Indirubin-3'-monoxime Research Articles

Identification of novel brain penetrant GSK-3β inhibitors toward Alzheimer’s disease therapy by virtual screening, molecular docking, dynamic simulation, and MMPBSA analysis

One of the significant therapeutic targets for Alzheimer’s disease (AD) is Glycogen Synthase Kinase-3β (GSK-3β). Inhibition of GSK-3β can prevent hyperphosphorylation of tau, and thus prevent formation and accumulation of neurofibrillary tangles and neuropil threads that block intracellular transport, trigger unfolded protein response, and increase oxidative stress, cumulatively leading to neurodegeneration. In this study, we have performed structure-based virtual screening of two small-molecule libraries from ChemDiv CNS databases using AutoDock Vina to identify hit molecules based on their binding affinities compared to that of an established GSK-3β inhibitor, indirubin-3’-monoxime (IMO). Pharmacoinformatic screening on SwissADME and pkCSM servers enabled identification of lead molecules with favorable pharmacoinformatic properties for drug likeliness, including blood brain barrier (BBB) permeability. Further, molecular dynamic simulations identified six candidate lead molecules that show stable complex formation with GSK-3β in dynamic state under physiological conditions. Principal component analysis of the dynamic state was used to plot Free Energy Landscapes (FELs) of GSK-3β-ligand complexes. STRIDE secondary structure analysis of the lowest energy conformations identified from FEL plots, and binding free energy calculations by Molecular Mechanics Poisson-Boltzmann Surface Area ((ΔGbind )MM-PBSA) of the simulation trajectories led to the identification of two ligands as potential lead molecules having favorable free energy landscape profiles as well as significantly lower (ΔGbind )MM-PBSA in dynamic state compared to that of reference inhibitor IMO. Hence, this study identifies two novel brain penetrant GSK-3β inhibitors that are likely to have therapeutic potential against Alzheimer’s disease.

Establishment of Patient-Derived Xenograft (PDX) Zebrafish Model of Multiple Myeloma and Its Application in Drug Screening

To establish a MM patient-derived tumor xenograft model (MM-PDX) in zebrafish, and to evaluate the anti-myeloma activity of indirubin-3'-monoxime(I3MO) using this model. Zebrafish embryos 2 days after fertilization were transplanted with fluorescence labeled myeloma primary tumor cells, the survival of primary tumor cells in zebrafish was observed at 0,16 and 24 hours after cell injection. The zebrafish embryos after tumor cell transplantation were randomly divided into control group, BTZ treatment and I3MO treatment group. Before and 24 hours after treatment with BTZ and I3MO, the positive area with calcein or Dil in zebrafish were observed under fluorescence microscope to reflect the survival of tumor cells, and it was verified. MM patient derived tumor cells survived in zebrafish. The construction of MM-PDX was successful. Compared with control group, the fluo- rescence area of the BTZ and I3MO treatment groups in zebrafish were significantly decreased(P<0.05), and BTZ and I3MO significantly inhibited the survival of MM cells in zebrafish. MM-PDX model was successfully established. Zebrafish model derived from tumor cells of MM patients can be used as a tool for drug screening of MM.

A Novel Indirubin-3-Monoxime Derivative Functions As Regulator of Proteostasis Via Targeting TRIM28 in Multiple Myeloma

Introduction: Multiple myeloma (MM) remains an incurable plasma cell malignancy. Agents disturbing the proteostasis play indispensable roles in MM treatment. Our previous studies have shown that the indirubin-3-monoxime (I3MO) works as a novel proteasome inhibitor that effectively inhibits MM cell growth. In this study, we aim to investigate the improvement of I3MO combined with histone deacetylase 6 (HDAC6) inhibitors, and clarified the molecular mechanisms. Methods: We constructed a compound 8b combined with I3MO and HADC6 inhibitor. The anti-MM effects of compound 8b were investigated in vivo and in vitro studies. Western blots, immunofluorescence, and proteasome activity assay were utilized to investigate the effects of 8b on MM cell proteasome activity, aggresome and autophagosome formation. RNA-seq and Dual-luciferase reporter gene assay were performed to identify the downstream targets of 8b treatment. We constructed MM cell lines with TRIM28 overexpression or shRNA knockdown. We further explored the function of TRIM28, one of the targets of 8b treatment, by ChIP-seq and IP-MS. Results: The novel I3MO derivative 8b more efficiently suppressed myeloma cell growth in vitro and in vivo. Compound 8b not decreased proteasome activity but inhibited the formation of aggresomes and autophagosomes. Interesting, we found that compound 8b efficiently inhibited TRIM28 promoter activity and repressed TRIM28 transcription level further. GEO data analysis demonstrated a positive correlation between TRIM28 and the expression of proteasome subunits as well as autophagy-related genes in MM. Further, we utilized ChIP-seq to confirm that TRIM28 could bind to the promoter region of multiple proteasome subunits-encoding genes, including PSMB1. Our data indicated that TRIM28 knockdown not only decreased the proteasome activity, but inhibited the formation of autophagosomes. Knockdown TRIM28 induced a higher sensitivity to BTZ treatment in MM cells. Furthermore, IP-MS with Co-IP analysis showed that TRIM28 interacts with 14-3-3ζ. TRIM28 acts as an E3 ligase in mediating the ubiquitination and degradation of 14-3-3ζ, a well-known negative regulator of autophagy. 14-3-3ζ degradation induced by TRIM28 activates autophagy in MM cells. These data suggested that TRIM28 suppressed by compound 8b would involve in proteostasis by regulation of proteasome activity and autophagy. Conclusions: Our study identified a novel compound 8b, I3MO combined with HDAC6i, efficiently suppressed MM cells survival. Additionally, we for the first time provided novel important insights for the roles of TRIM28 in MM pathobiology by regulation of proteasome activity and autophagy.

Establishment of Patient-Derived Xenograft (PDX) Zebrafish Model of Multiple Myeloma and Its Application in Drug Screening

Objective: To confirm the in vivo anti-myeloma activity of I3MO (Indirubin-3' -monoxime) in primary patient samples, a patient-derived xenograft (PDX) zebrafish model of MM was utilized. Methods: zebrafish embryos were obtained by the natural spawning of Tubingen strain and incubated at 28°C in embryo medium. The purified CD138+ MM cells fluorescently labeled with Calcein-AM or Dil were injected into the perivitelline space of each embryo of zebrafish at 48 hpf. Engrafted embryos were transferred into 24-well plates and incubated at 28°C in freshly prepared E3 medium containing DMSO, BTZ, I3MO. At 24 hours post injection (hpi), engrafted embryos were detected by fluorescent microscopy to qualify the positive areas with calcein (green) or Dil (red). Results:1. The zebrafish PDX model of MM was successfully applied in the drug effects evaluation. 2. The results in vivo demonstrated that BTZ or I3MO eliminates the engraftment and growth of MM cells in zebrafish embryos (p<0.05). Conclusion: The zebrafish is an ideal model to investigate the cytotoxicity in vivo of compounds on primary MM patient samples.

Indirubin-3'-monoxime acts as proteasome inhibitor: Therapeutic application in multiple myeloma.

SummaryBackgroundMultiple myeloma (MM) is still an incurable malignancy of plasma cells. Proteasome inhibitors (PIs) work as the backbone agent and have greatly improved the outcome in majority of newly diagnosed patients with myeloma. However, drug resistance remains the major obstacle causing treatment failure in clinical practice. Here, we investigated the effects of Indirubin-3’-monoxime (I3MO), one of the derivatives of Indirubin, in the treatment of MM.MethodsMM patient primary samples and human cell lines were examined. I3MO effects on myeloma treatment and the underling molecular mechanisms were investigated via in vivo and in vitro study.FindingsOur results demonstrated the anti-MM activity of I3MO in both drug- sensitive and -resistance MM cells. I3MO sensitizes MM cells to bortezomib-induced apoptosis. Mechanistically, I3MO acts as a multifaceted regulator of cell death, which induced DNA damage, cell cycle arrest, and abrogates NF-κB activation. I3MO efficiently down-regulated USP7 expression, promoted NEK2 degradation, and suppressed NF-κB signaling in MM. Our study reported that I3MO directly bound with and caused the down-regulation of PA28γ (PSME3), and PA200 (PSME4), the proteasome activators. Knockdown of PSME3 or PSME4 caused the inhibition of proteasome capacity and the overload of paraprotein, which sensitizes MM cells to bortezomib-mediated growth arrest. Clinical data demonstrated that PSME3 and PSME4 are over-expressed in relapsed/refractory MM (RRMM) and associated with inferior outcome.InterpretationAltogether, our study indicates that I3MO is agent triggering proteasome inhibition and represents a promising therapeutic strategy to improve patient outcome in MM.FundingsA full list of funding can be found in the acknowledgements.

Indirubin-3-monoxime and thymoquinone exhibit synergistic efficacy as therapeutic combination in in-vitro and in-vivo models of Lung cancer.

In this study, we report the combination of indirubin-3-monoxime (I3M) and thymoquinone (Tq) to have excellent therapeutic efficacy in models of Lung cancer (LC). Preliminary screening was done with A549 cells. Cell cycle, apoptosis and NFκB phosphorylation were determined by flow cytometry, while apoptotic proteins, Akt and mTOR were assessed by western blotting. Mouse xenograft model was used to assess the therapeutic efficacy in-vivo. Synergistic reduction in cell viability was observed with I3M + Tq combinations, which were non-toxic to normal HFL-1 cells. Cell cycle analysis indicated G1 phase reduction with subsequent accumulation of sub G0 contents. Annexin V assay revealed higher apoptotic cells with combinations compared to individual treatments with a decrease in Bcl-2/Bax ratio. The combinations exhibited anti-metastasis activity in cell migration in the scratch, scatter and tumour cell migration assays and effectively reduced the tumour growth in mouse xenograft model. Expression levels of p-AKT, p-mTOR, Caspase-3, p-53 and NFκB were significantly reduced in the combination treated mice compared to individual treatments. Results of current study demonstrate clear efficacy of I3M + Tq combinations in LC models mediated by suppressing Akt/mTOR/NFκB signalling. Further research is recommended to transform these findings into novel therapeutic combinations against LC.

Protocol development for discovery of angiogenesis inhibitors via automated methods using zebrafish.

Their optical clarity as larvae and embryos, small size, and high fecundity make zebrafish ideal for whole animal high throughput screening. A high-throughput drug discovery platform (HTP) has been built to perform fully automated screens of compound libraries with zebrafish embryos. A Tg(kdrl:EGFP) line, marking endothelial cell cytoplasm, was used in this work to help develop protocols and functional algorithms for the system, with the intent of screening for angiogenesis inhibitors. Indirubin 3’ Monoxime (I3M), a known angiogenesis inhibitor, was used at various concentrations to validate the protocols. Consistent with previous studies, a dose dependant inhibitory effect of I3M on angiogenesis was confirmed. The methods and protocols developed here could significantly increase the throughput of drug screens, while limiting human errors. These methods are expected to facilitate the discovery of novel anti-angiogenesis compounds and can be adapted for many other applications in which samples have a good fluorescent signal.

Rational combinations of indirubin and arylidene derivatives exhibit synergism in human non-small cell lung carcinoma cells.

Rational combination of natural and synthetic derivatives to treat lung cancer has advantages of both efficacy and safety. Herein, the combination of indirubin-3-monoxime (I3M), a chemical derived from Chinese herbal medicine and FXY-1, a synthetic arylidene derivative, was tested for combined activity in lung cancer cells. A dose-dependent synergistic reduction in cell viability was recorded with the combinations in A549 and NCI-H460 cells. Combination treatments of I3M and FXY-1 showed antimetastatic effects in both cells. Cell cycle analysis revealed G1 growth phase reduction with subsequent accumulation of sub G0 contents. Annexin V assay revealed higher apoptotic cells with combinations compared to individual treatments. I3M+FXY-1 combination significantly decreased the antiapoptotic Bcl-2 protein and increased pro-apoptotic Bax protein levels. These results demonstrate efficacy of I3M+FXY-1 in lung cancer cells and suggest further preclinical research in animal models to develop it into a new form combination chemotherapeutic against lung cancer. PRACTICAL APPLICATIONS: Current investigation will open new options in rational combinations of natural and synthetic compounds to treat cancer. The observed efficacy and safety of the combinations will add to the advantage of higher therapeutic window in formulating treatment regimens. The antimetastatic effects by the combinations provides promising efficacy in controlling the lung cancer progression. A detailed in vivo investigation is recommended to transform the combinations to novel chemotherapeutic options against lung cancer.

Indirubin-3′-monoxime prevents aberrant activation of GSK-3β/NF-κB and alleviates high fat-high fructose induced Aβ-aggregation, gliosis and apoptosis in mice brain

Deciphering the molecular mechanisms of amyloid pathology and glial cell-mediated neuroinflammation, offers a novel avenue for therapeutic intervention against neurodegeneration. Recent findings demonstrate a crucial link between activation of glycogen synthase kinase-3β (GSK-3β), amyloid deposition and a neuroinflammatory state. However, studies demonstrating the pharmacological effects of GSK-3β inhibition and the interlinked molecular mechanisms still remain elusive. The present study explores whether high fat-high fructose diet (HFFD)-induced neuropathological changes could be alleviated by indirubin-3′-monoxime (IMX), a GSK-3β inhibitor. Male Swiss albino mice (8 weeks old) were fed with normal pellet or HFFD for 60 days. HFFD mice were treated with IMX once daily for last 7 days of the experimental period. HFFD fed-mice had significant amyloid deposits in cerebral cortex and hippocampus, and protein expression analyses showed activation of GSK-3β, nuclear translocation of NF-κB p65 and upregulation of inflammatory (TNF-α, IL-6, COX-2), astrocytic (GFAP), glial surface (CD-68) and pro-apoptotic markers (Bax and caspase-3). IMX treatment promotes the inhibitory phosphorylation of GSK-3β at Ser9 and moreover, a marked reduction in the phosphorylation of IKK-β, which prevents translocation and activation of NF-κB. Protein expression studies in IMX-treated brain tissues positively correlate with the anti-neuroinflammatory effects of GSK-3β inhibition. Taken together, our results provide substantial evidence that IMX could potentially attenuate neuroinflammation in coordination with the master transcription factor-NF-κB.

Inhibition of Suicidal Erythrocyte Death by Indirubin-3’-Monoxime

Background/Aims: Qing Dai is a prized traditional Chinese medicine whose major component, indirubin, and its derivative, indirubin-3’-monoxime (IDM), have inhibitory effects on the growth of many human tumor cells and pronounced anti-leukemic activities. However, the effects of IDM on mature human erythrocytes are unclear. This study aimed to evaluate the potential impact of IDM on erythrocytes and the mechanisms underlying that impact. Methods: Utilizing flow cytometry and confocal laser scanning microscopy, phosphatidylserine exposure at the cell surface was estimated by annexin V-fluorescein isothiocyanate (FITC). The relative cell size, expressed in arbitrary units, was evaluated by forward scatter in a flow cytometer. Fluo-3 fluorescence was used to bewrite changes in cytosolic Ca²⁺ activity, reactive oxygen species (ROS) formation was assessed by 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence, and ceramide abundance was evaluated by FITC-conjugated specific antibodies. Results: The 24-h exposure of human erythrocytes to IDM (12 µM) significantly decreased the percentage of annexin V-binding erythrocytes and the intracellular calcium concentration ([Ca²⁺]_i). IDM (3-12 µM) did not significantly modify the ceramide level or DCFH-DA fluorescence. Energy depletion (removal of glucose for 24 hours) significantly increased annexin V binding and Fluo-3 fluorescence and diminished forward scatter, and these effects were significantly mitigated by IDM (12 µM). Moreover, the Ca²⁺ ionophore ionomycin (1 µM, 60 min) and oxidative stress (30 min exposure to 0.05 mM tert-butyl hydroperoxide, t-BHP) similarly triggered eryptosis, which was also significantly suppressed by IDM. Conclusions: IDM is a novel inhibitor of suicidal erythrocyte death following ionomycin treatment, t-BHP treatment and energy depletion. Thus, IDM may counteract anemia and impairment of microcirculation, at least in part, by inhibition of Ca²⁺ entry into erythrocytes.

Increased aerobic glycolysis is important for the motility of activated VSMC and inhibited by indirubin-3′-monoxime

Increased aerobic glycolysis is a recognized feature of multiple cellular phenotypes and offers a potential point for drug interference, as pursued by anti-tumor agents targeting the Warburg effect. This study aimed at examining the role of aerobic glycolysis for migration of vascular smooth muscle cells (VSMC) and its susceptibility to the small molecule indirubin-3′-monoxime (I3MO). Activation of VSMC with platelet-derived growth factor (PDGF) resulted in migration and increased glycolytic activity which was accompanied by an increased glucose uptake and hexokinase (HK) 2 expression. Inhibition of glycolysis or hexokinase by pharmacological agents or siRNA-mediated knockdown significantly reduced the migratory behavior in VSMC without affecting cell viability or early actin cytoskeleton rearrangement. I3MO, previously recognized as inhibitor of VSMC migration, was able to counteract the PDGF-activated increase in glycolysis and HK2 abundance. Activation of signal transducer and activator of transcription (STAT) 3 could be identified as crucial event in upregulation of HK2 and glycolytic activity in PDGF-stimulated VSMC and as point of interference for I3MO. I3MO did not inhibit hypoxia-inducible factor (HIF)1α-dependent transcription nor influence miRNA 143 levels, other potential regulators of HK2 levels. Overall, we demonstrate that increased aerobic glycolysis is an important factor for the motility of activated VSMC and that the anti-migratory property of I3MO may partly depend on impairment of glycolysis via a compromised STAT3/HK2 signaling axis.

Neuroprotective role of Indirubin-3′-monoxime, a GSKβ inhibitor in high fat diet induced cognitive impairment in mice

Recent studies have highlighted that diabetes mellitus (DM) is a strong risk factor for Alzheimer’s disease (AD). Insulin resistance and/or hyperinsulinemia is one of the main characteristics of type 2 DM. Numerous epidemiological studies have demonstrated that insulin resistance contributes to AD pathogenesis. However the molecular mechanisms of association between these still remain elusive. Among the various possible mechanisms, the GSK-3β activity has been reported to be impaired in insulin-resistance, type 2 DM and AD. Thus, the present study was designed to explore the neuroprotective role of GSK3 β inhibitor, Indirubin-3′-monoxime (IMX) in insulin resistance induced cognitive impairment. Further, we have explored the possible molecular mechanism involved in cognitive impairment associated with insulin resistance. The mice subjected to high fat diet exhibited characteristic features of insulin resistance viz. increased serum glucose, triglycerides, cholesterol, insulin levels and impaired spatial learning and memory ability along with reduced brain insulin level, elevated oxidative stress and acetylcholinesterase (AChE) activity. The observed changes occurred concurrently with reduced brain derived neurotrophic factor. In contrast, the mice treated with IMX showed a significant reduction in plasma glucose, triglycerides, cholesterol, insulin levels and improvement in learning and memory performance, attenuated the oxidative stress and AChE activity. Moreover, IMX dose dependently augment the brain insulin and BDNF levels in HFD fed mice. Based upon these findings it could be suggested that GSK3 β inhibition could prove to be beneficial in insulin resistance induced cognitive deficit and this neuroprotection could be the result of enhanced BDNF based synaptic plasticity.

Abstract 562: High-Throughput Analysis of Compounds Targeting Zebrafish Angiogenesis and Vascular Development

Introduction: Angiogenic sprouting occurs in the presence of high levels of exogenous pro-angiogenesis factors. Pathological over expression of pro-angiogenesis factors leads to excessive tumor growth. Inhibition of pro-angiogenesis factors can restrict tumor growth. But, prolonged inhibition can lead to the activation of alternate pro-angiogenesis pathways. The objective of this research is to discover compounds that inhibit multiple pro-angiogenesis factors and increase efficacy in the treatment of cancerous tumors using zebrafish vascular development as a model in a high throughput setting. Methods: The NIH Clinical Collections Libraries I and II will be screened with a fully automated high throughput drug screening platform (HTS). Compounds that cause abnormal vascular phenotypes will be identified on Tg(flk1:EGFP) embryos. The lead compounds will then be analyzed with 3-D confocal imaging, studies on cultured human umbilical vein endothelial cells (HUVECs), and animal cancer models. Results: The HTS was constructed and made operational. A protocol for anti-angiogenesis screening with Tg(flk1:EGFP) zebrafish has been developed and validated with indirubin 3’ monoxime (I3M), a known angiogenesis inhibitor. Pixel counting (to quantify the overall vascular network) and ISV counting (to count the number of ISVs and give an indication of overall vascular morphology) programs were created to provide readouts from confocal images taken within the HTS. Normative parameters, including several endothelial cell counts and various vessel length measurements, were characterised at the 1 and 2 days post fertilization (dpf) stages using 3-D confocal imaging. These values will be compared to values found in the presence of lead compounds to validate them as angiogenesis inhibitors. Conclusions &amp; Future Work: The framework for a robust drug discovery process has been put in place. The next step is to screen the NIH Clinical Collections Libraries I and II and analyze the efficacy and mechanism of lead compounds. Based on data from previous manual screens, 5-10 lead compounds are expected to be identified. These compounds will have the potential to be developed as repurposed anti-angiogenesis compounds and improve therapeutics for cancerous tumors.

Indirubin-3′-monoxime exerts a dual mode of inhibition towards leukotriene-mediated vascular smooth muscle cell migration

AimsThe small molecule indirubin-3′-monoxime (I3MO) has been shown to inhibit vascular smooth muscle cell (VSMC) proliferation and neointima formation in vivo. The influence of I3MO on VSMC migration and vascular inflammation, two additional key players during the onset of atherosclerosis and restenosis, should be investigated.Methods and resultsWe examined the influence of I3MO on VSMC migration, with focus on monocyte-derived leukotrienes (LTs) and platelet-derived growth factors (PDGFs) as elicitors. Exogenous LTB4 and cysteinyl leukotrienes as well as LT-enriched conditioned medium of activated primary human monocytes induced VSMC migration, which was inhibited by I3MO. I3MO also blunted migration of VSMC stimulated with the PDGF, the strongest motogen tested in this study. Induction of haem oxygenase 1 accounted for this anti-migratory activity of I3MO in VSMC. Notably, I3MO not only interfered with the migratory response in VSMC, but also suppressed the production of pro-migratory LT in monocytes. Conditioned media from monocytes that were activated in the presence of I3MO failed to induce VSMC migration. In cell-based and cell-free assays, I3MO selectively inhibited 5-lipoxygenase (5-LO), the key enzyme in LT biosynthesis, with an IC50 in the low micromolar range.ConclusionOur study reveals a novel dual inhibitory mode of I3MO on LT-mediated VSMC migration: (i) I3MO interferes with pro-migratory signalling in VSMC and (ii) I3MO suppresses LT biosynthesis in monocytes by direct inhibition of 5-LO. These inhibitory actions on both migratory stimulus and response complement the previously demonstrated anti-proliferative properties of I3MO and may further promote I3MO as promising vasoprotective compound.

12/15-Lipoxygenase Contributes to Platelet-derived Growth Factor-induced Activation of Signal Transducer and Activator of Transcription 3

We showed previously that the small molecule indirubin-3'-monoxime (I3MO) prevents vascular smooth muscle cell (VSMC) proliferation by selectively inhibiting signal transducer and activator of transcription 3 (STAT3). Looking for the underlying upstream molecular mechanism, we here reveal the important role of reactive oxygen species (ROS) for PDGF-induced STAT3 activation in VSMC. We show that neither NADPH-dependent oxidases (Noxes) nor mitochondria, but rather 12/15-lipoxygenase (12/15-LO) are pivotal ROS sources involved in the redox-regulated signal transduction from PDGFR to STAT3. Accordingly, pharmacological and genetic interference with 12/15-LO activity selectively inhibited PDGF-induced Src activation and STAT3 phosphorylation. I3MO is able to blunt PDGF-induced ROS and 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) production, indicating an inhibitory action of I3MO on 12/15-LO and consequently on STAT3. We identify 12/15-LO as a hitherto unrecognized signaling hub in PDGF-triggered STAT3 activation and show for the first time a negative impact of I3MO on 12/15-LO.

Molecular mechanism of indirubin-3′-monoxime and Matrine in the reversal of paclitaxel resistance in NCI-H520/TAX25 cell line

Background Multidrug resistance (MDR) is a main reason for paclitaxel (TAX) treatment failure. Indirubin-3′-monoxime (IRO) and Matrine are traditional Chinese medicines, which may reverse the resistance of tumor cells to some chemotherapy drugs, but the relationship between paclitaxel resistance and Matrine is still unclear. The aim of this study was to explore the potential molecular mechanism of IRO and Matrine in reversal of TAX resistance. Methods In this study, MTT assay was used to measure the non-cytotoxic dosage of IRO and Matrine on NCI-H520/TAX25 cells and determine the reversal extent of TAX resistance under non-toxic doses. In addition, RT-PCR and Western blotting were used to evaluate the mRNA expression and the protein level of survivin, Oct-4, and Sox-2 in NCI-H520/TAX25 cells using semi-quantitative methods. Results There was no obvious inhibition on sensitive cell strains and drug-resistant strains, when the final concentration was at lest 4 μmol/L for IRO and 100 μmol/L for Matrine. So 4 μmol/L of IRO and 100 μmol/L of Matrine were considered as the reversal dosage. When 4 μmol/L of IRO or 100 μmol/L of Matrine were used together with TAX, the sensitivity to TAX increased evidently in NCI-H520/TAX2 cells; the reversal rate of IRO and Matrine was about 1.92 (43.56/22.6 nmol/L) and 1.74 (43.56/25.0 nmol/L), respectively. The mRNA expression and the protein level of survivin, Oct-4, and Sox-2 in NCI-H520/TAX25 decreased significantly (P &lt;0.05) after addition of IRO or Matrine in TAX treatment, compared to that of TAX treatment alone. Conclusion The decrease in both mRNA expression and protein level of survivin, Oct-4, and Sox-2 might be the molecular mechanism, by which IRO and Matrine mediate the reversal of TAX resistance.

Pharmacological inhibition of GSK-3β produces late phase of cardioprotection in hyperlipidemic rat: possible involvement of HSP 72

The acute, as well as late, phase of cardioprotection induced by ischemic preconditioning is abolished in hyperlipidemic (HL) rat heart. The pharmacological inhibition of glycogen synthase kinase-3β (GSK-3β), has earlier been reported to restore this attenuated acute cardioprotective effect. However, it not known whether GSK-3β inhibitors administered 24 h before the ischemic injury would restore the late cardioprotective in HL rat and, if yes, the role of heat shock protein 72 (HSP 72) in its modulation. Hyperlipidemia was produced in rat by feeding high-fat diet for 6 weeks. Isolated perfused rat heart was subjected to 30 min of ischemia followed by 120 min of reperfusion (I/R). Myocardial infarct size was estimated by triphenyltetrazolium chloride staining, while lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) levels were analyzed from coronary effluent. GSK-3β inhibitors, SB 216763 (SB, 0.6 mg/kg, i.p.), and indirubin-3 monoxime (IND, 0.4 mg/kg, i.p.), administered 24 h before the isolation of heart, significantly decreased the I/R-induced myocardial infarct size and the release of LDH and CK-MB. The cardioprotective effect of GSK-3β inhibitors was significantly attenuated by quercetin (4 mg/kg, i.p.), a HSP 72 inhibitor, administered 1 h before the administration of SB or IND. That the late phase of cardioprotection induced by pretreatment with GSK-3β inhibitors is not attenuated/lost in HL rat heart is a new finding in our study. Our results indicate that HSP 72 acts on pathway of GSK-3β and plays a significant role in cardioprotection.

Indirubin-3-monoxime exhibits anti-inflammatory properties by down-regulating NF-κB and JNK signaling pathways in lipopolysaccharide-treated RAW264.7 cells

Indirubin-3-monoxime (I3M), an indirubin analogue that shows favorable inhibitory activity targeting cyclin-dependent kinase and glycogen synthase kinase, exhibits various biological properties, including chemopreventive, antiangiogenic, and neuropreventive activities. In the present study, we investigated the ability of I3M to regulate inflammatory reactions in macrophages. The effects of I3M on inflammation, lipopolysaccharide (LPS)-induced releases of inflammatory mediators, nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling was examined by ELISA and Western blotting analysis. I3M suppressed not only the generation of nitric oxide (NO) and prostaglandin E(2) but also the expression of inducible NO synthase and cyclooxygenase-2 induced by LPS. Similarly, I3M inhibited the release of pro-inflammatory cytokines induced by LPS in RAW264.7 cells, including interleukin (IL)-1β and IL-6. The underlying mechanism of I3M on anti-inflammatory action was correlated with down-regulation of the NF-κB and MAPK activation. Our data collectively indicate that I3M inhibited the production of several inflammatory mediators and might be used for the treatment of various inflammatory diseases.

Indirubin‐3'‐monoxime, a derivative of a chinese antileukemia medicine, inhibits angiogenesis

Although the antiangiogenic activity of indirubin-3-monoxime (I3M), a derivative of a Chinese anti-leukemia medicine, has been demonstrated using transgenic zebrafish, the detail molecular mechanism has not been elicited. To further establish its role in antiangiogenic activity, we tested its potential against human umbilical vein endothelial cells (HUVECs) and the in vivo Matrigel plug model was applied to evaluate new vessel formation. We also investigated the molecular mechanisms of I3M-induced antiangiogenic effects in HUVECs. We found that I3M significantly inhibited HUVEC proliferation (2.5-20 µM), migration (2.5-20 µM), and tube formation (10-20 µM) in HUVECs. The number of microvessels growing from the aortic rings was suppressed by I3M treatment. Moreover, I3M suppressed neovascularization in Matrigel plugs in mice. The underlying antiangiogenic mechanism of I3M was correlated with down-regulation of the vascular endothelial growth factor receptor-2 activation, at least a part. These findings emphasize the potential use of I3M in pathological situations involving stimulated angiogenesis, such as tumor development.

Indirubin-3′-Monoxime Blocks Vascular Smooth Muscle Cell Proliferation by Inhibition of Signal Transducer and Activator of Transcription 3 Signaling and Reduces Neointima Formation In Vivo

Our goal was to examine the influence of indirubin-3'-monoxime (I3MO), a natural product-derived cyclin-dependent kinase inhibitor, on vascular smooth muscle cell (VSMC) proliferation in vitro, experimentally induced neointima formation in vivo, and related cell signaling pathways. I3MO dose-dependently inhibited platelet-derived growth factor (PDGF)-BB-induced VSMC proliferation by arresting cells in the G(0)/G(1) phase of the cell cycle as assessed by 5-bromo-2'-deoxyuridine incorporation and flow cytometry. PDGF-induced activation of the kinases Akt, Erk1/2, and p38(MAPK) was not affected. In contrast, I3MO specifically blocked PDGF-, interferon-γ-, and thrombin-induced phosphorylation of signal transducer and activator of transcription 3 (STAT3). Human endothelial cells (EA.hy926) responded to I3MO with increased endothelial nitric oxide synthase activity as assessed via [(14)C]l-arginine/[(14)C]l-citrulline conversion. The specific STAT3 inhibitor Stattic led to decreased VSMC proliferation, and transient expression of a constitutively active form of STAT3 overcame the I3MO-induced cell cycle arrest in mouse embryonic fibroblasts. In a murine femoral artery cuff model, I3MO prevented neointima formation while reducing STAT3 phosphorylation and the amount of proliferating Ki67-positive cells. I3MO represses PDGF- and thrombin-induced VSMC proliferation and, in vivo, neointima formation, likely because it specifically blocks STAT3 signaling. This profile and its positive effect on endothelial NO production turns I3MO into a promising lead compound to prevent restenosis.