Increased expression of Annexin A2 in oral squamous cell carcinoma

Label-based comparative proteomics of oral mucosal tissue to understand progression of precancerous lesions to oral squamous cell carcinoma

Introduction

Oral squamous cell carcinomas typically arise from precancerous lesions such as leukoplakia and erythroplakia. These lesions exhibit a range of histological changes from hyperplasia to dysplasia and carcinoma in situ, during their transformation to malignancy. The molecular mechanisms driving this multistage transition remain incompletely understood. To bridge this knowledge gap, our current study utilizes label based comparative proteomics to compare protein expression profiles across different histopathological grades of leukoplakia, erythroplakia, and oral squamous cell carcinoma samples, aiming to elucidate the molecular changes underlying lesion evolution.

Methodology

An 8-plex iTRAQ proteomics of 4 biological replicates from 8 clinical phenotypes of leukoplakia and erythroplakia, with hyperplasia, mild dysplasia, moderate dysplasia; along with phenotypes of well differentiated squamous cell carcinoma and moderately differentiated squamous cell carcinoma was carried out using the Orbitrap Fusion Lumos mass spectrometer. Raw files were processed with Maxquant, and statistical analysis across groups was conducted using MetaboAnalyst. Statistical tools such as ANOVA, PLS-DA VIP scoring, and correlation analysis were employed to identify differentially expressed proteins that had a linear expression variation across phenotypes of hyperplasia to cancer. Validation was done using Bioinformatic tools such as ClueGO + Cluepedia plugin in Cytoscape to extract functional annotations from gene ontology and pathway databases.

Results and discussion

A total of 2685 protein groups and 12,397 unique peptides were identified, and 61 proteins consistently exhibited valid reporter ion corrected intensities across all samples. Of these, 6 proteins showed linear varying expression across the analysed sample phenotypes. Collagen type VI alpha 2 chain (COL6A2), Fibrinogen β chain (FGB), and Vimentin (VIM) were found to have increased linear expression across pre-cancer phenotypes of leukoplakia to cancer, while Annexin A7 (ANXA7) was seen to be having a linear decreasing expression. Collagen type VI alpha 2 chain (COL6A2) and Annexin A2 (ANXA2) had increased linear expression across precancer phenotypes of erythroplakia to cancer. The mass spectrometry proteomics data have been deposited to the ProteomeXchanger Consortium via the PRIDE partner repository with the data set identifier PXD054190. These differentially expressed proteins mediate cancer progression mainly through extracellular exosome; collagen-containing extracellular matrix, hemostasis, platelet aggregation, and cell adhesion molecule binding.

Conclusion

Label-based proteomics is an ideal platform to study oral cancer progression. The differentially expressed proteins provide insights into the molecular mechanisms underlying the progression of oral premalignant lesions to malignant phenotypes. The study has translational value for early detection, risk stratification, and potential therapeutic targeting of oral premalignant lesions and in its prevention to malignant forms.

Recent Advances in Molecular and Cellular Functions of S100A10

S100A10 (p11, annexin II light chain, calpactin light chain) is a multifunctional protein with a wide range of physiological activity. S100A10 is unique among the S100 family members of proteins since it does not bind to Ca2+, despite its sequence and structural similarity. This review focuses on studies highlighting the structure, regulation, and binding partners of S100A10. The binding partners of S100A10 were collated and summarized.

Integrative metabolomics-genomics approach reveals key metabolic pathways and regulators of Alzheimer's disease

Metabolites, the biochemical products of the cellular process, can be used to measure alterations in biochemical pathways related to the pathogenesis of Alzheimer's disease (AD). However, the relationships between systemic abnormalities in metabolism and the pathogenesis of AD are poorly understood. In this study, we aim to identify AD-specific metabolomic changes and their potential upstream genetic and transcriptional regulators through an integrative systems biology framework for analyzing genetic, transcriptomic, metabolomic, and proteomic data in AD. Metabolite co-expression network analysis of the blood metabolomic data in the Alzheimer's Disease Neuroimaging Initiative (ADNI) shows short-chain acylcarnitines/amino acids and medium/long-chain acylcarnitines are most associated with AD clinical outcomes, including episodic memory scores and disease severity. Integration of the gene expression data in both the blood from the ADNI and the brain from the Accelerating Medicines Partnership Alzheimer's Disease (AMP-AD) program reveals ABCA1 and CPT1A are involved in the regulation of acylcarnitines and amino acids in AD. Gene co-expression network analysis of the AMP-AD brain RNA-seq data suggests the CPT1A- and ABCA1-centered subnetworks are associated with neuronal system and immune response, respectively. Increased ABCA1 gene expression and adiponectin protein, a regulator of ABCA1, correspond to decreased short-chain acylcarnitines and amines in AD in the ADNI. In summary, our integrated analysis of large-scale multiomics data in AD systematically identifies novel metabolites and their potential regulators in AD and the findings pave a way for not only developing sensitive and specific diagnostic biomarkers for AD but also identifying novel molecular mechanisms of AD pathogenesis.

Advances in cancer treatment: a new therapeutic target, Annexin A2

Annexin A2 (ANXA2) is a calcium regulated phospholipid-binding protein. It is expressed in some tumor cells, endothelial cells, macrophages, and mononuclear cells, affecting cell survival and mediating interactions between intercellular and extracellular microenvironment. Aberrant expression of ANXA2 can be used as a potential predictive factor, diagnostic biomarker and therapeutic target in cancer therapy. Investigators used various technologies to target ANXA2 in a preclinical model of human cancers and demonstrated encouraging results. In this review article, we discuss the diagnosis and prognosis latent capacity of ANXA2 in progressive cancers, focus on the exploration of restorative interventions targeting ANXA2 in cancer treatment. Further, we comment on a promising candidate therapy that is conceivable for clinical translation.

Clinical significance of Annexin A2 expression in oral squamous cell carcinoma and its influence on cell proliferation, migration and invasion

Oral squamous cell carcinoma (OSCC) is the most common malignant epithelial neoplasm of the head and neck, with poorer prognosis. There is lack of specific targets for diagnosis and treatment of OSCC at present. Annexin A2 (ANXA2) is involved in cell angiogenesis, invasion, proliferation and metastasis. In this study, the significance and effect of ANXA2 on OSCC and OSCC cells were explored from the clinical and basic study. First, ANXA2 expression in OSCC tissues and adjacent non-cancer tissues of 124 patients were detected, and the correlation between ANXA2 expression and clinical parameters were analyzed. The results found that ANXA2 was highly expressed in OSCC tissues, and was associated with the TNM stage, tumor differentiation, lymph node metastasis and poor survival of OSCC patients. The expression of ANXA2 in OSCC cells were higher than the normal oral cells. And knockdown of ANXA2 by transfecting ANXA2-siRNA could suppress the proliferation, migration, and invasion abilities of OSCC cells. Overall, ANXA2 expression is correlated with poor survival of OSCC patients, and silencing of ANXA2 suppress the proliferation, migration and invasion of OSCC cells.

Extracellular Vesicles in Oral Squamous Cell Carcinoma and Oral Potentially Malignant Disorders: A Systematic Review

Extracellular vesicles (EVs) are secreted from most cell types and utilized in a complex network of near and distant cell-to-cell communication. Insight into this complex nanoscopic interaction in the development, progression and treatment of oral squamous cell carcinoma (OSCC) and precancerous oral mucosal disorders, termed oral potentially malignant disorders (OPMDs), remains of interest. In this review, we comprehensively present the current state of knowledge of EVs in OSCC and OPMDs. A systematic literature search strategy was developed and updated to December 17, 2019. Fifty-five articles were identified addressing EVs in OSCC and OPMDs with all but two articles published from 2015, highlighting the novelty of this research area. Themes included the impact of OSCC-derived EVs on phenotypic changes, lymph-angiogenesis, stromal immune response, mechanisms of therapeutic resistance as well as utility of EVs for drug delivery in OSCC and OPMD. Interest and progress of knowledge of EVs in OSCC and OPMD has been expanding on several fronts. The oral cavity presents a unique and accessible microenvironment for nanoparticle study that could present important models for other solid tumours.

Sp1 promotes cell migration and invasion in oral squamous cell carcinoma by upregulating Annexin A2 transcription

Oral squamous cell carcinoma (OSCC) is a common malignant tumor with high metastatic potential in head and neck. Revealing the mechanism of OSCC metastasis will benefit the prognosis and prevention of OSCC. Sp1 is a transcription factor involved in the progression of several tumors. Annexin A2 functions as an oncogene, and there are three putative Sp1 binding sites in the Annexin A2 promoter region. Therefore, we hypothesized that Sp1 could regulate OSCC metastasis by regulating Annexin A2 expression. Quantitative real-time PCR (qRT-PCR) and Western blot were used to evaluate Sp1 or Annexin A2 expression. Transwell assays were used to evaluate the migration and invasion capacity of OSCC cells. Luciferase assays and Chromatin immunoprecipitation assays were used to verify whether Sp1 regulate Annexin A2 at the transcriptional level. We found that the expression of Sp1 increased in OSCC tissues compared to paired adjacent normal tissues, and the overexpression of Sp1 was associated with tumor metastasis. Furthermore, Sp1 promoted cell migration and invasion through Annexin A2. In addition, we verified that Sp1 controls Annexin A2 expression at the transcriptional level and identified the binding sites involved. Our study suggests that Sp1/Annexin A2 expression could be a promising prognostic biomarker and therapeutic target for OSCC metastasis.

Hedgehog signaling stimulates Tenascin C to promote invasion of pancreatic ductal adenocarcinoma cells through Annexin A2

Pancreatic adenocarcinoma (PDA) is characterized by a dense desmoplastic reaction that comprises 60-90% of the tumor, while only 10-40% of the tumor is composed of malignant epithelial cells. This desmoplastic reaction is composed of stromal fibroblast cells, extracellular matrix proteins, and immune cells. Accumulating evidence has suggested that the stromal and epithelial cell compartments interact during the pathogenesis of this disease. Therefore, it is important to identify the signaling pathways responsible for this interaction to better understand the mechanisms by which PDA invades and metastasizes. Here, we show that secreted stromal factors induce invasion of PDA cells. Specifically, hedgehog signaling from the tumor cells induces tenascin C (TnC) secretion from the stromal cells that acts back upon the tumor cells in a paracrine fashion to induce the invasion of PDA cells through its' receptor annexin A2 (AnxA2). Therefore, blocking the interaction between TnC and AnxA2 has the potential to prevent liver metastasis in PDA.

Serum Annexin A2 Level Is Associated With Diagnosis and Prognosis in Patients With Oral Squamous Cell Carcinoma

PURPOSE

In several human cancer types, serum annexin A2 levels are increased, but little is known regarding oral squamous cell carcinoma (OSCC). This study aimed to measure serum annexin A2 levels in OSCC patients and assess the association with diagnosis and prognosis.

MATERIALS AND METHODS

This case-control study compared serum annexin A2 concentrations in a group of OSCC patients and a control group. The predictor variable was the presence or absence of OSCC, and the outcome variable was the level of serum annexin A2. Annexin A2 concentrations were measured with an enzyme-linked immunosorbent assay, and correlations with clinicopathologic characteristics of OSCC were further evaluated. Receiver operating characteristic (ROC) curves, Kaplan-Meier curves, log-rank analyses, and a Cox proportional hazards model were used to evaluate the diagnostic and prognostic value of annexin A2.

RESULTS

Serum samples were taken from 399 individuals: 126 patients with OSCC (aged 62.7 ± 10.6 years, 79 men and 47 women); 115 patients with benign oral disease (aged 63.9 ± 10.8 years, 73 men and 42 women); and 158 healthy controls (aged 65.4 ± 12.8 years, 92 men and 66 women). The annexin A2 level was significantly higher in OSCC patients than in patients with benign disease and controls (27.1 ± 9.81 ng/mL vs 15.9 ± 6.97 ng/mL and 15.0 ± 6.69 ng/mL, respectively). To distinguish OSCC patients from the other 2 groups, ROC curve-area under the ROC curve (AUC) analysis for serum annexin A2 levels provided an AUC of 0.80 (sensitivity, 0.62; specificity, 0.87) and an AUC of 0.77 (sensitivity, 0.57; specificity, 0.89). Furthermore, OSCC patients with high annexin A2 levels had poorer overall survival.

CONCLUSIONS

This study suggested that an elevated serum annexin A2 level might be a novel diagnostic and prognostic biomarker for OSCC patients.

H3K9 histone methyltransferase, KMT1E/SETDB1, cooperates with the SMAD2/3 pathway to suppress lung cancer metastasis

Aberrant histone methylation is a frequent event during tumor development and progression. KMT1E (also known as SETDB1) is a histone H3K9 methyltransferase that contributes to epigenetic silencing of both oncogenes and tumor suppressor genes in cancer cells. In this report, we demonstrate that KMT1E acts as a metastasis suppressor that is strongly downregulated in highly metastatic lung cancer cells. Restoring KMT1E expression in this setting suppressed filopodia formation, migration, and invasive behavior. Conversely, loss of KMT1E in lung cancer cells with limited metastatic potential promoted migration in vitro and restored metastatic prowess in vivo. Mechanistic investigations indicated that KMT1E cooperates with the TGFβ-regulated complex SMAD2/3 to repress metastasis through ANXA2. Together, our findings defined an essential role for the KMT1E/SMAD2/3 repressor complex in TGFβ-mediated lung cancer metastasis.

A panel of tumor markers, calreticulin, annexin A2, and annexin A3 in upper tract urothelial carcinoma identified by proteomic and immunological analysis

Background

Upper tract urothelial carcinoma (UTUC) is a tumor with sizable metastases and local recurrence. It has a worse prognosis than bladder cancer. This study was designed to investigate the urinary potential tumor markers of UTUC.

Methods

Between January 2008 and January 2009, urine was sampled from 13 patients with UTUC and 20 healthy adults. The current study identified biomarkers for UTUC using non-fixed volume stepwise weak anion exchange chromatography for fractionation of urine protein prior to two-dimensional gel electrophoresis.

Results

Fifty five differential proteins have been determined by comparing with the 2-DE maps of the urine of UTUC patients and those of healthy people. Western blotting analysis and immunohistochemistry of tumor tissues and normal tissues from patients with UTUC were carried out to further verify five possible UTUC biomarkers, including zinc-alpha-2-glycoprotein, calreticulin, annexin A2, annexin A3 and haptoglobin. The data of western blot and immunohistochemical analysis are consistent with the 2-DE data. Combined the experimental data in the urine and in tumor tissues collected from patients with UTUC, the crucial over-expressed proteins are calreticulin, annexin A2, and annexin A3.

Conclusions

Calreticulin, annexin A2, and annexin A3 are very likely a panel of biomarkers with potential value for UTUC diagnosis.

Dynamic reciprocity: the role of annexin A2 in tissue integrity

Interactions between cells and the extracellular matrix are integral to tissue development, remodelling and pathogenesis. This is underlined by bi-directional flow of information signalling, referred to as dynamic reciprocity. Annexin A2 is a complex and multifunctional protein that belongs to a large family of Ca(2+)-dependent anionic phospholipid and membrane-binding proteins. It has been implicated in diverse cellular processes at the nuclear, cytoplasmic and extracellular compartments including Ca(2+)-dependent regulation of endocytosis and exocytosis, focal adhesion dynamics, transcription and translation, cell proliferation, oxidative stress and apoptosis. Most of these functions are mediated by the annexin A2-S100A10 heterotetramer (AIIt) via its ability to simultaneously interact with cytoskeletal, membrane and extracellular matrix components, thereby mediating regulatory effects of extracellular matrix adhesion on cell behaviour and vice versa. While Src kinase-mediated phosphorylation of filamentous actin-bound AIIt results in membrane-cytoskeletal remodelling events which control cell polarity, cell morphology and cell migration, AIIt at the cell surface can bind to a number of extracellular matrix proteins and catalyse the activation of serine and cysteine proteases which are important in facilitating tissue remodelling during tissue repair, neoangiogenesis and pathological situations. This review will focus on the role of annexin A2 in regulating tissue integrity through intercellular and cell-extracellular matrix interaction. Annexin A2 is differentially expressed in various tissue types as well as in many pathologies, particularly in several types of cancer. These together suggest that annexin A2 acts as a central player during dynamic reciprocity in tissue homeostasis.

Annexin A2: its molecular regulation and cellular expression in cancer development

Annexin A2 (ANXA2) orchestrates multiple biologic processes and clinical associations, especially in cancer progression. The structure of ANXA2 affects its cellular localization and function. However, posttranslational modification and protease-mediated N-terminal cleavage also play critical roles in regulating ANXA2. ANXA2 expression levels vary among different types of cancers. With some cancers, ANXA2 can be used for the detection and diagnosis of cancer and for monitoring cancer progression. ANXA2 is also required for drug-resistance. This review discusses the feasibility of ANXA2 which is active in cancer development and can be a therapeutic target in cancer management.

Three are better than one: plasminogen receptors as cancer theranostic targets

Activation of plasminogen on the cell surface initiates a cascade of protease activity with important implications for several physiological and pathological events. In particular, components of the plasminogen system participate in tumor growth, invasion and metastasis. Plasminogen receptors are in fact expressed on the cell surface of most tumors, and their expression frequently correlates with cancer diagnosis, survival and prognosis. Notably, they can trigger multiple specific immune responses in cancer patients, highlighting their role as tumor-associated antigens. In this review, three of the most characterized plasminogen receptors involved in tumorigenesis, namely Annexin 2 (ANX2), Cytokeratin 8 (CK8) and alpha-Enolase (ENOA), are analyzed to ascertain an overall view of their role in the most common cancers. This analysis emphasizes the possibility of delineating new personalized therapeutic strategies to counteract tumor growth and metastasis by targeting plasminogen receptors, as well as their potential application as cancer predictors.

Surgical management of solitary venous malformation in the midcheek region

OBJECTIVE

The aim of this study was to analyze a single institution's experience of solitary venous malformation (VM) in the midcheek region.

STUDY DESIGN

From 2002 to 2009, a total of 10 consecutive patients with solitary venous malformation in the midcheek region were retrospectively analyzed. Clinical records were reviewed for patient demographic data, presenting symptoms and signs, imaging modalities used, histologic and immunohistochemical results, surgical data, and clinical outcomes.

RESULTS

The sample consisted of 5 males and 5 females with a mean age of 42.8 years. The course of disease ranged from 0.5 to 144.0 months with a mean time of 64.9 months. The mean size of the masses was 1.7 × 1.5 cm (range 1.0 × 0.8 cm to 2.5 × 2.5 cm). Investigations included Doppler ultrasonography (US) and computed tomography (CT) scanning. Surgical excision using various surgical approaches was performed in all patients. Postoperative pathologic examination confirmed the diagnosis of VM. The mean follow-up period was 41.2 months (range 2 months to 94 months) with no recurrence reported.

CONCLUSIONS

For solitary VM in the midcheek region, investigations, such as Doppler US or CT scanning or the use of fine-needle aspiration cytology, may aid in clinical diagnosis. The primary treatment of these lesions is surgical excision, and in our sample, the prognosis of such treatment was good with no recurrence reported.

Overexpression of annexin A2 is associated with abnormal ubiquitination in breast cancer

Abnormal expression of annexin A2 contributes to metastasis and infiltration of cancer cells. To elucidate the cause of abnormal expression of annexin A2, Western blotting, immunoproteomics and immunohistochemical staining were performed to analyze differentially ubiquitinated proteins between fresh breast cancer tissue and its adjacent normal breast tissue from five female volunteers. We detected an ubiquitinated protein that was up-regulated in the cancer tissue, which was further identified as annexin A2 by mass spectrometry. These results suggest that abnormal ubiquitination and/or degradation of annexin A2 may lead to presence of annexin A2 at high level, which may further promote metastasis and infiltration of the breast cancer cells.

Alterations of protein profile in zebrafish liver cells exposed to methyl parathion: a membrane proteomics approach

Methyl parathion (MP) is an extensively used organophosphorus pesticide, which has been associated with a wide spectrum of toxic effects on environmental organisms. The aim of this study is to investigate the alterations of membrane protein profiles in zebrafish liver (ZFL) cell line exposed to MP for 24 h using proteomic approaches. Two-dimensional gel electrophoresis revealed a total of 13 protein spots, whose expression levels were significantly altered by MP. These differential proteins were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, and nine proteins were identified to be membrane proteins, among which seven were up-regulated, while two were down-regulated. In addition, the mRNA levels corresponding to these differential membrane proteins were further analyzed by quantitative real-time PCR. And the differential expression of arginase-2 was specially validated via Western blotting. Regarding the physiological functions, these proteins are involved in molecular chaperon, cytoskeleton system, cell metabolism, signal transduction, transport and hormone receptor respectively, suggesting the complexity of MP-mediated toxicity to ZFL cell. These data could provide useful insights for better understanding the hepatotoxic mechanisms of MP and develop novel protein biomarkers for effectively monitoring MP contamination level in aquatic environment.

Clinical significance of annexin A2 downregulation in oral squamous cell carcinoma

BACKGROUND

The purpose of this study was to determine the expression of Annexin A2 (ANXA2) in normal oral epithelium and in oral carcinomas to correlate these findings with prognostically relevant variables.

METHODS

ANXA2 expression in normal oral mucosa and in 106 oral squamous cell carcinomas was examined by immunohistochemistry.

RESULTS

ANXA2 expression was detected in basal and suprabasal cell layers of normal epithelium, and immunostaining was preferentially membrane-localized. ANXA2 expression was significantly correlated with the histopathological grade, tumor size, and recurrence, but ANXA2 expression was not an independent prognostic factor.

CONCLUSION

The reduction of ANXA2 expression in poorly differentiated tumors is expected to result in a loss of function aimed at the coordination of membrane signaling enzyme complexes. The consequences may manifest as an alteration of epithelial tissue growth and remodeling which eventually exert an influence on tumor progression and metastasis.

The role of annexin A2 in tumorigenesis and cancer progression

Annexin A2 is a calcium-dependent, phospholipid-binding protein found on various cell types. It is up-regulated in various tumor types and plays multiple roles in regulating cellular functions, including angiogenesis, proliferation, apoptosis, cell migration, invasion and adhesion. Annexin A2 binds with plasminogen and tissue plasminogen activator on the cell surface, which leads to the conversion of plasminogen to plasmin. Plasmin is a serine protease which plays a key role in the activation of metalloproteinases and degradation of extracellular matrix components essential for metastatic progression. We have recently found that both annexin A2 and plasmin are increased in conditioned media of co cultured ovarian cancer and peritoneal cells. Our studies suggest that annexin A2 is part of a tumor-host signal pathway between ovarian cancer and peritoneal cells which promotes ovarian cancer metastasis. Accumulating evidence suggest that interactions between annexin A2 and its binding proteins play an important role in the tumor microenvironment and act together to enhance cancer metastasis. This article reviews the current knowledge on the biological role of annexin A2 and its binding proteins in solid malignancies including ovarian cancer.

Breast cancer cell surface annexin II induces cell migration and neoangiogenesis via tPA dependent plasmin generation

Annexin II, an abundant phospholipids binding cell surface protein, binds tPA and functions as a regulator of fibrinolysis. Annexin II also mediates angiogenesis and enhances tumor growth and metastasis. However, the mechanism supporting this role is not known. Using human breast cancer model we show that invasive human breast cancer cells (MDA-MB231) synthesize annexin II and tissue plasminogen activator (tPA). In vitro both annexin II and tPA interacts which in turn convert zymogen plasminogen to reactive enzyme plasmin. Cell surface produced plasmin inhibited the migration of MDA-MB231 cells. Silencing of annexin II gene in MDA-MB231 cells abolished tPA binding therefore inhibited tPA dependent plasmin generation. These annexin II suppressed MDA-MB231 cells showed reduced motility. Immunohistochemical analysis of prediagnosed clinical specimens showed abundant secretion of tPA and expression of annexin II on the surface of invasive human breast cancer cells which correlates with neovascularization of the tumor. Taken together, these data indicate that annexin II may regulate localized plasmin generation in breast cancer. This may be an early event switching breast cancer from the prevascular phase to the vascular phase and thus contributing to aggressive cancer with the possibility of metastasis. The data provide a mechanism explaining the role of annexin II in breast cancer progression and suggest that annexin II may be an attractive target for therapeutic strategies aimed to inhibit angiogenesis and breast cancer.

Annexin A2 is a molecular target for TM601, a peptide with tumor-targeting and anti-angiogenic effects

TM601 is a synthetic form of chlorotoxin, a 36-amino acid peptide derived from the venom of the Israeli scorpion, Leirius quinquestriatus, initially found to specifically bind and inhibit the migration of glioma cells in culture. Subsequent studies demonstrated specific in vitro binding to additional tumor cell lines. Recently, we demonstrated that proliferating human vascular endothelial cells are the only normal cell line tested that exhibits specific binding to TM601. Here, we identify annexin A2 as a novel binding partner for TM601 in multiple human tumor cell lines and human umbilical vein endothelial cell (HUVEC). We demonstrate that the surface binding of TM601 to the pancreatic tumor cell line Panc-1 is dependent on the expression of annexin A2. Identification of annexin A2 as a binding partner for TM601 is also consistent with the anti-angiogenic effects of TM601. Annexin A2 functions in angiogenesis by binding to tissue plasminogen activator and regulating plasminogen activation on vascular endothelial cells. We demonstrate that in HUVECs, TM601 inhibits both vascular endothelial growth factor- and basic fibroblast growth factor-induced tissue plasminogen activator activation, which is required for activation of plasminogen to plasmin. Consistent with inhibition of cell surface protease activity, TM601 also inhibits platelet-derived growth factor-C induced trans-well migration of both HUVEC and U373-MG glioma cells.