Proteomic detection of changes in protein synthesis induced by fibroblast growth factor-2 in MCF-7 human breast cancer cells

Topoisomerase II is regulated by translationally controlled tumor protein for cell survival during organ growth in Drosophila

Regulation of cell survival is critical for organ development. Translationally controlled tumor protein (TCTP) is a conserved protein family implicated in the control of cell survival during normal development and tumorigenesis. Previously, we have identified a human Topoisomerase II (TOP2) as a TCTP partner, but its role in vivo has been unknown. To determine the significance of this interaction, we examined their roles in developing Drosophila organs. Top2 RNAi in the wing disc leads to tissue reduction and caspase activation, indicating the essential role of Top2 for cell survival. Top2 RNAi in the eye disc also causes loss of eye and head tissues. Tctp RNAi enhances the phenotypes of Top2 RNAi. The depletion of Tctp reduces Top2 levels in the wing disc and vice versa. Wing size is reduced by Top2 overexpression, implying that proper regulation of Top2 level is important for normal organ development. The wing phenotype of Tctp RNAi is partially suppressed by Top2 overexpression. This study suggests that mutual regulation of Tctp and Top2 protein levels is critical for cell survival during organ development.

History of Histamine-Releasing Factor (HRF)/Translationally Controlled Tumor Protein (TCTP) Including a Potential Therapeutic Target in Asthma and Allergy

Histamine-releasing factor (HRF) also known as translationally controlled tumor protein (TCTP) is a highly conserved, ubiquitous protein that has both intracellular and extracellular functions. Here we will highlight the subcloning of the molecule, its clinical implications, as well as an inducible-transgenic mouse. Particular attention will be paid to its extracellular functioning and its potential role as a therapeutic target in asthma and allergy. The cells and the cytokines that are produced when stimulated or primed by HRF/TCTP will be detailed as well as the downstream signaling pathway that HRF/TCTP elicits. While it was originally thought that HRF/TCTP interacted with IgE, the finding that cells not binding IgE also respond to HRF/TCTP called this interaction into question. HRF/TCTP or at least its mouse counterpart appears to interact with some, but not all IgE and IgG molecules. HRF/TCTP has been shown to activate multiple human cells including basophils, eosinophils, T cells, and B cells. Since many of the cells that are activated by HRF/TCTP participate in the allergic response, the extracellular functions of HRF/TCTP could exacerbate the allergic, inflammatory cascade. Particularly exciting is that small molecule agonists of the phosphatase SHIP-1 have been shown to modulate the P13 kinase/AKT pathway and may control inflammatory disorders. This review discusses this possibility in light of HRF/TCTP.

Insights into the role and regulation of TCTP in skeletal muscle

The translationally controlled tumor protein (TCTP) is upregulated in a range of cancer cell types, in part, by the activation of the mechanistic target of rapamycin (mTOR). Recently, TCTP has also been proposed to act as an indirect activator of mTOR. While it is known that mTOR plays a major role in the regulation of skeletal muscle mass, very little is known about the role and regulation of TCTP in this post-mitotic tissue. This study shows that muscle TCTP and mTOR signaling are upregulated in a range of mouse models (mdx mouse, mechanical load-induced hypertrophy, and denervation- and immobilization-induced atrophy). Furthermore, the increase in TCTP observed in the hypertrophic and atrophic conditions occurred, in part, via a rapamycin-sensitive mTOR-dependent mechanism. However, the overexpression of TCTP was not sufficient to activate mTOR signaling (or increase protein synthesis) and is thus unlikely to take part in a recently proposed positive feedback loop with mTOR. Nonetheless, TCTP overexpression was sufficient to induce muscle fiber hypertrophy. Finally, TCTP overexpression inhibited the promoter activity of the muscle-specific ubiquitin proteasome E3-ligase, MuRF1, suggesting that TCTP may play a role in inhibiting protein degradation. These findings provide novel data on the role and regulation of TCTP in skeletal muscle in vivo.

Targeting TCTP with Sertraline and Thioridazine in Cancer Treatment

We have initially demonstrated in knocking down experiments that decreasing TCTP in cancer cells leads in some tissues to cell death while in others to a complete reorganization of the tumor into architectural structures reminiscent of normal ones. Based on these experiments and a series of other findings confirming the key role of TCTP in cancer, it became important to find pharmacological compounds to inhibit its function, and this became for us a priority. In the present text, we explain in detail the experiments that were performed and the perspectives of sertraline in cancer treatment, as this became today a reality with a clinical study that started in collaboration with Columbia University and Johns Hopkins University.

Potential role of histamine releasing factor (HRF) as a therapeutic target for treating asthma and allergy

Histamine releasing factor (HRF), also known as translationally controlled tumor protein (TCTP), is a highly conserved, ubiquitous protein that has both intracellular and extracellular functions. Here, we will highlight the history of the molecule, its clinical implications with a focus on its extracellular functioning, and its potential role as a therapeutic target in asthma and allergy. The cells and cytokines produced when stimulated or primed by HRF/TCTP are detailed as well as the downstream signaling pathway that HRF/TCTP elicits. While it was originally thought that HRF/TCTP interacted with IgE, the finding that cells not binding IgE also respond to HRF/TCTP called this interaction into question. HRF/TCTP, or at least its mouse counterpart, appears to interact with some, but not all IgE and IgG molecules. HRF/TCTP has been shown to activate multiple human cells including basophils, eosinophils, T cells, and B cells. Since many of the cells activated by HRF/TCTP participate in the allergic response, extracellular functions of HRF/TCTP may exacerbate the allergic, inflammatory cascade. Particularly exciting is that small molecule agonists of Src homology 2-containing inositol phosphatase-1 have been shown to modulate the phosphoinositide 3-kinase/AKT pathway and may control inflammatory disorders. This review discusses this possibility in light of HRF/TCTP.

Upregulation of TCTP expression in human skin squamous cell carcinoma increases tumor cell viability through anti-apoptotic action of the protein

The translationally controlled tumor protein (TCTP) is an anti-apoptotic protein, which is highly expressed in several human cancer types. However, the role of TCTP in skin cancers, including squamous cell carcinoma (SCC), has not been investigated. In this study, we analyzed the expression of TCTP in cutaneous SCC samples using immunohistochemistry in two epidermoid SCC cell lines, A431 and SCL-1, using western blot analysis. We further investigated the role of TCTP in skin cancinogenesis by silencing the TPT1 gene using small interfering RNA (siRNA) in the SCC cell line A431. Our results demonstrated that TCTP was overexpressed in cutaneous SCC cells, compared to normal skin keratinocytes. In addition, the expression of TCTP in skin SCC significantly increased with the grade of malignancy. Western blot analysis further confirmed that the expression of TCTP in the cell lines, A431 and SCL-1, was significantly higher compared to that in the normal keratinocyte cell line, HaCaT. The expression of TCTP in A431 cells was significantly downregulated by transfection with our specifically designed TCTP siRNA. We found that downregulation of TCTP expression was associated with decreased cell proliferation and increased apoptosis in A431 cells. These results suggest that the TPT1 gene may be a potential therapeutic target in skin SCC through a siRNA approach.

TRX is up-regulated by fibroblast growth factor-2 in lung carcinoma

We have previously shown that exogenous fibroblast growth factor-2 (FGF-2) inhibits apoptosis of the small-cell lung cancer (SCLC) cell line NCI-H446, but the underlying mechanism remains unknown. In this study, the protein profiles of FGF-2-treated and untreated NCI-H446 cells were determined by 2-D gel electrophoresis combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and bioinformatics. Differential expression analysis of the protein profiles after FGF-2 treatment identified a total of 24 protein spots, of which nine were up-regulated and 15 were down-regulated. Four proteins were identified by MALDI-TOF-MS: thioredoxin (TRX), visfatin, ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) and Cu/Zn superoxide dismutase (CuZn-SOD). Western blotting revealed that TRX was up-regulated in NCI-H446 and A549 cells treated with FGF-2. Furthermore, immunohistochemical staining confirmed that both FGF-2 and TRX were overexpressed in lung cancer tissues and could be correlated with both lymph node metastasis and clinical stage. These data indicate that TRX may be involved in the FGF-2 signaling pathway.

Molecular cloning and expression characterization of translationally controlled tumor protein in silkworm pupae

A Bombyx mori (B. mori) cDNA was isolated from silkworm pupae cDNA library encoding a homologue of translationally controlled tumor protein (BmTCTPk). BmTCTPk was expressed in E. coli; SDS-PAGE and Western blot showed the molecular weight of recombinant and native BmTCTPk is approximately 28 and 25 kDa, respectively; they are larger than the theoretical molecular weight. Immunohistochemical studies showed that BmTCTPk is uniformly distributed throughout the cytoplasm of BmN cells. In silkworm pupae, BmTCTPk is expressed in the midgut wall, the midgut cavity, and some fat body tissues lying between the midgut wall and body wall. Western blot and ELISAs performed on total protein extracts isolated from silkworm pupae at different development stages showed that, although BmTCTPk is expressed during all pupae stages, its expression level increases dramatically during late pupae stages, suggesting that BmTCTPk may play an important role during the developmental transition from pupa to imago.

Membrane protein analysis of human breast cancer cell line MCF-7 by different membrane washing methods

Membrane and membrane-associated proteins are rich in known or potential pharmaceutical drug targets for carcinogenesis. In order to systemically analyze membrane proteins of human breast cancer, we isolated membrane from MCF-7 cells by sequential extraction by washing with three different buffers, namely, phosphate buffer (5 mM, pH 8.0), Tris (40 mM, pH 9.5), and sodium carbonate (100 mM pH 11). The extracted proteins were separated by two-dimensional gel electrophoresis (2-DE) using cup-loading and were then analyzed by peptide mass fingerprinting (PMF). A total of 137 spots from the gels of the three procedures were successfully identified. They corresponded to 79 distinct proteins. Among them, 22 exclusive proteins belonging to each washing procedure were also found, including P-glycoprotein, endoplasmin, Stress-70 protein, ADAM 10, protein disulfide isomerase, and glutamate receptor. These results indicate phosphate buffer to be the most beneficial for enrichment of peripheral membrane proteins, and sodium carbonate is beneficial for the presentation of integral membrane proteins but usually with poor resolution. The reference maps and identified proteins will serve as a basis for the further investigation of breast cancer, especially the proteomic comparison among different cell types of breast cancer, or among the different stages in the drug interfering process of the MCF-7 cell line.

Neuron-microglia crosstalk up-regulates neuronal FGF-2 expression which mediates neuroprotection against excitotoxicity via JNK1/2

Glial cells and neurons are in constant reciprocal signalling both under physiological and neuropathological conditions. Microglial activation is often associated with neuronal death during inflammation of the CNS, although microglial cells are also known to exert a neuroprotective role. In this work, we investigated the interplay between cerebellar granule neurons (CGN) and microglia in the perspective of CGN survival to an excitotoxic stimulus, quinolinic acid (QA), a catabolite of the tryptophan degradation pathway. We observed that CGN succumb to QA challenge via extracellular signal regulated kinase 1 and 2 (ERK) activation. Our data with transgenic mice expressing the natural inhibitor of calpains, calpastatin, indicate that together with cathepsins they mediate QA-induced toxicity acting downstream of the mitogen-activated protein kinase kinase-ERK pathway. Microglial cells are not only resistant to QA but can rescue neurons from QA-mediated toxicity when they are mixed in culture with neurons or by using mixed culture-conditioned medium (MCCM). This effect is mediated via fibroblast growth factor-2 (FGF-2) present in MCCM. FGF-2 is transcriptionally up-regulated in neurons and secreted in the MCCM as a result of neuron-microglia crosstalk. The neuroprotection is associated with the retention of cathepsins in the lysosomes and with transactivation of inducible heat-shock protein 70 downstream of FGF-2. Furthermore, FGF-2 upon release by neurons activates c-jun N-terminal kinase 1 and 2 pathway which also contributes to neuronal survival. We suggest that FGF-2 plays a pivotal role in neuroprotection against QA as an outcome of neuron-microglia interaction.

Radiolabeling for two-dimensional gel analysis

Radiolabeling is a highly sensitive method for protein detection, which is easily performed by the incorporation of radioactive amino acids into proteins. This makes radiolabeling a method of choice for visualizing proteins separated on two-dimensional (2-D) gels. This chapter presents protocols to determine in vivo labeling conditions and to label proteins for the comparison of protein samples by means of 2-D gel electrophoresis.

Altered chaperone and protein turnover regulators expression in cultured skin fibroblasts from type 1 diabetes mellitus with nephropathy

In type-1 diabetes mellitus (T1DM) with diabetic nephropathy (DN), accumulation of abnormal proteins in the kidney and other tissues may derive from constitutive alterations of intracellular protein recognition, assembly, and turnover. We characterized the proteins involved in these functions in cultured skin fibroblasts from long-term T1DM patients with [DN+] or without [DN-] nephropathy but similar metabolic control, and from matched healthy subjects. 2-D gel electrophoresis and MS-MALDI analysis were employed. The [DN+] T1DM patients, compared with the two other groups, exhibited increased abundance of a high-molecular weight isoform of protein disulphide-isomerase A3 and a decrease of two low-molecular weight isoforms. They also had increased levels of heat shock protein (HSP) 60 kDa isoform #A4, of HSP71 kDa isoform #A30, and of HSP27 kDa isoform #6, whereas the HSP27 kDa isoforms #A90 and #A71 were decreased. Cathepsin beta-2 (#40), the cation-independent mannose 6-phosphate receptor binding protein 1 (CIMPR) (#A27), and annexin 2 (#A9) were also decreased in the [DN+] T1DM patients, whereas the RNA-binding protein regulatory subunity (#38) and the translationally-controlled tumor protein (TCTP) (#A45) were increased. These changes of chaperone-like proteins in fibroblasts may highlight those of the kidney and be patho-physiologically related to the development of nephropathy in T1DM.

Proteomics of TGF-beta signaling and its impact on breast cancer

The complexity of mechanisms leading to the appearance and progression of cancer is a challenge being addressed by large-scale studies, such as proteomics. Simultaneous monitoring of thousands of proteins uncovers novel signaling mechanisms, thus revising our knowledge of tumorigenesis. Transforming growth factor (TGF)-beta is a secreted polypeptide that is known to inhibit tumor growth at the early stages of cancer, but promote metastasis at the later stages. Proteomics-based studies have significantly widened our knowledge of TGF-beta-dependent regulation of cell proliferation, apoptosis, DNA damage repair and transcription. This leads to better understanding of the TGF-beta role in human breast tumorigenesis, and opens the way for the development of novel anticancer treatments and drugs, with some of the drugs already entering clinics. This review discusses recent advances in proteomics studies of TGF-beta signaling and its contribution to the understanding and treatment of breast cancer.

Comparative proteome analysis of breast cancer and adjacent normal breast tissues in human

Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS), incorporated with online database searching, were performed to investigate differential proteins of breast cancer and adjacent normal breast tissues. Considering that serum albumin is abundantly presented in normal control samples, 15 differential spots detected in 11 out of 12 (91.7%) breast cancer samples were identified by online SIENA-2DPAGE database searching and MALDI-TOF/TOF-MS analysis. The results indicate that pathological changes of breast cancer are concerned with augmentation of substance metabolism, promotion of proteolytic activity, decline of activity of some inhibitors of enzymes, and so on. Some important proteins involved in the pathological process of breast cancer with changed expression may be useful biomarkers, such as alpha-1-antitrypsin, EF-1-beta, cathepsin D, TCTP, SMT3A, RPS12, and PSMA1, among which SMT3A, RPS12, and PSMA1 were first reported for breast cancer in this study.

Proteomic analysis of MCF-7 breast cancer cell line exposed to mitogenic concentration of 17β-estradiol

Estrogens are powerful mitogens that play a critical role in the onset of breast cancer and its progression. About two-thirds of all breast cancers are estrogen receptor (ER)+ at the time of diagnosis, and the ER expression is the determinant of a tumor phenotype associated with hormone responsiveness. The molecular basis of the relationship between ER expression, (anti)hormonal responsiveness, and breast cancer prognosis is still unknown. To identify the proteins affected by the presence of the hormone we used 2-D-PAGE-based bottom-up proteomics for the study of the proteome of MCF-7 cells of estrogen-responsive breast carcinoma exposed to a mitogenic concentration of 17beta-estradiol (E2) for 12, 18, 24, and 30 h. Differential expression analysis showed significant changes for 12 proteins. These include ezrin-radixin-moesin-binding phosphoprotein of 50 kDa which was previously shown to be directly regulated by E2. Expression profiles of other proteins already implicated in the progression of breast cancer, such as stathmin, calreticulin, heat shock 71 kDa, alpha-enolase are also described. Moreover, it is observed that different unexpected proteins, translation factors, and energetic metabolism enzymes are also influenced by the presence of the hormone.

Design, synthesis, and biological evaluation of hydroquinone derivatives of 17-amino-17-demethoxygeldanamycin as potent, water-soluble inhibitors of Hsp90

17-Allylamino-17-demethoxygeldanamycin (17-AAG)1 is a semisynthetic inhibitor of the 90 kDa heat shock protein (Hsp90) currently in clinical trials for the treatment of cancer. However, 17-AAG faces challenging formulation issues due to its poor solubility. Here we report the synthesis and evaluation of a highly soluble hydroquinone hydrochloride derivative of 17-AAG, 1a (IPI-504), and several of the physiological metabolites. These compounds show comparable binding affinity to human Hsp90 and its endoplasmic reticulum (ER) homologue, the 94 kDa glucose regulated protein (Grp94). Furthermore, the compounds inhibit the growth of the human cancer cell lines SKBR3 and SKOV3, which overexpress Hsp90 client protein Her2, and cause down-regulation of Her2 as well as induction of Hsp70 consistent with Hsp90 inhibition. There is a clear correlation between the measured binding affinity of the compounds and their cellular activities. Upon the basis of its potent activity against Hsp90 and a significant improvement in solubility, 1a is currently under evaluation in Phase I clinical trials for cancer.

Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) is regulated by CREB transcription factors

Re-evaluation of genomic and cDNA data revealed that the human TPT1 gene coding for the translationally controlled tumor protein (TCTP) consists of at least 4211 base pairs. It is transcribed into two transcripts of about 0.8 and 1.2 kb, which contain the same coding region and 5'-UTR, but differ in the length of 3'-UTRs by the use of alternative polyadenylation signals. 459 bp promoter sequences were analyzed by theoretical evaluation, reporter-gene assays, gelshift and footprinting experiments to search for transcription factor binding sites. The promoter contains two highly conserved CRE sites between -50 and -89 in close vicinity to a TATA-box at -30. Supershift assays identified CREB I and Fra II of the CREB/ATF1/AP1 family as factors interacting with the CRE/AP1 site. A 3-5-fold stimulation of TCTP synthesis by forskolin and phorbolester in T24 cells and promoter-reporter experiments using CRE-deletion constructs suggested a transcriptional control by cAMP signaling via phosphorylation dependent activation of CRE/CREB interaction.

New frontiers in proteomics research: A perspective

Substantial advances have been made in the fundamental understanding of human biology, ranging from DNA structure to identification of diseases associated with genetic abnormalities. Genome sequence information is becoming available in unprecedented amounts. The absence of a direct functional correlation between gene transcripts and their corresponding proteins, however, represents a significant roadblock for improving the efficiency of biological discoveries. The success of proteomics depends on the ability to identify and analyze protein products in a cell or tissue and, this is reliant on the application of several key technologies. Proteomics is in its exponential growth phase. Two-dimensional electrophoresis complemented with mass spectrometry provides a global view of the state of the proteins from the sample. Proteins identification is a requirement to understand their functional diversity. Subtle difference in protein structure and function can contribute to complexity and diversity of life. This review focuses on the progress and the applications of proteomics science with special reference to integration of the evolving technologies involved to address biological questions.

Global Protein Shotgun Expression Profiling of Proliferating MCF-7 Breast Cancer Cells

Protein expression becomes altered in breast epithelium during malignant transformation. Knowledge of these perturbations should provide insight into the molecular basis of breast cancer, as well as reveal possible new therapeutic targets. To this end, we have performed an extensive comparative proteomic survey of global protein expression patterns in proliferating MCF-7 breast cancer cells and normal human mammary epithelial cells using gel-free shotgun tandem mass spectrometry. Pathophysiological alterations associated with the malignant breast cancer phenotype were detected, including differences in the apparent levels of key regulators of the cell cycle, signal transduction, apoptosis, transcriptional regulation, and cell metabolism.

The molecular and biological analysis of ixodid ticks histamine release factors

We previously described a Dermacentor varibialis (DV) cDNA that encodes a ubiquitously expressed and tick saliva-secreted functional histamine release factor (HRF) homolog. In this study gene specific primers based on DVHRF open reading frame nucleotide sequence were utilized to amplify three orthologs, from the wood tick, D. andersoni (DA), the black legged tick, the southern cattle tick, Boophilus microplus (BM) and the lone star tick, Amblyomma americanum (AA). At nucleotide level, sequence comparisons revealed 98 89 and 84% similarity to DVHRF for DAHRF, AAHRF and BMHRF, respectively, while predicted polypeptide comparisons revealed 98, 96 and 91% similarity for DAHRF, AAHRF and BMHRF respectively. Phylogenetically, the tick HRF clade, while distinct (100% bootstrap value), is closely related to other arthropods, but distantly related to vertebrate and protozoan clades. Consistent with sequence similarity analysis, a DVHRF-specific northern blotting probe hybridized a approximately 900 base pair (bp) mRNA band on all RNA blots. Likewise a mouse polyclonal antibody to E. coli-expressed recombinant (r) DVHRF, cross-reacted baculovirus-expressed non-fusion rAAHRF, rDAHRF, and rBMHRF. As revealed by northern blotting analysis of larvae and nymph RNA, DVHRF mRNA is expressed in both immature and mature ticks indicating that its transcription is not developmentally regulated. Unlike rHRF/TCTP proteins of other organisms, the calcium-binding function may not be conserved for tick HRF homologs as revealed by the 45CaCl2+ overlay assay. Apparent global expression of DVHRF and its orthologs make this protein family an ideal target antigen for development of novel tick control strategies targeting multiple tick species.

Molecular cloning and characterization of the translationally controlled tumor protein gene in Bombyx mori

Translationally controlled tumor protein (Tctp/p23) is known to be synthesized preferentially in cells during the early growth phase of tumors, but is also expressed in normal cells. To elucidate its molecular basis of the expression and physiological significance, a cDNA encoding for the Bombyx mori Tctp (BmTctp) was deduced by editing the partial cDNA sequences registered in a Bombyx EST database. RT-PCR analyses indicated that the BmTCTP mRNA was transcribed in all larval organs examined and was present constantly during the cell cycle of BmN4 cells. A genomic clone of 4255 nucloetide residues produced by inverse PCR contained the 5'-flanking region, two introns and three exons of the BmTCTP gene. Sequence analysis of the 5'-flanking region indicated that a putative promoter region contains several canonical transcription elements such as GATA box, CCAAT motif, MEF2, E4BP4.01 and AP-1, but lacks a TATA box element. Luciferase reporter assay of the deletion constructs of the 5'-flanking region revealed that the -676 to +66 region enhanced the promoter activity the most markedly. In addition to this, there were at least two enhancer-like elements and several repressor elements.

Significance of heat shock protein-27 expression in patients with renal cell carcinoma

OBJECTIVES

To investigate heat shock protein (HSP)-27 expression in patients with renal cell carcinoma (RCC) and examine its biologic significance. HSPs were first defined as proteins induced by heat shock and other environmental and pathophysiologic stresses. They are implicated in protein-protein interactions and are thought to play an important role in cancer. The expression of HSP-27 has been demonstrated in some human tumors.

METHODS

The expression of HSP-27 was studied in tumor and normal parenchyma tissue specimens from 76 patients with RCC by immunohistochemistry. The findings were correlated with clinical stage, lymph node metastasis, histologic grade, and survival.

RESULTS

Of the 76 RCC tissue specimens studied, the presence of HSP-27 was demonstrated in 73 (96%). The expression was low in 10 patients (14%), intermediate in 38 (50%), and high in 25 (33%). HSP-27 expression was greater in RCC tissue compared with adjacent noncancerous renal tissue (P <0.001). An inverse relationship was found between tumor stage and HSP-27 expression (r = -0.281, P = 0.016). However, no statistically significant difference was observed in progression-free survival with respect to HSP-27 expression. No relationship was found between HSP-27 expression and tumor grade, lymph node metastasis, distant metastasis, or cause-specific survival.

CONCLUSIONS

Our data suggest that HSP-27 expression is not a powerful and statistically significant prognostic indicator for disease-free survival for patients with RCC.

Proteomics in the chicken: tools for understanding immune responses to avian diseases

The entire chicken genome sequence will be available by the time this review is in press. Chickens will be the first production animal species to enter the "postgenomic era." This fundamental structural genomics achievement allows, for the first time, complete functional genomics approaches for understanding the molecular basis of chicken normo- and pathophysiology. The functional genomics paradigm, which contrasts with classical functional genetic investigations of one gene (or few) in isolation, is the systematic holistic genetic analyses of biological systems in defined contexts. Context-dependent gene interactions are the fundamental mechanics of all life. Functional genomics uses high-throughput large-scale experimental methods combined with statistical and computational analyses. Projects with expressed sequence tags in chickens have already allowed the creation of cDNA microarrays for large-scale context-dependant mRNA analysis (transcriptomics). However, proteins are the functional units of almost all biological processes, and protein expression very often bears no correlation to mRNA expression. Proteomics, a discipline within functional genomics, is the context-defined analysis of complete complements of proteins. Proteomics bridges the "sequence-to-phenotype gap;" it complements structural and other functional genomics approaches. Proteomics requires high capital investment but has ubiquitous biological applications. Although currently the fastest-growing human biomedical discipline, new paradigms may need to be established for production animal proteomics research. The prospective promise and potential pitfalls of using proteomics approaches to improve poultry pathogen control will be specifically highlighted. The first stage of our recently established proteomics program is global protein profiling to identify differentially expressed proteins in the context of the commercially important pathogens. Our trials and tribulations in establishing our proteomics program, as well some of our initial data to understand chicken immune system function, will be discussed.

Newly expressed proteins of mouse embryonic fibroblasts irradiated to be inactive

It has been found that post-radiation mouse embryonic fibroblasts can well maintain the pluripotency in human embryonic stem cells. However, the molecular mechanism remains unclear. In the present study, the new protein expression profile of post-radiation mouse embryonic fibroblasts was analyzed by immobilized pH gradient 2-dimensional polyacrylamide gel electrophoresis. Image analysis following silver staining revealed (969+/-57) vs. (1085+/-107) spots from post-radiation mouse embryonic fibroblasts and pre-radiation ones, respectively. Some newly expressed proteins, which were only abundantly present after irradiation, were subjected to peptide mass fingerprint analysis and identified using MALDI-TOF-MS, SWISS-PROT database, and RT-PCR. Several of those proteins were preliminarily identified to participate in cytokine secretion, cell signal transduction, transcriptional regulation, and apoptosis, etc., which suggested that inactive post-radiation mouse embryonic fibroblasts expressed some new proteins that may underlie the molecular mechanisms to maintain the pluripotency in human embryonic stem cells.

Proteomic evaluation of core biopsy specimens from breast lesions

Analysis of tumour samples by a proteomic technology, which combines two-dimensional gel electrophoresis and mass spectrometry analysis, is a promising approach for molecular characterization of cancer. Proteomic analysis of neoplasms is usually performed on surgical material. The possibility to perform proteomic analysis on pre-operative samples might be useful for diagnostic purposes or for determination of tumour sensitivity to therapy. In this study, we report how tissues from core biopsy of breast lesions can be routinely used to obtain accurate protein expression profiles by proteomic analysis. Protein profiles from fibroadenomas were compared to those from ductal infiltrating carcinomas. By using mass spectrometry, identification of proteins overexpressed in carcinomas with respect to fibroadenomas was obtained. Thus, our study provides a methodology to perform proteomic analysis on pre-operative samples of breast lesions.

Surface nucleolin participates in both the binding and endocytosis of lactoferrin in target cells

Lactoferrin (Lf), a multifunctional molecule present in mammalian secretions and blood, plays important roles in host defense and cancer. Indeed, Lf has been reported to inhibit the proliferation of cancerous mammary gland epithelial cells and manifest a potent antiviral activity against human immunodeficiency virus and human cytomegalovirus. The Lf-binding sites on the cell surface appear to be proteoglycans and other as yet undefined protein(s). Here, we isolated a Lf-binding 105 kDa molecular mass protein from cell extracts and identified it as human nucleolin. Medium-affinity interactions ( approximately 240 nm) between Lf and purified nucleolin were further illustrated by surface plasmon resonance assays. The interaction of Lf with the cell surface-expressed nucleolin was then demonstrated through competitive binding studies between Lf and the anti-human immunodeficiency virus pseudopeptide, HB-19, which binds specifically surface-expressed nucleolin independently of proteoglycans. Interestingly, binding competition studies between HB-19 and various Lf derivatives in proteoglycan-deficient hamster cells suggested that the nucleolin-binding site is located in both the N- and C-terminal lobes of Lf, whereas the basic N-terminal region is dispensable. On intact cells, Lf co-localizes with surface nucleolin and together they become internalized through vesicles of the recycling/degradation pathway by an active process. Morever, a small proportion of Lf appears to translocate in the nucleus of cells. Finally, the observations that endocytosis of Lf is inhibited by the HB-19 pseudopeptide, and the lack of Lf endocytosis in proteoglycan-deficient cells despite Lf binding, point out that both nucleolin and proteoglycans are implicated in the mechanism of Lf endocytosis.

Identification and characterization of a phytoestrogen-specific gene from the MCF-7 human breast cancer cell

Phytoestrogens are a group of compounds present in human diet that display estrogenic-like properties. Several studies have demonstrated that populations who consume large quantities of phytoestrogens have a reduced risk of estrogen-dependent cancers. Although it has been shown that certain phytoestrogens modulate estrogen action, their biological role in cancer reduction remains unclear. Through the use of differential display reverse transcriptase-polymerase chain reaction and representational difference analysis of cDNA, we have identified several phytoestrogen-responsive genes from the human breast cancer cell MCF-7. Two of these genes, PE-13.1 and pRDA-D, have been characterized in greater detail in this study. These genes were not previously known to be regulated by phytoestrogen or estradiol. PE-13.1 is a novel gene that specifies the coding of a 1.10-kb mRNA transcript. Northern blot analysis confirmed that the PE-13.1 transcript is up-regulated by phytoestrogens (Genistein, sevenfold; Zearalenone, twofold) and is nonresponsive to estradiol. Conversely, the pRDA-D transcript was down-regulated by both phytoestrogens and estradiol. The antiestrogen ICI-182,780 inhibits the expression of PE-13.1 and reverses the inhibition of pRDA-D expression induced by phytoestrogens and estradiol. Analysis of the tissue distribution of PE-13.1 transcript by RNA blot reveals that this transcript is expressed in both normal and tumor tissues. This report demonstrates for the first time the presence of two phytoestrogen-responsive genes that may be used as molecular markers in understanding the role dietary estrogen plays in cancer prevention.

Breast cancer: when proteomics challenges biological complexity

Proteomics is now entering into the field of biomedicine with declared hopes for the identification of new pathological markers and therapeutic targets. Current proteomic tools allow large-scale, high-throughput analyses for the detection, identification, and functional investigation of low-abundant proteins. However, the major limitation of proteomic investigations remains the complexity of biological structures and physiological processes, rendering the path of exploration of related pathologies paved with various difficulties and pitfalls. The case of breast cancer illustrates the major challenge facing modern proteomics and more generally post-genomics: to tackle the complexity of life.

Current perspectives in cancer proteomics

Proteome technology has been used widely in cancer research and is a useful tool for the identification of new cancer markers and treatment-related changes in cancer. This article details the use of proteome technology in cancer research, and laboratory-based and clinical cancer research studies are described. New developments in proteome technology that enable higher sample-throughput are evaluated and methods for enhancing conventional proteome analysis (based on two-dimensional electrophoresis) discussed. The need to couple laboratory-based proteomics research with clinically relevant models of the disease is also considered, as this remains the next main challenge of cancer-related proteome research.

Insulin and estrogen receptor ligand influence the FGF-2 activities in MCF-7 breast cancer cells

From the MCF-7 cell line we have developed, a human mammary cancer cell subline with the same karyotype as the mother strain and named MCF-7(SF), able to grow in serum-free chemically defined medium. This cell subline was firstly used to analyze the effect of basic fibroblast growth factor (FGF-2) in estrogen-receptor-positive human breast cancer cells. FGF-2 like estradiol is able to increase cell proliferation and pS2 expression but was also found to inhibit progesterone receptor (PR) expression. The anti-estrogen tamoxifen partly counteracts the effects of FGF-2 and to discriminate between its two main mediators (estrogen receptor vs. anti-estrogen binding site, AEBS) we compare the efficacies of pure anti-estrogen (ICI 182,780) and AEBS ligand (PBPE). It appears that pure anti-estrogen counteracts cell growth and pS2 effects of FGF-2 since AEBS ligand inhibits the cell growth but has no activity on pS2 expression. Secondly, adding insulin (10(-6)M) in the culture medium induces a strong increase in cell proliferation, which then elicits an inhibitory effect of FGF-2 and addition of anti-estrogens, are less efficient to further decrease growth, since the effects of FGF-2 and anti-estrogens on pS2 expression are conserved.

Identification of differentially expressed proteins between human esophageal immortalized and carcinomatous cell lines by two-dimensional electrophoresis and MALDI-TOF-mass spectrometry

AIM: To identify the differentially expressed proteins between the human immortalized esophageal epithelial cell line (SHEE) and the malignant transformed esophageal carcinoma cell line (SHEEC), and to explore new ways for studying esophageal carcinoma associated genes.

METHODS: SHEE and SHEEC cell lines were used to separate differentially expressed proteins by two-dimensional electrophoresis. The silver-stained 2-D gels was scanned with EDAS290 digital camera system and analyzed with the PDQuest 6.2 Software. Six spots in which the differentially expressed protein was more obvious were selected and analyzed with matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI-TOF-MS).

RESULTS: There were 107±4.58 and 115±9.91 protein spots observed in SHEE and SHEEC respectively, and the majority of these spots between the two cell lines matched each other (r = 0.772), only a few were expressed differentially. After analyzed by MALDI-TOF-MS and database search for the six differentially expressed proteins, One new protein as well as other five sequence-known proteins including RNPEP-like protein, human rRNA gene upstream sequence binding transcription factor, uracil DNA glycosylase, Annexin A2 and p300/CBP-associated factor were preliminarily identified.

CONCLUSION: These differentially expressed proteins might play an importance role during malignant transformation of SHEEC from SHEE. The identification of these proteins may serve as a new way for studying esophageal carcinoma associated genes.

Functional proteomics of breast cancer for signal pathway profiling and target discovery

The near completion of human genome sequencing and the introduction of mass spectrometry combined with advanced bioinformatics for protein identification have led to the emergence of proteomics as a powerful tool for characterizing new markers and therapeutic targets. Breast cancer proteomics has already identified proteins of potential clinical interest, such as the molecular chaperone 14-3-3 sigma and the heat shock protein HSP90, and technological innovations such as large scale and high throughput analysis are now driving the field. Methods in functional proteomics have also been developed to study the intracellular signaling pathways that underlie the development of breast cancer cells. As illustrated by fibroblast growth factor-2 and the H19 noncoding oncogenic mRNA, proteomics is a pertinent approach to identify signaling proteins and to decipher the complex signaling circuitry involved in tumor growth and metastasis. Together with genomics, proteomics is now providing a way to define molecular processes involved in breast carcinogenesis and to identify new therapeutic targets. The next challenge will be the introduction of proteomics as a tool for the clinic, for the establishment of diagnosis, prognosis, and the monitoring of treatment; however, this ambitious goal still requires further technological progress in the field.

The application of 2D gel-based proteomics methods to the study of breast cancer

The protein complement of breast cells consists of many thousands of proteins. Recent developments in 2D gel electrophoresis technology have made studies requiring the quantitative analysis of a differential proteome, such as comparison between normal and malignant cells or investigation of drug effects on cells, truly feasible. Computer software plays a central part in the comparisons between multiple gels required for such experiments. In addition, software tools allow patterns of coexpression of proteins to be studied, offering potential insights into protein regulation, interactions, and functions, especially when combined with complementary data on gene expression. In this paper, the technology and limitations of 2D gel-based proteomics are reviewed. Techniques for comparing sets of gels at a global level as well as identifying specific protein features that differentiate gels are discussed. Our own experience of studying the breast cell proteome is used to illustrate the difficulties and achievements of differential proteomics.

Proteomics in studies of signal transduction in epithelial cells

An understanding of the complexity of cancer is important for correct diagnostics and efficient treatment of this disease. Recent developments of proteomics technologies allow us to address the complexity of tumorigenesis at a level of global protein profiling. This review discusses recent studies of signaling processes in cells of epithelial origin undertaken with the use of global protein profiling. Tumors of epithelial origin comprise about 90% of human breast cancers, and it is believed that transformation of breast epithelial cells shares common features of transformation with other mammalian cells: destabilization of the genome followed by acquisition of immortalization, unrestricted growth, evasion of death-inducing signals, and acquisition of invasive and tumor promoting characteristics. Functional proteomics of growth-promoting, growth-inhibiting, and pro-apoptotic signaling pathways, in combination with proteomics studies of breast epithelial cell differentiation and profiling of breast tumorigenesis, revealed groups of regulated proteins: structural components, stress-regulated proteins, regulators of transcription, translation and RNA processing, and regulators of posttranslational modifications, e.g., kinases, phosphatases, and proteases. The first lesson of proteomics studies is the discovery of significant number of new targets, as compared to total number of affected proteins. The second lesson is the poor correlation between expressions of proteins and their mRNAs. The third lesson is the low amplitude of protein changes compared to that observed for mRNA. These observations also recommend the analysis of signaling patterns rather than separate signaling pathways.

Growth signaling in breast cancer cells: outcomes and promises of proteomics

Methods in functional proteomics are now used to study the intracellular signaling pathways that underlie the development of breast cancer. As shown with fibroblast growth factor-2, the oncogenic/non-coding mRNA H19 and 14-3-3 proteins, proteomics is a powerful approach to identify signaling proteins and to decipher the complex signaling circuitry involved in growth of breast cancer cells. Together with genomics, proteomics is now providing a way to define molecular processes involved in breast cancerogenesis and to identify new therapeutic targets.

Proteomics of breast cancer: outcomes and prospects

Breast cancer is a major public health problem. The identification of new markers to differentiate neoplastic from the normal cells, more thorough understanding of different stages of the pathology, as well as the definition of new therapeutic targets, are all of critical importance. With the completion of human genome sequencing and the introduction of mass spectrometry, combined with protein identification via advanced bioinformatics, proteomics has emerged as a valuable tool for the discovery of new molecular markers. New methods in functional proteomics have also been developed to study the intracellular signaling pathways that underline the development of breast cancer. As illustrated with the examples of fibroblast growth factor-2 and H19, an oncogenic, noncoding mRNA, proteomics have become a powerful approach for deciphering the complex signaling circuitry involved in tumor growth. Breast cancer proteomics have already identified proteins of potential clinical interest (such as the molecular chaperone 14-3-3 sigma) and technological innovations in large scale/high throughput analysis are now ushering in new prospects.

The role of proteomics in toxicology: identification of biomarkers of toxicity by protein expression analysis

Proteomics, i.e. the high throughput separation, display and identification of proteins, has the potential to be a powerful tool in drug development. It could increase the predictability of early drug development and identify non-invasive biomarkers of toxicity or efficacy. This review provides an introduction to modern proteomics, with particular reference to applications in toxicology. A literature search was carried out to identify studies in two broad classes: screening/predictive toxicology, and mechanistic toxicology. The strengths and limitations of current methods and the likely impact of techniques in drug development are also considered. Proteomics can increase the speed and sensitivity of toxicological screening by identifying protein markers of toxicity. Proteomics studies have already provided insights into the mechanisms of action of a wide range of substances, from metals to peroxisome proliferators. Current limitations involving speed of throughput are being overcome by increasing automation and the development of new techniques. The isotope-coded affinity tag (ICAT) method appears particularly promising. The application of proteomics to drug development has given rise to the new field of pharmacoproteomics. New associations between proteins and toxicopathological effects are constantly being identified, and major progress is on the horizon as we move into the post-genomic era.

Proteomic analysis of nipple aspirate fluid to detect biologic markers of breast cancer

The early detection of breast cancer is the best means to minimise disease-related mortality. Current screening techniques have limited sensitivity and specificity. Breast nipple aspirate fluid can be obtained noninvasively and contains proteins secreted from ductal and lobular epithelia. Nipple aspirate fluid proteins are breast specific and generally more concentrated than corresponding blood levels. Proteomic analysis of 1 microl of diluted nipple aspirate fluid over a 5-40 kDa range from 20 subjects with breast cancer and 13 with nondiseased breasts identified five differentially expressed proteins. The most sensitive and specific proteins were 6500 and 15 940 Da, found in 75-84% of samples from women with cancer but in only 0-9% of samples from normal women. These findings suggest that (1) differential expression of nipple aspirate fluid proteins exists between women with normal and diseased breasts, and (2) analysis of these proteins may predict the presence of breast cancer.

Heat shock protein expression and anti-heat shock protein reactivity in renal cell carcinoma

Heat shock proteins (HSP) are families of highly conserved proteins which are induced in cells and tissues upon exposure to extreme conditions causing acute or chronic stress. They exhibit distinct functions and have been implicated in the pathogenesis of a number of diseases, including cancer. A causal relationship between HSP expression and immunogenicity has been demonstrated in murine and human tumors and is also associated with the immune response. In order to investigate the correlation of HSP expression and their immunogenic potential in renal cell carcinoma (RCC), we here analyzed (i) the protein expression profile of various members of the HSP family in untreated and interferon (IFN)-gamma treated RCC cell lines as well as normal kidney epithelium, and (ii) the anti-heat shock protein reactivity in sera derived from RCC patients and healthy controls using proteomics-based techniques. A heterogeneous expression pattern of members of the HSP families was demonstrated in RCC cell lines and in cells representing normal renal epithelium. In some cases the expression rate is moderately altered by IFN-gamma treatment. In addition, a distinct anti-heat shock protein reactivity could be detected in autologous and allogeneic sera from RCC patients and healthy controls. These data suggest that HSP play a role in the immunogenicity of RCC and thus might be used for the design of immunization strategies to induce a potent antitumor response in this disease.

Molecular characterization of a calcium binding translationally controlled tumor protein homologue from the filarial parasites Brugia malayi and Wuchereria bancrofti

We have cloned homologues of the mammalian translationally controlled tumor protein (TCTP) from the human filarial parasites Wuchereria bancrofti and Brugia malayi. TCTP genes from B. malayi and W. bancrofti were expressed in a T7 promoter vector as histidine tagged fusion proteins. Both the recombinant B. malayi TCTP (rBm-TCTP) and recombinant W. bancrofti TCTP (rWb-TCTP) have a molecular mass of approximately 28 kDa with the histidine tag. Sequence analyses showed that there is a 98% similarity between the two filarial TCTPs at amino acid levels and are immunologically cross-reactive. Analysis of soluble proteins from various lifecycle stages of B. malayi suggested that the expression of Bm-TCTP might be differentially regulated and occurs in multimeric form. Recombinant TCTP were found to form multimers in solution under non-reducing conditions. The tendency for filarial TCTPs to become multimers was predicted by the presence of the Lupas coiled coil structure in their sequence. Despite the absence of a signal sequence, Bm-TCTP is present abundantly in the excretory/secretions (ES) of microfilariae. Characterization studies showed that both Bm- and Wb-TCTPs are calcium-binding proteins and have histamine-releasing function in vitro. When injected intraperitoneally both the filarial TCTPs induced inflammatory infiltration of eosinophils into the peritoneal cavity of mice suggesting that the filarial TCTPs may have a role in the allergic inflammatory responses associated with filarial infections.

Thioredoxin post-transcriptional regulation by H19 provides a new function to mRNA-like non-coding RNA

Classically, the functional product of coding genes is a protein whose synthesis is directed by an mRNA-template. However, in the last few years several genes yielding an mRNA-like non-coding RNA as a functional product have been identified. In most cases these transcripts are synthesized by the RNA polymerase II, capped, spliced and polyadenylated, like classical mRNA. These latter have non-conserved open reading frames and seem to be untranslated. Consequently, it has been proposed and admitted that these genes act at the RNA level, and are so-called 'riboregulators'. H19 belongs to this class of gene and its role remains a matter of debate: for some authors it is an oncogene, for others a tumour suppressor. Here, we demonstrate, using a proteomic approach, that an H19 overexpression in human cancerous mammary epithelial cells stably transfected with genomic DNA containing the entire H19 gene is responsible for positively regulating at the post-transcriptional level the thioredoxin, a key protein of the cellular redox metabolism. Interestingly, this protein accumulates in many cancerous tissues, such as breast carcinomas in which we have also demonstrated an overexpression of the H19 gene.

Expression of inducible Hsp70 enhances the proliferation of MCF-7 breast cancer cells and protects against the cytotoxic effects of hyperthermia

Heat shock proteins (Hsps) are ubiquitous proteins that are induced following exposure to sublethal heat shock, are highly conserved during evolution, and protect cells from damage through their function as molecular chaperones. Some cancers demonstrate elevated levels of Hsp70, and their expression has been associated with cell proliferation, disease prognosis, and resistance to chemotherapy. In this study, we developed a tetracycline-regulated gene expression system to determine the specific effects of inducible Hsp70 on cell growth and protection against hyperthermia in MCF-7 breast cancer cells. MCF-7 cells expressing high levels of Hsp70 demonstrated a significantly faster doubling time (39 hours) compared with nonoverexpressing control cells (54 hours). The effect of elevated Hsp70 on cell proliferation was characterized further by 5-bromo-2'deoxyuridine labeling, which demonstrated a higher number of second and third division metaphases in cells at 42 and 69 hours, respectively. Estimates based on cell cycle analysis and mean doubling time indicated that Hsp70 may be exerting its growth-stimulating effect on MCF-7 cells primarily by shortening of the G0/G1 and S phases of the cell cycle. In addition to the effects on cell growth, we found that elevated levels of Hsp70 were sufficient to confer a significant level of protection against heat in MCF-7 cells. The results of this study support existing evidence linking Hsp70 expression with cell growth and cytoprotection in human cancer cells.

Spot the differences: proteomics in cancer research

Separation of thousands of cellular proteins by two-dimensional electrophoresis allows the detailed comparison of proteins from normal and diseased tissue. Mass spectrometry provides a fast and reliable way of characterising proteins of interest, particularly when the gene sequence of the source organism is known. The availability of the human genome sequence has opened up the possibility of identifying protein differences between normal and diseased tissue, thus providing the opportunity to search for tumour markers or for therapeutic targets. This new technology will give much-needed insight into the molecular mechanisms of tumour development and progression.