Downregulation Of Hsp70 Research Articles

Skin equivalent tensional force alters keloid fibroblast behavior and phenotype.

Skin tension may influence keloid scar behavior, development, and spreading, e.g., butterfly-shaped keloid disease in the sternum. Here, we developed a three-dimensional (3D) in vitro model to mimic in vivo tension and evaluate keloid fibroblast (KF) behavior and extracellular matrix synthesis under tension. In vivo skin tension measured in volunteers (n = 4) using 3D image photogrammetry enabled prediction of actual force (35 mN). A novel cell force monitor applied tension in a fibroblast-populated 3D collagen lattice replicating the in vivo force. The effect of tension on keloid (n = 10) fibroblast (KF) and normal skin (n = 10) fibroblasts (NF) at set time points (6, 12, and 24 hours) was measured in Hsp27, PAI-2, and α2β1 integrin, tension-related genes demonstrating significant (p < 0.05) time-dependent regulation of these genes in NF vs. KF with and without tension. KF showed higher (p < 0.05) proliferation post-tension. Knockdown of all three genes in 24 and 48 hours with and without tension showed significant down-regulation in NF vs. KF. Additionally, we show significant (p < 0.05) modification of the expression of extracellular matrix-related genes post-tension following down-regulation of Hsp27, PAI-2, or α2β1 integrin. Finally, we demonstrate significant alteration in NF compared with KF morphology following knockdown. In conclusion, this study shows induction of tension-related genes expression following mechano-regulation in KFs, with potential relevance to its development and therapy.

Proteomics research of bufalin-induced apoptosis in osteosarcoma cell lines

To study the apoptosis inducing effects of bufalin on various human osteosarcoma cells and the concerning molecular mechanisms. MTT assay was used to detect the growth inhibition rates of osteosarcoma cells U-20S, U-20S/MTX300, SaOS-2, IOR/OS9 treated with bufalin in different concentrations and times. The apoptosis of cells was observed flow cytometry 48 h following bufalin treatment. The proteomic techniques were used to separate and compare the treated and control groups 48 h after bufalin-incubation. Then, the proteomic results were validated by western blot. Bufalin inhibited the growth of human osteosarcoma cells U20S, U20S/MTX300 (methotrexate resistant cells), SAOS2, IOR/OS9 in a dose- and time-dependent manner. The 72 h IC50 were (37.43 +/- 4.1), (32.24 +/- 5.3) nmol x L(-1) in U20S,U20S/MTX300 cells,respectivly. Flow cytometry showed that the apoptosis cells were increased following bufalin treatment. The protein expression profile showed 24 differentiated expression proteins. Among these proteins, the level of an anti-apoptotic protein, heat shock protein 27 (Hsp27) decreased significantly and the result was then validated by western blot. Ectopic expression of Hsp27 could reduce the bufalin-induced apoptosis remarkably in U20S and U20S/MTX300 cells. Bufalin could inhibit the cell growth and induce apoptosis on human osteosarcoma cells. The effect of bufalin may be related to the joint intervention with multiple protein targets. Among them, downregulation of Hsp27 plays a critical role in the bufalin-induced apoptosis in human osteosarcoma cells.

Disturbed Hsp70 and Hsp27 expression and thiol redox status in porcine kidney PK15 cells provoked by individual and combined ochratoxin A and citrinin treatments

The aim of this study was to explore the oxidative properties of ochratoxin A (OTA) and citrinin (CTN) as a possible underlying mechanism of their individual and/or combined cytotoxicity. Metabolic activity of PK15 porcine kidney cells was significantly reduced with OTA and CTN co-exposures, with synergistic cytotoxic interactions. Single CTN increased both reduced (GSH) and oxidized (GSSG) glutathione after 24h. However, GSH was significantly lowered with all OTA and CTN combined applications in synergistic manner after 12 and 24h. GSH/GSSG ratio was reduced in most single and dual treatments, which suggested the presence of oxidative stress. In addition, OTA and CTN exposures significantly decreased concentrations of total thiols, with mycotoxins interactions being synergistic or antagonistic. The expression levels of Hsps were differentially affected by single and dual mycotoxin(s) applications. Single OTA provoked significant down-regulation of Hsp70 and Hsp27 expressions, while CTN stimulated Hsps expressions. Hsps were also up-regulated by dual treatments, and this induction was much stronger then with single CTN. In conclusion, significant alterations in cellular redox status (glutathione, thiols) and protective mechanisms (Hsps) suggest that those disturbances might be involved in OTA and CTN individual and combined mechanisms of cytotoxicity.

Microarray analysis for the influence of CMV infection on tomato genomes (617.1)

Functional genomics is the study of gene function through parallel expression measurements of a genome. The most common tools used to carry out these measurements include complementary DNA microarrays, oligonucleotide microarrays or serial analysis of gene expression (SAGE)3. A custom‐designed Affymetrix tomato GeneChip array was used to study the gene expression changes in response to viral inoculation with a mild and severe CMV strains. The basic technique involves extraction of RNA from tomato leaf samples and then copied, while incorporating either fluorescent nucleotides or a tag that is later stained with fluorescence. Labeled RNA is then hybridized to a microarray for a period of time, then excess is washed off and the microarray is scanned under laser light. Different expression responses were resulted due to the type of viral infection.Total number of expressed genes were 3213, Out of this 1660 genes were down‐regulated and 1553 were up‐regulated. The response to CMV‐16 infection led to 1365 gene expression, 642 were down‐regulated and 723 genes were up‐regulated Specific seven different genes in tomato genome (Hsp70,ChMDH, Wif1, rccr, AAP2, PIIF &amp; GAPDH endogenous gene used as a control) were analyzed and resulted in down regulation of Hsp70 and upper regulation of both ChMDH and PIIF. Gene expression results were confirmed with relative quantitative RT‐PCR technology.

Gene expression during imidacloprid-induced hormesis in green peach aphid.

Imidacloprid-induced hormesis in the form of stimulated reproduction has previously been reported in green peach aphid, Myzus persicae. Changes in gene expression accompanying this hormetic response have not been previously investigated. In this study, expression of stress response (Hsp60), dispersal (OSD, TOL and ANT), and developmental (FPPS I) genes were examined for two generations during imidacloprid-induced reproductive stimulation in M. persicae. Global DNA methylation was also measured to test the hypothesis that changes in gene expression are heritable. At hormetic concentrations, down-regulation of Hsp60 was followed by up-regulation of this gene in the subsequent generation. Likewise, expression of dispersal-related genes and FPPS I varied with concentration, life stage, and generation. These results indicate that reproductive hormesis in M. persicae is accompanied by a complex transgenerational pattern of up- and down-regulation of genes that likely reflects trade-offs in gene expression and related physiological processes during the phenotypic dose-response. Moreover, DNA methylation in second generation M. persicae occurred at higher doses than in first-generation aphids, suggesting that heritable adaptability to low doses of the stressor might have occurred.

Ultrasound Targeted Microbubble Destruction for Novel Dual Targeting of HSP72 and HSC70 in Prostate Cancer

The aim was to determine whether ultrasound targeted microbubble destruction (UTMD) promotes dual targeting of HSP72 and HSC70 for therapy of castration-resistant prostate cancer (CRPC), to improve the specific and efficient delivery of siRNA, to induce tumor cell specific apoptosis, and to find new therapeutic targets specific of CRPC.VCaP cells were transfected with siRNA oligonucleotides. HSP70, HSP90 and cleaved caspase-3 expression were determined by real-time quantitative polymerase chain reaction and Western blotting. Apoptosis and transfection efficiency were assessed by flow cytometry. Cell viability assays were used to evaluate safety. We found HSP72, HSC70 and HSP90 expression to be absent or weak in normal prostate epithelial cells (RWPE-1), but uniformly strong in prostate cancerous cells (VCaP). UTMD combined with dual targeting of HSP72 and HSC70 siRNA improve the efficiency of transfection, cell uptake of siRNA, downregulation of HSP70 and HSP90 expression in VCaP cells at the mRNA and protein level, and induction of extensive tumor-specific apoptosis. Cell counting kit-8 assays showed decreased cellular viability in the HSP72/HSC70-siRNA silenced group. These results suggest that the combination of UTMD with dual targeting HSP70 therapy for PCa may be most efficacious, providng a novel, reliable, non-invasive, safe targeted approach to improve the specific and efficient delivery of siRNA, and achieve maximal effects.

Ibuprofen enhances the anticancer activity of cisplatin in lung cancer cells by inhibiting the heat shock protein 70

Hsp70 is often overexpressed in cancer cells, and the selective cellular survival advantage that it confers may contribute to the process of tumour formation. Thus, the pharmacological manipulation of Hsp70 levels in cancer cells may be an effective means of preventing the progression of tumours. We found that the downregulation of Hsp70 by ibuprofen in vitro enhances the antitumoural activity of cisplatin in lung cancer. Ibuprofen prominently suppressed the expression of Hsp70 in A549 cells derived from lung adenocarcinoma and sensitized them to cisplatin in association with an increase in the mitochondrial apoptotic cascade, whereas ibuprofen alone did not induce cell death. The cisplatin-dependent events occurring up- and downstream of mitochondrial disruption were accelerated by treatment with ibuprofen. The increase in cisplatin-induced apoptosis caused by the depletion of Hsp70 by RNA interference is evidence that the increased apoptosis by ibuprofen is mediated by its effect on Hsp70. Our observations indicate that the suppression of Hsp70 by ibuprofen mediates the sensitivity to cisplatin by enhancing apoptosis at several stages of the mitochondrial cascade. Ibuprofen, therefore, is a potential therapeutic agent that might allow lowering the doses of cisplatin and limiting the many challenge associated with its toxicity and development of drug resistance.

Dexamethasone induces heat shock response and slows down disease progression in mouse and fly models of Huntington's disease

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by abnormal expansion of glutamine repeats in the protein huntingtin. In HD brain, mutant huntingtin undergoes proteolytic processing, and its N-terminal fragment containing poly-glutamine repeats accumulate as insoluble aggregates leading to the defect in cellular protein quality control system and heat shock response (HSR). Here we demonstrate that the defective HSR in the brain is due to the down-regulation of heat shock factor 1 (HSF1) in both mice and fly models of HD. Interestingly, treatment of dexamethasone (a synthetic glucocorticoid) to HD mice or flies significantly increased the expression and transactivation of HSF1 and induction of HSR and these effects are mediated through the down-regulation of HSP90. Dexamethasone treatment also significantly decreased the aggregate load and transient recovery of HD-related behavioural phenotypes in both disease models. These results suggest that dexamethasone could be a potential therapeutic molecule for the treatment of HD and related poly-glutamine disorders.

Water Soluble &lt;i&gt;Pleurotus ostreatus&lt;/i&gt; Polysaccharide Down-Regulates the Expression of MMP-2 and MMP-9 in Caco-2 Cells

Many polysaccharides and polysaccharide-protein complexes isolated from mushrooms have immunomodulatory and anti-cancer effects. Our aim was to study the regulatory mechanisms of Caco-2 cell response to water soluble P. ostreatus polysaccharide extract up to 72 hours. Specific enzymatic activities were assessed by kinetic measurements. The reduced glutathione content and the lipid peroxidation level were also analyzed. Protein expression of several heat shock proteins, Bcl-2 and metalloproteinases 2 and 9 were revealed by Western blot. Gelatin zymography assay was used to evaluate the MMP-2 and MMP-9 activities. Until the third day of exposure the total SOD activity decreased continuously by 30%, whereas GST and GR ones diminished by 17% respectively 30.5% compared to control. No significant changes were observed in CAT and G6PDH specific activities as well as in GSH and MDA concentration. After the third day of exposure a significant up-regulation of Hsp60 and Hsp90 expression and a down-regulation of Hsp70 one were registered. Bcl-2 protein levels were down-regulated by 50% in the first day of treatment but increased after 3 days. MMP-2 and 9 secretion in the culture medium was significantly reduced suggesting a diminished ability of invasion of colon cancer cells. Our data revealed that in vitro treatment with P. ostreatus aqueous polysaccharide extract does not induce apoptosis in Caco-2 cell line but it could inhibit the invasion of colon cancer cells through the basement membrane.

Pro-inflammatory cytokines downregulate Hsp27 and cause apoptosis of human retinal capillary endothelial cells

The formation of acellular capillaries in the retina, a hallmark feature of diabetic retinopathy, is caused by apoptosis of endothelial cells and pericytes. The biochemical mechanism of such apoptosis remains unclear. Small heat shock proteins play an important role in the regulation of apoptosis. In the diabetic retina, pro-inflammatory cytokines are upregulated. In this study, we investigated the effects of pro-inflammatory cytokines on small heat shock protein 27 (Hsp27) in human retinal endothelial cells (HREC). In HREC cultured in the presence of cytokine mixtures (CM), a significant downregulation of Hsp27 at the protein and mRNA level occurred, with no effect on HSF-1, the transcription factor for Hsp27. The presence of high glucose (25mM) amplified the effects of cytokines on Hsp27. CM activated indoleamine 2,3-dioxygenase (IDO) and enhanced the production of kynurenine and ROS. An inhibitor of IDO, 1-methyl tryptophan (MT), inhibited the effects of CM on Hsp27. CM also upregulated NOS2 and, consequently, nitric oxide (NO). A NOS inhibitor, L-NAME, and a ROS scavenger blocked the CM-mediated Hsp27 downregulation. While a NO donor in the culture medium did not decrease the Hsp27 content, a peroxynitrite donor and exogenous peroxynitrite did. The cytokines and high glucose-induced apoptosis of HREC were inhibited by MT and L-NAME. Downregulation of Hsp27 by a siRNA treatment promoted apoptosis in HREC. Together, these data suggest that pro-inflammatory cytokines induce the formation of ROS and NO, which, through the formation of peroxynitrite, reduce the Hsp27 content and bring about apoptosis of retinal capillary endothelial cells.

Lens specific RLIP76 transgenic mice show a phenotype similar to microphthalmia

RALBP1/RLIP76 is a ubiquitously expressed protein, involved in promotion and regulation of functions initiated by Ral and R-Ras small GTPases. Presence of multiple domains in its structure enables RLIP76 to be involved in a number of physiological processes such as endocytosis, exocytosis, mitochondrial fission, actin cytoskeleton remodeling, and transport of exogenous and endogenous toxicants. Previously, we have established that RLIP76 provides protection to ocular tissues against oxidative stress by transporting the glutathione-conjugates of the toxic, electrophilic products of lipid peroxidation generated during oxidative stress. Therefore, we developed lens specific RLIP76 transgenic mice (lensRLIP76 Tg) to elucidate the role of RLIP76 in protection against oxidative stress, but these transgenic mice showed impaired lens development and a phenotype with small eyes similar to that observed in microphthalmia. These findings prompted us to investigate the mechanisms via which RLIP76 affects lens and eye development. In the present study, we report engineering of lensRLIP76 Tg mice, characterization of the associated phenotype, and the possible molecular mechanisms that lead to the impaired development of eye and lens in these mice. The results of microarray array analysis indicate that the genes involved in pathways for G-Protein signaling, actin cytoskeleton reorganization, endocytosis, and apoptosis are affected in these transgenic mice. The expression of transcription factors, Pax6, Hsf1, and Hsf4b known to be involved in lens development is down regulated in the lens of these Tg mice. However, the expression of heat shock proteins (Hsps), the downstream targets of Hsfs, is differentially affected in the lens showing down regulation of Hsp27, Hsp40, up regulation of Hsp60, and no effect on Hsp70 and Hsp90 expression. The disruption in the organization of actin cytoskeleton of these Tg mice was associated with the inhibition of the activation of Cdc42 and down regulation of cofilin phosphorylation. These mice may provide useful animal model for elucidating the mechanisms of lens development, and etiology of microphthalmia.

Downregulation of Hsp70 inhibits apoptosis induced by sialic acid-binding lectin (leczyme)

Heat shock proteins (Hsps) are molecular chaperones that maintain homeostasis of organisms. In regards to the Hsps, many studies have investigated the structure, expression, localization and functions of Hsp70 and Hsc70 including expression in the glycosphingolipid-enriched microdomain (GEM) on the cell surface and involvement in cell death. Sialic acid-binding lectin (SBL) isolated from oocytes of Rana catesbeiana is a multifunctional protein which has lectin activity, ribonuclease activity and antitumor activity. SBL has potential as a new type of anticancer drug, since it causes cancer-selective induction of apoptosis by multiple signaling pathways in which RNA is its target; and the participation of the mitochondrial pathway and the endoplasmic reticulum (ER) stress-mediated pathway has been suggested. It has also been suggested that receptor(s) for SBL (SBLR) may exist in the GEM on the cell surface. In the present study, we studied the possible involvement of Hsp70 and Hsc70 in SBL-induced apoptosis. We showed that Hsp70 and Hsc70 were expressed on the P388 cell surface similar to SBLR, and their distribution in cells dramatically changed immediately prior to the execution of apoptosis following stimulation of SBL. Functional study of Hsp70 revealed that decreased expression of Hsp70 diminished the apoptosis induced by SBL. It is suggested that Hsp70 participates in the antitumor effect of SBL.

Trigonelline isolated from fenugreek seed protects against isoproterenol-induced myocardial injury through down-regulation of Hsp27 and αB-crystallin

ObjectiveProtective effects of trigonelline (TRG) isolated from fenugreek seed were evaluated in isoproterenol (ISO)-induced myocardial dysfunctions in adult rats and a proteomic approach was applied to understand its mechanism of action. MethodsIn a preliminary experiment, effects of TRG at 20, 40, and 80 mg/kg for 20 d were studied in ISO-induced (100 mg/kg) adult rats. As 40 mg/kg was found the most effective concentration, in the final experiment, effects of 40 mg/kg of the test drug were investigated using different indices including cardiac marker enzymes, lipid peroxidation, antioxidants, cardiac histology, and electrocardiogram. Proteomic analyses were also done in cardiac myocytes. ResultsISO administration increased serum levels of cardiac markers (creatine kinase-MB, glutamate pyruvate transaminase, and lactate dehydrogenase) and exhibited a positive reaction in the TROP-T test. It also increased the cardiac lipid peroxidation and decreased the cellular antioxidants. Proteomic data revealed nine protein spots, seven were down-regulated and two up-regulated. The overexpressions of two small stress proteins, heat shock protein (Hsp)27 and αB crystallin were confirmed by Western blot analysis. All these alterations were restored to nearly normal values in 40 mg/kg of TRG-pretreated animals, suggesting its cardioprotective effects, which were further confirmed by histologic examinations and triphenyl tetrazolium chloride staining assay. ConclusionFor the first time, our study revealed the down-regulation of Hsp27 and αB-crystallin and (CaMKII delta) isoform by TRG. As the test compound prevented the ISO-induced myocardial injury, its therapeutic use may further be explored.

Identification of differentially expressed proteins by treatment with PUGNAc in 3T3-L1 adipocytes through analysis of ATP-binding proteome

O-GlcNAc (2-acetamino-2-deoxy-β-D-glucopyranose), an important modification for cellular processes, is catalyzed by O-GlcNAc transferase and O-GlcNAcase. O-(2-acetamido-2-deoxy-D-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc) is a nonselective inhibitor of O-GlcNAcase, which increases the level of protein O-GlcNAcylation and is known to induce insulin-resistance in adipose cells due to uncharacterized targets of this inhibitor. In this study, using ATP affinity chromatography, we applied a targeted proteomic approach for identification of proteins induced by treatment with PUGNAc. For optimization of proteomic methods using ATP affinity chromatography, comparison of two cell lines (3T3-L1 adipocytes and C2C12 myotubes) and two different digestion steps was performed using four different structures of immobilized ATP-bound resins. Using this approach, based on DNA sequence homologies, we found that the identified proteins covered almost half of ATP-binding protein families classified by PROSITE. The optimized ATP affinity chromatography approach was applied for identification of proteins that were differentially expressed in 3T3-L1 adipocytes following treatment with PUGNAc. For label-free quantitation, a gel-assisted method was used for digestion of the eluted proteins, and analysis was performed using two different MS modes, data-independent (671 proteins identified) and data-dependent (533 proteins identified) analyses. Among identified proteins, 261 proteins belong to nucleotide-binding proteins and we focused on some nucleotide-binding proteins, ubiquitin-activation enzyme 1 (E1), Hsp70, vasolin-containing protein (Vcp), and Hsp90, involved in ubiquitin-proteasome degradation and insulin signaling pathways. In addition, we found that treatment with PUGNAc resulted in increased ubiquitination of proteins in a time-dependent manner, and a decrease in both the amount of Akt and the level of phosphorylation of Akt, a key component in insulin signaling, through downregulation of Hsp90. In this study, based on a targeted proteomic approach using ATP affinity chromatography, we found four proteins related to ubiquitination and insulin signaling pathways that were induced by treatment with PUGNAc. This result would provide insight into understanding functions of PUGNAc in 3T3-L1 cells.

Hsp70 positively regulates porcine circovirus type 2 replication in vitro

The Hsp70 chaperone plays a central role in multiple processes within cells. Porcine circovirus type 2 (PCV2) is the essential causal agent of post-weaning multisystemic wasting syndrome (PMWS), which has spread worldwide. But the mechanism of PCV2 replication remains poorly understood. In this study, we firstly found the positive effect of heat stress on the replication of PCV2 in the continuous porcine monocytic cell line 3D4/31. Downregulation of Hsp70 by the specific chaperone inhibitor Quercetin or RNA interference and upregulation of Hsp70 by expression from a recombinant adenovirus showed that Hsp70 enhanced PCV2 genome replication and virion production. A specific interaction between Hsp70 and PCV2 Cap was confirmed by colocalization by confocal microscopy and co-immunoprecipitation. Furthermore, the NF-κB pathway was activated and caspase-3 activity was reduced when Hsp70 was overexpressed in PCV2-infected 3D4/31 cells. These data suggested that Hsp70 positively regulated PCV2 replication, which being helpful for understanding the molecular mechanism of PCV2 infection.

Pro‐inflammatory cytokines induce apoptosis of human retinal capillary endothelial cells through downregulation of Hsp27

AbstractPurpose Retinal capillary cells undergo apoptosis in diabetes, but the mechanism is not clear. Pro‐inflammatory cytokines are upregulated in the diabetic retina of humans and rodents. In this study, we have investigated the effect if pro‐inflammatory cytokines on a small heat shock protein, Hsp27 in human retinal endothelial cells (HREC)Methods HREC were cultured in the presence of pro‐inflammatory cytokines, interferon ‐γ (IFN‐γ, 50 and 100 units/ml), interleukin‐1β (IL‐1β, 10 and 20 ng/ml) and tumor necrosis factor‐α (TNF‐α, 10 and 20 ng/ml) for 48 hrs and in the presence or absence of high glucose (25 mM, HG). The roles of the kynurenine pathway and NOS were determined by adding 20 μM 1‐methyl tryptophan (MT) and 500 μM L‐Nω‐nitroarginine methyl ester hydrochloride (L‐NAME), respectively to the culture medium.Results HREC cultured in the presence of mixed cytokines showed a significant downregulation of Hsp27 at the protein and mRNA levels. This downregulation was not due to downregulation of the transcription factor, HSF‐1. Mixed cytokines activated indoleamine 2,3‐dioxygenase (IDO), enhanced kynurenine production and increased the ROS content in HREC. MT inhibited the effects of mixed cytokines on Hsp27. Mixed cytokines upregulated NOS2 and increased levels of NO. A peroxynitrite donor and exogenous peroxynitrite drastically reduced Hsp27. The cytokine and HG‐mediated downregulation of Hsp27 was accompanied by increased apoptosis of HRECConclusion Our data suggest that pro‐inflammatory cytokines induce ROS and NO formation, which through peroxynitrite production reduce Hsp27 and bring about apoptosis of HREC. These results suggest a novel mechanism for capillary cell death in diabetic retinopathy.

Abstract B16: Phenotypic plasticity in the EML cell culture system as a result of HSP90 inhibition

Abstract The process of canalization whereby phenotypic traits are buffered against stochastic fluctuations to preserve the evolutionarily advantageous “normal” level can be potentially exploited during cancer progression. Release of canalization through pharmacologic or genetic down-regulation of Hsp90 removes this buffer and increases variation, allowing for rapid changes in traits as evidenced in Drosophila, Arabidopsis, and maize. If cancer is viewed as a Darwinian struggle of the premalignant cell to acquire the hallmarks of a fully malignant cell or be extinguished, then increasing variation or heterogeneity has a beneficial effect on the fitness of the premalignant cell. It is the goal of this work to test the hypothesis that Hsp90-derived canalization, though its ability to buffer phenotypic variance and thus reduce cell plasticity, is involved in hematopoietic cell differentiation. Furthermore, we wish to determine if the canalization mechanism has an epigenetic component. We are currently using a murine hematopoietic stem cell culture system, EML cells, to investigate this hypothesis. EML cells have been induced to differentiate into macrophage and granulocyte lineages with and without pharmacologic inhibition of HSP90 through 17-AAG. We found that 17-AAG treatment increases the ability of these differentiating cells to survive in a selective medium, during culturing conditions that suggest an epigenetic mechanism. If our hypothesis is true, then loss of canalization could be a potentially powerful mechanism driving cancer progression. Fully understanding the mechanism involved would allow for new therapeutic insights and provide vital information regarding the use of HSP90 inhibitors. Citation Format: Jennifer Napper, Vincent E. Sollars. Phenotypic plasticity in the EML cell culture system as a result of HSP90 inhibition. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B16.

Anticancer Potential of Myricanone, a Major Bioactive Component of Myrica cerifera: Novel Signaling Cascade for Accomplishing Apoptosis

Extract of Myrica cerifera bark has long been fruitfully used as a hepato-protective and anti-cancer drug in various complementary and alternative systems of medicine. Myricanone, its principal bioactive compound, had also been reported to have apoptosis-promoting ability. We evaluated its anti-cancer potential in vitro in HepG2 liver cancer cells and tried to understand the signal cascades involved in accomplishing apoptosis. Further, we ascertained by using a (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay (MTT) assay if it had cytotoxic effects on normal noncancerous liver cells (WRL-68). We deployed various tools and protocols, like phase contrast, scanning electron and fluorescence microscopies, performed an annexinV-FITC/PI assay and cell cycle analysis, and estimated the reactive oxygen species (ROS) generation and mitochondrial membrane depolarization through flow cytometry. Further, analyses of cytochrome-c translocation and of HSP70 and caspase expressions were also done by using immunoblota and Enzyme linked immunosorbent assay (ELISA). Results revealed that myricanone induced apoptosis in HepG2 cells through generation of ROS, depolarization of the mitochondrial membrane, early release of cytochrome-c, down-regulation of HSP70 and activation of a caspase cascade; it had no, or insignificant, cytotoxic effects in WRL-68 cells in vitro and in mice in vivo. Thus, myricanone has great potential for use in formulating an effective drug against both hepatotoxicity and hepatocellular cancer.

S-nitroso-N-acetylcysteine attenuates liver fibrosis in experimental nonalcoholic steatohepatitis

S-Nitroso-N-acetylcysteine (SNAC) is a water soluble primary S-nitrosothiol capable of transferring and releasing nitric oxide and inducing several biochemical activities, including modulation of hepatic stellate cell activation. In this study, we evaluated the antifibrotic activity of SNAC in an animal model of nonalcoholic steatohepatitis (NASH) induced in Sprague-Dawley rats fed with a choline-deficient, high trans fat diet and exposed to diethylnitrosamine for 8 weeks. The rats were divided into three groups: SNAC, which received oral SNAC solution daily; NASH, which received the vehicle; and control, which received standard diet and vehicle. Genes related to fibrosis (matrix metalloproteinases [MMP]-13, -9, and -2), transforming growth factor β-1 [TGFβ-1], collagen-1α, and tissue inhibitors of metalloproteinase [TIMP-1 and -2] and oxidative stress (heat-shock proteins [HSP]-60 and -90) were evaluated. SNAC led to a 34.4% reduction in the collagen occupied area associated with upregulation of MMP-13 and -9 and downregulation of HSP-60, TIMP-2, TGFβ-1, and collagen-1α. These results indicate that oral SNAC administration may represent a potential antifibrotic treatment for NASH.

Abstract 197: Emerging Role of Toll-like Receptor 4 and Heat Shock Protein 60&amp;70 in Ischaemia-Induced Skeletal Muscle Damage In Vitro

OBJECTIVES The innate immune response contributes to the skeletal muscle damage in patients with critical limb ischaemia (CLI); however, the detailed signaling mechanisms are not fully understood. We hypothesized that simulated ischaemia induces inflammatory cytokine release from skeletal myotubes, via a mechanism that involves heat shock protein (HSP) 60&amp;70, known endogenous ligands of Toll-like receptor 4 (TLR4), in vitro. METHODS Human gastrocnemius muscle biopsies were taken from patients with CLI undergoing major lower limb amputation and from patients with no peripheral arterial disease (PAD). Human myoblasts were isolated, cultured to myotubes and then pre-treated with TLR4 neutralizing antibody prior to exposure to simulated ischaemia. Fluorescent immunostaining was carried out to confirm cell differentiation; ELISA analysis were carried out to quantify IL6 and TNF-α release; and Western blot was used to assess expression of HSP60&amp;70, TLR4 and cleaved caspase-3 as a marker of apoptosis. RESULTS Myotubes from patients with CLI expressed greater levels of cleaved caspase-3 and TLR4 as compared to those from patients with no PAD. When exposed to ischaemic conditions, increased IL6 and TNF-α release and upregulation of HSP60&amp;70, cleaved caspase-3 and TLR4 were observed in myotubes from both groups of patients compared to culturing in normoxic conditions (P&lt;0.05). Pre-treatment of myotubes from patients with CLI with TLR4 neutralizing antibody prior to simulated ischaemia was associated with reduced expression of HSP60&amp;70, IL6, TNF-α and cleaved caspase-3 (P&lt;0.05). CONCLUSIONS Increased cytokine release, apoptosis and expression of HSP60&amp;70 and TLR4 occur in ischaemic skeletal muscle in vitro. TLR4 antagonism was associated with reduced apoptosis and inflammatory cytokine release and down-regulation of HSP60&amp;70 expression. This suggests a potential pathway where TLR4 and its endogenous ligands contribute to a positive feedback loop to maintain a proinflammatory environment during ischaemia.