Annexin A2 localizes to the basal epithelial layer and is down-regulated in dysplasia and head and neck squamous cell carcinoma

Pathobiological functions and clinical implications of annexin dysregulation in human cancers

Annexins are an extensive superfamily of structurally related calcium- and phospholipid-binding proteins, largely conserved and widely distributed among species. Twelve human annexins have been identified, referred to as Annexin A1-13 (A12 remains as of yet unassigned), whose genes are spread throughout the genome on eight different chromosomes. According to their distinct tissue distribution and subcellular localization, annexins have been functionally implicated in a variety of biological processes relevant to both physiological and pathological conditions. Dysregulation of annexin expression patterns and functions has been revealed as a common feature in multiple cancers, thereby emerging as potential biomarkers and molecular targets for clinical application. Nevertheless, translation of this knowledge to the clinic requires in-depth functional and mechanistic characterization of dysregulated annexins for each individual cancer type, since each protein exhibits varying expression levels and phenotypic specificity depending on the tumor types. This review specifically and thoroughly examines the current knowledge on annexin dysfunctions in carcinogenesis. Hence, available data on expression levels, mechanism of action and pathophysiological effects of Annexin A1-13 among different cancers will be dissected, also further discussing future perspectives for potential applications as biomarkers for early diagnosis, prognosis and molecular-targeted therapies. Special attention is devoted to head and neck cancers (HNC), a complex and heterogeneous group of aggressive malignancies, often lately diagnosed, with high mortality, and scarce therapeutic options.

Clinicopathological value and underlying molecular mechanism of annexin A2 in 992 cases of thyroid carcinoma

BACKGROUND

Thyroid carcinoma (THCA) is one of the most frequent endocrine cancers and has increasing morbidity. Annexin A2 (ANXA2) has been found to be highly expressed in various cancers; however, its expression level and potential mechanism in THCA remain unknown. This study investigated the clinicopathological value and primary molecular machinery of ANXA2 in THCA.

MATERIAL AND METHODS

Public RNA-sequencing and microarray data were obtained and analyzed with ANXA2 expression in THCA and corresponding non-cancerous thyroid tissue. A Pearson correlation coefficient calculation was used for the acquisition of ANXA2 coexpressed genes, while edgR, limma, and Robust Rank Aggregation were employed for differentially expressed gene (DEG) in THCA. The probable mechanism of ANXA2 in THCA was predicted by gene ontology and pathway enrichment. A dual-luciferase reporter assay was employed to confirm the targeting relationships between ANXA2 and its predicted microRNA (miRNA).

RESULTS

Expression of ANXA2 was significantly upregulated in THCA tissues with a summarized standardized mean difference of 1.09 (P < 0.0001) based on 992 THCA cases and 589 cases of normal thyroid tissue. Expression of ANXA2 was related to pathologic stage. Subsequently, 1442 genes were obtained when overlapping 4542 ANXA2 coexpressed genes with 2248 DEGs in THCA; these genes were mostly enriched in pathways of extracellular matrix-receptor interaction, cell adhesion molecules, and complement and coagulation cascades. MiR-23b-3p was confirmed to target ANXA2 by dual-luciferase reporter assay.

CONCLUSIONS

Upregulated expression of ANXA2 may promote the malignant biological behavior of THCA by affecting the involving pathways or being targeted by miR-23b-3p.

Annexin A2 Enhances the Progression of Colorectal Cancer and Hepatocarcinoma via Cytoskeleton Structural Rearrangements

Annexin A2 (ANXA2) is reported to be associated with cancer development. To investigate the roles ANXA2 plays during the development of cancer, the RNAi method was used to inhibit the ANXA2 expression in caco2 (human colorectal cancer cell line) and SMMC7721 (human hepatocarcinoma cell line) cells. The results showed that when the expression of ANXA2 was efficiently inhibited, the growth and motility of both cell lines were significantly decreased, and the development of the motility relevant microstructures, such as pseudopodia, filopodia, and the polymerization of microfilaments and microtubules were obviously inhibited. The cancer cell apoptosis was enhanced without obvious significance. The possible regulating pathway in the process was also predicted and discussed. Our results suggested that ANXA2 plays important roles in maintaining the malignancy of colorectal and hepatic cancer by enhancing the cell proliferation, motility, and development of the motility associated microstructures of cancer cells based on a possible complicated signal pathway.

Frequent Alteration of Annexin A9 and A10 in HPV-Negative Head and Neck Squamous Cell Carcinomas: Correlation with the Histopathological Differentiation Grade

The annexin protein superfamily has been implicated in multiple physiological and pathological processes, including carcinogenesis. Altered expression of various annexins has frequently been observed and linked to the development and progression of various human malignancies. However, information is lacking on the expression and clinical significance of annexin A9 (ANXA9) and A10 (ANXA10) in head and neck squamous cell carcinomas (HNSCC). ANXA9 and ANXA10 expression was evaluated in a large cohort of 372 surgically treated HPV-negative HNSCC patients and correlated with the clinicopathologic parameters and disease outcomes. Down-regulation of ANXA9 expression was found in 42% of HNSCC tissue samples, compared to normal epithelia. ANXA9 expression in tumors was significantly associated with oropharyngeal location and histological differentiation grade (P < 0.001). In marked contrast, ANXA10 expression was absent in normal epithelium, but variably detected in the cytoplasm of cancer cells. Positive ANXA10 expression was found in 64% of tumors, and was significantly associated with differentiation grade (P < 0.001), being also more frequent in oropharyngeal tumors (P = 0.019). These results reveal that the expression of both ANXA9 and ANXA10 is frequently altered in HNSCC and associated to the tumor differentiation grade, suggesting that they could be implicated in the pathogenesis of these cancers.

Annexin A2 (ANX A2): An emerging biomarker and potential therapeutic target for aggressive cancers

ANX A2 is an important member of annexin family of proteins expressed on surface of endothelial cells (ECs), macrophages, mononuclear cells and various types of cancer cells. It exhibits high affinity binding for calcium (Ca⁺⁺ ) and phospholipids. ANX A2 plays an important role in many biological processes such as endocytosis, exocytosis, autophagy, cell-cell communications and biochemical activation of plasminogen. On the cell surface ANX A2 organizes the assembly of plasminogen (PLG) and tissue plasminogen activator (tPA) for efficient conversion of PLG to plasmin, a serine protease. Proteolytic activity of plasmin is required for activation of inactive pro-metalloproteases (pro-MMPs) and latent growth factors for their biological actions. These activation steps are critical for degradation of extracellular matrix (ECM) and basement proteins (BM) for cancer cell invasion and metastasis. Increased expression of ANX A2 protein/gene has been correlated with invasion and metastasis in a variety of human cancers. Moreover, clinical studies have positively correlated ANX A2 protein expression with aggressive cancers and with resistance to anticancer drugs, shorter disease-free survival (DFS), and worse overall survival (OS). The mechanism(s) by which ANX A2 regulates cancer invasion and metastasis are beginning to emerge. Investigators used various technologies to target ANX A2 in preclinical model of human cancers and demonstrated exciting results. In this review article, we analyzed existing literature concurrent with our own findings and provided a critical overview of ANX A2-dependent mechanism(s) of cancer invasion and metastasis.

Heterotetrameric annexin A2/S100A10 (A2t) is essential for oncogenic human papillomavirus trafficking and capsid disassembly, and protects virions from lysosomal degradation

Human papillomavirus (HPV) entry into epithelial cells is independent of canonical endocytic pathways. Upon interaction with host cells, HPV establishes infection by traversing through an endocytic pathway that is clathrin- and caveolin-independent, but dependent on the annexin A2/S100A10 heterotetramer (A2t). We examined the contribution of monomeric annexin A2 (AnxA2) vs. A2t in HPV infection and endocytosis, and further characterized the role of these molecules in protein trafficking. We specifically show that cell surface A2t is not required for HPV attachment, and in the absence of A2t virion internalization remains clathrin-independent. Without A2t, viral progression from early endosomes to multivesicular endosomes is significantly inhibited, capsid uncoating is dramatically reduced, and lysosomal degradation of HPV is accelerated. Furthermore, we present evidence that AnxA2 forms a complex with CD63, a known mediator of HPV trafficking. Overall, the observed reduction in infection is less significant in the absence of S100A10 alone compared to full A2t, supporting an independent role for monomeric AnxA2. More broadly, we show that successful infection by multiple oncogenic HPV types is dependent on A2t. These findings suggest that A2t is a central mediator of high-risk HPV intracellular trafficking post-entry and pre-viral uncoating.

Liprin-α1 modulates cancer cell signaling by transmembrane protein CD82 in adhesive membrane domains linked to cytoskeleton

Background

PPFIA1 is located at the 11q13 region commonly amplified in cancer. The protein liprin-α1 encoded by PPF1A1 contributes to the adhesive and invasive structures of cytoskeletal elements and is located at the invadosomes in cancer cells. However, the precise mechanism of liprin-α1 function in cancer progression has remained elusive.

Methods

Invasion regulating activity of liprin-α1 was examined by analyzing the functions of squamous cell carcinoma of head and neck (HNSCC) cell lines in three-dimensional collagen I after RNAi mediated gene knockdown. Transcriptome profiling and Gene Set Enrichment Analysis from HNSCC and breast cancer cells were used to identify expression changes relevant to specific cellular localizations, biological processes and signaling pathways after PPFIA1 knockdown. The significance of the results was assessed by relevant statistical methods (Wald and Benjamini-Hochberg). Localization of proteins associated to liprin-α1 was studied by immunofluorescence in 2D and 3D conditions. The association of PPFIA1 amplification to HNSCC patient survival was explored using The Cancer Genome Atlas data.

Results

In this study, we show that liprin-α1 regulates biological processes related to membrane microdomains in breast carcinoma, as well as protein trafficking, cell-cell and cell-substrate contacts in HNSCC cell lines cultured in three-dimensional matrix. Importantly, we show that in all these cancer cells liprin-α1 knockdown leads to the upregulation of transmembrane protein CD82, which is a suppressor of metastasis in several solid tumors.

Conclusions

Our results provide novel information regarding the function of liprin-α1 in biological processes essential in cancer progression. The results reveal liprin-α1 as a novel regulator of CD82, linking liprin-α1 to the cancer cell invasion and metastasis pathways.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0253-y) contains supplementary material, which is available to authorized users.

Genomic analysis of head and neck cancer cases from two high incidence regions

We investigated how somatic changes in HNSCC interact with environmental and host risk factors and whether they influence the risk of HNSCC occurrence and outcome. 180-paired samples diagnosed as HNSCC in two high incidence regions of Europe and South America underwent targeted sequencing (14 genes) and evaluation of copy number alterations (SCNAs). TP53, PIK3CA, NOTCH1, TP63 and CDKN2A were the most frequently mutated genes. Cases were characterized by a low copy number burden with recurrent focal amplification in 11q13.3 and deletion in 15q22. Cases with low SCNAs showed an improved overall survival. We found significant correlations with decreased overall survival between focal amplified regions 4p16, 10q22 and 22q11, and losses in 12p12, 15q14 and 15q22. The mutational landscape in our cases showed an association to both environmental exposures and clinical characteristics. We confirmed that somatic copy number alterations are an important predictor of HNSCC overall survival.

Annexin A1 down-regulation in head and neck squamous cell carcinoma is mediated via transcriptional control with direct involvement of miR-196a/b

Annexin A1 (ANXA1) down-regulation is an early and frequent event in the development of head and neck squamous cell carcinomas (HNSCC). In an attempt to identify the underlying mechanisms of reduced ANXA1 protein expression, this study investigated ANXA1 mRNA expression in HNSCC specimens by both in situ hybridization and RT-qPCR. Results showed a perfect concordance between the pattern of ANXA1 mRNA and protein detected by immunofluorescence in tumors, precancerous lesions and normal epithelia, reflecting that ANXA1 down-regulation occurs at transcriptional level. We also found that both miR-196a and miR-196b levels inversely correlated with ANXA1 mRNA levels in paired HNSCC tissue samples and patient-matched normal mucosa. In addition, endogenous levels of ANXA1 mRNA and protein were consistently and significantly down-regulated upon miR-196a and miR-196b over-expression in various HNSCC-derived cell lines. The direct interaction of both mature miR-196a and miR-196b was further confirmed by transfection with Anxa1 3′UTR constructs. Combined bioinformatics and functional analysis of ANXA1 promoter activity contributed to identify key regions and potential mediators of ANXA1 transcriptional control. This study unveils that, in addition to miR-196a, miR-196b also directly targets ANXA1 in HNSCC.

Prognostic significance of annexin A2 and annexin A4 expression in patients with cervical cancer

BACKGROUND

The annexins (ANXs) have diverse roles in tumor development and progression, however, their clinical significance in cervical cancer has not been elucidated. The present study was to investigate the clinical significance of annexin A2 (ANXA2) and annexin A4 (ANXA4) expression in cervical cancer.

METHODS

ANXA2 and ANXA4 immunohistochemical staining were performed on a cervical cancer tissue microarray consisting of 46 normal cervical epithelium samples and 336 cervical cancer cases and compared the data with clinicopathological variables, including the survival of cervical cancer patients.

RESULTS

ANXA2 expression was lower in cancer tissue (p = 0.002), whereas ANXA4 staining increased significantly in cancer tissues (p < 0.001). ANXA2 expression was more prominent in squamous cell carcinoma (p < 0.001), whereas ANXA4 was more highly expressed in adeno/adenosquamous carcinoma (p < 0.001). ANXA2 overexpression was positively correlated with advanced cancer phenotypes, whereas ANXA4 expression was associated with resistance to radiation with or without chemotherapy (p = 0.029). Notably, high ANXA2 and ANXA4 expression was significantly associated with shorter disease-free survival (p = 0.004 and p = 0.033, respectively). Multivariate analysis indicated that ANXA2+ (HR = 2.72, p = 0.003) and ANXA2+/ANXA4+ (HR = 2.69, p = 0.039) are independent prognostic factors of disease-free survival in cervical cancer. Furthermore, a random survival forest model using combined ANXA2, ANXA4, and clinical variables resulted in improved predictive power (mean C-index, 0.76) compared to that of clinical-variable-only models (mean C-index, 0.70) (p = 0.006).

CONCLUSIONS

These findings indicate that detecting ANXA2 and ANXA4 expression may aid the evaluation of cervical carcinoma prognosis.

Association of annexin A2 with cancer development (Review)

Annexin A2 (ANXA2) is a well-known calcium-dependent phospholipid binding protein widely distributed in the nucleus, cytoplasm and extracellular surface of various eukaryotic cells. It has been recognized as a pleiotropic protein affecting a wide range of molecular and cellular processes. Dysregulation and abnormal expression of ANXA2 are linked to a large number of prevalent diseases, including autoimmune and neurodegenerative disease, antiphospholipid syndrome, inflammation, diabetes mellitus and a series of cancers. Accumulating data suggest that ANXA2 is aberrantly expressed in a wide spectrum of cancers, and exerts profound effects on tumor cell adhesion, proliferation, apoptosis, invasion and metastasis as well as tumor neovascularization via different modes of action. However, despite significant research, our knowledge of the mechanism by which ANXA2 participates in cancer development remains fragmented. The present review systematically summarizes the effects of ANXA2 on tumor progression, in an attempt to gain an improved understanding of the underlying mechanisms and to provide a potential effective target for cancer therapy.

Identification of tumour-related proteins as potential screening markers by proteome analysis-protein profiles of human saliva as a predictive and prognostic tool

The analysis of biomarkers in saliva as a clinical application offers an attractive, simple and rapid diagnostic tool for the short- and long-term monitoring of pathological disorders and drug therapy. The collection of saliva, either in the pure or in its fractionated form, is a relatively easy and non-invasive procedure that is not harmful to the patients and has no complications at all. However, the fluid collection must be clearly defined due to variations in saliva composition, flow rate and day-to-day variability. In order to minimise possible variations, saliva from five patients without squamous cell carcinoma (SCC) pathology and five with suspicion of oral squamous carcinoma (OSCC) were collected and matched at different days and analysed by two-dimensional polyacrylamide gel electrophoresis (2DE-PAGE). Approximately 800 spots were identified, corresponding to 151 different gene products. The list of identified proteins includes a large number of structural proteins like keratins, keratin subunits, enzymes and enzyme inhibitors, cytokines, immunoglobulins as well as amylase and other salivary specific glycoproteins. The majority of proteins that are localised in oral epithelia cells were found as unsolved debris in saliva. One of the identified proteins was significantly overexpressed in OSCC and was selected for further validation by Western blot analysis.

Annexin A2 knockdown inhibits hepatoma cell growth and sensitizes hepatoma cells to 5-fluorouracil by regulating β-catenin and cyclin D1 expression

Hepatocellular carcinoma (HCC) is one of the most common cancer types, and chemotherapy plays an important role in treatment of HCC. However, long‑term treatment with chemotherapeutic drugs such as 5‑fluorouracil (5‑FU) often results in chemoresistance, and the underlying mechanisms remain unclear. In this study, we showed that the annexin A2 (ANXA2) protein is highly expressed in hepatoma cells compared to healthy cells. Knockdown of the ANXA2 gene inhibited hepatoma cell growth, and the underlying mechanism may involve cell cycle inhibition through downregulation of β‑catenin and cyclin D1. We also investigated the role of ANXA2 in chemotherapeutic treatment with 5‑FU. 5‑FU inhibited hepatoma cell growth, while ANXA2 overexpression reduced, and knockdown enhanced, the effects of 5‑FU on hepatoma cell growth. Furthermore, β‑catenin and cyclin D1 were asscociated with the ANXA2‑induced resistance. Taken together, our data suggest that the ANXA2 protein is a critical factor in HCC and that its downregulation can enhance chemotherapeutic treatment with 5‑FU. ANXA2 may thus constitute a new therapeutic target for HCC.

ERG oncoprotein inhibits ANXA2 expression and function in prostate cancer

Overexpression of ERG in the prostate epithelium, due to chromosomal translocations, contributes to prostate tumorigenesis. Here, genomic analysis of ERG siRNA-treated prostate cells harboring the endogenous TMPRSS2-ERG fusion revealed an inverse relationship between ERG and Annexin A2 (ANXA2) expression at both the RNA and protein level. ANXA2, a Ca(2+)-dependent and phospholipid-binding protein, is involved in various cellular functions, including maintenance of epithelial cell polarity. Mechanistic studies defined the prostate-specific transcription start site of ANXA2 and showed that the recruitment of ERG to the ANXA2 promoter is required for transcriptional repression by ERG. Knockdown of ERG enhanced the apical localization of ANXA2, the bundling of actin filaments at cell-cell junctions and formation of a polarized epithelial phenotype. ERG overexpression disrupted ANXA2-mediated cell polarity and promoted epithelial-mesenchymal transition (EMT) by inhibiting CDC42 and RHOA, and by activating cofilin. Immunohistochemistry demonstrated a reciprocal relationship of ANXA2 and ERG expression in a large fraction of primary prostate cancer clinical specimens. ANXA2 was absent or markedly reduced in ERG(+) tumors, which were mostly well differentiated. ERG(-) tumors, meanwhile, expressed moderate to high levels of ANXA2, and were either poorly differentiated or displayed subsets of poorly differentiated cells. Taken together, the transcriptional repression of ANXA2 by ERG in prostate epithelial cells plays a critical role in abrogating differentiation, promoting EMT, and in the reciprocal correlation of ERG and ANXA2 expression observed in human prostate cancer.

IMPLICATIONS

ANXA2 is a new component of the ERG network with potential to enhance biologic stratification and therapeutic targeting of ERG-stratified prostate cancers.

Serum annexin A2 levels in patients with colon cancer in comparison to healthy controls and in relation to tumor pathology

BACKGROUND

The deregulation and localization of the Annexins is consistently reported to have close relation to tumor cell malignancy, invasion, and metastasis as well as clinical progression of tumors. This study aimed to evaluate serum Annexin A2 (Anx A2) levels in patients with colon cancer in comparison to healthy controls and in relation to demographics and tumor pathology.

MATERIAL AND METHODS

A total of 100 patients (mean (SD) age: 58 (5.8) years, 55.0% females) with colon cancer and 70 controls (mean (SD) age: 59 (5.4) years, 50.0% females) were included. Serum levels for Anx A2 were evaluated in relation to study group, demographics, and tumor pathology.

RESULTS

Serum levels for Anx A2 were significantly lower in patients with colon cancer than in controls (13.1 (4.5) vs. 22.8 (2.1) ng/mL, p<0.001) and significantly decreased with increase in tumor size (p=0.003), and at higher stages of TNM (p=0.004), tumor invasion (p=0.005), lymph node metastasis (p=0.003), and distant metastasis (p=0.005).

CONCLUSIONS

Our findings indicate a significant decrease in Anx A2 expression in colon cancer patients compared to healthy controls and in parallel with tumor progression.

Modulation of hepatitis B surface antigen secretion by annexin II expressed in hepatitis B virus‑producing hepatoma cells

The role of annexin II in hepatitis B virus (HBV)‑associated hepatocellular carcinoma (HCC) remains to be elucidated. Intracellular hepatitis B surface antigen (HBsAg)‑retention contributes to the induction of hepatocarcinogenesis. The present study aimed to investigate the regulation of HBsAg secretion by annexin II expressed in HBV‑producing hepatoma cells. The expression of annexin II was analyzed using western blot analysis in SMMC‑7721, HepG2, HepG2.2.15, 293T and Chinese hamster ovary (CHO) cells. CHO cells transfected with an annexin II plasmid were used as a positive control. The localization of annexin II and HBsAg was observed in the HepG2 and HepG2.2.15 cells using indirect immunofluorescence. HepG2.2.15 cells were transfected with a human immunodeficiency virus‑type 1 viral infectivity factor‑hemagglutinin (Vif‑HA) plasmid or a control vector and, 24 h post‑transfection, MG132 was added to the Vif‑complemented HepG2.2.15 cells. Western blot analysis was performed to detect the expression of annexin II and Vif‑HA. HepG2 cells were cotransfected with HBV and annexin II expression vectors. Western blot analysis was performed to examine the expression of annexin II and an Abbott chemiluminescence immunoassay was used to assess the levels of HBsAg. The expression of annexin II was lower in the HepG2.2.15 cells compared with the SMMC‑7721 and HepG2 cells and the fluorescence signal of annexin II in the HepG2 cells was brighter than in the HepG2.2.15 cells. Annexin II colocalized with HBsAg in the cytosol of the HepG2.2.15 cells. MG132 was not able to increase the stability of annexin II expression in HepG2.2.15 cells. Annexin II reduced the secretion of HBsAg when compared with the control‑transfected HepG2 cells. In conclusion, HBV downregulated the expression of annexin II and annexin II decreased the secretion of HBsAg in HBV‑producing hepatoma cells in favor of intracellular HBsAg storage.

Significance of expression of PKCα, Annexin A2 and S100A10 proteins in gastric cancer

AIM: To investigate the clinical significance of expression of protein kinase C (PKC), Annexin A2 and S100A10 proteins in gastric cancer and provide valuable data for finding diagnosis related proteins in gastric cancer.

METHODS: The expression of PKCα, Annexin A2 and S100A10 proteins was detected by Western blot in normal gastric mucosa and gastric cancer tissues. Moreover, their expression was analyzed by immunohistochemistry in a tissue array containing normal gastric mucosa and gastric cancer tissues. The clinicopathologic significance of their expression was evaluated.

RESULTS: Western blot analysis showed that the expression of PKCα, Annexin A2 and S100A10 proteins was significantly higher in gastric cancer tissue than in normal gastric mucosa tissue (P < 0.01 for all). Immunohistochemistry analysis showed that the positive expression rates of PKCα, Annexin A2 and S100A10 proteins were significantly lower in normal gastric mucosa tissue than in gastric cancer tissue [8.82% (3/34) vs 76.54% (62/81), 5.88% (2/34) vs 79.01% (64/81), 2.94% (1/34) vs 59.26% (48/81); P < 0.01 for all].

CONCLUSION: The expression of PKCα, Annexin A2 and S100A10 proteins is up-regulated in gastric cancer tissue compared with normal gastric mucosa tissue and may be related with the occurrence and differentiation degree of gastric cancer.

Immunohistochemical markers of distant metastasis in laryngeal and hypopharyngeal squamous cell carcinomas

Metastasis remains a major cause of mortality in head and neck squamous cell carcinoma (HNSCC). Current clinicopathological features have shown limited predictability for the risk of distant metastasis in individual patients, and therefore more accurate and reliable markers are needed. The aim of this study was to investigate the ability of various molecular markers present in primary tumors to predict the risk of developing distant metastasis. Restrictive clinical criteria were applied for patient selection in order to carry out a case-control study with comparable clinical features on a group-wide basis and a similar risk of metastasis. All patients were surgically treated (with postoperative radiotherapy when appropriate) and classified as stage IV disease. Immunohistochemical analysis was performed for a panel of proteins known to participate in cellular processes relevant to metastatic dissemination (E-cadherin, annexin A2, cortactin, FAK, EGFR, p53, and p-AKT). Results showed that the loss of E-cadherin expression was significantly correlated with the risk of distant metastasis (P = 0.002; log-rank test), while the loss of annexin A2 expression was nearly statistically significant (P = 0.06). None of the other protein markers assessed were associated with the development of distant metastasis. Therefore, according to our data the loss of epithelial adhesion seems to play a central role in the development of metastasis in HNSCC, and more importantly, immunohistochemical assessment of key proteins involved in cell adhesion regulation, such as E-cadherin could represent a useful tool to evaluate easily and routinely the metastatic potential of these carcinomas.

Annexin A2 promotes the migration and invasion of human hepatocellular carcinoma cells in vitro by regulating the shedding of CD147-harboring microvesicles from tumor cells

It has been reported that Annexin A2 (ANXA2) is up-regulated in hepatocellular carcinoma (HCC), but the roles of ANXA2 in the migration and invasion of HCC cells have not been determined. In this study, we found that ANXA2-specific siRNA (si-ANXA2) significantly inhibited the migration and invasion of HCC cells co-cultured with fibroblasts in vitro. In addition, the production of MMP-2 by fibroblasts cultured in supernatant collected from si-ANXA2-transfected HCC cells was notably down-regulated. ANXA2 was also found to be co-localized and co-immunoprecipitated with CD147. Further investigation revealed that the expression of ANXA2 in HCC cells affected the shedding of CD147-harboring membrane microvesicles, acting as a vehicle for CD147 in tumor-stromal interactions and thereby regulating the production of MMP-2 by fibroblasts. Together, these results suggest that ANXA2 enhances the migration and invasion potential of HCC cells in vitro by regulating the trafficking of CD147-harboring membrane microvesicles.

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.

Annexin A2 heterotetramer: structure and function

Annexin A2 is a pleiotropic calcium- and anionic phospholipid-binding protein that exists as a monomer and as a heterotetrameric complex with the plasminogen receptor protein, S100A10. Annexin A2 has been proposed to play a key role in many processes including exocytosis, endocytosis, membrane organization, ion channel conductance, and also to link F-actin cytoskeleton to the plasma membrane. Despite an impressive list of potential binding partners and regulatory activities, it was somewhat unexpected that the annexin A2-null mouse should show a relatively benign phenotype. Studies with the annexin A2-null mouse have suggested important functions for annexin A2 and the heterotetramer in fibrinolysis, in the regulation of the LDL receptor and in cellular redox regulation. However, the demonstration that depletion of annexin A2 causes the depletion of several other proteins including S100A10, fascin and affects the expression of at least sixty-one genes has confounded the reports of its function. In this review we will discuss the annexin A2 structure and function and its proposed physiological and pathological roles.

Clinical significance of annexin II expression in human non-small cell lung cancer

The aim of the present study is to explore the role of annexin II in the development and progression of human non-small cell lung cancer (NSCLC). Real-time quantitative reverse transcription-polymerase chain reaction was conducted to detect annexin II mRNA expression. Annexin II protein expression was also determined by western blot. In addition, annexin II expression was analyzed by immunohistochemistry in 137 clinicopathologically characterized NSCLC cases. The correlation of annexin II expression with patients' survival rate was assessed by Kaplan-Meier analysis and Cox regression. Our results showed that the expression levels of annexin II mRNA and protein in NSCLC tissues were significantly higher than those in non-cancerous tissues. Immunohistochemistry analysis showed that annexin II expression was significantly correlated with tumor diameter, pathological grade, pT status, pN status, and pleural invasion. The results of the Kaplan-Meier analysis indicated that a high expression level of annexin II resulted in a significantly poor prognosis of NSCLC patients. Multi-variate Cox regression analysis revealed that annexin II expression level was an independent prognostic parameter for the overall survival rate of NSCLC patients. In conclusion, these results suggested that annexin II up-regulation was associated with poor prognosis in NSCLC; therefore, it might act as a prognostic marker and a new potential target for NSCLC treatment.

The S100A10 subunit of the annexin A2 heterotetramer facilitates L2-mediated human papillomavirus infection

Mucosotropic, high-risk human papillomaviruses (HPV) are sexually transmitted viruses that are causally associated with the development of cervical cancer. The most common high-risk genotype, HPV16, is an obligatory intracellular virus that must gain entry into host epithelial cells and deliver its double stranded DNA to the nucleus. HPV capsid proteins play a vital role in these steps. Despite the critical nature of these capsid protein-host cell interactions, the precise cellular components necessary for HPV16 infection of epithelial cells remains unknown. Several neutralizing epitopes have been identified for the HPV16 L2 minor capsid protein that can inhibit infection after initial attachment of the virus to the cell surface, which suggests an L2-specific secondary receptor or cofactor is required for infection, but so far no specific L2-receptor has been identified. Here, we demonstrate that the annexin A2 heterotetramer (A2t) contributes to HPV16 infection and co-immunoprecipitates with HPV16 particles on the surface of epithelial cells in an L2-dependent manner. Inhibiting A2t with an endogenous annexin A2 ligand, secretory leukocyte protease inhibitor (SLPI), or with an annexin A2 antibody significantly reduces HPV16 infection. With electron paramagnetic resonance, we demonstrate that a previously identified neutralizing epitope of L2 (aa 108-120) specifically interacts with the S100A10 subunit of A2t. Additionally, mutation of this L2 region significantly reduces binding to A2t and HPV16 pseudovirus infection. Furthermore, downregulation of A2t with shRNA significantly decreases capsid internalization and infection by HPV16. Taken together, these findings indicate that A2t contributes to HPV16 internalization and infection of epithelial cells and this interaction is dependent on the presence of the L2 minor capsid protein.

The association of annexin A2 and cancers

Annexins are a group of calcium- and phospholipid-dependent proteins. As a member of the annexin, annexin A2 (Anxa2) is widely distributed in nucleus, cytoplasm and extracellular surface and mainly expressed in human endothelial cells, mononuclear cells, macrophages, marrow cells and some tumor cells. Accumulated evidences indicated that Anxa2 deregulation was associated with the occurrence, invasion and metastasis of cancers. Anxa2 up-regulation was related to the development, invasion, metastasis and drug resistance of hepatocellular carcinoma, colorectal cancer, breast cancer, pancreatic cancer, acute promyelocytic leukemia and renal cell carcinoma; while Anxa2 down-regulation was associated with prostate cancer, esophageal squamous carcinoma and nasopharyngeal carcinoma and sinonasal adenocarcinoma. The association between Anxa2 and malignant tumors as well as the potential action mechanisms were summarized in current work. Anxa2 might be used as a potential biomarker for the diagnosis, treatment and prognosis of certain tumors.

Upregulated expression of annexin II is a prognostic marker for patients with gastric cancer

Background

The role of annexin II in the development and progression of gastric cancer was explored.

Methods

Real-time PCR was conducted to detect annexin II and S100A6 mRNA expression. Protein expressions of annexin II and S100A6 were also examined by immunohistochemistry in 436 clinicopathologically characterized gastric cancer cases.

Results

The expression of annexin II and S100A6 mRNA differ significantly among gastric tumor tissue and matched non-cancerous gastric mucosa. Protein levels of annexin II and S100A6 were up-regulated in gastric cancer compared with adjacent non-cancerous tissues. High expression of annexin II correlated with age, location of tumor, size of tumor, differentiation, histological type, depth of invasion, vessel invasion, lymph node metastasis, distant metastasis and Tumor, Node, Metastasis (TNM) stage, and also with expression of S100A6. Further multivariate analysis suggested that expression of annexin II and S100A6 were independent prognostic indicators for gastric cancer.

Cumulative five-year survival rates of patients with high expression of both annexin II and S100A6 was significantly lower than those with low expression of both.

Conclusion

Expression of annexin II in gastric cancer was significantly associated with depth of invasion, lymph node metastasis and distant metastasis, TNM stage, high S100A6 expression, and poor prognosis. Annexin II and S100A6 proteins could be useful prognostic marker to predict tumor progression and prognosis in gastric cancer.

Annexin II binds to capsid protein VP1 of enterovirus 71 and enhances viral infectivity

Enterovirus type 71 (EV71) causes hand, foot, and mouth disease (HFMD), which is mostly self-limited but may be complicated with a severe to fatal neurological syndrome in some children. Understanding the molecular basis of virus-host interactions might help clarify the largely unknown neuropathogenic mechanisms of EV71. In this study, we showed that human annexin II (Anx2) protein could bind to the EV71 virion via the capsid protein VP1. Either pretreatment of EV71 with soluble recombinant Anx2 or pretreatment of host cells with an anti-Anx2 antibody could result in reduced viral attachment to the cell surface and a reduction of the subsequent virus yield in vitro. HepG2 cells, which do not express Anx2, remained permissive to EV71 infection, though the virus yield was lower than that for a cognate lineage expressing Anx2. Stable transfection of plasmids expressing Anx2 protein into HepG2 cells (HepG2-Anx2 cells) could enhance EV71 infectivity, with an increased virus yield, especially at a low infective dose, and the enhanced infectivity could be reversed by pretreating HepG2-Anx2 cells with an anti-Anx2 antibody. The Anx2-interacting domain was mapped by yeast two-hybrid analysis to VP1 amino acids 40 to 100, a region different from the known receptor binding domain on the surface of the picornavirus virion. Our data suggest that binding of EV71 to Anx2 on the cell surface can enhance viral entry and infectivity, especially at a low infective dose.

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.

Annexin A2 as a differential diagnostic marker of hepatocellular tumors

While improved imaging techniques have made it possible to detect focal liver lesions smaller than 1cm in diameter, differentiating benign lesions from hepatocellular carcinoma (HCC) still remains a challenge. To address this problem and obtain a definite diagnosis, needle core biopsies are often performed, leading to an increased need for supportive ancillary techniques in the histopathological assessment of highly differentiated hepatocellular tumors. Here we evaluate the diagnostic value of immunohistologically detected Annexin A2 (ANXA2) expression in highly differentiated liver tumors. ANXA2 is a calcium-dependent phospholipid-binding protein that has been linked to malignant transformation and HCC development. Our data show that adding sinusoidal ANXA2 expression to the already established marker panel (GPC3, GS, and HSP70) increases the accuracy for the detection of well-differentiated HCC (74% sensitivity, 100% specificity). In addition, in our series, the combinations ANXA2-GPC3 and ANXA2-GS performed better compared to the other established marker combinations. In conclusion, we suggest that adding ANXA2 to the established diagnostic marker panel increases the reliability and objectivity of HCC diagnosis in liver biopsies.

Proliferating cell nuclear antigen in the cytoplasm interacts with components of glycolysis and cancer

Proliferating cell nuclear antigen (PCNA) is involved in a wide range of functions in the nucleus. However, a substantial amount of PCNA is also present in the cytoplasm, although their function is unknown. Here we show, through Far-Western blotting and mass spectrometry, that PCNA is associated with several cytoplasmic oncoproteins, including elongation factor, malate dehydrogenase, and peptidyl-prolyl isomerase. Surprisingly, PCNA is also associated with six glycolytic enzymes that are involved in the regulation of steps 4-9 in the glycolysis pathway.

Identification of cellular targets in human intrahepatic cholangiocarcinoma using laser microdissection and accurate mass and time tag proteomics

Obtaining accurate protein profiles from homogeneous cell populations in heterogeneous tissues can enhance the capability to discover protein biomarkers. In this context, methodologies to access specific cellular populations and analyze their proteome with exquisite sensitivity have to be selected. We report here the results of an investigation using a combination of laser microdissection and accurate mass and time tag proteomics. The study was aimed at the precise determination of proteome alterations in intrahepatic cholangiocarcinoma ICC, a markedly heterogeneous tumor. This cancer, which is difficult to diagnose and carries a very poor prognosis, has shown an unexplained increase in incidence over the last few years. Among a pool of 574 identified proteins, we were able to report on altered abundance patterns affecting 39 proteins conforming to a variety of potential tumorigenic pathways. The reliability of the proteomics results was confirmed by Western blot and immunohistochemistry on matched samples. Most of the proteins displaying perturbed abundances had not yet been described in the setting of ICC. These include proteins involved in cell mobility and actin cytoskeleton remodeling, which may participate in the epithelial to mesenchymal transition, a process invoked in migration and invasion of cancer cells. The biological relevance of these findings was explored using a tissue microarray. An increased abundance of vimentin was thus detected in 70% of ICC and none of the controls. These results suggest that vimentin could play a role in the aggressiveness of ICC and provide a basis for the serious outcome of this cancer.

Annexin II represents metastatic potential in clear-cell renal cell carcinoma

BACKGROUND: Annexin II (ANX2) is a multi-functional protein involved in cell proliferation and membrane physiology and is related to cancer progression. The purpose of this study was to assess ANX2 expression in clear-cell (cc) renal cell carcinoma (RCC).

METHODS: The ANX2 expression in 18 primary ccRCCs was examined by real-time reverse transcriptase (RT)–PCR and western blot analyses. Furthermore, immunohistochemical study was performed using paraffin section of 154 primary ccRCCs and 24 metastases. The association between ANX2 expression and the clinicopathological factors and prognosis was analysed.

RESULTS: The ANX2 was upregulated at both mRNA and protein levels in 14 of 18 primary ccRCCs. Immunohistochemical analysis showed that ANX2 was positive in 73 (47.4%) of 154 primary ccRCC and in 21 (87.5%) of 24 metastatic tumours. The ANX2 expression in the primary tumours showed significant associations with a higher stage, a higher nuclear grade. In patients without metastasis, the 5-year metastasis-free rate in patients with ANX2-positive tumour was significantly lower than that in those with ANX2-negative tumour (63.0% vs 90.1%; P<0.0001). Multivariate analysis showed that ANX2 expression is an independent predictor for metastasis.

CONCLUSION: Our findings suggest that ANX2 expression might be a novel predictor of the metastatic potential of ccRCC.

Increased expression of Annexin A2 in oral squamous cell carcinoma

Previously, in vitro cellular carcinogenesis model of oral squamous cell carcinoma (OSCC) was established with a line of human immortalized oral epithelia cells (HIOECs), a line of cancerous HB96 cells, and another kind of cells (HB56 cells) at the early stage of carcinogenesis. In this study, comparative proteomic analysis identified a panel of differentially expressed proteins among these cells, and Annexin A2 shown as one of the significantly up-regulated proteins accompanying cellular transformation. Annexin A2 was further validated for its expression in the three kinds of cells and in the clinical samples of tumour tissues and their adjacent normal epithelia from primary OSCC patients. Western blot analysis and real-time PCR detected increased Annexin A2 protein and mRNA levels in cancerous HB56 and HB96 cells over HIOECs. Immunohistochemistry showed elevated Annexin A2 protein expression in tumour tissues over the adjacent non-malignant epithelia from OSCC patients; however, the mRNA levels between tumour and normal tissues did not change significantly. Interestingly, levels of Annexin A2 protein expression negatively correlated with the tumour differentiation grades. The results presented here suggest that Annexin A2 protein may play important roles in carcinogenesis of OSCC, and it may also serve as a candidate biomarker for pathologic differentiation grade of OSCC.