Use of non-invasive tissue sampling as an alternative to biopsy and detection of a suitable Oral Squamous Cell Carcinoma (OSCC) biomarker could increase the rate and accuracy of early OSCC diagnosis. Changes in microRNA (miRNA) expression are associated with various cancers. We hypothesised miRNAs could be used as biomarkers for OSCC and that miRNAs could be quantified from oral epithelial scrapings (OES).
Objectives: To detect miRNA in RNA extracts from OES and determine if miRNAs could be used as biomarkers for OSCC.
Methods: RNAs used were human-heart RNA or those extracted from OES or frozen and/or formalin-fixed-paraffin-embedded (FFPE) biopsies using commercial kits. cDNA conversion used miRNA-specific primers or a megaplex primer pool with and without preamplification. Quantitative-reverse-transcription–polymerase-chain-reaction (qRT-PCR) was used to detect miRNAs using Taqman miRNA assays. Cq values were normalized using the Global Mean Normalisation (GMN) Strategy. Archival FFPE tissues of 20 OSCC and 20 histologically normal epithelium (HNE) were compared for relative miRNA quantities using a panel of 11 miRNAs.
Results: Human-heart RNA cDNA conversion using the megaplex primer pool with preamplification gave the most sensitive miRNA detection. miRNAs were detected in RNAs extracted from OES immediately and after 24 hours or 7 days stored in either RNA Protect Saliva reagent or buffer, at room temperature; 24ºC; and 36ºC. miRNAs were extracted from FFPE and pair-matched frozen tissue with the proportion in the FFPE tissue extracts greater than the counterpart frozen tissue extracts. 6 of the 11 miRNAs in the biomarker panel showed significant differential expression in OSCC compared with HNE.
Conclusions: MiRNAs are robust and can be extracted from OES despite differing storage conditions. OES may be an alternative to biopsy of suspect lesions. 6 miRNAs have been shown as potential biomarkers for OSCC.