Increased cAMP-PKA signaling pathway activation is involved in up-regulation of CTLA-4 expression in CD4+ T cells in acute SIVmac239-infected Chinese rhesus macaques

Human immunodeficiency virus-1 (HIV-1) infection can cause chronic activation, exhaustion, and anergy of the immune system. Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is an immune checkpoint molecule, which plays an important role in immune homeostasis and disease. CTLA-4 expression is elevated in HIV-1-infected patients and is associated with disease progression. However, the mechanism controlling expression of CTLA-4 in HIV-1 infection is poorly characterized. In this study, we used a SIV-infected Chinese rhesus macaque (ChRM) model to explore CTLA-4 expression in SIV infection. Results showed that SIV infection significantly increased CTLA-4 expression in all T cell subsets, especially central memory T cells. CTLA-4+CD4+ T cell frequency was significantly associated with disease progression markers. Activation of the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway regulated CTLA-4 expression in CD4+T cells, as confirmed by stimulation with dibutyryl cyclic adenosine monophosphate, forskolin, and 3-isobutyl-1-methylxanthine, and inhibition with H-89 ex vivo. Simultaneously, cAMP concentration in PBMCs and PKA activity in both PBMCs and CD4+ T cells were increased in acute SIV-infected ChRMs, accompanied by an increase in adenylate cyclase 6 expression and a decrease in cAMP-phosphodiesterase 3A (PDE3A), PDE4B, and PDE5A expression in PBMCs. In addition, selective inhibition of PDE4B and PDE5A activity enhanced CTLA-4 expression in CD4+ T cells. These results suggest that SIV infection alters cAMP metabolism and increases cAMP-PKA signaling pathway activation, which up-regulates the expression of CTLA-4 in acute SIVmac239-infected ChRMs. Thus, regulation of the cAMP-PKA signaling pathway may be a potential strategy for the restoration of T cell function and therapy for AIDS.

Nanodrug regulates lactic acid metabolism to reprogram the immunosuppressive tumor microenvironment for enhanced cancer immunotherapy

A majority of cancers fail to respond to immunotherapy due to the immunosuppressive tumor microenvironment (TME), and metabolic regulation of the TME has been a promising strategy to improve immunotherapy. Lactate is a key metabolic player in tumor immune response since its excess secretion aggravates tumor immune escape by favoring the polarization of tumor-associated macrophages (TAMs) to an immunosuppressive phenotype meanwhile impeding the tumor infiltration of the cytotoxic T lymphocyte. Here, we proposed a metabolic reprogramming mechanism to ameliorate tumor immunosuppression by using lonidamine and syrosingopine incorporated liposomes (L@S/L) to regulate lactate production and efflux. Concretely, lonidamine reduced lactate production by affecting the glycolytic metabolic pathway while syrosingopine decreased lactate efflux by inhibiting the key protein expression of the lactate transporter MCT-4. Consequently, both the drugs synergistically normalize the pH of the TME to overcome the tumor immunosuppressive microenvironment. In vivo studies demonstrated that the decreased extracellular lactate preferentially polarized TAMs to the M1 phenotype, simultaneously increased the proportion of NK cells and reduced the number of Treg cells. These results validated an efficient tumor immunotherapy in the breast cancer model. This new strategy of lactic acid metabolism regulation is proposed to operate in concert with immune modulation in the TME, which shows great potential for immunotherapy of immunologically "cold" tumors.

[Efficacy and safety of neoadjuvant apatinib in combination with dose-dense paclitaxel and carboplatin in locally advanced triple negative breast cancer patients]

Objective: To observe the short-term efficacy and safety of apatinib in combination with dose-dense paclitaxel and carboplatin in locally advanced triple-negative breast cancer (TNBC) patients. Methods: From September 2018 to September 2019, 17 stage Ⅱ/Ⅲ TNBC patients were enrolled in this single arm, single center prospective phase Ⅱ study. They received neoadjuvant treatment of apatinib 250 mg per day, paclitaxel 175 mg/m(2) on 1(st) day and a dose of carboplatin according to the area under curve (AUC)=4 on 2(nd) day, every 14 days as a cycle. Results: By January 2020, 16 cases completed 4-7 cycles of apatinib treatment and 4-8 cycles of chemotherapy. The median cycles of apatinib treatment and chemotherapy were 5 cycles and 6 cycles, respectively. Two cases achieved complete responses (CR), 12 achieved partial responses (PR), 2 achieved stable diseases (SD) and no progressive disease was observed. The objective response rate (ORR) was 87.5%, disease control rate (DCR) was 100%. By January 2020, among 12 patients who received surgery, 8 achieved pathologic complete response (pCR, 66.7%). The grade Ⅲ/Ⅳ adverse events included: neutropenia, thrombocytopenia in 3 cases (18.8%) each, anemia, fatigue, arrhythmia and alanine aminotransferase (ALT) elevation in 1 case each. Apatinib was interrupted in 5 cases, and was discontinued in 3 cases; chemotherapy dosage was reduced in 1 case. Conclusion: Apatinib in combination with dose-dense paclitaxel and carboplatin neoadjuvant therapy are effective and well tolerated in locally advanced TNBC patients.

Relationship between Fundamental Movement Skills and Physical Activity in Preschool-Aged Children: A Systematic Review

Preschool-aged children are in a critical period of developing fundamental movement skills (FMS). FMS have a close link with physical activity (PA). This study aimed to systematically review the associations between FMS and PA in preschool-aged children. Searching Cochrane Library, Web of Science, PubMed, ScienceDirect, and EBSCO (including SPORTDiscus, ERIC, and Academic Search Premier) was utilized to conduct a systematic review of the available literature. Studies were included if they examined associations between FMS and PA among typically developing children aged 3-6 years, published between January 2000 and April 2020. A total of 26 studies met the inclusion criteria, including 24 cross-sectional studies and two cohort studies. There was a strong level of evidence to support low to moderate associations between moderate to vigorous physical activity and components of FMS, specifically, the total FMS (r = 0.11-0.48, R2 = 16%-19%) and object control skill (r = 0.16-0.46, β = 0.28-0.49, R2 = 10.4%-16.9%). Similar associations were also found between the total physical activity and components of FMS, specifically, the total FMS (r = 0.10-0.45, R2 = 16%), locomotor skills (r = 0.14-0.46, R2 = 21.3%), and objective control skills (r = 0.16-0.44, β = 0.47, R2 = 19.2%). There was strong evidence that there is no significant association between light physical activity and FMS, specifically, total FMS and locomotor skills. The associations, including "stability skills-PA" and "locomotor skills-moderate to vigorous PA", were uncertain due to insufficient evidence. Our findings provide strong evidence of associations between specific FMS components and a specific PA intensity. Future studies should consider using a longitudinal study design in order to explore the causal relationship between specific-intensity PA and the FMS subdomain.

Thermal degradation kinetics investigation on Nano-ZnO/IFR synergetic flame retarded polypropylene/ethylene-propylene-diene monomer composites processed via different fields

In the field of polymer processing, disperse phase exhibited better dispersion and distribution performance in elongational field rather than shearing field. This property commonly brought a better functional feature for polymer composites. It could also be applied to Nano-ZnO/IFR synergetic flame retarded polypropylene/ ethylene-propylene-diene monomer composites. An experiment was designed to study the mechanism of improving flame retardant properties. In the experiment, the same formulas of composites were extruded by vane extruder (represents elongational field) and three-screw extruder (represents shearing field). Then Kissinger method and Flynn-Wall-Ozawa method were used to mutually proved that Nano-ZnO with better dispersion condition catalysed a more intense esterification of IFR in the whole thermal degradation process.

Reducing 3,4-dihydroxyphenylpyruvic acid to d-3,4-dihydroxyphenyllactic acid via a coenzyme nonspecific d-lactate dehydrogenase from Lactobacillus reuteri

AIMS

The purpose of this work was to find an efficient enzyme to synthesize d-3,4-dihydroxyphenyllactic acid (d-DSS).

METHODS AND RESULTS

Nineteen lactic acid bacteria strains were screened for production of d-DSS using 3,4-dihydroxyphenylpyruvic acid (DPA) as a substrate. Lactobacillus reuteri JN516 exhibited the highest d-DSS yield. A nonspecific coenzyme, d-lactate dehydrogenase (d-LDH82319), from L. reuteri JN516 with high DPA reducing activity was identified. This enzyme reduced DPA to form d-DSS with excellent optical purity (enantioselectivity >99%). Its molecular weight was 35 kDa based on SDS-PAGE migration. The Michaelis-Menten constant (Km ), turnover number (kcat ), and catalytic efficiency (kcat /Km ) of d-LDH82319 for DPA were 0·09 mmol l-1 , 2·17 s-1 and 24·07 (mmol l-1 )-1  s-1 , respectively, with NADH as the coenzyme. The (Km ), (kcat ) and (kcat /Km ) of d-LDH82319 for DPA were 0·10 mmol l-1 , 0·13 s-1 and 1·30 (mmol l-1 )-1  s-1 , respectively, with NADPH as the coenzyme. The optimum temperature and pH of d-LDH82319 were 25°C and pH 8 respectively. Additionally, d-LDH82319 had a broad substrate range for alpha-keto acids, among which the activity of reducing pyruvate was the strongest; therefore, it belongs to the group of d-lactate dehydrogenases. d-LDH82319 and glucose dehydrogenase (GDH) were coexpressed to produce d-DSS from DPA.

CONCLUSIONS

d-LDH82319 from L. reuteri JN516 with high DPA reducing activity has the characteristics of a nonspecific coenzyme.

SIGNIFICANCE AND IMPACT OF THE STUDY

d-LDH82319 is the first reported coenzyme nonspecific d-lactate dehydrogenase with DPA-reducing activity. The coexpression system provided an effective method to produce d-DSS.

Root-soil air gap and resistance to water flow at the soil-root interface of Robinia pseudoacacia

During periods of water deficit, growing roots may shrink, retaining only partial contact with the soil. In this study, known mathematical models were used to calculate the root-soil air gap and water flow resistance at the soil-root interface, respectively, of Robinia pseudoacacia L. under different water conditions. Using a digital camera, the root-soil air gap of R. pseudoacacia was investigated in a root growth chamber; this root-soil air gap and the model-inferred water flow resistance at the soil-root interface were compared with predictions based on a separate outdoor experiment. The results indicated progressively greater root shrinkage and loss of root-soil contact with decreasing soil water potential. The average widths of the root-soil air gap for R. pseudoacacia in open fields and in the root growth chamber were 0.24 and 0.39 mm, respectively. The resistance to water flow at the soil-root interface in both environments increased with decreasing soil water potential. Stepwise regression analysis demonstrated that soil water potential and soil temperature were the best predictors of variation in the root-soil air gap. A combination of soil water potential, soil temperature, root-air water potential difference and soil-root water potential difference best predicted the resistance to water flow at the soil-root interface.

Lignocellulolytic enzyme profiles of edible mushroom fungi

One of the most economically-viable processes for the bioconversion of many types of lignocellulosic wastes is represented by edible mushroom cultivation. Lentinula edodes, Volvariella volvacea and Pleurotus sajor-caju are three important commercially cultivated mushrooms which exhibit varying abilities to utilise different lignocellulosics as growth substrate. Examination of the lignocellulolytic enzyme profiles of the three species show this diversity to be reflected in qualitative variations in the major enzymic determinants (i.e. cellulases, ligninases) required for substrate bioconversion. For example, L. edodes, which is cultivated on highly lignified substrates such as wood or sawdust, produces two extracellular enzymes which have been associated with lignin depolymerisation in other fungi, (manganese peroxidase and laccase). Conversely, V. volvacea, which prefers high cellulose-, low lignin-containing substrates produces a family of cellulolytic enzymes including at least five endoglucanases, five cellobiohydrolases and two β-glucosidases, but none of the recognised lignin-degrading enzymes.

The short-time treatment with curcumin sufficiently decreases cell viability, induces apoptosis and copper enhances these effects in multidrug-resistant K562/A02 cells

The anti-cancer activities of curcumin (CUR), a polyphenol derived from the plant Curcuma longa, has been extensively studied. In the present study, we found that CUR displayed anti-multidrug-resistant (MDR) activity in K562/A02 cells. A short-time treatment with CUR sufficiently and equally induced DNA damage, decreased cell viability, and triggered apoptosis in parent K562 and MDR K562/A02 cells. The short-time treatment with CUR also caused decrease of pro-caspase 3 in both cell lines and decrease of pro-caspase 9, increase of PARP cleavage and the ratio of Bax/Bcl-xL in MDR K562/A02 cells. Further experiment revealed that CUR was capable of down-regulating P-glycoprotein in MDR K562/A02 cells. Moreover, we observed that Cu(2+) enhanced CUR-mediated apoptosis which was blocked by antioxidants N-acetyl-cysteine and catalase. In summary, the short-time treatment with CUR sufficiently induced DNA damage, decreased cell viability and triggered apoptosis in MDR K562/A02 cells and Cu(2+) enhanced CUR-mediated apoptosis which due to reactive oxygen species generation.

Low-dose 5-fluorouracil induces cell cycle G2 arrest and apoptosis in keloid fibroblasts

BACKGROUND

Intralesional injection of low-dose 5-fluorouracil (5-FU) has recently been used as an experimental modality for treating keloid scarring and has shown promising efficacy in improving scar appearance and preventing recurrence of the keloid.

OBJECTIVES

We sought to explore the cellular- and molecular-based evidence for the observed clinical benefits.

METHODS

Primary cell lines of keloid fibroblasts were treated with 5-FU at a range of lower doses (∼10 mg mL(-1) ) in monolayer culture and subjected to examination for cell viability, proliferative potential, apoptosis, cell cycle and associated proteins involved in cell cycle control.

RESULTS

5-FU significantly inhibited cell proliferation of keloid fibroblasts in the full dose range used in this study. The DNA synthesis was completely inhibited by 5-FU at 72 h, and significant cell apoptosis was observed at concentrations ≥ 1 mg mL(-1) for a period over 72 h. 5-FU caused a significant delay in cell cycle progression and the G2/M phase arrest. 5-FU induced p53 and p21 accumulation together with a decrease in cyclin B1 and Bcl-2 levels in treated keloid fibroblasts.

CONCLUSIONS

Our data indicate that low-dose 5-FU (as low as 1 mg mL(-1) ) induces significant inhibition of proliferation, G2/M cell cycle arrest and apoptosis but not immediate cell death of keloid fibroblasts. The lack of tissue necrosis is a particular benefit as further scarring is likely to be prevented. These results support the use of low-dose 5-FU as a potential modality for treating keloid scars.

A novel nonionic surfactant- and solvent-stable alkaline serine protease from Serratia sp. SYBC H with duckweed as nitrogen source: production, purification, characteristics and application

A novel nonionic surfactant- and hydrophilic solvent-stable alkaline serine protease was purified from the culture supernatant of Serratia sp. SYBC H with duckweed as nitrogen source. The molecular mass of the purified protease is about 59 kDa as assayed via SDS-PAGE. The protease is highly active over the pH range between 5.0 and 11.0, with the maximum activity at pH 8.0. It is also fairly active over the temperature range between 30 and 80°C, with the maximum activity at 40°C. The protease activity was substantially stimulated by Mn(2+) and Na(+) (5 mM), up to 837.9 and 134.5% at 40°C, respectively. In addition, Mn(2+) enhanced the thermostability of the protease significantly at 60°C. Over 90% of its initial activity remained even after incubating for 60 min at 40°C in 50% (v/v) hydrophilic organic solvents such as DMF, DMSO, acetone and MeOH. The protease retained 81.7, 83.6 and 76.2% of its initial activity in the presence of nonionic surfactants 20% (v/v) Tween 80, 25% (v/v) glycerol and Triton X-100, respectively. The protease is strongly inhibited by PMSF, suggesting that it is a serine protease. Washing experiments revealed that the protease has an excellent ability to remove blood stains.

Structural and Functional Analysis of Giant Strong Component of Bacillus thuringiensis Metabolic Network

The purpose of this work was to study the giant strong component (GSC) of B. thuringiensis metabolic network by structural and functional analysis. Based on so-called “bow tie” structure, we extracted and studied GSC with its functional significance. Global structural properties such as degree distribution and average path length were computed and indicated that the GSC is also a small-world and scale-free network. Furthermore, the GSC was decomposed and functional significant for metabolism of these divisions were investigated by comparing to KEGG metabolic pathways.

Salvicine triggers DNA double-strand breaks and apoptosis by GSH-depletion-driven H2O2 generation and topoisomerase II inhibition

Glutathione (GSH), as the major small-molecule antioxidant in cells, has been implicated in the regulation of cell proliferation and apoptosis. Salvicine (SAL), a novel diterpenoid quinone compound, exhibits potent antitumor activities both in vitro and in vivo by poisoning topoisomerase II (Topo II) and has entered Phase II clinical trials for cancer therapy. Herein, we provide further evidence that SAL-induced DNA double-strand breaks (DSBs) and apoptosis by GSH depletion drives H2O2 generation and Topo II inhibition. Our data reveal that treatment with SAL results in a pronounced increase in intracellular H2O2 and is accompanied by the occurrence of DNA DSBs and apoptosis in epithelial HeLa cells. Furthermore, SAL was also noted to trigger a dramatic depletion of intracellular GSH via its direct reaction with GSH. Importantly, the introduction of GSH and overexpression of catalase antagonized SAL-mediated DNA DSBs and apoptosis, and the GSH synthesis inhibitor dl-buthionine-[S,R]-sulfoximine reduced SAL-mediated H2O2 generation, indicating that SAL-mediated H2O2 generation is derived from intracellular GSH depletion. Notably, SAL-mediated Topo II inhibition was also concentration-dependently reversed by GSH. Furthermore, we found that Topo II-defective HL-60/MX2 cells were almost completely resistant to SAL-induced DNA DSBs, suggesting that, in addition to its direct inhibitory effect on Topo II, SAL-mediated H2O2 generation may also trigger DNA DSBs via poisoning of Topo II. All these findings together suggest that GSH-depletion-driven H2O2 generation and Topo II inhibition are both critical for SAL-induced DNA DSBs and apoptosis.

Chk1 and Chk2 are differentially involved in homologous recombination repair and cell cycle arrest in response to DNA double-strand breaks induced by camptothecins

Camptothecins (CPT) activate S or G(2)-M arrest and the homologous recombination (HR) repair pathway in tumor cells. In this process, both checkpoint kinases 1 and 2 (Chk1 and Chk2, respectively) are activated, but their differential roles, especially in the coordination of checkpoint and repair control, and potential clinic relevance remain to be fully elucidated. In this study, the repairable double-strand breaks were induced in human colon cancer HCT116 cells by 1-h exposure to 25 or 100 nmol/L CPT and its novel derivative chimmitecan. The cellular disposal of double-strand breaks was reflected as the progressive dispersal of gamma-H2AX foci, reduction of "comet" tails, dynamic activation of RAD51-mediated HR repair, and reversible G(2)-M arrest. In this model, the differential kinetics of Chk1 and Chk2 activation was characterized by the progressively increased phosphorylation of Chk2 until 72 h, the degradation of Chk1, and the disappearance of phosphorylated Chk1 48 h after drug removal. Using RNA interference, we further showed that Chk2 was essential to G(2)-M arrest, whereas Chk1 was mainly required for HR repair in CPT-treated HCT116 cells. Moreover, Chk2, rather than Chk1, predominated over the control of cell survival in this model. The differential roles of Chk1 and Chk2 in regulating HR repair and G(2)-M phase arrest were also confirmed in HT-29 colon cancer cells. Together, these findings systematically dissect the differential roles of Chk1 and Chk2 in a favorable model pursuing CPT-driven DNA damage responses, providing critical evidence to further explore checkpoint modulation, especially Chk2 inhibition as a therapeutic strategy in combination with CPT.

R16, a novel amonafide analogue, induces apoptosis and G2-M arrest via poisoning topoisomerase II

Amonafide, a naphthalimide derivative, although selected for exploratory clinical trials for its potent anticancer activity, has long been challenged by its unpredictable side effects. In the present study, a novel amonafide analogue, 2-(2-dimethylamino)-6-thia-2-aza-benzo-[def]-chrysene-1,3-diones (R16) was synthesized by substituting 5'-NH(2) of the naphthyl with a heterocyclic group to amonafide, with additional introduction of a thiol group. In a panel of various human tumor cell lines, R16 was more cytotoxic than its parent compound amonafide. It was also effective against multidrug-resistant cells. Importantly, the i.p. administration of R16 inhibited tumor growth in mice implanted with S-180 sarcoma and H(22) hepatoma. The molecular and cellular machinery studies showed that the R16 functions as a topoisomerase II (topo II) poison via binding to the ATPase domain of human topo IIalpha. The superior cytotoxicity of R16 to amonafide was ascribed to its potent effects on trapping topo II-DNA cleavage complexes. Moreover, using a topo II catalytic inhibitor aclarubicin, ataxia-telangiectasia-mutated (ATM)/ATM- and Rad3-related (ATR) kinase inhibitor caffeine and topo II-deficient HL-60/MX2 cells, we further showed that R16-triggered DNA double-strand breaks, tumor cell cycle arrest, and apoptosis were in a topo II-dependent manner. Taken together, R16 stood out by its improved anticancer activity, appreciable anti-multidrug resistance activities, and well-defined topo II poisoning mechanisms, as comparable with the parent compound amonafide. All these collectively promise the potential value of R16 as an anticancer drug candidate, which deserves further development.

DNA damage induced by resveratrol and its synthetic analogues in the presence of Cu (II) ions: mechanism and structure-activity relationship

The prooxidant effect of resveratrol (3,5,4'-trihydroxy-trans-stibene) and its synthetic analogues (ArOH), that is, 3,4,4'-trihydroxy-trans-stibene (3,4,4'-THS), 3,4,5-trihydroxy-trans-stibene (3,4,5-THS), 3,4-dihydroxy-trans-stibene (3,4-DHS), 4,4'-dihydroxy-trans-stibene (4,4'-DHS), 2,4-dihydroxy-trans-stilbene (2,4-DHS), 3,5-dihydroxy-trans-stilbene (3,5-DHS) and 3,5,4'-trimethoxy-trans-stibene (3,5,4'-TMS), on supercoiled pBR322 plasmid DNA strand breakage and calf thymus DNA damage in the presence of Cu (II) ions has been studied. It was found that the compounds bearing ortho-dihydroxyl groups (3,4-DHS, 3,4,4'-THS, and 3,4,5-THS) or bearing 4-hydroxyl groups (2,4-DHS, 4,4'-DHS, and resveratrol) exhibit remarkably higher activity in the DNA damage than the ones bearing no such functionalities. Kinetic analysis by UV-visible spectra demonstrates that the formation of ArOH-Cu (II) complexes, the stabilization of oxidative intermediate derived from ArOH and Cu (II)/Cu (I) redox cycles, might be responsible for the DNA damage. This study also reveals a good correlation between antioxidant and prooxidant activity, as well as cytotoxicity against human leukemia (HL-60 and Jurkat) cell lines. The mechanisms and implications of these observations are discussed.

Cytotoxic and apoptotic activities of diarylheptanoids and gingerol-related compounds from the rhizome of Chinese ginger

Ginger is one of the most widely used spices and has been used in traditional oriental medicines for long time. Its extract and major pungent principles have been shown to exhibit a variety of biological activities. In order to find more active constituents and evaluate their structure-activity relationship (SAR) we isolated from the rhizomes of Chinese ginger (Zingiber officinale Roscoe) five new diarylheptanoids along with 20 known diarylheptanoids and gingerol-related compounds and studied their cytotoxic and apoptotic activities against human promyelocytic leukemia (HL-60) cells. It was found that compounds 1a, 2a, 5, 6a, 6b and 7 possess significant cytotoxicity against HL-60 cells (IC(50)<50 microM) and that the cytotoxic activity is associated with the cell apoptosis. SAR analysis demonstrates that the following structural determinants contribute critically to the enhancement of the activity: (i) acetoxyl groups at 3- and/or 5-positions of the side chain; (ii) the appropriate longer alkyl side-chain length; (iii) the ortho-diphenoxyl functionality on the aromatic ring; (iv) the alpha,beta-unsaturated ketone moiety in the side chain. These provide useful information for potential chemopreventive drug design.

Reactive Oxygen Species Elicit Apoptosis by Concurrently Disrupting Topoisomerase II and DNA-Dependent Protein Kinase

Reactive oxygen species (ROS) are produced by all aerobic cells and have been implicated in the regulation of diverse cellular functions, including intracellular signaling, transcription activation, proliferation, and apoptosis. Salvicine, a novel diterpenoid quinone compound, demonstrates a broad spectrum of antitumor activities. Although salvicine is known to trap the DNA-topoisomerase II (Topo II) complex and induce DNA double-strand breaks (DSBs), its precise antitumor mechanisms remain to be clarified. In this study, we investigated whether salvicine altered the levels of ROS in breast cancer MCF-7 cells and whether these ROS contributed to the observed antitumoral activity. Our data revealed that salvicine stimulated intracellular ROS production and subsequently elicited notable DSBs. The addition of N-acetyl cysteine (NAC), an antioxidant, effectively attenuated the salvicine-induced ROS enhancement and subsequent DNA DSBs. Heat treatment reversed the accumulation of DNA DSBs, and the addition of NAC attenuated the Topo II-DNA cleavable complexes formation and the growth inhibition of salvicine-treated JN394top2-4 yeast cells, collectively indicating that Topo II is a target of the salvicine-induced ROS. On the other hand, when examining the impact of salvicine on DNA repair pathways, we unexpectedly observed that salvicine selectively down-regulated the catalytic subunit of DNA-dependent protein kinase (DNA-PK(CS)) protein levels and repressed DNA-PK kinase activity; both of these effects were attenuated by NAC pretreatment of MCF-7 cells. Finally and most importantly, NAC attenuated salvicine-induced apoptosis and cytotoxicity in MCF-7 cells. These results indicate that apart from its direct actions, salvicine generates ROS that modulate DNA damage and repair, contributing to the comprehensive biological consequences of salvicine treatment, such as DNA DSBs, apoptosis, and cytotoxicity in tumor cells. The finding of salvicine-induced ROS provides new evidence for the molecular mechanisms of this compound. Moreover, the effects of salvicine-induced ROS on Topo II and DNA-PK give new insights into the diverse biological activities of ROS.

Diterpenoids from the Chinese herb Caryopteris terniflora and their antibacterial and antitumor activity

Two ent-kaurene type diterpenoids, diterpenoids A (1) and B (2) were isolated from the Chinese herb Caryopteris terniflora and defined as ent-7beta, 11alpha,14-trihydroxy-18-aldehyde-11beta-20-epoxy-kaur-16-en15-one and ent-7beta,14-dihydroxy-11alpha-methoxy-18-aldehyde-11beta-20-epoxy-kaur-16-en-15-one respectively. Compounds 1 and 2 showed significant antibacterial and antitumour activity.

The 3,4-dihydroxyl groups are important for trans-resveratrol analogs to exhibit enhanced antioxidant and apoptotic activities

We compared the abilities of trans-resveratrol and seven analogs to inhibit an azo compound-induced peroxidation of linoleic acid in vitro and to induce apoptosis in cultured human leukemia cells. The results showed that both the antioxidant and apoptotic activities of the analogs containing 3,4-dihydroxyl groups were significantly higher than those of the trans-resveratrol and the other analogs. Hence, the 3,4-dihydroxyl groups were important for trans-resveratrol analogs to exhibit concurrent high antioxidant and apoptotic activities.

Structure determination, apoptosis induction, and telomerase inhibition of CFP-2, a novel lichenin from Cladonia furcata

A great deal of experimental evidence has accumulated in the past several decades, suggesting that polysaccharides have wide bioactivities. Cladonia furcata polysaccharide, CFP-2, a water-soluble lichenin with a mean Mr 7.6 x 10(4), was first obtained by 0.25 M NaOH solution extraction, ethanol precipitation, DEAE-cellulose, and Sephadex G-200 column chromatography. Gas chromatography of acid hydrolyzate of CFP-2 suggested that it was composed of D-glucose, D-galactose, and D-mannose in the molar ratios of 8:1:1. Periodate oxidation, Smith degradation, IR, and NMR spectroscopy analysis revealed that CFP-2 had a backbone consisting of alpha-(1-->3) and alpha-(1-->4)-linked D-glucopyranosyl residues substituted at O-6 with beta-(1-->6)-linked D-galactopyranosyl residue and alpha-(1-->6)-linked D-mannopyranosyl residue. CFP-2 was able to reduce viability of cultured HL-60 and K562 cells. The antiproliferative properties of CFP-2 appeared to be attributable to its induction of apoptotic cell death as determined by ultrastructural change, internucleosomal DNA fragmentation, and increased proportion of the subdiploid cell population. To elucidate molecular events in the apoptosis, protein expressions of Bcl-2, Bax, Fas, and FasL were measured by Western blotting using specific antibodies in HL-60 cells. The level of Bcl-2 remained largely unchanged, but the Bax, Fas, and FasL expression showed up-regulation. Moreover, the telomerase activity analyzed by TRAP-ELISA assay in HL-60 cells treated with CFP-2 decreased as compared with the untreated control cells. These results suggest that CFP-2 could have a possible cancer therapeutic potential.

Antioxidative and free radical scavenging effects of ecdysteroids from Serratula strangulata

The antioxidative and free radical scavenging effects of four ecdysteroids, 20-hydroxyecdysone (E1), 25-deoxy-11,20-dihydroxyecdysone (E2), 24-(2-hydroxyethyl)-20-hydroxyecdysone (E3), and 20-hydroxyecdysone-20,22-monoacetonide (E4), isolated from the Chinese herb Serratula strangulata have been investigated in vitro. These ecdysteroids could protect human erythrocytes against oxidative hemolysis induced by a water-soluble azo initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). They could also inhibit the peroxidation of rat liver microsomes induced by hydroxyl radicals, as monitored by the formation of thiobarbituric acid reactive substances (TBARS), and prevent radical-induced decrease of membrane fluidity as determined by fluorescence polarization. They reacted with galvinoxyl radicals in homogeneous solution, and the pseudo-first-order rate constants were determined spectrophotometrically by following the disappearance of galvinoxyl radicals. Compounds E1 and (or) E3 were the most active in both antioxidative and radical-scavenging reactions.

Efficiency and structure-activity relationship of the antioxidant action of resveratrol and its analogs

Resveratrol and its analogs, six other polyhydroxystilbenes, were synthesized and their antioxidative activities were evaluated in vitro by determination of the levels of malondialdehyde and hydrogen peroxide. Results clearly exhibited that resveratrol and its analogs had various potencies in inhibiting lipid peroxidation in rat brain, kidney, and liver homogenates and rat erythrocyte hemolysis. Several polyhydroxystilbenes were found to be more active than resveratrol in these models, and structure-activity relationship studies on polyhydroxystilbenes are described in this paper.

Cladonia furcata polysaccharide induced apoptosis in human leukemia K562 cells

AIM

To study whether Cladonia furcata polysaccharide (CFP-1) might induce apoptosis in human leukemia K562 cells.

METHODS

Inhibition of proliferation was measured by MTT assay. Morphological assessment of apoptosis was performed with fluorescence microscope and electron microscope. DNA fragmentation was visualized by agarose gel electrophoresis. The amount of apoptosis cells was measured by flow cytometry.

RESULTS

CFP-1 (50 - 800 mg/L) inhibited K562 cell proliferation in a concentration-dependent manner. After incubation of K562 cells with CFP-1 300 mg/L for 5 d, morphological changes of typical apoptosis were observed and agarose gel electrophoresis of DNA revealed "ladder" pattern.

CONCLUSION

CFP-1 induced apoptosis in human leukemia K562 cells.

Production and distribution of endoglucanase, cellobiohydrolase, and beta-glucosidase components of the cellulolytic system of Volvariella volvacea, the edible straw mushroom

The edible straw mushroom, Volvariella volvacea, produces a multicomponent enzyme system consisting of endo-1,4-beta-glucanase, cellobiohydrolase, and beta-glucosidase for the conversion of cellulose to glucose. The highest levels of endoglucanase and cellobiohydrolase were recorded in cultures containing microcrystalline cellulose (Avicel) or filter paper, while lower but detectable levels of activity were also produced on carboxymethyl cellulose, cotton wool, xylitol, or salicin. Biochemical analyses of different culture fractions in cultures exhibiting peak enzyme production revealed that most of the endoglucase was present either in the culture filtrate (45.8% of the total) or associated with the insoluble pellet fraction remaining after centrifugation of homogenized mycelia (32.6%). Cellobiohydrolase exhibited a similar distribution pattern, with 58.9% of the total enzyme present in culture filtrates and 31.0% associated with the pellet fraction. Conversely, most beta-glucosidase activity (63.9% of the total) was present in extracts of fungal mycelia whereas only 9.4% was detected in culture filtrates. The endoglucanase and beta-glucosidase distribution patterns were confirmed by confocal laser scanning microscopy combined with immunolabelling. Endoglucanase was shown to be largely cell wall associated or located extracellularly, with the highest concentrations being present in a region 1 to 2 microm wide immediately adjacent to the outer surface of (and possibly including) the hyphal wall and extending 60 to 70 microm from the hyphal tip. Immunofluorescence patterns indicated little if any intracellular endoglucanase. Most beta-glucosidase was located intracellularly in the apical area extending 60 to 70 microm below the hyphal tip, although enzyme was also evident in the extracellular region extending approximately 15 microm all around the hyphal tip and trailing back along the length of the hypha. The regions of the hypha located some distance from the apical region appeared to be devoid of intracellular beta-glucosidase, and the enzyme appears to be associated almost exclusively with, or located on the outside surface of, the hyphal wall.