The proteasome is important for degradation of worn out and misfolded proteins. Decreased proteasome activity has been implicated in Alzheimer's disease (AD). Proteasome inhibition induces autophagy, but it is still unknown whether autophagy is beneficial or deleterious to AD neurons, as the autophagosome has been suggested as a site of amyloid-β (Aβ) generation. In this study, we investigated the effect of proteasome inhibition on Aβ accumulation and secretion, as well as the processing of amyloid-β protein precursor (AβPP) in AβPPSwe transfected SH-SY5Y neuroblastoma cells. We show that proteasome inhibition resulted in autophagy-dependent accumulation of Aβ in lysosomes, and increased levels of intracellular and secreted Aβ. The enhanced levels of Aβ could not be explained by increased amounts of AβPP. Instead, reduced degradation of the C-terminal fragment of AβPP (C99) by the proteasome makes C99 available for γ-secretase cleavage, leading to Aβ generation. Inhibition of autophagy after proteasome inhibition led to reduced levels of intracellular, but not secreted Aβ, and tended to further increase the C99 to AβPP ratio, supporting involvement of the autophagosome in Aβ generation. Furthermore, proteasome inhibition caused a reduction in cellular viability, which was reverted by inhibition of autophagy. Dysfunction of the proteasome could cause lysosomal accumulation of Aβ, as well as increased generation and secretion of Aβ, which is partly facilitated by autophagy. As a decrease in cellular viability was also detected, it is possible that upregulation of autophagy is an unsuccessful rescue mechanism, which instead of being protective, contributes to AD pathogenesis.

Neuroscience, including research on Alzheimers disease, is hampered by the lack of suitable in vitro models to study the human nervous system. To counteract this, many attempts to differentiate cell lines into more neuron-like cells have been performed, resulting in partial expression of neuronal features. Furthermore, it has been reported that neuroblastoma cell lines lack mature isoforms of tau. Our aim was to develop an improved in vitro model, generating sustainable cells with morphology and biochemistry of human, mature neurons. To obtain cells with neuronal differentiation and function, we investigated the effect of combining three-dimensional culturing of SH-SY5Y cells in extracellular matrix (ECM) gel with several factors reported to have neuro-differentiating effects. This resulted in cells with apparent neuronal morphology with long, extensively branched neurites. Further investigation revealed expression of several neurospecific markers including synapse protein Sv2 and nuclear marker NeuN, as well as the presence of synapses and axonal vesicle transport. In addition, these cells expressed mature tau isoforms, and tau protein expression was significantly increased compared to undifferentiated cells, reaching levels found in adult human brain. In conclusion, we found that pre-treatment with retinoic acid followed by ECM gel culturing in combination with brain derived neurotrophic factor, neuregulin beta(1), nerve growth factor, and vitamin D-3 treatment generated sustainable cells with unambiguous resemblance to adult neurons. These cells also expresses adult splicing forms of tau with neuronal localization, making this cellular in vitro model useful in many areas of neuroscience research, particularly the Alzheimers disease field.

Generation of free radicals is often associated with the induction and progression of apoptosis. Therefore, antioxidants can prove anti-apoptotic, and can help to elucidate specific apoptotic pathways. Here we studied whether coenzyme Q, present in membranes in reduced (ubiquinol) or oxidised (ubiquinone) forms, can affect apoptosis induced by various stimuli. Exposure of Jurkat cells to a-tocopheryl succinate (a-TOS), hydrogen peroxide, anti-Fas IgM or TRAIL led to induction of apoptosis. Cell death due to the chemical agents was suppressed in cells enriched with the reduced form of coenzyme Q. However, coenzyme Q did not block cell death induced by the immunological agents. Ubiquinol-10 inhibited reactive oxygen species (ROS) generation in cells exposed to a-TOS, and a mitochondrially targeted coenzyme Q analogue also blocked apoptosis triggered by a-TOS or hydrogen peroxide. Therefore, it is plausible that ubiquinol-10 protects cells from chemically-induced apoptosis by acting as an antioxidant in mitochondria. Our results also indicate that generation of free radicals may not be a critical step in induction of apoptosis by immunological agents. © 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

Enkephalin-synthesizing neurons in the super®cial laminae of the spinal and trigeminal dorsal horn are critical components of the endogenous pain-modulatory system. We have previously demonstrated that these neurons display intracellular estrogen receptors, suggesting that estrogen can potentially influence their enkephalin expression. By using Northern blot, we now show that a bolus injection of estrogen results in a rapid increase in spinal cord enkephalin mRNA levels in ovariectomized female rats. Thus, 4 h after estrogen administration the enkephalin mRNA-expression in the lumbar spinal cord was on average 68% higher (P , 0:05) than in control animals injected with vehicle only. A small increase in the amount of enkephalin mRNA was also seen after 8 h (P , 0:05), whereas no difference between estrogen-injected and control animals was found after 24 h or at time periods shorter than 4 h. Taken together with the previous anatomical data, the present findings imply that estrogen has an acute effect on spinal opioid levels in areas involved in the transmission of nociceptive information.

Lysosomes are acidic organelles that are critically involved in a number of physiological processes, including macromolecule degradation, endocytosis, autophagy, exocytosis and cholesterol homeostasis. Several pathological conditions, such as cancer, neurodegenerative disorders and lysosomal storage diseases, involve lysosomal disturbances, indicating the importance of the organelle for correct cellular function. The aim of this thesis was to investigate the role of lysosomes in cell death signaling.

Previous studies have shown that permeabilization of the lysosomal membrane and release of hydrolytic enzymes such as cathepsin D to the cytosol occurs during apoptosis. We identified Bid and 14-3-3 proteins as cytosolic targets of cathepsin D in human fibroblasts. Truncated Bid, generated by cathepsin D proteolytic cleavage, stimulates Bax-mediated release of pro-apoptotic factors from the mitochondria, thereby engaging the intrinsic pathway to apoptosis.

Since the presence of cathepsins in the cytosol is sufficient to induce apoptosis, the permeability of the lysosomal membrane influences the fate of the cell. In this thesis, we demonstrated that the stability of the lysosomal membrane can be manipulated by altering the lysosomal cholesterol content. Cells with high lysosomal cholesterol content were less prone to undergo apoptosis when challenged with stimuli known to induce lysosome-mediated cell death. In addition, cholesterol accumulation was associated with increased expression of lysosome-associated membrane proteins and storage of other lipids; however, these factors did not contribute to lysosomal stabilization.

Lysosomal membrane permeabilization and cathepsins contribute to ultraviolet (UV) irradiation-induced apoptosis. We demonstrate plasma membrane damage induced by UVA irradiation to be rapidly repaired by lysosomal exocytosis in human keratinocytes. Despite efficient plasma membrane resealing, the cells underwent apoptosis, which was dependent on early activation of caspase-8. The activation of caspase-8 was lysosome-dependent and occurred in vesicles positive for lysosomal markers.

This thesis demonstrates the importance of lysosomal stability for apoptosis regulation and that this stability can be influenced by drug intervention. Modulation of the lysosomal membrane permeability may have potential for use as a therapeutic strategy in conditions associated with accelerated or repressed apoptosis.

Bax-mediated permeabilization of the outer mitochondrial membrane and release of apoptogenic factors into the cytosol are key events that occur during apoptosis. Likewise, apoptosis is associated with permeabilization of the lysosomal membrane and release of lysosomal cathepsins into the cytosol. This report identifies proteolytically active cathepsin D as an important component of apoptotic signaling following lysosomal membrane permeabilization in fibroblasts. Lysosome-mediated cell death is associated with degradation of Bax sequestering 14-3-3 proteins, cleavage of the Box activator Bid, and translocation of Box to mitochondria, all of which were cathepsin D-dependent. Processing of Bid could be reproduced by enforced lysosomal membrane permeabilization, using the lysosomotropic detergent O-methyl-serine dodecylamine hydrochloride (MSDH). We identified three cathepsin D-specific cleavage sites in Bid, Phe24, Trp48, and Phe183. Cathepsin D-cleaved Bid induced Bax-mediated release of cytochrome c from purified mitochondria, indicating that the fragments generated are functionally active. Moreover, apoptosis was associated with cytosolic acidification, thereby providing a more favorable environment for the cathepsin D-mediated cleavage of Bid. Our study suggests that cytosolic cathepsin D triggers Bax-mediated cytochrome c release by proteolytic activation of Bid.

In the past decade, lysosomal membrane permeabilization (LMP) has emerged as a significant component of cell death signaling. The mechanisms by which lysosomal stability is regulated are not yet fully understood, but changes in the lysosomal membrane lipid composition have been suggested to be involved. Our aim was to investigate the importance of cholesterol in the regulation of lysosomal membrane permeability and its potential impact on apoptosis. Treatment of normal human fibroblasts with U18666A, an amphiphilic drug that inhibits cholesterol transport and causes accumulation of cholesterol in lysosomes, rescued cells from lysosome-dependent cell death induced by the lysosomotropic detergent 0-methyl-serine dodecylamide hydrochloride (MSDH), staurosporine (STS), or cisplatin. LMP was decreased by pretreating cells with U18666A, and there was a linear relationship between the cholesterol content of lysosomes and their resistance to permeabilization induced by MSDH. U18666A did not induce changes in expression or localization of 70-kDa heat shock proteins (Hsp70) or antiapoptotic Bcl-2 proteins known to protect the lysosomal membrane. Induction of autophagy also was excluded as a contributor to the protective mechanism. By using Chinese hamster ovary (CHO) cells with lysosomal cholesterol overload due to a mutation in the cholesterol transporting protein Niemann-Pick type C1 (NPC1), the relationship between lysosomal cholesterol accumulation and protection from lysosome-dependent cell death was confirmed. Cholesterol accumulation in lysosomes attenuates apoptosis by increasing lysosomal membrane stability.

Alterations in lipid homeostasis are implicated in several neurodegenerative diseases, although the mechanisms responsible are poorly understood. We evaluated the impact of cholesterol accumulation, induced by U18666A, quinacrine or mutations in the cholesterol transporting Niemann-Pick disease type C1 (NPC1) protein, on lysosomal stability and sensitivity to lysosome-mediated cell death. We found that neurons with lysosomal cholesterol accumulation were protected from oxidative stress-induced apoptosis. In addition, human fibroblasts with cholesterol-loaded lysosomes showed higher lysosomal membrane stability than controls. Previous studies have shown that cholesterol accumulation is accompanied by the storage of lipids such as sphingomyelin, glycosphingolipids and sphingosine and an up regulation of lysosomal associated membrane protein-2 (LAMP-2), which may also influence lysosomal stability. However, in this study the use of myriocin and LAMP deficient fibroblasts excluded these factors as responsible for the rescuing effect and instead suggested that primarily lysosomal cholesterol content determined the cellular sensitivity to toxic insults. Further strengthening this concept, depletion of cholesterol using methyl-β-cyclodextrin or 25-hydroxycholesterol decreased the stability of lysosomes and cells became more prone to undergo apoptosis. In conclusion, cholesterol content regulated lysosomal membrane permeabilization and thereby influenced cell death sensitivity. Our data suggests that lysosomal cholesterol modulation might be used as a therapeutic strategy for conditions associated with accelerated or repressed apoptosis.

Stress-induced heat shock protein 70 (Hsp70) effectively protects cells against apoptosis, although the anti-apoptotic mechanism is still undefined. Exposure of human melanocytes to heat and subsequent UVB irradiation increased the level of Hsp70 and pre-heating reduced UVB induced apoptosis. Immunofluorescence staining of Hsp70 in combination with staining of lysosomes (Lamp2) or mitochondria (Mitotracker^®) in pre-heated UVB exposed cells showed co-localization of Hsp70 with both lysosomes and mitochondria in the surviving cell population. Furthermore, UVB induced apoptosis was accompanied by lysosomal and mitochondrial membrane permeabilization, detected as release of cathepsin D and cytochrome c, respectively, which were prevented by heat pre-treatment. In purified fractions of lysosomes and mitochondria, recombinant Hsp70 attached to both lysosomal and mitochondrial membranes. Moreover, in apoptotic cells Bax was translocated from a diffuse cytosolic location into punctate mitochondrial-like structures, which was inhibited by Hsp70 induction. Such inhibition of Bax translocation was abolished by transfection with Hsp70 siRNA. Furthermore, Hsp70 siRNA eliminated the apoptosis preventive effect observed after pre-heating. These findings show Hsp70 to rescue melanocytes from UVB induced apoptosis by preventing release of cathepsins from lysosomes, Bax translocation and cytochrome c release from mitochondria.

Abbreviations: AIF, apoptosis-inducing factor; Hsp, heat shock protein; NAG, ß-N-acetylglucosaminidase; tBid, truncated Bid; UV, ultraviolet

We demonstrate UVA/B to induce apoptosis in human melanocytes through the mitochondrial pathway, displaying cytochrome c release, caspase-3 activation, and fragmentation of nuclei. The outcome of a death signal depends on the balance between positive and negative apoptotic regulators, such as members of the Bcl-2 protein family. Apoptotic melanocytes, containing fragmented nucleus, show translocation of the proapoptotic proteins Bax and Bid from the cytosol to punctate mitochondrial-like structures. Bcl-2, generally thought to be attached only to membranes, was in melanocytes localized in the cytosol as well. In the fraction of surviving melanocytes, that is, cells with morphologically unchanged nucleus, the antiapoptotic proteins Bcl-2 and Bcl-X_L were translocated to mitochondria following UVA/B. The lysosomal proteases, cathepsin B and D, which may act as proapoptotic mediators, were released from lysosomes to the cytosol after UVA/B exposure. Proapoptotic action of the cytosolic cathepsins was confirmed by microinjection of cathepsin B, which induced nuclear fragmentation. Bax translocation and apoptosis were markedly reduced in melanocytes after pretreatment with either cysteine or aspartic cathepsin inhibitors. No initial caspase-8 activity was detected, excluding involvement of the death receptor pathway. Altogether, our results emphasize translocation of Bcl-2 family proteins to have central regulatory functions of UV-induced apoptosis in melanocytes and suggest cathepsins to be proapoptotic mediators operating upstream of Bax.

UVB irradiation induced phosphorylation of JNK and subsequent apoptosis in human melanocytes. Depletion of both JNK1 and JNK2 expression using siRNA transfection, protected against apoptosis, as detected by decreased nuclear fragmentation and caspase-3 activity, as well as reduced translocation of Bax to mitochondria. Moreover, release of cathepsin B and D from lysosomes to the cytosol was reduced when JNK expression was suppressed by siRNA, demonstrating a JNK dependent regulation of lysosomal membrane permeabilization. In unirradiated control melanocytes, coimmunoprecipitation showed that Bim was sequestered by Mcl-1, which had a pro-survival function. After UVB irradiation, a significant decrease in Mcl-1 protein level was found, which was prevented by addition of a proteasome inhibitor. The interaction between Bim and Mcl-1 was reduced in response to UVB irradiation and Bim was phosphorylated in a JNK dependent manner. In conclusion, these findings Suggest JNK to have an important pro-apoptotic function following UVB irradiation in human melanocytes, by acting upstream of lysosomal membrane permeabilization and Bim phosphorylation.

Neuronal Pentraxin 2 (NP2, Narp), known to mediate clustering of glutamatergic AMPA receptors at synapses, is involved in activity-dependent synaptogenesis and synaptic plasticity. In experimental settings, antidepressant treatment as well as a stimulating environment has a positive influence on cognition and hippocampal plasticity. This study demonstrates that NP2 mRNA is robustly expressed in the hippocampus and the medial habenula (MHb), both regions implicated in cognitive functions. Furthermore, NP2 mRNA expression is enhanced in the hippocampal subregions as well as in the MHb after long-term treatment with antidepressant drugs of various monoaminergic profiles, indicating a common mode of action of different antidepressant drugs. This effect occurs at the time frame where clinical response is normally achieved. In contrast, neither environmental enrichment nor deprivation has any influence on long-term NP2 mRNA expression. These findings support an involvement of NP2 in the pathway of antidepressant induced plasticity, but not EE induced plasticity; that NP2 might constitute a common link for the action of different types of antidepressant drugs and that the MHb could be a putative region for further studies of NP2.

The most common types of benign gastric polyps are fundic gland polyps, hyperplastic polyps, and adenomas. The aim of this study was to determine on which morphological and functional background benign gastric polyps develop. The study includes 85 consecutive patients with gastric polyps and sex and age-matched controls without polyps selected at random from a general population sample. The type of polyp was hyperplastic in 52 (61%), fundic gland in 18 (21%), adenoma in 10 (12%), carcinoid in 2 (2%), hamartoma in 2 ( 2%), and inflammatory fibroid in 1 (1%) of the cases. Routine biopsies from the gastric corpus and antrum were examined for presence of gastritis and H. pylori. Blood samples were analyzed for H. pylori antibodies, H+, K+-ATPase antibodies, gastrin, and pepsinogen I. Patients with hyperplastic polyps had increased P-gastrin concentrations and S-H+, K+-ATPase antibody titers and decreased S-pepsinogen I concentrations with a high prevalence of atrophic corpus gastritis or pangastritis. A similar pattern was observed among patients with adenomas, whereas patients with fundic gland polyps had normal serology and a lower prevalence of gastritis and H. pylori infection than controls. In conclusion, hyperplastic polyps and adenomas are generally associated with atrophic gastritis. Patients with fundic gland polyps seem to have a sounder mucosa than controls. Whereas the risk of malignant gastric neoplasia is increased in patients with hyperplastic polyps or adenomas, this does not seem to be the case in patients with fundic gland polyps.

The unique absence of major histocompatibility complex class I antigen (MHC-I) expression in normal muscle is one possible mechanism protecting striated muscle. In order to define their possible involvement in protection of normal muscle. we investigated the expression of molecules involved in muscle fibre death and survival mechanisms (Bcl-2, Fas, Fas-ligand and TRAIL), focusing on disorders with possible involvement of cytotoxic T cells. We studied muscle biopsies from 20 healthy volunteers, from 10 patients affected by polymyositis and 10 by Duchenne muscular dystrophy. By using immunohistochemistry, Western blot and real-time PCR we detected a constitutional expression of Bcl-2 in healthy muscle, whereas the expression was weaker in disease processes. Fas-L and TRAIL were not detected in muscle fibres, and Fas only in muscle affected by disease. Our findings indicate that the major apoptotic protein Bcl-2 might have a hitherto unrecognized role in the protection of normal muscle.

Anorexia in response to immune challenge by Interleukin-1β (IL-1β) has been shown to be dependent on Prostaglandin E2 (PGE2) produced by the inducible enzyme microsomal prostaglandin E synthase-1 (mPGES-1). However, it is not known which of the four known PGE₂ receptors EP_1-4, encoded by the genes Ptger 1-4, that mediates the PGE₂-induced anorexia. Here we examined food intake in mice deficient in EP₁, EP₂ and EP₃, respectively, during normal conditions and following treatment with IL-1β. Neither of the gene deletions affected baseline food intake, and all the three genotypes displayed anorexia following IL-1β injection, similar to wild type mice. Previous work has demonstrated that the EP3 receptor is critical for the generation of fever, and that EP₁ and EP₃ receptors mediate inflammationinduced activation of the hypothalamic-pituitary-adrenal (HPA) axis. The present data, showing intact anorexigenic responses in EP₁ and EP₃ deficient mice, as well as in mice with deletion of the EP₂ receptor, hence suggest that PGE₂-elicited acute phase responses are mediated by distinct set or sets of PGE₂-receptors.

High activity of histone deacetylases (HDACs) has been documented in several types of cancer and may be associated with survival advantage. In a head and neck squamous cell carcinoma cell line, cisplatin-induced apoptosis was augmented by pretreatment with the HDAC inhibitor trichostatin Apoptosis was accompanied by lysosomal membrane permeabilization (LMP), as shown by immunoblotting of the lysosomal marker protease cathepsin B in extracted cytosol and by immunofluorescence. Moreover, LAMP-2 (lysosomal associated membrane protein-2) was translocated from lysosomal membranes and found in a digitonin extractable fraction together with cytosolic proteins and pretreatment with trichostatin A potentiated the release. Overall, protein level of LAMP-2 was decreased during cell death and, interestingly, inhibition of cysteine cathepsins, by the pan-cysteine cathepsin inhibitor zFA-FMK, prevented loss of LAMP-2. The importance of LAMP-2 for lysosomal membrane stability, was confirmed by showing that LAMP-2 knockout MEFs (mouse embryonic fibroblasts) were more sensitive to cisplatin as compared to the corresponding wildtype cells. Trichostatin A reduced lysosomal pH from 4.46 to 4.25 and cell death was prevented when lysosomal pH was increased by NH4Cl, or when inhibiting the activity of lysosomal proteases. We conclude that trichostatin A enhances cisplatin induced cell death by decreasing lysosomal pH, which augments cathepsin activity resulting in reduced LAMP-2 level, and might promote LMP.

The present study was undertaken to evaluate the possibility of using a panel of proteins and single nucleotide polymorphisms (SNPs) involved in apoptosis, growth control, and DNA repair as predictive markers for cisplatin sensitivity. For this purpose the intrinsic cisplatin sensitivity (ICS) was determined in 39 cell lines derived from squamous cell carcinomas of the head and neck using a colony-forming assay. In these cell lines and in normal oral keratinocytes (NOK), the expression of epidermal growth factor receptor (EGFR), Hsp70, Bax, Bcl-2, Bcl-XL, survivin, and COX-2 was determined. Moreover, the p53, MDM2, FGFR4, XPC, XPD, XRCC1, and XRCC3 genes were analyzed for the presence of specific single nucleotide polymorphisms (SNPs). Pearsons correlation test showed that EGFR was the only protein that was significantly correlated to the ICS (r=0.388, p=0.015). The combination of EGFR, Hsp70, Bax, and Bcl-2 gave the strongest correlation (r=0.566, p andlt;= 0.001), whereas Bax alone had the second highest influence on the ICS. Furthermore, all four SNPs within genes involved in DNA repair, i.e. XPC, XPD, XRCC1, and XRCC3, tended to influence the ICS. In order to find the combination of factors, on both protein and gene levels, with the highest correlation to ICS, a multivariate statistical calculation was performed. Our results indicate that SNPs in DNA repair genes (XRCC3(241) and XPD751) influence the ICS and together with the expression of EGFR, Hsp70, Bax, and Bcl-2, they could predict the cisplatin sensitivity of head and neck cancer cell lines (r=0.614, p andlt;= 0.001).

BACKGROUND: Radiotherapy is the main therapy for head and neck squamous cell carcinoma (HNSCC); however, treatment resistance and local recurrence are significant problems, highlighting the need for predictive markers. In this study, we evaluated selected proteins, mutations, and single nucleotide polymorphisms (SNPs) involved in apoptosis, cell proliferation, and DNA repair alone or combined as predictive markers for radioresponse in 42 HNSCC cell lines.

METHODS: The expression of epidermal growth factor receptor, survivin, Bax, Bcl-2, Bcl-X_L, cyclooxygenase-2, and heat shock protein 70 was analyzed by ELISA. Furthermore, mutations and SNPs in the p53 gene as well as SNPs in the MDM2, XRCC1, and XRCC3 genes were analyzed for their relation to radioresponse. To enable the evaluation of the predictive value of several factors combined, each cell line was allocated points based on the number of negative points (NNP) system, and the NNP sum was correlated with radioresponse.

RESULTS: Survivin was the only factor that alone was significantly correlated with the intrinsic radiosensitivity (r=0.36, p=0.02). The combination of survivin, Bax, Bcl-2, Bcl-XL, cyclooxygenase-2, and the p53 Arg72Pro polymorphism was found to most strongly correlate with radioresponse (r=0.553, p<0.001).

CONCLUSION: These data indicate that the intrinsic radiosensitivity of 42 HNSCC cell lines can be predicted by a panel of factors on both the protein and gene levels. Moreover, among the investigated factors, survivin was the most promising biomarker of radioresponse.

Purpose. The aim of this study was to get a deeper understanding into how adults with cerebral palsy (CP) experience physiotherapy and physical activity in a perspective from childhood to adulthood; and how personal and environmental factors influence possibilities for physiotherapy and physical activity. Method. Data was collected through interviews with 22 community-living adults (35-68 years) with CP, from five counties in Sweden. The questions were open-ended and the interviews were taped and transcribed to written language. The material was analysed through qualitative content analysis, a classification process resulting in different themes. Results. The narratives from the 22 informants, based on experiences from childhood to adulthood, resulted in a description of prerequisites for carrying out physiotherapy and physical activity. Five different themes were identified: (i) Being enjoyable, (ii) Giving effects, (iii) Being comprehensible, (iv) Being integrated in daily life, and (v) Supportive healthcare with competent professionals. Conclusion. The information from the interviews elucidates the importance of a lifelong support from healthcare professionals. Physiotherapists with attentiveness to different life situations in combination with good understanding and knowledge in CP could facilitate continuous physical activity in people growing up and ageing with CP.

Tobacco smoke contains substances capable of binding iron in an aqueous medium and transferring the metal into both organic solvents and intact mammalian red cells. This iron-binding activity is due to free fatty acids which are abundant in tobacco smoke and form 2:1 (free fatty acid:iron) chelates with ferrous iron. These earlier observations suggested that smoke-borne free fatty acids and the associated delocalization of iron within the lung might contribute to both the chronic pulmonary inflammation and the carcinogenesis associated with smoking. We now report that micromolar concentrations of iron or free fatty acid are not toxic to cultured human lung fibroblasts. However, when combined, the same low concentrations of iron and free fatty acid exert synergistic toxicity. Furthermore, the combination of free fatty acid and iron is highly mutagenic, inducing almost as many selectable mutations in the gene for hypoxanthine/guanine phosphoribosyl transferase as does benzo[a] pyrenediolepoxide, a class I carcinogen generated from benzo[a]pyrene present in cigarette smoke. The combination of free fatty acid and iron also promotes transformation of NIH 3T3 cells into an anchorage-independent phenotype. We conclude that free fatty acids in tobacco smoke may be important contributors to both the pulmonary damage and the carcinogenesis associated with smoking. © 2005 Elsevier Inc. All rights reserved.

Chronic iron overload has slow and insidious effects on heart, liver, and other organs. Because iron-driven oxidation of most biologic materials (such as lipids and proteins) is readily repaired, this slow progression of organ damage implies some kind of biological "memory." We hypothesized that cumulative iron-catalyzed oxidant damage to mtDNA might occur in iron overload, perhaps explaining the often lethal cardiac dysfunction. Real time PCR was used to examine the " intactness" of mttDNA in cultured H9c2 rat cardiac myocytes. After 3 -5 days exposure to high iron, these cells exhibited damage to mtDNA reflected by diminished amounts of near full-length 15.9-kb PCR product with no change in the amounts of a 16.1-kb product from a nuclear gene. With the loss of intact mtDNA, cellular respiration declined and mRNAs for three electron transport chain subunits and 16 S rRNA encoded by mtDNA decreased, whereas no decrements were found in four subunits encoded by nuclear DNA. To examine the importance of the interactions of iron with metabolically generated reactive oxygen species, we compared the toxic effects of iron in wild-type and rhoo cells. In wild-type cells, elevated iron caused increased production of reactive oxygen species, cytostasis, and cell death, whereas the rhoo cells were unaffected. We conclude that long-term damage to cells and organs in iron-overload disorders involves interactions between iron and mitochondrial reactive oxygen species resulting in cumulative damage to mtDNA, impaired synthesis of respiratory chain subunits, and respiratory dysfunction.

Objective: The aim of this study was to establish three-dimensional cultures originating from muscle biopsies and evaluate the viability and morphology. Method: Muscle biopsies from patients with suspected neuromuscular disorders were obtained and established as primary muscle tissue cultures. Tissue pieces, 1-2 mm of diameters, were placed in culture medium and subjected to sporadic stirring to prevent attachment and outgrowth as monolayer cells. Morphology and ability to attach to the surface were investigated by light microscopy. Viability was evaluated by Tc-99m-tetrofosmin uptake. After 1 month, histology was evaluated by light microscopy and immunocytochemistry. The findings of a healthy muscle and a dystrophic muscle were compared. Results: Initially, the tissue pieces were unshaped but formed spheroid-like structures during the culture period. For dystrophic muscle, attachment capacity to the surface was initially potent and decreased during the culture period, whereas control muscle showed weak attachment from the start that increased during the culture period. The uptake of Tc-99m-tetrofosmin increased in control muscle, while it decreased in dystrophic muscle, during the culture period. The histological investigation demonstrated larger destruction of myofiber, weaker satellite cell activation and reduced myofiber regeneration in the dystrophic muscle as compared to the control muscle. Conclusion: The cellular components of the muscle tissue can survive and proliferate as spheroid-like primary cultures. The cellular composition resembles the in vivo condition, which allows studies of degeneration of the original fibers, and activation and proliferation of the satellite cells. The culture system may provide better understanding of the degeneration and regeneration processes in different muscle disorders and allow investigations of pharmacological interventions.

Moderate lysosomal membrane permeabilization (LMP) is an important inducer of apoptosis. Macrophages are professional scavengers and are rich in hydrolytic enzymes and iron. In the present study, we found that LMP by lysosomotropic detergent MSDH resulted in early up-regulation of lysosomal cathepsins, oxidative stress and ferritin up-regulation, and cell death. Lysosomotropic base NH(4)Cl reduced the ferritin induction and oxidative stress in apoptotic cells induced by MSDH. Cysteine cathepsin inhibitors significantly protected cell death and oxidative stress, but had less effect on ferritin induction. We conclude that oxidative stress induced by lysosomal rupture causes ferritin induction with concomitant mitochondrial damage, which are the potential target for prevention of cellular oxidative stress and cell death induced by typical lysosomotropic substances in different disorders.

Histone H1 is an important constituent of chromatin which undergoes major structural rearrangements during mitosis. However, the role of H1, multiple H1 subtypes and H1 phosphorylation is still unclear. In normal human fibroblasts, phosphorylated H1 was found located in nuclei during prophase and in both cytoplasm and condensed chromosomes during metaphase, anaphase and telophase as detected by immunocytochemistry. Moreover, we detected remarkable differences in the distribution of the histone H1 subtypes H1.2, H1.3 and H1.5 during mitosis. H1.2 was found in chromatin during prophase, and almost solely in the cytoplasm of metaphase and early anaphase cells. In late anaphase it appeared in both chromatin and cytoplasm, and again in chromatin during telophase. H1.5 distribution pattern resembled that of H1.2, but some H1.5 remained situated in chromatin during metaphase and early anaphase. H1.3 was detected in chromatin in all cell cycle phases. We propose therefore, that H1 subtype translocation during mitosis is controlled by phosphorylation, in combination with H1 subtype inherent affinity. We conclude that H1 subtypes, or their phosphorylated variants, may be signalling molecules in mitosis or that they leave chromatin in a regulated way to give access for chromatin condensing factors or transcriptional regulators during mitosis.

OBJECTIVES To assess the value of bladder mapping and prostatic urethra biopsies for detection of urothelial carcinoma in situ (CIS). CIS of the urinary bladder is a flat high-grade lesion of the mucosa associated with a significant risk of progression to muscle-invasive disease. CIS is difficult to identify on cystoscopy, and definite diagnosis requires histopathology. Traditionally, if CIS is suspected, multiple cold-cup biopsies are taken from the bladder mucosa, and resection biopsies are obtained from the prostatic urethra in males. This approach is often called bladder mapping (BMAP). The accuracy of BMAP as a diagnostic tool is not known. PATIENTS AND METHODS Male patients with bladder cancer scheduled for cystectomy underwent cold-cup bladder biopsies (sidewalls, posterior wall, dome, trigone), and resection biopsies were taken from the prostatic urethra. After cystectomy, the surgical specimen was investigated in a standardised manner and subsequently compared with the BMAP biopsies for the presence of CIS. RESULTS The histopathology reports of 162 patients were analysed. CIS was detected in 46% of the cystoprostatectomy specimens, and multiple (greater than= 2) CIS lesions were found in 30%. BMAP (cold-cup bladder biopsies + resection biopsies from the prostatic urethra) provided sensitivity of 51% for any CIS, and 55% for multiple CIS lesions. The cold-cup biopsies for CIS in the bladder mucosa showed sensitivity and specificity of 46% and 89%, respectively. CONCLUSION Traditional cold-cup biopsies are unreliable for detecting CIS in bladder mucosa and negative findings must be interpreted with caution.

The formation of amyloid-β peptide (Aβ) aggregates at an early stage during the self-assembly process is an important factor in the development of Alzheimer’s disease. The toxic effect is believed to be exerted by prefibrillar species of Aβ. It is therefore important to identify which prefibrillar species are toxic and characterize their distinct properties. In the present study, we investigated the in vitro aggregation behavior of Aβ-derived peptides possessing different levels of neurotoxic activity, using fluorescence spectroscopy in combination with transmission electron microscopy. The toxicity of various Aβ aggregates was assessed by using cultures of human neuroblastoma cells. Through combined use of the fluorescence probe 8-anilino-1-napthalenesulfonate (ANS) and the novel luminescent probe pentamer formyl thiophene acetic acid (p-FTAA), we were able to identify those Aβ peptide-derived prefibrillar species which exhibited cellular toxicity. In particular, species, which formed early during the aggregation process and showed strong p-FTAA and ANS fluorescence, were the species that possessed toxic activities. Moreover, by manipulating the aggregation conditions, it was possible to change the capacity of the Aβ peptide to form nontoxic versus toxic species.

Interleukin-6 (IL-6) is critical for the lipopolysaccharide (LPS)-induced febrile response. However, the exact source(s) of IL-6 involved in regulating the LPS-elicited fever is still to be identified. One known source of IL-6 is hematopoietic cells, such as monocytes. To clarify the contribution of hematopoietically derived IL-6 to fever, we created chimeric mice expressing IL-6 either in cells of hematopoietic or, conversely, in cells of non-hematopoietic origin. This was performed by extinguishing hematopoetic cells in wild-type (WT) or IL-6 knockout (IL-6 KO) mice by whole-body irradiation and transplanting them with new stem cells. Mice lacking IL-6 in hematopoietic cells displayed normal fever to LPS and were found to have similar levels of IL-6 in the cerebrospinal fluid (CSF) and in plasma as well as similar expression of the IL-6 gene in the brain as WT mice. In contrast, IL-6 KO mice, with intact IL-6 production in cells of hematopoietic origin, only showed a minor elevation of the body temperature after peripheral LPS injection. While they displayed significantly elevated levels of IL-6 both in plasma and CSF compared with control mice, the increase was modest compared with that seen in LPS injected mice on WT background, the latter being approximately 20 times larger in magnitude. These results suggest that IL-6 of nonhematopoietic origin is the main source of IL-6 in LPS-induced fever, and that IL-6 produced by hematopoietic cells only plays a minor role.

Background

Histone deacetylase (HDAC) plays an important role in the deacetylation of histone, which can alter gene expression patterns and affect cell behavior associated with malignant transformation. The aims of this study were to investigate the relationships between HDAC1, HDAC2, clinicopathologic characteristics, patient prognosis and apoptosis, to clarify the mechanism of upregulation of the Axis inhibitor Axin (an important regulator of the Wnt pathway) by X-radiation and to elucidate the effect of siRNA on radiation therapy of non-small cell lung cancer (NSCLC).

Methods

HDAC1 and HDAC2 expression levels were measured by immunohistochemistry and reverse transcription PCR. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling and fluorescence activated cell sorting. BE1 cells expressing Axin were exposed to 2 Gy of X-radiation.

Results

Expression of HDAC1 and that of HDAC2 were correlated, and significantly higher in NSCLC tissues than in normal lung tissues (P < 0.05). HDAC1 and HDAC2 expression was correlated with pTNM stage and negatively correlated with differentiation of NSCLC and apoptotic index (P < 0.05). The prognosis of patients with low expression of HDAC1 and HDAC2 was better than that of those with high expression. X-radiation and siRNA inhibited HDAC1 and HDAC2 expression in NSCLC cells and Axin levels were significantly higher in BE1 cells.

Conclusions

X-radiation and siRNA inhibit expression of HDAC1 and HDAC2, weaken the inhibitory effect of HDAC on Axin, upregulate Axin expression and induce apoptosis of lung cancer cells. Inhibition of HDAC1 and HDAC2 is a means of enhancing the radiosensitivity of NSCLC.

Based on in vitro studies and short-term in vivo studies, all mercurials were for a long time considered as prototypic immunosuppressive substances. Recent studies have confirmed that organic mercurials such as methyl mercury (MeHg) and ethyl mercury (EtHg) are much more potent immunosuppressors than inorganic mercury (Hg). However, Hg interacts with the immune system in the presence of a susceptible genotype to cause immunostimulation, antinucleolar antibodies targeting fibrillarin, and systemic immune-complex (IC) deposits, a syndrome called Hg-induced autoimmunity (HgIA). Recent studies in mice with a susceptible genotype has revealed that the immunosuppressive effect of MeHg and EtHg will within 1-3 weeks be superseded by immunostimulation causing an HgIA-like syndrome. At equimolar doses of Hg, MeHg has the weakest immunostimulating, autoimmunogen, and IC-inducing effect, while the effect of thimerosal is similar to that of inorganic mercury. The immunosuppression is caused by the organic mercurials per se. Since they undergo rapid transformation to inorganic Hg, studies are being undertaken to delineate the importance of the organic substances per se and the newly formed inorganic Hg for induction of autoimmunity. © 2004 Elsevier B.V. All rights reserved.

Objective. Explanted tissue has been shown to keep adult human cells in organ culture with a preserved morphology for at least one month as spheres in a non-adhesive organ culture. In the present study, we explored whether also human biliary epithelium can be grown in this manner, because the result may be of interest in studies of hepato-biliary-pancreatic carciogenesis. Material and methods. Small tissue samples were obtained from the gallbladder wall of patients who had been operated upon with cholecystectomy. Fragments of about 300 µm in diameter from each patient were cultured and investigated with light microscopy at the time of explantation and after 5, 10, 20, 30 and 40 days of culture. Scanning and transmission electron microscopy were performed to demonstrate the ultrastructure. Incubation of cultured fragments with the vital dyes revealed a viable epithelium. Results. At the time of explantation, all the tissue fragments had a rough appearance with an uneven, torn periphery, while during the first few days of culture they became rounder with a smooth-looking surface covering the entire circumference. This spheroid morphology persisted for the remainder of the culture period. The core of the fragments harboured connective tissue with vascular elements, fibroblasts and leucocytes. Immunostaining for cytokeratin 7, 19 and 20 revealed a strong positive staining of the epithelium. Conclusions. These results show that biliary epithelium can be grown in vitro in a non-adhesive organ culture with their stroma. © 2008 Taylor & Francis.

F1 hybrids of SWR (H-2q) and SJL (H-2s) mice spontaneously develop a lupuslike condition in an age-dependent manner, and these two H-2 haplotypes also confer susceptibility to induction of systemic autoimmunity by heavy metals such as mercury, silver, and gold with antifibrillarin antibodies (AFA) as marker. The aim of this study was to determine how the mixing of two susceptible genomes might influence expression of idiopathic and induced autoimmunity over a period of 14 mo of exposure to mercury and silver. Spontaneous autoimmunity first appeared as antinuclear antibodies (ANA) in females at 10 wk of age and in males at 10 mo of age, and was followed by development of anti-chromatin antibodies. Antibodies to double-stranded DNA developed in 60% of males and 20% of females. Thirty percent of males and 10% of females developed a coarsely speckled ANA pattern associated with high titers of anti-Sm antibodies. Glomerular immune complex (IC) deposits and a proliferative glomerulonephritis were seen at 17 mo of age. The F1 hybrids treated with metals showed no exaggeration of spontaneous autoimmunity. However, the metals suppressed the spontaneous development of anti-Sm and antichromatin antibodies. The metal-induced AFA, linked to the H-2s and H-2q haplotype, reached a maximum after 3-4 mo of treatment and then declined, 33% of the silver-treated hybrids finally became AFA-negative, despite continuous treatment. The decline in ANoA during metal treatment is contrary to the situation in metal-treated SJL mice. This indicates that dominant SWR background genes suppressed induction of certain autoimmune traits in the (SWR x SJL)F1 hybrid mice. Copyright© Taylor & Francis Group, LLC.

Background: Combination treatment (chemoradiotherapy) is the standard treatment for locally advanced head and neck squamous cell carcinoma (HNSCC); however, treatment resistance and local recurrence are significant problems. A high level of epidermal growth factor receptor (EGFR) has been associated with a more aggressive phenotype as well as decreased responsiveness to radio- or chemotherapy. We examined the role of EGFR status and EGFR ligand expression for the treatment response. Methods: Intrinsic sensitivity to radiotherapy, cisplatin, and cetuximab treatments was investigated in 25 HNSCC cell lines. EGFR gene copy number, mRNA and protein expression, EGFR and Akt phosphorylation status, and mRNA expression of the EGFR ligands were analyzed using quantitative PCR and ELISA and assessed for their impact on treatment sensitivity. Results: Different treatment modalities yielded great diversity in outcome; of note, cetuximab treatment stimulated growth in one cell line. When treatments were combined primarily additive effects were observed. While radioresistance tended to be associated with a high level of phosphorylated EGFR (pEGFR; P = 0.09), cetuximab-resistant cells had low levels of pEGFR (P = 0.13). The three most cetuximab-sensitive cell lines had high EGFR gene copy numbers. Furthermore, cetuximab treatment response was significantly correlated with epiregulin mRNA expression (r = -0.408, P = 0.043). Cisplatin-resistant tumor cells expressed significantly lower levels of EGFR protein (P = 0.04) compared to cisplatin-sensitive cells and tended to have lower levels of phosphorylated Akt (pAkt; P = 0.13) and lower expression levels of amphiregulin (P = 0.18). Conclusions: Epidermal growth factor receptor status and ligand expression influence the treatment sensitivity of HNSCC cells and may be useful as predictive markers.

The epidermal growth factor receptor (EGFR) is commonly overexpressed in head and neck squamous cell carcinomas (HNSCC). The monoclonal antibody cetuximab (Erbitux®) inhibits its signaling and has been approved for treatment of HNSCC. However, since many patients do not benefit from cetuximab treatment, predictive biomarkers of cetuximab response are required. The present study aims at finding novel markers of cetuximab resistance.

The intrinsic cetuximab sensitivity of 35 HNSCC cell lines was determined, and revealed a great variation in the response between cell lines. Five cell lines (14%) were cetuximab sensitive, and 12 (34%) were resistant. Interestingly, two cell lines proliferated after cetuximab treatment.

10 cell lines (five cetuximab sensitive and five cetuximab resistant) were selected for gene copy number array analysis on the Affymetrix SNP 6.0 platform. 39 protein coding genes were amplified in cetuximab resistant cells and normal in sensitive cells, all present on genomic regions 11q22.1 or 5p13-15. Five genes were selected for quantitative PCR  verification, namely, YAP1 and TRPC6 (11q22.1) and PDCD6, TPPP, and PTGER4 (5p13-15). An extended panel of totally 10 cetuximab resistant and 10 sensitive cell lines verified that YAP1 amplified cells are cetuximab resistant.

YAP1 gene amplification was highly correlated to the YAP1 mRNA expression, which was significantly higher in cetuximab resistant cells than in sensitive. YAP1 downregulation resulted in increased cetuximab sensitivity in one of two cetuximab resistant cell lines investigated and growth inhibition in another. We conclude that YAP1 is a marker for cetuximab resistance in head and neck cancer.

In the last decade, a tremendous gain in knowledge concerning the molecular events of apoptosis signaling and execution has been achieved.

The aim of this thesis was to clarify the role of lysosomal membrane permeabilization and lysosomal proteases, cathepsins, in signaling for apoptosis. We identified cathepsin D as an important factor in staurosporine-induced human fibroblast cell death. After release to the cytosol, cathepsin D promoted mitochondrial release of cytochrome c by proteolytic activation of Bid. Cathepsin D-mediated cleavage of Bid generated two fragments with the apparent molecular mass of 15 and 19 kDa. By sequence analysis, three cathepsin D-specific cleavage sites, Phe24, Trp48, and Phe183, were identified. Moreover, we investigated the mechanism by which cathepsins escape the lysosomal compartment, and found that Bax is translocated from the cytosol to lysosomes upon staurosporine treatment. In agreement with these data, recombinant Bax triggered release of cathepsins from isolated rat liver lysosomes. Conceivably, the Bcl-2 family of proteins may govern release of pro-apoptotic factors from both lysosomes and mitochondria. The importance of lysosomal cathepsins in apoptosis signaling was studied also in oral squamous cell carcinoma cells following exposure to the redox-cycling drug naphthazarin or agonistic anti-Fas antibodies. In this experimental system, cathepsins were released to the cytosol, however, inhibition of neither cathepsin D, nor cysteine cathepsin activity suppressed cell death. Interestingly, cysteine cathepsins still appeared to be involved in activation of the caspase cascade. Cathepsins are often overexpressed and secreted by cancer cells, and it has been reported that extracellular cathepsins promote tumor growth and metastasis. Here, we propose that cathepsin B secreted from cancer cells may suppress cancer cell death by shedding of the Fas death receptor.

Defects in the regulation of apoptosis contribute to a wide variety of diseases, such as cancer, neurodegeneration and autoimmunity. Increased knowledge of the molecular details of apoptosis could lead to novel, more effective, treatments for these illnesses. This thesis emphasizes the importance of the lysosomal death pathway, which is a promising target for future therapeutic intervention.

A growing body of evidence suggests that components of the tumor microenvironment, including cancer-associated fibroblasts (CAF), may modulate the treatment sensitivity of tumor cells. Here, we investigated the possible influence of CAFs on the sensitivity of head and neck squamous cell carcinoma (HNSCC) cell lines to cetuximab, an antagonistic epidermal growth factor receptor (EGFR) antibody. Cetuximab treatment caused a reduction in the proliferation rate of HNSCC cell lines, whereas the growth of HNSCC-derived CAF cultures was unaffected. When tumor cells were cocultured with CAFs in a transwell system, the cetuximab-induced growth inhibition was reduced, and a complete protection from growth inhibition was observed in one of the tumor cell lines investigated. Media that had been conditioned by CAFs offered protection from cetuximab treatment in a concentration-dependent manner, suggesting that the resistance to treatment was mediated by CAF-derived soluble factors. The coculture of HNSCC cell lines with CAFs resulted in an elevated expression of matrix metalloproteinase-1 (MMP-1) in both the tumor cells and CAFs. Moreover, the CAF-induced resistance was partly abolished by the presence of an MMP inhibitor. However, CAFs treated with siRNA targeting MMP-1 still protected tumor cells from cetuximab treatment, suggesting that several MMPs may cooperate to facilitate resistance or that the protective effect is mediated by another member of the MMP family. These results identify a novel CAF-dependent modulation of cetuximab sensitivity and suggest that inhibiting MMPs may improve the effects of EGFR-targeted therapy.

Lysosomal membrane permeabilization (LMP) occurs in response to a large variety of cell death stimuli causing release of cathepsins from the lysosomal lumen into the cytosol where they participate in apoptosis signaling. In some settings, apoptosis induction is dependent on an early release of cathepsins, while under other circumstances LMP occurs late in the cell death process and contributes to amplification of the death signal. The mechanism underlying LMP is still incompletely understood; however, a growing body of evidence suggests that LMP may be governed by several distinct mechanisms that are likely engaged in a death stimulus- and cell-type-dependent fashion. In this review, factors contributing to permeabilization of the lysosomal membrane including reactive oxygen species, lysosomal membrane lipid composition, proteases, p53, and Bcl-2 family proteins, are described. Potential mechanisms to safeguard lysosomal integrity and confer resistance to lysosome-dependent cell death are also discussed.

Conclusion. Intracellular cysteine cathepsins are pro-apoptotic factors involved in activation of caspases in two oral squamous cell carcinoma (SCC) cell lines.

Objective. To study the possible involvement of lysosomal cathepsins in oral SCC cell apoptosis.

Material and methods. Apoptosis was induced in the two human oral SCC cell lines UT-SCC-20A and UT-SCC-24A using naphthazarin or anti-Fas antibodies, and was studied by analysis of caspase activity and nuclear morphology. Involvement of lysosomal cathepsins was investigated using the cysteine cathepsin inhibitor z-FA-FMK and the cathepsin D inhibitor pepstatin A. The amounts of cellular and soluble Fas death receptor were determined by ELISA.

Results. Release of cathepsins from the lysosomes to the cytosol was observed early in apoptosis. Cysteine cathepsins were found to be involved in activation of caspases in response to treatment with naphthazarin or anti-Fas antibodies, but inhibition of cysteine cathepsin activity was not sufficient to prevent cell death. Moreover, inhibition of cysteine cathepsin activity resulted in increased expression of the Fas death receptor, suggesting involvement of extracellular cysteine cathepsins in death receptor shedding.

There is increasing evidence that proteases other than caspases, for example, the lysosomal cathepsins B, D and L, are involved in apoptotic cell death. In the present study, we present data that suggest a role for cathepsin D in staurosporine-induced apoptosis in human foreskin fibroblasts. Cathepsin D and cytochrome c were detected partially released to the cytosol after exposure to 0.1 µM staurosporine for 1 h. After 4 h, activation of caspase-9 and -3 was initiated and later caspase-8 activation and a decrease in full-length Bid were detected. Pretreatment of cells with the cathepsin D inhibitor, pepstatin A, prevented cytochrome c release and caspase activation, and delayed cell death. These results imply that cytosolic cathepsin D is a key mediator in staurosporine-induced apoptosis. Analysis of the relative sequence of apoptotic events indicates that, in this cell type, cathepsin D acts upstream of cytochrome c release and caspase activation.

Modified low-density lipoprotein (LDL) has been implicated as an initiating or amplifying factor in atherogenesis. Some of its biological activities, such as apoptosis induction and upregulation of the scavenger receptor CD36, appear to share common signaling pathways in cells of the cardiovascular system. Exposure of low-differentiated monocytic cells to LDL modified with 15-lipoxygenase and secretory phospholipase A(2) induced apoptosis and upregulated CD36. Cell treatment with constituents of modified LDL, such as 13-hydroxyoctadecadienoic acid (13-HODE), 25-hydroxycholesterol, and lysophosphatidyl choline, and with an unrelated apoptogen (TNF-related apoptosis-inducing ligand) induced apoptosis. In contrast, only 13-HODE caused upregulation of CD36 expression. Cotreatment with the pan-caspase inhibitor z.VAD-fmk resulted in suppression of apoptosis, but was without any effect on CD36 expression. These data indicate that in monocytic cells enzymatically modified LDL is capable of inducing both apoptosis and upregulation of CD36 expression. However, in our cellular model, the two induction processes appear to be causally unrelated. (C) 2002 Elsevier Science (USA).

ATP-binding cassette transporter A1 (ABCA1) reduces amyloid-beta burden in transgenic mouse models of Alzheimer's disease (AD). Associations between ABCA1 polymorphisms and AD risk are also established. Little is known regarding the regulation of ABCA1 expression in the brain and how this may be affected by AD. In the present study we assessed ABCA1 mRNA and protein expression in the hippocampus of AD cases compared to controls. ABCA1 was clearly expressed in hippocampal neurons and expression was increased two- to three-fold in AD cases. The increased hippocampal ABCA1 expression was associated with increased APOE and PUMA gene expression, implying an association with neuronal stress. Consistent with this, treatment of SK-N-SH neurons with amyloid-beta peptide resulted in a 48% loss in survival and a significant upregulation of ABCA1, APOE, and PUMA gene expression. Studies in young (2 month) and old (12 month) transgenic mice expressing a familial AD form of human amyloid-beta protein precursor and presenilin-1 revealed a significant age-dependent upregulation of hippocampal Abca1 compared to wild-type control mice. However, hippocampal Apoe and Puma gene expression were not correlated with increased Abca1 expression in mice. Our data indicate that ABCA1 is upregulated in AD hippocampal neurons potentially via an amyloid-beta-mediated pathway.

Photo-cytotoxicity of zinc oxide (ZnO) nanowires (NWs) either bare or conjugated with photosensitizers was studied in dark and after ultraviolet light exposure, in human melanoma and foreskin fibroblast cells. ZnO NWs were grown on the capillary tip and then coated with photosensitizer. This coated tip was used as pointer for intracellular insertion of ZnO NWs and photosensitizer. ZnO NWs pointer was inserted into a specific cell and then irradiated with ultraviolet (UVA), which led to loss of mitochondrial membrane potential, as estimated by loss of the Mitotracker Red staining. Dissolved ZnO NWs showed cytotoxicity as detected by MTT viability assay and morphological evaluation. UVA-irradiation enhanced the toxicity and caused the production of reactive oxygen species (ROS) resulting in cell necrosis. ZnO NWs were photo-toxic for both normal and cancer cells, questioning their bio-safety.