Importance of oxygen tension in human ovarian tissue in vitro culture

STUDY QUESTION

Is there any difference between 20% and 5% oxygen (O2) tension in vitro culture (IVC) on the viability and quality of human follicles contained in cultured ovarian cortex?

SUMMARY ANSWER

An O2 tension of 5% yields higher follicle viability and quality than does 20% O2 tension after 6 days of IVC.

WHAT IS KNOWN ALREADY

The primordial follicle (PMF) pool resides within the ovarian cortex, where the in vivo O2 tension ranges between 2% and 8%. Some studies suggest that lowering O2 tension to physiological levels may improve in vitro follicle quality rates.

STUDY DESIGN, SIZE, DURATION

This prospective experimental study included frozen-thawed ovarian cortex from six adult patients (mean age: 28.5 years; age range: 26-31 years) who were undergoing laparoscopic surgery for non-ovarian diseases. Ovarian cortical fragments were cultured for 6 days at (i) 20% O2 with 5% CO2 and (ii) 5% O2 with 5% CO2. Non-cultured fragments served as controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cortical fragments were used for the following analyses: hematoxylin and eosin staining for follicle count and classification; Ki67 staining to evaluate PMF proliferation; cleaved caspase-3 immunostaining to identify follicle apoptosis; 8-hydroxy-2-deoxyguanosine and gamma-H2AX (γH2AX) immunolabeling to detect oxidative stress damage and DNA double-strand breaks (DSBs) in oocytes and granulosa cells (GCs); and β-galactosidase staining to assess follicle senescence. Droplet digital PCR was also performed to further explore the gene expression of superoxide dismutase 2 (SOD2) and glutathione peroxidase 4 (GPX4) from the antioxidant defense system and cyclin-dependent kinase inhibitors (p21 and p16) as tissue senescence-related genes.

MAIN RESULTS AND THE ROLE OF CHANCE

Apoptosis (P = 0.002) and follicle senescence (P < 0.001) rates were significantly lower in the 5% O2 group than in the 20% O2 group. Moreover, GCs in follicles in the 20% O2 group exhibited significantly (P < 0.001) higher oxidative stress damage rates than those in the 5% O2 group. DNA DSB damage rates in GCs of follicles were also significantly higher (P = 0.001) in the 20% O2 group than in the 5% O2 group. SOD2 expression was significantly greater in the 5% O2 group compared to the 20% O2 group (P = 0.04) and the non-cultured group (P = 0.002). Expression of p21 was significantly increased in both the 20% O2 (P = 0.03) and 5% O2 (P = 0.008) groups compared to the non-cultured group. Moreover, the 20% O2 group showed significantly greater p16 expression (P = 0.04) than the non-cultured group, while no significant variation was observed between the 5% O2 and no culture groups.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study focuses on improving follicle outcomes during the first step of ovarian tissue IVC, where follicles remain in situ within the tissue. The impact of O2 tension in further steps, such as secondary follicle isolation and maturation, was not investigated here.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that 5% O2 tension culture is a promising step toward potentially solving the problem of poor follicle viability after IVC.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Fonds National de la Recherche Scientifique de Belgique (FNRS-PDR T.0064.22, CDR J.0063.20 and grant 5/4/150/5 awarded to M.M.D.). The authors have nothing to disclose.

Quercetin induced apoptosis of human oral cancer SAS cells through mitochondria and endoplasmic reticulum mediated signaling pathways

Oral cancer is a cause of cancer-associated mortality worldwide and the treatment of oral cancer includes radiation, surgery and chemotherapy. Quercetin is a component from natural plant products and it has been demonstrated that quercetin is able to induce cytotoxic effects through induction of cell apoptosis in a number of human cancer cell lines. However, there is no available information to demonstrate that quercetin is able to induce apoptosis in human oral cancer cells. In the present study, the effect of quercetin on the cell death via the induction of apoptosis in human oral cancer SAS cells was investigated using flow cytometry, Annexin V/propidium iodide (PI) double staining, western blotting and confocal laser microscopy examination, to test for cytotoxic effects at 6–48 h after treatment with quercetin. The rate of cell death increased with the duration of quercetin treatment based on the results of a cell viability assay, increased Annexin V/PI staining, increased reactive oxygen species and Ca²⁺ production, decreased the levels of mitochondrial membrane potential (ΔΨ_m), increased proportion of apoptotic cells and altered levels of apoptosis-associated protein expression in SAS cells. The results from western blotting revealed that quercetin increased Fas, Fas-Ligand, fas-associated protein with death domain and caspase-8, all of which associated with cell surface death receptor. Furthermore, quercetin increased the levels of activating transcription factor (ATF)-6α, ATF-6β and gastrin-releasing peptide-78 which indicated an increase in endoplasm reticulum stress, increased levels of the pro-apoptotic protein BH3 interacting-domain death antagonist, and decreased levels of anti-apoptotic proteins B-cell lymphoma (Bcl) 2 and Bcl-extra large which may have led to the decreases of ΔΨ_m. Additionally, confocal microscopy suggested that quercetin was able to increase the expression levels of cytochrome c, apoptosis-inducing factor and endonuclease G, which are associated with apoptotic pathways. Therefore, it is hypothesized that quercetin may potentially be used as a novel anti-cancer agent for the treatment of oral cancer in future.

Gypenosides induce cell death and alter gene expression in human oral cancer HSC-3 cells

Gypenosides (Gyp), the primary components of Gynostemma pentaphyllum Makino, have long been used as a Chinese herbal medicine. In the present study, the effects of Gyp on cell viability, the cell cycle, cell apoptosis, DNA damage and chromatin condensation were investigated in vitro using human oral cancer HSC-3 cells. The results of the present study indicated that Gyp induces cell death, G2/M phase arrest and apoptosis in HSC-3 cells in a dose-dependent manner. It was also demonstrated that Gyp decreased the depolarization of mitochondrial membrane potential in a time-dependent manner. A cDNA microarray assay was performed and the results indicated that a number of genes were upregulated following Gyp treatment. The greatest increase was a 75.42-fold increase in the expression of GTP binding protein in skeletal muscle. Levels of the following proteins were also increased by Gyp: Serpine peptidase inhibitor, clade E, member 1 by 20.25-fold; ras homolog family member B by 18.04-fold, kelch repeat and BTB domain containing 8 by 15.22-fold; interleukin 11 by 14.96-fold; activating transcription factor 3 by 14.49-fold; cytochrome P450, family 1 by 14.44-fold; ADP-ribosylation factor-like 14 by 13.88-fold; transfer RNA selenocysteine 2 by 13.23-fold; and syntaxin 11 by 13.08-fold. However, the following genes were downregulated by GYP: Six-transmembrane epithelial antigen of prostate family member 4, 14.19-fold; γ-aminobutyric acid A receptor by 14.58-fold; transcriptional-regulating factor 1 by 14.69-fold; serpin peptidase inhibitor, clade B, member 13 by 14.71-fold; apolipoprotein L 1 by 14.85-fold; follistatin by 15.22-fold; uncharacterized LOC100506718; fibronectin leucine rich transmembrane protein 2 by 15.61-fold; microRNA 205 by 16.38-fold; neuregulin 1 by 19.69-fold; and G protein-coupled receptor 110 by 22.05-fold. These changes in gene expression illustrate the effects of Gyp at the genetic level and identify potential targets for oral cancer therapy.

Fisetin-induced apoptosis of human oral cancer SCC-4 cells through reactive oxygen species production, endoplasmic reticulum stress, caspase-, and mitochondria-dependent signaling pathways

Oral cancer is one of the cancer-related diseases in human populations and its incidence rates are rising worldwide. Fisetin, a flavonoid from natural products, has been shown to exhibit anticancer activities in many human cancer cell lines but the molecular mechanism of fisetin-induced apoptosis in human oral cancer cells is still unclear; thus, in this study, we investigated fisetin-induced cell death and associated signal pathways on human oral cancer SCC-4 cells in vitro. We examined cell morphological changes, total viable cells, and cell cycle distribution by phase contrast microscopy and flow cytometry assays. Reactive oxygen species (ROS), Ca²⁺ , mitochondria membrane potential (ΔΨ_m ), and caspase-8, -9, and -3 activities were also measured by flow cytometer. Results indicate that fisetin induced cell death through the cell morphological changes, caused G2/M phase arrest, induction of apoptosis, promoted ROS and Ca²⁺ production, and decreased the level of ΔΨ_m and increased caspase-3, -8, and -9 activities in SCC-4 cells. DAPI staining and DNA gel electrophoresis were also used to confirm fisetin-induced cell apoptosis in SCC-4 cells. Western blotting also found out that Fisetin increased the proapoptotic proteins such as Bax and Bid and decreased the antiapoptotic proteins such as Bcl-2. Furthermore, results also showed that Fisetin increased the cytochrome c, AIF, and Endo G release from mitochondria in SCC-4 cells. We also used ATF-6α, ATF-6β, GADD153, and GRP78 which indicated that fisetin induced cell death through ER stress. Based on those observations, we suggest that fisetin induced cell apoptosis through ER stress, mitochondria-, and caspase-dependent pathways.

Anticancer effects of cantharidin in A431 human skin cancer (Epidermoid carcinoma) cells in vitro and in vivo

Cantharidin (CTD), a potential anticancer agent of Traditional Chinese Medicine has cytotxic effects in different human cancer cell lines. The cytotoxic effects of CTD on A431 human skin cancer (epidermoid carcinoma) cells in vitro and in A431 cell xenograft mouse model were examined. In vitro, A431 human skin cell were treated with CTD for 24 and 48 h. Cell phase distribution, ROS production, Ca²⁺ release, Caspase activity and the level of apoptosis associated proteins were measured. In vivo, A431 cell xenograft mouse model were examined. CTD-induced cell morphological changes and decreased percentage of viable A431 cells via G0/G1 phase arrest and induced apoptosis. CTD-induced G0/G1 phase arrest through the reduction of protein levels of cyclin E, CDK6, and cyclin D in A431 cells. CTD-induced cell apoptosis of A431 cells also was confirm by DNA gel electrophoresis showed CTD-induced DNA fragmentation. CTD reduced the mitochondrial membrane potential and stimulated release of cytochrome c, AIF and Endo G in A431 cells. Flow cytometry demonstrated that CTD increased activity of caspase-8, -9 and -3. However, when cells were pretreated with specific caspase inhibitors activity was reduced and cell viability increased. CTD increased protein levels of death receptors such as DR4, DR5, TRAIL and levels of the active form of caspase-8, -9 and -3 in A431 cells. AIF and Endo G proteins levels were also enhanced by CTD. In vivo studies showed that CTD significantly inhibited A431 cell xenograft tumors in mice. Taken together, these in vitro and in vivo results provide insight into the mechanisms of CTD on cell growth and tumor production. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 723-738, 2017.

Antitumor effects of deguelin on H460 human lung cancer cells in vitro and in vivo: Roles of apoptotic cell death and H460 tumor xenografts model

Deguelin, a naturally occurring rotenoid of the flavonoid family, is known to be an Akt inhibitor, to have chemopreventive activities and anti-tumor effect on several cancers. In this study, investigation to elucidate the effect of deguelin on apoptotic pathways in human lung cancer cells and on the anti-tumor effect in lung cancer xenograft nu/nu mice was performed. In vitro studies, found that deguelin induced cell morphological changes, and decreased the percentage of viability through the induction of apoptosis in H460 lung cancer cells. Deguelin triggered apoptosis in H460 cells was also confirmed by DAPI staining, DNA gel electrophoresis, and Annexin V-FITC staining and these effects are dose-dependent manners. It was also found that deguelin promoted the Ca²⁺ production and activation of caspase-3 but decreased the level of ΔΨ_m in H460 cells. Western blots indicated that the protein levels of cytochrome c, AIF, and pro-apoptotic Bax and Bak protein were increased, but the anti-apoptotic Bcl-2 and Bcl-x were decreased that may have led to apoptosis in H460 cells after exposure to deguelin. It was also confirmed by confocal laser microscope examination that deguelin promoted the release of AIF from mitochondria to cytosol. In vivo studies, found that in immunodeficient nu/nu mice bearing H460 tumor xenografts showed that the deguelin significantly suppressed tumor growth. Deguelin might be a potential therapeutic agent for the treatment of lung cancer in the future. This finding might fully support a critical event for deguelin via induction of apoptotic cell death and H460 tumor xenografts model against human lung cancer. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 84-98, 2017.

Tetrandrine induces programmed cell death in human oral cancer CAL 27 cells through the reactive oxygen species production and caspase-dependent pathways and associated with beclin-1-induced cell autophagy

Tetrandrine, a bisbenzylisoquinoline alkaloid, is extracted from the root of the Chinese herb Radix Stephania tetrandra S Moore. This compound has antitumor activity in different cancer cell types. In this study, the effects of tetrandrine on human oral cancer CAL 27 cells were examined. Results indicated that tetrandrine induced cytotoxic activity in CAL 27 cells. Effects were due to cell death by the induction of apoptosis and accompany with autophagy and these effects were concentration- and time-dependent manners. Tetrandrine induced apoptosis was accompanied by alterations in cell morphology, chromatin fragmentation, and caspase activation in CAL 27 cells. Tetrandrine treatment also induced intracellular accumulation of reactive oxygen species (ROS). The generation of ROS may play an important role in tetrandrine-induced apoptosis. Tetrandrine triggered LC3B expression and induced autophagy in CAL 27 cells. Tetrandrine induced apoptosis and autophagy were significantly attenuated by N-acetylcysteine pretreatment that supports the involvement of ROS production. Tetrandrine induced cell death may act through caspase-dependent apoptosis with Beclin-1-induced autophagy in human oral cancer cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 329-343, 2017.

Allyl Isothiocyanate Induces Cell Toxicity by Multiple Pathways in Human Breast Cancer Cells

Isothiocyanates (ITCs) occur in many cruciferous vegetables. These compounds, which have significant anticancer actions, can induce apoptosis in different human cancer cell lines. In the present study, we investigated if allyl isothiocyanate (AITC) would induce toxicity in human breast cancer MCF-7 (estrogen receptor positive) and MDA-MB-231 (estrogen receptor negative) cells. We found that AITC stimulated reactive oxygen species and Ca[Formula: see text] production, and decreased the mitochondrial membrane potential. Activity of caspase-8, -9 and -3 was increased by AITC in both cell lines. AITC also induced mitochondrial-mediated apoptosis, as shown by cytochrome c, AIF and Endo G release from mitochondria, activation of caspase-9 and caspase-3, and formation of DAPI-positive cells. There was a significant reduction in the levels of the anti-apoptotic protein Bcl-2 along with a marked increase in the pro-apoptotic protein Bax in both cell lines. AITC induced apoptosis in human breast cancer MCF-7 cells via AIF and Endo G signaling pathways, but in MDA-MB-231 cells apoptosis occurred via the GADD153 pathway. This study has revealed novel anti-cancer mechanisms of AITC, a compound that is ordinarily present in human diets and may have potential therapeutic effects in various cancers.

Suppression of the migration and invasion is mediated by triptolide in B16F10 mouse melanoma cells through the NF-kappaB-dependent pathway

Melanoma cancer is one of the major causes of death in humans worldwide. Triptolide is one of the active components of Tripterygium wilfordii Hook F, and has biological activities including induced cell cycle arrest and induction of apoptosis but its antimetastatic effects on murine melanoma cells have not yet been elucidated. Herein, we investigated the effect of triptolide on the inhibition of migration and invasion and possible associated signal pathways in B16F10 murine melanoma cancer cells. Wound healing assay and Matrigel Cell Migration Assay and Invasion System demonstrated that triptolide marked inhibiting the migration and invasion of B16F10 cells. Gelatin zymography assay demonstrated that triptolide significantly inhibited the activities of matrix metalloproteinases-2 (MMP-2). Western blotting showed that triptolide markedly reduced CXCR4, SOS1, GRB2, p-ERK, FAK, p-AKT, Rho A, p-JNK, NF-κB, MMP-9, and MMP-2 but increased PI3K and p-p38 and COX2 after compared to the untreated (control) cells. Real time PCR indicated that triptolide inhibited the gene expression of MMP-2, FAK, ROCK-1, and NF-κB but did not significantly affect TIMP-1 and -2 gene expression in B16F10 cells in vitro. EMSA assay also showed that triptolide inhibited NF-κB DNA binding in a dose-dependent manner. Confocal laser microscopy examination also confirmed that triptolide inhibited the expression of NF-κB in B16F10 cells. Taken together, we suggest that triptolide inhibited B16F10 cell migration and invasion via the inhibition of NF-κB expression then led to suppress MMP-2 and -9 expressions. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1974-1984, 2016.

Tetrandrine Induces Apoptosis of Human Nasopharyngeal Carcinoma NPC-TW 076 Cells through Reactive Oxygen Species Accompanied by an Endoplasmic Reticulum Stress Signaling Pathway

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy of the head and neck and the incidence is higher in Southeast Asia. Tetrandrine (TET) is a bisbenzylisoquinoline alkaloid, a natural product, and exhibits biological activities including action against many human cancer cell lines. However, the molecular mechanism of TET-induced cell apoptosis in human NPC cells is still unclear. In the present study, we investigated TET-induced apoptotic cell death and associated possible signal pathways on human nasopharyngeal carcinoma NPC-TW 076 cells in vitro. Phase contrast microscopy was used to examine cell morphology and DAPI staining was used to examine chromatin condensation. Flow cytometry assay was used to measure total viable cells, cell cycle and sub-G₁ phase distribution, reactive oxygen species (ROS), Ca²⁺, and mitochondria membrane potential (ΔΨm) in NPC-TW 076 cells. Results indicate that TET induced cell death through the cell morphological changes, caused G₀/G₁ phase arrest, increased ROS and Ca²⁺ production, and finally caused apoptotic cell death in NPC-TW 076 cells. There was no influence on the level of ΔΨm after TET treatment. Western blotting indicated that TET increased endoplasmic reticulum (ER) stress associated protein expression such as GADD153, GRP78, ATF-6α and ATF-6 βwhich indicated that TET induced cell death through ER stress. ER stress is a potential target in cancer treatment, so the ability of TET to induce ER stress response and to activate programming cell death in NPC-TW 076 cells make this molecule become a promising anticancer agent.

Bufalin Inhibits NCI-H460 Human Lung Cancer Cell Metastasis In Vitro by Inhibiting MAPKs, MMPs, and NF-κB Pathways

Bufalin, a component of Chan Su (a traditional Chinese medicine), has been known to have antitumor effects for thousands of years. In this study, we investigated its anti-metastasis effects on NCI-H460 lung cancer cells. Under sub-lethal concentrations (from 25 up to 100 nM), bufalin significantly inhibits the invasion and migration nature of NCI-H460 cells that were measured by Matrigel Cell Migration Assay and Invasion System. Bufalin also suppressed the enzymatic activity of matrix metalloproteinase (MMP)-9, which was examined by gelatin zymography methods. Western blotting revealed that bufalin depressed several key metastasis-related proteins, such as NF-κB, MMP-2, MMP-9, protein kinase C (PKC), phosphatidylinositol 3-kinase (PI3-K), phosphorylated Akt, growth factor receptor-bound protein 2 (GRB2), phosphorylated extracellular signal-regulated kinase (ERK), phosphorylated p38, and phosphorylated c-Jun NH2-terminal kinase (JNK). As evidenced by immunostaining and the electrophoretic mobility shift assay (EMSA), bufalin induced not only a decreased cytoplasmic NF-κB production, but also decreased its nuclear translocation. Several metastasis-related genes, including Rho-associated (Rho A), coiled-coil-containing protein kinase 1 (ROCK1), and focal adhesion kinase (FAK), were down-regulated after bufalin treatment. In conclusion, bufalin is effective in inhibiting the metastatic nature of NCI-H460 cells in low, sub-lethal concentrations. Such an effect involves many mechanisms including MMPs, mitogen-activated protein kinases (MAPKs) and NF-κB systems. Bufalin has a potential to evolve into an anti-metastasis drug for human lung cancer in the future.

Tetrandrine induces apoptosis Via caspase-8, -9, and -3 and poly (ADP ribose) polymerase dependent pathways and autophagy through beclin-1/ LC3-I, II signaling pathways in human oral cancer HSC-3 cells

Tetrandrine is a bisbenzylisoquinoline alkaloid that was found in the Radix Stephania tetrandra S Moore. It had been reported to induce cytotoxic effects on many human cancer cells. In this study, we investigated the cytotoxic effects of tetrandrine on human oral cancer HSC-3 cells in vitro. Treatments of HSC-3 cells with tetrandrine significantly decreased the percentage of viable cells through the induction of autophagy and apoptosis and these effects are in concentration-dependent manner. To define the mechanism underlying the cytotoxic effects of tetrandrine, we investigated the critical molecular events known to regulate the apoptotic and autophagic machinery. Tetrandrine induced chromatin condensation, internucleosomal DNA fragmentation, activation of caspases-3, -8, and -9, and cleavage of poly (ADP ribose) polymerase (PARP) that were associated with apoptosis, and it also enhanced the expression of LC3-I and -II that were associated with the induction of autophagy in human squamous carcinoma cell line (HSC-3) cells. Tetrandrine induced autophagy in HSC-3 cells was significantly attenuated by bafilomycin A1 (inhibitor of autophagy) pre-treatment that confirmed tetrandrine induced cell death may be associated with the autophagy. In conclusion, we suggest that tetrandrine induced cell death may be through the induction of apoptosis as well as autophagy in human oral cancer HSC-3 cells via PARP, caspases/Becline I/LC3-I/II signaling pathways.

PEITC inhibits human brain glioblastoma GBM 8401 cell migration and invasion through the inhibition of uPA, Rho A, and Ras with inhibition of MMP-2, -7 and -9 gene expression

Glioblastoma is the most aggressive primary brain malignancy, and the efficacy of multimodality treatments remains unsatisfactory. Phenethyl isothiocyanate (PEITC), one member of the isothiocyanate family, was found to inhibit the migration and invasion of many types of human cancer cells. In our previous study, PEITC induced the apoptosis of human brain glioblastoma GBM 8401 cells through the extrinsic and intrinsic signaling pathways. In the present study, we first investigated the effects of PEITC on the migration and invasion of GBM 8401 cells. PEITC decreased the migration of GBM 8401 cells in a dose-dependent manner as determined from scratch wound healing and Transwell migration assays. The percentage of inhibition ranged from 46.89 to 15.75%, and from 27.80 to 7.31% after a 48-h treatment of PEITC as determined from the Transwell migration assay and invasion assay, respectively. The western blot analysis indicated that PEITC decreased the levels of proteins associated with migration and invasion, Ras, uPA, RhoA, GRB2, p-p38, p-JNK, p-ERK, p65, SOS1, MMP-2, MMP-9 and MMP-13, in a dose-dependent manner. Real-time PCR analyses revealed that PEITC reduced the mRNA levels of MMP-2, MMP-7, MMP-9 and RhoA in a dose- and time-dependent manner. PEITC exhibited potent anticancer activities through the inhibition of migration and invasion in the GBM 8401 cells. Our findings elucidate the possible molecular mechanisms and signaling pathways of the anti-metastatic effects of PEITC on human brain glioblastoma cells, and PEITC may be considered as a therapeutic agent.

Gallic acid induces DNA damage and inhibits DNA repair-associated protein expression in human oral cancer SCC-4 cells

Gallic acid (GA), a phenolic compound naturally present in plants, used as an antioxidant additive in food and in the pharmaceutical industry, may have cancer chemopreventive properties. In the present study, we investigated whether GA induced DNA damage and affected DNA repair-associated protein expression in human oral cancer SCC-4 cells. Flow cytometry assays were used to measure total viable cells and results indicated that GA decreased viable cells dose-dependently. The comet assay and 4',6-Diamidino-2-phenylindole dihydrochloride (DAPI) staining were used to measure DNA damage, as well as condensation and it was shown that GA induced DNA damage (comet tail) and DNA condensation in a dose-dependent manner. DNA gel electrophoresis was used to examine DNA fragmentation and we found that GA induced DNA ladder (fragmentation). Using western blotting it was shown that GA inhibited the protein expressions of MDC1, O(6)-methylguanine-DNA methyltransferase (MGMT), p-H2A.X, p53, DNA-dependent serine/threonine protein kinase (DNA-PK) and 14-3-3 proteins sigma (14-3-3σ) but increased p-p53, phosphate-ataxia-telangiectasia (p-H2A.X) and ataxia telangiectasia mutated and Rad3-related (p-ATR), phosphate-ataxia telangiectasia mutated (p-ATM) and breast cancer susceptibility protein 1 (BRCA1) in a 24-h treatment. The protein translocation was examined by confocal laser microscopy and results indicated that GA increased the levels of p-H2A.X, MDC1 and p-p53 in SCC-4 cells. In conclusion, we found that GA-induced cell death may proceed through the induced DNA damage and suppressed DNA repair-associated protein expression in SCC-4 cells.

Crude extract of Polygonum cuspidatum promotes immune responses in leukemic mice through enhancing phagocytosis of macrophage and natural killer cell activities in vivo

Polygonum cuspidatum is a traditional Chinese herbal medicine used in the treatment of various diseases. In the present study, we investigated whether the crude extract of Polygonum cuspidatum (CEPC) could affect immune responses of murine leukemia cells in vivo. Normal BALB/c mice were i.p. injected with WEHI-3 cells to generate leukemic mice and then were treated orally with CEPC at 0, 50, 100 and 200 mg/kg for three weeks. Animals were weighed and blood, liver, spleen samples were collected for further analyses. Results indicated that CEPC did not significantly affect the body and liver weight of animals, but reduced the weight of spleen when compared to control groups. Flow cytometric assay demonstrated that CEPC increased the percentage of CD3- (T-cell marker) and CD19- (B-cell marker) positive cells, but reduced that of CD11b-positive ones (monocytes). However, it did not significantly affect the proportion of Mac-3-positive cells (macrophages), compared to control groups. Results indicated that CEPC promoted phagocytosis by macrophages from blood samples at all examined doses but did not affect that of macrophages from the peritoneal cavity. CEPC also promoted natural killer cell activity of splenocytes at 200 mg/kg of CEPC. CEPC promoted B-cell proliferation at 200 mg/kg treatment when cells were stimulated with lipopolysaccharides but did not promote T-cell proliferation at three doses of CEPC treatment on concanavalin A stimulation.

α-Phellandrene alters expression of genes associated with DNA damage, cell cycle, and apoptosis in murine leukemia WEHI-3 cells

α-phellandrene (α-PA) is a cyclic monoterpene, present in natural plants such as Schinus molle L. α-PA promotes immune responses in mice in vivo. However, there is no available information on whether α-PA affects gene expression in leukemia cells. The present study determined effects of α-PA on expression levels of genes associated with DNA damage, cell cycle and apoptotic cell death in mouse leukemia WEHI-3 cells. WEHI-3 cells were treated with 10 μM α-PA for 24 h, cells were harvested and total RNA was extracted, and gene expression was analyzed by cDNA microarray. Results indicated that α-PA up-regulated 10 genes 4-fold, 13 by over 3-fold and 175 by over 2-fold; 21 genes were down-regulated by over 4-fold, 26 genes by over 3-fold and expression of 204 genes was altered by at leas 2-fold compared with the untreated control cells. DNA damage-associated genes such as DNA damage-inducer transcript 4 and DNA fragmentation factor were up-regulated by 4-fold and over 2-fold, respectively; cell-cycle check point genes such as cyclin G2 and cyclin-dependent kinases inhibitor 2D and IA (p21) were up-regulated by over 3-fold and over 2-fold, respectively; apoptosis-associated genes such as BCL2/adenovirus EIB interacting protein 3, XIAP-associated factor 1, BCL2 modifying factor, caspase-8 and FADD-like apoptosis regulator were over 2-fold up-regulated. Furthermore, DNA damage-associated gene TATA box binding protein was over 4-fold down-regulated, and D19Ertd652c (DNA segment) over 2-fold down-regulated; cell cycle-associated gene cyclin E2 was over 2-fold down-regulated; apoptosis associated gene growth arrest-specific 5 was over 9-fold down-regulated, Gm5426 (ATP synthase) was over 3-fold down-regulated, and death box polypeptide 33 was over 2-fold down-regulated. Based on these observations, α-PA altered gene expression in WEHI-3 cells in vitro.

Safrole suppresses murine myelomonocytic leukemia WEHI-3 cells in vivo, and stimulates macrophage phagocytosis and natural killer cell cytotoxicity in leukemic mice

Many anticancer drugs are obtained from phytochemicals and natural products. However, some phytochemicals have mutagenic effects. Safrole, a component of Piper betle inflorescence, has been reported to be a carcinogen. We have previously reported that safrole induced apoptosis in human oral cancer cells in vitro and inhibited the human oral tumor xenograft growth in vivo. Until now, there is no information addressing if safrole promotes immune responses in vivo. To evaluate whether safrole modulated immune function, BALB/c mice were intraperitoneally injected with murine myelomonocytic WEHI-3 leukemia cells to establish leukemia and then were treated with or without safrole at 4 and 16 mg/kg. Animals were sacrificed after 2 weeks post-treatment with safrole for examining the immune cell populations, phagocytosis of macrophages and the natural killer (NK) cells' cytotoxicity. Results indicated that safrole increased the body weight, and decreased the weights of spleen and liver in leukemic mice. Furthermore, safrole promoted the activities of macrophages phagocytosis and NK cells' cytotoxicity in leukemic mice when compared with untreated leukemic mice. After determining the cell marker population, we found that safrole promoted the levels of CD3 (T cells), CD19 (B cells) and Mac-3 (macrophages), but it did not affect CD11b (monocytes) in leukemic mice. In conclusion, safrole altered the immune modulation and inhibited the leukemia WEHI-3 cells in vivo.

Safrole induces cell death in human tongue squamous cancer SCC-4 cells through mitochondria-dependent caspase activation cascade apoptotic signaling pathways

Safrole is one of important food-borne phytotoxin that exhibits in many natural products such as oil of sassafras and spices such as anise, basil, nutmeg, and pepper. This study was performed to elucidate safrole-induced apoptosis in human tongue squamous carcinoma SCC-4 cells. The effect of safrole on apoptosis was measured by flow cytometry and DAPI staining and its regulatory molecules were studied by Western blotting analysis. Safrole-induced apoptosis was accompanied with up-regulation of the protein expression of Bax and Bid and down-regulation of the protein levels of Bcl-2 (up-regulation of the ratio of Bax/Bcl-2), resulting in cytochrome c release, promoted Apaf-1 level and sequential activation of caspase-9 and caspase-3 in a time-dependent manner. We also used real-time PCR to show safrole promoted the mRNA expressions of caspase-3, -8, and -9 in SCC-4 cells. These findings indicate that safrole has a cytotoxic effect in human tongue squamous carcinoma SCC-4 cells by inducing apoptosis. The induction of apoptosis of SCC-4 cells by safrole is involved in mitochondria- and caspase-dependent signal pathways.

Diallyl sulfide inhibits murine WEHI-3 leukemia cells in BALB/c mice in vitro and in vivo

It is well documented that enhanced garlic (Allium sativum) consumption leads to decrease in the cancer incidences. Diallyl sulfide (DAS), one of the components of garlic, induces cytotoxicity and apoptosis in many cancer cell lines. The present studies are focused on the in vivo effects of DAS on leukemia WEHI-3 cells in the BALB/c mice. We examined the effects of DAS on the cytotoxicity of WEHI-3 cells and results indicated that DAS decreased the percentage of viable WEHI-3 cells and these effects are dose-dependent. We examined the effects of DAS on WEHI-3 in vivo and the results indicated that DAS decreased the percentage of Mac-3 and CD11b, indicating that the differentiation of the precursor of macrophage cells was inhibited. DAS stimulated the percentage of CD3 and CD19, indicating that the differentiation of the precursor of T and B cells promoted. The weights of liver and spleen indicated that DAS decreased the weight of these organs after being compared to the control groups. One of the major characteristic of WEHI-3 leukemia is the enlarged spleen in murine after intraperitoneal (i.p.) injection of WEHI-3 cells. In conclusion, DAS affects WEHI-3 cells both in vitro and in vivo.

Emodin induces apoptosis of human tongue squamous cancer SCC-4 cells through reactive oxygen species and mitochondria-dependent pathways

Emodin was isolated from Rheum palmatum L. and exhibits an anticancer effect on human cancer cell lines, however, the molecular mechanisms of emodin-mediated apoptosis in human tongue cancer cells have not been fully investigated. In this study, treatment of human tongue cancer SCC-4 cells with various concentrations of emodin led to G2/M arrest through promoted p21 and Chk2 expression but inhibited cyclin B1 and cdc2; it also induced apoptosis through the pronounced release of cytochrome c from mitochondria and activations of caspase-9 and caspase-3. These events were accompanied by the generation of reactive oxygen species (ROS), disruption of mitochondrial membrane potential (delta psi(m)) and a decrease in the ratio of mitochondrial Bcl-2 and Bax content; emodin also promoted the levels of GADD153 and GRP78. The free radical scavenger N-acetylcysteine and caspase inhibitors markedly blocked emodin-induced apoptosis. Taken together, these findings suggest that emodin mediated oxidative injury (DNA damage) based on ROS production and ER stress based on the levels of GADD153 and GRP78 that acts as an early and upstream change in the cell death cascade to caspase- and mitochondria-dependent signaling pathways, triggers mitochondrial dysfunction from Bcl-2 and Bax modulation, mitochondrial cytochrome c release and caspase activation, consequently leading to apoptosis in SCC-4 cells.

The roles of endoplasmic reticulum stress and Ca2+ on rhein-induced apoptosis in A-549 human lung cancer cells

Although rhein has been shown to induce apoptosis in several cancer cell lines, the mechanism of action of rhein-induced cell cycle arrest and apoptosis at the molecular level is not well known. In this study, the mechanism of rhein action on A-549 human lung cancer cells was investigated. Rhein induced G0/G1 arrest through inhibition of cyclin D3, Cdk4 and Cdk6. The efficacious induction of apoptosis was observed at 50 microM for 12 h and up to 72 h as examined by a flow cytometric method. Flow cytometric analysis demonstrated that rhein increased the levels of GADD153 and GRP78, both hallmarks of endoplasmic reticulum stress, promoted ROS and Ca2+ production, induced the loss of mitochondrial membrane potential (delta psi(m)), promoted cytochrome c release from mitochondria, promoted capase-3 activation and led to apoptosis. Rhein also increased the levels of p53, p21 and Bax but reduced the level of Bcl-2. The Ca2+ chelator BAPTA was added to the cells before rhein treatment, thus blocking the Ca2+ production and inhibiting rhein-induced apoptosis in A-549 cells. Our data demonstrate that rhein induces apoptosis in A-549 cells via a Ca2+ -dependent mitochondrial pathway.

Berberine induced down-regulation of matrix metalloproteinase-1, -2 and -9 in human gastric cancer cells (SNU-5) in vitro

Berberine, a yellow benzylisoquinoline alkaloid, is a constituent of Coptis chines and is commonly used in Chinese herbal medicine for patients with gastrointestinal disorders. The pharmacological effects of berberine include anti-inflammation, antidiarrhetic, antimalarial, and even antimicrobial activities. However, its mechanism of action on the cell migration of human gastric cancer SNU-5 cells is not fully understood. The effects of berberine on the percentage of viable cells were examined first and it was found that berberine induced dose-dependent inhibition in human gastric cancer SNU-5 cells. The effect of berberine on the levels of reactive oxygen species (ROS) and matrix metalloproteinase-1, -2, -7 and -9 was then examined using Western blotting and the results showed that berberine induced ROS production for up to 6 hours of incubation. It was also found that berberine induced downregulation of MMP-1 -2, and -9 but did not affect the level of MMP-7. The mRNA levels of MMPs in SNU-5 cells after treatment with berberine for 24 hours were investigated using a polymerase chain reaction and the results showed that berberine inhibited the gene expression of MMP-1, -2 and -9 in human SNU-5 cells but it did not affect MMP-7. In conclusion, berberine appears to exert its anticancer properties by inducing ROS production and prevention of cell migration via inhibition of the gene expression of MMP-1, -2 and -9 in human gastric cancer SNU-5 cancer cells.

Shikonin-induced apoptosis involves caspase-3 activity in a human bladder cancer cell line (T24)

Apoptosis is a process that leads to programmed cell death and also a therapeutic target of cancer. In this study, potential apoptotic effects of shikonin on human bladder cancer cells (T24) in vitro were evaluated. Apoptosis induction, cell viability and morphological changes were investigated and caspase-3 and -9 activity was determined by flow cytometric assay and reverse transcription-polymerase chain reaction. The results showed marked differences in G0/G1 cell cycle arrest and cell death of the T24 cells between shikonin treated and untreated groups. Within 72 hours of treatment, shikonin influenced the cyclin dependent kinase (CDK) and cyclin activity by increasing p21 and decreasing cyclin E, CDK2 and CDK4 protein levels. A marked increase was found in apoptosis induction when the T24 cells were treated with shikonin compared to the untreated group, also confirmed by flow cytometry assay. Shikonin also promoted caspase-3 activity, which led to the induction of caspase-activated DNase (CAD) and cleavage poly(ADP-ribose)polymerase. Furthermore, the shikonin-induced apoptosis of the T24 cells was markedly blocked by the broad-spectrum caspase inhibitor, z-VAD-fmk. Shikonin may be a potential agent for the treatment of bladder transitional cell carcinoma since it induces apoptosis through the activation of caspase-3 activity in T24 human bladder cancer cells.

Berberine induces apoptosis in human HSC-3 oral cancer cells via simultaneous activation of the death receptor-mediated and mitochondrial pathway

Evidence has accumulated that berberine is able to induce cell cycle arrest and apoptosis in many human cancer cell lines. However, there is no available information on the effects of berberine on human oral squamous cell carcinoma. In this study, the effects of berberine on cell growth, apoptosis and cell cycle regulation in human oral squamous carcinoma HSC-3 cells were examined. Berberine induced dose- and time-dependent irreversible inhibition of cell growth and cellular DNA synthesis. This was also confirmed by phase-contrast microscopy which showed that berberine induced morphological changes in HSC-3 cells. Propidium iodide/annexin V staining for flow cytometric analysis showed that berberine-induced apoptosis correlated with caspase-3 activation. Flow cytometric studies of the cell cycle distribution showed that berberine induced mainly G0/G1-phase arrest. Flow cytometric examinations also showed that berberine induced reactive oxygen species (ROS) and Ca2+ production, as well as the dysfunction of mitochondrial membrane potential (MMP), which were correlated with apoptosis. In conclusion, our data support that berberine initially induces an endoplasmic reticulum stress response based on ROS and Ca2+ production which is followed by dysfunctions of the mitochondria, resulting in apoptosis of these oral cancer HSC-3 cells. Prolonged exposure of the HSC-3 cells to berberine causes increased apoptosis through reduced levels of MMP, release of cytochrome c and activation of caspase-3.

Berberine inhibits WEHI-3 leukemia cells in vivo

Berberine, an isoquinoline alkaloid, has a wide range of pharmacological effects including anticancer activities, yet the exact effects on leukemia in vivo are unknown. Our previous studies have demonstrated that berberine induced cytotoxicity against murine leukemia WEHI-3 cells in vitro in a dose-dependent manner. In order to understand the berberine action against leukemia, the effect of berberine on WEHI-3 leukemia cells in vivo was studied. The results showed that Mac-3 and CD11b markers were reduced, indicating differentiation inhibition of the macrophages and granulocytes precursors. There was no affect on the CD14 marker but the CD19 marker that was indicating the promotion of the differentiation of the B-cells precursors. The weights of spleen samples from mice treated with berberine were found to be lower when compared to these from untreated animals.

Aloe-emodin affects the levels of cytokines and functions of leukocytes from Sprague-Dawley rats

Aloe-emodin has shown anti-neoplastic activity against some human cancer cell lines. This study aimed to explore the effects of aloe-emodin on the phagocytosis of macrophages, the activity of natural killer (NK) cells and the expression of cytokines in leukocytes from Sprague-Dawley rats. Leukocytes were collected, placed into culture plates and the functions of macrophages and NK cells and the percentage of viable cells were determined by flow cytometric analysis. Incubation of leukocytes with various concentrations of aloe-emodin caused a dose-dependent decrease of viable cells, a decrease of phagocytosis by macrophages, and a decrease of the activity of NK cells. Evaluation of cytokines in leukocytes by ELISA indicated that aloe-emodin increased the levels of interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. The results were also confirmed by PCR assay for the mRNA expression of the examined cytokines.

Ketoprofen-inhibited N-acetyltransferase activity and gene expression in human colon tumor cells

The activation of ketoprofen, which inhibits the outgrowth of azoxymethane-induced aberrant crypt foci in the rat colon, on the inhibition of arylamine N-acetyltransferase (NAT) activity (N-acetylation of substrates), gene expression (mRNA NAT) and 2-aminofluorene (AF)-DNA adduct formation was studied in a human colon tumor (adenocarcinoma) cell line (colo 205). Cellular cytosols (9000 xg supernatant) and intact colon tumor cells were used. The NAT activity in colo 205 cells was inhibited by ketoprofen in a dose- and time -dependent manner in both examined systems. The data also indicated that ketoprofen decreased the apparent value of V(max) of NAT enzymes, being a competitive inhibitor of NAT enzymes. The AF-DNA adduct formation in colo 205 cells was also decreased by ketoprofen. Based on the results from PCR, it was shown that ketoprofen affected mRNA NAT expression in human colon colo 205 cells. The cells were stained with anti-NAT antibody, then analyzed by flow cytometry. The results showed that ketoprofen decreased the percentage of cells stained by anti-NAT. This report is the first to demonstrate that ketoprofen inhibits human colon tumor cell NAT activity, gene expression and DNA adduct formation.

The role of Ca2+ in (-)-menthol-induced human promyelocytic leukemia HL-60 cell death

A human promyelocytic leukemia HL-60 cell line was selected to examine the effect of (-)-Menthol on cell death. Based on the results from morphological changes and the percentage of viable cells in HL-60 cells after treatment with various concentrations of (-)-Menthol, it was shown that (-)-Menthol induced cell death through necrosis, not apoptosis. No cell cycle arrest was found in HL-60 cells examined by flow cytometry analysis. Also, the DNA gel electrophoresis method showed that (-)-Menthol did not induce apoptosis in HL-60 cells. However, it was found that (-)-Menthol induced the production of Ca2+ in these examined cells, dose-dependently. When HL-60 cells were pretreated with the chelator (BAPTA) of Ca2+ for 3 hours before addition of (-)-Menthol to the culture, a decrease of Ca2+ production was observed. Under the same conditions, the percentage of viable HL-60 cells was increased. Apparently Ca2+ production is associated with the induction of (-)-Menthol-induced cell death.

The effects of emodin on the expression of cytokines and functions of leukocytes from Sprague-Dawley rats

Emodin has been reported to induce apoptosis in many human cancer cell lines, although its effects on leukocyte functions in vitro have not been demonstrated Therefore, the purpose of this study was to assess the effect of emodin on the phagocytosis of macrophages, the activity of natural killer cells and the expression of cytokines in leukocytes from Sprague-Dawley rats. Leukocytes, isolated from rats, were placed into culture plates for incubation with or without various concentrations of emodin for 1-6 hours and the functions of macrophages and natural killer cells were evaluated by flow cytometric analysis. The results indicated that emodin caused a decrease in phagocytosis of macrophages after treatment for up to 4 hours but 6-hour treatments led to an increase in the phagocytosis of macrophages. Further, emodin increased the activity of natural killer cells, both effects being dose-dependent. The levels of cytokines from the examined leukocytes were evaluated by ELISA and the results indicated that emodin increased the levels of IL-1beta and TNF-alpha, results which were confirmed by PCR assay for the mRNA expressions of the examined cytokines.

Diallyl disulfide inhibits N-acetyltransferase activity and gene expression in human esophagus epidermoid carcinoma CE 81T/VGH cells

Individuals can be classified into rapid or slow acetylators based on the N-acetyltransferase (NAT) activity which is believed to affect cancer risk that is related to environmental carcinogen exposure. Diallyl disulfide (DADS) is a naturally occurring organosulfur compound, from garlic (Allium sativum), which exerts anti-neoplasm activity. In this study, we investigated the inhibitory effects of DADS on NAT activity and gene expresseion (NAT mRNA) in human esophagus epidermoid carcinoma CE 81T/VGH cells. NAT activity was measured by the amounts of N-acetylation of 2-aminofluorene (AF) and non-acetylation of AF by high performance liquid chromatography on cells treated with or without DADS. The amounts of NAT enzymes were examined and analyzed by Western blot. NAT gene expression (NAT mRNA) was examined by polymerase chain reaction and cDNA microarray. DADS decreased the amount of N-acetylation of AF in human esophagus epidermoid carcinoma CE 81T/VGH cells in a dose-dependent manner. Western blot analysis indicated that DADS decreased the levels of NAT protein in CE 81T/VGH cells. PCR and cDNA microarray experiments showed that DADS affected NAT1 mRNA expression in CE 81T/VGH cells. DADS affect NAT activity due to the inhibition of gene expression (NAT1 mRNA) and the decreasing of the protein levels of NAT in CE 81T/VGH cells.

Wogonin inhibits N-acetyltransferase activity and gene expression in human leukemia HL-60 cells

It is well documented that arylamine carcinogens are N-acetylated by cytosolic N-acetyltransferase (NAT) enzyme. NAT plays an important role in the metabolizing of those arylamine compounds. 2-Aminofluorene (AF) is an arylamine carcinogen which has been demonstrated to induce carcinogenesis in laboratory animals. Our previous study has shown that a human promyelocytic leukemia cell line, HL-60, displays NAT activity. The purpose of the present study was to determine whether or not wogonin could affect the N-acetylation of AF in HL-60. N-acetylated and non-N-acetylated AF were determined by using high performance liquid chromatography. Wogonin displayed a dose-dependent inhibition of NAT activity in cytosols and intact cells. Wogonin also decreased AF-DNA adduct formation in these cells. The effects of wogonin on the NAT enzymes levels were also examined by Western blotting and flow cytometry and the changes of NAT gene expression were examined by polymerase chain reaction (PCR) and cDNA microarray. The results demonstrated that wogonin inhibited NAT1 mRNA gene expression and the level of NAT enzyme in HL-60 cells. This is the first demonstration that wogonin affects human leukemia cells' NAT activity in vitro.

Paclitaxel inhibits N-acetyltransferase activity and gene expression in human stomach tumor cells (SC-M1)

Evidence has shown that N-acetyltransferase (NAT) acetylated 2-aminofluorene (AF) to form N-acetyl-2-aminofluorene (AAF). Then it was metabolized by cytochrome P450 (CYP) enzyme to form ring or N-hydroxylated metabolites. Sulfotransferase and other enzymes participated to form the ultimate metabolites which bind to DNA to form DNA-AF adducts which may have led to cancer development. The aim of the present study is to demonstrate whether paclitaxel (taxol) can inhibit the NAT activity, NAT gene expression and DNA-AF adduct formation in human stomach tumor cell line (SC-M1). The activity of NAT was determined by high performance liquid chromatography (HPLC) assaying for the amounts of acetylated AF (AAF) or p-aminobenzoic acid (N-Ac-PABA) and nonacetylated AF or PABA. While SC-M1 cell cytosols were used for examining NAT activity, intacts cells were used for examining all three: NAT activity, gene expression and DNA-AF adduct formation. As compared with the control group, the paclitaxel- treated group showed decreased NAT activity and DNA-AF adduct formation in SC-M1 cells and the decrease was dose-dependent. The results also indicated that paclitaxel decreased the apparent values of K(m) and V(max) from SC-M1 cells in both cytosol and intact cells. Palitaxel did significantly affect NAT gene expression (NAT1 mRNA) in SC-M1 cells.

A role for MAP kinase in regulating ectodomain shedding of APLP2 in corneal epithelial cells

We previously reported an increased secretion of amyloid precursor-like protein 2 (APLP2) in the healing corneal epithelium. The present study sought to investigate signal transduction pathways involved in APLP2 shedding in vitro. APLP2 was constitutively shed and released into culture medium in SV40-immortalized human corneal epithelial cells as assessed by Western blotting, flow cytometry, and indirect immunofluorescence. Activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) caused significant increases in APLP2 shedding. This was inhibited by staurosporine and a PKC-epsilon-specific, N-myristoylated peptide inhibitor. Epidermal growth factor (EGF) also induced APLP2 accumulation in culture medium. Basal APLP2 shedding as well as that induced by PMA and EGF was blocked by a mitogen-activated protein kinase (MAPK) kinase inhibitor, U-0126. Our results suggest that MAPK activity accounts for basal as well as PKC- and EGF-induced APLP2 shedding. In addition, PKC-epsilon may be involved in the induction of APLP2 shedding in corneal epithelial cells.

Corneal epithelial tight junctions and their response to lipopolysaccharide challenge

PURPOSE

To investigate the expression and cellular distribution of putative tight junction (TJ) proteins occludin, ZO-1, ZO-2, and claudin-1 in rat corneal epithelium and alterations of TJs in cultured human corneal epithelial cells in response to lipopolysaccharide (LPS) challenge.

METHODS

Immunohistochemistry was used to determine tissue distribution of occludin, ZO-1, ZO-2, and claudin-1 in the rat cornea. Reverse transcription-polymerase chain reaction was used to reveal the expression of mRNAs for claudins in simian virus (SV)40-immortalized human corneal epithelial (THCE) cells. To assess epithelial response to LPS challenge, THCE cells were cultured on the upper chamber of Transwell filters (Costar, Cambridge, MA), transepithelial electrical resistance (TER) was measured using a voltohmmeter. Immunocytochemistry and immunoblotting were used to assess alteration in the levels and localization of TJ-associated proteins occludin, ZO-1, and ZO-2 in LPS-treated THCE cells.

RESULTS

Occludin, ZO-1, and ZO-2 were found at the cell borders of the superficial layer, whereas claudin-1 was localized mainly in the basal and wing cell layers of rat corneal epithelium. In addition to claudin-1, the transcripts for several other isotypes of claudins-2, -3, -7, -9, -14, and -15 were identified in THCE cells. Treatment of cultured THCE cells with LPS caused a dose- and time-dependent increase in monolayer permeability as assessed by TER measurements. The maximal decrease of TER was observed at approximately 6 to 9 hours after LPS challenge. The TER was then recovered gradually and returned to baseline after 24 hours. Examination of specific proteins associated with TJs by immunoblot analysis and immunomicroscopy revealed changes in the expression levels and localization of some of these proteins after their exposure to LPS. Specifically, LPS challenge resulted in a decrease in the levels of ZO-1 and ZO-2 compared with untreated cells. Reduction of the ZO-2 level was associated with the disappearance of ZO-2 staining from cell borders in 6-hour LPS-treated cells.

CONCLUSIONS

Occludin, ZO-1, and ZO-2, but not claudin-1, are components of corneal epithelial TJs. LPS induces breakdown of the epithelial barrier through disruption of TJs, and ZO-1 and ZO-2 are targets for the induction.

Corneal organ culture model for assessing epithelial responses to surfactants

The main goal of the present study was to investigate the response of cultured bovine corneas to the application of irritant substances and its potential use for predicting ocular irritancy in humans. We hypothesized that chemicals causing eye irritation may induce disruption of epithelial tight junctions and trigger cell stress responses modulated via transcription factors such as AP-1 and NF-kappaB. A simple air-lifted corneal organ culture system was used as an ex vivo model for ocular irritancy test. The effects of two surfactants, sodium dodecyl sulfate (SDS) and benzalkonium chloride (BAK), on corneal epithelial permeability and DNA-binding activity of AP-1 and NF-kappaB were studied in cultured bovine corneas. Both SDS and BAK induced tight junction disruption and increased permeability of corneal epithelium assessed using surface biotinylation in a concentration- and time-dependent manner. An increase in DNA-binding activity measured using electrophoretic mobility shift assay was observed when cultured corneas were treated with surfactants at concentrations causing minimal to mild ocular irritation, indicating epithelial cell stress response. Furthermore, exposure of cultured corneas to SDS or BAK at concentrations causing severe ocular irritancy resulted in a decrease in DNA-binding activity of these transcription factors in epithelial cells. These results indicate that the combination of corneal organ culture and measurements of corneal epithelial permeability and DNA-binding activity of stress-response transcription factors following chemical exposure has the potential to be used as a mechanistically based alternative to in vivo animal testing.

Differential expression of MT1-MMP (MMP-14) and collagenase III (MMP-13) genes in normal and wounded rat corneas

PURPOSE

Several members of the matrix metalloproteinase (MMP) group have been identified in the rat cornea during corneal wound healing. The aim of the present study was to identify additional members of the MMP gene family in the rat cornea and localize the expression of membrane type-1 matrix metalloproteinase (MT1-MMP; MMP-14) and collagenase III (MMP-13) in normal and wounded corneas.

METHODS

Adult rats underwent laser keratectomy on the right eye. Unwounded left eyes were normal controls. Corneas were collected and processed at different times post-wounding. Reverse transcription-polymerase chain reaction (RT-PCR) and DNA sequencing were used to discover the MMP genes expressed in the corneas. In situ hybridization was performed to localize the mRNA expression of MMP-14 and MMP-13.

RESULTS

MMP-13 mRNA was detected in epithelial cells of wounded corneas, but not in normal controls; MMP-14 was found in both normal and wounded corneas. MMP-14 mRNA was expressed predominantly in the stromal keratocytes and rarely in the basal epithelial cells in normal and wounded corneas. MMP-13 mRNA was localized exclusively to basal cells of the epithelium at the wounded area from 6 hours to 3 days after wounding.

CONCLUSIONS

MMP-14 and MMP-13 expression in rat corneas parallels that of gelatinases A and B, respectively. MMP-13 may play an important role in the gelatinase B-associated proteolytic cascade that allows rapid turnover of the extracellular matrix (ECM) components during corneal wound healing. MMP-14 may contribute to removing abnormal ECM components through activation of gelatinase A in rat corneas.

A novel epithelial wound-related gene is abundantly expressed in developing rat cornea and skin

PURPOSE

We previously used mRNA differential display and identified a novel gene that is up regulated in the healing corneal epithelium. To understand the potential in vivo role of this gene, termed T4a, we cloned the full-length T4a cDNA and investigated its temporal and spatial transcription expression in healing rat corneas, as well as in developing cornea and skin.

METHODS

The displayed T4a cDNA was used to identify clones from a rat cDNA library derived from healing corneal epithelia. The cDNA clones were sequenced and the sequence was analyzed with the Blast program. In situ hybridization was performed using digoxigenin-labeled riboprobes and cryostat sections from healing and developing cornea as well as skin.

RESULTS

The T4a cDNA had 2538 bp with an open reading frame of 2178 bp, consistent with a conceptual translation product of 725 amino acid residues, a calculated molecular mass of 83.1 kD and theoretical pI of 6.93. Although T4a exhibited no sequence homology with known genes in the GenBank, it matched a large number of Expressed Sequence Tags (ESTs) from human, mouse and rat tissue cDNA libraries; more than half of the murine T4a ESTs were from embryonic DNA libraries. Sequence analysis revealed numerous phosphorylation and myristoylation sites in the deduced amino acid sequence of T4a. In the wounded rat cornea, intensive T4a mRNA staining was observed in the epithelium at all stages of re-epithelialization indicating that the expression of T4a is wound-related. In 7 day old mice, an abundant level of T4a transcripts was found in the epidermis and hair follicles, as well as in the corneal epithelial layer. High levels of T4a mRNA staining persisted in the developing postnatal corneal epithelia. In contrast, weak mRNA staining was only detected in the basal layer of the adult epidermis and corneal epithelium.

CONCLUSION

These results indicate that T4a expression correlates with re-epithelialization of the cornea and maturation of the cornea and skin, suggesting a role for this gene in epithelial development, differentiation, and wound healing.

Identification of androgen receptor protein and 5alpha-reductase mRNA in human ocular tissues

BACKGROUND/AIMS

Androgens have been reported to influence the structural organisation, functional activity, and/or pathological features of many ocular tissues. In addition, these hormones have been proposed as a topical therapy for such conditions as dry eye syndromes, corneal wound healing, and high intraocular pressure. To advance our understanding of androgen action in the eye, the purpose of the present study was twofold: firstly, to determine whether tissues of the anterior and posterior segments contain androgen receptor protein, which might make them susceptible to hormone effects following topical application; and, secondly, to examine whether these tissues contain the mRNA for types 1 and/or 2 5alpha-reductase, an enzyme that converts testosterone to the very potent metabolite, dihydrotestosterone.

METHODS

Human ocular tissues and cells were obtained and processed for histochemical and molecular biological procedures. Androgen receptor protein was identified by utilising specific immunoperoxidase techniques. The analysis of type 1 and type 2 5alpha-reductase mRNAs was performed by the use of RT-PCR, agarose gel electrophoresis, and DNA sequence analysis. All immunohistochemical evaluations and PCR amplifications included positive and negative controls.

RESULTS

These findings show that androgen receptor protein exists in the human lacrimal gland, meibomian gland, cornea, bulbar and forniceal conjunctivae, lens epithelial cells, and retinal pigment epithelial cells. In addition, our results demonstrate that the mRNAs for types 1 and 2 5alpha-reductase occur in the human lacrimal gland, meibomian gland, bulbar conjunctiva, cornea, and RPE cells.

CONCLUSION

These combined results indicate that multiple ocular tissues may be target sites for androgen action.

Amyloid precursor-like protein 2 promotes cell migration toward fibronectin and collagen IV

Previous studies have established that in response to wounding, the expression of amyloid precursor-like protein 2 (APLP2) in the basal cells of migrating corneal epithelium is greatly up-regulated. To further our understanding of the functional significance of APLP2 in wound healing, we have measured the migratory response of transfected Chinese hamster ovary (CHO) cells expressing APLP2 isoforms to a variety of extracellular matrix components including laminin, collagen types I, IV, and VII, fibronectin, and heparan sulfate proteoglycans (HSPGs). CHO cells overexpressing either of two APLP2 variants, differing in chondroitin sulfate (CS) attachment, exhibit a marked increase in chemotaxis toward type IV collagen and fibronectin but not to laminin, collagen types I and VII, and HSPGs. Cells overexpressing APLP2-751 (CS-modified) exhibited a greater migratory response to fibronectin and type IV collagen than their non-CS-attached counterparts (APLP2-763), suggesting that CS modification enhanced APLP2 effects on cell migration. Moreover, in the presence of chondroitin sulfate, transfectants overexpressing APLP2-751 failed to exhibit this enhanced migration toward fibronectin. The APLP2-ECM interactions were also explored by solid phase adhesion assays. While overexpression of APLP2 isoforms moderately enhanced CHO adhesion to laminin, collagen types I and VII, and HSPGs lines, especially those overexpressing APLP2-751, exhibited greatly increased adhesion to type IV collagen and fibronectin. These observations suggest that APLP2 contributes to re-epithelialization during wound healing by supporting epithelial cell adhesion to fibronectin and collagen IV, thus influencing their capacity to migrate over the wound bed. Furthermore, APLP2 interactions with fibronectin and collagen IV appear to be potentiated by the addition of a CS chain to the core proteins.

Upregulation of xanthine oxidase by lipopolysaccharide, interleukin-1, and hypoxia. Role in acute lung injury

LPS and selected cytokines upregulate xanthine dehydrogenase/xanthine oxidase (XDH/XO) in cellular systems. However, the effect of these factors on in vivo XDH/XO expression, and their contribution to lung injury, are poorly understood. Rats were exposed to normoxia or hypoxia for 24 h after treatment with LPS (1 mg/kg) and IL-1beta (100 microg/kg) or sterile saline. Lungs were then harvested for measurement of XDH/XO enzymatic activity and gene expression, and pulmonary edema was assessed by measurement of the wet/dry lung weight ratio (W/D). Although treatment with LPS + IL-1beta or hypoxia independently produced a 2-fold elevation (p < 0. 05 versus exposure to normoxia and treatment with saline) in lung XDH/XO activity and mRNA, the combination of LPS + IL-1beta and hypoxia caused a 4- and 3.5-fold increase in these values, respectively. XDH/XO protein expression was increased 2-fold by hypoxia alone and 1.3-fold by treatment with LPS + IL-1beta alone or combination treatment. Compared with normoxic lungs, W/D was significantly increased by exposure to hypoxia, LPS + IL-1beta, or combination treatment. This increase was prevented by treatment of the animals with tungsten, which abrogated lung XDH/XO activity. In conclusion, LPS, IL-1beta, and hypoxia significantly upregulate lung XDH/XO expression in vivo. The present data support a role for this enzyme in the pathogenesis of acute lung injury.

Intracellular generation of reactive oxygen species in endothelial cells exposed to anoxia-reoxygenation

Reactive oxygen species (ROS) play an important role in the pathogenesis of ischemia-reperfusion injury. Extracellular H2O2 generation from bovine pulmonary artery endothelial cells (EC) is known to increase in response to anoxia-reoxygenation (A-R). To determine potential sources of intracellular ROS formation in EC in response to A-R, a fluorometric assay based on the oxidation of 2',7'-dichlorofluorescin was used. Intracellular ROS production declined 40% during 6 h of anoxia (P < 0.05). After A-R, the rates of intracellular ROS formation increased to 148 +/- 9% (P < 0.001) that of normoxic EC (100 +/- 3%). In EC exposed to A-R, allopurinol and NG-methyl-L-arginine (L-NMMA), inhibitors of xanthine oxidase (XO) and nitric oxide synthase (NOS), respectively, reduced intracellular ROS formation by 25 +/- 1% (P < 0.001) and 36 +/- 4% (P < 0.01). Furthermore, at low doses (i.e., 20 microM), deferoxamine and diethylenetriaminepentaacetic acid (DTPA) significantly inhibited intracellular ROS formation. However, at 100 microM, only deferoxamine caused further reduction in DCF fluorescence. In summary, EC respond to A-R by generating increased amounts of XO- and NOS-derived intracellular ROS. The inhibition, to a similar extent, caused by allopurinol and L-NMMA, as well as the effect of deferoxamine and DTPA suggest that the ROS detected is peroxynitrite. Based on these findings and previous work, we conclude that EC generate ROS in response to A-R from at least two different sources: a plasma membrane-bound NADPH oxidase-like enzyme that releases H2O2 extracellularly and XO, which generates intracellular O2-, which in turn may react with nitric oxide to form peroxynitrite.

Intrinsic cervical spinal cord deformation on MRI: "the distorted 'H' sign"

Extrinsic and intrinsic pathologic processes involving the spinal cord can affect its gross morphologic appearance. Contour-related abnormalities of the spinal cord can be determined by both noninvasive and invasive imaging techniques. Detailing internal dysmorphism of the spinal cord is more difficult to determine because the internal architecture of the cord is not usually visualized. Now magnetic resonance (MR) imaging can readily demonstrate the central "H" configuration of the normal spinal gray matter on axial T2* gradient-recall echo pulse sequences; thus, it should also be capable of demonstrating distortions of it. We initially reviewed 55 abnormal cervical spine 1.5-T MR imaging studies. Of 37 large lesions, 31 deformed the "H" whereas 18 small lesions did not. To compare potential differences in visualization of the "H" by MR scanners of different field strengths (1.5-0.5 T), a total of 125 additional patients were reviewed at different State University of New York (SUNY) sites. Visualization of the "H" varied from 51.4% at 1.5 T to 18.4% at 0.5 T. As resolution of the spinal cord increases on MR imaging, it becomes possible to more accurately map the altered cord "interior," which may have a detectable clinical (neurologic) counterpart.

Determination of xanthine dehydrogenase mRNA by a reverse transcription-coupled competitive quantitative polymerase chain reaction assay: regulation in rat endothelial cells by hypoxia and hyperoxia

The enzyme system xanthine dehydrogenase (XD):xanthine oxidase, which generates the superoxide anion as a by-product of action on endogenous substrates, is believed to play a role in mediating pathophysiological changes through its contribution to total superoxide production. To aid with analysis of factors that regulate XD, we have developed a reverse transcription (RT)-coupled competitive quantitative polymerase chain reaction (PCR) assay which enables XD mRNA to be determined from small amounts of cultured cells where constitutive XD levels are low. A homologous insertion mutant of wild-type XD cDNA was prepared and used as an internal standard to normalize intersample PCR efficiency differences. XD mRNA levels determined by RT-PCR also were normalized to tubulin mRNA to compensate for RT differences and loading effects among samples. We report that XD mRNA levels, determined by RT-PCR, were increased twofold in hypoxic (3% oxygen) rat pulmonary microvascular endothelial cells relative to normoxic controls (20% oxygen). Conversely, XD mRNA was decreased threefold within 24 h under hyperoxic (95% oxygen) conditions. These data support the hypothesis that XD is regulated by oxygen tension in the pulmonary vasculature.

Regulation of intracellular xanthine oxidase by endothelial-derived nitric oxide

We have previously shown that nitric oxide (NO) donors, such as nitrosoglutathione, inhibit endothelial cell (EC) xanthine dehydrogenase (XD)/xanthine oxidase (XO) activity. The purpose of this study was to assess whether endothelial-derived NO plays any role in the regulation of intracellular XD/XO. We exposed rat pulmonary microvascular EC to L-arginine (precursor of NO) or inhibitors of nitric oxide synthase (NOS), i.e., NG-nitro-L-arginine methyl esther (L-NAME) and NG-nitro-L-arginine, in conditions of normoxia, hypoxia, and hypoxia followed by reoxygenation. Hypoxia alone caused a 1.9- and a 6.6-fold increase in XO and a 5-fold increase in XO + XD activities after 24 and 48 h of exposure, respectively. The combination of hypoxia and L-NAME (300 microM) treatment amounted at 48 h to a 10- and 7.5-fold increase in XO and XO + XD activities, respectively, compared with normoxic untreated cells. L-NAME also prevented the decline in XD/XO activity that occurred in untreated EC after hypoxia-reoxygenation. On the other hand, treatment with L-arginine caused a dose-dependent decrease in XD/XO activity in hypoxic EC compared with cells provided with L-arginine-free medium. In separate experiments, we assessed the role of L-arginine supplementation on the in vivo regulation of lung XD/XO by exposing male adult Sprague-Dawley rats for a period of 5 days to a hypoxic hypobaric atmosphere (0.5 atm). Exposure to hypoxia produced a significant increase in lung tissue XO activity and an increase in the ratio of XO to XD. L-Arginine supplementation in the drinking water prevented the increase in lung XO and the XO-to-XD ratio in hypoxic rats and caused a significant decrease in XO and XD in rats exposed to normoxia. In conclusion, this study suggests that endogenous NO has a significant role in the regulation of XD/XO both in vitro and in vivo. By inhibiting XD/XO activity, NO may have a modulating effect in conditions of hypoxia and hypoxia-reoxygenation, where this enzyme is thought to be important.

Quantification of polymerase chain reaction products: enzyme immunoassay based systems for digoxigenin- and biotin-labelled products that quantify either total or specific amplicons

Enzyme immunoassays were developed for quantification of polymerase chain reaction (PCR) products, referred to as amplicons. Amplicons were dual labelled simultaneously by enzymatic incorporation of digoxigenin and biotin during PCR. For total amplicon quantification, Microfluor B polystyrene wells, compatible with chemiluminescent detection, were coated with streptavidin. Dual labelled amplicons were bound, treated with anti-digoxigenin antibody conjugated to alkaline phosphatase to complete the two-site sandwich immunoassay configuration, and detected by the chemiluminescence generated upon hydrolysis of a phosphate substituted dioxetane substrate, AMPPD. For specific amplicon quantification, the Microfluor B wells were coated with an unlabelled DNA probe complementary to the labelled amplicon target. Subsequent steps were performed as described above. This assay detects 2 pg of specifically amplified DNA. Chemiluminescent detection provides a linear range of four orders of magnitude for amplicon quantification. The non-radioactive labels are safe and stable. PCR as described here obviates the need for labelled primers and constitutes the initial report of concurrent dual non-radioactive labelling of DNA by a DNA polymerase.

Regulation of bovine endothelial constitutive nitric oxide synthase by oxygen

Oxygen (O2) may regulate pulmonary vascular resistance through changes in endothelial nitric oxide (NO) production. To determine whether constitutive NO synthase (cNOS) is regulated by O2, we assessed cNOS expression and activity in bovine pulmonary artery endothelial cells exposed to different concentrations of O2. In a time-dependent manner, changes in O2 concentration from 95 to 3% produced a progressive decrease in cNOS mRNA and protein levels resulting in 4.8- and 4.3-fold reductions after 24h, respectively. This correlated with changes in cNOS activity as determined by nitrite measurements. Compared with 20% O2, cNOS activity was increased 1.5-fold in 95% O2 and decreased 1.9-fold in 3% O2. A decrease in O2 concentration from 94 to 3% shortened cNOS mRNA half-life from 46 to 24 h and caused a 20-fold repression of cNOS gene transcription. Treatment with cycloheximide produced a threefold increase in cNOS mRNA at all O2 concentrations, suggesting that cNOS mRNA expression is negatively regulated under basal condition. We conclude that O2 upregulates cNOS expression through transcriptional and post-transcriptional mechanisms. A decrease in cNOS activity in the presence of low O2 levels, therefore, may contribute to hypoxia-induced vasoconstriction in the pulmonary circulation.

Effect of nitric oxide and cell redox status on the regulation of endothelial cell xanthine dehydrogenase

We have previously reported that endothelial cell (EC) xanthine dehydrogenase/xanthine oxidase (XD/XO) activity correlates inversely with the O2 tension to which the cells are exposed. Whether this effect is related to the production of reactive O2 species is unclear. We exposed bovine pulmonary artery EC to various conditions that altered the redox status of the cells: 1) hypoxia (3% O2) and normoxia (20% O2); 2) menadione (MEN), known to generate O2 radicals; 3) catalase (CAT) and reduced glutathione (GSH), which detoxify H2O2; and 4) various NO-generating systems. Changes in intracellular XO and XO + XD activities were correlated with rates of extracellular H2O2 release from the same cells. Conditions that decreased extracellular H2O2 release (hypoxia, CAT, and GSH) produced significant and parallel increases in intracellular XO and XO + XD activities in a time-dependent fashion. MEN treatment increased extracellular release of H2O2 and subsequently reduced intracellular XO and XO + XD activities. NO-generating agents did not change extracellular release of H2O2 but significantly reduced XO and XO + XD activities. The latter effect was prevented by reduced hemoglobin. Scavengers of hydroxyl radicals reversed the inhibition of XO and XO + XD activities produced by MEN but not that produced by NO. While NO significantly inhibited XD/XO activity from rat epididymal fat pad, it did not affect XD/XO mRNA expression in these cells. We conclude that intracellular XD/XO activity is sensitive to changes in oxidant-generating and protective systems. Inhibition of XD/XO activity by NO may be mediated through direct binding of NO to the enzyme iron-sulfur moiety or to its sulfhydryl groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical knowledge systems: applications to telemedicine

The application and form of electronically stored medical knowledge has a direct impact on the design of any healthcare delivery system. For those who plan for remote medical care or who work at the disaster relief level, there are specific requirements which will dictate the type of knowledge required and the vehicle best suited to deliver that information. The PC based multimedia biomedical library developed for NASA was originally intended for long-term space missions where complete isolation from each support was a distinct possibility. The library is a combination of traditional references and secondary databases structured within a primary care physician's workstation. The integration of the library and a point-of-care system allows optimal use of both resources and provides a basic building block for telemedicine networking.