A novel function of tissue factor pathway inhibitor-2 (TFPI-2) in human glioma invasion

Tissue factor pathway inhibitor 2: Current understanding, challenges, and future perspectives

AIM

Tissue factor pathway inhibitor 2 (TFPI2) is a structural homolog of tissue factor pathway inhibitor 1 (TFPI1). Since TFPI2 is a placenta-derived protein, dynamic changes in TFPI2 levels may be related to pregnancy-related diseases. Furthermore, TFPI2 has been reported to be a novel serum biomarker for detecting ovarian cancer, especially clear cell carcinoma (CCC). This review aims to summarize the current knowledge on the biological function of TFPI2, highlight the major challenges that remain to be addressed, and discuss future research directions.

METHODS

Papers published up to March 31, 2023 in the PubMed and Google Scholar databases were included in this review. We also provide novel complementary information to what is known about the action of TFPI2.

RESULTS

Since TFPI2 concentrations in the blood of pregnant women, preeclampsia patients, and cancer patients vary greatly, its pathophysiological functions have attracted attention. Downregulation of TFPI2, a tumor-suppressor gene, by hypermethylation may contribute to the progression of several cancers. On the other hand, TFPI2 overexpressed in CCC is a risk factor for the development of thrombosis, possibly through inhibition of plasmin activity. However, agreement on the biological function of TFPI2 is still lacking and there are many scientific questions to be addressed. In particular, the lack of international standardization for the quantification of TFPI2 concentrations makes it difficult for researchers and clinicians to evaluate, pool, and compare data from different studies across countries.

DISCUSSION

This review summarizes current understandings and challenges in TFPI2 research and discusses future perspectives.

Kunitz-type protease inhibitor TFPI2 remodels stemness and immunosuppressive tumor microenvironment in glioblastoma

Glioblastoma (GBM) tumors consist of multiple cell populations, including self-renewing glioblastoma stem cells (GSCs) and immunosuppressive microglia. Here we identified Kunitz-type protease inhibitor TFPI2 as a critical factor connecting these cell populations and their associated GBM hallmarks of stemness and immunosuppression. TFPI2 promotes GSC self-renewal and tumor growth via activation of the c-Jun N-terminal kinase-signal transducer and activator of transcription (STAT)3 pathway. Secreted TFPI2 interacts with its functional receptor CD51 on microglia to trigger the infiltration and immunosuppressive polarization of microglia through activation of STAT6 signaling. Inhibition of the TFPI2-CD51-STAT6 signaling axis activates T cells and synergizes with anti-PD1 therapy in GBM mouse models. In human GBM, TFPI2 correlates positively with stemness, microglia abundance, immunosuppression and poor prognosis. Our study identifies a function for TFPI2 and supports therapeutic targeting of TFPI2 as an effective strategy for GBM.

Bioinformatics of Differentially Expressed Genes in Phorbol 12-Myristate 13-Acetate-Induced Megakaryocytic Differentiation of K562 Cells by Microarray Analysis

Megakaryocytes are large hematopoietic cells present in the bone marrow cavity, comprising less than 0.1% of all bone marrow cells. Despite their small number, megakaryocytes play important roles in blood coagulation, inflammatory responses, and platelet production. However, little is known about changes in gene expression during megakaryocyte maturation. Here we identified the genes whose expression was changed during K562 leukemia cell differentiation into megakaryocytes using an Affymetrix GeneChip microarray to determine the multifunctionality of megakaryocytes. K562 cells were differentiated into mature megakaryocytes by treatment for 7 days with phorbol 12-myristate 13-acetate, and a microarray was performed using RNA obtained from both types of cells. The expression of 44,629 genes was compared between K562 cells and mature megakaryocytes, and 954 differentially expressed genes (DEGs) were selected based on a p-value < 0.05 and a fold change >2. The DEGs was further functionally classified using five major megakaryocyte function-associated clusters—inflammatory response, angiogenesis, cell migration, extracellular matrix, and secretion. Furthermore, interaction analysis based on the STRING database was used to generate interactions between the proteins translated from the DEGs. This study provides information on the bioinformatics of the DEGs in mature megakaryocytes after K562 cell differentiation.

Toward an understanding of tissue factor pathway inhibitor-2 as a novel serodiagnostic marker for clear cell carcinoma of the ovary

AIMS

Tissue factor pathway inhibitor (TFPI)-2 has recently emerged as a serodiagnostic marker for patients with epithelial ovarian cancer (EOC), especially clear cell carcinoma (CCC). This review discusses the biological properties of TFPI-2 and why serum levels are elevated in CCC patients.

METHODS

A comprehensive literature search was conducted in PubMed up until March, 2021.

RESULTS

TFPI-2 is a Kunitz-type protease inhibitor and negatively regulates the enzymatic activities, such as plasmin. TFPI-2 has been characterized as a tumor suppressor gene and was frequently downregulated through promoter hypermethylation in various human cancers. In contrast, TFPI-2 was overexpressed only in CCC. TFPI-2 may be involved in the pathophysiology of CCC, possibly through regulation of coagulation system, stabilization of extracellular matrix (ECM), and induction of intracellular signal transduction. TFPI-2 suppresses tissue factor-induced hypercoagulation in a hypoxic environment. TFPI-2, secreted by CCC cells, platelets, and adjacent vascular endothelial cells, may suppress tumor growth and invasion through ECM remodeling. Nuclear TFPI-2 may suppress matrix metalloproteinase production via transcription factors and modulate caspase-mediated cell apoptosis. CCC cells may upregulate the TFPI-2 expression to adapt to survival in the demanding environment. TFPI-2 is secreted by CCC cells and enters the systemic circulation, resulting in elevated blood levels.

DISCUSSION

Serum TFPI-2 reflects the overexpression of TFPI-2 in CCC tissues and is a potential serodiagnostic marker. Further research is needed to explore the expression, clinical significance, biological function, and potential mechanism of TFPI-2 in CCC.

TFPI2 Promotes Perivascular Migration in an Angiotropism Model of Melanoma

Purpose

Angiotropism is the process by which cancer cells attach to and migrate along blood vessels to acquire vasculature, disseminate, and metastasize. However, the molecular basis for such vessel–tumor interactions has not been fully elucidated, partly due to limited experimental models. In this study, we aimed to observe and explore the molecular mechanism underlying angiotropism in melanoma.

Methods

To monitor the interactions of human melanoma cells with the vasculature in vivo, a murine coxenograft model was employed by co-injecting highly and poorly invasive melanoma cells subcutaneously. To identify key pathways and genes involved in the angiotropic phenotype of melanoma, analysis of differentially expressed genes (DEGs) and gene set enrichment analysis (GSEA) were performed. The role of tissue factor pathway inhibitor 2 (TFPI2) in angiotropism was evaluated by immunostaining, adhesion assay, shRNA, and in vivo tumorigenicity. Angiotropism and TFPI2 expression were examined in surgical specimens of melanoma by immunohistochemical staining. Data from The Cancer Genome Atlas (TCGA) were analyzed to explore the expression and prognostic implications of TFPI2 in uveal and cutaneous melanoma.

Results

Highly invasive melanoma cells spread along the branches of intratumor blood vessels to the leading edge of invasion in the coxenograft model, resembling angiotropic migration. Mechanisms underlying angiotropism were primarily associated with molecular function regulators, regulation of cell population proliferation, developmental processes, cell differentiation, responses to cytokines and cell motility/locomotion. TFPI2 downregulation weakened the perivascular migration of highly invasive melanoma cells. High levels of TFPI2 were correlated with worse and better survival in uveal and cutaneous melanoma, respectively.

Conclusion

These results provide a straightforward in vivo model for the observation of angiotropism and suggest that TFPI2 could inhibit the angiotropic phenotype of melanoma.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

microRNAs and Markers of Neutrophil Activation as Predictors of Early Incidental Post-Surgical Pulmonary Embolism in Patients with Intracranial Tumors

Venous thromboembolism (VTE) is a common complication of cancer that severely increases morbidity and mortality. Patients with intracranial tumors are more likely to develop VTE than patients with cancers at other sites. Conversely, limited tools exist to identify patients with high thrombotic risk. Upon activation, neutrophils release their content through different mechanisms triggering thrombosis. We explored the ability of microRNAs (miRNAs) and plasma markers of neutrophil activation measured before surgery to predict the risk of early post-surgical pulmonary embolism (PE) in glioma and meningioma patients. We recruited and prospectively followed 50 patients with glioma and 50 with meningioma, 34% of whom in each group developed an early objectively-diagnosed post-surgical PE. We measured miRNA expression and neutrophil markers (cell-free DNA, nucleosomes, calprotectin and myeloperoxidase) before surgery. In glioma patients, we adjusted and validated a predictive model for post-surgical PE with 6 miRNAs: miR-363-3p, miR-93-3p, miR-22-5p, miR-451a, miR-222-3p and miR-140-3p (AUC = 0.78; 95% Confidence Interval (CI) [0.63, 0.94]) and another with cfDNA and myeloperoxidase as predictors (AUC = 0.71; 95% CI [0.52, 0.90]). Furthermore, we combined both types of markers and obtained a model with myeloperoxidase and miR-140-3p as predictors (AUC = 0.79; 95% CI [0.64, 0.94]). In meningioma patients we fitted and validated a predictive model with 6 miRNAs: miR-29a-3p, miR-660-5p, miR-331-3p, miR-126-5p, miR-23a-3p and miR-23b-3p (AUC = 0.69; 95% CI [0.52, 0.87]). All our models outperformed the Khorana score. This is the first study that analyzes the capability of plasma miRNAs and neutrophil activation markers to predict early post-surgical PE in glioma and meningioma patients. The estimation of the thrombotic risk before surgery may promote a tailored thromboprophylaxis in a selected group of high-risk patients, in order to minimize the incidence of PE and avoid bleedings.

Irisin, an exercise myokine, potently suppresses tumor proliferation, invasion, and growth in glioma

Glioblastoma multiforme is the most common and aggressive glial tumor with poor prognosis. Importantly, effective treatment options for glioblastoma are unmet needs. Obesity and low physical activity have been linked with a high risk of cancer, and exercise is related to delayed cancer development and progression. Epidemiological studies have revealed a correlation between exercise and the survival rate of patients with glioblastoma. Nevertheless, the mechanisms by which exercise exerts its anticancer effects in glioblastoma remain unclear. Here, we found that irisin, an exercise-induced myokine, induced G₂ /M cell cycle arrest and increased p21 levels in glioblastoma cells, leading to the inhibition of cell proliferation. In addition, irisin inhibited glioblastoma cell invasion by upregulating TFPI-2 and even reversed the aggressive tumor phenotype promoted by co-cultivation with cancer-associated adipocytes. Furthermore, irisin retarded xenograft glioblastoma tumor growth, and radiolabeled irisin demonstrated specific tumor-targeting capability in vivo. Therefore, this study identified one potential molecular mechanism by which exercise prevents cancer progression via irisin. Intriguingly, irisin has the potential to be developed as a molecular imaging and therapeutic anticancer agent.

Higher methylation subtype of malignant melanoma and its correlation with thicker progression and worse prognosis

Malignant melanoma (MM) is the most life‐threatening disease among all skin malignancies, and recent genome‐wide studies reported BRAF, RAS, and NF1 as the most frequently mutated driver genes. While epigenetic aberrations are known to contribute to the oncogenic activity seen in various cancers, their role in MM has not been fully investigated. To investigate the role of epigenetic aberrations in MM, we performed genome‐wide DNA methylation analysis of 51 clinical MM samples using Infinium 450k beadarray. Hierarchical clustering analysis stratified MM into two DNA methylation epigenotypes: high‐ and low‐methylation subgroups. Tumor thickness was significantly greater in case of high‐methylation tumors than low‐methylation tumors (8.3 ± 5.3 mm vs 4.5 ± 2.9 mm, P = .003). Moreover, prognosis was significantly worse in high‐methylation cases (P = .03). Twenty‐seven genes were found to undergo significant and frequent hypermethylation in high‐methylation subgroup, where TFPI2 was identified as the most frequently hypermethylated gene. MM cases with lower expression levels of TFPI2 showed significantly worse prognosis (P = .001). Knockdown of TFPI2 in two MM cell lines, CHL‐1 and G361, resulted in significant increases of cell proliferation and invasion. These indicate that MM can be stratified into at least two different epigenetic subgroups, that the MM subgroup with higher DNA methylation shows a more progressive phenotype, and that methylation of TFPI2 may contribute to the tumor progression of MM.

Increased placental expression of Placental Protein 5 (PP5) / Tissue Factor Pathway Inhibitor-2 (TFPI-2) in women with preeclampsia and HELLP syndrome: Relevance to impaired trophoblast invasion?

INTRODUCTION

Placental Protein 5 (PP5)/Tissue Factor Pathway Inhibitor-2 (TFPI-2) is an extracellular matrix-associated protein mainly expressed by the syncytiotrophoblast that may regulate trophoblast invasion. Our aim was to study placental PP5/TFPI-2 expression and its relation to placental pathology in various forms of preeclampsia and HELLP syndrome.

METHODS

Placental and maternal blood specimens were collected at the time of delivery from the same women in the following groups: 1) early controls; 2) early preeclampsia; 3) early preeclampsia with HELLP syndrome; 4) late controls; and 5) late preeclampsia. After histopathological examination, placental specimens were immunostained with polyclonal anti-PP5/TFPI-2 antibody on Western blot and tissue microarray immunohistochemistry. Placental PP5/TFPI-2 immunoscores were assessed manually and with a semi-automated method. Maternal sera were immunoassayed for PP5/TFPI-2.

RESULTS

PP5/TFPI-2 was localized to the cytoplasm of syncytiotrophoblast. Manual and semi-automated PP5/TFPI-2 immunoscores were higher in early preeclampsia with or without HELLP syndrome but not in late preeclampsia than in respective controls. In patients with preeclampsia, the correlation of placental PP5/TFPI-2 expression with maternal vascular malperfusion score of the placenta was positive while it was negative with birthweight and placental weight. Maternal serum PP5/TFPI-2 concentration was higher in early preeclampsia and it tended to be higher in early preeclampsia with HELLP syndrome than in early controls.

DISCUSSION

Our findings suggest that an increased placental PP5/TFPI-2 expression may be associated with abnormal placentation in early preeclampsia, with or without HELLP syndrome.

Implication of the Kallikrein-Kinin system in neurological disorders: Quest for potential biomarkers and mechanisms

Neurological disorders represent major health concerns in terms of comorbidity and mortality worldwide. Despite a tremendous increase in our understanding of the pathophysiological processes involved in disease progression and prevention, the accumulated knowledge so far resulted in relatively moderate translational benefits in terms of therapeutic interventions and enhanced clinical outcomes. Aiming at specific neural molecular pathways, different strategies have been geared to target the development and progression of such disorders. The kallikrein-kinin system (KKS) is among the most delineated candidate systems due to its ubiquitous roles mediating several of the pathophysiological features of these neurological disorders as well as being implicated in regulating various brain functions. Several experimental KKS models revealed that the inhibition or stimulation of the two receptors of the KKS system (B1R and B2R) can exhibit neuroprotective and/or adverse pathological outcomes. This updated review provides background details of the KKS components and their functions in different neurological disorders including temporal lobe epilepsy, traumatic brain injury, stroke, spinal cord injury, Alzheimer's disease, multiple sclerosis and glioma. Finally, this work will highlight the putative roles of the KKS components as potential neurotherapeutic targets and provide future perspectives on the possibility of translating these findings into potential clinical biomarkers in neurological disease.

Methylation of tissue factor pathway inhibitor 2 as a prognostic biomarker for hepatocellular carcinoma after hepatectomy

BACKGROUND AND AIM

Methylation of tissue factor pathway inhibitor 2 (TFPI2) gene has been detected in hepatocellular carcinoma (HCC). However, the clinicopathologcial significance and prognostic value of TFPI2 methylation in HCC remains largely unknown. This study aimed to investigate the prognostic value of TFPI2 methylation in HCC after hepatectomy.

METHODS

Methylation status of TFPI2 gene was examined in 178 surgical specimens of HCC and 20 normal liver samples using methylation-specific polymerase chain reaction.

RESULTS

Methylation of TFPI2 gene was detected in 44.9% (80 of 178) of primary HCC samples, 10.7% (19 of 178) of the corresponding non-tumorous liver samples, and 5.0% (1/20) of the normal liver samples. The mRNA concentrations of TFPI2 in primary HCC tissues were significantly lower than those in corresponding non-tumorous liver tissues and those in normal liver tissues. TFPI2 methylation was significantly associated with higher TNM stage. Patients with TFPI2 methylation demonstrated a significantly poorer prognosis than those without TFPI2 methylation for both overall survival and disease-free survival (P < 0.001, respectively). Multivariate analyses confirmed that TFPI2 methylation was an independent prognostic factor for both overall survival (P = 0.002) and disease-free survival (P = 0.000) in HCC after hepatectomy. Moreover, TFPI2 methylation was found to be the only independent predictor for early tumor recurrence of HCC after resection based on multivariate analysis (P = 0.002).

CONCLUSIONS

Methylation of TFPI2 predicts high risk of advanced tumor stage, early tumor recurrence, and poor prognosis, and it could be a potential prognostic biomarker in patients with HCC after hepatectomy.

Upregulated matrix metalloproteinase-2 and downregulated tissue factor pathway inhibitor-2 are risk factors for lymph node metastasis and perineural invasion in pancreatic carcinoma

BACKGROUND

Dysregulated expression of matrix metalloproteinase (MMP)-2 and tissue factor pathway inhibitor (TFPI)-2 is closely associated with tumorigenesis and tumor progression. The aim of this work was to determine the predictive values of MMP-2 and TFPI-2 in identifying lymph node metastasis (LNM) and perineural invasion (PNI) in pancreatic carcinoma.

METHODS

Formalin-fixed and paraffin-embedded tissue samples containing pancreatic carcinoma tissues and their corresponding para-carcinoma tissues were obtained from 122 patients with pancreatic carcinoma. The expression levels of MMP-2 and TFPI-2 were evaluated by immunohistochemistry. The roles of MMP-2 and TFPI-2 in predicting LNM and PNI in pancreatic carcinoma were analyzed.

RESULTS

The level of MMP-2 expression was markedly increased in pancreatic carcinoma tissues (76.9%) compared with para-carcinoma tissues (29.2%; P<0.05). In contrast, there was obviously decreased TFPI-2 expression level in pancreatic carcinoma tissues (29.2%) compared with para-carcinoma tissues (77.7%; P<0.001). Additionally, MMP-2 expression was significantly positively correlated with LNM (r=0.468, P<0.01) and PNI (r=0.637, P<0.01). In contrast, TFPI-2 expression was strongly negatively correlated with LNM (r=-0.396, P<0.001) and PNI (r=-0.460, P<0.001). Logistic regression analysis showed that high MMP-2 expression and low TFPI-2 expression acted as independent predictors for LNM and PNI in pancreatic carcinoma.

CONCLUSION

Taken together, our findings suggest that upregulated MMP-2 and downregulated TFPI-2 serve as useful predictors for a high risk of LNM and PNI. Obtaining information on the expression of MMP-2 and TFPI-2 before surgery may predict the occurrence of LNM and PNI, thereby permitting reasonable and effective surgical treatment for patients with pancreatic carcinoma.

Detection of TFPI2 methylation in the serum of hepatocellular carcinoma patients

BACKGROUND

DNA methylation plays a key role in hepatocellular carcinogenesis and progression. Analysis of aberrant methylation in serum DNA might provide a strategy for noninvasive detection of hepatocellular carcinoma (HCC).

METHODS

To explore the feasibility of this approach, we compared TFPI2 methylation status in serum samples of HCC, chronic hepatitis B (CHB) patients and normal control groups using methylation-specific polymerase chain reaction.

RESULTS

Our results showed that the percentage of serum TFPI2 promoter methylation was significantly higher in the HCC group (46.5 %, 20/43) compared with the CHB group (16.7 %, 4/24; p = 0.015) and the normal control group (19.2 %, 5/26; p = 0.022), respectively, indicating that TFPI2 methylation frequently existed in the serum of HCC patients. In our study, the detection rate of HCC using serum TFPI2 methylation was 46.5 % (20/43), which was quite close to the reported detection rate of α-fetoprotein (54 %). In cases where we combined both markers, the detection rate was 61.0 %, suggesting that serum TFPI2 methylation could be used as a potential marker for noninvasive detection of HCC. Then, we evaluated the correlation between the serum TFPI2 methylation status of HCC patients and their clinicopathological parameters. Patients with advanced TNM stage (III-IV) showed a significantly elevated serum methylation percentage of TFPI2 in comparison with those with early TNM stage (I-II) (p = 0.025). Moreover, TFPI2 methylation was observed more frequently according to the progression of TNM stage.

CONCLUSIONS

Our present study suggested that TFPI2 methylation in serum tended to be detected more easily in patients with advanced HCC and might be used as a predictor of HCC progression.

The interaction of the second Kunitz-type domain (KD2) of TFPI-2 with a novel interaction partner, prosaposin, mediates the inhibition of the invasion and migration of human fibrosarcoma cells

TFPI-2 (tissue factor pathway inhibitor-2) has recently been recognized as a new tumour suppressor gene. Low expression of this protein in several types of cancers allows for enhanced tumour growth, invasion and metastasis. To investigate the molecular mechanism responsible for the tumour-suppressor effects of TFPI-2, we performed yeast two-hybrid analysis and identified PSAP (prosaposin) as a TFPI-2-interacting partner. This interaction was confirmed by co-immunoprecipitation and immunofluorescence. The region of TFPI-2 that interacts with PSAP is located in the KD2 (Kunitz-type domain 2). Further study showed that PSAP does not affect the function of TFPI-2 as a serine proteinase inhibitor, but that TFPI-2 could inhibit the invasion-promoting effects of PSAP in human HT1080 fibrosarcoma cells. The results of the present study revealed that TFPI-2 interacts with PSAP, which may play an important role in the physiology and pathology of diseases such as cancer.

TFPI-2 is a putative tumor suppressor gene frequently inactivated by promoter hypermethylation in nasopharyngeal carcinoma

Background

Epigenetic silencing of tumor suppressor genes play important roles in NPC tumorgenesis. Tissue factor pathway inhibitor-2 (TFPI-2), is a protease inhibitor. Recently, TFPI-2 was suggested to be a tumor suppressor gene involved in tumorigenesis and metastasis in some cancers. In this study, we investigated whether TFPI-2 was inactivated epigenetically in nasopharyngeal carcinoma (NPC).

Methods

Transcriptional expression levels of TFPI-2 was evaluated by RT-PCR. Methylation status were investigated by methylation specific PCR and bisulfate genomic sequencing. The role of TFPI-2 as a tumor suppressor gene in NPC was addressed by re-introducing TFPI-2 expression into the NPC cell line CNE2.

Results

TFPI-2 mRNA transcription was inactivated in NPC cell lines. TFPI-2 was aberrantly methylated in 66.7% (4/6) NPC cell lines and 88.6% (62/70) of NPC primary tumors, but not in normal nasopharyngeal epithelia. TFPI-2 expression could be restored in NPC cells after demethylation treatment. Ectopic expression of TFPI-2 in NPC cells induced apoptosis and inhibited cell proliferation, colony formation and cell migration.

Conclusions

Epigenetic inactivation of TFPI-2 by promoter hypermethylation is a frequent and tumor specific event in NPC. TFPI-2 might be considering as a putative tumor suppressor gene in NPC.

Tissue factor pathway inhibitor 2 (TFPI2) is frequently silenced by aberrant promoter hypermethylation in gastric cancer

Aberrant methylation of promoter CpG islands is associated with transcriptional inactivation of tumor-suppressor genes in cancer. TFPI2, a Kunitz-type serine proteinase inhibitor, has been identified as a putative tumor-suppressor gene from genome-wide screening for aberrant methylation, using a microarray combined with the methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dCyd) in various types of tumors. We assessed the methylation status of TFPI2 and investigated its expression pattern in human primary gastric cancer (GC) tissues and in GC cell lines. Hypermethylation of the promoter CpG island, which was observed in more or less all of GC cell lines, was prevalent in a high proportion of primary GC tissues (15/18, or 83%), compared with noncancerous (4/18, or 22%) or normal (0/3, or 0%) stomach tissues, and expression of TFPI2 mRNA was reduced in 7 of the 17 primary GC tissues (41%). Moreover, immunohistochemical analyses showed decreased levels of TFPI-2 protein, compared with adjacent noncancerous tissues in 8 of the 20 primary GC tissues examined (40%). TFPI2 mRNA expression was restored in gene-silenced GC cells after treatment with 5-aza-dCyd. Aberrant methylation of TFPI2 promoter CpG island occurred not only in GC cells but also in primary GC tissues at a high frequency, suggesting that epigenetic silencing of TFPI2 may contribute to gastric carcinogenesis.

Multifunctional roles of enolase in Alzheimer's disease brain: beyond altered glucose metabolism

Enolase enzymes are abundantly expressed, cytosolic carbon-oxygen lyases known for their role in glucose metabolism. Recently, enolase has been shown to possess a variety of different regulatory functions, beyond glycolysis and gluconeogenesis, associated with hypoxia, ischemia, and Alzheimer's disease (AD). AD is an age-associated neurodegenerative disorder characterized pathologically by elevated oxidative stress and subsequent damage to proteins, lipids, and nucleic acids, appearance of neurofibrillary tangles and senile plaques, and loss of synapse and neuronal cells. It is unclear if development of a hypometabolic environment is a consequence of or contributes to AD pathology, as there is not only a significant decline in brain glucose levels in AD, but also there is an increase in proteomics identified oxidatively modified glycolytic enzymes that are rendered inactive, including enolase. Previously, our laboratory identified alpha-enolase as one the most frequently up-regulated and oxidatively modified proteins in amnestic mild cognitive impairment (MCI), early-onset AD, and AD. However, the glycolytic conversion of 2-phosphoglycerate to phosphoenolpyruvate catalyzed by enolase does not directly produce ATP or NADH; therefore it is surprising that, among all glycolytic enzymes, alpha-enolase was one of only two glycolytic enzymes consistently up-regulated from MCI to AD. These findings suggest enolase is involved with more than glucose metabolism in AD brain, but may possess other functions, normally necessary to preserve brain function. This review examines potential altered function(s) of brain enolase in MCI, early-onset AD, and AD, alterations that may contribute to the biochemical, pathological, clinical characteristics, and progression of this dementing disorder.

Prognostic significance of tissue factor pathway inhibitor-2 in pancreatic carcinoma and its effect on tumor invasion and metastasis

Tissue factor pathway inhibitor-2 (TFPI-2) is a matrix-associated kunitz-type serine proteinase inhibitor that plays an important role in plasmin and trypsin-mediated activation of zymogen matrix metalloproteinases involved in tumor angiogenesis, invasion and metastasis. Earlier studies have shown that the production of TFPI-2 is downregulated during the progression of various tumors. To detect whether TFPI-2 can be expressed in human pancreatic carcinoma samples, to evaluate its prognostic significance on pancreatic carcinoma and to investigate its effect on tumor invasion and metastasis, we collected 9 normal pancreatic tissue samples and 41 pancreatic carcinoma samples and stably transfected the human pancreatic carcinoma cell line Panc-1 with a vector capable of expressing TFPI-2 gene. RT-PCR and Western blot analysis revealed that the expression of TFPI-2 in pancreatic carcinoma samples was markedly lower than that in normal pancreas samples, and there was no TFPI-2 expression in Panc-1 cell. Its expression was related with biological characters of pancreatic carcinoma. The results of Boyden chamber assay and orthotopic pancreatic carcinoma model showed that TFPI-2 could inhibit invasion and metastasis ability of pancreatic carcinoma in vitro and in vivo. Kaplan-Meier survival curve and Cox proportional hazards model assay identified TFPI-2 as an independent prognostic factor for pancreatic carcinoma. Our data suggest that TFPI-2 plays a significant role in the invasion and metastasis of pancreatic carcinoma cell in vitro and in vivo and is determined to be an important prognostic factor for pancreatic carcinoma patients.

Expression of tissue factor pathway inhibitor 2 in human pancreatic carcinoma and its effect on tumor growth, invasion, and migration in vitro and in vivo. J Surg Res. 2011;167:62-69. [PMID: 20018303 DOI: 10.1016/j.jss.2009.06.015]

Tissue factor pathway inhibitor 2 (TFPI-2), also known as placental protein and matrix-associated serine protease inhibitor, plays an important role in angiogenesis, intravascular fibrinolysis, wound healing, tumor invasion, metastasis by plasmin, and trypsin mediated activation of zymogen matrix metalloproteinases. To detect whether TFPI-2 can be expressed in human pancreatic carcinoma samples and to investigate its role in the growth, invasion, and metastasis of pancreatic carcinoma cell in vitro and in vivo, we collected eight normal pancreatic tissue samples and 50 pancreatic carcinoma samples, and stably transfected the human pancreatic carcinoma cell line Panc-1 with a vector capable of expressing TFPI-2 gene. RT-PCR and Western blot analysis revealed that the levels of TFPI-2 expression were markedly lower in pancreatic carcinoma samples compared with normal pancreas samples. The level of TFPI-2 protein was significantly higher in cells transfected with TFPI-2 gene than that in the untransfected cells. The results of MTT assay showed that TFPI-2 inhibited Panc-1 cells growth in vitro. The invasive capacity of the cells transfected with TFPI-2 gene was also markedly less than that of untransfected cells in vitro as determined by the Matrigel invasion/migration assay. Moreover, TFPI-2 inhibited tumor growth, invasion, and metastasis in vivo in an orthotopic pancreatic carcinoma model. Our findings suggest that TFPI-2 plays a significant role in the growth, invasion, and metastasis of pancreatic carcinoma cell in vitro and in vivo, and has potential in anticancer therapy.

Tissue factor pathway inhibitor-2 was repressed by CpG hypermethylation through inhibition of KLF6 binding in highly invasive breast cancer cells

Background

Tissue factor pathway inhibitor-2 (TFPI-2) is a matrix-associated Kunitz inhibitor that inhibits plasmin and trypsin-mediated activation of zymogen matrix metalloproteinases involved in tumor progression, invasion and metastasis. Here, we have investigated the mechanism of DNA methylation on the repression of TFPI-2 in breast cancer cell lines.

Results

We found that both protein and mRNA of TFPI-2 could not be detected in highly invasive breast cancer cell line MDA-MB-435. To further investigate the mechanism of TFPI-2 repression in breast cancer cells, 1.5 Kb TFPI-2 promoter was cloned, and several genetic variations were detected, but the promoter luciferase activities were not affected by the point mutation in the promoter region and the phenomena was further supported by deleted mutation. Scan mutation and informatics analysis identified a potential KLF6 binding site in TFPI-2 promoter. It was revealed, by bisulfite modified sequence, that the CpG island in TFPI-2 promoter region was hypermethylated in MDA-MB-435. Finally, using EMSA and ChIP assay, we demonstrated that the CpG methylation in the binding site of KLF-6 diminished the binding of KLF6 to TFPI-2 promoter.

Conclusion

In this study, we found that the CpG islands in TFPI-2 promoter was hypermethylated in highly invasive breast cancer cell line, and DNA methylation in the entire promoter region caused TFPI-2 repression by inducing inactive chromatin structure and decreasing KLF6 binding to its DNA binding sequence.

Restoration of tissue factor pathway inhibitor-2 in a human glioblastoma cell line triggers caspase-mediated pathway and apoptosis

PURPOSE

The induction of apoptotic pathways in cancer cells offers a novel and potentially useful approach to improve patient responses to conventional chemotherapy. Tissue factor pathway inhibitor-2 (TFPI-2) is a protease inhibitor that is abundant in the extracellular matrix and highly expressed in noninvasive cells but absent or undetectable in highly invasive human glioblastoma cells.

EXPERIMENTAL DESIGN

Using a recombinant adeno-associated viral vector carrying human TFPI-2 cDNA, we stably expressed TFPI-2 in U-251 cells, a highly invasive human glioblastoma cell line. Our previous studies showed that restoration of TFPI-2 in glioblastomas effectively prevents cell proliferation, angiogenesis, and tumor invasion. In this study, we determined whether TFPI-2 restoration could induce apoptosis through the caspase-mediated signaling pathway.

RESULTS

The results from nuclear chromatin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and fluorescence-activated cell sorting analysis showed increased apoptosis in U-251 cells after restoration of TFPI-2. Caspase-9 and caspase-3 activity assays showed increased activity, indicating enhanced apoptosis. Immunofluorescence for cleaved caspase-9 and caspase-3 depicted increased expression and colocalization of both molecules. Western blot analysis showed increased transcriptional activities of Fas ligand, tumor necrosis factor-alpha, Bax, Fas-associated death domain, and tumor necrosis factor receptor 1-associated death domain as well as elevated levels of cleaved caspases and poly(ADP-ribose) polymerase. Semiquantitative reverse transcription-PCR depicted increased expression of tumor necrosis factor-alpha and Fas ligand and the related death domains tumor necrosis factor receptor 1-associated death domain and Fas-associated death domain.

CONCLUSIONS

Taken together, these results show that restoration of TFPI-2 activates both intrinsic and extrinsic caspase-mediated, proapoptotic signaling pathways and induces apoptosis in U-251 cells. Furthermore, our study suggests that recombinant adeno-associated viral vector-mediated gene expression offers a novel tool for cancer gene therapy.

Structural templates predict novel protein interactions and targets from pancreas tumour gene expression data

MOTIVATION

Pancreatic ductal adenocarcinoma (PDAC) eludes early detection and is characterized by its aggressiveness and resistance to current therapies. A number of gene expression screens have been carried out to identify genes differentially expressed in cancerous tissue. To identify molecular markers and suitable targets, these genes have been mapped to protein interactions to gain an understanding at systems level.

RESULTS

Here, we take such a network-centric approach to pancreas cancer by re-constructing networks from known interactions and by predicting novel protein interactions from structural templates. The pathways we find to be largely affected are signal transduction, actin cytoskeleton regulation, cell growth and cell communication. Our analysis indicates that the alteration of the calcium pathway plays an important role in pancreas-specific tumorigenesis. Furthermore, our structural prediction method identifies 40 novel interactions including the tissue factor pathway inhibitor 2 (TFPI2) interacting with the transmembrane protease serine 4 (TMPRSS4). Since TMPRSS4 is involved in metastasis formation, we hypothesize that the upregulation of TMPRSS4 and the downregulation of its predicted inhibitor TFPI2 plays an important role in this process. Moreover, we examine the potential role of BVDU (RP101) as an inhibitor of TMPRSS4. BDVU is known to support apoptosis and prevent the acquisition of chemoresistance. Our results suggest that BVDU might bind to the active site of TMPRSS4, thus reducing its assistance in metastasis.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Silencing of tissue factor pathway inhibitor-2 gene in malignant melanomas

To identify tumor-suppressor genes inactivated by aberrant methylation of promoter CpG islands (CGIs) in human malignant melanomas, genes upregulated by treatment of cells with a demethylating agent, 5-aza-2'-deoxycytidine (5-aza-dC), were searched for using oligonucleotide microarrays in melanoma cell lines, HMV-I, MeWo and WM-115. Seventy-nine known genes with CGIs were identified as being upregulated (>or=16-fold), and 18 of them had methylation of their putative promoter CGIs in 1 or more of 8 melanoma cell lines. Among the 18 genes, TFPI-2, which is involved in repression of the invasive potential of malignant melanomas, was further analyzed. Its expression was repressed in a melanoma cell line with its complete methylation, and was restored by 5-aza-dC treatment. It was unmethylated in cultured neonatal normal epidermal melanocyte, and was induced by ultraviolet B. In surgical melanoma specimens, TFPI-2 methylation was detected in 5 of 17 metastatic site specimens (29%), while it was not detected in 20 primary site specimens (0%) (p=0.009). By immunohistochemistry, the 5 specimens with promoter methylation lacked immunoreactivity for TFPI-2. The results showed that TFPI-2 is silenced in human malignant melanomas by methylation of its promoter CGI and suggested that its silencing is involved in melanoma metastasis.

Tissue factor pathway inhibitor-2 as a frequently silenced tumor suppressor gene in hepatocellular carcinoma

In HCC, inactivation of tumor suppressor genes plays a significant role in carcinogenesis. Apart from deletions and mutations, growing evidence has indicated that epigenetic alterations including aberrant promoter methylation and histone deacetylation are also implicated in inactivation of tumor suppressor genes. The goal of this study was to identify epigenetically silenced candidate tumor suppressor genes in human HCC by comparing the changes in oligonucleotide microarray gene expression profiles in HCC cell lines upon pharmacological treatment with the demethylating agent 5-Aza-2'-deoxycytidine (5-Aza-dC). By analyzing the gene expression profiles, we selected tissue factor pathway inhibitor-2 (TFPI-2), a Kunitz-type serine protease inhibitor, for validation and further characterization. Our results showed that TFPI-2 was frequently silenced in human HCC and HCC cell lines. TFPI-2 was significantly underexpressed in approximately 90% of primary HCCs when compared with their corresponding nontumorous livers. TFPI-2 promoter methylation was detected in 80% of HCC cell lines and 47% of human HCCs and was accompanied by reduced TFPI-2 messenger RNA expression. In addition, TFPI-2 expression in HCC cell lines can be robustly restored by combined treatment with 5-Aza-dC and histone deacetylase inhibitor trichostatin A. These findings indicate that TFPI-2 is frequently silenced in human HCC via epigenetic alterations, including promoter methylation and histone deacetylation. Moreover, ectopic overexpression of TFPI-2 significantly suppressed the proliferation and invasiveness of HCC cells.

CONCLUSION

Our findings suggest that TFPI-2 is a candidate tumor suppressor gene in human HCC.

Identification of a human TFPI-2 splice variant that is upregulated in human tumor tissues

Background

Previous studies have shown that the expression of tissue factor pathway inhibitor-2 (TFPI-2), a matrix-associated Kunitz-type serine proteinase inhibitor, is markedly down-regulated in several tumor cells through hypermethylation of the TFPI-2 gene promoter. In the present study, RT-PCR analysis of total RNA from both human normal and tumor cells revealed a novel 289 nucleotide splice variant of the TFPI-2 transcript designated as aberrantly-spliced TFPI-2 (asTFPI-2).

Results

Nucleotide sequence analyses indicated that asTFPI-2 consists of complete exons II and V, fused with several nucleotides derived from exons III and IV, as well as six nucleotides derived from intron C. 5'- and 3'-RACE analyses of total RNA amplified exclusively the wild-type TFPI-2 transcript, indicating that asTFPI-2 lacks either a 5'-untranslated region (UTR) or a 3'-poly (A)⁺ tail. Quantitative real-time RT-PCR analyses revealed that several human tumor cells contain 4 to 50-fold more copies of asTFPI-2 in comparison to normal cells. In spite of the absence of a 5'-UTR or poly (A)⁺ tail, the asTFPI-2 variant exhibited a half-life of ~16 h in tumor cells.

Conclusion

Our studies reveal the existence of a novel, aberrantly-spliced TFPI-2 transcript predominantly expressed in tumor cells and provides suggestive evidence for an additional mechanism for tumor cells to down-regulate TFPI-2 protein expression enhancing their ability to degrade the extracellular matrix.

Tissue Factor Pathway Inhibitor-2 Is Upregulated by Vascular Endothelial Growth Factor and Suppresses Growth Factor-Induced Proliferation of Endothelial Cells

Objective— The purpose of this study is to investigate the expression and regulation of type-2 tissue factor pathway inhibitor (TFPI-2) in endothelial cells, as well as the regulation of human endothelial cell (EC) function by TFPI-2.

Methods and Results— Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that vascular endothelial growth factor (VEGF) induced both time- and dose-dependent increase in TFPI-2 mRNA and protein expression in endothelial cells. TFPI-2 mRNA expression was also significantly upregulated by IL-1β, and modestly increased by both tumor necrosis factor (TNF)-α and fibroblast growth factor (FGF)-2, but not placental growth factor (PlGF). VEGF upregulation of TFPI-2 was dramatically reduced by inhibition of the MEK pathway. Administration of TFPI-2 protein suppressed both VEGF and FGF-2 stimulation of EC proliferation in a dose-dependent manner. A recombinant preparation of the first Kunitz-type domain of TFPI-2 (KD1) did not suppress growth factor stimulation of EC proliferation, suggesting a mechanism distinct from the proteinase inhibitory activity of TFPI-2. Exogenously added TFPI-2 protein suppressed VEGF-induced EC migration in 2 different assays. Recombinant wt-KD1 or the R24K mutant of KD1, but not the R24Q mutant, dramatically suppressed VEGF-induced EC migration. TFPI-2 protein, but not recombinant KD1, blocked VEGF-induced activation of both Akt and ERK1/2 in ECs. At higher doses, TFPI-2 protein blocked VEGFR2 activation.

Conclusion— Our data suggest that VEGF-upregulation of TFPI-2 expression in endothelial cells may represent a mechanism for negative feedback regulation and modulation of its pro-angiogenic action on endothelial cells. TFPI-2, or derivatives of TFPI-2, may be novel therapeutics for treatment of angiogenic disease processes.

Glial cell-derived neurotrophic factor (GDNF) promotes low-grade Hs683 glioma cell migration through JNK, ERK-1/2 and p38 MAPK signaling pathways

Invasion of tumor cells is the primary cause of therapeutic failure in the treatment of malignant gliomas. In an attempt to investigate the properties of the malignant progression of glioma cells, we examined the correlation between cell migration and glial cell-derived neurotrophic factor (GDNF) secretion of two glioma cell lines which differ in their invasive phenotypes. Here, we show that the high-grade C6 cells are more migrative and secrete more GDNF than the low-grade Hs683 cells. GDNF signaling is more highly activated in C6 cells than in Hs683 cells. Treatment of the Hs683 cells with GDNF significantly increased migration comparable to the C6 cells, revealing the autocrine and/or paracrine effect of GDNF on promotion of the glioma cell migration. We then examined the involvement of mitogen-activated protein kinases (MAPKs) including c-Jun N-terminal protein kinase (JNK), extracellular signal-regulated kinases (ERKs) and p38 MAPK in Hs683 cell migration induced by GDNF. A prominent activation of JNK, ERKs and p38 MAPK was observed in the GDNF-treated cells. Functional studies showed that the activation of these MAPKs was critical for Hs683 cell migration induced by GDNF. Our findings revealing molecular mechanisms for the promoting effect of GDNF on glioma cell migration may provide an insight into a better understanding to the malignant progression of human gliomas.

ADAMTS1 Interacts with, Cleaves, and Modifies the Extracellular Location of the Matrix Inhibitor Tissue Factor Pathway Inhibitor-2

ADAMTS1 is an extracellular metalloproteinase known to participate in a variety of biological processes that includes inflammation, angiogenesis, and development of the urogenital system. Many of its functions rely on its catalytic activity, which thus far has been limited to the cleavage of the matrix proteoglycans aggrecan and versican. However, it is likely that other substrates exist. Using a yeast two-hybrid screen, we identified the Kunitz-type inhibitor, tissue factor pathway inhibitor-2 (TFPI-2), as a binding partner of ADAMTS1. The interaction was confirmed by several biochemical and cell-based assays. In addition, our studies revealed alterations in the pattern of TFPI-2-secreted isoforms and in its extracellular location caused by the specific action of ADAMTS1. Interestingly, we found that TFPI-2 is a novel substrate of ADAMTS1. The cleavage removes a protease-sensitive C-terminal region in TFPI-2, altering its binding properties. The proposed role of TFPI-2 as a maintenance factor of extracellular remodeling suggests the indirect function of ADAMTS1 as an additional homeostatic player by its ability to alter the extracellular location of TFPI-2 and, therefore, to disrupt the remodeling machinery, a phenomenon directly associated to pathologies such as atherosclerosis and tumor progression.

FoxM1B is overexpressed in human glioblastomas and critically regulates the tumorigenicity of glioma cells

The transcription factor Forkhead box M1 (FoxM1) is overexpressed in malignant glioma. However, the functional importance of this factor in human glioma is not known. In the present study, we found that FoxM1B was the predominant FoxM1 isoform expressed in human glioma but not in normal brain tissue. The level of FoxM1 protein expression in human glioma tissues was directly correlated with the glioma grade. The level of FoxM1 protein expression in human glioblastoma tissues was inversely correlated with patient survival. Enforced FoxM1B expression caused SW1783 and Hs683 glioma cells, which do not form tumor xenografts, to regain tumorigenicity in nude mouse model systems. Moreover, gliomas that arose from FoxM1B-transfected anaplastic astrocytoma SW1783 cells displayed glioblastoma multiforme phenotypes. Inhibition of FoxM1 expression in glioblastoma U-87MG cells suppressed their anchorage-independent growth in vitro and tumorigenicity in vivo. Furthermore, we found that FoxM1 regulates the expression of Skp2 protein, which is known to promote degradation of the cell cycle regulator p27(Kip1). These results showed that FoxM1 is overexpressed in human glioblastomas and contributes to glioma tumorigenicity. Therefore, FoxM1 might be a new potential target of therapy for human malignant gliomas.

Analysis of sequence variations in the promoter region of the human tissue factor pathway inhibitor 2 gene in apoplectic patients and blood donors

Tissue factor pathway inhibitor 2 (TFPI-2) is a Kunitz-type serine protease inhibitor with homology to TFPI-1, an important regulator of the extrinsic pathway of blood coagulation. Recent studies have focused on TFPI-2 and its implications for atherosclerosis. The promoter region and the exons of the human TFPI-2 gene were screened for sequence variations in 41 apoplectic patients and 140 blood donors with no history of ischemic stroke. The sequence variations -567T>C, -546T>C, -353A>G, -161G>C, -167G>A, -47C>A, and -18C>A, which are located in the TFPI-2 promoter, were discovered in both cohorts with allelic frequencies ranging from 0.3 to 2.4%. The influence of these sequence variations on the transcriptional activity of the TFPI-2 gene was investigated in HEK-293 cells using a promoter test system. A wild-type TFPI-2 promoter fragment 716 bp upstream of the translation start site was cloned into a secreted alkaline phosphatase expression vector, and the sequence variations were introduced by site-directed mutagenesis. Interestingly, the promoter activity of the tested mutants was reduced by 1.3- to 2.8-fold compared to that of wild-type control. The variation -18C>A, where a putative binding site of the transcription factor Sp-1 is located, had the strongest effect on transcriptional activity. In conclusion, our present study shows that the transcription of TFPI-2 is changed by single nucleotide polymorphisms and that the sequence variations in transcription factor binding sites of the TFPI-2 promoter may influence the regulation of this gene.

Recombinant adeno-associated virus (rAAV) expressing TFPI-2 inhibits invasion, angiogenesis and tumor growth in a human glioblastoma cell line

Recombinant adeno-associated viruses (rAAV) have become the vector of choice for many gene therapy protocols. rAAVs have a number of attractive features including long-term transgene expression and the ability to transduce both dividing and non-dividing cells. We have shown previously the anti-cancer role of tissue factor pathway inhibitor-2 (TFPI-2), a matrix-associated serine protease inhibitor, in human glioblastomas. As a result of our present study, in which 0.8-kb fragment of human TFPI-2 was cloned into the adeno-associated viral vectors (rAAA-TFPI-2), rAAV-TFPI-2 infection of SNB19 cells significantly increased TFPI-2 as determined by Western blotting. As assessed by spheroid and Matrigel assays, infection of SNB19 cells with rAAV-TFPI-2 significantly reduced migration and invasion in a dose-dependent manner. Tumor spheroids infected with rAAV-TFPI-2 and co-cultured with fetal rat brain aggregates did not invade rat brain aggregates, whereas 90-95% of the mock and AAV-CMV infected cells invaded rat brain aggregates. In vitro angiogenesis studies (tumor cells co-cultured with endothelial cells or endothelial cells seeded on matrigel) showed reduction of capillary-like structure formation in rAAV-TFPI-2-treated cells as compared to parental and mock-transfected cells. In in vivo angiogenesis results demonstrated the formation of microvessels in SNB19 parental cells and this formation was inhibited when the SNB19 cells were infected with rAAV-TFPI-2. Further, we observed a large reduction of tumor growth in SNB19 cells treated with rAAV-TFPI-2 virus injected intracerebrally when compared to controls. Our study demonstrates that rAAV-TFPI-2-mediated gene therapy offers a novel tool for the treatment of brain tumors.

Gene expression profiling revealed novel molecular targets of docetaxel and estramustine combination treatment in prostate cancer cells

Both docetaxel and estramustine are antimicrotubule agents with antitumor activity in various cancers including prostate cancer. Clinical trials for docetaxel and estramustine combination treatment have suggested improved antitumor activity in hormone-refractory prostate cancer. However, the molecular mechanisms involved in the combination treatment with docetaxel and estramustine have not been fully elucidated. In order to establish such molecular mechanisms in both hormone insensitive (PC-3) and sensitive (LNCaP) prostate cancer cells, gene expression profiles of docetaxel- and estramustine-treated prostate cancer cells were obtained by using Affymetrix Human Genome U133A Array. Total RNA from PC-3 and LNCaP cells untreated and treated with 2 nmol/L docetaxel, 4 micromol/L estramustine, or 1 nmol/L docetaxel plus 2 micromol/L estramustine for 6, 36, and 72 hours was subjected to microarray analysis. Real-time PCR and Western blot analysis were conducted to confirm the microarray data. Clustering analysis based on biological function showed that docetaxel and estramustine combination treatment down-regulated some genes that are known to regulate cell proliferation, transcription, translation, and oncogenesis. In contrast, docetaxel and estramustine combination treatment up-regulated some genes related to induction of apoptosis, cell cycle arrest, and tumor suppression. Docetaxel and estramustine also showed differential effects on gene expression between mono- and combination treatment. Combination treatment with docetaxel and estramustine caused alternations of a large number of genes, many of which may contribute to the molecular mechanisms by which docetaxel and estramustine inhibit the growth of prostate cancer cells. These results provide novel molecular targets of docetaxel and estramustine combination treatment in prostate cancer cells. This information could be utilized for further mechanistic research and for devising optimized therapeutic strategies against prostate cancer.

Crystal structure of Kunitz domain 1 (KD1) of tissue factor pathway inhibitor-2 in complex with trypsin. Implications for KD1 specificity of inhibition

Kunitz domain 1 (KD1) of tissue factor pathway inhibitor-2 inhibits trypsin, plasmin, and factor VIIa (FVIIa)/tissue factor with Ki values of 13, 3, and 1640 nM, respectively. To investigate the molecular specificity of KD1, crystals of the complex of KD1 with bovine beta-trypsin were obtained that diffracted to 1.8 A. The P1 residue Arg-15 (bovine pancreatic trypsin inhibitor numbering) in KD1 interacts with Asp-189 (chymotrypsin numbering) and with the carbonyl oxygens of Gly-219 and Ogamma of Ser-190. Leu-17, Leu-18, Leu-19, and Leu-34 in KD1 make van der Waals contacts with Tyr-39, Phe-41, and Tyr-151 in trypsin, forming a hydrophobic interface. Molecular modeling indicates that this complementary hydrophobic patch is composed of Phe-37, Met-39, and Phe-41 in plasmin, whereas in FVIIa/tissue factor, it is essentially absent. Arg-20, Tyr-46, and Glu-39 in KD1 interact with trypsin through ordered water molecules. In contrast, insertions in the 60-loop in plasmin and FVIIa allow Arg-20 of KD1 to directly interact with Glu-60 in plasmin and Asp-60 in FVIIa. Moreover, Tyr-46 in KD1 electrostatically interacts with Lys-60A and Arg-60D in plasmin and Lys-60A in FVIIa. Glu-39 in KD1 interacts directly with Arg-175 of the basic patch in plasmin, whereas in FVIIa, such interactions are not possible. Thus, the specificity of KD1 for plasmin is attributable to hydrophobic and direct electrostatic interactions. For trypsin, hydrophobic interactions are intact, and electrostatic interactions are weak, whereas for FVIIa, hydrophobic interactions are missing, and electrostatic interactions are partially intact. These findings provide insight into the protease selectivity of KD1.

Sequential 5-Aza 2'-deoxycytidine/depsipeptide FK228 treatment induces tissue factor pathway inhibitor 2 (TFPI-2) expression in cancer cells

cDNA arrays were used to examine gene induction in CALU-6 and H460 lung cancer cells mediated by sequential 5-aza 2'-deoxycytidine (DAC)/depsipeptide FK228 (DP) exposure in order to identify translational end points for clinical trials evaluating these agents. In both cell lines, sequential DAC/DP treatment induced expression of tissue factor pathway inhibitor-2 (TFPI-2), an inhibitor of Factor VII: tissue factor signal transduction known to diminish the malignant phenotype of cancer cells. TFPI-2 expression was diminished or absent in 16 of 32 cell lines established from thoracic malignancies. Sequential DAC/DP treatment induced TFPI-2 in cancer cells deficient for TFPI-2 expression in the basal state. Promoter methylation coincided with loss of TFPI-2 expression in a number of cancer lines. TFPI-2 promoter methylation was observed in one of five pulmonary adenocarcinomas, and seven of seven esophageal adenocarcinomas, but not corresponding normal tissues. DP enhanced acetylation of TFPI-2-associated histones in CALU-6 cells. DP or PDBU, alone, induced TFPI-2 expression in cancer cells deficient for TFPI-2 expression in the absence of promoter methylation. In these cells, DP-mediated TFPI-2 induction was abrogated by calphostin. Induction of TFPI-2 by distinct, yet cooperative mechanisms involving chromatin remodeling and PKC signaling strengthens the preclinical rationale for sequential administration of DNA demethylating agents and HDAC inhibitors in cancer patients. Furthermore, induction of TFPI-2 may be a useful surrogate marker of treatment response in individuals receiving sequential DAC/DP infusions.

Epigenetic inactivation of TFPI-2 as a common mechanism associated with growth and invasion of pancreatic ductal adenocarcinoma

Using microarrays, we have screened for genes reactivated by drugs that modify epigenetic mechanisms in pancreatic cancer cells. One of the genes identified was tissue factor pathway inhibitor 2 (TFPI-2), which encodes for a broad-spectrum serine proteinase inhibitor that negatively regulates the extracellular matrix degradation, an essential step in tumor invasion and metastasis. We therefore investigated the expression and methylation patterns of the TFPI-2 gene in pancreatic adenocarcinoma, and determined its role in tumor growth and invasion. In contrast to its abundant expression in normal pancreas, TFPI-2 mRNA was undetectable in a high fraction of pancreatic cancer cell lines and in primary pancreatic ductal neoplasms (IPMNs). Loss of TFPI-2 expression was associated with aberrant hypermethylation of its promoter CpG island. Treatment with the phorbol ester (PMA), known to stimulate the TFPI-2 promoter activity, augmented the TFPI-2 expression in cell lines with unmethylated or partially methylated TFPI-2, but failed to induce the expression in cell lines that harbored fully methylated TFPI-2. Aberrant methylation of TFPI-2 was also detected in 73% (102/140) of pancreatic cancer xenografts and primary pancreatic adenocarcinomas, was more likely in older patients with pancreatic cancer, and significantly correlated with progression of IPMNs (P=0.0002). Restored expression of the TFPI-2 gene in nonexpressing pancreatic cancer cells resulted in marked suppression in their proliferation, migration, and invasive potential in vitro. We thus conclude that epigenetic inactivation of TFPI-2 is a common mechanism that contributes to the aggressive phenotype of pancreatic ductal adenocarcinoma.

Expression and characterization of the first kunitz domain of human tissue factor pathway inhibitor-2

Human tissue factor pathway inhibitor-2 (hTFPI-2) has three kunitz domains whose structure and function are unclear. We expressed the first kunitz domain of hTFPI-2 (hTFPI-2/KD1) as functional form using Pichia pastoris and investigated its characterization. In the experiment, hTFPI-2/KD1 can inhibit the plasmin and trypsin activity and the Ki of hTFPI-2/KD1 towards plasmin (30nM) and trypsin (50nM) was determined as 10 and 7nM by chromogenic assay, respectively. hTFPI-2/KD1 can also inhibit MMP-2 and MMP-9 in zymography assay. Furthermore, the inhibition of hTFPI-2/KD1 to the Matrigel invasion by HT-1080 is also described. This study provides a method to produce hTFPI-2/KD1 efficiently and some insights into the structure and function of hTFPI-2/KD1.

Inhibition of cathepsin B and MMP-9 gene expression in glioblastoma cell line via RNA interference reduces tumor cell invasion, tumor growth and angiogenesis

Extracellular proteases have been shown to cooperatively influence matrix degradation and tumor cell invasion through proteolytic cascades, with individual proteases having distinct roles in tumor growth, invasion, migration and angiogenesis. Matrix metalloproteases (MMP)-9 and cathepsin B have been shown to participate in the processes of tumor growth, vascularization and invasion of gliomas. In the present study, we used a cytomegalovirus promoter-driven DNA template approach to induce hairpin RNA (hpRNA)-triggered RNA interference (RNAi) to block MMP-9 and cathepsin B gene expression with a single construct. Transfection of a plasmid vector-expressing double-stranded RNA (dsRNA) for MMP-9 and cathepsin B significantly inhibited MMP-9 and cathepsin B expression and reduced the invasive behavior of SNB19, glioblastoma cell line in Matrigel and spheroid invasion models. Downregulation of MMP-9 and cathepsin B using RNAi in SNB19 cells reduced cell-cell interaction of human microvascular endothelial cells, resulting in the disruption of capillary network formation in both in vitro and in vivo models. Direct intratumoral injections of plasmid DNA expressing hpRNA for MMP-9 and cathepsin B significantly inhibited established glioma tumor growth and invasion in intracranial tumors in vivo. Further intraperitoneal (i.p.) injections of plasmid DNA expressing hpRNA for MMP-9 and cathepsin B completely regressed pre-established tumors for a long time (4 months) without any indication of these tumor cells. For the first time, these observations demonstrate that the simultaneous RNAi-mediated targeting of MMP-9 and cathepsin B has potential application for the treatment of human gliomas.

Integrative analysis of multiple gene expression profiles applied to liver cancer study

A statistical method for combining multiple microarray studies has been previously developed by the authors. Here, we present the application of the method to our hepatocellular carcinoma (HCC) data and report new findings on gene expression changes accompanying HCC. From the cross-verification result of our studies and that of published studies, we found that single microarray analysis might lead to false findings. To avoid those pitfalls of single-set analyses, we employed our effect size method to integrate multiple datasets. Of 9982 genes analyzed, 477 significant genes were identified with a false discovery rate of 10%. Gene ontology (GO) terms associated with these genes were explored to validate our method in the biological context with respect to HCC. Furthermore, it was demonstrated that the data integration process increases the sensitivity of analysis and allows small but consistent expression changes to be detected. These integration-driven discoveries contained meaningful and interesting genes not reported in previous expression profiling studies, such as growth hormone receptor, erythropoietin receptor, tissue factor pathway inhibitor-2, etc. Our findings support the use of meta-analysis for a variety of microarray data beyond the scope of this specific application.

Structure-Function Analysis of the Reactive Site in the First Kunitz-type Domain of Human Tissue Factor Pathway Inhibitor-2

Human tissue factor pathway inhibitor-2 (TFPI-2) is a Kunitz-type proteinase inhibitor that regulates a variety of serine proteinases involved in coagulation and fibrinolysis through their non-productive interaction with a P(1) residue (Arg-24) in its first Kunitz-type domain (KD1). Previous kinetic studies revealed that TFPI-2 was a more effective inhibitor of plasmin than several other serine proteinases, but the molecular basis for this specificity was unclear. In this study, we employed molecular modeling and mutagenesis strategies to produce several variants of human TFPI-2 KD1 in an effort to identify interactive site residues other than the P(1) Arg that contribute significantly to its inhibitory activity and specificity. Molecular modeling of KD1 based on the crystal structure of bovine pancreatic trypsin inhibitor revealed that KD1 formed a more energetically favorable complex with plasmin versus trypsin and/or the factor VIIa-tissue factor complex primarily due to strong ionic interactions between Asp-19 (P(6)) and Arg residues in plasmin (Arg-644, Arg-719, and Arg-767), Arg-24 (P(1)) with Asp-735 in plasmin, and Arg-29 (P(5)') with Glu-606 in plasmin. In addition, Leu-26 through Leu-28 (P(2)'-P(4)') in KD1 formed strong van der Waals contact with a hydrophobic cluster in plasmin (Phe-583, Met-585, and Phe-587). Mutagenesis of Asp-19, Tyr-20, Arg-24, Arg-29, and Leu-26 in KD1 resulted in substantial reductions in plasmin inhibitory activity relative to wild-type KD1, but the Asp-19 and Tyr-20 mutations revealed the importance of these residues in the specific inhibition of plasmin. In addition to the reactive site residues in the P(6)-P(5)' region of KD1, mutation of a highly conserved Phe at the P(18)' position revealed the importance of this residue in the inhibition of serine proteinases by KD1. Thus, together with the P(1) residue, the nature of other residues flanking the P(1) residue, particularly at P(6) and P(5)', strongly influences the inhibitory activity and specificity of human TFPI-2.

The effect of human tissue factor pathway inhibitor-2 on the growth and metastasis of fibrosarcoma tumors in athymic mice

Human tissue factor pathway inhibitor-2 (TFPI-2) is a matrix-associated Kunitz inhibitor that inhibits the plasmin- and trypsin-mediated activation of zymogen matrix metalloproteinases involved in tumor progression, invasion, and metastasis. To directly assess its role in tumor growth and metastasis in vivo, we stably transfected HT-1080 fibrosarcoma cells expressing either fully active wild-type human TFPI-2 (WT) or inactive R24Q TFPI-2 (QT) and examined their ability to form tumors and metastasize in athymic mice in comparison to mock-transfected cells (MT). MT and QT fibrosarcoma tumors grew 2 to 3 times larger than WT tumors. Tumor metastasis was confined to the lung and was observed in 75% of mice treated with either MT or QT cells, whereas only 42% of mice treated with WT cells developed lung metastases. Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analyses of each tumor group revealed 3- to 6-fold lower levels of murine vascular endothelial growth factor gene expression in WT tumors in relation to either MT or QT tumors. Comparative tumor gene expression analysis revealed that several human genes implicated in oncogenesis, invasion, metastasis, apoptosis, and angiogenesis had significantly altered levels of expression in WT tumors. Our collective data demonstrate that secretion of inhibitory TFPI-2 by a highly metastatic tumor cell markedly inhibits its growth and metastasis in vivo by regulating pericellular extracellular matrix (ECM) remodeling and angiogenesis. (Blood. 2004;103:1069-1077)

Thrombin up-regulates tissue factor pathway inhibitor-2 synthesis through a cyclooxygenase-2-dependent, epidermal growth factor receptor-independent mechanism

The serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2) inhibits the tissue factor-factor VIIa complex and thereby impairs factor Xa and subsequently thrombin generation. Here we show that thrombin itself up-regulates TFPI-2 mRNA and protein expression in human liver myofibroblasts, a cell type shown to express high levels of TFPI-2 (Neaud, V., Hisaka, T., Monvoisin, A., Bedin, C., Balabaud, C., Foster, D. C., Desmoulière, A., Kisiel, W., and Rosenbaum, J. (2000) J. Biol. Chem. 275, 35565-35569). This effect required thrombin catalytic activity, as shown by its abolition with hirudin. Although the thrombin effect could be mimicked by agonists of both protease-activated receptor (PAR)-1 and PAR-4, it was largely blocked by a PAR-1 blocking antibody. Transactivation of the epidermal growth factor (EGF) receptor has been reported as a common event in thrombin signaling. However, thrombin did not detectably transactivate the EGF receptor in liver myofibroblasts, and blocking the EGF receptor did not affect TFPI-2 induction. On the other hand, thrombin increased the expression of cyclooxygenase-2 (COX-2) mRNA via a MAPK-dependent pathway, and a specific COX-2 inhibitor abolished the effect of thrombin on TFPI-2 expression. Thus, thrombin, through PAR-1 signaling, up-regulates the synthesis of TFPI-2 via a MAPK/COX-2-dependent pathway. The up-regulation of TFPI-2 expression by thrombin could in turn down-regulate thrombin generation and contribute to limit blood coagulation.

Promoter methylation and silencing of the tissue factor pathway inhibitor-2 (TFPI-2), a gene encoding an inhibitor of matrix metalloproteinases in human glioma cells

We have shown previously that the tissue factor pathway inhibitor-2 (TFPI-2), a broad range proteinase inhibitor, is highly expressed in low-grade gliomas, but, minimally expressed or undetectable in glioblastomas, and that enforced expression of this gene reduces the invasive properties of brain tumor cells. Here, we examined the role of promoter methylation as a mechanism of TFPI-2 gene silencing. In SNB19 glioblastoma cells, which have no detectable TFPI-2 expression, 5-aza-2'-deoxycytidine (5aC), an inhibitor of DNA methyltransferase, induced TFPI-2 mRNA in a dose-dependent manner. Trichostatin A (TSA), the histone deacetylase (HDAC) inhibitor, by itself, was more efficient than 5aC in inducing TFPI-2 transcripts, and the 5aC+TSA combination resulted in highly synergistic reactivation of the gene, both at the transcript and protein levels. In Hs683 glioma cells, which express the TFPI-2 gene at high levels, transfection of the in vitro methylated TFPI-2 promoter constructs resulted in a drastic decrease of promoter activity compared to the unmethylated promoter. Further, the methylation-specific PCR in SNB19 and Hs683 cells showed that TFPI-2 gene repression was closely linked with methylation of the CpG islands in the promoter. Finally, the chromatin immunoprecipitation assays in SNB19 cells showed that the methylated and repressed TFPI-2 promoter was associated with the methyl-CpG binding protein 2 (MeCP2), and that gene reactivation resulted in the loss of MeCP2 from this site. These studies establish that TFPI-2 is transcriptionally silenced through promoter methylation in SNB19 cells.