Circular RNAs in Cancer.

Circular RNAs (circRNAs) constitute a class of RNAs that only recently have come into the focus of the scientific cancer community after it was revealed that they are very abundant, highly conserved across species and show tissue- and developmental stage-specific expression. This tightly regulated, dynamic circRNA expression, in line with expression of messenger RNAs, microRNAs, and long noncoding RNAs, is altered in both solid tumors and hematologic malignancies and most likely contributes to tumorigenesis. In this chapter, we will review cancer-associated and cancer-specific circRNAs, some of which have oncogenic or tumor-suppressive potential. We will specifically focus on circRNAs for which the role in cancer has been studied in more detail, and we will discuss the opportunity to use circRNAs as biomarkers and potential therapeutic targets in cancer.