ANXA2 Human

What is the molecular structure and basic characteristics of human ANXA2?

Human ANXA2 is a 36-kDa protein encoded by the ANXA2 gene, with an expected mass of 38.6 kDa and two reported isoforms . The protein can exist in multiple configurations in vivo, including as a monomer, heterodimer, or heterotetramer . ANXA2 has four forms: secretory, membrane-bound, cytoplasmic, and nuclear .

ANXA2 is also known by several alternative names in the literature:

• ANX2

• ANX2L4

• CAL1H

• HEL-S-270

• Annexin II

• Annexin-2

Methodologically, researchers typically identify ANXA2 through Western blotting, ELISA, immunohistochemistry, or immunofluorescence using specific anti-ANXA2 antibodies. Currently, there are over 617 commercial ANXA2 antibodies available across 34 suppliers, indicating the protein's significance in research .

What cell types express ANXA2 and where is it localized within cells?

ANXA2 is expressed on the surface of multiple cell types, including:

• Endothelial cells

• Macrophages

• Mononuclear cells

• Various cancer cells

Within cells, ANXA2 can be found in multiple compartments, reflecting its diverse functions. The four main localization patterns include:

For accurate localization studies, researchers should employ subcellular fractionation followed by Western blotting or immunofluorescence with compartment-specific markers to confirm ANXA2 distribution patterns .

What are the primary biological functions of ANXA2 in normal human physiology?

ANXA2 orchestrates multiple cellular functions in normal human physiology:

• Vesicle transport - regulates endocytosis and exocytosis

• Cell division - contributes to cytokinesis processes

• Calcium signaling - responds to calcium fluctuations

• Cell growth - influences proliferation pathways

At the endothelial cell surface, ANXA2 forms a heterotetramer with S100A10 (p11), which accelerates tissue plasminogen activator-dependent activation of the fibrinolytic protease plasmin, playing a crucial role in vascular homeostasis and fibrinolysis .

Methodologically, researchers can study these functions through:

• Calcium binding assays to assess ANXA2 activation

• Co-immunoprecipitation to identify binding partners

• RNA interference to evaluate loss-of-function effects

• Plasmin generation assays to measure fibrinolytic activity

ANXA2 functions are regulated by various posttranslational modifications, making it a dynamic responder to cellular conditions .

How does ANXA2 expression correlate with glioma progression and patient outcomes?

ANXA2 expression demonstrates significant correlation with glioma progression:

This correlation has been validated in multiple large datasets:

• The Cancer Genome Atlas (TCGA) database (699 glioma samples)

• Chinese Glioma Genome Atlas (CGGA) database (325 glioma samples)

Methodologically, multivariate Cox regression analysis confirms ANXA2 as an independent risk factor for poor clinical prognosis in glioma patients, suggesting its value as a negative prognostic marker that could be incorporated into molecular diagnostic panels .

What role does ANXA2 play in tumor-associated immune responses and the glioma microenvironment?

ANXA2 exhibits significant connections to immune responses in the glioma microenvironment:

• Immune cell correlation: ANXA2 expression positively correlates with biomarker genes of six key immune cell types in glioma, with particularly strong associations with immunosuppressive cells:

  • Tumor-associated macrophages (TAMs): r = 0.74 (TCGA), r = 0.65 (CGGA)

  • Regulatory T cells (Tregs): r = 0.63 (TCGA), r = 0.55 (CGGA)

  • Myeloid-derived suppressor cells (MDSCs): r = 0.68 (TCGA), r = 0.29 (CGGA)

• Immunosuppression mechanisms: ANXA2 contributes to glioma immune escape through:

  • Promoting increased proportion of Treg cells

  • Enhancing expression of immune checkpoint molecules

  • Reducing proportion of natural killer cells and dendritic cells

  • Downregulating expression of inhibitory molecules

• T cell inhibition: ANXA2 regulates the actin cytoskeleton, which negatively affects T cell aggregation, potentially reducing T cell activation and creating immune imbalance in the tumor microenvironment .

Methodologically, researchers can investigate these immune interactions using:

• Single-cell RNA sequencing of tumor samples

• Immune cell co-culture systems with ANXA2 manipulation

• Flow cytometric analysis of immune cell populations

• Spatial transcriptomics to map ANXA2 and immune cell distributions

These findings suggest ANXA2-targeted immunotherapy could potentially reduce immunosuppression in glioma and improve patient outcomes .

How is ANXA2 involved in hypoxia response and angiogenesis?

ANXA2 demonstrates important functions in hypoxia response and neovascularization:

• Hypoxic regulation: ANXA2 is upregulated under hypoxic conditions, suggesting its role as part of the cellular adaptation to low oxygen environments .

• Vascular impact: Evidence from animal models shows that:

  • Mice deficient in ANXA2 are resistant to oxygen-induced retinal neovascularization

  • This suggests ANXA2 plays a critical role in promoting new blood vessel formation under pathological conditions

• Clinical implications: These findings suggest ANXA2 may be involved in human retinal vascular proliferation disorders and other pathological angiogenesis conditions .

Methodologically, researchers studying ANXA2 in hypoxia and angiogenesis should consider:

• Hypoxic chamber experiments with ANXA2 knockdown/overexpression

• Endothelial tube formation assays to assess angiogenic potential

• In vivo models using ANXA2-deficient animals

• Analysis of hypoxia-inducible factor (HIF) binding sites in the ANXA2 promoter

Understanding these mechanisms could lead to novel anti-angiogenic therapeutic approaches for conditions characterized by pathological vessel growth .

What are the most effective methods for studying ANXA2 post-translational modifications and their functional impacts?

ANXA2 undergoes various post-translational modifications that significantly influence its functions. Research approaches should include:

• Identification methods:

  • Mass spectrometry to map specific modification sites

  • Phospho-specific or other modification-specific antibodies

  • 2D gel electrophoresis to separate modified forms

• Functional analysis:

  • Site-directed mutagenesis of modification sites

  • Pharmacological inhibitors of specific modifying enzymes

  • In vitro modification assays to assess catalytic changes

• Cellular impact assessment:

  • Microscopy to track localization changes of modified ANXA2

  • Co-immunoprecipitation to identify altered protein interactions

  • Activity assays (e.g., plasmin generation) to measure functional consequences

Many ANXA2 functions are regulated by these modifications, making them critical targets for understanding ANXA2's role in both normal physiology and disease states .

What experimental approaches are optimal for investigating ANXA2's role in the heterotetramer complex with S100A10 (p11)?

Studying the ANXA2-S100A10 heterotetramer (A2- p11) requires specialized approaches:

• Complex isolation and characterization:

  • Co-immunoprecipitation with either ANXA2 or S100A10 antibodies

  • Size exclusion chromatography to isolate the heterotetrameric complex

  • Cross-linking mass spectrometry to map interaction interfaces

  • Surface plasmon resonance to measure binding kinetics

• Functional analysis:

  • Plasmin generation assays to measure fibrinolytic activity

  • Mutagenesis of key binding residues to disrupt complex formation

  • Competitive peptides to inhibit complex assembly

  • Cell-based assays in endothelial cells where the complex naturally functions

• Visualization techniques:

  • Proximity ligation assays to visualize interactions in situ

  • FRET/BRET to measure real-time complex dynamics

  • Super-resolution microscopy to localize the complex at the cell surface

This complex accelerates tissue plasminogen activator-dependent activation of plasmin, playing crucial roles in fibrinolysis and vascular function . Understanding the heterotetramer's assembly, regulation, and activity is essential for developing potential therapeutic interventions for thrombotic or hemorrhagic disorders.

How can researchers effectively analyze and interpret ANXA2 expression patterns in patient tumor samples?

For robust analysis of ANXA2 in patient samples, researchers should employ:

• Multi-omic approaches:

  • RNA-seq for transcriptional analysis

  • Proteomics for protein level quantification

  • Integrate with genomic data (mutations, CNVs)

  • Single-cell approaches for cellular heterogeneity assessment

• Statistical methods for clinical correlation:

  • Kaplan-Meier survival analysis stratified by ANXA2 expression

  • Cox regression to determine independent prognostic value

  • Correlation analysis with established biomarkers

  • Machine learning algorithms for pattern recognition

• Validation strategies:

  • Multiple independent cohorts (like TCGA and CGGA databases)

  • Different analytical platforms (RNA-seq, qPCR, IHC)

  • Bench validation of computational findings

  • Prospective sample collection and analysis

When analyzing expression patterns in glioma, researchers should consider:

• Stratification by WHO grade (II-IV)

• IDH mutation status

• Molecular subtypes (especially mesenchymal)

• Patient demographics and treatment history

What is the potential of ANXA2 as a therapeutic target in glioma and other cancers?

ANXA2 presents several promising avenues for therapeutic targeting:

• Target rationale:

  • Overexpressed in multiple aggressive cancers

  • Associated with poor patient prognosis

  • Involved in multiple cancer hallmarks (invasion, metastasis, therapy resistance)

  • Linked to immunosuppressive microenvironment

• Potential therapeutic approaches:

  • Monoclonal antibodies against cell-surface ANXA2

  • Small molecule inhibitors of ANXA2-protein interactions

  • Peptide-based disruptors of ANXA2-S100A10 complex

  • ANXA2-targeted immunotherapy approaches

• Combination strategies:

  • ANXA2 inhibition + conventional chemotherapy

  • ANXA2 inhibition + immune checkpoint blockade

  • ANXA2 inhibition + anti-angiogenic therapy

  • ANXA2 inhibition + radiation therapy

How can ANXA2 be effectively utilized as a biomarker in cancer diagnosis and prognosis?

ANXA2 demonstrates significant potential as a clinical biomarker:

ANXA2's use as a biomarker has precedent in multiple cancers. For example, it has been used as an immunosensor for lung cancer detection and for early diagnosis of liver cancer via ELISA . Implementation in clinical practice would require standardized detection methods and establishment of validated cutoff values for high vs. low expression.

What is the relationship between ANXA2 and coagulation disorders in various disease contexts?

ANXA2 plays significant roles in coagulation and fibrinolysis across multiple conditions:

• Thrombotic conditions:

  • In antiphospholipid syndrome, anti-ANXA2 antibodies are associated with clinical thrombosis

  • These antibodies may interfere with ANXA2's normal fibrinolytic functions

  • ANXA2 targeting could potentially modulate thrombotic risk

• Hemorrhagic conditions:

  • Overexpression of ANXA2 in acute promyelocytic leukemia promotes hyperfibrinolytic bleeding

  • This suggests ANXA2 inhibition might help manage bleeding complications

  • Monitoring ANXA2 levels could predict bleeding risk

• Mechanistic basis:

  • ANXA2 at the endothelial cell surface forms a heterotetramer with S100A10 (p11)

  • This complex accelerates tissue plasminogen activator-dependent activation of plasmin

  • The resulting plasmin is a key fibrinolytic protease that degrades fibrin clots

Methodologically, researchers investigating ANXA2 in coagulation should consider:

• Plasmin generation assays

• Clot lysis time measurements

• Thromboelastography

• In vivo thrombosis models with ANXA2 manipulation

• Analysis of ANXA2 autoantibodies in patient plasma

Understanding these mechanisms could lead to novel diagnostic and therapeutic approaches for both thrombotic and hemorrhagic disorders .

How does ANXA2 contribute to therapy resistance mechanisms in cancer?

ANXA2 has been implicated in multiple therapy resistance pathways:

• Resistance mechanisms:

  • ANXA2 promotes resistance to radiotherapy, chemotherapy, and immunotherapy

  • May be involved in cancer stem cell formation and maintenance

  • Contributes to epithelial-mesenchymal transition (EMT), increasing cellular plasticity

  • Supports tumor microenvironment remodeling that protects cancer cells

• Research approaches:

  • Drug-resistant cell line models with ANXA2 modulation

  • Patient-derived xenografts from treatment-resistant tumors

  • Temporal analysis of ANXA2 expression during treatment courses

  • Combination therapy testing with ANXA2 inhibition

• Clinical correlations:

  • Analysis of pre- and post-treatment ANXA2 expression

  • Correlation of ANXA2 levels with time to recurrence

  • Examination of ANXA2 in matched primary and recurrent tumors

  • Patient stratification based on ANXA2 status for therapy selection

Understanding ANXA2's role in therapy resistance could potentially lead to strategies that re-sensitize tumors to existing therapies, particularly in aggressive cancers like glioblastoma where treatment options remain limited .

What is the role of ANXA2 in the interaction between cancer cells and their microenvironment?

ANXA2 coordinates complex interactions within the tumor microenvironment:

• Immune cell interactions:

  • Strong correlations with tumor-associated macrophages (r = 0.74 in TCGA, r = 0.65 in CGGA)

  • Associations with regulatory T cells (r = 0.63 in TCGA, r = 0.55 in CGGA)

  • Relationships with myeloid-derived suppressor cells (r = 0.68 in TCGA, r = 0.29 in CGGA)

  • Interaction with DC-SIGN (CD209) leading to immunosuppression

• Extracellular matrix remodeling:

  • ANXA2's role in plasmin activation influences ECM degradation

  • May facilitate cancer cell invasion and migration

  • Potentially contributes to pre-metastatic niche formation

• Vascular interactions:

  • Promotes angiogenesis under hypoxic conditions

  • Influences vascular permeability and integrity

  • May regulate immune cell trafficking into tumors

Research methodologies to investigate these interactions include:

• 3D co-culture systems with multiple cell types

• Extracellular vesicle isolation and characterization

• Spatial transcriptomics/proteomics of tumor sections

• Intravital microscopy to observe real-time interactions

These microenvironment interactions make ANXA2 a potential master regulator of tumor ecology, suggesting that targeting ANXA2 could disrupt multiple tumor-supporting networks simultaneously .