MicroRNAs and photocarcinogenesis.

As a new class of sequence-specific regulators of gene expression, the microRNAs (miRNA) form a regulatory network with growth factors and transcription factors participating in various biological processes. It is now being recognized that the various key processes involved in cancer induction are under the control of these small noncoding RNAs, which regulate ~30% of all human genes by targeting sequences in their 3'-untranslated regions. Photocarcinogenesis is a complex interplay of signaling events in the UV exposed human skin including DNA damage and repair, apoptosis, cell survival, mutations and the immune system. In this review, we have scrutinized the role of miRNAs in skin cancer biology focusing on the three most common types of skin cancer namely the basal cell carcinoma, squamous cell carcinoma and cutaneous malignant melanoma. An overview of these studies will be useful in gaining insights into the mechanisms of cancer development in the human skin. A better understanding of the functionality of miRNAs will have enormous implications to risk assessment, and to target interventions against signaling events involved in photocarcinogenesis.