Bradley S. Henson

Salivary microRNA: Discovery, Characterization, and Clinical Utility for Oral Cancer Detection

Purpose: We have previously shown that a transcriptome is found in saliva and subpanels of these mRNAs can be used as oral cancer biomarkers. In this study, we measured the presence of microRNAs (miRNA) in saliva and determined their potential as an additional set of oral cancer biomarkers. Experimental Design: A total of 314 miRNAs were measured using reverse transcriptase-preamplification-quantitative PCR in 12 healthy controls. Degradation pattern of endogenous and exogenous saliva miRNAs were measured at room temperature over time. Selected miRNAs were validated in saliva of 50 oral squamous cell carcinoma patients and 50 healthy matched control subjects. Results: We detected ∼50 miRNAs in both the whole and supernatant saliva. Endogenous saliva miRNA degraded much slower compared with exogenous miRNA. Two miRNAs, miR-125a and miR-200a, were present in significantly lower levels (P < 0.05) in the saliva of oral squamous cell carcinoma patients than in control subjects. Conclusions: Both whole and supernatant saliva of healthy controls contained dozens of miRNAs, and similar to saliva mRNAs, these miRNAs are stable. Saliva miRNAs can be used for oral cancer detection. (Clin Cancer Res 2009;15(17):5473–7)

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.

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.

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.

The clinical value of salivary biomarkers for periodontal disease.

Periodontal disease is a chronic bacterial infection characterized by persistent inflammation, connective tissue breakdown, and alveolar bone destruction (3). It has been a great challenge in periodontology to determine biomarkers for screening and predicting the early onset of disease (prognostic tests) or evaluating the disease activity and the efficacy of therapy (diagnostic tests). Traditional diagnostic measures, such as periodontal pocket depth, attachment level, plaque index, bleeding on probing and radiographic assessment of alveolar bone loss, are informative to evaluate disease severity (83) but provide few useful determinants of disease activity (2, 29, 30, 61, 80). The presence of bleeding on probing is still the best disease activity predictor available, but it is not specific enough and thus reveals too many false positives. The absence of bleeding on probing on the other hand is a very precise negative predictor of disease activity (59, 60, 73). The identification of susceptible individuals or sites at risk from disease, and the diagnosis of active phases of periodontal disease, represent a challenge for both clinicians and oral health researchers. Indeed, the subjectivity and variability of definitions of the periodontitis phenotype in clinical studies are such that no universally accepted diagnostic criteria exist to define what a case of periodontitis is, thus making outcomes from different studies difficult to compare (11). It has long been established that a simple and non-invasive diagnostic tool that allows rapid screening, provides accurate predictive information and enables reliable evaluation of periodontal disease status would be of great value to both dentists and patients. Saliva is a secretion of the salivary and mucous glands and is of major importance in the maintenance of oral health (22). The fluid is readily accessible via a totally non-invasive collection method, and contains locally produced microbial and host response mediators. For the past two decades, saliva has been increasingly evaluated as a diagnostic fluid for detecting caries risk (12, 13, 62), periodontitis (18), oral cancer (63), breast cancer (104–107), salivary gland diseases (42) and systemic disorders such as hepatitis and the presence of human immunodeficiency virus (HIV) or hepatitis C virus (23, 39, 75, 123). The ease of collecting, handling and testing saliva has led to its use for determining hormone levels, including estradiol, progesterone and testosterone, dehydroepiandrosterone and cortisol (31). Numerous drugs are detectible in oral fluid, and can even be quantified in saliva as a viable substitute for testing in blood, and, as a result, salivary diagnostic technology is currently utilized to test for drugs of abuse, such as cocaine (50, 94), methamphetamines (44, 93) and opiates (20). Additionally, testing of saliva can also be used for therapeutic monitoring of drugs, such as digoxin (19, 108), methadone (17) and some anticonvulsants (34). The biochemical analysis of saliva is particularly important in dentistry. Estimation of the risk of disease onset and severity, monitoring of disease progression and evaluation of therapeutic efficacy for premalignant and malignant oropharyngeal lesions as well as infectious diseases of the oral cavity can be performed by analyzing an array of constituents within saliva. Although there is a large body of literature on gingival crevicular fluid biomarkers, this review limits itself to saliva analysis. Salivary constituents that have been studied as potential diagnostic biomarkers for periodontal disease mainly include locally produced proteins of host and bacterial origin (enzymes, immunoglobulins and cytokines), genetic ⁄ genomic biomarkers such as DNA and

Collection, Storage, and Processing of Saliva Samples for Downstream Molecular Applications

Saliva is an ideal translational research tool and diagnostic medium and is being used in novel ways to provide molecular biomarkers for a variety of oral and systemic diseases and conditions. The ability to analyze saliva to monitor health and disease is a highly desirable goal for oral health promotion and research. Saliva has been used to detect caries risk, periodontitis, oral cancer, breast cancer, salivary gland diseases, and systemic disorders such as hepatitis, HIV and HCV. Technology advancement has allowed high-throughput studies to be performed at a scale unrealized previously and is serving to advance the discovery and validation of salivary disease biomarkers. Of course, successful measurement of salivary analytes requires optimal collection, processing, and storage procedures and conditions. This chapter describes protocols for saliva collection, processing, and storage for the molecular analysis of salivary diagnostic constituents.

Rap1A and rap1B ras-family proteins are prominently expressed in the nucleus of squamous carcinomas: nuclear translocation of GTP-bound active form

We recently showed that rap1 regulates growth and proliferation in normal keratinocytes, which provoked us to investigate its expression and regulation in malignant cells. Rap1 is variably expressed in whole cell lysates of squamous cell carcinoma (SCC) cell lines. Immunoblot analysis of nuclear and cytosolic fractions and immunohistochemistry revealed that in addition to cytoplasmic expression, SCC cells also exhibit prominent punctate rap1 expression in the nucleus. This unexpected nuclear distribution was confirmed by the evaluation of human oral cancer specimens by immunohistochemistry, which showed both nuclear and cytoplasmic localization. Cytoplasmic rap1 expression was observed mostly in large differentiated cells, whereas nuclear localization was found in morphologically less differentiated cells. Quantitative reverse transcriptase polymerase chain reaction and Northern blot analysis showed that both rap1A and rap1B are expressed in SCC cell lines although rap1B signals are more prominent. Transfection with enhanced GFP-tagged constitutively active and inactive forms of rap1B demonstrated that the active GTP-bound form translocates to the nucleus whereas inactive rap1BGDP is retained in the cytoplasm, much of which is in a perinuclear distribution. Furthermore, growth factors induce nuclear translocation of rap1 in oral cancer cells. This novel discovery that active, GTP-bound rap1 translocates to the nucleus makes it only the second of over 100 small GTP-binding proteins to be identified in the nucleus, and the striking prominence of rap1 expression in the nucleus of SCC cells suggests that activated rap1 plays a role in the malignant process.

Exon-Level Expression Profiling: A Comprehensive Transcriptome Analysis of Oral Fluids

BACKGROUND The application of global gene expression profiling to saliva samples is hampered by the presence of partially fragmented and degraded RNAs that are difficult to amplify and detect with the prevailing technologies. Moreover, the often limited volume of saliva samples is a challenge to quantitative PCR (qPCR) validation of multiple candidates. The aim of this study was to provide proof-of-concept data on the combination of a universal mRNA-amplification method with exon arrays for candidate selection and a multiplex preamplification method for easy validation. METHODS We used a universal mRNA-specific linear-amplification strategy in combination with Affymetrix Exon Arrays to amplify salivary RNA from 18 healthy individuals on the nanogram scale. Multiple selected candidates were preamplified in one multiplex reverse transcription PCR reaction, cleaned up enzymatically, and validated by qPCR. RESULTS We defined a salivary exon core transcriptome (SECT) containing 851 transcripts of genes that have highly similar expression profiles in healthy individuals. A subset of the SECT transcripts was verified by qPCR analysis. Informatics analysis of the SECT revealed several functional clusters and sequence motifs. Sex-specific salivary exon biomarkers were identified and validated in tests with samples from healthy individuals. CONCLUSIONS It is feasible to use samples containing fragmented RNAs to conduct high-resolution expression profiling with coverage of the entire transcriptome and to validate multiple targets from limited amounts of sample.

Galanin Receptor 1 Has Anti-proliferative Effects in Oral Squamous Cell Carcinoma

In the United States, oral cancer accounts for more deaths annually than cervical cancer, leukemias, or Hodgkins lymphoma. Studies have shown that aberrations of chromosome 18q develop with tumor progression and are associated with significantly decreased survival in head and neck cancer patients. The G-protein-coupled receptor, galanin receptor 1 (GALR1), maps to this region of chromosome 18q. Although the role of GALR1 has been well characterized in neuronal cells, little is known regarding this receptor in non-neuronal cells. In this study, the expression, mitogenic function, and signaling mechanism of GALR1 are investigated in normal and malignant oral epithelial cells. mRNA expression was determined via reverse transcriptase-PCR. Protein quantification was done via immunoblot analysis and enzyme-linked immunosorbent assay. For functional and signaling studies, an inhibitory antibody was generated to the N-terminal ligand binding domain of GALR1. GALR1 protein and mRNA expression and GAL secretion were detected at variable levels in immortalized human oral keratinocytes and human oropharyngeal squamous cell carcinoma cell lines. Upon competitive inhibition of GALR1, proliferation was up-regulated in immortalized and malignant keratinocytes. Furthermore, studies with the inhibitory antibody and U0126, the MAPK inhibitor, show that GALR1 inhibits proliferation in immortalized and malignant keratinocytes by inactivating the MAPK pathway. GALR1s inhibitory effects on proliferation in epithelial cells raises the possibility that inactivation or disregulation of this receptor can lead to uncontrolled proliferation and neoplastic transformation.

Rap1 Stabilizes β-Catenin and Enhances β-Catenin–Dependent Transcription and Invasion in Squamous Cell Carcinoma of the Head and Neck

Purpose: In head and neck squamous cell carcinoma (HNSCC) cells, Rap1 shuttles between the nucleus and cytoplasm. Prior findings suggested that Rap1 may modulate the β-catenin–independent Wnt pathway in some settings, but the role of Rap1 in β-catenin–dependent Wnt signaling remains undefined. Experimental Design and Results: We observed that β-catenin bound to active Rap1 in vitro and Rap1 activated β-catenin/T-cell factor (TCF)–dependent transcription. Immunofluorescence studies showed that ectopic expression of Rap1 increased nuclear translocation of β-catenin. Overexpression of active Rap1 facilitated an increase in β-catenin–mediated transcription that was abrogated by dominant-negative TCF4. Conversely, small interfering RNA–mediated inhibition of endogenous Rap1 expression inhibited β-catenin/TCF–mediated transcription as well as invasion of HNSCC. Furthermore, inhibition of Rap1 expression downregulated the expression of matrix metalloproteinase 7, a transcriptional target of β-catenin/TCF. In HNSCC cells stably transfected with β-catenin or treated with lithium chloride or Wnt3A to stabilize endogenous β-catenin, inhibition of Rap1 expression led to decreases in the free pool of β-catenin. Immunohistochemical studies of tissue from HNSCC patients revealed that increased β-catenin intensity correlated with higher tumor stage. Furthermore, the prognostic effect of active Rap1 on tumor N stage was found to depend on cytosolic β-catenin expression (P < 0.013). When β-catenin is high, higher Rap1GTP intensity is associated with more advanced N stage. Conclusions: The findings suggest that Rap1 enhances β-catenin stability and nuclear localization. In addition to indicating that Rap1 has a significant role in regulating β-catenin and β-catenin–dependent progression to more advanced N-stage lesions, these data highlight Rap1 as a potential therapeutic target in HNSCC. Clin Cancer Res; 16(1); 65–76