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[Identification of colorectal cancer using proteomic patterns in serum].

BACKGROUND & OBJECTIVE: At present there is no serological parameter with high sensitivity and specificity to diagnose colorectal cancer. This study aimed at establishing a serum protein fingerprinting technique coupled with a pattern-matching algorithm to distinguish colorectal cancer from benign colorectal diseases and healthy people. METHODS: Preliminary group and test group were both random selected serum samples, which each comprises 73 cases of colorectal cancer, 31 healthy people, and 16 cases of benign colorectal diseases. The sera of the test group was combined with the surface of the IMAC3 proteinchip. Then reading data of surface enhanced laser desorption/ionization- time of flight-mass spectrometry (SELDI-TOF-MS) was analyzed by Biomarker Wizard software and Biomarker pattern software to get a classification rule of tree, which is standard configuration that can distinguish the sera of colorectal cancer patients from the sera of benign colorectal disease patients and healthy people, and the standard was approved test validity by double-blindly in the test group. RESULTS: At the key M/Z values of 4 467 Da, 8 131 Da, 8 939 Da, 9 192 Da, 9 134 Da, 8 221 Da, 5 928 Da, 8 324 Da, 11 732 Da, protein contents of the three classes in preliminary group are obviously different by the software analysis. And the classification rule of tree was discovered, and corresponding correct ratio was 98.33% (118/120), corresponding sensitivity was 97.26% (71/73) and corresponding specificity was 100% (47/47); after double-blind examining the test group with that rule, the corresponding correct ratio was 96.77% (116/120),the corresponding sensitivity was 95.89% (70/73) and the corresponding specificity was 97.87%(46/47). CONCLUSION: Via comparative proteomics research in the sera of colorectal cancer patients and benign colorectal disease patients and healthy people, the group of protein was obviously different in pathological process in discovering colorectal cancer.

Algorithms↗

Overexpression of annexin 1 in pancreatic cancer and its clinical significance.

AIM: To investigate the expression of annexin I in pancreatic cancer and its relationship with the clinicopathologic factors, and to evaluate its potential clinical significance. METHODS: Annexin I expression was analyzed by Western blot and immunohistochemical staining in pancreatic adenocarcinoma and multi-tissue microarrays (MTAs). RESULTS: Western blot analysis showed that annexin I was overexpressed in 84.6% (11/13) pancreatic ductal adenocarcinomas. Immunohistochemistry analysis of pancreatic cancer in MTAs showed that annexin I protein was 71.4%(30/42) positive which was markedly increased compared with that in the tumor matched normal pancreas tissues 18.4%(7/38) (P<0.01). In the meantime, the high expression of annexin 1 was correlated with the poor differentiation of pancreatic adenocarcinoma. CONCLUSION: Annexin 1 overexpression is a frequent biological marker and correlates with the differentiation of pancreatic cancer during tumorigenesis.

Adenocarcinoma↗

Improving feature detection and analysis of surface-enhanced laser desorption/ionization-time of flight mass spectra.

Discovering valid biological information from surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) depends on clear experimental design, meticulous sample handling, and sophisticated data processing. Most published literature deals with the biological aspects of these experiments, or with computer-learning algorithms to locate sets of classifying biomarkers. The process of locating and measuring proteins across spectra has received less attention. This process should be tunable between sensitivity and false-discovery, and should guarantee that features are biologically meaningful in that they represent chemical species that can be identified and investigated. Existing feature detection in SELDI-TOF MS is not optimal for acquiring biologically relevant data. Most methods have so many user-defined settings that reproducibility and comparability among studies suffer considerably. To address these issues, we have developed an approach, called simultaneous spectrum analysis (SSA), which (i) locates proteins across spectra, (ii) measures their abundance, (iii) subtracts baseline, (iv) excludes irreproducible measurements, and (v) computes normalization factors for comparing spectra. SSA uses only two key parameters for feature detection and one parameter each for quality thresholds on spectra and peaks. The effectiveness of SSA is demonstrated by identifying proteins differentially expressed in SELDI-TOF spectra from plasma of wild-type and knockout mice for plasma glutathione peroxidase. Comparing analyses by SSA and CiphergenExpress Data Manager 2.1 finds similar results for large signal peaks, but SSA improves the number and quality of differences betweens groups among lower signal peaks. SSA is also less likely to introduce systematic bias when normalizing spectra.

Algorithms↗

High-resolution serum proteomic features for ovarian cancer detection.

Serum proteomic pattern diagnostics is an emerging paradigm employing low-resolution mass spectrometry (MS) to generate a set of biomarker classifiers. In the present study, we utilized a well-controlled ovarian cancer serum study set to compare the sensitivity and specificity of serum proteomic diagnostic patterns acquired using a high-resolution versus a low-resolution MS platform. In blinded testing sets, the high-resolution mass spectral data contained multiple diagnostic signatures that were superior to the low-resolution spectra in terms of sensitivity and specificity (P<0.00001) throughout the range of modeling conditions. Four mass spectral feature set patterns acquired from data obtained exclusively with the high-resolution mass spectrometer were 100% specific and sensitive in their diagnosis of serum samples as being acquired from either unaffected patients or those suffering from ovarian cancer. Important to the future of proteomic pattern diagnostics is the ability to recognize inferior spectra statistically, so that those resulting from a specific process error are recognized prior to their potentially incorrect (and damaging) diagnosis. To meet this need, we have developed a series of quality-assurance and in-process control procedures to (a) globally evaluate sources of sample variability, (b) identify outlying mass spectra, and (c) develop quality-control release specifications. From these quality-assurance and control (QA/QC) specifications, we identified 32 mass spectra out of the total 248 that showed statistically significant differences from the norm. Hence, 216 of the initial 248 high-resolution mass spectra were determined to be of high quality and were remodeled by pattern-recognition analysis. Again, we obtained four mass spectral feature set patterns that also exhibited 100% sensitivity and specificity in blinded validation tests (68/68 cancer: including 18/18 stage I, and 43/43 healthy). We conclude that (a) the use of high-resolution MS yields superior classification patterns as compared with those obtained with lower resolution instrumentation; (b) although the process error that we discovered did not have a deleterious impact on the present results obtained from proteomic pattern analysis, the major source of spectral variability emanated from mass spectral acquisition, and not bias at the clinical collection site; (c) this variability can be reduced and monitored through the use of QA/QC statistical procedures; (d) multiple and distinct proteomic patterns, comprising low molecular weight biomarkers, detected by high-resolution MS achieve accuracies surpassing individual biomarkers, warranting validation in a large clinical study.

Biomarkers, Tumor↗

Analysis of sequence specificities of DNA-binding proteins with protein binding microarrays.

DNA-binding proteins are important for various cellular processes, such as transcriptional regulation, recombination, replication, repair, and DNA modification. Of particular interest are transcription factors (TFs), since through interactions with their DNA binding sites, they modulate gene expression in a manner required for normal cellular growth and differentiation, and also for response to environmental stimuli. To date, the DNA-binding specificities of most DNA-binding proteins remain unknown, as earlier technologies aimed at characterizing DNA-protein interactions have been laborious and not highly scalable. New DNA microarray-based technology, termed protein binding microarrays (PBMs), has been developed that allows rapid, high-throughput characterization of in vitro DNA binding site sequence specificities of TFs or of any DNA binding protein. DNA binding site data from PBMs can be used to predict what genes are regulated by a given TF, what the functions are of a given TF and its predicted target genes, and how that TF may fit into the transcriptional regulatory networks of the cell.

Animals↗

Influence of hormone replacement therapy on proteomic pattern in serum of postmenopausal women.

OBJECTIVES: Proteomics approaches to cardiovascular biology and disease hold the promise of identifying specific proteins and peptides or modification thereof to assist in the identification of novel biomarkers. METHOD: By using surface-enhanced laser desorption and ionization time of flight mass spectroscopy (SELDI-TOF-MS) serum peptide and protein patterns were detected enabling to discriminate between postmenopausal women with and without hormone replacement therapy (HRT). RESULTS: Serum of 13 HRT and 27 control subjects was analyzed and 42 peptides and proteins could be tentatively identified based on their molecular weight and binding characteristics on the chip surface. By using decision tree-based Biomarker Patternstrade mark Software classification and regression analysis a discriminatory function was developed allowing to distinguish between HRT women and controls correctly and, thus, yielding a sensitivity of 100% and a specificity of 100%. The results show that peptide and protein patterns have the potential to deliver novel biomarkers as well as pinpointing targets for improved treatment. The biomarkers obtained represent a promising tool to discriminate between HRT users and non-users. CONCLUSION: According to a tentative identification of the markers by their molecular weight and binding characteristics, most of them appear to be part of the inflammation induced acute-phase response.

Blood Proteins↗

Reverse-phase protein microarrays for tissue-based analysis.

The deciphering of the human genome has elucidated our biological structural design and has generated insights into disease development and pathogenesis. At the same time, knowledge of genetic changes during disease processes has demonstrated the need to move beyond genomics towards proteomics and a systems biology approach to science. Analyzing the proteome comprises more than just a numeration of proteins. In fact, it characterizes proteins within cells in the context of their functional status and interactions in their physiological micro- and macroenvironments. As dysregulated signaling often underpins most human diseases, an overarching goal of proteomics is to profile the working state of signaling pathways, to develop 'circuit maps' of normal and diseased protein networks and identify hyperactive, defective or inoperable transduction pathways. Reverse-phase protein microarrays represent a new technology that can generate a multiplex readout of dozens of phosphorylated events simultaneously to profile the state of a signaling pathway target even after the cell is lyzed and the contents denatured.

Animals↗

Urinary proteomic profiles distinguish between active and inactive lupus nephritis.

OBJECTIVES: Key aims of the treatment of lupus nephritis (LN) are to induce and maintain remission with minimal side effects. However, assessing ongoing renal inflammatory activity is poorly served by current diagnostic tests apart from renal biopsy, but frequent biopsies cannot be justified. Our long-term aim is to identify novel biomarkers from urinary protein profiles to improve diagnosis and monitoring of activity and response to therapy in LN. METHODS: We used surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify biomarkers able to discriminate between urine samples from patients with inactive (n= 49) and active (n= 26) LN. Discriminant function analysis was used to define the minimum number of proteins whose levels best distinguished between the two patient groups. Serial urines of six biopsied patients were studied prospectively, and multiple regression (MR) scores calculated. RESULTS: Proteins with masses of 3340 and 3980 distinguished active from inactive LN with 92% sensitivity and specificity of 92% each. The prospective study of the biopsied patients demonstrated that MR scores could predict both relapse and remission earlier than traditional clinical markers. CONCLUSIONS: SELDI-TOF MS identified potential biomarker profiles strongly associated with activity in LN. Identification of these proteins will allow us to devise specific assays to routinely monitor disease progression, and alter immunosuppressive drug regimens accordingly. These proteins may also play a critical role in the pathogenesis of glomerulonephritis, and could therefore provide targets for therapeutic intervention.

Adult↗

Evaluation of a novel, integrated approach using functionalized magnetic beads, bench-top MALDI-TOF-MS with prestructured sample supports, and pattern recognition software for profiling potential biomarkers in human plasma.

The advantage of using proteins and peptides as biomarkers is that they can be found readily in blood, urine, and other biological fluids. Such sample types are easily obtained and represent a potentially rich palette of biologically informative molecules. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) represents a key tool for rapidly interrogating such sample types. The goal of clinical proteomics is to harness the power of this tool for identifying novel, condition-specific protein fingerprints that may, in turn, lead to the elucidation and use of diseasespecific biomarkers that may be used to diagnose disease as well as to evaluate disease severity, disease progression, and intervention efficacy. Here we have evaluated a simple, affordable bench-top MALDI-TOF mass spectrometer to generate protein profiles from human plasma samples of asthma patients and healthy individuals. We achieve this profiling by using C8-functionalized magnetic beads that enrich a specific subset of plasma proteins based on their absorption by this resin. This step is followed by elution, transfer onto a prestructured sample support (AnchorChip technology), and analysis in a bench-top MALDI-TOF mass spectrometer (OmniFLEX) with AutoXecute acquisition control which enables automated operation with reproducible results. Resulting spectra are compiled and analyzed through the pattern recognition component of ClinProTools software. This approach in combination with ClinProTools software permits the investigator to rapidly scan for potential biomarker peptides/proteins in human plasma. The reproducibility of plasma profiles within and between days has been evaluated. The results show that the novel and facile approach with manual magnetic-bead sample preparation and a low-cost bench-top MALDI-TOF mass spectrometer is suitable for preliminary biomarker discovery studies.

Algorithms↗

Protein profiling of 3T3-L1 adipocyte differentiation and (tumor necrosis factor alpha-mediated) starvation.

The increased incidence of obesity and related disorders in Western societies requires a thorough understanding of the adipogenic process. Data at the protein level of this process are scarce. Therefore we performed a proteome analysis of differentiating and starving 3T3-L1 cells using two-dimensional gel electrophoresis combined with mass spectrometry. Effects of different starvation conditions were examined by subjecting 3T3-L1 adipocytes to caloric restriction, either in the absence or the presence of the lipolysis inducer tumor necrosis factor-alpha. Ninety-three differentially expressed proteins were found during differentiation and starvation of 3T3-L1 cells, 50 of which were identified. GenMAPP/MAPP-finder software revealed a non-reciprocal regulation of the glycolytic pathway during 3T3-L1 differentiation followed by starvation. Furthermore, proteins involved in growth regulation, cytoskeletal rearrangements and protein modification, 16 of which have not been described before in 3T3-L1 cells, were identified. In conclusion, our data provide valuable information for further understanding of the adipogenic process.

3T3-L1 Cells↗

Recent trends and advances in immunodiagnostics of solid tumors.

The development of new cancer immunodiagnostic tests measuring soluble markers can be divided along the lines of single analyte measurement versus multiplex analysis. In the measurement of single analytes, newly proposed test analytes still struggle with the same issues as their predecessors; namely, can the measurement of a single biomarker be sufficiently sensitive and specific for screening the general population? Probably the best example of this challenge is in the area of bladder cancer detection, where several newly identified markers are being clinically evaluated in multicenter trials. In order to surmount this hurdle, multiplex analysis has become an increasingly important research focus. By combining the statistical power of measuring many cancer-associated analytes, it is hoped that highly specific diagnostic tests can be developed that are suitable for screening the general population. Some of the most impressive data for multiplex cancer biomarker detection derive from a non-immunologic technique - mass spectroscopy. Multiplex analysis has also recently been applied to the measurement of serum antibodies to tumor-associated antigens. Recent data link the development of antibodies to tumor-associated antigens with the presence of solid tumors. This strategy is a departure from the more traditional assay format of measuring the antigens themselves, and is another promising emerging area of investigation for the early detection of solid tumors. Solid tumor analysis by quantitative immunohistochemical staining is another rapidly growing area of cancer immunodiagnosis. This field has become especially important in the context of pharmacodiagnostics - the coupling of cancer therapy to the outcome of a test measurement from a patient biopsy. Standardization and assay reproducibility appear to be the most significant challenges in this context. In summary, developments over the past several years give reason for excitement and optimism about the potential for cancer immunodiagnostics to meaningfully impact cancer patient survival. In this review we take a fresh look at the field of cancer immunodiagnostics, to identify these recent and emerging trends that may impact on clinical practice over the next few years.

Animals↗

A new compact disc format of high density array synthesis applied to peptide nucleic acids and in situ MALDI analysis.

A fully automated synthesizer was constructed and designed to perform high speed miniaturized syntheses of compound libraries using the SPOT technique. Utilizing magnetically controlled drop-on-demand ink jet nozzles, an r/phi array format of 2500 spots can be simultaneously dispensed from up to 24 separate reagent valves onto a rotating disc as the solid phase in less than three minutes. In addition, a complete wash station is on board allowing for fully programmable combinatorial syntheses without manual attention. A new carbon black/polypropylene composite solid phase disc was developed and tested for its functionalisation/loading, spot detection, durability and MALDI-TOF target capabilities. The carbon black/polypropylene composite was then successfully employed jointly as the solid phase in the syntheses of short peptide and PNA oligomers and as the target probe holder for MALDI-TOF measurement without transfer of the material. Several protocols for PNA syntheses were also investigated and an optimised PNA methodology for the carbon black/polypropylene composite is reported.

Amino Acid Sequence↗

Cancer immunomics: using autoantibody signatures in the early detection of prostate cancer.

Prostate cancer remains the most common malignancy among men and the second leading cause of cancer death of men in the United States. Although measurement of prostate-specific antigen (PSA) has led to earlier detection of many prostate cancers, new serum biomarkers are still needed to improve the accuracy of prostate cancer detection. Considerable evidence has shown that an immune response in the form of autoantibodies to various tumor antigens develops in many patients with cancer. By using phage-epitope microarray analysis, we were able to identify peptides expressed by prostate cancer tissue, which commonly induce formation of autoantibodies in the sera of patients with prostate cancer. Using a panel of 22 peptides, we were able to detect prostate cancer with a specificity of 88.2% and a sensitivity of 81.6%. These results were significantly better than PSA, especially among men with a PSA between 4 and 10 ng/ml. Measurement of the immune response to prostate cancer, as well as other malignancies, has the potential to improve significantly the detection of these cancers and possibly assist in the determination of prognosis.

Antigens, Neoplasm↗

Molecular profiling of hepatocellular carcinoma in mice with a chronic deficiency of hepatic s-adenosylmethionine: relevance in human liver diseases.

S-adenosylmethionine arises as a central molecule in the preservation of liver homeostasis as a chronic hepatic deficiency results in spontaneous development of steatohepatitis and hepatocellular carcinoma. In the present work, we have attempted a comprehensive analysis of proteins associated with hepatocarcinogenesis in MAT1A knock out mice using a combination of two-dimensional electrophoresis and mass spectrometry, to then apply the resulting information to identify hallmarks of human HCC. Our results suggest the existence of individual-specific factors that might condition the development of preneoplastic lesions. Proteomic analysis allowed the identification of 151 differential proteins in MAT1A-/- mice tumors. Among all differential proteins, 27 changed in at least 50% of the analyzed tumors, and some of these alterations were already detected months before the development of HCC in the KO liver. The expression level of genes coding for 13 of these proteins was markedly decreased in human HCC. Interestingly, seven of these genes were also found to be down-regulated in a pretumoral condition such as cirrhosis, while depletion of only one marker was assessed in less severe liver disorders.

Adult↗

Autoantibody signatures in prostate cancer.

BACKGROUND: New biomarkers, such as autoantibody signatures, may improve the early detection of prostate cancer. METHODS: With a phage-display library derived from prostate-cancer tissue, we developed and used phage protein microarrays to analyze serum samples from 119 patients with prostate cancer and 138 controls, with the samples equally divided into training and validation sets. A phage-peptide detector that was constructed from the training set was evaluated on an independent validation set of 128 serum samples (60 from patients with prostate cancer and 68 from controls). RESULTS: A 22-phage-peptide detector had 88.2 percent specificity (95 percent confidence interval, 0.78 to 0.95) and 81.6 percent sensitivity (95 percent confidence interval, 0.70 to 0.90) in discriminating between the group with prostate cancer and the control group. This panel of peptides performed better than did prostate-specific antigen (PSA) in distinguishing between the group with prostate cancer and the control group (area under the curve for the autoantibody signature, 0.93; 95 percent confidence interval, 0.88 to 0.97; area under the curve for PSA, 0.80; 95 percent confidence interval, 0.71 to 0.88). Logistic-regression analysis revealed that the phage-peptide panel provided additional discriminative power over PSA (P<0.001). Among the 22 phage peptides used as a detector, 4 were derived from in-frame, named coding sequences. The remaining phage peptides were generated from untranslated sequences. CONCLUSIONS: Autoantibodies against peptides derived from prostate-cancer tissue could be used as the basis for a screening test for prostate cancer.

Aged↗

Proteome-wide analysis of head and neck squamous cell carcinomas using laser-capture microdissection and tandem mass spectrometry.

Remarkable progress has been made to identify genes expressed in squamous cell carcinomas of the head and neck (HNSCC). However, limited information is available on their corresponding protein products, whose expression, post-translational modifications, and activity are ultimately responsible for the malignant behavior of this tumor type. We have combined laser-capture microdissection (LCM) with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify proteins expressed in histologically normal squamous epithelium and matching SCC. The protein fraction from approximately 10,000-15,000 normal and tumor cells was solubilized, digested with trypsin, and the resulting peptides were analyzed by LC-MS/MS. Database searching of the resulting sequence information identified 30-55 proteins per sample. Keratins were the most abundant proteins in both normal and tumor tissues. Among the proteins differentially expressed, keratin 13 was much lower in tumors, whereas heat-shock (Hsp) family members were highly expressed in neoplastic cells. Wnt-6 and Wnt-14 were identified in both normal and tumor tissues, respectively, and placental growth factor (PIGF) was detected only in tumors. Immunohistochemical analysis of HNSCC tissues revealed lack of keratin 13 in tumor tissues, and strong staining in normal epithelia, and high expression of Hsp90 in tumors. Our study, by combining LCM and proteomic technologies, underscores the advantages of this approach to investigate complex changes at the protein level in HNSCC, thus complementing existing and emerging genomic technologies. These efforts may likely result in the identification of new biomarkers for HNSCC that can be used to diagnose disease, predict susceptibility, and monitor progression in individual patients.

Aged↗

Targeting topoisomerase IIa in endometrial adenocarcinoma: a combined chromogenic in situ hybridization and immunohistochemistry study based on tissue microarrays.

Topoisomerase IIa is a nucleic enzyme that affects the topological structure of DNA and also is a target for chemotherapy (ie, anthracyclines). In this study, we coevaluated its protein expression with chromosome 17 and gene status. Using tissue microarrays, 40 cases of sporadic, primary endometrial adenocarcinomas, 5 cases of atypical hyperplasia, and 5 cases of benign hyperplasia were obtained and reembedded into two paraffin blocks with a core diameter of 1 mm. Immunohistochemistry combined with chromogenic in situ hybridization was performed in 2 and 5 microm sections, respectively. Finally using a semiautomated Image Analysis System, we evaluated the levels of Nuclear labeling index of topoisomerase IIa expression. Statistical analysis was performed by SPSS version 11.0 software. The results indicate that chromosome 17 instability (aneuploidy in 7/40 cases) and Topo IIa gene deregulation (amplification in 3/40 and deletion in 1/40 cases) are significant genetic events correlated with biologic behavior in endometrial adenocarcinoma. Because protein overexpression was observed in a significant proportion of the tumors (18/40), detection of the specific gene deregulation mechanism is a crucial process for application of targeted chemotherapies, which are characterized by different levels of cardiotoxicity and other serious effects.

Adenocarcinoma↗

Purification of novel UBAP1 protein and its decreased expression on nasopharyngeal carcinoma tissue microarray.

Recently, the UBAPl gene, a putative nasopharyngeal carcinoma (NPC) related gene, which is located at human chromosome 9p21-22 where loss of heterozygosity frequently occurs in NPC, was cloned. The present study aimed to explore the purification approach to UBAP1 protein and its expression pattern in NPC with tissue microarray. The full length coding sequence of UBAP1 was subcloned into a prokaryotic expression vector, pGEX-4T-2, and expressed in Escherichia coli as a GST-fusion protein. With modification of the purification method, GST-UBAP1 fusion protein achieved a high level of purity. The New Zealand rabbit was immunized with the purified fusion protein to prepare polyclonal antiserum following standard protocols. With this antiserum, high-throughput analysis of UBAP1 protein expression using immunohistochemistry was performed on self-made tissue microarrays consisting of 316 nasopharyngeal specimens from 148 NPC and 168 non-cancerous nasopharyngeal epithelia with different morphological features. Consequently, we found that there was a significant decrease in the percentage of positive expression in all NPC on protein levels for UBAP1 (23%), compared to that of the non-NPC (89%) (P<0.01). The result suggests that UBAP1 might be a potential effective diagnosis candidate for NPC and decreased expression of UBAP1 protein is a possible point of dysfunction along the pathogenesis pathway for NPC that may contribute to malignant transformation.

Animals↗