Shen Hu

Salivary Proteomics for Oral Cancer Biomarker Discovery

Purpose: This study aims to explore the presence of informative protein biomarkers in the human saliva proteome and to evaluate their potential for detection of oral squamous cell carcinoma (OSCC). Experimental Design: Whole saliva samples were collected from patients (n = 64) with OSCC and matched healthy subjects (n = 64). The proteins in pooled whole saliva samples of patients with OSCC (n = 16) and matched healthy subjects (n = 16) were profiled using shotgun proteomics based on C4 reversed-phase liquid chromatography for prefractionation, capillary reversed-phase liquid chromatography with quadruple time-of-flight mass spectrometry, and Mascot sequence database searching. Immunoassays were used for validation of the candidate biomarkers on a new group of OSCC (n = 48) and matched healthy subjects (n = 48). Receiver operating characteristic analysis was exploited to evaluate the diagnostic value of discovered candidate biomarkers for OSCC. Results: Subtractive proteomics revealed several salivary proteins at differential levels between the OSCC patients and matched control subjects. Five candidate biomarkers were successfully validated using immunoassays on an independent set of OSCC patients and matched healthy subjects. The combination of these candidate biomarkers yielded a receiver operating characteristic value of 93%, sensitivity of 90%, and specificity of 83% in detecting OSCC. Conclusion: Patient-based saliva proteomics is a promising approach to searching for OSCC biomarkers. The discovery of these new targets may lead to a simple clinical tool for the noninvasive diagnosis of oral cancer. Long-term longitudinal studies with large populations of individuals with oral cancer and those who are at high risk of developing oral cancer are needed to validate these potential biomarkers.

The Proteomes of Human Parotid and Submandibular/Sublingual Gland Salivas Collected as the Ductal Secretions

Saliva is a body fluid with important functions in oral and general health. A consortium of three research groups catalogued the proteins in human saliva collected as the ductal secretions: 1166 identifications--914 in parotid and 917 in submandibular/sublingual saliva--were made. The results showed that a high proportion of proteins that are found in plasma and/or tears are also present in saliva along with unique components. The proteins identified are involved in numerous molecular processes ranging from structural functions to enzymatic/catalytic activities. As expected, the majority mapped to the extracellular and secretory compartments. An immunoblot approach was used to validate the presence in saliva of a subset of the proteins identified by mass spectrometric approaches. These experiments focused on novel constituents and proteins for which the peptide evidence was relatively weak. Ultimately, information derived from the work reported here and related published studies can be used to translate blood-based clinical laboratory tests into a format that utilizes saliva. Additionally, a catalogue of the salivary proteome of healthy individuals allows future analyses of salivary samples from individuals with oral and systemic diseases, with the goal of identifying biomarkers with diagnostic and/or prognostic value for these conditions; another possibility is the discovery of therapeutic targets.

Electrochemical Sensor for Multiplex Biomarkers Detection

Purpose: Multiplexing assay of biomarkers at the point-of-care is an elusive goal for molecular diagnostics. Experimental Design: Here, we report an electrochemical (EC) sensor for oral cancer detection based on the simultaneous detection of two salivary biomarkers: interleukin (IL)-8 mRNA and IL-8 protein. Results: Under the multiplexing mode, the limit of detection of salivary IL-8 mRNA reaches to 3.9 fM and 7.4 pg/mL for IL-8 protein in saliva. Multiplex assay of these 2 biomarkers directly from 28 cancer and 28 matched control saliva samples shows significant difference between the two groups. From the receiver operating characteristic analysis, the EC sensor yields around 90% sensitivity and specificity for both IL-8 mRNA and IL-8 protein, which are very close to the data measured by traditional assays (ELISA and PCR) with the same group of saliva. Combined IL-8 mRNA and protein show better AUC compared with single biomarker. Conclusions: We show, for the first time, concurrently multiplexing detection of salivary mRNA and protein biomarkers using point-of-care EC sensor.

Human Saliva Proteome Analysis

Abstract:  Human saliva contains proteins that can be informative for disease detection and surveillance of oral health. Comprehensive analysis and identification of the proteomic content in human whole and ductal saliva is a necessary first step toward the discovery of saliva protein markers for human disease detection. The article will review the recent advances in human saliva proteome analysis, including the efforts of the UCLA saliva proteome consortium funded by the National Institute of Dental and Craniofacial Research (NIDCR). We aim to summarize the proteomics technologies currently used for global analysis of saliva proteins and to elaborate on the application of saliva proteomics to discovery of disease biomarkers, in particular for oral cancer and Sjögrens syndrome, and discuss some of the critical challenges and perspectives for this emerging field. The impact of human saliva proteome analysis in the search for clinically relevant disease biomarkers will be realized through advances made using proteomics technologies.

Prevalidation of Salivary Biomarkers for Oral Cancer Detection

Background: Oral cancer is the sixth most common cancer with a 5-year survival rate of approximately 60%. Presently, there are no scientifically credible early detection techniques beyond conventional clinical oral examination. The goal of this study is to validate whether the seven mRNAs and three proteins previously reported as biomarkers are capable of discriminating patients with oral squamous cell carcinomas (OSCC) from healthy subjects in independent cohorts and by a National Cancer Institute (NCI)-Early Detection Research Network (EDRN)-Biomarker Reference Laboratory (BRL). Methods: Three hundred and ninety-five subjects from five independent cohorts based on case controlled design were investigated by two independent laboratories, University of California, Los Angeles (Los Angeles, CA) discovery laboratory and NCI-EDRN-BRL. Results: Expression of all seven mRNA and three protein markers was increased in OSCC versus controls in all five cohorts. With respect to individual marker performance across the five cohorts, the increase in interleukin (IL)-8 and subcutaneous adipose tissue (SAT) was statistically significant and they remained top performers across different cohorts in terms of sensitivity and specificity. A previously identified multiple marker model showed an area under the receiver operating characteristic (ROC) curve for prediction of OSCC status ranging from 0.74 to 0.86 across the cohorts. Conclusions: The validation of these biomarkers showed their feasibility in the discrimination of OSCCs from healthy controls. Established assay technologies are robust enough to perform independently. Individual cutoff values for each of these markers and for the combined predictive model need to be further defined in large clinical studies. Impact: Salivary proteomic and transcriptomic biomarkers can discriminate oral cancer from control subjects. Cancer Epidemiol Biomarkers Prev; 21(4); 664–72. ©2012 AACR.

Fully Automated Two-dimensional Capillary Electrophoresis for High Sensitivity Protein Analysis

We report a system for automated protein analysis. In the system, proteins are labeled with the fluorogenic reagent 3-(2-furoyl)quinoline-2-carboxaldehyde, which reacts with lysine residues and creates a highly fluorescent product. These labeled proteins are analyzed by submicellar capillary electrophoresis at pH 7.5 to perform a first dimension separation. Once the first components migrate from the capillary, a fraction is transferred to a second dimension capillary, where electrophoresis is performed at pH 11.1 to further separate the proteins. Laser-induced fluorescence is used as an ultrasensitive detector of the separated proteins. Successive fractions are transferred from the first dimension capillary to the second dimension capillary for further separation to generate, in serial fashion, a two-dimensional electropherogram. The transfer of fractions is computer-controlled; there is no operator intervention once the sample has been injected. Zeptomoles of labeled proteins are detected, providing exquisite sensitivity.

Human saliva proteome analysis and disease biomarker discovery

Human saliva is an attractive body fluid for disease diagnosis and prognosis because saliva testing is simple, safe, low-cost and noninvasive. Comprehensive analysis and identification of the proteomic content in human whole and ductal saliva will not only contribute to the understanding of oral health and disease pathogenesis, but also form a foundation for the discovery of saliva protein biomarkers for human disease detection. In this article, we have summarized the proteomic technologies for comprehensive identification of proteins in human whole and ductal saliva. We have also discussed potential quantitative proteomic approaches to the discovery of saliva protein biomarkers for human oral and systemic diseases. With the fast development of mass spectrometry and proteomic technologies, we are enthusiastic that saliva protein biomarkers will be developed for clinical diagnosis and prognosis of human diseases in the future.

Multiplexed immunobead-based assay for detection of oral cancer protein biomarkers in saliva.

OBJECTIVE For clinical applications of biomarkers, there is a need for multiplex assays using high throughput platforms. The objective of this study was to determine the efficacy of Luminex Multianalyte Profiling (xMAP) technology for measurement of salivary proteins and to evaluate whether multiplex assays are as effective as single-plex assays and enzyme-linked immunosorbent assay (ELISA). RESULTS The average levels of interleukin-8 (IL-8) from the single-plex assay were 3313.2 +/- 3759.8 pg ml(-1) [oral squamous cell carcinoma (OSCC), n = 20] and 1061.7 +/- 1978.8 pg ml(-1) (control, n = 20). The IL-1beta average levels from the single-plex assay were 945.2 +/- 1134.8 pg ml(-1) (OSCC, n = 20) and 314.2 +/- 444.8 pg ml(-1) (control, n = 20). The average levels of IL-8 from the multiplex assay were 2834.9 +/- 3385.6 pg ml(-1) (OSCC, n = 20) and 947.3 +/- 2036.8 pg ml(-1) (control, n = 20). The IL-1beta average levels from the multiplex assay were 1013.5 +/- 1221.1 pg ml(-1) (OSCC, n = 20) and 376.3 +/- 576.3 pg ml(-1) (control, n = 20). The correlation coefficient between Luminex and ELISA assay for IL-8 (n = 19) and IL-1beta (n = 19) was 0.91 and 0.84, respectively. CONCLUSION Luminex xMAP single-plex and multiplex assays are as effective as ELISA assays for quantification of proteins in saliva. Both IL-8 and IL-1beta were expressed at significantly higher levels in OSCC subjects than in the matched healthy control subjects.

Preclinical validation of salivary biomarkers for primary Sjögren’s syndrome

Sjögrens syndrome (SS) is a systemic autoimmune disease with a variety of presenting symptoms that may delay its diagnosis. We previously discovered a number of candidate salivary biomarkers for primary SS using both mass spectrometry and expression microarray analysis. In the current study, we aimed to verify these candidate biomarkers in independent patient populations and to evaluate their predictive values for primary SS detection.

Human Saliva Proteome and Transcriptome

This paper tests the hypothesis that salivary proteins and their counterpart mRNAs co-exist in human whole saliva. Global profiling of human saliva proteomes and transcriptomes by mass spectrometry (MS) and expression microarray technologies, respectively, revealed many similarities between saliva proteins and mRNAs. Of the function-known proteins identified in saliva, from 61 to 70% were also found present as mRNA transcripts. For genes not detected at both protein and mRNA levels, we made further efforts to determine if the counterpart is present. Of 19 selected genes detected only at the protein level, the mRNAs of 13 (68%) genes were found in saliva by RT-PCR. In contrast, of many mRNAs detected only by microarrays, their protein products were found in saliva, as reported previously by other investigators. The saliva transcriptome may provide preliminary insights into the boundary of the saliva proteome.