MicroRNAs in the development and progression of skin cancer

MicroRNAs are known to regulate the messenger RNA (mRNA) levels and protein expression of multiple genes and their products by binding to the 3′ untranslated region (3′-UTR) of target mRNAs and causing their degradation or inhibiting their translation. Numerous reports have demonstrated the importance of microRNAs in skin biology, with microRNAs regulating multiple processes in the skin in vivo and in skin cells in vitro. Keratinocytes are the predominant cells of the outer layer of skin, the epidermis, and microRNAs have been shown to regulate proliferation, differentiation, apoptosis, senescence, migration/invasion, and morphogenesis of these cells. In addition, microRNAs modulate proteins involved in angiogenesis and genome stability, as well as immune function. Since dysregulation of all of these cellular processes can contribute to the development, progression, and metastasis of cancer, it is perhaps not surprising that recent studies are beginning to show alterations in microRNA profiles in different skin cancers. Thus, differences in various microRNAs have been detected in melanoma and in the nonmelanoma skin cancers, basal and squamous cell carcinoma. In this chapter, we discuss the literature indicating a role of microRNAs in regulating skin structure and function as well as in the development, progression, and metastasis of skin cancer, focusing primarily on the nonmelanoma skin cancers.