BackgroundCutaneous squamous cell carcinoma (CSCC) is the second most widespread cancer in humans and its incidence is rising. These tumours can evolve as diseases of poor prognosis, and therefore it is important to identify new markers to better predict its clinical evolution.ObjectivesWe aimed to identify the expression pattern of microRNAs (miRNAs or miRs) at different stages of skin cancer progression in a panel of murine skin cancer cell lines. Owing to the increasing importance of miRNAs in the pathogenesis of cancer, we considered the possibility that miRNAs could help to define the prognosis of CSCC and aimed to evaluate the potential use of miR-203 and miR-205 as biomarkers of prognosis in human tumours.MethodsSeventy-nine human primary CSCCs were collected at the University Hospital of Salamanca in Spain. We identified differential miRNA expression patterns at different stages of CSCC progression in a well-established panel of murine skin cancer cell lines, and then selected miR-205 and miR-203 to evaluate their association with the clinical prognosis and evolution of human CSCC.ResultsmiR-205 was expressed in tumours with pathological features recognized as indicators of poor prognosis such as desmoplasia, perineural invasion and infiltrative growth pattern. miR-205 was mainly expressed in undifferentiated areas and in the invasion front, and was associated with both local recurrence and the development of general clinical events of poor evolution. miR-205 expression was an independent variable selected to predict events of poor clinical evolution using the multinomial logistic regression model described in this study. In contrast, miR-203 was mainly expressed in tumours exhibiting the characteristics associated with a good prognosis, was mainly present in well-differentiated zones, and rarely expressed in the invasion front. Therefore, the expression and associations of miR-205 and miR-203 were mostly mutually exclusive. Finally, using a logistic biplot we identified three clusters of patients with differential prognosis based on miR-203 and miR-205 expression, and pathological tumour features.ConclusionsmiR-205 and miR-203 tended to exhibit mutually exclusive expression patterns in human CSCC. This work highlights the utility of miR-205 and miR-203 as prognostic markers in CSCC
