Jau-Ling Huang

Evaluation of protective efficacy and immune mechanisms of using a non-structural protein NS1 in DNA vaccine against dengue 2 virus in mice.

To evaluate the potential of DNA vaccine against dengue (DEN) infection, we characterize the protective efficacy and immune responses of mice intramuscularly injected with plasmid encoding DEN-2 non-structural protein 1 (NS1). Intravenously challenged by lethal DEN-2, mice vaccinated with NS1-DNA exhibited a delay onset of paralysis, a marked decrease of morbidity, and a significant enhancement of survival. In addition to a moderate increase of NS1-specific antibody titer from immunized mice measured by ELISA, a strong priming effect on anti-NS1 response was also noticed in plasmid NS1-vaccinated mice by radioimmunoprecipitation (RIP) or immunoblot analysis. Interestingly, newborn mice from NS1-DNA-immunized dam showed stronger resistance to viral challenge, as compared to those from vector DNA or PBS-immunized dams, indicating the protective role of NS1-specific antibody. In contrast to humoral immune response, DNA immunization can elicit strong cellular immune responses, including NS1-specific T cell proliferation and cytolytic activity. The NS1-DNA-induced protection can be further augmented by co-injection of plasmid encoding interleukin 12 (IL-12), suggesting an effector role of Th1 immunity against DEN infection. In summary, our results suggest the potential of NS1-DNA vaccine against DEN infection, and indicate both NS1-specific humoral and cellular immune responses contribute to the protection.

Arecoline;a major alkaloid of areca nut;inhibits p53;represses DNA repair;and triggers DNA damage response in human epithelial cells.

The International Agency for Research on Cancer declared that areca nut was carcinogenic to human. Areca nut is the main component of betel quid (BQ), which is commonly consumed in Asia. Epidemiological studies have shown that BQ chewing is a predominant risk factor for oral and pharyngeal cancers. It has been known that areca nut is genotoxic to human epithelial cells. However, the molecular and cellular mechanisms underlying areca nut-associated genotoxicity are not fully understood. Here we showed that arecoline, a major alkaloid of areca nut, might contribute to oral carcinogenesis through inhibiting p53 and DNA repair. We found, on the biological aspect, that arecoline could induce gamma-H2AX phosphorylation, a sensitive DNA damage marker, in KB, HEp-2, and 293 cells, suggesting that DNA damages were elicited by arecoline. This phenomenon was supported by the observations of arecoline-induced hyperphosphorylation of ATM, Nbs1, Chk1/2, p53, and Cdc25C, as well as G2/M cell cycle arrest, indicating that a cellular DNA damage response was activated. To explore the possible mechanism accounting for arecoline-elicited DNA damages, we found that arecoline could inhibit p53 by its expression and transactivation function. As a result, the expression of p53-regulated p21(WAF1) and the p53-activated DNA repair were repressed by arecoline. Finally, we showed that p53 mRNA transcripts were frequently down-regulated in BQ-associated oral cancer, suggesting that arecoline-mediated p53 inhibition might play a role in BQ-associated tumorigenesis.

Identification of B-Cell Epitope of Dengue Virus Type 1 and Its Application in Diagnosis of Patients

ABSTRACT Using a serotype-specific monoclonal antibody (MAb) of dengue virus type 1 (DEN-1), 15F3-1, we identified the B-cell epitope of DEN-1 from a random peptide library displayed on phage. Fourteen immunopositive phage clones that bound specifically to MAb 15F3-1 were selected. These phage-borne peptides had a consensus motif of HxYaWb (a = S/T, b = K/H/R) that mimicked the sequence HKYSWK, which corresponded to amino acid residues 111 to 116 of the nonstructural protein 1 (NS1) of DEN-1. Among the four synthetic peptides corresponding to amino acid residues 110 to 117 of the NS1 of DEN-1, -2, -3, and -4, only one peptide, EHKYSWKS (P14M) of DEN-1, was found to bind to 15F3-1 specifically. Furthermore, P14M was shown to inhibit the binding of phage particles to 15F3-1 in a competitive inhibition assay. Histidine111 (His111) was crucial to the binding of P14M to 15F3-1, since its binding activity dramatically reduced when it changed to leucine111 (Leu111). This epitope-based peptide demonstrated its clinical diagnostic potential when it reacted with a high degree of specificity with serum samples obtained from both DEN-1-infected rabbits and patients. Based on these observations, our DEN-1 epitope-based serologic test could be useful in laboratory viral diagnosis and in understanding the pathogenesis of DEN-1.

Sensitive and Specific Detection of Strains of Japanese Encephalitis Virus Using a One-Step TaqMan RT-PCR Technique

A rapid, sensitive, and accurate laboratory diagnostic test is needed for distinguishing Japanese encephalitis virus (JEV) from other diseases featuring similar clinical symptoms and also for preventing potential outbreaks. In this study, a TaqMan reverse transcription (RT)‐polymerase chain reaction (PCR) assay was developed for rapid detection and quantification of the viral RNA of various JEV strains. A consensus JEV NS3 region was chosen to design the primers and the TaqMan probe. The JEV TaqMan assay used the EZ‐rTtH RT‐PCR system featuring advantages such as a one‐step, high‐temperature RT reaction modality and preventing carry‐over contamination. The sensitivity of the JEV TaqMan assay for detecting in vitro‐transcribed JEV NS3 RNA was estimated to be one to five copies of RNA per reaction. For cultured JE virions, less than 40 plaque forming unit (PFU)/ml of virus load (corresponding to 0.07 PFU/test) could be detected. In addition, the JEV TaqMan assay could detect all seven strains of JEV tested, but provided negative results for nine other flaviviruses and encephalitis viruses tested. The JEV TaqMan assay demonstrated greater sensitivity and specificity than traditional RT‐PCR methods as has been previously reported. The application of the JEV TaqMan assay herein has been shown to the sensitive detection of the JEV from both mosquito pools and also JEV‐spiking human blood. The assay should be of use in diagnostic laboratory conduct and could be used to replace or complement time‐consuming viral‐culture methods, thus achieving more rapid, sensitive, and highly specific identification of JEV infection. J. Med. Virol. 74:589–596, 2004.

Arecoline arrests cells at prometaphase by deregulating mitotic spindle assembly and spindle assembly checkpoint: Implication for carcinogenesis

One apparent feature of cancerous cells is genomic instability, which may include various types of chromosomal aberrations, such as translocation, aneuploidy, and the presence of micronuclei inside the cells. Mutagenic factors that promote the emergence of genomic instability are recognized as risk factors for the development of human malignancies. In Asia, betel quid (BQ) chewing is one of such risk factors for oral cancer. Areca nut is an essential constitute of BQ and is declared as a group I carcinogen by the International Agency for Research on Cancer. However, the molecular and cellular mechanisms regarding the carcinogenicity of areca nut are not fully explored. Here we reported that arecoline, a major alkaloid of areca nut, could arrest cells at prometaphase with large amounts of misaligned chromosomes. This prometaphase arrest was evidenced by condensed chromosome pattern, increased histone H3 phosphorylation, and accumulation of mitotic proteins, including aurora A and cyclin B(1). To investigate the molecular mechanisms accounting for arecoline-induced prometaphase arrest, we found that arecoline could stabilize mitotic spindle assembly, which led to distorted organization of mitotic spindles, misalignment of chromosomes, and up-regulation of spindle assembly checkpoint (SAC) genes. The SAC proteins BubR1 and Mps1 were differentially modified between the cells treated with arecoline and nocodazole. This together with aurora A overexpression suggested that SAC might be partly suppressed by arecoline. As a result, the arecoline-exposed cells might produce progeny that contained various chromosomal aberrations and exhibited genomic instability.

Elevated mRNA transcripts of non-homologous end-joining genes in pediatric acute lymphoblastic leukemia

Elevated mRNA transcripts of non-homologous end-joining genes in pediatric acute lymphoblastic leukemia

Lower ataxia telangiectasia mutated (ATM) mRNA expression is correlated with poor outcome of laryngeal and pharyngeal cancer patients

BACKGROUND Ataxia telangiectasia mutated (ATM) kinase is a critical regulator in initiating DNA damage response and activating DNA repair. However, the correlation between ATM expression and the outcome of laryngopharyngeal cancer patients is unknown. We hypothesize that ATM expression is correlated with a worse outcome in laryngopharyngeal cancer patients. PATIENTS AND METHODS The ATM messenger RNA (mRNA) expression of 80 tumors of laryngeal and pharyngeal cancer was examined by real-time quantitative RT-PCR. Overall survival rates were measured using Kaplan-Meier estimates and the log-rank tests. The adjusted hazard rate ratios (HRRs) were computed by multivariate Cox regressions. RESULTS Reduced ATM mRNA was found in 65 of 80 studied cases. Lower ATM expression [tumor/normal <0.3, HRR = 2.49; 95% confidence interval (CI) 1.27-4.88], younger age (<55 years, HRR = 2.71; 95% CI 1.16-6.32), and larger tumor (T(3)/T(4), HRR = 2.21; 95% CI 1.10-4.44) were independent risk factors for survival. Patients with lower ATM and younger age (HRR = 6.51; 95% CI 2.05-20.66) or with lower ATM and T(3)/T(4) tumor (HRR = 5.23; 95% CI 2.04-13.40) exhibited the poorest outcome. CONCLUSION The expression of ATM mRNA, which is frequently downregulated in laryngeal and pharyngeal cancers, could be a valuable prognostic marker.

Autophagy and reactive oxygen species modulate cytotoxicity induced by suppression of ATM kinase activity in head and neck cancer cells.

OBJECTIVES Because Ataxia Telangiectasia Mutated (ATM)-deficient cells are hypersensitive to ionizing irradiation and DNA-damaging agents, ATM kinase inhibition is thought to enhance radiochemotherapy efficacy. In this study, we investigated the roles of autophagy and reactive oxygen species (ROS) in modulating cytotoxicity induced by suppression of ATM kinase in head and neck cancer cells. MATERIALS AND METHODS We use KU55933 to inhibit ATM kinase activity. The cell viability was determined by MTT assays. Autophagy was examined by Western blot for LC3-II and microscopy for acidic vesicles and EGFP-LC3 punctate formation. DCF-DA staining and flow cytometry were used for analyzing ROS generation. RESULTS we found that KU55933 reduced cell viability in several head and neck cancer cell lines. KU55933-treated cells showed increased cytoplasmic vesicles, LC3-II accumulation, and EGFP-LC3 punctate formation, indicating that autophagy was induced. KU55933 also increased ROS generation, which was required for autophagy induction because the ROS scavenger N-acetyl-L-cysteine could reduce LC3-II accumulation. KU55933-induced autophagy played a cytoprotective role against ROS-mediated cytotoxicity because autophagy inhibition by chloroquine augmented KU55933s cytotoxicity. In addition, KU55933 reduced cisplatin-resistant head and neck cancer cell viabilities, and induced LC3-II accumulation in these cells. CONCLUSION Together, these results shed light on KU55933s therapeutic values as well as autophagy inhibitors in treating primary and cisplatin-resistant head and neck cancers.

Rapid and sensitive detection of multiple genes from the SARS-Coronavirus using quantitative RT-PCR with dual systems

The outbreak of severe acute respiratory syndrome (SARS) was caused by a newly identified coronavirus (SARS‐CoV) in 2003. To detect early SARS‐CoV infection, a one‐step, real‐time quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) assay was developed that could simultaneously detect nucleocapsid (N), membrane (M), and spike (S) genes of SARS‐CoV with the same PCR condition using either Applied Biosystems (ABI) Prism 7700 Sequence Detection System or Roche LightCycler. The sensitivity of this assay was evaluated using cell culture‐derived viruses, in vitro transcribed viral RNA, and clinical specimens. The SARS‐S, ‐M, and ‐N primer/probe sets described in this paper could detect one to ten copies of in vitro transcribed S, M, and N RNA per test using both the ABI and Roche assay systems. The relative sensitivities for detecting cell culture‐derived SARS‐CoV were 0.01, 0.01, and 0.001 PFU/test, respectively. It showed that SARS‐N has comparable detection efficiencies to SARS2 and SARS3 which are primers sets designed by Centers for Disease Control and Prevention. In addition, SARS‐S and SARS‐M also demonstrated equivalent sensitivity to the commercially available RealArt HPA‐Coronavirus reagents (Artus). The relative sensitivity of these primer/probe sets was also examined using human sera spiked viruses and clinical specimens from four confirmed SARS patients. Similar results as above were obtained. Specificity tests and sequence alignment showed that these primer/probe sets annealed perfectly to 31 isolates of SARS‐CoV; and there was no cross detection with other coronaviruses and human respiratory tract‐associated viruses. Therefore, not only is it compatible with the ABI and Roche systems, this multiple‐gene detection assay also has the merit of being a rapid, safe, sensitive, and specific tool for accurate diagnosis of SARS‐CoV infection. J. Med. Virol. 77:151–158, 2005.

Enhancement of the genotoxicity of benzo[a]pyrene by arecoline through suppression of DNA repair in HEp-2 cells.

The International Agency for Research on Cancer lists the principal component of betel quid (BQ), the areca nut, and that of cigarette smoke, benzo[a]pyrene (BaP), as Group 1 carcinogens. Epidemiological studies have shown that coexposure of BQ and cigarette smoke markedly increases the risk of cancer. We previously demonstrated that arecoline, the most abundant alkaloid in the areca nut, inhibits nucleotide excision repair through the repression of p53 activity. To investigate the combined potency of arecoline and BaP in carcinogenesis, we treated human epithelial HEp-2 cells with subcytotoxic doses of arecoline and BaP, alone or in combination, and examined the effects on DNA damage and repair. When exposed for 24h, BaP enhanced DNA repair and p53 transactivation activity. However, these enhancements were suppressed through concurrent treatment of the cells with arecoline. Using a Comet assay, we found that extended exposure to arecoline and BaP caused moderate-to-severe DNA damage in 60% of the cells. Expression of the XPD helicase was transcriptionally suppressed by 1 week of treatment with BaP. Our studies have revealed potential targets in the DNA repair pathway that are affected by BQ and tobacco components, as well as the effect of these components on carcinogenesis.