Circular RNA-AnnexinA7 accelerates cisplatin resistance in non- small cell lung cancer via modulating microRNA-545-3p to mediate Cyclin D1

Objective: To explore the mechanism of circular RNA (circRNA)-AnnexinA7 (ANXA7) in non-small cell lung cancer (NSCLC) cisplatin (DDP) resistance through mi-croRNA (miR)-545-3p to target Cyclin D1 (CCND1). Metk-ods: DDP-resistant and non-resistant NSCLC tissues and normal tissues were collected. DDP-resistant cells (A549/ DDP and H460/DDP) were constructed. circ-ANXA7, miR-545-3p, CCND1, P-Glycoprotein, and glutathione S-transferase-pi in tissues and cells were measured. Anal-ysis of circ-ANXA7 ring structure was performed, as well as detection of circ-ANXA7 distribution in cells. Cell pro-liferation was detected by MTT and colony formation as-say, apoptosis rate was detected by flow cytometry, and cell migration and invasion were evaluated by Transwell assay. The targeting relationship between circ-ANXA7, miR-545-3p and CCND1 was verified. Measurement of tu-mor volume and quality in mice was performed. Results: Circ-ANXA7 and CCND1 were elevated, while miR-545-3p was suppressed in DDP-resistant NSCLC tissues and cells. Circ-ANXA7 combined with miR-545-3p, which targeted CCND1 to expedite A549/DDP cell proliferation, migra-tion, invasion, DDP resistance, but inhibited cell apopto-sis. Conclusion: Circ-ANXA7 enhances DDP resistance in NSCLC via absorbing miR-545-3p to target CCND1 and might be a latent therapeutic target for NSCLC.