Biofilm and Cancer: Interactions and Future Directions for Cancer Therapy.

There is a growing body of evidence supporting the significant role of bacterial biofilms in the pathogenesis of various human diseases, including cancer. Biofilms are polymicrobial communities enclosed within an extracellular matrix composed of polysaccharides, proteins, extracellular DNA, and lipids. This complex matrix provides protection against antibiotics and host immune responses, enabling the microorganisms to establish persistent infections. Moreover, biofilms induce anti-inflammatory responses and metabolic changes in the host, further facilitating their survival. Many of these changes are comparable to those observed in cancer cells. This review will cover recent research on the role of bacterial biofilms in carcinogenesis, especially in colorectal (CRC) and gastric cancers, emphasizing the shared physical and chemical characteristics of biofilms and cancer. This review will also discuss the interactions between bacteria and the tumor microenvironment, which can facilitate oncogene expression and cancer progression. This information will provide insight into developing new therapies to identify and treat biofilm-associated cancers, such as utilizing bacteria as delivery vectors, using bacteria to upregulate immune function, or more selectively targeting biofilms and cancer for their shared traits.

Anti-biofilm activity of Pseudomonas fluorescens culture supernatants on biofilm formation of Staphylococcus epidermidis 1457.

OBJECTIVE: Staphylococcus epidermidis is a skin colonizer and a major cause of nosocomial infections that can lead to sepsis. It causes opportunistic infections by forming biofilms on medical devices, which are hard to control with conventional antibiotics. In an attempt to develop its biofilm inhibitors, the culture supernatant (CS) of Pseudomonas fluorescens was assessed. This study examined the effect of the CS on S. epidermidis 1457 biofilm formation, the characteristics of inhibitors in the CS, and the differential gene expression of S. epidermidis when treated with the CS. RESULTS: P. fluorescens CS specifically targeted the maturation stage of S. epidermidis biofilm formation while not affecting planktonic growth. RT-qPCR analysis revealed that P. fluorescens CS significantly downregulated S. epidermidis ica genes and upregulated an ica repressor, tcaR. This indicates that the CS reduced polysaccharide intercellular adhesin synthesis, a major component of the S. epidermidis 1457 biofilm matrix. Further studies are required to elucidate the specific inhibitory components in the CS and their mechanism of action. Our results indicate that inhibitors in the P. fluorescens CS may have a significant value for inhibiting S. epidermidis biofilm. Combinations of specific inhibitors from the CS and antibiotics against staphylococci may provide an effective measure to control S. epidermidis biofilm formation while avoiding antibiotic resistance and compensating the attenuated effectiveness of antibiotics on biofilms.

Dual Function of Secreted APE1/Ref-1 in TNBC Tumorigenesis: An Apoptotic Initiator and a Regulator of Chronic Inflammatory Signaling.

The simultaneous regulation of cancer cells and inflammatory immune cells in the tumor microenvironment (TME) can be an effective strategy in treating aggressive breast cancer types, such as triple-negative breast cancer (TNBC). Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) is a multi-functional nuclear protein that can be stimulated and then secreted. The extracellular APE1/Ref-1 causes a reduction in disulfide bonds in cytokine receptors, resulting in their conformational changes, thereby inhibiting inflammatory signaling. Furthermore, the secreted APE1/Ref-1 in response to acetylation has been shown to bind to a receptor for the advanced glycation end product (RAGE), initiating the apoptotic cell death of TNBC in vitro and in vivo. This study used PPTLS-APE1/Ref-1 in an adenovirus vector (Ad-PPTLS-APE1/Ref-1) for the constant expression of extracellular APE1/Ref-1, and our results demonstrated its dual function as an apoptotic initiator and inflammation regulator. Injecting MDA-MB 231 orthotopic xenografts with the Ad-PPTLS-APE1/Ref-1 inhibited tumor growth and development in response to acetylation. Moreover, Ad-PPTLS-APE1/Ref-1 generated reactive oxygen species (ROS), and tumor tissues derived from these xenografts exhibited apoptotic bodies. Compared to normal mice, a comparable ratio of anti- and pro-inflammatory cytokines was observed in the plasma of Ad-PPTLS-APE1/Ref-1-injected mice. Mechanistically, the disturbed cytokine receptor by reducing activity of PPTLS-APE1/Ref-1 inhibited inflammatory signaling leading to the inactivation of the p21-activated kinase 1-mediated signal transducer and activator of transcription 3/nuclear factor-κB axis in tumor tissues. These results suggest that the regulation of inflammatory signaling with adenoviral-mediated PPTLS-APE1/Ref-1 in tumors modulates the secretion of pro-inflammatory cytokines in TME, thereby inhibiting aggressive cancer cell progression, and could be considered as a promising and safe therapeutic strategy for treating TNBCs.

Salicornia herbacea Aqueous Extracts Regulate NLRP3 Inflammasome Activation in Macrophages and Trophoblasts.

Salicornia herbacea L. (Chenopodiaceae), an edible salt marsh plant with anti-inflammatory effects, was examined in macrophages and trophoblasts whether it modulates NLRP3 inflammasome activity. Pretreatment and delayed treatment of S. herbacea extract (SHE) in bone marrow-derived macrophages (BMDMs) reduced the activity of NLRP3 inflammasome induced by lipopolysaccharide (LPS) and adenosine triphosphate stimulation and downregulated interleukin (IL)-1ß production. SHE also inhibited pyroptotic cell death, the adaptor molecule apoptosis-associated speck-like protein containing a CARD (ASC), oligomerization, and speck by NLRP3 inflammasome activity in BMDM. Similarly, SHE decreased the mRNA expression of NLRP3, ASC, IL-1ß, and IL-6 in the LPS-stimulated human trophoblast cell line, Swan 71 cells. In addition, SHE inhibited the production of IL-6 and IL-1ß and decreased the expression of cyclooxygenase-2 and prostaglandin E2 in stimulated Swan 71 cells. Finally, 3,5-dicaffeoylquinic acid (3,5-DCQA), one of the components of S. herbacea, inhibited IL-1ß produced by NLRP3 inflammasome activity. In conclusion, SHE downregulated the activity of the NLRP3 inflammasome in macrophages and trophoblasts.

ATP Binding Cassette Transporter A1 is Involved in Extracellular Secretion of Acetylated APE1/Ref-1.

Acetylation of nuclear apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE1/Ref-1) is associated with its extracellular secretion, despite the lack of an N-terminal protein secretion signal. In this study, we investigated plasma membrane targeting and translocation of APE1/Ref-1 in HEK293T cells with enhanced acetylation. While APE1/Ref-1 targeting was not affected by inhibition of the endoplasmic reticulum/Golgi-dependent secretion, its secretion was reduced by inhibitors of ATP-binding cassette (ABC) transporters, and siRNA-mediated down-regulation of ABC transporter A1. The association between APE1/Ref-1 and ABCA1 transporter was confirmed by proximal ligation assay and immunoprecipitation experiments. An APE1/Ref-1 construct with mutated acetylation sites (K6/K7R) showed reduced co-localization with ABC transporter A1. Exposure of trichostatin A (TSA) induced the acetylation of APE1/Ref-1, which translocated into membrane fraction. Taken together, acetylation of APE1/Ref-1 is considered to be necessary for its extracellular targeting via non-classical secretory pathway using the ABCA1 transporter.

The extracellular role of Ref-1 as anti-inflammatory function in lipopolysaccharide-induced septic mice.

Apurinic/apyrimidinic endonuclease/redox factor-1 (Ref-1), a multifunctional protein secreted from stimulated cells, has been identified as a new serological biomarker. Despite recent reports on the role of Ref-1 in inflammation, the biological function of secreted Ref-1 remains unknown, especially in vivo. This study aimed to evaluate the possible roles of secreted Ref-1 in lipopolysaccharide-induced systemic inflammation in vivo. We generated a secretory Ref-1 adenoviral vector system, AdPPT-LS-Ref-1, by conjugation of preprotrypsin leading sequence (PPT-LS) with full-length Ref-1 sequences. Expression of tumor necrosis factor-α (TNF-α)-induced vascular cell adhesion molecule-1 (VCAM-1) in endothelial cells and lipopolysaccharide (LPS)-induced cyclooxygenase-2 in Raw264.7 cells was inhibited by secretory Ref-1, and this inhibitory effect was abrogated following neutralization of Ref-1 with anti-Ref-1 antibody. Plasma Ref-1 levels following administration of AdPPT-LS-Ref-1 (2 × 109 ifu, i.p.) for 24 h were substantially higher than those recorded following administration of Adßgal (84.6 ±â€¯7.2 ng/ml vs. 4.4 ±â€¯1.5 ng/ml). Treatment with LPS (10 mg/kg, i.v. for 6 h) markedly increased VCAM-1 expression, cathepsin or myeloperoxidase activity, which were significantly suppressed by treatment with AdPPT-LS-Ref-1. Furthermore, LPS-induced cytokines, such as TNF-α, interleukin (IL)-1ß, IL-6, and monocyte chemoattractant protein 1, were significantly inhibited in AdPPT-LS-Ref-1-treated mice. However, LPS-induced myeloperoxidase activities were not suppressed by treatment with the redox mutant of secretory Ref-1, AdPPT-LS-Ref-1(C65A/C93A), or wild-type AdRef-1. Collectively, these results suggest that secreted Ref-1 has anti-inflammatory properties and that its redox cysteine residue is associated with the anti-inflammatory activity in vivo. Furthermore, our findings indicate that secretory Ref-1 may be useful as a therapeutic biomolecule against systemic inflammation.

Therapeutic positioning of secretory acetylated APE1/Ref-1 requirement for suppression of tumor growth in triple-negative breast cancer in vivo.

Triple-negative breast cancer (TNBC) represents a relatively small proportion of all BCs but a relatively large proportion of BC-related death. Thus, more effective therapeutic strategies are needed for the management of TNBC. We demonstrated that the stimulation of apoptosis by the binding of secreted acetylated-apurinic apyrimidinic endonuclease 1/redox factor-1 (Ac-APE1/Ref-1) to the receptor for advanced glycation end products (RAGE) was essential for TNBC cell death in response to hyperacetylation. The aim of the present study was to assess the potential therapeutic efficacy of secretory Ac-APE1/Ref-1 in orthotopic TNBC xenografts in vivo. We found that hyperacetylation in xenografts caused secretion of Ac-APE1/Ref-1 into the blood, where the factor bound directly to RAGE in hyperacetylated tumor tissues. Hyperacetylation in the TNBC xenografts induced strong inhibition of tumor growth and development, leading to apoptotic cell death, accompanied by increased RAGE expression and generation of reactive oxygen species. Tissues exhibited markedly higher counts of apoptotic bodies, a reduced proliferation index, and reduced neovascularization compared with control tumors. Ac-APE1/Ref-1-stimulated apoptosis was markedly reduced in RAGE-knockdown tumors compared with RAGE-overexpressing tumors, even in the presence of hyperacetylation. The function of secreted Ac-APE1/Ref-1 was confirmed in other hyperacetylated TNBCs xenografts using BT-549 and MDA-MB-468 cells, demonstrating its relevance as an anti-cancer molecule.

Anthocyanin-Rich Extract from Red Chinese Cabbage Alleviates Vascular Inflammation in Endothelial Cells and Apo E-/- Mice.

Anthocyanins, the most prevalent flavonoids in red/purple fruits and vegetables, are known to improve immune responses and reduce chronic disease risks. In this study, the anti-inflammatory activities of an anthocyanin-rich extract from red Chinese cabbage (ArCC) were shown based on its inhibitory effects in cultured endothelial cells and hyperlipidemic apolipoprotein E-deficient mice. ArCC treatment suppressed monocyte adhesion to tumor necrosis factor-α-stimulated endothelial cells. This was validated by ArCC's ability to downregulate the expression and transcription of endothelial adhesion molecules, determined by immunoblot and luciferase promoter assays, respectively. The regulation of adhesion molecules was accompanied by transcriptional inhibition of nuclear factor-κB, which restricted cytoplasmic localization as shown by immunocytochemistry. Administration of ArCC (150 or 300 mg/kg/day) inhibited aortic inflammation in hyperlipidemic apolipoprotein E-deficient mice, as shown by in vivo imaging. Immunohistochemistry and plasma analysis showed that the aortas from these mice exhibited markedly lower leukocyte infiltration, reduced plaque formation, and lower concentrations of blood inflammatory cytokines than those observed in the control mice. The results suggest that the consumption of anthocyanin-rich red Chinese cabbage is closely correlated with lowering the risk of vascular inflammatory diseases.

APE1/Ref-1 Inhibits Phosphate-Induced Calcification and Osteoblastic Phenotype Changes in Vascular Smooth Muscle Cells.

Vascular calcification plays a role in the pathogenesis of atherosclerosis, diabetes, and chronic kidney disease; however, the role of apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) in inorganic phosphate (Pi)-induced vascular smooth muscle cell (VSMC) calcification remains unknown. In this study, we investigated the possible role of APE1/Ref-1 in Pi-induced VSMC calcification. We observed that Pi decreased endogenous APE1/Ref-1 expression and promoter activity in VSMCs, and that adenoviral overexpression of APE1/Ref-1 inhibited Pi-induced calcification in VSMCs and in an ex vivo organ culture of a rat aorta. However, a redox mutant of APE1/Ref-1(C65A/C93A) did not reduce Pi-induced calcification in VSMCs, suggesting APE1/Ref-1-mediated redox function against vascular calcification. Additionally, APE1/Ref-1 overexpression inhibited Pi-induced intracellular and mitochondrial reactive oxygen species production, and APE1/Ref-1 overexpression resulted in decreased Pi-induced lactate dehydrogenase activity, pro-apoptotic Bax levels, and increased anti-apoptotic Bcl-2 protein levels. Furthermore, APE1/Ref-1 inhibited Pi-induced osteoblastic differentiation associated with alkaline phosphatase activity and inhibited Pi-exposure-induced loss of the smooth muscle phenotype. Our findings provided valuable insights into the redox function of APE1/Ref-1 in preventing Pi-induced VSMC calcification by inhibiting oxidative stress and osteoblastic differentiation, resulting in prevention of altered osteoblastic phenotypes in VSMCs.

Protein kinase C beta II upregulates intercellular adhesion molecule-1 via mitochondrial activation in cultured endothelial cells.

Activation of protein kinase C (PKC) is closely linked with endothelial dysfunction. However, the effect of PKCßII on endothelial dysfunction has not been characterized in cultured endothelial cells. Here, using adenoviral PKCßII gene transfer and pharmacological inhibitors, the role of PKCßII on endothelial dysfucntion was investigated in cultured endothelial cells. Phorbol 12-myristate 13-acetate (PMA) increased reactive oxygen species (ROS), p66shc phosphorylation, intracellular adhesion molecule-1, and monocyte adhesion, which were inhibited by PKCßi (10 nM), a selective inhibitor of PKCßII. PMA increased the phosphorylation of CREB and manganese superoxide dismutase (MnSOD), which were also inhibited by PKCßi. Gene silencing of CREB inhibited PMA-induced MnSOD expression, suggesting that CREB plays a key role in MnSOD expression. Gene silencing of PKCßII inhibited PMA-induced mitochondrial ROS, MnSOD, and ICAM-1 expression. In contrast, overexpression of PKCßII using adenoviral PKCßII increased mitochondrial ROS, MnSOD, ICAM-1, and p66shc phosphorylation in cultured endothelial cells. Finally, PKCßII-induced ICAM-1 expression was inhibited by Mito-TEMPO, a mitochondrial ROS scavenger, suggesting the involvement of mitochondrial ROS in PKC-induced vascular inflammation. Taken together, the results suggest that PKCßII plays an important role in PMA-induced endothelial dysfunction, and that the inhibition of PKCßII-dependent p66shc signaling acts as a therapeutic target for vascular inflammatory diseases.

Ethanol Extract of Brassica rapa ssp. pekinensis Suppresses Tumor Necrosis Factor-α-Induced Inflammatory Response in Human Umbilical Vein Endothelial Cells.

Brassica rapa L. ssp. pekinensis, commonly known as Chinese cabbage, is a cruciferous vegetable traditionally consumed in east Asia. Although its habitual consumption could account for the low incidence of chronic vascular inflammation, the therapeutic and protective potential of phytochemicals derived from Chinese cabbage has been poorly studied. In this study, we identified the phenolic compounds, kaempferol and quercetin, from the ethanol extract of Chinese cabbage (EtCC). We show for the first time that EtCC contains effective phytochemicals that suppress tumor necrosis factor (TNF)-α-induced inflammatory response in human umbilical vein endothelial cells. The EtCC inhibited TNF-α-induced monocyte adhesion to endothelial cells in a dose-dependent manner. The antiadhesive activity of EtCC directly correlated with downregulation of expression and transcription of vascular cell adhesion molecule-1 (VCAM-1). It was caused by an Nrf-2-dependent mechanism, leading to activation of antioxidant responsive element-driven promoter. Taken together, these results suggest that EtCC inhibits the expression of TNF-α-induced adhesion molecules through the indirect transcriptional modulation of VCAM-1 in endothelial cells. In conclusion, regular consumption of vegetables containing dietary phytochemicals might be a potential therapeutic strategy to protect against various stresses, to prevent several pathological conditions, and to treat chronic vascular inflammation, such as atherosclerosis.

Altered Secretory Activity of APE1/Ref-1 D148E Variants Identified in Human Patients With Bladder Cancer.

PURPOSE: Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein involved in DNA repair and redox modulation. Recently, serum and urinary APE1/Ref-1 levels were reported to be increased in patients with bladder cancer. Genetic variations of APE/Ref-1 are associated with the risk of cancer. However, the effect of APE1/Ref-1 variants on its secretory activity is yet unknown. METHODS: APE1/Ref-1 variants were evaluated by DNA sequencing analysis of reverse transcription polymerase chain reaction products in coding DNA sequences (CDS) of APE1/Ref-1 in bladder tissue samples from patients with bladder cancer (n=10). Secretory activity of APE1/Ref-1 variants was evaluated with immunoblot and enzyme-linked immunosorbent assay of the culture medium supernatants. RESULTS: Four different substitution mutants (D148E, I64V/D148E, W67R/D148E, and E86G/D148E) of APE1/Ref-1 were identified in bladder cancer specimens. However, deletion mutants of APE1/Ref-1 CDS were not found. The secretory activity of the APE1/Ref-1 variants (D148E, I64V/D148E, and E86G/D148E) was increased compared to that of wild type APE1/Ref-1. Furthermore, the secretory activity in basal or hyperacetylated conditions was much higher than that in APE1/Ref-1 D148E-transfected HEK293 cells. CONCLUSIONS: Taken together, our data suggest that the increased secretory activity of D148E might contribute to increased serum levels of APE1/Ref-1 in patients with bladder cancer.

Dynamic Regulation of APE1/Ref-1 as a Therapeutic Target Protein.

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein that plays a central role in the cellular response to DNA damage and redox regulation against oxidative stress. APE1/Ref-1 functions in the DNA base excision repair pathway, the redox regulation of several transcription factors, and the control of intracellular redox status through the inhibition of reactive oxygen species (ROS) production. APE1/Ref-1 is predominantly localized in the nucleus; however, its subcellular localization is dynamically regulated and it may be found in the mitochondria or elsewhere in the cytoplasm. Studies have identified a nuclear localization signal and a mitochondrial target sequence in APE1/Ref-1, as well as the involvement of the nuclear export system, as determinants of APE1/Ref-1 subcellular distribution. Recently, it was shown that APE1/Ref-1 is secreted in response to hyperacetylation at specific lysine residues. Additionally, post-translational modifications such as phosphorylation, S-nitrosation, and ubiquitination appear to play a role in fine-tuning the activities and subcellular localization of APE1/Ref-1. In this review, we will introduce the multifunctional role of APE1/Ref-1 and its potential usefulness as a therapeutic target in cancer and cardiovascular disease.

Urinary APE1/Ref-1: A Potential Bladder Cancer Biomarker.

Bladder cancer (BCa) is one of the most common urothelial cancers with still noticeable incidence rate. Early detection of BCa is highly correlated with successful therapeutic outcomes. We previously showed that apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) was expressed at an increased level in the serum of BCa patients when compared to the level in healthy controls. In this study, we investigated whether urinary APE1/Ref-1 was also elevated in patients with BCa. In this case-control study, voided urine was collected from 277 subjects including 169 BCa patients and 108 non-BCa controls. Urinary APE1/Ref-1 level was assessed by enzyme-linked immunosorbent assay (ELISA). APE1/Ref-1 levels were significantly elevated in BCa patients relative to levels in non-BCa controls and were correlated with tumor grade and stage. Urinary APE1/Ref-1 levels were also higher in patients with recurrence history of BCa. The receiver operating characteristics (ROC) curve of APE1/Ref-1 showed an area under the curve of 0.83, indicating the reliability and validity of this biomarker. The optimal combination of sensitivity and specificity was determined to be 82% and 80% at a cut-off value of 0.376 ng/100 µL for detection of APE1/Ref-1 in urine. In conclusion, urinary APE1/Ref-1 levels measured from noninvasively obtained body fluids would be clinically applicable for diagnosis of BCa.

Secreted APE1/Ref-1 inhibits TNF-α-stimulated endothelial inflammation via thiol-disulfide exchange in TNF receptor.

Apurinic apyrimidinic endonuclease 1/Redox factor-1 (APE1/Ref-1) is a multifunctional protein with redox activity and is proved to be secreted from stimulated cells. The aim of this study was to evaluate the functions of extracellular APE1/Ref-1 with respect to leading anti-inflammatory signaling in TNF-α-stimulated endothelial cells in response to acetylation. Treatment of TNF-α-stimulated endothelial cells with an inhibitor of deacetylase that causes intracellular acetylation, considerably suppressed vascular cell adhesion molecule-1 (VCAM-1). During TSA-mediated acetylation in culture, a time-dependent increase in secreted APE1/Ref-1 was confirmed. The acetyl moiety of acetylated-APE1/Ref-1 was rapidly removed based on the removal kinetics. Additionally, recombinant human (rh) APE1/Ref-1 with reducing activity induced a conformational change in rh TNF-α receptor 1 (TNFR1) by thiol-disulfide exchange. Following treatment with the neutralizing anti-APE1/Ref-1 antibody, inflammatory signals via the binding of TNF-α to TNFR1 were remarkably recovered, leading to up-regulation of reactive oxygen species generation and VCAM-1, in accordance with the activation of p66(shc) and p38 MAPK. These results strongly indicate that anti-inflammatory effects in TNF-α-stimulated endothelial cells by acetylation are tightly linked to secreted APE1/Ref-1, which inhibits TNF-α binding to TNFR1 by reductive conformational change, with suggestion as an endogenous inhibitor of vascular inflammation.

Ulmus davidiana ethanol extract inhibits monocyte adhesion to tumor necrosis factor-alpha-stimulated endothelial cells.

BACKGROUND: Ulmus davidiana var. japonica Rehder (UD) has long been used in traditional folk medicine in Asia. This study is designed to investigate the antiadhesive activity of the ethanol extract of UD (UDE) and its underlying mechanisms in cultured endothelial cells. METHODS: The dried root bark of UD was extracted with 80% (v/v) ethanol. The antiadhesive activity of the UDE was investigated in cultured human umbilical vein endothelial cells and human embryonic kidney epithelial 293T (HEK 293T) cells stably transfected with pGL3-vascular cell adhesion molecule (VCAM)-1-luc. Monocyte adhesion in endothelial cells was induced by tumor necrosis factor-alpha (TNF-α), and the protective effects of UDE on monocyte-endothelial cell adhesion, VCAM-1 expression, reactive oxygen species production, and nuclear factor-κB activity were determined. RESULTS: Exposure to UDE at a concentration of 3-30 µg/mL for 24 hours produced no detectable cytotoxicity in human umbilical vein endothelial cells, but it significantly inhibited TNF-α-induced monocyte adhesion and VCAM-1 expression. TNF-α treatment of HEK 293T/VCAM-1-luc cells resulted in increased luciferase activity of the VCAM-1 promoter, which was inhibited by treatment with UDE. Additionally, TNF-α-induced reactive oxygen species generation, nuclear translocation of nuclear factor-κB, and IκBα degradation in human umbilical vein endothelial cells were effectively reduced by treatment with 30 µg/mL of UDE. CONCLUSION: Our results indicated that UDE treatment inhibited TNF-α-induced monocyte adhesion in endothelial cells, suggesting that UD may reduce vascular endothelial inflammation.

The 18-kDa Translocator Protein Inhibits Vascular Cell Adhesion Molecule-1 Expression via Inhibition of Mitochondrial Reactive Oxygen Species.

Translocator protein 18 kDa (TSPO) is a mitochondrial outer membrane protein and is abundantly expressed in a variety of organ and tissues. To date, the functional role of TSPO on vascular endothelial cell activation has yet to be fully elucidated. In the present study, the phorbol 12-myristate 13-acetate (PMA, 250 nM), an activator of protein kinase C (PKC), was used to induce vascular endothelial activation. Adenoviral TSPO overexpression (10-100 MOI) inhibited PMA-induced vascular cell adhesion molecule-1 (VCAM-1) and intracellular cell adhesion molecule-1 (ICAM-1) expression in a dose dependent manner. PMA-induced VCAM-1 expressions were inhibited by Mito-TEMPO (0.1-0.5 µM), a specific mitochondrial antioxidants, and cyclosporin A (1-5 µM), a mitochondrial permeability transition pore inhibitor, implying on an important role of mitochondrial reactive oxygen species (ROS) on the endothelial activation. Moreover, adenoviral TSPO overexpression inhibited mitochondrial ROS production and manganese superoxide dismutase expression. On contrasts, gene silencing of TSPO with siRNA increased PMA-induced VCAM-1 expression and mitochondrial ROS production. Midazolam (1-50 µM), TSPO ligands, inhibited PMA-induced VCAM-1 and mitochondrial ROS production in endothelial cells. These results suggest that mitochondrial TSPO can inhibit PMA-induced endothelial inflammation via suppression of VCAM-1 and mitochondrial ROS production in endothelial cells.

Trichostatin A Modulates Angiotensin II-induced Vasoconstriction and Blood Pressure Via Inhibition of p66shc Activation.

Histone deacetylase (HDAC) has been recognized as a potentially useful therapeutic target for cardiovascular disorders. However, the effect of the HDAC inhibitor, trichostatin A (TSA), on vasoreactivity and hypertension remains unknown. We performed aortic coarctation at the inter-renal level in rats in order to create a hypertensive rat model. Hypertension induced by abdominal aortic coarctation was significantly suppressed by chronic treatment with TSA (0.5 mg/kg/day for 7 days). Nicotinamide adenine dinucleotide phosphate-driven reactive oxygen species production was also reduced in the aortas of TSA-treated aortic coarctation rats. The vasoconstriction induced by angiotensin II (Ang II, 100 nM) was inhibited by TSA in both endothelium-intact and endothelium-denuded rat aortas, suggesting that TSA has mainly acted in vascular smooth muscle cells (VSMCs). In cultured rat aortic VSMCs, Ang II increased p66shc phosphorylation, which was inhibited by the Ang II receptor type I (AT1R) inhibitor, valsartan (10 µM), but not by the AT2R inhibitor, PD123319. TSA (1~10 µM) inhibited Ang II-induced p66shc phosphorylation in VSMCs and in HEK293T cells expressing AT1R. Taken together, these results suggest that TSA treatment inhibited vasoconstriction and hypertension via inhibition of Ang II-induced phosphorylation of p66shc through AT1R.

Elevation of the Serum Apurinic/Apyrimidinic Endonuclease 1/Redox Factor-1 in Coronary Artery Disease.

BACKGROUND AND OBJECTIVES: Apurinic/apyrimidinic endonuclease 1/redox effector factor-1 (APE1/Ref-1) is a multifunctional protein involved in the DNA base excision repair pathway, inflammation, angiogenesis, and survival pathways. We investigated serum APE1/Ref-1 in patients with coronary artery disease (CAD). SUBJECTS AND METHODS: Serum APE1/Ref-1 was measured with a sandwich enzyme-linked immunosorbent assay from 360 patients who received coronary angiograms. They were divided into two groups; a control (n=57) and a CAD group (n=303), the latter included angina (n=128) and myocardial infarction (MI, n=175). RESULTS: The levels of APE1/Ref-1 were higher in the CAD than the control (0.63±0.07 vs. 0.12±0.07 ng/100 µL, respectively; p<0.01). They were also higher in MI than angina (0.81±0.10 vs. 0.38±0.11 ng/100 µL, respectively; p<0.01) and different according to the thrombolysis in myocardial infarction (TIMI) flow (0.88±0.09 for TIMI flow 0, 1, 2 vs. 0.45±0.13 ng/100 µL for TIMI flow 3, p<0.01) in acute coronary syndrome. In correlation analysis, the levels of APE1/Ref-1 were positively correlated with Troponin I (r=0.222; p<0.0001) and N-terminal pro-B type natriuretic peptide (NT-proBNP, r=0.217; p<0.0001) but not high sensitivity to C-reactive protein. Also, they revealed a negative correlation with ejection fraction (EF, r=-0.221; p=0.002). However, there were no significant differences among the three groups, were divided by their levels of APE1/Ref-1, for major adverse cardiovascular events (death, recurrent MI, stroke, revascularization) (8.2 vs. 14.0 vs. 12.5%, p=ns). CONCLUSION: The levels of serum APE1/Ref-1 are elevated in CAD, and are higher in MI than in angina. They are correlated with Troponin I, NT-proBNP, and EF.

Extracellularly secreted APE1/Ref-1 triggers apoptosis in triple-negative breast cancer cells via RAGE binding, which is mediated through acetylation.

The present study evaluated the mechanism of apoptosis caused by post-translational modification, hyperacetylation in triple-negative breast cancer (TNBC) cells. We previously showed that trichostatin A (TSA) induced secretion of acetylated apurinic apyrimidinic endonuclease 1/redox factor-1 (Ac-APE1/Ref-1). This is the first report showing that Ac-APE1/Ref-1 initiates apoptosis in TNBC cells by binding to the receptor for advanced glycation end products (RAGE). The functional significance of secreted Ac-APE1/Ref-1 was studied by induction of intracellular hyperacetylation through co-treatment with acetylsalicylic acid and TSA in MDA-MB-231 cells. In response to hyperacetylation, secretion of Ac-APE1/Ref-1 in vesicles was observed, resulting in significantly decreased cell viability and induction of apoptosis with increased expression of RAGE. The hyperacetylation-induced apoptosis was similar in two other TNBC cell lines: BT-459 and MDA-MB-468. Therefore, hyperacetylation may be a therapeutic target for treatment of TNBCs. This study introduces a novel paradigm whereby post-translational modification induces apoptotic cell death in breast cancer cells resistant to standard chemotherapeutic agents through secretion of auto- or paracrine molecules such as Ac-APE1/Ref-1.