Circular RNA hsa_circRNA_103809 promotes lung cancer progression via facilitating ZNF121-dependent MYC expression by sequestering miR-4302

Lung cancer characterized with malignant cell growth is the leading cause of cancer-related deaths. In recent years, several circular RNAs (circRNAs) have been reported to participate in lung cancer progression. However, the correlation between circular RNA (circRNA) and lung cancer still remains to be further investigated. In this study, we screened out a highly expressed circular RNA hsa_circRNA_103809 in lung cancer tissues. We showed hsa_circRNA_103809 could serve as a prognostic biomarker for patients with lung cancer. Furthermore, we found that hsa_circRNA_103809 knockdown significantly suppressed lung cancer cell proliferation and invasion in vitro and delayed tumor growth in vivo. In mechanism, we identified hsa_circRNA_103809 as a sponge of miR-4302 targeting ZNF121. By sequestering miR-4302, hsa_circRNA_103809 promoted the expression of ZNF121 which consequently enhanced MYC protein level in lung cancer cells. Through rescue assays, we demonstrated hsa_circRNA_103809 contributed to lung cancer cell proliferation and invasion via facilitating ZNF121-dependent MYC expression by sponging miR-4302. In conclusion, our findings illustrated a novel hsa_circRNA_103809/miR-4302/ZNF121/MYC regulatory signaling pathway in lung cancer progression.