ABSTRACT: Saliva (oral fluids) is an emerging biofluid poised for clinical diseases detection. Although the rationale for oral diseases applications (e.g. oral cancer) is clear, the rationale and relationship between systemic diseases and saliva biomarkers are unknown. In this study, we used mouse models of melanoma and non-small cell lung cancer and compared the transcriptome biomarker profiles of tumor-bearing mice to those of control mice. Microarray analysis showed that salivary transcriptomes were significantly altered in tumor-bearing mice vs. controls. Analysis of the transcriptomes in the mouse tumors, serum, salivary glands and saliva revealed that salivary biomarkers have multiple origins. Furthermore, we identified that the expression of two groups of significantly altered transcription factors Runx1, Mlxipl, Trim30 and Egr1, Tbx1, Nr1d1 in melanoma-bearing mice that can potentially be responsible for 82.6% of the up-regulated genes expression and 62.5% of the down-regulated gene expression in the mice saliva, respectively. We also confirmed that the ectopic production of nerve growth factor (NGF) in the melanoma tumor tissue as a tumor-released mediator that can induce expression of the transcription factor Egr-1 in the salivary gland. Taken together, our data support the conclusion that upon systemic disease development, a disease-specific change occurs in the salivary biomarker profile. Although the origins of the disease-specific salivary biomarkers are both systemic and local, stimulation of salivary gland by mediators released from remote tumors play an important role in regulating the salivary surrogate biomarker profiles. Experiment Overall Design: Mice (either C57BL/6 mice or DBA/2 mice) were randomly assigned to control group and tumor group (15 animals per group). Melanoma mice model was induced by subcutaneous (s.c.) injection of B16-F1 cells in 0.1 ml PBS into the lower-right flank of C57BL/6 mice. The lung cancer model was established by s.c. injection of KLN-205 cells in DBA/2 mice. Control animal were injected with PBS alone. Established tumors were observed after 2-3 weeks. Experiment Overall Design: When tumors reached 15 mm in diameter saliva was collected and the mice were sacrificed. Mild anesthesia was induced. Mice saliva was stimulated, obtained and immediately placed in pre-schilled 1.5-ml microcentrifuge tubes. Collection was completed in 20 minutes and samples were stored at -80ºC until analyzed.In addition, Blood was collected in BD Vacutainer tubes containing clot activator (BD Biosciences). Salivary gland and tumor tissue were removed from mice, snap-frozen in liquid nitrogen and stored at -80ºC. Experiment Overall Design: Experiment Overall Design: Salivary,salivary gland, serum or tumor RNA was isolated using the RNeasy Mini Kit (Qiagen) as described previously. There are 15 mice in the control group or tumor group (totally 30 C57BL/6 mice for melanoma mouse model, another 30 DBA/2 mice for lung cancer mouse model). Samples derived from 5 mice in each group were pooled and RNA extracted. The pooling is necessary to ensure sufficient salivary mRNA can be obtained for microarray analyses. Isolated total RNA was treated with recombinant DNase (Ambion, Austin, TX). For microarray analysis, mRNA from mouse saliva, gland or tumor was linearly amplified using the RiboAmp RNA Amplification kit (Molecular Devices, Sunnyvale, CA). After purification, cDNA were in vitro transcribed and biotinylated using GeneChip Expression 3â-Amplification Reagents for in vitro transcription labeling (Affymetrix, Santa Clara, CA). The labeled RNAs was subsequently fragmented, hybridization and scanning.
