Clusterin overexpression in both malignant and nonmalignant prostate epithelial cells induces cell cycle arrest and apoptosis

Clusterin: a double-edged sword in cancer and neurological disorders

Clusterin is a ubiquitously expressed glycoprotein that is involved in a whole range of biological processes. This protein is known to promote tumor survival and resistance to therapy in cancer, which contrasts sharply with its neuroprotective functions in various neurological diseases. This duality has led to recent investigations into the potential therapeutic applications of clusterin inhibition, particularly in cancer treatment. Inhibition of clusterin has been shown to be able to induce cancer cell senescence, suppress their growth and increase their sensitivity to therapy. The involvement of clusterin in the aging process makes its biological effects even more complex and offers a broad perspective for research and therapeutic exploration of various pathological conditions. This review critically examines the multiple functions of clusterin in cancer and neurological disorders and addresses the controversies surrounding its role in these areas. The assessment includes an in-depth analysis of the existing literature and examining the relationship of clusterin to fundamental aspects of cancer progression, including cell proliferation, apoptosis, metastasis, and drug resistance. In addition, the review addresses the neurobiological implications of clusterin and examines its controversial role in neuroprotection, neurodegeneration, and synaptic plasticity. Attention is also paid to the epigenetic regulation of clusterin expression. By clarifying conflicting findings and discrepancies in the literature, this review aims to provide a nuanced understanding of the molecular mechanisms underlying clusterin functions and its potential clinical implications in both cancer and neurodisorders. See also the graphical abstract(Fig. 1).

Therapeutic Potential of Clusterin Inhibition in Human Cancer

Clusterin (CLU) protein is involved in various pathophysiological processes including carcinogenesis and tumor progression. In recent years, the role of the secretory isoform has been demonstrated in tumor cells, where it inhibits apoptosis and favors the acquisition of resistance to conventional treatments used to treat cancer. To determine the possible therapeutic potential of inhibiting this protein, numerous studies have been carried out in this field. In this article, we present the existing knowledge to date on the inhibition of this protein in different types of cancer and analyze the importance it could have in the development of new therapies targeted against this disease.

Clusterin Expression in Colorectal Carcinomas

Colorectal cancer is the third most diagnosed cancer, behind only breast and lung cancer. In terms of overall mortality, it ranks second due to, among other factors, problems with screening programs, which means that one of the factors that directly impacts survival and treatment success is early detection of the disease. Clusterin (CLU) is a molecular chaperone that has been linked to tumorigenesis, cancer progression and resistance to anticancer treatments, which has made it a promising drug target. However, it is still necessary to continue this line of research and to adjust the situations in which its use is more favorable. The aim of this paper is to review the current genetic knowledge on the role of CLU in tumorigenesis and cancer progression in general, and discuss its possible use as a therapeutic target in colorectal cancer.

The Ins and Outs of Clusterin: Its Role in Cancer, Eye Diseases and Wound Healing

Clusterin (CLU) is a glycoprotein originally discovered in 1983 in ram testis fluid. Rapidly observed in other tissues, it was initially given various names based on its function in different tissues. In 1992, it was finally named CLU by consensus. Nearly omnipresent in human tissues, CLU is strongly expressed at fluid-tissue interfaces, including in the eye and in particular the cornea. Recent research has identified different forms of CLU, with the most prominent being a 75-80 kDa heterodimeric protein that is secreted. Another truncated version of CLU (55 kDa) is localized to the nucleus and exerts pro-apoptotic activities. CLU has been reported to be involved in various physiological processes such as sperm maturation, lipid transportation, complement inhibition and chaperone activity. CLU was also reported to exert important functions in tissue remodeling, cell-cell adhesion, cell-substratum interaction, cytoprotection, apoptotic cell death, cell proliferation and migration. Hence, this protein is sparking interest in tissue wound healing. Moreover, CLU gene expression is finely regulated by cytokines, growth factors and stress-inducing agents, leading to abnormally elevated levels of CLU in many states of cellular disturbance, including cancer and neurodegenerative conditions. In the eye, CLU expression has been reported as being severely increased in several pathologies, such as age-related macular degeneration and Fuch's corneal dystrophy, while it is depleted in others, such as pathologic keratinization. Nevertheless, the precise role of CLU in the development of ocular pathologies has yet to be deciphered. The question of whether CLU expression is influenced by these disorders or contributes to them remains open. In this article, we review the actual knowledge about CLU at both the protein and gene expression level in wound healing, and explore the possibility that CLU is a key factor in cancer and eye diseases. Understanding the expression and regulation of CLU could lead to the development of novel therapeutics for promoting wound healing.

Transcript-Targeted Therapy Based on RNA Interference and Antisense Oligonucleotides: Current Applications and Novel Molecular Targets

The development of novel target therapies based on the use of RNA interference (RNAi) and antisense oligonucleotides (ASOs) is growing in an exponential way, challenging the chance for the treatment of the genetic diseases and cancer by hitting selectively targeted RNA in a sequence-dependent manner. Multiple opportunities are taking shape, able to remove defective protein by silencing RNA (e.g., Inclisiran targets mRNA of protein PCSK9, permitting a longer half-life of LDL receptors in heterozygous familial hypercholesteremia), by arresting mRNA translation (i.e., Fomivirsen that binds to UL123-RNA and blocks the translation into IE2 protein in CMV-retinitis), or by reactivating modified functional protein (e.g., Eteplirsen able to restore a functional shorter dystrophin by skipping the exon 51 in Duchenne muscular dystrophy) or a not very functional protein. In this last case, the use of ASOs permits modifying the expression of specific proteins by modulating splicing of specific pre-RNAs (e.g., Nusinersen acts on the splicing of exon 7 in SMN2 mRNA normally not expressed; it is used for spinal muscular atrophy) or by downregulation of transcript levels (e.g., Inotersen acts on the transthryretin mRNA to reduce its expression; it is prescribed for the treatment of hereditary transthyretin amyloidosis) in order to restore the biochemical/physiological condition and ameliorate quality of life. In the era of precision medicine, recently, an experimental splice-modulating antisense oligonucleotide, Milasen, was designed and used to treat an 8-year-old girl affected by a rare, fatal, progressive form of neurodegenerative disease leading to death during adolescence. In this review, we summarize the main transcriptional therapeutic drugs approved to date for the treatment of genetic diseases by principal regulatory government agencies and recent clinical trials aimed at the treatment of cancer. Their mechanism of action, chemical structure, administration, and biomedical performance are predominantly discussed.

Study on plasma exosome biomarkers of pregnant women with intrahepatic cholestasis of pregnancy

OBJECTIVE AND AIMS

Serum total bile acid (TBA) level as the main index for the diagnosis of intrahepatic cholestasis of pregnancy (ICP) has some limitations. The early diagnosis and new treatment of ICP still need to be further strengthened.

MATERIALS AND METHODS

Plasma samples were collected, and exosomes were isolated. Key differential proteins were screened by bioinformatics methods. ELISA method was used to detect the concentration of the key differential protein in plasma samples, and the receiver operating characteristic curve (ROC) curve was drawn to find out the best critical value.

RESULTS

There were 138 differentially expressed proteins between the ICP and the normal groups by quantitative analysis. Cluster protein (CLU) was screened as a clinical validation index. The CLU concentration of plasma exosomes in the ICP group was significantly higher than that in the normal group (p < .0001). ROC curve analysis showed that the best critical point for diagnosing ICP according to the plasma exosomes CLU concentration of pregnant women was 255.28 ng/ml. In the ICP group, the best crucial point for predicting ICP with premature delivery is 286.72 ng/ml.

CONCLUSIONS

The plasma exosomes CLU in pregnant women with ICP is an important biomarker for clinical diagnosis and prediction of premature delivery of ICP.

A novel hemocompatible core@shell nanosystem for selective targeting and apoptosis induction in cancer cells

Synthesis, characterization and evaluation of transferrin-decorated mesoporous silica-coated silver nanoparticles as a novel hemocompatible core@shell nanosystem for selective targeting and apoptosis induction in cancer cells.

Clusterin as modulator of carcinogenesis: A potential avenue for targeted cancer therapy

Clusterin (CLU) is an evolutionary conserved molecular chaperone present in different human tissues and fluids and established to be a significant cancer regulator. It controls several cancer-associated cellular events, including cancer cell proliferation, stemness, survival, metastasis, epithelial-mesenchymal transition, therapy resistance, and inhibition of programmed cell death to support cancer growth and recurrence. This multifunctional role of CLU makes it an ideal target for cancer control. More importantly, genetic and antisense-mediated (OGX-011) inhibition of CLU enhances the anticancer potential of different FDA-approved chemotherapeutic drugs at the clinical level, improving patient's survival. In this review, we have discussed the detailed mechanism of CLU-mediated modulation of different cancer-associated signaling pathways. We have also provided updated information on the current preclinical and clinical findings that drive trials in various cancer types for potential targeted cancer therapy.

Diagnostic value of clusterin immunostaining in hepatocellular carcinoma

Background

Histologic distinction between well differentiated hepatocellular carcinoma (HCC) and benign hepatocellular mass lesions is a known challenge. Existing biomarkers are of limited diagnostic value. Our previous studies observed an enhanced canalicular expression pattern of clusterin (CLU) in HCC, which was not observed in benign hepatocellular mass lesions such as hepatocellular adenoma. The aim of this study was to further investigate its diagnostic value for HCC by examining the expression pattern of CLU in a large number of non-hepatocellular tumors, and by comparing it with two other commonly used hepatocellular markers pCEA and CD10 that also show a canalicular staining pattern in HCC.

Methods

Enhanced canalicular staining patterns of CLU, pCEA and CD10 were analyzed on 54 surgically resected well to moderately differentiated HCCs on whole tissue sections, of which 37 had surrounding regenerative nodules while the remaining 17 had a non-cirrhotic background. CLU immunostaining was also performed on tissue microarray sections that contained 74 HCCs (40 of which were also stained for pCEA and CD10), 55 normal liver tissue samples, and 1305 non-hepatocellular tumors from multiple organs.

Results

Enhanced CLU canalicular staining was observed in 70% (89/128) HCCs but not in regenerative nodules, normal liver tissues or any non-hepatocellular tumors. The sensitivity and specificity for enhanced canalicular staining pattern of CLU in HCCs were 0.70 and 1.00. This enhanced canalicular pattern was observed in only 26 and 23% HCCs for CD10 and pCEA, respectively. These results further demonstrate that the distinctive enhanced canalicular pattern of CLU is unique to HCC.

Conclusions

CLU is superior to pCEA and CD10 as a diagnostic immunomarker in that it can help distinguish well to moderately differentiated HCC not only from non-HCC malignancies but also from benign hepatocellular mass lesions.

'Omics driven discoveries of gene targets for apoptosis attenuation in CHO cells

Chinese hamster ovary (CHO) cells are widely used in biopharmaceutical production. Improvements to cell lines and bioprocesses are constantly being explored. One of the major limitations of CHO cell culture is that the cells undergo apoptosis, leading to rapid cell death, which impedes reaching high recombinant protein titres. While several genetic engineering strategies have been successfully employed to reduce apoptosis, there is still room to further enhance CHO cell lines performance. 'Omics analysis is a powerful tool to better understand different phenotypes and for the identification of gene targets for engineering. Here, we present a comprehensive review of previous CHO 'omics studies that revealed changes in the expression of apoptosis-related genes. We highlight targets for genetic engineering that have reduced, or have the potential to reduce, apoptosis or to increase cell proliferation in CHO cells, with the final aim of increasing productivity.

Clusterin Silencing in Prostate Cancer Induces Matrix Metalloproteinases by an NF-κB-Dependent Mechanism

Clusterin (CLU) is a stress-activated glycoprotein, whose expression is altered both in inflammation and cancer. Previously, we showed that abrogation of CLU expression in cancer-prone mice (TRAMP) results in the enhancement of tumor spreading and homing, concomitant with an enhanced expression of NF-κB. In the present paper, we carried out an extensive experimental work by utilizing microarray gene expression data, as well as in vitro and in vivo models of prostate cancer (PCa). Our results demonstrated that (i) CLU expression is significantly downregulated in human PCa and inversely correlates with the expression of p65 in metastases; (ii) CLU overexpression in PCa cells reduces the Ser₅₃₆ phosphorylation of p65, inhibits NF-κB nuclear translocation, and reduces the transcription of matrix metalloproteinase-9 and metalloproteinase-2 (MMP-9 and MMP-2). Conversely, CLU silencing promotes NF-κB activation and transcriptional upregulation of MMP-9; and (iii) expression and activity of MMP-2 and MMP-9 are increased in CLU^−/− mice (CLUKO) and in TRAMP/CLUKO mice in comparison to their relative Clu^+/+ littermates. Taken together, our data support the hypothesis that CLU downregulation, an early and relevant event in PCa onset, may inhibit NF-κB activation and limit the execution of a transcriptional program that favor the disease progression towards a metastatic stage.

Clusterin enhances AKT2-mediated motility of normal and cancer prostate cells through a PTEN and PHLPP1 circuit

Clusterin (CLU) is a chaperone-like protein with multiple functions. sCLU is frequently upregulated in prostate tumor cells after chemo- or radiotherapy and after surgical or pharmacological castration. Moreover, CLU has been documented to modulate the cellular homolog of murine thymoma virus akt8 oncogene (AKT) activity. Here, we investigated how CLU overexpression influences phosphatidylinositol 3'-kinase (PI3K)/AKT signaling in human normal and cancer epithelial prostate cells. Human prostate cells stably transfected with CLU were broadly profiled by reverse phase protein array (RPPA), with particular emphasis on the PI3K/AKT pathway. The effect of CLU overexpression on normal and cancer cell motility was also tested. Our results clearly indicate that CLU overexpression enhances phosphorylation of AKT restricted to isoform 2. Mechanistically, this can be explained by the finding that the phosphatase PH domain leucine-rich repeat-containing protein phosphatase 1 (PHLPP1), known to dephosphorylate AKT2 at S474, is markedly downregulated by CLU, whereas miR-190, a negative regulator of PHLPP1, is upregulated. Moreover, we found that phosphatase and tensin homolog (PTEN) was heavily phosphorylated at the inhibitory site S380, contributing to the hyperactivation of AKT signaling. By keeping AKT2 phosphorylation high, CLU dramatically enhances the migratory behavior of prostate epithelial cell lines with different migratory and invasive phenotypes, namely prostate normal epithelial 1A (PNT1A) and prostatic carcinoma 3 (PC3) cells. Altogether, our results unravel for the first time a circuit by which CLU can switch a low migration phenotype toward a high migration phenotype, through miR-190-dependent downmodulation of PHLPP1 expression and, in turn, stabilization of AKT2 phosphorylation.

Clusterin in Alzheimer's Disease: Mechanisms, Genetics, and Lessons From Other Pathologies

Clusterin (CLU) or APOJ is a multifunctional glycoprotein that has been implicated in several physiological and pathological states, including Alzheimer's disease (AD). With a prominent extracellular chaperone function, additional roles have been discussed for clusterin, including lipid transport and immune modulation, and it is involved in pathways common to several diseases such as cell death and survival, oxidative stress, and proteotoxic stress. Although clusterin is normally a secreted protein, it has also been found intracellularly under certain stress conditions. Multiple hypotheses have been proposed regarding the origin of intracellular clusterin, including specific biogenic processes leading to alternative transcripts and protein isoforms, but these lines of research are incomplete and contradictory. Current consensus is that intracellular clusterin is most likely to have exited the secretory pathway at some point or to have re-entered the cell after secretion. Clusterin's relationship with amyloid beta (Aβ) has been of great interest to the AD field, including clusterin's apparent role in altering Aβ aggregation and/or clearance. Additionally, clusterin has been more recently identified as a mediator of Aβ toxicity, as evidenced by the neuroprotective effect of CLU knockdown and knockout in rodent and human iPSC-derived neurons. CLU is also the third most significant genetic risk factor for late onset AD and several variants have been identified in CLU. Although the exact contribution of these variants to altered AD risk is unclear, some have been linked to altered CLU expression at both mRNA and protein levels, altered cognitive and memory function, and altered brain structure. The apparent complexity of clusterin's biogenesis, the lack of clarity over the origin of the intracellular clusterin species, and the number of pathophysiological functions attributed to clusterin have all contributed to the challenge of understanding the role of clusterin in AD pathophysiology. Here, we highlight clusterin's relevance to AD by discussing the evidence linking clusterin to AD, as well as drawing parallels on how the role of clusterin in other diseases and pathways may help us understand its biological function(s) in association with AD.

Clusterin, a Novel DEC1 Target, Modulates DNA Damage-Mediated Cell Death

Differentiated embryonic chondrocyte expressed gene 1 (DEC1, also known as Sharp2/Stra13/BHLHE40) is a basic helix-loop-helix transcription factor that plays an important role in circadian rhythms, cell proliferation, apoptosis, cellular senescence, hypoxia response, and epithelial-to-mesenchymal transition of tumor cells. Secretory clusterin (sCLU) is a cytoprotective protein that guards against genotoxic stresses. Here, clusterin (CLU) was identified as a novel target gene of DEC1 and suppresses DNA damage-induced cell death in tumor cells. Mechanistically, based on chromatin immunoprecipitation and luciferase assays, DEC1 binds to and activates the promoter of the CLU gene. DEC1 and DNA-damaging agents induce sCLU expression, whereas DEC1 knockdown decreases the expression of sCLU upon DNA damage. Moreover, the data demonstrate that DEC1 inhibits, whereas sCLU knockdown enhances, DNA damage-induced cell death in MCF7 breast cancer cells. Given that DEC1 and sCLU are frequently overexpressed in breast cancers, these data provide mechanistic insight into DEC1 as a prosurvival factor by upregulating sCLU to reduce the DNA damage-induced apoptotic response. Together, this study reveals sCLU as a novel target of DEC1 which modulates the sensitivity of the DNA damage response.Implications: DEC1 and sCLU are frequently overexpressed in breast cancer, and targeting the sCLU-mediated cytoprotective signaling pathway may be a novel therapeutic approach. Mol Cancer Res; 16(11); 1641-51. ©2018 AACR.

Proteotranscriptomic Measurements of E6-Associated Protein (E6AP) Targets in DU145 Prostate Cancer Cells

Prostate cancer is a common cause of cancer-related death in men. E6AP (E6-Associated Protein), an E3 ubiquitin ligase and a transcription cofactor, is elevated in a subset of prostate cancer patients. Genetic manipulations of E6AP in prostate cancer cells expose a role of E6AP in promoting growth and survival of prostate cancer cells in vitro and in vivo However, the effect of E6AP on prostate cancer cells is broad and it cannot be explained fully by previously identified tumor suppressor targets of E6AP, promyelocytic leukemia protein and p27. To explore additional players that are regulated downstream of E6AP, we combined a transcriptomic and proteomic approach. We identified and quantified 16,130 transcripts and 7,209 proteins in castration resistant prostate cancer cell line, DU145. A total of 2,763 transcripts and 308 proteins were significantly altered on knockdown of E6AP. Pathway analyses supported the known phenotypic effects of E6AP knockdown in prostate cancer cells and in parallel exposed novel potential links of E6AP with cancer metabolism, DNA damage repair and immune response. Changes in expression of the top candidates were confirmed using real-time polymerase chain reaction. Of these, clusterin, a stress-induced chaperone protein, commonly deregulated in prostate cancer, was pursued further. Knockdown of E6AP resulted in increased clusterin transcript and protein levels in vitro and in vivo Concomitant knockdown of E6AP and clusterin supported the contribution of clusterin to the phenotype induced by E6AP. Overall, results from this study provide insight into the potential biological pathways controlled by E6AP in prostate cancer cells and identifies clusterin as a novel target of E6AP.

Clusterin inhibition mediates sensitivity to chemotherapy and radiotherapy in human cancer

Since its discovery in 1983, the protein clusterin (CLU) has been isolated from almost all human tissues and fluids and linked to the development of different physiopathological processes, including carcinogenesis and tumor progression. During the last few years, several studies have shown the cytoprotective role of secretory CLU in tumor cells, inhibiting their apoptosis and enhancing their resistance to conventional treatments including hormone depletion, chemotherapy, and radiotherapy. In an effort to determine the therapeutic potential that the inhibition of this protein could have on the development of new strategies for cancer treatment, numerous studies have been carried out in this field, with results, in most cases, satisfactory but sometimes contradictory. In this document, we summarize for the first time the current knowledge of the effects that CLU inhibition has on sensitizing tumor cells to conventional cancer treatments and discuss its importance in the development of new strategies against cancer.

The CLU-files: disentanglement of a mystery

The multifaceted protein clusterin (CLU) has been challenging researchers for more than 35 years. The characterization of CLU as a molecular chaperone was one of the major breakthroughs in CLU research. Today, secretory clusterin (sCLU), also known as apolipoprotein J (apoJ), is considered one of the most important extracellular chaperones ever found. It is involved in a broad range of physiological and pathophysiological functions, where it exerts a cytoprotective role. Descriptions of various forms of intracellular CLU have led to further and even contradictory functions. To untangle the current state of knowledge of CLU, this review will combine old views in the field, with new discoveries to highlight the nature and function of this fascinating protein(s). In this review, we further describe the expression and subcellular location of various CLU forms. Moreover, we discuss recent insights into the structure of CLU and assess how structural properties as well as the redox environment determine the chaperone activity of CLU. Eventually, the review connects the biochemistry and molecular cell biology of CLU with medical aspects, to formulate a hypothesis of a CLU function in health and disease.

Inflammation in Alzheimer's Disease and Molecular Genetics: Recent Update

Alzheimer's disease (AD) is a complex age-related neurodegenerative disorder of the central nervous system. Since the first description of AD in 1907, many hypotheses have been established to explain its causes. The inflammation theory is one of them. Pathological and biochemical studies of brains from AD individuals have provided solid evidence of the activation of inflammatory pathways. Furthermore, people with long-term medication of anti-inflammatory drugs have shown a reduced risk to develop the disease. After three decades of genetic study in AD, dozens of loci harboring genetic variants influencing inflammatory pathways in AD patients has been identified through genome-wide association studies (GWAS). The most well-known GWAS risk factor that is responsible for immune response and inflammation in AD development should be APOE ε4 allele. However, a growing number of other GWAS risk AD candidate genes in inflammation have recently been discovered. In the present study, we try to review the inflammation in AD and immunity-associated GWAS risk genes like HLA-DRB5/DRB1, INPP5D, MEF2C, CR1, CLU and TREM2.

Clusterin transcript variants expression in thyroid tumor: a potential marker of malignancy?

BACKGROUND

Clusterin (CLU) is a ubiquitous multifunctional factor involved in neoplastic transformation. The CLU transcript variants and protein forms play a crucial role in balancing cells proliferation and death.

METHODS

We investigated the regulation of CLU transcript variants expression in an in vivo model system consisting of both neoplastic tissues and fine needle aspiration biopsy (FNAB) samples isolated from patients undergoing thyroidectomy.

RESULTS

The immunohistochemical analyses showed an overall CLU up-regulation in papillary carcinoma. A specific CLU2 transcript variant increase was registered using qPCR in papillary carcinomas while CLU1 decreased. In addition, the analysis of CLU transcripts expression level showed an increase of the CLU2 transcript in the TIR 3 patients with histologically confirmed thyroid cancer.

CONCLUSIONS

Our results suggest the existence of a specific alteration of CLU2:CLU1 ratio towards CLU2, thus providing the first circumstantial evidence for the potential use of CLU transcript variants as effective biomarkers for a more accurate assessment of the so called "indeterminate" thyroid nodules.

Potential nanotechnologies and molecular targets in the quest for efficient chemotherapy in ovarian cancer

INTRODUCTION

Ovarian cancer, considered one of the most fatal gynecological cancers, goes largely undiagnosed until metastasis presents itself, usually once the patient is in the final stages and thus, too late for worthwhile therapy. Targeting this elusive disease in its early stages would improve the outcome for most patients, while the information generated thereof would increase the possibility of preventative mechanisms of therapy.

AREAS COVERED

This review discusses various molecular targets as possible moieties to be incorporated in a holistic drug delivery system or the more aptly termed 'theranostic' system. These molecular targets can be used for targeting, visualizing, diagnosing, and ultimately, treating ovarian cancer in its entirety. Currently implemented nanoframeworks, such as nanomicelles and nanoliposomes, are described and the effectiveness of nanostructures in tumor targeting, treatment functions, and overcoming the drug resistance challenge is discussed.

EXPERT OPINION

Novel nanotechnology strategies such as the development of nanoframeworks decorated with targeted ligands of a molecular nature may provide an efficient chemotherapy, especially when instituted in combination with imaging, diagnostic, and ultimately, therapeutic moieties. An imperative aspect of utilizing nanotechnology in the treatment of ovarian cancer is the flexibility of the drug delivery system and its ability to overcome standard obstacles such as: i) successfully treating the desired cells through direct targeting; ii) reducing toxicity levels of treatment by achieving direct targeting; and iii) delivery of targeted therapy using an efficient vehicle that is exceptionally degradable in response to a particular stimulus. The targeting of ovarian cancer in its early stages using imaging and diagnostic nanotechnology is an area that can be improved upon by combining therapeutic moieties with molecular biomarkers. The nanotechnology and molecular markers mentioned in this review have generally been used for either imaging or diagnostics, and have not yet been successfully implemented into bi-functional tools, which it is hoped, should eventually include a therapeutic aspect.

Clusterin is a gene-specific target of microRNA-21 in head and neck squamous cell carcinoma

PURPOSE

MicroRNA-21 (miRNA-21) has proto-oncogenic properties, although no miRNA-21-specific targets have been found in head and neck squamous cell carcinoma (HNSCC). Further study of miRNA-21 and its specific targets is essential to understanding HNSCC biology.

EXPERIMENTAL DESIGN

miRNA expression profiles of 10 HNSCCs and 10 normal mucosa samples were investigated using a custom miRNA microarray. Thirteen HNSCCs and five normal mucosa primary tissue specimens underwent mRNA expression microarray analysis. To identify miRNA-21 downstream targets, oral keratinocyte cells were subjected to microarray analysis after miRNA-21 transient transfection. miRNA and mRNA expression were validated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) in a separate cohort of 16 HNSCCs and 15 normal mucosal samples. Microarray and bioinformatics analyses were integrated to identify potential gene targets. In vitro assays looked at the function and interaction of miRNA-21 and its specific gene targets.

RESULTS

miRNA-21 was upregulated in HNSCCs and stimulated cell growth. Integrated analyses identified Clusterin (CLU) as a potential miRNA-21 gene target. CLU was downregulated after forced expression of miRNA-21 in normal and HNSCC cell lines. The activity of a luciferase construct containing the 3'-untranslated region (UTR) of CLU was repressed by the ectopic expression of miRNA-21. CLU was also downregulated in primary HNSCCs and correlated with miRNA-21 overexpression. CLU variant 1 (CLU-1) was the predominant splice variant in HNSCCs and showed growth suppression function that was reversed by miRNA-21 overexpression.

CONCLUSIONS

CLU is a specific, functional target of oncogenic miRNA-21 in HNSCCs. CLU-1 isoform is the predominant growth-suppressive variant targeted by miRNA-21.

Clusterin plays an important role in clear renal cell cancer metastasis

OBJECTIVE

Clusterin (CLU) is implicated in regulating clear renal cell carcinoma (CRCC) progression and metastasis, yet the mechanisms are not elucidated. In the present study, we explored the potential role of CLU in CRCC metastasis.

METHODS

Levels of CLU mRNA and CLU protein were measured by RT-PCR and immunohistochemistry analysis in 22 CRCC with metastasis and 22 without metastasis and 22 samples of normal kidney tissue. After CLU silencing and re-expression, the migration and invasion in vitro and in vivo of Caki-2 cells were determined by wound healing assay, transwell migration assay and pulmonary nodule assay, respectively. The expression of pERK1/2 and MMP-9 were detected by RT-PCR and Western blot assay.

RESULTS

We found a significant increase of CLU and CLU mRNA expression in CRCC, and the expression of CLU is strongly correlated in patients with metastatic disease. We discovered that CLU-rich Caki-2 cells displayed higher invasive ability which prompted us to investigate if CLU silencing could reduce the migration and invasion in Caki-2 cells. Compared with the vector-transfected cells, CLU knocked-down (CLUi) cells showed reduced migration and invasion in vitro, as well as decreased metastatic potential in experimental metastasis. Re-expression of CLU in CLUi cells restored the invasive phenotypes. We found that MMP-9 was downregulated in CLUi cells. We also discovered that levels of activated ERK1/2 correlated with the rich expression of CLU and MMP-9.

CONCLUSION

Our data suggest that CLU may regulate aggressive behavior of human CRCC cells through modulating ERK1/2 signaling and MMP-9 expression.

Establishment of adult mouse Sertoli cell lines by using the starvation method

Sertoli cells were isolated from the testes of 6-week-old mice and stable Sertoli cell lines with higher proliferation rates were subcloned after starvation of primary cultured cells. After two rounds of this subcloning, 33 subcloned lines were selected on the basis of their proliferation rates. In addition, these subclones were screened according to their phagocytic activity and the characteristics of mature Sertoli cells, such as the expression of androgen receptors (ARs) and progesterone receptors, by using western blotting and immunocytochemical analysis, in addition to their morphology and proliferation rates. After the third round of subcloning, 12 subclones were selected for the final selection using RT-PCR for identification of genes specifically expressed by various testicular cells. Three clones were selected that expressed Sertoli-cell-specific genes, i.e. stem cell factor, clusterin, AR, α-inhibin, transferrin, Wilms' tumour-1, Müllerian inhibitory substance, sex-determining region Y-box 9, FSH receptor (Fshr) and occludin; however, these clones did not express globulin transcription factor 1, steroidogenic factor or androgen-binding protein. These clones also expressed growth and differentiation factors that act on germ cells, such as leukaemia inhibitory factor, transforming growth factor β1 and basic fibroblast growth factor 2, but did not express c-kit (specific for germ cells), LH receptor and 3β-hydroxyl-dehydrogenase (specific for Leydig cells). Immunocytochemical data confirmed the expression of clusterin in these clones. Furthermore, the Bromodeoxyuridine incorporation assay confirmed the proliferation activity of these clones throughFshrafter treatment with FSH. These clones are considered to be valuable tools for the study of Sertoli cell-specific gene expression and function.

Regulation of the expression of CLU isoforms in endometrial proliferative diseases

Clusterin (CLU) is a nearly ubiquitous multifunctional protein synthesized in different functionally divergent isoforms, sCLU and nCLU, playing a crucial role by keeping a balance between cell proliferation and death. Studying in vivo CLU expression we found a higher mRNA expression both in neoplastic and hyperplastic tissues in comparison to normal endometria; in particular, by RT-qPCR we demonstrated an increase of the specific sCLU isoform in the neoplastic and hyperplastic endometrial diseases. On the contrary, no CLU increase was detected at the protein level. The CLU gene transcriptional activity was upregulated in the hyperplastic and neoplastic tissues, indicating the existence of a fine post-trans-criptional regulation of CLU expression possibly responsible for the protein decrease in the malignant disease. A specific CLU immunoreactivity was present in all the endometrial glandular cells in comparison to the other cellular compartments where CLU immunoreactivity was lower or absent. In conclusion, our results suggest the existence of a complex regulatory mechanism of CLU gene expression during the progression from normal to malignant cells, possibly contributing to endometrial carcinogenesis. Moreover, the specific alteration of the sCLU:nCLU ratio associated with the pathological stage, suggests a possible usage of CLU as molecular biomarker for the diagnosis/prognosis of endometrial proliferative diseases.

Stable knockdown of clusterin by vectorbased RNA interference in a human breast cancer cell line inhibits tumour cell invasion and metastasis

OBJECTIVE

Overexpression of the clusterin (CLU) gene occurs in breast cancer and is associated with lymph node metastasis. The present study explored the effect of CLU silencing on invasion and metastasis, and the relationship between CLU expression and the extracellular signal-regulated kinase (ERK) / matrix metalloproteinase-9 (MMP) signalling pathway in human breast cancer cells.

METHODS

A pcDNA3.1-based RNA interference approach was used to knockdown the CLU gene in MDA-231 cells (MDA-231-CLUi); control MDA-231 cells were transfected with an empty vector (MDA-231-Vec). Reverse transcription-polymerase chain reaction was used to assess CLU and MMP-9 mRNA levels, and Western blotting was used to analyse CLU, MMP-9 and ERK protein levels. Metastatic potential was evaluated using in vitro and in vivo models of invasion and metastasis.

RESULTS

Compared with MDA-231-Vec cells, the MDA-231-CLUi cells demonstrated reduced migration and invasion in vitro and decreased metastatic potential in vivo. Reintroduction and reexpression of the CLU gene into the MDA-231-CLUi cells restored the invasive phenotype. MMP-9 mRNA and protein levels were reduced in MDA-231-CLUi cells, and there was a correlation between activated ERK and CLU and MMP-9 protein levels.

CONCLUSION

CLU may regulate the aggressive behaviour of human breast cancer cells through modulation of ERK signalling and MMP9 expression.

Changes of transthyretin and clusterin after androgen ablation therapy and correlation with prostate cancer malignancy

After androgen ablation therapy (AAT), advanced prostate cancer (Pca) eventually progresses to castration-resistant Pca (CRPC); however, the biomarkers that are used to predict its prognosis are limited. In this study, serum samples from four patients with advanced Pca were collected at the time of the initial diagnosis and 3 months after AAT. Proteomic changes were analyzed with two-dimensional differential in-gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Altogether, nine proteins were differentially expressed in the samples collected at diagnosis and in the samples collected after AAT. Among them, the expression of transthyretin (TTR) was 1.58-fold lower and clusterin (CLU) was 1.51-fold higher in the sera of post-AAT patients compared with those in the sera from pre-AAT patients. The significant changes in serum TTR and CLU in post-AAT patients were further confirmed by a large-scale ELISA. Immunohistochemistical staining revealed that the expression levels of TTR and CLU were significantly higher in Pca tissue than in normal and benign prostate hyperplasia tissue. The expression levels of TTR and CLU in Pca tissue were found to be associated with the grade and stage of Pca. Overall, this study indicated that TTR and CLU might be used to monitor the efficacy of AAT therapy and serve as biomarkers for the prognosis of Pca.

Regulation of chemosensitivity and migration by clusterin in non-small cell lung cancer cells

PURPOSE

In terms of drug resistance, cancer cells usually benefit from high clusterin (CLU) expression on chemotherapy. In contrast, CLU expression has been found to be a favorable prognostic factor in lung cancer patients. The aims of this study are to determine the association between CLU expression and chemotherapeutic sensitivity and the potential role of CLU in migration in human non-small-cell lung cancer (NSCLC) cell lines.

METHODS

The levels of clusterin in NSCLC cell lines were altered by short hairpin RNA interference (shRNAi) and overexpression on chemosensitivity assay. Migratory ability of these cell lines was also investigated.

RESULTS

H1355 cells with the highest level of CLU demonstrated the lowest sensitivities to Adriamycin (ADR), docetaxel (DOC), and gemcitabine (GEM) treatment. Inhibition of CLU expression in H1355 cells resulted in higher chemosensitivities. When CLU was stably overexpressed in A549 and H1299 cells, only the chemosensitivity to ADR was reduced. The migratory ability of CLU-overexpressing cells significantly decreased. Moreover, MMP2 transcription was inhibited in CLU-overexpressing H1299 cells. These results indicated lower metastatic potential for cancer cells with high CLU level.

CONCLUSION

Lung cancer cells with high level of CLU have reduced chemosensitivity. High level of CLU may result in migratory inhibition and thus favorable prognosis in lung cancer.

Liquid chromatography-tandem and MALDI imaging mass spectrometry analyses of RCL2/CS100-fixed, paraffin-embedded tissues: proteomics evaluation of an alternate fixative for biomarker discovery

Human tissues are an important source of biological material for the discovery of novel biomarkers. Fresh-frozen tissue could represent an ideal supply of archival material for molecular investigations. However, immediate flash freezing is usually not possible, especially for rare or valuable tissue samples such as biopsies. Here, we investigated the compatibility of RCL2/CS100, a non-cross-linking, nontoxic, and nonvolatile organic fixative, with shotgun proteomic analyses. Several protein extraction protocols compatible with mass spectrometry were investigated from RCL2/CS100-fixed and fresh-frozen colonic mucosa, breast, and prostate tissues. The peptides and proteins identified from RCL2/CS100 tissue were then comprehensively compared with those identified from matched fresh-frozen tissues using a bottom-up strategy based on nano-reversed phase liquid chromatography coupled with tandem mass spectrometry (nanoRPLC-MS/MS). Results showed that similar peptides could be identified in both archival conditions and the proteome coverage was not obviously compromised by the RCL2/CS100 fixation process. NanoRPLC-MS/MS of laser capture microdissected RCL2/CS100-fixed tissues gave the same amount of biological information as that recovered from whole RCL2/CS100-fixed or frozen tissues. We next performed MALDI tissue profiling and imaging mass spectrometry and observed a high level of agreement in protein expression as well as excellent agreement between the images obtained from RCL2/CS100-fixed and fresh-frozen tissue samples. These results suggest that RCL2/CS100-fixed tissues are suitable for shotgun proteomic analyses and tissue imaging. More importantly, this alternate fixative opens the door to the analysis of small, valuable, and rare target lesions that are usually inaccessible to complementary biomarker-driven genomic and proteomic research.

Chapter 5: Nuclear CLU (nCLU) and the fate of the cell

The possible biological role played by Clusterin (CLU) has been puzzling researchers for a long time since its first discovery and characterization. CLU has been often described as an "enigmatic" gene, a clear indication that too many aspects of this issue have been obscure or difficult to interpret for long. The good news is that this is certainly no longer true. Since the beginning, CLU was believed to play important roles in nearly all most important biological phenomena. The diversity, sometime the contradictions, of its biological action is now likely explained by the existence of different protein products all generated by the same single copy CLU gene. The relatively recent discovery that CLU can be retained inside the cell and targeted to many intracellular sites and organelles, including the nucleus, provided us a very different view from that solely deriving from its possible role in the outer cellular environment. In particular, nuclear localization of CLU (nCLU) was found to trigger cell death in many systems. In this chapter, a critical review of previous work will enable us to reinterpret old data and observations in the attempt to progressively unravelling the CLU "enigma" by considering its localization inside and outside the cell. The final picture would supposedly reconciliate different or alternative hypothesis. Starting with an "historical" approach demonstrating that nCLU was right under our eyes since the beginning, up to the more recent contributions we will describe which stimuli would inhibit secretion and maturation of CLU leading at least one protein product to target the nucleus and kill the cell. A better understanding of this complex issue is not an easy work, considering the thoughtfulness in reviewing the existing literature and the known controversial reports. We hope that the information contained in this article will be useful for the reader to enlighten this field.

The role of clusterin (CLU) in malignant transformation and drug resistance in breast carcinomas

Breast cancer is the main cause of cancer-related death among women in Western countries. Current research is focused on identifying antiapoptotic proteins which could be a possible target for novel chemotherapeutic drugs. Secretory clusterin (sCLU) is an extracellular chaperone that has been functionally implicated in DNA repair, cell-cycle regulation, apoptotic cell death and tumorigenesis. The implication of sCLU in carcinogenesis and the progression of breast carcinomas make it an interesting gene, worthy of investigation. It has been reported to present powerful antiapoptotic activity and to perform a prosurvival function with most therapeutic treatments for breast cancer. This review summarizes our current understanding of the role of CLU in tumorigenesis, progression, and response to treatment in breast carcinomas.

Regulation of CLU gene expression by oncogenes and epigenetic factors implications for tumorigenesis

In no other field has the function of clusterin (CLU) been more controversial than in cancer genetics. After more than 20 years of research, there is still uncertainty with regard to the role of CLU in human cancers. Some investigators believe CLU to be an oncogene, others-an inhibitor of tumorigenesis. However, owing to the recent efforts of several laboratories, the role of CLU in important cellular processes like proliferation, apoptosis, differentiation, and transformation is beginning to emerge. The "enigmatic" CLU is becoming less so. In this chapter, we will review the work of research teams interested in understanding how CLU is regulated by oncogenic signaling. We will discuss how and under what circumstances oncogenes and epigenetic factors modify CLU expression, with important consequences for mammalian tumorigenesis.

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.

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.

Vanadium-induced apoptosis of HaCaT cells is mediated by c-fos and involves nuclear accumulation of clusterin

Vanadium exerts a variety of biological effects, including antiproliferative responses through activation of the respective signaling pathways and the generation of reactive oxygen species. As epidermal cells are exposed to environmental insults, human keratinocytes (HaCaT) were used to investigate the mechanism of the antiproliferative effects of vanadyl(IV) sulfate (VOSO(4)). Treatment of HaCaT cells with VOSO(4) inhibited proliferation and induced apoptosis in a dose-dependent manner. Inhibition of proliferation was associated with downregulation of cyclins D1 and E, E2F1, and the cyclin-dependent kinase inhibitors p21(Cip1/Waf1) and p27(Kip1). Induction of apoptosis correlated with upregulation of the c-fos oncoprotein, changes in the expression of clusterin (CLU), an altered ratio of antiapoptotic to proapoptotic Bcl-2 protein family members, and poly(ADP-ribose) polymerase-1 cleavage. Forced overexpression of c-fos induced apoptosis in HaCaT cells that correlated with secretory CLU downregulation and upregulation of nuclear CLU (nCLU), a pro-death protein. Overexpression of Bcl-2 protected HaCaT cells from vanadium-induced apoptosis, whereas secretory CLU overexpression offered no cytoprotection. In contrast, nCLU sensitized HaCaT cells to apoptosis. Our data suggest that vanadium-mediated apoptosis was promoted by c-fos, leading to alterations in CLU isoform processing and induction of the pro-death nCLU protein.

A novel gene signature for molecular diagnosis of human prostate cancer by RT-qPCR

BACKGROUND

Prostate cancer (CaP) is one of the most relevant causes of cancer death in Western Countries. Although detection of CaP at early curable stage is highly desirable, actual screening methods present limitations and new molecular approaches are needed. Gene expression analysis increases our knowledge about the biology of CaP and may render novel molecular tools, but the identification of accurate biomarkers for reliable molecular diagnosis is a real challenge. We describe here the diagnostic power of a novel 8-genes signature: ornithine decarboxylase (ODC), ornithine decarboxylase antizyme (OAZ), adenosylmethionine decarboxylase (AdoMetDC), spermidine/spermine N(1)-acetyltransferase (SSAT), histone H3 (H3), growth arrest specific gene (GAS1), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and Clusterin (CLU) in tumour detection/classification of human CaP.

METHODOLOGY/PRINCIPAL FINDINGS

The 8-gene signature was detected by retrotranscription real-time quantitative PCR (RT-qPCR) in frozen prostate surgical specimens obtained from 41 patients diagnosed with CaP and recommended to undergo radical prostatectomy (RP). No therapy was given to patients at any time before RP. The bio-bank used for the study consisted of 66 specimens: 44 were benign-CaP paired from the same patient. Thirty-five were classified as benign and 31 as CaP after final pathological examination. Only molecular data were used for classification of specimens. The Nearest Neighbour (NN) classifier was used in order to discriminate CaP from benign tissue. Validation of final results was obtained with 10-fold cross-validation procedure. CaP versus benign specimens were discriminated with (80+/-5)% accuracy, (81+/-6)% sensitivity and (78+/-7)% specificity. The method also correctly classified 71% of patients with Gleason score<7 versus > or =7, an important predictor of final outcome.

CONCLUSIONS/SIGNIFICANCE

The method showed high sensitivity in a collection of specimens in which a significant portion of the total (13/31, equal to 42%) was considered CaP on the basis of having less than 15% of cancer cells. This result supports the notion of the "cancer field effect", in which transformed cells extend beyond morphologically evident tumour. The molecular diagnosis method here described is objective and less subjected to human error. Although further confirmations are needed, this method poses the potential to enhance conventional diagnosis.

Trichinella spiralis: nurse cell formation with emphasis on analogy to muscle cell repair

Trichinella infection results in formation of a capsule in infected muscles. The capsule is a residence of the parasite which is composed of the nurse cell and fibrous wall. The process of nurse cell formation is complex and includes infected muscle cell response (de-differentiation, cell cycle re-entry and arrest) and satellite cell responses (activation, proliferation and differentiation). Some events that occur during the nurse cell formation are analogous to those occurring during muscle cell regeneration/repair. This article reviews capsule formation with emphasis on this analogy.

Candidate genes responsible for common and different pathology of infected muscle tissues between Trichinella spiralis and T. pseudospiralis infection

The gene expression profiles were compared between Trichinella spiralis- and T. pseudospiralis-infected muscle tissues by means of a cDNA microarray. Out of 30,000 genes, the expressions of 55 genes were up-regulated in both T. spiralis and T. pseudospiralis infections, 24 genes were down-regulated in both Trichinella infections, 30 genes were up-regulated only in T. spiralis infection, 23 genes were down-regulated only in T. spiralis infection, 25 genes were up-regulated only in T. pseudospiralis infection, and 21 genes were down-regulated only in T. pseudospiralis infection. Many of these differentially expressed genes were associated with satellite cell activation and proliferation (paired box gene 7, Pax7; Pax3; desmin; M-cadherin), myogenesis and muscle development (eyes absent 2 homolog, Eya2; myocyte enhancer factor 2C, MEF2C; pre B-cell leukemia transcription factor 1, Pbx1; chordin-like 2, Chrdl2), cell differentiation (galectin 1; insulin like growth factors, IGFs; c-ski; msh-like 1, Msx1; Numb), cell proliferation and cycle regulation (retinoblastoma 1, Rb1; granulin; p21, CDK4, cyclin A2), and apoptosis (tumor necrosis factor receptor 1, TNF-R1; programmed cell death protein 11, Pdcd11; Pdcd1; nuclear protein 1, Nuprl; clusterin, CLU). The differential expression of 17 genes was validated by quantitative real time PCR and 15 genes showed identical results with the microarray analysis. The present study listed the candidate genes that were commonly and differentially expressed between T. spiralis and/or T. pseudospiralis infection, thus suggesting that these genes need to be further investigated to reveal the mechanism of the common and/or different pathological changes induced by the two species Trichinella.

Doxazosin-induced clusterin expression and apoptosis in prostate cancer cells

The purpose of this study was to correlate temporal expression of clusterin and apoptosis in androgen-independent human prostate cancer cells (PC-3) treated with 25 microM doxazosin. DNA fragmentation, reverse transcriptase polymerase chain reaction, and terminal transferase-mediated biotinylated 16-desoxy-uridene triphosphate nick-end labeling (TUNEL) assays were used to assess degree of apoptosis and temporal and spatial expression of clusterin mRNA and protein. DNA fragmentation was significant at 48 hours. Clusterin mRNA expression was 3-fold higher than control at 9 hours and was maintained over 48 hours. The TUNEL assay showed increasing percentage of apoptotic cells and presence of clusterin after doxazosin treatment. During doxazosin-induced apoptosis in PC3 cells, clusterin appeared to initially accumulate in the cytoplasm and protect against apoptosis; later, after its transport to the nucleus, clusterin was no longer able to suppress apoptosis.

NF-kappaB-dependent genes induced by proteinuria and identified using DNA microarrays

BACKGROUND

A close correlation has been shown between tubulointerstitial (TI) injury and the outcome of renal dysfunction, and nuclear factor-kappaB (NFkappaB) has been shown to play a key role in proteinuria-induced TI injury. To explore the molecular mechanisms of the proteinuria-induced TI injury further, we have analyzed renal gene expression with DNA microarrays, with and without specific inhibition of NF-kappaB in the proximal tubules.

METHODS

Unilaterally nephrectomized rats loaded with bovine serum albumin (BSA) were used as a model of proteinuric renal injury. Renal NF-kappaB activation was inhibited by gene transfer of the truncated form of IkappaBalpha (inhibitor of NF-kappaB) via the injection of a recombinant adenovirus vector into the renal artery, an method established in a previous study. Total RNA was extracted from the kidney and analyzed with a DNA microarrays containing 1081 genes.

RESULTS

Renal NF-kappaB activation and TI injury in BSA-loaded proteinuric rats were inhibited by the gene transfer of the truncated form of IkappaBalpha. DNA microarray analysis revealed 45 up-regulated genes and six down-regulated genes in the proteinuric rats, and expression of 23 of these 51 genes was significantly altered by NF-kappaB inhibition. Among these 23 genes, we focused on clusterin and confirmed the results of microarray analysis by Western blotting and PCR.

CONCLUSION

In this study, 23 genes of 51 proteinuria-related genes were regulated by NF-kappaB activation, suggesting that some of these genes may serve as target molecules for the treatment of progressive TI injury.

Cytoplasmic clusterin expression is associated with longer survival in patients with resected non small cell lung cancer

BACKGROUND

Clusterin is a glycoprotein that has been implicated in many processes, including apoptosis, cell cycle regulation, and DNA repair. Previous studies have examined the prognostic value of clusterin expression in various malignancies. In the present study, we examined clusterin staining in tumors resected from patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Tumor specimens were obtained for 113 patients with completely resected NSCLC from paraffin-embedded tissue microarrays and stained with an antibody specific for clusterin. Staining patterns were observed and graded based on intensity and then correlated with clinical data.

RESULTS

Positive cytoplasmic clusterin staining was observed in 44 patients, and weak/negative staining was observed in 62 patients. Patients who had tumors that stained positive for cytoplasmic clusterin had significantly longer survival in multivariate analysis (hazard ratio 0.487, 95% confidence interval 0.27-0.89). A correlation was also observed for recurrence-free survival, which approached statistical significance (hazard ratio 0.345, 95% confidence interval 0.12-1.02). In univariate analysis, patients with clusterin-positive tumors had a 63% 3-year survival, whereas patients with clusterin-negative tumors had a 42% 3-year survival (P = 0.0108); clusterin-positive tumors also had significantly less recurrence (P = 0.0231).

CONCLUSIONS

Cytoplasmic clusterin staining is present in a substantial number of NSCLC tumors and may be a biomarker for longer survival in patients with surgically resected NSCLC.

Inhibition of NF-kappaB-dependent Bcl-xL expression by clusterin promotes albumin-induced tubular cell apoptosis

Apoptosis and inflammation, important contributors to the progression of chronic kidney disease, can be influenced by clusterin (a secreted glycoprotein that regulates apoptosis) and nuclear factor-kappaB (NF-kappaB, a transcription factor modifying the expression of inflammatory genes). We studied proteinuria-induced renal disease and its influence on clusterin-mediated apoptosis. Exposure of cultured mouse proximal tubule epithelial cells to bovine serum albumin (BSA) resulted in activation of NF-kappaB and activator protein-1 (AP-1) within hours followed by a decline in their activation, decreased activation of extracellular signal-regulated kinases (ERK1/2), decreased cell-associated antiapoptotic Bcl-xL protein but increased apoptosis. Clusterin progressively increased in the media over a 3 day period. Clusterin siRNA blocked protein production, increased NF-kappaB activation, and significantly increased cellular Bcl-xL protein, thereby reducing spontaneous and BSA-induced apoptosis. An siRNA to the NF-kappaB inhibitor IkappaBalpha had similar results. BSA-stimulated NF-kappaB activation reciprocally decreased AP-1 activity by preventing ERK1/2 phosphorylation. These in vitro studies suggest that clusterin inhibits NF-kappaB-mediated antiapoptotic effects by the apparent stabilization of IkappaBalpha switching from promoting inflammation to apoptosis during proteinuria.

Loss of Nkx3.1 expression in the transgenic adenocarcinoma of mouse prostate model

BACKGROUND

The transgenic adenocarcinoma of mouse prostate (TRAMP) model has been extensively characterized at the histological and molecular levels, and has been shown to mimic significant features of human prostate cancer. However, the status of Nkx3.1 expression in the TRAMP model has not been elucidated.

METHODS

Immunohistochemical analyses were performed using dorsal, lateral, and ventral prostate (VP) lobes from ages 6 to 30 weeks. Quantitative RT-PCR analyses were performed to determine relative mRNA expression.

RESULTS

Heterogeneous loss of Nkx3.1 was observed in hyperplastic lesions of the ventral, dorsal, and lateral lobes. At 6 weeks of age, the ventral lobe displayed profound loss of Nkx3.1. Diminished Nkx3.1 protein was observed in well- to moderately-differentiated cancer lesions of all lobes. Poorly differentiated (PD) tumors stained negatively for Nkx3.1. Quantitative RT-PCR analyses revealed the presence of Nkx3.1 mRNA in each lobe at all ages, albeit reduced to variable levels.

CONCLUSIONS

These data suggest that disease progression in the TRAMP model may be driven by loss of function of Nkx3.1, in addition to p53 and Rb. Lobe-specific disease progression in the TRAMP model correlates with the reduction of Nkx3.1 protein. Regulation of Nkx3.1 expression during tumorigenesis appears to occur by post-transcriptional and post-translational mechanisms.

Clusterin isoforms differentially affect growth and motility of prostate cells: possible implications in prostate tumorigenesis

Besides a fully processed, secreted form of clusterin (sCLU), an alternative proapoptotic form of the protein targeting the nucleus (nCLU) was recently described. The possible differential roles played by the two clusterin forms in growth and motility of nonmalignant and malignant prostate cells are investigated here. sCLU or nCLU was transiently transfected in both androgen-independent prostate cancer cells (PC3 and DU 145) and immortalized prostate epithelial cells (PNT1A, a nontumoral control). Then, cell growth, motility, and cytoskeleton organization were studied. We found that (a) in PNT1A cells, both sCLU and nCLU significantly decreased cell proliferation and motility; (b) in PC3 and DU 145 cancer cells, only nCLU inhibited cell growth and migration, with sCLU being ineffective; and (c) the antimotility effect of nCLU was accompanied by a dramatic dismantling of the actin cytoskeleton. Moreover, transfection with "full-length" CLU cDNA produced both sCLU and nCLU in nonmalignant PNT1A cells, whereas only sCLU was found in cancer cells. Thus, CLU gene expression might play a crucial role in prostate tumorigenesis by exerting differential biological effects on normal versus tumor cells through differential processing of CLU isoforms in the two cell systems. We also found that nCLU binds to alpha-actinin, a key protein for the regulation of actin cytoskeleton, and that nCLU and alpha-actinin colocalize in the cytoplasm. Thus, the antimotility activity of nCLU and its ability to cause dismantling of the actin cytoskeleton seem to be mediated by its binding to alpha-actinin.

Follistatin antagonizes transforming growth factor-beta3-induced epithelial-mesenchymal transition in vitro: implications for murine palatal development supported by microarray analysis

Epithelial-mesenchymal transition (EMT) is involved in normal embryonic development as well as in tumor progression and invasiveness. This process is also known to be a crucial step in palatogenesis during fusion of the bi-lateral palatal processes. Disruption of this step results in a cleft palate, which is among the most frequent birth defects in humans. A number of genes and encoded proteins have been shown to play a role in this developmental stage. The central role is attributed to the cytokine transforming growth factor-beta3 (TGF-beta3), which is expressed in the medial edge epithelium (MEE) already before the fusion process. The MEE covers the tips of the growing palatal shelves and eventually undergoes EMT or programmed cell death (apoptosis). TGF-beta3 is described to induce EMT in embryonic palates. With regard to the early expression of this molecule before the fusion process, it is not well understood which mechanisms prevent the TGF-beta3 producing epithelial cells from undergoing differentiation precociously. We used the murine palatal fusion to study the regulation of EMT. Specifically, we analyzed the MEE for the expression of known antagonists of TGF-beta molecules using in situ hybridization and detected the gene coding for Follistatin to be co-expressed with TGF-beta3. Further, we could show that Follistatin directly binds to TGF-beta3 and that it completely blocks TGF-beta3-induced EMT of the normal murine mammary gland (NMuMG) epithelial cell line in vitro. In addition, we analyzed the gene expression profile of NMuMG cells during TGF-beta3-induced EMT by microarray hybridization, detecting strong changes in the expression of apoptosis-regulating genes.

Synergy of p53 and Rb deficiency in a conditional mouse model for metastatic prostate cancer

Pathways mediated by p53 and Rb are frequently altered in aggressive human cancers, including prostate carcinoma. To test directly the roles of p53 and Rb in prostate carcinogenesis, we have conditionally inactivated these genes in the prostate epithelium of the mouse. Inactivation of either p53 or Rb leads to prostatic intraepithelial neoplasia developing from the luminal epithelium by 600 days of age. In contrast, inactivation of both genes results in rapidly developing (median survival, 226 days) carcinomas showing both luminal epithelial and neuroendocrine differentiation. The resulting neoplasms are highly metastatic, resistant to androgen depletion from the early stage of development, and marked with multiple gene expression signatures commonly found in human prostate carcinomas. Interestingly, gains at 4qC3 and 4qD2.2 and loss at 14qA2-qD2 have been consistently found by comparative genomic hybridization. These loci contain such human cancer-related genes as Nfib, L-myc, and Nkx3.1, respectively. Our studies show a critical role for p53 and Rb deficiency in prostate carcinogenesis and identify likely secondary genetic alterations. The new genetically defined model should be particularly valuable for providing new molecular insights into the pathogenesis of human prostate cancer.

Prostate Cancer Associated withp53andRbDeficiency Arises from the Stem/Progenitor Cell–Enriched Proximal Region of Prostatic Ducts

Recently, we have shown that prostate epithelium-specific deficiency for p53 and Rb tumor suppressors leads to metastatic cancer, exhibiting features of both luminal and neuroendocrine differentiation. Using stage-by-stage evaluation of carcinogenesis in this model, we report that all malignant neoplasms arise from the proximal region of the prostatic ducts, the compartment highly enriched for prostatic stem/progenitor cells. In close similarity to reported properties of prostatic stem cells, the cells of the earliest neoplastic lesions express stem cell marker stem cell antigen 1 and are not sensitive to androgen withdrawal. Like a subset of normal cells located in the proximal region of prostatic ducts, the early neoplastic cells coexpress luminal epithelium markers cytokeratin 8, androgen receptor, and neuroendocrine markers synaptophysin and chromogranin A. Inactivation of p53 and Rb also takes place in the lineage-committed transit-amplifying and/or differentiated cells of the distal region of the prostatic ducts. However, the resulting prostatic intraepithelial neoplasms never progress to carcinoma by the time of mouse death. Interestingly, in an ectopic transplantation assay, early mutant cells derived from either region of the prostatic ducts are capable of forming neoplasms within 3 months. These findings indicate that p53 and Rb are critically important for the regulation of the prostatic stem cell compartment, the transformation in which may lead to particularly aggressive cancers in the context of microenvironment.

Regulation of clusterin/apolipoprotein J, a functional homologue to the small heat shock proteins, by oxidative stress in ageing and age-related diseases

Clusterin/apolipoprotein J (CLU) gene has a nearly ubiquitous expression pattern in human tissues. The two main CLU protein isoforms in human cells include the conventional glycosylated secreted heterodimer (sCLU) and a truncated nuclear form (nCLU). CLU has been implicated in various physiological processes and in many severe physiological disturbance states including ageing, cancer progression, vascular damage, diabetes, kidney and neuron degeneration. Although unrelated in their etiology and clinical manifestation, these diseases represent states of increased oxidative stress, which in turn, promotes amorphous aggregation of target proteins, increased genomic instability and high rates of cellular death. Among the various properties attributed to CLU so far, those mostly investigated and invariably appreciated are its small heat shock proteins-like chaperone activity and its involvement in cell death regulation, which are both directly correlated to the main features of oxidant injury. Moreover, the presence of both a heat shock transcription factor-1 and an activator protein-1 element in the CLU gene promoter indicate that CLU gene can be an extremely sensitive biosensor to reactive oxygen species. This review emphasizes on CLU gene regulation by oxidative stress that is the common link between all pathological conditions where CLU has been implicated.

Ethylenediaminetetraacetic acid affects subcellular expression of clusterin protein in human colon adenocarcinoma COLO 205 cell line

The aim of our study was to determine the expression of various isoforms of clusterin and to evaluate how etoposide or calcium chelators [ethylenediaminetetraacetic acid and (2-aminoethoxyethane)-N,N,N',N'-tetraacetic acid] affect the subcellular expressions of the 50-kDa isoform of clusterin protein in colon adenocarcinoma COLO 205 cells. We then determined how the cytoplasmic vs. nuclear expression of the 50-kDa isoform of clusterin correlates with the viability of COLO 205 cells. To identify the clusterin isoforms, and its nuclear and cytoplasmic expression in COLO 205 cells, Western bloting was used. Cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide assay. Etoposide decreased the viability of COLO 205 cells with a concomitant increase in the 50-kDa clusterin concentration in the cell nucleus. Chelation of the extracellular calcium ions by (2-aminoethoxyethane)-N,N,N',N'-tetraacetic acid did not modulate the subcellular distribution of clusterin. The use of ethylenediaminetetraacetic acid, which reduces the intracellular and extracellular calcium levels, stimulated nuclear expression of clusterin protein and was accompanied by extensive cell death. Intracellular calcium determines cytoplasmic expression and antiapoptotic activity of the intracellular protein clusterin. The depletion of intracellular calcium leads to increased nuclear expression of the 50-kDa clusterin protein, which is accompanied by cell death. We concluded that there is at least one cell death-promoting pathway in COLO 205 cells that is dependent on intracellular calcium and nuclear localization of 50-kDa clusterin.