circ-ZNF609 regulates G1-S progression in Rhabdomyosarcoma

Circular RNAs (circRNAs) represent a class of covalently closed RNAs, derived from a non-canonical splicing event, ubiquitously expressed among Eukaryotes and conserved among different species. We identified a circRNA (circ-ZNF609) involved in the regulation of human primary myoblast proliferation. Upon its depletion, the percentage of proliferating myoblasts was highly reduced. To deepen our knowledge about circ-ZNF609 role in cell cycle regulation, we studied its expression and function in Rhabdomyosarcoma (RMS), a pediatric skeletal muscle malignancy. We found that circ-ZNF609 is up-regulated in biopsies from both the two major RMS subtypes, the alveolar (ARMS) and the embryonal (ERMS), and we discovered that its knock-down blocks proliferation of an ERMS-derived cell line, while it has no effect on ARMS-derived cells. To understand the mechanism through which circ-ZNF609 affects cell proliferation we compared the different effects of circ-ZNF609 depletion in ERMS and ARMS and we identified genes and pathways on which the circRNA acts. Overall design: Total RNA from wild-type human primary myoblasts treated either with a control siRNA (si-SCR) or with a siRNA specific for circ-ZNF609 (si-Circ) was analyzed by RNA-Seq. The experiment was performed in duplicate (4 samples in total). Total RNA from RD cells (Embryonal Rhabdomyosarcoma) and RH4 cells (Alveolar Rhabdomyosarcoma) treated either with a control siRNA (si-SCR) or with a siRNA specific for circ-ZNF609 (si-Circ) was analyzed by RNA-Seq. The experiment was repeated in duplicate (8 samples in total).