Clusterin, a novel modulator of TGF-beta signaling, is involved in Smad2/3 stability

The Pigmentation of Blue Light Is Mediated by Both Melanogenesis Activation and Autophagy Inhibition through OPN3-TRPV1

Blue light, a high-energy radiation in the visible light spectrum, was recently reported to induce skin pigmentation. In this study, we investigated the involvement of TRPV1-mediated signaling along with OPN3 in blue light-induced melanogenesis as well as its signaling pathway. Operating downstream target of OPN3 in blue light-induced melanogenesis, blue light activated TRPV1 and upregulated its expression, resulting in calcium influx. Calcium ion induced the activation of calcium/calmodulin-dependent protein kinase II and MAPK. It also downregulated clusterin expression, leading to the nuclear translocation of PAX3, ultimately affecting melanin synthesis. In addition, blue light interfered with autophagy-mediated regulation of melanosomes by decreasing not only the interaction between clusterin and LC3B but the expression of activating transcription factor family. These findings demonstrate that the pigmenting effects of blue light are mediated by calcium/calmodulin-dependent protein kinase II- and MAPK-mediated signaling as well as clusterin-dependent inhibition of autophagy through OPN3-TRPV1-calcium influx, suggesting, to our knowledge, a previously unreported signaling pathway through which blue light regulates melanocyte biology. Furthermore, these results suggest that TRPV1 and clusterin could be potential therapeutic targets for blue light-induced pigmentation due to prolonged exposure to blue light.

Pathways to Alzheimer's Disease: The Intersecting Roles of Clusterin and Apolipoprotein E in Amyloid-β Regulation and Neuronal Health

One of the hallmarks of Alzheimer's disease (AD) is the deposition of amyloid-β (Aβ) within the extracellular spaces of the brain as plaques and along the blood vessels in the brain, a condition also known as cerebral amyloid angiopathy (CAA). Clusterin (CLU), or apolipoprotein J (APOJ), is a multifunctional glycoprotein that has a role in many physiological and neurological conditions, including AD. The apolipoprotein E (APOE) is a significant genetic factor in AD, and while the primary physiological role of APOE in the brain and peripheral tissues is to regulate lipid transport, it also participates in various other biological processes, having three basic human forms: APOE2, APOE3, and APOE4. Notably, the APOE4 allele substantially increases the risk of developing late-onset AD. The main purpose of this review is to examine the roles of CLU and APOE in AD pathogenesis in order to acquire a better understanding of AD pathogenesis from which to develop targeted therapeutic approaches.

Decoding CLU (Clusterin): Conquering cancer treatment resistance and immunological barriers

One major obstacle in the treatment of cancer is the presence of proteins resistant to cancer therapy, which can impede the effectiveness of traditional approaches such as radiation and chemotherapy. This resistance can lead to disease progression and cause treatment failure. Extensive research is currently focused on studying these proteins to create tailored treatments that can circumvent resistance mechanisms. CLU (Clusterin), a chaperone protein, has gained notoriety for its role in promoting resistance to a wide range of cancer treatments, including chemotherapy, radiation therapy, and targeted therapy. The protein has also been discovered to have a role in regulating the immunosuppressive environment within tumors. Its ability to influence oncogenic signaling and inhibit cell death bolster cancer cells resistant against treatments, which poses a significant challenge in the field of oncology. Researchers are actively investigating to the mechanisms by which CLU exerts its resistance-promoting effects, with the ultimate goal of developing strategies to circumvent its impact and enhance the effectiveness of cancer therapies. By exploring CLU's impact on cancer, resistance mechanisms, tumor microenvironment (TME), and therapeutic strategies, this review aims to contribute to the ongoing efforts to improve cancer treatment outcomes.

The clusterin connectome: Emerging players in chondrocyte biology and putative exploratory biomarkers of osteoarthritis

Introduction

Clusterin is amoonlighting protein that hasmany functions. It is amultifunctional Q6 holdase chaperone glycoprotein that is present intracellularly and extracellularly in almost all bodily fluids. Clusterin is involved in lipid transport, cell differentiation, regulation of apoptosis, and clearance of cellular debris, and plays a protective role in ensuring cellular survival. However, the possible involvement of clusterin in arthritic disease remains unclear. Given the significant potential of clusterin as a biomarker of osteoarthritis (OA), a more detailed analysis of its complex network in an inflammatory environment, specifically in the context of OA, is required. Based on the molecular network of clusterin, this study aimed to identify interacting partners that could be developed into biomarker panels for OA.

Methods

The STRING database and Cytoscape were used to map and visualize the clusterin connectome. The Qiagen Ingenuity Pathway Analysis (IPA) software was used to analyze and study clusterinassociated signaling networks in OA. We also analyzed transcription factors known to modulate clusterin expression, which may be altered in OA.

Results

The top hits in the clusterin network were intracellular chaperones, aggregate-forming proteins, apoptosis regulators and complement proteins. Using a text-mining approach in Cytoscape, we identified additional interacting partners, including serum proteins, apolipoproteins, and heat shock proteins.

Discussion

Based on known interactions with proteins, we predicted potential novel components of the clusterin connectome in OA, including selenoprotein R, semaphorins, and meprins, which may be important for designing new prognostic or diagnostic biomarker panels.

A meta-analysis of mRNA expression profiling studies in sheep with different FecB genotypes

The FecB mutation in the sheep BMPRIB is strongly correlated with high ovulation traits but its mechanism remains unclear. This study explored differentially expressed genes (DEGs) and their associated molecular mechanisms that may be involved in FecB mutation-induced high ovulation from the perspective of the hypothalamic-pituitary-gonadal (HPG) axis by conducting a systematic review and meta-analysis. The PubMed, EMBASE, CNKI, WanFang, and CBM databases were searched for eligible articles published before August 2022, focusing on mRNA sequencing of different tissues in the HPG axis in sheep with different FecB genotypes. A total of 6555 DEGs were identified from the analysis of six published articles and experimental results from our laboratory. The DEGs were screened by vote-counting rank and robust rank aggregation. Among these, in the follicular phase, FKBP5, CDCA7 and CRABP1 were upregulated in the hypothalamus. INSM2 was upregulated, while LDB3 was downregulated in the pituitary. CLU, SERPINA14, PENK, INHA and STAR were upregulated, while FERMT2 and NPY1R were downregulated in the ovary. On the HPG axis, TAC1 was upregulated and NPNT was downregulated. Many DEGs were found in sheep with different FecB genotypes. The genes FKBP5, CDCA7, CRABP1, INSM2, LDB3, CLU, SERPINA14, PENK, INHA, STAR, FERMT2, NPY1R, TAC1 and NPNT, may be associated with FecB mutation-induced high ovulation in different tissues. These candidate genes will further improve the mechanism of multiple fertility traits induced by the FecB mutation from the perspective of the HPG axis.

The Role of Clusterin Transporter in the Pathogenesis of Alzheimer’s Disease at the Blood–Brain Barrier Interface: A Systematic Review

Alzheimer’s disease (AD) is considered a chronic and debilitating neurological illness that is increasingly impacting older-age populations. Some proteins, including clusterin (CLU or apolipoprotein J) transporter, can be linked to AD, causing oxidative stress. Therefore, its activity can affect various functions involving complement system inactivation, lipid transport, chaperone activity, neuronal transmission, and cellular survival pathways. This transporter is known to bind to the amyloid beta (Aβ) peptide, which is the major pathogenic factor of AD. On the other hand, this transporter is also active at the blood–brain barrier (BBB), a barrier that prevents harmful substances from entering and exiting the brain. Therefore, in this review, we discuss and emphasize the role of the CLU transporter and CLU-linked molecular mechanisms at the BBB interface in the pathogenesis of AD.

Exploring the Role of CLU in the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic and devastating neurodegenerative disorder that is affecting elderly people at an increasing rate. Clusterin (CLU), an extracellular chaperone, is an ubiquitously expressed protein that can be identified in various body fluids and tissues. Expression of CLU can lead to various processes including suppression of complement system, lipid transport, chaperone function, and also controlling neuronal cell death and cell survival mechanisms. Studies have confirmed that the level of CLU expression is increased in AD. Furthermore, CLU also decreased the toxicity and aggregation of amyloid beta (Aβ). However when the Aβ level was far greater than CLU, then the amyloid generation was increased. CLU was also found to incorporate in the amyloid aggregates, which were more harmful as compared with the Aβ42 aggregates alone. Growing evidence indicates that CLU plays roles in AD pathogenesis via various processes, including aggregation and clearance of Aβ, neuroinflammation, lipid metabolism, Wnt signaling, copper homeostasis, and regulation of neuronal cell cycle and apoptosis. In this article, we represent the critical interaction of CLU and AD based on recent advances. Furthermore, we have also focused on the Aβ-dependent and Aβ-independent mechanisms by which CLU plays a role in AD pathogenesis.

Transcriptional analysis of cleft palate in TGFβ3 mutant mice

Cleft palate (CP) is one of the most common craniofacial birth defects, impacting about 1 in 800 births in the USA. Tgf-β3 plays a critical role in regulating murine palate development, and Tgf-β3 null mutants develop cleft palate with 100% penetrance. In this study, we compared global palatal transcriptomes of wild type (WT) and Tgf-β3 −/− homozygous (HM) mouse embryos at the crucial palatogenesis stages of E14.5, and E16.5, using RNA-seq data. We found 1,809 and 2,127 differentially expressed genes at E16.5 vs. E14.5 in the WT and HM groups, respectively (adjusted p < 0.05; |fold change|> 2.0). We focused on the genes that were uniquely up/downregulated in WT or HM at E16.5 vs. E14.5 to identify genes associated with CP. Systems biology analysis relating to cell behaviors and function of WT and HM specific genes identified functional non-Smad pathways and preference of apoptosis to epithelial-mesenchymal transition. We identified 24 HM specific and 11 WT specific genes that are CP-related and/or involved in Tgf-β3 signaling. We validated the expression of 29 of the 35 genes using qRT-PCR and the trend of mRNA expression is similar to that of RNA-seq data . Our results enrich our understanding of genes associated with CP that are directly or indirectly regulated via TGF-β.

The Multiple Roles and Therapeutic Potential of Molecular Chaperones in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancer types in men worldwide. Heat shock proteins (HSPs) are molecular chaperones that are widely implicated in the pathogenesis, diagnosis, prognosis, and treatment of many cancers. The role of HSPs in PCa is complex and their expression has been linked to the progression and aggressiveness of the tumor. Prominent chaperones, including HSP90 and HSP70, are involved in the folding and trafficking of critical cancer-related proteins. Other members of HSPs, including HSP27 and HSP60, have been considered as promising biomarkers, similar to prostate-specific membrane antigen (PSMA), for PCa screening in order to evaluate and monitor the progression or recurrence of the disease. Moreover, expression level of chaperones like clusterin has been shown to correlate directly with the prostate tumor grade. Hence, targeting HSPs in PCa has been suggested as a promising strategy for cancer therapy. In the current review, we discuss the functions as well as the role of HSPs in PCa progression and further evaluate the approach of inhibiting HSPs as a cancer treatment strategy.

Proteomics biomarkers for solid tumors: Current status and future prospects

Cancer is a heterogeneous multifactorial disease, which continues to be one of the main causes of death worldwide. Despite the extensive efforts for establishing accurate diagnostic assays and efficient therapeutic schemes, disease prevalence is on the rise, in part, however, also due to improved early detection. For years, studies were focused on genomics and transcriptomics, aiming at the discovery of new tests with diagnostic or prognostic potential. However, cancer phenotypic characteristics seem most likely to be a direct reflection of changes in protein metabolism and function, which are also the targets of most drugs. Investigations at the protein level are therefore advantageous particularly in the case of in-depth characterization of tumor progression and invasiveness. Innovative high-throughput proteomic technologies are available to accurately evaluate cancer formation and progression and to investigate the functional role of key proteins in cancer. Employing these new highly sensitive proteomic technologies, cancer biomarkers may be detectable that contribute to diagnosis and guide curative treatment when still possible. In this review, the recent advances in proteomic biomarker research in cancer are outlined, with special emphasis placed on the identification of diagnostic and prognostic biomarkers for solid tumors. In view of the increasing number of screening programs and clinical trials investigating new treatment options, we discuss the molecular connections of the biomarkers as well as their potential as clinically useful tools for diagnosis, risk stratification and therapy monitoring of solid tumors.

Amyloid β peptide promotes lysosomal degradation of clusterin via sortilin in hippocampal primary neurons

Progressive accumulation of amyloid-β peptide (Aβ) in the brain is implicated as the central event in the development of Alzheimer's disease (AD). It is thought that extracellular Aβ triggers toxic signals leading to neurodegeneration. The events downstream of Aβ however are not entirely clear. Clusterin (Apo J) is one of the major risk factors for sporadic form of AD. Clusterin binds to Aβ and prevents Aβ aggregation. In addition, clusterin promotes Aβ degradation and accelerates Aβ clearance from the brain. Clusterin thus protects neurons from Aβ and loss of clusterin level in the brain is implicated as promoting AD pathology. In this study, we found that the level of clusterin protein but not mRNA is reduced in the brains of 3xTg-AD mice. When rat hippocampal primary neurons were treated with Aβ1-42, level of clusterin protein but not mRNA was downregulated. Aβ1-42-induced downregulation of clusterin was blocked by lysosome inhibitors bafilomycin A1 and ammonium chloride. In neurons, Aβ1-42 induced expression of sortilin, a lysosomal sorting protein that targets proteins to lysosome for degradation. In BE(2) M17 human neuroblastoma cells, clusterin bound to sortilin and when sortilin expression was silenced, Aβ1-42-induced clusterin downregulation was almost completely blocked. Our data demonstrate that in neurons, Aβ1-42 promotes lysosomal degradation of clusterin by inducing expression of sortilin and provide a novel mechanism by which Aβ promotes AD pathogenesis.

Clusterin as a therapeutic target

INTRODUCTION

Clusterin (CLU) is a stress-activated, ATP-independent molecular chaperone, normally secreted from cells, that is up-regulated in Alzheimer disease and in many cancers. It plays important roles in protein homeostasis/proteostasis, inhibition of cell death pathways, and modulation of pro-survival signalling and transcriptional networks. Changes in the CLU gene locus are highly associated with Alzheimer disease, and many therapy-resistant cancers over-express CLU. The extensive post-translational processing and heterogeneous oligomerization of CLU have so far prevented any definitive structure determination. This in turn has meant that targeting CLU with small molecule inhibitors is challenging. Therefore, inhibiting CLU at the gene-expression level using siRNA or antisense is a valid approach to inhibit its function. Areas covered: This article reviews recent advances regarding the role of CLU in proteostasis, cellular trafficking, human diseases, and signalling pathways involved in oncogenesis. It addresses the rationale for CLU as a therapeutic target in cancer, and the current status of pre-clinical and clinical studies using CLU antisense inhibitor OGX011. Expert opinion: Discusses challenges facing the therapeutic targeting of CLU including rapid changes in the treatment landscape for prostate cancer with multiple new FDA approved drugs, selection of windows of intervention, and potential side effects when silencing CLU expression.

Plasma Clusterin and the CLU Gene rs11136000 Variant Are Associated with Mild Cognitive Impairment in Type 2 Diabetic Patients

Objective: Type 2 diabetes mellitus (T2DM) is related to an elevated risk of mild cognitive impairment (MCI). Plasma clusterin is reported associated with the early pathology of Alzheimer's disease (AD) and longitudinal brain atrophy in subjects with MCI. The rs11136000 single nucleotide polymorphism within the clusterin (CLU) gene is also associated with the risk of AD. We aimed to investigate the associations among plasma clusterin, rs11136000 genotype and T2DM-associated MCI.

Methods: A total of 231 T2DM patients, including 126 MCI and 105 cognitively healthy controls were enrolled in this study. Demographic parameters were collected and neuropsychological tests were conducted. Plasma clusterin and CLU rs11136000 genotype were examined.

Results: Plasma clusterin was significantly higher in MCI patients than in control group (p = 0.007). In subjects with MCI, plasma clusterin level was negatively correlated with Montreal cognitive assessment and auditory verbal learning test_delayed recall scores (p = 0.027 and p = 0.020, respectively). After adjustment for age, educational attainment, and gender, carriers of rs11136000 TT genotype demonstrated reduced risk for MCI compared with the CC genotype carriers (OR = 0.158, χ² = 4.113, p = 0.043). Multivariable regression model showed that educational attainment, duration of diabetes, high-density lipoprotein cholesterol (HDL-c), and plasma clusterin levels are associated with MCI in T2DM patients.

Conclusions: Plasma clusterin was associated with MCI and may reflect a protective response in T2DM patients. TT genotype exhibited a reduced risk of MCI compared to CC genotype. Further investigations should be conducted to determine the role of clusterin in cognitive decline.

Trial registration Advanced Glycation End Products Induced Cognitive Impairment in Diabetes: BDNF Signal Meditated Hippocampal Neurogenesis ChiCTR-OCC-15006060; http://www.chictr.org.cn/showproj.aspx?proj=10536

Silver nanoparticles/chitosan oligosaccharide/poly(vinyl alcohol) nanofiber promotes wound healing by activating TGFβ1/Smad signaling pathway

Wound healing occupies a remarkable place in everyday pathology and remains a challenging clinical problem. In our previous study, we prepared a silver nanoparticle/chitosan oligosaccharide/poly(vinyl alcohol) (PVA/COS-AgNPs) nanofiber via electrospinning and revealed that it could promote wound healing; however, the healing mechanism remained unknown. Therefore, we aimed to clarify the mechanism underlying the accelerated healing effect of the PVA/COS-AgNPs nanofiber. The TGFβ1/Smad signaling pathway is actively involved in wound healing. Considering the key role of this signaling pathway in wound healing, our preliminary study showed that the TGFβ1 level was significantly increased during the early stage of wound healing. Thus, in this study, hematoxylin-eosin, Masson's trichrome, immunofluorescent staining, hydroxyproline content, quantitative real-time polymerase chain reaction, and Western blot analyses were used to analyze the wound healing in a rat model treated with gauze, the PVA/COS-AgNPs nanofiber, and the nanofiber plus SB431542 (an inhibitor of TGFβ1 receptor kinase). The results showed that the PVA/COS-AgNPs nanofiber promoted wound healing and upregulated the expression levels of cytokines associated with the TGFβ1/Smad signaling pathway such as TGFβ1, TGFβRI, TGFβRII, collagen I, collagen III, pSmad2, and pSmad3. Inhibiting this pathway with SB431542 resulted in prevention of the PVA/COS-AgNPs nanofiber-associated salutary effects on the early stage of wound healing and relative cytokines expression. In conclusion, the wound healing effect of the PVA/COS-AgNPs nanofiber involves activation of the TGFβ1/Smad signaling pathway.

Secreted clusterin (sCLU) regulates cell proliferation and chemosensitivity to cisplatin by modulating ERK1/2 signals in human osteosarcoma cells

Background

Several studies have shown that secreted clusterin (sCLU) up-regulation in multi-drug resistant osteosarcoma (OS) cells relates to enhanced drug resistance. Furthermore, sCLU silencing directed against sCLU induces significant reduction of cellular growth and sensitizes OS cells to chemotherapy. However, the molecular mechanisms underlying the effect of sCLU on OS cells are not known.

Methods

To evaluate the roles and possible mechanisms of sCLU in chemoresistance of OS cells to cisplatin (DPP), we utilized RNA interference to knockdown sCLU expression in the sCLU-rich U-2 OS cells and to overexpress sCLU in the sCLU-poorer KH OS cells, and further assessed the cell viability and chemosensitivity to DDP as well as possible signaling transduction pathways.

Results

The data showed that sCLU depletion inhibited growth and sensitized sCLU-rich U-2 OS cells to cisplatin in vitro and in vivo by inducing inactivation of ERK1/2, and sCLU overexpression promoted growth and increased resistance of sCLU-less KH OS cells to cisplatin in vitro and in vivo by activation of ERK1/2.

Conclusions

The data also suggests critical roles of sCLU in OS cell chemoresistance to DPP and raises the possibility of sCLU depletion as a promising approach to OS therapy.

Pathway bridge based multiobjective optimization approach for lurking pathway prediction

Ovarian carcinoma immunoreactive antigen-like protein 2 (OCIAD2) is a protein with unknown function. Frequently methylated or downregulated, OCIAD2 has been observed in kinds of tumors, and TGFβ signaling has been proved to induce the expression of OCIAD2. However, current pathway analysis tools do not cover the genes without reported interactions like OCIAD2 and also miss some significant genes with relatively lower expression. To investigate potential biological milieu of OCIAD2, especially in cancer microenvironment, a nova approach pbMOO was created to find the potential pathways from TGFβ to OCIAD2 by searching on the pathway bridge, which consisted of cancer enriched looping patterns from the complicated entire protein interactions network. The pbMOO approach was further applied to study the modulator of ligand TGFβ1, receptor TGFβR1, intermediate transfer proteins, transcription factor, and signature OCIAD2. Verified by literature and public database, the pathway TGFβ1-TGFβR1-SMAD2/3-SMAD4/AR-OCIAD2 was detected, which concealed the androgen receptor (AR) which was the possible transcription factor of OCIAD2 in TGFβsignal, and it well explained the mechanism of TGFβ induced OCIAD2 expression in cancer microenvironment, therefore providing an important clue for the future functional analysis of OCIAD2 in tumor pathogenesis.

The physiological roles of apolipoprotein J/clusterin in metabolic and cardiovascular diseases

Several isoforms of apolipoprotein J/clusterin (CLU) are encoded from a single gene located on chromosome 8 in humans. These isoforms are ubiquitously expressed in the tissues, and have been implicated in aging, neurodegenerative disorders, cancer progression, and metabolic/cardiovascular diseases including dyslipidemia, diabetes, atherosclerosis and myocardial infarction. The conventional secreted form of CLU (sCLU) is thought to be a component of high density lipoprotein-cholesterol. sCLU functions as a chaperone for misfolded proteins and it is thought to promote survival by reducing oxidative stress. Nuclear CLU, a truncated CLU formed by alternative splicing, is responsible for promoting apoptosis via a Bax-dependent pathway. There are putative regulatory sites in the promoter regions of CLU, which are occupied by transcription factors such as transforming growth factor (TGF)-β inhibitory element, activator protein-1, CLU-specific elements, and carbohydrate response element. However, the molecular mechanisms underlying the distinct roles of CLU in a variety of conditions remain unclear. Although the function of CLU in cancer or neurological disease has been studied intensively for three decades, physiological roles of CLU seem unexplored in the cardiovascular system and metabolic diseases. In this review, we will discuss general characteristics and regulations of CLU based on previous literature and assess the recent findings associated with its physiological roles in different tissues including the vasculature, heart, liver, kidney, adipose tissue, and brain.

Expression of Clu and Tgfb1 during murine tooth development: effects of in-vivo transfection with anti-miR-214

Expression of clusterin (Clu) in the murine first molar tooth germ was markedly increased at postnatal developmental stages. The time-course of expression of this gene paralleled those of other genes encoding proteins involved during the secretory phase of odontogenesis, as described previously. Immunohistochemical studies of clusterin in murine molar tooth germs suggested this protein to be located in outer enamel epithelium, regressing enamel organ, secretory ameloblasts, and the dental epithelium connecting the tooth to the oral epithelium at an early eruptive stage. Immunolabelling of transforming growth factor beta-1 (TGF-β1) revealed it to be located close to clusterin. The levels of expression of Clu and Tgfb1 were markedly decreased following in-vivo transfection with anti-miR-214. In contrast, the expression of several genes associated with regulation of growth and development were increased by this treatment. We suggest that clusterin has functions during secretory odontogenesis and the early eruptive phase. Bioinformatic analysis after treatment with anti-miR-214 suggested that, whilst cellular activities associated with tooth mineralization and eruption were inhibited, activities associated with an alternative developmental activity (i.e. biosynthesis of contractile proteins) appeared to be stimulated. These changes probably occur through regulation mediated by a common cluster of transcription factors and support suggestions that microRNAs (miRNAs) are highly significant as regulators of differentiation during odontogenesis.

Reduction in serum clusterin is a potential therapeutic biomarker in patients with castration-resistant prostate cancer treated with custirsen

Elevated levels of clusterin (CLU), a stress-induced and secreted cytoprotective chaperone, are associated with advanced tumor stage, metastasis, treatment resistance, and adverse outcome in several cancers. Custirsen, a second-generation antisense oligonucleotide, inhibits CLU production in tumor cells and reduces serum CLU levels. A Phase 2 study evaluated custirsen in combination with second-line chemotherapy in men with metastatic castration-resistant prostate cancer (mCRPC) who had progressed while on or within 6 months of first-line docetaxel-based chemotherapy. Exploratory analyses evaluated serum CLU levels during custirsen treatment and correlative clinical effects on prostate-specific antigen (PSA) response, overall survival, and any relationship between serum CLU and PSA. Men with mCRPC were treated with mitoxantrone/prednisone/custirsen (MPC, n = 22) or docetaxel retreatment/prednisone/custirsen (DPC plus DPC-Assigned, n = 45) in an open-label, multicenter study. Subject-specific profiles of PSA and serum CLU levels during treatment were characterized using statistical modeling to compute subject-specific summary measures; these measures were analyzed for relationship to survival using proportional hazard regression. Estimated individual serum CLU response profiles were scored as below or at/above the median level for the population through 100 days postrandomization. Median survival was longer for subjects scoring below the median serum CLU level compared with subjects at/above the median level, respectively (MPC: 15.1 months vs. 6.2 months; DPC-Pooled: 17.0 months vs. 12.1 months). Lowered serum CLU levels during custirsen treatment when in combination with either chemotherapy regimen were predictive of longer survival in mCRPC. These results support further evaluation of serum CLU as a therapeutic biomarker.

Secretory clusterin contributes to oxaliplatin resistance by activating Akt pathway in hepatocellular carcinoma

Secretory clusterin (sCLU) is expressed in numerous cancers and is associated with the resistance to chemotherapy. However, the role of sCLU in the resistance of hepatocellular carcinoma (HCC) to oxaliplatin (OXA), a recently used third-generation platinum agent, remains unclear. The stable transfectants that are depleted of or overexpress sCLU and OXA-resistant cells were generated using human HCC cells. Overexpression of sCLU abrogated OXA-induced inhibition of cell growth and cell apoptosis, but depletion of sCLU synergized with OXA to inhibit cell growth and enhance cell apoptosis, by regulating proteins involved in mitochondrial apoptosis pathways, such as Bcl-2, Bax, Bcl-xL and caspase-9, and affecting phosphorylation of Akt and GSK-3β. Overexpression of sCLU in either OXA-resistant cells or stable transfectants that overexpress sCLU significantly increased phosphorylated Akt. However, specific inhibition of Akt enhanced sensitivity of sCLU-overexpressing cells to OXA, but had no effect on sCLU expression, suggesting that the regulatory effects between sCLU and pAkt may be in a one-way manner in HCC cells. The expression levels of sCLU affected the therapeutic efficacy of OXA to treat HCC tumors established in immunodeficiency mice. The results have demonstrated that sCLU contributes to OXA resistance by activating Akt pathway, indicating that sCLU may be a novel molecular target for overcoming OXA resistance in HCC.

Mesenchymal stem cells in non-small cell lung cancer--different from others? Insights from comparative molecular and functional analyses

BACKGROUND

Cancer-associated fibroblasts (CAF) play a vital role in lung cancer initiation and progression. Although mesenchymal stem cells (MSC) are considered progenitor cells of fibroblasts and show cancer modulating abilities themselves, analyses on their presence and properties in lung cancer are lacking so far.

METHODS

We performed a comparative molecular and functional analysis of MSC derived from non-small cell lung cancer (NSCLC) and corresponding normal lung tissue (NLT) of a total of 15 patients. MSC were identified and selected according to their mesenchymal multilineage differentiation capability and surface marker profile.

RESULTS

Compared to NLT-MSC, NSCLC-MSC showed accelerated growth kinetics and reduced sensitivity to cisplatin. Karyotyping, comparative genomic hybridization and multiplex fluorescence in situ hybridization revealed no chromosomal aberrations. However, gene expression profiling of NSCLC- and NLT-MSC indicated variable expression of 62 genes involved in proliferation, DNA repair, apoptosis, extracellular matrix synthesis, tissue remodeling and angiogenesis. Differential expression of the selected candidate genes butyrylcholinesterase, clusterin and quiescin Q6 sulfhydryl oxidase 1 was validated by quantitative real-time PCR and, on protein level, by immunohistochemical analyses of original tumor tissue. Upon exposure to tumor cell-conditioned medium or transforming growth factor-β, both, NSCLC-MSC and NLT-MSC acquired expression of α-smooth muscle actin (α-SMA), a major characteristics of CAF.

CONCLUSIONS

This study indicates that NSCLC tissue contains MSC with specific molecular and functional properties. These cells might represent a progenitor reservoir for CAF and thus crucially contribute to lung cancer progression.

Proteomic analysis on N, N'-dinitrosopiperazine-mediated metastasis of nasopharyngeal carcinoma 6-10B cells

BACKGROUND

Nasopharyngeal carcinoma (NPC) has a high metastatic feature. N,N'-Dinitrosopiperazine (DNP) is involved in NPC metastasis, but its mechanism is not clear. The aim of this study is to reveal the pathogenesis of DNP-involved metastasis. 6-10B cells with low metastasis are from NPC cell line SUNE-1, were used to investigate the mechanism of DNP-mediated NPC metastasis.

RESULTS

6-10B cells were grown in DMEM containing 2H4-L-lysine and 13C 6 15 N4-L-arginine or conventional L-lysine and L-arginine, and identified the incorporation of amino acid by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Labeled 6-10B cells were treated with DNP at 0 -18 μM to establish the non-cytotoxic concentration (NCC) range. NCC was 0 -10 μM. Following treatment with DNP at this range, the motility and invasion of cells were detected in vitro, and DNP-mediated metastasis was confirmed in the nude mice. DNP increased 6-10B cell metastasis in vitro and vivo. DNP-induced protein expression was investigated using a quantitative proteomic. The SILAC-based approach quantified 2698 proteins, 371 of which showed significant change after DNP treatment (172 up-regulated and 199 down-regulated proteins). DNP induced the change in abundance of mitochondrial proteins, mediated the status of oxidative stress and the imbalance of redox state, increased cytoskeletal protein, cathepsin, anterior gradient-2, and clusterin expression. DNP also increased the expression of secretory AKR1B10, cathepsin B and clusterin 6-10B cells. Gene Ontology and Ingenuity Pathway analysis showed that DNP may regulate protein synthesis, cellular movement, lipid metabolism, molecular transport, cellular growth and proliferation signaling pathways.

CONCLUSION

DNP may regulate cytoskeletal protein, cathepsin, anterior gradient-2, and clusterin expression, increase NPC cells motility and invasion, is involved NPC metastasis.

Knockdown of clusterin sensitizes pancreatic cancer cells to gemcitabine chemotherapy by ERK1/2 inactivation

OBJECTIVES

To study the hypothesis that gemcitabine treatment augments the chemoresistance to gemcitabine by clusterin (sCLU) upregulation. Clusterin inhibition could augment the chemosensitivity of human pancreatic cancer cells by inhibition of clusterin-dependent pERK1/2 activation.

METHODS

Clusterin was silenced by serial concentration of OGX-011 transfection in pancreatic cancer MIAPaCa-2 and BxPC-3 cell lines, then treated with serial concentration of gemcitabine. After the cells were treated with OGX-011 for 8 h, the cells were then treated with 5 μM ERK inhibitor PD98059 for 18 h or transfected with a wt-pERK-expressing plasmid into these cells for 24 h, after which the cells were treated with 1.0 uM gemcitabine for 24-72 h. Cell proliferation was determined by MTT. Apoptosis was quantified by flow cytometry,.sCLU and pERK1/2 production was analyzed by western blot, and sCLU mRNA was analyzed by RT-PCR. Xenograft of established tumors was used to evaluate primary tumor growth and apoptosis after treatment with gemcitabine alone or in combination with OGX-011. Phosphorylated ERK1/2 and sCLU levels in tumor tissues were measured by TUNEL analysis.

RESULTS

As detected by MTT and FACS assay, a combination of gemcitabine + OGX-011 reflected the chemotherapeutic sensitivity and increased the gemcitabine -induced apoptosis in MIAPaCa-2 and BxPC-3 cells. Western blotting and RT-PCR analysis revealed that the expression of clusterin was higher in gemcitabine -resistant MIAPaCa-2 cells, however, decreased significantly after pretreatment with OGX-011. Furthermore, the OGX-011 or combination of gemcitabine + OGX-011 decreased the gemcitabine -induced activation of pERK1/2. wt-pERK-re-expression decreased OGX-011+ gemcitabine -induced apoptosis. Finally, OGX-011 in combination with gemcitabine substantially decreased the in vivo tumor growth and promoted apoptosis. Taken together, clusterin confers gmcitabine resistance in pancreatic cancer cells.

CONCLUSIONS

Knockdown of clusterin by OGX-011 transfection sensitizes pancreatic cancer cells to gemcitabine by inhibition of gemcitabine -induced clusterin-pERK1/2 activation.

Clusterin mediates TGF-β-induced epithelial-mesenchymal transition and metastasis via Twist1 in prostate cancer cells

TGF-β promotes epithelial-mesenchymal transition (EMT) and induces clusterin (CLU) expression, linking these genes to cancer metastasis. CLU is a pleiotropic molecular chaperone that confers survival and proliferative advantage to cancer cells. However, the molecular mechanisms by which TGF-β regulates CLU expression and CLU affects metastasis remain unknown. In this study, we report that the transcription factor Twist1 mediates TGF-β-induced CLU expression. By binding to E-boxes in the distal promoter region of CLU gene, Twist1 regulated basal and TGF-β-induced CLU transcription. In addition, CLU reduction reduced TGF-β induction of the mesenchymal markers, N-cadherin and fibronectin, thereby inhibiting the migratory and invasive properties induced by TGF-β. Targeted inhibition of CLU also suppressed metastasis in an in vivo model. Taken together, our findings indicate that CLU is an important mediator of TGF-β-induced EMT, and suggest that CLU suppression may represent a promising therapeutic option for suppressing prostate cancer metastatic progression.

Clusterin in Alzheimer's disease

Clusterin, also known as apolipoprotein J, is a ubiquitous multifunctional glycoprotein. Following its identification in 1983, clusterin was found to be clearly increased in Alzheimer's disease (AD). Later research demonstrated that clusterin could bind amyloid-beta (Abeta) peptides and prevent fibril formation, a hallmark of AD pathology. In addition to preventing excessive inflammation, intracellular clusterin was found to reduce apoptosis and oxidative stress. Although early studies were inconclusive, two recent large-scale genome-wide association studies (GWAS) independently identified variants within the clusterin gene as risk factors for developing AD. This review focuses on the characteristics of clusterin and possible mechanisms of its relationship to AD.

The role of clusterin in Alzheimer's disease: pathways, pathogenesis, and therapy

Genetic variation in clusterin gene, also known as apolipoprotein J, has been associated with Alzheimer's disease (AD) through replicated genome-wide studies, and plasma clusterin levels are associated with brain atrophy, baseline prevalence and severity, and rapid clinical progression in patients with AD, highlighting the importance of clusterin in AD pathogenesis. Emerging data suggest that clusterin contributes to AD through various pathways, including amyloid-β aggregation and clearance, lipid metabolism, neuroinflammation, and neuronal cell cycle control and apoptosis. Moreover, epigenetic regulation of the clusterin expression also seems to play an important role in the pathogenesis of AD. Emerging knowledge of the contribution of clusterin to the pathogenesis of AD presents new opportunities for AD therapy.

Clusterin attenuates the development of renal fibrosis

Upregulation of clusterin occurs in several renal diseases and models of nephrotoxicity, but whether this promotes injury or is a protective reaction to injury is unknown. Here, in the mouse unilateral ureteral obstruction model, obstruction markedly increased the expression of clusterin, plasminogen activator inhibitor-1 (PAI-1), type I collagen, and fibronectin. Compared with wild-type mice, clusterin-deficient mice exhibited higher levels of PAI-1, type I collagen, and fibronectin and accelerated renal fibrosis in response to obstruction. In cultured rat tubular epithelium-like cells, adenovirus-mediated overexpression of clusterin inhibited the expression of TGF-β-stimulated PAI-1, type I collagen, and fibronectin. Clusterin inhibited TGF-β-stimulated Smad3 activity via inhibition of Smad3 phosphorylation and its nuclear translocation. Moreover, intrarenal delivery of adenovirus-expressing clusterin upregulated expression of clusterin in tubular epithelium-like cells and attenuated obstruction-induced renal fibrosis. In conclusion, clusterin attenuates renal fibrosis in obstructive nephropathy. These results suggest that upregulation of clusterin during renal injury is a protective response against the development of renal fibrosis.

Prognostic gene-expression signature of carcinoma-associated fibroblasts in non-small cell lung cancer

The tumor microenvironment strongly influences cancer development, progression, and metastasis. The role of carcinoma-associated fibroblasts (CAFs) in these processes and their clinical impact has not been studied systematically in non-small cell lung carcinoma (NSCLC). We established primary cultures of CAFs and matched normal fibroblasts (NFs) from 15 resected NSCLC. We demonstrate that CAFs have greater ability than NFs to enhance the tumorigenicity of lung cancer cell lines. Microarray gene-expression analysis of the 15 matched CAF and NF cell lines identified 46 differentially expressed genes, encoding for proteins that are significantly enriched for extracellular proteins regulated by the TGF-β signaling pathway. We have identified a subset of 11 genes (13 probe sets) that formed a prognostic gene-expression signature, which was validated in multiple independent NSCLC microarray datasets. Functional annotation using protein-protein interaction analyses of these and published cancer stroma-associated gene-expression changes revealed prominent involvement of the focal adhesion and MAPK signaling pathways. Fourteen (30%) of the 46 genes also were differentially expressed in laser-capture-microdissected corresponding primary tumor stroma compared with the matched normal lung. Six of these 14 genes could be induced by TGF-β1 in NF. The results establish the prognostic impact of CAF-associated gene-expression changes in NSCLC patients.

Targeting the cytoprotective chaperone, clusterin, for treatment of advanced cancer

Many strategies used to kill cancer cells induce stress-responses that activate survival pathways to promote emergence of a treatment resistant phenotype. Secretory clusterin (sCLU) is a stress-activated cytoprotective chaperone up-regulated by many varied anticancer therapies to confer treatment resistance when overexpressed. sCLU levels are increased in several treatment recurrent cancers including castrate resistant prostate cancer, and therefore sCLU has become an attractive target in cancer therapy. sCLU is not druggable with small molecule inhibitors, therefore nucleotide-based strategies to inhibit sCLU at the RNA level are appealing. Preclinical studies have shown that antisense oligonucleotide (ASO) or siRNA knockdown of sCLU have preclinical activity in combination with hormone- and chemotherapy. Phase I and II clinical trial data indicate that the second generation ASO, custirsen (OGX-011), has biologic and clinical activity, suppressing sCLU expression in prostate cancer tissues by more than 90%. A randomized study comparing docetaxel-custirsen to docetaxel alone in men with castrate resistant prostate cancer reported improved survival by 7 months from 16.9 to 23.8 months. Strong preclinical and clinical proof-of-principle data provide rationale for further study of sCLU inhibitors in randomized phase III trials, which are planned to begin in 2010.

CLU "in and out": looking for a link

Cancer cells need to interact synergistically with their surrounding microenvironment to form a neoplasm and to progress further to colonize distant organs. The microenvironment can exert profound epigenetic effects on cells through cell-derived interactions between cells, or through cell-derived factors deposited into the microenvironment. Tumor progression implies immune-escaping and triggers several processes that synergistically induce a cooperation among transformed and stromal cells, that compete for space and resources such as oxygen and nutrients. Therefore, the extra cellular milieu and tissue microenvironment heterotypic interactions cooperate to promote tumor growth, angiogenesis, and cancer cell motility, through elevated secretion of pleiotropic cytokines and soluble factors. Clusterin (CLU), widely viewed as an enigmatic protein represents one of the numerous cellular factors sharing the intracellular information with the microenvironment and it has also a systemic diffusion, tightly joining the "In and the Out" of the cell with a still debated variety of antagonistic functions. The multiplicity of names for CLU is an indication of the complexity of the problem and could reflect, on one hand its multifunctionality, or alternatively could mask a commonality of function. The posited role for CLU, further supported as a cytoprotective prosurvival chaperone-like molecule, seems compelling, in contrast its tumor suppressor function, as a guide of the guardians of the genome (DNA-repair proteins Ku70/80, Bax cell death inducer), could really reflect the balanced expression of its different forms, most certainly depending on the intra- and extracellular microenvironment cross talk. The complicated balance of cytokines network and the regulation of CLU forms production in cancer and stromal cells undoubtedly represent a potential link among adaptative responses, genomic stability, and bystander effect after oxidative stresses and damage. This review focuses on the tumor-microenvironment interactions strictly involved in controlling local cancer growth, invasion, and distant metastases that play a decisive role in the regulation of CLU different forms expression and release. In addition, we focus on the pleiotropic action of the extracellular form of this protein, sCLU, that may play a crucial role in redirecting stromal changes, altering intercellular communications binding cell surface receptors and contributing to influence the secretion of chemokines in paracrine and autocrine fashion. Further elucidation of CLU functions inside and outside ("in and out") of cancer cell are warranted for a deeper understanding of the interplay between tumor and stroma, suggesting new therapeutic cotargeting strategies.

Transcriptome profiling of a TGF-beta-induced epithelial-to-mesenchymal transition reveals extracellular clusterin as a target for therapeutic antibodies

Transforming growth factor (TGF)-beta plays a dual role in tumorigenesis, switching from acting as a growth inhibitory tumor suppressor early in the process, to a tumor promoter in late-stage disease. Since TGF-beta's prometastatic role may be linked to its ability to induce tumor cell epithelial-to-mesenchymal transition (EMT), we explored TGF-beta's EMT-promoting pathways by analysing the transcriptome changes occurring in BRI-JM01 mammary tumor epithelial cells undergoing a TGF-beta-induced EMT. We found the clusterin gene to be the most highly upregulated throughout most of the TGF-beta time course, and showed that this results in an increase of the secreted form of clusterin. By monitoring several hallmark features of EMT, we demonstrated that antibodies targeting secreted clusterin inhibit the TGF-beta-induced EMT of BRI-JM01 cells, as well as the invasive phenotype of several other breast and prostate tumor cell lines (4T1, NMuMG, MDA-MB231LM2 and PC3), without affecting the proliferation of these cells. These results indicate that secreted clusterin is a functionally important EMT mediator that lies downstream within TGF-beta's EMT-promoting transcriptional cascade, but not within its growth-inhibitory pathways. To further investigate the role played by secreted clusterin in tumor metastasis, we assessed the effect of several anti-clusterin monoclonal antibodies in vivo using a 4T1 syngeneic mouse breast cancer model and found that these antibodies significantly reduce lung metastasis. Taken together, our results reveal a role for secreted clusterin as an important extracellular promoter of EMT, and suggest that antibodies targeting clusterin may inhibit tumor metastasis without reducing the beneficial growth inhibitory effects of TGF-beta.

Clusterin: a forgotten player in Alzheimer's disease

Clusterin, also known as apolipoprotein J, is a versatile chaperone molecule which contains several amphipathic and coiled-coil alpha-helices, typical characteristics of small heat shock proteins. In addition, clusterin has three large intrinsic disordered regions, so-called molten globule domains, which can stabilize stressed protein structures. Twenty years ago, it was demonstrated that the expression of clusterin was clearly increased in Alzheimer's disease (AD). Later it was observed that clusterin can bind amyloid-beta peptides and prevent their fibrillization. Clusterin is also involved in the clearance of amyloid-beta peptides and fibrils by binding to megalin receptors and enhancing their endocytosis within glial cells. Clusterin is a complement inhibitor and can suppress complement activation observed in AD. Clusterin is also present in lipoprotein particles and regulates cholesterol and lipid metabolism of brain which is disturbed in AD. Clusterin is a stress-induced chaperone which is normally secreted but in conditions of cellular stress, it can be transported to cytoplasm where it can bind to Bax protein and inhibit neuronal apoptosis. Clusterin can also bind to Smad2/3 proteins and potentiate the neuroprotective TGFbeta signaling. An alternative splicing can produce a variant isoform of clusterin which can be translocated to nuclei where it induces apoptosis. The role of nuclear clusterin in AD needs to be elucidated. We will review here the extensive literature linking clusterin to AD and examine the recent progress in clusterin research with the respect to AD pathology. Though clusterin can be viewed as a multipotent guardian of brain, it is unable to prevent the progressive neuropathology in chronic AD.

A signaling network in phenylephrine-induced benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an age-related disease of unknown etiology characterized by prostatic enlargement and coinciding with distinctive alterations in tissue histomorphology. To identify the molecular mechanisms underlying the development of BPH, we conducted a DNA microarray study using a previously described animal model in which chronic alpha(1)-adrenergic stimulation by repeated administration of phenylephrine evokes histomorphological changes in the rat prostate that resemble human BPH. Bioinformatic tools were applied to microarray data obtained from prostate tissue to construct a network model of potentially relevant signal transduction pathways. Significant involvement of inflammatory pathways was demonstrable, including evidence for activation of a TGF-beta signaling cascade. The heterodimeric protein clusterin (apolipoprotein J) was also identified as a prominent node in the network. Responsiveness of TGF-beta signaling and clusterin gene and protein expression were confirmed independently of the microarray data, verifying some components of the model. This is the first attempt to develop a comprehensive molecular network for histological BPH induced by adrenergic activation. The study also implicated clusterin as a novel biochemical target for therapy.

Molecular profiling of CD3-CD4+ T cells from patients with the lymphocytic variant of hypereosinophilic syndrome reveals targeting of growth control pathways

The clonal CD3(-)CD4(+) T-cell population characterizing lymphocytic variant hypereosinophilic syndrome (L-HES) persists for years, with a subgroup of patients ultimately progressing to T lymphoma. The molecular changes associated with the premalignant clone and the emergence of malignant subclones are unknown, precluding the development of targeted therapy for this HES variant. In this study, we used whole genome arrays to examine gene expression in the CD3(-)CD4(+) T cells and found that 850 genes were differentially regulated during chronic disease compared with CD3(+)CD4(+) T cells from healthy donors. Changes in the expression of 349 genes were altered in association with the clinical progression from chronic L-HES to T lymphoma in 1 patient, with 87 of 349 genes representing further changes in genes whose expression was altered in all chronic disease patients (87 of 850). Array analysis after CD2/CD28-mediated activation revealed that the major gene expression changes observed in the CD3(-)CD4(+) T cells do not reflect activation induced alterations but rather pathways involved in T-cell homeostasis, including transforming growth factor-beta signaling, apoptosis, and T-cell maturation, signaling, and migration. Examination of microRNA expression in the CD3(-)CD4(+) T cells from patients with chronic disease identified 23 microRNAs that changed significantly, among which miR-125a further decreased in association with one patient's evolution to T lymphoma.

TGF-beta indirectly favors the development of human Th17 cells by inhibiting Th1 cells

Human Th17 clones and circulating Th17 cells showed lower susceptibility to the anti-proliferative effect of TGF-beta than Th1 and Th2 clones or circulating Th1-oriented T cells, respectively. Accordingly, human Th17 cells exhibited lower expression of clusterin, and higher Bcl-2 expression and reduced apoptosis in the presence of TGF-beta, in comparison with Th1 cells. Umbilical cord blood naïve CD161(+)CD4(+) T cells, which contain the precursors of human Th17 cells, differentiated into IL-17A-producing cells only in response to IL-1beta plus IL-23, even in serum-free cultures. TGF-beta had no effect on constitutive RORgamma t expression by umbilical cord blood CD161(+) T cells but it increased the relative proportions of CD161(+) T cells differentiating into Th17 cells in response to IL-1beta plus IL-23, whereas under the same conditions it inhibited both T-bet expression and Th1 development. These data suggest that TGF-beta is not critical for the differentiation of human Th17 cells, but indirectly favors their expansion because Th17 cells are poorly susceptible to its suppressive effects.

Use of ProteinChip technology for identifying biomarkers of parasitic diseases: the example of porcine cysticercosis (Taenia solium)

Taenia solium cysticercosis is a significant public health problem in endemic countries. The current serodiagnostic techniques are not able to differentiate between infections with viable cysts and infections with degenerated cysts. The objectives of this study were to identify specific novel biomarkers of these different disease stages in the serum of experimentally infected pigs using ProteinChip technology (Bio-Rad) and to validate these biomarkers by analyzing serum samples from naturally infected pigs. In the experimental sample set 30 discriminating biomarkers (p<0.05) were found, 13 specific for the viable phenotype, 9 specific for the degenerated phenotype and 8 specific for the infected phenotype (either viable or degenerated cysts). Only 3 of these biomarkers were also significant in the field samples; however, the peak profiles were not consistent among the two sample sets. Five biomarkers discovered in the sera from experimentally infected pigs were identified as clusterin, lecithin-cholesterol acyltransferase, vitronectin, haptoglobin and apolipoprotein A-I.

Clusterin increases post-ischemic damages in organotypic hippocampal slice cultures

Clusterin or apolipoprotein J is a heterodimeric glycoprotein which is known to be increased during tissue involution in response to hormonal changes or injury and under circumstances leading to apoptosis. Previous studies in wild-type (WT) and clusterin-null (Clu-/-) mice indicated a protective role of clusterin over-expression in astrocytes lasting up to 90 days post-ischemia. However, in in vitro and in vivo models of neonatal hypoxia-ischemia, clusterin exacerbates necrotic cell death. We developed recombinant forms of clusterin and examined their effect on propidium iodide uptake, neuronal and synaptic markers as well as electrophysiological recordings in hippocampal slice cultures from Clu-/- and WT mice subjected to oxygen-glucose deprivation (OGD). WT mice displayed a marked up-regulation of clusterin associated with electrophysiological deficits and dramatic increase of propidium iodide uptake 5 days post-OGD. Immunocytochemical and western blot analyses revealed a substantial decrease of neuronal nuclei and synaptophysin immunoreactivity that predominated in WT mice. These findings contrasted with the relative post-OGD resistance of Clu-/- mice. The addition of biologically active recombinant forms of human clusterin for 24 h post-OGD led to the abolishment of the ischemic tolerance in Clu-/- slices. This deleterious effect of clusterin was reverted by the concomitant administration of the NMDA receptor antagonist, d-2-amino-5-phosphonopentanoate. The present data indicate that in an in vitro model of ischemia characterized by the predominance of NMDA-mediated cell death, clusterin exerts a negative effect on the structural integrity and functionality of hippocampal neurons.

Clusterin expression during fetal and postnatal CNS development in mouse

Clusterin (or apolipoprotein J) is a widely distributed multifunctional glycoprotein involved in CNS plasticity and post-traumatic remodeling. Using biochemical and morphological approaches, we investigated the clusterin ontogeny in the CNS of wild-type (WT) mice and explored developmental consequences of clusterin gene knock-out in clusterin null (Clu-/-) mice. A punctiform expression of clusterin mRNA was detected through the hypothalamic region, neocortex and hippocampus at embryonic stages E14/E15. From embryonic stage E16 to the first week of the postnatal life, the vast majority of CNS neurons expressed low levels of clusterin mRNA. In contrast, a very strong hybridizing signal mainly localized in pontobulbar and spinal cord motor nuclei was observed from the end of the first postnatal week to adulthood. Astrocytes expressing clusterin mRNA were often detected through the hippocampus and neocortex in neonatal mice. Real-time polymerase chain amplification and clusterin-immunoreactivity dot-blot analyses indicated that clusterin levels paralleled mRNA expression. Comparative analyses between WT and Clu-/- mice during postnatal development showed no significant differences in brain weight, neuronal, synaptic and astrocyte markers as well myelin basic protein expression. However, quantitative estimation of large motor neuron populations in the facial nucleus revealed a significant deficit in motor cells (-16%) in Clu-/- compared with WT mice. Our data suggest that clusterin expression is already present in fetal life mainly in subcortical structures. Although the lack of this protein does not significantly alter basic aspects of the CNS development, it may have a negative impact on neuronal development in certain motor nuclei.

Expression of transforming growth factor β1 and its type I receptor in gastric cancer

AIM: To evaluate the significance of transforming growth factor-β1 (TGF-β1) and its β I type receptor (TGF-β R1) in the pathogenesis of gastric carcinoma.

METHODS: TGF-β1 and TGF-β R1 were detected by immunohistochemistry in and real-time PCR (RT-PCR) 50 cases of gastric carcinoma, 19 cases of atrophic gastritis and 18 cases of normal gastric mucosa.

RESULTS: Immunohistochemistry demonstrated that the positive expression rates of TGF-β1 and TGF-β R1 were significantly higher in gastric carcinoma (80.0% and 75.0%) than in normal gastric mucosa (33.3% and 27.8%) and atrophic gastritis (36.8% and 36.8%) (P < 0.01). The lower the differentiation of gastric carcinoma was, the higher the expression of TGF-β1 and TGF-β R1 was (r = 35.58, P < 0.01). Furthermore, the expression of TGF-β1 and TGF-β R1 mRNA was significantly higher in gastric carcinoma than in normal gastric mucosa and atrophic gastritis (TGF-β1: 4.20 ± 0.51 vs 9.15 ± 2.12, 8.22 ± 1.81; TGF-β R1: 1.28 ± 0.48 vs 5.55 ± 1.48, 4.19 ± 0.95).

CONCLUSION: High expression of TGF-β1 and TGF-β R1 is correlated with the development, biologic behavior and prognosis of gastric carcinoma.