Knockdown of circRNA_0007534 suppresses the tumorigenesis of cervical cancer via miR-206/GREM1 axis

BACKGROUND: Increasing evidence manifested that circular RNAs (circRNAs) acted as crucial regulators in human cancers by targeting the miRNA/mRNA axis, including cervical cancer (CC). Circ_0007534 was reported to promote CC cell proliferation and invasion by the miR-498/BMI-1 axis. The aim of this study was to explore a novel miRNA/mRNA network underlying circ_0007534 in CC regulation. METHODS: The quantitative real-time polymerase chain reaction (qRT-PCR) was implemented to examine the levels of circ_0007534, miR-206 and Gremlin1 (GREM1). Cell viability was determined using MTT assay. BrdU and colony formation assays were performed for analyzing cell proliferation. Cell apoptosis was assessed by flow cytometry. The protein levels of GREM1 and apoptotic markers (Bcl-2, Bax, C-Caspase3) were measured via western blot. Cell invasion was detected by transwell assay. The target relationship was analyzed by dual-luciferase reporter assay. The impact of circ_0007534 on CC growth in vivo was ascertained by xenograft assay. RESULTS: Circ_0007534 expression was aberrantly increased in CC tissues and cells. Functionally, knockdown of circ_0007534 reduced CC cell growth and invasion but motivated apoptosis. In the mechanism, circ_0007534 targeted miR-206 and its regulatory function was associated with sponging miR-206. Moreover, circ_0007534 was found to regulate GREM1 level by targeting miR-206. The inhibitory effect of si-circ_0007534 on the malignant progression of CC was reversed after GREM1 was overexpressed. Furthermore, circ_0007534 inhibition also reduced tumor growth of CC in vivo partially by regulating miR-206/GREM1 axis. CONCLUSION: These results suggested that knockdown of circ_0007534 promoted the level of miR-206 to induce the expression downregulation of GREM1, consequently inhibiting the progression of CC.