Genes and gene networks involved in sodium fluoride-elicited cell death accompanying endoplasmic reticulum stress in oral epithelial cells

Unraveling molecular characteristic of fluoride neurotoxicity on U87 glial-like cells: insights from transcriptomic and proteomic approach

The potential of fluoride (F) as a neurotoxicant in humans is still controversial in the literature. However, recent studies have raised the debate by showing different mechanism of F-induced neurotoxicity, as oxidative stress, energy metabolism and inflammation in the central nervous system (CNS). In the present study, we investigated the mechanistic action of two F concentration (0.095 and 0.22 μg/ml) on gene and protein profile network using a human glial cell in vitro model over 10 days of exposure. A total of 823 genes and 2,084 genes were modulated after exposure to 0.095 and 0.22 μg/ml F, respectively. Among them, 168 were found to be modulated by both concentrations. The number of changes in protein expression induced by F were 20 and 10, respectively. Gene ontology annotations showed that the main terms were related to cellular metabolism, protein modification and cell death regulation pathways, such as the MAP kinase (MAPK) cascade, in a concentration independent manner. Proteomics confirmed the changes in energy metabolism and also provided evidence of F-induced changes in cytoskeleton components of glial cells. Our results not only reveal that F has the potential to modulate gene and protein profiles in human U87 glial-like cells overexposed to F, but also identify a possible role of this ion in cytoskeleton disorganization.

The Strong Protective Action of Ce3+/F- Combined Treatment on Tooth Enamel and Epithelial Cells

We studied the toxic effects of cerium and fluoride species on human dental pulp stem cells and epithelial cells of Cercopithecus aethiops as a surrogate for the human oral mucosa. The sequential use of CeCl₃ and NH₄F solutions in equimolar sub-toxic concentrations enabled the possible toxic effects of individual components to be avoided, ensuring the preservation of the metabolic activity of the cells due to the formation of CeF₃ nanoparticles. Cerium fluoride nanoparticles and terbium-doped cerium fluoride nanoparticles exhibited neither cytotoxicity nor genotoxicity to dental pulp stem cells, even at high concentrations (10^-4 M). In millimolar concentrations (from 10^-5-10^-6 M), these nanoparticles significantly increased the expression of genes responsible for the cell cycle, differentiation and proliferation. The formation of cerium fluoride on the surface of the mucous membrane and teeth provided protection against the development of carious lesions, periodontitis, ROS attacks and other inflammatory diseases of the oral cavity. Luminescent CeF₃: Tb nanoparticles enabled the visualization of tooth enamel microcracks.

Rh(III)-Catalyzed Redox-Neutral [4+2] Annulation for Direct Assembly of 3-Acyl Isoquinolin-1(2H)-ones as Potent Antitumor Agents

By virtue of an efficient rhodium(III)-catalyzed redox-neutral C-H activation/ring-opening of a strained ring/[4+2] annulation cascade of N-methoxybenzamides with propargyl cycloalkanols, diverse 3-acyl isoquinolin-1(2H)-ones were directly obtained in good yields and with excellent functional group compatibility. Additionally, their antitumor activities against various human cancer cells including HepG2, A549, MCF-7 and SH-SY5Y were evaluated and the action mechanism of the selected compound was also investigated in vitro. The results revealed that these products possessed a potent efficacy, by inhibiting proliferation and inducing apoptosis in a time-dependent and dose-dependent manner, suggesting that such compounds can serve as promising candidates for anti lung cancer drug discovery.

CDKN2A, CDK1, and CCNE1 overexpression in sebaceous gland carcinoma of eyelid

PURPOSE

To investigate the overexpression of genes in sebaceous gland carcinoma (SGC) of the eyelid compared to sebaceous adenoma of the eyelid in order to elucidate the molecular mechanism underlying pathogenesis.

METHODS

We performed histopathological examination of eyelid tissues surgically removed from four patients diagnosed with SGC (cases 1-3) and sebaceous adenoma (case 4) of the eyelid. Next, we performed global gene expression analysis of surgical tissue samples using a GeneChip^® system and the Ingenuity Pathways Knowledge Base. The results of the GeneChip^® analysis were explored with quantitative real-time polymerase chain reaction (qRT-PCR) analysis.

RESULTS

In the SGC samples, we found that 211, 199, and 199 genes, respectively, showed ≥ 2.0-fold higher expression than those in the sebaceous adenoma sample (case 4); 194 genes were common to all three SGC samples. For the 194 genes with upregulated expression, functional category analysis showed that SGC of the eyelid employed a unique gene network, including cyclin-dependent kinase inhibitor 2A (CDKN2A), cyclin-dependent kinase 1 (CDK1), and cyclin E1 (CCNE1), which are related to cell cycle progression, incidence of tumor, and cell viability. Furthermore, qRT-PCR analysis showed that the expression levels of CDKN2A, CDK1, and CCNE1 were significantly upregulated in all SGC cases compared to those in the sebaceous adenoma case. These data were similar to the results of microarray analysis.

CONCLUSION

Overexpression of cell cycle-related genes CDKN2A, CDK1, CCNE1, and their gene network may help elucidate the pathogenic pathway of SGC of the eyelid at the molecular level.

Cell culture models of oral mucosal barriers: A review with a focus on applications, culture conditions and barrier properties

Understanding the function of oral mucosal epithelial barriers is essential for a plethora of research fields such as tumor biology, inflammation and infection diseases, microbiomics, pharmacology, drug delivery, dental and biomarker research. The barrier properties are comprised by a physical, a transport and a metabolic barrier, and all these barrier components play pivotal roles in the communication between saliva and blood. The sum of all epithelia of the oral cavity and salivary glands is defined as the blood-saliva barrier. The functionality of the barrier is regulated by its microenvironment and often altered during diseases. A huge array of cell culture models have been developed to mimic specific parts of the blood-saliva barrier, but no ultimate standard in vitro models have been established. This review provides a comprehensive overview about developed in vitro models of oral mucosal barriers, their applications, various cultivation protocols and corresponding barrier properties.

Gene networks in basal cell carcinoma of the eyelid, analyzed using gene expression profiling

Basal cell carcinoma (BCC) is the most frequent malignant tumor of the eyelid; it progresses slowly and rarely metastasizes. However, BCC of the eyelid is partially invasive and can extend to the surrounding ocular adnexa even if appropriate treatment is performed. To understand the molecular mechanism underlying its pathogenesis, global gene expression analysis of surgical tissue samples of BCC of the eyelid (n=2) and normal human epidermal keratinocytes was performed using a GeneChip^® system. The histopathological examination of surgically removed eyelid tissues showed the tumor nest composed with small basaloid. In the samples from patients 1 and 2, 687 and 713 genes were identified, respectively, demonstrating ≥5.0-fold higher expression than that noted in normal human epidermal keratinocytes. For the 640 genes with upregulated expression in both patient samples, Ingenuity^® pathway analysis showed that the gene network in BCC of the eyelid included many BCC-associated genes, such as the following: BCL2 apoptosis regulator; Patched-1; and SRY-box 9. In addition, unique gene networks related to cancer cell growth, tumorigenesis, and cell survival were identified. These results of integrating microarray analyses provide further insights into the molecular mechanisms involved in BCC of the eyelid and may provide a therapeutic approach for this disease.

High Throughput SiRNA Screening for Chloropicrin and Hydrogen Fluoride-Induced Cornea Epithelial Cell Injury

Toxicant-induced ocular injury is a true ocular emergency because chemicals have the potential to rapidly inflict significant tissue damage. Treatments for toxicant-induced corneal injury are generally supportive as no specific therapeutics exist to treat these injuries. In the efforts to develop treatments and therapeutics to care for exposure, it can be important to understand the molecular and cellular mechanisms of these injuries. We propose that utilization of high throughput small inhibitory RNA (siRNA) screening can be an important tool that could help to more rapidly elucidate the molecular mechanisms of chemical cornea epithelial injury. siRNA are double stranded RNA molecules that are 19-25 nucleotides long and utilize the post-transcriptional gene silencing pathway to degrade mRNA which have homology to the siRNA. The resulting reduction of expression of the specific gene can then be studied in toxicant exposed cells to ascertain the function of that gene in the cellular response to the toxicant. The development and validation of in vitro exposure models and methods for the high throughput screening (HTS) of hydrogen fluoride- (HF) and chloropicrin- (CP) induced ocular injury are presented in this article. Although we selected these two toxicants, our methods are applicable to the study of other toxicants with minor modifications to the toxicant exposure protocol. The SV40 large T antigen immortalized human corneal epithelial cell line SV40-HCEC was selected for study. Cell viability and IL-8 production were selected as endpoints in the screening protocol. Several challenges associated with the development of toxicant exposure and cell culture methods suitable for HTS studies are presented. The establishment of HTS models for these toxicants allows for further studies to better understand the mechanism of injury and to screen for potential therapeutics for chemical ocular injury.

Excessive ER stress and the resulting autophagic flux dysfunction contribute to fluoride-induced neurotoxicity

Fluoride is capable of inducing neurotoxicity, but its mechanisms remain elusive. This study aimed to explore the roles of endoplasmic reticulum (ER) stress and autophagy in sodium fluoride (NaF)-induced neurotoxicity, focusing on the regulating role of ER stress in autophagy. The in vivo results demonstrated that NaF exposure impaired the learning and memory capabilities of rats, and resulted in histological and ultrastructural abnormalities in rat hippocampus. Moreover, NaF exposure induced excessive ER stress and associated apoptosis, as manifested by elevated IRE1α, GRP78, cleaved caspase-12 and cleaved-caspase-3, as well as defective autophagy, as shown by increased Beclin1, LC3-II and p62 expression in hippocampus. Consistently, the in vitro results further verified the findings of in vivo study that NaF induced excessive ER stress and defective autophagy in SH-SY5Y cells. Notably, inhibition of autophagy in NaF-treated SH-SY5Y cells with Wortmannin or Chloroquine decreased, while induction of autophagy by Rapamycin increased the cell viability. These results were correlated well with the immunofluorescence observations, thus confirming the pivotal role of autophagic flux dysfunction in NaF-induced cell death. Importantly, mitigation of ER stress by 4-phenylbutyrate in NaF-treated SH-SY5Y cells inhibited the expressions of autophagy markers, and decreased cell apoptosis. Taken together, these data suggest that neuronal death resulted from excessive ER stress and autophagic flux dysfunction contributes to fluoride-elicited neurotoxicity. Moreover, the autophagic flux dysfunction was mediated by excessive ER stress, which provided novel insight into a better understanding of fluoride-induced neurotoxicity.

Overexpression of the anti-apoptotic protein BAG3 in human choroidal melanoma: A case report

Bcl-2-associated athanogene 3 (BAG3), a co-chaperone of heat shock protein 70 (HSP70), exerts anti-apoptotic effects in various malignant tumors. However, relationships between choroidal melanoma and BAG3 are poorly studied. This study investigated the expression of BAG3 in a case of human choroidal melanoma. Funduscopy, computed tomography, and single-photon emission computed tomography with the intravenous injection of N-isopropyl-p-[¹²³I] iodoamphetamine strongly indicated choroidal melanoma in a 68-year-old woman. Accordingly, we carried out an enucleation and pathological diagnosis. Proteins and total RNA were extracted from normal retinochoroidal and tumor tissues. Proteins were also extracted from ocular nevus tissues of other patients. We examined the expression of BAG3 protein and mRNA using Western blotting and the real-time quantitative polymerase chain reaction, respectively. Immunohistochemical stains were positive for melan-A, HMB-45, and S-100. Histopathology confirmed a choroidal melanoma. The expression of BAG3 protein and mRNA in the choroidal melanoma tissue was upregulated with respect to both normal retinochoroidal tissue and ocular nevus tissues from other patients. Because BAG3 may inhibit apoptosis of choroidal melanoma and facilitate its survival, overexpression of this gene product may be a prognostic marker and therapeutic target.

Network analysis of genes involved in the enhancement of hyperthermia sensitivity by the knockdown of BAG3 in human oral squamous cell carcinoma cells

BCL2-associated athanogene 3 (BAG3), a co-chaperone of the heat shock 70 kDa protein (HSPA) family of proteins, is a cytoprotective protein that acts against various stresses, including heat stress. The aim of the present study was to identify gene networks involved in the enhancement of hyperthermia (HT) sensitivity by the knockdown (KD) of BAG3 in human oral squamous cell carcinoma (OSCC) cells. Although a marked elevation in the protein expression of BAG3 was detected in human the OSCC HSC-3 cells exposed to HT at 44˚C for 90 min, its expression was almost completely suppressed in the cells transfected with small interfering RNA against BAG3 (siBAG) under normal and HT conditions. The silencing of BAG3 also enhanced the cell death that was increased in the HSC-3 cells by exposure to HT. Global gene expression analysis revealed many genes that were differentially expressed by >2-fold in the cells exposed to HT and transfected with siBAG. Moreover, Ingenuity® pathways analysis demonstrated two unique gene networks, designated as Pro-cell death and Anti-cell death, which were obtained from upregulated genes and were mainly associated with the biological functions of induction and the prevention of cell death, respectively. Of note, the expression levels of genes in the Pro-cell death and Anti-cell death gene networks were significantly elevated and reduced in the HT + BAG3-KD group compared to those in the HT control group, respectively. These results provide further insight into the molecular mechanisms involved in the enhancement of HT sensitivity by the silencing of BAG3 in human OSCC cells.

Effects of nitrogen on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon-based cold atmospheric pressure plasma

Cold atmospheric pressure plasma (CAP) is known as a source of biologically active agents, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). In the present study, we examined the effects of nitrogen (N2) on the apoptosis of and changes in gene expression in human lymphoma U937 cells exposed to argon (Ar)-CAP. Enormous amounts of hydroxyl (·OH) radicals in aqueous solution were produced using Ar‑CAP generated using a 20 kHz low frequency at 18 kV with a flow rate of 2 l/min. The increase in the levels of ·OH radicals was significantly attenuated by the addition of N2 to Ar gas. On the other hand, the level of total nitrate/nitrite in the supernatant was significantly elevated in the Ar + N2-CAP‑exposed U937 cells. When the cells were exposed to Ar‑CAP, a significant increase in apoptosis was observed, whereas apoptosis was markedly decreased in the cells exposed to Ar + N2-CAP. Microarray and pathway analyses revealed that a newly identified gene network containing a number of heat shock proteins (HSPs), anti-apoptotic genes, was mainly associated with the biological function of the prevention of apoptosis. Quantitative PCR revealed that the expression levels of HSPs were significantly elevated in the cells exposed to Ar + N2-CAP than those exposed to Ar‑CAP. These results indicate that N2 gas in Ar‑CAP modifies the ratio of ROS to RNS, and suppresses the apoptosis induced by Ar‑CAP. The modulation of gaseous conditions in CAP may thus prove to be useful for future clinical applications, such as for switching from a sterilizing mode to cytocidal effect for cancer cells.

Neurotoxin-induced pathway perturbation in human neuroblastoma SH-EP cells

The exact causes of cell death in Parkinson's disease (PD) remain unknown despite extensive studies on PD.The identification of signaling and metabolic pathways involved in PD might provide insight into the molecular mechanisms underlying PD. The neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) induces cellular changes characteristic of PD, and MPP(+)-based models have been extensively used for PD studies. In this study, pathways that were significantly perturbed in MPP(+)-treated human neuroblastoma SH-EP cells were identified from genome-wide gene expression data for five time points (1.5, 3, 9, 12, and 24 h) after treatment. The mitogen-activated protein kinase (MAPK) signaling pathway and endoplasmic reticulum (ER) protein processing pathway showed significant perturbation at all time points. Perturbation of each of these pathways resulted in the common outcome of upregulation of DNA-damage-inducible transcript 3 (DDIT3). Genes involved in ER protein processing pathway included ubiquitin ligase complex genes and ER-associated degradation (ERAD)-related genes. Additionally, overexpression of DDIT3 might induce oxidative stress via glutathione depletion as a result of overexpression of CHAC1. This study suggests that upregulation of DDIT3 caused by perturbation of the MAPK signaling pathway and ER protein processing pathway might play a key role in MPP(+)-induced neuronal cell death. Moreover, the toxicity signal of MPP(+) resulting from mitochondrial dysfunction through inhibition of complex I of the electron transport chain might feed back to the mitochondria via ER stress. This positive feedback could contribute to amplification of the death signal induced by MPP(+).