ANXA4 promotes trophoblast invasion via the PI3K/Akt/eNOS pathway in preeclampsia.

The inadequate trophoblast invasion is associated with the development of preeclampsia (PE). Considering that annexin A4 (ANXA4) enhances tumor invasion, we aimed to explore the functional role of ANXA4 in trophoblast cells and to examine the underlying mechanism. ANXA4 expression in PE placentas was analyzed using immunohistochemistry and Western blotting. Cell proliferation, invasion, and apoptosis were determined using a MTT assay, Transwell assay, and flow cytometry, respectively. The expression levels of matrix metalloproteinase (MMP)-2, MMP-9, phosphoinositide 3-kinase (PI3K), Akt, phosphorylated (p)-Akt, and phosphorylated endothelial nitric oxide synthase (p-eNOS) were detected by Western blotting. Placentas were prepared for pathological examination using hematoxylin and eosin staining and apoptosis determination using the TUNEL method. Expression of ANXA4, PI3K, p-Akt and p-eNOS was downregulated in human PE placentas and PE placenta-derived extravillous cytotrophoblasts (EVCTs). Furthermore, ANXA4 overexpression promoted cell proliferation and invasion, inhibited cell apoptosis, and upregulated protein expression of PI3K, p-Akt, and p-eNOS in human trophoblast cells HTR-8/SVneo and JEG-3. By contrast, ANXA4 knockdown exerted the opposite effects. Furthermore, inhibition of the PI3K/Akt pathway by LY294002 abrogated the ANXA4 overexpression-mediated effects on trophoblast behavior. Furthermore, eNOS knockdown abrogated the ANXA4 overexpression-induced promotion of cell invasion and MMP2/9 expression. Additionally, in N-nitro-l-arginine methyl ester (l-NAME)-induced PE rats, ANXA4 overexpression alleviated PE progression, accompanied by an increase in expression of PI3K, p-Akt, and p-eNOS in rat placentas. Our findings demonstrate that ANXA4 expression is downregulated in PE. ANXA4 may promote trophoblast invasion via the PI3K/Akt/eNOS pathway.

Vascular ligand-receptor mapping by direct combinatorial selection in cancer patients.

Molecules differentially expressed in blood vessels among organs or between damaged and normal tissues, are attractive therapy targets; however, their identification within the human vasculature is challenging. Here we screened a peptide library in cancer patients to uncover ligand-receptors common or specific to certain vascular beds. Surveying ~2.35 x 10(6) motifs recovered from biopsies yielded a nonrandom distribution, indicating that systemic tissue targeting is feasible. High-throughput analysis by similarity search, protein arrays, and affinity chromatography revealed four native ligand-receptors, three of which were previously unrecognized. Two are shared among multiple tissues (integrin α4/annexin A4 and cathepsin B/apolipoprotein E3) and the other two have a restricted and specific distribution in normal tissue (prohibitin/annexin A2 in white adipose tissue) or cancer (RAGE/leukocyte proteinase-3 in bone metastases). These findings provide vascular molecular markers for biotechnology and medical applications.

miR-203 Inhibits the Invasion and EMT of Gastric Cancer Cells by Directly Targeting Annexin A4.

Many studies have shown that downregulated miR-203 level is in a variety of cancers including gastric cancer (GC). However, the precise molecule mechanisms of miR-203 in GC have not been well clarified. In the current study, we investigated the biological functions and molecular mechanisms of miR-203 in GC cell lines. We found that miR-203 is downregulated in GC tissues and cell lines. Moreover, the low level of miR-203 was associated with increased expression of annexin A4 in GC tissues and cell lines. The invasion and EMT of GC cells were suppressed by overexpression of miR-203. However, downregulation of miR-203 promoted invasion and EMT of GC cells. Bioinformatics analysis predicted that annexin A4 was a potential target gene of miR-203. Next, luciferase reporter assay confirmed that miR-203 could directly target annexin A4. Consistent with the effect of miR-203, downregulation of annexin A4 by siRNA inhibited the invasion and EMT of GC cells. Introduction of annexin A4 in GC cells partially blocked the effects of miR-203 mimic. Introduction of miR-203 directly targeted annexin A4 to inhibit the invasion and EMT of GC cells. Overall, reactivation of the miR-203/annexin A4 axis may represent a new strategy for overcoming metastasis of GC.

[Study of altered expression of annexin IV and human endometrial receptivity].

OBJECTIVE: To explore the association of altered expression of annexin IV in human endometrium during the implantation window and endometrial receptivity. METHODS: A comparative proteomic strategy, in a combination of two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), was adopted to search for proteome alternations of pre-receptive (day LH + 2) versus receptive (LH + 7) endometria. The location and abundance of the identified differentially expressed protein- annexin IV were analyzed by immunostaining and western blot. RESULTS: By comparing protein profiles of LH + 2 and LH + 7 samples, we found a protein up-regulated 2.12 times in LH + 7 samples, with a relative molecular weight of 36,000 and an isoelectric point near pH 5.8. It was characterized using mass spectrometry and was identified as annexin IV. Immunohistochemical analysis revealed an altered localization of annexin IV--in the epithelia on day LH + 2, and both in the epithelia and stroma cells on day LH + 7. Protein levels of annexin IV were up-regulated on day LH + 7 compared with that on day LH + 2 by Western blot. Integrated optical density of the object (OPTDI) was 46.249 +/- 32.376 and 249.507 +/- 31.959, respectively (P = 0.004). CONCLUSIONS: Our study indicates endometrial samples obtained by microbiopsy are available for proteomics studies. It seems possible that the increased expression of annexin IV during the implantation window plays an important role in the morphological differentiation of the uterus to the receptive state.

Ethanol-induced augmentation of annexin IV in cultured cells and the enhancement of cytotoxicity by overexpression of annexin IV by ethanol.

The annexins are a family of highly homologous Ca(2+) and phospholipid binding proteins. The expressive amounts of several annexins have been shown to alter in certain pathological states such as brain ischemia and Alzheimer's disease. It has been demonstrated that ethanol induces cytotoxicity, which results in brain damage. In this study, we examined the relationship between ethanol-induced cytotoxicity and the intrinsic amount of annexins using cell lines (rat glioma C6 cells and human adenocarcinoma A549 cells). A decrease in the mitochondrial enzyme (dehydrogenase) activity, which is widely used to measure cytotoxicity, was observed with a high concentration of ethanol (200 mM or more) after a 24-h exposure in both C6 and A549 cells. Western blot analysis revealed that the amount of annexin IV was augmented in both cells by ethanol, whereas levels of annexins I and V were unchanged. The amount of annexin IV was augmented with increasing concentration of ethanol. The overexpression of annexin IV in C6 cells by transfection with annexin IV-DNA enhanced ethanol-induced cell lesion and was accompanied by NFkappaB activation. Thus, it might be indicated that the amount of annexin IV is selectively augmented and this augmentation facilitates the development of cell lesion by ethanol.

Differential expression of annexins I-VI in the rat dorsal root ganglia and spinal cord.

The annexins are a family of Ca(2+)-dependent phospholipid-binding proteins. In the present study, the spatial expression patterns of annexins I-VI were evaluated in the rat dorsal root ganglia (DRG) and spinal cord (SC) by using indirect immunofluorescence. Annexin I is expressed in small sensory neurons of the DRG, by most neurons of the SC, and by ependymal cells lining the central canal. Annexin II is expressed by most sensory neurons of the DRG but is primarily expressed in the SC by glial cells. Annexin III is expressed by most sensory neurons, regardless of size, by endothelial cells lining the blood vessels, and by the perineurium. In the SC, annexin III is primarily expressed by astrocytes. In the DRG and the SC, annexin IV is primarily expressed by glial cells and at lower levels by neurons. In the DRG, annexin V is expressed in relatively high concentrations in small sensory neurons in contrast to the SC, where it is expressed mainly by ependymal cells and by small-diameter axons located in the superficial laminae of the dorsal horn areas. Annexin VI is differentially expressed by sensory neurons of the DRG, being more concentrated in small neurons. In the SC, annexin VI has the most striking distribution. It is concentrated subjacent to the plasma membrane of motor neurons and their processes. The differential localization pattern of annexins in cells of the SC and DRG could reflect their individual biological roles in Ca(2+)-signal transduction within the central nervous system.

Increased expression and altered location of annexin IV in renal clear cell carcinoma: a possible role in tumour dissemination.

The proteome of renal cell carcinoma and non-neoplastic kidney tissue was analysed from 12 patients by two-dimensional polyacrylamide gel electrophoresis to search for differentially expressed proteins in the tumour. Annexin IV was identified to be up-regulated in tumour cells. These patients and further 11 were characterized by RT-PCR. We found an increased amount of annexin IV mRNA. Immunohistochemical analysis revealed an altered localization of annexin IV in tumour cells. Additionally we demonstrate that over-expressed annexin IV promotes cell migration in a carcinoma model system. From these results above it seems possible that annexin IV plays an important role in the morphological diversification and dissemination of the clear cell renal cell carcinoma.

Overexpression of annexin A4 is associated with chemoresistance in papillary serous adenocarcinoma of the ovary.

Annexin A4 study in ovarian cancer has been primarily focused on clear cell carcinoma, which exhibits strong resistance to chemotherapy. The aim of this study was to examine the expression and cellular localization of annexin A4 in serous ovarian carcinomas. We evaluated the expression of annexin A4 with real-time polymerase chain reaction in 40 ovarian serous carcinoma tissues. Furthermore, the distribution of the protein within the tumor was studied by immunohistochemistry in 70 epithelial ovarian carcinoma tissues. The levels of annexin A4 transcripts were higher in 14 chemoresistant tumors than those in 26 chemosensitive tumors (P = .013). Immunohistochemical expressions showed that nuclear expression was detected in 14 (20.0%) of 70 samples, and cytoplasmic expression was detected in 17 (24.3%) of 70 samples. The results showed that 35.7% of women with nuclear expression were resistant to platinum-based chemotherapy, whereas only 14.3% of women without expression were chemoresistant (P = .065). In addition, patients with nuclear staining had significantly shorter disease-free survival than did patients who showed negative staining. Multivariate proportional hazards model revealed that the stage and nuclear annexin A4 expression were independent prognostic factors (hazard ratios, 6.34 [P = .001] and 2.85 [P = .011], respectively). This study showed that overexpression and nuclear localization of annexin A4 are related to chemoresistance and poor survival in patients with serous papillary ovarian carcinomas. Future studies are required to develop new therapies targeting annexin A4 in patients with ovarian epithelial adenocarcinoma.

Cyclic changes and hormonal regulation of annexin IV mRNA and protein in human endometrium.

Annexin IV (ANXA4) belongs to a ubiquitous family of Ca(2+)-dependent phospholipid-binding proteins. ANXA4 has been shown to be involved in a range of physiological functions including ion channel regulation, exocytosis and Ca(2+)-dependent signal transduction. The aims of this study were to fully characterize ANXA4 mRNA and protein in human endometrium during the menstrual cycle and to investigate the hormonal regulation of ANXA4. ANXA4 mRNA expression was quantified by real-time PCR in fresh endometrial tissue from cycling women, and protein expression was analysed by immunohistochemistry and western blotting. Hormonal regulation of ANXA4 transcription and translation was investigated using an endometrial explant system. ANXA4 mRNA was significantly up-regulated during mid-secretory (MS) and late-secretory (LS) phases compared with proliferative phases during the menstrual cycle. ANXA4 protein was localized to glandular and luminal epithelium and was present in high levels throughout the menstrual cycle except during early-secretory (ES) phase, when it was significantly reduced. Our data also show that, in proliferative explants, progesterone significantly increased the ANXA4 mRNA and protein after 48h in culture. Estrogen did not have any significant effects. This is the first study to show that ANXA4 transcription and translation are regulated by progesterone and suggests that ANXA4 may be important in regulating ion and water transport across the endometrial epithelium.

A novel expression vector, designated as pHisJM, for producing recombinant His-fusion proteins.

Compared to glutathione S -transferase (GST), tagging with hexahistidine residues (His) has several merits: low levels of toxicity and immunogenicity, a smaller size and no electric charge. We have constructed a novel expression vector, designated as pHisJM (EMBL/GenBank/DDJB accession no. AB116367), for producing recombinant His-fusion proteins. This vector was constructed by replacing GST and multiple cloning site (MCS) cassettes in pGEX-5X-3 with those of hexahistidine and MCS derived from pRSET C vector. Human annexin IV (Anx IV) was used as target protein. His-Anx IV fusion protein was expressed using pHisJM and gave a 40 kDa band when immuno-stained with anti-His mAb or anti-Anx IV mAb as predicted. To compare expression efficiency, a Anx IV cDNA inserted-pHisJM or pGEX-5X-3 was transformed into Escherichia coli DH5alpha, JM109, BL21 and BL21(DE3). Using pHisJM, Anx IV protein was highly expressed in all cell strains. In addition to the merits of using His-tag, pHisJM has several advantages: 1) it has high expression efficiency; 2) it can be used in any Escherichia coli strain; and 3) it can be used in a single strain of Escherichia coli in all steps from plasmid construction to the expression of the target gene.

Comparison of the expression of native and mutant bovine annexin IV in Escherichia coli using four different expression systems.

Bovine annexin IV, a Ca(2+)-dependent, membrane-binding protein, was expressed in E. coli using four different prokaryotic expression vector systems. An annexin IV cDNA was mutated in the 5' noncoding region to introduce an NcoI restriction site at the translation initiation site. The coding sequence was then excised and ligated into the expression vectors: pKK233-2 (which uses a hybrid trc promoter), pFOG405 (which uses the alkaline phosphatase promoter and generates a fusion protein with the alkaline phosphatase signal sequence that targets the protein for secretion), pOTSNco12 (which provides temperature-sensitive expression from the lambda phage promoter), and pET11d (which uses the T7lac promoter and a protease-deficient host). Expression of wild type and mutant annexin IV in the various systems was compared. Differences in level of expression, formation of inclusion bodies, and yield of purified protein were observed. The pET11d system was found to be the most effective expression system for annexin IV and various annexin IV mutant constructs, providing the highest yield of functional protein from the soluble fraction of cell lysates. Bovine chromaffin granule binding and aggregating activities of recombinant annexin IV were found to be virtually indistinguishable from those of bovine annexin IV isolated from liver tissue. Truncation constructs containing one, two, or three of the four conserved 70-amino-acid domains of native annexin IV were successfully created and expressed in E. coli, but the recombinant proteins were generally insoluble. pET11d annexin constructs containing point mutations in residues involved in binding calcium produced soluble protein at levels comparable to those of constructs expressing wild type protein.

Modulation of paclitaxel resistance by annexin IV in human cancer cell lines.

A recurring problem with cancer therapies is the development of drug resistance. While investigating the protein profile of cells resistant to a novel antimitotic compound (A204197), we discovered an increase in annexin IV expression. When we examined the annexin IV protein expression level in a paclitaxel-resistant cell line (H460/T800), we found that annexin IV was also overexpressed. Interestingly a closely related protein, annexin II, was not overexpressed in H460/T800 cells. Immunostaining with either annexin II or IV antibody revealed that annexin IV was primarily located in the nucleus of paclitaxel-resistant H460/T800 cells. Short-term treatment of H460 cells with 10 nM paclitaxel for up to 4 days resulted in induction of annexin IV, but not annexin II expression. In addition, there was an increase in annexin IV staining in the nucleus starting at day 1. Furthermore, cells pretreated with 10 nM paclitaxel for 4 days resulted in cells becoming approximately fivefold more resistant to paclitaxel. Transfection of annexin IV cDNA into 293T cells revealed that there was a threefold increase in paclitaxel resistance. Thus our results indicate that annexin IV plays a role in paclitaxel resistance in this cell line and it is among one of the earliest proteins that is induced in cells in response to cytotoxic stress such as antimitotic drug treatment.

A role for annexin IV in epithelial cell function. Inhibition of calcium-activated chloride conductance.

The cellular function of annexin IV was evaluated by correlating tissue expression, cellular localization, and whole-cell electrophysiology. Immunolocalization and biochemical data demonstrate that annexin IV is concentrated along the apical membranes of many epithelia. Introduction of purified exogenous annexin IV into colonic T84 cells through a patch pipette specifically prevented Ca(2+)-dependent Cl- current activation. Affinity-purified antibody against annexin IV applied in the same manner enhanced the activation. Reduction of the endogenous level of annexin IV with a derivatized oligodeoxynucleotide antisense to annexin IV mRNA lowered the threshold for the Ca(2+)-induced current response, mimicking the enhancement of current activation exerted by anti-annexin IV antibody. The inhibitory effect of annexin IV on Ca(2+)-dependent Cl- conductance represents a novel mechanism by which Ca(2+)-binding proteins modulate membrane channel activity.