Lithium enhances TRAIL-induced apoptosis in human lung carcinoma A549 cells

Targeting CaN/NFAT in Alzheimer's brain degeneration

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive functions. While the exact causes of this debilitating disorder remain elusive, numerous investigations have characterized its two core pathologies: the presence of β-amyloid plaques and tau tangles. Additionally, multiple studies of postmortem brain tissue, as well as results from AD preclinical models, have consistently demonstrated the presence of a sustained inflammatory response. As the persistent immune response is associated with neurodegeneration, it became clear that it may also exacerbate other AD pathologies, providing a link between the initial deposition of β-amyloid plaques and the later development of neurofibrillary tangles. Initially discovered in T cells, the nuclear factor of activated T-cells (NFAT) is one of the main transcription factors driving the expression of inflammatory genes and thus regulating immune responses. NFAT-dependent production of inflammatory mediators is controlled by Ca2+-dependent protein phosphatase calcineurin (CaN), which dephosphorylates NFAT and promotes its transcriptional activity. A substantial body of evidence has demonstrated that aberrant CaN/NFAT signaling is linked to several pathologies observed in AD, including neuronal apoptosis, synaptic deficits, and glia activation. In view of this, the role of NFAT isoforms in AD has been linked to disease progression at different stages, some of which are paralleled to diminished cognitive status. The use of classical inhibitors of CaN/NFAT signaling, such as tacrolimus or cyclosporine, or adeno-associated viruses to specifically inhibit astrocytic NFAT activation, has alleviated some symptoms of AD by diminishing β-amyloid neurotoxicity and neuroinflammation. In this article, we discuss the recent findings related to the contribution of CaN/NFAT signaling to the progression of AD and highlight the possible benefits of targeting this pathway in AD treatment.

Lithium in Cancer Therapy: Friend or Foe?

Lithium, a trace element important for fetal health and development, is considered a metal drug with a well-established clinical regime, economical production process, and a mature storage system. Several studies have shown that lithium affects tumor development by regulating inositol monophosphate (IMPase) and glycogen synthase kinase-3 (GSK-3). Lithium can also promote proliferation and programmed cell death (PCD) in tumor cells through a number of new targets, such as the nuclear receptor NR4A1 and Hedgehog-Gli. Lithium may increase cancer treatment efficacy while reducing side effects, suggesting that it can be used as an adjunctive therapy. In this review, we summarize the effects of lithium on tumor progression and discuss the underlying mechanisms. Additionally, we discuss lithium's limitations in antitumor clinical applications, including its narrow therapeutic window and potential pro-cancer effects on the tumor immune system.

LiCl induces apoptosis via CHOP/NOXA/Mcl-1 axis in human choroidal melanoma cells

Background

Choroidal melanoma is the most common primary intraocular malignancy that occurs in adults. Lithium Chloride Promotes Apoptosis in Human Leukemia NB4 Cells by Inhibiting Glycogen Synthase Kinase-3 Beta. In this study, we aimed to understand whether LiCl exerts anticancer effects on choroidal melanoma cells and elucidate the underlying molecular mechanisms.

Methods

Human choroidal melanoma cells were treated with LiCl, and cell survival was assessed with MTT assays. Cell reproductive viability was measured by plate colony formation assays. Cell apoptosis was evaluated using flow cytometry, and proteins were detected using western blotting. A human choroidal melanoma xenograft model was established to demonstrate the effect of LiCl on human choroidal melanoma in vivo.

Results

We found that LiCl inhibited cell survival and clonogenic potential and induced apoptosis in human choroidal melanoma cells. LiCl also reduced the proliferation of choroidal melanoma cells in vivo. Moreover, the upregulation of NOXA and downregulation of Mcl-1 were responsible for LiCl-induced apoptosis. Mcl-1 overexpression obviously impaired LiCl-induced apoptosis and cleavage of caspase8, caspase9, caspase3 and PARP. Moreover, the protein expression of endoplasmic reticulum stress markers, including IRE1α, Bip, p-eIF2α, ATF4 and CHOP, were upregulated following treatment with LiCl. When CHOP expression was knocked down and cells were treated with LiCl, the protein level of NOXA was partially increased, and Mcl-1 expression was increased, while the cleavage of caspase8, caspase9, caspase3 and PARP that was induced by the LiCl was reduced compared with the vehicle treated group. Prolonged ER stress results in the activation of the apoptotic pathway.

Conclusions

In summary, LiCl induced an endoplasmic reticulum stress response while activating intrinsic apoptosis. Furthermore, the CHOP/NOXA/Mcl-1 axis contributed to LiCl-induced apoptosis both in vitro and in vivo. The present study provides important mechanistic insight into potential cancer treatments involving LiCl and enhances the understanding of human choroidal melanoma.

Pchaeglobolactone A, Spiropchaeglobosin A, and Pchaeglobosals A and B: Four Rearranged Cytochalasans from Chaetomium globosum P2-2-2

Four novel rearranged cytochalasans (1-4) were isolated from an endophytic fungus Chaetomium globosum P2-2-2. Pchaeglobolactone A (1) possessed an unprecedented 13-aza-21-oxa-tetracyclo-[10.6.1.2^17,19.0^15,19]henicosane core. Spiropchaeglobosin A (2) was the first example of cytochalasans featuring a novel spiro[5.10]hexadecane unit. Pchaeglobosals A (3) and B (4) featured a unique 5/5/13 fused tricyclic ring system. Compounds 1-4 were tested for their antiproliferative, apoptosis, cell cycle arrest, and TRAIL-resistance-overcoming activities on cancer cell lines.

Cytochalasins from an endophytic fungus Phoma multirostrata XJ-2-1 with cell cycle arrest and TRAIL-resistance-overcoming activities

Nine new (1-9) and four known (10-13) [13]cytochalasins, along with three known 24-oxa[14]cytochalasins (14-16), were isolated from the culture of Phoma multirostrata XJ-2-1, an endophytic fungus obtained from the fibrous root of Parasenecio albus. Their structures were elucidated by interpretation of the nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS). The absolute configurations were assigned by single-crystal X-ray crystallography, modified Mosher's method, and by analysis of their experimental electronic circular dichroism (ECD) spectra. Compound 6 could induce cell cycle arrest at G2-phase in CT26 and A549 cells, and displayed moderate cytotoxicity against CT26 and A549 cell lines with IC₅₀ values of 6.03 and 5.04 μM, respectively. Co-treatment of 7-9, 13 and 16 with tumor necrosis factor related apoptosis inducing ligand (TRAIL) could significantly decrease the cell viability of A549, which revealed that cytochalasins could possibly be a new group of TRAIL sensitizers in lung cancer therapy.

DR5 related autophagy can promote apoptosis in gliomas after irradiation

As a cancer treatment strategy, irradiation therapy is widely used that can cause DNA breakage and increase free radicals, which leads to different types of cell death. Among them, apoptosis and autophagy are the most important and the most studied cell death processes. Although the exploration of the relationship between apoptosis and autophagy has been a major area of focus, still the molecular mechanisms of autophagy on apoptosis remain unclear. Here, we have revealed that apoptosis was enhanced by the death receptor 5 (DR5) pathway, and the effect of autophagy on apoptosis was promoted by DR5 interacting with LC3B as well as Caspase8 in gliomas after irradiation. Interestingly, we observed that the addition of four different autophagy inducers, rapamycin (RAP), CCI779, ABT737 and temozolomide (TMZ), induced the differences of DR5 expression and cell apoptosis after irradiation. Unlike RAP and CCI779, ABT737 and TMZ were able to increase DR5 expression and further induce cell death. Therefore, we have concluded that DR5 plays a novel and indispensable role in promoting cell apoptosis under irradiation and suggest a potential therapeutic approach for glioblastoma treatment.

Lithium targeting of AMPK protects against cisplatin-induced acute kidney injury by enhancing autophagy in renal proximal tubular epithelial cells

Autophagy has been demonstrated to be vital for kidney homeostasis and is centrally implicated in the pathogenesis of cisplatin-induced acute kidney injury (AKI). Lithium is a potent autophagy inducer in a number of cell types. However, it remains uncertain whether its autophagic activity is associated with a beneficial effect on renal tubular cells in AKI. This study aimed to examine the effect of lithium on renal autophagy in cisplatin-induced AKI. Mice or renal proximal tubular epithelial cells in culture were exposed to cisplatin-induced acute injury in the presence or absence of lithium treatment. AKI or tubular cell injury was evaluated, and cell signaling associated with autophagy was examined. Lithium pretreatment prominently ameliorated acute renal tubular damage in mice exposed to cisplatin insult, associated with enhanced autophagy in renal tubules, as assessed by measuring microtubule-associated protein 1A/1B-light chain 3 (LC3)BII/I expression and autophagosome formation. Consistently, in cisplatin-injured renal tubular cells in vitro, lithium enhanced autophagic activities, improved cell viability, and attenuated cell death. Mechanistically, lithium triggered AMPK-α phosphorylation and activation, which in turn positively correlated with the induced expression of autophagy-related molecules, like mammalian target of rapamycin and LC3BII/I. AMPK-α activation is likely required for lithium-induced tubular cell autophagy and protection in cisplatin-induced AKI because blockade of AMPK-α phosphorylation by compound C markedly abrogated lithium-induced autophagosome formation and mitigated the protective effect of lithium on AKI. Our findings suggest that lithium represents a promising therapeutic strategy for protecting renal tubular cells against cisplatin-induced AKI by enhancing autophagy via AMPK-α activation.-Bao, H., Zhang, Q., Liu, X., Song, Y., Li, X., Wang, Z., Li, C., Peng, A., Gong, R. Lithium targeting of AMPK protects against cisplatin-induced acute kidney injury by enhancing autophagy in renal proximal tubular epithelial cells.

Quercetin enhances the antitumor activity of trichostatin A through up-regulation of p300 protein expression in p53 null cancer cells

In the present study, we investigated the p53-independent mechanism by which quercetin (Q) increased apoptosis in human lung cancer H1299 cells exposed to trichostatin A (TSA), a histone deacetylase inhibitor. We also investigated the role of Q in increasing the acetylation of histones H3 and H4 and the possible mechanism. Q at 5 μM significantly increased apoptosis by 88% in H1299 cells induced by TSA at 72 h. Q also significantly increased TSA-induced death receptor 5 (DR5) mRNA and protein expression as well as caspase-10/3 activities in H1299 cells. Transfection of DR5 siRNA into H1299 cells significantly diminished the enhancing effects of Q on TSA-induced apoptosis. Furthermore, TSA in combination with Q rather than TSA alone significantly increased p300 expression. Transfection of p300 siRNA in H1299 cells significantly diminished the increase of histone H3/H4 acetylation, DR5 protein expression, caspase-10/3 activity and apoptosis induced by Q. In addition, similar effects of Q were observed when Q was combined with vorinostat, another FDA-approved histone deacetylase inhibitor. These data suggest that the up-regulation of p300 expression, which in turn increases histone acetylation and DR5 expression, plays an important role in the enhancing effect of Q on TSA/vorinostat- induced apoptosis in H1299 cells.

Lithium: Immunomodulatory and Anti-Infectious Activities

Lithium (Li), a well-known immunomodulatory agent, has been in use for the treatment of several infectious diseases. Li mainly acts through GSK3β inactivation and several other signalling pathways, which are directly involved in the activation of innate immune system. Li therapy has been shown to cause effective modulation of various inflammatory cytokines, and has also been shown to boost immunity in several disease models. Apart from treatment for mania, Li has also been proved to be effective against infections caused by viruses, bacteria, parasites, and certain life-style disorders. Its effects, ranging from common defensive capabilities to complex pathways for protection of human body, make Li extraordinary. Thus, Li is an absolute requirement that can be a solution for some of the immune related disorders. This review mainly focuses on pharmacology, immune reactions of different cell types, and anti-infectious activities of Li.

β-catenin decreases acquired TRAIL resistance in non-small-cell lung cancer cells by regulating the redistribution of death receptors

Tumor necrosis factor‑related apoptosis‑inducing ligand (TRAIL) exhibits antitumor activity in various types of tumor cell and tumor‑bearing animals. However, acquired TRAIL resistance is a common issue that restricts its clinical application. Previous studies have revealed that β‑catenin is associated with TRAIL resistance in melanoma and colorectal tumors. In the present study, an acquired‑resistance non‑small‑cell lung cancer (NSCLC) cell line (H460‑TR) was established from parental TRAIL‑sensitive H460 cells using a gradient ascent model (8‑256 ng/ml TRAIL). Cellular FADD‑like interleukin‑1β converting enzyme inhibitory protein and Mcl‑1 were upregulated and the cell surface distribution of death receptor (DR)4 and DR5 was downregulated in H460‑TR cells compared with the parental H460 cells. The results of reverse transcription‑quantitative polymerase chain reaction and western blot analysis indicated that H460 cells expressed increased levels of β‑catenin and were more sensitive to TRAIL compared with H460‑TR cells. β‑catenin‑knockdown in H460 cells decreased their sensitivity to TRAIL, while upregulation of β‑catenin expression in H460‑TR cells increased their sensitivity to TRAIL, increased the cell surface distribution of DRs and activated caspase‑3/8. Taken together, the results of the present study suggest that β‑catenin impairs acquired TRAIL resistance in NSCLC cells by promoting the redistribution of DR4 and DR5 to the cytomembrane, and inducing TRAIL‑mediated cell apoptosis via caspase‑3/8 activation.

Lithium chloride attenuates mitomycin C induced necrotic cell death in MDA-MB-231 breast cancer cells via HMGB1 and Bax signaling

The clinical use of potent anticancer drug mitomycin C (MMC) has limited due to side effects and resistance of cancer cells. The aim of this study was to investigate whether lithium chloride (LiCl), as a mood stabilizer, can affect the sensitivity of MDA-MB-231 breast cancer cells to mitomycin C. The cells were exposed to various concentrations of mitomycin C alone and combined with LiCl and the viability determined by trypan blue and MTT assays. Proteins were analyzed by western blot and mRNA expression of HMGB1 MMP9 and Bcl-2 were analyzed by RT-PCR. Flow cytometry was used to determine the cell cycle arrest and percent of apoptotic and necrotic cells. Concentration of Bax assessed by ELISA. Exposure of the cells to mitomycin C revealed IC₅₀ value of 20 μM, whereas pretreatment of the cells with LiCl induced synergistic cytotoxicity and IC₅₀ value declined to 5 μM. LiCl combined with mitomycin C significantly down-regulated HMGB1, MMP9 and Bcl-2 gene expression but significantly increased the level of Bax protein. In addition, the content of HMGB1 in the nuclei decreased and pretreatment with LiCl reduced the content of HMGB1 release induced by MMC. LiCl increased mitomycin C-induced cell shrinkage and PARP fragmentation suggesting induction of apoptosis in these cells. LiCl prevented mitomycin C-induced necrosis and changed the cell death arrest at G2/M-phase. Taking all together, it is suggested that LiCl efficiently enhances mitomycin C-induced apoptosis and HMGB1, Bax and Bcl-2 expression may play a major role in this process, the findings that provide a new therapeutic strategy for LiCl in combination with mitomycin C.

The combination of TRAIL and MG-132 induces apoptosis in both TRAIL-sensitive and TRAIL-resistant human follicular lymphoma cells

We have previously shown that the human follicular lymphoma cell line, HF28GFP, is sensitive to TRAIL-mediated apoptosis. Nevertheless, when the same cells overexpress anti-apoptotic Bcl-2 family protein, Bcl-xL (HF28Bcl-xL), they become resistant to TRAIL. Thus, these cell lines help us to investigate the action of novel apoptosis inducing candidate drugs. In the present study, we examined the effects of MG-132 (a proteasome inhibitor), LiCl (a glycogen synthase kinase-3 inhibitor) and/or TRAIL on pro-apoptotic Bcl-2 family proteins such as Bim and Bid. Here we demonstrate that the combination of MG-132 and TRAIL induced significant apoptotic cell death in both cell lines, HF28GFP and HF28BclxL. Apoptosis correlated with a decrease of phospho-ERK1/2, the accumulation of Bim and translocation of truncated Bid (tBid) and jBid. In addition, the combination of MG-132 and TRAIL seemed to target other apoptotic factors, which led to the accumulation of active capsase-3. Furthermore, co-stimulation of LiCl and TRAIL induced apoptosis in HF28GFP cells. However, HF28Bcl-xL cells were far less sensitive to the combinatorial effects of LiCl and TRAIL. Interestingly, we observed that LiCl did not target Bim and Bid proteins. In conclusion, these data show that targeting of pro-apoptotic Bcl-2 family proteins simultaneously through a selective proteasome inhibition might help to overcome TRAIL resistance caused by overexpression of anti-apoptotic Bcl-2 family proteins. Moreover, the data may provide new strategies to develop targeted therapies against lymphomas.

Improved detection of synthetic lethal interactions in Drosophila cells using variable dose analysis (VDA)

Synthetic sick or synthetic lethal (SS/L) screens are a powerful way to identify candidate drug targets to specifically kill tumor cells, but this approach generally suffers from low consistency between screens. We found that many SS/L interactions involve essential genes and are therefore detectable within a limited range of knockdown efficiency. Such interactions are often missed by overly efficient RNAi reagents. We therefore developed an assay that measures viability over a range of knockdown efficiency within a cell population. This method, called Variable Dose Analysis (VDA), is highly sensitive to viability phenotypes and reproducibly detects SS/L interactions. We applied the VDA method to search for SS/L interactions with TSC1 and TSC2, the two tumor suppressors underlying tuberous sclerosis complex (TSC), and generated a SS/L network for TSC. Using this network, we identified four Food and Drug Administration-approved drugs that selectively affect viability of TSC-deficient cells, representing promising candidates for repurposing to treat TSC-related tumors.

DKK1 promotes migration and invasion of non-small cell lung cancer via β-catenin signaling pathway

Disregulation of dickkopf-related protein 1 (DKK1) has been reported in a variety of human cancers. However, how DKK1 functions in Non-small cell lung cancer has not been revealed. In the current study, DKK1 was knocked out by the lentivirus-mediated short hairpin RNA interference approach in H1299 and 95C non-small cell lung cancer cell lines. Subsequently, the migration and invasion ability were assessed by wound-healing and transwell assays. In addition, epithelial-mesenchymal transition markers and β-catenin were examined by Western blot analysis. The signaling pathway downstream of DKK1 was characterized using the Wnt signaling pathway inhibitor, IWP2, and glycogen synthase kinase 3 beta inhibitor, LiCl. Immunofluorescence analysis investigated the subcellular localization of β-catenin. The results suggested that knockdown of DKK1 caused reduced migration and invasion ability of H1299 and 95C cells. DKK1 silencing resulted in the downregulation of epithelial-mesenchymal transition-related proteins, such as Snail and zinc finger E-box binding homeobox 1. Besides, DKK1 silencing inhibited β-catenin and promoted the phosphorylation of β-catenin. Mechanism results indicated that the expression of β-catenin was reduced in H1299 or 95C cells after being treated with Wnt signaling inhibitor, IWP2. In addition, the inhibition of β-catenin phosphorylation by glycogen synthase kinase 3 beta inhibitor, LiCl, significantly enhanced the migration and invasion capacities in DKK1-knockdown cell lines. Furthermore, cell immunofluorescence revealed that nuclear β-catenin was reduced when DKK1 was knocked down. Taken together, these findings suggest that DKK1 induces the occurrence of epithelial-mesenchymal transition and promotes migration and invasion in non-small cell lung cancer cells. Mechanically, β-catenin plays a vital role in DKK1-induced non-small cell lung cancer cell migration and invasion, and DKK1 inhibits the phosphorylation of β-catenin, resulting in the increased nuclear localization of β-catenin.

From direct to indirect lithium targets: a comprehensive review of omics data

Metal ions are critical to a wide range of biological processes.

Carthorquinosides A and B, Quinochalcone C-Glycosides with Diverse Dimeric Skeletons from Carthamus tinctorius

Two novel quinochalcone C-glycosides, carthorquinosides A (1) and B (2), were isolated from the florets of Carthamus tinctorius. Their structures, including the absolute configurations, were established by analysis of NMR and MS data, together with chemical degradation and electronic circular dichroism spectra. Compound 1 has an unprecedented quinochalcone-flavonol structure linked via a methylene bridge, and compound 2 comprises two glucopyranosylquinochalcone moieties linked via the formyl carbon of an acyclic glucosyl unit. A potential biosynthesis pathway is also proposed. Compounds 1 and 2 exhibited anti-inflammatory activities in LPS-stimulated HUVEC cells by regulating IL-1, IL-6, IL-10, and IFN-γ mRNA expression at concentrations as low as 4 μM, and compound 2 also showed inhibitory activity against topoisomerase I at100 μM.

Propolis extracts from the northern region of Thailand suppress cancer cell growth through induction of apoptosis pathways

The continual increase in mortality rates and number of cancer cases is a matter of serious concern in developing countries. The incorporation of natural products into classical cancer treatment approaches is a promising direction. The mechanisms of A549 and HeLa cancer cell death induction by ethanolic extracts of propolis samples from Phayao, Chiang Mai, and Nan provinces in northern Thailand were investigated in this study. The propolis extract from Chiang Mai showed the highest antioxidant activity and the greatest total phenolic content. The propolis extract from Nan also exhibited the highest total flavonoid content. The proliferation of A549 and HeLa cells grown in the presence of the propolis extracts was suppressed in a dose- and time-dependent manner. Moreover, treatment of both cancer cells with the propolis extracts showed DNA fragmentation and significantly increased the number of the apoptotic cells. On A549 cells, the extrinsic and intrinsic pathways of caspase enzymes were activated by the propolis extracts from Phayao and Chiang Mai. In the case of the propolis extract from Nan, the mechanisms involved apoptosis on the A549 cells were caspase-independent pathway. The extrinsic pathway of the caspase enzyme was triggered by all of the propolis extracts on HeLa cells. Finally, oral administration of the propolis granule produced from the propolis extract from Nan resulted in extended survival of tumour-bearing mice. Therefore, propolis extracts from the northern region of Thailand demonstrated pharmacological properties, both antioxidant and anticancer activities. From these findings, it is evident that propolis extracts can be considered as a naturally obtained agent extremely useful in cancer treatment.

Schedule-dependent cytotoxicity of sunitinib and TRAIL in human non-small cell lung cancer cells with or without EGFR and KRAS mutations

ABSTACT

BACKGROUND

Non-small cell lung cancer (NSCLC) patients who do initially respond to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) may eventually develop resistance, which may at least partly be due to the acquisition of a secondary EGFR mutation (T790M). Additionally, it has been found that KRAS mutations may serve as poor prognostic biomarkers. Here, we aimed at establishing a suitable treatment regimen for the multi-target TKI sunitinib and the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) in NSCLC-derived cells with or without EGFR and KRAS mutations.

METHODS

Four NSCLC-derived cell lines with or without EGFR and KRAS mutations were exposed to different sunitinib and TRAIL treatment regimens. Alterations in cell viability, cell cycle distribution, apoptosis, phosphorylation of AKT and expression of the death receptors DR4 and DR5 were evaluated using CCK8, flow cytometry and Western blotting assays, respectively.

RESULTS

A synergistic cytotoxic effect was observed in all four cell lines treated with sunitinib (1 nM) followed by TRAIL (100 ng/ml), as well as after simultaneous treatment with both agents. We found that sunitinib enhances TRAIL-induced G0/G1-phase cell cycle arrest and blocks TRAIL-triggered activation of AKT as the underlying mechanism. In contrast, we observed antagonistic effects when sunitinib was administered after TRAIL to the cell lines tested. A decreased DR4 and DR5 expression was found to be correlated with this antagonism.

CONCLUSION

From our data we conclude that administration of sunitinib followed by TRAIL, as well as a simultaneous administration of both agents, serve as favorable treatment regimens for NSCLC-derived cells, irrespective of their EGFR and/or KRAS mutation status.

MK-2206 induces cell cycle arrest and apoptosis in HepG2 cells and sensitizes TRAIL-mediated cell death

It has become evident that AKT inhibitors have great potential in cancer treatment. In this study, we investigate the anticancer activity of MK-2206, a novel AKT inhibitor, on HepG2 hepatocellular carcinoma cell, and to show whether MK-2206 enhances the apoptosis-inducing potential of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). The cell growth inhibition was evaluated by MTT assay and colony formation assay. Cell cycle distribution was assessed by propidium iodide flow cytometry. Apoptosis was determined by AnnexinV-FITC/PI double staining assay and caspase-9, casapse-7, caspase-3, and PARP cleavage. The results of present study showed that MK-2206-induced G1-phase arrest was associated with a marked decrease in the protein expression of cyclin D1 with concomitant induction of p21 and p27. MK-2206-induced apoptosis was characterized by cleavage of a pro-caspase in a concentration-dependent manner. Moreover, the MAP family kinases p38 kinase and JNK were activated by exposure to MK-2206. SB203580, an p38-specific inhibitor, partially blocked MK-2206-induced death of HepG2 cells and caspase activation. A combination of MK-2206 with TRAIL significantly inhibited growth of TRAIL resistant HepG2 cells. Taken together, our findings provide a new insight to better understand anticancer mechanisms of MK-2206, at least in HepG2 cell. Using of MK-2206 as a potent sensitizer to TRAIL-induced apoptotic cell death offers a promising means of enhancing the efficacy of TRAIL-based HCC treatments.

Effect of Embelin on TRAIL receptor 2 mAb-induced apoptosis of TRAIL-resistant A549 non-small cell lung cancer cells

INTRODUCTION

Some non-small cell lung cancer (NSCLC) tumor cells are insensitive to tumor necrosis factor- related apoptosis-inducing ligand (TRAIL) -based therapy. This study was conducted to examine the effect of embelin on the sensitivity of the A549 NSCLC cell line to TRAIL receptor2 (TRAILR2) monoclonal antibodies and to investigate the potential mechanisms.

MATERIALS AND METHODS

A549 cells were treated with embelin, TRAILR2 mAb or a combination of both. Cell viability was measured using ATPlite assay and apoptosis rates were determined by flow cytometry with AnnexinV-FITC and propidium iodide staining, with the expression levels of proteins analyzed by Western blotting.

RESULTS

The cell survival rate of separate treatments with 100 ng/ml TRAILR2 antibody or 25 uM embelin were 81.5±1.57% and 61.7±2.84%, respectively. Their combined use markedly decreased cell viability in A549 cells to 28.1±1.97% (P<0.05). The general caspase inhibitor Z-VAD- FMK could inhibit the embelin-enhanced sensitivity of A549 cells to TRAILR2 mAb (75.97±3.17%)(P<0.05). Both flow cytometry and cell morphological analysis showed that embelin was able to increase TRAIL-induced apoptosis in A549 cells. Combined treatment with embelin and TRAILR2 mAb augmented the activation of initiator caspases and effector caspase. In addition, A549 cells showed increasing levels of TRAILR2 protein and decreasing levels of Bcl-2, survivin and c-FLIP following the treatment with embelin+TRAILR2 mAb.

CONCLUSIONS

Embelin could enhance TRAIL-induced apoptosis in A549 cells. The synergistic effect of the combination treatment might be due to modulation of multiple components in the TRAIL receptor-mediated apoptotic signaling pathway, including TRAILR2, XIAP, survivin, Bcl-2 and c-FLIP.

Concerted suppression of STAT3 and GSK3β is involved in growth inhibition of non-small cell lung cancer by Xanthatin

Xanthatin, a sesquiterpene lactone purified from Xanthium strumarium L., possesses prominent anticancer activity. We found that disruption of GSK3β activity was essential for xanthatin to exert its anticancer properties in non-small cell lung cancer (NSCLC), concurrent with preferable suppression of constitutive activation of STAT3. Interestingly, inactivation of the two signals are two mutually exclusive events in xanthatin-induced cell death. Moreover, we surprisingly found that exposure of xanthatin failed to trigger the presumable side effect of canonical Wnt/β-Catenin followed by GSK3β inactivation. We further observed that the downregulation of STAT3 was required for xanthatin to fine-tune the risk. Thus, the discovery of xanthatin, which has ability to simultaneously orchestrate two independent signaling cascades, may have important implications for screening promising drugs in cancer therapies.

Inhibition of Hedgehog signaling sensitizes NSCLC cells to standard therapies through modulation of EMT-regulating miRNAs

Background

Epidermal growth factor receptor- tyrosine kinase inhibitors (EGFR-TKIs) benefit Non-small cell lung cancer (NSCLC) patients, and an EGFR-TKIi erlotinib, is approved for patients with recurrent NSCLC. However, resistance to erlotinib is a major clinical problem. Earlier we have demonstrated the role of Hedgehog (Hh) signaling in Epithelial-to-Mesenchymal transition (EMT) of NSCLC cells, leading to increased proliferation and invasion. Here, we investigated the role of Hh signaling in erlotinib resistance of TGF-β1-induced NSCLC cells that are reminiscent of EMT cells.

Methods

Hh signaling was inhibited by specific siRNA and by GDC-0449, a small molecule antagonist of G protein coupled receptor smoothened in the Hh pathway. Not all NSCLC patients are likely to benefit from EGFR-TKIs and, therefore, cisplatin was used to further demonstrate a role of inhibition of Hh signaling in sensitization of resistant EMT cells. Specific pre- and anti-miRNA preparations were used to study the mechanistic involvement of miRNAs in drug resistance mechanism.

Results

siRNA-mediated inhibition as well as pharmacological inhibition of Hh signaling abrogated resistance of NSCLC cells to erlotinib and cisplatin. It also resulted in re-sensitization of TGF-β1-induced A549 (A549M) cells as well the mesenchymal phenotypic H1299 cells to erlotinib and cisplatin treatment with concomitant up-regulation of cancer stem cell (CSC) markers (Sox2, Nanog and EpCAM) and down-regulation of miR-200 and let-7 family miRNAs. Ectopic up-regulation of miRNAs, especially miR-200b and let-7c, significantly diminished the erlotinib resistance of A549M cells. Inhibition of Hh signaling by GDC-0449 in EMT cells resulted in the attenuation of CSC markers and up-regulation of miR-200b and let-7c, leading to sensitization of EMT cells to drug treatment, thus, confirming a connection between Hh signaling, miRNAs and drug resistance.

Conclusions

We demonstrate that Hh pathway, through EMT-induction, leads to reduced sensitivity to EGFR-TKIs in NSCLCs. Therefore, targeting Hh pathway may lead to the reversal of EMT phenotype and improve the therapeutic efficacy of EGFR-TKIs in NSCLC patients.

Lithium attenuates IFN-β production and antiviral response via inhibition of TANK-binding kinase 1 kinase activity

Lithium salt is a widely used glycogen synthase kinase-3β inhibitor and effective drug for the treatment of psychiatric diseases. However, the effects of lithium in innate immune responses, especially in cellular antiviral responses, are unknown. In this study, we show that lithium chloride attenuates LPS-, polyinosinic-polycytidylic acid-, and Sendai virus-induced IFN-β production and IFN regulatory factor 3 activation in macrophages in a glycogen synthase kinase-3β-independent manner. The ability of the lithium to inhibit IFN-β production was confirmed in vivo, as mice treated with lithium chloride exhibited decreased levels of IFN-β upon Sendai virus infection. In vitro kinase assay demonstrates that lithium suppresses TANK-binding kinase 1 kinase activity. Consistently, lithium significantly enhanced the replication of vesicular stomatitis virus in vitro and in vivo. Severe infiltration of monocytes and tissue damage were observed in the lungs of control mice, compared with lithium-treated mice after virus infection. Our findings suggest lithium as an inhibitor of TANK-binding kinase 1 and potential target for the intervention of diseases with uncontrolled IFN-β production. Furthermore, lithium attenuates host defense to virus infection and may cause severely adverse effects in clinical applications.