HSP90 C-terminal domain inhibition promotes VDAC1 oligomerization via decreasing K274 mono-ubiquitination in Hepatocellular Carcinoma.

Voltage-dependent anion-selective channel protein 1 (VDAC1) is the most abundant protein in the mitochondrial outer membrane and plays a crucial role in the control of hepatocellular carcinoma (HCC) progress. Our previous research found that cytosolic molecular chaperone heat shock protein 90 (Hsp90) interacted with VDAC1, but the effect of the C-terminal and N-terminal domains of Hsp90 on the formation of VDAC1 oligomers is unclear. In this study, we focused on the effect of the C-terminal domain of Hsp90 on VDAC1 oligomerization, ubiquitination, and VDAC1 channel activity. We found that Hsp90 C-terminal domain inhibitor Novobiocin promoted VDAC1 oligomerization, release of cytochrome c, and activated mitochondrial apoptosis pathway. Atomic coarse particle modeling simulation revealed C-terminal domain of Hsp90α stabilized VDAC1 monomers. The purified VDAC1 was reconstituted into a planar lipid bilayer, and electrophysiology experiments of patch clamp showed that the Hsp90 C-terminal inhibitor Novobiocin increased VDAC1 channel conductance via promoting VDAC1 oligomerization. The mitochondrial ubiquitination proteomics results showed that VDAC1 K274 mono-ubiquitination was significantly decreased upon Novobiocin treatment. Site-directed mutation of VDAC1 (K274R) weakened Hsp90α-VDAC1 interaction and increased VDAC1 oligomerization. Taken together, our results reveal that Hsp90 C-terminal domain inhibition promotes VDAC1 oligomerization and VDAC1 channel conductance by decreasing VDAC1 K274 mono- ubiquitination, which provides a new perspective for mitochondria-targeted therapy of HCC.

Stanniocalcin 1 promotes lung metastasis of breast cancer by enhancing EGFR-ERK-S100A4 signaling.

Lung metastasis is the leading cause of breast cancer-related death. The tumor microenvironment contributes to the metastatic colonization of tumor cells in the lungs. Tumor secretory factors are important mediators for the adaptation of cancer cells to foreign microenvironments. Here, we report that tumor-secreted stanniocalcin 1 (STC1) promotes the pulmonary metastasis of breast cancer by enhancing the invasiveness of tumor cells and promoting angiogenesis and lung fibroblast activation in the metastatic microenvironment. The results show that STC1 modifies the metastatic microenvironment through its autocrine action on breast cancer cells. Specifically, STC1 upregulates the expression of S100 calcium-binding protein A4 (S100A4) by facilitating the phosphorylation of EGFR and ERK signaling in breast cancer cells. S100A4 mediates the effect of STC1 on angiogenesis and lung fibroblasts. Importantly, S100A4 knockdown diminishes STC1-induced lung metastasis of breast cancer. Moreover, activated JNK signaling upregulates STC1 expression in breast cancer cells with lung-tropism. Overall, our findings reveal that STC1 plays important role in breast cancer lung metastasis.

Amino Acid Leaching of Critical Metals from Spent Lithium-Ion Batteries Followed by Selective Recovery of Cobalt Using Aqueous Biphasic System.

To reduce the exploitation of mine resources and decrease the harm to the environment caused by urban electronic wastes, the recovery of critical metals in secondary resources is crucial. In this study, we have successfully developed an eco-friendly process to integrate the leaching and separation of cobalt (Co) from a spent lithium-ion battery (LIB) cathode using an amino acid-based aqueous biphasic system (ABS). We, for the first time, demonstrated a simple method for leaching a LIB cathode using only amino acids. In addition, we have investigated the leaching mechanism using the typical cathode active material lithium cobalt oxide (LiCoO2). Then, the Co was selectively extracted by a biphasic system (amino acid-PPG400-H2O). This novel process has an excellent prospect in the field of spent-battery recycling because of its eco-friendly and process-simplified advantages.

MCU-dependent negative sorting of miR-4488 to extracellular vesicles enhances angiogenesis and promotes breast cancer metastatic colonization.

Based on Stephen Paget's well-established theory, both cell-autonomous and non-cell-autonomous mechanisms are crucial for metastasis. Although the mitochondrial calcium uniporter (MCU) has been suggested to be involved in breast cancer (BC) progression via cell-autonomous mechanisms, whether it assists the metastasis of BC cells through non-cell-autonomous mechanisms remains unclear. This study aimed to demonstrate that the MCU regulates BC metastatic colonization via non-cell-autonomous mechanisms. The results suggested that extracellular vesicles (EVs) derived from MCU-downregulated MDA-MB-231 cells suppressed angiogenesis in the metastatic niche in a nude mouse model, thereby hindering the colonization of BC cells. Mechanistically, we revealed that the MCU negatively correlated with miR-4488 in EVs derived from BC cells. Significantly, miR-4488 was determined to suppress angiogenesis of vascular endothelial cells by directly targeting angiogenic CX3CL1. Furthermore, we identified miR-4488 as being significantly downregulated in serum EVs from patients with triple-negative BC. Hence, this study suggests that MCU-dependent negative sorting of miR-4488 to EVs enhances angiogenesis in the metastatic niche and, thus, favors the metastatic colonization of BC cells.

Calcium-sensing stromal interaction molecule 2 upregulates nuclear factor of activated T cells 1 and transforming growth factor-ß signaling to promote breast cancer metastasis.

BACKGROUND: Stromal interaction molecule (STIM) 2 is a key calcium-sensing molecule that regulates the stabilization of calcium ions (Ca2+) and therefore regulates downstream Ca2+-associated signaling and cellular events. We hypothesized that STIM2 regulates epithelial-mesenchymal transition (EMT) to promote breast cancer metastasis. METHODS: We determined the effects of gain, loss, and rescue of STIM2 on cellular motility, levels of EMT-related proteins, and secretion of transforming growth factor-ß (TGF-ß). We also conducted bioinformatics analyses and in vivo assessments of breast cancer growth and metastasis using xenograft models. RESULTS: We found a significant association between STIM2 overexpression and metastatic breast cancer. STIM2 overexpression activated the nuclear factor of activated T cells 1 (NFAT1) and TGF-ß signaling. Knockdown of STIM2 inhibited the motility of breast cancer cells by inhibiting EMT via specific suppression of NFAT1 and inhibited mammary tumor metastasis in mice. In contrast, STIM2 overexpression promoted metastasis. These findings were validated in human tissue arrays of 340 breast cancer samples for STIM2. CONCLUSION: Taken together, our results demonstrated that STIM2 specifically regulates NFAT1, which in turn regulates the expression and secretion of TGF-ß1 to promote EMT in vitro and in vivo, leading to metastasis of breast cancer.

Knockdown of FAM64A suppresses proliferation and migration of breast cancer cells.

BACKGROUND: FAM64A is a mitotic regulator promoting cell metaphase-anaphase transition, and it is frequently reported to be highly expressed in cancer cells. However, the role of FAM64A in human breast cancer (BrC) is poorly studied. METHODS: The expression of FAM64A mRNA in BrC samples was determined by RT-qPCR assay and TCGA database mining. Kaplan-Meier plotter was used to analyze whether FAM64A expression impacted prognosis. Then, the expression of FAM64A was silenced using RNA interference. Cell-counting assay, colony formation assay and flow cytometry assay were conducted to detect proliferation; transwell migration assay, EMT-related proteins expression (E-cadherin, N-cadherin and vimentin), and EMT-related transcription factors mRNA expression (Snail, Twist, Slug) were conducted to evaluate the migration ability. RESULTS: FAM64A was highly expressed in human BrC samples, which was negatively associated with poor survival time. Analysis of FAM64A expression in BrC cell lines demonstrated that the expression of FAM64A was significantly correlated with the proliferation rate and migration ability of BrC cells. Indeed, knockdown of FAM64A suppressed the proliferation of MDA-MB-231 and MCF-7 cells. Importantly, we also found that silencing of FAM64A inhibited the migration of BrC cells via impeding epithelial-mesenchymal transition. CONCLUSIONS: Our findings suggest that FAM64A plays an important role in the proliferation and migration of BrC cells, which might serve as a potential target for BrC treatment.

Highly selective and sensitive probes for the detection of Cr(vi) in aqueous solutions using diglycolic acid-functionalized Au nanoparticles.

In this study, a variety of diglycolic acid-functionalized gold nanoparticle (Au NP) probes are reported, which are highly sensitive for the detection of chromium ions, Cr(vi) ions, at low concentrations in aqueous solutions based on the application of surface plasmon resonance (SPR) theory. Due to its outstanding affinity for Cr(vi) ions, the capped diglycolic acid would induce the aggregation of the NP probes upon encountering them; this was evidenced by the obvious red-shifting of the SPR peak and the enlarged size of the NPs. For the same reason, the selectivity of the probe for Cr(vi) against other heavy metal ions was found to be remarkable. Under optimized conditions, the probe showed the limit of detection (LOD) of 0.32 ppb for Cr(vi) and a linear detection scale ranging from 0.32 ppb to 0.1 ppm. To the best of our knowledge, this is probably the lowest LOD reported for Cr(vi) detection among those of the methods based on SPR.

Exosomes derived from breast cancer lung metastasis subpopulations promote tumor self-seeding.

Lung metastasis is a primary obstacle in the clinical treatment of metastatic breast cancer. Most patients with lung metastasis eventually die of recurrence. Recurrence may be related to self-seeding, which occurs when circulating tumor cells re-seed into the tumors they originated from (metastasis or carcinoma in situ). Tumor-derived exosomes have been intensively revealed to promote the progression of various cancers. However, whether tumor-derived exosomes play roles in tumor self-seeding has not yet been identified. By establishing a self-seeding nude mouse model, we found that exosomes derived from MDA231-LM2 cells (subpopulations of breast cancer lung metastasis) potentiate the growth of MDA-MB-231 xenografts. More importantly, laser confocal microscopy and flow cytometry results identified that MDA231-LM2-secreted exosomes promote the seeding of MDA231-LM2 cells into MDA-MB-231 xenografts. These findings suggest MDA231-LM2-secreted exosomes as a promising target to treat breast cancer lung metastasis.

Preparation of elastic diglycolamic-acid modified chitosan sponges and their application to recycling of rare-earth from waste phosphor powder.

Inspired by the phenomenon of sponges soaking up water, a novel syringe-like adsorption device used diglycolamic-acid modified chitosan sponges (CSs-DGAA) as adsorbents is reported for recycling of rare-earth elements (REEs) by Squeezing & Soaking (S&S) operation. Integrating the elasticity of sponges and selective extraction ability of diglycolamic acid groups, the new device can efficiently recycle REEs from aqueous solutions. This device only needs 10 min to achieve adsorption equilibrium; squeezing the water from the sponges achieves solid-liquid separation. This syringe-like adsorption method not only solves the pollution problem caused by the organic solvents used during liquidliquid extractions, but also improves the time needed to achieve adsorption equilibrium and uses significantly less energy than energy intensive solid-phase extractions of solid-liquid separations. Moreover, the environment-friendly adsorbents effectively recycle yttrium and europium from waste phosphor powders. These experimental results demonstrated that the S&S method based on polymeric sponges has potential application in hydrometallurgy and environmental remediation.

Mitochondrial calcium uniporter as a target of microRNA-340 and promoter of metastasis via enhancing the Warburg effect.

BACKGROUND: A shift from oxygen phosphorylation to aerobic glycolysis was known as the Warburg effect and a characteristic of cancer cell metabolism facilitating metastasis. Mitochondrial calcium uniporter (MCU), a key ion channel that mediates Ca2+ uptake into mitochondria, was found to promote cancer progression and metastasis. However, its explicit role in shifting metabolism of breast cancer cells has not been defined. METHODS: We evaluated MCU overexpression or knock-down on migration, invasion and glucose metabolismin breast cancer cells. Mitochondrial Ca2+ dynamics were monitored with Rhod-2 fluorescence imaging. Luciferase reporter assay was used to confirm the interaction between miR-340 and 3'-untranslated region (3'-UTR) of MCU gene. Mouse models of lung metastasis were used to determine whether gain-/loss-of-MCU impacts metastasis. MCU expression was assessed in 60 tumor samples from breast cancer patients by immunohistochemistry (IHC). RESULTS: Knockdown of MCU in MDA-MB-231 cells significantly reduced cell migration and invasion in vitro and lung metastasis in vivo; whereas overexpression of MCU in MCF-7 cells significantly increased migration and invasion in vitro and lung metastasis in vivo. Overexpression of MCU promoted lung metastasis by enhancing glycolysis, whereas suppression of MCU abolished this effect. Moreover, a novel mechanism was identified that MCU was a direct target of microRNA-340, which suppressed breast cancer cell motility by inhibiting glycolysis. Consistently, significantly increased MCU protein was found in metastatic breast cancer patients. CONCLUSIONS: We identified a novel mechanism that upregulated MCU promotes breast cancer metastasis via enhancing glycolysis, and that this process is posttranscriptionally and negatively regulated by microRNA-340.

STIM1 and STIM2 differently regulate endogenous Ca2+ entry and promote TGF-ß-induced EMT in breast cancer cells.

The Ca2+ sensor proteins STIM1 and STIM2 are crucial elements of store-operated calcium entry (SOCE) in breast cancer cells. Increased SOCE activity may contribute to epithelial-mesenchymal transitions (EMT) and increase cell migration and invasion. However, the roles of STIM1 and STIM2 in TGF-ß-induced EMT are still unclear. In this study, we demonstrate roles of STIMs in TGF-ß-induced EMT in breast cancer cells. In particular, STIM1 and STIM2 expression affected TGF-ß-induced EMT by mediating SOCE in MDA-MB-231 and MCF-7 breast cancer cells. The specific SOCE inhibitor YM58483 blocked TGF-ß-induced EMT, and differing effects of STIM1 and STIM2 on TGF-ß-induced EMT correlated with differing roles in SOCE. Finally, we showed that STIM2 is associated with non-store-operated calcium entry (non-SOCE) during TGF-ß-induced EMT, whereas STIM1 is not. What's more, non-SOCE have a large possibility to be ROCE. In conclusion, STIM1 and STIM2 proteins play important roles in TGF-ß-induced EMT and these effects are related to both SOCE and non-SOCE.

Phosphorylation of dynamin-related protein 1 at Ser616 regulates mitochondrial fission and is involved in mitochondrial calcium uniporter-mediated neutrophil polarization and chemotaxis.

During an inflammatory response, polarization of neutrophils is necessary for effective chemotaxis and bacterial endocytosis. Ca2+ uptake into mitochondria through the mitochondrial calcium uniporter (MCU) is crucial for cell metabolism, signaling and survival; however, the physiological role of MCU in human neutrophils remains unclear. Here we show that MCU is vital for the polarization and chemotaxis of neutrophils. Activation of MCU by spermine promotes neutrophil polarization and chemotaxis, whereas inhibition of MCU by Ru360 blunts both processes. We also provide evidence that this role of the MCU in neutrophils may result from modulation of mitochondrial fission by increased levels of pDrp1 S616 via accumulation of Ca2+ into the mitochondrial matrix. Thus, our study identifies the dependence of neutrophil polarization and chemotaxis on the MCU and highlights the importance of regulating mitochondrial fission during the anti-inflammatory cascade in human neutrophils.

Downregulation of ACE2/Ang-(1-7)/Mas axis promotes breast cancer metastasis by enhancing store-operated calcium entry.

The renin-angiotensin system (RAS) is an important component of the tumor microenvironment and plays a key role in promoting cancer cell proliferation, angiogenesis, metabolism, migration and invasion. Meanwhile, the arm of angiotensin-converting enzyme (ACE)2/angiotensin-(1-7) [Ang-(1-7)]/Mas axis in connection with RAS is associated with anti-proliferative, vasodilatory and anti-metastatic properties. Previous studies have shown that Ang-(1-7) reduces the proliferation of orthotopic human breast tumor growth by inhibiting cancer-associated fibroblasts. However, the role of ACE/Ang-(1-7)/Mas axis in the metastasis of breast cancer cells is still unknown. In the present study, we found that ACE2 protein level is negatively correlated with the metastatic ability of breast cancer cells and breast tumor grade. Upregulation of ACE2/Ang-(1-7)/Mas axis inhibits breast cancer cell migration and invasion in vivo and in vitro. Mechanistically, ACE2/Ang-(1-7)/Mas axis activation inhibits store-operated calcium entry (SOCE) and PAK1/NF-κB/Snail1 pathways, and induces E-cadherin expression. In summary, our results demonstrate that downregulation of ACE2/Ang-(1-7)/Mas axis stimulates breast cancer metastasis through the activation of SOCE and PAK1/NF-κB/Snail1 pathways. These results provide new mechanisms by which breast cancer develop metastasis and shed light on developing novel anti-metastasis therapeutics for metastatic breast cancer by modulating ACE2/Ang-(1-7)/Mas axis.

Store-operated Ca2+ entry plays a role in HMGB1-induced vascular endothelial cell hyperpermeability.

AIMS: Endothelial dysfunction, including increased endothelial permeability, is considered an early marker for atherosclerosis. High-mobility group box 1 protein (HMGB1) and extracellular Ca2+ entry, primarily mediated through store-operated Ca2+ entry (SOCE), are known to be involved in increasing endothelial permeability. The aim of this study was to clarify how HMGB1 could lead to endothelia hyperpermeability. METHODS AND RESULTS: We have shown that human vascular endothelial cell permeability is increased, while transendothelial electrical resistance and VE-cadherin expression were reduced by HMGB1 treatment. Two SOCE inhibitors and knockdown of stromal interaction molecule 1 (STIM1), a Ca2+ sensor mediating SOCE, inhibited the HMGB1-induced influx of Ca2+ and Src activation followed by significant suppression of endothelial permeability. Moreover, knockdown of Orai1, an essential pore-subunit of SOCE channels, decreased HMGB1-induced endothelial hyperpermeability. CONCLUSIONS: These data suggest that SOCE, acting via STIM1, might be the predominant mechanism of Ca2+ entry in the modulation of endothelial cell permeability. STIM1 may thus represent a possible new therapeutic target against atherosclerosis.

Mitochondrial Ca²âº uniporter is critical for store-operated Ca²âº entry-dependent breast cancer cell migration.

Metastasis of cancer cells is a complicated multistep process requiring extensive and continuous cytosolic calcium modulation. Mitochondrial Ca(2+) uniporter (MCU), a regulator of mitochondrial Ca(2+) uptake, has been implicated in energy metabolism and various cellular signaling processes. However, whether MCU contributes to cancer cell migration has not been established. Here we examined the expression of MCU mRNA in the Oncomine database and found that MCU is correlated to metastasis and invasive breast cancer. MCU inhibition by ruthenium red (RuR) or MCU silencing by siRNA abolished serum-induced migration in MDA-MB-231 breast cancer cells and reduced serum- or thapsigargin (TG)-induced store-operated Ca2+ entry (SOCE). Serum-induced migrations in MDA-MB-231 cells were blocked by SOCE inhibitors. Our results demonstrate that MCU plays a critical role in breast cancer cell migration by regulating SOCE.

Role of the mitochondrial Ca²âº uniporter in Pb²âº-induced oxidative stress in human neuroblastoma cells.

Lead (Pb(2+)) has been shown to induce cellular oxidative stress, which is linked to changes in intracellular calcium (Ca(2+)) concentration. The mitochondrial Ca(2+) uniporter (MCU) participates in the maintenance of Ca(2+) homeostasis in neurons, but its role in Pb(2+)-induced oxidative stress is unclear. To address this question, oxidative stress was induced in human neuroblastoma SH-SY5Y cells and in newborn rats by Pb(2+) treatment. The results showed that the production of reactive oxygen species is increased in cells upon treatment with Pb(2+) in a dose-dependent manner, while glutathione and MCU expression were reduced. Moreover, neuronal nitric oxide synthase protein expression was elevated in rats exposed to Pb(2+) during gestation, while MCU expression was decreased. Application of the MCU activator spermine or MCU overexpression reversed Pb(2+)-induced oxidative stress and inhibition of mitochondrial Ca(2+) uptake, while the MCU inhibitor Ru360 and MCU knockdown potentiated the effects of Pb(2+). These results indicate that the MCU mediates the Pb(2+)-induced oxidative stress response in neurons through the regulation of mitochondrial Ca(2+) influx.

Store-operated Ca²âº entry mediated regulation of polarization in differentiated human neutrophil-like HL-60 cells under hypoxia.

The regulation of neutrophil polarization by calcium entry is critical for maintaining an effective host response. Hypoxia has a major effect on the apoptosis of neutrophils, however the role of store-operated Ca2+ entry (SOCE) in neutrophil polarization under hypoxia remains to be elucidated. In the present study, we examined the polarization of differentiated human neutrophil-like HL-60 (dHL-60) cells exposed to hypoxia (3% O2) and the results demonstrated that the percentage of polarized cells following exposure to an N-formyl-Met-Leu-Phe (fMLP) gradient in the Zigmond chamber was increased. We examined stromal interaction molecule 1 (STIM1) and Orai1 expression in dHL-60 cells during hypoxia, and it was observed that the expression of STIM1 and Orai1 was significantly reduced at day 2. However, no apparent change was observed on the first day, indicating that this effect is dependent on stimulation time. Fluo-4/acetoxymethyl (AM) ester imaging also demonstrated that SOCE was decreased in dHL-60 cells. The plasmid overexpression assay demonstrated that the response of polarization was returned to the control level. We demonstrated the inhibitory role of SOCE on the polarization of dHL-60 cells under hypoxic conditions, which may be the mechanism for the adaptation of neutrophils to hypoxia. SOCE is also suggested to be a key modulator of immune deficiency under hypoxic conditions and is potentially a therapeutic target.

[Polarization of neutrophils from patients with asthma, chronic obstructive pulmonary disease and asthma-chronic obstructive pulmonary disease overlap syndrome].

OBJECTIVE: To explore the polarization of migration dynamics of neutrophils isolated from patients with asthma, chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap syndrome (ACOS) compared with healthy smoking and non-smoking controls. METHODS: Recruited volunteers were classified as healthy controls, healthy smokers, asthma, COPD and ACOS at Nanfang Hospital from April 2013 to June 2014 according to the Global Strategy for the Diagnosis, Management and Prevention of COPD 2011, Global Strategy for Asthma Management and Prevention 2011 and Consensus on Overlap Phenotype COPD-asthma in COPD 2012. Neutrophils were freshly isolated from whole blood with density gradient technique. The proportion of polarized cells with gradient concentration of formyl-Met-Leu-Phe (fMLP) in Zigmond chamber and vital component of Store Operated Calcium Entry (SOCE) (stromal interaction molecule (STIM) 1, 2 and Orai1) in neutrophils was detected by Western blot. RESULTS: Asthma, COPD and ACOS neutrophils demonstrated a higher spontaneous polarization rate versus healthy controls and healthy smokers ((25.05 ± 4.06)%, (16.20 ± 4.46)%, (29.43 ± 5.53)% vs (7.27 ± 0.99)%, (7.06 ± 3.12)%, all P < 0.01), asthma and ACOS neutrophils showed a higher directed polarization rate ((14.62 ± 2.26)%, (8.00 ± 1.75)%, all P < 0.05), but COPD had a relatively lower rate of directional polarization rate than healthy controls and healthy smokers ((2.45 ± 0.54)% vs (5.12 ± 1.28)%, (5.24 ± 1.34)%, all P < 0.01). The vital component of SOCE in neutrophils from asthma, COPD and ACOS were all up-regulated versus healthy controls and healthy smokers (STIM1: 1.63 ± 0.14, 0.88 ± 0.41, 1.29 ± 0.22 vs 0.26 ± 0.14, 0.38 ± 0.12; STIM2: 0.52 ± 0.19, 0.22 ± 0.13, 0.24 ± 0.10 vs 0.05 ± 0.03, 0.10 ± 0.06; Orai1: 0.56 ± 0.04, 0.39 ± 0.05, 0.48 ± 0.05 vs 0.13 ± 0.04, 0.13 ± 0.03) (all P < 0.01). CONCLUSIONS: Asthma, COPD and ACOS neutrophils are intrinsically different than counterparts from healthy control subjects and healthy smokers. And vital components of SOCE from patient neutrophils are intrinsically up-regulated.

TRPM7 mediates breast cancer cell migration and invasion through the MAPK pathway.

Metastasis is an inherent feature of breast cancer and transient receptor potential (TRP) channels were found to be potentially implicated in this process. Particularly, TRPM7 may regulate cell motility. We therefore examined the expression of TRPM7 mRNA in the Oncomine database and found that TRPM7 is correlated to metastasis and invasive breast cancer. Silencing TRPM7 with RNA interference resulted in a significant decrease in migration and invasion capability of MDA-MB-435 breast cancer cells, and phosphorylation levels of Src and MAPK but not AKT. Our results suggest that TRPM7 regulates migration and invasion of metastatic breast cancer cells via MAPK pathway.

Requirement for both receptor-operated and store-operated calcium entry in N-formyl-methionine-leucine-phenylalanine-induced neutrophil polarization.

Tissue penetration of neutrophils is a key process in many inflammatory diseases. In response to inflammatory stimuli such as N-formyl-methionine-leucine-phenylalanine (fMLP), neutrophils polarize and migrate towards the chemotactic gradient of the stimulus. Elevated intracellular Ca(2+) concentration is known to play a critical role in neutrophil polarization and migration; however, the exact mechanism remains elusive. Here, we demonstrated that fMLP stimulation caused not only store-operated calcium entry (SOCE), but also receptor-operated calcium entry (ROCE) in neutrophils by using both pharmacological and neutralizing monoclonal antibody approaches. We also investigated neither Rac2 nor Cdc42 activation could take place if either SOCE or ROCE was inhibited. This study thus provides the first evidence for coordination of Ca(2+) influx by SOCE and ROCE to regulate neutrophil polarization.