Zeng B, Chen GL, Daskoulidou N, Xu SZ (2014) The ryanodine receptor agonist 4-chloro-3-ethylphenol blocks ORAI store-operated channels., Br J Pharmacol171(5)pp. 1250-1259
BACKGROUND: Depletion of the Ca(2+) store by ryanodine receptor (RyR) agonists induces store-operated Ca(2+) entry (SOCE). 4-Chloro-3-ethylphenol (4-CEP) and 4-chloro-m-cresol (4-CmC) are RyR agonists commonly used as research tools and diagnostic reagents for malignant hyperthermia. Here, we investigated the effects of 4-CEP and its analogues on SOCE. EXPERIMENTAL APPROACH: SOCE and ORAI1-3 currents were recorded by Ca(2+) imaging and whole-cell patch recordings in rat L6 myoblasts and in HEK293 cells overexpressing STIM1/ORAI1-3. KEY RESULTS: 4-CEP induced a significant release of Ca(2+) in rat L6 myoblasts, but inhibited SOCE. The inhibitory effect was concentration-dependent and more potent than its analogues 4-CmC and 4-chlorophenol (4-ClP). In the HEK293 T-REx cells overexpressing STIM1/ORAI1-3, 4-CEP inhibited the ORAI1, ORAI2 and ORAI3 currents evoked by thapsigargin. The 2-APB-induced ORAI3 current was also blocked by 4-CEP. This inhibitory effect was reversible and independent of the Ca(2+) release. The two analogues, 4-CmC and 4-ClP, also inhibited the ORAI1-3 channels. Excised patch and intracellular application of 4-CEP demonstrated that the action site was located extracellularly. Moreover, 4-CEP evoked STIM1 translocation and subplasmalemmal clustering through its Ca(2+) store-depleting effect via the activation of RyR, but no effect on STIM1 redistribution was observed in cells co-expressing STIM1/ORAI1-3. CONCLUSION AND IMPLICATIONS: 4-CEP not only acts as a RyR agonist to deplete the Ca(2+) store and trigger STIM1 subplasmalemmal translocation and clustering, but also directly inhibits ORAI1-3 channels. These findings demonstrate a novel pharmacological property for the chlorophenol derivatives that act as RyR agonists.
Oleksiewicz U, Liloglou T, Tasopoulou KM, Daskoulidou N, Bryan J, Gosney JR, Field JK, Xinarianos G (2013) Cytoglobin has bimodal: tumour suppressor and oncogene functions in lung cancer cell lines., Hum Mol Genet22(16)pp. 3207-3217
Cytoglobin (CYGB) is frequently downregulated in many types of human malignancies, and its exogenous overexpression reduces proliferation of cancer cells. Despite its implied tumour suppressor (TSG) functions, its exact role in carcinogenesis remains unclear as CYGB upregulation is also associated with tumour hypoxia and aggressiveness. In this study, we explore the TSG role of CYGB, its influence on the phenotype of cancerous cells under stress conditions and the clinical significance of CYGB expression and promoter methylation in non-small cell lung cancer (NSCLC). DNA methylation-dependent expression silencing of CYGB is demonstrated in both clinical samples and cell lines. CYGB promoter was more frequently methylated in lung adenocarcinomas (P = 1.4 × 10(-4)). Demethylation by 5'-azadeoxycytidine partially restored CYGB expression in cell lines. Interestingly, trichostatin A triggered upregulation of CYGB expression in cancer cell lines and downregulation in non-tumourigenic ones. CYGB mRNA expression in NSCLC surgical specimens correlated with that of HIF1± and VEGFa (P < 1 × 10(-4)). Overexpression of CYGB in cancer cell lines reduced cell migration, invasion and anchorage-independent growth. Moreover, CYGB impaired cell proliferation, but only in the lung adenocarcinoma cell line (H358). Upon hydrogen peroxide treatment, CYGB protected cell viability, migratory potential and anchorage independence by attenuating oxidative injury. In hypoxia, CYGB overexpression decreased cell viability, augmented migration and anchorage independence in a cell-type-specific manner. In conclusion, CYGB revealed TSG properties in normoxia but promoted tumourigenic potential of the cells exposed to stress, suggesting a bimodal function in lung tumourigenesis, depending on cell type and microenvironmental conditions.
Daskoulidou N, Zeng B, Berglund LM, Jiang H, Chen GL, Kotova O, Bhandari S, Ayoola J, Griffin S, Atkin SL, Gomez MF, Xu SZ (2014) High glucose enhances store-operated calcium entry by upregulating ORAI/STIM via calcineurin-NFAT signalling., J Mol Med (Berl)93(5)pp. 511-521
UNLABELLED: ORAI and stromal interaction molecule (STIM) are store-operated channel molecules that play essential roles in human physiology through a coupling mechanism of internal Ca(2+) store to Ca(2+) influx. However, the roles of ORAI and STIM in vascular endothelial cells under diabetic conditions remain unknown. Here, we investigated expression and signalling pathways of ORAI and STIM regulated by high glucose or hyperglycaemia using in vitro cell models, in vivo diabetic mice and tissues from patients. We found that ORAI1-3 and STIM1-2 were ubiquitously expressed in human vasculatures. Their expression was upregulated by chronic treatment with high glucose (HG, 25 mM D-glucose), which was accompanied by enhanced store-operated Ca(2+) influx in vascular endothelial cells. The increased expression was also observed in the aortae from genetically modified Akita diabetic mice (C57BL/6-Ins2(Akita)/J) and streptozocin-induced diabetic mice, and aortae from diabetic patients. HG-induced upregulation of ORAI and STIM genes was prevented by the calcineurin inhibitor cyclosporin A and NFATc3 siRNA. Additionally, in vivo treatment with the nuclear factor of activated T cells (NFAT) inhibitor A-285222 prevented the gene upregulation in Akita mice. However, HG had no direct effects on ORAI1-3 currents and the channel activation process through cytosolic STIM1 movement in the cells co-expressing STIM1-EYFP/ORAIs. We concluded that upregulation of STIM/ORAI through Ca(2+)-calcineurin-NFAT pathway is a novel mechanism causing abnormal Ca(2+) homeostasis and endothelial dysfunction under hyperglycaemia. KEY MESSAGE: ORAI1-3 and STIM1-2 are ubiquitously expressed in vasculatures and upregulated by high glucose. Increased expression is confirmed in Akita (Ins2(Akita)/J) and STZ diabetic mice and patients. Upregulation mechanism is mediated by Ca(2+)/calcineurin/NFATc3 signalling. High glucose has no direct effects on ORAI1-3 channel activity and channel activation process.
Oleksiewicz U, Daskoulidou N, Liloglou T, Tasopoulou K, Bryan J, Gosney JR, Field JK, Xinarianos G (2011) Neuroglobin and myoglobin in non-small cell lung cancer: expression, regulation and prognosis., Lung Cancer74(3)pp. 411-418
Globins are respiratory proteins involved in oxygen metabolism, which is a critical factor in tumor growth and progression. The status of neuroglobin and myoglobin is largely unknown in human malignancies, including lung cancer. The aim of this study was to explore mRNA expression profiles, potential regulatory mechanisms and clinicopathological associations of neuroglobin and myoglobin in non-small cell lung cancer (NSCLC). We screened 208 surgically resected NSCLC specimens and a panel of lung normal and cancer cell lines. The mRNA expression of neuroglobin, myoglobin and hypoxia markers (HIF1± and VEGFa) was measured with qRTPCR, while neuroglobin promoter methylation was assessed with Pyrosequencing. Neuroglobin and myoglobin were upregulated in the tumor samples compared to normal tissue (p=1.3×10(-22) and p=1.9×10(-9), respectively). Neuroglobin was more frequently overexpressed in squamous cell carcinomas (SqCCL) than adenocarcinomas. Overexpression of myoglobin was more profound in adenocarcinomas, which correlated with poor survival (p=0.013). Neuroglobin promoter was hypermethylated in 30.8% of NSCLC cases, which correlated with neuroglobin mRNA downregulation. The epigenetic regulation of neuroglobin was confirmed by treating lung cell lines with 5'azadeoxycytidine and/or trichostatin A. Expression of both genes correlated with the expression of HIF1± (neuroglobin: p=3.8×10(-5), myoglobin: p=1.1×10(-11)). Myoglobin expression was also associated to that of VEGFa (p=2.1×10(-7)). Hypoxia-dependent upregulation of both globins was validated in vitro. In summary, neuroglobin and myoglobin overexpression in NSCLC is associated with histological subtype, hypoxia and, in case of neuroglobin - epigenetic regulation. Myoglobin expression may have potential significance in the prognostication of lung adenocarcinomas.
Jiang HN, Zeng B, Zhang Y, Daskoulidou N, Fan H, Qu JM, Xu SZ (2013) Involvement of TRPC channels in lung cancer cell differentiation and the correlation analysis in human non-small cell lung cancer., PLoS One8(6)
The canonical transient receptor potential (TRPC) channels are Ca(2+)-permeable cationic channels controlling the Ca(2+) influx evoked by G protein-coupled receptor activation and/or by Ca(2+) store depletion. Here we investigate the involvement of TRPCs in the cell differentiation of lung cancer. The expression of TRPCs and the correlation to cancer differentiation grade in non-small cell lung cancer (NSCLC) were analyzed by real-time PCR and immunostaining using tissue microarrays from 28 patient lung cancer samples. The association of TRPCs with cell differentiation was also investigated in the lung cancer cell line A549 by PCR and Western blotting. The channel activity was monitored by Ca(2+) imaging and patch recording after treatment with all-trans-retinoic acid (ATRA). The expression of TRPC1, 3, 4 and 6 was correlated to the differentiation grade of NSCLC in patients, but there was no correlation to age, sex, smoking history and lung cancer cell type. ATRA upregulated TRPC3, TRPC4 and TRPC6 expression and enhanced Ca(2+) influx in A549 cells, however, ATRA showed no direct effect on TRPC channels. Inhibition of TRPC channels by pore-blocking antibodies decreased the cell mitosis, which was counteracted by chronic treatment with ATRA. Blockade of TRPC channels inhibited A549 cell proliferation, while overexpression of TRPCs increased the proliferation. We conclude that TRPC expression correlates to lung cancer differentiation. TRPCs mediate the pharmacological effect of ATRA and play important roles in regulating lung cancer cell differentiation and proliferation, which gives a new understanding of lung cancer biology and potential anti-cancer therapy.
Daskoulidou N, Zeng B, Berglund LM, Jiang H, Chen GL, Kotova O, Bhandari S, Ayoola J, Griffin S, Atkin SL, Gomez MF, Xu SZ (2015) High glucose enhances store-operated calcium entry by upregulating ORAI/STIM via calcineurin-NFAT signalling, Journal of Molecular Medicine93(5)pp. 511-521
© 2014, Springer-Verlag Berlin Heidelberg.Abstract: ORAI and stromal interaction molecule (STIM) are store-operated channel molecules that play essential roles in human physiology through a coupling mechanism of internal Ca2+ store to Ca2+ influx. However, the roles of ORAI and STIM in vascular endothelial cells under diabetic conditions remain unknown. Here, we investigated expression and signalling pathways of ORAI and STIM regulated by high glucose or hyperglycaemia using in vitro cell models, in vivo diabetic mice and tissues from patients. We found that ORAI1-3 and STIM1-2 were ubiquitously expressed in human vasculatures. Their expression was upregulated by chronic treatment with high glucose (HG, 25 mM d-glucose), which was accompanied by enhanced store-operated Ca2+ influx in vascular endothelial cells. The increased expression was also observed in the aortae from genetically modified Akita diabetic mice (C57BL/6-Ins2Akita/J) and streptozocin-induced diabetic mice, and aortae from diabetic patients. HG-induced upregulation of ORAI and STIM genes was prevented by the calcineurin inhibitor cyclosporin A and NFATc3 siRNA. Additionally, in vivo treatment with the nuclear factor of activated T cells (NFAT) inhibitor A-285222 prevented the gene upregulation in Akita mice. However, HG had no direct effects on ORAI1-3 currents and the channel activation process through cytosolic STIM1 movement in the cells co-expressing STIM1-EYFP/ORAIs. We concluded that upregulation of STIM/ORAI through Ca2+-calcineurin-NFAT pathway is a novel mechanism causing abnormal Ca2+ homeostasis and endothelial dysfunction under hyperglycaemia. Key message: ORAI1-3 and STIM1-2 are ubiquitously expressed in vasculatures and upregulated by high glucose.Increased expression is confirmed in Akita (Ins2Akita/J) and STZ diabetic mice and patients.Upregulation mechanism is mediated by Ca2+/calcineurin/NFATc3 signalling.High glucose has no direct effects on ORAI1-3 channel activity and channel activation process.
Xu SZ, Zeng B, Daskoulidou N, Chen GL, Atkin SL, Lukhele B (2012) Activation of TRPC cationic channels by mercurial compounds confers the cytotoxicity of mercury exposure., Toxicol Sci125(1)pp. 56-68
Mercury is an established worldwide environmental pollutant with well-known toxicity affecting neurodevelopment in humans, but the molecular basis of cytotoxicity and the detoxification procedure are still unclear. Here we examined the involvement of the canonical transient receptor potential (TRPC) channel in the mercury-induced cytotoxicity and the potential detoxification strategy. Whole-cell and excised patches, Ca(2+) imaging, and site-directed mutagenesis were used to determine the mechanism of action of mercurial compounds on TRPC channels overexpressed in HEK293 cells, and cytotoxicity and preventive effect were investigated in cell culture models using small interfering RNA and pharmacological blockers. Mercury potently activates TRPC4 and TRPC5 channels. The extracellular cysteine residues (C(553) and C(558)) near the channel pore region of TRPC5 are the molecular targets for channel activation by mercury. The sensitivity of mercury to TRPC5 is presumed to be specific because other divalent heavy metal pollutants, such as Cd(2+), Ni(2+), and Zn(2+), had no stimulating effect, and TRPC3, TRPC6, TRPV1, and TRPM2 were resistant to mercurial compounds. The channel activity of TRPC5, as well as TRPC4, induced by mercury, was prevented by 2-aminoethoxydiphenyl borate and modified by a reducing environment. The inhibition of TRPC5 channels by specific TRPC5 pore-blocking antibody or by SKF-96365 alleviated the cytotoxicity, whereas the mercury chelator, meso-2,3-dimercaptosuccinic acid, showed nonselective prevention of cell survival. Silencing of the TRPC5 gene reduced the mercury-induced neuronal damage. These results indicate that mercurial compounds are activators for TRPC5 and TRPC4 channels. Blockade of TRPC channels could be a novel strategy for preventing mercury-induced cytotoxicity and neurodevelopment impairment.