Annexin-A1 regulates microRNA-26b* and microRNA-562 to directly target NF-κB and angiogenesis in breast cancer cells

An overview of the regulatory role of annexin A1 in the tumor microenvironment and its prospective clinical application (Review)

Although annexin A1 (ANXA1), a 37 kDa phospholipid‑binding anti‑inflammatory protein expressed in various tissues and cell types, has been investigated extensively for its regulatory role in cancer biology, studies have mainly focused on its intracellular role. However, cancer cells and stromal cells expressing ANXA1 have the ability to transmit signals within the tumor microenvironment (TME) through autocrine, juxtacrine, or paracrine signaling. This bidirectional crosstalk between cancer cells and their environment is also crucial for cancer progression, contributing to uncontrolled tumor proliferation, invasion, metastasis and resistance to therapy. The present review explored the important role of ANXA1 in regulating the cell‑specific crosstalk between various compartments of the TME and analyzed the guiding significance of the crosstalk effects in promotion or suppressing cancer progression in the development of cancer treatments. The literature shows that ANXA1 is critical for the regulation of the TME, indicating that ANXA1 signaling between cancer cells and the TME is a potential therapeutic target for the development of novel therapeutic approaches for impeding cancer development.

The role of ANXA1 in the tumor microenvironment

Annexin A1 (ANXA1) is widely expressed in a variety of body tissues and cells and is also involved in tumor development through multiple pathways. The invasion, metastasis, and immune escape of tumor cells depend on the interaction between tumor cells and their surrounding environment. Research shows that ANXA1 can act on a variety of cells in the tumor microenvironment (TME), and subsequently affect the proliferation, invasion and metastasis of tumors. This article describes the role of ANXA1 in the various components of the tumor microenvironment and its mechanism of action, as well as the existing clinical treatment measures related to ANXA1. These findings provide insight for the further design of strategies targeting ANXA1 for the diagnosis and treatment of malignant tumors.

Annexin A1 affects tumor metastasis through epithelial-mesenchymal transition: a narrative review

Background and Objective

Annexin A1 (annexin I, ANXA1), the first discovered member of the annexin superfamily, plays important roles in tumor development, invasion, metastasis, apoptosis and drug resistance based on tumor type-specific patterns of expression. The acquisition of the epithelial-mesenchymal transition (EMT) characteristics is an essential mechanism of metastasis because they increase the mobility and invasiveness of cancer cells. Cancer invasion and metastasis remain major health problems worldwide. Elucidating the role and mechanism of ANXA1 in the occurrence of EMT will help advance the development of novel therapeutic strategies. Hence, this review aims to attract everyone's attention to the important role of ANXA1 in tumors and provide new ideas for clinical tumor treatment.

Methods

The PubMed database was mainly used to search for various English research papers and reviews related to the role of ANXA1 in tumors and EMT published from November 1994 to April 2022. The search terms used mainly include ANXA1, EMT, tumor, cancer, carcinoma, and mechanism.

Key Content and Findings

This article mainly provides a summary of the roles of ANXA1 and EMT in tumor metastasis as well as the various mechanisms via which ANXA1 facilitates the occurrence of EMT, thereby affecting tumor metastasis. In addition, the expression of ANXA1 in different metastatic tumor cell lines and its roles in tumorigenesis and development are also elaborated. This article has found many tumorous therapeutic targets related to ANXA1 and EMT, further confirming that ANXA1 has a huge potential for the diagnosis, treatment and prognosis of certain cancers.

Conclusions

Both the abnormal expression of ANXA1 and the occurrence of EMT are closely related to the invasion and metastasis of tumors, and more interestingly, ANXA1 can impact EMT directly or indirectly by mediating signaling pathways and adhesion among cells. We need more studies to elucidate the effects of ANXA1 on tumor invasion, migration and metastasis through EMT in vitro and in vivo clearly, and ultimately in patients to identify more therapeutic targets.

Pathobiological functions and clinical implications of annexin dysregulation in human cancers

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

A Cell-Based Systematic Review on the Role of Annexin A1 in Triple-Negative Breast Cancers

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that is often associated with a poorer prognosis and does not respond to hormonal therapy. Increasing evidence highlights the exploitability of Annexin A1 (AnxA1), a calcium dependent protein, as a precision medicine for TNBC. To systematically summarize the role of AnxA1 and its associated mechanisms in TNBC, we performed data mining using three main databases: PubMed, Scopus, and Ovid/Medline. The papers retrieved were based on two different sets of key words such as “Annexin A1” or “Lipocortin 1” and “Breast cancer” or “TNBC”. A total of 388 articles were identified, with 210 chosen for comprehensive screening and 13 papers that met inclusion criteria were included. Current evidence from cell culture studies showed that AnxA1 expression is correlated with NF-κB, which promotes migration by activating ERK phosphorylation. AnxaA1 also activates TGF-β signaling which upregulates MMP-9 and miR196a expression to enhance epithelial-mesenchymal transition and migratory capacity of TNBC cells. AnxA1 can steer the macrophage polarization toward the M2 phenotype to create a pro-tumor immune environment. Existing research suggests a potential role of AnxA1 in the metastasis and immune landscape of TNBC tumors. Preclinical and clinical experiments are warranted to investigate the feasibility and effectiveness of targeting AnxA1 in TNBC.

Emerging role of exosomes in cancer progression and tumor microenvironment remodeling

Cancer is one of the leading causes of death worldwide, and the factors responsible for its progression need to be elucidated. Exosomes are structures with an average size of 100 nm that can transport proteins, lipids, and nucleic acids. This review focuses on the role of exosomes in cancer progression and therapy. We discuss how exosomes are able to modulate components of the tumor microenvironment and influence proliferation and migration rates of cancer cells. We also highlight that, depending on their cargo, exosomes can suppress or promote tumor cell progression and can enhance or reduce cancer cell response to radio- and chemo-therapies. In addition, we describe how exosomes can trigger chronic inflammation and lead to immune evasion and tumor progression by focusing on their ability to transfer non-coding RNAs between cells and modulate other molecular signaling pathways such as PTEN and PI3K/Akt in cancer. Subsequently, we discuss the use of exosomes as carriers of anti-tumor agents and genetic tools to control cancer progression. We then discuss the role of tumor-derived exosomes in carcinogenesis. Finally, we devote a section to the study of exosomes as diagnostic and prognostic tools in clinical courses that is important for the treatment of cancer patients. This review provides a comprehensive understanding of the role of exosomes in cancer therapy, focusing on their therapeutic value in cancer progression and remodeling of the tumor microenvironment.

Signaling pathways modulated by miRNAs in breast cancer angiogenesis and new therapeutics

MicroRNAs (miRNAs) act as oncogenes or tumor suppressors by suppressing the expression of target genes, some of which are engaged in angiogenic signaling pathways directly or indirectly. Tumor development and metastasis are dependent on angiogenesis, and it is the main reason for the poor prognosis of cancer patients. New blood vessels are formed from pre-existing vessels when angiogenesis occurs. Thus, it is essential to develop primary tumors and the spread of cancer to surrounding tissues. MicroRNAs (miRNAs) are small noncoding RNAs involved in various biological processes. They can bind to the 3'-UTR of their target genes and prevent them from expressing. MiRNAs control the activity of endothelial cells (ECs) through altering many biological pathways, which plays a key role in cancer progression and angiogenesis. Recent findings revealed that tumor-derived extracellular vesicles participated directly in the control of tumor angiogenesis by delivering miRNAs to ECs. miRNAs recently show great promise in cancer therapies to inhibit angiogenesis. In this study, we showed the miRNA-regulated signaling pathways in tumor angiogenesis with highlighting the anti-angiogenic therapy response and miRNA delivery methods that have been used to inhibit angiogenesis in both in vivo and in vitro studies.

MicroRNAs: Important Players in Breast Cancer Angiogenesis and Therapeutic Targets

The high incidence of breast cancer (BC) is linked to metastasis, facilitated by tumor angiogenesis. MicroRNAs (miRNAs or miRs) are small non-coding RNA molecules that have an essential role in gene expression and are significantly linked to the tumor development and angiogenesis process in different types of cancer, including BC. There's increasing evidence showed that various miRNAs play a significant role in disease processes; specifically, they are observed and over-expressed in a wide range of diseases linked to the angiogenesis process. However, more studies are required to reach the best findings and identify the link among miRNA expression, angiogenic pathways, and immune response-related genes to find new therapeutic targets. Here, we summarized the recent updates on miRNA signatures and their cellular targets in the development of breast tumor angiogenetic and discussed the strategies associated with miRNA-based therapeutic targets as anti-angiogenic response.

Annexin A1 as a Regulator of Immune Response in Cancer

Annexin A1 is a 37 kDa phospholipid-binding protein that is expressed in many tissues and cell types, including leukocytes, lymphocytes and epithelial cells. Although Annexin A1 has been extensively studied for its anti-inflammatory activity, it has been shown that, in the cancer context, its activity switches from anti-inflammatory to pro-inflammatory. Remarkably, Annexin A1 shows pro-invasive and pro-tumoral properties in several cancers either by eliciting autocrine signaling in cancer cells or by inducing a favorable tumor microenvironment. Indeed, the signaling of the N-terminal peptide of AnxA1 has been described to promote the switching of macrophages to the pro-tumoral M2 phenotype. Moreover, AnxA1 has been described to prevent the induction of antigen-specific cytotoxic T cell response and to play an essential role in the induction of regulatory T lymphocytes. In this way, Annexin A1 inhibits the anti-tumor immunity and supports the formation of an immunosuppressed tumor microenvironment that promotes tumor growth and metastasis. For these reasons, in this review we aim to describe the role of Annexin A1 in the establishment of the tumor microenvironment, focusing on the immunosuppressive and immunomodulatory activities of Annexin A1 and on its interaction with the epidermal growth factor receptor.

Angioregulatory microRNAs in breast cancer: Molecular mechanistic basis and implications for therapeutic strategies

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Cancer-associated angiogenesis is a fundamental process in tumor growth and metastasis.

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Angioregulatory miRNA–target gene interaction is not only involved in sprouting vessels of breast tumors but also, trans-differentiation of breast cancer cells to endothelial cells in a process termed vasculogenic mimicry.

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Successful targeting of tumor angiogenesis is still a missing link in the treatment of Breast cancer (BC) due to the low effectiveness of anti-angiogenic therapies in this cancer.

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Response to anti-angiogenic therapeutics are controlled by a miRNAs, so the identification of interaction networks of miRNAs–targets can be applicable in determining anti-angiogeneic therapy and new biomarkers in BC.

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Angioregulatory miRNAs in breast cancer cells and their microenvironment have therapeutic potential in cancer treatment.

Background

Cancer-associated angiogenesis is a fundamental process in tumor growth and metastasis. A variety of signaling regulators and pathways contribute to establish neovascularization, among them as small endogenous non-coding RNAs, microRNAs (miRNAs) play prominent dual regulatory function in breast cancer (BC) angiogenesis.

Aim of Review

This review aims at describing the current state-of-the-art in BC angiogenesis-mediated by angioregulatory miRNAs, and an overview of miRNAs dysregulation association with the anti-angiogenic response in addition to potential clinical application of miRNAs-based therapeutics.

Key Scientific Concepts of Review

Angioregulatory miRNA–target gene interaction is not only involved in sprouting vessels of breast tumors but also, trans-differentiation of BC cells to endothelial cells (ECs) in a process termed vasculogenic mimicry. Using canonical and non-canonical angiogenesis pathways, the tumor cell employs the oncogenic characteristics such as miRNAs dysregulation to increase survival, proliferation, oxygen and nutrient supply, and treatment resistance. Angioregulatory miRNAs in BC cells and their microenvironment have therapeutic potential in cancer treatment. Although, miRNAs dysregulation can serve as tumor biomarker nevertheless, due to the association of miRNAs dysregulation with anti-angiogenic resistant phenotype, clinical benefits of anti-angiogenic therapy might be challenging in BC. Hence, unveiling the molecular mechanism underlying angioregulatory miRNAs sparked a booming interest in finding new treatment strategies such as miRNA-based therapies in BC.

Ad- and AAV8-mediated ABCA1 gene therapy in a murine model with retinal ischemia/reperfusion injuries

The anti-inflammatory molecule annexin A1 (ANXA1) determines the ultimate fate of retinal ganglion cell (RGC) in glaucoma. Cytoplasmic and extracellular ANXA1 facilitate resolution of inflammation. However, the nuclear translocation of ANXA1 induces RGC apoptosis in a murine glaucoma model, and the maintenance of ANXA1 secreted in the extracellular environments remains unclear. In this study, we found that intravitreal injection of the recombinant adenovirus vector (Ad)-ATP-binding cassette transporter A1 (ABCA1; carrying full-length ABCA1) improved RGC survival in the ischemia reperfusion (IR) mice model. Upregulation of ABCA1 maintained ANXA1 cytoplasmic location and reduced ANXA1 nuclear translocation, which is due to the decreased binding of ANXA1 with importin β. Moreover, we found that amino acids 903 to 1,344 of ABCA1 interacted with ANXA1 and decreased its nuclear localization. Importantly, intravitreal injection of adenovirus-associated viral (AAV) vector AAV8-ABCA1 (carrying 903 to 1,344 fragments of ABCA1) maintained ANXA1 cytoplasmic location and improved RGC survival in the IR mice model. Thus, overexpression of ABCA1 protects against RGC apoptosis by partially blocking ANXA1 nuclear translocation. This study puts forth a potential gene treatment strategy to prevent RGC apoptosis in glaucoma.

The crosstalk of ABCA1 and ANXA1: a potential mechanism for protection against atherosclerosis

Atherosclerosis, characterized by the formation of fat-laden plaques, is a chronic inflammatory disease. ABCA1 promotes cholesterol efflux, reduces cellular cholesterol accumulation, and regulates anti-inflammatory activities in an apoA-I- or ANXA1-dependent manner. The latter activity occurs by mediating the efflux of ANXA1, which plays a critical role in anti-inflammatory effects, cholesterol transport, exosome and microparticle secretion, and apoptotic cell clearance. ApoA-I increases ANXA1 expression via the ERK, p38MAPK, AKT, and PKC pathways. ApoA-I regulates the signaling pathways by binding to ABCA1, suggesting that apoA-I increases ANXA1 expression by binding to ABCA1. Furthermore, ANXA1 may increase ABCA1 expression. ANXA1 increases PPARγ expression by modulating STAT6 phosphorylation. PPARγ also increases ANXA1 expression by binding to the promoter of ANXA1. Therefore, ABCA1, PPARγ, and ANXA1 may form a feedback loop and regulate each other. Interestingly, the ANXA1 needs to be externalized to the cell membrane or secreted into the extracellular fluids to exert its anti-inflammatory properties. ABCA1 transports ANXA1 from the cytoplasm to the cell membrane by regulating lipidization and serine phosphorylation, thereby mediating ANXA1 efflux, likely by promoting microparticle and exosome release. The direct role of ABCA1 expression and ANXA1 release in atherosclerosis has been unclear. In this review, we focus on the role of ANXA1 in atheroprogression and its novel interaction with ABCA1, which may be useful for providing basic knowledge for the development of novel therapeutic targets for atherosclerosis and cardiovascular disease.

Evaluation of miR-196a2 expression and Annexin A1 level in children with bronchial asthmaEvaluation of miR-196a2 expression and Annexin A1 level in children

BACKGROUND

Annexin A1 (ANXA1) is an important anti-inflammatory mediator that may play a significant role in bronchial asthma. MiR-196a2 can target ANXA1 and therefore may play a role in the pathogenesis of asthma.

AIM OF STUDY

This is the first study which aimed to evaluate the expression of miR-196a2 in the serum of asthmatic children and correlate its expression with ANXA1 serum level and asthma severity.

SUBJECTS AND METHODS

The study included 100 asthma patients who were subdivided into three groups (mild, moderate and severe) and 50 healthy control subjects. Assessment of miR-196a2 expression and ANXA1 serum level were done using quantitative reverse transcriptase PCR (RT qPCR) and Elisa techniques, respectively.

RESULTS

Compared to the control group, asthmatic children showed an increased ANXA1 serum level and decreased expression of miR-196a2 (p=0.001). However, ANXA1 serum level was lower and miR-196a2 expression was higher in severe asthmatic patients compared to moderate asthmatic ones (p=0.01, 0.03). Pearson's correlation coefficient revealed no significant correlations between ANXA1 serum level and miR-196a2 expression in the patient group (p=0.9).

CONCLUSIONS

Altered miR-196a2 expression and serum ANXA1 concentration may play a role in the pathogenesis of asthma. In addition, ANXA1 and miR-196a2 may represent potential diagnostic biomarkers for asthma and future targets for therapy.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Annexin 1-nuclear factor-κB-microRNA-26a regulatory pathway in the metastasis of non-small cell lung cancer

Background

Annexin 1 (ANXA1) expression is associated with the malignant tumor phenotype, making it an attractive therapeutic target. However, little is known about the regulation of ANXA1 in non‐small cell lung cancer (NSCLC).

Methods

We investigated the biological roles of ANXA1 in tumor growth, migration, and invasion, and explored the possibility of ANXA1 as a potential therapeutic target for the treatment of NSCLC.

Results

Our findings revealed that ANXA1 enhanced nuclear factor (NF)‐κB activation in NSCLC cells by interaction with inhibitor of NF‐κB kinase complex subunit, IKKγ. We also found that NF‐κB could negatively regulate microRNA (miR)‐26a, and miR‐26a was regulated through the ANXA1–NF‐κB regulatory pathway. NF‐κB activation negatively regulated by miR‐26a was confirmed in NSCLC.

Conclusion

Together, these results provide evidence of the mechanisms of the ANXA1–NF‐κB–miR‐26a regulatory pathway in the invasion and migration in NSCLC.

Annexin A12-26 Treatment Improves Skin Heterologous Transplantation by Modulating Inflammation and Angiogenesis Processes

Skin graft successful depends on reduction of local inflammation evoked by the surgical lesion and efficient neovascularization to nutrition the graft. It has been shown that N-terminal portion of the Annexin A1 protein (AnxA1) with its anti-inflammatory properties induces epithelial mucosa repair and presents potential therapeutic approaches. The role of AnxA1 on wound healing has not been explored and we investigated in this study the effect of the peptide Ac2-26 (N-terminal AnxA1 peptide Ac2-26; AnxA1_2-26) on heterologous skin scaffolds transplantation in BALB/c mice, focusing on inflammation and angiogenesis. Treatment with AnxA1_2-26, once a day, from day 3-60 after scaffold implantation improved the take of the implant, induced vessels formation, enhanced gene and protein levels of the vascular growth factor-A (VEGF-A) and fibroblast influx into allograft tissue. It also decreased pro- while increasing anti-inflammatory cytokines. The pro-angiogenic activity of AnxA1_2-26 was corroborated by topical application of AnxA1_2-26 on the subcutaneous tissue of mice. Moreover, treatment of human umbilical endothelial cells (HUVECs) with AnxA1_2-26 improved proliferation, shortened cycle, increased migration and actin polymerization similarly to those evoked by VEGF-A. The peptide treatment instead only potentiated the tube formation induced by VEGF-A. Collectively, our data showed that AnxA1_2-26 treatment favors the tissue regeneration after skin grafting by avoiding exacerbated inflammation and improving the angiogenesis process.

miR-338 modulates proliferation and autophagy by PI3K/AKT/mTOR signaling pathway in cervical cancer

Cervical cancer (CC) is a malignant solid tumor, which is one of the main causes of morbidity and mortality in women. Given that autophagy is an important factor promoting tumor progression, we aim to investigate the functional role of miR-338 in autophagy and proliferation of cervical cancer. In our study, expression of miR-338 was validated by quantitative RT-PCR in 30 paired cervical cancer tissues and normal tissues. We performed MTT, colony formation and cell cycle assay to explore the effect of miR-338 on cell proliferation. The level of autophagy was evaluated by observing the expression of LC3 formation under fluorescence microscope and detected the LC3 expression by western blot. We used luciferase reporter assays to identify the target gene about miR-338. We not only found that the level of miR-338 is decreased in cervical cancer tissues and cells, but also negatively correlated with the protein level of ATF2. In turn, restoring the expression of miR-338 inhibited proliferation in Hela and SiHa cells. Further mechanistic study identified that ATF2 as a direct target of miR-338. Forced lowexpression of miR-338 directly led to increased the level of autophagy in cervical cancer cells, which was similar to the mTOR signaling inhibitor rapamycin. The western blot analysis show that inhibited miR-338 expression could decrease the p-mTOR and p-p70S6 expression. Thus, we infer that miR-338 decreases autophagy level in cervical cancer cells by activating mTOR signaling pathway. In summary, our study demonstrate that miR-338 could inhibites proliferation and autophagy by targeting ATF2 via mTOR signaling pathway on cervical cancer cells. These results suggest a potential application of miR-338 in cervical cancer as a novel mechanism of tumor therapeutic.

Ac2-26 Induces IKKβ Degradation Through Chaperone-Mediated Autophagy Via HSPB1 in NCM-Treated Microglia

Annexin A1 (ANXA1) is an endogenous protein with potent anti-inflammatory properties in the brain. Although ANXA1 has been predominantly studied for its binding to formyl peptide receptors (FPRs) on plasma membranes, little is known regarding whether this protein has an anti-inflammatory effect in the cytosol. Here, we investigated the mechanism by which the ANXA1 peptide Ac2-26 decreases high TNF-α production and IKKβ activity, which was caused by oxygen glucose deprivation/reperfusion (OGD/R)-induced neuronal conditioned medium (NCM) in microglia. We found that exogenous Ac2-26 crosses into the cytoplasm of microglia and inhibits both gene expression and protein secretion of TNF-α. Ac2-26 also causes a decrease in IKKβ protein but not IKKβ mRNA, and this effect is inverted by lysosome inhibitor NH₄CL. Furthermore, we demonstrate that Ac2-26 induces IKKβ accumulation in lysosomes and that lysosomal-associated membrane protein 2A (LAMP-2A), not LC-3, is enhanced in microglia exposed to Ac2-26. We hypothesize that Ac2-26 mediates IKKβ degradation in lysosomes through chaperone-mediated autophagy (CMA). Interestingly, ANXA1 in the cytoplasm does not interact with IKKβ but with HSPB1, and Ac2-26 promotes HSPB1 binding to IKKβ. Furthermore, both ANXA1 and HSPB1 can interact with Hsc70 and LAMP-2A, but IKKβ only associates with LAMP-2A. Downregulation of HSPB1 or LAMP-2A reverses the degradation of IKKβ induced by Ac2-26. Taken together, these findings define an essential role of exogenous Ac2-26 in microglia and demonstrate that Ac2-26 is associated with HSPB1 and promotes HSPB1 binding to IKKβ, which is degraded by CMA, thereby reducing TNF-α expression.

MicroRNA-26b inhibits the immune response to Mycobacterium tuberculosis (M.tb) infection in THP-1 cells via targeting TGFβ-activated kinase-1 (TAK1), a promoter of the NF-κB pathway

Tuberculosis (TB), caused by Mycobacterium tuberculosis, has led to many clinical disorders and remains a major global health problem, leading to great morbidity and mortality worldwide. Previous studies reported that Mycobacterium tuberculosis (M.tb) has evolved to utilize various mechanisms to evade or attenuate the immune response, such as dysregulation of miRNAs. However, reports concerning the role of miRNAs in M.tb infection are limited. Here, we report that a host microRNA, miR-26b, was significantly down-regulated by M.tb infection in THP-1 cells. Subsequently, our results of in vitro experiments demonstrate that miR-26b is a negative regulator of the NF-κB pathway by directly targeting TAK1, resulting in the inhibition of immune response, and promotion of M.tb replication and gene expression. Taken together, our findings provide detailed molecular mechanisms for how miR-26 inhibits inflammatory cytokine secretion during M.tb infection in THP-1 cells, and these results suggest anti-M.tb as a promising therapy.

Functional Association between Regulatory RNAs and the Annexins

Cells respond to pathophysiological states by activation of stress-induced signalling. Regulatory non-coding microRNAs (miRNAs) often form stable feed-forward loops which ensure prolongation of the signal, contributing to sustained activation. Members of the annexin protein family act as sensors for Ca²⁺, pH, and lipid second messengers, and regulate various signalling pathways. Recently, annexins were reported to participate in feedback loops, suppressing miRNA synthesis and attenuating stress-induced dysregulation of gene expression. They can directly or indirectly associate with RNAs, and are transferred between the cells in exosomes and shed microvesicles. The ability of annexins to recruit other proteins and miRNAs into exosomes implicates them in control of cell–cell interactions, affecting the adaptive responses and remodelling processes during disease. The studies summarized in this Review point to an emerging role of annexins in influencing the synthesis, localisation, and transfer of regulatory RNAs.

Annexin-A1 enhances breast cancer growth and migration by promoting alternative macrophage polarization in the tumour microenvironment

Macrophages are potent immune cells with well-established roles in the response to stress, injury, infection and inflammation. The classically activated macrophages (M1) are induced by lipopolysaccharide (LPS) and express a wide range of pro-inflammatory genes. M2 macrophages are induced by T helper type 2 cytokines such as interleukin-4 (IL4) and express high levels of anti-inflammatory and tissue repair genes. The strong association between macrophages and tumour cells as well as the high incidences of leukocyte infiltration in solid tumours have contributed to the discovery that tumour-associated macrophages (TAMs) are key to tumour progression. Here, we investigated the role of Annexin A1 (ANXA1), a well characterized immunomodulatory protein on macrophage polarization and the interaction between macrophages and breast cancer cells. Our results demonstrate that ANXA1 regulates macrophage polarization and activation. ANXA1 can act dually as an endogenous signalling molecule or as a secreted mediator which acts via its receptor, FPR2, to promote macrophage polarization. Furthermore, ANXA1 deficient mice exhibit reduced tumour growth and enhanced survival in vivo, possibly due to increased M1 macrophages within the tumor microenvironment. These results provide new insights into the molecular mechanisms of macrophage polarization with therapeutic potential to suppress breast cancer growth and metastasis.

ANXA1 inhibits miRNA-196a in a negative feedback loop through NF-kB and c-Myc to reduce breast cancer proliferation

MiRNAs are endogenous ~22 nt RNAs which play critical regulatory roles in a wide range of biological and pathological processes, which can act as oncogenes or tumor suppressor genes depending on their target genes. We have recently shown that ANXA1 inhibits the expression of miRNAs including miR196a. Here, we show that miR196a was highly expressed in ER+ MCF-7 breast cancer cells when compared to normal mammary gland cells, with expression levels negatively correlating to ANXA1. ANXA1 inhibits the biogenesis of oncogenic miR-196a by suppressing primary-miR196a indirectly through the stimulation of c-myc and NFkB expression and activity in breast cancer cells. In a negative feedback loop, miR-196a directly inhibits ANXA1 and enhances breast cancer cell proliferation in vitro. Finally, miR196a promotes breast tumor growth in vivo. This study reports a novel regulatory circuit between ANXA1, NF-kB, c-myc and miR-196a which regulates breast cancer cell proliferation and tumor growth.

Bioinformatic analysis of microRNA-mRNA expression profiles of bladder tissue induced by bladder outlet obstruction in a rat model

Various microRNAs (miRNAs) have previously been demonstrated to exhibit an association with the process of bladder remodeling, induced by bladder outlet obstruction (BOO). However, little is known about miRNA and gene expression profiles and the molecular mechanism underlying bladder pathophysiological alterations. The present study used bioinformatic analysis technology to examine the altered miRNA and mRNA expression profiles of bladder tissue in a rat model of BOO and validate the involved signaling pathways. The gene expression profile data was downloaded from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were screened. Potential target genes of DEMs were predicted. The target genes and DEGs were used for further gene ontology (GO) analysis followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis using the Database for Annotation, Visualization and Integrated Discovery. The present study additionally constructed a DEM‑DEG interaction network. A total of 9 DEMs (3 upregulated and 6 downregulated) were identified; 664 DEGs were screened. KEGG analysis revealed that the DEGs were involved in the regulation of the actin cytoske-leton, extracellular matrix (ECM) remodeling, cell adhesion and the cell cycle. Additionally, KEGG classification indicated that these genes were important in angiogenesis, and in the p53 and transforming growth factor‑β signaling pathways. Notably, rno‑miRNA (miR)‑26b and rno‑miR‑101b were the two larger nodes of the 7 obstruction‑associated DEMs and interacted with 32 and 27 DEGs, respectively. On removal of obstruction, few DEMs were present; however, 370 genes exhibited the opposite expression trend. The majority of pathways enriched for the DEGs were identified and were associated with ECM‑receptor interaction and focal adhesion. In the DEM‑DEG regulatory network, miR‑495, miR‑494 and their target genes were significantly differentially expressed. The present study demonstrated that miRNAs and genes may be potential biomarkers of bladder remodeling induced by BOO, and additionally provided novel insights into the molecular mechanisms underlying this disorder.

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

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

Annexin A1 nuclear translocation induces retinal ganglion cell apoptosis after ischemia-reperfusion injury through the p65/IL-1β pathway

The degeneration of retinal ganglion cells (RGCs) has been identified as a major problem in glaucoma. Previous studies have indicated an association between annexin A1 (ANXA1) and neuronal cell apoptosis, and RGCs apoptosis in acute ischemia-reperfusion was attributed to an increased production of IL-1β. We found that the expression and nuclear translocation of ANXA1 were upregulated in models of acute ischemia-reperfusion in RGCs in vivo. ANXA1 was found to have a promoting effect on the expression of IL-1β in primary cultured RGCs, which could be inhibited by treatment with ANXA1 shRNA or the p65 inhibitor BAY 11-7082. ANXA1 interacted with p65, and recruited it into the nucleus. Chromatin immunoprecipitation assay revealed that ANXA1 accumulated at the IL-1β gene promoter. The reduction of p65 nuclear translocation using a membrane-permeable ANXA1 peptide containing a Ser5Ala mutation led to a decrease in the expression of IL-1β, and acute ischemia-reperfusion induced RGCs apoptosis in vivo. These results indicate that in RGCs, ANXA1 increases IL-1β expression by recruiting p65 to the nucleus, which induces cell apoptosis. The obtained results may help the development of a novel treatment strategy against RGCs apoptosis in acute ischemia-reperfusion injury.

Annexin A1 influences in breast cancer: Controversies on contributions to tumour, host and immunoediting processes

Annexin A1 is a multifunctional protein characterised by its actions in modulating the innate and adaptive immune response. Accumulating evidence of altered annexin A1 expression in many human tumours raises interest in its functional role in cancer biology. In breast cancer, altered annexin A1 expression levels suggest a potential influence on tumorigenic and metastatic processes. However, reports of conflicting results reveal a relationship that is much more complex than first conceptualised. In this review, we explore the diverse actions of annexin A1 on breast tumour cells and various host cell types, including stromal immune and structural cells, particularly in the context of cancer immunoediting.

Annexin A1 is involved in resistance to 5-FU in colon cancer cells

Resistance to 5-fluorouracil (5‑FU), a key drug in the treatment of colorectal cancer, is one of the major reasons for poor patient prognosis during cancer treatment. Annexin A1 (ANXA1) is a calcium‑dependent phospholipid‑linked protein that is associated with drug resistance, anti‑inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. Although there have been several studies investigating ANXA1 expression in drug resistant cells, the role of ANXA1 is yet to be fully understood. We therefore, in this study, generated SW480 cells resistant to 5‑FU (SW480/5‑FU) to evaluate ANXA1 expression. When compared to the control cells, ANXA1 expression was significantly induced in the SW480/5‑FU cells. We then revealed the role of ANXA1 expression in 5‑FU resistance by using overexpression and knockdown methods in colon cancer cells. Overexpression of ANXA1 induced a significant increase of cell viability to 5‑FU, whereas ANXA1 knockdown induced a significant decrease of cell viability to 5‑FU. Further experiments revealed that ANXA1 expression was induced by hypoxia in colon cancer cells. These results suggest that ANXA1 expression may play a critical role in 5‑FU resistance and may be induced by hypoxia during cancer progression. Our results provide a possible strategy to overcome 5‑FU resistance by modulating ANXA1 expression.

Annexin A1 localization and its relevance to cancer

Annexin A1 (ANXA1) is a Ca(2+)-regulated phospholipid-binding protein involved in various cell processes. ANXA1 was initially widely studied in inflammation resolution, but its overexpression was later reported in a large number of cancers. Further in-depth investigations have revealed that this protein could have many roles in cancer progression and act at different levels (from cancer initiation to metastasis). This is partly due to the location of ANXA1 in different cell compartments. ANXA1 can be nuclear, cytoplasmic and/or membrane associated. This last location allows ANXA1 to be proteolytically cleaved and/or to become accessible to its cognate partners, the formyl-peptide receptors. Indeed, in some cancers, ANXA1 is found at the cell surface, where it stimulates formyl-peptide receptors to trigger oncogenic pathways. In the present review, we look at the different locations of ANXA1 and their association with the deregulated pathways often observed in cancers. We have specifically detailed the non-classic pathways of ANXA1 externalization, the significance of its cleavage and the role of the ANXA1-formyl-peptide receptor complex in cancer progression.

Knockdown of ANXA1 suppresses the biological behavior of human NSCLC cells in vitro

Annexin A1 (ANXA1) is a member of the annexin superfamily. Previous studies have reported that ANXA1 is highly expressed in various types of malignant tumor; however, its role in the progression of non‑small cell lung cancer (NSCLC) remains to be fully clarified. The present study aimed to investigate the oncogenic role of ANXA1 in NSCLC cells in vitro. RNA interference was used to downregulate ANXA1 expression in A549 and H1299 cells using a small interfering RNA lentiviral vector. Subsequently, cell proliferation and migration were detected using Cell Counting kit‑8, clone formation, wound healing and Transwell chamber assays. Successful transfection was confirmed using fluorescence microscopy, which demonstrated that ANXA1 had been efficiently inhibited. ANXA1 knockdown suppressed the proliferation, migration and invasion of NSCLC cells. In conclusion, the present study provided evidence suggesting that ANXA1 may contribute to the growth and invasion of NSCLC cell lines, and ANXA1 may be exploited as an in vitro therapeutic target for the treatment of NSCLC.

Modeling the combined effect of RNA-binding proteins and microRNAs in post-transcriptional regulation

Recent studies show that RNA-binding proteins (RBPs) and microRNAs (miRNAs) function in coordination with each other to control post-transcriptional regulation (PTR). Despite this, the majority of research to date has focused on the regulatory effect of individual RBPs or miRNAs. Here, we mapped both RBP and miRNA binding sites on human 3'UTRs and utilized this collection to better understand PTR. We show that the transcripts that lack competition for HuR binding are destabilized more after HuR depletion. We also confirm this finding for PUM1(2) by measuring genome-wide expression changes following the knockdown of PUM1(2) in HEK293 cells. Next, to find potential cooperative interactions, we identified the pairs of factors whose sites co-localize more often than expected by random chance. Upon examining these results for PUM1(2), we found that transcripts where the sites of PUM1(2) and its interacting miRNA form a stem-loop are more stabilized upon PUM1(2) depletion. Finally, using dinucleotide frequency and counts of regulatory sites as features in a regression model, we achieved an AU-ROC of 0.86 in predicting mRNA half-life in BEAS-2B cells. Altogether, our results suggest that future studies of PTR must consider the combined effects of RBPs and miRNAs, as well as their interactions.

Proteome Differences between Hepatitis B Virus Genotype-B- and Genotype-C-Induced Hepatocellular Carcinoma Revealed by iTRAQ-Based Quantitative Proteomics

Hepatitis B virus (HBV) is the main cause of hepatocellular carcinoma (HCC) in southeast Asia where HBV genotype B and genotype C are the most prevalent. Viral genotypes have been reported to significantly affect the clinical outcomes of HCC. However, the underlying molecular differences among different genotypes of HBV virus infected HCC have not been revealed. Here, we applied isobaric tags for relative and absolute quantitation (iTRAQ) technology integrated with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to identify the proteome differences between the HBV genotypes B- and C-induced HCC. In brief, a total of 83 proteins in the surrounding noncancerous tissues and 136 proteins in the cancerous tissues between HBV genotype-B- and genotype-C-induced HCC were identified, respectively. This information revealed that there might be different molecular mechanisms of the tumorigenesis and development of HBV genotypes B- and C-induced HCC. Furthermore, our results indicate that the two proteins ARFIP2 and ANXA1 might be potential biomarkers for distinguishing the HBV genotypes B- and C-induced HCC. Thus, the quantitative proteomic analysis revealed molecular differences between the HBV genotypes B- and C-induced HCC, and might provide fundamental information for further deep study.

Impact of single-nucleotide polymorphisms on radiation pneumonitis in cancer patients

Radiation pneumonitis (RP) is one of the most important dose-limiting toxicities in the radiotherapy of thoracic tumors, which reduces the rate of local tumor control and overall survival and severely affects the patients' quality of life. Single-nucleotide polymorphisms (SNPs) have recently attracted increasing attention as biomarkers for predicting the development of RP. SNPs in inflammation-related, DNA repair-related, stress response-related and angiogenesis-related genes were proved to be associated with RP, with different underlying mechanisms. Radiogenomics focuses on the differences in radiosensitivity caused by gene sequence variation, which may prove helpful in investigating the abovementioned associations. In this review, we aimed to investigate the associations between RP and SNPs reported in recent studies and highlight the main content and prospects of radiogenomics.