Reactivation of Epstein-Barr virus by a dual-responsive fluorescent EBNA1-targeting agent with Zn2+-chelating function.

Epstein-Barr nuclear antigen 1 (EBNA1) plays a vital role in the maintenance of the viral genome and is the only viral protein expressed in nearly all forms of Epstein-Barr virus (EBV) latency and EBV-associated diseases, including numerous cancer types. To our knowledge, no specific agent against EBV genes or proteins has been established to target EBV lytic reactivation. Here we report an EBNA1- and Zn2+-responsive probe (ZRL5P4) which alone could reactivate the EBV lytic cycle through specific disruption of EBNA1. We have utilized the Zn2+ chelator to further interfere with the higher order of EBNA1 self-association. The bioprobe ZRL5P4 can respond independently to its interactions with Zn2+ and EBNA1 with different fluorescence changes. It can selectively enter the nuclei of EBV-positive cells and disrupt the oligomerization and oriP-enhanced transactivation of EBNA1. ZRL5P4 can also specifically enhance Dicer1 and PML expression, molecular events which had been reported to occur after the depletion of EBNA1 expression. Importantly, we found that treatment with ZRL5P4 alone could reactivate EBV lytic induction by expressing the early and late EBV lytic genes/proteins. Lytic induction is likely mediated by disruption of EBNA1 oligomerization and the subsequent change of Dicer1 expression. Our probe ZRL5P4 is an EBV protein-specific agent that potently reactivates EBV from latency, leading to the shrinkage of EBV-positive tumors, and our study also suggests the association of EBNA1 oligomerization with the maintenance of EBV latency.

Role of miR-96/EVI1/miR-449a Axis in the Nasopharyngeal Carcinoma Cell Migration and Tumor Sphere Formation.

The Wnt signaling pathway is one of the major signaling pathways used by cancer stem cells (CSC). Ecotropic Viral Integration Site 1 (EVI1) has recently been shown to regulate oncogenic development of tumor cells by interacting with multiple signaling pathways, including the Wnt signaling. In the present study, we found that the Wnt modulator ICG-001 could inhibit the expression of EVI1 in nasopharyngeal carcinoma (NPC) cells. Results from loss-of-function and gain-of-function studies revealed that EVI1 expression positively regulated both NPC cell migration and growth of CSC-enriched tumor spheres. Subsequent studies indicated ICG-001 inhibited EVI1 expression via upregulated expression of miR-96. Results from EVI1 3'UTR luciferase reporter assay confirmed that EVI1 is a direct target of miR-96. Further mechanistic studies revealed that ICG-001, overexpression of miR-96, or knockdown of EVI1 expression could restore the expression of miR-449a. The suppressive effect of miR-449a on the cell migration and tumor sphere formation was confirmed in NPC cells. Taken together, the miR-96/EVI1/miR-449a axis is a novel pathway involved in ICG-001-mediated inhibition of NPC cell migration and growth of the tumor spheres.

Role of G3BP1 in glucocorticoid receptor-mediated microRNA-15b and microRNA-23a biogenesis in endothelial cells.

MicroRNAs (miRNAs) are a family of non-coding RNAs that play crucial roles in regulating various normal cellular responses. Recent studies revealed that the canonical miRNA biogenesis pathway is subject to sophisticated regulation. Hormonal control of miRNA biogenesis by androgen and estrogen has been demonstrated, but the direct effects of the glucocorticoid receptor (GR) on miRNA biogenesis are unknown. This study revealed the role of GR in miRNA maturation. We showed that two GR agonists, dexamethasone and ginsenoside-Rg1 rapidly suppressed the expression of mature miR-15b, miR-23a, and miR-214 in human endothelial cells. RNA pulldown coupled with proteomic analysis identified GTPase-activating protein (SH3 domain) binding protein 1 (G3BP1) as one of the RNA-binding proteins mediating GR-regulated miRNA maturation. Activated GR induced phosphorylation of v-AKT Murine Thymoma Viral Oncogene Homologue (AKT) kinase, which in turn phosphorylated and promoted nuclear translocation of G3BP1. The nuclear G3BP1 bound to the G3BP1 consensus sequence located on primary miR-15b~16-2 and miR-23a~27a~24-2 to inhibit their maturation. The findings from this study have advanced our understanding of the non-genomic effects of GR in the vascular system.

Proteomic analysis of exosomes from nasopharyngeal carcinoma cell identifies intercellular transfer of angiogenic proteins.

Exosomes, a group of secreted extracellular nanovesicles containing genetic materials and signaling molecules, play a critical role in intercellular communication. During tumorigenesis, exosomes have been demonstrated to promote tumor angiogenesis and metastasis while their biological functions in nasopharyngeal carcinoma (NPC) are poorly understood. In this study, we focused on the role of NPC-derived exosomes on angiogenesis. Exosomes derived from the NPC C666-1 cells and immortalized nasopharyngeal epithelial cells (NP69 and NP460) were isolated using ultracentrifugation. The molecular profile and biophysical characteristics of exosomes were verified by Western blotting, sucrose density gradient and electron microscopy. We showed that the C666-1 exosomes (10 and 20 µg/ml) could significantly increase the tubulogenesis, migration and invasion of human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner. Subsequently, an iTRAQ-based quantitative proteomics was used to identify the differentially expressed proteins in C666-1 exosomes. Among the 640 identified proteins, 51 and 89 proteins were considered as up- and down-regulated (≥ 1.5-fold variations) in C666-1 exosomes compared to the normal counterparts, respectively. As expected, pro-angiogenic proteins including intercellular adhesion molecule-1 (ICAM-1) and CD44 variant isoform 5 (CD44v5) are among the up-regulated proteins, whereas angio-suppressive protein, thrombospondin-1 (TSP-1) was down-regulated in C666-1 exosomes. Further confocal microscopic study and Western blotting clearly demonstrated that the alteration of ICAM-1 and TSP-1 expressions in recipient HUVECs are due to internalization of exosomes. Taken together, these data strongly indicated the critical roles of identified angiogenic proteins in the involvement of exosomes-induced angiogenesis, which could potentially be developed as therapeutic targets in future.

Monitoring and inhibition of Plk1: amphiphilic porphyrin conjugated Plk1 specific peptides for its imaging and anti-tumor function.

Polo-like kinase 1 (Plk1) is well-known for taking part in cell cycle progression and regulation. Using small molecules for Plk inhibition has been well documented in the literature. However, there are several intrinsic and intractable problems associated with this approach. For example monitoring small molecule Plk inhibitors as anti-tumor agents in vitro/in vivo is often ineffective, they can have poor cell internalization and be susceptible to enzymatic degradation. Herein, we report the synthesis of cell-permeable, water-soluble amphiphilic porphyrin ­ Plk1 specific peptide bioconjugates, Por-P1 and Por-P2. In addition to resolving the aforementioned problems of the small molecule inhibitors Por-P2 manifests responsive emission enhancement upon binding with Plk1 in aqueous medium and in vitro, while potently triggering G2-M phase arrest and then apoptosis selectively in the cancer cells tested. In combination our findings make Por-P2 a promising candidate for the preparation of a new generation of smart chemotherapeutic targeting agents (imaging and inhibition) for Plk1 in particular cancer cell lines.

A novel Hsp90 inhibitor AT13387 induces senescence in EBV-positive nasopharyngeal carcinoma cells and suppresses tumor formation.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is an epithelial malignancy strongly associated with Epstein-Barr virus (EBV). AT13387 is a novel heat shock protein 90 (Hsp90) inhibitor, which inhibits the chaperone function of Hsp90 and reduces expression of Hsp90-dependent client oncoproteins. This study aimed to evaluate both the in vitro and in vivo antitumor effects of AT13387 in the EBV-positive NPC cell line C666-1. RESULTS: Our results showed that AT13387 inhibited C666-1 cell growth and induced cellular senescence with the downregulation of multiple Hsp90 client oncoproteins EGFR, AKT, CDK4, and restored the protein expression of negative cell cycle regulator p27. We also studied the ability of AT13387 to restore p27 expression by downregulation of AKT and the p27 ubiquitin mediator, Skp2, using AKT inhibitor and Skp2 siRNA. In the functional study, AT13387 inhibited cell migration with downregulation of a cell migration regulator, HDAC6, and increased the acetylation and stabilization of α-tubulin. We also examined the effect of AT13387 on putative cancer stem cells (CSC) by 3-D tumor sphere formation assay. AT13387 effectively reduced both the number and size of C666-1 tumor spheres with decreased expression of NPC CSC-like markers CD44 and SOX2. In the in vivo study, AT13387 significantly suppressed tumor formation in C666-1 NPC xenografts. CONCLUSION: AT13387 suppressed cell growth, cell migration, tumor sphere formation and induced cellular senescence on EBV-positive NPC cell line C666-1. Also, the antitumor effect of AT13387 was demonstrated in an in vivo model. This study provided experimental evidence for the preclinical value of using AT13387 as an effective antitumor agent in treatment of NPC.

EBV latent membrane protein 1 augments γδ T cell cytotoxicity against nasopharyngeal carcinoma by induction of butyrophilin molecules.

Nasopharyngeal carcinoma (NPC) is a diverse cancer with no well-defined tumor antigen, associated with oncogenic Epstein-Barr Virus (EBV), and with usually late-stage diagnosis and survival <40%. Current radiotherapy and chemotherapy have low effectiveness and cause adverse effects, which calls for the need of new therapy. In this regard, adoptive immunotherapy using γδ T cells has potential, but needs to be coupled with butyrophilin 2A1 and 3A1 protein expression to achieve tumoricidal effect. Methods: Human γδ T cells were expanded (with Zol or PTA) and used for cytotoxicity assay against NPC cells, which were treated with the EBV EBNA1-targeting peptide (L2)P4. Effect of (L2)P4 on BTN2A1/BTN3A1 expression in NPC cells was examined by flow cytometry and Western blot. An NPC-bearing NSG mice model was established to test the effectiveness of P4 and adoptive γδ T cells. Immunofluorescence was performed on NPC tissue sections to examine the presence of γδ T cells and expression of BTN2A1 and BTN3A1. EBV gene expression post-(L2)P4 treatment was assessed by qRT-PCR, and the relationship of LMP1, NLRC5 and BTN2A1/BTN3A1 was examined by transfection, reporter assay, Western blot, and inhibition experiments. Results: Zol- or PTA-expanded the Vδ2 subset of γδ T cells that exerted killing against certain NPC cells. (L2)P4 reactivates latent EBV, which increased BTN2A1 and BTN3A1 expression and conferred higher susceptibility towards Vδ2 T cells cytotoxicity in vitro, as well as enhanced tumor regression in vivo by adoptive transfer of Vδ2 T cells. Mechanistically, (L2)P4 induced EBV LMP1, leading to IFN-γ/p-JNK and NLRC5 activation, and subsequently stimulated the expression of BTN2A1 and BTN3A1. Conclusions: This study demonstrated the effectiveness of using the EBV-targeting probe (L2)P4 and adoptive γδ T cells as a promising combinatorial immunotherapy against NPC. The identification of the LMP1-IFN-γ/p-JNK-NLRC5-BTN2A1/BTN3A1 axis may lead to new insight and therapeutic targets against NPC and other EBV+ tumors.

CDK5RAP2 is a Wnt target gene and promotes stemness and progression of oral squamous cell carcinoma.

In oral squamous cell carcinoma (OSCC), a highly aggressive and frequently lethal malignancy, the role and action mechanism of the microtubule regulatory protein CDK5RAP2 have not been fully understood. Here, we show that CDK5RAP2 is highly expressed in OSCC and its expression correlates with clinical stage and lymph node metastasis of the disease. The expression of CDK5RAP2 is regulated by the Wnt signaling pathway. Depletion of CDK5RAP2 inhibits the tumorigenesis and migration of OSCC cells and alters the OSCC cancer stem (-like) cell (CSC) signature. Notably, suppression of CDK5RAP2 expression disrupts spindle orientation during mitosis. Collectively, these results identify CDK5RAP2 as a potential CSC marker and reveal a mechanism that controls the CSC population in OSCC.

Comparative studies of the cellular uptake, subcellular localization, and cytotoxic and phototoxic antitumor properties of ruthenium(II)-porphyrin conjugates with different linkers.

Six water-soluble free-base porphyrin-Ru(II) conjugates, 1-3, and Zn(II) porphyrin-Ru(II) conjugates, 4-6, with different linkers between the hydrophobic porphyrin moiety and the hydrophilic Ru(II)-polypyridyl complex, have been synthesized. The linear and two-photon-induced photophysical properties of these conjugates were measured and evaluated for their potential application as dual in vitro imaging and photodynamic therapeutic (PDT) agents. Conjugates 1-3, with their high luminescence and singlet oxygen quantum yields, were selected for further study of their cellular uptake, subcellular localization, and cytotoxic and photocytotoxic (under linear and two-photon excitation) properties using HeLa cells. Conjugate 2, with its hydrophobic phenylethynyl linker, was shown to be highly promising for further development as a bifunctional probe for two-photon (NIR) induced PDT and in vitro imaging. Cellular uptake and subcellular localization properties were shown to be crucial to its PDT efficacy.

Cytoprotective effect of 20S-Rg3 on benzo[a]pyrene-induced DNA damage.

Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon ubiquitously existing in the environment. Its metabolites have been shown to cause DNA damage and cellular dysfunction in humans. Panax ginseng C.A. Meyer is a Chinese medicinal herb, and ginsenosides are the main active constituent of ginseng. Accumulating evidence had indicated that ginseng extract and ginsenosides possess cytoprotective effects. In this study, the protective effect of ginsenosides on BaP-induced DNA damage in human dermal fibroblasts (HDFs) and HepG2 cells was investigated. The genotoxic effect of BaP was measured by the comet assay. Results showed that tail moment was increased in BaP-treated cells, but cotreatment of ginsenoside 20(S)-Rg3 can significantly decrease BaP-induced DNA damage. A downstream mechanistic study revealed that 20(S)-Rg3 increased the gene expression of an important phase II detoxifying enzyme NAD(P)H:quinine oxidoreductase 1. The effect was also associated with the activation of protein kinase B (Akt) and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). These results indicated that 20(S)-Rg3 might protect HDFs from BaP-induced DNA damage through the activation of the phosphatidylinositol 3-kinase/Akt/Nrf2 pathway. Our results also demonstrated that 20(S)-Rg3 is a functional ligand of pregnane X receptor (PXR), a nuclear receptor that mediates the induction of drug clearance pathways. Subsequent knockdown of PXR expression by small interfering RNA confirmed the involvement of PXR on the protective effects of 20(S)-Rg3 against BaP-induced DNA damage. In summary, ginsenoside 20(S)-Rg3 can protect against BaP-induced genotoxicity in human cells, suggesting that ginseng may serve as a natural cytoprotective agent against environmental carcinogens.

Highly selective mitochondria-targeting amphiphilic silicon(IV) phthalocyanines with axially ligated rhodamine B for photodynamic therapy.

Two axially ligated rhodamine-Si(IV)-phthalocyanine (Rh-SiPc) conjugates, bearing one and two rhodamine B, were synthesized and their linear and two-photon photophysical, subcellular localization and photocytotoxic properties were studied. These Rh-SiPc conjugates exhibited an almost exclusive mitochondrial localizing property in human nasopharyngeal carcinoma (HK-1) cells and human cervical carcinoma (HeLa) cells. Strong photocytotoxic but low dark cytotoxic properties were also observed for the two Rh-SiPc conjugates toward the HK-1 cells. Using nuclei staining method and flow cytometric DNA content analysis, apoptotic cell death was induced by these conjugates upon photoactivation. This observation is consistent with their mitochondrial localization property. The observed properties of these conjugates qualify them as promising PDT agents.

The CBP/ß-Catenin Antagonist, ICG-001, Inhibits Tumor Metastasis via Blocking of the miR-134/ITGB1 Axis-Mediated Cell Adhesion in Nasopharyngeal Carcinoma.

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV)-associated malignancy ranking as the 23rd most common cancer globally, while its incidence rate ranked the 9th in southeast Asia. Tumor metastasis is the dominant cause for treatment failure in NPC and metastatic NPC is yet incurable. The Wnt/ß-catenin signaling pathway plays an important role in many processes such as cell proliferation, differentiation, epithelial-mesenchymal transition (EMT), and self-renewal of stem cells and cancer stem cells (CSCs). Both the EMT process and CSCs are believed to play a critical role in cancer metastasis. We here investigated whether the specific CBP/ß-catenin Wnt antagonist, IGC-001, affects the metastasis of NPC cells. We found that ICG-001 treatment could reduce the adhesion capability of NPC cells to extracellular matrix and to capillary endothelial cells and reduce the tumor cell migration and invasion, events which are closely associated with distant metastasis. Through a screening of EMT and CSC-related microRNAs, it was found that miR-134 was consistently upregulated by ICG-001 treatment in NPC cells. Very few reports have mentioned the functional role of miR-134 in NPC, except that the expression was found to be downregulated in NPC. Transient transfection of miR-134 into NPC cells reduced their cell adhesion, migration, and invasion capability, but did not affect the growth of CSC-enriched tumor spheres. Subsequently, we found that the ICG-001-induced miR-134 expression resulting in downregulation of integrin ß1 (ITGB1). Such downregulation reduced cell adhesion and migration capability, as demonstrated by siRNA-mediated knockdown of ITGB1. Direct targeting of ITGB1 by miR-134 was confirmed by the 3'-UTR luciferase assay. Lastly, using an in vivo lung metastasis assay, we showed that ICG-001 transient overexpression of miR-134 or stable overexpression of miR-134 could significantly reduce the lung metastasis of NPC cells. Taken together, we present here evidence that modulation of Wnt/ß-catenin signaling pathway could inhibit the metastasis of NPC through the miR-134/ITGB1 axis.

Two-photon induced luminescence, singlet oxygen generation, cellular uptake and photocytotoxic properties of amphiphilic Ru(II) polypyridyl-porphyrin conjugates as potential bifunctional photodynamic therapeutic agents.

Two Ru(II) polypyridyl-porphyrin and Zn(II) porphyrin conjugates (Ru-L and Ru-Zn-L) have been synthesized and their photophysical properties studied. The two conjugates, which contained a hydrophobic tetraphenylporphyrin L conjugated via an acetylide linker at its ß-position with a hydrophilic Ru(II) polypyridyl complex, showed high singlet oxygen quantum yields (>70%) and substantial two-photon absorption cross-sections (~500 GM). Ru-L gave strong emissions at ~660 and ~733 nm through linear or two-photon excitation. Solvatochromism was observed in the fluorescence spectra of Ru-L and Ru-Zn-L, where in less polar solvents (i.e., toluene and dichloromethane) their fluorescence emissions became slightly blue-shifted with a 3-fold reduction in intensity relative to those observed in polar solvents (i.e., acetonitrile and methanol). Cell-based studies of these complex conjugates were conducted using human nasopharyngeal carcinoma HK-1 and cervical carcinoma HeLa cells on which Ru-L showed rapid cellular uptake, low dark-cytotoxicity, and high photo-cytotoxicity. Furthermore, Ru-L can be excited and emits in the "biological window"in vitro, making it a potential potent new generation photodynamic therapeutic agent capable of singlet oxygen generation and in vitro near-infrared emission.

Triphenyltin induced growth inhibition and antioxidative responses in the green microalga Scenedesmus quadricauda.

The toxicity of organotin compounds in the environment is closely related to their uptake by microorganisms and delivery through the food chain. The population at low trophic levels like microalgae plays an important role in this aspect. In this study, the toxic effects of triphenyltin (TPT) on Scenedesmus quadricauda were assessed at the population, cellular and subcellular levels. The alga was exposed to TPT of up to 64 µg l(-1) (nearly lethal concentration), but the algal growth was inhibited significantly when TPT was elevated to 8 µg l(-1). This growth inhibition was correlated to the presence of oxidative stress as evidenced by the accumulation of malondialdehyde (MDA) and confirmed by fluorescent probing of the intracellular reactive oxygen species (ROS) levels. The imbalanced activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) may lead to an accumulation of intracellular H(2)O(2), which can initiate an oxidative damage to cell components and cause growth inhibition and finally cell death. The detachment of plasma membrane from cell wall, the structural change of chloroplasts as well as the increased number and size of starch granules together with electron-dense deposits in chloroplasts were noticed through electron microscopic examination. It was suggested that mitochondria, chloroplasts and protoplasm might be the direct targets of TPT toxicity. This study confirmed that TPT poisoning on phytoplankton can happen at very low concentrations. There existed different defense mechanisms e.g., antioxidant enzyme activation, starch accumulation and possibly metal sequestration in algal species as the means to resist TPT toxicity.

A red-light-activated sulfonamide porphycene for highly efficient photodynamic therapy against hypoxic tumor.

Photodynamic therapy (PDT) is an emerging alternative cancer treatment modality that utilizes photo-sensitivity to cause cell death upon photo-irradiation. However, PDT efficiency has been hampered by tumor hypoxia, blue-shifted excitation wavelengths, and the high dark toxicity of photo-sensitizers. We designed and synthesized two novel porphycene-based photosensitizers (TBPoS-OH and TBPoS-2OH) with potent photo-cytotoxicity and a LD50 in the nM range under both normoxic and hypoxic conditions in a variety of cell types after photo-irradiation (λ = 640 ± 15 nm). Further studies showed fast-cellular uptake for TBPoS-OH that localized lysosomes and subsequently induced cell apoptosis via the lysosomal-mitochondrial pathway. Moreover, TBPoS-OH significantly reduced tumor growth in two xenografted mouse models bearing melanoma A375 and B16 cells. Finally, TBPoS-OH exhibited no obvious immunogenicity and toxicity to blood cells and major organs in mice. These data demonstrated that these two porphycene-based photosensitizers, especially TBPoS-OH, could be developed as a potential PDT modality.

Lanthanide-Based Peptide-Directed Visible/Near-Infrared Imaging and Inhibition of LMP1.

A lanthanide-based peptide-directed bioprobe LnP19 (Ln = Eu or Yb) is designed as an impressive example of a small molecule-based dual-functional probe for the EBV oncoprotein LMP1. The peptide P19 (Pra-KAhx-K-LDLALK-FWLY-K-IVMSDKW-K-RrRK) is designed to selectively bind to LMP1 by mimicking its TM1 region during oligomerization in lipid rafts while signal transduction is significantly suppressed. Immunofluorescence imaging and Western blotting results reveal that P19 can effectively inactivate the oncogenic cellular pathway nuclear factor κB (NF-κB) and contribute to a selective cytotoxic effect on LMP1-positive cells. By conjugation with cyclen-based europium(III) and ytterbium(III) complexes, EuP19 and YbP19 were constructed to offer visible and near-infrared LMP1-targeted imaging and cancer monitoring. In addition to the ability to target and inhibit LMP1 and to selective inhibit LMP1-positive cells, selective growth inhibition toward the LMP1-positive tumor by LnP19 is also demonstrated.

Anti-inflammatory protein of Schistosoma japonicum directs the differentiation of the WEHI-3B JCS cells and mouse bone marrow cells to macrophages.

Sj16 is an anti-inflammatory protein identified from Schistosoma japonicum. Our previous studies showed that recombinant Sj16 (rSj16) could suppress host's inflammatory responses and inhibit macrophage maturation. In the present study, the effects of rSj16 on the differentiation of the murine myeloid leukemia WEHI-3B JCS cell line and on mouse hematopoiesis were investigated. Our data demonstrated that rSj16 expressed and purified from Escherichia coli could suppress the proliferation of the WEHI-3B JCS cells in a time- and concentration-dependent manner, while not affect the viability of the cells. Further studies indicated that rSj16 induced macrophage differentiation of the WEHI-3B JCS cells, and arrested the cell cycle in the G1/G0 and G2/M phases. The macrophage differentiation of the rSj16-treated WEHI-3B JCS cells was confirmed by their expression of macrophage specific antigen F4/80 and phagocytic activity. Furthermore, our results revealed that rSj16 biased the colony formation of mouse bone marrow cells towards macrophage linage.

Ultraviolet-B radiation improves astaxanthin accumulation in green microalga Haematococcus pluvialis.

Ultraviolet-B (UV-B) radiation has significantly negative effect on cell survival rate (P < 0.01) and positive effect on astaxanthin accumulation (P < 0.01) of Haematococcus pluvialis. H. pluvialis accumulated 3.2 mg/g of astaxanthin when being exposed to 5 W/m(2) of UV-B for 60 min prior to 72 h of high light treatment, which was 122% higher than that of the control. This UV-B treatment also significantly stimulated lipid peroxidation and the value of malondialdehyde and glutathione peroxidase activities were 156 and 166% higher than those of control, respectively (P < 0.01).

Targeting Epstein-Barr Virus in Nasopharyngeal Carcinoma.

Nasopharyngeal carcinoma (NPC) is consistently associated with Epstein-Barr virus (EBV) infection in regions in which it is endemic, including Southern China and Southeast Asia. The high mortality rates of NPC patients with advanced and recurrent disease highlight the urgent need for effective treatments. While recent genomic studies have revealed few druggable targets, the unique interaction between the EBV infection and host cells in NPC strongly implies that targeting EBV may be an efficient approach to cure this virus-associated cancer. Key features of EBV-associated NPC are the persistence of an episomal EBV genome and the requirement for multiple viral latent gene products to enable malignant transformation. Many translational studies have been conducted to exploit these unique features to develop pharmaceutical agents and therapeutic strategies that target EBV latent proteins and induce lytic reactivation in NPC. In particular, inhibitors of the EBV latent protein EBNA1 have been intensively explored, because of this protein's essential roles in maintaining EBV latency and viral genome replication in NPC cells. In addition, recent advances in chemical bioengineering are driving the development of therapeutic agents targeting the critical functional regions of EBNA1. Promising therapeutic effects of the resulting EBNA1-specific inhibitors have been shown in EBV-positive NPC tumors. The efficacy of multiple classes of EBV lytic inducers for NPC cytolytic therapy has also been long investigated. However, the lytic-induction efficiency of these compounds varies among different EBV-positive NPC models in a cell-context-dependent manner. In each tumor, NPC cells can evolve and acquire somatic changes to maintain EBV latency during cancer progression. Unfortunately, the poor understanding of the cellular mechanisms regulating EBV latency-to-lytic switching in NPC cells limits the clinical application of EBV cytolytic treatment. In this review, we discuss the potential approaches for improvement of the above-mentioned EBV-targeting strategies.

Targeted inhibition of the EGFR pathways enhances Zn-BC-AM PDT-induced apoptosis in well-differentiated nasopharyngeal carcinoma cells.

Epidermal growth factor receptor (EGFR), a receptor often expressed in nasopharyngeal carcinoma (NPC) cells, is one of the recently identified molecular targets in cancer treatment. In the present study, the effects of combined treatment of Zn-BC-AM PDT with an EGFR inhibitor AG1478 were investigated. Well-differentiated NPC HK-1 cells were subjected to PDT with 1 microM of Zn-BC-AM and were irradiated at a light dose of 1 J/cm(2) in the presence or absence of EGFR inhibitor AG1478. Specific protein kinase inhibitors of downstream EGFR targets were also used in the investigation. EGFR, Akt, and ERK were found constitutively activated in HK-1 cells and the activities could be inhibited by the EGFR inhibitor AG1478. A sub-lethal concentration of AG1478 was found to further enhance the irreversible cell damage induced by Zn-BC-AM PDT in HK-1 cells. Pre-incubation of the cells with specific inhibitors of EGFR (AG1478), PI3k/Akt (LY294002), or MEK/ERK (PD98059) before light irradiation were found to enhance Zn-BC-AM PDT-induced formation of apoptotic cells. The efficacy of Zn-BC-AM PDT can be increased through the inhibition of EGFR/PI3K/Akt and EGFR/MEK/ERK signaling pathways in NPC cells. Combination therapy with Zn-BC-AM PDT and EGFR inhibitors may further be developed for the treatment of advanced NPC.