A novel circular RNA, hsa_circ_0030998 suppresses lung cancer tumorigenesis and Taxol resistance by sponging miR-558.

Circular RNAs (circRNAs) are single-stranded RNAs which form a covalently closed continuous loop. Although originally shown to be non-protein-coding, some circRNAs can give rise to micropeptides. circRNAs have also been shown to play essential regulatory roles in a variety of developmental and disease processes. In a previous study, hsa_circ_0030998 was identified as a circRNA downregulated in lung cancer but its potential implications and mechanisms in lung cancer were not addressed. Here, we showed that overexpressing circ_0030998 decreased proliferation, migration and invasion of lung cancer cells whilst also dampening resistance to Taxol, a classical antitumor drug. Depleting circ_0030998 reversed these phenotypic effects. A high circ_0030998 expression was correlated to a high survival rate in lung cancer patients. Additionally, we found circ_0030998 could downregulate miR-558 expression, serving as a microRNA sponge. In conclusion, our data support that hsa_circ_0030998 can slow down the progression of lung cancer by targeting miR-558 and suppress malignant phenotypes such as proliferation, migration and invasion progression of lung cancer cells. Therefore, we highlight that circ_0030998 could be a novel tumor suppressor of lung cancer.