Abstract
Background: MicroRNA (miRNA) plays a crucial role in initiating and progressing non-small cell lung cancer (NSCLC). Aim: This study aims to investigate the expression and prognostic value of miR-323b-5p in NSCLC patients, and to clarify the mechanisms of miR-323b-5p and IL1A on the proliferation and cell cycle of NSCLC cells. Methods: Differentially expressed miRNAs were screened from the GSE171517 dataset. 120 NSCLC patients and 60 healthy controls were collected. RT-qPCR was used to detect miR-323b-5p and interleukin 1α (IL1A). Prognostic value was analyzed via Kaplan-Meier and Cox regression. Target genes of miR-323b-5p were predicted using TargetScan/miRDB and validated by dual-luciferase assay. Cell proliferation was detected by cell counting kit-8 (CCK-8). Cell cycle was detected by flow cytometry. The expression of cyclin-dependent kinase inhibitor 1 A (P21), cyclin D1 (CCND1) and cyclin dependent kinase 4 (CDK4) was detected by western blot and RT-qPCR. Results: miR-323b-5p was significantly downregulated in NSCLC serum samples and A549, HCC827, and NCI-H1299 cell lines. Low miR-323b-5p correlated with poorer 5-year survival rate and was a prognostic risk factor for NSCLC. IL1A was a direct target of miR-323b-5p. miR-323b-5p mimics can inhibit the proliferation of A549, HCC827, and NCI-H1299 cells, arrest the cell cycle to the S phase, promote P21, and inhibit the expression of CCND1 and CDK4. Overexpression of IL1A can partially reverse the above phenomena. Conclusions: Low levels of miR-323b-5p predict a poor prognosis for NSCLC. miR-323b-5p regulates the cell cycle of NSCLC cells by targeting IL1A, thereby inhibiting cell proliferation.