Exploiting salivary miR-31 as a clinical biomarker of oral squamous cell carcinoma

Background Oral carcinoma is an important malignancy throughout the world. MicroRNAs (miRNAs) are endogenously expressed, non-coding RNAs that regulate post-transcriptional levels of targeted mRNAs. MiRNA-31(miR-31) is significantly upregulated in oral carcinoma tissues and plays oncogenic roles in oral carcinogenesis. Methods. We analyzed the levels of miR-31 in saliva of patients with oral carcinoma (n = 45), oral verrucous leukoplakia (n = 10), and control healthy individuals (n = 24) by quantitative reverse transcriptase-polymerase chain reaction (RTPCR). Results. Salivary miR-31 was significantly increased in patients with oral carcinoma at all clinical stages, including very small tumors. However, our preliminary analysis showed no increase of salivary miR-31 in patients with oral verrucous leukoplakia relative to controls. The miR-31 was more abundant in saliva than in plasma, suggesting salivary miR-31 was a more sensitive marker for oral malignancy. After excision of oral carcinoma, salivary miR-31 was remarkably reduced, indicating that most of the upregulated salivary miR-31 came from tumor tissues. Conclusion. Our results point to a potential application of salivary miR-31 as a biomarker for early detection and postoperative follow-up of oral carcinoma. (C) 2011 Wiley Periodicals, Inc. Head Neck 34: 219-224, 2012