Cross-analysis of gene and miRNA genome-wide expression profiles in human fibroblasts at different stages of transformation.

We have developed a cellular system constituted of human telomerase immortalized fibroblasts that gradually underwent neoplastic transformation during propagation in culture. We exploited this cellular system to in- vestigate gene and miRNA transcriptional programs in cells at different stages of propagation, representing five different phases along the road to transformation, from non-transformed cells up to tumorigenic and metastatic ones. Here we show that gene and miRNA expression profiles were both able to divide cells according to their transformation phase. We identified more than 1,700 genes whose expression was highly modulated in cells at at least one propagation stage and we found that the number of modulated genes progressively increased at successive stages of transformation. These genes identified processes significantly deregulated in tumorigenic cells, such as cell differentiation, cell movement and extracellular matrix remodeling, cell cycle and apoptosis, together with upregulation of several cancer testis antigens. Alterations in cell cycle, apoptosis, and cancer testis antigen expression were particular hallmarks of metastatic cells. A parallel deregulation of a panel of 43 miRNAs strictly connected to the p53 and c-Myc pathways and with oncogenic/oncosuppressive functions was also found. Our results indicate that cen3tel cells can be a useful model for human fibroblast neoplastic transfor- mation, which appears characterized by complex and peculiar alterations involving both genetic and epige- netic reprogramming, whose elucidation could provide useful insights into regulatory networks underlying cancerogenesis.