• The Role of miRNAs in Early Detection of Oral Cancer

      Almubarak, Hussain Mohammed; Meiller, Timothy F.; Mao, Li, M.D. (2012)
      MicroRNAs, commonly noted as miRNAs (miRs), are evolutionary conserved small non-coding RNAs that negatively regulate gene expression post-transcriptionally. Recently, miRNAs have been identified as potentially important biomarkers in various cancers including oral squamous cell carcinoma. The hypothesis of this study was that the expression of miRNAs is different in squamous cell carcinoma in African Americans as compared to Caucasians; as well as when compared to Age, Sex, Location, Recurrence, Grade of cancer, Stage of cancer, Neural invasion, Muscular invasion, and HPV 16/18 or HPV 31/33/51 status. Fifty cases of oral squamous cell carcinoma were matched to the Maryland Cancer Registry (MCR) database and were selected for one Caucasian and one African American in matched sets for age, sex and location. To detect potentially significant miRNAs, two different epithelial cell lines were selected to represent the normal epithelium (HaCaT and NOK) and compared to the dysplastic epithelium (Leuk-1) and the oral cancer (SCC-9 and SCC-25). The miRNAs profiling was performed for the cell lines and several dysregulated miRNAs were identified. The microarray data were validated by the real-time PCR. The expression of miR-708, miR-193a-5p, miR-155, miR-584, miR-663, and miR-886-5p suggested their significant potential at the early stages of tumorigenesis. However, miR-30d, miR-34a, miR-34c-3p, miR-138, and miR-486-5p were dysregulated only in cancer cell lines reflecting their potential at the late stages. The prominently dysregulated miR-708 and miR-193a-5p were selected for further analysis. The lentiviral transduction targeting miR-708 and miR-193a-5p was used to reverse their originally detected expression levels. Immunoblotting was performed on Survivin, a miR-708's direct target in Renal Cell Carcinoma, and on previously studied biomarkers including Hexokinase II, Beclin 1, and LC3. The expression patterns of the detected miRNAs were matched with microarrays results of the 50 paraffin-embedded tissue samples. Significant difference was found based on race (miR-34c-3p), sex (miR-193a-5p), location (miR-193a-5p & miR-34a), grade (miR-486-5p), and HPV status (miR-584). The survival analysis showed a significant difference based on age, location, and grade. The bioinformatics analysis supported our findings and showed consistent results with other miRNAs studies in the literature. The high expressions of miR-584 and miR-486-5p deserve further investigation.