Characterization of RNA in saliva

Area of Science:

• Molecular Biology
• Biochemistry
• Oral Biology

Background:

• Human messenger RNAs (mRNAs) are detectable in saliva.
• Salivary mRNA holds potential as biomarkers for oral cancer detection.

Purpose of the Study:

• To analyze the integrity, origins, and stability of RNA found in saliva.
• To investigate factors influencing salivary RNA degradation and protection.

Main Methods:

• RNA integrity was assessed using reverse transcription followed by PCR (RT-PCR) and RT-quantitative PCR (RT-qPCR).
• RNA sources were identified by analyzing samples from salivary glands, gingival crevices, and oral epithelial cells.
• RNA stability was measured by incubating salivary RNA at room temperature and assessing degradation over time.
• RNA association with macromolecules was studied using filtration and Triton X-100 treatment.

Main Results:

• Partial- to full-length mRNAs were detected in saliva, with varying amplicon lengths.
• RNA was present in all examined oral fluid samples.
• Endogenous salivary beta-actin mRNA exhibited significantly slower degradation (half-life 12.2 min) compared to exogenous mRNA (0.4 min).
• Salivary RNA could not pass through 0.22 or 0.45 micrometer pores, indicating association with larger molecules.
• Triton X-100 treatment accelerated salivary RNA degradation.

Conclusions:

• Saliva contains both intact and degraded mRNA molecules.
• RNA originates from multiple sites within the oral cavity.
• Association with macromolecules in saliva appears to protect RNA from degradation.