MicroRNA analysis in E6/E7 HPV-transformed human keratinocytes

Introduction: MicroRNAs (miRNAs) are a class of naturally occurring non-coding RNAs that play a key role in gene regulation. MiRNAs exert their regulatory effects through the RNA interference machinery by cleaving the mRNA targets or repressing their translation, and are predicted to regulate at least one third of all human genes. As a result of their action, miRNAs may be directly involved in the development and progression of human diseases, such as cancer, as it is well known that tumor cells bear a specific and altered pattern of miRNA expression. Methods: We perfomed TaqMan MicroRNA Assays for the quantitation of 384 mature miRNAs expression in normal primary keratinocytes (HFK) compared to primary keratinocytes transformed by both E6 and E7 proteins derived from mucosal HPV-16 (K16 cells) or cutaneous HPV-38 (K38 cells). Results: Preliminary results identified 53 miRNAs deregulated in K16 and K38 cells with respect to HFK. Interestingly, it is detectable a strong increase in the expression of 12 miRNAs in K16 and 7 miRNAs in K38, as well as a strong decrease in the expression of 14 miRNAs in K16 and 35 miRNAs in K38 cells. Moreover, 14 miRNAs are up-regulated in K16 but down-regulated in K38 whereas only two miRNAs are down-regulated in K16 but up-regulated in K38 cells. Conclusions: These data suggest that different clusters of miRNA targets may be correlated with different HPV genotypes-induced tumorigenesis. To this respect, the miRNA expression profile of K16 cells appears to be similar to that of HPV-positive cervical cancer cell lines and tissues obtained by other authors. Conversely, major differences in K38 cells miRNA profile have been observed. Studies of miRNA expression in both cells treated with IFN-beta are in progress, since preliminary results have indicated the ability of the antitumoral agent IFN-beta to interfere with E6 and/or E7-induced miRNA deregulation.