Proteomic analysis of saliva for cancer diagnosis

Functionalized optical fiber ball-shaped biosensor for label-free, low-limit detection of IL-8 protein

Detection of biomarkers for tracking disease progression is becoming increasingly important in biomedicine. Using saliva as a diagnostic sample appears to be a safe, cost-effective, and non-invasive approach. Salivary interleukin-8 levels demonstrate specific changes associated with diseases such as obstructive pulmonary disease, squamous cell carcinoma, oral cancer, and breast cancer. Traditional protein detection methods, such as enzyme-linked immunosorbent assay (ELISA), mass spectrometry, and Western blot are often expensive, complex, and time-consuming. In this study, an optical fiber-based biosensor was developed to detect salivary IL-8 protein in a label-free manner. The biosensor was able to achieve an ultra-low limit detection of 0.91 fM. Moreover, the tested concentration range was wide: from 273 aM to 59 fM. As a proof-of-concept for detecting the protein in real clinical samples, the detection was carried out in artificial saliva. It was possible to achieve high sensitivity for the target protein and minimal signal alterations for the control proteins.

Circulating Proteins as Diagnostic Markers in Gastric Cancer

Gastric cancer (GC) is a highly malignant disease affecting humans worldwide and has a poor prognosis. Most GC cases are detected at advanced stages due to the cancer lacking early detectable symptoms. Therefore, there is great interest in improving early diagnosis by implementing targeted prevention strategies. Markers are necessary for early detection and to guide clinicians to the best personalized treatment. The current semi-invasive endoscopic methods to detect GC are invasive, costly, and time-consuming. Recent advances in proteomics technologies have enabled the screening of many samples and the detection of novel biomarkers and disease-related signature signaling networks. These biomarkers include circulating proteins from different fluids (e.g., plasma, serum, urine, and saliva) and extracellular vesicles. We review relevant published studies on circulating protein biomarkers in GC and detail their application as potential biomarkers for GC diagnosis. Identifying highly sensitive and highly specific diagnostic markers for GC may improve patient survival rates and contribute to advancing precision/personalized medicine.

Advances in the Diagnosis, Monitoring, and Progression of Oral Cancer through Saliva: An Update

The early detection of cancer, and in particular oral cancer, has been a priority objective of study in recent years. Saliva has been proposed as an easy-to-obtain means of providing the necessary information to diagnose malignant lesions in the oral cavity, since it can be obtained very easily and completely noninvasively. There are a number of molecules, known as biomarkers, which may be involved in the malignant transformation of oral lesions, and which have different natures. The involvement of proteins (“proteomics”), metabolites (“metabolomics”), and even certain genes in the structural changes of altered tissue has been investigated in order to establish validated parameters for the early diagnosis of oral cancer. In addition, the development of new analytical assay methods that can reduce costs and obtain better results in terms of sensitivity and specificity has been a key point in recent research in this field. Even though there are numerous biomarkers with results showing high sensitivity and specificity, there is still a need for more studies, with a larger sample and with analytical methods that can constitute a real advance in time and cost. Although salivary biomarkers are a promising new diagnostic tool for oral cancer, for the moment they do not replace biopsy as the “gold standard”.

Updates and Original Case Studies Focused on the NMR-Linked Metabolomics Analysis of Human Oral Fluids Part II: Applications to the Diagnosis and Prognostic Monitoring of Oral and Systemic Cancers

Human saliva offers many advantages over other biofluids regarding its use and value as a bioanalytical medium for the identification and prognostic monitoring of human diseases, mainly because its collection is largely non-invasive, is relatively cheap, and does not require any major clinical supervision, nor supervisory input. Indeed, participants donating this biofluid for such purposes, including the identification, validation and quantification of surrogate biomarkers, may easily self-collect such samples in their homes following the provision of full collection details to them by researchers. In this report, the authors have focused on the applications of metabolomics technologies to the diagnosis and progressive severity monitoring of human cancer conditions, firstly oral cancers (e.g., oral cavity squamous cell carcinoma), and secondly extra-oral (systemic) cancers such as lung, breast and prostate cancers. For each publication reviewed, the authors provide a detailed evaluation and critical appraisal of the experimental design, sample size, ease of sample collection (usually but not exclusively as whole mouth saliva (WMS)), their transport, length of storage and preparation for analysis. Moreover, recommended protocols for the optimisation of NMR pulse sequences for analysis, along with the application of methods and techniques for verifying and resonance assignments and validating the quantification of biomolecules responsible, are critically considered. In view of the authors’ specialisms and research interests, the majority of these investigations were conducted using NMR-based metabolomics techniques. The extension of these studies to determinations of metabolic pathways which have been pathologically disturbed in these diseases is also assessed here and reviewed. Where available, data for the monitoring of patients’ responses to chemotherapeutic treatments, and in one case, radiotherapy, are also evaluated herein. Additionally, a novel case study featured evaluates the molecular nature, levels and diagnostic potential of ¹H NMR-detectable salivary ‘acute-phase’ glycoprotein carbohydrate side chains, and/or their monomeric saccharide derivatives, as biomarkers for cancer and inflammatory conditions.

Salivary Proteome Profile of Women during Fertile Phase of Menstrual Cycle as Characterized by Mass Spectrometry

Objectives:

Ovulation is such a critical physiological process that its noninvasive detection based on salivary constituents has several advantages in humans. Hence, the present study is proposed to identify the ovulatory-specific proteins in saliva in order to detect ovulation phase.

Materials and Methods:

Samples were collected from women volunteers. The procedure adopted was approved by the Institutional Human Ethical Committee (DM/2014/101/38), Bharathidasan University. The saliva samples were collected from thirty healthy female volunteers, with a prior written consent. One-way analysis of variance was used to calculate protein concentration and band intensity using SPSS 16 software (SPSS Inc., Cary, NC, USA). The salivary protein expression pattern during different phases of menstrual cycle was analyzed using gel-based high resolution-liquid chromatography-mass spectrometry/mass spectrometry and matrix-assisted laser desorption ionization-time of flight/time of flight. Further, bioinformatics tools were adopted to annotate the proteins identified at various phases of menstrual cycle.

Results:

As many as 530 proteins showed up in the saliva during ovulatory phase, whereas there were only 251 proteins identified during postovulatory phase. The functional annotation of salivary proteins revealed that the proteins got assigned to the class of “extracellular proteins” which are concerned with regulatory functions. The 16 unique and/or differentially expressed protein spots appeared during ovulatory phase, among which Cystatin-S, Prolactin-inducible protein, Cystatin-A, Cystatin-SN, BPI fold-containing family A member 2, Alpha-tubulin N-acetyltransferase 1, Carbonic anhydrase-6, Protein LEG1 homolog, Hemoglobin subunit beta, and Pancreatic alpha-amylase were identified.

Conclusion:

Total salivary proteome profile has been listed with respect to various phases of menstrual cycle. Among the protein listed, Cystatin-S offers a biomarker protein and/or indicator of ovulatory phase. However, extensive validation is required before arriving to a candidate bio-marker protein.

Validation of Salivary Markers, IL-1β, IL-8 and Lgals3bp for Detection of Oral Squamous Cell Carcinoma in an Indian Population

Early detection and easier follow-up of oral squamous cell carcinoma (OSCC) would significantly improve the morbidity and mortality associated with it. With newer technologies, it has become possible to validate cancer biomarkers in saliva with high sensitivity and specificity. There is however a need to further validate these biomarkers in cohorts of different ethnic groups. Our objective was to validate previously evaluated salivary biomarkers in Indian population. The study enrolled 117 patients. These were grouped into subcatergories of 31 early (TNMstage I-II) and 27 late-stage OSCC (TNM stage III-IV), 30 PMOD and 29 post-treatment patients. There were 42 control subjects. We evaluated 3 protein markers, IL-1β, IL-8 and LGALS3BP using ELISA, from unstimulated saliva samples. Statistical analysis was done to calculate p-value, ROC, AUC, sensitivity, and specificity. Protein markers IL-1β and IL-8 were significantly elevated (p < 0.05) in OSCC patients. Though the markers could not discriminate PMOD and post-treatment subjects from controls, they proved to be significantly discriminatory between OSCC and controls. Both these markers were especially strong discriminators of late stage OSCC (stage III-IV). IL-1β had the most statistically significant discriminative power (AUC = 0.9017) in late-stage OSCC followed by IL-8 (AUC = 0.7619). Although LGALS3BP was not found to be significantly elevated in late stage OSCC patients, but it was a significant discriminator of early stage OSCC (stage I-II) with p-value = 0.0008 and AUC = 0.7296. These salivary biomarkers have been discovered and validated in other ethnic groups earlier. Hence, the fact that these markers were discriminatory in Indian population too, strengthens the possibility of using these salivary biomarkers as screening tools in different ethnic cohorts. Such trials would potentiate use of a non-invasive tool, like saliva for diagnosis and follow-up of oral cancer.

Estimation of salivary and serum basic fibroblast growth factor in treated and untreated patients with oral squamous cell carcinoma

OBJECTIVE

The purpose of this study was to evaluate salivary and serum basic fibroblast growth factor (bFGF) level in OSCC patients to provide a reliable biomarker for the early detection, monitoring, and prognosis of OSCC patients.

MATERIALS AND METHODS

The study enrolled 90 subjects, equally grouped as recently diagnosed & untreated OSCC patients (Group I), treated OSCC without any recurrence (Group II) & as control (Group III). Enzyme-linked immunosorbent assay was employed to measure bFGF concentrations in saliva and serum samples of all three groups. The results were tabulated and analyzed statistically.

RESULTS

Group I showed high-level of bFGF expression profile in saliva (8.80 ± 1.26 pg/ml) whereas the levels of bFGF in group II (2.69 ± 0.17 pg/ml) and Group III (3.17 ± 0.43 pg/ml) are significantly lower than group I. Serum bFGF levels were also high in group I (6.33 ± 0.81 pg/ml) and decreased significantly in group II (3.52 ± 0.45 pg/ml) however, the control group showed elevated range of levels (7.63 ± 0.88 pg/ml).

CONCLUSIONS

This study demonstrates the reliability of salivary bFGF marker as diagnostic as well as prognostic marker. Serum bFGF could also be used as prognostic marker only in Oral Squamous cell carcinoma patients.

Role of Salivary Biomarkers in Oral Cancer Detection

Oral cancers are the sixth most frequent cancer with a high mortality rate. Oral squamous cell carcinoma accounts for more than 90% of all oral cancers. Standard methods used to detect oral cancers remain comprehensive clinical examination, expensive biochemical investigations, and invasive biopsy. The identification of biomarkers from biological fluids (blood, urine, saliva) has the potential of early diagnosis. The use of saliva for early cancer detection in the search for new clinical markers is a promising approach because of its noninvasive sampling and easy collection methods. Human whole-mouth saliva contains proteins, peptides, electrolytes, organic, and inorganic salts secreted by salivary glands and complimentary contributions from gingival crevicular fluids and mucosal transudates. This diagnostic modality in the field of molecular biology has led to the discovery and potential of salivary biomarkers for the detection of oral cancers. Biomarkers are the molecular signatures and indicators of normal biological, pathological process, and pharmacological response to treatment hence may provide useful information for detection, diagnosis, and prognosis of the disease. Saliva's direct contact with oral cancer lesions makes it more specific and potentially sensitive screening tool, whereas more than 100 salivary biomarkers (DNA, RNA, mRNA, protein markers) have already been identified, including cytokines (IL-8, IL-1b, TNF-α), defensin-1, P53, Cyfra 21-1, tissue polypeptide-specific antigen, dual specificity phosphatase, spermidine/spermineN1-acetyltransferase , profilin, cofilin-1, transferrin, and many more. However, further research is still required for the reliability and validation of salivary biomarkers for clinical applications. This chapter provides the latest up-to-date list of known and emerging potential salivary biomarkers for early diagnosis of oral premalignant and cancerous lesions and monitoring of disease activity.

Protein-Protein Interaction Network Analysis of Salivary Proteomic Data in Oral Cancer Cases

Background:

Oral cancer is a frequently encountered neoplasm of the head and neck region, being the eight most common type of human malignancy worldwide. Despite improvement in its control, morbidity and mortality rates have improved little in the past decades. Therefore, prevention and/or early detection are a high priority. Proteomics with network analysis have emerged as a powerful tool to identify important proteins associated with cancer development and progression that can be potential targets for early diagnosis. In the present study, network- based protein- protein interactions (PPI) for oral cancer were identified and then analyzed for use as key proteins/potential biomarkers.

Material and Methods:

Gene expression data in articles which focused on saliva proteomics of oral cancer were collected and 74 candidate genes or proteins were extracted. Related protein networks of differentially expressed proteins were explored and visualized using cytoscape software. Further PPI analysis was performed by Molecular Complex Detection (MCODE) and BiNGO methods.

Results:

Network analysis of genes/proteins related to oral cancer identified kininogen-1, angiotensinogen, annexin A1, IL-8, IgG heavy variable and constant chains, CRP, collagen alpha-1 and fibronectin as 9 hub-bottleneck proteins. In addition, based on clustering with the MCODE tool, vitronectin, collagen alpha-2, IL-8 and integrin alpha-v were established as 5 distinct seed proteins.

Conclusion:

A hub-bottleneck protein panel may offer a potential /candidate biomarker pattern for diagnosis and treatment of oral cancer disease. Further investigation and validation of these proteins are warranted.

Salivary biomarkers for oral cancer and pre-cancer screening: a review

OBJECTIVE

The objective of the study was to conduct a systematic review of the literature assessing potential salivary biomarkers of oral cancer and pre-cancer and discuss emerging issues and challenges in relation to oral cancer and pre-cancer diagnostics.

MATERIALS AND METHODS

Search for articles involved the Medline, PubMed, and EMBASE. Specific terms were used from January 1995 to March 2017 by three experts.

RESULTS

This search collected 270 articles, of which 105 articles such as reviews, case reports, news, letter to editor, etc. in first round and 117 articles such as publications in other languages than English, non-human studies, etc. were excluded. The remaining 48 articles considered analyzing whole saliva as well as specific gland saliva. Thirty-one studies considered oral stimuli such as eating, drinking, and oral hygiene practices for varied periods of time prior to sample collection. The time of collection of saliva was morning in most studies, but the exact time of collection was not mentioned. Three studies showed to have evaluated the whole saliva without centrifugation. Two-dimensional gel electrophoresis and tandem mass spectrometry were the most commonly used methods. Most of the potential salivary biomarkers of oral cancer are salivary proteins.

CONCLUSION

Combination approach of salivary biomarkers could be used as screening tool to improve early detection and diagnostic precision of oral pre-cancer and cancer.

CLINICAL RELEVANCE

The current findings are of importance for clinicians and researchers to mitigate the challenges in salivary-based diagnosis of oral cancer and to evaluate reliable, specific, and sensitive salivary biomarkers for oral pre-cancer and cancer diagnosis.

A Review of Salivary Biomarker: A Tool for Early Oral Cancer Diagnosis

The oral squamous cell carcinoma (OSCC) is one of the most common epithelial malignancies with significant morbidity and mortality. Recent observations indicate that the clinical and histological appearance of oral mucosa may not truly depict the damage occurring at the genetic level. This phenotypic and genotypic disparity may account in part for the failure to establish effective screening and surveillance protocols, based on the traditional clinical and microscopic examination. The tumor markers are playing an increasingly important role in cancer detection and management. These laboratory-based tests are potentially useful in screening for early malignancy, aiding in cancer diagnosis, determining prognosis, surveillance following curative surgery for cancer, up-front predicting drug response or resistance, and monitoring therapy in advanced disease. A systematic review of the literature was performed based on the English titles listed in the PubMed, EBSCO, Cochrane, Science Direct, ISI web Science, and SciELO databases using the keywords. Abstracts and full-text articles were assessed. This article may help to identify the potential biomarkers for screening and the molecular pathology analysis in the high-risk patients with the OSCC.

Human Salivary Micro-RNA in Patients with Parotid Salivary Gland Neoplasms

BACKGROUND

Currently, clinical examination, ultrasound scanning (with or without fine needle aspiration cytology), preoperative CT-scan and MRI are available for the differential diagnosis of parotid gland swelling. A preliminary non-invasive salivary diagnostic tool may be helpful in the clinical decision making process. Altered salivary micro-RNA (miRNA) expression levels have been observed in saliva from patients with various cancers. Therefore, we investigated miRNA expression levels in saliva samples from patients with a parotid gland neoplasm using Human miRNA cards in comparison to controls.

RESULTS

In the discovery phase, eight miRNAs were identified having different expression levels in patients compared to controls. In the validation phase, the differences in miRNA expression levels between patients and controls were confirmed for seven out of eight discovered miRNAs (p < 0.001). A combination of two miRNAs yielded a receiver-operator-characteristics curve with an AUC of 0.94 (95% CI: 0.87-1.00; sensitivity 91%; specificity 86%). Validation of discovered miRNAs in segregated collected parotid saliva revealed that expression of these miRNAs differ between whole saliva and parotid saliva.

CONCLUSIONS

A two miRNA combination can predict the presence of a parotid gland neoplasm. Furthermore, this study suggested that the identified, patient-specific, salivary miRNAs were not derived from the parotid gland itself.

Neuroproteomics tools in clinical practice

Neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are characterized by neuronal impairment that leads to disease-specific changes in the neuronal proteins. The early diagnosis of these disorders is difficult, thus, the need for identifying, developing and using valid clinically applicable biomarkers that meet the criteria of precision, specificity and repeatability is very vital. The application of rapidly emerging technology such as mass spectrometry (MS) in proteomics has opened new avenues to accelerate biomarker discovery, both for diagnostic as well as for prognostic purposes. This review summarizes the most recent advances in the mass spectrometry-based neuroproteomics and analyses the current and future directions in the biomarker discovery for the neurodegenerative diseases. This article is part of a Special Issue entitled: Neuroproteomics: Applications in Neuroscience and Neurology.

Discovery and prevalidation of salivary extracellular microRNA biomarkers panel for the noninvasive detection of benign and malignant parotid gland tumors

PURPOSE

This study was conducted to explore the differences in salivary microRNA (miRNA) profiles between patients with malignant or benign parotid gland tumors as a potential preoperative diagnostic tool of tumors in the salivary glands.

EXPERIMENTAL DESIGN

Whole saliva samples from patients with malignant (n = 38) or benign (n = 29) parotid gland tumors were obtained from the Salivary Gland Tumor Biorepository (SGTB). After total RNA isolation, human miRNA cards were used for miRNA profiling. The differential miRNA expression was analyzed using two-sided Wilcoxon test. Quantitative real-time PCR (qRT-PCR) was used to validate selected miRNAs in an independent sample set. Receiver-operating characteristics curve and probability of malignancy was exploited to evaluate the diagnostic power of the validated miRNAs.

RESULTS

With miRNA profiling, 57 of 750 investigated miRNAs were differently expressed, of which 54 showed higher miRNA expression in samples from patients with malignant tumors than those from patients with benign tumors. Validating the expression in an independent sample set of 9 miRNAs revealed indeed higher expression of miRNAs in malignant samples compared with benign samples. The expression of 6 validated miRNAs was statistically significantly different between the two groups (P < 0.05). A four miRNA combination was able to discriminate between saliva samples from patients with malignant tumors from those of patients with benign parotid gland tumors (sensitivity 69%, specificity 95%).

CONCLUSIONS

Salivary miRNA profiles differ in saliva from patients with malignant from saliva from patients with a benign parotid gland tumor. These preliminary results are promising to develop a noninvasive diagnostic tool for diagnosing tumors in the salivary glands.

Salivary biomarkers--an update

Saliva is the most easily available and accessible body fluid, which makes it one of the most sought after tools in diagnostic pathology. Markers expressed in saliva can be used for diagnosis and concurrent patient follow-up of diseases ranging from hereditary disorders to infections, as well as malignancies and also analysis of therapeutic levels of drugs. The emergence of hand-held devices has made possible the elucidation of point-of-care methods and research in the field has resulted in the assimilation of knowledge useful for clinical applications.

CLINICAL RELEVANCE

This article describes some of the latest research in saliva diagnostics and provides some information on the various hand-held devices available.

Quantitative proteomics of parotid saliva in primary Sjögren's syndrome

The diagnosis of primary Sjögren's syndrome (pSS) is difficult due to the lack of specific laboratory and clinical tests. As an initial step for the global discovery of changes in the abundance of parotid salivary proteins in pSS, a pooled sample was compared to that from healthy control subjects by multidimensional protein identification technology (MudPIT). A total of 1246 proteins were identified by MudPIT. The abundance of 477 of these proteins did not change, 529 were only detected in either the pSS or HC sample, while 206 of these proteins were significantly upregulated ≥ twofold and 34 were downregulated ≤ 0.5. Ingenuity Pathway Analyses of differentially expressed proteins identified by MudPIT resulted in the identification of 100 significant pathways. The same samples were quantified in parallel using RP MS. Fifty-eight of 71 proteins identified by RP overlapped with MudPIT results. Five proteins were further analyzed by targeted label-free quantification to confirm the similar relative differential expression observed by RP and MudPIT approaches. The present study supports the use of MS for global discovery and validation of marker proteins for improved and early diagnosis of pSS.

High-Throughput Screening of Saliva for Early Detection of Oral Cancer: A Pilot Study

The success of tumour therapy depends considerably on early diagnosis. Therefore, we aimed to develop a widely available, cheap, non-invasive, high-throughput method suitable for screening high-risk populations, at least, for early signs of malignant transformation in the oral cavity. First, in order to identify suitable tumour marker candidates, we compared the protein patterns of five selected saliva samples obtained from healthy controls and tumour patients after electrophoretic separation, excised the bands that were consistently up-regulated in the tumour patients only, and performed matrix-assisted laser-desorption ionisation (MALDI)-time of flight (TOF) tandem mass spectrometry (MS/MS) analysis of the proteins in these bands after in-gel tryptic digestion. From the panel of proteins identified, we chose annexin 1 and peroxiredoxin 2 for further studies based on their presence in the saliva of all five oral cancer patients only. Then, we performed a homology search of protein databases using the primary sequence of each in silico tryptic fragment peptide of these two proteins as bait, and selected a unique peptide for each. Finally, we performed targeted MALDI-TOF MS peptide analysis in a blinded fashion on all samples obtained from 20 healthy controls and 22 tumour patients for the presence of these peptides. We found both peptides present in the saliva samples of all cancer patients only. Even though these tumour markers should be validated in a wider population, our results indicate that targeted MALDI-TOF MS analysis of unique peptides of putative saliva protein tumour biomarkers could be the method of choice for cost-efficient, high-throughput screening for the early detection of oral cancer.

A review on salivary genomics and proteomics biomarkers in oral cancer

Oral cancer has emerged as an alarming public health problem with increasing incidence and mortality rates all over the world. Therefore, the implementation of newer screening and early detection approaches are of utmost importance which could reduce the morbidity and mortality associated with this disease. Sensitive and specific biomarkers for oral cancer are likely to be most effective for screening, diagnosis, staging and follow-up for this dreaded malignancy. Unlike other deep cancers, oral cancer is located in oral cavity. Hence, the direct contact between saliva and oral cancer lesion makes the measurement of tumor markers in saliva an attractive alternative to serum and tissue testing. The DNA, RNA and protein molecules derived from the living cancer cells can be conveniently obtained from saliva. Thus, salivary biomarkers, a non-invasive alternative to serum and tissue-based biomarkers may be an effective modality for early diagnosis, prognostication and monitoring post therapy status. In the current post-genomic era, various technologies provide opportunities for high-throughput approaches to genomics and proteomics; which have been used to evaluate altered expressions of gene and protein targets in saliva of oral cancer patients. The emerging field of salivary biomarkers has great potentials to prove its clinical significance to combat oral cancer. Hence, we have reviewed importance of several salivary genomics and proteomics biomarkers for oral cancer.

Defining salivary biomarkers using mass spectrometry-based proteomics: a systematic review

Recent advancements in mass spectrometric proteomics provide a promising result in utilizing saliva to explore biomarkers for diagnostic purposes. However, the issues of specificity or redundancy of disease-associated salivary biomarkers have not been described. This systematic review was therefore aimed to define and summarize disease-related salivary biomarkers identified by mass spectrometry proteomics. Peer-reviewed articles published through July 2009 within three databases were reviewed. Out of 243 articles, 21 studies were selected in this systematic review with conditions including Sjögren's syndrome, squamous cell carcinoma, dental caries, diabetes, breast cancer, periodontitis, gastric cancer, systemic sclerosis, oral lichen planus, bleeding oral cavity, and graft-versus-host disease. The sample size ranged from 3-41 in both diseased and control subjects, with no consensus on sample collection protocol. One hundred eighty biomarkers were identified in total; 87 upregulated, 63 downregulated, and 30 varying based on disease. Except for Sjögren's syndrome, the majority of studies with the same disease produce inconsistent biomarkers. Larger sample size and standardization of sample collection/treatment protocol may improve future studies.

Comparative proteomic analysis of human oral fluids according to gender and age

BACKGROUND

Recently, interest in finding disease bio-markers in human body fluids including oral fluids (OF), mainly saliva has increased. However, the physiologic differences in salivary proteins according to gender and age should be explored to establish a clinical diagnostic tool.

OBJECTIVE

To compare OF protein expression according to gender and age, using proteomic approaches.

MATERIALS AND METHODS

Oral fluids from 27 healthy volunteers (14 males, 13 females) was collected and divided into three age-groups. OF proteins were separated by means of 2D-SDS-PAGE. A total of 51 proteins in 37 protein spots were identified by ESI-MS/MS.

RESULTS

Gender differences revealed six proteins with significant higher expression in females, including β-2-microglobulin and transferrin. Age differences revealed decrease in expression of eight proteins with aging among males and seven proteins differentially expressed with aging among females including prolactin inducible protein, Ig-k light chain, transferrin, and calgranulin-B.

CONCLUSION

Proteomic analysis of OF revealed differences in protein expression according to gender and age and therefore can highlight future use of this technique for diagnostic purposes in health and in disease.

Potential biomarkers in saliva for oral squamous cell carcinoma

Sensitive and reliable early diagnostic markers for oral squamous cell carcinoma (OSCC) remain unavailable. Early identification of recurrence for OSCC is also a challenge. Unlike the other deep cancers, OSCC is located in oral cavity. The DNA, RNA, and protein derived from the living cancer cells and inflammatory cells then can be conveniently obtained from saliva. High-throughput genomic and proteomic approaches have been carried out to identify the potential biomarkers in body fluids such as saliva and blood for diagnosis and prognosis of OSCC. This article reviewed the recently identified biomarkers from saliva for OSCC. In addition, the biomarkers which have been correlated with OSCC tumor malignancy by molecular pathology analysis are also described. Finally, the potential biomarkers that have been demonstrated to associate with the malignant OSCC may be used for salivary screening for high-risk patients are suggested. This article may help to identify the potential biomarkers for screening and the molecular pathology analysis for high-risk patients of OSCC. Effective screening to identify high-risk patients can allow the clinician to provide the appropriate treatment without delay and to reduce the recurrence of OSCC.

Salivary biomarkers for the detection of malignant tumors that are remote from the oral cavity

Proteomic analyses by mass spectrometry are propelling the field of medical diagnostics forward at unprecedented rates because of its ability reliably to identify proteins that are at the femtomole level in concentration. These advancements have also benefited biomarker research to the point where saliva is now recognized as an excellent diagnostic medium for the detection of malignant tumors that are remote from the oral cavity. Saliva is easy to collect and may provide diagnostic information about a variety of cancers. In particular, proof-of-principle has been demonstrated for salivary biomarker research. This article reviews the literature, discusses the theories associated with saliva-based tumor diagnostics, and presents the current research focused on the use of saliva as a diagnostic medium for the detection of cancer.

Breast cancer related proteins are present in saliva and are modulated secondary to ductal carcinoma in situ of the breast

OBJECTIVE

The objective of this study was to determine if protein-by-products secondary to cancer related oncogenes appear in the saliva of breast cancer patients.

METHODS

Three pooled (n = 10 subjects/pool) stimulated whole saliva specimens from women were analyzed. One pooled specimen was from healthy women, another pooled specimen from women diagnosed with a benign breast tumor and the other one pooled specimen was from women diagnosed with ductal carcinoma in situ (DCIS). Differential expression of proteins was measured by isotopically tagging proteins in the tumor groups and comparing them to the healthy control group. Experimentally, saliva from each of the pooled samples was trypsinized and the peptide digests labeled with the appropriate iTRAQ reagent. Labeled peptides from each of the digests were combined and analyzed by reverse phase (C18) capillary chromatography on an Applied Biosystems QStar LC-MS/MS mass spectrometer equipped with an LC-Packings HPLC.

RESULTS

The results of the salivary analyses in this population of patients yielded approximately 130 proteins in the saliva specimens. Forty-nine proteins were differentially expressed between the healthy control pool and the benign and cancer patient groups.

CONCLUSIONS

The study suggests that saliva is a fluid suffused with solubilized by-products of oncogenic expression and that these proteins may be modulated secondary to DCIS. Additionally, there may be salivary protein profiles that are unique to both DCIS and fibroadenoma tumors.

Salivary Genomics, Transcriptomics and Proteomics: The Emerging Concept of the Oral Ecosystem and their Use in the Early Diagnosis of Cancer and other Diseases

There is an increasingly growing interest world-wide for the genomics, transcriptomics and proteomics of saliva and the oral cavity, since they provide a non-invasive source of unprecedently rich genetic information. The complexity of oral systems biology goes much beyond the human genome, transcriptome and proteome revealed by oral mucosal cells, gingival crevicular fluid, and saliva, and includes the complexity of the oral microbiota, the symbiotic assembly of bacterial, fungal and other microbial flora in the oral cavity. In our review we summarize the recent information on oral genomics, transcriptomics and proteomics, of both human and microbial origin. We also give an introduction and practical advice on sample collection, handling and storage for analysis. Finally, we show the usefulness of salivary and oral genomics in early diagnosis of cancer, as well as in uncovering other systemic diseases, infections and oral disorders. We close the review by highlighting a number of possible exploratory pathways in this emerging, hot research field.

Proteomic analysis of the saliva: a clue for understanding primary from secondary Sjögren's syndrome?

The clinical entity of secondary Sjögren's syndrome (SS) is controversial and the relationship with primary SS and other systemic autoimmune diseases is still far from being completely understood. In the last few years, proteomic approaches have been applied with a growing interest in the search for diagnostic biomarkers for many rheumatic diseases and it is possible that, in the near future, proteomic analysis of human saliva could help in distinguishing also primary from secondary SS. This review summarizes the state of the art of proteomic analysis of human saliva in the diagnosis of connective diseases focusing its advantages, limits and future perspectives.