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, while also dampening resistance to Taxol, a classical antitumor drug. Depleting circ_0030998 reversed these phenotypic effects. A high circ_0030998 expression was correlated with 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.