Tongue cancer and epigenetic factors: An in-vitro study on 298 micro-RNAs

Oral Squamous Cell Carcinoma (OSCC) is the sixth most frequent malignant tumour. There is some evidence that tongue cancer has a higher local failure rate and poorer prognosis than other anatomical sites in the oral cavity. We used tongue squamous cell carcinoma cell lines harbouring mutated p53/p16 as tongue cancer models to study the influences exerted by p53 and p16 genes on the expression of micro RNAs (miRNAs). The study was performed on microarray chips harbouring 298 miRNA sequences. OSCC cell lines used in this study were SCC-4, SCC-15 and SCC-25, all three carrying mutated/hypermethylated p53/p16. The expression values normalized to healthy control of 298 miRNAs were obtained for each cell line. MiRNA 196b was found hyperexpressed in the three cell lines. MiRNAs 19b-1, 21, 27a, 30d, 134, 339, 379 and 465 were found altered in two out of three cell lines. miRNAs found altered in one cell line out of three were: 7b, 23a, 25, 30c, 30e-3p, 107, 125b, 124a, 214, 216, 325 and 384. A literature review for each miRNA found significant was undertaken. Some miRNAs have a well-known role in oral cancer, some have been put in correlation with other cancers/diseases, others are found significant for the first time. These early results in tongue cancer cell lines harbouring mutation of p16/p53 need further analyses to understand whether this variation of miRNA levels are directly influenced by the malfunction of these proteins or if, vice-versa, altered miRNA levels influence the function of p16 and p53.