Altered expression of annexin II in human B-cell lymphoma cell lines

Proteomic Portrait of Human Lymphoma Reveals Protein Molecular Fingerprint of Disease Specific Subtypes and Progression

An altered proteome in lymph nodes often suggests abnormal signaling pathways that may be associated with diverse lymphatic disorders. Current clinical biomarkers for histological classification of lymphomas have encountered many discrepancies, particularly for borderline cases. Therefore, we launched a comprehensive proteomic study aimed to establish a proteomic landscape of patients with various lymphatic disorders and identify proteomic variations associated with different disease subgroups. In this study, 109 fresh-frozen lymph node tissues from patients with various lymphatic disorders (with a focus on Non-Hodgkin's Lymphoma) were analyzed by data-independent acquisition mass spectrometry. A quantitative proteomic landscape was comprehensively characterized, leading to the identification of featured protein profiles for each subgroup. Potential correlations between clinical outcomes and expression profiles of signature proteins were also probed. Two representative signature proteins, phospholipid-binding proteins Annexin A6 (ANXA6) and Phospholipase C Gamma 2 (PLCG2), were successfully validated via immunohistochemistry. We also evaluated the capability of acquired proteomic signatures to segregate multiple lymphatic abnormalities and identified several core signature proteins, such as Sialic Acid Binding Ig Like Lectin 1 (SIGLEC1) and GTPase of immunity-associated protein 5 (GIMAP5). In summary, the established lympho-specific data resource provides a comprehensive map of protein expression in lymph nodes during multiple disease states, thus extending the existing human tissue proteome atlas. Our findings will be of great value in exploring protein expression and regulation underlying lymphatic malignancies, while also providing novel protein candidates to classify various lymphomas for more precise medical practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-022-00075-w.

Annexin A2 binds the internal ribosomal entry site of c-myc mRNA and regulates its translation

The expression and localization of the oncoprotein c-Myc is highly regulated at the level of transcription, mRNA transport, translation, as well as stability of the protein. We previously showed that Annexin A2 (AnxA2) binds to a specific localization element in the 3'untranslated region (UTR) of c-myc mRNA and is involved in its localization to the perinuclear region. In the present study, we demonstrate that AnxA2 binds in a Ca²⁺-dependent manner to the internal ribosomal entry site (IRES) containing two pseudo-knots in the 5´UTR of the c-myc mRNA. Here, we employ an in vitro rabbit reticulocyte lysate system with chimeric c-myc reporter mRNAs to demonstrate that binding of AnxA2 to the c-myc IRES modulates the expression of c-Myc. Notably, we show that low levels of AnxA2 appear to increase, while high levels of AnxA2 inhibits translation of the chimeric mRNA. However, when both the AnxA2-binding site and the ribosomal docking site in the c-myc IRES are deleted, AnxA2 has no effect on the translation of the reporter mRNA. Forskolin-treatment of PC12 cells results in upregulation of Ser25 phosphorylated AnxA2 expression while c-Myc expression is down-regulated. The effect of forskolin on c-Myc expression and the level of Ser25 phosphorylated AnxA2 was abolished in the presence of EGTA. These findings indicate that AnxA2 regulates both the transport and subsequent translation of the c-myc mRNA, possibly by silencing the mRNA during its transport. They also suggest that AnxA2 act as a switch to turn off the c-myc IRES activity in the presence of calcium.Abbreviations: AnxA2, Annexin A2; β₂--µglob, β₂-microglobulin; cpm, counts per minute; hnRNP, heterogenous nuclear ribonucleoprotein; IRES, internal ribosomal entry site; ITAF, IRES trans-acting factor; MM, multiple myeloma; PABP, poly(A)-binding protein; PCBP, poly(rC) binding protein; PSF, PTB-associated splicing factor; PTB, polypyrimidine tract binding protein; RRL, rabbit reticulocyte lysate; UTR, untranslated region; YB, Y-box binding protein.

The Protein Landscape of Chronic Lymphocytic Leukemia (CLL)

Many functional consequences of mutations on tumor phenotypes in chronic lymphocytic leukemia (CLL) are unknown. This may be in part due to a scarcity of information on the proteome of CLL. We profiled the proteome of 117 CLL patient samples with data-independent acquisition mass spectrometry (DIA-MS) and integrated the results with genomic, transcriptomic, ex vivo drug response and clinical outcome data. We found trisomy 12, IGHV mutational status, mutated SF3B1, trisomy 19, del(17)(p13), del(11)(q22.3), mutated DDX3X, and MED12 to influence protein expression (FDR < 5%). Trisomy 12 and IGHV status were the major determinants of protein expression variation in CLL as shown by principal component analysis (1055 and 542 differentially expressed proteins, FDR=5%). Gene set enrichment analyses of CLL with trisomy 12 implicated BCR/PI3K/AKT signaling as a tumor driver. These findings were supported by analyses of protein abundance buffering and protein complex formation, which identified limited protein abundance buffering and an upregulated protein complex involved in BCR, AKT, MAPK and PI3K signaling in trisomy 12 CLL. A survey of proteins associated with trisomy 12/IGHV-independent drug response linked STAT2 protein expression with response to kinase inhibitors including BTK and MEK inhibitors. STAT2 was upregulated in U-CLL, trisomy 12 CLL and required for chemokine/cytokine signaling (interferon response). This study highlights the importance of protein abundance data as a non-redundant layer of information in tumor biology, and provides a protein expression reference map for CLL.

Distinct prognostic values of Annexin family members expression in acute myeloid leukemia

BACKGROUND

Annexin family consist of 12 members, many of them are frequently dysregulated in human cancers. However, the diagnosis and prognosis of Annexin family expression in acute myeloid leukemia (AML) remain elusive. The aim of the present study was to assess the prognostic value of Annexin expressions in adult and pediatric AML.

METHODS

GenomicScape tool was used to assess the prognostic value of the expressions of Annexin family members in a cohort of 162 adult AML patients. Quantitative reverse transcript real-time PCR (QRT-PCR) was performed to detect the ANXA2 expression level in the bone marrow-derived mononuclear cells (BMMCs) obtained from 101 pediatric AML patients and 30 controls.

RESULTS

The results demonstrated that high mRNA expressions of ANXA2, ANXA6, and ANXA7 were significantly associated with worse prognosis, while ANXA5 was correlated with better prognosis in adult AML. QRT-PCR analysis showed that ANXA2 expression was dramatically downregulated in BMMCs of pediatric AML patients compared to controls (p < 0.0001). ROC analysis demonstrated that ANXA2 could efficiently differentiate pediatric AML patients from controls (AUC 0.872, p < 0.0001). Likewise, ANXA2 was significantly lower in AML patients with poor-risk karyotype (p = 0.048). Also, the level of ANXA2 trended to decrease in AML patients who had not achieving complete remission. Moreover, patients with lower expression of ANXA2 had higher death rate (p = 0.042) and shorter overall survival (HR 0.55, p = 0.042). Thus, these findings suggest that ANXA2 exerts poor prognostic effect on adult AML but favorable prognostic effect on pediatric AML.

CONCLUSIONS

Collectively, Annexin family members exert distinct prognostic roles in AML, and ANXA2 can be used as a biological marker for diagnosis and prognosis of pediatric AML.

Protein phosphorylation and its role in the regulation of Annexin A2 function

BACKGROUND

Annexin A2 (AnxA2) is a multifunctional protein involved in endocytosis, exocytosis, membrane domain organisation, actin remodelling, signal transduction, protein assembly, transcription and mRNA transport, as well as DNA replication and repair.

SCOPE OF REVIEW

The current knowledge of the role of phosphorylation in the functional regulation of AnxA2 is reviewed. To provide a more comprehensive treatment of this topic, we also address in depth the phosphorylation process in general and discuss its possible conformational effects. Furthermore, we discuss the apparent limitations of the methods used to investigate phosphoproteins, as exemplified by the study of AnxA2.

MAJOR CONCLUSIONS

AnxA2 is subjected to complex regulation by post-translational modifications affecting its cellular functions, with Ser11, Ser25 and Tyr23 representing important phosphorylation sites. Thus, Ser phosphorylation of AnxA2 is involved in the recruitment and docking of secretory granules, the regulation of its association with S100A10, and sequestration of perinuclear, translationally inactive mRNP complexes. By contrast, Tyr phosphorylation of AnxA2 regulates its role in actin dynamics and increases its association with endosomal compartments. Modification of its three main phosphorylation sites is not sufficient to discriminate between its numerous functions. Thus, fine-tuning of AnxA2 function is mediated by the joint action of several post-translational modifications.

GENERAL SIGNIFICANCE

AnxA2 participates in malignant cell transformation, and its overexpression and/or phosphorylation is associated with cancer progression and metastasis. Thus, tight regulation of AnxA2 function is an integral aspect of cellular homeostasis. The presence of AnxA2 in cancer cell-derived exosomes, as well as the potential regulation of exosomal AnxA2 by phosphorylation or other PTMs, are topics of great interest.

Reactive oxygen species exert opposite effects on Tyr23 phosphorylation of the nuclear and cortical pools of annexin A2

Annexin A2 (AnxA2) is a multi-functional and -compartmental protein whose subcellular localisation and functions are tightly regulated by its post-translational modifications. AnxA2 and its Tyr23-phosphorylated form (pTyr23AnxA2) are involved in malignant cell transformation, metastasis and angiogenesis. Here, we show that H₂O₂ exerts rapid, simultaneous and opposite effects on the Tyr23 phosphorylation status of AnxA2 in two distinct compartments of rat pheochromocytoma (PC12) cells. Reactive oxygen species induce dephosphorylation of pTyr23AnxA2 located in the PML bodies of the nucleus, whereas AnxA2 associated with F-actin at the cell cortex is Tyr23 phosphorylated. The H₂O₂-induced responses in both compartments are transient and the pTyr23AnxA2 accumulating at the cell cortex is subsequently incorporated into vesicles and then released to the extracellular space. Blocking nuclear export by leptomycin B does not affect the nuclear pool of pTyr23AnxA2, but increases the amount of total AnxA2 in this compartment, indicating that the protein might have several functions in the nucleus. These results suggest that Tyr23 phosphorylation can regulate the function of AnxA2 at distinct subcellular sites.

Summary: Reactive oxygen species cause two opposite and transient Tyr23-based modifications of annexin A2; its dephosphorylation in the nucleus and phosphorylation at the cell cortex, resulting in release of the protein in exosomes.

A tumor deconstruction platform identifies definitive end points in the evaluation of drug responses

Tumor heterogeneity and the presence of drug-sensitive and refractory populations within the same tumor are almost never assessed in the drug discovery pipeline. Such incomplete assessment of drugs arising from spatial and temporal tumor cell heterogeneity reflects on their failure in the clinic and considerable wasted costs in the drug discovery pipeline. Here we report the derivation of a flow cytometry-based tumor deconstruction platform for resolution of at least 18 discrete tumor cell fractions. This is achieved through concurrent identification, quantification and analysis of components of cancer stem cell hierarchies, genetically instable clones and differentially cycling populations within a tumor. We also demonstrate such resolution of the tumor cytotype to be a potential value addition in drug screening through definitive cell target identification. Additionally, this real-time definition of intra-tumor heterogeneity provides a convenient, incisive and analytical tool for predicting drug efficacies through profiling perturbations within discrete tumor cell subsets in response to different drugs and candidates. Consequently, possible applications in informed therapeutic monitoring and drug repositioning in personalized cancer therapy would complement rational design of new candidates besides achieving a re-evaluation of existing drugs to derive non-obvious combinations that hold better chances of achieving remission.

Annexin A2 complexes with S100 proteins: structure, function and pharmacological manipulation

Annexin A2 (AnxA2) was originally identified as a substrate of the pp60v-src oncoprotein in transformed chicken embryonic fibroblasts. It is an abundant protein that associates with biological membranes as well as the actin cytoskeleton, and has been implicated in intracellular vesicle fusion, the organization of membrane domains, lipid rafts and membrane-cytoskeleton contacts. In addition to an intracellular role, AnxA2 has been reported to participate in processes localized to the cell surface including extracellular protease regulation and cell-cell interactions. There are many reports showing that AnxA2 is differentially expressed between normal and malignant tissue and potentially involved in tumour progression. An important aspect of AnxA2 function relates to its interaction with small Ca²⁺-dependent adaptor proteins called S100 proteins, which is the topic of this review. The interaction between AnxA2 and S100A10 has been very well characterized historically; more recently, other S100 proteins have been shown to interact with AnxA2 as well. The biochemical evidence for the occurrence of these protein interactions will be discussed, as well as their function. Recent studies aiming to generate inhibitors of S100 protein interactions will be described and the potential of these inhibitors to further our understanding of AnxA2 S100 protein interactions will be discussed.

Effect of serine phosphorylation and Ser25 phospho-mimicking mutations on nuclear localisation and ligand interactions of annexin A2

Annexin A2 (AnxA2) interacts with numerous ligands, including calcium, lipids, mRNAs and intracellular and extracellular proteins. Different post-translational modifications participate in the discrimination of the functions of AnxA2 by modulating its ligand interactions. Here, phospho-mimicking mutants (AnxA2-S25E and AnxA2-S25D) were employed to investigate the effects of Ser25 phosphorylation on the structure and function of AnxA2 by using AnxA2-S25A as a control. The overall α-helical structure of AnxA2 is not affected by the mutations, since the thermal stabilities and aggregation tendencies of the mutants differ only slightly from the wild-type (wt) protein. Unlike wt AnxA2, all mutants bind the anxA2 3' untranslated region and β-γ-G-actin with high affinity in a Ca(2+)-independent manner. AnxA2-S25E is not targeted to the nucleus in transfected PC12 cells. In vitro phosphorylation of AnxA2 by protein kinase C increases its affinity to mRNA and inhibits its nuclear localisation, in accordance with the data obtained with the phospho-mimicking mutants. Ca(2+)-dependent binding of wt AnxA2 to phosphatidylinositol, phosphatidylinositol-3-phosphate, phosphatidylinositol-4-phosphate and phosphatidylinositol-5-phosphate, as well as weaker but still Ca(2+)-dependent binding to phosphatidylserine and phosphatidylinositol-3,5-bisphosphate, was demonstrated by a protein-lipid overlay assay, whereas binding of AnxA2 to these lipids, as well as its binding to liposomes, is inhibited by the Ser25 mutations. Thus, introduction of a modification (mutation or phosphorylation) at Ser25 appears to induce a conformational change leading to increased accessibility of the mRNA- and G-actin-binding sites in domain IV independent of Ca(2+) levels, while the Ca(2+)-dependent binding of AnxA2 to phospholipids is attenuated.

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.

Annexin A2 modulates radiation-sensitive transcriptional programming and cell fate

We previously established annexin A2 as a radioresponsive protein associated with anchorage independent growth in murine epidermal cells. In this study, we demonstrate annexin A2 nuclear translocation in human skin organotypic culture and murine epidermal cells after exposure to X radiation (10-200 cGy), supporting a conserved nuclear function for annexin A2. Whole genome expression profiling in the presence and absence of annexin A2 [shRNA] identified fundamentally altered transcriptional programming that changes the radioresponsive transcriptome. Bioinformatics predicted that silencing AnxA2 may enhance cell death responses to stress in association with reduced activation of pro-survival signals such as nuclear factor kappa B. This prediction was validated by demonstrating a significant increase in sensitivity toward tumor necrosis factor alpha-induced cell death in annexin A2 silenced cells, relative to vector controls, associated with reduced nuclear translocation of RelA (p65) following tumor necrosis factor alpha treatment. These observations implicate an annexin A2 niche in cell fate regulation such that AnxA2 protects cells from radiation-induced apoptosis to maintain cellular homeostasis at low-dose radiation.

Proteomic analysis of testis biopsies in men treated with injectable testosterone undecanoate alone or in combination with oral levonorgestrel as potential male contraceptive

Treatment with injectable testosterone undecanoate (TU) alone or in combination with oral levonorgestrel (LNG) resulted in marked decreases in sperm concentrations. In this study, we used proteomic analyses to examine the cellular/molecular events occurring in the human testis after TU or TU + LNG treatment. We conducted a global proteomic analysis of the human testicular biopsies before and at 2 weeks after TU alone or TU + LNG treatment. Proteins showing significant changes in expression were identified and analyzed. As a result, 17 and 46 protein spots were found with significant differential expression after the treatment with TU alone and TU + LNG, respectively. TU treatment changed the expression of heterogeneous nuclear ribonucleoprotein K (hnRNP K), proteasome inhibitor PI31 subunit (PSMF1), and superoxide dismutase [Mn] mitochondrial precursor (SOD2). These proteins inhibit "assembly", induce cell death, and promote compensatory "cell survival" in the testis. After TU + LNG treatment, "proliferation/cell survival" and "apoptosis/death" were the predominant responses in the testis. TU + LNG treatment inhibited the expression of Prolyl 4-hydroxylase beta subunit (P4HB) and Annexin A2 (Annexin II). These proteins are involved in apoptosis and cell proliferation, respectively. TU + LNG treatment also enhanced the expression of SOD2 and Parvalbumin alpha (Pvalb). These two proteins may protect testicular cells against apoptosis/death and promote cell survival. In conclusion, TU and TU + LNG treatments suppress spermatogenesis through different pathways by changing the expression of different proteins. hnRNP K, PSMF1, SOD2, P4HB, Annexin II, and Pvalb, are key proteins that may be early molecular targets responsible for spermatogenesis suppression induced by hormone treatment.

[Annexin A2 expression in head and neck squamous cell carcinoma]

OBJECTIVE

Over-expression of annexin A2 (ANXA2) has been reported in various cancers. However, no data are available on the expression of this protein in head and neck squamous cell carcinomas (HNSCC). The objective of this preliminary study is to investigate the expression of ANXA2 in these carcinomas.

MATERIAL AND METHOD

ANXA2 expression was analyzed by immunohistochemistry in paraffin-embedded sections from 9 patients with premalignant lesions and 21 patients with HNSCC.

RESULTS

All dysplastic tissues showed significantly reduced ANXA2 expression compared to normal tissue. In contrast, ANXA2 expression was observed in all but one of the tumours studied. There was a significant correlation of lower ANXA2 expression with a poorer histological differentiation, larger tumours, and nodal metastases.

CONCLUSIONS

Our data show for the first time that ANXA2 is expressed in head and neck squamous cell carcinomas and that its expression seems to be related with the degree of differentiation status of these tumours.

Role of Annexin-II in GI cancers: interaction with gastrins/progastrins

The role of the gastrin peptide hormones (G17, G34) and their precursors (progastrins, PG; gly-extended gastrin, G-gly), in gastrointestinal (GI) cancers has been extensively reviewed in recent years [W. Rengifo-Cam, P. Singh, Role of progastrins and gastrins and their receptors in GI and pancreatic cancers: targets for treatment, Curr. Pharm. Des. 10 (19) (2004) 2345-2358; M. Dufresne, C. Seva, D. Fourmy, Cholecystokinin and gastrin receptors, Physiol. Rev. 86 (3) (2006) 805-847; A. Ferrand, T.C. Wang, Gastrin and cancer: a review, Cancer Lett. 238 (1) (2006) 15-29]. A possible important role of progastrin peptides in colon carcinogenesis has become evident from experiments with transgenic mouse models [W. Rengifo-Cam, P. Singh, (2004); A. Ferrand, T.C. Wang, (2006)]. It is now known that growth stimulatory and co-carcinogenic effects of gastrin/PG peptides are mediated by both proliferative and anti-apoptotic effects of the peptides on target cells [H. Wu, G.N. Rao, B. Dai, P. Singh, Autocrine gastrins in colon cancer cells Up-regulate cytochrome c oxidase Vb and down-regulate efflux of cytochrome c and activation of caspase-3, J. Biol. Chem. 275 (42) (2000) 32491-32498; H. Wu, A. Owlia, P. Singh, Precursor peptide progastrin(1-80) reduces apoptosis of intestinal epithelial cells and upregulates cytochrome c oxidase Vb levels and synthesis of ATP, Am. J. Physiol. Gastrointest. Liver Physiol. 285 (6) (2003) G1097-G1110]. Several receptor subtypes have been described that mediate growth effects of gastrin peptides [W. Rengifo-Cam, P. Singh (2004); M. Dufresne, C. Seva, D. Fourmy, (2006)]. Recently, we identified Annexin II as a high affinity binding protein for gastrin/PG peptides [P. Singh, H. Wu, C. Clark, A. Owlia, Annexin II binds progastrin and gastrin-like peptides, and mediates growth factor effects of autocrine and exogenous gastrins on colon cancer and intestinal epithelial cells, Oncogene (2006), doi:10.1038/sj.onc.1209798]. Importantly, the expression of Annexin II was required for mediating growth stimulatory effects of gastrin and PG peptides on intestinal epithelial and colon cancer cells [P. Singh, H. Wu, C. Clark, A. Owlia, Annexin II binds progastrin and gastrin-like peptides, and mediates growth factor effects of autocrine and exogenous gastrins on colon cancer and intestinal epithelial cells, Oncogene (2006), doi:10.1038/sj.onc.1209798], suggesting that Annexin-II may represent the elusive novel receptor for gastrin/PG peptides. The importance of this finding in relation to the structure and function of Annexin-II, especially in GI cancers, is described below. Since this surprising finding represents a new front in our understanding of the mechanisms involved in mediating growth effects of gastrin/PG peptides in GI cancers, our current understanding of the role of Annexin-II in proliferation and metastasis of cancer cells is additionally reviewed.

A proteomic study on human osteoblastic cells proliferation and differentiation

Changes in expression profiles for 17 proteins were ascertained in human mature osteoblasts compared to pre-osteoblasts (differentiation markers). A differential approach was used to highlight proteomic changes between human osteosarcoma cells and mature osteoblasts, showing a relative over-expression of 8 proteins (proliferation and tumor indicators), as well as under-expression of proteins also found down-regulated in pre-osteoblasts (specific markers of osteoblast differentiation). Our findings confirmed the differences between cell lines and primary human cell cultures and suggested caution on the use of osteosarcoma to study anti-osteoporotic drugs in humans.

The RacGEF Tiam1 inhibits migration and invasion of metastatic melanoma via a novel adhesive mechanism

Rho-like GTPases such as RhoA, Rac1 and Cdc42 are key regulators of actin-dependent cell functions including cell morphology, adhesion and migration. Tiam1 (T lymphoma invasion and metastasis 1), a guanine nucleotide exchange factor that activates Rac, is an important regulator of cell shape and invasiveness in epithelial cells and fibroblasts. Overexpression of Tiam1 in metastatic melanoma cells converted the constitutive mesenchymal phenotype into an epithelial-like phenotype. This included the induction of stringent cell-cell contacts mediated by the Ig-like receptor ALCAM (activated leukocyte cell adhesion molecule) and actin redistribution to cell-cell junctions. This phenotypic switch was dependent on increased Rac but not Rho activity, and on the redistribution and adhesive function of ALCAM, whereas cadherins were not involved. Although cell proliferation was significantly enhanced, the gain of cell-cell junctions strongly counteracted cell motility and invasion as shown for two- and three-dimensional collagen assays as well as invasion into human skin reconstructs. The reverse transition from mesenchymal invasive to a resident epithelial-like phenotype implicates a role for Tiam1/Rac signaling in the control of cell-cell contacts through a novel ALCAM-mediated mechanism.

Absence of annexin I expression in B-cell non-Hodgkin's lymphomas and cell lines

BACKGROUND

Annexin I, one of the 20 members of the annexin family of calcium and phospholipid-binding proteins, has been implicated in diverse biological processes including signal transduction, mediation of apoptosis and immunosuppression. Previous studies have shown increased annexin I expression in pancreatic and breast cancers, while it is absent in prostate and esophageal cancers.

RESULTS

Data presented here show that annexin I mRNA and protein are undetectable in 10 out of 12 B-cell lymphoma cell lines examined. Southern blot analysis indicates that the annexin I gene is intact in B-cell lymphoma cell lines. Aberrant methylation was examined as a cause for lack of annexin I expression by treating cells 5-Aza-2-deoxycytidine. Reexpression of annexin I was observed after prolonged treatment with the demethylating agent indicating methylation may be one of the mechanisms of annexin I silencing. Treatment of Raji and OMA-BL-1 cells with lipopolysaccharide, an inflammation inducer, and with hydrogen peroxide, a promoter of oxidative stress, also failed to induce annexin I expression. Annexin I expression was examined in primary lymphoma tissues by immunohistochemistry and presence of annexin I in a subset of normal B-cells and absence of annexin I expression in the lymphoma tissues were observed. These results show that annexin I is expressed in normal B-cells, and its expression is lost in all primary B-cell lymphomas and 10 of 12 B-cell lymphoma cell lines.

CONCLUSIONS

Our results suggest that, similar to prostate and esophageal cancers, annexin I may be an endogenous suppressor of cancer development, and loss of annexin I may contribute to B-cell lymphoma development.

CEACAM1, a Cell-Cell Adhesion Molecule, Directly Associates with Annexin II in a Three-dimensional Model of Mammary Morphogenesis

The epithelial cell adhesion molecule CEACAM1 (carcinoembryonic antigen cell adhesion molecule-1) is down-regulated in colon, prostate, breast, and liver cancer. Here we show that CEACAM1-4S, a splice form with four Ig-like ectodomains and a short cytoplasmic domain (14 amino acids), directly associates with annexin II, a lipid raft-associated molecule, which is also down-regulated in many cancers. Annexin II was identified using a glutathione S-transferase pull-down assay in which the cytoplasmic domain of CEACAM-4S was fused to glutathione S-transferase, the fusion protein was incubated with cell lysates, and isolated proteins were sequenced by mass spectrometry. The interaction was confirmed first by reciprocal immunoprecipitations using anti-CEACAM1 and anti-annexin II antibodies and second by confocal laser microscopy showing co-localization of CEACAM1 with annexin II in mammary epithelial cells grown in Matrigel. In addition, CEACAM1 co-localized with p11, a component of the tetrameric AIIt complex at the plasma membrane, and with annexin II in secretory vesicles. Immobilized, oriented peptides from the cytoplasmic domain of CEACAM1-4S were shown to directly associate with bovine AIIt, which is 98% homologous to human AIIt, with average KD values of about 30 nM using surface plasmon resonance, demonstrating direct binding of functionally relevant AIIt to the cytoplasmic domain of CEACAM1-4S.

Expression of biomarkers modulating prostate cancer angiogenesis: differential expression of annexin II in prostate carcinomas from India and USA

BACKGROUND

Prostate cancer (PCa) incidences vary with genetic, geographical and ethnic dietary background of patients while angiogenesis is modulated through exquisite interplay of tumor-stromal interactions of biological macromolecules. We hypothesized that comprehensive analysis of four biomarkers modulating angiogenesis in PCa progression in two diverse populations might explain the variance in the incidence rates.

RESULTS

Immunohistochemical analysis of 42 PCa biopsies reveals that though Anx-II expression is lost in both the Indian and American population with Gleason scores (GS) ranging between 6 and 10, up to 25 % of cells in the entire high grade (GS > 8) PD PCa samples from US show intense focal membrane staining for Anx-II unlike similarly graded specimens from India. Consistent with this observation, the prostate cancer cell lines PC-3, DU-145 and MDA PCa 2A, but not LNCaP-R, LNCAP-UR or MDA PCa 2B cell lines, express Anx-II. Transcriptional reactivation of Anx-II gene with Aza-dC could not entirely account for loss of Anx-II protein in primary PCa. Cyclooxygenase-2 (COX-2) was moderately expressed in most of high grade PIN and some MD PCa and surrounding stroma. COX-2 was not expressed in PD PCa (GS approximately 7-10), while adjacent smooth muscles cells stained weakly positive. Decorin expression was observed only in high grade PIN but not in any of the prostate cancers, atrophy or BPH while stromal areas of BPH stained intensively for DCN and decreased with advancing stages of PCa. Versican expression was weak in most of the MD PCa, moderate in all of BPH, moderately focal in PD PC, weak and focal in PIN, atrophy and adjacent stroma.

CONCLUSIONS

Expression of pro- and anti-angiogenic modulators changes with stage of PCa but correlates with angiogenic status. Focal membrane staining of Anx-II reappears in high grade PCa specimens only from US indicating differential expression of Anx-II. COX-2 stained stronger in American specimens compared to Indian specimens. The sequential expression of DCN and VCN in progressive stages was similar in specimens from India and USA indicating no population-based differences. The mechanistic and regulatory role of Anx-II in PCa progression warrants further investigation.

Nuclear annexin II negatively regulates growth of LNCaP cells and substitution of ser 11 and 25 to glu prevents nucleo-cytoplasmic shuttling of annexin II

BACKGROUND

Annexin II heavy chain (also called p36, calpactin I) is lost in prostate cancers and in a majority of prostate intraepithelial neoplasia (PIN). Loss of annexin II heavy chain appears to be specific for prostate cancer since overexpression of annexin II is observed in a majority of human cancers, including pancreatic cancer, breast cancer and brain tumors. Annexin II exists as a heterotetramer in complex with a protein ligand p11 (S100A10), and as a monomer. Diverse cellular functions are proposed for the two forms of annexin II. The monomer is involved in DNA synthesis. A leucine-rich nuclear export signal (NES) in the N-terminus of annexin II regulates its nuclear export by the CRM1-mediated nuclear export pathway. Mutation of the NES sequence results in nuclear retention of annexin II.

RESULTS

Annexin II localized in the nucleus is phosphorylated, and the appearance of nuclear phosphorylated annexin II is cell cycle dependent, indicating that phosphorylation may play a role in nuclear entry, retention or export of annexin II. By exogenous expression of annexin II in the annexin II-null LNCaP cells, we show that wild-type annexin II is excluded from the nucleus, whereas the NES mutant annexin II localizes in both the nucleus and cytoplasm. Nuclear retention of annexin II results in reduced cell proliferation and increased doubling time of cells. Expression of annexin II, both wild type and NES mutant, causes morphological changes of the cells. By site-specific substitution of glutamic acid in the place of serines 11 and 25 in the N-terminus, we show that simultaneous phosphorylation of both serines 11 and 25, but not either one alone, prevents nuclear localization of annexin II.

CONCLUSION

Our data show that nuclear annexin II is phosphorylated in a cell cycle-dependent manner and that substitution of serines 11 and 25 inhibit nuclear entry of annexin II. Aberrant accumulation of nuclear annexin II retards proliferation of LNCaP cells.

Expression analysis of alpha-NAC and ANX2 in juvenile myelomonocytic leukemia using SMART polymerase chain reaction and "virtual Northern" hybridization

Juvenile myelomonocytic leukemia (JMML) is a malignant hematopoietic disease of early childhood with both myeloproliferative and myelodysplastic features. We had previously identified the genes for the alpha-chain of the nascent polypeptide-associated complex (NACA) and annexin II (ANX2) as potentially involved in the pathophysiology of JMML. Now we used SMART cDNA synthesis and subsequent "virtual Northern" blot to analyze differential expression of NACA and ANX2 genes in various hematologic cell lines and compared the data to those obtained by standard Northern analyses. The results show that SMART cDNA reproduces the expression profile found in mRNA. Dilution experiments showed that analyses using as little as 0.5 ng of total RNA led to reliable results. After validating the technique, we used virtual Northern blots to analyze expression of NACA and ANX2 in progenitor cultures of nine children with JMML and five healthy individuals. We found no consistent pattern of differential expression between patients and healthy donors. We conclude that aberrant regulation of NACA or ANX2 does not play a relevant role in JMML pathogenesis.

Annexin II expression is reduced or lost in prostate cancer cells and its re-expression inhibits prostate cancer cell migration

While studying Bim, a BH3-only proapoptotic protein, we identified an approximately 36 kDa protein, which was abundantly expressed in all five strains of primary normal human prostate (NHP) epithelial cells but significantly reduced or lost in seven prostate cancer cell lines. The approximately 36 kDa protein was subsequently identified as annexin II by proteomic approach and confirmed by Western blotting using an annexin II-specific antibody. Conventional and 2D SDS-PAGE, together with Western blotting, also revealed reduced or lost expression of annexin I in prostate cancer cells. Subcellular localization studies revealed that in NHP cells, annexin II was distributed both in the cytosol and underneath the plasma membrane, but not on the cell surface. Prostate cancer cells showed reduced levels as well as altered expression patterns of annexin II. Since annexins play important roles in maintaining Ca(2+) homeostasis and regulating the cytoskeleton and cell motility, we hypothesized that the reduced or lost expression of annexin I/II might promote certain aggressive phenotypes of prostate cancer cells. In subsequent experiments, we indeed observed that restoration of annexin II expression inhibited the migration of the transfected prostate cancer cells without affecting cell proliferation or apoptosis. Hence, our results suggest that annexin II, and, likely, annexin I, may be endogenous suppressors of prostate cancer cell migration and their reduced or lost expression may contribute to prostate cancer development and progression.

Angiostatin binds to tyrosine kinase substrate annexin II through the lysine-binding domain in endothelial cells

Angiostatin(AS), an internal fragment of plasminogen, is one of the most potent specific inhibitors of angiogenesis. Angiostatin treatment has resulted in the complete regression of human tumors implanted subcutaneously into nude mice and has great therapeutic value (O'Reilly et al., Nat. Med. 2, 689-692, 1996). Despite promising therapeutic value in the treatment of cancer, the mechanism of its action is still unknown. We found that angiostatin binds to a 35-kDa protein in bovine aortic endothelial (BAE) cells (Sharma et al., Proc. Am. Assoc. Cancer Res. 42, 568, A3050, 2002). In an attempt to begin to understand angiostatin's mechanism of action, we have purified and characterized this 35-kDa protein from BAE cells. Internal peptide sequence analysis of purified protein demonstrated (SLYYIQQDTK, SYSPYDMLESIK, and ALLYLXGGDD) 100% sequence identity with tyrosine kinase substrate annexin II. Solid phase binding analysis suggests that angiostatin specifically bound to purified annexin II immobilized on 96-well plastic plates. Hundred-fold molar excess of unlabeled AS and anti-annexin II antibody inhibited bindings 85 and 55%, respectively, suggesting specific interaction. Annexin II is a predominant receptor for angiostatin, since neutralizing the angiostatin by soluble receptor (annexin II) effectively blocks angiostatin's anti-EC activity. Similarly, saturating the annexin II receptor by plasminogen in endothelial cells also blocks angiostatin's activity. Both angiostatin and plasminogen bind to purified annexin II in BAE cells saturably with apparent K(d) values of 101 and 164 nM, respectively, for purified annexin II and K(d) values of 83 and 125 nM, respectively, for BAE cells. Anti-annexin II monoclonal antibody inhibited angiostatin and plasminogen binding to endothelial cells by 68 and 62%, respectively, supporting our in vitro studies that annexin II is a receptor for angiostatin. Angiostatin-binding protein/annexin II specifically expressed in endothelial cells but not in fibroblasts suggests its EC-specific function. Epsilon-aminocaproic acid, a lys analogue, effectively blocks angiostatin and annexin II interaction, indicating that the lysine-binding domain of AS is required for binding to annexin II. These results suggest that the antiangiogenic action of angiostatin may be mediated via interaction with annexin II. Identification of annexin II as a receptor for angiostatin provides further evidence that clotting and fibrinolytic pathways are directly involved in the angiogenic process.

Annexin II overexpression correlates with stromal tenascin-C overexpression: a prognostic marker in colorectal carcinoma

BACKGROUND

Overexpression of annexin II, a calcium-dependent phospholipid-binding protein, has been reported in various carcinomas. One of its ligands is tenascin-C, an extracellular matrix glycoprotein with predominantly antiadhesive qualities that also has been reported to be a prognostic marker for several carcinomas. In the current study, the authors investigated the correlation between the overexpression of annexin II and tenascin-C in colorectal carcinoma.

METHODS

Western blot analysis of annexin II expression was examined in four human colorectal carcinoma cell lines. Using immunohistochemical methods, the authors also examined expression of annexin II and tenascin-C in 105 primary colorectal carcinoma cases.

RESULTS

Although annexin II was expressed in human colon carcinoma cell lines, there was no apparent correlation between its expression level and the metastatic potential of these cell lines. The authors observed overexpression of annexin II and tenascin-C proteins in 29.5% and 49.5%, respectively, of colorectal carcinoma cases. Overexpression of annexin II was found to be correlated significantly with histologic type, tumor size, depth of invasion, and pTNM stage, whereas tenascin-C overexpression was noted to be correlated significantly with histologic type, depth of invasion, lymphatic invasion, venous invasion, lymph node metastasis, and pTNM stage. Expression of annexin II was shown to be correlated significantly with that of tenascin-C. Multivariate analysis demonstrated that annexin II and tenascin-C cooverexpression was an independent factor of poor prognosis in patients with colorectal carcinoma.

CONCLUSIONS

The data from the current study suggest that both annexin II and tenascin-C are overexpressed in advanced colorectal carcinoma and that they may be related to the progression and metastatic spread of colorectal carcinoma.

Control of the nuclear-cytoplasmic partitioning of annexin II by a nuclear export signal and by p11 binding

This study investigated mechanisms controlling the nuclear-cytoplasmic partitioning of annexin II (AnxII). AnxII and its ligand, p11, were localized by immunofluorescence to the cytoplasmic compartment of U1242MG cells, with minimal AnxII or p11 detected within nuclei. Similarly, GFP-AnxII and GFP-p11 chimeras localized to the endogenous proteins. Likewise, GFP-AnxII(1-22) was excluded from nuclei, whereas GFP-AnxII(23-338) and GFP alone were distributed throughout the cells. Immunoprecipitation and biochemical studies showed that GFP-AnxII did not form heteromeric complexes with endogenous p11 and AnxII. Thus, the AnxII N-tail is necessary and sufficient to cause nuclear exclusion of the GFP fusion protein but this does not involve p11 binding. A nuclear export signal consensus sequence was found in the AnxII 3-12 region. The consensus mutant GFP-AnxII(L10A/L12A) confirmed that these residues are necessary for nuclear exclusion. The nuclear exclusion of GFP-AnxII(1-22) was temperature-dependent and reversible, and the nuclear export inhibitor leptomycin B (LmB) caused GFP-AnxII or overexpressed AnxII monomer to accumulate in nuclei. Therefore, AnxII monomer can enter the nucleus and is actively exported. However, LmB had little effect on the localization of AnxII/p11 complex in U1242MG cells, indicating that the complex is sequestered in the cytoplasm. By contrast, LmB treatment of v-src-transformed fibroblasts caused endogenous AnxII to accumulate in nuclei. The LmB-induced nuclear accumulation of AnxII was accelerated by pervanadate and inhibited by genistein, suggesting that phosphorylation promotes nuclear entry of AnxII. Thus, nuclear exclusion of AnxII results from nuclear export of the monomer and sequestration of AnxII/p11 complex, and may be modulated by phosphorylation.

Cell surface complex of cathepsin B/annexin II tetramer in malignant progression

The cysteine protease cathepsin B is upregulated in a variety of tumors, particularly at the invasive edges. Cathepsin B can degrade extracellular matrix proteins, such as collagen IV and laminin, and can activate the precursor form of urokinase plasminogen activator (uPA), perhaps thereby initiating an extracellular proteolytic cascade. Recently, we demonstrated that procathepsin B interacts with the annexin II heterotetramer (AIIt) on the surface of tumor cells. AIIt had previously been shown to interact with the serine proteases: plasminogen/plasmin and tissue-type plasminogen activator (tPA). The AIIt binding site for cathepsin B differs from that for either plasminogen/plasmin or tPA. AIIt also interacts with extracellular matrix proteins, e.g., collagen I and tenascin-C, forming a structural link between the tumor cell surface and the extracellular matrix. Interestingly, cathepsin B, plasminogen/plasmin, t-PA and tenascin-C have all been linked to tumor development. We speculate that colocalization through AIIt of proteases and their substrates on the tumor cell surface may facilitate: (1) activation of precursor forms of proteases and initiation of proteolytic cascades; and (2) selective degradation of extracellular matrix proteins. The recruitment of proteases to specific regions on the cell surface, regions where potential substrates are also bound, could well function as a 'proteolytic center' to enhance tumor cell detachment, invasion and motility.