Geranylgeranylacetone induces heat shock proteins in cultured guinea pig gastric mucosal cells and rat gastric mucosa

Pantoprazole and Vonoprazan Performed Well in Preventing Peptic Ulcer Recurrence in Low-Dose Aspirin Users

BACKGROUND

Low-dose aspirin (LDA) administration is associated with an elevated risk of recurring peptic ulcer (PU) and gastrointestinal (GI) hemorrhage.

AIMS

This systematic review and Bayesian network meta-analysis aimed to comprehensively assess the effectiveness of diverse medications in preventing the recurrence of PU and GI hemorrhage in patients with a history of PU receiving long-term LDA therapy.

METHODS

This systematic review and network meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered on PROSPERO (CRD42023406550). We searched relevant studies in main databases from inception to March 2023. All statistical analyses were performed using R (version 4.1.3), with the "Gemtc" (version 1.0-1) package. The pooled risk ratio (RR), corresponding 95% credible interval (95% CrI), and the surface under the cumulative ranking curve (SUCRA) were calculated.

RESULTS

11 Randomized clinical trials (RCTs) were included. The analysis underscored pantoprazole was the most efficacious for reducing the risk of PU recurrence (RR [95% CrI] = 0.02 [0, 0.28]; SUCRA: 90.76%), followed by vonoprazan (RR [95% CrI] = 0.03 [0, 0.19]; SUCRA: 86.47%), comparing with the placebo group. Pantoprazole also performed well in preventing GI hemorrhage (RR [95% CrI] = 0.01[0, 0.42]; SUCRA: 87.12%) compared with Teprenone.

CONCLUSIONS

For patients with a history of PU receiving LDA, pantoprazole and vonoprazan might be the optimal choices to prevent PU recurrence and GI hemorrhage.

Geranylgeranylacetone, an inducer of heat shock protein 70, attenuates pulmonary fibrosis via inhibiting NF-κB/NOX4/ROS signalling pathway in vitro and in vivo

Idiopathic pulmonary fibrosis (IPF) is a devastating and progressive pulmonary disease which is characterized by epithelial cell damage and extracellular collagen deposition. To date, the therapeutic options for IPF are still very limited, so the relevant mechanisms need to be explored. Heat shock protein 70 (HSP70), which has protective versus antitumor effects on cells under stress, is a member of the heat shock protein family. In the current study, qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to explore the Epithelial-mesenchymal transition (EMT) process in BEAS-2B cells. Moreover, the role of GGA in the process of pulmonary fibrosis was detected by HE, Masson staining, pulmonary function test and immunohistochemistry in C57BL/6 mice. Our results indicated that GGA, as an inducer of HSP70, enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells through the NF-κB/NOX4/ROS (reactive oxygen species) signalling pathway and could significantly reduce apoptosis of BEAS-2B cells induced by TGF-β1(Transforming growth factor β1) in vitro. In vivo studies demonstrated that HSP70-inducing drugs, such as GGA, attenuated pulmonary fibrosis progression induced by bleomycin (BLM). Collectively, these results suggested that overexpression of HSP70 attenuated pulmonary fibrosis induced by BLM in C57BL/6 mice and EMT process induced by TGF-β1 through NF-κB/NOX4/ROS pathway in vitro. Thus, HSP70 might be a potential therapeutic strategy for human lung fibrosis.

Inflammatory Bowel Diseases: An Updated Overview on the Heat Shock Protein Involvement

Inflammatory bowel diseases (IBDs) represent chronic idiopathic disorders, including Crohn's disease (CD) and ulcerative colitis (UC), in which one of the trigger factors is represented by aberrant immune interactions between the intestinal epithelium and the intestinal microbiota. The involvement of heat shock proteins (HSPs) as etiological and pathogenetic factors is becoming of increasing interest. HSPs were found to be differentially expressed in the intestinal tissues and sera of patients with CD and UC. It has been shown that HSPs can play a dual role in the disease, depending on the stage of progression. They can support the inflammatory and fibrosis process, but they can also act as protective factors during disease progression or before the onset of one of the worst complications of IBD, colorectal cancer. Furthermore, HSPs are able to mediate the interaction between the intestinal microbiota and intestinal epithelial cells. In this work, we discuss the involvement of HSPs in IBD considering their genetic, epigenetic, immune and molecular roles, referring to the most recent works present in the literature. With our review, we want to shed light on the importance of further exploring the role of HSPs, or even better, the role of the molecular chaperone system (CS), in IBD: various molecules of the CS including HSPs may have diagnostic, prognostic and therapeutic potential, promoting the creation of new drugs that could overcome the side-effects of the therapies currently used.

Geranylgeranylacetone Ameliorates Beta-Amyloid Toxicity and Extends Lifespan via the Heat Shock Response in Caenorhabditis elegans

Activation of a cytoprotective cellular pathway known as the heat shock response (HSR) is a promising strategy for the treatment of Alzheimer’s disease and other neurodegenerative diseases. Geranylgeranylacetone (GGA) is a commonly used anti-ulcer drug in Japan that has been shown to activate the HSR. Here, we establish C. elegans as a model system to investigate the effects of GGA. First, we show that GGA-mediated activation of the HSR is conserved in worms. Then, we show that GGA can ameliorate beta-amyloid toxicity in both muscle and neuronal worm Alzheimer’s disease models. Finally, we find that exposure to GGA is sufficient to extend the lifespan of wild-type worms. Significantly, the beneficial effects of GGA on both beta-amyloid toxicity and lifespan are dependent on HSR activation. Taken together, this research supports further development of GGA as a therapeutic for Alzheimer’s disease, provides evidence that HSR activation is a relevant therapeutic mechanism, and indicates that the beneficial effects of GGA are not limited to disease.

Quantitative Comparison of HSF1 Activators

The heat shock response (HSR) pathway is a highly conserved rescue mechanism, which protects the cells from harmful insults disturbing the cellular protein homeostasis via expression of chaperones. Furthermore, it was demonstrated to play crucial roles in various diseases like neurodegeneration and cancer. For neurodegenerative diseases, an overexpression of chaperones is a potential therapeutic approach to clear the cells from non-functional protein aggregates. Therefore, activators of the HSR pathway and its master regulator HSF1 are under close observation. There are numerous HSR activators published in the literature using different model systems, experimental designs, and readout assays. The aim of this work was to provide a quantitative comparison of a broad range of published activators using a newly developed HSF responsive dual-luciferase cell line. Contrary to natural target genes, which are regulated by multiple input pathways, the artificial reporter exclusively reacts to HSF activity. In addition, the results were compared to endogenous heat shock protein expression. As a result, great differences in the intensity of pathway activation were observed. In addition, a parallel viability assessment revealed high variability in the specificity of the drugs. Furthermore, the differences seen compared to published data indicate that some activators exhibit tissue-specific differences leading to interesting assumptions about the regulation of HSF1.

Oxidative Stress and Inflammation Caused by Cisplatin Ototoxicity

Hearing loss is a significant health problem that can result from a variety of exogenous insults that generate oxidative stress and inflammation. This can produce cellular damage and impairment of hearing. Radiation damage, ageing, damage produced by cochlear implantation, acoustic trauma and ototoxic drug exposure can all generate reactive oxygen species in the inner ear with loss of sensory cells and hearing loss. Cisplatin ototoxicity is one of the major causes of hearing loss in children and adults. This review will address cisplatin ototoxicity. It includes discussion of the mechanisms associated with cisplatin-induced hearing loss including uptake pathways for cisplatin entry, oxidative stress due to overpowering antioxidant defense mechanisms, and the recently described toxic pathways that are activated by cisplatin, including necroptosis and ferroptosis. The cochlea contains G-protein coupled receptors that can be activated to provide protection. These include adenosine A1 receptors, cannabinoid 2 receptors (CB2) and the Sphingosine 1-Phosphate Receptor 2 (S1PR2). A variety of heat shock proteins (HSPs) can be up-regulated in the cochlea. The use of exosomes offers a novel method of delivery of HSPs to provide protection. A reversible MET channel blocker that can be administered orally may block cisplatin uptake into the cochlear cells. Several protective agents in preclinical studies have been shown to not interfere with cisplatin efficacy. Statins have shown efficacy in reducing cisplatin ototoxicity without compromising patient response to treatment. Additional clinical trials could provide exciting findings in the prevention of cisplatin ototoxicity.

Geranylgeranylacetone decreases the production of hepatitis B virus-related antigen by comprehensive downregulation of mRNA transcription activity

BACKGROUND AND AIM

Elimination of hepatitis B virus (HBV) is infrequently achieved with current therapies. Therefore, more effective anti-HBV therapy is needed. We previously reported that geranylgeranylacetone (GGA) showed anti-hepatitis C virus activity in human hepatoma cells. In this study, we examined the anti-HBV activity of GGA.

METHODS

We used HepG2.2.15.7 cells, PXB cells infected with HBV, Huh7 cells transfected with linear HBV, and PLC/PRF/5 cells as HBV-infected hepatocyte models. After GGA treatment, HBV-related antigen was measured by chemiluminescent immunoassay. HBV-related mRNA was examined by Northern blot. cccDNA and endoplasmic reticulum stress markers were measured by real-time polymerase chain reaction. The activities of HBV promoters and enhancer regions were examined using luciferase vectors.

RESULTS

After GGA treatment, hepatitis B surface antigen and hepatitis B e antigen secretion was decreased in all HBV-infected hepatocyte models. HBV-related mRNA was also decreased by GGA treatment, although cccDNA levels were not affected. Additionally, the activity of HBV S1 and S2 promoter region and Enhancer 1/Enhancer 2/core promoter region was reduced by GGA treatment. The mRNA expression of the main transcription factors, hepatocyte nuclear factor 3 and 4 and CCAAT/enhancer binding protein, was also decreased. Further, the expression levels of endoplasmic reticulum stress markers were increased by GGA treatment, which reflected the change in HBV-related antigen secretion.

CONCLUSIONS

Geranylgeranylacetone treatment reduces HBV-related protein levels by suppressing comprehensive downregulation of HBV promoter and enhancer activity, which might be caused by decreased hepatic transcription factor expression. GGA treatment may enhance anti-HBV effects in combination with other therapies.

Overexpression of heat shock protein 70 inhibits epithelial-mesenchymal transition and cell migration induced by transforming growth factor-β in A549 cells

Heat shock protein 70 (HSP70) is a key member of the HSP family that contributes to a pre-cancerous environment; however, its role in lung cancer remains poorly understood. The present study used geranylgeranylacetone (GGA) to induce HSP70 expression, and transforming growth factor-β (TGF-β) was used to construct an epithelial-mesenchymal transition (EMT) model by stimulating A549 cells in vitro. Western Blot was performed to detect protein levels of NADPH oxidase 4 (NOX4) and the EMT-associated proteins E-cadherin and vimentin both before and after HSP70 expression. Cell morphological changes were observed, and the effect of HSP70 on cell migration ability was detected via the wound healing. The results demonstrated that GGA at 50 and 200 μmol/L could significantly induce HSP70 expression in A549 cells (P < 0.05). Furthermore, HSP70 induced by 200 μmol/L GGA significantly inhibited the changes of E-cadherin, vimentin, and cell morphology induced by TGF-β (P < 0.05), while HSP70 induced by 50 μmol/L GGA did not. The results of the wound healing assay indicated that 200 μmol/L GGA significantly inhibited A549 cell migration induced by TGF-β. Taken together, the results of the present study demonstrated that overexpression of HSP70 inhibited the TGF-β induced EMT process and changed the cell morphology and migratory ability induced by TGF-β in A549 cells.

Geranylgeranylacetone attenuates cerebral ischemia-reperfusion injury in rats through the augmentation of HSP 27 phosphorylation: a preliminary study

Background

We previously reported that heat shock protein 27 (HSP27) phosphorylation plays an important role in the activation of glucose-6-phosphate dehydrogenase (G6PD), resulting in the upregulation of the pentose phosphate pathway and antioxidant effects against cerebral ischemia–reperfusion injury. The present study investigated the effect of geranylgeranylacetone, an inducer of HSP27, on ischemia–reperfusion injury in male rats as a preliminary study to see if further research of the effects of geranylgeranylacetone on the ischemic stroke was warranted.

Methods

In all experiments, male Wistar rats were used. First, we conducted pathway activity profiling based on a gas chromatography–mass spectrometry to identify ischemia–reperfusion-related metabolic pathways. Next, we investigated the effects of geranylgeranylacetone on the pentose phosphate pathway and ischemia–reperfusion injury by real-time polymerase chain reaction (RT-PCR), immunoblotting, and G6PD activity, protein carbonylation and infarct volume analysis. Geranylgeranylacetone or vehicle was injected intracerebroventricularly 3 h prior to middle cerebral artery occlusion or sham operation.

Results

Pathway activity profiling demonstrated that changes in the metabolic state depended on reperfusion time and that the pentose phosphate pathway and taurine-hypotaurine metabolism pathway were the most strongly related to reperfusion among 137 metabolic pathways. RT-PCR demonstrated that geranylgeranylacetone did not significantly affect the increase in HSP27 transcript levels after ischemia–reperfusion. Immunoblotting showed that geranylgeranylacetone did not significantly affect the elevation of HSP27 protein levels. However, geranylgeranylacetone significantly increase the elevation of phosphorylation of HSP27 after ischemia–reperfusion. In addition, geranylgeranylacetone significantly affected the increase in G6PD activity, and reduced the increase in protein carbonylation after ischemia–reperfusion. Accordingly, geranylgeranylacetone significantly reduced the infarct size (median 31.3% vs 19.9%, p = 0.0013).

Conclusions

As a preliminary study, these findings suggest that geranylgeranylacetone may be a promising agent for the treatment of ischemic stroke and would be worthy of further study. Further studies are required to clearly delineate the mechanism of geranylgeranylacetone-induced HSP27 phosphorylation in antioxidant effects, which may guide the development of new approaches for minimizing the impact of cerebral ischemia–reperfusion injury.

Combined application of geranylgeranylacetone and amelogenin promotes angiogenesis and wound healing in human periodontal ligament cells

Amelogenin directly binds to glucose-regulated protein 78 (Grp78). Cell migration activity is expected to increase when human periodontal ligament cells (hPDLCs) overexpressing Grp78 are treated with amelogenin. Geranylgeranylacetone (GGA) is a drug that induces the expression of heat shock protein and is routinely used to treat gastric ulcers. Here, we investigated the changes in the properties and behavior of hPDLCs in response to treatment with GGA and the synergistic effects of amelogenin stimulation in hPDLCs pretreated with GGA for the establishment of a novel periodontal tissue regenerative therapy. We observed that GGA treatment increased Grp78 protein expression in hPDLCs and enhanced cell migration. Microarray analysis demonstrated that increased Grp78 expression triggered the production of angiopoietin-like 4 and amphiregulin, which are involved in the enhancement of angiogenesis and subsequent wound healing via the activation of hypoxia-inducible factor 1α and peroxisome proliferator-activated receptors as well as the phosphorylation of cAMP response element-binding protein and protein kinase A. Moreover, the addition of recombinant murine amelogenin (rM180) further accelerated hPDLC migration and tube formation of human umbilical vein endothelial cells due to the upregulation of interleukin-8 (IL-8), monocyte chemotactic protein 1, and IL-6, which are also known as angiogenesis-inducing factors. These findings suggest that the application of GGA to gingival tissue and alveolar bone damaged by periodontal disease would facilitate the wound healing process by inducing periodontal ligament cells to migrate to the root surface and release cytokines involved in tissue repair. Additionally, supplementation with amelogenin synergistically enhanced the migratory capacity of these cells while actively promoting angiogenesis. Therefore, the combined application of GGA and amelogenin may establish a suitable environment for periodontal wound healing and further drive the development of novel therapeutics for periodontal tissue regeneration.

Predictive Modeling of MAFLD Based on Hsp90α and the Therapeutic Application of Teprenone in a Diet-Induced Mouse Model

BACKGROUND AND AIMS

The heat shock protein (Hsp) 90α is induced by stress and regulates inflammation through multiple pathways. Elevated serum Hsp90α had been found in nonalcoholic steatohepatitis (NASH). Geranylgeranylacetone (GGA, also called teprenone) is a terpenoid derivative. It was reported to induce Hsp and alleviate insulin resistance. We aimed to evaluate the Hsp90α as a biomarker in predicting metabolic-associated fatty liver disease (MAFLD) and define the therapeutic effects of geranylgeranylacetone for the disease.

METHODS

A clinical study was conducted to analyze the elements associated with Hsp90α, and a predictive model of MAFLD was developed based on Hsp90α. The histopathological correlation between Hsp90α and MAFLD was investigated through a diet-induced mouse model. Furthermore, GGA was applied to the mouse model.

RESULTS

Serum Hsp90α was increased in patients with MAFLD. A positive linear relationship was found between age, glycosylated hemoglobin (HbA1c), MAFLD, and serum Hsp90α. Meanwhile, a negative linear relationship with body mass index (BMI) was found. A model using Hsp90α, BMI, HbA1c, and ALT was established for predicting MAFLD. The area under the receiver operating characteristic (ROC) curves was 0.94 (95% CI 0.909-0.971, p = 0.000). The sensitivity was 84.1%, and the specificity was 93.1%. In vitro experiments, GGA induced Hsp90α in steatosis cells. In the mice model, Hsp90α decreased in the GGA treatment group. Hepatic steatosis, inflammation, insulin resistance, and glucose intolerance were improved in the GGA-treated group. Serum Hsp90α was positively correlated with steatohepatitis activity according to hepatic histopathology.

CONCLUSIONS

Serum Hsp90α was elevated in MAFLD, and a positive correlation between serum Hsp90α and the grade of activity of steatohepatitis was observed. The model using BMI, HbA1c, and alanine aminotransferase (ALT) had a good value to predict MAFLD. The findings also revealed the effectiveness of GGA in the treatment of MAFLD.

Geranylgeranyl acetone prevents glutamate-induced cell death in HT-22 cells by increasing mitochondrial membrane potential

Geranylgeranyl acetone (GGA) protects against various types of cell damages by upregulating heat shock proteins. We investigated whether GGA protects neuronal cells from cell death induced by oxidative stress. Glutamate exposure was lethal to HT-22 cells which comprise a neuronal line derived from mouse hippocampus. This configuration is often used as a model for hippocampus neurodegeneration in vitro. In the present study, GGA protected HT-22 cells from glutamate-induced oxidative stress. GGA pretreatment did not induce heat shock proteins (Hsps). Moreover, reactive oxygen species increased to the same extent in both GGA-pretreated and untreated cells exposed to glutamate. In contrast, glutamate exposure and GGA pretreatment increased mitochondrial membrane potential. However, increases in intracellular Ca²⁺ concentration were inhibited by GGA pretreatment. In addition, the increase of phosphorylated ERKs by the glutamate exposure was inhibited by GGA pretreatment. These findings suggest that GGA protects HT-22 cells from glutamate-provoked cell death without Hsp induction and that the mitochondrial calcium buffering capacity plays an important role in this protective effect.

Inflammasomes and Proteostasis Novel Molecular Mechanisms Associated With Atrial Fibrillation

Atrial fibrillation (AF), the most common progressive and age-related cardiac arrhythmia, affects millions of people worldwide. AF is associated with common risk factors, including hypertension, diabetes mellitus, and obesity, and serious complications such as stroke and heart failure. Notably, AF is progressive in nature, and because current treatment options are mainly symptomatic, they have only a moderate effect on prevention of arrhythmia progression. Hereto, there is an urgent unmet need to develop mechanistic treatments directed at root causes of AF. Recent research findings indicate a key role for inflammasomes and derailed proteostasis as root causes of AF. Here, we elaborate on the molecular mechanisms of these 2 emerging key pathways driving the pathogenesis of AF. First the role of NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome on AF pathogenesis and cardiomyocyte remodeling is discussed. Then we highlight pathways of proteostasis derailment, including exhaustion of cardioprotective heat shock proteins, disruption of cytoskeletal proteins via histone deacetylases, and the recently discovered DNA damage-induced nicotinamide adenine dinucleotide⁺ depletion to underlie AF. Moreover, potential interactions between the inflammasomes and proteostasis pathways are discussed and possible therapeutic targets within these pathways indicated.

The road ahead for health and lifespan interventions

Aging is a modifiable risk factor for most chronic diseases and an inevitable process in humans. The development of pharmacological interventions aimed at delaying or preventing the onset of chronic conditions and other age-related diseases has been at the forefront of the aging field. Preclinical findings have demonstrated that species, sex and strain confer significant heterogeneity on reaching the desired health- and lifespan-promoting pharmacological responses in model organisms. Translating the safety and efficacy of these interventions to humans and the lack of reliable biomarkers that serve as predictors of health outcomes remain a challenge. Here, we will survey current pharmacological interventions that promote lifespan extension and/or increased healthspan in animals and humans, and review the various anti-aging interventions selected for inclusion in the NIA's Interventions Testing Program as well as the ClinicalTrials.gov database that target aging or age-related diseases in humans.

HSP70 induction by bleomycin metal core analogs

Induction of heat shock protein 70 (HSP70) is known to be effective against various diseases. We are interested in HSP70 induction capability of an antitumor antibiotic bleomycin which produces oxidative stress by iron chelate formation and oxygen activation in a cell. The HSP70 induction activity of bleomycin and its six metal core analogs was examined, and a compound HPH-1Trt of 10 μM was found to induce this protein in a pheochromocytoma cell line and some T cell and monocytic cell lines. Its mechanism is increase of HSP70 mRNA, but higher concentration of this compound showed toxicity. Two new derivatives were then synthesized, and one of them named DHPH-1Trt was shown to have less toxicity and higher HSP70 induction activity. This study would lead to a clue for new HSP70 inducer clinically used in near future.

The Cytotoxic Effects of Geranylgeranylacetone Are Attenuated in the High-Glucose Condition

Geranylgeranylacetone (GGA) has been used as an antiulcer drug and also is known as inducer of heat shock protein 70 that has cytoprotective effects especially in hyperglycemic condition. In contrast, cytotoxicity of GGA has also been reported. Some studies have reported that GGA suppresses cell growth and induces apoptosis in cell models of human leukemia, ovarian carcinoma, and colon cancer in vitro. Therefore, the aim of this study was to determine whether GGA can have a cytotoxic effect on a human cervical cancer cell line (HeLa), human colorectal adenocarcinoma cells (Caco-2), and human embryonic kidney cells 293 (HEK) in normal-glucose and high-glucose environments (NG and HG, respectively). The results showed that 100 μM GGA inhibited proliferation of HeLa cells only in NG environment despite inhibiting proliferation of Caco-2 and HEK cells regardless of glucose concentration. Cell viability assay revealed that GGA decreased viability of HeLa, Caco-2, and HEK cells only in NG environment. Flow cytometric analyses revealed that the type of cell death was a combination of necrosis and apoptosis. Our study revealed that difference in cytotoxicity of GGA is influenced by glucose condition. The cytotoxic effects of GGA are attenuated in the HG condition. Since both cytotoxic and cytoprotective effects are reported about GGA, further research is needed about the mechanism of the cytotoxic effects.

Heat-Shock Proteins in Neuroinflammation

The heat-shock response, one of the main pro-survival mechanisms of a living organism, has evolved as the biochemical response of cells to cope with heat stress. The most well-characterized aspect of the heat-shock response is the accumulation of a conserved set of proteins termed heat-shock proteins (HSPs). HSPs are key players in protein homeostasis acting as chaperones by aiding the folding and assembly of nascent proteins and protecting against protein aggregation. HSPs have been associated with neurological diseases in the context of their chaperone activity, as they were found to suppress the aggregation of misfolded toxic proteins. In recent times, HSPs have proven to have functions apart from the classical molecular chaperoning in that they play a role in a wider scale of neurological disorders by modulating neuronal survival, inflammation, and disease-specific signaling processes. HSPs are gaining importance based on their ability to fine-tune inflammation and act as immune modulators in various bodily fluids. However, their effect on neuroinflammation processes is not yet fully understood. In this review, we summarize the role of neuroinflammation in acute and chronic pathological conditions affecting the brain. Moreover, we seek to explore the existing literature on HSP-mediated inflammatory function within the central nervous system and compare the function of these proteins when they are localized intracellularly compared to being present in the extracellular milieu.

Harnessing biocompatible chemistry for developing improved and novel microbial cell factories

White biotechnology relies on the sophisticated chemical machinery inside living cells for producing a broad range of useful compounds in a sustainable and environmentally friendly way. However, despite the impressive repertoire of compounds that can be generated using white biotechnology, this approach cannot currently fully replace traditional chemical production, often relying on petroleum as a raw material. One challenge is the limited number of chemical transformations taking place in living organisms. Biocompatible chemistry, that is non‐enzymatic chemical reactions taking place under mild conditions compatible with living organisms, could provide a solution. Biocompatible chemistry is not a novel invention, and has since long been used by living organisms. Examples include Fenton chemistry, used by microorganisms for degrading plant materials, and manganese or ketoacids dependent chemistry used for detoxifying reactive oxygen species. However, harnessing biocompatible chemistry for expanding the chemical repertoire of living cells is a relatively novel approach within white biotechnology, and it could potentially be used for producing valuable compounds which living organisms otherwise are not able to generate. In this mini review, we discuss such applications of biocompatible chemistry, and clarify the potential that lies in using biocompatible chemistry in conjunction with metabolically engineered cell factories for cheap substrate utilization, improved cell physiology, efficient pathway construction and novel chemicals production.

Teprenone improves gastric mucosal injury and dyspeptic symptoms in long-term nonsteroidal anti-inflammatory drug users

BACKGROUND AND AIM

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a major cause of gastric mucosal lesions. In China, teprenone is frequently prescribed as a mucoprotective agent, but the literature regarding their efficacy is limited. Our purpose was to address the effects of teprenone on long-term NSAID-associated gastric mucosal lesions.

METHODS

This study examined 369 patients taking NSAIDs for at least 12 weeks. Patients without gastroduodenal ulcer and without Helicobacter pylori infection on endoscopy at baseline were randomized to receive either NSAID plus teprenone (150 mg/day) or NSAID only for 12 weeks. Lanza scores were examined using endoscopy before and after treatment, and dyspeptic symptom scores are also analyzed.

RESULTS

A total of 158 patients were randomized to the teprenone group (n = 74) or the control group (n = 84) for 12 weeks. Seventy-one of patients in the teprenone group and 79 of patients in the control group were analyzed finally. After treatment, the Lanza scores and dyspeptic symptom scores decreased significantly in the teprenone group while increased in the control group (P < 0.05). The changes of Lanza scores and dyspeptic symptom scores were higher in the teprenone group than in the control group (P < 0.05). For subgroup analysis, the change in Lanza scores and dyspeptic symptom scores improved significantly in the teprenone group receiving long-term low-dose aspirin treatment, as well as in the teprenone group receiving other NSAIDs treatment (P < 0.05).

CONCLUSIONS

Teprenone may be an effective treatment choice of gastric mucosal injuries and dyspepsia symptoms in patients who used NSAIDs chronically without H. pylori infection or history of gastroduodenal ulcer.

Role of heat shock protein 22 in the protective effect of geranylgeranylacetone in response to oxidized-LDL

Objective

The aim was to investigate the role and potential mechanism of geranylgeranylacetone (GGA) in the development of atherosclerosis, and to explore the role of heat shock protein 22 (HSP22) in mediating GGA effect.

Methods

Human coronary artery endothelial cell (HCAEC) was used for in vitro study. RNA interference was applied to suppress HSP22 in the cells. Cellular apoptosis and intracellular level of reactive oxygen species (ROS) were detected by flow cytometer, and proteins of HSP22, NF-κB, eNOS, and ICAM-1 were assessed by immunoblotting. HSP22^-/-//ApoE^-/-, and HSP22^+/+//ApoE^-/- mice were used to investigate the effect of GGA in the animal model of atherosclerosis. Atherosclerotic lesion of the mice aortas was evaluated by Oil Red O staining and H&E staining.

Results

GGA significantly inhibited HCAEC apoptosis in response to oxidized-LDL (ox-LDL), but stimulated HSP22 synthesis in the cells. Transfection of HSP22-siRNA in the cells resulted in complete blockage of the GGA effect on apoptosis. GGA also significantly inhibited ROS, NF-κB, and ICAM-1 in the cells transfected control siRNA, but not in the cells transfected with HSP22-siRNA. Atherosclerotic plaque in the aorta was significantly less in the wild type (WT) animals treated with GGA as stained either by Oil Red O or by H&E staining, but not in the HSP22-KO mice. GGA significantly inhibited expression of NF-κB and ICAM-1 in the WT mice, but not in the HSP22-KO mice.

Conclusion

GGA-induced HSP22, and inhibited ox-LDL-induced apoptosis as well as expression of NF-κB and ICAM-1 in the HCAECs. GGA also attenuated formation of atherosclerotic plaques in mice aorta. Suppression of HSP22 by siRNA resulted in blockage of the GGA inhibition on apoptosis or stimulation on NF-κB and ICAM-1. These findings suggested that GGA protects endothelial cells from injury in response to ox-LDL and block atherosclerotic development in mice aorta through induction of HSP22.

Screening of novel HSP-inducing compounds to conserve cardiomyocyte function in experimental atrial fibrillation

Background

The heat shock protein (HSP) inducer, geranylgeranylacetone (GGA), was previously found to protect against atrial fibrillation (AF) remodeling in experimental model systems. Clinical application of GGA in AF is limited, due to low systemic concentrations owing to the hydrophobic character of GGA.

Objectives

To identify novel HSP-inducing compounds, with improved physicochemical properties, that prevent contractile dysfunction in experimental model systems for AF.

Methods

Eighty-one GGA-derivatives were synthesized and explored for their HSP-inducing properties by assessment of HSP expression in HL-1 cardiomyocytes pretreated with or without a mild heat shock (HS), followed by incubation with 10 µM GGA or GGA-derivative. Subsequently, the most potent HSP-inducers were tested for preservation of calcium transient (CaT) amplitudes or heart wall contraction in pretreated tachypaced HL-1 cardiomyocytes (with or without HSPB1 siRNA) and Drosophilas, respectively. Finally, CaT recovery in tachypaced HL-1 cardiomyocytes posttreated with GGA or protective GGA-derivatives was determined.

Results

Thirty GGA-derivatives significantly induced HSPA1A expression after HS, and seven showed exceeding HSPA1A expression compared to GGA. GGA and nine GGA-derivatives protected significantly from tachypacing (TP)-induced CaT loss, which was abrogated by HSPB1 suppression. GGA and four potent GGA-derivatives protected against heart wall dysfunction after TP compared to non-paced control Drosophilas. Of these compounds, GGA and three GGA-derivatives induced a significant restoration from CaT loss after TP of HL-1 cardiomyocytes.

Conclusion

We identified novel GGA-derivatives with improved physicochemical properties compared to GGA. GGA-derivatives, particularly GGA^*-59, boost HSP expression resulting in prevention and restoration from TP-induced remodeling, substantiating their role as novel therapeutics in clinical AF.

Neurodegenerative Diseases: Regenerative Mechanisms and Novel Therapeutic Approaches

Regeneration refers to regrowth of tissue in the central nervous system. It includes generation of new neurons, glia, myelin, and synapses, as well as the regaining of essential functions: sensory, motor, emotional and cognitive abilities. Unfortunately, regeneration within the nervous system is very slow compared to other body systems. This relative slowness is attributed to increased vulnerability to irreversible cellular insults and the loss of function due to the very long lifespan of neurons, the stretch of cells and cytoplasm over several dozens of inches throughout the body, insufficiency of the tissue-level waste removal system, and minimal neural cell proliferation/self-renewal capacity. In this context, the current review summarized the most common features of major neurodegenerative disorders; their causes and consequences and proposed novel therapeutic approaches.

Cytoprotective effect of eupatilin against indomethacin-induced damage in feline esophageal epithelial cells: relevance of HSP27 and HSP70

Indomethacin is a non-steroidal anti-inflammatory drug with clearly known side effects on the gastrointestinal tract. The purpose of the present study was to investigate whether eupatilin inhibit cell injury induced by indomethacin in cultured feline esophageal epithelial cells (EECs). EECs were used to investigate the ability of eupatilin to induce the expression of heat shock proteins (HSP27 and HSP70) and analyze its cytoprotective effect against indomethacin-induced damage. The treatment of EECs with indomethacin for 8 h decreased cell viability. Western blot analysis showed that the levels of HSPs gradually decreased in cells treated with indomethacin, while eupatilin treatment increased the levels of HSPs. When treated with both indomethacin and eupatilin, the levels of HSPs increased rapidly, and were maintained at 130-140%. In addition, treatment with the specific inhibitors of PTK, PKC, PLC, p38 MAPK, JNKs, and PI3K attenuated the eupatilin-induced expression of HSPs. Pretreatment of EECs with the inhibitors of protein synthesis, actinomycin D or cycloheximide, attenuated the cytoprotective effect of eupatilin on indomethacin-induced cell damage. Reactive oxygen species production was upregulated by indomethacin, but downregulated by eupatilin. Taken together, it was suggested that HSPs were partly responsible for the eupatilin-mediated cytoprotective activity against the indomethacin-induced damage in EECs.

Hsp70 Suppresses Mitochondrial Reactive Oxygen Species and Preserves Pulmonary Microvascular Barrier Integrity Following Exposure to Bacterial Toxins

Pneumonia is a leading cause of death in children and the elderly worldwide, accounting for 15% of all deaths of children under 5 years old. Streptococcus pneumoniae is a common and aggressive cause of pneumonia and can also contribute to meningitis and sepsis. Despite the widespread use of antibiotics, mortality rates for pneumonia remain unacceptably high in part due to the release of bacterial toxins. Pneumolysin (PLY) is a cholesterol-dependent toxin that is produced by Streptococcus, and it is both necessary and sufficient for the development of the extensive pulmonary permeability edema that underlies acute lung injury. The mechanisms by which PLY disrupts the pulmonary endothelial barrier are not fully understood. Previously, we found that reactive oxygen species (ROS) contribute to the barrier destructive effects of PLY and identified an unexpected but potent role of Hsp70 in suppressing ROS production. The ability of Hsp70 to influence PLY-induced barrier dysfunction is not yet described, and the goal of the current study was to identify whether Hsp70 upregulation is an effective strategy to protect the lung microvascular endothelial barrier from G⁺ bacterial toxins. Overexpression of Hsp70 via adenovirus-mediated gene transfer attenuated PLY-induced increases in permeability in human lung microvascular endothelial cells (HLMVEC) with no evidence of cytotoxicity. To adopt a more translational approach, we employed a pharmacological approach using geranylgeranylacetone (GGA) to acutely upregulate endogenous Hsp70 expression. Following acute treatment (6 h) with GGA, HLMVECs exposed to PLY displayed improved cell viability and enhanced endothelial barrier function as measured by both Electric Cell-substrate Impedance Sensing (ECIS) and transwell permeability assays compared to control treated cells. PLY promoted increased mitochondrial ROS, decreased mitochondrial oxygen consumption, and increased caspase 3 cleavage and cell death, which were collectively improved in cells pretreated with GGA. In mice, IP pretreatment with GGA 24 h prior to IT administration of PLY resulted in significantly less Evans Blue Dye extravasation compared to vehicle, indicating preserved endothelial barrier integrity and suggesting that the acute upregulation of Hsp70 may be an effective therapeutic approach in the treatment of lung injury associated with pneumonia.

Geranylgeranylacetone induction of HSP90α exerts cryoprotective effect on Acipenser sinensis sperm

Heat Shock Protein 90 (HSP90) is a fertility-associated protein, the expression of which positively correlates with sperm quality in many species. Geranylgeranylacetone (GGA) is reported to induce expression of HSP90. The present study aimed to investigate whether GGA induced expression of HSP90 in Acipenser sinensis sperm to exert a cryoprotective effect. Sperm from five male A. sinensis was combined with extender containing 20 mmol/L tris pH = 8.1, 10% v/v methanol, 2-5 mmol/L KCl, 15 mmol/L lactose, and 15 mmol/L trehalose, with GGA at 0, 14, 67, 135, 673, 1346, or 6731 μmol/L. After cryopreservation and thawing, the percentage of motile spermatozoa, spermatozoon curvilinear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), acrosome integrity, and membrane integrity, as well as fertility were evaluated. Sperm quality increased with the increase of GGA to 673 μmol/L, but decreased at higher concentrations. Expression levels of HSP90α were detected by Western blot in sperm frozen with GGA at 673 μmol/L (highest obtained sperm quality), 6731 μmol/L (highest GGA concentration), and a control without GGA. The expression of HSP90α increased with the increase in GGA, with lowest expression observed in the control. GGA was found to induce increase of HSP90α, and this increase was associated with higher quality cryopreserved sperm at concentrations ≤673 μmol/L. This research suggests a viable technique to increase the quality of cryopreserved A. sinensis sperm by adding GGA to induce expression of HSP90α.

Geranylgeranylacetone attenuates fibrogenic activity and induces apoptosis in cultured human hepatic stellate cells and reduces liver fibrosis in carbon tetrachloride-treated mice

Background

Geranylgeranylacetone (GGA), an anti-ulcer drug widely used in Japan, has attracted interest because of its various therapeutic effects. Therefore, we investigated the effects of GGA on human hepatic stellate cells (HSCs) in vitro and in a mouse model of liver fibrosis.

Methods

LX2, an immortalized human HSC line, was cultured and treated with GGA at concentrations up to 0.5 mM. After GGA treatment, changes in cellular morphology, apoptosis, and fibrosis-related gene expression were assessed. Male C57BL/6 J mouse model of carbon tetrachloride (CCl₄)-induced liver fibrosis was treated with GGA. Liver fibrosis was evaluated using Sirius red staining and immunohistochemistry for α-smooth muscle actin (SMA).

Results

GGA decreased the density of LX2 and primary human hepatic stellate cells but not that of HepG2 cells (a human hepatoma cell line), which was employed as control. In addition, GGA decreased the expression of fibrogenic genes and increased that of C/EBP homologous protein (CHOP). It also induced endoplasmic reticulum (ER) stress and increased apoptosis. CHOP knockdown, however, failed to suppress the GGA-induced decrease in LX2 cell density, suggesting the involvement of additional molecules in ER stress–associated apoptosis. Expression of death receptor 5, mitogen-activated protein kinase, heat shock protein 70, and Akt, all of which affect the activity of stellate cells, was unchanged in relation to LX2 cell fibrogenic activity. In the mouse model of liver fibrosis, GGA decreased the extent of Sirius red staining and SMA expression.

Conclusions

GGA attenuated fibrogenic activity and induced apoptosis in cultured human HSCs, and suppressed liver fibrosis in mice, suggesting its potential as an agent for treating liver fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0761-7) contains supplementary material, which is available to authorized users.

Geranylgeranylacetone exerts neuroprotective roles through medicating the phosphatidylinositol-3 kinase/Akt signaling pathway in an intracerebral hemorrhage rat model

AIM

Previous studies have demonstrated that geranylgeranylacetone exerts neuroprotective effects in experimental intracerebral hemorrhage. This study is designed to explore the underlying mechanism.

MATERIALS AND METHODS

One hundred and eighty male Sprague-Dawley rats were subjected to intracerebral hemorrhage by stereotactic injection of collagenase and were pretreated without or with different doses of geranylgeranylacetone. At 6 h, 24 h, 48 h, 72 h and 7 days after the operation, the neurological deficits were examined with the scoring scale method. To explore the underlying mechanism, wortmannin (Wort), a specific phosphatidylinositol-3 kinase (PI3K) inhibitor, was used. The protein expression of Akt was determined by Western blotting. The brain water content and the hematoma volume assessment were measured and compared among the different groups.

RESULTS

We first found that geranylgeranylacetone pretreatment significantly reduced neurological deficit in intracerebral hemorrhage rats, indicating its neuroprotective role. Then, we found wort treatment significantly decreased the geranylgeranylacetone-induced Akt expression level in intracerebral hemorrhage rats. Besides, wort not only reversed the effects of geranylgeranylacetone on neurological function, but also reversed the effects of geranylgeranylacetone on reducing brain edema and decreasing hematoma volume in intracerebral hemorrhage rats.

CONCLUSION

Geranylgeranylacetone exerts neuroprotective roles, at least partially, through medicating the PI3K/Akt signaling pathway in an experimental intracerebral hemorrhage rat model.

Heat Shock Proteins and Autophagy Pathways in Neuroprotection: from Molecular Bases to Pharmacological Interventions

Neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease and Huntington's disease (HD), amyotrophic lateral sclerosis, and prion diseases are all characterized by the accumulation of protein aggregates (amyloids) into inclusions and/or plaques. The ubiquitous presence of amyloids in NDDs suggests the involvement of disturbed protein homeostasis (proteostasis) in the underlying pathomechanisms. This review summarizes specific mechanisms that maintain proteostasis, including molecular chaperons, the ubiquitin-proteasome system (UPS), endoplasmic reticulum associated degradation (ERAD), and different autophagic pathways (chaperon mediated-, micro-, and macro-autophagy). The role of heat shock proteins (Hsps) in cellular quality control and degradation of pathogenic proteins is reviewed. Finally, putative therapeutic strategies for efficient removal of cytotoxic proteins from neurons and design of new therapeutic targets against the progression of NDDs are discussed.

From bench (laboratory) to bed (hospital/home): How to explore effective natural and synthetic PAK1-blockers/longevity-promoters for cancer therapy

PAK family kinases are RAC/CDC42-activated kinases that were first found in a soil amoeba 4 decades ago, and 2 decades later, were discovered in mammals as well. Since then at least 6 members of this family have been identified in mammals. One of them called PAK1 has been best studied so far, mainly because it is essential not only for malignant cell growth and metastasis, but also for many other diseases/disorders such as diabetes (type 2), AD (Alzheimer's disease), hypertension, and a variety of inflammatory or infectious diseases, which definitely shorten our lifespan. Moreover, PAK1-deficient mutant of C. elegans lives longer than the wild-type by 60%, clearly indicating that PAK1 is not only an oncogenic but also ageing kinase. Thus, in theory, both anti-oncogenic and longevity-promoting activities are among the "intrinsic" properties or criteria of "clinically useful" PAK1-blockers. There are a variety of PAK1-blocking natural products such as propolis and curcumin which indeed extend the healthy lifespan of small animals such as C. elegans by inducing the autophagy. Recently, we managed to synthesize a series of potent water-soluble and highly cell-permeable triazolyl esters of COOH-bearing PAK1-blockers such as Ketorolac, ARC (artepillin C) and CA (caffeic acid) via "Click Chemistry" that boosts their anti-cancer activity over 500-fold, mainly by increasing their cell-permeability, and one of them called 15K indeed extends the lifespan of C. elegans. In this mini-review we shall discuss both synthetic and natural PAK1-blockers, some of which would be potentially useful for cancer therapy with least side effect (rather promoting the longevity as well).

Oral administration of geranylgeranylacetone to protect vestibular hair cells

OBJECTIVE

We recently reported that the heat shock response played a major role in the protection of hair cells against stress. Oral administration of the heat shock inducer, geranylgeranylacetone (GGA) protected hair cells against intense noise. In our present study, we investigated the effect of GGA on vestibular hair cell death induced by an aminoglycoside.

METHODS

We used CBA/N mice aged 4-6 weeks. The mice were divided into two groups, GGA and control. Mice in the GGA group were fed a diet containing GGA (0.5%) for 4 weeks, and those in the control group were fed a standard diet. Immunohistochemical analyses for Hsp70 were performed in four animals. The utricles of the remaining animals were cultured in medium for 24h with neomycin to induce hair cell death. After fixation, the vestibular hair cells were immunohistochemically stained against calmodulin, and hair cell survival was evaluated.

RESULTS

The vestibular hair cells of mice in the GGA group expressed Hsp70. In addition, after exposure to neomycin, vestibular hair cell survival was higher in the GGA group than in the control group.

CONCLUSION

Our results demonstrated the oral administration of GGA induced the heat shock response in the vestibule and could protect sensory cells.

HSP105 prevents depression-like behavior by increasing hippocampal brain-derived neurotrophic factor levels in mice

Heat shock proteins (HSPs) are stress-induced chaperones that are involved in neurological disease. Although increasingly implicated in behavioral disorders, the mechanisms of HSP action, and the relevant functional pathways, are still unclear. We examined whether oral administration of geranylgeranylacetone (GGA), a known HSP inducer, produced an antidepressant effect in a social defeat stress model of depression in mice. We also investigated the possible molecular mechanisms involved, particularly focusing on hippocampal neurogenesis and neurotrophic factor expression. In stressed mice, hippocampal HSP105 expression decreased. However, administration of GGA increased HSP105 expression and improved depression-like behavior, induced hippocampal cell proliferation, and elevated brain-derived neurotrophic factor (BDNF) levels in mouse hippocampus. Co-treatment with GGA and the BDNF receptor inhibitor K252a suppressed the antidepressant effects of GGA. HSP105 knockdown decreased BDNF mRNA levels in HT22 hippocampal cell lines and hippocampal tissue and inhibited the GGA-mediated antidepressant effect. These observations suggest that GGA administration is a therapeutic candidate for depressive diseases by increasing hippocampal BDNF levels via HSP105 expression.

Targeting chaperones, heat shock factor-1, and unfolded protein response: Promising therapeutic approaches for neurodegenerative disorders

Protein misfolding, which is known to cause several serious diseases, is an emerging field that addresses multiple therapeutic areas. Misfolding of a disease-specific protein in the central nervous system ultimately results in the formation of toxic aggregates that may accumulate in the brain, leading to neuronal cell death and dysfunction, and associated clinical manifestations. A large number of neurodegenerative diseases in humans, including Alzheimer's, Parkinson's, Huntington's, and prion diseases, are primarily caused by protein misfolding and aggregation. Notably, the cellular system is equipped with a protein quality control system encompassing chaperones, ubiquitin proteasome system, and autophagy, as a defense mechanism that monitors protein folding and eliminates inappropriately folded proteins. As the intrinsic molecular mechanisms of protein misfolding become more clearly understood, the novel therapeutic approaches in this arena are gaining considerable interest. The present review will describe the chaperones network and different approaches as the therapeutic targets for neurodegenerative diseases. Current and emerging therapeutic approaches to combat neurodegenerative diseases, addressing the roles of molecular, chemical, and pharmacological chaperones, as well as heat shock factor-1 and the unfolded protein response, are also discussed in detail.

Treatment with Geranylgeranylacetone Induces Heat Shock Protein 70 and Attenuates Neonatal Hyperoxic Lung Injury in a Model of Bronchopulmonary Dysplasia

Purpose

Bronchopulmonary dysplasia (BPD) is a respiratory complication characterized by abnormal alveolar development in premature infants. Geranylgeranylacetone (GGA) can induce heat shock protein (HSP) 70, which has cytoprotective effects against various stressors. Here, we investigated whether GGA protected neonatal lungs from hyperoxic stress in a murine BPD model, and measured the serum HSP70 levels in preterm humans treated with oxygen.

Methods

Newborn mice were exposed to >90% oxygen and administered GGA or vehicle alone orally on days 1, 2, and 3 of life. At 2 days of age, HSP70 expression in the lung was determined by western blotting. At 8 days of age, the lungs were processed for histological analysis. Radial alveolar count (RAC) and mean linear intercept (MLI) were measured as parameters of alveolarization. Apoptosis was evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and cleaved caspase-3 immunohistochemistry. Serum HSP70 levels in preterm humans treated with oxygen were measured by enzyme-linked immunosorbent assay.

Results

GGA administration enhanced the HSP70 expression to two-fold compared with normoxia-exposed and vehicle-treated mice. Hyperoxia reduced HSP70 expression, whereas GGA abrogated the effects. Hyperoxia-exposed mice exhibited more apoptotic cells in lung parenchyma and a more simplified alveolar structure with less RAC and larger MLI than normoxia-exposed mice. GGA suppressed the increase in apoptotic cells and the structural changes of the lungs induced by hyperoxia. Serum HSP70 levels of preterm human infants gradually decreased with age.

Conclusions

GGA may attenuate hyperoxic injury in neonatal lungs and thereby may prevent the development of BPD.

Evaluation of geranylgeranylacetone against cisplatin-induced ototoxicity by auditory brainstem response, heat shock proteins and oxidative levels in guinea pigs

This study aims to assess whether geranylgeranylacetone (GGA) could reduce ototoxicity induced by cisplatin through upregulation of not only heat shock protein(HSP)-70, but also HSP-27 and HSP-40, and to study if GGA would reduce cisplatin-induced increase in oxidative stress. 48 guinea pigs were used in this study and treated with the following regimen: 0.5% CMC (sodium carboxymethyl cellulose) control for 7days, GGA (600mg/kg/d) for 7days, a combination of GGA (600mg/kg) for 7days and then one dose of 10mg/kg cisplatin (GGA+Cis), and a combination of CMC for 7days and then 10mg/kg cisplatin (cisplatin group). Auditory brainstem response (ABR) measurement was performed in each animal at time before treatment and 7days after the last dose. Additionally, HSPs, nitric oxide (NO), and lipid peroxidation (LPO) levels in cochlear membranous tissues were assessed. The mean ABR thresholds in the cisplatin group were significantly (p<0.05) increased when compared to the other three groups. In guinea pigs receiving both GGA and cisplatin, the mean threshold shift (TS) were smaller (p<0.05) than those of the cisplatin group, but larger (p<0.05) than those of the CMC control or GGA only group with statistical significance. Compared to the GGA only group or the group treated with GGA+Cis, the cisplatin group had the highest (p<0.05) oxidative stress (NO and LPO levels), and the lowest (p<0.05) mean HSPs expression levels. It can be concluded that GGA attenuate ototoxicity induced by cisplatin through upregulation of HSP-27, -40, and -70. Moreover, increased oxidative stress induced by cisplatin in the cochlea membranous tissue could be reduced by pre-treatment of GGA.

Targeted delivery of geranylgeranylacetone to mitochondria by triphenylphosphonium modified nanoparticles: a promising strategy to prevent aminoglycoside-induced hearing loss

TPP induced and GGA loaded mitochondria-targeting nanoparticles could efficiently protect hair cells from damage.

The antioxidant N-acetyl cysteine suppresses lidocaine-induced intracellular reactive oxygen species production and cell death in neuronal SH-SY5Y cells

BACKGROUND

The local anesthetic lidocaine can affect intra- and extra-cellular signaling pathways in both neuronal and non-neuronal cells, resulting in long-term modulation of biological functions, including cell growth and death. Indeed, lidocaine was shown to induce necrosis and apoptosis in vitro. While several studies have suggested that lidocaine-induced apoptosis is mitochondrial pathway-dependent, it remains unclear whether reactive oxygen species (ROS) are involved in this process and whether the observed cell death can be prevented by antioxidant treatment.

METHODS

The effects of lidocaine and antioxidants on cell viability and death were evaluated using SH-SY5Y cells, HeLa cells, and HeLa cell derivatives. Cell viability was examined via MTS/PES ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt]/phenazine ethosulfate) assay. Meanwhile, cell apoptosis and necrosis were evaluated using a cell death detection assay with Annexin V-FITC and PI staining, as well as by assaying for caspase-3/7 and caspase-9 activity, and by measuring the release of lactate dehydrogenase, respectively. Mitochondrial transmembrane potential (ΔΨm) was assessed using the fluorescent probe tetramethylrhodamine ethyl ester.

RESULTS

Lidocaine treatment resulted in suppression of the mitochondrial electron transport chain and subsequent attenuation of mitochondrial membrane potential, as well as enhanced ROS production, activation of caspase-3/7 and caspase-9, and induction of apoptosis and necrosis in SH-SY5Y cells in a dose- and time-dependent manner. Likewise, the anesthetics mepivacaine and bupivacaine also induced apoptosis in SH-SY5Y cells. Notably, the antioxidants N-acetyl cysteine (NAC) and Trolox successfully scavenged the mitochondria-derived ROS and suppressed local lidocaine-induced cell death.

CONCLUSIONS

Our findings demonstrate that the local anesthetics lidocaine, mepivacaine, and bupivacaine inhibited the activity of mitochondria and induced apoptosis and necrosis in a dose-dependent manner. Furthermore, they demonstrate that treatment with the antioxidants NAC, Trolox, and GGA resulted in preservation of mitochondrial voltage and inhibition of apoptosis via suppression of caspase activation.

Heat Shock Proteins and Diabetes

Diabetes is a chronic disease, and its prevalence continues to rise and can increase the risk for the progression of microvascular (such as nephropathy, retinopathy and neuropathy) and also macrovascular complications. Diabetes is a condition in which the oxidative stress and inflammation rise. Heat shock proteins (HSPs) are a highly conserved family of proteins that are expressed by all cells exposed to environmental stress, and they have diverse functions. In patients with diabetes, the expression and levels of HSPs decrease, but these chaperones can aid in improving some complications of diabetes, such as oxidative stress and inflammation. (The suppression of some HSPs is associated with a generalized increase in tissue inflammation.) In this review, we summarize the current understanding of HSPs in diabetes as well as their complications, and we also highlight their potential role as therapeutic targets in diabetes.

Geranylgeranylacetone induces apoptosis via the intrinsic pathway in human melanoma cells

The aim of this study was to test the anti-cancer effects of geranylgeranylacetone (GGA), an isoprenoid compound, on human melanoma cells. Human melanoma cell lines G361, SK-MEL-2, and SK-MEL-5 were treated with GGA at various doses (1-100μM). Cell viability was measured by crystal violet assay. Western blot analysis was adopted to detect marker proteins of apoptosis. GGA significantly reduced the viability of G361, SK-MEL-2, and SK-MEL-5 human melanoma cells at concentrations above 10μM. Western blot analysis showed the phosphorylation of p38 MAPK and c-Jun N-terminal kinase (JNK) after GGA treatment, as well as activation of caspase-9, caspase-3, and poly(ADP-ribose) polymerase (PARP) cleavage. GGA also induced p53 and Bax expression, but did not affect expression of Bcl-2 and MITF. These findings suggest that GGA induces apoptosis through the intrinsic pathway. Accordingly, GGA should be considered for further development as a potential agent for melanoma.

The human HSP70 family of chaperones: where do we stand?

The 70-kDa heat shock protein (HSP70) family of molecular chaperones represents one of the most ubiquitous classes of chaperones and is highly conserved in all organisms. Members of the HSP70 family control all aspects of cellular proteostasis such as nascent protein chain folding, protein import into organelles, recovering of proteins from aggregation, and assembly of multi-protein complexes. These chaperones augment organismal survival and longevity in the face of proteotoxic stress by enhancing cell viability and facilitating protein damage repair. Extracellular HSP70s have a number of cytoprotective and immunomodulatory functions, the latter either in the context of facilitating the cross-presentation of immunogenic peptides via major histocompatibility complex (MHC) antigens or in the context of acting as "chaperokines" or stimulators of innate immune responses. Studies have linked the expression of HSP70s to several types of carcinoma, with Hsp70 expression being associated with therapeutic resistance, metastasis, and poor clinical outcome. In malignantly transformed cells, HSP70s protect cells from the proteotoxic stress associated with abnormally rapid proliferation, suppress cellular senescence, and confer resistance to stress-induced apoptosis including protection against cytostatic drugs and radiation therapy. All of the cellular activities of HSP70s depend on their adenosine-5'-triphosphate (ATP)-regulated ability to interact with exposed hydrophobic surfaces of proteins. ATP hydrolysis and adenosine diphosphate (ADP)/ATP exchange are key events for substrate binding and Hsp70 release during folding of nascent polypeptides. Several proteins that bind to distinct subdomains of Hsp70 and consequently modulate the activity of the chaperone have been identified as HSP70 co-chaperones. This review focuses on the regulation, function, and relevance of the molecular Hsp70 chaperone machinery to disease and its potential as a therapeutic target.

Geranylgeranylacetone alleviates radiation-induced lung injury by inhibiting epithelial-to-mesenchymal transition signaling

Radiation-induced lung injury (RILI) involves pneumonitis and fibrosis, and results in pulmonary dysfunction. Moreover, RILI can be a fatal complication of thoracic radiotherapy. The present study investigated the protective effect of geranylgeranlyacetone (GGA), an inducer of heat shock protein (HSP)70, on RILI using a C57BL/6 mouse model of RILI developing 6 months subsequent to exposure to 12.5 Gy thoracic radiation. GGA was administered 5 times orally prior and subsequent to radiation exposure, and the results were assessed by histological analysis and western blotting. The results show that late RILI was alleviated by GGA treatment, possibly through the suppression of epithelial‑to‑mesenchymal transition (EMT) marker expression. Based on histological examination, orally administered GGA during the acute phase of radiation injury not only significantly inhibited pro‑surfactant protein C (pro‑SPC) and vimentin expression, but also preserved E‑cadherin expression 6 months after irradiation‑induced injury of the lungs. GGA induced HSP70 and inhibited EMT marker expression in L132 human lung epithelial cells following IR. These data suggest that the prevention of EMT signaling is a key cytoprotective effect in the context of RILI. Thus, HSP70‑inducing drugs, such as GGA, could be beneficial for protection against RILI.

Hsp70 Knockdown by siRNA Decreased Collagen Production in Keloid Fibroblasts

PURPOSE

There are currently no consistently effective treatments for the excessive collagen produced by keloid fibroblasts. Previously, we reported that heat shock protein 70 (Hsp70) is up-regulated in keloid fibroblasts and keloid tissue. We, therefore, investigated whether Hsp70 is related to excessive collagen production in keloid fibroblasts.

MATERIALS AND METHODS

We inhibited Hsp70 in keloid fibroblasts by RNA interference and examined the resulting collagen expression. Thus, we selected small interfering RNAs (siRNAs) specific for human Hsp70, transfected them into keloid fibroblasts, and evaluated the resulting phenotypes and protein production using real-time polymerase chain reaction (PCR), Western blot, and a collagen assay.

RESULTS

The siRNAs dramatically suppressed Hsp70 mRNA expression, resulting in a decrease in collagen production in the keloid fibroblasts compared with controls. The siRNAs did not influence the viability of the keloid fibroblasts.

CONCLUSION

Hsp70 overexpression likely plays an important role in the excessive collagen production by keloid fibroblasts. RNA interference has therapeutic potential for the treatment of keloids.

Structure-activity analysis and antiprion mechanism of isoprenoid compounds

The prion strain-specific mechanism by which normal prion protein is converted to abnormal prion protein remains largely unknown. This study found that insect juvenile hormone III reduced abnormal prion protein levels only in cells infected with the RML prion. We conducted a structure-activity analysis using juvenile hormone III biosynthetic intermediates in the isoprenoid pathway. Both farnesol and geranylgeraniol, the most potent inhibitors of abnormal prion protein formation, behaved in an RML prion-dependent fashion. Neither of them modified cellular and cell surface prion protein levels. Events downstream of this pathway include cholesterol biosynthesis and protein prenylation. However, neither of these isoprenoid compounds modified lipid raft microdomains and cellular cholesterol levels and neither affected the representative prenylated protein expression levels of prenylation pathways. Therefore, these isoprenoid compounds are a new class of prion strain-dependent antiprion compounds. They are useful for exploring strain-specific prion biology.

Geranylgeranylacetone selectively binds to the HSP70 of Helicobacter pylori and alters its coccoid morphology

Geranylgeranylacetone (GGA) is used to treat patients suffering from peptic ulcers and gastritis. We examined the effect of GGA on Helicobacter pylori, which is a causative factor of gastrointestinal diseases. Previously, we have reported that GGA binds specifically to the molecular chaperone HSP70. In this paper, we report that GGA bounds to H. pylori HSP70 (product of the DnaK gene) with 26-times higher affinity than to human HSP70, and induced large conformational changes as observed from surface plasmon resonance and circular dichroism. Binding of GGA suppressed the activity of the H. pylori chaperone. GGA also altered several characteristics of H. pylori cells. GGA-treated cells elicited enhanced interleukin-8 production by gastric cancer cell lines and potentiated susceptibility to complement as compared to untreated cells. GGA also caused morphological alterations in H. pylori as reflected in fewer coccoid-like cells, suggesting that GGA converts H. pylori to an actively dividing, spiral state (vegetative form) from a non-growing, coccoid state. This morphological conversion by GGA resulted in accelerated growth of H. pylori. These results suggest a model in which GGA sensitizes H. pylori to antibiotic treatment by converting the cells to an actively growing state.

Anthocyanin-rich tea Sunrouge upregulates expressions of heat shock proteins in the gastrointestinal tract of ICR mice: A comparison with the conventional tea cultivar Yabukita

Sunrouge is an anthocyanin-rich, new tea cultivar that contains similar levels of catechins as Yabukita, the most popular tea cultivar consumed in Japan. Interestingly, Sunrouge preparations have previously been shown to have more pronounced acetylcholinesterase inhibitory and anticolitis activities than those of Yabukita. In this study, we examined their effects on expressions of self-defensive molecules, including heat shock proteins (HSPs), which are molecular chaperones involved in homeostasis and longevity. Hot water extract from freeze-dried Sunrouge significantly upregulated messenger RNA (mRNA) expressions of HSP40, HSP70, and HSP32 (heme oxygenase-1), with grades greater than those shown by Yabukita. Oral administration of freeze-dried preparation of Sunrouge to male ICR mice at a dose of 1% in the basal diet for 1 month resulted in marked upregulations of several HSP mRNA expressions in mucosa from the gastrointestinal tract, especially the upper small intestine. Again, its efficacy was remarkably higher than that of Yabukita. Moreover, exposure of Caenorhabditis elegans to Sunrouge conferred thermoresistant phenotype, and also resulted in a significant life-span elongation. Taken together, our results suggest that Sunrouge is a unique and promising tea cultivar for regulating self-defense systems.