Hydroxygenkwanin Increases the Sensitivity of Liver Cancer Cells to Chemotherapy by Inhibiting DNA Damage Response in Mouse Xenograft Models.

Molecules involved in DNA damage response (DDR) are often overexpressed in cancer cells, resulting in poor responses to chemotherapy and radiotherapy. Although treatment efficacy can be improved with the concomitant use of DNA repair inhibitors, the accompanying side effects can compromise the quality of life of patients. Therefore, in this study, we identified a natural compound that could inhibit DDR, using the single-strand annealing yeast-cell analysis system, and explored its mechanisms of action and potential as a chemotherapy adjuvant in hepatocellular carcinoma (HCC) cell lines using comet assay, flow cytometry, Western blotting, immunofluorescence staining, and functional analyses. We developed a mouse model to verify the in vitro findings. We found that hydroxygenkwanin (HGK) inhibited the expression of RAD51 and progression of homologous recombination, thereby suppressing the ability of the HCC cell lines to repair DNA damage and enhancing their sensitivity to doxorubicin. HGK inhibited the phosphorylation of DNA damage checkpoint proteins, leading to apoptosis in the HCC cell lines. In the mouse xenograft model, HGK enhanced the sensitivity of liver cancer cells to doxorubicin without any physiological toxicity. Thus, HGK can inhibit DDR in liver cancer cells and mouse models, making it suitable for use as a chemotherapy adjuvant.

Targeting HR Repair as a Synthetic Lethal Approach to Increase DNA Damage Sensitivity by a RAD52 Inhibitor in BRCA2-Deficient Cancer Cells.

BRCA mutation, one of the most common types of mutations in breast and ovarian cancer, has been suggested to be synthetically lethal with depletion of RAD52. Pharmacologically inhibiting RAD52 specifically eradicates BRCA-deficient cancer cells. In this study, we demonstrated that curcumin, a plant polyphenol, sensitizes BRCA2-deficient cells to CPT-11 by impairing RAD52 recombinase in MCF7 cells. More specifically, in MCF7-siBRCA2 cells, curcumin reduced homologous recombination, resulting in tumor growth suppression. Furthermore, a BRCA2-deficient cell line, Capan1, became resistant to CPT-11 when BRCA2 was reintroduced. In vivo, xenograft model studies showed that curcumin combined with CPT-11 reduced the growth of BRCA2-knockout MCF7 tumors but not MCF7 tumors. In conclusion, our data indicate that curcumin, which has RAD52 inhibitor activity, is a promising candidate for sensitizing BRCA2-deficient cells to DNA damage-based cancer therapies.

Development of single-chain variable fragments (scFv) against influenza virus targeting hemagglutinin subunit 2 (HA2).

Influenza A viruses (IAV) are widespread in birds and domestic poultry, occasionally causing severe epidemics in humans and posing health threats. Hence, the need to develop a strategy for prophylaxis or therapy, such as a broadly neutralizing antibody against IAV, is urgent. In this study, single-chain variable fragment (scFv) phage display technology was used to select scFv fragments recognizing influenza envelope proteins. The Tomlinson I and J scFv phage display libraries were screened against the recombinant HA2 protein (rHA2) for three rounds. Only the third-round elution sample of the Tomlinson J library showed high binding affinity to rHA2, from which three clones (3JA18, 3JA62, and 3JA78) were chosen for preparative-scale production as soluble antibody by E. coli. The clone 3JA18 was selected for further tests due to its broad affinity for influenza H1N1, H3N2 and H5N1. Simulations of the scFv 3JA18-HA trimer complex revealed that the complementarity-determining region of the variable heavy chain (VH-CDR2) bound the stem region of HA. Neutralization assays using a peptide derived from VH-CDR2 also supported the simulation model. Both the selected antibody and its derived peptide were shown to suppress infection with H5N1 and H1N1 viruses, but not H3N2 viruses. The results also suggested that the scFvs selected from rHA2 could have neutralizing activity by interfering with the function of the HA stem region during virus entry into target cells.

A recommended integrated mechanism to enhance OSH management of blue-collar foreign workers in Taiwan.

This study examines the roles and functions of businesses, labor-exporting countries' representative offices in Taiwan, religious organizations, and manpower agencies in promoting occupational safety and health (OSH). It also offers advice to Taiwanese authorities on making policies and improvements regarding the oversight mechanism mandated by the Labor Safety and Health Act, giving them an idea of what to focus on when enforcing control over blue-collar foreign workers' OSH conditions. This study also proposes that Taiwanese authorities may serve not only as an overseer/inspector of those hiring blue-collar foreign workers in Taiwan, but also expand their role to lay down policies regarding a variety of OSH teaching materials in the blue-collar foreign workers' native languages (spoken or written), the qualifications of translators in blue-collar foreign workers' OSH training programs, and regulations concerning the longer hours such training programs take.

Identification of genomic regions controlling spikelet degeneration under FRIZZLE PANICLE (FZP) defect genetic background in rice.

The FZP gene plays a critical role in the formation of lateral branches and spikelets in rice panicle architecture. This study investigates the qSBN7 allele, a hypomorphic variant of FZP, and its influence on panicle architectures in different genetic backgrounds. We evaluated two backcross inbred lines (BILs), BC5_TCS10sbn and BC3_TCS10sbn, each possessing the homozygous qSBN7 allele but demonstrating differing degrees of spikelet degeneration. Our analysis revealed that BC5_TCS10sbn had markedly low FZP expression, which corresponded with an increase in axillary branches and severe spikelet degeneration. Conversely, BC3_TCS10sbn exhibited significantly elevated FZP expression, leading to fewer secondary and tertiary branches, and consequently decreased spikelet degeneration. Compared to BC5_TCS10sbn, BC3_TCS10sbn carries three additional chromosomal substitution segments from its donor parent, IR65598-112-2. All three segments significantly enhance the expression of FZP and reduce the occurrence of tertiary branch and spikelet degeneration. These findings enhance our understanding of the mechanisms regulating FZP and aid rice breeding efforts.

Increasing DNA damage sensitivity through corylin-mediated inhibition of homologous recombination.

BACKGROUND: DNA repair allows the survival of cancer cells. Therefore, the development of DNA repair inhibitors is a critical need for sensitizing cancers to chemoradiation. Sae2CtIP has specific functions in initiating DNA end resection, as well as coordinating cell cycle checkpoints, and it also greatly interacts with the DDR at different levels. RESULTS: In this study, we demonstrated that corylin, a potential sensitizer, causes deficiencies in DNA repair and DNA damage checkpoints in yeast cells. More specifically, corylin increases DNA damage sensitivity through the Sae2-dependent pathway and impairs the activation of Mec1-Ddc2, Rad53-p and γ-H2A. In breast cancer cells, corylin increases apoptosis and reduces proliferation following Dox treatment by inhibiting CtIP. Xenograft assays showed that treatment with corylin combined with Dox significantly reduced tumor growth in vivo. CONCLUSIONS: Our findings herein delineate the mechanisms of action of corylin in regulating DNA repair and indicate that corylin has potential long-term clinical utility as a DDR inhibitor.

Analysis of anabolic androgenic steroids in urine by full-capillary sample injection combined with a sweeping CE stacking method.

This study describes an on-line stacking CE approach by sweeping with whole capillary sample filling for analyzing five anabolic androgenic steroids in urine samples. The five anabolic steroids for detection were androstenedione, testosterone, epitestosterone, boldenone, and clostebol. Anabolic androgenic steroids are abused in sport doping because they can promote muscle growth. Therefore, a sensitive detection method is imperatively required for monitoring the urine samples of athletes. In this research, an interesting and reliable stacking capillary electrophoresis method was established for analysis of anabolic steroids in urine. After liquid-liquid extraction by n-hexane, the supernatant was dried and reconstituted with 30 mM phosphate buffer (pH 5.00) and loaded into the capillary by hydrodynamic injection (10 psi, 99.9 s). The stacking and separation were simultaneously accomplished at -20 kV in phosphate buffer (30 mM, pH 5.0) containing 100 mM sodium dodecyl sulfate and 40 % methanol. During the method validation, calibration curves were linear (r≥0.990) over a range of 50-1,000 ng/mL for the five analytes. In the evaluation of precision and accuracy for this method, the absolute values of the RSD and the RE in the intra-day (n=3) and inter-day (n=5) analyses were all less than 6.6 %. The limit of detection for the five analytes was 30 ng/mL (S/N=5, sampling 99.9 s at 10 psi). Compared with simple MECK, this stacking method possessed a 108- to 175-fold increase in sensitivity. This simple and sensitive stacking method could be used as a powerful tool for monitoring the illegal use of doping.

The flavonoid corylin exhibits lifespan extension properties in mouse.

In the long history of traditional Chinese medicine, single herbs and complex formulas have been suggested to increase lifespan. However, the identification of single molecules responsible for lifespan extension has been challenging. Here, we collected a list of traditional Chinese medicines with potential longevity properties from pharmacopeias. By utilizing the mother enrichment program, we systematically screened these traditional Chinese medicines and identified a single herb, Psoralea corylifolia, that increases lifespan in Saccharomyces cerevisiae. Next, twenty-two pure compounds were isolated from Psoralea corylifolia. One of the compounds, corylin, was found to extend the replicative lifespan in yeast by targeting the Gtr1 protein. In human umbilical vein endothelial cells, RNA sequencing data showed that corylin ameliorates cellular senescence. We also examined an in vivo mammalian model, and found that corylin extends lifespan in mice fed a high-fat diet. Taken together, these findings suggest that corylin may promote longevity.

Stability of gp41 hairpin and helix bundle assembly probed by combined stacking and circular dichroic approaches.

The envelope glycoprotein gp41 of HIV-1 undergoes structural rearrangement to form a helix hairpin during the virus-mediated fusion. Previous studies to investigate the folding and stability of hairpin did not monitor the end-to-end distance of the molecule. To directly probe the distance change, rhodamine dye was conjugated to the gp41 recombinant near the N- and C-terminal regions to detect the UV absorption and fluorescence intensity changes induced by the chemical denaturant guanidinium chloride (GdmCl). Using the singly- and doubly-labeled constructs allowed us to distinguish between the hairpin formation and protein oligomerization. A biphasic transition of helical structure for the wild type protein was revealed by circular dichroism measurements while unfolding of the hairpin occurred at 6M GdmCl. The relevance of our study to the fusion inhibitor for HIV-1 was borne out by results on the mutants at the positions within the N-terminal heptad repeat (NHR) and the C-terminal heptad repeat (CHR) regions. A monophasic transition at lower denaturant concentration was detected for the NHR mutant supporting the concept of differential stability of NHR and CHR helical structure. The conclusion that the observed unstacking of doubly-labeled variant arises principally from the intra-molecular dimers was drawn from the unstacking of the protein labeled in the loop. Remarkably, it is deduced that the hairpin is more stable than the CHR helical structure. A model for denaturation of the helix hairpin bundle was proposed from these results. The biological implications of the findings and further applications of the distance-based approach were discussed.

Biological monitoring of low-level 2-butoxyethanol exposure in decal transfer workers in bicycle manufacturing factories.

OBJECTIVES: In this study, exposures to ethylene glycol monobutyl ether (or 2-butoxyethanol, 2-BE) in decal transfer workers in the bicycle manufacturing industry were investigated. Personal air sampling and biological monitoring were used to assess total uptake through inhalation and dermal exposure. Haemoglobin was also analysed to evaluate the effects of exposure on the haematopoietic system. METHODS: 80 workers in two bicycle factories completed a questionnaire. NIOSH method 1403 was adopted for air sampling and analysis of 2-BE. Prework and postwork urine samples were also collected for determination of total 2-butoxyacetic acid (BAA) after hydrolysis. Haemoglobin tests were performed using an automated haemoglobin analysis system. RESULTS: The 31 decal transfer workers whose hands were in direct contact with a dilute aqueous solution of 2-BE, were exposed to an average of 1.7 ppm (8.1 mg/m(3)) of 2-BE in air. Correlation of 2-BE in air and postshift urinary BAA levels (after hydrolysis) was poor. Postshift total BAA levels in urine on Monday and Friday (446.8 and 619.4 mg/g creatinine) were around 223% and 310% of the ACGIH proposed Biological Exposure Index (BEI; 200 mg/g creatinine). Higher levels of total BAA were observed in the urine of subjects exposed to low-level 2-BE in air, presumably because of direct dermal contact. CONCLUSIONS: The mean preshift BAA on Friday was significantly higher than that on Monday, implying that the more days of exposures, the higher the accumulation. Since accumulation occurred with low-level exposure to 2-BE, it is recommended that urine samples be collected at the end of the working week.

Urinary 8-hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to ethylbenzene.

This study assessed the relationships between ethylbenzene exposure and levels of 8-hydroxydeoxyguanosine (8-OHdG) among spray painters. Sixty-four male workers employed at a large shipyard were recruited for this investigation. Fifteen spray painters exposed to paint, together with two non-exposed groups, namely 19 sandblasting workers and 30 office staffs were selected as the subjects. Personal exposure to xylene and ethylbenzene in air were collected using diffusive samplers. Urine samples of the spray painters were collected after a month-long holiday leave and during the pre- and post-workshifts. Urine samples of sandblasting workers and office staffs were gathered after their shift. Urinary mandelic acid and methyl hippuric acid were used as biological indices of dose of ethylbenzene and xylene, respectively. Urinary 8-OHdG was used as biomarker of oxidative DNA damage. The post-workshift concentration of urinary 8-OHdG for 10 spray painters (30.3 ± 9.28 µg g(-1) creatinine) significantly exceeded that of holiday leave (7.20 ± 1.08 µg g(-1) creatinine; P = 0.001). The post-workshift concentration of urinary 8-OHdG was higher among 15 spray painters (29.0 ± 6.52 µg g(-1) creatinine) than sandblasting workers (9.14 ± 2.05 µg g(-1) creatinine; P = 0.01) and office staffs (8.35 ± 0.84 µg g(-1) creatinine; P = 0.007). A stepwise regression model revealed an 8.11 µg g(-1) creatinine increase per 1 p.p.m. increase in ethylbenzene [95% confidence interval (CI) 4.13-12.1]. A stepwise regression model revealed an increase of 6.04 µg g(-1) creatinine (95% CI 2.23-9.84) per 1 p.p.m. in ethylbenzene after adjustment of age (95% CI 2.23-9.84). This pilot study suggests that occupational exposure to paint increases oxidative DNA injury. Moreover, urinary 8-OHdG levels displayed greater DNA damage in spray painters compared to other unexposed groups and their holiday leave samples. A significant correlation was found between urinary 8-OHdG and the exposure to ethylbenzene. The ethylbenzene exposure could not explain all urinary 8-OHdG measured. Other components of paint deserve further investigation.

The fusion peptide domain is the primary membrane-inserted region and enhances membrane interaction of the ectodomain of HIV-1 gp41.

To execute the membrane fusion function, it is necessary for the fusion protein of the virus to penetrate into the hydrophobic milieu of membrane bilayer. Hence identification of the region(s) of the ectodomain of viral fusion proteins involved in the membrane insertion and their interaction with the rest of the fusion protein in the membrane would be important for the mechanistic study of membrane fusion. To this end, we examined membrane activity of the fusion peptide, and the ectodomain protein with or without the fusion peptide domain of HIV-1 gp41 by several biophysical measurements. The results revealed that the ectodomain protein containing the fusion peptide domain had higher membrane-perturbing activity and deeper membrane insertion, while the construct lacking the fusion peptide domain had much lower membrane activity. Strikingly, the N-terminal heptad repeat region was found to be induced deeper into the membrane by the fusion peptide, consistent with the role of the latter in the membrane penetration. We concluded that the fusion peptide is the only stretch of gp41 ectodomain that embeds deeply in the membrane interior in the prefusion stage. The function of fusion peptide in terms of membrane interaction and the implications of its interplay with other domains of gp41 on the membrane fusion cascade were discussed.

2-O-Methylmagnolol, a Magnolol Derivative, Suppresses Hepatocellular Carcinoma Progression via Inhibiting Class I Histone Deacetylase Expression.

Magnolia officinalis is widely used in Southeast Asian countries for the treatment of fever, headache, diarrhea, and stroke. Magnolol is a phenolic compound extracted from M. officinalis, with proven antibacterial, antioxidant, anti-inflammatory, and anticancer activities. In this study, we modified magnolol to synthesize a methoxylated derivative, 2-O-methylmagnolol (MM1), and investigated the use of MM1, and magnolol in the treatment of liver cancer. We found that both magnolol and MM1 exhibited inhibitory effects on the growth, migration, and invasion of hepatocellular carcinoma (HCC) cell lines and halted the cell cycle at the G1 phase. MM1 also demonstrated a substantially better tumor-suppressive effect than magnolol. Further analysis suggested that by inhibiting class I histone deacetylase expression in HCC cell lines, magnolol and MM1 induced p21 expression and p53 activation, thereby causing cell cycle arrest and inhibiting HCC cell growth, migration, and invasion. Subsequently, we verified the significant tumor-suppressive effects of magnolol and MM1 in an animal model. Collectively, these findings demonstrate the anti-HCC activities of magnolol and MM1 and their potential for clinical use.

Membrane interaction and structure of the transmembrane domain of influenza hemagglutinin and its fusion peptide complex.

BACKGROUND: To study the organization and interaction with the fusion domain (or fusion peptide, FP) of the transmembrane domain (TMD) of influenza virus envelope glycoprotein for its role in membrane fusion which is also essential in the cellular trafficking of biomolecules and sperm-egg fusion. RESULTS: The fluorescence and gel electrophoresis experiments revealed a tight self-assembly of TMD in the model membrane. A weak but non-random interaction between TMD and FP in the membrane was found. In the complex, the central TMD oligomer was packed by FP in an antiparallel fashion. FP insertion into the membrane was altered by binding to TMD. An infrared study exhibited an enhanced membrane perturbation by the complex formation. A model was built to illustrate the role of TMD in the late stages of influenza virus-mediated membrane fusion reaction. CONCLUSION: The TMD oligomer anchors the fusion protein in the membrane with minimal destabilization to the membrane. Upon associating with FP, the complex exerts a synergistic effect on the membrane perturbation. This effect is likely to contribute to the complete membrane fusion during the late phase of fusion protein-induced fusion cascade. The results presented in the work characterize the nature of the interaction of TMD with the membrane and TMD in a complex with FP in the steps leading to pore initiation and dilation during virus-induced fusion. Our data and proposed fusion model highlight the key role of TMD-FP interaction and have implications on the fusion reaction mediated by other type I viral fusion proteins. Understanding the molecular mechanism of membrane fusion may assist in the design of anti-viral drugs.

Sensing capability of the localized surface plasmon resonance of gold nanorods.

We demonstrate the feasibility of using the longitudinal component of gold nanorod's surface plasmon resonance in biomolecular sensing. The sensitive dependence of the absorption maximum on the dielectric constant of the particle interfacial region makes gold nanorods a promise for constructing a biomolecular sensing scheme. The sensor containing gold nanorods, with a mean aspect ratio of 5.2, exhibits a sensitivity of ca. 366 nm/RIU (refractive index unit), which increases accordingly with the increase of the particle mean aspect ratios. Such a biosensor was further modified to demonstrate its effectiveness in quantitative detection for selective binding events, such as biotin/streptavidin pairs, through a process in which biotin molecules were chemically attached to the gold nanorods' surface prior to detection measurements. Results showed that the spectral lambda(max) shifts linearly to the concentrations of the streptavidin. The results from both experiment and model calculations strongly indicate the efficacy of the longitudinal surface plasmon absorption band in biosensing.

Dermal absorption of solvents as a major source of exposure among shipyard spray painters.

OBJECTIVE: The purpose of this study was to evaluate the relevance of inhalational and dermal exposure to solvents in shipyard spray painters. Special emphasis was placed on the spatial distribution of dermal exposure and absorption across different regions of the body. METHODS: Fifteen male spray painters were recruited for this study. The subjects were monitored during a 3-day work period using a repeated-measures study design. Air and dermal exposure of solvents were collected each day. Urine was collected before and after the work shift. RESULTS: Air samples showed that the workers were primarily exposed to ethylbenzene and xylene. The concentrations of ethylbenzene and xylene outside the workers' masks were 59.2 +/- 10.4 (mean +/- standard error [SE]) ppm and 29.4 +/- 4.70 ppm, whereas those inside the masks were 7.91 +/- 17.4 ppm and 3.83 +/- 8.22 ppm, respectively. The average mass of ethylbenzene and xylene across the different body regions inside the block units of assembled ships were 305.1 +/- 63.9 mg and 165.6 +/- 34.1 mg. The quantity was, on average, 5.8 and 5.1 times higher than those collected outside the blocks. In both measurements, the highest exposure mass was found on the upper legs, and the lowest exposure mass was found on the back. Principal component analysis (PCA) was used to transform the variables of dermal exposure for all investigated body regions into only one principal component. Multiple regression analyses revealed a significant relationship between dermal exposure to xylene (PCA dermal xyl) and urinary methylhippuric acid (MHA) levels, adjusting for air xylene exposure (R2=0.491, P<0.05). CONCLUSIONS: :The present study indicated that dermal exposure to xylene significantly increased the urinary levels of MHA, suggesting that dermal exposure to solvents was an important route among spray painters.

pH-dependence of intermediate steps of membrane fusion induced by the influenza fusion peptide.

Membrane fusion mediated by the influenza-virus fusion protein is activated by low pH via a cascade of reactions. Some processes among them are irreversible, such as helix hairpin formation of the ectodomain, whereas others are reversible, such as exposure of the fusion peptide. Using this property, we attempted to dissect, in temporal order, different stages of the fusion reaction involving the fusion peptide by an acidic-neutral-acidic pH cycle. The fluorescence-quenching data indicated that both insertion depth and self-assembly are pH-reversible. In addition, lipid mixing assay was demonstrated to be arrested by neutral pH. By contrast, membrane leakage was shown to be irreversible with respect to pH. Our results, along with those from other studies on the pH-dependence of membrane fusion, are used to build a model for the virus-mediated fusion event from the perspective of pH-reversibility.

Self-association of glutamic acid-rich fusion peptide analogs of influenza hemagglutinin in the membrane-mimic environments: effects of positional difference of glutamic acids on side chain ionization constant and intra- and inter-peptide interactions deduced from NMR and gel electrophoresis measurements.

Two glutamic acid-rich fusion peptide analogs of influenza hemagglutinin were synthesized to study the organization of the charged peptides in the membranous media. Fluorescence and gel electrophoresis experiments suggested a loose association between the monomers in the vesicles. A model was built which showed that a positional difference of 3, 7 and 4, 8 results in the exposure of Glu3 and Glu7 side chains to the apolar lipidic core. Supportive results include: first, pK(a) values of two pH units higher than reference value in aqueous medium for Glu3 and Glu7 CgammaH, whereas the deviation of pK(a) from the reference value for Glu4 and Glu8 CgammaH is substantially smaller; second, Hill coefficients of titration shift of these protons indicate anti-cooperativity for Glu3 and Glu7 side chain protons but less so for Glu4 and Glu8, implying a strong electrostatic interaction between Glu3 and Glu7 possibly resulting from their localization in an apolar environment; third, positive and larger titration shift for NH of Glu3 is observed compared to that of Glu4, suggesting stronger hydrogen bond between the NH and the carboxylic group of Glu3 than that of Glu4, consistent with higher degree of exposure to hydrophobic medium for the side chain of Glu3.

Hazard Prevention Regarding Occupational Accidents Involving Blue-Collar Foreign Workers: A Perspective of Taiwanese Manpower Agencies.

Since 1989, blue-collar foreign workers have been permitted to work in Taiwanese industries. Most blue-collar foreign workers apply for jobs in Taiwan through blue-collar foreign workers' agencies. Because blue-collar foreign workers are not familiar with the language and culture in Taiwan, in occupational accident education and hazard prevention, the agencies play an important role in the coordination and translation between employees and blue-collar foreign workers. The purpose of this study is to establish the agencies' role in the occupational accidents education and hazard prevention for blue-collar foreign workers in Taiwan. This study uses a qualitative method-grounded theory-to collect, code, and analyze the data in order to understand the agencies' role in occupational accident education and hazard prevention for blue-collar foreign workers in Taiwan. The results show that the duty of agencies in occupational accident education and hazard prevention includes selecting appropriate blue-collar foreign workers, communicating between employees and blue-collar foreign workers, collecting occupational safety and health information, assisting in the training of occupational safety and health, and helping blue-collar foreign workers adapt to their lives in Taiwan. Finally, this study suggests seven important points and discusses the implementation process necessary to improve governmental policies. The government and employees should pay attention to the education/training of occupational safety and health for blue-collar foreign workers to eliminate unsafe behavior in order to protect the lives of blue-collar foreign workers.