Epstein-Barr Virus Early Antigen Research Articles

Cancer preventive agents, Part 2: Synthesis and evaluation of 2-phenyl-4-quinolone and 9-oxo-9,10-dihydroacridine derivatives as novel antitumor promoters

2-Phenyl-4-quinolone and 9-oxo-9,10-dihydroacridine derivatives were synthesized and screened as potential antitumor promoters by examining the ability of the compounds to inhibit Epstein–Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Interestingly, compounds 14, 15, and 17 showed similar inhibitory effects (89–92%, 66–69%, and 24–29% at 1000, 500, and 100mol ratio to TPA, respectively) against EBV-EA with potencies comparable to those of glycyrrhetic acid, a known natural antitumor-promoter.

Cancer Chemopreventive Activity of Lupane‐ and Oleanane‐Type Triterpenoids from the Cones of Liquidamber styraciflua

In a search for cancer chemopreventive agents from natural sources, four lupane-type and seven oleanane-type triterpenoids, and ten synthetic analogs were screened as potential anti-tumor promoters by using the in vitro short-term 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus early antigen (EBV-EA) activation assay. Among them, 25-acetoxy-3alpha-hydroxyolean-12-en-28-oic acid (1) and 3beta,25-epoxy-3alpha-hydroxylup-20(29)-en-28-oic acid (2) were examined for anti-tumor promoting activity in a two-stage carcinogenesis assay on mouse skin with 7,12-dimethylbenz[a]anthracene (DMBA) and TPA as promoter. 25-Acetoxy-3alpha-hydroxyolean-12-en-28-oic acid (1) and 3beta,25-epoxy-3alpha-hydroxylup-20(29)-en-28-oic acid (2) showed moderate inhibitory activities.

Comparison of three different serological techniques for primary diagnosis and monitoring of nasopharyngeal carcinoma in two age groups from Tunisia

Nasopharyngeal carcinoma (NPC) in Tunisia is characterized by its bimodal age distribution involving juvenile patients of 10-24 years and adult patients of 40-60 years. Three serological techniques were compared for primary diagnosis (N = 117) and post-treatment monitoring (N = 21) of NPC patients separated in two age groups. Immunofluorescence assay (IFA) was used as the "gold standard" for detection of IgG and IgA antibodies reactive with Epstein-Barr virus (EBV) early (EA) and viral capsid (VCA) antigens. Results were compared with ELISA measuring IgG and IgA antibody reactivity to defined EBNA1, EA, and VCA antigens. Immunoblot was used to reveal the molecular diversity underlying the anti-EBV IgG and IgA antibody responses. The results indicate that young NPC patients have significantly more restricted anti-EBV IgG and IgA antibody responses with aberrant IgG VCA/EA levels in 78% compared to 91.7% in elder patients. IgA VCA/EA was detected in 50% of young patients versus 89.4% for the elder group (P < 0.001). Immunoblot revealed a reduced overall diversity of EBV antigen recognition for both IgG and IgA in young patients. A good concordance was observed between ELISA and IFA for primary NPC diagnosis with 81-91% overall agreement. Even better agreement (95-100%) was found for antibody changes during follow-up monitoring, showing declining reactivity in patients in remission and increasing reactivity in patients with persistent disease or relapse. ELISA for IgA anti-VCA-p18 and immunoblot proved most sensitive for predicting tumor relapse. VCA-p18 IgA ELISA seems suitable for routine diagnosis and early detection of NPC complication.

Antitumor-Promoting Effects of New Sesquiterpenes fromCrossopetalum tonduzii

Seven new sesquiterpenes (1-7) with a 'dihydro-beta-agarofuran' (= 5,11-epoxy-5beta,10alpha-eudesmane) skeleton were isolated from Crossopetalum tonduzii. Their structures were elucidated spectroscopically, especially by means of homo- and heteronuclear NMR correlation (COSY, ROESY, HSQC, and HMBC). The absolute configurations of the new compounds were determined by circular dichroism (CD) studies and by chemical correlations via the derivatives 8-11. The new compounds showed moderate antitumor-promoting effects with respect to the activation of the Epstein-Barr virus early antigen (EBV-EA).

Chemical constituents of Murraya siamensis: three coumarins and their anti-tumor promoting effect

Isolation and structure elucidation of three coumarins, murrayacoumarins A, B, and C, together with eight known coumarins, from the leaves of Murraya siamensis C raib collected in Thailand are described. Results of a primary screening of inhibitory effects of seven of these compounds on 12- O-tetradecanoylphorbol-13-acetate-induced Epstein–Barr virus early antigen activation in Raji cells are also presented.

Azaphilones, Furanoisophthalides, and Amino Acids from the Extracts of Monascus pilosus-Fermented Rice (Red-Mold Rice) and Their Chemopreventive Effects

Six azaphilones, monascin (1), ankaflavin (2), rubropunctatin (3), monascorburin (4), rubropunctamine (5), and monascorburamine (6), two furanoisophthalides, xanthomonasin A (7) and xanthomonasin B (8), and two amino acids, (+)-monascumic acid (9) and (-)-monascumic acid (10), isolated from the extracts of Monascus pilosus-fermented rice (red-mold rice) were evaluated for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice, on the induction of Epstein-Barr virus early antigen (EBV-EA) by TPA in Raji cells, and on the activation of (+/-)-(E)-methyl-2[(E)-hydroxy-imino]-5-nitro-6-methoxy-3-hexemide (NOR 1), a nitric oxide (NO) donor. Among the compounds tested, seven compounds (1-6 and 10) on TPA-induced inflammation, and six compounds (1, 3-5, 9, and 10) on EBV-EA activation, exhibited potent inhibitory effects. All of the compounds tested showed moderate inhibitory effects on NOR 1 activation.

Antitubercular Activity and Inhibitory Effect on Epstein-Barr Virus Activation of Sterols and Polyisoprenepolyols from an Edible Mushroom, Hypsizigus marmoreus

Seven sterols (1-7) and eight polyisoprenepolyols (8-15), isolated from the non-saponifiable lipid fraction of the dichloromethane extract of an edible mushroom, Hypsizigus marmoreus (Buna-shimeji), were tested for their antitubercular activity against Mycobacterium tuberculosis strain H37Rv using the Microplate Alamar Blue Assay (MABA). Six sterols (2-7) and two polyisoprenepolyols (8, 12) showed a minimum inhibitory concentration (MIC) in the range of 1-51 microg/ml, while the others (1, 9-11, 13-15) were inactive (MIC>128 microg/ml). The seven sterols (1-7) and three polyisoprenepolyols (8, 10, 12) were further evaluated for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Sterols 6 and 7 showed potent inhibitory effects while preserving the high viability of Raji cells.

Antitumor-Promoting Activity of Coumarins fromCitrusPlants

In order to identify antitumor-promoting agents, we performed primary in vitro screening of 31 coumarins isolated from 11 plants of the Citrus species (Rutaceae), examining their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Some of the 8-substituted coumarins, 8-formyl-7-hydroxycoumarin (5), osthenol (7), demethylauraptenol (8), osthenon (9) and dihydroosthenon (10), were found to significantly inhibit EBV-EA activation (IC50: 129-207 mol ratio/32 pmol TPA). Osthenol (7) exhibited a marked inhibitory effect on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test.

Anti-inflammatory and Antitumor-Promoting Effects of the Triterpene Acids from the Leaves of Eriobotrya japonica

Sixteen triterpene acids, viz., five of the oleanane-type (1-5), nine of the ursane-type (6-14), and two of the lupane-type (15, 16), were isolated and identified from the ethyl acetate-soluble fraction of the methanol extract of the leaves of loquat, Eriobotrya japonica LINDL. (Rosaceae). Twelve of these compounds, 1-4, 6, 8-13, and 15, were evaluated for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation (1 microg/ear) in mice. All the compounds tested showed a marked anti-inflammatory effect, with a 50% inhibitory dose (ID50) of 0.03-0.43 mg per ear. In addition, an evaluation against the Epstein-Barr virus early antigen (EBV-EA) activation induced by TPA for all of the compounds, 12 and 13 showed potent inhibitory effects on EBV-EA induction. Furthermore, euscaphic acid (12) exhibited marked antitumor-promoting activity in an in vivo two-stage carcinogenesis test of mouse tumor by using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter.

Correlation between reduction potentials and inhibitory effects on Epstein–Barr virus activation of poly-substituted anthraquinones

As a continuation of our studies using natural and synthetic products as cancer chemopreventive agents, we examined the reduction potentials of some poly-substituted anthraquinones in phosphate buffer at pH 7.2 by means of cyclic voltammetry. A definite correlation has been found between the reduction potentials and the inhibitory effects of the poly-substituted anthraquinones on Epstein–Barr virus early antigen activation. It has been further shown that the correlation can be enhanced by introducing log P as an additional parameter.

Anti-tumor-promoting activity of simple models of galactoglycerolipids with branched and unsaturated acyl chains

Six new galactoglycerolipid analogs, in which one or two 4-methylpentanoyl or trans-2-butenoyl groups are linked to the 2- O-β- d-galactosylglycerol skeleton, were tested for their anti-tumor-promoting activity using a short-term in vitro assay for Epstein–Barr virus early antigen (EBV-EA) activation. All these compounds were more active than their linear or saturated reference compounds in inhibiting the EBV activation promoted by the tumor promoter 12- O-tetradecanoylphorbol-13-acetate (TPA), the diester 1- O-(4-methylpentanoyl)-2- O-[6- O-(4-methylpentanoyl)-β- d-galactopyranosyl]- sn-glycerol resulting the most active glycoglycerolipid analog till now tested. Four compounds (three butenoates and one 4-methylpentanoate), when tested in the in vivo two-stage carcinogenesis test, exhibited also inhibitory effects on mouse skin tumor promotion.

Cancer preventive agents. Part 1: Chemopreventive potential of cimigenol, cimigenol-3,15-dione, and related compounds

In continuation of our previous report, cimigenol ( 1) and 15 related compounds were screened as potential antitumor promoters by using the in vitro short-term 12- O-tetradecanoylphorbol-13-acetate (TPA)––induced Epstein-Barr virus early antigen (EBV-EA) activation assay. Cimigenol-3,15-dione ( 2) displayed the greatest potency (100% inhibition at 1000 mol ratio/TPA) and consequently was further examined for antitumor-promoting activity in a two-stage carcinogenesis assay of mouse skin tumors (DMBA/TPA). In this assay, compound 2 showed significant activity, reducing the number of papillomas per mouse to 48% of the control group at 20 weeks. In addition, compounds 1 and 2 were examined for antitumor-initiating activity in a two-stage carcinogenesis assay of mouse skin tumors induced by peroxynitrite as an initiator and TPA as a promoter. Results showed that these two triterpenoids were almost equipotent with epigallocatechin gallate (EGCG) and slightly more potent than tocinol (group V), the positive controls. Thus, compounds 1 and 2 exhibited not only strong antitumor-promoting activity but also significant antitumor-initiating effect on mouse skin. These data suggest that both compounds might be valuable chemopreventors.

Potential Anti-Tumor Promoting Activity of Lupane-Type Triterpenoids from the Stem Bark ofGlochidion zeylanicumandPhyllanthus flexuosus

Four known lupane-type triterpenoids, glochidonol (1), glochidiol (2), lup-20(29)-ene-1beta,3beta-diol (3) and glochidone (3) were isolated from the stem bark of Glochidion zeylanicum. Previously, lupeol (5), lup-20(29)-ene-3beta,24-diol (6) and betulin (7) were isolated from the stem bark of Phyllanthus flexuosus. This study reports the assays of these lupane-type triterpenoids: all isolates 1-7 and synthetic analogues, glochidonyl acetate (1a), lup-20(29)-ene-1,3-dione (1b) and lup-20(29)-ene 3beta,24-diacetate (6a) were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). Among them, the effects of compounds 2 (IC50 = 290 mol ratio/32 pmol TPA) and 3 (IC50 = 300) were stronger than the others. In addition, compound 2 exhibited a strong inhibitory effect on mouse skin tumor promotion in an in vivo mouse two-stage carcinogenesis test.

Inhibition of Epstein-Barr virus (EBV) reactivation by short interfering RNAs targeting p38 mitogen-activated protein kinase or c-myc in EBV-positive epithelial cells.

Latent Epstein-Barr virus (EBV) is reactivated by 12-O-tetradecanoylphorbol-13-acetate (TPA) in EBV-infected cells. In this study, we found that TPA up-regulated phosphorylation of p38, a mitogen-activated protein kinase, and activated c-myc mRNA in EBV-positive epithelial GT38 cells. The EBV immediate-early gene BZLF1 mRNA and its product ZEBRA protein were induced following TPA treatment. Protein kinase C inhibitors, 1-(5-isoquinolinesulphonyl)-2, 5-dimethylpiperazine (H7) and staurosporine, inhibited the induction of p38 phosphorylation and the activation of c-Myc by TPA. The p38 inhibitor SB203580 blocked both p38 phosphorylation and ZEBRA expression by TPA. Pretreatment of GT38 cells with the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine inhibited p38 phosphorylation and c-Myc activation by TPA, suggesting that NO may inhibit EBV reactivation via both p38 and c-Myc. By using short interfering RNA (siRNA) targeting either p38 or c-myc, we found that p38 or c-myc siRNA specifically inhibited expression of the respective gene and also suppressed the induction of ZEBRA and EBV early antigen. The interferon (IFN)-responsive gene expression tests ruled out the possibility that the antiviral effect of siRNA is dependent on IFN. Our present study demonstrates for the first time that either p38 or c-myc siRNA can efficiently inhibit TPA-induced EBV reactivation in GT38 cells, indicating that p38- and/or c-myc-associated signaling pathways may play critical roles in the disruption of EBV latency by TPA.

A Newseco-Abietane-Type Diterpene from the Stem Bark ofPicea glehni

A new seco-abietane-type diterpenoid, 13S-hydroxy-9-oxo-9,10-seco-abiet-8(14)-en-18,10alpha-olide (1) along with a known lignan compound, pinoresinol (2) was isolated from the stem bark of Picea glehni (Fr. Schm.) Masters. Spectroscopic methods and chemical conversions were used to establish the structure of 1. In order to assess their cancer chemopreventive potential, the inhibition of Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) was examined for compound 1, its synthetic analogue, 9,10-seco-8S,13S-epoxy-abiet-8(14)-en-18,10alpha-olide (la) and 2. The inhibitory effect of la on EBV-EA induction was strong (0, 20.7, 67.1 and 89.2 % inhibition at 1000, 500,100 and 10 mol ratio/TPA). The IC50 of la was 226 mol ratio/32 pmol/TPA.

Chemical constituents of Glycosmis arborea: three new carbazole alkaloids and their biological activity.

As part of the phytochemical studies of the plant genus Glycosmis, the constituents of the plant Glycosmis arborea were investigated. Three new carbazole alkaloids named glybomines A (1), B (2), and C (3), along with known monomeric alkaloids belonging to the carbazole, quinazoline, furoquinoline, quinolone, and acridone classes, were isolated from stems of the plant collected at Mymensing in Dhaka, Bangladesh. Glybomine A (1) is the first example of a 2,5-oxygenated carbazole alkaloid from natural sources. As a primary screening test for anti-tumor promoters, nine alkaloids isolated from this plant have been tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) induction by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). All alkaloids tested showed inhibitory activity.

Multidrug-resistant cancer cell susceptibility to cytotoxic quassinoids, and cancer chemopreventive effects of quassinoids and canthin alkaloids

Twenty-three quassinoids (1–23), which were isolated previously from Simaroubaceous plants, were evaluated for cytotoxicity against three multidrug-resistant cancer cell lines, KB-VIN, KB-7d, and KB-CPT. Nine compounds (2–7 and 9–11) showed significant cytotoxicity in all three cell lines. Compounds 1, 12–14, 17, and 20 demonstrated significant activity against the KB-7d and KB-CPT cell lines, and compounds 18, 19, and 23 revealed notable activity only against KB-7d cells. Structure–activity relationships were drawn based on these data. In addition, six quassinoid derivatives (24–29) and four canthin alkaloids (30–33), which were isolated from Brucea antidysenterica, were examined for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA) induced Epstein–Barr virus early antigen (EBV-EA) activation as cancer chemopreventive agents. All of these compounds demonstrated significant inhibitory effects against EBV-EA activation.

Cancer chemopreventive activity of 3β-methoxyserrat-14-en-21β-ol and several serratane analogs on two-stage mouse skin carcinogenesis

3β-Methoxyserrat-14-en-21β-ol ( 1) and 3α-methoxyserrat-14-en-21β-ol ( 2) are the most abundant triterpenoids from two Picea plants, Picea jezoensis (Sieb. et Zucc.) Carr. var. jezoensis and P. jezoensis (Sieb. et Zucc.) Carr. hondoensis (Mayr) Rehder, and the total yield of 1 and 2 reach over 1/3 of the chloroform extract of the above two plants. This study deals with the potential of anti-tumor promoting activity of 1 and results of the assay of 22 synthetic serratane-type triterpenoids ( 6)–( 27) derived from 1, 2, 21-episerratenediol ( 3), diepiserratenediol ( 4) and 13α,14α-epoxy-3β-methoxyserratan-21β-ol ( 5) to discuss the structure–activity relationship. As a preliminary evaluation of their potential to inhibit tumor promotion, the inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol-13-acetate (TPA) were used. All compounds except for 12 and 19 showed potent inhibitory effects on EBV-EA induction (100% inhibition at 1000 mol ratio/TPA), their effects being stronger than that of a positive control oleanolic acid. Compounds 1, 13, 14, 18, 20 and 26 were selected to examine the effect on the in vivo two-stage mouse skin carcinogenesis test induced by 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. The most abundant triterpenoid 1 and the synthetic compounds 13 and 14 were found to exhibit the excellent anti-tumor promoting activity in the in vivo carcinogenesis test, and compounds 18, 20 and 26 also showed strong inhibitory effects.

Cancer chemopreventive activity of phenylpropanoids and phytoquinoids from Illicium plants

In our joint project involving search of anti-tumor promoters from natural plant sources, six phenylpropanoids and seven phytoquinoids isolated from three Illicium plants (Illiciaceae) were tested for their inhibitory activities against Epstein–Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol-13-acetate in Raji cells. All tested compounds showed inhibitory activity against the EBV-EA activation even at 1×10 mol ratio, and the inhibitory activity of their compounds was found to be more than that of β-carotene. Two phenylpropanoids having prenyl group, 4-allyl-2-methoxy-6-(3-methyl-2-butenyl)phenol (3) and 4-allyl-2,6-dimethoxy-3-(3-methyl-2-butenyl)phenol (4), showed more potent activities as anti-tumor promoters (IC 50 224 and 217 mol ratio/TPA, respectively). The presence of a prenyl moiety in the phenylpropanoids plays an important role in anti-tumor promoting activity as xanthone, coumarin and flavonoid previously reported. This investigation indicated that prenylated phenylpropanoids might be valuable as potential cancer chemopreventive agents.

Sensitivity and specificity of Epstein-Barr virus IGA titer in the diagnosis of nasopharyngeal carcinoma: a three-year institutional review.

IgA antibody titers to the Epstein-Barr virus (EBV) viral capsid antigen (EBV IgA-VCA) and to the EBV early antigen (EBV IgA-EA) are used to screen for nasopharyngeal carcinoma (NPC). This study evaluates the sensitivity and specificity of EBV IgA-VCA and EBV IgA-EA titers in screening patients for NPC and in those diagnosed with NPC at our institution. The NPC status was determined for all patients who had their EBV IgA-VCA and EBV-IgA EA titers measured over a 3-year period, and the sensitivity and specificity were calculated. Five thousand one hundred ninety-six samples were analyzed. NPC was diagnosed in 215 patients. The sensitivity and specificity of a raised EBV IgA-VCA titer (> or =1:5) for diagnosing NPC were 89% and 80%, respectively, with a raised EbV IgA-EA titer (> or =1:5) having a sensitivity and specificity of 63% and 97%, respectively. Although the EBV IgA-VCA titer is sensitive for the diagnosis of NPC, it should not be used as the sole means of screening for NPC in a population in which NPC is endemic.