V8, a newly synthetic flavonoid, induces apoptosis through ROS-mediated ER stress pathway in hepatocellular carcinoma

A new insight into fluoride induces cardiotoxicity in chickens: Involving the regulation of PERK/IRE1/ATF6 pathway and heat shock proteins

Fluorosis poses a significant threat to human and animal health and is an urgent public safety concern in various countries. Subchronic exposure to fluoride has the potential to result in pathological damage to the heart, but its potential mechanism requires further investigation. This study investigated the effects of long-term exposure to sodium fluoride (0, 500, 1000, and 2000 mg/kg) on the hearts of chickens were investigated. The results showed that an elevated exposure dose of sodium fluoride led to congested cardiac tissue and disrupted myofiber organisation. Sodium fluoride exposure activated the ERS pathways of PERK, IRE1, and ATF6, increasing HSP60 and HSP70 and decreasing HSP90. The NF-κB pathway and the activation of TNF-α and iNOS elicited an inflammatory response. BAX, cytc, and cleaved-caspase3 were increased, triggering apoptosis and leading to cardiac injury. The abnormal expression of HSP90 and HSP70 affected the stability and function of RIPK1, RIPK3, and MLKL, which are crucial necroptosis markers. HSPs inhibited TNF-α-mediated necroptosis and apoptosis of the death receptor pathway. Sodium fluoride resulted in heart injury in chickens because of the ERS and variations in HSPs, inducing inflammation and apoptosis. Cardiac-adapted HSPs impeded the activation of necroptosis. This paper may provide a reference for examining the potential cardiotoxic effects of sodium fluoride.

Fisetin, an Anti-Inflammatory Agent, Overcomes Radioresistance by Activating the PERK-ATF4-CHOP Axis in Liver Cancer

Fisetin, a well-known plant flavonol from the natural flavonoid group, is found in traditional medicines, plants, vegetables, and fruits. Fisetin also has anti-oxidant, anti-inflammatory, and anti-tumor effects. This study investigated the anti-inflammatory effects of fisetin in LPS-induced Raw264.7 cells and found that fisetin reduced the LPS-induced production of pro-inflammation markers, such as TNF-α, IL-1β, and IL-6, demonstrating the anti-inflammatory effects of fisetin. Furthermore, this study investigated the anti-cancer effects of fisetin and found that fisetin induced apoptotic cell death and ER stress through intracellular calcium (Ca²⁺) release, the PERK-ATF4-CHOP signaling pathway, and induction of GRP78 exosomes. However, the suppression of PERK and CHOP inhibited the fisetin-induced cell death and ER stress. Interestingly, fisetin induced apoptotic cell death and ER stress and inhibited the epithelial-mesenchymal transition phenomenon under radiation in radiation-resistant liver cancer cells. These findings indicate that the fisetin-induced ER stress can overcome radioresistance and induce cell death in liver cancer cells following radiation. Therefore, the anti-inflammatory agent fisetin, in combination with radiation, may be a powerful immunotherapy strategy to overcome resistance in an inflammatory tumor microenvironment.

Endoplasmic reticulum stress in liver diseases

The endoplasmic reticulum (ER) is an intracellular organelle that fosters the correct folding of linear polypeptides and proteins, a process tightly governed by the ER-resident enzymes and chaperones. Failure to shape the proper 3-dimensional architecture of proteins culminates in the accumulation of misfolded or unfolded proteins within the ER, disturbs ER homeostasis, and leads to canonically defined ER stress. Recent studies have elucidated that cellular perturbations, such as lipotoxicity, can also lead to ER stress. In response to ER stress, the unfolded protein response (UPR) is activated to reestablish ER homeostasis ("adaptive UPR"), or, conversely, to provoke cell death when ER stress is overwhelmed and sustained ("maladaptive UPR"). It is well documented that ER stress contributes to the onset and progression of multiple hepatic pathologies including NAFLD, alcohol-associated liver disease, viral hepatitis, liver ischemia, drug toxicity, and liver cancers. Here, we review key studies dealing with the emerging role of ER stress and the UPR in the pathophysiology of liver diseases from cellular, murine, and human models. Specifically, we will summarize current available knowledge on pharmacological and non-pharmacological interventions that may be used to target maladaptive UPR for the treatment of nonmalignant liver diseases.

1, 8-cineole protects against ISO-induced heart failure by inhibiting oxidative stress and ER stress in vitro and in vivo

Sugemule-3 is widely adopted in clinical practice to manage cardio-cerebral diseases. 1, 8-cineole is the main ingredient of Sugemule-3, however, the underlying cellular mechanisms for its protective effect are poorly understood. 1, 8-cineole improved the survival of H9C2 cardiomyocytes during isoproterenol (ISO) injury and reduced ISO-induced apoptosis. Compared to the ISO group, 1, 8-cineole highly attenuated the generation of ISO-induced reactive oxygen species (ROS), the depolarization of △ψm, suppression of the Bax/Bcl-2 ratio, and p-caspase 3 expression, in vitro. Furthermore, 1, 8-cineole treatment in H9C2 cardiomyocytes lowered the expressions of 78-kDa glucose-regulated protein (GRP78), p-protein kinase-like ER kinase (PERK), activation of transcription factor (ATF) 4, and ER stress effector protein C/EBP and homologous protein (CHOP). These findings implied that 1, 8-cineole contribute to cardioprotection via the GRP78/CHOP pathways. Using animal models, 1, 8-cineole was revealed to markedly alleviate ISO-induced heart injury, and reduce cardiac hypertrophy, formation of the cytoplasmic vacuole, loss of myofiber, and fibrosis by inhibiting oxidative stress and ER stress. 1, 8-cineole reduces apoptosis by inhibiting signaling pathways related to oxidative stress and ER stress. These findings implicate 1, 8-cineole as a potential therapeutic target for cardiac hypertrophy-related heart diseases, including heart failure.

Anti‑inflammatory mechanism of berberine on lipopolysaccharide‑induced IEC‑18 models based on comparative transcriptomics

Intestinal surface epithelial cells (IECs) have long been considered as an effective barrier for maintaining water and electrolyte balance, and are involved in the mechanism of nutrient absorption. When intestinal inflammation occurs, it is often accompanied by IEC malfunction. Berberine (BBR) is an isoquinoline alkaloid found in numerous types of medicinal plants, which has been clinically used in China to treat symptoms of gastrointestinal pathogenic bacterial infection, especially bacteria‑induced diarrhea and inflammation. In the present study, IEC‑18 rat intestinal epithelial cells were treated with lipopolysaccharide (LPS) to establish an in vitro model of epithelial cell inflammation, and the cells were subsequently treated with BBR in order to elucidate the anti‑inflammatory mechanism. Transcriptome data were then searched to find the differentially expressed genes (DEGs) compared between two of the treatment groups (namely, the LPS and LPS+BBR groups), and DEGs were analyzed using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Weighted Gene Correlation Network Analysis and Interactive Pathways Explorer to identify the functions and pathways enriched with DEGs. Finally, reverse transcription‑quantitative PCR was used to verify the transcriptome data. These experiments revealed that, comparing between the LPS and LPS+BBR groups, the functions and pathways enriched in DEGs were 'DNA replication', 'cell cycle', 'apoptosis', 'leukocyte migration' and the 'NF‑κB and AP‑1 pathways'. The results revealed that BBR is able to restrict DNA replication, inhibit the cell cycle and promote apoptosis. It can also inhibit the classic inflammatory pathways, such as those mediated by NF‑κB and AP‑1, and the expression of various chemokines to prevent the migration of leukocytes. According to transcriptomic data, BBR can exert its anti‑inflammatory effects by regulating a variety of cellular physiological activities, including cell cycle, apoptosis, inflammatory pathways and leukocyte migration.

Titanium dioxide nanoparticles induce endoplasmic reticulum stress-mediated apoptotic cell death in liver cancer cells

Objective

Titanium oxide (TiO₂) acts as a photosensitizer in photodynamic therapy by mediating reactive oxygen species (ROS)-induced endoplasmic reticulum (ER) stress. This study aimed to investigate the effect of TiO₂ on ER stress in liver cancer cells.

Methods

Normal human liver and human hepatocarcinoma cell lines were incubated with various concentrations of TiO₂ nanotubes for 48 hours. Cell growth, apoptosis, cell cycle, and cellular ROS were detected. Expression levels of ER stress sensors (PERK and ATF6) and Bax were evaluated by western blot. The effect of TiO₂ on liver cancer growth was also investigated in mice in vivo.

Results

TiO₂ inhibited cell growth, increased apoptosis and cellular ROS levels, and arrested the cell cycle in G1 stage in liver cancer cells. TiO₂ also increased PERK, ATF6, and Bax expression levels in liver cancer cells in dose-dependent manners. TiO₂ had no significant effect on cell growth, apoptosis, ROS level, cell cycle distribution, or PERK, ATF6, or Bax expression in normal liver cells. TiO₂ administration reduced tumor volume and increased PERK, Bax, and ATF6 expression levels in tumor tissues in vivo.

Conclusions

TiO₂ nanoparticles increased ROS-induced ER stress and activated the PERK/ATF6/Bax axis in liver cancer cells in vitro and in vivo.

Activation of endoplasmic reticulum stress and the extrinsic apoptotic pathway in human lung cancer cells by the new synthetic flavonoid, LZ-205

It has been shown that flavonoids have anti-tumor activity. In this study, LZ-205, a newly synthesized flavonoid, was found to be effective in inducing apoptosis in human lung cancer cells in vivo and in vitro. Mechanistically, LZ-205 triggers reactive oxygen species (ROS)-induced endoplasmic reticulum (ER) stress and unfolded protein response, which could be reversed by silencing CHOP, a mediator of the ER stress-associated apoptosis. In addition, LZ-205-induced apoptosis is accompanied by the activation of both the mitochondrial apoptotic and extrinsic pathways, followed by decreased mitochondrial membrane potential (ΔΨm) and the alteration of the expression of mitochondria-related pro- and anti-apoptotic proteins. LZ-205 exhibits a potential antitumor effect in BALB/c nude mice bearing H460 tumor with low systemic toxicity. In summary, both the ROS-mediated ER stress pathway and the exogenous apoptotic pathway are involved in LZ-205-induced apoptosis in vitro and in vivo. Our data show a therapeutic potential of LZ-205 for the treatment of lung cancer.

Flavonoids as detoxifying and pro-survival agents: What's new?

The role of flavonoids in the survival machinery of cells has come in the spotlight due to the recent evidence of their effect on the relationship mitochondria-ER stress-proteasome, including the intracellular mechanisms of autophagy and apoptosis. Numerous experimental animal investigations and even human clinical studies have highlighted the major role of these natural compounds in the economy of life and their deep relationship with autotrophic organisms in the evolutionary space. Their role as anti-oxidant and oxidative stress preventive molecules has to date been investigated extensively in the literature. Despite this great amount of promising evidence, many concerns, however, remain, most of which dealing with biochemistry, bioavailability, pharmacokinetics, and interaction of flavonoids with gut microbiome, issues that make difficult any good attempt to introduce these molecules in the human healthcare systems as possible, encouraging therapeutic substances. This review tries to address and elucidate these items.

TLR4-MyD88-TRAF6-TAK1 Complex-Mediated NF-κB Activation Contribute to the Anti-Inflammatory Effect of V8 in LPS-Induced Human Cervical Cancer SiHa Cells

The synthetic compound 7-4-[Bis-(2-hydroxyethyl)-amino]-butoxy-5-hydroxy-8-methoxy-2-phenylchromen-4-one (V8) is a novel flavonoid-derived compound. In this study, we investigated the effects of V8 on Toll-like receptor 4 (TLR4)-mediated inflammatory reaction in human cervical cancer SiHa cells and lipopolysaccharide (LPS)-induced TLR4 activity in cervical cancer SiHa (HPV16+) cells, but not in HeLa (HPV18+) and C33A (HPV-) cells. In addition, V8 inhibited LPS-induced expression of TLR4, MyD88, TRAF6 and phosphorylation of TAK1, and their interaction with TLR4 in SiHa cells, resulting in an inhibition of TLR4-MyD88-TRAF6-TAK1 complex. Moreover, V8 blocked LPS-induced phosphorylation of IκB and IKK, resulting in inhibition of the nuclear translocation of P65-NF-κB in SiHa cells. We also found that V8 reduced the expression of NF-κB target genes, such as those for COX-2, iNOS, IL-6, IL-8, CCL-2, and TNF-α in LPS-stimulated SiHa cells. These results suggested that V8 exerted an anti-inflammatory effect on SiHa cells by inhibiting the TLR4-MyD88-TRAF6-TAK1 complex-mediated NF-κB activation.

Tris (1,3-dichloro-2-propyl) phosphate-induced apoptotic signaling pathways in SH-SY5Y neuroblastoma cells

Tris (1, 3-dichloro-2-propyl) phosphate (TDCIPP, also known as TDCPP), an extensively used flame retardant, is frequently detected in the environment and biota. Recent studies have shown that TDCIPP has neurotoxic effects. In this study, we determined the mechanisms of TDCIPP-induced neurotoxicity in human neuroblastoma (SH-SY5Y) cells. By using morphological examination, flow cytometry, and mitochondrial membrane potential (ΔYm) measurement, we confirmed that exposure to TDCIPP caused apoptosis accompanied by the activation of apoptosis-related genes (e.g. Bax and Bcl-2) and caspase 3 protein in SH-SY5Y cells. Increased reactive oxygen species (ROS) formation and intracellular calcium ions ([Ca²⁺]_i) were also observed in TDCIPP-treated SH-SY5Y cells. Exposure to TDCIPP led to the activation of protein markers of endoplasmic reticulum (ER) stress, including eukaryotic translation initiation factor 2a subunit (p-EIF2a), activation transcription factor (ATF4), glucose-regulated protein (GRP78), and the proapoptotic factor C/EBP homologous protein (CHOP). To determine the role of the ER in apoptosis, phenyl butyric acid (PBA), an ER stress inhibitor, was applied. Treatment with PBA effectively attenuated TDCIPP-induced ER stress and protected against apoptotic death in SH-SY5Y cells by inhibition of Bax expression and promotion of Bcl-2 expression. Furthermore, we found that pretreatment of the cells with the ROS scavenger N-acetyl cysteine (NAC) inhibited the ER stress response and prevented apoptosis. The combination of PBA and NAC pretreatment could further prevent TDCIPP induced ER-stress and apoptotic death compared with PBA or NAC pretreatment alone. Thus, in the present study, we demonstrated that TDCIPP induces cytotoxicity through a ROS-dependent mechanism involving ER stress and activation of mitochondrial apoptotic pathways in SH-SY5Y cells.

V8 induces apoptosis and the endoplasmic reticulum stress response in human multiple myeloma RPMI 8226 cells via the PERK-eIF2α-ATF4 signaling pathway

Multiple myeloma (MM) is a fatal hematological cancer characterized by clonal plasma cell proliferation in the bone marrow. MM has an increasing global incidence and a poor prognosis. There are limited treatment options available for MM, and this is further compounded by the development of drug resistance. The present study demonstrated that 7-{4-[Bis-(2-hydroxyethyl)-amino]-butoxy}-5-hydroxy-8-methoxy-2-phenylchromen-4-one (V8), a novel synthetic flavonoid, induced apoptosis in human MM RPMI 8226 cells in a dose- and time-dependent manner, using cell viability assays and flow cytometry. Subsequently, V8-induced apoptosis in RPMI 8226 cells was revealed to occur via mitochondria-mediated pathways. The activity of caspase-3, -8 and -9, and the mRNA level of B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large were greatly increased, while the expression of Bcl-2-like protein 4 and BH3 interacting domain death agonist was significantly decreased in RPMI 8226 cells following V8 treatment, as observed using quantitative polymerase chain reaction (qPCR). In addition, western blotting revealed that the release of mitochondrial cytochrome c into the cytosol was promoted by V8. Furthermore, a clear alteration in endoplasmic reticulum (ER) stress was observed in cells treated with V8; upregulation of glucose-regulated protein (GRP) 78, GRP94, C/EBP homologous protein, cleavage of caspase-12, phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (p-PERK), phosphorylated eukaryotic initiation factor 2α (p-eIF2α) and activating transcription factor 4 (ATF4) was observed with qPCR and western blotting, suggesting that V8-induced apoptosis is involved in the ER stress response. Overall, the present results demonstrated that V8 induced apoptosis in human MM RPMI 8226 cells via the PERK-eIF2α-ATF4 ER stress response pathway, which may provide novel directions for exploiting this compound as a potential anti-neoplastic drug for MM therapy.

Insights into anticancer activity and mechanism of action of a ruthenium(II) complex in human esophageal squamous carcinoma EC109 cells

A ruthenium(II) complex [Ru(p-cymene)(NHC)Cl2] (NHC=1,3-bis(4-(tert-butyl)benzylimidazol-2-ylidene), referred to as L-4, has been designed and synthesized recently in order to look for new anticancer drugs with high efficacy and low side effects. The anticancer activity and mechanism of action of L-4 in human esophageal squamous carcinoma EC109 cells were systematically investigated. The results revealed that L-4 exerted strong inhibitory effect on the proliferation of EC109 cells, and it arrested EC109 cells at G2/M phase, accompanied with the up-regulation of p53 and p21 and the down-regulation of cyclin D1. The results also showed that the reactive oxygen species (ROS)-dependent apoptosis of EC109 can be induced by L-4 via inhibiting the activity of glutathione reductase (GR), decreasing the ratio of glutathione to oxidized glutathione (GSH/GSSG), and leading to the generation of reactive oxygen species. The mitochondria-mediated apoptosis of EC109 induced by L-4 was also observed from the increase of Bax/Bcl-2 ratio, overload of Ca(2+), disruption of mitochondrial membrane potential (MMP), redistribution of cytochrome c, and activation of caspase-3/-9. However, the effects of L-4 on the cell viability, GR activity, GSH/GSSG ratio, reactive oxygen species level, mitochondria dysfunction and apoptosis induction were remarkably attenuated by adding the reactive oxygen species scavenger, NAC. Therefore, it was concluded that L-4 can inhibit the proliferation of EC109 cells via blocking cell cycle progression and inducing reactive oxygen species-dependent and mitochondria-mediated apoptosis. These findings suggested that the ruthenium(II) complex might be a potential effective chemotherapeutic agent for human esophageal squamous carcinoma (ESCC) and worthy of further investigation.

2,4-dichlorophenol induces ER stress-mediated apoptosis via eIF2α dephosphorylation in vitro

2,4-Dichlorophenol (2,4-DCP) has been widely used to produce herbicides and pharmaceutical intermediates, which exhibits various toxic effects including apoptosis. However, the mechanisms underlying 2,4-DCP-induced apoptosis, especially mediated by endoplasmic reticulum (ER) stress, are still unknown. In the present study, the mouse embryonic fibroblasts (MEFs) were used as an in vitro model system to figure out whether 2,4-DCP could induce ER stress, and further to elucidate the role of ER stress in 2,4-DCP-induced apoptosis. The results showed that 2,4-DCP dramatically caused the decrease of cell viability, the increase of apoptotic cells, the collapse of mitochondrial membrane potential (MMP) and the activation of caspase-3, suggesting that 2,4-DCP did induce apoptosis. Meanwhile, 2,4-DCP acted similarly as ER stress agonist tunicamycin (Tu) to activate all three branches (IRE1α, ATF6 and eIF2α) of ER stress. Furthermore, repression of ER stress or inhibition of eIF2α dephosphorylation significantly alleviated 2,4-DCP-induced apoptosis. Taking these results together, the present study firstly showed that 2,4-DCP induced ER stress-mediated apoptosis via eIF2α dephosphorylation in mammalian cells. These findings will provide new insights into the mechanisms underlying apoptosis after chlorophenols exposure.

5-Fluorouracil combined with apigenin enhances anticancer activity through mitochondrial membrane potential (ΔΨm)-mediated apoptosis in hepatocellular carcinoma

The development of chemoresistance may reduce the efficacy of chemotherapeutic drugs for treating hepatocellular carcinoma (HCC). In the present study, the effects of apigenin on intensifying the chemosensitivity of HCC cells and an HCC xenograft model in response to 5-fluorouracil (5-FU) were investigated. Sub-toxic concentrations of apigenin (4 μmol/L) significantly enhanced the cytotoxicity of 5-FU (100 μg/mL) in HCC cells. In vivo, combined treatment with apigenin (20 mg/kg, five times/week for 3 weeks) and 5-FU (20 mg/kg for 5 consecutive days) significantly inhibited the growth of HCC xenograft tumours. Annexin V-propidium iodide dual staining assays, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling assays and western blotting analysis were used to confirm the synergistic effects of apigenin and 5-FU on HCC apoptosis. Coincubation of HCC cells with apigenin and 5-FU increased levels of reactive oxygen species (ROS), which was followed by a decrease in the mitochondrial membrane potential (ΔΨm). In addition, combined triggered the mitochondrial apoptotic pathway, as indicated by decreased Bcl-2 expression and loss of ΔΨm, with significant activation of caspase 3 and poly(ADP-ribose) polymerase. The present study is the first to demonstrate that apigenin may potentiate the cytotoxicity of 5-FU in HCC via inhibition of ROS-mediated drug resistance and concurrent activation of the mitochondrial pathways of apoptosis.

Selective in vivo targeting of human liver tumors by optimized AAV3 vectors in a murine xenograft model

Current challenges for recombinant adeno-associated virus (rAAV) vector-based cancer treatment include the low efficiency and the lack of specificity in vivo. rAAV serotype 3 (rAAV3) vectors have previously been shown to be ineffective in normal mouse tissues following systemic administration. In the present study, we report that rAAV3 vectors can efficiently target and transduce various human liver cancer cells in vivo. Elimination of specific surface-exposed serine and threonine residues on rAAV3 capsids results in further augmentation in the transduction efficiency of these vectors, without any change in the viral tropism and cellular receptor interactions. In addition, we have identified a potential chemotherapy drug, shikonin, as a multifunctional compound to inhibit liver tumor growth as well as to significantly enhance the efficacy of rAAV vector-based gene therapy in vivo. Furthermore, we also document that suppression of tumorigenesis in a human liver cancer xenograft model can be achieved through systemic administration of the optimized rAAV3 vectors carrying a therapeutic gene, and shikonin at a dose that does not lead to liver damage. Our research provides a novel means to achieve not only targeted delivery but also the potential for gene therapy of human liver cancer.

Global Transcriptome Analysis Reveals Acclimation-Primed Processes Involved in the Acquisition of Desiccation Tolerance in Boea hygrometrica

Boea hygrometrica resurrection plants require a period of acclimation by slow soil-drying in order to survive a subsequent period of rapid desiccation. The molecular basis of this observation was investigated by comparing gene expression profiles under different degrees of water deprivation. Transcripts were clustered according to the expression profiles in plants that were air-dried (rapid desiccation), soil-dried (gradual desiccation), rehydrated (acclimated) and air-dried after acclimation. Although phenotypically indistinguishable, it was shown by principal component analysis that the gene expression profiles in rehydrated, acclimated plants resemble those of desiccated plants more closely than those of hydrated acclimated plants. Enrichment analysis based on gene ontology was performed to deconvolute the processes that accompanied desiccation tolerance. Transcripts associated with autophagy and α-tocopherol accumulation were found to be activated in both air-dried, acclimated plants and soil-dried non-acclimated plants. Furthermore, transcripts associated with biosynthesis of ascorbic acid, cell wall catabolism, chaperone-assisted protein folding, respiration and macromolecule catabolism were activated and maintained during soil-drying and rehydration. Based on these findings, we hypothesize that activation of these processes leads to the establishment of an optimal physiological and cellular state that enables tolerance during rapid air-drying. Our study provides a novel insight into the transcriptional regulation of critical priming responses to enable survival following rapid dehydration in B. hygrometrica.

LZ-207, a Newly Synthesized Flavonoid, Induces Apoptosis and Suppresses Inflammation-Related Colon Cancer by Inhibiting the NF-κB Signaling Pathway

Flavonoids and flavonoid derivatives, which have significant biological and pharmacological activities, including antitumor and anti-inflammatory activities, have been widely used in human healthcare. To design a more effective flavonoid antitumor agent, we altered the flavonoid backbone with substitutions of piperazine and methoxy groups to synthesize a novel flavonoid derivative, LZ-207. The anticancer effect of LZ-207 against HCT116 colon cancer cells and the underlying mechanism of this effect were explored in this study. Specifically, LZ-207 exhibited inhibitory effects on growth and viability in several human colon cancer cell lines and induced apoptosis in HCT116 cells both in vitro and in vivo. LZ-207 treatment also suppressed the nuclear translocation of NF-κB and the phosphorylation of IκB and IKKα/β in a dose-dependent manner in both HCT116 cells and human acute monocytic leukemia THP-1 cells. Moreover, LZ-207 also reduced the secretion of the pro-inflammatory cytokine interleukin-6 (IL-6) in LPS-induced THP-1 cells, and this effect was confirmed at the transcriptional level. Furthermore, LZ-207 significantly inhibited HCT116 cell proliferation that was elicited by LPS-induced THP-1 cells in a co-culture system. These findings elucidated some potential molecular mechanisms for preventing inflammation-driven colon cancer using the newly synthesized flavonoid LZ-207 and suggested the possibility of further developing novel therapeutic agents derived from flavonoids.

Cytotoxic genes from traditional Chinese medicine inhibit tumor growth both in vitro and in vivo

OBJECTIVE

Little effort has been made to study the protein-encoding genes isolated from traditional Chinese medicine (TCM) drugs, and the delivery of these genes into malignant cells through recombinant adeno-associated virus (rAAV) vectors has not been attempted.

METHODS

We synthesized the cDNAs of five known cytotoxic proteins isolated from TCM drugs and the FLAG epitope-tagged cDNAs were subcloned into a rAAV plasmid vector. The protein expression was confirmed by Western blot assay. Various cancer cell lines were transfected with the above plasmids and cell growth was monitored both in vitro and in vivo. The best cytotoxic gene was further packaged into rAAV vectors, under the control of a liver cancer-specific promoter. The liver tumor growth was then monitored following intratumor administration of the rAAV vectors.

RESULTS

The expression plasmids, encoding individual potential cytotoxic genes tagged with FLAG epitope, were successfully generated and sequenced. Among these genes, trichosanthin (TCS) gene yielded the most promising results for the inhibition of cancer cell growth in vitro. The over-expressed TCS functioned as a type I ribosome-inactivating protein, followed by inducing apoptosis that is associated with the Bcl-PARP signaling pathway. Furthermore, intratumor injection of rAAV vectors containing the TCS gene significantly inhibited the growth of human hepatocellular carcinoma tumors in a murine xenograft model.

CONCLUSION

Our studies suggest that the use of TCM cytotoxic genes is a useful therapeutic strategy for treating human cancers in general, and liver tumors in particular.

SC-III3, a novel scopoletin derivative, induces cytotoxicity in hepatocellular cancer cells through oxidative DNA damage and ataxia telangiectasia-mutated nuclear protein kinase activation

Background

Natural products from plants have been proven to be important resources of antitumor agents. In this study, we exploited the antitumor activity of (E)-3-(4-chlorophenyl)-N-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yl) acrylamide (SC-III3), a newly synthesized derivative of scopoletin, by in vitro and in vivo experiments.

Methods

Human hepatocellular carcinoma cell line HepG2 cells and xenograft of HepG2 cells in BALB/c nude mice were used to investigate the effects of SC-III3 on hepatocellular cancers. Cell cycle arrest and apoptosis were analyzed by flow cytometry. Cell cycle arrest, apoptosis and ATM-Chk pathway-related proteins were characterized by western blot.

Results

SC-III3 selectively inhibited the viability of HepG2 cells without significant cytotoxicity against human normal liver cells LO2. In mouse xenograft model of HepG2 cells, SC-III3 showed a marked inhibition of tumor growth in a dose-dependent manner. Cell cycle analysis revealed that SC-III3 induced cells to accumulate in S phase, which was accompanied by a marked decrease of the expressions of cyclin A, cyclin B, cyclin E and Cdk2 proteins, the crucial regulators of S phase cell cycle. SC-III3 treatment resulted in DNA breaks in HepG2 cells, which might contribute to its S phase arrest. The S arrest and the activation of ATM-Chk1/Chk2-Cdc25A-Cdk2 pathways induced by SC-III3 in HepG2 cells could be efficiently abrogated by pretreatments of either Ku55933 (an inhibitor of ATM) or UCN-01 (an inhibitor of Chk1/Chk2). The activation of p53-p21 pathway by SC-III3 was also reversed by Ku55933 treatment. SC-III3 led to significant accumulation of intracellular reactive oxygen species (ROS), a breaker of DNA strand, in HepG2 cells but not LO2 cells. Pretreatment with N-acetyl-l-cysteine (NAC), a ROS scavenger, could reverse SC-III3-caused ROS accumulation, DNA damage, activation of signal pathways relevant to DNA damage, S phase arrest and cell viability decrease in HepG2 cells.

Conclusion

SC-III3 is able to efficiently inhibit the growth of hepatocellular carcinoma through inducing the generation of intracellular ROS, DNA damage and consequent S phase arrest, but lack of significant cytotoxicity against normal liver cells. This compound deserves further studies as a candidate of anticancer drugs.

Cajaninstilbene acid protects corticosterone-induced injury in PC12 cells by inhibiting oxidative and endoplasmic reticulum stress-mediated apoptosis

It has been reported that high corticosterone level could damage the normal hippocampal neurons both in vitro and in vivo. Furthermore, high concentration of corticosterone induced impair in PC12 cells has been widely used as in vitro model to screen neuroprotective agents. Cajaninstilbene acid (CSA), a natural stilbene isolated from Cajanus cajan leaves, has various activities. In present study, we investigated the effect of CSA on corticosterone-induced cell apoptosis and explored its possible signaling pathways in PC12 cells. We demonstrated that pretreatment with CSA at the concentrations of 1-8 μmol/L remarkably reduced the cytotoxicity induced by 200 μmol/L of corticosterone in PC12 cells by MTT, and further confirmed the neuroprotection by Hoechst 33342 and PI double staining and lactate dehydrogenase release (LDH) assay at the concentration of 8 μmol/L. Moreover, the cytoprotection of CSA was proved to be associated with the homeostasis of intracellular Ca(2+), relieving corticosterone-induced oxidative stress by decreasing the contents of ROS and malondialdehyde (MDA), increasing the activities of superoxide dismutase (SOD) and catalase (CAT), and the stabilization of ER stress via down-regulating the expression of ER chaperone protein glucose-regulated protein 78 (GRP78), ER stress associated transcription factor C/EBP homologous protein (CHOP/GADD153), and the X box-binding protein-1 (XBP-1), as well as the expression of ER stress-specific protein caspase-12 and its downstream protein caspase-9. Considering all the findings, it is suggested that the neuroprotective activity of CSA against the impairment induced by corticosterone in PC12 cells was through the inhibition of oxidative stress and ER stress-mediated pathway.

Luteoloside suppresses proliferation and metastasis of hepatocellular carcinoma cells by inhibition of NLRP3 inflammasome

The inflammasome is a multi-protein complex which when activated regulates caspase-1 activation and IL-1β secretion. Inflammasome activation is mediated by NLR proteins that respond to stimuli. Among NLRs, NLRP3 senses the widest array of stimuli. NLRP3 inflammasome plays an important role in the development of many cancer types. However, Whether NLRP3 inflammasome plays an important role in the process of hepatocellular carcinoma (HCC) is still unknown. Here, the anticancer effect of luteoloside, a naturally occurring flavonoid isolated from the medicinal plant Gentiana macrophylla, against HCC cells and the underlying mechanisms were investigated. Luteoloside significantly inhibited the proliferation of HCC cells in vitro and in vivo. Live-cell imaging and transwell assays showed that the migration and invasive capacities of HCC cells, which were treated with luteoloside, were significantly inhibited compared with the control cells. The inhibitory effect of luteoloside on metastasis was also observed in vivo in male BALB/c-nu/nu mouse lung metastasis model. Further studies showed that luteoloside could significantly reduce the intracellular reactive oxygen species (ROS) accumulation. The decreased levels of ROS induced by luteoloside was accompanied by decrease in expression of NLRP3 inflammasome resulting in decrease in proteolytic cleavage of caspase-1. Inactivation of caspase-1 by luteoloside resulted in inhibition of IL-1β. Thus, luteoloside exerts its inhibitory effect on proliferation, invasion and metastasis of HCC cells through inhibition of NLRP3 inflammasome. Our results indicate that luteoloside can be a potential therapeutic agent not only as an adjuvant therapy for HCC, but also, in the control and prevention of metastatic HCC.

LW-214, a newly synthesized flavonoid, induces intrinsic apoptosis pathway by down-regulating Trx-1 in MCF-7 human breast cells

In this study, the anticancer effect of LW-214, a newly synthesized flavonoid, against MCF-7 human breast cancer cells and the underlying mechanisms were investigated. LW-214 triggered the mitochondrial apoptotic pathway by increasing Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm) and caspase-9 activation, degradation of poly (ADP-ribose) polymerase (PARP), cytochrome c (Cyt c) release and apoptosis-inducing factor (AIF) transposition. Further research revealed that both the reactive oxygen species (ROS) generation and the apoptosis signal regulating kinase 1 (ASK1) activation by LW-214 were induced by down-regulating the thioredoxin-1 (Trx-1) expression. The ROS elevation and ASK1 activation induced a sustained phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125, as known as JNK inhibitor, almost reversed LW-214-induced apoptosis in MCF-7 cells. Overexpression of Trx-1 in MCF-7 cells attenuated LW-214-mediated apoptosis as well as the JNK activation and reversed the expression of mitochondrial apoptosis-related protein. Accordingly, the in vivo study showed that LW-214 exhibited a potential antitumor effect in BALB/c species mice inoculated MCF-7 tumor with low systemic toxicity, and the mechanism was the same as in vitro study. Taken together, these findings indicated that LW-214 may down-regulated Trx-1 function, causing intracellular ROS generation and releasing the ASK1, and lead to JNK activation, which consequently induced the mitochondrial apoptosis in vitro and in vivo.