Role Of Annexin Research Articles

Abstract 3026: Role of AnnexinA2, Sema3D and PlexinD1 in mediating perineural invasion as a mechanism of metastasis in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDA) is a devastating malignant disease. Upon diagnosis, eighty percent of patients present with metastatic disease. Perineural invasion, the spreading of cancer to the space surrounding or invading the nerve, is often found in surgically removed pancreatic tumors and is associated with a worse overall prognosis including high risk of recurrence and metastasis. Perineural invasion is thought to represent the initial steps of metastasis; however, the mechanism that mediates the role of neurons in precancerous inflammation and pancreatic cancer initiation is not known. We have previously found that Annexin A2 (AnxA2), is a metastasis-associated protein in PDA and is not required for primary PDA growth but is essential for the metastasis in genetically engineered spontaneous pancreatic tumor producing KPC mice. Knock-down of AnxA2 results in diminished metastasis and prolonged survival in mouse liver metastasis models of PDA. Moreover, the presence of perineural invasion is AnxA2 dependent in this model. By comparing tumor cells of AnxA2 wild type vs. knock-out KPC mice, we identified Semaphorin 3D (Sema3D) and PlexinD1 (PlxnD1) were among the most differentially expressed genes. We found that AnxA2 regulates the secretion of Sema3D. Originally characterized as axon guidance genes, ligand Sema3D along with its receptor PlxnD1 and co-receptor, Neuropilin 1 (NP1), are among the cellular pathways most frequently altered at the genetic level in PDA. Moreover, we found that knock down of Sema3D or PlxnD1 suppresses metastasis formation in mouse models of PDA (Foley et al. Science Signaling 2015). In the present study, our lab has found that PNI was present in 9/10 human PDA samples with abundant Sema3D expression compared to only 3/10 human PDA samples with low Sema3D expression. Using a Dorsal Root Ganglion (DRG) invasion assay, we found paracrine signaling between DRG and pancreatic cancer cells is important for increasing tumor cell invasion toward DRGs. Using small interfering RNA for AnxA2 in tumor cells, we find that decrease in AnxA2 significantly decreases tumor invasion. Furthermore, knock down of Sema3D from tumor cells, using shRNA, shows significant decrease in tumor cell invasion toward DRGs. We have also tested the role of the Sema3D receptor, PlexinD1, on DRGs in regulating the invasion of tumor cells towards nerves. A neutralizing antibody for PlexinD1 treated on DRGs caused significant decrease in tumor cell invasion in comparison to DRGs treated with IgG isotype control. These results demonstrate that AnxA2, Sema3D and PlexinD1 are involved in paracrine signaling between the tumor cells and nerves. Taken together, we conclude AnxA2/Sema3D/PlexinD1 signaling may aid in mediating perineural invasion of tumor cells towards nerves as a mechanism of metastasis in pancreatic ductal adenocarcinoma. Citation Format: Noelle R. Jurcak, Kenji Fujiwara, Agnieszka A. Rucki, Kelly Foley, Adrian Murphy, Stephen Muth, Abigail Brittingham, Elizabeth M. Jaffee, Lei Zheng. Role of AnnexinA2, Sema3D and PlexinD1 in mediating perineural invasion as a mechanism of metastasis in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3026.

Knockdown of annexin A5 restores gefitinib sensitivity by promoting G2/M cell cycle arrest

BackgroundEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, including gefitinib, are first-line drugs against advanced non-small cell lung cancer with activating EGFR mutations. However, the development of resistance to such drugs is a major clinical challenge.MethodsThe role of annexin A5 in resistance to EGFR tyrosine kinase inhibitors was investigated by qPCR and western blot of relevant molecules, by CCK8 and EdU assay of cell proliferation and viability, by annexin V/propidium iodide assay of apoptosis and cell cycle distribution, by JC-1 assay of mitochondrial integrity, and by xenograft assay of tumorigenicity.ResultsWe found that annexin A5 is upregulated in gefitinib-resistant cell lines, as well as in clinical specimens resistant to EGFR tyrosine kinase inhibitors. Accordingly, knockdown of the gene from gefitinib-resistant cells restores gefitinib sensitivity in vitro and in vivo by downregulating polo-like kinase 1 signal pathway, thereby inducing mitochondrial damage, caspase activation, cell cycle arrest at G2/M, and, finally, apoptosis.ConclusionsThe data indicate that annexin A5 confers gefitinib resistance in lung cancer by inhibiting apoptosis and G2/M cell cycle arrest, and is thus a potential therapeutic target in non-small cell lung cancers resistant to EGFR tyrosine kinase inhibitors.

Association of serum annexin A1 with treatment response and prognosis in patients with esophageal squamous cell carcinoma.

Annexin A1 (ANXA1), a calcium-dependent phospholipid binding protein, is known to be regulated by microRNA-196a (miR-196a) in esophageal adenocarcinoma, and its high expression in tumor tissue is correlated with the poor prognosis of esophageal squamous cell carcinoma (ESCC). However, the role of ANXA1 in the serum of patients with ESCC remains unclear. In this study, we used enzyme-linked immunosorbent assay to evaluate the levels of ANXA1 and real-time polymerase chain reaction to detect the expression of miR-196a in the serum of ESCC patients (healthy donors as controls) and evaluated the relationship between ANXA1 and clinical outcomes. The results showed that the level of serum ANXA1 in ESCC patients was significantly lower than that in controls (P = 0.001) but increased after chemoradiotherapy (P = 0.001). There was no correlation between the baseline level of serum ANXA1 and the short-term efficacy of treatment (P = 0.26) as well as the 1-year progression-free survival (PFS) (P = 0.094). However, there existed a significant correlation between the increases of serum ANXA1 expression and the 1-year PFS (P = 0.04). A higher increase (>2-fold of baseline) in the serum ANXA1 levels was correlated with a poorer PFS (hazard ratio = 3.096, 95% confidence interval 1.239-7.861). There was an inverse correlation between the expressions of miR-196a and ANXA1 in serum (Pearson's correlation of -0.54, P = 0.021). Our data revealed that the expression of serum ANXA1 in ESCC patients increases after chemoradiotherapy and the increased fold change in serum ANXA1 confers independent negative prognostic impact in ESCC. The higher the increase in serum ANXA1 levels, the poorer the outcome.

Role of annexin A5 in tumor and basic research on the target of it

As a key protein, annexin A5 involves in the process of invasion, metastasis and immune tolerance of tumors. And annexin A5 can not only promote the tumor, but also inhibit it. It has been widely concerned in the basic research targeting annexin A5. Because of the high affinity of annexin A5 for phosphatidylserine, annexin A5 is expected to be a new diagnostic marker and anti-tumor target. Key words: Annexin A5; Neoplasm invasiveness; Neoplasm metastasis; Signal transduction; Immune tolerance

Investigating the role of Annexin A1 in Adipogenesis and its ability to dampen Obesity associated Inflammation

Investigating the role of Annexin A1 in Adipogenesis and its ability to dampen Obesity associated Inflammation

Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells.

Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.

Annexin A1 Is Involved in the Resolution of Inflammatory Responses duringLeishmania braziliensisInfection

Leishmaniases are diseases caused by several Leishmania species. Leishmania (Viannia) braziliensis can cause localized cutaneous leishmaniasis (LCL), which heals spontaneously, or mucosal leishmaniasis (ML), characterized by chronic and intense inflammation and scanty parasitism. Annexin A1 (AnxA1) is a protein involved in modulation and resolution of inflammation through multiple mechanisms. In the present study, the role of AnxA1 was investigated in L. braziliensis-infected BALB/c mice. AnxA1 levels increased at the peak of tissue lesion and parasitism in infected mice. AnxA1 increased also after L. braziliensis infection of BALB/c (wild-type [WT]) bone marrow derived macrophages. Despite a lower parasite intake, parasite burden in bone marrow-derived macrophages from AnxA1-/- mice was similar to WT and associated with an early increase of TNF-α and, later, of IL-10. AnxA1-/- mice controlled tissue parasitism similarly to WT animals, but they developed significantly larger lesions at later stages of infection, with a more pronounced inflammatory infiltrate and increased specific production of IFN-γ, IL-4, and IL-10. AnxA1-/- mice also presented higher phosphorylation levels of ERK-1/2 and p65/RelA (NF-κB) and inducible NO synthase expression, suggesting that AnxA1 may be involved in modulation of inflammation in this model of experimental leishmaniasis. Finally, assessment of AnxA1 levels in sera from patients with LCL or ML revealed that ML patients had higher levels of serum AnxA1 than did LCL patients or control subjects. Collectively, these data indicate that AnxA1 is actively expressed during L. braziliensis infection. In the absence of AnxA1, mice are fully able to control parasite replication, but they present more intense inflammatory responses and delayed ability to resolve their lesion size.

Annexin A1 as a target for managing murine pristane-induced systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a polygenic pathological disorder which involves multiple organs. Self-specific B cells play a main role in the lupus pathogenesis by generating autoantibodies as well as by serving as important autoantigen-presenting cells. Autoreactive T lymphocytes, on the other hand, are responsible for B cell activation and proliferation, and cytokine production. Therefore, both factors promote the idea that a down-modulation of activated self-reactive T and B cells involved in the pathogenic immune response is a reasonable approach for SLE therapy. Annexin A1 (ANX A1) is expressed by many cell types and binds to phospholipids in a Ca2+ dependent manner. Abnormal expression of ANX A1 was found on activated B and T cells in both murine and human autoimmunity, suggesting its potential role as a therapeutic target. While its role on T lymphocytes is through formyl peptide receptor-like molecules (FPRL), and the formed ANX A1/FPRL pathway modulates T cell receptor signalling, there is still no fool-proof data available for the role of ANX A1 in B cells. We employed a lupus model of Balb/c mice with pristane-induced SLE which very closely resembles human lupus. In the present study, we investigated the possibility to modulate the autoimmune response in a pristane-induced mouse model of SLE using an anti- ANX A1 antibody. Administration of this monoclonal antibody resulted in the inhibition of T-cell activation and proliferation, suppression of IgG anti-dsDNA antibody-secreting plasma cells and of proteinuria, decreased disease activity and prolonged survival compared to control group.

Downregulation of Annexin A1 is correlated with radioresistance in nasopharyngeal carcinoma.

Radiotherapy is the primary treatment for nasopharyngeal carcinoma (NPC), but radioresistance often remains an obstacle to successful treatment. In our previous study, it was demonstrated that Annexin A1 (ANXA1) was involved in the p53-mediated radioresponse in NPC cells, which suggested that it may be associated with radioresistance in NPC; however, the role of ANXA1 in NPC radioresistance is unknown. In the present study, CNE2 cells were stably transfected with pLKO.1-ANXA1-small hairpin (sh)RNAs to investigate the effects of ANXA1 on the radiosensitivity of NPC. CNE2 cells transfected with pLKO.1 were used as the control. The radiosensitivities of the cells in vitro were analyzed using the clonogenic survival assay, cell growth analysis, flow cytometry and Hoechst 33258 staining. ANXA1 downregulation significantly enhanced clonogenic survival and cell growth following treatment of CNE2 cells with ionizing radiation (IR), increased the number of cells in the S phase and decreased IR-induced apoptosis. These results suggested that the radiosensitivity of CNE2 cells transfected with ANXA1-specific shRNA was significantly lower compared with the control cells. Therefore, ANXA1 downregulation may be involved in the radioresistance of NPC, and ANXA1 may be considered a novel biomarker for predicting NPC response to radiotherapy.

More than just innate affairs – on the role of annexins in adaptive immunity

In more than 30 years of research annexins have been demonstrated to regulate immune responses. The prototype member of this family, annexin (Anx) A1, has been widely recognized as an anti-inflammatory mediator affecting migration and cellular responses of various cell types of the innate immune system. Evidently, effects on innate immune cells also impact on the course of adaptive immune responses. Innate immune cells provide a distinct cytokine milieu during initiation of adaptive immunity which regulates the development of T cell responses. Moreover, innate immune cells such as monocytes can differentiate into dendritic cells and take an active part in T cell stimulation. Accumulating evidence shows a direct role for annexins in adaptive immunity. Anx A1, the annexin protein studied in most detail, has been shown to influence antigen presentation as well as T cells directly. Moreover, immune modulatory roles have been described for several other annexins such as Anx A2, Anx A4, Anx A5 and Anx A13. This review will focus on the involvement of Anx A1 and other annexins in central aspects of adaptive immunity, such as recruitment and activation of antigen presenting cells, T cell differentiation and the anti-inflammatory removal of apoptotic cells.

Annexin A2 Modulates ROS and Impacts Inflammatory Response via IL-17 Signaling in Polymicrobial Sepsis Mice.

Sepsis is a progressive disease manifesting excessive inflammatory responses, severe tissue injury, organ dysfunction, and, ultimately, mortality. Since currently, there are limited therapeutic options for this disease, further understanding the molecular pathogenesis of sepsis may help develop effective treatments. Here we identify a novel role for Annexin A2 (AnxA2), a multi-compartmental protein, in inhibiting pro-inflammatory response by regulating reactive oxygen species (ROS) and IL-17 signaling during sepsis. In cecal ligation and puncture (CLP) sepsis models, anxa2 -/- mice manifested increased pro-inflammatory cytokines and neutrophil infiltration, but decreased bacterial clearance and animal survival. In addition, AnxA2 deficiency led to intensified ROS and IL-17A. Using site directed mutagenesis, we uncovered that cysteine 9 of AnxA2 was the most important aa (site) for regulation of ROS levels. Furthermore, ROS appears to be responsible for elevated IL-17A levels and subsequently exaggerated inflammatory response. Depletion of IL-17 via CRISPR/Cas9 KO strategy down-regulated inflammation and conferred protection against sepsis in anxa2 -/- mice. Our findings reveal a previously undemonstrated function for AnxA2 in inflammatory response in polymicrobial sepsis models via an AnxA2-ROS-IL-17 axis, providing insight into the regulation of pathophysiology of sepsis.

Annexin A2, an essential partner of the exocytotic process in chromaffin cells

Annexin A2 is a calcium-, actin-, and lipid-binding protein implicated in exocytosis in different cell types, such as neuroendocrine cells. In chromaffin cells, cytosolic annexin A2 is recruited to the plasma membrane upon cell stimulation. Here, we review the latest evidence detailing the functional importance of annexin A2 in different stages of exocytosis. These include the recruitment of annexin A2 to the plasma membrane near soluble N-ethylmaleimide-sensitive factor attachment protein receptor complexes, the role of annexin A2 in the formation of lipid domains at exocytotic sites, and finally the annexin A2 bundling of actin microfilaments associated with chromaffin granules. These structures induce first the coalescence of lipid domains required for the formation of the exocytotic site, and in the second time, exert mechanical force on the granule to favor fusion pore expansion and squeeze the granule to facilitate catecholamine release. Annexin A2 is a calcium-, actin-, and lipid-binding protein implicated in exocytosis in different cell types, including neuroendocrine cells. Upon cell stimulation, annexin A2 translocates from the cytosol to the plasma membrane of chromaffin cells and bundles actin filaments associated with chromaffin granules. This promotes the formation of lipid domains required for granule docking, and facilitates catecholamine release by compressing the granule. This article is part of a mini review series on Chromaffin cells (ISCCB Meeting, 2015).

Influenza A virus enhances its propagation through the modulation of Annexin-A1 dependent endosomal trafficking and apoptosis.

The influenza virus infects millions of people each year and can result in severe complications. Understanding virus recognition and host responses to influenza infection will enable future development of more effective anti-viral therapies. Previous research has revealed diverse yet important roles for the annexin family of proteins in modulating the course of influenza A virus (IAV) infection. However, the role of Annexin-A1 (ANXA1) in IAV infection has not been addressed. Here, we show that ANXA1 deficient mice exhibit a survival advantage, and lower viral titers after infection. This was accompanied with enhanced inflammatory cell infiltration during IAV infection. ANXA1 expression is increased during influenza infection clinically, in vivo and in vitro. The presence of ANXA1 enhances viral replication, influences virus binding, and enhances endosomal trafficking of the virus to the nucleus. ANXA1 colocalizes with early and late endosomes near the nucleus, and enhances nuclear accumulation of viral nucleoprotein. In addition, ANXA1 enhances IAV-mediated apoptosis. Overall, our study demonstrates that ANXA1 plays an important role in influenza virus replication and propagation through various mechanisms and that we predict that the regulation of ANXA1 expression during IAV infection may be a viral strategy to enhance its infectivity.

Abstract 3906: Annexin A1 overexpression preferentially predicts poor prognosis of basal-like breast cancer patients by activating m TOR-S6 signaling

Abstract Introduction: Annexin A1 is an anti-inflammatory protein reported to play a role in cell proliferation, apoptosis and to be deregulated in breast cancer. The role and regulation of annexin A1 in the biology and prognosis of breast cancer remain unclear because most of the studies did not consider specific differences between the different subtypes of breast cancer. Thus, in this study, we hypothesize that annexin A1 plays subtype-specific role in basal like breast cancer progression and metastasis. Methods: By mining The Cancer Genome Atlas-Breast Cancer Dataset (TCGA-BRCA) and manipulating annexin A1 levels in breast cancer cell lines, we studied the role of annexin A1 in breast cancer and underlying signaling pathways. Results: Our in-silico analysis of TCGA-BRCA dataset demonstrated that annexin A1 mRNA expression is higher in basal subtype compared to luminal and HER2 subtypes. Within the basal subtype, patients show significantly poorer survival associated with higher expression of annexin A1. In both TCGA patient samples and cell lines, annexin A1 levels were significantly higher in basal-like breast cancer tumors than luminal and Her2/neu-positive breast cancer tumors. Stable annexin A1 knockdown in TNBC cell lines suppressed the mTOR-S6 pathway. Specifically, annexin A1 knockdown inhibited phosphorylation of mTOR and S6 (18-73% inhibition in pmTOR and 50-60% inhibition in pS6). But annexin A1 knockdown had no impact on the MAPK, c-Met, and EGFR pathways. In cell migration assays, annexin A1-depleted TNBC cells showed delayed migration as compared to wild-type cells which we found to be through suppression of MMP9. Conclusions: Our data suggest that annexin A1 is prognostic only in patients with basal like breast cancer. This appears to be due in part to the role of annexin A1 in activating mTOR-pS6 pathway. Citation Format: Kazunoshin Tachibana, Anjana Bhardwaj, Nivetha Ganesan, Kimal Rajapakshe, Constance T. Albarracin, Preethi H. Gunaratn, Cristian Coarfa, Isabelle Bedrosian. Annexin A1 overexpression preferentially predicts poor prognosis of basal-like breast cancer patients by activating m TOR-S6 signaling. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3906. doi:10.1158/1538-7445.AM2015-3906

A novel role of annexin A2 in human type I collagen gene expression.

ABSTRACTThe fibrillar collagen scaffold of the extracellular matrix provides a structural framework for cells in tissues and regulates intercellular communication; its disregulation has been associated with tumour development and progression. Previous work has shown that expression of type I collagen, the most abundant mammalian extracellular matrix protein, is decreased in chemically or virally transformed cells. This negative regulation could be mapped to a proximal COL1A2 promoter element spanning a CME (Collagen Modulating Element) site in SV40‐transformed human fibroblasts (SV‐WI38) that binds an unknown repressing protein. By magnetic bead pull‐down, we observed a multi‐protein complex bound to the CME with preference for single‐stranded over conventional double‐stranded DNA. MALDI‐TOF mass spectrometry of the CME‐binding protein complex revealed involvement of nuclear annexin A2 (AnxA2) which was increased in SV40‐transformed cells. Further EMSA analysis demonstrated that AnxA2 did not directly bind to the DNA but stabilised the complex and led to an increase in protein binding to the CME in SV‐WI38 but not untransformed WI38 cells. Knockdown of AnxA2 by siRNA increased type I collagen production in both WI38 and SV‐WI38 cells; however, these effects were not mediated at the transcriptional level. Rather, our data indicate a novel functional role of AnxA2 in the negative post‐transcriptional regulation of type I collagen synthesis in human fibroblasts. In SV40‐transformed cells, AnxA2 is accumulated at the proximal COL1A2 promoter region, suggesting close association with the transcriptional machinery that possibly facilitates binding to the emerging mRNA, eventually contributing to overall repression of type I collagen protein synthesis. J. Cell. Biochem. 116: 408–417, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.

Absence of Annexin A1 impairs host adaptive immunity against Mycobacterium tuberculosis in vivo

The role of Annexin A1 (ANXA1) in counter-regulating the activities of innate immune cells, such as the migration of neutrophils and monocytes, and the generation of pro-inflammatory mediators in various models of inflammatory and autoimmune diseases is well documented. However, while ANXA1 has been proposed as an important mediator of the adaptive immune response, its involvement in this respect has been less studied. Furthermore, while there have been numerous studies on the role of ANXA1 in inflammatory diseases, less has been reported on its influence in immunity against infection. A recent study reported a link between ANXA1 and tuberculosis, and proposed a model in which Mycobacterium tuberculosis exerts its virulence by manipulating the ANXA1-mediated host apoptotic response. This has prompted us to further investigate the role of ANXA1 in the pathogenesis of tuberculosis in vivo. Here, we show that ANXA1−/− mice are more susceptible to M. tuberculosis infection, as evidenced by a transient increase in the pulmonary bacterial burden, and exacerbated and disorganized granulomatous inflammation. These pathological manifestations correlated with an impaired ability of ANXA1−/− dendritic cells to activate naïve T cells, thereby supporting a role for ANXA1 in shaping the adaptive immunity against M. tuberculosis.

Inflammation and cancer: role of annexin A1 and FPR2/ALX in proliferation and metastasis in human laryngeal squamous cell carcinoma.

The anti-inflammatory protein annexin A1 (ANXA1) has been associated with cancer progression and metastasis, suggesting its role in regulating tumor cell proliferation. We investigated the mechanism of ANXA1 interaction with formylated peptide receptor 2 (FPR2/ALX) in control, peritumoral and tumor larynx tissue samples from 20 patients, to quantitate the neutrophils and mast cells, and to evaluate the protein expression and co-localization of ANXA1/FPR2 in these inflammatory cells and laryngeal squamous cells by immunocytochemistry. In addition, we performed in vitro experiments to further investigate the functional role of ANXA1/FPR2 in the proliferation and metastasis of Hep-2 cells, a cell line from larynx epidermoid carcinoma, after treatment with ANXA12–26 (annexin A1 N-terminal-derived peptide), Boc2 (antagonist of FPR) and/or dexamethasone. Under these treatments, the level of Hep-2 cell proliferation, pro-inflammatory cytokines, ANXA1/FPR2 co-localization, and the prostaglandin signalling were analyzed using ELISA, immunocytochemistry and real-time PCR. An influx of neutrophils and degranulated mast cells was detected in tumor samples. In these inflammatory cells of peritumoral and tumor samples, ANXA1/FPR2 expression was markedly exacerbated, however, in laryngeal carcinoma cells, this expression was down-regulated. ANXA12–26 treatment reduced the proliferation of the Hep-2 cells, an effect that was blocked by Boc2, and up-regulated ANXA1/FPR2 expression. ANXA12–26 treatment also reduced the levels of pro-inflammatory cytokines and affected the expression of metalloproteinases and EP receptors, which are involved in the prostaglandin signalling. Overall, this study identified potential roles for the molecular mechanism of the ANXA1/FPR2 interaction in laryngeal cancer, including its relationship with the prostaglandin pathway, providing promising starting points for future research. ANXA1 may contribute to the regulation of tumor growth and metastasis through paracrine mechanisms that are mediated by FPR2/ALX. These data may lead to new biological targets for therapeutic intervention in human laryngeal cancer.

Role of annexin a5 on mitochondria-dependent apoptosis induced by tetramethoxystilbene in human breast cancer cells.

We have previously shown that 2,4,3′,5′-tetramethoxystilbene (TMS), a trans-stilbene analogue, induces apoptosis in human cancer cells. However, the detailed mechanisms of mitochondria-dependent apoptosis induced by TMS are not fully understood. In the present study, the possible roles of annexin A5 in TMS-mediated apoptosis were investigated in MCF7 human breast cancer cells. Quantitative real-time PCR analysis and Western blot analysis showed that the expression of annexin A5 was strongly increased in TMS-treated cells. TMS caused a strong translocation of annexin A5 from cytosol into mitochondria. Confocal laser scanning microscopic analysis clearly showed that TMS induced translocation of annexin A5 into mitochondria. TMS increased the expression and oligomerization of voltage-dependent anion channel (VDAC) 1, which may promote mitochondria-dependent apoptosis through disruption of mitochondrial membrane potential. When cells were treated with TMS, the levels of Bax, and Bak as well as annexin A5 were strongly enhanced. Moreover, we found that the cytosolic release of apoptogenic factors such as cytochrome c, or apoptosis-inducing factor (AIF) in mitochondria was markedly increased. Annexin A5 depletion by siRNA led to decreased proapoptotic factors such as Bax, Bak, and annexin A5. Taken together, our results indicate that annexin A5 may play an important role in TMS-mediated mitochondrial apoptosis through the regulation of proapoptotic proteins and VDAC1 expression.

440 Phenotypic alteration in a highly metastatic variant of the MDA-MB-231 cell line: role of Annexin A1

440 Phenotypic alteration in a highly metastatic variant of the MDA-MB-231 cell line: role of Annexin A1

Following OGD/R, annexin 1 nuclear translocation and subsequent induction of apoptosis in neurons are assisted by myosin IIA in a TRPM7 kinase-dependent manner.

Transient receptor potential cation channel, subfamily M, member 7 (TRPM7) is a bifunctional channel protein that contains an α-kinase domain at its C-terminal. Previous studies have indicated that oxygen-glucose deprivation/reoxygenation (OGD/R) induces neuronal apoptosis via TRPM7. Annexin 1 and myosin IIA have been identified as TRPM7 kinase substrates; however, the role of annexin 1 in OGD/R-induced neuron apoptosis remains unclear. Here, we report that OGD/R induces nuclear translocation of annexin 1 in primary cultured neurons. Interestingly, ablation of the TRPM7 kinase or a point mutation in Ser(5) interferes with TRPM7 kinase-annexin 1 binding, decreasing annexin 1 nuclear translocation, and thereby reducing neuronal apoptosis. Furthermore, mutation of Arg(205), which intercepts annexin 1-formyl peptide receptor binding, also decreased annexin 1 nuclear translocation. Coimmunoprecipitation indicated that annexin 1 is moved as cargo through the cytoplasm by myosin IIA. However, inhibiting myosin IIA can decrease annexin 1 nuclear translocation. Moreover, blocking myosin IIA function by antagonist injection into the lateral ventricle was found to improve learning and memory in rats after middle cerebral artery occlusion and could also improve cell viability after OGD/R. Last, we determined that the annexin 1-myosin IIA complex is recognized and translocated by the importin α/β heterodimer. Therefore, TRPM7 kinase modulates OGD/R-induced neuronal apoptosis via annexin 1 carried by myosin IIA, while nuclear formyl peptide receptor (FPR)-annexin 1 binding and importin β are involved in nuclear translocation.