MicroRNA profiling in E6/E7 HPV-transformed human keratinocytes

MicroRNAs (miRNAs) are naturally occurring noncoding RNAs that play a key role in gene regulation. They are highly conserved single-stranded RNAs (~22 nucleotides) that are cleaved from larger precursor transcripts. miRNAs exert their regulatory effects by cleaving the mRNA targets or repressing their translation and are predicted to regulate at least one third of all human genes. This posttranscriptional gene regulation has been demonstrated to be active in fundamental cellular processes as cell proliferation, differentiation, and death. miRNAs are also involved in the development and progression of human diseases, such as cancer. Accumulating evidence indicates a role of miRNAs in tumorigenesis and tumor cells bear a specific and altered pattern of miRNA expression. We performed a high throughput screening using a TaqMan MicroRNA assay for the quantitation of 384 miRNAs in normal primary human keratinocytes compared to keratinocytes transformed by both E6 and E7 derived from mucosal HPV-16 or cutaneous HPV-38 (K16 and K38 cells, respectively). Our analysis identified 18 miRNAs mainly deregulated in either K16 and/or K38 cells. Eight deregulated miRNAs (i.e. miR-10a, -18a, -19a, -19b, -34a, -99a, -579 and -590) were further tested using miRNA single assay to confirm the results obtained in the screening. Since IFNβ may interfere with E6 and/or E7-dependent transformation, we characterized the miRNA expression in K16 and K38 cells treated with this cytokine. Studies on the biological significance of interesting specific targets are also in progress.