Upregulated Circular RNAs in Gastric Cancer: Target Identification and Tools for Therapeutic Intervention.

Surveying the literature (PubMed), we have identified upregulated circular RNAs involved in pathogenesis and dissemination of gastric cancer. We have focused on circRNAs that upregulate the following target classes or physiological processes: transmembrane receptors, secreted proteins, RNA metabolism and processing, ubiquitination, WNT signalling, ferroptosis and druggable enzymes. Circular RNAs upregulating targets for approved drugs in GC, such as vascular endothelial growth factor A (VEGF-A) and programmed death-ligand 1 (PD-L1), were identified, validating circRNAs as tools for target identification. We highlight targets and target classes that are frequently affected by circRNAs such as solute carrier (SLC) proteins, subtypes of heterogeneous nuclear RNA (hnRNA), ubiquitin-specific proteases (USPs) and targets related to inhibition of ferroptosis. We also highlight druggable enzymes as targets. We discuss technical issues for inhibition of the identified targets and their corresponding circular RNAs.