Staggered intercalation of DNA duplexes with base-pair modulation by two distinct drug molecules induces asymmetric backbone twisting and structure polymorphism.

The use of multiple drugs simultaneously targeting DNA is a promising strategy in cancer therapy for potentially overcoming single drug resistance. In support of this concept, we report that a combination of actinomycin D (ActD) and echinomycin (Echi), can interact in novel ways with native and mismatched DNA sequences, distinct from the structural effects produced by either drug alone. Changes in the former with GpC and CpG steps separated by a A:G or G:A mismatch or in a native DNA with canonical G:C and C:G base pairs, result in significant asymmetric backbone twists through staggered intercalation and base pair modulations. A wobble or Watson-Crick base pair at the two drug-binding interfaces can result in a single-stranded 'chair-shaped' DNA duplex with a straight helical axis. However, a novel sugar-edged hydrogen bonding geometry in the G:A mismatch leads to a 'curved-shaped' duplex. Two non-canonical G:C Hoogsteen base pairings produce a sharply kinked duplex in different forms and a four-way junction-like superstructure, respectively. Therefore, single base pair modulations on the two drug-binding interfaces could significantly affect global DNA structure. These structures thus provide a rationale for atypical DNA recognition via multiple DNA intercalators and a structural basis for the drugs' potential synergetic use.

The mediation of health-promoting lifestyle on self-perceived health status and quality of life among nurses: a cross-sectional study.

BACKGROUND: Nurses with busy workloads lack the time to maintain health, leading to a decline in physical and mental health and quality of life. It is widely accepted that self-perception of health triggers health-promoting behaviors and impacts the quality of life; however, the relationship between these factors among nurses is unclear. The purpose of this study was to investigate the ability of a health-promoting lifestyle to mediate the relationship between self-perceived health and quality of life among nurses. METHODS: A cross-sectional survey was conducted in four regional Taiwanese teaching hospitals with over 500 beds. The survey used stratified random sampling of 600 nurses who had worked for more than six months. The Self-Perceived Health Questionnaire, the Health-Promoting Lifestyle Profile, and the World Health Organization Quality of Life Scale were used to measure nurses' self-perceived health (SPH), health-promoting lifestyle (HPL), and quality of life (QoL). A Hayes PROCESS analysis and bootstrapping method were used for the mediation analysis. RESULTS: A total of 518 nurses' data was included in the analysis. Nurses perceived their health status as less favorable than their colleagues, but frequently adopted health promotion behaviors. Nurses reported a moderate QoL. QoL and SPH were correlated (r = .33) and a high correlation between QoL and HPL (r = .64) was found. SPH and HPL both affect QoL (B = 0.077 and 0.070). SPH and HPL explained 42.6% of the variation in QoL. HPL played a partial mediation role. CONCLUSIONS: The study confirmed that HPL has an important role in mediating nurses' SPH and QoL. Nurse administrators are advised to encourage nurses to monitor their health status and provide health promotion mechanisms to improve their quality of life.

Structural Basis for Targeting T:T Mismatch with Triaminotriazine-Acridine Conjugate Induces a U-Shaped Head-to-Head Four-Way Junction in CTG Repeat DNA.

The potent DNA-binding compound triaminotriazine-acridine conjugate (Z1) functions by targeting T:T mismatches in CTG trinucleotide repeats that are responsible for causing neurological diseases such as myotonic dystrophy type 1, but its binding mechanism remains unclear. We solved a crystal structure of Z1 in a complex with DNA containing three consecutive CTG repeats with three T:T mismatches. Crystallographic studies revealed that direct intercalation of two Z1 molecules at both ends of the CTG repeat induces thymine base flipping and DNA backbone deformation to form a four-way junction. The core of the complex unexpectedly adopts a U-shaped head-to-head topology to form a crossover of each chain at the junction site. The crossover junction is held together by two stacked G:C pairs at the central core that rotate with respect to each other in an X-shape to form two nonplanar minor-groove-aligned G·C·G·C tetrads. Two stacked G:C pairs on both sides of the center core are involved in the formation of pseudo-continuous duplex DNA. Four metal-mediated base pairs are observed between the N7 atoms of G and CoII, an interaction that strongly preserves the central junction site. Beyond revealing a new type of ligand-induced, four-way junction, these observations enhance our understanding of the specific supramolecular chemistry of Z1 that is essential for the formation of a noncanonical DNA superstructure. The structural features described here serve as a foundation for the design of new sequence-specific ligands targeting mismatches in the repeat-associated structures.

Ethyl Acetate Extract of Scindapsus cf. hederaceus Exerts the Inhibitory Bioactivity on Human Non-Small Cell Lung Cancer Cells through Modulating ER Stress.

Unfolded protein response (UPR) is a cytoprotective mechanism that alleviates the protein-folding burden in eukaryotic organisms. Moderate activation of UPR is required for maintaining endoplasmic reticulum (ER) homeostasis and profoundly contributes to tumorigenesis. Defects in UPR signaling are implicated in the attenuation of various malignant phenotypes including cell proliferation, migration, and invasion, as well as angiogenesis. This suggests UPR as a promising target in cancer therapy. The pharmacological effects of the plant Scindapsus cf. hederaceus on human cancer cell lines is not understood. In this study, we identified an ethyl acetate extract from Scindapsus cf. hederaceus (SH-EAE), which markedly altered the protein expression of UPR-related genes in human non-small cell lung cancer (NSCLC) cells. Treatment with the SH-EAE led to the dose-dependent suppression of colony forming ability of both H1299 and H460 cells, but not markedly in normal bronchial epithelial BEAS-2B cells. SH-EAE treatment also attenuated the migration and invasion ability of H1299 and H460 cells. Moreover, SH-EAE strikingly suppressed the protein expression of two ER stress sensors, including inositol requiring enzyme-1α (IRE-1α) and protein kinase R-like ER kinase (PERK), and antagonized the induction of C/EBP homologous protein (CHOP) expression by thapsigargin, an ER stress inducer. SH-EAE induced the formation of massive vacuoles which are probably derived from ER. Importantly, SH-EAE impaired the formation of intersegmental vessels (ISV) in zebrafish larvae, an index of angiogenesis, but had no apparent effect on the rate of larval development. Together, our findings demonstrate, for the first time, that the ability of SH-EAE specifically targets the two sensors of UPR, with significant anti-proliferation and anti-migration activities as a crude extract in human NSCLC cells. Our finding also indicates potential applications of SH-EAE in preventing UPR activation in response to Tg-induced ER stress. We suggest that SH-EAE attenuates UPR adaptive pathways for rendering the NSCLC cells intolerant to ER stress.

Targeting the receptor binding domain and heparan sulfate binding for antiviral drug development against SARS-CoV-2 variants.

The emergence of SARS-CoV-2 variants diminished the efficacy of current antiviral drugs and vaccines. Hence, identifying highly conserved sequences and potentially druggable pockets for drug development was a promising strategy against SARS-CoV-2 variants. In viral infection, the receptor-binding domain (RBD) proteins are essential in binding to the host receptor. Others, Heparan sulfate (HS), widely distributed on the surface of host cells, is thought to play a central role in the viral infection cycle of SARS-CoV-2. Therefore, it might be a reasonable strategy for antiviral drug design to interfere with the RBD in the HS binding site. In this study, we used computational approaches to analyze multiple sequences of coronaviruses and reveal important information about the binding of HS to RBD in the SARS-CoV-2 spike protein. Our results showed that the potential hot-spots, including R454 and E471, in RBD, exhibited strong interactions in the HS-RBD binding region. Therefore, we screened different compounds in the natural product database towards these hot-spots to find potential antiviral candidates using LibDock, Autodock vina and furthermore applying the MD simulation in AMBER20. The results showed three potential natural compounds, including Acetoside (ACE), Hyperoside (HYP), and Isoquercitrin (ISO), had a strong affinity to the RBD. Our results demonstrate a feasible approach to identify potential antiviral agents by evaluating the binding interaction between viral glycoproteins and host receptors. The present study provided the applications of the structure-based computational approach for designing and developing of new antiviral drugs against SARS-CoV-2 variants.

Burning down the house: Pyroptosis in the tumor microenvironment of hepatocellular carcinoma.

A high mortality rate makes hepatocellular carcinoma (HCC) a difficult cancer to treat. When surgery is not possible, liver cancer patients are treated with chemotherapy. However, HCC management and treatment are difficult. Sorafenib, which is a first-line treatment for hepatocellular carcinoma, initially slows disease progression. However, sorafenib resistance limits patient survival. Recent studies have linked HCC to programmed cell death, which has increased researcher interest in therapies targeting cell death. Pyroptosis, which is an inflammatory mode of programmed cell death, may be targeted to treat HCC. Pyroptosis pathways, executors, and effects are examined in this paper. This review summarizes how pyroptosis affects the tumor microenvironment (TME) in HCC, including the role of cytokines such as IL-1ß and IL-18 in regulating immune responses. The use of chemotherapies and their ability to induce cancer cell pyroptosis as alternative treatments and combining them with other drugs to reduce side effects is also discussed. In conclusion, we highlight the potential of inducing pyroptosis to treat HCC and suggest ways to improve patient outcomes. Studies on cancer cell pyroptosis may lead to new HCC treatments.

Effective topical treatments using innovative NNO-tridentate vanadium(IV) complexes-mediated photodynamic therapy in a psoriasis-like mouse model.

Psoriasis is a chronic inflammatory skin disease that can significantly impact the quality of human life. Various drug treatments are available; however, due to their long-term severe side effects the usage of these drugs is limited. Photodynamic therapy (PDT) has been clinically approved for skin diseases due to its non-invasive nature. We present novel NNO-tridentate vanadium(IV) complexes used in PDT for anti-inflammatory effects in an imiquimod-induced psoriasis-like skin disease mouse model. The vanadium(IV) complexes (1-4) were synthesized using the NNO-tridentate ligand with a benzo[i]dipyrido[3,2-a;2',3'-c]phenazine (dppn) moiety, and were characterized by UV/Visible spectroscopy, EPR spectroscopy, NMR (1H, and 13C) spectroscopy, electrospray ionization mass (ESI-MS) spectrometry and cyclic voltammetry (CV) studies. The photocytotoxicity of vanadium(IV) complexes (1-4) was low under dark conditions and complex (4) showed remarkable photocytotoxicity under blue light (430 nm, 8 W cm-2, 30 min) irradiation. Moreover, [VO(t-butylL)(dppn)] (4)-mediated PDT down-regulated inflammatory cytokines IL-17A and IL-22 in the psoriasis-like mouse model, which could evidence the significant relieving of the psoriatic-like symptoms in the mouse model. Overall, these results suggested that [VO(t-butylL)(dppn)] (4) could be a potential candidate for the treatment of psoriasis both in vitro and in vivo.

Concomitant inactivation of the epidermal growth factor receptor, phosphatidylinositol 3-kinase/Akt and Janus tyrosine kinase 2/signal transducer and activator of transcription 3 signalling pathways in cardiotoxin III-treated A549 cells.

1. Cardiotoxin (CTX) III, a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has potential anticancer therapeutic activity. The aim of the present study was to investigate the apoptotic effect (and the underlying mechanism of action) of CTX III in human adenocarcinoma A549 cells. 2. It was found that CTX III induces apoptosis in A549 cells, as indicated by an increase in the sub-G(1) population, phosphatidylserine externalization, loss of mitochondrial membrane potential (Psi(m)) with cytochrome c release and activation of caspases 9 and 3. These actions were correlated with upregulation of Bax and Bad and downregulation of various anti-apoptotic proteins, including Bcl-2, Bcl-X(L), Mcl-1, X-linked inhibitor of apoptosis protein (XIAP) and p-Bad in CTX III-treated cells. 3. The signal transduction pathways involved in the effects of CTX III in A549 cells were evaluated using 5 micromol/L AG1478, an inhibitor of the epidermal growth factor receptor (EGFR), and exposing cells to the drug for 8 h. The results indicated that CTX III suppresses phosphorylation of EGFR and activation of phosphatidylinositol 3-kinase (PI3-K)/Akt and Janus tyrosine kinase (JAK) 2/signal transducer and activator of transcription (STAT) 3, all of which are downstream molecules in the EGFR signalling pathway. 4. Exposure of cells for 8 h to the PI3-K inhibitor wortmannin (10 micromol/L) blocked JAK2 and STAT3 activation, whereas exposure of cells to the JAK2 inhibitor AG490 (5 micromol/L) decreased levels of phosphorylated (p-) JAK2 and p-STAT3 without affecting PI3-K/Akt activation. These observations suggest that PI3-K is an upstream activator of JAK2/STAT3. Furthermore, 5 micromol/L AG490 and 10 micromol/L wortmannin treatment of A549 cells for 8 h resulted in upregulation of Bax and Bad and downregulation of Bcl-2, Bcl-X(L), XIAP and p-Bad. 5. Together, the results of the present study indicate that CTX III induces apoptosis in A549 cells by inactivating the EGFR, PI3-K/Akt and JAK2/STAT3 signalling pathways.

Structure-Based Stabilization of Non-native Protein-Protein Interactions of Coronavirus Nucleocapsid Proteins in Antiviral Drug Design.

Structure-based stabilization of protein-protein interactions (PPIs) is a promising strategy for drug discovery. However, this approach has mainly focused on the stabilization of native PPIs, and non-native PPIs have received little consideration. Here, we identified a non-native interaction interface on the three-dimensional dimeric structure of the N-terminal domain of the MERS-CoV nucleocapsid protein (MERS-CoV N-NTD). The interface formed a conserved hydrophobic cavity suitable for targeted drug screening. By considering the hydrophobic complementarity during the virtual screening step, we identified 5-benzyloxygramine as a new N protein PPI orthosteric stabilizer that exhibits both antiviral and N-NTD protein-stabilizing activities. X-ray crystallography and small-angle X-ray scattering showed that 5-benzyloxygramine stabilizes the N-NTD dimers through simultaneous hydrophobic interactions with both partners, resulting in abnormal N protein oligomerization that was further confirmed in the cell. This unique approach based on the identification and stabilization of non-native PPIs of N protein could be applied toward drug discovery against CoV diseases.

Effects of cardiotoxin III on NF-kappaB function, proliferation, and apoptosis in human breast MCF-7 cancer cells.

Cardiotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity. CTX III-induced apoptosis in human breast MCF-7 cancer cells was confirmed by sub-G1 formation, phosphatidylserine (PS) externalization, and poly (ADP-ribose) polymerase (PARP) cleavage with an IC50 of 2 microg/ml at 48 h. Effects of CTX III on proliferation and apoptosis correlated with upregulation of Bax, and downregulation of Bcl-XL, Bcl-2, and XIAP, with no appreciable alteration on the protein levels of Bid, Bim, and survivin. CTX III treatment also caused release of mitochondrial cytochrome c to the cytosol, which led to subsequent activation of capase-9. Moreover, CTX III inhibited the nuclear factor-kappaB (NF-kappaB) activation through inhibition of IkappaB kinase (IkappaK) activity. Overall, our results indicate that CTX III downregulates NF-kappaB in MCF-7 cells, leading to the suppression of proliferation and induction of apoptosis. These findings suggest the molecular basis for CTX III-induced apoptotic death of MCF-7 cells.

1-(2-((Z)-6-(2-(Trifluoromethyl)phenyl)hexa-3-en-1,5-diynyl)phenyl)piperidin-2-one as a new potent apoptosis agent.

Compounds 4a-f, 5a-f and 6-9, showed significant growth inhibition activity against human tumor cell lines. Of these compounds, 1-(2-((Z)-6-(2-(trifluoromethyl)phenyl)hexa-3-en-1,5-diynyl)phenyl)piperidin-2-one (8) displayed the most potent growth inhibition activity. Compound 8 also arrested cancer cells in G2/M phase and induced apoptosis via activation of caspase-3 and -9. According to western-blotting analysis, compound 8 can up-regulate Bax, down-regulate Bcl-2 and XIAP, as well as promote cytochrome c release.

Inactivation of epidermal growth factor receptor and downstream pathways in oral squamous cell carcinoma Ca9-22 cells by cardiotoxin III from Naja naja atra.

Cardiotoxin III (1), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has potential therapeutic activity in cancer. Treatment with 1 reduced phosphorylation of EGFR and Akt, as well as ERK in Ca9-22 cells. Moreover, 1-treatment inhibited constitutive activation of STAT3 and STAT5 in a time-dependent manner. Up-regulation of Bax and down-regulation of anti-apoptotic proteins including Bcl-2, Bcl-X(L), and myeloid cell leukemia-1(Mcl-1) were also found in cells treated with 1. In addition, 1-treatment disrupted mitochondrial membrane potential (DeltaPsim) and resulted in release of mitochondrial cytochrome c and activation of both caspases-9 and -3. AG1478, a specific pharmacological inhibitor of EGFR activation, mimics the cytotoxic effects of 1. Taken together, these results showed that 1 causes significant induction of apoptosis in Ca9-22 cells via abolition of the EGFR-mediated survival pathway of these cells. Thus, cardiotoxin III appears to be a potential therapeutic agent for killing oral squamous carcinoma Ca9-22 cells.

Hyaluronic Acid-Povidone-Iodine Compound Facilitates Diabetic Wound Healing in a Streptozotocin-Induced Diabetes Rodent Model.

BACKGROUND: This study investigated whether a hyaluronic acid-povidone-iodine compound can enhance diabetic wound healing. METHODS: A dorsal skin defect (6 × 5 cm) in a streptozotocin-induced diabetes rodent model was used. Seventy male Wistar rats were divided into seven groups: I, normal control; II, diabetic control, no treatment; III, diabetic rats, lower molecular weight (100 kDa) hyaluronic acid; IV, rats, higher molecular weight (1000 kDa) hyaluronic acid; V, rats, 0.1% povidone-iodine; VI, rats, lower molecular weight hyaluronic acid plus povidone-iodine; and VII, rats, higher molecular weight hyaluronic acid plus povidone-iodine. Histologic examination was performed with hematoxylin and eosin staining. CD45, Ki-67, prolyl 4-hydroxylase, and vascular endothelial growth factor were evaluated with immunohistochemical staining. RESULTS: Compared with the control, higher molecular weight hyaluronic acid plus povidone-iodine-treated rats had significantly reduced wound area (p < 0.001). Higher molecular weight hyaluronic acid plus povidone-iodine increased wound healing time when compared with higher molecular weight hyaluronic acid, povidone-iodine, or lower molecular weight hyaluronic acid plus povidone-iodine. Histology revealed significantly increased neovessels and suppressed inflammatory response in the higher molecular weight hyaluronic acid plus povidone-iodine group when compared with the control group. Immunohistochemical staining revealed significantly increased Ki67, prolyl 4-hydroxylase, and vascular endothelial growth factor expression, and suppressed CD45 expression in the higher molecular weight hyaluronic acid plus povidone-iodine group when compared with the other groups. CONCLUSION: Higher molecular weight hyaluronic acid plus povidone-iodine complex dressing significantly facilitated diabetic wound healing via increasing neovascularization and tissue regeneration and suppressing a proinflammatory response.

Half-sandwich Ru(η6-p-cymene) complexes featuring pyrazole appended ligands: Synthesis, DNA binding and in vitro cytotoxicity.

Organometallic Ru(II)-arene complexes have emerged as potential alternatives to platinum appended agents due to their wide range of interesting features such as stability in solution and solid, significant activity, less toxicity and hydrophobic property of arene moiety, etc. Hence, a series of Ru(II)-p-cymene complexes, [(η6-p-cymene)Ru(η2-N,N-L1)Cl]Cl (1), [(η6-p-cymene)Ru(η1-N-L2)Cl2] (2) and [(η6-p-cymene)Ru(η1-N-L3)Cl2] (3) were prepared from pyrazole based ligands [2-(1H-pyrazol-3-yl)pyridine (L1), 3-(furan-2-yl)-1H-pyrazole (L2) and 3-(thiophen-2-yl)-1H-pyrazole (L3)], and [RuCl2-(η6-p-cymene)] dimer. The new Ru(II)-p-cymene complexes were well characterized by elemental analysis, and spectroscopic (FT-IR, UV-Visible, 1H NMR, 13C NMR and mass) and crystallographic methods. The Ru(II)-p-cymene complexes (1-3) were found to adopt their characteristic piano stool geometry around Ru(II) ion. The calf thymus DNA (CT-DNA) binding ability of the new complexes was investigated by electronic absorption spectroscopic titration and viscosity methods. The molecular docking study results showed that complex 1 strongly bound with targeted biomolecules than 2 and 3. Docked poses of bidentate pyrazole based Ru(II)-p-cymene complex 1 revealed that the complex formed a crucial guanine N7 position hydrogen bond with DNA receptor. Complexes 1-3 might hydrolyze under physiological conditions and form aqua complexes 4-8, and docking calculations showed that the aqua complexes bound strongly with the receptors than original complexes. The in vitro cytotoxicity of the Ru(II)-p-cymene complexes and cisplatin was evaluated against triple negative breast cancer (TNBC) MDA-MB-231 cells. Our results showed that the inhibitory effect of bidentate pyrazole based Ru(II)-p-cymene complex 1 on the growth of breast cancer cells was superior to other tested complexes.

Phytochemical naphtho[1,2-b] furan-4,5­dione induced topoisomerase II-mediated DNA damage response in human non-small-cell lung cancer.

BACKGROUND: Phytochemical naphtho[1,2-b] furan-4,5­dione (NFD) presenting in Avicennia marina exert anti-cancer effects, but little is known regarding about DNA damage-mediated apoptosis in non-small-cell lung carcinoma (NSCLC). PURPOSE: To examine whether NFD-induced apoptosis of NSCLC cells is correlated with the induction of DNA damage, and to investigate its underlying mechanism. STUDY DESIGN: The anti-proliferative effects of NFD were assessed by MTS Assay Kit FACS assay, and in vivo nude mice xenograft assay. The DNA damage related proteins, the Bcl-2 family and pro-apoptotic factors were examined by immunofluorescence assay, q-PCR, and western blotting. The activity of NF-κB p65 in nuclear extracts was detected using a colorimetric DNA-binding ELISA assay. The inhibitory activity of topoisomerase II (TOPO II) was evaluated by molecular docking and TOPO II catalytic assay. RESULTS: NFD exerted selective cytotoxicity against NSCLC H1299, H1437 and A549 cells rather than normal lung-embryonated cells MRC-5. Remarkably, we found that NFD activated the hull marker and modulator of DNA damage repairs such as γ-H2AX, ATM, ATR, CHK1, and CHK2 probably caused by the accumulation of intracellular reactive oxygen species (ROS) and inhibition of TOPO II activity. Furthermore, the suppression of transcription factor NF-κB by NFD resulted in significantly decreased levels of pro-survival proteins including Bcl-2 family Bcl-2, Bcl-xL and Mcl-1 and the endogenous inhibitors of apoptosis XIAP and survivin in H1299 cells. Moreover, the nude mice xenograft assay further validated the suppression of H1299 growth by NFD, which is the first report for evaluating the anti-cancer effect of NFD in vivo. CONCLUSION: These findings provide a novel mechanism indicating the inhibition of TOPO II activity and NF-κB signaling by NFD, leading to DNA damage and apoptosis of NSCLC tumor cells.

Novel indoloquinoline derivative, IQDMA, suppresses STAT5 phosphorylation and induces apoptosis in HL-60 cells.

Signal transducers and activators of transcription (STATs) are a family proteins that mediate cytokine and growth factor-induced signals playing a role in cell differentiation, proliferation, angiogenesis, and apoptosis. One STAT family member, STAT5, is often constitutively active in myeloid leukaemia. Agents that can suppress STAT5 activation have potential for prevention and treatment of cancer. N'-(11H-indolo[3,2-c]quinolin-6-yl)-N,N-dimethylethane-1,2-dia-mine (IQDMA), an indoloquinoline derivative, synthesized in our laboratory, has been demonstrated to be an effective anti-tumor agent in human leukemia cells. In the present report, we tested IQDMA for its ability to suppress STAT5 activation. We found that IQDMA inhibited constitutive activation of STAT5 in HL-60 cells in a dose- and time-dependent manner. The activation of Src and interleukin-6 (IL-6), implicated in STAT5 activation, was also inhibited by the IQDMA. Furthermore, IQDMA up-regulated Bax, and down-regulated Bcl-2, Bcl-X(L), cyclin D1, and vascular endothelial growth factor (VEGF) as followed by growth arrest of HL-60 cells, but the expression of survivin did not change in the presence of IQDMA. Taken together, these results indicate that IQDMA causes significant induction of apoptosis in HL-60 cells via down-regulation of Src, IL-6, and STAT5 signaling and modulation of Bcl-2 family, cyclin D1 and VEGF proteins. Thus, IQDMA appears to be a potential therapeutic agent for treating leukaemia HL-60 cells.

Cardiotoxin III-induced apoptosis is mediated by Ca2+-dependent caspase-12 activation in K562 cells.

Cardiotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity. When K562 cells were treated with CTX III, cytosolic calcium concentration was rapidly and persistently increased. This CTX III-induced cell death was partially reversed by pretreatment with BAPTA/AM (20 microM), a chelator of intracellular Ca2+. Moreover, CTX III-induced apoptotic signals, such as caspase-12 and c-Jun N-terminal kinase (JNK) activation, were induced in a time-dependent manner and inhibited by BAPTA/AM. In contrast, the neutral protease micro-calpain, a key enzyme in endoplasmic reticulum (ER) stress-related apoptosis via caspase-12 activation, was unchanged during apoptosis. Taken together, our findings suggest CTX III-induced apoptosis is triggered by Ca2+ influx, then activated caspase-12 and JNK through micro-calpain-independent cascade, and consequently caused apoptosis.

Novel indoloquinoline derivative, IQDMA, inhibits STAT5 signaling associated with apoptosis in K562 cells.

N'-(11H-indolo[3,2-c]quinolin-6-yl)-N,N-dimethylethane-1,2-diamine (IQDMA), an indoloquinoline derivative, synthesized in our laboratory, has been demonstrated to be an effective antitumor agent in human leukemia cells. In the present study, treatment with IQDMA inhibited phosphorylation of epidermal growth factor receptor (EGFR), Src, Bcr-Abl, and Janus-activated kinase (JAK2) in a time-dependent manner. IQDMA also degraded JAK2 protein. Moreover, signal transducer and activator of transcription 5 (STAT5) signaling were also blocked by IQDMA. However, IQDMA did not inhibit other oncogenic and tumor survival pathways such as those mediated by Akt and extracellular signal-regulated kinase 1/2. Furthermore, IQDMA upregulated the expression of p21 and p27 and downregulated the expression of cyclin D1, myeloid cell leukemia-1(Mcl-1), Bcl-X(L), and vascular endothelial growth factor (VEGF). Taken together, these results indicate that IQDMA causes significant induction of apoptosis in K562 cells via downregulation of EGFR, Src, Bcr-Abl, JAK2, and STAT5 signaling and modulation of p21, p27, cyclin D1, Mcl-1, Bcl-X(L), and VEGF proteins. Thus, IQDMA appears to be a potential therapeutic agent for treating leukemia K562 cells.

Cardiotoxin III induces c-jun N-terminal kinase-dependent apoptosis in HL-60 human leukaemia cells.

Cardiotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity. The molecular effects of CTX III on HL-60 cells were dissected in the present study. We found that the antiproliferative action of CTX III on HL-60 cells was mediated through apoptosis, as characterized by an increase of sub G1 population, DNA fragmentation and poly(ADP-ribose) polymerase (PARP) cleavage. Upregulation of Bax, downregulation of Bcl-2, the release of mitochondrial cytochrome c to cytosol and the activations of capase-9 and -3 were noted, while CTX III had no appreciable effect on the levels of Bcl-X(L) and Bad proteins. Moreover, c-Jun N-terminal kinase (JNK) was activated shortly after CTX III treatment in HL-60 cells. Consistently, the SP600125 compound, an anthrapyrazolone inhibitor of JNK, suppressed apoptosis induced by CTX III. As expected, this JNK inhibitor also attenuated the modulation of Bax and Bcl-2, as well as the cytosolic appearance of cytochrome c and the activation of caspase-3 and caspase-9 that induced by CTX III. These findings suggest that CTX III can induce apoptosis in HL-60 cells via the mitochondrial caspase cascade and the activation of JNK is critical for the initiation of the apoptotic death of HL-60 cells.

Involvement of both endoplasmic reticulum- and mitochondria-dependent pathways in cardiotoxin III-induced apoptosis in HL-60 cells.

Cardiotoxin (CTX) III, a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity. In the present study, we investigated the mechanisms underlying the anticancer activity of CTX III in human leukaemia (HL-60 cells). Cardiotoxin III activated the endoplasmic reticulum (ER) pathway of apoptosis in HL-60 cells, as indicated by increased levels of calcium and glucose-related protein 78 (Grp78), and triggered the subsequent activation of micro-calpain and caspase 12. In addition, CTX III initiated the mitochondrial apoptotic pathway in HL-60 cells, as evidenced by an increased Bax/Bcl-2 ratio, the release of cytochrome c and activation of caspase 9. In the presence of 50 micromol/L Z-ATAD-FMK (a caspase 12 inhibitor) and 100 micromol/L Z-LEHD-FMK (a caspase 9 inhibitor), the CTX III-mediated activation of caspase 9 and caspase 3 was significantly reduced. There was no significant effect of the caspase 12 inhibitor Z-ATAD-FMK on mitochondrial cytochrome c release. Cardiotoxin III-mediated activation of caspase 12 was not abrogated in the presence of the caspase 9 inhibitor Z-LEHD-FMK, indicating that caspase 12 activation was not downstream of caspase 9. These results indicate that CTX III induces cell apoptosis via both ER stress and a mitochondrial death pathway.