Hepatitis C virus (HCV) NS5B polymerase is a key target for the development of anti-HCV drugs. Here we report on the identification of novel allosteric inhibitors of HCV NS5B through a combination of structure-based virtual screening and in vitro NS5B inhibition assays. One hundred and sixty thousand compounds from the Otava database were virtually screened against the thiazolone inhibitor binding site on NS5B (thumb pocket-2, TP-2), resulting in a sequential down-sizing of the library by 2.7 orders of magnitude to yield 59 NS5B non-nucleoside inhibitor (NNI) candidates. In vitro evaluation of the NS5B inhibitory activity of the 59 selected compounds resulted in a 14% hit rate, yielding 8 novel structural scaffolds. Of these, compound 1 bearing a 4-hydrazinoquinazoline scaffold was the most active (IC50 = 16.0 µM). The binding site of all 8 NNIs was mapped to TP-2 of NS5B as inferred by a decrease in their inhibition potency against the M423T NS5B mutant, employed as a screen for TP-2 site binders. At 100 µM concentration, none of the eight compounds exhibited any cytotoxicity, and all except compound 8 exhibited between 40–60% inhibition of intracellular NS5B polymerase activity in BHK-NS5B-FRLuc reporter cells. These inhibitor scaffolds will form the basis for future optimization and development of more potent NS5B inhibitors.
Hepatitis C virus; NS5B polymerase; virtual screening; NS5B inhibitors; thumb pocket
Upon screening of plant-derived natural products against hepatitis C virus (HCV) in the replicon system, we demonstrate that lucidone, a phytocompound, isolated from the fruits of Lindera erythrocarpa Makino, significantly suppressed HCV RNA levels with 50% effective concentrations of 15 ± 0.5 μM and 20 ± 1.1 μM in HCV replicon and JFH-1 infectious assays, respectively. There was no significant cytotoxicity observed at high concentrations, with a 50% cytotoxic concentration of 620 ± 5 μM. In addition, lucidone significantly induced heme oxygenase-1 (HO-1) production and led to the increase of its product biliverdin for inducing antiviral interferon response and inhibiting HCV NS3/4A protease activity. Conversely, the anti-HCV activity of lucidone was abrogated by blocking HO-1 activity or silencing gene expression of HO-1 or NF-E2-related factor 2 (Nrf2) in the presence of lucidone, indicating that the anti-HCV action of lucidone was due to the stimulation of Nrf-2-mediated HO-1 expression. Moreover, the combination of lucidone and alpha interferon, the protease inhibitor telaprevir, the NS5A inhibitor BMS-790052, or the NS5B polymerase inhibitor PSI-7977, synergistically suppressed HCV RNA replication. These findings suggest that lucidone could be a potential lead or supplement for the development of new anti-HCV agent in the future.
Long noncoding RNA (lncRNA) function is described in terms of related gene expressions, diseases, and cancers as well as their polymorphisms. Potential modulators of lncRNA function, including clinical drugs, natural products, and derivatives, are discussed, and bioinformatic resources are summarized. The improving knowledge of the lncRNA regulatory network has implications not only in gene expression, diseases, and cancers, but also in the development of lncRNA-based pharmacology.
For their various bioactivities, biomaterials derived from marine algae are important ingredients in many products, such as cosmetics and drugs for treating cancer and other diseases. This mini-review comprehensively compares the bioactivities and biological functions of biomaterials from red, green, brown, and blue-green algae. The anti-oxidative effects and bioactivities of several different crude extracts of algae have been evaluated both in vitro and in vivo. Natural products derived from marine algae protect cells by modulating the effects of oxidative stress. Because oxidative stress plays important roles in inflammatory reactions and in carcinogenesis, marine algal natural products have potential for use in anti-cancer and anti-inflammatory drugs.
Algae; ROS; Antioxidant; Inflammation; Antinociceptive; Anti-cancer
Alternative splicing is a major diversification mechanism in the human transcriptome and proteome. Several diseases, including cancers, have been associated with dysregulation of alternative splicing. Thus, correcting alternative splicing may restore normal cell physiology in patients with these diseases. This paper summarizes several alternative splicing-related diseases, including cancers and their target genes. Since new cancer drugs often target spliceosomes, several clinical drugs and natural products or their synthesized derivatives were analyzed to determine their effects on alternative splicing. Other agents known to have modulating effects on alternative splicing during therapeutic treatment of cancer are also discussed. Several commonly used bioinformatics resources are also summarized.
Structure-based studies led to the identification of a constrained derivative of S-trityl-L-cysteine (STLC) scaffold as a candidate inhibitor of hepatitis C virus (HCV) NS5B polymerase. A panel of STLC derivatives were synthesized and investigated for their activity against HCV NS5B. Three STLC derivatives, 9, F-3070, and F-3065, were identified as modest HCV NS5B inhibitors with IC50 values between 22.3 to 39.7 μM. F-3070 and F-3065 displayed potent inhibition of intracellular NS5B activity in the BHK-NS5B-FRLuc reporter and also inhibited HCV RNA replication in the Huh7/Rep-Feo1b reporter system. Binding mode investigations suggested that the STLC scaffold can be used to develop new NS5B inhibitors by further chemical modification at one of the trityl phenyl group.
antiviral agents; hepatitis C; HCV NS5B polymerase; inhibitors; STLC derivatives
Background and Objectives. Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by loss of motor neurons in the brainstem, motor cortex, and spinal cord. Oxidative stress and neuroinflammation have been implicated in the pathophysiology of ALS. Members of the family of damage-associated molecular patterns, including reactive oxygen species, high-mobility group box 1, and eosinophil-derived neurotoxin (EDN), may participate in pathological conditions. In this study, we aim to discover new biomarker for detecting ALS. Materials and Methods. We examined 44 patients with ALS, 41 patients with Alzheimer's disease, 41 patients with Parkinson's disease, and 44 healthy controls. The concentration of serum EDN was measured using an enzyme-linked immunosorbent assay. Results. EDN levels were significantly increased 2.17-fold in the serum of patients with ALS as compared with healthy controls (P < 0.05). No correlation between the levels of serum EDN and various clinical parameters of ALS was found. Moreover, the levels of serum EDN in patients with Parkinson's disease and Alzheimer's disease and healthy controls were similar. Conclusion. A higher level of serum EDN was found specifically in patients with ALS, indicating that EDN may participate in the pathophysiology of ALS.
Methanolic extracts of Gracilaria tenuistipitata (MEGT) were obtained from the edible red algae. Previously, we found that water extract of G. tenuistipitata was able to modulate oxidative stress-induced DNA damage and its related cellular responses.
In this study, the methanol extraction product MEGT was used to evaluate the cell growth inhibition in oral cancer cells and its possible mechanism was investigated.
The cell viability of MEGT treated Ca9-22 oral cancer cell line was significantly decreased in a dose–response manner (p < 0.05). The sub-G1 population and annexin V intensity of MEGT-treated Ca9-22 cancer cells were significantly increased in a dose–response manner (p < 0.0005 and p < 0.001, respectively). The γH2AX intensities of MEGT-treated Ca9-22 cancer cells were significantly increased in a dose–response manner (p < 0.05). The reactive oxygen species (ROS) and glutathione (GSH)-positive intensities of MEGT-treated Ca9-22 oral cancer cells were significantly increased and decreased, respectively, in a dose–response manner (p < 0.05). The DiOC2(3) intensity for mitochondrial membrane potential (MMP) of MEGT-treated Ca9-22 cancer cells was significantly decreased in a dose–response manner (p < 0.05).
These results indicated that MEGT had apoptosis-based cytotoxicity against oral cancer cells through the DNA damage, ROS induction, and mitochondrial depolarization. Therefore, MEGT derived from the edible algae may have potential therapeutic effects against oral squamous cell carcinoma (OSCC).
Red algae; Oral cancer; Apoptosis; γ-H2AX; ROS; Mitochondrial membrane potential; Glutathione
A cell culture system for the production of hepatitis C virus (HCV) whole virions has greatly accelerated studies of the virus life cycle and the discovery of anti-HCV agents. However, the quantification of the HCV titers in a whole-virus infection/replication system currently relies mostly on reverse transcription-PCR or immunofluorescence assay, which would be cumbersome for high-throughput drug screening. To overcome this problem, this study has generated a novel cell line, Huh7.5-EG(Δ4B5A)SEAP, that carries a dual reporter, EG(Δ4B5A)SEAP. The EG(Δ4B5A)SEAP reporter is a viral protease-cleavable fusion protein in which the enhanced green fluorescence protein is linked to secreted alkaline phosphatase (SEAP) in frame via Δ4B5A, a short peptide cleavage substrate for NS3/4A viral protease. This study demonstrates that virus replication/infection in the Huh7.5-EG(Δ4B5A)SEAP cells can be quantitatively indicated by measuring the SEAP activity in cell culture medium. The levels of SEAP released from HCV-infected Huh7.5-EG(Δ4B5A)SEAP cells correlated closely with the amounts of HCV in the inocula. The Huh7.5-EG(Δ4B5A)SEAP cells were also shown to be a suitable host for the discovery of anti-HCV inhibitors by using known compounds that target multiple stages of the HCV life cycle. The Z′-factor of this assay ranged from 0.64 to 0.74 in 96-well plates, indicating that this reporter system is suitable for high-throughput screening of prospective anti-HCV agents.
Hepatitis C virus (HCV) is a serious global problem, and present therapeutics are inadequate to cure HCV infection. In the present study, various antiviral assays show that As2O3 at submicromolar concentrations is capable of inhibiting HCV replication. The 50% effective concentration (EC50) of As2O3 required to inhibit HCV replication was 0.35 μM when it was determined by a reporter-based HCV replication assay, and the EC50 was below 0.2 μM when it was determined by quantitative reverse transcription-PCR analysis. As2O3 did not cause cellular toxicity at this concentration, as revealed by an MTS [3-(4,5-dimethylthiozol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] assay. A combination of As2O3 and alpha interferon exerted synergistic effects against HCV, as revealed by a multiple linear logistic model and isobologram analysis. Furthermore, in an alternative HCV antiviral system that may recapitulate additional steps involved in HCV infection and replication, As2O3 at 0.3 μM totally abolished the HCV signal, whereas alpha interferon at a high dose (5,000 IU/ml) only partially suppressed the HCV signal. The study highlights the indications for use of a novel class of anti-HCV agent. Further elucidation of the exact antiviral mechanism of As2O3 may lead to the development of agents with potent activities against HCV or related viruses.
Persistent/latent viral infections of insect cells are a prominent though poorly understood phenomenon. In this study, the long-term association between the Hz-1 virus and insect host cells, conventionally referred to as persistent viral infection, is described. With the aid of a newly developed fluorescent cell-labeling system, we found that productive viral replication occurs by spontaneous viral reactivation in fewer than 0.2% of persistently infected cell lines over a 5-day period. Once viral reactivation takes place, the host cell dies. The persistently infected cells contain various amounts of viral DNA, and, in an extreme case, up to 16% of the total DNA isolated from infected cells could be of viral origin. Both pulsed-field gel electrophoresis and in situ hybridization experiments showed that some of these viral DNA molecules are inserted into the host chromosomes but that the rest of viral DNA copies are free from host chromosomes. Thus, Hz-1 virus is the first nonretroviral insect virus known to insert its genome into the host chromosome during the infection process. These data also suggest that the previously described persistent infection of Hz-1 virus in insect cells should be more accurately referred to as latent viral infection.
Infection with the wild-type baculovirus Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) results in complete death of Spodoptera frugiperda (Sf) cells. However, infection of Sf cells with AcMNPV carrying a mutation or deletion of the apoptotic suppressor gene p35 allowed the cloning of surviving Sf cells that harbored persistent viral genomes. Persistent infection established with the virus with p35 mutated or deleted was blocked by stable transfection of p35 in the host genome or by insertion of the inhibitor of apoptosis (iap) gene into the viral genome. These artificially established persistently virus-infected cells became resistant to subsequent viral challenge, and some of the cell lines carried large quantities of viral DNA capable of early gene expression. Continuous release of viral progenies was evident in some of the persistently virus-infected cells, and transfection of p35 further stimulated viral activation of the persistent cells, including the reactivation of viruses in those cell lines without original continuous virus release. These results have demonstrated the successful establishment of persistent baculovirus infections under laboratory conditions and that their establishment may provide a novel continuous, nonlytic baculovirus expression system in the future.
Hepatitis C virus (HCV) is an important human pathogen leading to hepatocellular carcinoma. Using an in vitro cell-based HCV replicon and JFH-1 infection system, we demonstrated that an aqueous extract of the seaweed Gracilaria tenuistipitata (AEGT) concentration-dependently inhibited HCV replication at nontoxic concentrations. AEGT synergistically enhanced interferon-α (IFN-α) anti-HCV activity in a combination treatment. We found that AEGT also significantly suppressed virus-induced cyclooxygenase-2 (COX-2) expression at promoter transactivation and protein levels. Notably, addition of exogenous COX-2 expression in AEGT-treated HCV replicon cells gradually abolished AEGT anti-HCV activity, suggesting that COX-2 down-regulation was responsible for AEGT antiviral effects. Furthermore, we highlighted the inhibitory effect of AEGT in HCV-induced pro-inflammatory gene expression such as the expression of tumour necrosis factor-α, interleukin-1β, inducible nitrite oxide synthase and COX-2 in a concentration-dependent manner to evaluate the potential therapeutic supplement in the management of patients with chronic HCV infections.
Chronic hepatitis C virus (HCV) infection is the leading risk factor for hepatocellular carcinoma (HCC) and chronic liver disease worldwide. Green tea, in addition to being consumed as a healthy beverage, contains phenolic catechins that have been used as medicinal substances. In the present study, we illustrated that the epicatechin isomers (+)-epicatechin and (−)-epicatechin concentration-dependently inhibited HCV replication at nontoxic concentrations by using in vitro cell-based HCV replicon and JFH-1 infectious systems. In addition to significantly suppressing virus-induced cyclooxygenase-2 (COX-2) expression, our results revealed that the anti-HCV activity of the epicatechin isomers occurred through the down-regulation of COX-2. Furthermore, both the epicatechin isomers additively inhibited HCV replication in combination with either interferon-α or viral enzyme inhibitors [2′-C-methylcytidine (NM-107) or telaprevir]. They also had prominent anti-inflammatory effects by inhibiting the gene expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and inducible nitrite oxide synthase as well as the COX-2 in viral protein-expressing hepatoma Huh-7 cells. Collectively, (+)-epicatechin and (−)-epicatechin may serve as therapeutic supplements for treating HCV-related diseases.