Indirubin-3′-monoxime inhibits β-amyloid-induced neurotoxicity in neuroblastoma SH-SY5Y cells

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.

Thymoquinone and curcumin combination protects cisplatin-induced kidney injury, nephrotoxicity by attenuating NFκB, KIM-1 and ameliorating Nrf2/HO-1 signalling

This study evaluates the protective effects of Thymoquinone (Tq) and Curcumin (Cur) in models of cisplatin-induced renal toxicity. Proliferation studies were carried out in HEK-293 cells. Cisplatin(ip) 5 mg/kg BW was used to induce renal injury in Sprague-Dawley rats. 50 mg/kg BW Tq + 100 mg/kg BW Cur, with or without cisplatin-treatment were administered for 5 days. Tq + Cur combination synergistically reduced the proliferation inhibition of HEK-293 cells resulted from cisplatin treatment and brought down cisplatin-induced apoptosis in these cells. In vitro studies revealed serum levels of BUN, creatinine, CK and pro-inflammatory cytokines like TNF-α, IL-6 and MRP-1 to be elevated in the cisplatin-treated group while reducing glomerular filtration rate. Tq + Cur treatment significantly improved these conditions. The antioxidant enzyme levels and mitochondrial ATPases were restored upon treatment, which were lessened in the cisplatin-treated group. Cisplatin induced the expression of KIM-1, which was brought down by the combination treatment. Tq + Cur treatment increased the expressions of phosphorylated Akt, Nrf2 and HO-1 proteins while decreasing the levels of cleaved caspase 3 and NFκB in kidney homogenates. In summary, Tq + Cur had protective effects on cisplatin-induced nephrotoxicity and renal injury, which could be mediated by up-regulation of survival signals like Akt, Nrf2/HO-1 and attenuation of KIM-1, NFκB.

Viral Induced Oxidative and Inflammatory Response in Alzheimer's Disease Pathogenesis with Identification of Potential Drug Candidates: A Systematic Review using Systems Biology Approach

Alzheimer's disease (AD) is genetically complex with multifactorial etiology. Here, we aim to identify the potential viral pathogens leading to aberrant inflammatory and oxidative stress response in AD along with potential drug candidates using systems biology approach. We retrieved protein interactions of amyloid precursor protein (APP) and tau protein (MAPT) from NCBI and genes for oxidative stress from NetAge, for inflammation from NetAge and InnateDB databases. Genes implicated in aging were retrieved from GenAge database and two GEO expression datasets. These genes were individually used to create protein-protein interaction network using STRING database (score≥0.7). The interactions of candidate genes with known viruses were mapped using virhostnet v2.0 database. Drug molecules targeting candidate genes were retrieved using the Drug- Gene Interaction Database (DGIdb). Data mining resulted in 2095 APP, 116 MAPT, 214 oxidative stress, 1269 inflammatory genes. After STRING PPIN analysis, 404 APP, 109 MAPT, 204 oxidative stress and 1014 inflammation related high confidence proteins were identified. The overlap among all datasets yielded eight common markers (AKT1, GSK3B, APP, APOE, EGFR, PIN1, CASP8 and SNCA). These genes showed association with hepatitis C virus (HCV), Epstein- Barr virus (EBV), human herpes virus 8 and Human papillomavirus (HPV). Further, screening of drugs targeting candidate genes, and possessing anti-inflammatory property, antiviral activity along with a suggested role in AD pathophysiology yielded 12 potential drug candidates. Our study demonstrated the role of viral etiology in AD pathogenesis by elucidating interaction of oxidative stress and inflammation causing candidate genes with common viruses along with the identification of potential AD drug candidates.

Inhibitory effects of indirubin-3'-monoxime against human osteosarcoma

Indirubin is widely used as the active component of "Dangui Luhui Wan" in ancient China. However, its effects against the osteosarcoma (OS), the most common primary malignancy, are still unknown. In our present study, we investigated the effects of the Indirubin-3'-monoxime (I3M), a derivative of indirubin with better water solubility, against the OS cells. We found I3M inhibited OS cell proliferation in a dose-dependent manner. Flow cytometry assays showed that I3M could not only induce OS cell apoptosis in a time- and dose-dependent manner but also regulate the cell cycle distribution. Additionally, we demonstrated that several Bcl-2 family members, cyclin-dependent kinases (CDKs) and cyclins contributed to this process. Furthermore, out data verified that I3M suppressed OS cell migration and invasion by decreasing MMP-2 and MMP-9 levels. Moreover, survivin and focal adhesion kinase (FAK) might play important roles in the anti-OS effects of I3M. The administration of I3M also inhibited the OS cell growth in mice. Taken together, our results indicated the inhibitory effects of I3M against human OS and thus might be an efficient candidate for OS chemotherapy.

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.

Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio) Attenuates Aβ Oligomer-Induced Cognitive Impairments in Mice

Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio), an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3β (GSK3β), two pharmacological targets of Alzheimer's disease (AD). In this study, we have discovered that 2.3–23.3 μg/kg 7Bio effectively prevented β-amyloid (Aβ) oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aβ oligomer-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aβ oligomer-treated mice. The mean optical density (OD) with hyper-phosphorylated tau (pTau), glial fibrillary acidic protein (GFAP) and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aβ oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aβ oligomer-decreased expression of pSer9-GSK3β. Those results suggested that 7Bio could potently inhibit Aβ oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.

Indirubin-3'-monoxime suppresses amyloid-beta-induced apoptosis by inhibiting tau hyperphosphorylation

Indirubin-3′-monoxime is an effective inhibitor of cyclin-dependent protein kinases, and may play an obligate role in neuronal apoptosis in Alzheimer's disease. Here, we found that indirubin-3′-monoxime improved the morphology and increased the survival rate of SH-SY5Y cells exposed to amyloid-beta 25–35 (Aβ_25–35), and also suppressed apoptosis by reducing tau phosphorylation at Ser199 and Thr205. Furthermore, indirubin-3′-monoxime inhibited phosphorylation of glycogen synthase kinase-3β (GSK-3β). Our results suggest that indirubin-3′-monoxime reduced Aβ_25–35-induced apoptosis by suppressing tau hyperphosphorylation via a GSK-3β-mediated mechanism. Indirubin-3′-monoxime is a promising drug candidate for Alzheimer's disease.

Indirubin-3-Oxime Prevents H2O2-Induced Neuronal Apoptosis via Concurrently Inhibiting GSK3β and the ERK Pathway

Oxidative stress-induced neuronal apoptosis plays an important role in many neurodegenerative disorders. In this study, we have shown that indirubin-3-oxime, a derivative of indirubin originally designed for leukemia therapy, could prevent hydrogen peroxide (H₂O₂)-induced apoptosis in both SH-SY5Y cells and primary cerebellar granule neurons. H₂O₂ exposure led to the increased activities of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinase (ERK) in SH-SY5Y cells. Indirubin-3-oxime treatment significantly reversed the altered activity of both the PI3-K/Akt/GSK3β cascade and the ERK pathway induced by H₂O₂. In addition, both GSK3β and mitogen-activated protein kinase inhibitors significantly prevented H₂O₂-induced neuronal apoptosis. Moreover, specific inhibitors of the phosphoinositide 3-kinase (PI3-K) abolished the neuroprotective effects of indirubin-3-oxime against H₂O₂-induced neuronal apoptosis. These results strongly suggest that indirubin-3-oxime prevents H₂O₂-induced apoptosis via concurrent inhibiting GSK3β and the ERK pathway in SH-SY5Y cells, providing support for the use of indirubin-3-oxime to treat neurodegenerative disorders caused or exacerbated by oxidative stress.

Indirubin-3-Oxime Effectively Prevents 6OHDA-Induced Neurotoxicity in PC12 Cells via Activating MEF2D Through the Inhibition of GSK3β

Indirubin-3-oxime (I3O), a synthetic derivative of indirubin, was originally designed as potent inhibitors of cyclin-dependent kinases (CDKs) and glycogen synthase kinase 3β (GSK3β) for leukemia therapy. In the current study, we have shown, for the first time, that I3O prevented 6-hydroxydopamine (6OHDA)-induced neuronal apoptosis and intracellular reactive oxygen species accumulation in PC12 cells in a concentration-dependent manner. GSK3β inhibitors but not CDK5 inhibitors reduced the neurotoxicity induced by 6OHDA. Moreover, the activation of GSK3β was observed after 6OHDA treatment. Furthermore, 6OHDA substantially decreased the transcriptional activity of myocyte enhancer factor 2D (MEF2D), a transcription factor that plays an important role in dopaminergic neuron survival, and reduced nuclear localized MEF2D expression. Interestingly, indirubin-3-oxime and GSK3β inhibitors prevented 6OHDA-induced dysregulation of MEF2D. In addition, short hairpin RNA-mediated decrease of MEF2D expression significantly abolished the neuroprotective effects of indirubin-3-oxime. Collectively, our results strongly suggested that indirubin-3-oxime prevented 6OHDA-induced neurotoxicity via activating MEF2D, possibly through the inhibition of GSK3β. In view of the capability of indirubin-3-oxime to cross the blood-brain barrier, our findings further indicated that indirubin-3-oxime might be a novel drug candidate for neurodegenerative disorders, including Parkinson's disease in particular.

Caffeoylquinic acids in Centella asiatica protect against amyloid-β toxicity

The accumulation of amyloid-β (Aβ) is a hallmark of Alzheimer's disease and is known to result in neurotoxicity both in vivo and in vitro. We previously demonstrated that treatment with the water extract of Centella asiatica (CAW) improves learning and memory deficits in Tg2576 mice, an animal model of Aβ accumulation. However the active compounds in CAW remain unknown. Here we used two in vitro models of Aβ toxicity to confirm this neuroprotective effect and identify several active constituents of the CAW extract. CAW reduced Aβ-induced cell death and attenuated Aβ-induced changes in tau expression and phosphorylation in both the MC65 and SH-SY5Y neuroblastoma cell lines. We confirmed and quantified the presence of several mono- and dicaffeoylquinic acids (CQAs) in CAW using chromatographic separation coupled to mass spectrometry and ultraviolet spectroscopy. Multiple dicaffeoylquinic acids showed efficacy in protecting MC65 cells against Aβ-induced cytotoxicity. Isochlorogenic acid A and 1,5-dicaffeoylquinic acid were found to be the most abundant CQAs in CAW, and the most active in protecting MC65 cells from Aβ-induced cell death. Both compounds showed neuroprotective activity in MC65 and SH-SY5Y cells at concentrations comparable to their levels in CAW. Each compound not only mitigated Aβ-induced cell death, but was able to attenuate Aβ-induced alterations in tau expression and phosphorylation in both cell lines, as seen with CAW. These data suggest that CQAs are active neuroprotective components in CAW, and therefore are important markers for future studies on CAW standardization, bioavailability, and dosing.

Morin attenuates tau hyperphosphorylation by inhibiting GSK3β

Alzheimer's disease (AD) is the major form of age-related dementia and is characterized by progressive cognitive impairment, the accumulation of extracellular amyloid β-peptide (Aβ), and intracellular hyperphosphorylated tau aggregates in affected brain regions. Tau hyperphosphorylation and accumulation in neurofibrillary tangles is strongly correlated with cognitive deficits, and is apparently a critical event in the dementia process because mutations in tau can cause a tangle-only form of dementia called frontotemporal lobe dementia. Among kinases that phosphorylate tau, glycogen synthase kinase 3β (GSK3β) is strongly implicated in AD pathogenesis. In the present study, we established an ELISA to screen for agents that inhibit GSK3β activity and found that the flavonoid morin effectively inhibited GSK3β activity and blocked GSK3β-induced tau phosphorylation in vitro. In addition, morin attenuated Aβ-induced tau phosphorylation and protected human neuroblastoma cells against Aβ cytotoxicity. Furthermore, treatment of 3xTg-AD mice with morin resulted in reductions in tau hyperphosphorylation and paired helical filament-like immunoreactivity in hippocampal neurons. Morin is a novel inhibitor of GSK3β that can reduce tau pathology in vivo and may have potential as a therapeutic agent in tauopathies.

Effect of indirubin-3-monoxime against lung cancer as evaluated by histological and transmission electron microscopic studies

The aim of this study is to evaluate the antitumor effect of indirubin-3-monoxime and its mode of action in benzo(α)pyrene [B(α)P] induced lung cancer in A/J mice. Light microscopic examination of lung sections of [B(α)P] induced lung cancer mice revealed the presence of adenocarcinoma characterized by extensive proliferation of alveolar epithelium and loss of alveolar spaces. The control lung tissue showed a normal architecture with clear alveolar spaces. Interestingly the indirubin-3-monoxime treated groups showed the reduced adenocarcinoma with appearance of alveolar spaces. Transmission Electron Microscopic (TEM) studies of lung sections of [B(α)P] induced lung cancer mice showed the presence of phaemorphic cells with dense granules and increased mitochondria. The lung sections of mice treated with indirubin-3-monoxime showed the presence of shrunken, fragmented, and condensed nuclei implying apoptosis. The effects were dose dependent and prominent in 10 mg/kg/5 d/week groups suggesting the therapeutic role of indirubin analogue against this deadly human malignancy. Here, our results indicate that indirubin-3-monoxime brings antitumor effect against [B(α)P] induced lung cancer by its apoptotic action in A/J mice.

Protective effects of TRH and its analogues against various cytotoxic agents in retinoic acid (RA)-differentiated human neuroblastoma SH-SY5Y cells

TRH (thyroliberin) and its analogues were reported to possess neuroprotective effects in cellular and animal experimental models of acute and chronic neurodegenerative diseases. In the present study we evaluated effects of TRH and its three stable analogues, montirelin (CG-3703), RGH-2202 and Z-TRH (N-(carbobenzyloxy)-pGlutamyl-Histydyl-Proline) on the neuronally differentiated human neuroblastoma SH-SY5Y cell line, which is widely accepted for studying potential neuroprotectants. We found that TRH and all the tested analogues at concentrations 0.1-50 μM attenuated cell damage induced by MPP(+) (2 mM), 3-nitropropionate (10 mM), hydrogen peroxide (0.5 mM), homocysteine (250 μM) and beta-amyloid (20μM) in retinoic acid differentiated SH-SY5Y cells. Furthermore, we demonstrated that TRH and its analogues decreased the staurosporine (0.5 μM)-induced LDH release, caspase-3 activity and DNA fragmentation, which indicate the anti-apoptotic proprieties of these peptides. The neuroprotective effects of TRH (10 μM) and RGH-2202 (10 μM) on St-induced cell death was attenuated by inhibitors of PI3-K pathway (wortmannin and LY294002), but not MAPK/ERK1/2 (PD98059 and U0126). Moreover, TRH and its analogues at neuroprotective concentrations (1 and 10 μM) increased expression of Bcl-2 protein, as confirmed by Western blot analysis. All in all, these results extend data on neuroprotective properties of TRH and its analogues and provide evidence that mechanism of anti-apoptotic effects of these peptides in SH-SY5Y cell line involves induction of PI3K/Akt pathway and Bcl-2. Furthermore, the data obtained on human cell line with a dopaminergic phenotype suggest potential utility of TRH and its analogues in the treatment of some neurodegenerative diseases including Parkinson's disease.

Indirubin-3'-oxime inhibits inflammatory activation of rat brain microglia

Microglial cells play critical roles in the immune and inflammatory responses of the brain. Under pathological conditions, the activation of microglia helps to restore brain homeostasis. However, chronic microglial activation endangers neuronal survival through the release of various proinflammatory and neurotoxic factors. As such, regulators of microglial activation have been considered as potential therapeutic candidates to reduce the risk of neurodegeneration associated with neurodegenerative diseases, including Alzheimer's and, Parkinson's diseases. Indirubin-3'-oxime, a potent inhibitor of cyclin-dependent kinases and glycogen synthase kinase-3β, has been shown to have neuroprotective potential. The specific aim of this study was to examine the efficacy of indirubin-3'-oxime in the repression of microglial activation. Indirubin-3'-oxime was shown to effectively inhibit lipopolysaccharide (LPS)-induced nitric oxide release from cultured rat brain microglia. This compound reduced the LPS-stimulated productions of tumor necrosis factor-α, interleukin-1β, prostaglandin E(2), and intracellular reactive oxygen species and also effectively reduced LPS-elicited NF-κB activation. In organotypic hippocampal slice cultures, indirubin-3'-oxime blocked LPS-related hippocampal cell death. These results suggest that indirubin-3'-oxime provides neuroprotection by reducing the productions of various neurotoxic molecules in activated microglia.

Targeting mitochondrial dysfunction in neurodegenerative disease: Part II

IMPORTANCE OF THE FIELD

With improvements in life expectancy over the past decades, the incidence of neurodegenerative disease has dramatically increased and new therapeutic strategies are urgently needed. One possible approach is to target mitochondrial dysfunction, which has been implicated in the pathogenesis of numerous neurodegenerative disorders.

AREAS COVERED IN THIS REVIEW

This review examines the role of mitochondrial dysfunction in neurodegeneration, drawing examples from common diseases such as Alzheimer's disease and rarer familial disorders such as Charcot-Marie-Tooth. The review is provided in two parts. In part I we discussed the mitochondrial defects which have been most extensively researched (oxidative stress, bioenergetic dysfunction, calcium mishandling). We focus now on those defects which have more recently been implicated in neurodegeneration; in mitochondrial fusion/fission, protein import, protein quality control, kinase signalling and opening of the permeability transition pore.

WHAT THE READER WILL GAIN

An examination of mitochondrial defects observed in neurodegeneration, and existing and possible future therapies to target these defects.

TAKE HOME MESSAGE

The mitochondrially-targeted therapeutics that have reached clinical trials so far have produced encouraging but largely inconclusive results. Increasing understanding of mitochondrial dysfunction has, however, led to preclinical work focusing on novel approaches, which has generated exciting preliminary data.