Involvement of human heat shock protein 90 alpha in nicotine-induced apoptosis

Combination of HSP90 Inhibitors and HSP70 Inducers Prevent Hydrochloric Acid-Induced Pulmonary Fibrosis in Rabbits

Combined therapies with Heat Shock Protein 90 (HSP90) inhibitors and Heat Shock Protein 70 (HSP70) inducers are gaining significant interest in cancer and cardiovascular research. Here, we tested the hypothesis that HSP90 inhibitors and HSP70 inducers, together, can block the development of pulmonary fibrosis. We exposed New Zealand White Rabbits to hydrochloric acid (HCl, 0.1 N, 1.5 mL/kg), one of the top five chemicals most commonly involved in accidental exposures and inhalation injuries worldwide, and treated animals with either the orally available HSP90 inhibitor TAS-116 (1.7 mg/kg 5x/week) or TAS-116 combined with the HSP70 inducer, geranylgeranyl acetone (GGA, 50 mg/kg, 3x/week). At 60 days post-HCl instillation, TAS and GGA treatment markedly reduced the degree of pulmonary fibrosis, lung dysfunction, and activation of profibrotic pathways. The use of HSP70 inducers may be a helpful tool to improve the profile of HSP90 inhibitors and reduce their minimal effective dose and side effects. Further investigation is required to explore the exact synergistic mechanism behind the antifibrotic profile of HSP90 inhibitors and HSP70 inducers.

Caffeic Acid Phenethyl Ester Reduces the Adverse Effects of Nicotine on the Endometrium

Background

Tobacco smoke contains various toxins that negatively affect the human reproductive system. Caffeic acid phenethyl ester (CAPE), a potent antioxidant, has protective effects on the reproductive system against oxygen-free radicals, methotrexate, and pesticides. Herein, the effect of CAPE on some key markers of endometrial receptivity has been evaluated.

Methods

A cross-sectional study was conducted during 2018-2019 in the Department of Clinical Biochemistry, School of Medicine, Fasa University of Medical Sciences (Fasa, Iran). Primary endometrial cells were divided into five groups, namely control, nicotine, CAPE, vehicle, and nicotine+CAPE. Real-time polymerase chain reaction (PCR) and methylation-specific PCR were performed to evaluate gene expressions and methylation, respectively. Appropriate doses of CAPE and nicotine were determined using the MTT assay. Data were analyzed using SPSS software (version 16.0) with a one-way analysis of variance. P<0.01 was considered statistically significant. The fold change was calculated using the 2-∆ΔCT method.

Results

Treatment of cells with nicotine significantly reduced the expression of C-X-C motif chemokine ligand 12 (CXCL12), fibroblast growth factor 2 (FGF2), and vascular endothelial growth factor A (VEGF-A) genes (P<0.0001). However, the expression levels increased significantly when treated with nicotine+CAPE (P<0.0001). Despite the reduced CXCL12 gene expression in cells treated with nicotine, CXCL12 was unmethylated in all study groups, indicating that the methylation status of the CXCL12 gene was not affected by nicotine or CAPE.

Conclusion

CAPE can be a suitable agent to protect female smokers from the harmful effects of nicotine. This manuscript is available as a preprint on the Research Gate website.

Antibodies to Heat Shock Proteins 90α and 90β in Psoriasis

One of many hypotheses of psoriasis pathogenesis supposes an overexpression of heat shock proteins (Hsps) in different skin layers and systemic immunologic response to them. Hsp90 is one of the most abundant chaperone in eukaryotic cells. The number of studies concerning the role of Hsp90 and anti-Hsp90 antibodies in etiopathogenesis of various diseases is also constantly expanding. Still, there are not many reports concerning potential involvement of this Hsp family or anti-Hsp90 immunization in pathomechanism of psoriasis. The aim of the study was the estimation of anti-Hsp90α and anti-Hsp90β IgG antibodies in the sera of the psoriatic patients at different phases of disease activity in comparison to the sera of healthy individuals. The study material consisted of sera from psoriasis patients (n = 80) in active phase and in the remission phase and healthy individuals (n = 80). Concentrations of anti-Hsp90α and anti-Hsp90β IgG antibodies were determined using ELISA technique. In the patients with psoriasis (both in the active phase of the disease and in the remission phase) concentrations of anti-Hsp90α antibodies were significantly higher than in healthy individuals and they correlated positively with psoriasis area severity index values. The mean concentrations of anti-Hsp90β antibodies in the psoriatic patients and healthy controls were comparable. The obtained results indicate an existence of increased immunological response to Hsp90α in psoriasis. It may suggest the role of the extracellular form of this chaperone and/or anti-Hsp90α antibodies in etiopathogenesis of this dermatosis. The inhibition of Hsp90α may represent a novel therapeutic approach to treat psoriasis.

Prognostic value of the mRNA expression of members of the HSP90 family in non-small cell lung cancer

The aim of the present study was to investigate the potential prognostic value of members of the heat shock protein (HSP)90 family in non-small cell lung cancer (NSCLC) patients. The mRNA expression profiles of 1,926 NSCLC patients, which was available from the Kaplan-Meier plotter database, were included in the study. High expression of HSP90AA1 mRNA was significantly associated with a poorer rate of overall survival (OS) for all NSCLC patients [hazard ratio (HR), 1.21; 95% confidence interval (CI): 1.06–1.37; P=0.004], as well as for patients with adenocarcinoma (ADE; HR, 1.3; 95% CI: 1.02–1.65; P=0.034), but no significant correlation was identified for squamous cell carcinoma (SCC) patients (HR, 1.08; 95% CI: 0.85–1.38; P=0.51). High expression of HSP90AB1 and HSP90B1 mRNA was significantly associated with poorer rates of OS in lung SCC and ADE patients combined, as well as in lung ADE patients alone. By contrast, high expression of tumor necrosis factor receptor-associated protein 1 (TRAP1) mRNA was significantly associated with improved OS rates in all NSCLC patients combined (HR, 0.88; 95% CI: 0.77–0.99; P=0.041), as well as ADE patients. In stratified survival analysis, a high expression of HSP90AA1, HSP90AB1 and HSP90B1 predicted poor prognosis in stage I NSLCC patients, suggesting that these genes may serve as stage-independent prognostic indicators. As an elevated expression of HSP90AA1, HSP90AB1, HSP90B1 and TRAP1 was associated with poorer OS outcomes in patients with NSCLC, these HSP90 members may be potential prognostic biomarkers and drug targets for the treatment of NSCLC.

Inhibition of HSP90α protects cultured neurons from oxygen-glucose deprivation induced necroptosis by decreasing RIP3 expression

Heat shock protein 90α (HSP90α) maintains cell stabilization and regulates cell death, respectively. Recent studies have shown that HSP90α is involved in receptor interacting protein 3 (RIP3)-mediated necroptosis in HT29 cells. It is known that oxygen and glucose deprivation (OGD) can induce necroptosis, which is regulated by RIP3 in neurons. However, it is still unclear whether HSP90α participates in the process of OGD-induced necroptosis in cultured neurons via the regulation of RIP3. Our study found that necroptosis occurs in primary cultured cortical neurons and PC-12 cells following exposure to OGD insult. Additionally, the expression of RIP3/p-RIP3, MLKL/p-MLKL, and the RIP1/RIP3 complex (necrosome) significantly increased following OGD, as measured through immunofluorescence (IF) staining, Western blotting (WB), and immunoprecipitation (IP) assay. Additionally, data from computer simulations and IP assays showed that HSP90α interacts with RIP3. In addition, HSP90α was overexpressed following OGD in cultured neurons, as measured through WB and IF staining. Inhibition of HSP90α in cultured neurons, using the specific inhibitor, geldanamycin (GA), and siRNA/shRNA of HSP90α, protected cultured neurons from necrosis. Our study showed that the inhibitor of HSP90α, GA, rescued cultured neurons not only by decreasing the expression of total RIP3/MLKL, but also by decreasing the expression of p-RIP3/p-MLKL and the RIP1/RIP3 necrosome. In this study, we reveal that inhibition of HSP90α protects primary cultured cortical neurons and PC-12 cells from OGD-induced necroptosis through the modulation of RIP3 expression.

Expression Changes of Apoptotic Genes in Tissues from Mice Exposed to Nicotine

Objective:

Smoking is the leading preventable cause of various diseases such as lung cancer, chronic obstructive pulmonary disease and cardiovascular disease. Nicotine, one of the major toxic components of tobacco, contributes to the pathogenesis of different diseases.

Methods:

Given the controversy about nicotine toxicity, the present study was conducted to determine apoptotic effects of nicotine on the heart, kidney, lung and liver of male mice. Real-time PCR was performed to identify mRNA expression changes in apoptotic-related genes between nicotine treated and control mice.

Result:

In the heart and lung, nicotine caused significant decrease in P53, Bax and Caspase-3 mRNA expression levels compared to the control group. However, in the kidney and liver, the result was significant increase in Bax, Caspase-2, Caspase-3 and a significant decrease in P53 mRNA expression (p<0.01). DNA fragmentation assays indicated no fragmentation in the heart and lung, but in the kidney and liver of nicotine treated mice, isolated DNA was fragmented.

Conclusion:

Our study provided insight into the molecular mechanisms of nicotine anti-apoptotic effects on the heart and lung as well as pro-apoptotic effects on kidney and liver via a P53-independent pathway.

Discovery and validation of small-molecule heat-shock protein 90 inhibitors through multimodality molecular imaging in living subjects

Up-regulation of the folding machinery of the heat-shock protein 90 (Hsp90) chaperone protein is crucial for cancer progression. The two Hsp90 isoforms (α and β) play different roles in response to chemotherapy. To identify isoform-selective inhibitors of Hsp90(α/β)/cochaperone p23 interactions, we developed a dual-luciferase (Renilla and Firefly) reporter system for high-throughput screening (HTS) and monitoring the efficacy of Hsp90 inhibitors in cell culture and live mice. HTS of a 30,176 small-molecule chemical library in cell culture identified a compound, N-(5-methylisoxazol-3-yl)-2-[4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidin-2-ylthio]acetamide (CP9), that binds to Hsp90(α/β) and displays characteristics of Hsp90 inhibitors, i.e., degradation of Hsp90 client proteins and inhibition of cell proliferation, glucose metabolism, and thymidine kinase activity, in multiple cancer cell lines. The efficacy of CP9 in disrupting Hsp90(α/β)/p23 interactions and cell proliferation in tumor xenografts was evaluated by non-invasive, repetitive Renilla luciferase and Firefly luciferase imaging, respectively. At 38 h posttreatment (80 mg/kg × 3, i.p.), CP9 led to selective disruption of Hsp90α/p23 as compared with Hsp90β/p23 interactions. Small-animal PET/CT in the same cohort of mice showed that CP9 treatment (43 h) led to a 40% decrease in (18)F-fluorodeoxyglucose uptake in tumors relative to carrier control-treated mice. However, CP9 did not lead to significant degradation of Hsp90 client proteins in tumors. We performed a structural activity relationship study with 62 analogs of CP9 and identified A17 as the lead compound that outperformed CP9 in inhibiting Hsp90(α/β)/p23 interactions in cell culture. Our efforts demonstrated the power of coupling of HTS with multimodality molecular imaging and led to identification of Hsp90 inhibitors.

Nicotine inhibits cisplatin-induced apoptosis in NCI-H446 cells

Nicotine is not only a major component in tobacco but is also a survival agonist that inhibits apoptosis induced by certain agents including chemotherapeutic drugs. Here, we first showed that nicotine inhibits cisplatin-induced apoptosis in NCI-H446 cells. An MTT assay, Annexin V-FITC staining, RT-PCR, and Western blot were applied to identify the viability of cells, stages of apoptosis, mRNA and signaling proteins expression, respectively. First, we observed that nicotine induced no significant apoptosis when used alone and promoted cell proliferation at a low concentration or for a short time, but the opposite was observed at a high concentration or for a long time. In addition, an increase in XIAP and Survivin mRNA or protein was observed. Next, when combined with cisplatin, growth inhibition rates were concentration dependent, decreased to the lowest level at first, but later climbed to the highest point. Furthermore, nicotine inhibited apoptosis induced by cisplatin and caused a concentration-dependent increase in both XIAP and Survivin mRNA or protein. Moreover, the apoptotic effect of the combination group was obviously higher than that of nicotine used alone at the same nicotine concentration and lower than that of cisplatin used alone at the same cisplatin concentration. These studies suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutics.

Estradiol pretreatment attenuated nicotine-induced endothelial cell apoptosis via estradiol functional membrane receptor

Cigarette smoking is highly associated with increased cardiovascular disease complications. The female population, however, manifests reduced cardiovascular morbidity. We define nicotine's effect upon human umbilical vein endothelial cells (HUVECs), determine whether estradiol might ameliorate endothelial dysfunction via its membrane estrogen receptor (mER), and attempt to elucidate the underlying mechanisms. Endothelial cells were pretreated with estradiol-BSA and measured resultant ion flux across the cells via the patch clamp technique to assess mER is functionality. Estradiol-BSA administration was associated with 30% decreased nicotine-induced apoptosis and also attenuated nicotine-activated phosphorylation of p38 and ERK. Pretreatment of estradiol-BSA triggered a low calcium influx, suggesting ahead low influx calcium played a critical role in the underlying protective mechanisms of estradiol. Furthermore, this estradiol-BSA protection against apoptosis remained effective in the presence of tamoxifen, an intracellular estrogen receptor (iER) inhibitor. Additionally, tamoxifen did not abolish estradiol-BSA's inhibitory effect upon p38 and ERK's activation, giving evidence to the obligatory role of p38 and ERK signaling in the estradiol-BSA's anti-apoptotic action via mER. Our study provides evidence that nicotine enhances endothelial cell apoptosis, but estrogen exerts anti-apoptotic effect through its functional membrane estrogen receptor. Clinically, the nicotine in cigarettes might contribute to endothelial dysfunction, whereas ambient estradiol may provide cellular protection against nicotine-induced injury through its functional membrane receptor via MAPK pathway downregulation.

Nicotine-mediated signals modulate cell death and survival of T lymphocytes

The capacity of nicotine to affect the behavior of non-neuronal cells through neuronal nicotinic acetylcholine receptors (nAChRs) has been the subject of considerable recent attention. Previously, we showed that exposure to nicotine activates the nuclear factor of activated T cells (NFAT) transcription factor in lymphocytes and endothelial cells, leading to alterations in cellular growth and vascular endothelial growth factor production. Here, we extend these studies to document effects of nicotine on lymphocyte survival. The data show that nicotine induces paradoxical effects that might alternatively enforce survival or trigger apoptosis, suggesting that depending on timing and context, nicotine might act both as a survival factor or as an inducer of apoptosis in normal or transformed lymphocytes, and possibly other non-neuronal cells. In addition, our results show that, while having overlapping functions, low and high affinity nAChRs also transmit signals that promote distinct outcomes in lymphocytes. The sum of our data suggests that selective modulation of nAChRs might be useful to regulate lymphocyte activation and survival in health and disease.

Gene expression endpoints following chronic waterborne copper exposure in a genomic model organism, the zebrafish, Danio rerio

Although copper (Cu) is an essential micronutrient for all organisms, in excess, waterborne Cu poses a significant threat to fish from the cellular to population level. We examined the physiological and gene expression endpoints that chronic waterborne Cu exposure (21 d) imposes on soft-water acclimated zebrafish at two environmentally relevant concentrations: 8 microg/l (moderate) and 15 microg/l (high). Using a 16,730 65-mer oligonucleotide customized zebrafish microarray chip related to metal metabolism and toxicity to assess the transcriptomic response, we found that 573 genes in the liver responded significantly to Cu exposure. These clustered into three distinct patterns of expression. There was distinct upregulation of a majority of these genes under moderate Cu exposure and a significant downregulation under high Cu exposure. Microarray results were validated by qPCR of eight genes; two genes, metallothionein 2 (mt2) and Na(+)-K(+)-ATPase 1a1 (atp1a1), displayed increased expression under both Cu exposures, indicative of potential genetic endpoints of Cu toxicity, whereas the remaining six genes demonstrated opposing effects at each Cu exposure. Na(+)-K(+)-ATPase enzyme activity decreased during Cu exposure, which may be linked to Cu's competitive effects with Na(+). Whole body cortisol levels were significantly increased in Cu-exposed fish, which prompted an analysis of the promoter region of all significantly regulated genes for glucocorticoid (GRE) and metal (MRE) response elements to dissociate metal- and stress-specific gene responses. Of the genes significantly regulated, 30% contained only a GRE sequence, whereas 2.5% contained only a consensus MRE. We conclude that the indirect effects of Cu exposure regulate gene expression to a much greater degree than the direct effects.

Cholinergic neural signals to the spleen down-regulate leukocyte trafficking via CD11b

The cholinergic anti-inflammatory pathway is a physiological mechanism that inhibits cytokine production and diminishes tissue injury during inflammation. Recent studies demonstrate that cholinergic signaling reduces adhesion molecule expression and chemokine production by endothelial cells and suppresses leukocyte migration during inflammation. It is unclear how vagus nerve stimulation regulates leukocyte trafficking because the vagus nerve does not innervate endothelial cells. Using mouse models of leukocyte trafficking, we show that the spleen, which is a major point of control for cholinergic modulation of cytokine production, is essential for vagus nerve-mediated regulation of neutrophil activation and migration. Administration of nicotine, a pharmacologic agonist of the cholinergic anti-inflammatory pathway, significantly reduces levels of CD11b, a beta(2)-integrin involved in cell adhesion and leukocyte chemotaxis, on the surface of neutrophils in a dose-dependent manner and this function requires the spleen. Similarly, vagus nerve stimulation significantly attenuates neutrophil surface CD11b levels only in the presence of an intact and innervated spleen. Further mechanistic studies reveal that nicotine suppresses F-actin polymerization, the rate-limiting step for CD11b surface expression. These studies demonstrate that modulation of leukocyte trafficking via cholinergic signaling to the spleen is a specific, centralized neural pathway positioned to suppress the excessive accumulation of neutrophils at inflammatory sites. Activating this mechanism may have important therapeutic potential for preventing tissue injury during inflammation.

Control mechanisms of differential translation of Hsp90 isoforms in 9L rat gliosarcoma cells

Although the differential expression of heat shcok proteins, Hsp90alpha and Hsp90beta was extensively studied in many kinds of cells, the post-transcriptional regulation of Hsp90 isoforms remains unclear. In control and GA-treated rat gliosarcoma cells, it has been reported that the translational efficiency of hsp90alpha is higher than hsp90beta. In this study, we present evidences identifying the roles for leaky scanning and 5'-UTR sequence in translational regulation of Hsp90beta. The result of in vitro transcription and translation (IVTT) experiment showed that hsp90alpha exhibited higher translation efficiency than hsp90beta. Sequence analysis revealed that there is an out-of-frame downstream AUG codon in hsp90beta gene. However, elimination of the downstream AUG by site-directly mutagenesis or introducing Kozak context sequence around the initiator AUG of hsp90beta open reading frame increased its translational efficiency, which indicated that leaky scanning might be a possible mechanism regulating hsp90beta. Furthermore, we also constructed a firefly luciferase reporter system to verify the effect of subsequent translation at the downstream out-of-frame AUG codon in 9L and A549 cells. Furthermore, it is believed that 5'-untranslated region (5'-UTR) also plays a significant role in translational control. We showed hsp90beta 5'-UTR gives rise to the reduction of the translation efficiency in IVTT experiment. Additionally, the reductive effect of hsp90beta 5'-UTR was further confirmed by luciferase reporter assay using truncated deletion analyses of 5'-UTR of hsp90beta. Our results support the hypothesis that ribosome leaky scanning mechanism and 5'-UTR sequence acts as negative regulators in hsp90beta mRNA.

Heat shock protein-90-alpha, a prolactin-STAT5 target gene identified in breast cancer cells, is involved in apoptosis regulation

INTRODUCTION

The prolactin-Janus-kinase-2-signal transducer and activator of transcription-5 (JAK2-STAT5) pathway is essential for the development and functional differentiation of the mammary gland. The pathway also has important roles in mammary tumourigenesis. Prolactin regulated target genes are not yet well defined in tumour cells, and we undertook, to the best of our knowledge, the first large genetic screen of breast cancer cells treated with or without exogenous prolactin. We hypothesise that the identification of these genes should yield insights into the mechanisms by which prolactin participates in cancer formation or progression, and possibly how it regulates normal mammary gland development.

METHODS

We used subtractive hybridisation to identify a number of prolactin-regulated genes in the human mammary carcinoma cell line SKBR3. Northern blotting analysis and luciferase assays identified the gene encoding heat shock protein 90-alpha (HSP90A) as a prolactin-JAK2-STAT5 target gene, whose function was characterised using apoptosis assays.

RESULTS

We identified a number of new prolactin-regulated genes in breast cancer cells. Focusing on HSP90A, we determined that prolactin increased HSP90A mRNA in cancerous human breast SKBR3 cells and that STAT5B preferentially activated the HSP90A promoter in reporter gene assays. Both prolactin and its downstream protein effector, HSP90alpha, promote survival, as shown by apoptosis assays and by the addition of the HSP90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in both untransformed HC11 mammary epithelial cells and SKBR3 breast cancer cells. The constitutive expression of HSP90A, however, sensitised differentiated HC11 cells to starvation-induced wild-type p53-independent apoptosis. Interestingly, in SKBR3 breast cancer cells, HSP90alpha promoted survival in the presence of serum but appeared to have little effect during starvation.

CONCLUSIONS

In addition to identifying new prolactin-regulated genes in breast cancer cells, we found that prolactin-JAK2-STAT5 induces expression of the HSP90A gene, which encodes the master chaperone of cancer. This identifies one mechanism by which prolactin contributes to breast cancer. Increased expression of HSP90A in breast cancer is correlated with increased cell survival and poor prognosis and HSP90alpha inhibitors are being tested in clinical trials as a breast cancer treatment. Our results also indicate that HSP90alpha promotes survival depending on the cellular conditions and state of cellular transformation.

The heat shock protein 90 inhibitor IPI-504 induces apoptosis of AKT-dependent diffuse large B-cell lymphomas

Heat shock protein 90 (HSP90) is a molecular chaperone that stabilizes critical client proteins in multiple cancers. Gene expression profiling was utilized to characterize HSP90 isoform expression in primary human diffuse large B-cell lymphomas (DLBCLs). HSP90 alpha and beta isoforms were differentially expressed in subsets of tumours defined by their transcriptional profiles. Thereafter, we assessed the activity of the HSP90 inhibitor, IPI-504, in an extensive panel of DLBCL cell lines. IPI-504, which interacts with the conserved ATP-binding site in both HSP90 isoforms, inhibited proliferation and induced apoptosis in the majority of DLBCL cell lines at low micromolar concentrations. IPI-504-sensitive cell lines expressed high levels of the HSP90 client protein, pAKT, and exhibited dose-dependent decreases in pAKT levels following IPI-504 treatment and significantly reduced proliferation following AKT RNAi. Furthermore, the combination of low-dose (<1 micromol/l) IPI-504 and the AKT/Pi3K pathway inhibitor, LY24009, was synergistic in IPI-504-sensitive DLBCL cell lines. Low-dose IPI-504 was also synergistic with the chemotherapeutic agent, doxorubicin. The HSP90 inhibitor IPI-504 warrants further investigation in DLBCL alone and in combination with identified client protein inhibitors and active chemotherapeutic agents.

Nicotine and apoptosis

Cigarette smoking is associated with a plethora of different diseases. Nicotine is the addictive component of cigarette but also acts onto cells of the non-neuronal system, including immune effector cells. Although nicotine itself is usually not referred to as a carcinogen, there is ongoing debate whether nicotine functions as a 'tumor enhancer.' By binding to nicotinic acetylcholine receptors, nicotine deregulates essential biological processes like angiogenesis, apoptosis, and cell-mediated immunity. Apoptosis plays critical roles in a wide variety of physiologic processes during fetal development and in adult tissue and is also a fundamental aspect of the biology of malignant diseases. This review provides an overlook how nicotine influences apoptotic processes and is thus directly involved in the etiology of pathological conditions like cancer and obstructive diseases.

Heat shock protein 90alpha recruits FLIPS to the death-inducing signaling complex and contributes to TRAIL resistance in human glioma

Heat shock protein 90 (HSP90) is a molecular chaperone that contributes to the proper folding and stability of target proteins. Because HSP90 has been suggested to interact with FLIP(S), the key regulator of tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in glioma cells, we examined the role HSP90 played in controlling TRAIL response. HSP90alpha was found to associate with FLIP(S) in resting cells in a manner dependent on the ATP-binding NH2-terminal domain of HSP90alpha. Following TRAIL exposure, HSP90alpha and the client FLIP(S) protein were recruited to the death-inducing signaling complex (DISC). Short interfering RNA-mediated suppression of HSP90alpha did not alter the total cellular levels of FLIP(S), but rather inhibited the recruitment of FLIP(S) and other antiapoptotic proteins such as RIP and FLIP(L) to the DISC, and sensitized otherwise resistant glioma cells to TRAIL-induced apoptosis. These results show that HSP90alpha, by localizing FLIP(S) to the DISC, plays a key role in the resistance of tumor cells to TRAIL, and perhaps other proapoptotic agents. The results also define a novel means of apoptotic control by a HSP90alpha that may in turn help explain the global antiapoptotic effects of this protein.

Quantification of PPAR-gamma protein in monocyte/macrophages from healthy smokers and non-smokers: a possible direct effect of nicotine

Previous observations demonstrated that Peroxisome Proliferator-Activated Receptor-gamma (PPAR-gamma), a key regulator of adipocyte differentiation, is expressed in a large variety of cells, including cells of the monocyte/macrophage lineage. This study was aimed to quantify both the constitutive and ligand-induced PPAR-gamma expression in monocytes and monocyte-derived macrophages (MDM) isolated from healthy smokers and non-smokers, and to evaluate the possible direct effect of nicotine. PPAR-gamma protein was detected by Western blot and quantification was performed by calculating the ratio between PPAR-gamma and beta-actin protein expression. Cytokine release was measured with enzyme-linked immunoassay kits. Constitutive PPAR-gamma protein was detected in human monocytes and its expression was up-regulated along with differentiation to MDM. The endogenous ligand 15-deoxy-delta(12,14)-prostaglandin J(2) and the synthetic agonist ciglitazone enhanced PPAR-gamma expression, the former being effective also at low micromolar concentrations. Both agonists significantly inhibited the basal secretion of pro-inflammatory cytokines (e.g., TNF-alpha, IL-6), ciglitazone being more potent. Monocytes and MDM from healthy smokers presented a significantly enhanced (4-fold and 2.5-fold, respectively) constitutive PPAR-gamma expression, as compared to those from healthy non-smokers. However, ligand-induced PPAR-gamma expression and inhibition of cytokine secretion were similar in healthy smokers and non-smokers. Nicotine dose-dependently enhanced PPAR-gamma expression with a maximum at 10 muM, and inhibited release of pro-inflammatory cytokines; these effects were reversed by alpha-bungarotoxin. Nicotine and PPAR-gamma agonists did not exert synergistic effects. In conclusion, monocytes and MDM from healthy smokers present a constitutively enhanced PPAR-gamma expression; this effect is reproduced, to some extent, by nicotine in vitro.

[Effects of nicotine with special consideration given to tumorigenesis in the head and neck region]

BACKGROUND

Tumorigenesis is based on initiation, promotion, and progression, whereas tobacco smoke is a decisive predisposing factor for squamous cell carcinomas of the upper aerodigestive tract. A variety of tobacco smoke compounds is known to potentially initiate tumors, but the alkaloid nicotine is generally considered to induce addiction only. However, there is growing evidence that nicotine may also contribute to early stages of tumorigenesis. In the present study, a possible direct genotoxic potential of nicotine is investigated.

MATERIAL AND METHODS

Lymphatic tissue of the tonsilla palatina of eight donors was harvested during surgery and incubated with nicotine. DNA damage was measured with the comet assay.

RESULTS

Genotoxic effects of nicotine could be demonstrated.

DISCUSSION

The results suggest a direct contribution of nicotine to tumor initiation and carcinogenesis.

Heat shock proteins: endogenous modulators of apoptotic cell death

The highly conserved heat shock proteins (Hsps) accumulate in cells exposed to heat and a variety of other stressful stimuli. Hsps, that function mainly as molecular chaperones, allow cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. The events of cell stress and cell death are linked and Hsps induced in response to stress appear to function at key regulatory points in the control of apoptosis. Hsps include anti-apoptotic and pro-apoptotic proteins that interact with a variety of cellular proteins involved in apoptosis. Their expression level can determine the fate of the cell in response to a death stimulus, and apoptosis-inhibitory Hsps, in particular Hsp27 and Hsp70, may participate in carcinogenesis. This review summarizes the apoptosis-regulatory function of Hsps.

Nicotine prevents the apoptosis induced by menadione in human lung cancer cells

Approximately 50% of long-term cigarette smokers die prematurely from the adverse effects of smoking, including on lung cancer and other illnesses. Nicotine is a main component in tobacco and has been implicated as a potential factor in the pathogenesis of human lung cancer. However, the mechanism of nicotine action in the development of lung cancer remains largely unknown. In the present study, we designed a nicotine-apoptosis system, by pre-treatment of nicotine making lung cancer cell A549 to be in a physiological nicotine environment, and observed that nicotine promoted cell proliferation and prevented the menadione-induced apoptosis, and exerts its role of anti-apoptosis by shift of apoptotic stage induced by menadione from late apoptotic stage to early apoptotic stage, in which NF-kappaB was up-regulated. Interference analysis of NF-kappaB in A549 cells showed that knock down of NF-kappaB resulted in apoptosis promotion and counteracted the protective effect of nicotine. The findings suggest that nicotine has potential effect in lung cancer genesis, especially in patients with undetectable early tumor development and development of specific NF-kappaB inhibitors would represent a potentially exciting new pharmacotherapy for tobacco-related lung cancer.

The effects of erdosteine, N-acetylcysteine, and vitamin E on nicotine-induced apoptosis of pulmonary cells

This study was conducted to investigate the frequency of apoptosis in the pulmonary epithelial cells of rats after intratraperitoneal nicotine injection, in order to examine the role of inflammatory markers [myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha)] in nicotine-induced lung damage, and to determine the protective effects of three known antioxidant agents [N-acetylcysteine (NAC), erdosteine, and vitamin E] on the lung toxicity of nicotine in the lungs. Female Wistar rats were divided into seven groups, each composed of nine rats: two negative control groups, two positive control groups, one erdosteine-treated group (500 mg/kg), one NAC-treated group (500 mg/kg), and one vitamin E-treated group (500 mg/kg). Nicotine was injected intraperitoneally at a dosage of 0.6 mg/kg for 21 days. Following nicotine injection, the antioxidants were administered orally, treatment was continued until the rats were killed. Lung tissue samples were stained with hematoxylin-eosin (H&E) for histopathological assessments. The apoptosis level in the lung bronchiolar and alveolar epithelium was determined by using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) method. Cytoplasmic TNF-alpha in the bronchiolar and alveolar epithelial cells and the lung MPO activity were evaluated immunohistochemically. The protective effect of vitamin E on lung histology was stronger than that of erdosteine or NAC. Treatment with erdosteine, NAC, and vitamin E significantly reduced the rate of nicotine-induced pulmonary epithelial cell apoptosis, and there were no significant differences in apoptosis among the three antioxidants groups. Erdosteine, NAC, and vitamin E significantly reduced the increases in TNF-alpha staining and lung MPO activity. The effects of erdosteine on the increases in the local TNF-alpha level and lung MPO activity were weaker than that of NAC or vitamin E. This findings suggest that erdosteine and NAC can be as effective as vitamin E in protecting against nicotine-induced pulmonary cell apoptosis.

Enhanced expression of transferrin receptor confers UV-resistance in human and monkey cells

One of the most intriguing biological subjects is cell-surface molecules that regulate the susceptibility of human cells to cell-killing effects after irradiation with far-ultraviolet light (UV, principally 254 nm wavelength). Human RSa cells have unusual sensitivity to UV-induced cell-killing. We searched for molecules on the cell-surface of RSa cells that were present in different amounts as compared to a variant of these cells, UV(r)-1 cells, which have increased resistance to UV cell-killing. Among the 21 molecules examined, the amount of transferrin receptor (TfR) protein was found to be 2-fold higher in UV(r)-1 cells compared with in RSa cells. The amounts of this protein were also higher in the UV-resistant hematopoietic cell lines, CEM6 and Daudi, as compared to the UV-sensitive cell lines, Molt4 and 697. Culturing of UV(r)-1 cells in a medium containing anti-transferrin antibodies resulted in sensitization of the cells to UV cell-killing as demonstrated by colony formation assay. Similar results were observed by treatment of the cells with TfR siRNA. In contrast, overexpression of TfR protein led to a resistance to UV cell-killing in RSa cells and monkey COS7 cells as demonstrated by both colony formation and apoptosis assay. In TfR-overexpressing cells, reduction of p53 and Bax protein was observed after UV-irradiation. Thus, TfR expression appears to be involved in the regulation of UV-resistance, possibly via modulation of the amount of p53 and Bax protein.

Proteomic analysis of nicotine-associated protein expression in the striatum of repeated nicotine-treated rats

Through the proteomic analysis using 2-dimensional electrophoresis, the nicotine addiction-associated proteins were extensively screened in the striatum of rat brains. The nicotine addiction was developed by repeated nicotine injection (0.4mg/kg s.c.), twice daily for 7 days, followed by one challenge injection after a 3 day withdrawal period, and then confirmed by observing a 2.3-fold increase in locomoter activity. The 3 up- and 4 down-regulated proteins were selected and identified to be zinc-finger binding protein-89 (ZBP-89), 2'3'-cyclic nucleotide 3'-phosphodiesterase 1, deoxyribonuclease 1-like 3 (DNase1l3), tandem pore domain halothane inhibited K(+) channel (THIK-2), brain-specific hyaluronan-binding protein (BRAL-1), death effector domain-containing DNA binding protein (DEDD), and brain-derived neurotrophic factor (BDNF) by mass spectrophotometric fingerprinting. Among them, the expression patterns of ZEB-89, DNase1l3, THIK-2, DEDD, and BDNF mRNAs were found to be coincident with those of cognate proteins, by using RT-PCR analysis. These proteins could be suggested as drug targets to develop a new therapy for nicotine-associated diseases, as well as the clues to understand the mechanism of nicotine.

Nicotine enhancement of lipopolysaccharide/interferon-γ-induced cytotoxicity with elevating nitric oxide production

Nicotine has been shown to induce relaxation via nitric oxide (NO) production with activation of endothelium nitric oxide synthase (eNOS), however the effect of nicotine on lipopolysaccharide/interferon-gamma (LPS/IFN-gamma)-induced NO production and inducible NOS (iNOS) gene expression is still undefined. Here, nicotine alone did not affect the NO and PGE2 production in RAW264.7 and primary peritoneal macrophages. Interestingly, nicotine showed the dose-dependent stimulatory effect on LPS (20 ng/ml)/IFN-gamma (10 ng/ml)-induced NO but not PGE2 production in both cells. Although nicotine stimulates NO production in the presence of LPS/IFN-gamma, LPS at the dose of 20 ng/ml, nicotine showed no obvious inductive effect on the expression of iNOS protein by Western blotting in both cells. However, nicotine significantly stimulates LPS (2.5, 5 ng/ml)/IFN-gamma (10 ng/ml)-induced iNOS expression and NO production in RAW264.7 cells. Cytotoxicity assay showed that nicotine enhanced LPS (20 ng/ml) and IFN-gamma (10 ng/ml)-induced cytotoxicity, which was inhibited by an NOS inhibitor N-nitro-L-arginine (NLA) in RAW264.7 cells. Direct and indirect NOS activity assays indicated that nicotine did not affect NOS activity. And, iNOS protein stability was not changed by nicotine after LPS/IFN-gamma treatment. These data indicates that nicotine may potentiate LPS/IFN-gamma-induced cytotoxic effects by enhancing NO production; enhancing iNOS gene expression induced by LPS/IFN-gamma is involved. A cross-talk between inflammation and smoking was proposed in the present study.

Hsp90 isoforms: functions, expression and clinical importance

The 90 kDa heat shock protein, Hsp90, is a main functional component of an important cytoplasmic chaperone complex, and it is involved in various cellular processes, such as cell proliferation, differentiation and apoptosis. Identification of Hsp90 as a molecular target of various anticancer drugs highlighted its importance from the clinical point of view. Here we summarize the current knowledge of various Hsp90 isoforms regarding their genomic location, molecular evolution, functional differences, differential induction after various environmental stresses and in pathological conditions as well as the growing importance of discriminating between Hsp90 isoforms in clinical practice.

Nicotine, its metabolism and an overview of its biological effects

Nicotine is a naturally occurring alkaloid found in many plants. The principal sources of nicotine exposure is through the use of tobacco, nicotine containing gum and nicotine replacement therapies. Nicotine is an amine composed of pyridine and pyrrolidine rings. It has been shown that nicotine crosses biological membranes and the blood brain barrier easily. The absorbed nicotine is extensively metabolized in the liver to form a wide variety of metabolites including nicotine N'-oxide and cotinine N'-oxide. These are the products of mixed function oxidase system. Nicotine is also converted to some biologically important compounds during harvesting. Among these are the nitrosamines specific to tobacco. Nicotine has been shown to affect a wide variety of biological functions ranging from gene expression, regulation of hormone secretion and enzyme activities. The objective of this study was to overview the biological effects and metabolism of nicotine.

Differential gene expression during HIV-1 infection analyzed by suppression subtractive hybridization

OBJECTIVE

Characterization of the effects of HIV-1 infection and apoptosis on cellular and viral gene expression.

METHODS

Flow cytometry was used to analyze infection and apoptosis concurrently in HIV-1IIIB-infected CEM-SS T cells. Suppression subtractive hybridization (SSH) was applied to cells from different time points of infection to construct subtracted complementary DNA (cDNA) libraries. Differential screening and Northern blots confirmed differential gene expression and these genes were sequenced and compared with database.

RESULTS

T cells undergo apoptosis at early stages of HIV-1IIIB infection (days 5-7 post-infection). Surprisingly, cells begin to recover after day 9 and by day 18 almost all infected cells are viable, even though they maintain the same level of infection. By SSH, differential gene expression profiles between day 7 and day 18 after HIV-1IIIB infection were characterized. SSH yielded two subtracted cDNA libraries; differential screening of the subtracted cDNA libraries suggested that 200 out of 864 colonies were highly expressed at their respective time points. DNA sequence analysis identified specific apoptosis-related genes, HIV-1 viral genes, and other candidate genes of interest. Northern blot analysis confirmed that some of these genes were expressed predominantly at the 'apoptotic' or 'non-apoptotic' time points.

CONCLUSIONS

Known and novel cellular gene products have been identified that are directly (or inversely) correlated with apoptosis and may regulate cell death in HIV-1 infection. These results provide a framework for functional studies on the differentially expressed genes and may suggest novel therapeutic approaches for treatment of HIV-1-infected individuals.

Effect of gestational nicotine treatment on newborn rat retina: a histopathological and morphometric analysis

BACKGROUND

Smoking is a significant risk factor in several debilitating and fatal diseases. It has been implicated in bilateral tobacco-toxic and Leber's hereditary optic neuropathies. Although it has been demonstrated that smoking has a cumulative effect on retinal and optic nerve functions and causes diffuse and localised retinal sensitivity decrease in healthy chronic heavy smokers, the affected retinal layer has not been identified and there is no experimental study investigating the effect of nicotine exposure during gestation on the newborn rat retina.

PURPOSE

This experimental investigation evaluated histologically the influence in vivo of maternal nicotine treatment during pregnancy on the newborn rat retina. Different dosages of the test compound simulated the range of low, moderate, and heavy smokers in humans.

METHODS

Experimentally naive, adult female Wistar-albino rats weighing 200-250 g were mated with adult male rats over 2 days for copulation in the proportion of two females for every male animal. After confirming pregnancy with vaginal smear method, 40 gravid rats (dams) were then randomly assigned into four equal groups (three experimental and one control; n = 10 in each). On day 9 of gestation, groups 1, 2, and 3 experimental dams were treated with intraperitoneal (i.p.) (-)-nicotine tartrate at doses of 0.5, 1, and 2 mg kg body weight-1 day-1, respectively during pregnancy from gestational day 9-21. Group 4 control dams were given i.p. saline solution daily for the same period. After normal delivery, the newborn litters were sacrificed at postnatal day 1 or day 30. The eyes were enucleated for histopathologic and morphometric analysis of the retinas. Nicotine-induced neuronal changes were measured by morphometric analyses on cell counts of ganglion cell layer (linear cell density in number per unit length of retina) and thickness of the various retinal layers.

RESULTS

The litters in control group 4, and experimental groups 1 and 2 had normal retinal findings. On the other hand, morphometric analysis of retinal sections in experimental group 3 eyes demonstrated a 20.7% decrease in the number of surviving ganglion cells (40.7 +/- 2.0) compared with controls (51.3 +/- 1.1; p < 0.001). The thickness of whole retina (126.6 +/- 5.4 microm) was also reduced by 13.5% compared with controls (146.3 +/- 4.5 microm; p = 0.007). The main site of retinal atrophy was the inner plexiform layer (30.1 +/- 1.6 microm vs 43.5 +/- 1.3 microm; p < 0.001) with almost no change in the other retinal layers.

CONCLUSIONS

Gestational nicotine treatment induces marked changes in the organisation of the developing retina in newborn rats histopathologically. Quantitative morphometric analysis clearly demonstrated that the two most affected structures were the retinal ganglion cells and the inner plexiform layer, both of which are supplied by central retinal artery.