Indoxyl sulfate upregulates expression of ICAM-1 and MCP-1 by oxidative stress-induced NF-kappaB activation

BACKGROUND/AIM

Indoxyl sulfate, a uremic toxin, is considered a risk factor for cardiovascular disease (CVD) in chronic kidney disease (CKD). The present study aimed to determine whether indoxyl sulfate increases the expression of intercellular adhesion molecule-1 (ICAM-1) and monocyte chemotactic protein-1 (MCP-1) by reactive oxygen species (ROS)-induced activation of nuclear factor-kappaB (NF-kappaB) in vascular endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVEC) were incubated with indoxyl sulfate. The expression of ICAM-1 and MCP-1 in HUVEC was analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Phospho-NF-kappaB p65 (Ser 536), an active form of the NF-kappaB subunit, was determined by Western blotting.

RESULTS

Indoxyl sulfate significantly increased the mRNA expression of ICAM-1 and MCP-1 in HUVEC in a time- and concentration-dependent manner. Inhibitors of NF-kappaB (ammonium pyrrolidinedithiocarbamate and isohelenin) and an antioxidant (N-acetyl-L-cysteine) suppressed the indoxyl sulfate-induced expression of ICAM-1 and MCP-1 in HUVEC. Indoxyl sulfate increased phospho- NF-kappaB p65 in HUVEC, and N-acetyl-L-cysteine suppressed it.

CONCLUSIONS

Indoxyl sulfate upregulates the expression of ICAM-1 and MCP-1 by ROS-induced activation of NF-kappaB in vascular endothelial cells. Thus, indoxyl sulfate may play an important role in the development of CVD in CKD by increasing the endothelial expression of ICAM-1 and MCP-1.

Indoxyl sulfate inhibits nitric oxide production and cell viability by inducing oxidative stress in vascular endothelial cells

BACKGROUND/AIM

Cardiovascular disease is a major cause of mortality in chronic kidney disease patients. Oxidative stress and nitric oxide (NO) deficiency play an important role in vascular endothelial cell dysfunction in chronic kidney disease. To determine if the uremic toxin indoxyl sulfate (IS) induces oxidative stress and inhibits NO production and cell viability in human umbilical vein endothelial cells (HUVEC).

METHODS

The production of reactive oxygen species (ROS), superoxide, NO and peroxynitrite was measured using a fluorescence microplate reader. The expression of NADPH oxidases (Nox4, Nox2) was analyzed by quantitative reverse transcription-polymerase chain reaction. Cell viability was examined by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate assay.

RESULTS

IS induced ROS generation in HUVEC. An inhibitor of NADPH oxidase showed an inhibitory effect on IS-induced ROS production. However, the inhibitors of xanthine oxidase, mitochondrial electron transport and NO synthase did not show any significant effect on IS-induced ROS production. Antioxidants such as vitamin E, N-acetyl-L-cysteine and vitamin C inhibited IS-induced ROS production. IS induced the expression of Nox4 mRNA and the production of superoxide and peroxynitrite in HUVEC. IS inhibited NO production in HUVEC. IS inhibited cell viability, and antioxidants preserve the inhibitory effect of IS on cell viability.

CONCLUSIONS

IS inhibits NO production and cell viability by inducing ROS through induction of Nox4 in HUVEC.

Periodontitis and diabetes mellitus co-morbidity: A molecular dialogue

BACKGROUND

Type 2 diabetes mellitus (T2DM) and periodontitis are two biologically linked diseases that often coexist in complex interaction. While periodontitis may lead to insulin receptor desensitization, diabetes may increase the expression of inflammatory cytokines, such as Tumor Necrosis Factor-α (TNF-α) and Interleukin 6 (IL-6), in the gingival crevicular fluid and activate osteoclasts via Receptor activator of nuclear factor kappa-Β ligand (RANK-L) production, leading to bone resorption. However, the association between the two diseases processes, where one may exacerbate the progression of the other, is unclear. In addition, both diseases have similar mechanistic themes, such as chronic inflammation and oxidative stress. This review aimed to investigate the pathophysiological and molecular mechanisms underlying T2DM and periodontitis.

HIGHLIGHT

Uncontrolled diabetes is often associated with severe periodontitis, measured by clinical attachment loss. Alteration in the oral microbiome composition, which may activate the host inflammatory response and lead to irreversible oxidative stress, is a common finding in both diseases. An understanding of the molecular crosstalk between the two disease processes is crucial for developing therapeutic targets that inhibit bone resorption and halt the progression of periodontitis in patients with diabetes.

CONCLUSION

The Oral microbiome composition in T2DM and periodontitis shifts toward dysbiosis, favoring bacterial pathogens, such as Fusobacteria and Porphyromonas species. Both conditions are marked by pro-inflammatory immune activity via the activation of Interleukin 17 (IL-17), Interleukin 1 (IL-1), TNF-α, and Nuclear Factor Kappa Beta (NF-κB). Common molecular crosstalk signaling appears to involve advanced glycation end products (AGEs) and oxidative stress. Thus, future drug targets are multifactorial, ranging from modulatory of host inflammatory response to preventing the accumulation of AGEs and oxidative free radicals.

Oral sorbent AST-120 increases renal NO synthesis in uremic rats

OBJECTIVE

The urine level of nitric oxide (NO) metabolites, i.e., nitrates/nitrites (NOx), in chronic renal failure (CRF) is decreased because of reduced renal synthesis of NO. We determined whether the administration of an oral sorbent, AST-120, increases the urine level of NOx and the renal expression of nitric oxide synthase (NOS) isoforms in CRF rats.

METHODS

Chronic renal failure rats were produced by 4/5 nephrectomy. Rats were randomized into two groups: CRF control rats, and AST-120-treated CRF rats. The AST-120 was administered to the rats at a dose of 4 g/kg with powder chow for 16 weeks, whereas powder chow alone was administered to control rats. The urine levels of NOx were measured by using a NOx colorimetric assay kit. The expression of endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) in the kidney was determined by immunohistochemistry. Serum and urine levels of indoxyl sulfate were determined by high-performance liquid chromatography.

RESULTS

Urine levels of NOx and the expression of glomerular eNOS and tubulointerstitial nNOS were significantly decreased in CRF rats compared with normal rats. The administration of AST-120 to CRF rats significantly increased urine levels of NOx and the expression of glomerular eNOS and tubulointerstitial nNOS. The administration of AST-120 to CRF rats significantly decreased urine and serum levels of indoxyl sulfate.

CONCLUSIONS

The oral sorbent AST-120 increases NO synthesis in the kidneys of uremic rats by increasing the renal expression of eNOS and nNOS, through alleviation of indoxyl sulfate overload on the kidney.

RhoC mediates epidermal growth factor-stimulated migration and invasion in head and neck squamous cell carcinoma

Epidermal growth factor receptor (EGFR) is overexpressed in head and neck squamous cell carcinoma (HNSCC) where it has been shown to promote tumor cell invasion upon phosphorylation. One mechanism by which EGFR promotes tumor progression is by activating signal cascades that lead to loss of E-cadherin, a transmembrane glycoprotein of the cell-cell adherence junctions; however mediators of these signaling cascades are not fully understood. One such mediator, RhoC, is activated upon a number of external stimuli, such as epidermal growth factor (EGF), but its role as a mediator of EGF-stimulated migration and invasion has not been elucidated in HNSCC. In the present study, we investigate the role of RhoC as a mediator of EGF-stimulated migration and invasion in HNSCC. We show that upon EGF stimulation, EGFR and RhoC were strongly activated in HNSCC. This resulted in activation of the phosphatidylinositol 3-Kinase Akt pathway (PI3K-Akt), phosphorylation of GSK-3β at the Ser⁹ residue, and subsequent down regulation of E-cadherin cell surface expression resulting in increased tumor cell invasion. Knockdown of RhoC restored E-cadherin expression and inhibited EGF-stimulated migration and invasion. This is the first report in HNSCC demonstrating the role RhoC plays in mediating EGF-stimulated migration and invasion by down-regulating the PI3K-Akt pathway and E-cadherin expression. RhoC may serve as a treatment target for HNSCC.

Rosmarinic Acid/ Blue Light Combination Treatment Inhibits Head and Neck Squamous Cell Carcinoma In Vitro

BACKGROUND/AIM

This study investigated a novel combined therapy of rosmarinic acid (RA)/blue light on head and neck squamous cell carcinoma (HNSCC) cell proliferation in vitro.

MATERIALS AND METHODS

HNSCC cells were exposed to BL (500 mW/cm2) for 90 s, and incubated with 80 μg/ml RA for 1 hour. Cell viability was determined after 24 h using WST-1 assay. Western blot was used to detect treatment-induced changes in epidermal growth factor receptor (EGFR) activation. Hydrogen peroxide (H2O2) and nitric oxide levels were quantified using CM-H2DCFH-DA assays. Apoptosis was assessed using Annexin V/PI staining and flow cytometry.

RESULTS

RA/blue light treatment resulted in a significant reduction in cell viability, EGFR activation and H2O2 levels in all HNSCC cell lines. However, no significant changes in NO production or apoptosis induction were found.

CONCLUSION

RA/blue light effectively decreased HNSCC cell proliferation through reduction in EGFR activation and H2O2 production, and not via induction of apoptosis.

Abstract 1330: A novel rosmarinic acid/blue light combination treatment inhibits cell proliferation and migration in head and neck squamous cell carcinoma

Our labs have observed decreased proliferation of several cultured head and neck squamous cell carcinoma (HNSCC) cell lines when treated with rosmarinic acid or blue light. The purpose of this study was to test the hypothesis that the combination therapy would be more effective than either treatment alone, and to further characterize the cellular mechanisms responsible for these effects.

UM-SCC-6 oral squamous carcinoma cells were cultured in 24- or 96-well plates, and cells were exposed to blue light delivered from a Quartz-tungsten-halogen dental curing lamp (500 mW/cm2) for 90 or 120 sec, followed 1 h later by the addition of 80 μg/ml rosmarinic acid. Cell number was assessed at 24h using a WST-1 cell proliferation assay and cell migration was measured with an Oris Universal Migration Assay Kit. Reactive oxygen species (ROS) was quantified with each single treatment and combination using the CM-H2DCFH-DA assay. Western blot analysis was used to monitor changes in levels of cell signaling proteins known to be affected by each single treatment including phosphoAKT (pAKT) and AKT, NF-E2-related factor 2 (NRF2), heme oxygenase-1 (HO-1), and GAPDH (as a loading control).

As hypothesized, the combination of rosmarinic acid and blue light was more effective in reducing cell proliferation and migration than either single treatment alone. Both treatments also produced an early increase in ROS. Treatment with blue light significantly increased pAKT while rosmarinic acid decreased AKT activation. However, both treatments increased levels of Nrf2 and its downstream target, HO-1.

In order for the transcription factor NRF2 to translocate to the nucleus it needs to be stabilized and activated. AKT is an upstream kinase that is a known activator of NRF2 in response to an increase in ROS. Nuclear NRF2 binds to the antioxidant response element (ARE) within the promoters for phase II detoxifying/antioxidant genes, including that of HO-1. This signaling cascade has been shown to lead to anti-proliferative functions. Our results suggest that blue light induces this pathway by transiently increasing ROS that then significantly activates AKT. Subsequent NRF2 activation leads to increased levels of HO-1. Rosmarinic acid appears to use a different mechanism to upregulate NRF2 due to its downregulation of AKT. Importantly, both treatments activate NRF2, resulting in induction of antioxidant protein expression and ultimately decreasing ROS needed to promote tumor cell growth. This combination therapy may prove to be a useful, non-invasive treatment for HNSCC.

Citation Format: Christi N. Waer, Zohra Tumur, Dee Dee Hui, Bonnie Le, Carlos Guerra, Jill Lewis, Bradley Henson. A novel rosmarinic acid/blue light combination treatment inhibits cell proliferation and migration in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1330.

Modulation of liver-intestine cadherin (Cadherin 17) expression, ERK phosphorylation and WNT signaling in EPHB6 receptor-expressing MDA-MB-231 cells

Aberrant expression of erythropoietin-producing hepatocellular carcinoma cell (EPH) receptors has been reported in a variety of human cancer types. In addition to modulating cell proliferation and migration, EPH receptors are also involved in tumor progression. The transcriptional activation and silencing of EPH receptors are also associated with tumorigenesis. However, the mechanisms underlying the involvement of EPH receptors in tumorigenesis have not been completely deciphered. We have investigated and described the role of EPHB6, a kinase-deficient receptor, in modulating the abundance of cadherin 17 and activation of other intracellular signaling proteins. We previously showed that EPHB6 alters the tumor phenotype of breast carcinoma cells. However, the mechanisms underlying these phenotypic changes had not previously been investigated. Herein we demonstrated the downstream effects of EPHB6 expression on the abundance of cadherin 17, mitogen-activated protein kinase (MEK2), extracellular signal-regulated kinase (ERK), phospho-ERK, β-catenin, phospho- glycogen synthase kinase 3 beta (GSK3β) (ser21/9), cell morphology and actin cytoskeleton. These comparisons were made between EPHB6-deficient MDA-MB-231 cells transfected with an empty pcDNA3 vector and cells stably transfected with an expression construct of EPHB6. The results indicate elevated levels of MEK2 and phospho-ERK. While there was no change in the amount of ERK, the abundance of cadherin 17, β-catenin and phospho-GSK3β was significantly reduced in EPHB6-transfected cells. These studies clearly demonstrate an inverse relationship between the levels of phospho-ERK and the abundance of cadherin 17, β-catenin and phospho-GSK3β in EPHB6-expressing MDA-MB-231 cells. From these data we conclude that EPHB6-mediated alterations arise due to changes in abundance and localization of cadherin 17 and activation of WNT signaling pathway. Transcriptional silencing of EPHB6 in native MDA-MB-231 cells and consequent effects on cadherin 17 and WNT pathway may, thus, be responsible for the invasive behavior of these cells.