cells and H-ras(G12V)-Tg livers. Prx II is FoxM1-dependently-expressed antioxidant in HCC and function as an enhancer of Ras(G12V) oncogenic potential in hepatic tumorigenesis through activation of ERK/FoxM1/cyclin D1 cascade.

Elevated expression of FoxM1 promotes the tumor cell proliferation in hepatocellular carcinoma

The Forkhead box M1 (FoxM1) transcription factor plays crucial roles in multiple biological processes, including cell proliferation, differentiation, migration, and transformation. Recent studies have reported that aberrant expression of FoxM1 was found in a variety of human cancers. However, the expression pattern of FoxM1 and its clinical significance in human hepatocellular carcinoma (HCC) have not been well characterized to date. In this study, the expression of FoxM1 was evaluated in 46 pairs of human HCC, the adjacent non-tumorous liver tissues, and 12 pairs of normal liver tissues by immumohistochemistry. FoxM1 expression was upregulated in the HCC (76.09 %) compared with non-tumorous liver tissues (39.13 %) and normal liver tissues (8.33 %) (P < 0.05). FoxM1 expression was significantly associated with tumor stage, tumor size, tumor number, integrality of tumor encapsulation, tumor thrombus, and AFP level (P < 0.05). Functionally, enforced expression of FoxM1 in HCC cell line (HHCC) remarkably enhanced cell proliferation in vitro and in vivo. Further analysis of cell cycle-related molecules showed that FoxM1 overexpression increased expressions of cyclin B1 and cyclin D1 but reduced expressions of p27(Kip1) and p21(Cip1). Our findings suggest that FoxM1 overexpression promotes HCC cell proliferation by cell cycle regulation, which is a potential target for hepatocellular carcinoma therapy.

Loss of Foxm1 Results in Reduced Somatotrope Cell Number during Mouse Embryogenesis

FOXM1, a member of the forkhead box transcription factor family, plays a key role in cell cycling progression by regulating the expression of critical G1/S and G2/M phase transition genes. In vivo studies reveal that Foxm1 null mice have a 91% lethality rate at e18.5 due to significant cardiovascular and hepatic hypoplasia. Thus, FOXM1 has emerged as a key protein regulating mitotic division and cell proliferation necessary for embryogenesis. In the current study, we assess the requirement for Foxm1 in the developing pituitary gland. We find that Foxm1 is expressed in the pituitary at embryonic days 10.5-e18.5 and localizes with markers for active cell proliferation (BrdU). Interestingly, direct analysis of Foxm1 null mice at various embryonic ages, reveals no difference in gross pituitary morphology or cell proliferation. We do observe a downward trend in overall pituitary cell number and a small reduction in pituitary size in e18.5 embryos suggesting there may be subtle changes in pituitary proliferation not detected with our proliferation makers. Consistent with this, Foxm1 null mice have reductions in both the somatotrope and gonadotrope cell populations.

FOXM1-mediated downregulation of uPA and MMP9 by 3,3'-diindolylmethane inhibits migration and invasion of human colorectal cancer cells

Although 3,3'-diindolylmethane (DIM) has been suggested to reduce the risk of colorectal cancer, the underlying biological mechanism is not clearly understood. In the present study, we investigated the effect of DIM on the migratory and invasive activities of the human colorectal cancer cell lines DLD-1 and HCT116. DIM significantly inhibited the migration and invasion of colorectal cancer cells as assessed by wound healing and Matrigel invasion assays. The migratory ability of the DLD-1 and HCT116 cells was significantly reduced by DIM at 24 and 48 h. DIM also significantly inhibited the invasion rate of the DLD-1 and HCT116 cells in a dose-dependent manner. The mRNA expression levels of urokinase type plasminogen activator (uPA) and matrix metalloprotease 9 (MMP9) were significantly attenuated, whereas expression of E-cadherin mRNA was significantly enhanced, following DIM treatment. DIM also decreased the protein levels of uPA and MMP9, yet significantly increased E-cadherin protein expression. In addition, DIM significantly reduced the mRNA and protein levels of FOXM1 in the DLD-1 and HCT116 cells. Our results suggest that DIM can influence the cell migratory and invasive properties of human colorectal cancer cells and may decrease the invasive capacity of colorectal cancer through downregulation of uPA and MMP9 mediated by suppression of the transcription factor FOXM1.

Targeting FoxM1 transcription factor in T-cell acute lymphoblastic leukemia cell line

The Forkhead box protein M1 (FoxM1) is an important transcription factor having significant roles in various cellular events. FoxM1 overexpression has been reported to be related with many types of cancer. However, it is not known whether it contributes to oncogenesis of acute lymphoblastic leukemia. Siomycin A, a thiazol antibiotic, is known to inhibit FoxM1 transcriptional activity. In this study, we aimed to determine gene expression levels of FoxM1 in Jurkat cells (T-cell acute lymphoblastic leukemia cell line) and therapeutic potential of targeting FoxM1 by siomycin A alone and in combination with dexamethasone which improves the survival of children with T-cell acute lymphoblastic leukemia (ALL). We also examined the molecular mechanisms of siomycin A and dexamethasone-induced cell death in Jurkat cells. We demonstrated that FoxM1 mRNA is highly expressed in Jurkat cells. Dexamethasone and siomycin A caused a significant reduction in gene expression levels of FoxM1 in Jurkat cells. Targeting FoxM1 by siomycin A and dexamethasone caused a significant decrease in T-ALL cell line proliferation through induction of G1 cell cycle arrest. All these findings suggest a possible role of FoxM1 in T-cell ALL pathogenesis and represent FoxM1 as an attractive target for T-cell ALL therapy.

Gd-EOB-DTPA-enhanced magnetic resonance imaging and alpha-fetoprotein predict prognosis of early-stage hepatocellular carcinoma

The survival of patients with hepatocellular carcinoma (HCC) is often individually different even after surgery for early-stage tumors. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) has been introduced recently to evaluate hepatic lesions with regard to vascularity and the activity of the organic anion transporter OATP1B3. Here we report that Gd-EOB-DTPA-enhanced MRI (EOB-MRI) in combination with serum alpha-fetoprotein (AFP) status reflects the stem/maturational status of HCC with distinct biology and prognostic information. Gd-EOB-DTPA uptake in the hepatobiliary phase was observed in ∼15% of HCCs. This uptake correlated with low serum AFP levels, maintenance of hepatocyte function with the up-regulation of OATP1B3 and HNF4A expression, and good prognosis. By contrast, HCC showing reduced Gd-EOB-DTPA uptake with high serum AFP levels was associated with poor prognosis and the activation of the oncogene FOXM1. Knockdown of HNF4A in HCC cells showing Gd-EOB-DTPA uptake resulted in the increased expression of AFP and FOXM1 and the loss of OATP1B3 expression accompanied by morphological changes, enhanced tumorigenesis, and loss of Gd-EOB-DTPA uptake in vivo. HCC classification based on EOB-MRI and serum AFP levels predicted overall survival in a single-institution cohort (n=70), and its prognostic utility was validated independently in a multi-institution cohort of early-stage HCCs (n=109).

CONCLUSION

This noninvasive classification system is molecularly based on the stem/maturation status of HCCs and can be incorporated into current staging practices to improve management algorithms, especially in the early stage of disease.

Mitogen Activated Protein Kinase Family Proteins and c-jun Signaling in Injury-induced Schwann Cell Plasticity

Schwann cells (SCs) in the peripheral nerves myelinate axons during postnatal development to allow saltatory conduction of nerve impulses. Well-organized structures of myelin sheathes are maintained throughout life unless nerves are insulted. After peripheral nerve injury, unidentified signals from injured nerves drive SC dedifferentiation into an immature state. Dedifferentiated SCs participate in axonal regeneration by producing neurotrophic factors and removing degenerating nerve debris. In this review, we focus on the role of mitogen activated protein kinase family proteins (MAP kinases) in SC dedifferentiation. In addition, we will highlight neuregulin 1 and the transcription factor c-jun as upstream and downstream signals for MAP kinases in SC responses to nerve injury.

Computational modeling identifies key gene regulatory interactions underlying phenobarbital-mediated tumor promotion

Gene regulatory interactions underlying the early stages of non-genotoxic carcinogenesis are poorly understood. Here, we have identified key candidate regulators of phenobarbital (PB)-mediated mouse liver tumorigenesis, a well-characterized model of non-genotoxic carcinogenesis, by applying a new computational modeling approach to a comprehensive collection of in vivo gene expression studies. We have combined our previously developed motif activity response analysis (MARA), which models gene expression patterns in terms of computationally predicted transcription factor binding sites with singular value decomposition (SVD) of the inferred motif activities, to disentangle the roles that different transcriptional regulators play in specific biological pathways of tumor promotion. Furthermore, transgenic mouse models enabled us to identify which of these regulatory activities was downstream of constitutive androstane receptor and β-catenin signaling, both crucial components of PB-mediated liver tumorigenesis. We propose novel roles for E2F and ZFP161 in PB-mediated hepatocyte proliferation and suggest that PB-mediated suppression of ESR1 activity contributes to the development of a tumor-prone environment. Our study shows that combining MARA with SVD allows for automated identification of independent transcription regulatory programs within a complex in vivo tissue environment and provides novel mechanistic insights into PB-mediated hepatocarcinogenesis.

New insights on the role of epigenetic alterations in hepatocellular carcinoma

Emerging evidence assigns to epigenetic mechanisms heritable differences in gene function that come into being during cell development or via the effect of environmental factors. Epigenetic deregulation is strongly involved in the development of hepatocellular carcinoma (HCC). It includes changes in methionine metabolism, promoter hypermethylation, or increased proteasomal degradation of oncosuppressors, as well as posttranscriptional deregulation by microRNA or messenger RNA (mRNA) binding proteins. Alterations in the methylation of the promoter of methyl adenosyltransferase MAT1A and MAT2A genes in HCC result in decreased S-adenosylmethionine levels, global DNA hypomethylation, and deregulation of signal transduction pathways linked to methionine metabolism and methyl adenosyltransferases activity. Changes in S-adenosylmethionine levels may also depend on MAT1A mRNA destabilization associated with MAT2A mRNA stabilization by specific proteins. Decrease in MAT1A expression has also been attributed to miRNA upregulation in HCC. A complex deregulation of miRNAs is also strongly involved in hepatocarcinogenesis, with up-regulation of different miRNAs targeting oncosuppressor genes and down-regulation of miRNAs targeting genes involved in cell-cycle and signal transduction control. Oncosuppressor gene down-regulation in HCC is also induced by promoter hypermethylation or posttranslational deregulation, leading to proteasomal degradation. The role of epigenetic changes in hepatocarcinogenesis has recently suggested new promising therapeutic approaches for HCC on the basis of the administration of methylating agents, inhibition of methyl adenosyltransferases, and restoration of the expression of tumor-suppressor miRNAs.

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.

Identification of cell cycle-regulated genes periodically expressed in U2OS cells and their regulation by FOXM1 and E2F transcription factors

Characterization of the cell cycle–regulated transcripts in U2OS cells yielded 1871 unique genes. FOXM1 targets were identified via ChIP-seq, and novel targets in G2/M and S phases were verified using a real-time luciferase assay. ChIP-seq data were used to map cell cycle transcriptional regulators of cell cycle–regulated gene expression in U2OS cells.

We identify the cell cycle–regulated mRNA transcripts genome-wide in the osteosarcoma-derived U2OS cell line. This results in 2140 transcripts mapping to 1871 unique cell cycle–regulated genes that show periodic oscillations across multiple synchronous cell cycles. We identify genomic loci bound by the G2/M transcription factor FOXM1 by chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) and associate these with cell cycle–regulated genes. FOXM1 is bound to cell cycle–regulated genes with peak expression in both S phase and G2/M phases. We show that ChIP-seq genomic loci are responsive to FOXM1 using a real-time luciferase assay in live cells, showing that FOXM1 strongly activates promoters of G2/M phase genes and weakly activates those induced in S phase. Analysis of ChIP-seq data from a panel of cell cycle transcription factors (E2F1, E2F4, E2F6, and GABPA) from the Encyclopedia of DNA Elements and ChIP-seq data for the DREAM complex finds that a set of core cell cycle genes regulated in both U2OS and HeLa cells are bound by multiple cell cycle transcription factors. These data identify the cell cycle–regulated genes in a second cancer-derived cell line and provide a comprehensive picture of the transcriptional regulatory systems controlling periodic gene expression in the human cell division cycle.

Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis

Downregulation of liver-specific MAT1A gene, encoding S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and upregulation of widely expressed MAT2A, encoding MATII isozyme, known as MAT1A:MAT2A switch, occurs in hepatocellular carcinoma (HCC). Being inhibited by its reaction product, MATII isoform upregulation cannot compensate for MATI/III decrease. Therefore, MAT1A:MAT2A switch contributes to decrease in SAM level in rodent and human hepatocarcinogenesis. SAM administration to carcinogen-treated rats prevents hepatocarcinogenesis, whereas MAT1A-KO mice, characterized by chronic SAM deficiency, exhibit macrovesicular steatosis, mononuclear cell infiltration in periportal areas, and HCC development. This review focuses upon the pleiotropic changes, induced by MAT1A/MAT2A switch, associated with HCC development. Epigenetic control of MATs expression occurs at transcriptional and post-transcriptional levels. In HCC cells, MAT1A/MAT2A switch is associated with global DNA hypomethylation, decrease in DNA repair, genomic instability, and signaling deregulation including c-MYC overexpression, rise in polyamine synthesis, upregulation of RAS/ERK, IKK/NF-kB, PI3K/AKT, and LKB1/AMPK axis. Furthermore, decrease in MAT1A expression and SAM levels results in increased HCC cell proliferation, cell survival, and microvascularization. All of these changes are reversed by SAM treatment in vivo or forced MAT1A overexpression or MAT2A inhibition in cultured HCC cells. In human HCC, MAT1A:MAT2A and MATI/III:MATII ratios correlate negatively with cell proliferation and genomic instability, and positively with apoptosis and global DNA methylation. This suggests that SAM decrease and MATs deregulation represent potential therapeutic targets for HCC. Finally, MATI/III:MATII ratio strongly predicts patients' survival length suggesting that MAT1A:MAT2A expression ratio is a putative prognostic marker for human HCC.

LXRα-mediated downregulation of FOXM1 suppresses the proliferation of hepatocellular carcinoma cells

Liver X receptors (LXRs), including LXRα and LXRβ isoforms, have important roles in the metabolic regulation of glucose, cholesterol and lipid. Moreover, activation of LXRs also represses the expression of cyclin D1 and cyclin B1, and thus suppresses the proliferation of multiple cancer cells, but the relevant mechanism is not well known. Forkhead box M1 (FOXM1) is a proliferation-specific member of forkhead box family, which is highly expressed in proliferating normal cells and numerous cancer cells. FOXM1 directly activates transcription of cyclin D1 and cyclin B1, resulting in the enhancement of cell cycle progression and cell proliferation. However, it is unclear whether LXRs are involved in the regulation of FOXM1. In this study, we demonstrated that specific LXRs agonists downregulated expression of FOXM1, cyclin D1 and cyclin B1 in hepatocellular carcinoma (HCC) cells, which led to cell cycle and cell proliferation arrest. Knockdown of FOXM1 significantly alleviated LXRs activation-mediated cell cycle arrest and cell growth suppression. Reporter assays showed that the activation of LXRs significantly reduced the transcriptional activity of FOXM1 promoter. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that LXRα but not LXRβ could bind to an inverted repeat IR2 (-52CCGTCAcgTGACCT-39) in the promoter region of FOXM1 gene. Moreover, the xenograft tumor growth and the corresponding FOXM1 expression in nude mice were dramatically repressed by LXRs agonists. Taken together, we conclude that LXRα but not LXRβ functions as a transcriptional repressor for FOXM1 expression. The pathway 'LXRα-FOXM1-cyclin D1/cyclin B1' is a novel mechanism by which LXRs suppress the proliferation of HCC cells, suggesting that the pathway may be a novel target for HCC treatment.

ACP5, a direct transcriptional target of FoxM1, promotes tumor metastasis and indicates poor prognosis in hepatocellular carcinoma

Tartrate-resistant acid phosphatase 5 (ACP5), which is essential for bone resorption and osteoclast differentiation, promotes cell motility through the modulation of focal adhesion kinase phosphorylation. However, whether ACP5 contributes to the metastasis and progression of hepatocellular carcinoma (HCC) remains unknown. In this paper, a complementary DNA microarray, serial deletion, site-directed mutagenesis and a chromatin immunoprecipitation assays confirmed that ACP5 is a direct transcriptional target of Forkhead box M1 (FoxM1). ACP5 expression was markedly higher in HCC tissues compared with adjacent noncancerous tissues. ACP5 overexpression was correlated with microvascular invasion, poor differentiation and higher tumor-node-metastasis stage. HCC patients with positive ACP5 expression had poorer prognoses than those with negative ACP5 expression. A multivariate analysis revealed that ACP5 expression was an independent and significant risk factor for disease recurrence and reduced-patient survival following curative resection. Transwell assays and an orthotopic metastatic model showed that the upregulation of ACP5 promoted HCC invasion and lung metastasis, whereas ACP5 knockdown inhibited these processes. The knockdown of ACP5 significantly attenuated FoxM1-enhanced invasion and lung metastasis. Immunohistochemistry revealed that ACP5 expression was positively correlated with FoxM1 expression in human HCC tissues, and their coexpression was associated with poor prognoses. In summary, ACP5 is a direct transcriptional and functional target of FoxM1. This novel FoxM1/ACP5 signaling pathway promotes HCC metastasis and may be a candidate biomarker for prognosis and a target for new therapies.

FoxM1 is associated with poor prognosis of non-small cell lung cancer patients through promoting tumor metastasis

Background

FoxM1 has been reported to be important in initiation and progression of various tumors. However, whether FoxM1 has any indication for prognosis in non-small cell lung cancer patients remains unclear.

Methodology/Principal Findings

In this study, FoxM1 expression in tumor cells was examined first by immunohistochemistry in 175 NSCLC specimens, the result of which showed that FoxM1 overexpression was significantly associated with positive smoking status (P = 0.001), poorer tissue differentiation (P = 0.0052), higher TNM stage (P<0.0001), lymph node metastasis (P<0.0001), advanced tumor stage (P<0.0001), and poorer prognosis (P<0.0001). Multivariable analysis showed that FoxM1 expression increased the hazard of death (hazard ratio, 1.899; 95% CI, 1.016–3.551). Furthermore, by various in vitro and in vivo experiments, we showed that targeted knockdown of FoxM1 expression could inhibit the migratory and invasive abilities of NSCLC cells, whereas enforced expression of FoxM1 could increased the invasion and migration of NSCLC cells. Finally, we found that one of the cellular mechanisms by which FoxM1 promotes tumor metastasis is through inducing epithelial-mesenchymal transition (EMT) program.

Conclusions

These results suggested that FoxM1 overexpression in tumor tissues is significantly associated with the poor prognosis of NSCLC patients through promoting tumor metastasis.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

Overexpression of forkhead box C1 promotes tumor metastasis and indicates poor prognosis in hepatocellular carcinoma

Recurrence and metastasis remain the most common causes of lethal outcomes in hepatocellular carcinoma (HCC) after curative resection. Thus, it is critical to discover the mechanisms underlying HCC metastasis. Forkhead box C1 (FoxC1), a member of the Fox family of transcription factors, induces epithelial-mesenchymal transition (EMT) and promotes epithelial cell migration. However, the role of FoxC1 in the progression of HCC remains unknown. Here, we report that FoxC1 plays a critical role in HCC metastasis. FoxC1 expression was markedly higher in HCC tissues than in adjacent noncancerous tissues. HCC patients with positive FoxC1 expression had shorter overall survival times and higher recurrence rates than those with negative FoxC1 expression. FoxC1 expression was an independent, significant risk factor for recurrence and survival after curative resection. FoxC1 overexpression induced changes characteristic of EMT and an increase in HCC cell invasion and lung metastasis. However, FoxC1 knockdown inhibited these processes. FoxC1 transactivated Snai1 expression by directly binding to the Snai1 promoter, thereby leading to the inhibition of E-cadherin transcription. Knockdown of Snai1 expression significantly attenuated FoxC1-enhanced invasion and lung metastasis. FoxC1 expression was positively correlated with Snai1 expression, but inversely correlated with E-cadherin expression in human HCC tissues. Additionally, a complementary DNA microarray, serial deletion, site-directed mutagenesis, and a chromatin immunoprecipitation assay confirmed that neural precursor cell expressed, developmentally down-regulated 9 (NEDD9), which promotes the metastasis of HCC cells, is a direct transcriptional target of FoxC1 and is involved in FoxC1-mediated HCC invasion and metastasis.

CONCLUSIONS

FoxC1 may promote HCC metastasis through the induction of EMT and the up-regulation of NEDD9 expression. Thus, FoxC1 may be a candidate prognostic biomarker and a target for new therapies.

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.

Aberrant overexpression of FOXM1 transcription factor plays a critical role in lung carcinogenesis induced by low doses of arsenic

Environmental or occupational exposure to low doses of arsenic induces a series of health problems including cancer. The molecular events in arsenic-induced carcinogenicity remain to be defined. In the NuLi-1 immortalized human lung epithelial cell line with p53 and pRb deficiency, exposure to low doses of arsenic trioxide for 72 h promoted cell proliferation and upregulated the gene transcription levels of FOXM1, CDC6, CDC25A, and cyclin D1, which are both critical cell cycle regulatory genes and proto-oncogenes. Continuous in vitro exposure to 1 µM arsenic trioxide for 34 wks induced malignant cell transformation, as evidenced by enhanced anchorage-independent cell growth. The expression of FOXM1, CDC6, CDC25A, and Cyclin D1 was dynamically elevated at the gene transcription and protein levels in the process of cell transformation. The carcinogenic ability of transformed cell colonies coincides with the expression levels of FOXM1 in in vitro anchorage-independent growth assays and in vivo tumor xenograft formation assays. In reverse, the knockdown of FOXM1 in lung adenocarcinoma A549 cells or arsenic-transformed NuLi-1 cells significantly decreased anchorage-independent cell growth and tumor xenograft formation. The transformed NuLi-1 cells showed genomic instability in the form of copy number variation (CNV) at chromosome 1, 5, 6, 18, and 20, but not loss of heterozygosity (LOH). These results showed for the first time that chronic exposure to low doses of arsenic trioxide promoted lung carcinogenicity, in part by aberrantly upregulating FOXM1 and its associated oncogenes, when the tumor suppressor genes p53 and pRb were inactivated.

Casticin induces growth suppression and cell cycle arrest through activation of FOXO3a in hepatocellular carcinoma

Casticin, a polymethoxyflavone, has been reported to exert anticancer activities. The objectives of this study were to examine the molecular mechanisms by which casticin induces the growth inhibition and cell cycle arrest in human hepatocellular carcinoma (HCC) cells. The HCC cell lines Hep G2 and PLC/PRF/5 were cultured in vitro. The growth inhibitory effects of casticin were evaluated using clonogenic assays. The distribution of phases in the cell cycle was analyzed using flow cytometry (FCM) analysis with propidium iodide (PI) staining. Multiple molecular techniques, such as western blotting and gene transfection, were used to explore the molecular mechanisms of action. Our data demonstrated that casticin significantly inhibited cell viability and colony formation in HCC cells. Furthermore, it induced cell cycle arrest in the G2/M phase. Casticin inhibited phosphorylation of the FOXO3a protein and decreased the expression of FoxM1 and its downstream genes, such as cyclin-dependent kinase (CDK1), cdc25B and cyclin B and increased the expression of p27KIP1. Silencing of FOXO3a expression by small interfering RNA (siRNA) transfection clearly attenuated the inhibitory effects of casticin on FOXM1 expression and cell growth. Our findings provided clear evidence that casticin induces growth suppression and cell cycle arrest through inhibition of FOXO3a phosphorylation causing inactivation of FOXM1 in HCC cells.

Upregulated FoxM1 expression induced by hepatitis B virus X protein promotes tumor metastasis and indicates poor prognosis in hepatitis B virus-related hepatocellular carcinoma

BACKGROUND & AIMS

Forkhead box M1 (FoxM1) is a master regulator of tumor metastasis that plays an important role in the development of hepatocellular carcinoma (HCC). However, whether or not FoxM1 contributes to the progression of HBV-associated HCC (HBV-HCC) remains unknown. Therefore, we aimed at investigating the clinicopathologic significance of FoxM1 in HBV-HCC and the potential role of FoxM1 in hepatitis B virus X (HBx)-mediated invasiveness and metastasis.

METHODS

The expression of FoxM1 and its functional targets matrix metalloproteinase-7 (MMP-7), RhoC, and Rho-kinase 1 (ROCK1) in human HBV-HCC tissues was detected by immunohistochemistry. Luciferase reporter, chromatin immunoprecipitation, and electrophoretic mobility shift assays were used to measure the transcriptional regulation of FoxM1 promoter by HBx. The effect of FoxM1 on HBx-mediated invasiveness and metastasis was analyzed by transwell assays and an orthotopic metastatic model.

RESULTS

FoxM1 overexpression correlated with multiple malignant characteristics and indicated poor prognosis of HBV-HCC patients. FoxM1 expression was an independent factor affecting the recurrence and survival of patients with HBV-HCC after surgical resection. FoxM1 promoted hepatoma cell invasion and metastasis by promoting MMP-7, RhoC, and ROCK1 expression, while FoxM1 overexpression was associated with elevated expressions of these proteins in HBV-HCC tissues. HBx upregulated FoxM1 expression through the ERK/CREB pathway, and FoxM1 inhibition significantly decreased HBx-enhanced hepatoma cell invasion in vitro and lung metastasis in vivo.

CONCLUSIONS

We report a new molecular mechanism for HBV-associated hepatocarcinogenesis that involves the activation of FoxM1 expression by HBx through the ERK/CREB pathway, thereby leading to invasion and metastasis of hepatoma cells.

The TNF-α/ROS/HIF-1-induced upregulation of FoxMI expression promotes HCC proliferation and resistance to apoptosis

The proliferation-specific transcription factor Forkhead box M1 (FoxM1) acts as a master regulator of cancer cell growth and survival and plays an important role in the development of hepatocellular carcinoma. However, the molecular mechanisms that regulate FoxM1 expression remain largely unknown. In the current study, we demonstrated that tumor necrosis factor (TNF)-αα induced FoxM1 expression and transactivated its promoter activity in hepatoma cells. Serial 5" deletion and site-directed mutagenesis revealed that the induction of FoxM1 expression by TNF-α was dependent upon the hypoxia-inducible factor 1 (HIF1)-1 and HIF1-3/4 binding sites within the FoxM1 promoter. Furthermore, at the transcriptional level, the stabilization of HIF-1α via reactive oxygen species generation led to the binding of HIF-1α to the FoxM1 promoter and resulted in increased FoxM1 expression. The inhibition of both HIF-1α expression and reactive oxygen species generation significantly decreased TNF-α-induced FoxM1 overexpression. Consequently, the upregulation of FoxM1 promoted the proliferation of hepatoma cells and enhanced their resistance to TNF-α-induced apoptosis. Consistently, there was a positive correlation between HIF-1α and FoxM1 expression in 406 human hepatocellular carcinoma tissues, and the combination of these two parameters was a powerful predictor of poor prognosis in hepatocellular carcinoma patients after curative resection. Here, we report a new molecular mechanism by which FoxM1 expression is regulated by the TNF-α/reactive oxygen species/HIF-1 pathway, and this mechanism results in the proliferation of hepatoma cells and their resistance to apoptosis.