HCV Infection Alters Salivary Gland Histology and Saliva Composition.

Hepatitis C virus (HCV) infection is the most common blood-borne chronic infection in the United States. Chronic lymphocytic sialadenitis and sicca syndrome have been reported in chronic HCV infection. Up to 55% of these patients may have xerostomia; the mechanisms of the xerostomia and salivary gland (SG) hypofunction remain controversial. The objectives of this project are to establish if xerostomia associates with SG and HCV infection and to characterize the structural changes in SG and saliva composition. Eighteen HCV-infected patients with xerostomia were evaluated for SG dysfunction; 6 of these patients (patients 1-6) were further evaluated for SG histopathological changes and changes in saliva composition. The techniques used include clinical and laboratory assessment, SG ultrasonography, histological evaluation, sialochemical and proteomics analysis, and RNA in situ hybridization. All the HCV patients had low saliva flow, chronic sialadenitis, and SG fibrosis and lacked Sjögren syndrome (SS) characteristic autoantibodies. Further evaluation of a subgroup of 6 HCV patients (patients 1-6) demonstrated diffuse lymphocytic infiltrates that are predominantly CD8+ T cells with a significant increase in the number of inflammatory cells. Alcian Blue/periodic acid-Schiff staining showed significant changes in the ratio and intensity of the acinar secretory units of the HCV patients' minor SG. The submandibular glands showed significant ultrasonographic abnormalities in the parenchyma relative to the parotid glands. Significant changes were also observed in the concentration of sodium and mucin 5b. Although no significant correlation was observed between the lymphocytic infiltrates and the years of HCV chronic infection, a positive correlation was observed between HCV RNA-positive epithelial cells and the years of HCV infection. Consistent with the low saliva flow and xerostomia, patients showed changes in several markers of SG acinar and ductal function. Changes in the composition of the saliva suggest that HCV infection can cause xerostomia by mechanisms distinct from SS.

Profiling Autoantibodies against Salivary Proteins in Sicca Conditions.

Salivary gland dysfunction occurs in several autoimmune and immune-related conditions, including Sjögren syndrome (SS); immune checkpoint inhibitor-induced sicca (ICIS) that develops in some cancer patients and is characterized by severe, sudden-onset dry mouth; and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Although subjects with these conditions present with oral dryness and often exhibit inflammatory infiltration of the salivary gland, little is known about the B-cell humoral responses directed against salivary gland protein targets. In this study, autoantibodies were evaluated against Ro52, Ro60, and La, as well as against a panel of 22 proteins derived from the salivary proteome. The tested cohort included healthy volunteers and subjects with SS, ICIS, and APECED without and with sicca. As expected, a high percentage of autoantibody seropositivity was detected against Ro52, Ro60, and La in SS, but only a few ICIS patients were seropositive for these autoantigens. A few APECED subjects also harbored autoantibodies to Ro52 and La, but only Ro60 autoantibodies were weakly associated with a small subset of APECED patients with sicca. Additional testing of the salivary panel failed to detect seropositive autoantibodies against any of the salivary-enriched proteins in the SS and ICIS subjects. However, APECED subjects selectively demonstrated seropositivity against BPI fold containing family A member 1 (BPIFA1), BPI fold containing family A member 2 (BPIFA2)/parotid salivary protein (PSP), and lactoperoxidase, 3 salivary-enriched proteins. Moreover, high levels of serum autoantibodies against BPIFA1 and BPIFA2/PSP occurred in 30% and 67% of the APECED patients with sicca symptoms, respectively, and were associated with an earlier age onset of oral dryness (P = 0.001). These findings highlight the complexity of humoral responses in different sicca diseases and provide new insights and biomarkers for APECED-associated sicca (ClinicalTrials.gov: NCT00001196; NCT00001390; NCT01425892; NCT01386437).

Comparative analysis of the 2016 ACR-EULAR and the 2002 AECG classification criteria for Sjögren's syndrome: Findings from the NIH cohort.

INTRODUCTION: The introduction of new classification criteria for Sjögren's syndrome, known as the 2016 American College of Rheumatology/European League against Rheumatism Classification Criteria (ACR-EULAR), created a need for the evaluation of its performance in an external cohort. The purpose of this study was to compare the performance of the 2016 ACR-EULAR classification set with the widely used American-European Consensus Group Classification criteria (AECG) in the cohort at the National Institutes of Health, USA, and to compare the performance of the sets in classifying both primary and secondary Sjögren's syndrome (pSS and sSS). METHODS: The study cohort at the NIH (N = 1,303) was enrolled for clinical suspicion of SS. Participants were classified as SS, pSS, and sSS according to both classification sets. Performance of 2016 ACR-EULAR and AECG sets was compared holding each as gold standard to the other. Statistical analysis of test diagnostics and agreement between the two sets were undertaken. RESULTS: By the AECG set, 701 were classified as having SS (627 pSS, 74 sSS) and 714 were classified with SS (647 pSS, 67 sSS) by the 2016 ACR-EULAR set. Sensitivity and specificity of the two sets were comparable in classifying SS, pSS, and sSS. There was high agreement between the two sets for classifying SS (κ = 0.79), pSS (κ = 0.81), and sSS (κ = 0.87). The specificity of the 2016 ACR-EULAR set was significantly higher for classifying sSS than pSS, while the sensitivity was similar for the two disease groups. However, this pattern was also exhibited by the AECG set. CONCLUSION: There was high agreement between the two classification sets with comparable performance diagnostics. There was no evidence of superior performance value by the new 2016 ACR-EULAR set over the AECG set, and the two sets were found to be equivalent. Findings from our cohort indicate that 2016 ACR-EULAR classification could be extended to classification of sSS.

miRNA expression profile of mucoepidermoid carcinoma.

OBJECTIVES: MicroRNAs (miRNAs) are single-stranded RNAs that have been implicated in cancer initiation and progression and act as tumour suppressors or oncogenes. In this study, miRNA profiling was conducted on the most frequent malignancy of salivary glands, mucoepidermoid carcinoma (MEC), in comparison with normal tissues. MATERIALS AND METHODS: The TaqMan Human miRNA Cards Array was used for the miRNA profiling of MEC and normal tissues. To validate the differentially expressed miRNAs in MEC, we used real-time PCR (qRT-PCR). RESULTS: miR-302a was the most significantly increased miRNA in cancer tissues (p < .05). Here, we demonstrate that the upregulation of miR-302a expression in SGT cell lines induced cancer cell invasion in vitro. CONCLUSIONS: These promising results suggest the need for further studies to establish mir-302a as a marker of invasion and aggressiveness in MEC.

Neutralizing antibodies against adeno-associated viruses in Sjögren's patients: implications for gene therapy.

One potential setback to the use of gene therapy for the treatment of Sjögren's syndrome is the presence of neutralizing antibodies (nAb) against adeno-associated virus (AAV) serotypes. In order to evaluate the efficacy of this treatment option, nAb titers were measured in both healthy individuals and Sjögren's patients. Several serotypes with known transduction activity in mouse salivary glands were tested and only AAV5 showed a statistically significant change in the prevalence of nAbs between Sjögren's and healthy participants. Both groups showed a higher rate of nAbs for AAV2 compared with most of the other serotypes tested, except for bovine AAV (BAAV). Although a similar rate of seropositivity was seen against BAAV and AAV2, the percentage of samples with high titer was significantly lower with BAAV. Furthermore, the majority of positive samples exhibited low nAb titers in the primary Sjögren's syndrome (pSS) group for all serotypes except for AAV2. AAV5 was the only serotype that showed a statistically significant shift in the percentage of medium or high neutralizing titer. Based on these results, many serotypes are viable vectors in a gene therapy approach and pSS patients do not have a statistically significant higher rate of seropositivity or titer compared with healthy donors.

Elucidating the role of hyposalivation and autoimmunity in oral candidiasis.

INTRODUCTION: Oral candidiasis (OC) is a potential oral complication in Sjögren's syndrome (SS). Some studies indicate that the low stimulated salivary flow and not low unstimulated salivary flow is associated with OC in SS, while others report that the underlying autoimmune disorders contribute to OC, based solely on correlation coefficients. Given the conflicting and limited existing evidence, we purposed to ascertain the role of both salivary gland dysfunction (hyposalivation based on unstimulated and stimulated flow rates) and autoimmunity (SS, other autoimmune disorders) in OC among those with SS, other salivary gland dysfunction, and non-salivary gland dysfunction controls (NSGD). METHODS: A nested case-control study was designed within a larger NIH/NIDCR cohort. Descriptive analyses, nonparametric tests, comparative analyses, and multivariate logistic regression analyses were undertaken. RESULTS: Data on 1526 subjects (701 SS, 247 ISS, 355 Sicca, and 223 NSGD) were obtained from the source cohort of 2046 and analyzed for this study. The median whole unstimulated salivary flow rate (WUS, ml 15 min-1 ) was lower in SS (0.8, interquartile range (IQR) 1.8) compared to ISS (5.5, IQR: 5.2, P < 0.001) and NSGD (3.8, IQR: 3.8, P < 0.001) but comparable with that of Sicca (1.0, IQR: 1.5, P = 0.777) participants. The median total stimulated salivary flow rate (TSS, ml 15 min-1 ) was lowest in SS (7.0, IQR: 12.4, P < 0.001) compared to other groups. Of the 45 OC cases in this cohort, 71.1% (n = 32) were from the SS group. The prevalence of OC was highest in the SS group (4.6%, P = 0.008). SS group had twice the risk of OC than NSGD (OR = 2.2, 95%CI: 1.1-4.2, P = 0.02) and Sicca (OR = 2.2, 95% CI: 1.0-4.8, P = 0.03), adjusting for confounders; hyposalivation [WUS (OR = 5.1, 95%CI: 2.5-10.4, P < 0.001), TSS (OR = 1.9, 95%CI: 1.0-3.5, P = 0.04)], history of other autoimmune disorders (OR = 4.4, 95%CI: 1.7-11.3, P = 0.002), medications for extraglandular manifestations (OR = 2.3, 95%CI: 1.1-4.9, P = 0.03), and diabetes mellitus (4.2, 95%CI: 1.2-15.2, P = 0.02) were independent predictors of OC; females had a lower risk than males (OR = 0.29, 95%CI: 0.13-0.67, P = 0.004). Age, race, anti-SSA/SSB autoantibodies, focus score, other medications, anxiety, fatigue, cigarette smoking, alcohol, and caffeine use were not associated with oral candidiasis. CONCLUSION: Salivary gland dysfunction (hyposalivation with WUS being a stronger predictor than TSS) and autoimmunity (SS, other autoimmune disorders, medications, i.e., DMARDS) are both independent predictors of OC. Diabetes mellitus is an independent predictor of OC among those with salivary gland dysfunction. Our findings suggest that these independent predictors should be considered in the prevention and management of OC in this population.

Late responses to adenoviral-mediated transfer of the aquaporin-1 gene for radiation-induced salivary hypofunction.

We evaluated late effects of AdhAQP1 administration in five subjects in a clinical trial for radiation-induced salivary hypofunction (http://www.clinicaltrials.gov/ct/show/NCT00372320?order=). All were identified as initially responding to human aquaporin-1 (hAQP1) gene transfer. They were followed for 3-4 years after AdhAQP1 delivery to one parotid gland. At intervals we examined salivary flow, xerostomic symptoms, saliva composition, vector presence and efficacy in the targeted gland, clinical laboratory data and adverse events. All displayed marked increases (71-500% above baseline) in parotid flow 3-4.7 years after treatment, with improved symptoms for ~2-3 years. There were some changes in [Na+] and [Cl-] consistent with elevated salivary flow, but no uniform changes in secretion of key parotid proteins. There were no clinically significant adverse events, nor consistent negative changes in laboratory parameters. One subject underwent a core needle biopsy of the targeted parotid gland 3.1 years post treatment and displayed evidence of hAQP1 protein in acinar, but not duct, cell membranes. All subjects responding to hAQP1 gene transfer initially had benefits for much longer times. First-generation adenoviral vectors typically yield transit effects, but these data show beneficial effects can continue years after parotid gland delivery.

Immune reactivity after adenoviral-mediated aquaporin-1 cDNA transfer to human parotid glands.

OBJECTIVES: The purpose of this study was to examine the humoral and cellular immune reactivity to adenoviral vector (AdhAQP1) administration in the human parotid gland over the first 42 days of a clinical gene therapy trial. METHODS: Of eleven treated subjects, five were considered as positive responders (Baum et al, 2012). Herein, we measured serum neutralizing antibody titers, circulating cytotoxic lymphocytes, and lymphocyte proliferation in peripheral blood mononuclear cells. Additionally, after adenoviral vector stimulation of lymphocyte proliferation, we quantified secreted cytokine levels. RESULTS: Responders showed little to modest immune reactivity during the first 42 days following gene transfer. Additionally, baseline serum neutralizing antibody titers to serotype 5-adenovirus generally were not predictive of a subject's response to parotid gland administration of AdhAQP1. Cytokine profiling from activated peripheral blood mononuclear cells could not distinguish responders and non-responders. CONCLUSIONS: The data are the first to describe immune responses after adenoviral vector administration in a human parotid gland. Importantly, we found that modest (2-3 fold) changes in systemic cell-mediated immune reactivity did not preclude positive subject responses to gene transfer. However, changes beyond that level likely impeded the efficacy of gene transfer.

Persistence of hAQP1 expression in human salivary gland cells following AdhAQP1 transduction is associated with a lack of methylation of hCMV promoter.

In 2012, we reported that 5 out of 11 subjects in a clinical trial (NCT00372320) administering AdhAQP1 to radiation-damaged parotid glands showed increased saliva flow rates and decreased symptoms over the initial 42 days. AdhAQP1 is a first-generation, E1-deleted, replication-defective, serotype 5 adenoviral vector encoding human aquaporin-1 (hAQP1). This vector uses the human cytomegalovirus enhancer/promoter (hCMVp). As subject peak responses were at times much longer (7-42 days) than expected, we hypothesized that the hCMVp may not be methylated in human salivary gland cells to the extent previously observed in rodent salivary gland cells. This hypothesis was supported in human salivary gland primary cultures and human salivary gland cell lines after transduction with AdhAQP1. Importantly, hAQP1 maintained its function in those cells. Conversely, when we transduced mouse and rat cell lines in vitro and submandibular glands in vivo with AdhAQP1, the hCMVp was gradually methylated over time and associated with decreased hAQP1 expression and function in vitro and decreased hAQP1 expression in vivo. These data suggest that the hCMVp in AdhAQP1was probably not methylated in transduced human salivary gland cells of responding subjects, resulting in an unexpectedly longer functional expression of hAQP1.

Establishment of functional acinar-like cultures from human salivary glands.

Disorders of human salivary glands resulting from therapeutic radiation treatment for head and neck cancers or from the autoimmune disease Sjögren syndrome (SS) frequently result in the reduction or complete loss of saliva secretion. Such irreversible dysfunction of the salivary glands is due to the impairment of acinar cells, the major glandular cells of protein, salt secretion, and fluid movement. Availability of primary epithelial cells from human salivary gland tissue is critical for studying the underlying mechanisms of these irreversible disorders. We applied 2 culture system techniques on human minor salivary gland epithelial cells (phmSG) and optimized the growth conditions to achieve the maintenance of phmSG in an acinar-like phenotype. These phmSG cells exhibited progenitor cell markers (keratin 5 and nanog) as well as acinar-specific markers-namely, α-amylase, cystatin C, TMEM16A, and NKCC1. Importantly, with an increase of the calcium concentration in the growth medium, these phmSG cells were further promoted to acinar-like cells in vitro, as indicated by an increase in AQP5 expression. In addition, these phmSG cells also demonstrated functional calcium mobilization, formation of epithelial monolayer with high transepithelial electrical resistance (TER), and polarized secretion of α-amylase secretion after ß-adrenergic receptor stimulation. Taken together, suitable growth conditions have been established to isolate and support culture of acinar-like cells from the human salivary gland. These primary epithelial cells can be useful for study of molecular mechanisms involved in regulating the function of acinar cells and in the loss of salivary gland function in patients.

Emerging landscape of non-coding RNAs in oral health and disease.

The world of non-coding RNAs has only recently started being discovered. For the past 40 years, coding genes, mRNA, and proteins have been the center of cellular and molecular biology, and pathologic alterations were attributed to either the aberration of gene sequence or altered promoter activity. It was only after the completion of the human genome sequence that the scientific community started seriously wondering why only a very small portion of the genome corresponded to protein-coding genes. New technologies such as the whole-genome and whole-transcriptome sequencing demonstrated that at least 90% of the genome is actively transcribed. The identification and cataloguing of multiple kinds of non-coding RNA (ncRNA) have exponentially increased, and it is now widely accepted that ncRNAs play major biological roles in cellular physiology, development, metabolism, and are also implicated in a variety of diseases. The aim of this review is to describe the two major classes (long and short forms) of non-coding RNAs and describe their subclasses in terms of function and their relevance and potential in oral diseases.

Gross Cystic Disease Fluid Protein-15(GCDFP-15)/Prolactin-Inducible Protein (PIP) as Functional Salivary Biomarker for Primary Sjögren's Syndrome.

BACKGROUND: Gross cystic disease fluid protein-15(GCDFP-15)/prolactin-inducible protein (PIP) is a secretory acinar glycoprotein of 14 KDa which we have recently described as significantly lower in salivary samples of patients with primary Sjögren's syndrome (pSS) in comparison to healthy volunteers by proteomic analysis. AIMS OF THE STUDY: (1) to validate our previous data on the decrease of GCDFP-15/PIP protein in a larger number of subjects with pSS (2) to integrate the proteomic results with complementary immunoassays in order better clarify the pathophysiological relevance of GCDFP-15/PIP in pSS exocrinopathy (3) to assess both the glandular expression of the GCDFP-15/PIP and the levels of glandular GCDFP-15/PIP mRNA in the patients' minor salivary gland (MSG) biopsies in order to verify whether the observed reduction of GCDFP-15/PIP in saliva may be related to a decrease in the protein production. PATIENTS AND METHODS: A total of 123 salivary samples from patients affected by pSS, no-SS sicca syndrome and sex- age-matched healthy volunteers were analyzed by different proteomic techniques (SELDI-TOF-MS, 2DE, MALDI-TOF-MS). The expression of GCDFP-15/PIP was then validated by western blot analysis. Real Time PCR and immunohistochemistry for GCDFP-15/PIP in the minor salivary glands (MSG) biopsies were then carried out. RESULTS: By using complementary proteomic analysis we found that a putative peak of 16547 m/z was among the best independent biomarkers for pSS able to discriminate between patients and healthy controls with a sensitivity of 96 % and a specificity of 70%, with a global cross validated error of 29%. We identified the peak as the GCDFP-15/PIP protein and verified that the intensity of GCDFP-15/PIP was significantly lower in pSS patients when compared to both no-SS sicca subjects and healthy controls (p<0.0001). GCDFP-15/PIP expression also correlated with both the salivary flow rate (r=0.312, p=0.023) and MSG biopsies focus score (r=-0.377, p=0.04). Finally, immunohistochemistry confirmed that GCDFP-15/PIP staining was faint in mucus acini and Real Time PCR showed that GCDFP-15/PIP mRNA was significantly lower in pSS patients when compared to both no-SS sicca subjects and healthy controls (p=0.023) thus supporting the hypothesis that the observed reduction of GCDFP-15/PIP in pSS saliva may be related to a decrease in the protein production. CONCLUSION: In this study by different complementary-omic techniques we confirmed the potential role of GCDFP-15/PIP as a novel biomarker for pSS. This finding might also be functionally important as GCDFP-15/PIP has previously been shown to bind to Aquaporin 5 (AQP5), a salivary gland water channel, critical to saliva formation that is known to be downregulated in pSS. It is likely that exploring the GCDFP-15/PIP/AQP5 axis will help better understand the mechanism of salivary gland dysfunction in pSS.

Deep sequencing of short RNAs reveals novel microRNAs in minor salivary glands of patients with Sjögren's syndrome.

OBJECTIVES: Sjögren's syndrome is a complex autoimmune disease of the salivary gland with an unknown etiology, so a thorough characterization of the transcriptome would facilitate our understanding of the disease. We use ultradeep sequencing of small RNAs from patients with Sjögren's syndrome and healthy volunteers, primarily to identify and discover novel miRNA sequences that may play a role in the disease. METHODS: Total RNA was isolated from minor salivary glands of healthy volunteers and patients with either high or low salivary flow and sequenced on the SOLiD platform. Prediction of mature miRNAs from the sequenced reads was carried out using miRanalyzer, and expression was validated using Taqman qPCR assays. RESULTS: We validated the presence of six previously unidentified miRNA sequences in patient samples and in several cell lines. One of the validated novel miRNAs shows promise as a biomarker for salivary function. CONCLUSION: Sequencing small RNAs in the salivary gland is largely unprecedented, but here, we show the feasibility of discovering novel miRNAs and disease biomarkers by sequencing the transcriptome.

Microarray analysis of sexually dimorphic gene expression in human minor salivary glands.

OBJECTIVE: We hypothesized that differential mRNA transcription between the sexes may be linked to the 9:1 female-to-male gender-related relative risk for the development of Sjögren's syndrome (SS), an autoimmune disease that leads to inflammation and dysfunction in the lachrymal and salivary glands. SUBJECTS AND METHODS: RNA from minor salivary glands was collected from nine healthy volunteers (four men and five women) and analyzed using the Agilent 4 × 44K human microarray platform. Differential expression was confirmed by qRT-PCR. RESULTS: Comparison of the transcriptome of minor salivary glands from normal male and female volunteers with that of salivary glands and secretory epithelia identified a number of gender, species, and tissue-specific gene expression patterns. These differences include, but are not limited to, a diverse set of genes involved in immune modulation, chemotactic control, inhibition of complement, metabolism, and neurogenesis. CONCLUSION: Analysis of these changes provides insight into the protective and predisposing molecular factors that may be involved in the development of Sjögren's syndrome. Some of the gene changes observed in this study correlate with previously observed sexual dimorphisms in salivary gland function and also illustrate several new targets for further investigation.

Exosomes from human saliva as a source of microRNA biomarkers.

OBJECTIVE: The aim of this study was to examine the presence of microRNAs (miRNAs) within exosomes isolated from human saliva and to optimize and test methods for successful downstream applications. DESIGN: Exosomes isolated from fresh and frozen glandular and whole human saliva were used as a source of miRNAs. The presence of miRNAs was validated with TaqMan quantitative PCR and miRNA microarrays. RESULTS: We successfully isolated exosomes from human saliva from healthy controls and a patient with Sjögren's syndrome. microRNAs extracted from the exosomal fraction were sufficient for quantitative PCR and microarray profiling. CONCLUSIONS: The isolation of miRNAs from easily and non-invasively obtained salivary exosomes with subsequent characterization of the miRNA expression patterns is promising for the development of future biomarkers of the diagnosis and prognosis of various salivary gland pathologies.

Oral graft-versus-host disease.

OBJECTIVE: Graft-versus-host disease (GVHD) is a leading cause of morbidity and mortality in patients receiving hematopoietic cell transplant. It is estimated that 40-70% of engrafted patients surviving the initial transplant eventually develop chronic GVHD (cGVHD), which can persist for months to years and require long-term management from multiple disciplines. This review describes the oral component of this transplant complication. DESIGN: The search related to GVHD patho-biology, salivary gland disease after hematopoietic cell transplant and treatments for oral GVHD encompassed literature from 1966 through 2008. Searches were limited to the MEDLINE/PubMed database and English language literature in peer-reviewed journals. RESULTS: Our understanding of the patho-biology of oral cGVHD is based on studies of other affected tissues. It is difficult to determine the prevalence and incidence of salivary gland disease after transplant because there is no universally accepted case definition. In general, clinical trials for treatment of oral cGVHD have been too small to make strong recommendations for use in clinical practice. CONCLUSIONS: Larger well-designed clinical studies are needed to understand the patho-biology of oral cGVHD and determine best treatments for this disease.

Variant form of STAT4 is associated with primary Sjögren's syndrome.

Single nucleotide polymorphisms in the STAT4 gene have recently been shown to be associated with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Primary Sjögren's syndrome (pSS) is a related autoimmune disease thought to have a pathogenesis similar to these diseases. To test the hypothesis that the variant haplotype of STAT4 seen in RA and SLE is also associated with pSS, we genotyped rs7574865, the most strongly disease-associated SNP in the variant STAT4 haplotype, in 124 Caucasian pSS subjects and compared them to 1143 Caucasian controls. The disease-associated T allele was more common in chromosomes of the pSS patients (29.6%) than in controls (22.3%), leading to a P-value for association of 0.01. These results implicate polymorphisms in the STAT4 gene in the pathogenesis of pSS.

Oral cancer in vivo gene expression profiling assisted by laser capture microdissection and microarray analysis.

Large scale gene expression profiling was carried out on laser capture microdissected (LCM) tumor and normal oral epithelial cells and analysed on high-density oligonucleotide microarrays. About 600 genes were found to be oral cancer associated. These oral cancer associated genes include oncogenes, tumor suppressors, transcription factors, xenobiotic enzymes, metastatic proteins, differentiation markers, and genes that have not been implicated in oral cancer. The database created provides a verifiable global profile of gene expression during oral carcinogenesis, revealing the potential role of known genes as well as genes that have not been previously implicated in oral cancer.

Laser capture microdissection-generated target sample for high-density oligonucleotide array hybridization.

Current advances in biomolecular technology allow precise genetic fingerprinting of specific cells responsible for the pathogenesis of human diseases. This study demonstrates the feasibility of generating target samples from laser capture microdissection (LCM) tissues suitable for hybridization of high-density oligonucleotide arrays for gene expression profiling. RNA was successfully isolated by LCM from three paired specimens of oral cancer and linearly amplified using T7 RNA polymerase. Evaluation of the cDNA revealed that five of five cellular maintenance transcripts are detected. Biotinylated cRNA was generated and hybridized to the human Test 1 GeneChip probe arrays, which demonstrated that the RNA is of sufficient quality and integrity to warrant further analysis. Subsequent hybridization of the samples to the HuGenFL GeneChip probe arrays revealed that 26.5%-33.0% of the approximately 7000 represented genes are expressed in each of the six samples. These results demonstrate that LCM-generated tissues can generate sufficient quality cRNA for high-density oligonucleotide microarray analysis, an important step in determining comprehensive gene expression profiling using this high-throughput technology.