LncRNA HOXD-AS1 promotes oral squamous cell carcinoma by sponging miR-203a-5p.

OBJECTIVE: In the present study, we aimed to explore lncRNA HOXD cluster antisense RNA 1 (HOXD-AS1) expression in oral squamous cell carcinoma (OSCC) tissues, its biological roles, and the underlying potential mechanisms in OSCC progression. MATERIALS AND METHODS: HOXD-AS1 expression in paired OSCC and non-tumor tissues from 60 OSCC patients was determined by RT-qPCR. The effects of HOXD-AS1 and miR-203a-5p overexpression on expression of Annexin A4, a validated target of miR-203a-5p, were analyzed by RT-qPCR and Western blot. The roles of HOXD-AS1, miR-203a-5p, and Annexin A4 in the invasion and migration of OSCC cells were analyzed by Transwell assays. RESULTS: HOXD-AS1 overexpression in OSCC predicted poor survival. HOXD-AS1 was predicted to interact with miR-203a-5p, but its expression was not significantly correlated with miR-203a-5p. HOXD-AS1 overexpression increased Annexin A4 expression, while miR-203a-5p overexpression decreased Annexin A4 expression in OSCC cells. Transwell assays showed that invasion and migration of OSCC cells were enhanced by HOXD-AS1 and Annexin A4 overexpression but were reduced by miR-203a-5p overexpression. In addition, miR-203a-5p overexpression suppressed the role of HOXD-AS1 in cell movement and Annexin A4 expression. CONCLUSIONS: HOXD-AS1 may upregulate Annexin A4 by sponging miR-203a-5p in OSCC to promote cancer cell invasion and migration.

Skin Wound Repair Is Not Altered in the Absence of Endogenous AnxA1 or AnxA5, but Pharmacological Concentrations of AnxA4 and AnxA5 Inhibit Wound Hemostasis.

Skin injury induces the cell surface exposure of phosphatidylserine (PS) on damaged and dying cells to activate coagulation and repair processes. Annexins can bind to PS and may modulate the healing response. Here, we determine the relevance of annexins for skin wound healing using AnxA1- and AnxA5-deficient mice and recombinant annexins with distinct PS binding properties. Wound inflammation, closure and the formation of granulation tissue were not altered in AnxA1- or AnxA5-deficient mice or after increasing AnxA5 serum concentrations (100 nM) in wild-type mice. Increased serum concentrations (1 µM) of AnxA5 induced massive bleeding, but wound hemostasis was not delayed by AnxA1. Both annexins interact with PS, but only AnxA5 can form 2-dimensional (2D) arrays on the cell surface. The injection of an AnxA5 mutant that binds to PS but lacks the ability of 2D array formation failed to induce bleeding. 2D lattice-forming AnxA4, with high affinity to PS also caused bleeding, while hemostasis was not affected by AnxA8 with low affinity or the AnxA8 mutant with medium affinity for PS and the lack of 2D formation. Increased concentrations of AnxA4 and AnxA5 also delayed coagulation pathway activation in vitro. This effect was attenuated for the AnxA5 mutant as well as for AnxA1 and AnxA8. In conclusion, endogenous AnxA1 and AnxA5 are dispensable for wound hemostasis and repair, but pharmacologically excessive concentrations of AnxA4 and AnxA5 inhibit hemostasis in skin wounds.

Annexins I and IV inhibit Staphylococcus aureus attachment to human macrophages.

Annexins are a family of proteins that bind to phospholipids and carbohydrates in a calcium-dependent manner. They are present in a variety of body fluids. Previous studies have shown that annexins have anti-inflammatory activities for lipid A of Gram-negative bacteria. The present study investigated the effect of annexins on interaction between Gram-positive bacteria and immune cells such as macrophages. Annexins I and IV bound to lipoteichoic acids which are surface molecules on Gram-positive bacteria. Binding of annexins I and IV to whole Staphylococcus aureus (S. aureus) were observed and these bindings were inhibited by lipoteichoic acid from S. aureus. Moreover, annexins I and IV suppressed the attachment of S. aureus to phorbol 12-myristate 13-acetate-treated THP-1 cells (human macrophages). These results suggest that annexins I and IV have ligand specificities toward foreign substances, and that the annexins might have some anti-inflammatory property for Gram-positive bacteria.

Annexin IV inhibits calmodulin-dependent protein kinase II-activated chloride conductance. A novel mechanism for ion channel regulation.

Ca(2+)-activated Cl- current (ICl,Ca) in colonic T84 cells is inhibited by the specific peptide inhibitor of Ca2+/calmodulin-dependent kinase II (CaM KII). Annexin IV, a Ca(2+)-dependent phospholipid binding protein also inhibits Ca(2+)-dependent anion current activation (Kaetzel, M.A., Chan, H.-C., Dubinsky, W.P., Dedman, J.R., and Nelson, D.J. (1994) J. Biol. Chem. 269, 5297-5302). Intracellular injection of antibodies against annexin IV enhances current activation; this activation is inhibited by the peptide inhibitor of CaM KII. Intracellular application of autonomously active CaM KII in the presence of ATP induced a Cl- current similar to that activated by the Ca2+ ionophore A23187. Current activation by the exogenous kinase was completely inhibited in the presence of purified annexin IV. In vitro, annexin IV does not inhibit CaM KII activity nor does it act as a substrate for CaM KII. Thus, it appears that annexin IV inhibits phosphorylation-dependent anion conductance activation by preventing CaM KII-ion channel interaction rather than by direct interaction with the enzyme itself. These findings suggest a novel mechanism by which Ca(2+)-dependent membrane binding proteins, cytoplasmic kinases, and ion channels interact to regulate membrane conductance. The characterization of unique channel regulatory pathways in Cl- transporting epithelia may identify potential avenues of alternate therapy to compensate for the loss of functional Cl- channels in the disease of cystic fibrosis.

Annexin IV reduces the rate of lateral lipid diffusion and changes the fluid phase structure of the lipid bilayer when it binds to negatively charged membranes in the presence of calcium.

Bovine annexin IV (endonexin) was bound to supported planar bilayers composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) in the first monolayer facing the substrate, and varying mole fractions of POPC, 1-palmitoyl-2-oleoylphosphatidylglycerol (POPG) and small amounts of the fluorescent lipid analogs NBD-PC or NBD-PG in the second monolayer facing the large aqueous compartment. Lateral diffusion coefficients and mobile fractions of these phospholipids were measured by fluorescence recovery after photobleaching (FRAP) as a function of protein concentration and lipid composition in the presence of 2 mM CaCl2 or 1 mM EDTA. In the absence of annexin IV, the lateral diffusion coefficients depended only little on the POPC:POPG ratios and were approximately 3.0 microns2/s for NBD-PG (no Ca2+), 2.5 microns2/s for NBD-PG (2 mM Ca2+), and 1.6 microns2/s for NBD-PC (with or without 2 mM Ca2+). In the presence of 2 mM Ca2+ these diffusion coefficients decreased as a function of the added annexin concentration. A transition from a state with "rapid" lipid diffusion to a state with "slow" lipid diffusion occurred at about 80 nM annexin IV and was independent of the POPC:POPG ratio. In addition to reducing the lipid lateral diffusion coefficients, annexin IV also gave rise to two-component lateral diffusion of the lipids in these mixed bilayers. The split of the single diffusion coefficient of NBD-PG into two components occurred at most POPC:POPG ratios upon binding of annexin IV, but required higher annexin concentrations at mole fractions of POPC between 66 and 82 mol % than at high mole fractions of POPG or 90 mol % POPC.(ABSTRACT TRUNCATED AT 250 WORDS)